MS Research in past, present and future What`s in it for patients?
Transcription
MS Research in past, present and future What`s in it for patients?
program MS Research Days 2015 May 28 - 29, 2015 • CORPUS, Oegstgeest MS Research in past, present and future What’s in it for patients? content Welcome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Short program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Instructions speed dates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Complete program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Keynote Speakers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Abstracts sessions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Poster overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 Abstracts posters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 1 A warm welcome On behalf of all colleagues involved with our foundation I’d like to wish you a very warm welcome at the MS Research Days 2015. This time a special touch is added by the start of the Foundation’s 35th anniversary. Together with you, we are looking forward to an inspiring program; last year results will be shared and future views will be discussed. Also there will be great keynote speakers, surprising presentations, debates, guest speakers, speed dating sessions and much more. We hope that these MS Research Days will fulfill your expectations. Afterwards we are looking forward to your feedback, so in 2016, we can serve you and the research to MS even better. Special thanks to Jeroen Geurts, Jan Meilof and Annette van der Goes, who have made many extra efforts to compose these days. And of course our thanks as well to all others who have contributed to the establishment of these days. Dorinda Roos CEO Dutch MS Research Foundation 2 Introduction Dear colleagues, A warm welcome to the MS Research Days 2015! As the Dutch MS Research Foundation celebrates its 35th anniversary, we focus this year on past, present and future MS research and more particularly on what patients have gained by 35 years of research. Undeniably, we have learned a lot about MS as a disease in recent decades. Different abnormalities in white and grey matter have been characterized and MS is no longer considered a ‘typical white matter disease’. Various hypotheses concerning its origin circulate and are currently under study. Also, major steps have been made in making a diagnosis early in the course of the disease. And finally, in the past 20 years, the choice and number of therapies has been importantly increased. In short, we have seen, and are still seeing, tremendous progress in the field. And that makes MS research both fascinating and rewarding. We hope that the program for the MS Research Days 2015 will give new impetus to MS research. It contains three keynote lectures, nine scientific sessions and a hot topic session. We are fortunate that nine principal investigators were willing to chair a session; they proposed the line-up of researchers within their own session. As a fixed element, presenters have been asked to end their presentation with a statement regarding the significance of their work for other researchers and especially for patients with MS. The special Hot Topic session will focus on cognition in MS: from molecules and images towards cognitive interventions. In the first keynote lecture you will be taken on a short journey through time across the main results in MS research from the past 35 years. The second keynote, on Friday morning, will point out current and upcoming treatment options for people with MS and especially new research opportunities associated with these treatments. The third keynote will illustrate the dynamics of science policy discussions in the Netherlands and will explore opportunities for young researchers looking for a career in science in the (near) future. We all know why MS research is necessary. However, to provide you with a sense of what MS actually means for people experiencing the disease, we would like to draw your attention to Dit is mijn leven, a film presented on Thursday afternoon. Two new parts of the program are the MS-interactief and the MS speed dates. We hope that these new ways of discussing research will spark new insights and promote new collaborations within the MS research field. MS research in past, present and future. What’s in it for patients? On behalf of the Scientific Advisory Board of the Dutch MS Research Foundation, we wish you enlightening Research Days. Jeroen Geurts and Jan Meilof, Scientific Committee MS Research Days 3 Location Corpus, Oegstgeest Directions by car CORPUS is located on the A44 motorway in Oegstgeest. Our address is Willem Einthoven straat 1, 2342 BH Oegstgeest. However, the Willem Einthovenstraat is not recognized by all navigation systems. If your system does not recognize this street, use the following address: Ingenieur G. Tjalmaweg, Leiden. When you arrive here, you will already be able to see the CORPUS building. From the A44 coming from Amsterdam Exit for Leiden, nr 8. At the traffic lights turn right towards Katwijk. Then take the first road for CORPUS. From the A44 coming from The Hague/Wassenaar Exit for Leiden, nr 8. At the traffic lights turn left towards Katwijk. Go under the viaduct and straight on. The first road immediately after the crossroads is for CORPUS. From the N11 coming from Utrecht/Bodegraven Take the A4 heading towards The Hague. Take the first exit on the A4 for Leiden/Zoeterwoude (exit nr 7). Drive towards Leiden via the N206 heading to Katwijk. After about 3.5 km go under the viaduct of the A44 and straight on. The first road immediately after the crossroads is for CORPUS. 4 Location Directions by public transport CORPUS is located on the A44 motorway in Oegstgeest. Our address is Willem Einthovenstraat 1, 2342 BH Oegstgeest. CORPUS is easy to reach by public transport. Below you will find some suggested routes. From Leiden CS, option 1 From the south side of the Central Station (bus station and centre) you can take bus 38 or 33 (for Katwijk ZH) or bus 35 (for Katwijk ZH). Get off at the Transferium A44. This bus stop is located in the Ingenieur G. Tjalmaweg. From here, it is approximately a 7 minute walk to CORPUS. From the bus stop, follow the bicycle signs which show the route of the path (red dotted line on the map) which runs alongside the A44 motorway towards the CORPUS building which is located along this motorway. From Leiden CS, option 2 From the north side of the Central Station (LUMC stop), you can take bus 57 (for Lisse/ Hoofddorp). Get off at the stop for CORPUS, which is located at the end of the Wassenaarseweg before it becomes the Endegeesterstraatweg after the bend to the right. From the stop for CORPUS, you walk under the viaduct of the A44 to the CORPUS building. From Leiden CS, option 3 From the south side of the Central Station (bus station and centre) you can take bus 43 (for The Hague). Get off at the stop for Universiteitsterrein (university campus) and take the Einsteinweg in the direction of the A44. At the end of the Einsteinweg, turn right into the Niels Borhweg and continue until you reach the Wassenaarseweg. Then turn left and walk under the viaduct of the A44 to the CORPUS building. From The Hague CS From the Central Station bus platform, you can take the Qliner 386 (for Oegstgeest) or Qliner 385 (for Noordwijk). Get off at theTransferium A44. This bus stop is located in the Ingenieur G. Tjalmaweg. From here, it is approximately a 7 minute walk to CORPUS. From the bus stop, follow the bicycle signs which show the route of the path which runs alongside the A44 motorway towards the CORPUS building which is located along this motorway. From Oegstgeest Take bus 57 for Leiden and get off at the stop for CORPUS. From this stop, you walk under the viaduct of the A44 to the CORPUS building. 5 Short program MS Research Days 2015 MS research in past, present and future. What’s in it for patients? Corpus, Oegstgeest, Conference room Hosts prof.dr. Jeroen Geurts and dr. Jan Meilof Thursday, 28 May 2015 Time 09.00 Registration and Coffee 09.30 Opening prof.dr. Jeroen Geurts en dr. Jan Meilof 09.35 Keynote 1 prof.dr. Frederik Barkhof 35 years of MS research 10.20 Session 1 What drives the T- and B-cells in the CNS? Chair: prof.dr. Rogier Hintzen 11.05 11.30 Break MSinteractief 12.30 Lunch and poster viewing 13.30 Speed dates Speed dates for PhD students and post-docs Chair: dr. Wia Baron 14.15 Session 2 From microglia to lymphocyte Chair: prof.dr. Jon Laman 15.00 Session 3 Microglia: how the brain talks back to the immune system Chair: dr. Jeffrey Bajramovic 15.45 MS-biopic Tessa Dit is mijn leven 16.00 6 Toekomst van MS-onderzoek Moderator: Peter van der Geer Break 16.15 Session 4* Inflammation at the barriers of the central nervous system in MS Chair: prof.dr. Elga de Vries 17.00 Session 5* Progressive MS Alliance Chair: Ceri Angood Napier 18.00 Drinks 19.00 Dinner 22.30 End *session in Breakout room Short program MS Research Days 2015 Friday, 29 May 2015 08.30 Welcome and coffee 09.00 Session 6 Remyelination in MS: from basic science to therapy? Chair: dr. Wia Baron 09.45 Keynote 2 dr. Joep Killestein Therapies now and in the future 10.30 Break 11.00 Session 7 Imaging Chair: dr.ir. Hugo Vrenken 11.45 Hot topic Cognition in MS: from molecules and imaging towards cognitive interventions Chair: prof.dr. Jeroen Geurts 12.15 Lunch 12.45 Session 8 Latest insights from UHasselt Chair: prof.dr. Jack van Horssen 13.30 Session 9 Grey Matter tissue in MS Chair: dr. Inge Huitinga 14.15 Keynote 3 dr. Barend van der Meulen Future science and opportunities for PhD students 15.00 MS-overseas dr. Tessel Runia Travel grant 15.15 Speed dates Presentations of the nominees 15.45 Awards and closing 16.00 End 7 Instructions for MS speed date session The speed dates are meant for young MS researchers (PhD students and post-docs) to stimulate the collaborations between the different institutes and within the different disciplines. Every participant has three speed dates and will write a short research proposal with the best match speed date partner. Only PhD students and post-docs that are present on both the Thursday and the Friday can take part. Program Thursday 1.30 – 2.15 pm: Speed dates Wia Baron will give a short introduction. Subsequently, every participant has 3 speed dates of each 10 minutes. After 10 minutes the horn will give the signal that you can go to your next speed date. Together with your speed date partner you will discuss which research you are doing and whether you can come up with a joint research proposal. Thursday until Friday 9 am: write research proposal With the speed date partner you have the best match, you will write a short research proposal. For this you use the MS-speed date form, that you can fill in with pen. Remember to hand in your proposal by 9 am on Friday morning in the box at the registration desk (one copy). Friday 12.15 pm: announcement nominees Nominated 3 speed date couples will be announced. Friday 3.15 pm: presentations nominees The 3 nominated speed date couples will have 5 minutes per couple to present their research proposal (elevator pitch, no slides, flip-over is available). Friday 3.30: award ceremony The speed date couple with the best research proposal and presentation will be rewarded with a gift voucher of 150 euro per person. Guidelines - Only one research proposal per person; - A multidisciplinary approach is preferred; - Feasibility should be taken into account. The jury consists of - Wia Baron (chair) - Jeffrey Bajramovic - Anne-Marie van Dam 8 Complete program MS Research Days 2015 MS research in past, present and future. What’s in it for patients? Corpus, Oegstgeest, Conference room Hosts prof.dr. Jeroen Geurts and dr. Jan Meilof Thursday, 28 May 2015 Time 09.00 Registration and Coffee 09.30 Opening prof.dr. Jeroen Geurts en dr. Jan Meilof 09.35 Keynote 1 p14 35 years of MS research prof.dr. Frederik Barkhof 10.20 Session 1 p17 What drives the T- and B-cells in the CNS? Chair: prof.dr. Rogier Hintzen Identification of novel mechanisms controlling peripheral T-cell activation in MS Marvin van Luijn (ErasMS) Local T-cell responses in MS Gijsbert van Nierop (ErasMS) 11.05 Break 11.30 MS-interactief## Toekomst van MS-onderzoek Moderator: Peter van der Geer Thema’s: 1. Is MS een immunologisch of neurodegeneratief probleem? 2. Patiënten moeten kunnen mee beslissen over het onderzoek dat gefinancierd wordt? 3. Is RRMS een controleerbare ziekte? 4. Thema n.a.v. een peiling onder de deelnemers 12.30 Poster overview from p57 Lunch and poster viewing 13.30 Speed dates Speed dates for PhD students and post-docs Peter van der Geer, gespreksleider (Debat.nl) Marc van Bijsterveldt, wetenschapsjournalist ## 9 Complete program MS Research Days 2015 14.15 Session 2 p20 From microglia to lymphocyte Chair: prof.dr. Jon Laman Peripheral inflammation alters microglia function Bart Eggen (UMCG) The later stages of mouse EAE, a role for microglia Ilia Vainchtein (UMCG) Dichotomous outcome of IL-7 receptor (CD127) blockade in non-human primate experimental autoimmune encephalomyelitis Jordon Dunham (EMC) 15.00 Session 3 p24 Microglia: how the brain talks back to the immune system Chair: dr. Jeffrey Bajramovic Genome-wide approaches to study (micro) glia in health and disease: 1) Glia Open Access Database (GOAD; www.goad.education) and 2) a co-expression meta-analysis of primed microglia Inge Holtman (UMCG) Innate immune activation in macrophages and microglia Saskia Burm (BPRC) Microglia show an intermediate activation status in early lesion formationin multiple sclerosis Laura Peferoen (VUmc) 15.45 MS-biopic 16.00 16.15 Dit is mijn leven Tessa Break Session 4* p28 Inflammation at the barriers of the central nervous system in MS Chair: prof.dr. Elga de Vries The role of the choroid plexus in MS Gijs Kooij (VUmc) Relation between LXR activation and blood-brain barrier function during neuroinflammation in multiple sclerosis Jasmine Vanmol (UHasselt) Molecular regulation of the blood-brain barrier phenotype Claudio Derada Troletti (VUmc) 10 *session in Breakout room Complete program MS Research Days 2015 17.00 Session 5* p32 Progressive MS Alliance Chair: Ceri Angood Napier (MSIF, UK) Immune-primed microglia: a factor underlying progressive multiple sclerosis Sandra Amor (VUmc) Inflammation drives mitochondrial dysfunction and associated neurodegeneration in multiple sclerosis Philip Nijland (VUmc) Discovery of biomarkers reflecting progression pathophysiology for primary progressive MS subtype by applying next generation sequencing and novel multiplex aptamer approach Arjan Malekzadeh (VUmc) Towards a shared data repository to enhance the standards of rehabilitation in MS: feasibility, capacity building and proof-ofconcept on exercise therapy & mobility measures Peter Feys (UHasselt) 18.00 Drinks 19.00 Dinner An award ceremony and a special cabaret act will be part of the program. The evening will be musically entertained by “A night like this”. Besides participants of the MS Research Days 2015, the Scientific Advisory Board, Board members and colleagues of the Dutch MS Research Foundation, people with MS, donors and many others will be present. 11 Complete program MS Research Days 2015 friday, 29 May 2015 08.30 09.00 Welcome and coffee Session 6 p36 Remyelination in MS: from basic science to therapy? Chair: dr. Wia Baron Nrf2 activators: a novel strategy to promote oligodendrocyte survival in multiple sclerosis? Jamie Lim (VUmc) Distinct modulation of myelination efficiency by cortical and non-cortical astrocytes Inge Werkman (UMCG) Functionality of human induced pluripotent stem cell-derived oligodendrocytes in an MS primate model Arun Thiruvalluvan (UMCG) 09.45 Keynote 2 p15 Therapies now and in the future dr. Joep Killestein Session 7 p41 Imaging Chair: dr.ir. Hugo Vrenken 10.30 11.00 Break Understanding the relation of gray matter atrophy patterns in multiple sclerosis with other MS pathology Martijn Steenwijk (VUmc) Timing of retinal neuronal and axonal loss in MS; a longitudinal OCT study Lisanne Balk (VUmc) Longitudinal monitoring of microglia activation and CNS myelin with [11C]PK11195 and [11C]MEDAS PET imaging in the cuprizone mouse model for Multiple Sclerosis Ate Boerema (UMCG) 11.45 Hot topic p53 Cognition in MS: from molecules and imaging towards cognitive interventions Chair: prof.dr. Jeroen Geurts Understanding cognitive impairment in MS – brain imaging and histopathology Menno Schoonheim (VUmc) & Geert Schenk (VUmc) Treating cognitive impairment in MS – how to move forward? Neeltje Kant (Nieuw Unicum) & Hanneke Hulst (VUmc) 12.15 12 Lunch Complete program MS Research Days 2015 12.45 Session 8 p47 Latest insights from UHasselt Chair: prof.dr. Jack van Horssen Disturbed skeletal muscle cell biochemistry and composition in multiple sclerosis Inez Wens (UHasselt) Does CMV trigger CD4+CD28null T-cell expansion in the context of MS? Marjan Vanheusden (UHasselt) The role of LXRb in neuroinflammation Tim Vanmierlo (UHasselt) 13.30 Session 9 p50 Grey Matter tissue in MS Chair: dr. Inge Huitinga Experimental demyelination causes neuronal hyperexcitability Maarten Kole (NIN) Complement C1q-C3 associated synaptic changes in multiple sclerosis hippocampus Valeria Ramaglia (NIN) 14.15 Keynote 3 p16 Future science and opportunities for PhD students dr. Barend van der Meulen (Rathenau Instituut) 15.00 MS-overseas Travel grant dr. Tessel Runia 15.15 Speed dates Presentations of the nominees 15.45 Awards and closing 13 Keynote 1 Frederik Barkhof Frederik Barkhof received his MD from VU University, Amsterdam, the Netherlands in 1988 and defended his PhD thesis in 1992, for which he received the Philips Prize for Radiology in 1992 and the Lucien Appel Prize for Neuroradiology in 1994. Since 2001 he serves as a full Professor in Neuroradiology at the department of Radiology & Nuclear Medicine at the VU University Medical Center (VUmc). He is a senior staff member of the MS Center Amsterdam, and senior consultant of the Alzheimer Center, VUmc. He is the Scientific Director of the Image Analysis Centre (IAC), involved in analysis of multicentre drug trials. Prof. Barkhof was the chairman of the Dutch Society of Neuroradiology and the MAGNIMS study group for many years. He serves on the Editorial boards of Radiology, Brain, European Radiology (section editor for Neuroradiology), Multiple Sclerosis Journal, Neuroradiology and Neurology. Prof. Barkhof’s research interests focus on childhood white matter disease, on multiple sclerosis (spinal cord MRI, grey matter, atrophy, histopathology correlations), on ageing (white matter lesions and microbleeds) and dementia (hippocampal atrophy in Alzheimer and functional MR). He (co)authored >750 papers referenced in PubMed, has an H-factor of 86 and is author of the books “Neuroimaging in Dementia” and “Clinical applications of functional brain MRI”. Cumulatively, he has received >10 million euro grant money from various national and international funding agencies and performed contract research for all major pharmaceutical companies with cumulative contract value of > 15 million euro. More than 30 PhD students graduated under his supervision and 2 of them have subsequently attained a full professorship. In his keynote lecture at the MS Research Days, he will take you on a short journey through time along the main MS results in MS research from the past 35 years. During this period the diagnosis of MS has been revolutionized by the advent of MRI while many new treatments have been introduced that are increasingly effective. Some selected publications 1. Barkhof F, Ciccarelli O. Daclizumab in multiple sclerosis: a high-yield extension study. Lancet Neurol. 2014 May;13(5):443-4. 2. Barkhof, F. & Wattjes, M.P. (2013). Multiple sclerosis: CCSVI deconstructed and discarded. Nature Reviews Neurology, 9, 661-662. 3. Barkhof F, Calabresi PA, Miller DH, Reingold SC. Imaging outcomes for neuroprotection and repair in multiple sclerosis trials. Nat Rev Neurol. 2009 May;5(5):256-66 4. Geurts JJ, Barkhof F. Grey matter pathology in multiple sclerosis. Lancet Neurol. 2008;7(9):841-51 5. Jasperse B, Vrenken H, Sanz-Arigita E, de Groot V, Smith SM, Polman CH, Barkhof F. Regional brain atrophy development is related to specific aspects of clinical dysfunction in multiple sclerosis. Neuroimage. 2007 Nov 15;38(3):529-37 14 Keynote 2 Joep Killestein Joep Killestein, MD, PhD, is a Staff Neurologist at Vrije Universiteit University Medical Centre and the MS Centre Amsterdam since 2006. He completed his PhD training on T-cell functions in treated and untreated MS patients in 2002. The main focus of his current research is on the correlation between biomarkers and response to disease modifying therapies in MS, e.g. the response to interferon-beta (IFNb), fingolimod and natalizumab, including immunogenicity issues. Another important domain of his work comprises complications of therapy like natalizumab-associated progressive multifocal leukoencephalopathy (PML). He has been involved in several clinical trials in Multiple Sclerosis, including those testing safety and efficacy of IFNb, T and B cell depletion, natalizumab, cladribine, dimethylfumarate, laquinimod, fingolimod, vitamin D and cannabinoids. Dr Killestein is a member of the European Committee for Treatment and Research in MS (ECTRIMS) council, the Medical Ethics Review Committee of VUmc, company advisory boards, trial steering committees and adjudication committees. He is program leader of the research program ‘Neuroinflammation’ of the Neuroscience Campus Amsterdam. A member of the CBO committee which developed treatment guidelines for MS in the Netherlands and a board member of the MS taskforce of the Netherlands Society of Neurology. In his keynote lecture at the MS Research Days he will talk about the current and upcoming treatment options for people with MS, hopes and hazards. He will focus especially on new research opportunities associated with response to these treatments, personalized medicine and pharmacovigilance. Some selected publications 1. Vennegoor A, van Rossum JA, Polman CH, Wattjes MP, Killestein J. Longitudinal JCV serology in multiple sclerosis patients preceding natalizumab-associated progressive multifocal leukoencephalopathy. Mult Scler. 2015 [Epub ahead of print] 2. van Oosten BW, Killestein J, Barkhof F, Polman CH, Wattjes MP. PML in a patient treated with dimethyl fumarate from a compounding pharmacy. N Engl J Med. 2013 Apr 25;368(17):1658-9. 3. Vennegoor A, Rispens T, Strijbis EM, Seewann A, Uitdehaag BM, Balk LJ, Barkhof F, Polman CH, Wolbink G, Killestein J. Clinical relevance of serum natalizumab concentration and anti-natalizumab antibodies in multiple sclerosis. Mult Scler. 2013 Apr;19(5):593-600. 4. Killestein J, Rudick RA, Polman CH.Oral treatment for multiple sclerosis. Lancet Neurol. 2011 Nov;10(11):1026-34. 5. Killestein J, Polman CH. Determinants of interferon b efficacy in patients with multiple sclerosis. Nat Rev Neurol. 2011 Apr;7(4):221-8. 15 Keynote 3 Barend van der Meulen Barend van der Meulen is head of the dept Science System Assessment of the Rathenau Instituut. The Rathenau Instituut is an institute of the Netherlands Royal Academy of Arts and Sciences (KNAW), with a mission to support policy making and public debate on issues of science and technology. Barend van der Meulen has a long time experience in science policy studies on the interaction between policy making and the dynamics of the research system, on science policy instruments, dynamics of research organisations and evaluation of research. In his key note he will assess the issue of the future PhD education at universities, given the changes in labour markets for higher educated and development of academic careers. He will assess such issues against the backdrop of scenarios for the Dutch universities and the national research system more general. These scenarios are a result of a joint project of Rathenau Instituut and the Association of Dutch Universities. Universities are facing three key uncertainties for future strategies. First of all whether scientific knowledge is considered a private or a public good. Second, whether critically resources are rather certain or have to be earned on a (hyper)competitive market and thirdly, what the geographical space is in which they operate. Strategic options are different for each of the scenario’s. Some selected publications 1. Vizier Vooruit, 4 toekomstscenario’s voor Nederlandse universiteiten. Rathenau Instituut 2013 2. Talent Centraal, Ontwikkeling en selectie van wetenschappers in Nederland. Rathenau Instituut 2013 3. Valuable-indicators for valoriation. Rathenau Instituut 2013 16 Session 1 What drives the T- and B-cells in the CNS? Chair: prof.dr. Rogier Q. Hintzen Department of Neurology, MS Center ErasMS, Erasmus MC, Rotterdam, The Netherlands Abstract We are currently in the peculiar situation that the only medications that work in MS are drugs that interact with activated T and B cells. But what we don’t know is what signals are responsible for activation of these adaptive immune cells in MS. This may be due to direct recognition of auto antigens or via infection induced bystander effects, super antigens or mimicry. Evidence will be discussed as to why research on the background of the antigen specific stimulation deserves more attention. Marvin van Luijn Identification of novel mechanisms controlling peripheral T-cell activation in MS Authors Marvin M. van Luijn1, Liza Rijvers1, Roos M. van der Vuurst-de Vries2, Jeanet Hogervorst1, Malou Janssen2, Annet F. Wierenga-Wolf1, Marie-José Melief1, Jon D. Laman2 and Rogier Q. Hintzen2 Affiliation 1Department of Immunology, MS Center ErasMS, Erasmus MC, Rotterdam 2 Department of Neurology, MS Center ErasMS, Erasmus MC, Rotterdam Abstract BACKGROUND+OBJECTIVE: A central dogma in MS pathogenesis is that autoreactive T cells are activated in the periphery to mediate inflammatory events in the CNS. Although HLA, non-HLA genetic risk factors and EBV are considered to play critical roles in T-cell activation, exact underlying mechanisms remain poorly understood. We see a central role for the B-cell as a key antigen presenting cell in MS pathogenesis. Our aim is to specify if and how some novel genetic MS risk factors functionally link to the interactive pathways between antigen-presentation (APC) and T-cell activation. Some main topics: 1) genetic influence on HLA-II antigen presentation (with a specific focus on B cells), 2) EBV and B-cell immune escape, and 3) functional phenotyping of B- and T-cell subsets during MS disease course, and the association with MS risk alleles. METHODS: Novel genes coming from MS genome-wide association studies show direct links to the function of the major MS genetic factor, HLA-II. We use different human APC models (i.e. melanoma cells, primary monocyte-derived dendritic cells and B cells) to silence these genes and assess their role in HLA-II biology using RNAi and high-resolution microscopy. Additionally, 12-13 color flow cytometry and high-speed cell sorting equipment is used to assess functional markers and isolate B- and T-cell blood subsets of several cohorts of MS cases and healthy controls. We also take advantage of the in-house designed molecular assays to explore antigen- or EBV-driven maturation of sorted B-cell subsets (e.g. KREC assay, EBV qPCR). 17 RESULTS: Previously, we showed that of the candidate risk genes, CLEC16A, is upregulated in MS and is a key regulator of endosomal formation to control HLA-II expression in monocyte-derived dendritic cells. Our current research on the function of such risk genes in the HLA-II pathway zooms in on B cells, for which increased HLA-II surface expression was found on different subsets in MS. Differential EBV loads receptor expression in sorted B-cell subsets indicate a selective role of EBV in B cell development in MS. An interim finding in our study on functional T-cell markers and subsets is the strongly reduced frequency of highly activated effector Th1/17 (CXCR3+CCR6+) and for example not Th17 (CXCR3-CCR6+) in MS compared to control blood. These Th1/17 frequencies correlate with the time of CIS to MS conversion. CONCLUSIONS: This ongoing work provides evidence that the function of peripheral B and T cells is selectively regulated in MS. The reduced frequency of activated Th1/17 cells in MS blood implicate either differences in Th skewing, or their preferential migration to the CNS. We argue that HLA genetics and EBV integrate to selectively control B-T cell interaction, leading to impaired peripheral tolerance checkpoints in MS. Gijsbert van Nierop Local T-cell responses in MS Authors Gijsbert P. van Nierop1,2, Josef Mautner3, Malou Janssen1, Johanna G. Mitterreiter2,4, Rik L de Swart2, Bart L Haagmans2, Albert D.M.E. Osterhaus2, Georges M.G.M. Verjans1,4 and Rogier Q. Hintzen1 1 Affiliation MS centre ErasMS at the department of Neurology of the Erasmus MC, Rotterdam, the Netherlands 2 Department of Viroscience at the Erasmus MC, Rotterdam, the Netherlands 3 Helmholtz Zentrum München & Technical University, Munich, Germany 4 Research Center for Emerging Infections and Zoonosis, University of Veteri nary Medicine, Hannover, Germany Abstract BACKGROUND+OBJECTIVE: There is reason to believe that local intrathecal antigen recognition is instrumental in MS neuropathology. There are indirect signs of an aberrant response either auto- or foreign antigens (such as EBV), but the exact triggers remain to be elucidated. This project aims to study function, phenotype and fine specificity of locally derived intrathecal T cells, from cerebrospinal fluid (CSF) of early MS patients and controls or from post-mortem MS-tissues. METHODS: For early MS, CSF-derived T-cell lines (TCL) were generated by mitogenic stimulation from 29 MS and 13 other neurological disease (OND) patients. For chronically progressed MS, paired post-mortem tissues including MS lesion, normal appearing 18 white matter (NAWM) and CSF were obtained. Tissues were partly snap-frozen for in situ analysis and partly dispersed for T-cell phenotyping using flow cytometry and generation of TCL. CSF and tissue-derived TCL were analysed for clonal enrichment and antigen specificity. From blood, EBV-transformed B-cells (BLCL) were generated and used as autologous antigen presenting cell (APC) to simultaneously determine the frequency of EBV-specific CD4 and CD8 T-cells. Next, cognate CD8 T-cell antigens were identified using HLA-I negative monkey cells as artificial APC co-transfected with individual EBV antigens and the corresponding patient’s HLA-I alleles involved in T-cell reactivity. BLCL were stably transduced using a novel vector system for endogenous expression of eight MS-associated antigens (MSAg) used as APC in co-culture experiments. RESULTS: Early MS patients show an elevated oligoclonal BLCL-specific CD4 and CD8 T-cells response in CSF directed to lytic EBV antigens. No reactivity to MSAg is detected. In situ analysis of end stage MS lesions reveals extravasated T-cells, mainly CD8, expressing Ki67 and granzyme B, indicating local proliferation of antigen-experienced T-cells. Flow cytometric analysis shows a similar, mainly effector memory T-cell phenotype in MS lesions and NAWM but with distinct oligoclonal T-cell receptor Vß repertoires. BLCL-reactive T-cells are selectively detected in lesions of 2/7 MS patients. CONCLUSIONS: Enhanced intrathecal BLCL-specific T-cell reactivity, selectively directed towards lytic EBV proteins in CSF-TCL, suggest a local T-cell response to EBV early in MS. Inability to detect T-cells specific for eight MSAg questions their role as prominent target antigens in MS. Selective retention of BLCL-reactive CD8 T-cells in MS lesions indicate involvement of EBV-specific T-cells in at least part of the MS patients. 19 Session 2 From microglia to lymphocyte Chair: prof.dr. Jon laman Dept. of Neuroscience, section Medical Physiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands Bart Eggen Peripheral inflammation alters microglia function Authors Wandert Schaafsma, Xiaoming Zhang, Erik Boddeke, Bart Eggen Affiliation Dept. of Neuroscience, section Medical Physiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands Abstract BACKGROUND+OBJECTIVE: Microglia are the innate immune cells of the CNS involved in homeostasis maintenance. Microglia activation has been observed in a variety of neurodegenerative diseases, including Multiple Sclerosis, Alzheimer’s Disease and Amyotrophic Lateral Sclerosis. The aim of this study was to determine if peripheral inflammation altered microglia function and microglia activation in response to subsequent challenges. METHODS: Microglia were stimulated by lipopolysaccharides (LPS) and other TLR ligands, and the effect on microglia activation and function was determined in vitro and in vivo. Epigenetic changes in microglia were determined using chromatin immune precipitation experiments. Microglia function was assessed in view of cytokine secretion, electrophysiological parameters, and phagocytic activity. RESULTS: A single inflammatory insult by LPS resulted in a suppressed pro-inflammatory microglia phenotype. This reduced responsiveness to subsequent LPS challenges was persistent and accompanied by epigenetic silencing of inflammatory genes. LPS-challenged microglia displayed enhanced phagocytic activity and reduced inflammatory cytokine secretion after additional challenges. CONCLUSIONS: Microglia activation can be altered by a single peripheral inflammatory challenge, and result in long-term changes in microglia function. 20 Ilia Vainchtein The later stages of mouse EAE, a role for microglia. Authors Ilia Vainchtein, Martine Stevelink, Erik Boddeke, Bart Eggen Affiliation Department of Neuroscience, section Medical Physiology, University Medical Center Groningen, Groningen, The Netherlands Abstract BACKGROUND+OBJECTIVE: Multiple Sclerosis is a chronic, neurodegenerative inflammatory disorder where lesions are often associated with the presence of inflammatory immune cells. Using experimental autoimmune encephalomyelitis (EAE), an animal model for MS, infiltrated macrophages have been identified as the main driving force behind the progression of EAE. However, the role of microglia and other components of the infiltrating myeloid immune compartment remain under examined. Here, we studied microglia and infiltrating myeloid immune cells in more detail, in particular at the less well defined, later stages of EAE. MATERIALS+METHODS: EAE was induced in C57BL/6 mice using MOG35-55/CFA and pertussis toxin. Mice were terminated when their hind legs were paralyzed (acute phase) or 4-5 days after this time point when their EAE symptoms started to decline (slight remission). Subsequently, spinal cords were fixed and processed for immunohistochemistry or mechanically dissociated for cell isolation and subsequent FACS experiments. Using antibodies against CD11b, CD45, Ly-6C, Ly-6G, CD11c, and MHCII we have sorted pure microglia (CD11b+, CD45+ Ly-6C-) and various myeloid immune cell populations and analyzed their RNA expression profiles with quantitative RT-PCR. RESULTS: Immunohistochemistry results showed that Iba1-positive cells are always Ly6C negative, indicating that Iba1 positive cells are microglia. During EAE dense Ly-6C positive clusters appeared, which represent infiltrated myeloid cells. Microglia numbers extensively increased during EAE and displayed an activated morphology, not only around dense Ly-6C positive clusters, but throughout the spinal cord. Interestingly, at the slight remission stage, the Ly-6C positive clusters were no longer present. Instead very dense Iba1 positive microglia nodules were observed. Flow cytometry indicated that microglia upregulated their expression of MHCII during EAE, while the highest MHCII expression was detected in CD11c+ dendritic cells at the acute phase. Apart from these dendritic cells we have sorted macrophages and granulocytes. Macrophages and dendritic cells upregulated antigen presentation and myelin uptake related gene expression, whereas specifically the granulocytes have very high RNA expression of IL-1β and IL-10, indicating that these cells are actively involved EAE-related inflammation. CONCLUSIONS: During EAE, various peripheral immune cells infiltrate and although macrophages and dendritic cells have shown to be involved in EAE, granulocytes also 21 seem to play a major role. Microglia upregulate MHCII and cluster together at the later stages of EAE when the infiltrates have disappeared. This suggests an unidentified role for microglia during later stages of EAE, when mice display slight improvement in EAE score. Jordon Dunham Dichotomous outcome of IL-7 receptor (CD127) blockade in non-human primate experimental autoimmune encephalomyelitis. Authors Jordon Dunham1,2,3,5, Li-Fen Lee4, Nikki van Driel1, Jon D. Laman5, John C. Lin4, Jan Bauer6, Bert A. ‘t Hart1,2,3,5, and Yolanda S. Kap1 Affiliation 1Department of Immunobiology, Biomedical Primate Research Centre, Rijswijk, The Netherlands; 2 MS Centre Erasmus, Rotterdam, The Netherlands; 3 Department of Immunology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands; 4 Rinat, Pfizer Inc, South San Francisco, CA; 5 University Groningen, University Medical Center, Department of Neuroscience, Groningen, The Netherlands; 6 Medical University of Vienna, Center for Brain Research, Vienna, Austria Abstract Background & Objective: Interleukin-7 (IL-7) has complex biology with numerous functions, including T cell survival and proliferation, growth promotion of B cell progenitors, and enhancement of macrophage migration. Antibody blockade or deletion of the IL-7 receptor a (CD127) in mouse models of experimental autoimmune encephalomyelitis (EAE) ameliorates disease, demonstrating an important pathogenic function of IL-7. Evidence also suggests the IL-7/CD127 pathway may play an important role in multiple sclerosis (MS). Enhanced expression of both IL-7 protein and IL-7 mRNA is found in the cerebrospinal fluid of MS patients, with T cells isolated from the periphery and CNS exhibiting increased IL-7R expression. Here, we investigated whether CD127 blockade modulates EAE in a non-human primate model. Methods: EAE was induced in seven female marmoset twins by immunization with a 23-mer peptide from recombinant human myelin oligodendrocyte glycoprotein (MOG3456) emulsified in incomplete Freund’s adjuvant. Treatment with the anti-CD127 mAb or PBS as control was started 21 days after immunization followed by weekly intravenous administration. Results: The anti-CD127 mAb caused functional blockade as shown by reduced phosphorylation of STAT5 upon stimulation with IL-7. Despite functional blockade of CD127, we report that contrary to a profound clinical effect on EAE of CD127 blocking described 22 in mice, blockade of CD127 in the outbred marmoset could not entirely replicate effects on the clinical course of EAE. Treatment was associated with reductions of B cells (CD20+CD40+) and rescuing of CD27 expression on T cells. No treatment-associated changes were observed in MOG peptide-specific proliferation or IL-17A production by mononuclear cells. Although we observed no general effect in survival, treatment delayed disease onset in three fast EAE progressor twins. In this subgroup of marmosets that responded to treatment, a reduction of the percentages of B cells (CD3-CD20+CD40+) and programmed death receptor 1 (PD1)+ T cells were noted. Conclusions: The aforementioned heterogeneous responses highlight the complex nature of IL-7 biology and difficulties translating results obtained in genetically inbred models to genetically outbred populations. 23 Session 3 Microglia: how the brain talks to the immune system Chair: dr. Jeffrey Bajramovic Alternatives Unit, Biomedical Primate Research Centre, Rijswijk, The Netherlands Abstract For years microglia have been regarded as the macrophages of the brain. It was appreciated that microglia differ from other macrophages in some important aspects as reflected by the fact microglia were often referred to as ‘immature’ or ‘suppressed’ macrophages. However, we have learned recently that microglia derive from a different progenitor than macrophages do and we are learning rapidly about the characteristics of this fascinating cell type. This session will focus on what distinguishes microglia from other macrophages, both in terms of expressed proteins as in terms of functionality. In addition, we will discuss the necessity and the possibilities to study microglia biology for the pathogenesis of multiple sclerosis. -G inhoux F, Greter M, Leboeuf M, Nandi S, See P, Gokhan S, Mehler MF, Conway SJ, Ng LG, Stanley ER, Samokhvalov IM, Merad M. Science. 2010. 330(6005):841-5. - Butovsky O, Jedrychowski MP, Moore CS, Cialic R, Lanser AJ, Gabriely G, Koeglsperger T, Dake B, Wu PM, Doykan CE, Fanek Z, Liu L, Chen Z, Rothstein JD, Ransohoff RM, Gygi SP, Antel JP, Weiner HL. Nat Neurosci. 2014. (1):131-43. - Gosselin D, Link VM, Romanoski CE, Fonseca GJ, Eichenfield DZ, Spann NJ, Stender JD, Chun HB, Garner H, Geissmann F, Glass CK. Cell. 2014.159(6):1327-40. - Holtman IR, Noback M, Bijlsma M, Duong KN, van der Geest MA, Ketelaars PT, Brouwer N, Vainchtein ID, Eggen BJ, Boddeke HW. Glia. 2015 Mar 25. - Szulzewsky F, Pelz A, Feng X, Synowitz M, Markovic D, Langmann T, Holtman IR, Wang X, Eggen BJ, Boddeke HW, Hambardzumyan D, Wolf SA, Kettenmann H. PLoS One. 2015. 10(2) - Burm SM, Zuiderwijk-Sick EA, ‘t Jong AE, van der Putten C, Veth J, Kondova I, Bajramovic JJ. J Neurosci. 2015. 35(2):678-87. - Peferoen LA, Vogel DY, Ummenthum K, Breur M, Heijnen PD, Gerritsen WH, Peferoen-Baert RM, van der Valk P, Dijkstra CD, Amor S. J Neuropathol Exp Neurol. 2015. 74(1):48-63. 24 Inge Holtman Genome-wide approaches to study (micro) glia in health and disease: 1) Glia Open Access Database (GOAD; www.goad.education) and 2) a co-expression meta-analysis of primed microglia Authors I.R. Holtman1, H.W.G.M. Boddeke1*, B.J.L. Eggen1* Affiliation 1Medical Physiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands Abstract Recently a remarkable number of genome-wide transcriptome profiles from pure populations of glia cells has come available. This results in an unprecedented amount of data that can be used to study glia cells in health and disease. We recently developed the Glia Open Access Database (GOAD), to make this data easily available (url: www.goad. education). Moreover, we have done an extensive co-expression meta-analysis of microglia from different mouse models such as aging, Alzheimer’s Disease and Amyotrophic Lateral Sclerosis. A highly consistent consensus transcriptional profile of up-regulated genes was identified in all models of primed microglia, which prominently differed from the acute inflammatory gene network induced by lipopolysaccharide (LPS). Where the acute inflammatory network was significantly enriched for NF-kB signaling, the primed microglia profile contained key features related to phagosome, lysosome, antigen presentation, and AD signaling. To summarize, genome-wide approaches offer new data-driven opportunities to study (micro) glia in health and disease. Saskia Burm Innate immune activation in macrophages and microglia Authors Saskia Burm*, Ella Zuiderwijk-Sick*, Anke ‘t Jong*, Laura Peferoen#, Jan Bauer§, Celine van der Putten*, Jennifer Veth*, Ivanela Kondova‡, Sandra Amor#, Jeffrey Bajramovic* Affiliation *Alternatives Unit, Biomedical Primate Research Centre, Rijswijk, The Netherlands # Department of Pathology, VU Medical Centre, Amsterdam, The Netherlands § Department of Neuroimmunology, Medical University of Vienna, Vienna, Austria ‡ Animal Science Department, Biomedical Primate Research Centre, Rijswijk, The Netherlands Abstract BACKGROUND+OBJECTIVE: Activated innate immune cells are a prominent hallmark in multiple sclerosis (MS) lesions and include tissue-resident microglia and infiltrating macrophages. These cells can be activated via innate immune receptors by pathogens or by more general cellular stress, for example caused by neuronal degeneration. Recent studies have implicated NOD-like receptor (NLR)-mediated activation of microglia in 25 several neurodegenerative and infectious brain diseases. Upon activation, NLR can form multiprotein complexes with inflammatory caspases, called inflammasomes. Inflammasomes link pathogen recognition and cellular stress to the processing of the pro-inflammatory cytokine interleukin (IL)-1β. Whereas inflammasome-mediated activation is heavily studied in hematopoietic macrophages, much less is known about microglia. Although microglia resemble hematopoietic macrophages in phenotype and function, they originate from a distinct progenitor. The objectives of this study were to characterize involvement of the inflammasome in MS lesion development and to compare inflammasome-mediated activation in microglia and hematopoietic macrophages. METHODS: We studied IL-1β expression in well-characterized MS lesions, including preactive and (chronic) active lesions. To directly compare inflammasome-mediated activation in different types of macrophages, we isolated primary microglia and hematopoietic macrophages from adult, healthy rhesus macaques. We analyzed the expression profile of NLR and inflammatory caspases and characterized inflammasome activation and regulation in detail. RESULTS: We here demonstrate that IL-1β expression is only observed in microglial cells in pre-active MS lesions. In contrast, other MS lesion types, that also include infiltrating macrophages, are devoid of IL-1β expression. Furthermore, we demonstrate that in vitro primary microglia respond to the same innate stimuli as hematopoietic macrophages. However, microglial responses are more persistent due to lack of negative regulation on pro-IL-1β expression. In addition, we show that while caspase 1, 4 and 5 activation is pivotal for inflammasome-induced IL-1β secretion by hematopoietic macrophages, microglial secretion of IL-1β is only partially dependent on these inflammatory caspases. CONCLUSIONS: These results indicate involvement of the inflammasome in early MS lesions. Furthermore, we identify key cell type-specific differences between microglia and hematopoietic macrophages that may aid the development of strategies to modulate innate immune responses in the brain. Laura Peferoen Microglia show an intermediate activation status in early lesion formationin multiple sclerosis Authors Laura A.N. Peferoen1*, Daphne Y.S. Vogel1,2*, Kimberley Ummenthum1, Marjolein Breur2, Wouter Gerritsen1, Christien D Dijkstra2, Sandra Amor1,3 Affiliation 1Department of Pathology, VU University Medical Center, the Netherlands 2 Department of Molecular Cell Biology and Immunology, VU University Medical Center, the Netherlands 3 Department of Neuroimmunology Unit, Blizard Institute, Queen Mary University of London, UK 26 Abstract BACKGROUND+OBJECTIVE: Microglia play an important role during lesion formation in multiple sclerosis (MS). Well before the peripheral immune systems is involved and any sign of myelin damage is noticeable, foci of activated microglia appear in the normal appearing white matter (NAWM). Many of these so called preactive lesions are suggested to spontaneously resolve rather than developing into destructive lesions. This suggest that intrinsic regulation exists, which can stop lesion progression at an early stage. Activated microglia fulfil a broad range of functions both beneficial and harmful to the environment. Environmental signals are widely considered to contribute to the ‘switch’ between an immunoregulatory (M2) and a pro-inflammatory (M1) phentotype, in preactive lesions such signal might be the key to the developemt of active MS lesions. METHODS: Immunohistochemistry was used to determine the activation status of microglia in preactive lesions. First we screened primary human microglia polarized in a M1 or M2 phenotype for distinctive markers in vitro. To investigate whether a polarized phenotype is susceptible to changes in the microenvironment and thus switch between M1 and M2, polarized microglia were stimulated with the opposing treatment and qPCR for the most distinctive markers was performed. RESULTS: Our data showed that CD40, CD80 and CD74 were the most distinctive markers for M1, and mannose receptor (MR) for M2. Additionally, M1 microglia produce higher levels of pro-inflammatory chemokines CXCL10 and CCL2, whereas M2 phenotypes also produce CCL22. Using immunocytochemitry with antibodies directed to these markers revealed that all preactive lesions express an intermediate expression pattern; no preactive lesions were comprised specifically of M1 or M2 microglia. All activated microglia abundantly express M1 markers CD40, CD86, CD74 and the M2 cytokine CCL22. This indicates an intermediate activation status of microglia in preactive lesions. Furthermore, we showed that polarization of human microglia, in vitro, is not static, but a dynamic process in which microglia can switch from a M1 to a M2 phenotype and vice versa. CONCLUSIONS: Taken together, our data delineate the versatility of microglia, both in vitro and in vivo, in response to inflammatory signals from the CNS, already in early MS lesion formation. 27 Session 4 Inflammation at the barriers of the central nervous system in MS Chair: prof.dr. Elga de Vries Department of Molecular Cell Biology and Immunology, Neuroscience Campus Amsterdam, VU University Medical Center, MS Center Amsterdam, The Netherlands Abstract Leukocyte migration into the central nervous system (CNS) is a key stage in the development of multiple sclerosis (MS). In this process, inflammation and impaired function of the barriers of the CNS play a prominent role. Active participation of cells composing the blood-brain barrier (endothelial cells forming the BBB)) and the blood-cerebrospinal fluid barrier (epithelial cells of the choroid plexus forming the BCSFB) is critical to allow immune cells to pass these barriers of the CNS and induce severe and irreversible tissue damage. To fully grasp this process, the understanding of the key regulators of the brain endothelial and choroid plexus epithelial cell dynamics is essential. Within the current session, the altered cellular dynamics and interactions of the brain endothelial cells that form the BBB and the epithelial cells of the BCSFB that permit leukocyte migration into the CNS will be addressed. A better understanding of CNS barrier alterations in neuroinflammation might lead to new ways to promote their function in MS. Gijs Kooij The role of the choroid plexus in MS Authors G. Kooij, S.M.A. van der Pol, W.W. Kamphuis, C.D. Dijkstra, H.E. de Vries Affiliation Department of Molecular Cell Biology and Immunology, Neuroscience Campus Amsterdam, VU University Medical Center, MS Center Amsterdam, The Netherlands Abstract Background and objectives: Multiple sclerosis (MS) is a chronic neuro-inflammatory disorder, which is marked by the invasion of the central nervous system by monocyte-derived macrophages and auto-reactive T cells across the brain vasculature. Data from experimental animal models recently implied that the passage of leukocytes across the brain vasculature is preceded by their traversal across the blood-cerebrospinal fluid barrier (BCSFB) of the choroid plexus. The correlation between the presence of leukocytes in the CSF of patients suffering from MS and the number of inflammatory lesions as detected by magnetic resonance imaging suggests that inflammation at the choroid plexus contributes to the disease, although in a yet unknown fashion. Methods: Immunohistochemistry on human post-mortem choroid plexus brain tissues, real-time PCR, Western Blotting, deep sequencing and experimental autoimmune encephalomyelitis (EAE) using cldn3-/- mice. 28 Results: We here provide first insights into the involvement of the choroid plexus in the onset and severity of the disease and in particular address the role of the tight junction protein claudin-3 (CLDN3) in this process. Detailed analysis of human post-mortem brain tissue revealed a selective loss of CLDN3 at the choroid plexus in MS patients compared to control tissues. Importantly, mice that lack CLDN3 have an impaired BCSFB and experience a more rapid onset and exacerbated clinical signs of EAE, which coincides with enhanced levels of infiltrated leukocytes in their CSF. To provide a comprehensive view on CP alterations in MS, we used a deep sequencing approach (7 secondary progressive (SP-) MS patients and age/sex-matched controls), which revealed a large amount of differentially expressed genes. Conclusions: Together, this study highlights a profound role for the choroid plexus in the pathogenesis of multiple sclerosis, and implies that CLDN3 may be regarded as a crucial and novel determinant of BCSFB integrity. Jasmine Vanmol Relation between LXR activation and blood-brain barrier function during neuroinflammation in multiple sclerosis Authors J. Vanmol1, T. Vanmierlo1, J.F.J. Bogie1, S.M.A. van der Pol2, M.Mizee2, P. Stinissen1, N. Hellings1, H.E. de Vries2, J.J.A. Hendriks1 1 Affiliation Hasselt University, Biomedical Research Institute, School of Life Sciences, Diepenbeek, Belgium 2 Department of Molecular Cell Biology and Immunology, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, the Netherlands Abstract Background and objective: Multiple sclerosis (MS) is a demyelinating disease of the central nervous system (CNS), featured by an early disruption of the blood-brain barrier (BBB). Brain endothelial cells (BECs) tightly regulate BBB function and are regarded as the gatekeepers of the CNS. Changes in BBB properties comprise alterations in the tight and adherent junctions, differences in BEC adhesion molecule expression, and modulated chemoattraction of leukocytes. At the crossroads of linking metabolic and inflammatory responses are the liver X receptors (LXRs). In this study, the effect of LXR activation on BEC function was determined. Methods: The effect of inflammatory stimuli (interferon (IFN) gamma and tumor necrosis factor (TNF) alpha in combination with the LXR agonist GW3965 was studied in vitro in the human brain endothelial cell line hCMEC/D3 and ex vivo in primary CECs isolated from wild type and LXRalpha or LXRbeta isoform knockout mice using dextran gradient 29 centrifugation. Modulation of BBB properties and pro-inflammatory chemoattractants were quantified by qPCR. Results: In vitro, LXR activation in hCMEC/D3 suppressed the cell surface expression of the adhesion molecules ICAM-1 and VCAM-1 in a dose-dependent manner. Furthermore, the expression of CXC chemokines was reduced in hCMEC/D3 following LXR activation. Ex vivo, LXR response genes (ABCA1 and ABCG1) showed less upregulation after LXR activation in BECs isolated from LXRbeta isoform knockout mice compared to LXRalpha isoform knockout and wild type mice. Conclusions: Under inflammatory conditions, BBB properties are positively affected by the activation of LXRs in BECs. The suppression of adhesion molecule expression and chemoattraction by an LXR agonist provides an anti-inflammatory environment and may lead to reduced leukocyte extravasation into the CNS. LXRbeta appears the main LXR isoform in brain endothelial cells of the BBB confirming the importance of LXR subtype-specific research. Claudio Derada Troletti Molecular regulation of the blood-brain barrier phenotype Authors C. Derada Troletti1, W.W Kamphuis1, A. Reijerkerk2, B. Van Het Hof AJ1, I.A. Romero3 and H.E de Vries1 1 Affiliation Blood-brain barrier research group, Department of Molecular Cell Biology and Immunology, Neuroscience Campus Amsterdam, VU Medical Centre, P.O. Box 7057, 1007 MB Amsterdam, The Netherlands 2 Pluriomics therapeutics, Galileiweg 8, 2333 BD Leiden, The Netherlands 3 Biomedical Research Network, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK Abstract Background + objective: An early event in MS is the impairment function of the blood-brain barrier (BBB) which consists of specialized brain endothelial cells (BECs) supported by surrounding glial cells. Both inflammation and BBB dysfunction are pathological hallmarks of MS and affect brain homeostasis. Endothelial to mesenchymal transition (EndoMT) is a dynamic process that has been linked to pathological setting like cancer and fibrosis. During EndoMT, endothelial cells dedifferentiate into mesenchymal cells and as a result loose their tight and adherent junction, which are essential for the BBB function. The EndoMT process is known to be induced by transforming growth factor (TGF)-β which activates two important transcription factors: Snail1 and Snail2. Furthermore, recent discoveries unravelled a critical role for microRNAs (miRNA) in controlling the barrier properties of the endothelium in the 30 brain. Interestingly, both Snail1 and Snail2 are both predicted targets of miRNA-30c, of which we have previously shown that this miRNA is significantly downregulated both in MS patients post-mortem material as well as in inflamed human brain endothelial cells (hCMEC/D3). We believe that TGF-β can induced EndoMT in BECs and this event can play an important role in the alteration of the BBB phenotype. Moreover, we think that a miRNA based approach could restore the normal BBB phenotype by inhibiting the dedifferentiation of the BECs via targeting Snail1 and Snail2. Methods: To investigate the EndoMT process, hCMEC/D3 were stimulated for 48 hours with 10ng/ml of TGF-β and interleukin (IL)-1β. qPCR and western blot were used to analyze gene and protein expression. Results: Our preliminary data show that TGF-β and IL-1β can induce EndoMT in hCMEC/D3 which can be demonstrated by the loss of expression of brain endothelial markers and a gain in expression of mesenchymal markers. Moreover, Snail1 and Snail2 were upregulated in treated hCMEC/D3. Conclusions: Our findings suggest that EndoMT can be involved in the BBB breakdown and participate in the pathogenesis of MS. Moreover, repair of a disturbed BBB through a specific miRNA approach may represent a novel avenue for effective treatment of MS. 31 Session 5 Progressive MS Alliance Chair: Ceri Angood Napier Director of Programmes, Multiple Sclerosis International Federation Sandra Amor Immune-primed microglia: a factor underlying progressive multiple sclerosis Authors Sandra Amor Affiliation Department of Pathology, VU University Medical Center, 1007MB, Amsterdam, The Netherlands. Abstract This team aims to investigate the specific role of brain cells called “microglia” on MS progression. Both primary and secondary progressive MS start around 35 years, irrespective of relapses, suggesting that age may be a factor. Microglia help to activate the immune system (which attacks the brain and spinal cord in MS), but also dampen inflammation, producing substances that promote repair. A subtle balance exists between these two opposing functions. With increasing age, this balance shifts, and microglia become less effective in their protective functions, and more active stimulating damage, possibly explaining why progression increases with age. This team proposes to examine microglia from people with different types of MS, and people without neurological disease, taking into account their ages. This may reveal differences between “young” and “old” microglia, and differences between people with and without MS. They are extending these experiments in mice with relapsing-remitting MS-like disease that later becomes progressive. 32 Philip Nijland Inflammation drives mitochondrial dysfunction and associated neurodegeneration in multiple sclerosis Authors Philip G. Nijland1, Andreia Carvalho1, Maarten E. Witte2, Tim Muntslag1, Susanne MA van der Pol1, Helga E. de Vries1, Richard Reynolds3 and Jack van Horssen1 Affiliation 1Department of Molecular Cell Biology and Immunology, VU University Medical Center, 1007MB, Amsterdam, The Netherlands. 2 Institute of Clinical Neuroimmunology, Ludwig-Maximilians University Munich, Munich, Germany 3 Division of Brain Sciences, Faculty of Medicine, Imperial College London, Hammersmith Hospital, London, UK. Abstract In progressive MS patients, the steady rise in clinical disability is the direct result of neuronal tissue loss. However, remarkably little is known about the pathological processes leading to neurodegeneration. A better understanding of the mechanisms that drive neuronal injury and loss in progressive MS patients is required for the development of novel therapeutic treatment strategies aimed at limiting neurodegeneration. In the last decade, we and others have shown that neuronal mitochondrial dysfunction is closely associated with neuronal damage and loss in progressive MS patients. Our recent data using brain tissue samples from progressive MS patients and a novel animal model of MS suggest that inflammatory processes in the meninges and cortex of MS patients contribute to neuronal mitochondrial alterations. Moreover, we show that key inflammatory mediators produced by activated cortical microglia and meningeal infiltrates induce mitochondrial defects. Our preliminary studies will provide important new insights in the pathogenic mechanisms that drive progressive MS and might ultimately lead to the identification of putative therapeutic targets. Charlotte Teunissen Discovery of biomarkers reflecting progression pathophysiology for primary progressive MS subtype by applying next generation sequencing and novel multiplex aptamer approach. Authors A. Malekzadeh, J. Kuhle, C. Leurs, C. Oudejans, J. Killestein, CE Teunissen Affiliation VU University Medical Center Amsterdam Abstract Background: The heterogeneity in MS disease mechanisms is observed at both the patho-histological level and clinical disease course. The need for plasma based biomarkers for MS is required due to relative ease of access to blood. To attain new leads to unravel the mechanisms and predict MS progression, we previously selected plasma 33 samples of PPMS (n=10) patients, relapse-onset rapid progressors (RO-rapid, n=10) and relapse-onset slow progressors (RO-slow n=10) based on their disease course during ~4 years of follow-up and performed novel multiplex aptamer proteomics (SomaScan). Aim: The aim of the current proposal was to validate these proteomics results in plasma samples of MS patients with relapse-onset (RO) slow, RO-rapid disease course and primary progressive (PP), by aptamer proteomics. Two independent cohorts (Basel and Amsterdam) were selected, based on similar clinical characteristics as the previous study. In parallel, we used the same plasma samples for next generation sequencing, this to gain insight into to the epigenetic and transcriptomic pathways associated with these progression mechanisms. Results: Group comparisons between RO-slow and RO-rapid showed interesting markers that are associated with neuroprotection and inflammation. Group comparisons between RO-all and PP yielded several interesting markers associated with inflammatory pathways, cell motility, cytoskeleton and cell cycle related pathways. Lastly, similar pathways were observed by next generation seqeuncing on plasma for comparisons between RO-slow to RO-rapid and RO-all compared to PP. We also observed several regulatory non-coding RNAs and transcription factors differentiating the groups. The significant markers derived from sequencing are currently analyzed in an independent cohort by RT-PCR Conclusion: This innovative approach will lead to the discovery of marker(s) that potentially reflect PP and RO MS disease progression and aid in subtype diagnostics. Moreover, we will gain insight into pathophysiological mechanisms by means of proteomics, transcriptomics and epigenetic mechanisms that are involved in PP and RO progression. Peter Feys Towards a shared data repository to enhance the standards of rehabilitation in MS: feasibility, capacity building and proof-of-concept on exercise therapy & mobility measures. Authors Feys P1, Held Bradford E2, Baert I1, Wagner J2 Affiliation 1Hasselt University, REVAL rehabilitation Research Center, BIOMED, Diepenbeek, Belgium 2 Saint Louis University, Doisy College of Health Sciences, St Louis, United States Abstract Persons with progressive MS show overall more disability than those with the relapsing remitting type. Exercise therapy is a potentially effective treatment modality. However, despite an explosion of research on physical rehabilitation and exercise, it is not yet clear 34 whether beneficial effects are equally present in progressive compared to relapsing-remitting type of MS, and to what degree effects are dependent on severity level and the intervention (modality, duration and intensity). Also, it is not well-known which outcome measures are the best to measure changes in mobility that are meaningful to the person with MS. The development of this knowledge, specifically on exercise but also generally on rehabilitation, has been delayed in part by four issues: 1) small sample sizes that do not allow distinction of effects according to MS type or disability level, 2) limited systematic description of the intervention content (so-called ‘black box’ of rehabilitation), 3)inconsistent inclusion of multi-dimensional outcome measures with insufficient knowledge on their accuracy and values of meaningful change and 4) limited efforts to determine the dosage-response of different rehabilitation strategies. The long-term goal is to provide answers to research questions on the multi-dimensional effects of rehabilitation according to type of MS or disability level. This project concerns preparing the construction of a large shared data repository that will be established by 1) retrospective data retrieval of individual patient data of published studies and 2) prospective data entry by clinical and research centers. This will allow researchers to investigate questions on the (comparative) effects of specific interventions and settings, or on the appropriateness of different outcome measures. Ultimately, this will lead to improved standards in MS rehabilitation practice. This study will allow us to investigate 1) the legal regulation of repositories in Europe and the United States, 2) knowledge transfer of existing registries, 3) researcher’s perceived barriers and facilitators to data sharing, 4) clinician’s willingness and ability to provide data in a registry, 5) engagement of experts to collaborate in workgroups to define the outcome measures for the registry, and opinion on classification systems for treatment. Proof-of-concept studies will be performed in the domain of exercise therapy and mobility outcome measures. A platform will be established for information and communication. 35 Session 6 Remyelination in MS: from basic science to therapy? Chair: dr. Wia Baron Department of Cell Biology, University Medical Center Groningen, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, the Netherlands Abstract Multiple sclerosis (MS) is a chronic demyelinating disease of unknown etiology affecting the central nervous system. Clinical symptoms are manifested in a relapsing-remitting or progressive course, leading to an ultimate decline in neurological activity. Current approved MS therapies are primarily directed against the immune system, which is effective in relapsing-remitting MS but not in the progressive stages. A major challenge in the field is to address the progressive types of MS with regenerative and neuroprotective strategies. Indeed, remyelination following demyelination is essential for axonal survival and restoration of saltatory conduction, and its failure is a major cause of the neurological deficits in MS. Therefore, restoring remyelination should provide an effective treatment in halting disease progression and reversing disability. For the development of such a therapy, an understanding of molecular and cellular mechanisms that contribute to failure or restoration of remyelination is imperative. Remyelination of denuded axons requires the generation of new oligodendrocytes from oligodendrocyte progenitor cells (OPCs). The decline of remyelination in progressive MS is in part attributed to inadequate OPC migration towards the lesion and/or decreased OPC survival or in most cases to failure of OPC differentiation within the demyelinated areas. In this session, Jamie Lim (VUmc) will show evidence that Nrf2 activators protect oligodendrocyte from oxidative damage, and promote OPC differentiation. Inge Werkman (UMCG) will focus on the role of micro-environmental signals and present data on the distinct modulation of (re)myelination efficiency by cortical and non-cortical astrocytes, Finally, Arun Thiruvalluvan (UMCG) will speak on the remyelination potential of human iPSC-derived OPCs. All speakers will highlight how their findings on basic science (cel) biology will provide possibilities for improved and targeted remyelination in MS. Jamie Lim Nrf2 activators: a novel strategy to promote oligodendrocyte survival in multiple sclerosis? Authors Jamie Lim, Susanne van der Pol, Joost Drexhage, Elga de Vries, Jack van Horssen Affiliation Department of Molecular Cell Biology and Immunology, VU University Medical Center Amsterdam, the Netherlands Abstract BACKGROUND: Oligodendrocyte damage and loss are key features of multiple sclerosis (MS) pathology and oligodendrocytes appear to be particularly vulnerable to reactive 36 oxygen species (ROS). In vitro studies showed that ROS induce cell death and prevent the differentiation of oligodendrocyte precursor cells (OPCs) into mature myelin-producing oligodendrocytes. Hence, a potential therapeutic strategy to protect these cells from ROS-mediated damage is urgently needed. Here we investigated the efficacy of several compounds that are able to boost antioxidant enzyme production, including monomethyl fumarate (MMF), sulforaphane (SFN) and Protandim. These compounds are thought to exert their protective function via activation of the nuclear-factor-E2-related factor-2 (Nrf2) transcriptional pathway, which is involved in the production of antioxidant enzymes necessary for oxidative stress defense. OBJECTIVE: To investigate the potential of different Nrf2 activators to boost antioxidant enzyme expression in oligodendrocytes, protect them from ROS-mediated cell death and promote the differentiation of OPCs under inflammatory and oxidative conditions. METHODS: Primary rat oligodendrocytes were treated with different concentrations of MMF, SFN and Protandim. Expression of antioxidant enzymes was analyzed by PCR and Western blot analyses. To study the beneficial effects of the different Nrf2 activators, oligodendrocytes were incubated with Nrf2 activators and subsequently exposed to various concentrations of hydrogen peroxide. Oligodendrocyte cell survival was measured by live/death viability assay. Moreover, to investigate whether Protandim can promote the differentiation of OPCs under inflammatory or oxidative conditions, OPCs were treated with Protandim or vehicle control prior to exposing them to sub-lethal concentrations of tumor necrosis factor or hydrogen peroxide for 5 days. OPC differentiation was determined by comparing the ratio of MBP-positive to MBP-negative oligodendrocytes. RESULTS: SFN, MMF and Protandim are well-tolerated and induce Nrf2-driven antioxidant enzyme production in oligodendrocytes. Protandim was the most potent compound with regard to antioxidant enzyme induction and protected oligodendrocytes against ROS-induced cytotoxicity. Moreover, Protandim reduced the inhibitory effects of tumor necrosis factor and hydrogen peroxide on OPC differentiation. CONCLUSIONS: Nrf2 activators, particularly Protandim, are able to induce antioxidant enzyme production and protect oligodendrocytes against inflammatory and oxidative insults making them interesting therapeutic compounds. 37 Inge Werkman Distinct modulation of myelination efficiency by cortical and non-cortical astrocytes Authors Inge Werkman, Dick Hoekstra, Wia Baron Affiliation Department of Cell Biology, University Medical Center Groningen, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, the Netherlands Abstract BACKGROUND+OBJECTIVE: Multiple sclerosis (MS) is an inflammation-mediated demyelinating disease of the central nervous system, which eventually results in axonal degeneration due to failure of remyelination. Functional remyelination depends, among others, on carefully regulated signalling events, and requires sequential activation, recruitment and maturation of oligodendrocyte progenitor cells (OPCs). In addition to demyelination in the non-cortical areas of the brain, also cortical demyelination has been recognized as a feature of MS pathology. Intriguingly, remyelination is more efficient in cortical MS lesions. Underlying mechanisms of this remarkable difference in remyelination efficiency are likely related to cellular and environmental differences of cortical and non-cortical lesions. Here, we investigated how cortical, as opposed to non-cortical astrocytes modulate myelination efficiency. METHODS: In vitro myelinating cultures were placed on a feeding layer of either cortical or non-cortical astrocytes. In addition, the effect of astrocyte-derived secreted factors, extracellular matrix (ECM) factors or cues that dependent on cell-cell interaction on OPC behaviour were examined in primary oligodendrocyte monocultures. RESULTS: Our data reveal that in vitro myelination is more pronounced on a feeding layer of adult cortical than on non-cortical astrocytes. Secreted factors from cortical astrocytes slightly increased myelin-like membrane formation as compared to secreted factors from non-cortical astrocytes, while no effect on OPC differentiation was observed. In addition, secreted factors from cortical astrocytes promoted the viability of oligodendrocytes. However, OPC viability was significantly increased in the presence of conditioned-medium obtained from either astrocyte as compared to normal medium. No significant differences in OPC maturation were observed, as induced by cell-cell contact and astrocyte deposited ECM-mediated signals, derived from either cortical or non-cortical astrocytes. CONCLUSIONS: These findings thus further highlight that cortical astrocytes are more supportive to (re)myelination than non-cortical astrocytes, however, via which means remains to be established. Astrocyte derived conditioned media, ECM and direct cellcell contact had minimal effects on OPC behaviour. Therefore, it seems likely that the enhanced myelination efficiency by cortical astrocytes is caused by an indirect effect on myelination, presumably via neurons. 38 Arun Thiruvalluvan Functionality of human induced pluripotent stem cell-derived oligodendrocytes in an MS primate model Authors Arun Thiruvalluvan, Marcin Czepiel, Yolanda Kap, Ilia Vainchtein, Jeroen Kuipers, Marjolein Bijlard, Wia Baron, Ben Giepmans, Wolfgang Brück, Bert ’t Hart, Erik Boddeke, Sjef Copray Affiliation Department of Neurosciences, University Medical Centre Groningen, Groningen, the Netherlands. Abstract BACKGROUND+OBJECTIVE: Fast remyelination by endogenous oligodendrocyte precursor cells (OPCs) is essential to prevent axonal and subsequent retrograde neuronal degeneration in demyelinating lesions in Multiple sclerosis (MS). In chronic lesions, however, the remyelination capacity of OPCs becomes insufficient. Cell therapy with exogenous remyelinating cells has been forwarded as a potential strategy to replace the failing endogenous OPCs, but the absence of a suitable autologous source for such cells has hampered such an approach so far. Induced pluripotent stem cells (iPSCs) have provided a unique autologous source for remyelinating cells. In previous studies in rodents we have demonstrated the efficacy of implanted iPSC-derived OPCs to remyelinate demyelinated axons and to reduce symptoms in the EAE mouse model for MS. In the present study, we aim to investigate the functionality of iPSC-derived OPCs in a nonhuman primate model for MS. METHODS: We have generated human iPSCs by nonvirally reprogramming fibroblasts isolated from a small skin biopt and developed a protocol to differentiate them into OPCs. After characterization and validation of their myelin-forming capacity in vitro (DRG co-culture) as well as in vivo (cuprizone mice), we have implanted the human iPSC-derived OPCs stereotactically in the cortex of a nonhuman primate model for MS: the EAE marmoset model. This primate model is considered the most adequate animal model for RR-MS as it accurately mimics the relapsing-remitting disease course and the occurrence of typical demyelinated, inflammation-invested lesions as found in the brain of MS patients. We have examined the fate and functionality of human iPSC-derived OPCs up to 40 days after implantation in extensive immunohistochemical analyses. RESULTS: Our results show that: - the human iPSC-derived OPCs survive after stereotactic implantation within the marmoset brain - they selectively migrate to the demyelination lesions in the corpus callosum - they differentiate and maturate into myelin-forming oligodendrocytes - they form new myelin around denuded axons in the MS-lesion. 39 CONCLUSIONS: Our findings in the nonhuman primate model for MS are the first ones indicating that human iPSC-derived OPCs may be novel candidates for a remyelination therapy for MS patients. 40 Session 7 Imaging Chair: dr.ir. Hugo Vrenken Department of Radiology and Nuclear Medicine and Department of Physics and Medical Technology, Neuroscience Campus Amsterdam, VU University Medical Center, The Netherlands Abstract This session is dedicated to studies of MS through imaging, including but not limited to magnetic resonance imaging (MRI). MRI has played an important role in MS research already for a long time. Recent work shows that MRI could improve accuracy of clinical prognosis: clinical worsening is related to whole-brain MRI outcome measures such as lesion volume change and whole-brain volume change (Popescu 2013), but also ventricle volume change (Lukas 2010, Popescu 2013) and upper cervical spinal cord volume loss (Lukas 2015). MRI has also contributed to understanding disease evolution. Gray matter volume loss, or atrophy, has become an important outcome measure, and much work has been done to improve its measurement (e.g. Popescu 2014) and understand its development (e.g. Steenwijk 2014). The first talk of this session highlights how, by combining different MRI techniques, we may disentangle different contributions to the GM atrophy patterns observed in MS. Beyond MRI, important recent imaging work has focused on optical coherence tomography (OCT) of the retina (e.g., Balk 2014a, Balk 2015), which has been aptly termed “a window to the brain”. OCT can provide rapid, non-invasive assessment of retinal pathology (review in Balk 2014b). The second talk of this session focuses on retinal pathology in MS patients assessed through OCT in a longitudinal study. Imaging also plays an important role in studies of animal models of MS, whether to improve the understanding of disease processes or in the development of new treatment agents for MS. Recent work combining different disease models and different imaging methods studied the relations between (among other) microglial activation and de- and remyelination (de Paula Faria 2014a,b,c; Olah 2012). The third talk in this session highlights some recent advances in this field, focusing on PET imaging of microglial activation and of myelin in the cuprizone mouse model of MS. -B alk L, Tewarie P, Killestein J, Polman C, Uitdehaag B, Petzold A. Disease course heterogeneity and OCT in multiple sclerosis. Mult Scler. 2014a;20(9):1198-1206. - Balk LJ, Petzold A. Current and future potential of retinal optical coherence tomography in multiple sclerosis with and without optic neuritis. Neurodegener Dis Manag. 2014b; 4(2):165-76. Review. - Balk LJ, Steenwijk MD, Tewarie P, Daams M, Killestein J, Wattjes MP, Vrenken H, Barkhof F, Polman CH, Uitdehaag BM, Petzold A. Bidirectional trans-synaptic axonal degeneration in the visual pathway in multiple sclerosis. J Neurol Neurosurg Psychiatry. 2015;86(4):419-24. 41 -d e Paula Faria D, Vlaming ML, Copray SC, Tielen F, Anthonijsz HJ, Sijbesma JW, Buchpiguel CA, Dierckx RA, van der Hoorn JW, de Vries EF. PET Imaging of Disease Progression and Treatment Effects in the Experimental Autoimmune Encephalomyelitis Rat Model. J Nucl Med. 2014a;55(8):1330-1335. - de Paula Faria D, de Vries EF, Sijbesma JW, Buchpiguel CA, Dierckx RA, Copray SC. PET imaging of glucose metabolism, neuroinflammation and demyelination in the lysolecithin rat model for multiple sclerosis. Mult Scler. 2014b;20(11):1443-52. - de Paula Faria D, de Vries EF, Sijbesma JW, Dierckx RA, Buchpiguel CA, Copray S. PET imaging of demyelination and remyelination in the cuprizone mouse model for multiple sclerosis: a comparison between [11C]CIC and [11C]MeDAS. Neuroimage. 2014c;87:395-402. - Lukas C, Minneboo A, de Groot V, Moraal B, Knol DL, Polman CH, Barkhof F, Vrenken H. Early central atrophy rate predicts 5 year clinical outcome in multiple sclerosis. J Neurol Neurosurg Psychiatry. 2010;81(12):1351-6. - Lukas C, Knol DL, Sombekke MH, Bellenberg B, Hahn HK, Popescu V, Weier K, Radue EW, Gass A, Kappos L, Naegelin Y, Uitdehaag BM, Geurts JJ, Barkhof F, Vrenken H. Cervical spinal cord volume loss is related to clinical disability progression in multiple sclerosis. J Neurol Neurosurg Psychiatry. 2015;86(4):410-8. - Olah M, Amor S, Brouwer N, Vinet J, Eggen B, Biber K, Boddeke HW. Identification of a microglia phenotype supportive of remyelination. Glia. 2012;60(2):306-21. - Popescu V, Agosta F, Hulst HE, Sluimer IC, Knol DL, Sormani MP, Enzinger C, Ropele S, Alonso J, Sastre-Garriga J, Rovira A, Montalban X, Bodini B, Ciccarelli O, Khaleeli Z, Chard DT, Matthews L, Palace J, Giorgio A, De Stefano N, Eisele P, Gass A, Polman CH, Uitdehaag BM, Messina MJ, Comi G, Filippi M, Barkhof F, Vrenken H; MAGNIMS Study Group. Brain atrophy and lesion load predict long term disability in multiple sclerosis. J Neurol Neurosurg Psychiatry. 2013;84(10):1082-91. - Popescu V, Ran NC, Barkhof F, Chard DT, Wheeler-Kingshott CA, Vrenken H. Accurate GM atrophy quantification in MS using lesion-filling with co-registered 2D lesion masks. Neuroimage Clin. 2014;4:366-73. - Steenwijk MD, Daams M, Pouwels PJ, Balk LJ, Tewarie PK, Killestein J, Uitdehaag BM, Geurts JJ, Barkhof F, Vrenken H. What explains gray matter atrophy in long-standing multiple sclerosis? Radiology. 2014;272(3):832-42. 42 Martijn Steenwijk Understanding the relation of gray matter atrophy patterns in multiple sclerosis with other MS pathology Authors Martijn D. Steenwijk MSc1, Marita Daams MSc1,2, Petra J.W. Pouwels PhD3, Lisanne Balk MSc4, Prejaas K. Tewarie MD4, Jeroen J. G. Geurts PhD2, Frederik Barkhof PhD1, Hugo Vrenken PhD1,3 Affiliation Neuroscience Campus Amsterdam, VU University Medical Center, The Netherlands 1 Department of Radiology and Nuclear Medicine 2 Department of Anatomy and Neurosciences 3 Department of Physics and Medical Technology 4 Department of Neurology Abstract Introduction: Gray matter (GM) atrophy is common in multiple sclerosis (MS), but the relationship with white matter (WM) pathology is largely unknown. Some studies found a co-occurrence in specific systems, but a regional analysis across the brain in different clinical phenotypes is necessary to further understand the disease mechanism underlying GM atrophy in MS. Therefore we investigated the association between regional GM atrophy and pathology in anatomically connected WM tracts. Methods: Conventional and diffusion tensor imaging was performed at 3T in 208 patients with long-standing MS and 60 healthy controls. Deep and cortical GM regions were segmented and quantified, and both lesion volumes and normal appearing WM fractional anisotropy of their associated tracts were derived using an atlas obtained by probabilistic tractography in the controls. Linear regression was then performed to quantify the amount of regional GM atrophy that can be explained by WM pathology in the connected tract. Results: MS patients showed extensive deep and cortical GM atrophy. Cortical atrophy was particularly present in frontal and temporal regions. Pathology in connected WM tracts statistically explained both regional deep and cortical GM atrophy in relapsing-remitting (RR) patients, but only deep GM atrophy in secondary-progressive (SP) patients. Conclusion: In RRMS patients, both deep and cortical GM atrophy were associated with pathology in connected WM tracts. In SPMS patients, only regional deep GM atrophy could be explained by pathology in connected WM tracts. This suggests that in SPMS patients cortical GM atrophy and WM damage are (at least partly) independent disease processes. 43 Lisanne Balk Timing of retinal neuronal and axonal loss in MS; a longitudinal OCT study Authors Lisanne J. Balk, PhD,1 Andres Cruz-Herranz, MD,2 Philipp Albrecht, MD,3 Sam Arnow, BS,2 Jeffrey M. Gelfand, MD, MAS,2 Prejaas Tewarie, MD, PhD,1 Joep Killestein, MD, PhD,1 Bernard M.J. Uitdehaag, MD, PhD,1 Axel Petzold, MD, PhD1 and Ari J. Green, MD2 1 Affiliation Department of Neurology, VU University Medical Center, Amsterdam, the Netherlands 2 Department of Neurology, University of California San Francisco, San Francisco, United States 3 Department of Neurology, Heinrich-Heine University, Düsseldorf, Germany Abstract Background: The timing of retinal and axonal atrophy in multiple sclerosis remains unknown. It has often been presumed that the pace of central nervous system tissue atrophy in MS is consistent throughout the course of disease. Objective: To investigate the timing of central nervous system tissue atrophy in MS by evaluating longitudinal retinal volume changes in a broadly representative cohort with disease duration across the entire arc of disease. Methods: In this longitudinal study, 135 patients with MS and 16 healthy reference subjects underwent spectral-domain optical coherence tomography (OCT) at baseline and two years later. Following OCT quality control, automated segmentation of the the peripapillary retinal nerve fiber layer (pRNFL), macular ganglion cell-inner plexiform layer (mGCIPL) and macular inner nuclear layer (mINL) was performed. Generalized estimation equations were used to analyze longitudinal changes and associations with disease duration and clinical measures. Results: Participants had a median disease duration at baseline of 16.4 years (range 0.1-45.4). Nearly half (44%) of the MS patients had previously experienced MS related optic neuritis (MSON) greater than 6 months prior. The MS patients demonstrated a significant decrease over two years of the pRNFL (-1.1 µm, 95%CI 1.4 to 0.7,p<0.001) and mGCIPL (-1.1 µm, 95% CI -1.4 to -0.8,p<0.001), however, this thinning was most pronounced early in the course of disease. These findings were irrespective of previous episodes of MSON. No consistent pattern of change was observed for the mINL (-0.03 µm, 95%CI -0.2 to 0.2,p=0.795). Conclusion: This longitudinal study showed that retinal injury in MS occurs most rapidly during early stages of disease. The attenuation of atrophy with longer disease duration is suggestive of a plateau effect. These findings emphasize the importance of early intervention to prevent such injury. 44 Ate Boerema Longitudinal monitoring of microglia activation and CNS myelin with [11C]PK11195 and [11C] MEDAS PET imaging in the cuprizone mouse model for Multiple Sclerosis. Authors Boerema AS1, de Paula Faria D1,2,3, Kurtys E1, Verkuijl M4, Broersen LM4, Doorduin J1, Klein HC1, Eisel ULM5, Dierckx RAJO1, Copray JCVM2, de Vries EFJ1 Affiliation Departments of 1Nuclear Medicine & Molecular Imaging and 2Neuroscience, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands 3 Center of Nuclear Medicine, University of Sao Paulo, University of Sao Paulo Medical School, Sao Paulo, Brazil 4 Nutricia Advanced Medical Nutrition, Nutricia Research, Utrecht, the Netherlands 5 Department of Molecular Neurobiology, University of Groningen, Groningen, the Netherlands Abstract Objectives: Multiple Sclerosis (MS) is an inflammatory neurodegenerative disease characterized by inflammatory and demyelinated lesions in the brain. Microglia Activation (MA) occurs during both de- and remyelination. Traditionally MA is associated with myelin loss, but recent evidence suggests a supportive function of MA during remyelination.1 Monitoring MA and myelin content in vivo would provide a powerful tool to assess remyelination enhancing treatments during MS. In this study we aim to investigate whether it is possible to monitor MA and myelin status, over time, during de- and remyelination, in vivo, in the cuprizone mouse model for MS. Methods: Eight-week-old male C57BL6/J mice were exposed to 0.2% cuprizone for 5.5 weeks to induce demyelination. Thereafter remyelination was allowed to occur. MA was measured by [11C]PK11195 PET imaging at 7 time points: just before the start of cuprizone exposure (baseline); 3, 4 and 5 weeks after the onset of cuprizone exposure (demyelination); and 1, 2 and 5 weeks after the end of cuprizone exposure (remyelination). [11C]MEDAS scans were performed at the end, and 5 weeks after the end of cuprizone exposure, to measure CNS myelin content. Control [11C]MEDAS uptake was measured in an age matched control group.2 Results: We found a strong and significant increase in brain [11C]PK11195 uptake during demyelination, peaking 5 weeks after the onset of cuprizone exposure. During remyelination [11C]PK11195 uptake was initially still increased, but progressively decreased. Five weeks after remyelination onset [11C]PK11195 uptake was statistically indistinguishable from baseline. The [11C]MEDAS scans confirmed de- and remyelination in the CNS. 45 Conclusion: We show that [11C]PK11195 PET imaging can be used to longitudinally monitor MA during demyelination and remyelination in the mouse brain. We also show that MA associated with remyelination is present and detectable at least 3 weeks into the remyelination phase. This provides a window for neuroinflammation modulating treatments, aimed at enhancing remyelination. Combination of [11C]PK11195 and [11C] MEDAS PET imaging may be a powerful instrument for monitoring MS disease progression and treatment effects on MA and CNS myelin content in MS. Research support: STW project 11650 References: 1 Olah, M. et al., Glia 60, 306–321 (2012). 2 De Paula Faria, D. et al., NeuroImage doi:10.1016/j.neuroimage.2013.10.057 46 Session 8 Latest insights form UHasselt Chair: Prof.dr. Jack van Horssen Department of Molecular Cell Biology and Immunology, VU University Medical Center, 1007MB, Amsterdam, The Netherlands. Inez Wens Disturbed skeletal muscle cell biochemistry and composition in multiple sclerosis Authors Inez Wens, Dominique Hansen, Kenneth Verboven, Frank Vandenabeele, Bert O. Eijnde Affiliation REVAL Rehabilitation research center, BIOMED Biomedical research center, Hasselt University, Martelarenlaan 42, 3590 Hasselt, Belgium Abstract BACKGROUND+OBJECTIVE: MS patients are confronted with reduced muscle strength, decreased aerobic capacity and impaired muscle oxidative capacity. In accordance, a smaller m. vastus lateralis type I and II skeletal muscle fiber cross sectional area and a selective type II(a) atrophy were recently reported by our research group. Preliminary data suggest that this type II atrophy may be associated with a fiber type specific decline in satellite cells in MS patients. AMP-activated protein kinase (AMPK) is one of the key skeletal muscle kinases which mediates muscle biochemistry and composition in humans. To explore the etiology for the development of the MS muscle phenotype, muscle AMPK phosphorylation was researched. METHODS: After assessment of body composition, muscle strength and exercise tolerance, muscle fiber type and muscle phospho-AMPKa (m.vastus lateralis biopsy) were assessed in 14 MS patients and 10 healthy controls. RESULTS: Increased muscle phospho-AMPKa concentrations were present in MS (p<0.01) and independently related to MS, despite decreased exercise tolerance and muscle fiber characteristics. Correlations between muscle phospho-AMPKa and wholebody fat mass, peak oxygen uptake, and expanded disability status scale (p<0.05) were found. CONCLUSIONS: Based on these results, it could be hypothesized that inappropriate downstream signalling after muscle AMPKa phosphorylation occurs in MS. In addition, muscle signalling cascades for mitochondrial biogenesis seems altered in MS and related to the impairment and disability level. These findings indicate a link between muscle signalling cascades and the level of disability and impairment, and thus may open a new area for the development of novel therapies for peripheral muscle impairment in MS. 47 Marjan Vanheusden Does CMV trigger CD4+CD28null T-cell expansion in the context of MS? Authors Marjan Vanheusden1, Suzanne Welten², Bieke Broux1, Liesbet M. Peeters1, Ramon Arens², An Goris3, Piet Stinissen1, Niels Hellings1 Affiliation 1Hasselt University, Biomedisch Onderzoeksinstituut, School of Life Sciences, Diepenbeek, Belgium. 2 Leiden University Medical Center, Department of Immunohematology and Blood Transfusion, Leiden, The Netherlands. 3 KULeuven, Laboratory for Neuroimmunology, Section of Experimental Neurology, Leuven, Belgium. Abstract BACKGROUND: Cytotoxic CD4+CD28null T-cells arise during chronic activation of the immune system, in a subset of healthy controls (HC) and patients with multiple sclerosis (MS), a disabling autoimmune disease of the central nervous system. CD4+CD28null T-cells may contribute to MS, since they accumulate in active lesions and at least a subpopulation is autoreactive in nature. OBJECTIVE: Investigate whether CMV triggers CD4+CD28null T-cell expansion and what their role is in the context of MS. METHODS: An association study between CMV serology and CD4+CD28null T-cells in MS patients and HC was performed. In an in vitro assay, PBMCs from HC were stimulated with CMVpp65 and/or IL-2 to mimic chronic CMV stimulation. In vivo, splenocytes from CMV-infected mice were isolated at different time points and analysed via flow cytometry. Furthermore, CD4+CD28null T-cells were studied in experimental autoimmune encephalomyelitis (EAE) and the role of CMV and these cells in CMV infected EAE mice was examined. RESULTS: The association study showed that CD4+CD28null T-cells are increased in CMV+ donors (p<0.0001) and CMV IgG titers correlated with these cells (ρs=0.6, p<0.0001). In vitro stimulation of PBMCs with CMVpp65 +/- IL-2 led to increased CD4+CD28null T-cells in CMV+ HC with in vivo expanded CD4+CD28null T-cells. In CMV infected mice, there is a significant increase of CD4+CD28null T-cells over time (p<0.001). In EAE, CD4+CD28null T-cells were significantly higher compared to control mice. Furthermore, CD4+CD28null T-cells positively correlated with clinical score (ρs=0.42, p=0.008). CMV infected EAE mice had a worse disease course compared to EAE alone (mean cumulative score, p<0.01). At day 30, the percentage of CD4+CD28null T-cells was higher in the CMV+EAE group compared to CMV or EAE alone. CD4+ T-cell responses against MOG are higher in the CMV+EAE group compared to EAE alone (p<0.01). 48 CONCLUSIONS: CMV expands CD4+CD28null T-cells via repeated antigenic challenge and thereby aggravates MS disease. Further studies are warranted, but CMV vaccination to prevent CMV infection and these expansions might be beneficial for people at risk of developing MS. Tim Vanmierlo The role of LXRβ in neuroinflammation Authors T. Vanmierlo*, J. Vanmol* J.F.J. Bogie*, S. Timmermans, K. Nelissen, K. Wouters, H.E. de Vries, J.Å. Gustafsson, K.R. Steffensen, P. Stinissen, N. Hellings, and J.J.A. Hendriks *equal contribution Affiliation Hasselt University Abstract Liver-X-receptors (LXRs) are master regulators of cholesterol turnover and of inflammatory responses. Whereas LXRa is mainly expressed in liver, adipocytes, and immune cells, LXRβ is ubiquitously expressed, being the most prominent isoform in the CNS. Recent findings demonstrated that pan-LXR agonists ameliorate the disease course of experimental autoimmune encephalomyelitis (EAE), the animal model for inflammatory demyelination in multiple sclerosis (MS). Moreover, we previously reported that activation of LXRs by myelin induces a beneficial phenotype in macrophages by suppressing pro- inflammatory mediator production. Here, we determined the contribution of endogenous LXR activation to a neuroinflammatory response by inducing EAE in mice deficient for the LXRa or the LXRβ isoform. Surprisingly, in mice deficient for LXRβ, disease severity and neuroinflammation were strongly reduced in the early disease stages, which was not seen in LXRa deficient mice. This indicates that LXRβ activation can promote neuroinflammation. LXRb deficient mice subjected to EAE display less immune cell infiltration as well as a reduced chemokine production in the CNS. Moreover, this phenotype was independent of LXRb expression in peripheral immune cells. In line with these findings, an LXR agonist induced the expression of chemokines in a microglia, pointing towards a prominent role for microglia in the effect LXRb has on neuroinflammation. These findings indicate that endogenous LXRb activation controls immune cell infiltration into the CNS by inducing chemokine expression in microglia. 49 Session 9 Grey Matter Pathology in MS Chair: dr. Inge Huitinga Department of Neuroimmunology, Netherlands Institute for Neuroscience, Meibergdreef 47, 1105 BA, Amsterdam, The Netherlands Abstract Analysis of more than 4000 tissue blocks sampled through the brains of more than 200 MS patient that came to autopsy in the framework of the NBB revealed a high heterogeneity in lesions distribution and lesion activity between MS patients. Many patients have both white matter and cortical grey matter MS lesions, but some have no cortical grey matte lesions. Interestingly, we found profound gender differences in MS pathology. Significantly more male MS patients have cortical grey matter lesions and a higher active white matter lesion load as compared to females. These pathological features are compatible with the clinical finding that, although less males as compared to females develop MS, males develop more clinically severe MS and males also have more frequently cognitive impairment. Analysis of tissue blocks dissected from the brain stem and hippocampus revealed the presence of a high incidence of mixed white-grey matter lesions. These findings urge further investigation of MS pathology in the cortex and the deep grey matter. Maarten Kole will present a study on changes in axon excitability and expression in anchoring markers (Ankyrin-G, bIV-spectrin) as well as the main axonal voltage-gated ion channels (Nav1.6, Nav1.2, Pan-Nav and Kv7.3) in cortical layer V in cuprizone induced demyelination.1-4 Valeria Ramaglia will present a study on complement associated changes in neurons, axons and synapses in deep grey matter lesions in MS.5,6 1 2 3 4 5 6 50 attefeld A, Tran BT, Gavrilis J, Cooper EC, Kole MH.Heteromeric Kv7.2/7.3 channels B differentially regulate action potential initiation and conduction in neocortical myelinated axons. J Neurosci. 2014; 34:3719-32 Hallermann S, de Kock CP, Stuart GJ, Kole MH. State and location dependence of action potential metabolic cost in cortical pyramidal neurons. Nat Neurosci. 2012 Jun 3;15(7):1007-14. Kole MH, Stuart GJ. Signal processing in the axon initial segment. Neuron. 2012; 73:235-47. Kole MH. First node of Ranvier facilitates high-frequency burst encoding. Neuron. 2011;71:671-82. Michailidou I1, Willems JG, Kooi EJ, van Eden C, Gold SM, Geurts JJ, Baas F, Huitinga I, Ramaglia V.Complement C1q-C3 associated synaptic changes in multiple sclerosis hippocampus. Ann Neurol. 2015 Feb 27.[Epub ahead of print] Ramaglia V, Jackson SJ, Hughes TR, Neal JW, Baker D, Morgan BP. Complement activation and expression during chronic relapsing experimental autoimmune encephalomyelitis in the Biozzi ABH mouse. Clin Exp Immunol. 2015 Jan 23. [Epub ahead of print] Maarten Kole Experimental demyelination causes neuronal hyperexcitability Authors Mustafa S. Hamada1 and Maarten H.P. Kole1,2 Affiliation 1Department of Axonal Signaling, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, 1105 BA, Amsterdam, The Netherlands. 2 Cell Biology, Faculty of Science, Utrecht University, 3584 CH, Utrecht, The Netherlands Abstract BACKGROUND+OBJECTIVE: Axonal myelination and voltage-gated ion channel clustering at the nodes of Ranvier are key components for the rapid saltatory conduction of action potentials. Whether myelination also influences the structural organization of the axon initial segment (AIS) and action potential initiation is, however, poorly understood. Since layer 5 axons in the gray matter of the sensory cortex are typically densely ensheathed with myelin we investigated their structural and functional properties in a toxin demyelination model. METHODS: Male mice were fed 0.2% – 0.3% cuprizone for 5 – 9 weeks to induce demyelination. Layer 5 pyramidal neurons in acute brain slices of the neocortex were filled with Alexa Fluor or biocytin during whole-cell recording and intrinsic excitability including action potential firing was measured. Slices were subsequently stained for intracellular markers, myelin protein (MBP), anchoring markers (Ankyrin-G, bIV-spectrin) as well as the main axonal voltage-gated ion channels (Nav1.6, Nav1.2, Pan-Nav and Kv7.3) allowing correlative analysis of ion channels with the functional recordings. RESULTS: Layer 5 neurons with demyelinated axons showed increased intrinsic excitability, characterized by larger amplitude and increased frequency of spontaneous suprathreshold depolarizations (P < 0.0003) as well as antidromically propagating action potentials ectopically generated in distal parts of the axon (P < 0.005, 27 out of 178 axons). Immunofluorescence examination of demyelinated axons showed that bIV-spectrin, Nav1.6 and the Kv7.3 channels in nodes of Ranvier either dissolved or extended into the paranodal domains. In contrast, anchoring proteins and ion channel expression in AISs were maintained and the intrinsic capacity for single action potential generation was only marginally affected. CONCLUSIONS: These results suggest that myelin loss has a differential impact on AISs and nodes, even within the same demyelinated axon. The functional implications of demyelination is an hyperexcitability of single cells and neural circuits. We hypothesize that myelin loss-induced aberrant excitability comprises a cellular correlate of cognitive impairments in MS. 51 Valeria Ramaglia Complement C1q-C3 associated synaptic changes in multiple sclerosis hippocampus Authors Iliana Michailidou1, Janske G.P. Willems1,2, Evert-Jan Kooi3, Corbert van Eden2, Stefan M. Gold4,5, Jeroen J.G. Geurts3, Frank Baas1, Inge Huitinga2, Valeria Ramaglia1,2* Affiliation 1Department of Genome Analysis, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; 2 Department of Neuroimmunology, Netherlands Institute for Neuroscience, Meibergdreef 47, 1105 BA, Amsterdam, The Netherlands; 3 Department of Anatomy & Neurosciences, VU University Medical Center, De Boelelaan 1118, 1081 HV, Amsterdam The Netherlands; 4 Center for Molecular Neurobiology, University Medical Center Hamburg Eppendorf, Hamburg, Germany; 5 Department of Psychiatry, Charité, Berlin, Germany Abstract BACKGROUND+OBJECTIVE: Multiple sclerosis (MS) is a demyelinating disease of the central nervous system, leading to memory impairment in up to 65% of patients. Memory dysfunction in MS has been associated with loss of synapses in the hippocampus, but its molecular basis is unknown. Accumulating evidence suggest that components of the complement system, C1q and C3, can mediate elimination of synapses. METHODS: To investigate the involvement of complement in synaptic changes in MS, gene and protein expression and localization of C1q and C3 were analyzed in relation to neuropathological changes in myelinated and demyelinated hippocampi from post-mortem MS brains. Findings were compared to hippocampi of Alzheimer’s disease (AD) and non-neurological controls. RESULTS: C1q expression and C3 activation were increased in myelinated and demyelinated MS hippocampi, mainly in the CA3/2 and CA1 subfields, which also showed a marked decrease in synaptic density and increased neuronal staining for the mitochondrial heat shock protein 70 (mtHSP70) stress marker. Neurons were the major source of C1q mRNA. C1q protein and activated C3 localized at synapses within HLA-positive cell processes and lysosomes, suggesting engulfment of complement-tagged synapses by microglia. A significant association (p<0.0001) between the density of C1q and synaptophysin-positive synapses or mtHSP70 was seen in myelinated MS hippocampi, further pointing towards a link between the complement pathway and synaptic changes. In contrast to AD, MS hippocampi were consistently negative for the terminal complement activation complex C5b9. CONCLUSIONS: These data support a role for the C1q-C3 complement axis in synaptic alterations in the MS hippocampus. 52 HOT TOPIC Cognition in MS: From molecules and imaging towards cognitive interventions Chair: Prof.dr. Jeroen Geurts Department of Anatomy and Neuroscience, Neuroscience Campus Amsterdam, VU University Medical Center, The Netherlands Abstract Cognitive impairment occurs in up to 70% of all patients with MS. These cognitive symptoms can influence the patients’ life significantly, varying from minor impairments in daily living to social isolation and unemployment. The neurobiological changes that cause cognitive impairment in MS are still largely unknown. Conventional MRI (i.e. white matter lesion volume, overall brain volume) is too unspecific to understand the presence of cognitive impairment. Stronger correlations can be detected between cognitive impairment and grey matter pathology (i.e. the number of cortical lesions and (deep) grey matter atrophy). Additionally, the use of more advanced imaging techniques, such as functional MRI (i.e. brain activation, brain connectivity) has helped to better understand cognitive decline in MS. These studies suggest that structural damage in the brain may induce a variable extent of functional reorganisation as a token of brain plasticity, which may ‘mask’ clinical symptoms. Additionally, we can now measure the brain network efficiency of individual patients, which strongly relates to cognitive performance. Although the understanding of cognitive impairment in MS has advanced substantially over the last years, at least two major challenges need to be addressed so that we can move from the current situation towards actual cognitive rehabilitation: 1. Further understanding of cognitive decline in MS To improve our understanding of cognitive decline in MS even further, we have to study histopathological correlates of network efficiency, such as synapses, glutamate and GABA. Additionally, we need to study the time course of cognitive impairment in MS, by obtaining longitudinal follow-up information in vivo. Together, these research lines may provide us with more information on what induces the ‘tipping point’, i.e. the moment that cognitively preserved MS patients become cognitively impaired, which could lead to future intervention studies. 2. Start cognitive rehabilitation While we need to expand our understanding of the temporal dynamics and histopathological changes suggestive for cognitive decline in MS, we should simultaneously start exploring potential candidates for cognitive rehabilitation. The key question will be 53 whether it is possible to influence cognitive performance beneficially via several rehabilitation strategies, such as cognitive training, pharmacological intervention and transcranial magnetic stimulation. -B enedict RH, Zivadinov R. Risk factors for and management of cognitive dysfunction in multiple sclerosis. Nat Rev Neurol 2011 Jun;7:332-342. - Rao SM, Leo GJ, Bernardin L, Unverzagt F. Cognitive dysfunction in multiple sclerosis. I. Frequency, patterns, and prediction. Neurology 1991;41:685-691. - Houtchens MK, Benedict RH, Killiany R, et al. Thalamic atrophy and cognition in multiple sclerosis. Neurology 2007 Sep 18;69:1213-1223. - Mainero C, Caramia F, Pozzilli C, et al. fMRI evidence of brain reorganization during attention and memory tasks in multiple sclerosis. Neuroimage 2004 Mar;21:858-867. - Rocca MA, Ceccarelli A, Rodegher M, et al. Preserved brain adaptive properties in patients with benign multiple sclerosis. Neurology 2010 Jan 12;74:142-149. - Rosti-Otajarvi EM, Hamalainen PI. Neuropsychological rehabilitation for multiple sclerosis. Cochrane Database Syst Rev 2011;CD009131. - O’Brien AR, Chiaravalloti N, Goverover Y, DeLuca J. Evidenced-based cognitive rehabilitation for persons with multiple sclerosis: a review of the literature. Arch Phys Med Rehabil 2008 Apr;89:761-769. - Hulst HE, Schoonheim MM, Roosendaal SD, et al. Functional adaptive changes within the hippocampal memory system of patients with multiple sclerosis. Hum Brain Mapp 2012 Oct;33:2268-2280. - Schoonheim MM, Geurts JJ, Barkhof F. The limits of functional reorganization in multiple sclerosis. Neurology 2010 Apr 20;74:1246-1247. - Schoonheim MM, Hulst HE, Brandt RB, et al. Thalamus structure and function determine severity of cognitive impairment in multiple sclerosis. Neurology 2015 Feb 24;84(8):776-83. - Annese J. The importance of combining MRI and large-scale digital histology in neuroimaging studies of brain connectivity and disease. Front Neuroinform 2012 Apr 24;6:13 - Stam CJ, van Straaten EC. The organization of physiological brain networks. Clin Neurophysiol 2012 Jun;123(6):1067-87. - Verret L, Mann EO, Hang GB, et al. Inhibitory interneuron deficit links altered network activity and cognitive dysfunction in Alzheimer model. Cell 2012 Apr 27;149(3):70821. - Bonifazi P, Goldin M, Picardo MA, et al. GABAergic hub neurons orchestrate synchrony in developing hippocampal networks. Science 2009 Dec 4;326(5958):1419-24. - Pitt D, Werner P, Raine CS. Glutamate excitotoxicity in a model of multiple sclerosis. Nat Med 2000 Jan;6(1):67-70. - Chiaravalloti ND, Moore NB, Nikelshpur OM, DeLuca J. An RCT to treat learning impairment in multiple sclerosis: The MEMREHAB trial. Neurology 2013;81:2066-2072. 54 Menno Schoonheim & Geert Schenk Understanding cognitive impairment in MS – brain imaging and histopathology Authors Dr. Menno Schoonheim & Dr. Geert Schenk Affiliation VU medisch centrum Amsterdam Abstract From a research point of view, we still do not fully understand cognitive impairment in MS. Although recent studies have shown specific functional brain changes in MS that are cognitively relevant, we still lack critical longitudinal and histopathological data, strongly limiting the validity of causal claims. What we have observed is that the brain seems to exhibit a so-called “functional reorganization”. This apparently compensatory response is supposed to limit the functional impact of structural damage by changing brain function in MS. This was shown in cognitively preserved patients during specific tasks, where we see that some brain regions are hyperactivated, and that additional regions are recruited. This response is lost in patients with cognitive impairment. Besides the local activation patterns of specific structures, we can also look at the connectivity of individual brain structures, hereby mapping the efficiency of networks in our brain. As the concept of functional reorganization has gained popularity, scientists expected to find beneficial increases in connectivity as well as activity in patients with an intact cognitive performance. Strikingly, virtually all changes in connectivity that have been found in MS, both increases and decreases, have been linked to cognitive dysfunction. Apparently, there is a normal network balance in the brain, and any change in this balance will impact cognitive functioning greatly. What is crucially lacking in the field, however, is longitudinal network imaging. Furthermore, we critically lack histopathological correlates of connectivity changes in MS. By studying the normal balance between excitatory and inhibitory inputs and the structural integrity of individual synapses, we may be able to pinpoint the most important driver of network dysfunction in MS, in a post-mortem setting. To test this, we can relate measures of network efficiency, using post-mortem diffusion tensor imaging (DTI) data, to histopathological markers of synapse efficiency, such as glutamate, GABA and stereological markers. This session will provide an overview of the current network data in MS, focusing on what we can and cannot conclude from the current cross-sectional data. To conclude, we will discuss possible histopathological markers of network efficiency. 55 Neeltje Kant & Hanneke Hulst Treating cognitive impairment in MS – how to move forward? Authors Drs. Neeltje Kant & Dr. Hanneke Hulst Affiliation Nieuw Unicum, Zandvoort / VU medisch centrum Amsterdam Abstract From a clinical practice (neuropsychologist), two patients will be presented to the audience. Issues as the most common cognitive deficits in MS and how these cognitive deficits influences the daily functioning of these patients will be discussed. Also, the current psycho-educational programs and strategies to compensate for deficits that are currently available will be briefly mentioned. Although the latter will be able to help to improve the quality of life of patients with MS suffering from cognitive deficits, it will not give them their original function back (also called, re-training). The field of cognitive rehabilitation in MS is currently moving forward. One of the key questions is whether it will be possible to influence cognitive performance beneficially via several rehabilitation strategies such as cognitive training, pharmacological intervention, and transcranial magnetic stimulation. The main goal will be to improve cognitive functioning (i.e. re-train cognitively impaired MS patients) or to prevent cognitive impairment to occur (i.e. cognitively preserved MS patients). Until now, cognitive rehabilitation studies in MS are limited and largely report contradicting results. The inconsistency of the results is most likely due to methodological issues, such as relatively small sample sizes, inadequately defined groups (i.e. too liberal criteria for cognitive impairment) and incorrect matching. This conclusion was confirmed by a clinical trial by one of the leading groups in the field, which showed that improved learning and memory performance as a result of a memory-training program was uniquely found in moderately cognitively impaired patients. The mildly impaired individuals did not show any effect from the training. Future studies need to pay careful attention to tackle these methodological problems. Novel cognitive interventions and approaches to improve patients cognitive functioning will be presented. This includes amongst others an 7-week computerized attention training and a dance-cognition intervention. At the end of this special session on cognition, the audience will be able to describe: 1. the most common cognitive problems MS patients experience; 2. the currently available psycho-educational and compensational strategies; 3. the working hypothesis for cognitive rehabilitation and functional reorganisation; 4. the potential successful cognitive interventions for cognitive impairment in MS. 56 Poster overview nr Name and title 1 Navina Chrobok Tissue Transglutaminase in leukocytes that infiltrate the spinal cord during experimental multiple sclerosis 59 2 Malou Janssen A new tool to study antigen specificity of B lymphocytes in the CNS 61 3 Claudio Derada Troletti Molecular regulation of the Blood-Brain Barrier phenotype 63 4 Claudio Sestito Regulation of tissue Transglutaminase expression and activity in human monocytes and macrophages: implication in Multiple Sclerosis 65 5 Kim Meijer White matter tract abnormalities are associated with cognitive dysfunction in secondary progressive multiple sclerosis 67 6 Jeroen Bogie Myelin alters the inflammatory phenotype of macrophages by activating PPARs and LXRs 69 7 Winde Jorissen An altered lipoprotein profile underlying disease pathology in a subgroup of RRMS patients 71 8 Jo Mailleux Liver x receptor activation in ms lesions 73 9 Mustafa Hamada Myelin loss induces hyperexcitability of gray matter axons 74 Martijn Steenwijk Unraveling the relationship between regional gray matter atrophy and pathology in connected white matter tracts in long-standing multiple sclerosis 76 11 Liza Rijvers Increased CLIP expression on CD21low B-cell subsets indicating reduced HLA-II antigen presentation efficiency in MS 77 12 Anne-Hilde Muris Vitamin D status does not influence disability progression of multiple sclerosis patients over three years follow-up 79 13 Jasmine Vanmol Relation between LXR activation and blood-brain barrier function during neuroinflammation in multiple sclerosis 80 10 Abstract on page 57 Poster overview 58 nr Name and title Abstract on p 14 Natalia Ochocka Differential responsiveness of white and grey matter-derived glial cells in vitro 81 15 Rosa Boeschoten Prevalence of Depression and Anxiety in Multiple Sclerosis: A systematic review 82 16 Arne Battefeld Satellite oligodendrocytes produce myelin and limit neuronal excitability by activity-dependent potassium buffering 84 17 Tess Dhaeze Human circulating follicular regulatory T cells are impaired in multiple sclerosis 85 18 Karim Kreft MS risk genes are associated with enhanced EBNA-1 humoral immune response independent of HLA-DR 87 19 Laura de Bock Anti-SPAG16 antibodies in multiple sclerosis 88 20 Jordon Dunham EBV: a new role in MS 90 21 Judith Fraussen The importance of costimulation and antigen presentation by B cells in multiple sclerosis 91 22 Benthe Westerik Sleep problems and cognition in Multiple Sclerosis. 92 23 Quinten van Geest eMotionS: emotional memory impairment and amygdala activation in multiple sclerosis 93 Poster Abstracts P1 Tissue Transglutaminase in leukocytes that infiltrate the spinal cord during experimental multiple sclerosis AuthorsNL Chrobok1, ENTP Bakker3, S van der Pol2, HE de Vries2, KK Fenrich4, F Debarbieux4, MMM Wilhelmus1, C Sestito1, B Drukarch1 and A-M van Dam1 Affiliation VU University Medical Center, 1 Department of Anatomy and Neurosciences 2 Department of Molecular Cell Biology and Immunology, Amsterdam, The Netherlands 3 Academic Medical Center, Department of Biomedical Engineering and Physics, Amsterdam, The Netherlands 4 Institut de Biologie du Developpement de Marseille-Luminy, Université de la Méditerranée, Marseille, France Abstract Background + objective: A pathological hallmark of Multiple sclerosis (MS) is the infiltration of leukocytes into the central nervous system. They serve as a source of inflammatory mediators contributing to activation of glial cells and further cell recruitment which ultimately results in demyelination and axonal loss. One approach to prevent these pathological processes is to avert the infiltration of leukocytes. Tissue Transglutaminase (TG2) is a multifunctional enzyme whose expression and activity is enhanced during inflammatory processes. TG2 has been shown to be involved in monocyte adhesion/migration in vitro and we observed increased expression in infiltrated cells in human active white matter lesions. The aims of this project are to determine (1) if TG2 is of importance for clinical deficits in a mouse experimental autoimmune encephalomyelitis (EAE) model and (2) to visualize infiltrating myeloid cells and local microglia in vivo in mouse spinal cord during EAE. Methods: EAE using MOG35-55 was induced in TG2-/- mice (C57Bl/6) and wildtype littermates. For imaging a permanent window was fixed on top of the spinal cord of CX3CR1-GFP mice before EAE was induced and followed up by intravital 2-photon microscopy. Results: We observed that clinical symptoms and the maximal clinical score were significantly reduced in TG2-/- compared to wildtype mice. Using intravital video 2-photon microscopy, we found numerous GFP positive cells in the white matter around the imaged blood vessel in the spinal cord. This GFP signal increased during disease course. GFP positive cells were also found in the circulation as well as crawling on the lumen of blood vessels. Post-mortem immunohistochemical analysis revealed that various GFP positive leukocytes had infiltrated the spinal cord. GFP positive cells were co-localizing with macrophages/microglia, and not with T cell markers. In addition, a fraction of the GFP-positive cells showed TG2 immunoreactivity. 59 Poster Abstracts Conclusions: We conclude that TG2 plays a role in the development of clinical mouse EAE, and is present in infiltrating leukocytes. TG2 is therefore an interesting potential therapeutic target in EAE/MS treatment. To further address the role of TG2 in infiltrating leukocytes during EAE, specific inhibitors for TG2 activity will be administered to CX3CR1-GFP mice. The effects TG2 inhibition on interaction of myeloid cells with spinal cord endothelium will be visualized using intravital video microscopy. 60 Poster Abstracts P2 A new tool to study antigen specificity of B lymphocytes in the CNS Authors Malou Janssen1,2, Gijsbert P. van Nierop1,3, Mark J. Kwakkenbos4, Hatice Orhan1, Marvin M. van Luijn2, Georges M.G.M. Verjans3, Rogier Q. Hintzen2 1 AffiliationDept Neurology, MS center ErasMS, Erasmus MC, University Medical Centre,Rotterdam. 2 Dept Immunology, MS center ErasMS, Erasmus MC, University Medical Centre,Rotterdam. 3 Viroscience, Erasmus MC, University Medical Centre,Rotterdam. 4 AIMM therapeutics, Amsterdam Abstract Background + objective: Growing evidence suggest B cell involvement in multiple sclerosis pathology. Clonal populations have been demonstrated intrathecally. These cells underwent somatic hypermutation, a result of local continuous antigen driven activation. Until now, it is not known which (auto) antigens drive this process. In this project, B cells derived from different body compartments of both early and end-stage MS patients (lesion, NAWM, meninges, CSF and blood) will be immortalized, enabling us to unravel the antigenic targets of the Ig produced, focusing at both previously suggested suspects and antigen discovery. Methods: A novel immortalization technique will be applied. B cells are forced to express genes that are normally active in the germinal center reaction: BCL-xL and BCL-6, to prevent their apoptotic fate and terminal differentiation into plasma cells. The gene construct is coupled to a GFP reporter, enabling detection and sorting of successfully transduced cells. Co-stimulation for Ig production is provided via IL-21 and CD40L expressing feeder cells. The expression of the B-cell receptor in these immortalized cells is maintained, which enables us to obtain sufficient amounts of Ig from the original CNS B cells for further characterization and to perform functional studies (e.g. antigen presenting capacities) using simultaneously generated matched T-cell lines. Results: Ideally, the immortalization procedure is done after sorting of relevant B-cell subsets. However, the B cell counts from the compartments we study here are low. Therefore we are at the process of validating the original method without the B cell pre-sorting step, using mixed populations of lymphocyte subsets. In addition, we checked the reported necessity for pre-activation before the immortalization process, since we want to prevent activation-induced cell death by ex vivo overstimulation of the already in vivo activated, quite differentiated B cells. Using both confocal microscopy and cell sorting, GFP-expressing cells were identified in our cultures, proving successful immortalization of lymphocytes. 61 Poster Abstracts Conclusions: With some modifications of the original validated immortalization protocol, we were able to successful immortalize B cells obtained from several compartments. We have now set the stage for further cell culture and functional characterization of B cells derived from brain, blood and CSF of MS patients and controls. 62 Poster Abstracts P3 Molecular regulation of the Blood-Brain Barrier phenotype Authors: C. Derada Troletti1, W.W Kamphuis1, A. Reijerkerk2, B. Van Het Hof AJ1, I.A. Romero3 and H.E de Vries1 1 AffiliationBlood-brain barrier research group, Department of Molecular Cell Biology and Immunology, Neuroscience Campus Amsterdam, VU Medical Centre, P.O. Box 7057, 1007 MB Amsterdam, The Netherlands 2 Pluriomics therapeutics, Galileiweg 8, 2333 BD Leiden, The Netherlands 3 Biomedical Research Network, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK Abstract Background + objective: Multiple sclerosis (MS) is a progressive inflammatory disease of the central nervous system (CNS) characterized by inflammation, immune cell infiltration into the CNS, demyelination and ultimately axonal loss. An early event in MS is the impairment function of the blood-brain barrier (BBB) which consists of specialized brain endothelial cells (BECs) supported by surrounding glial cells. Both inflammation and BBB dysfunction are pathological hallmarks of MS and affect brain homeostasis. Endothelial to mesenchymal transition (EndoMT) is a dynamic process that has been linked to pathological setting like cancer and fibrosis. During EndoMT, endothelial cells dedifferentiate into mesenchymal cells and as a result lose their tight and adherens junction, which are essential for the BBB integrity. The EndoMT process is known to be induced by TGF-β which can upregulate two important transcription factors: Snail1 and Snail2. Furthermore, recent discoveries unravelled a critical role for microRNAs (miRNA) in controlling the function of the barrier endothelium in the brain. Interestingly, both Snail1 and Snail2 are both predicted target of miRNA-30c, and we have previously shown that this miRNA is highly downregulated both in MS patients as well as in inflamed human brain endothelial cells (hCMEC/D3). We believe that TGF-β can induced EndoMT in BECs and this event can play an important role in the alteration of the BBB phenotype. Moreover, we think that a miRNA based approach could restore the normal BBB phenotype by inhibiting the dedifferentiation of the BECs via targeting Snail1 and Snail2. Methods: To investigate the EndoMT process, hCMEC/D3 were stimulated for 48 hours with 10ng/ml of TGF-β and IL-1β. qPCR and western blot were used to analyze gene and protein expression. Results: Our preliminary data show that TGF-β and IL-1β can induce EndoMT in hCMEC/D3 which can be demonstrated by the loss of expression of brain endothelial markers and a gain in expression of mesenchymal markers. Moreover, Snail1 and Snail2 were upregulated in treated hCMEC/D3. 63 Poster Abstracts Conclusions: Our findings suggest that EndoMT can be involved in the BBB breakdown and participate in the pathogenesis of MS. Moreover, repair of a disturbed BBB through a specific miRNA approach may represent a novel avenue for effective treatment of MS. 64 Poster Abstracts P4 Regulation of tissue Transglutaminase expression and activity in human monocytes and macrophages: implication in Multiple Sclerosis Authors C Sestito1, JJP Brevé1, PJ van den Elsen2,3, MMM Wilhelmus1, NL Chrobok1, B Drukarch1 and A-M van Dam1 Affiliation1Department of Anatomy and Neurosciences, VU University Medical Center, Amsterdam, the Netherlands 2 Department of Pathology, VU University Medical Center, Amsterdam, the Netherlands 3 Department of Immunohematology and Blood Transfusion, Leiden, the Neth erlands Abstract Background + objective: Multiple sclerosis (MS) is a chronic neuroinflammatory disease of the central nervous system (CNS). Although the pathogenesis is still not clear, it is known that leukocytes from the circulation adhere to the brain endothelium and migrate into the CNS where they can stimulate local glial cells to produce inflammatory factors. Tissue Transglutaminase (TG2) is a multifunctional enzyme that has been shown to play a role in monocyte/macrophage adhesion and migration onto extracellular matrix proteins in vitro, which are processes relevant in MS pathology. Previously, we observed the appearance of TG2 in monocytes in active human post-mortem MS lesions in the CNS. In the present study we questioned whether TG2 expression and activity were regulated in human monocytes and macrophages by inflammatory mediators and whether TG2 expression was altered in MS patient-derived monocytes. Methods: mRNA expression levels in MS patient and control subject derived monocytes were measured by semi-quantitative RT-PCR (qPCR). Human THP1 monocytes and THP1-derived macrophages were treated with various inflammatory mediators for 24h and protein and mRNA expression were detected by western blotting and qPCR, respectively. Moreover, the transglutaminase cross-linking activity was measured by the Covalab assay. THP1 monocytes were transduced with lentiviral TG2 shRNA to silence TG2 expression for subsequent functional studies. Results: TG2 mRNA levels were significantly up-regulated in MS patient-derived monocytes compared to control subject-derived monocytes while Factor XIIIa mRNA levels remained unaffected. Furthermore, IL-1β mRNA levels were significantly down-regulated in MS patient-derived monocytes while CD16 and CD14 mRNA levels were significantly up-regulated. Of interest, TG2 mRNA levels correlated positively with CD16 and with CD14 mRNA levels. THP1 monocytes and THP1-derived macrophages upregulated TG2 expression after treatment with the anti-inflammatory cytokine IL-4 and not by e.g. LPS. 65 Poster Abstracts At the functional level, the ability of monocytes to adhere onto fibronectin and the capability of monocyte-derived macrophages to differentiate into anti-inflammatory macrophages (M2a) was reduced when TG2 expression was silenced. Conclusions: In conclusion, our data show that TG2 in human monocytes and monocyte-derived macrophages is up-regulated by the anti-inflammatory cytokine IL-4, and suggest that the enhanced TG2 expression in MS patient-derived monocytes might be mediated by anti-inflammatory stimuli. 66 Poster Abstracts P5 White matter tract abnormalities are associated with cognitive dysfunction in secondary progressive multiple sclerosis Authors: Kim A. Meijer1,2, Nils Muhlert2,3, Mara Cercignani4, Varun Sethi2, Maria A. Ron2, Alan J. Thompson2,5, David H. Miller2,5, Declan Chard2,5, Jeroen J.G. Geurts1, Olga Ciccarelli2,5 1 Affiliation Department of Anatomy and Neurosciences, VU University Medical Centre, Amsterdam, The Netherlands 2 NMR Research Unit, Queen Square MS Centre, University College London Institute of Neurology, London, United Kingdom 3 School of Psychology and Cardiff University Brain Research Imaging Centre, Cardiff University, Cardiff, United Kingdom 4 Clinical Imaging Centre, Brighton and Sussex Medical School, Brighton, United Kingdom 5 NIHR University College London Hospitals Biomedical Research Centre, London, United Kingdom Abstract Background + objective: Whilst our knowledge of white matter (WM) pathology underlying cognitive impairment in relapsing remitting MS (RRMS) is increasing, equivalent understanding in those with secondary progressive (SP) MS lags behind. This study examines whether the extent and severity of WM damage within major tracts, independent of normalized grey matter volume (GM), differs between SPMS patients with and without cognitive impairment. Methods: Conventional magnetic resonance imaging (MRI) and diffusion MRI were acquired from 30 SPMS patients and 32 healthy controls. Cognitive assessment included comprehensive testing spanning five cognitive domains that are commonly affected in MS patients. To investigate predictors of cognition in SPMS, backward stepwise linear regression was used. Patients were defined as cognitively impaired when their cognitive test score was at least 2 standard deviations (SD) below that of controls on a minimum of 2 out of 5 tested cognitive domains. Tract based spatial statistics (TBSS) was used to compare diffusion measures between groups. Furthermore, we mapped the extent and severity of WM damage. Analyses were adjusted for normalized GM volume. Results: Cognitive performance in SPMS was significantly predicted by WM integrity, premorbid IQ and gender (R2 = 0.38, p = 0.001). Relative to healthy controls, SPMS patients showed a widespread loss of WM integrity, reflected by reduced fractional anisotropy (FA) and elevated axial diffusivity (AD), radial diffusivity (RD) and mean diffusivity 67 Poster Abstracts (MD), both within and outside hyperintense T2 WM lesions. Out of the 30 SPMS patients, 12 patients were defined as cognitively impaired. More extensive and severe damage of association fibers, including the fornix, superior longitudinal fasciculus and anterior thalamic radiation, was observed in cognitively impaired patients, when compared with cognitively preserved patients. Conclusions: Cognitive dysfunction in SPMS is associated with more severely and extensively damaged WM tracts, even after controlling for GM pathology. Damage to association fibres may be particularly important for cognitive function in SPMS patients. 68 Poster Abstracts P6 Myelin alters the inflammatory phenotype of macrophages by activating PPARs and LXRs Authors Jeroen FJ Bogie1, Winde Jorissen1, Jo Mailleux1, Silke Timmermans1, Vân Anh Huynh-Thu2, Alexandre Irrthum2, Hubert J. M. Smeets3, Philip G Nijland4, Noam Zelcer5, Jan-Åke Gustafsson6, Tim Vanmierlo1, Knut R. Steffensen6, Jack van Horssen4, Monique Mulder7, Piet Stinissen1, Niels Hellings1 and Jerome JA Hendriks1. 1 AffiliationBiomedical Research Institute, School of Life Sciences, Hasselt University / Transnational University Limburg, Diepenbeek, Belgium. 2 University of Liège, GIGA-Research, Bioinformatics and Modeling, Liège, Belgium 3 Department of Genetics en Celbiology, Schools for Cardiovascular Research and for Oncology and Developmental Biology, Maastricht UMC+, Maastricht, The Netherlands 4 Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, The Netherlands. 5 Department of Medical Biochemistry, Amsterdam Medical Center, Amsterdam, The Netherlands. 6 Department of Biosciences and Nutrition, Karolinska Institutet, Stockholm, Sweden 7 Division of Pharmacology, Vascular and Metabolic Diseases, Department of Internal Medicine, Rotterdam University, Rotterdam, The Netherlands Abstract Foamy macrophages, containing myelin degradation products, are abundantly found in active multiple sclerosis (MS) lesions. Recent studies have described an altered phenotype of macrophages after myelin internalization. However, mechanisms by which myelin affects the phenotype of macrophages and how this phenotype influences lesion progression remain unclear. We demonstrate that myelin reduces nitric oxide and IL-6 production by macrophages through activation of peroxisome proliferator-activated receptor β/δ (PPARβ/δ) and liver X receptor β (LXRβ), respectively. Furthermore, phosphatidylserine, a phospholipid found in myelin, reduces nitric oxide production through activation of PPARβ/δ. In experimental autoimmune encephalomyelitis (EAE), an animal model for MS, uptake of PS by macrophages suppresses the production of inflammatory mediators and reduces disease severity. The protective effect of PS in EAE animals is associated with a reduced immune cell infiltration into the central nervous system and decreased splenic cognate antigen specific proliferation. Interestingly, PPARβ/δ is activated in foamy macrophages in MS lesions, indicating that myelin also activates PPARβ/δ in macrophages in the human 69 Poster Abstracts brain. Our data show that myelin modulates the phenotype of phagocytes by PPAR and LXR activation, which may subsequently dampen MS lesion progression. Moreover, our results suggest that myelin-derived PS mediates PPAR activation in macrophages after myelin uptake. The immunoregulatory impact of naturally-occurring myelin lipids may hold promise for future MS therapeutics. 70 Poster Abstracts P7 An altered lipoprotein profile underlying disease pathology in a subgroup of RRMS patients Authors Winde Jorissen1, E. Wouters1, JFJ. Bogie, B. van Wijmeersch2, D. Sviridov3, P. Stinissen1, N. Hellings1, V. Somers1, T. Vanmierlo1, M. Mulder4, AT. Remaley3 and JJA. Hendriks1 1 Affiliation Hasselt University, Biomed, Diepenbeek, Belgium 2 Revalidation and MS Center, Overpelt, Belgium 3 NIH, Dept. of Laboratory Medicine, Clinical Center, Bethesda, United States 4 Erasmus MC, Vasc. and Met. diseases, Rotterdam, the Netherlands Abstract Background + objective: Macrophages are major effector cells in multiple sclerosis (MS). Depending on environmental stimuli, more pro- or anti-inflammatory phenotypes of macrophages occur that contribute to respectively tissue injury or tissue repair processes. In MS, lipoprotein levels in the blood are altered. Moreover, an association between plasma lipoprotein levels and neurologic events in MS patients is reported. Interestingly, lipoproteins influence the inflammatory phenotype of monocytes in the blood. In atherosclerosis, high density lipoprotein (HDL) is known to beneficially influence the disease status by inducing cholesterol efflux in macrophages which is accompanied by an anti-inflammatory phenotype in these cells. In this study we aim to determine the interaction between changes in lipoproteins in the blood, their influence on the phenotype and function of monocytes and subsequently on disease progression. Methods: Fasting plasma samples were collected from healthy controls, relapsing remitting MS (RRMS) patients and progressive MS patients. Detailed lipoprotein profiles were determined in plasma samples with NMR spectroscopy. Plasma samples were converted to serum by defibrination and serum cholesterol efflux capacity was measured in vitro using 3H cholesterol-labeled baby hamster kidney (BHK) cells expressing the mifepristone-inducible human ABCG1 transporter. Statistical analyses were performed using SAS by fitting univariate multiple regression models for each response. Results: Our data show that RRMS patients but not progressive MS patients have an atherogenic, diabetic dyslipidemic lipoprotein profile. More specific, RRMS patients with a low BMI have increased amounts of small HDL particles. This is accompanied with a higher insulin resistance index and consequently increased levels of triglycerides (TG) and more and TG-richer VLDL particles. Importantly, the amount of small HDL particles in RRMS patients with a low BMI was strongly negatively correlated with serum cholesterol efflux capacity via the ABCG1 transporter. 71 Poster Abstracts Conclusions: In summary, our data indicate that the lipoprotein profile of a subgroup of RRMS patients is modified towards a more atherogenic, diabetic dyslipidemic profile which is associated with a reduced capacity for cholesterol efflux via the ABCG1 transporter. 72 Poster Abstracts P8 LIVER X RECEPTOR ACTIVATION IN MS LESIONS Authors: Jo Mailleux1, Tim Vanmierlo1, Jeroen Bogie1, Elien Wouters1, Piet Stinissen1, Jerome Hendriks1, Jack van Horssen2 1 AffiliationImmunology & biochemistry, Hasselt University, Diepenbeek 2 Molecular Cell Biology and Immunology, VUmc Amsterdam, Amsterdam Abstract Background + objective: Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS). It is pathologically characterized by infiltrating macrophages that destroy the myelin sheaths. Myelin consists for a large part of cholesterol and myelin breakdown causes an overload of cholesterol and oxysterols in macrophages. These oxidized derivatives of cholesterol are able to activate liver X receptors (LXRs), which will lead to the subsequent induction of genes involved in cholesterol efflux, including ABCA1, ABCG1 and APOE. Previously, we demonstrated that myelin activates LXRs in primary murine macrophages. Methods: In this study we used real-time quantitative PCR (qPCR) and immunohistochemistry (IHC) to determine the expression of LXRs and their response genes in human phagocytes after myelin phagocytosis and in MS lesions. Results: Myelin ingestion induced the LXR response genes ABCA1 and ABCG1 in human monocyte derived macrophages, demonstrating myelin activates LXRs in human phagocytes. We found that both ABCA1 and APOE gene expression and protein levels are highly upregulated in active MS lesions compared to healthy controls. MHCII-positive infiltrating macrophages and microglia in active lesions are positive for ABCA1 and APOE, indicating LXRs are activated in these myelin phagocytosing cells. LXRα is mainly present on MHCII+ cells while LXRβ is predominantly observed in perilesional astrocytes. Conclusions: Our findings indicate that LXRs are activated in phagocytes and perilesional astrocytes in active MS lesions. Future studies are needed to determine the impact of LXR activation on infiltrating and residential CNS celtypes. 73 Poster Abstracts P9 Myelin loss induces hyperexcitability of gray matter axons Authors M.S. Hamada1 and M.H.P. Kole1,2 1 Affiliation Axonal Signalling Group, Netherlands Institute for Neuroscience, KNAW, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands 2 Cell Biology, Faculty of Science, University of Utrecht Abstract Background + objective: Loss of sodium (Na+) channels at the nodes of Ranvier and increased lateral expression in internodes are major hallmarks of myelin loss known to cause impairment of action potential conduction and predisposing axons to injury. While most previous studies on demyelination focus on white matter fibre tract, the impact of demyelination on the gray matter and axon initial segment (AIS), which is the primary site for action potential initiation, remains elusive. Methods: Here, we used the cuprizone toxin mouse model for gray matter demyelination. Six weeks old male mice were put on 0.2% or 0.3% cuprizone mixed with powder food for 5 or 9 weeks, respectively. After treatment mice were anaesthetized and parasagittal brain slices were prepared from the cortex. Immuno-labelling of myelin basic protein (MBP) in the somatosensory cortex revealed that myelin loss was most prominent in the layers 5 and 6. In order to analyse the functional and structural properties of single demyelinated neocortical layer 5 axons we combined in vitro electrophysiological recordings with immunofluorescence of the voltage gated ion channels subunits and anchoring proteins from the same cell. Results: The anchoring proteins and Na+ channels of the AIS in demyelinated axons relocated to a more proximal position near the soma. In contrast, the potassium channel Kv7.3 diffused into the first demyelinated internode. Demyelination was also accompanied by diffuse lateral expression and loss of ion channels around branch points of identified layer 5 axons. Somatic whole-cell current-clamp recordings showed that demyelinated neurons displayed a ~3-fold increase in spontaneous suprathreshold depolarizations as well as an increase in high-frequency firing. Furthermore, demyelination of layer 5 axons induced ectopic action potentials, arising in distal parts of the axon, which invaded the soma in an anterograde direction. Conclusions: Taken together, this study reveals for the first time that demyelination of gray matter circuits is accompanied by an increase in intrinsic neuronal excitability and aberrant network excitation. Hyperexcitability may significantly deteriorate the spatio-temporal structure of information encoding in the neocortex and provides new insights into the cellular origin of cognitive impairments in multiple sclerosis. 74 Poster Abstracts This investigation was supported by grants from the National Multiple Sclerosis Society (RG 4924A1/1) and European Research Council under the European Community’s Seventh Framework Programme (FP7), ERC-StG #261114. 75 Poster Abstracts P10 Unraveling the relationship between regional gray matter atrophy and pathology in connected white matter tracts in long-standing multiple sclerosis. Authors Steenwijk MD1; Daams M1,2; Pouwels PJW3; Balk LJ4; Tewarie PK4; Geurts JJG1,2; Barkhof F1; Vrenken H13 Affiliation Neuroscience Campus Amsterdam, VU University Medical Center, The Netherlands 1 Department of Radiology and Nuclear Medicine, 2 Department of Anatomy and Neurosciences, 3 Department of Physics and Medical Technology, 4 Department of Neurology abstract Background + objective: Gray matter (GM) atrophy is common in multiple sclerosis (MS), but the relationship with white matter (WM) pathology is largely unknown. Some studies found a co-occurrence in specific systems, but a regional analysis across the brain in different clinical phenotypes is necessary to further understand the disease mechanism underlying GM atrophy in MS. Therefore, we investigated the association between regional GM atrophy and pathology in anatomically connected WM tracts. Methods: Conventional and diffusion tensor imaging was performed at 3T in 208 patients with long-standing MS and 60 healthy controls. Deep and cortical GM regions were segmented and quantified, and both lesion volumes and average normal appearing WM fractional anisotropy of their associated tracts were derived using an atlas obtained by probabilistic tractography in the controls. Linear regression was then performed to quantify the amount of regional GM atrophy that can be explained by WM pathology in the connected tract. Results: MS patients showed extensive deep and cortical GM atrophy. Cortical atrophy was particularly present in frontal and temporal regions. Pathology in connected WM tracts statistically explained both regional deep and cortical GM atrophy in relapsing-remitting (RR) patients, but only deep GM atrophy in secondary-progressive (SP) patients. Conclusions: In RRMS patients, both deep and cortical GM atrophy were associated with pathology in connected WM tracts. In SPMS patients, only regional deep GM atrophy could be explained by pathology in connected WM tracts. This suggests that in SPMS patients cortical GM atrophy and WM damage are (at least partly) independent disease processes. 76 Poster Abstracts P11 Increased CLIP expression on CD21low B-cell subsets indicating reduced HLA-II antigen presentation efficiency in MS Authors Liza Rijvers1, Jeanet M. Hogervorst1, Marie-José Melief1, Annet WierengaWolf1, Rogier Q. Hintzen2, Marvin M. van Luijn1 Affiliation MS Center ErasMS, Erasmus MC, University Medical Center, Rotterdam, The Netherlands 1 Department of Immunology 2 Department of Neurology abstract Background + objective: B-cell depletion with rituximab in MS patients exhibits a strong therapeutic effect, underlining the central role of B cells in MS. Interestingly, peripheral but not central B-cell tolerance is defective in MS, leading to an enhanced activation of B cells. Because B cells are capable of presenting autoantigens and the HLA class II (HLA-II) locus is the strongest genetic risk factor in MS, we hypothesize that HLA-II antigen presentation by selected B cell subsets is abnormally regulated in MS. Methods: We analysed the class II-associated invariant chain peptide (CLIP)/HLA-DR surface expression ratio, a measure for antigen presentation efficiency, on 12 B-cell subsets in peripheral blood of 10 healthy donors, as well as 20 MS patients and 20 ageand gender-matched healthy controls using 12-color flow cytometry. Next, we selected 20 genes associated with MS and autoimmunity, which potentially play a role in antigen processing and presentation. Relative mRNA levels of these genes were correlated to CLIP/ HLA-DR expression in 8 EBV+ and 7 EBV- human B-cell lines. Results: In contrast to other B-cell subsets, high CLIP/HLA-DR ratios were found in healthy donors especially for B cells with low expression of CD21 (EBV receptor), including CD38dim (anergic/autoreactive) and CD38highCD24high (transitional) subsets. In addition, CLIP expression on CD21low transitional B-cells of MS patients was significantly increased compared to CD21high transitional B cells (p<0.05) and naïve B cells (p<0.0001). CLIP expression was also significantly increased in EBV+ B cell lines (P=0.011) when compared to EBV- B cell lines. Furthermore, we already found correlations of several of our selected genes with both the CLIP/HLA-DR ratio and CD21 expression. For example, SPPL2a correlated in EBV+ (R2=0.671, p=0.046; R2=0.637, p=0.057, respectively), but not EBV- B-cell lines (R2=0.061. p=0.637; R2=0.058, p=0.645, respectively). Conclusions: We found a higher CLIP/HLA-DR ratio in CD21low CD38dim and CD21low transitional B cells in MS, suggesting less efficient antigen presentation. 77 Poster Abstracts The association of CLIP/DR with CD21 and certain risk genes related to HLA-II in EBV+ B-cell lines only warrants further investigation. We will explore whether active modulation of these risk genes during B cell activation will have an effect on HLA-II antigen presentation efficiency. 78 Poster Abstracts P12 Vitamin D status does not influence disability progression of multiple sclerosis patients over three years follow-up Authors Anne-Hilde Muris1,2, Joost Smolders2*, Linda Rolf1,2, Lieke Klinkenberg3, Noreen van der Linden3, Steven Meex3, Jan Damoiseaux3, Raymond Hupperts1,2 1 AffiliationSchool for Mental Health and Neuroscience, Maastricht University Medical Center, Maastricht, the Netherlands; 2 Academic MS Center Limburg, Orbis Medical Center, Sittard, the Netherlands; 3 Central Diagnostic Laboratory, Maastricht University Medical Center, Maastricht, the Netherlands; *Current address: Department of Neurology, Wilhelmina Canisius Hospital, Nijmegen, the Netherlands Abstract Introduction: The risk of developing multiple sclerosis (MS) as well as MS disease activity is associated with vitamin D (25(OH)D) status. The relationship between the main functional disability hallmark of MS, disability progression, and 25(OH)D status is less well established though, especially not in progressive MS patients. Material and Methods: This retrospective longitudinal study included MS patients with a baseline 25(OH)D serum level and Expanded Disability Status Scale (EDSS) with a minimum follow-up of three years. Logistic and multinominal regression were performed to assess the effect of baseline 25(OH)D on relapse rate. Multilevel analyses were performed to assess the effect on disability and disability progression. Results: 54 patients (61% RRMS, 27% SPMS, 11% PPMS, and a male:female ratio of 29:71) were included. The mean EDSS at baseline was 3.8, with a mean relapse rate of 0.95 and a mean uncorrected 25(OH)D level of 57.5 nmol/L. Baseline deseasonalized 25(OH)D levels predicted subsequent relapse risk (yes/no; OR=0.96, p=0.015) and EDSS (p=0.005), but did not predict EDSS progression (β=0.00008, p=0.712) whereas MS phenotype did (β SPMS compared to RRMS=-0.0271, p=0.02). Discussion and conclusion: 25(OH)D status within the physiological range predicts the occurrence of relapses and EDSS, but does not contribute significantly to EDSS progression in established MS. According to our data, only MS phenotype per se predicts EDSS progression. Whether high dose supplementation to supra physiological 25(OH)D levels could still help to prevent disability progression in MS should become clear from long term follow-up of supplementation studies. Keywords: disease progression, multiple sclerosis, vitamin D 79 Poster Abstracts P13 Relation between LXR activation and blood-brain barrier function during neuroinflammation in multiple sclerosis Authors:J. Vanmol1, T. Vanmierlo1, J.F.J. Bogie1, S.M.A. van der Pol2, W.W. Kamphuis2, P. Stinissen1, N. Hellings1, H.E. de Vries2, J.J.A. Hendriks1 1 Affiliation Hasselt University, Biomedical Research Institute, School of Life Sciences, Diepenbeek, Belgium 2 Department of Molecular Cell Biology and Immunology, Neuroscience Cam pus Amsterdam, VU University Medical Center, Amsterdam, the Netherlands Abstract Background + objective: Multiple sclerosis (MS) is a demyelinating disease of the central nervous system (CNS), featured by an early disruption of the blood-brain barrier (BBB). Cerebral endothelial cells (CECs) tightly regulate BBB function and are regarded as the gatekeepers of the CNS. Changes in BBB properties comprise alterations in the tight and adherens junctions, differences in CEC adhesion molecule expression, and modulated chemoattraction of leukocytes. At the crossroads of linking metabolic and inflammatory responses are the liver X receptors (LXRs). In this study, the effect of LXR activation on CEC function is determined. Methods: The effect of inflammatory stimuli (interferon y (IFN-y) and tumor necrosis factor a (TNF-a)) in combination with the LXR agonist GW3965 is studied in vitro in the human brain endothelial cell line hCMEC/D3 and ex vivo in primary CECs isolated from wild type and LXRa or LXRb isoform knockout mice using dextran gradient centrifugation. Modulation of BBB properties and pro-inflammatory chemoattractants are quantified by real-time PCR. Results: In vitro, LXR activation in hCMEC/D3 suppresses the cell surface expression of the adhesion molecules ICAM-1 and VCAM-1 in a dose-dependent manner. Furthermore, the expression of CXC chemokines is reduced in hCMEC/D3 following LXR activation. Ex vivo, LXR response genes (ABCA1 and ABCG1) show less upregulation after LXR activation in CECs isolated from LXRb isoform knockout mice compared to LXRa isoform knockout and wild type mice. Conclusions: Under inflammatory conditions, BBB properties are positively affected by the activation of LXRs in CECs. The suppression of adhesion molecule expression and chemoattraction by an LXR agonist provides an anti-inflammatory environment leading to reduced leukocyte extravasation into the CNS. LXRb appears the main LXR isoform in CECs confirming the importance of LXR subtype-specific research. 80 Poster Abstracts P14 Differential responsiveness of white and grey matter-derived glial cells in vitro Authors Natalia Ochocka, John Brevé, John Bol, Benjamin Drukarch and Anne-Marie van Dam Affiliation VU University Medical Center, Neuroscience Campus Amsterdam, Department of Anatomy and Neurosciences, Amsterdam, The Netherlands Abstract Background + objective: It is known that Multiple Sclerosis (MS) affects both white matter (WM) and grey matter (GM). Nevertheless, the immunopathology observed in those regions differs e.g. in a number of leukocytes that highly infiltrate WM, but not GM and increased level of nitric oxide (NO) resulting in nitrozative damage of WM, which is not seen in GM. This can be due to local differences in responsiveness of glial cells, resulting in a differential inflammatory environment. In the present study we aim to dissect the responsiveness of white and grey matter-derived glial cells in vitro. Methods: Primary glial cells were derived at postnatal day 1-2 from striatum (enriched white matter) and cerebral cortex (enriched grey matter) of Wistar rats. After 4 or 10 days in culture, the cells were treated with various doses of lipopolysaccharide (LPS; E.coli 055B5) for 24h and examined for the expression of inflammatory markers (IL-1β, IL-10, iNOS). In addition, isolated microglial cells will be exposed to astrocyte conditioned medium or plated upon an astrocyte monolayer to determine whether astrocyte-derived factors and/or cell-cell contact is essential for their response. Results: Thus far, glial cells derived from both striatum and cortex strongly upregulated the pro inflammatory markers (iNOS, IL 1β) when stimulated with LPS after 4 days in culture. However, after day 10 the expression was retained at the high level only in the striatum-derived culture, and reduced in the cortex-derived culture. On the contrary, the expression of anti-inflammatory marker IL-10 was increased in both cultures after day 4, but only cortex-derived culture showed further increase after day 10. The result is coupled with persistent ameboid morphology of striatal microglia, whereas the cortical microglia adopts a ramified morphology in time. Conclusions: The consistent expression of inflammatory mediators together with an amoeboid morphology of microglia suggests a more pro-inflammatory profile of glial cells in white matter, compared to GM-derived glial cells that show down-regulation of inflammatory mediators, up-regulation of the anti-inflammatory mediator and adapt the ramified phenotype. These data imply a differential responsiveness of white versus grey matter- derived glial cells that may contribute to the differential immunopathology observed in MS lesions. 81 Poster Abstracts P15 Prevalence of Depression and Anxiety in Multiple Sclerosis: A systematic review Authors: Rosa Boeschoten1,2, Annemarie Braamse1,2, Joost Dekker1,2,4, Patricia van Oppen1,2, Aartjan Beekman1,2, Bernard Uitdehaag3 1 AffiliationDepartment of Psychiatry, VU University Medical Center and GGZinGeest, Amsterdam, Netherlands. 2 EMGO Institute for Health and Care Research, VU University, Amsterdam, Netherlands 3 Department of Neurology, VU University Medical Center, Amsterdam, Netherlands 4 Department of Rehabilitation Medicine, VU university Medical Center, Amsterdam, Netherlands Abstract Background + Objectives: Emotional disorders such as depression and anxiety are common in patients with Multiple Sclerosis (MS) and among the most important factors affecting quality of life. Prevalence rates of depression and anxiety in MS vary widely across studies that differ in settings, sample sizes and diagnostic approaches. Taking into account these differences, this systematic review aimed at calculating the average prevalence of depression and anxiety in MS. Methods: A systematic review of available publications obtained via a computerized search in Medline, EMBASE, Psycinfo and the Cochrane library for studies of depression and anxiety in MS was executed. The literature search identified 2329 articles published between 1979 and December 2014 which were systematically reviewed. English written studies that identified prevalence of depressive disorders and anxiety disorders or clinical significant symptoms in 200 or more outpatients with MS, age >15 years, were included, resulting in 59 articles. Findings: Results showed a weighted prevalence for depressive disorder of 21.7% (95% CI=16.4%-28.2%) and anxiety disorder of 13.0% (95% CI=7.7%-21.1%). Clinically significant depressive symptoms were present in 34.9% (95% CI=30.0%-40.1%) and clinically significant anxiety symptoms in 35.5% (95% CI=26.1%-46.3%). Further analyses showed that taken together, studies using DSM criteria/ ICD-codes and no structured interview to diagnose depression, displayed a significantly lower prevalence rate compared to studies using (semi) structured interviews to establish DSM criteria (p<0.5). Population studies reported a similar prevalence rate for depression disorder but higher prevalence rate for clinically depressive symptoms compared to studies in clinical settings. 82 Poster Abstracts Conclusions: This review shows that the average prevalence of depression and anxiety in MS is substantial and should be a point of concern. However, due to methodological differences between studies results should be interpreted with caution. 83 Poster Abstracts P16 Satellite oligodendrocytes produce myelin and limit neuronal excitability by activity-dependent potassium buffering Authors Arne Battefeld, Jan Klooster1, Maarten HP Kole1,2 1 Affiliation Axonal Signaling Group, Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences, Meibergdreef 47, 1105 BA, Amsterdam. 2 Cell Biology, Faculty of Science, University of Utrecht, 3584 CH, Utrecht. Abstract Background + objective: The gray matter contains a large numbers of oligodendrocytes. In the deeper layers of the cortex oligodendrocytes are abundant and they myelinate mainly axons of projection neurons. Intriguingly about ~35% of oligodendrocytes can be found in direct contact with cell bodies of pyramidal neurons. These oligodendrocytes are described as ‘perineuronal’ or ‘satellite’ oligodendrocytes (sOLs) that are not myelinating axons but rather metabolically supporting and protecting neurons from apoptosis. Their unique position makes them an excellent target to investigate neuron-oligodendrocyte interactions in the grey matter. Here, we hypothesized that sOLs can detect and influence action potential firing due to their proximity to neurons. Methods: We combined whole-cell patch-clamp recordings and live confocal imaging of neuron-sOL pairs in acute neocortical slices from adult mice (wild-type or PLP-ECFP reporter mice) allowing morphological and physiological characterization. Immunohistochemical analyses and electron microscopy of single sOLs was performed post-hoc to identify protein expression and assess myelination. Computational modeling of neuron-glia interactions was based on published models. Results: We found that sOLs myelinated on average 32 surrounding axons with ~4 myelin layers. Interestingly, in response to action potentials sOLs displayed time locked inward currents with an amplitude of –16 ± 2 pA (n = 16). Inward currents were selectively reduced to 20% of control values by 100 µM barium, which is a blocker of Kir channels. Immunohistochemical and immuno-gold electron microscopy revealed somatic expression of Kir4.1. Computational modeling showed that during action potential firing the largest source of potassium release is the peri-somatic region of the neuron. Moreover, both computational modeling and in vitro experiments demonstrated that during repetitive firing sOLs can constrain the generation of during periods of high-frequency firing by rapidly buffering the extracellular potassium. 84 Conclusions: Our data show that sOLs unexpectedly produce myelin similar to other grey matter oligodendrocytes. Expression of Kir4.1 at the cell body and their direct apposition to pyramidal neurons plays a role in limiting hyper-excitability of the host neurons. These data suggest that neuron-oligodendrocyte interactions are critical for maintaining activity levels in the cortex. Poster Abstracts P17 Human circulating follicular regulatory T cells are impaired in multiple sclerosis Authors Tess Dhaeze1; Evelyn Peelen1; Stéphanie D’Hondt2; Nele Claes1; Anneleen Hombrouck3; Liesbet Peeters1; Bart Van Wijmeersch1,4; Isabelle Thomas3; Peter Lemkens5; Bieke Broux1; Sophie Lucas2; Veerle Somers, Piet Stinissen1; Niels Hellings1 1 Affiliation Hasselt University, Biomedical Research Institute and Transnationale Universiteit Limburg, School of Life Sciences, Diepenbeek, Belgium 2 de Duve Institute, Université catholique de Louvain, Brussels, Belgium 3 Scientific Institute of Public Health, Operational Direction of Transmitted and Infectious Diseases, Virology Unit, Brussels, Belgium 4 Rehabilitation & MS-Center, Overpelt, Belgium 5 Hospital East-Limburg (ZOL), Campus Sint-Jan, Genk, Belgium Abstract Background + objective: Both autoreactive T cells and autoantibodies are identified as key players in the immunepathogenesis of multiple sclerosis (MS). These overt autoimmune responses may result from disturbances in regulatory T cells important for the maintenance of peripheral tolerance. Recently a new subset of regulatory T cells was discovered in mice. Follicular regulatory T cells (TFR, CD4+CXCR5hiPD-1hiFoxP3+) participate in germinal responses by controlling the maturation of B cells and the production of (auto)antibodies. The aim of this study was to asses impairments in frequency and function of TFR in patients with MS. Methods: First, a side by side comparison is made of TFR derived from lymphoid tissue (tonsils) and peripheral blood (PB) of healthy donors (HC) to demonstrate whether blood is an appropriate source to study TFR. Next, frequency, phenotype and function is defined of circulating TFR of MS patients in comparison to those of HC. Results: We found that circulating TFR comprise a distinct population in humans. They express both follicular (CXCR5+PD-1+SAP+) and regulatory markers (Foxp3 and Helios). In addition, they display a memory phenotype (CD45RO+CD45RA-CCR7+) but are not considered bona fide TFR as they do not express BCL-6 and ICOS. Next, to identify their functional relevance the effect of influenza vaccination was assessed. We show that TFR frequencies increase after influenza vaccination and correlate with anti-flu antibody responses. To assess their suppressive capacity their function was compared with tonsil derived TFR. Both the suppressive function and the FOXP3 methylation status did not differ between both populations indicating a fully functional circulating population. A significantly decreased TFR frequency (p=0.0011) was found in untreated MS patients (0.1151 ± 0.008784 % of CD4+, n=96) compared to HC (0.1658 ± 0.01235 85 Poster Abstracts % of CD4+, n=47). Furthermore, the frequency of circulating Th17-like TFR cells was increased. Also, an impaired suppressive function of TFR from MS patients was found. Conclusions: These results suggest that it is eligible to study circulating TFR to investigate alterations in autoimmune diseases and an impairment in TFR could contribute to overt autoimmune reactivity in MS disease. 86 Poster Abstracts P18 MS risk genes are associated with enhanced EBNA-1 humoral immune response independent of HLA-DR. Authors Karim L. Kreft MD PhD1*, Gijsbert P. Van Nierop BASc1,2*, Sandra M.J. Scherbeijn BASc2, Georges M.G.M. Verjans PhD2,3 and Rogier Q. Hintzen MD PhD1 Affiliation Departments of 1 Neurology and MS centre ErasMS 2 Viroscience, Erasmus MC, Rotterdam, the Netherlands 3 Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine, Hannover, Germany. *These authors contributed equally to this study. Abstract Background + objective: The complex etiology of multiple sclerosis (MS) involves both genetic and environmental factors like Epstein Barr virus (EBV) infection. Currently, more than 150 mainly immune related single nucleotide polymorphisms (SNP) are known to increase the risk of developing MS. We hypothesized that the immune related MS risk SNP contribute to the enhanced humoral immune response against EBV observed in MS patients. Methods: Serum IgG levels towards EBV nuclear antigen-1 (EBNA-1) were determined in 566 genotyped MS patients and age/gender-matched 119 healthy individuals. Titers were dichotomized as above or below the 75th percentile of EBNA-1 IgG levels in MS patients and healthy EBV carriers. Subsequently, logistic regression was used to determine which MS risk SNP are associated with an increased risk to have enhanced (>75th percentile) EBNA-1 IgG responses. Analogous analyses were performed on IgG levels directed to varicella zoster virus (VZV), included as a control herpesvirus not associated with MS. Results: All included MS patients and healthy individuals were EBV and VZV seropositive. The alternate SNP of previously defined MS-risk alleles of VCAM1, CXCR5 and PRDX5 were independently associated with elevated EBNA-1 IgG, but not VZV IgG levels. This was only detected in MS patients. Additionally, we confirmed the association between HLA-DRB1 and enhanced EBNA-1 IgG levels in both cohorts. However, in an interaction model, the combination of MS-risk SNP alleles of VCAM1, CXCR5 and PRDX5, counteracted the HLA-DRB1 effect on enhanced EBNA-1 IgG response in MS patients. Analogous associations with VZV IgG responses were not observed. Conclusions: In addition to HLA-DRB1, we identified three SNPs (VCAM1, CXCR5 and PRDX5) that are predictive for enhanced EBNA-1 IgG levels, but not VZV IgG levels in MS patients. 87 Poster Abstracts P19 Anti-SPAG16 antibodies in multiple sclerosis Authors Laura de Bock1, Judith Fraussen1, Luisa M. Villar2, José C. Álvarez-Cermeño2, Bart Van Wijmeersch1,3, Vincent van Pesch4, Piet Stinissen1 and Veerle Somers1 1 AffiliationHasselt University, Biomedical Research Institute, and Transnationale Universiteit Limburg, Diepenbeek, Belgium. 2 Departments of Neurology and Immunology, Ramón y Cajal Hospital, Madrid, Spain. 3 Multiple Sclerosis and Rehabilitation Center, Overpelt, Belgium. 4 Institute of Neurosciences, Neurochemistry Unit, Universite´ Catholique de Louvain-la-Neuve, Louvain-la-Neuve, Belgium Abstract Background + objective: We previously identified Sperm-associated Antigen 16 (SPAG16) as a autoantigenic target in multiple sclerosis (MS) (Somers et. al. 2008. J. Immunol.). Since SPAG16 was never linked to MS, we further investigated SPAG16 and anti-SPAG16 antibodies in MS pathology. We demonstrated elevated anti-SPAG16 antibodies in the plasma of MS patients with 95% specificity and 21% sensitivity. The pathologic relevance of these antibodies was shown by the identification of SPAG16-specific oligoclonal bands in the cerebrospinal fluid (CSF) of 5/23 MS patients. In vivo experiments in experimental autoimmune encephalomyelitis (EAE) mice demonstrated that injection with anti-SPAG16 antibodies induced disease exacerbation. Finally, we found that SPAG16 was specifically upregulated in reactive astrocytes, both in EAE and MS lesions (de Bock et. al. 2014. J. Immunol.). These results emphasize the involvement of SPAG16 specific autoantibodies in MS, although their exact role remains to be determined. In the present study, we aim to validate the presence of anti-SPAG16 antibodies in three novel independent cohorts of MS patients. Methods: The autoantibody reactivity to SPAG16 was tested in plasma samples using our recombinant SPAG16 protein ELISA in three different cohorts of MS patients (N=94, N=196 and N=58) recruited at three locations. Results: Elevated plasma anti-SPAG16 antibodies were detected in 20% (19/94), 23% (46/196) and 21% (12/58) of MS patients in the different cohorts. Furthermore, statistical analysis revealed that there was no overall significant difference between the three cohorts (P=0.3960). Therefore, future statistical analysis will be performed on the whole MS cohort irrespective of recruitment location and we will compare the different MS subtypes (relapsing-remitting, primary or secondary progressive). Logistic regression analysis will be performed to identify factors that are predictive of positive anti-SPAG16 antibody assay results. Pearson chi square test and Fisher’s exact test will be used for between-group comparisons. 88 Poster Abstracts Conclusions: Anti-SPAG16 antibody reactivity is present in a subgroup of MS patients (~22%) in three novel cohorts, which is comparable to our previous studies. Moreover, assessing demographic and clinical characteristics of MS patients for association with anti-SPAG16 antibody positivity will provide clues regarding prognostic and/or pathologic potential of these antibodies in MS. 89 Poster Abstracts P20 EBV: a new role in MS Authors Jordon Dunham1,2, Jon D. Laman2 Bert A. ‘t Hart1,2, and Yolanda S. Kap1 1 Affiliation Department of Immunobiology, Biomedical Primate Research Centre, Rijswijk, The Netherlands; 2 University Groningen, University Medical Center, Department of Neuroscience, Groningen, The Netherlands Background + objective: Epidemiological evidence suggests a role for Epstein-Barr virus (EBV) in the development of multiple sclerosis (MS). In a non-human primate model for MS, a γ-herpes virus (CalHV-3) homologous to EBV has also been implicated in a pathogenic role in disease (EAE) induction. In both MS and marmoset EAE models, CD20+ B-cell depletion reduces disease pathology. CD20+ B-cell depletion in the common marmoset EAE model profoundly altered the immunostimulatory environment in the secondary lymphoid organs (SLO), enhanced the percentage of T cells expressing the homing receptor CCR7, and reduced the γ-herpesvirus virus load. This suggests a role of the γ-herpesvirus infected B cell in T cell homing. We hypothesized that γ-herpesvirus infected B cells activate T cells in SLO and license them to egress the SLO. Methods: EBV-infected B cells were co-cultured with mononuclear cells isolated from lymph nodes from MOG34-56/IFA immunized marmosets. Expression of surface markers related to homing (CCR6, CCR7), activation (IL-23R), function (CD27, CD279), and survival (CD127, CD95) were assessed on T cells by flow cytometry. Results: Co-culture of γ-herpesvirus infected B cells with lymph node cells reduced the percentage of CCR7 expressing T cells. This reduction was independent of stimulation with MOG34-56. Interestingly, CCR7 down-regulation was especially observed in animals that were sacrificed with clinical symptoms of EAE, while in animals that did not develop clinical symptoms CCR7 expression was unchanged. MOG34-56-independent reductions of CD27 expression were observed, and this reduction correlated to a loss of expression of Th17 markers (IL-23R, CCR6). Whereas apoptosis antigen 1 (CD95) expression up regulation was not restricted to MOG34-56 stimulation, significant reductions of IL7R (CD127) were observed and in a peptide-restricted fashion. Detection of enhanced expression of programmed cell death (PD-1;CD279) and trogocytotic acquisition of CD86 were observed, suggesting mechanisms of immune escape. Conclusions: Collectively these data suggest that the EBV B cell phenotypically alters the T cell in critical markers related to homing, development, function and survival in ways that may lead to altered migration and exhaustion. These immune-modulatory effects, in context to infectious mononucleosis and chronic EBV exposure, may explain the temporal association between EBV and autoimmune diseases such as MS. 90 Poster Abstracts P21 The importance of costimulation and antigen presentation by B cells in multiple sclerosis Authors Fraussen J1, Claes N1, Van Wijmeersch B1, Hupperts R2, Stinissen P1, Somers V1 1 Affiliation Hasselt University, Biomedical Research Institute, and Transnationale Universiteit Limburg, School of Life Sciences, Diepenbeek, Belgium 2 Department of Neurology, Orbis Medical Center, Sittard, The Netherlands Abstract Background + objective: The success of B cell depletion therapy in multiple sclerosis (MS) has pointed towards the involvement of antibody-independent B cell functions. The aim of this study is to analyze antigen presentation and costimulation by B cells in MS. Methods: Expression of costimulatory and antigen presentation molecules was measured on B cells from the peripheral blood and cerebrospinal fluid (CSF) of MS patients (n = 74 and n = 20, respectively) and peripheral blood of healthy individuals (HC, n = 52) using flow cytometry. B cell proliferation and antigen presentation capacity following antigen-specific stimulation was studied in vitro. B cells of 5 MS patients and 5 HC were labeled with CFSE and cultured 1:1 with autologous feeder cells during 13 days in the presence of tetanus toxoid (TT), myelin antigens or cytomegalovirus (CMV). Results: MS patients showed an increased CD80 and CD40 B cell expression and an increased percentage CD80 + and CD86+ B cells when compared to HC. In the CSF, percentages and fluorescence intensity of CD86+ and CD80+ B cells were even further elevated. B cell proliferation against myelin antigens and CMV was demonstrated in some MS patients. Following stimulation with myelin and viral antigens, the percentage of CD80+ and HLA-DR+ B cells was increased, emphasizing the potential of these B cells to activate autoreactive T cells. Conclusions: These results indicate the potential of B cells to function in antigen presentation and costimulation in MS. In vitro culture systems are currently optimized to study the interaction between T cells and B cells in MS. 91 Poster Abstracts P22 Sleep problems and cognition in Multiple Sclerosis. Authors Benthe Westerik, Quinten van Geest, Jeroen J. G. Geurts & Hanneke E. Hulst Affiliation Department of Anatomy and Neurosciences, VUmc, Amsterdam Abstract Background + objective: Approximately 70% of patients with multiple sclerosis (MS) experience cognitive problems. Additionally, in more than 50% of the patients sleep problems occur. Previous studies in healthy controls (HCs) suggest that sleep is essential for proper cognitive functioning. As there are still no effective treatment options for cognitive impairment in MS, treating sleep problems might have a beneficial, indirect effect on cognitive functioning. As a first step, the aim of the present study was to explore the relationship between sleep problems and cognition in patients with MS. Methods: Sleep problems were investigated using the five-item version of the Athens Insomnia Scale (AIS-5). The AIS-5 includes items of sleep induction, awakenings during the night, final awakening earlier than desired, total sleep duration, and overall sleep quality. Cognitive functioning was assessed using an extensive neuropsychological test battery, including tests on verbal learning and memory, spatial memory, working memory, information processing speed and verbal fluency. Additionally, questionnaires on fatigue (CIS-20), anxiety and depression (HADS) and subjective cognitive functioning were administered. Results: Seventy-one MS patients (mean age: 45.7±8.3, 47 females) and 40 HCs (mean age: 44.0±9.1, 26 females) were investigated. MS patients scored significantly worse than the HCs on all cognitive tests. Based on a median split of the AIS-5 scores in both the MS and HC group separately, 25 MS patients and 16 HCs were categorized as experiencing sleep problems. No significant differences in cognitive functioning were observed between MS patients with and without sleep problems, and between HCs with and without sleep problems. In HCs, but not in MS patients, AIS-5 scores correlated positively with fatigue. Conclusions: The findings of this study suggest that either the AIS-5 is not sensitive enough to detect true sleeping disturbances in patients with MS or that there is not a direct relation between sleeping disturbances and cognitive deficits. Future studies should aim to investigate sleep and sleeping problems in MS in more depth. 92 Poster Abstracts P23 eMotionS: emotional memory impairment and amygdala activation in multiple sclerosis Authors: Q. van Geest1, H.E. Hulst1, B.M.J. Uitdehaag2, F. Barkhof3, J.J.G. Geurts1 1 Affiliation Department of Anatomy and Neurosciences, VU University Medical Center, Amsterdam 2 Department of Neurology, VU University Medical Center, Amsterdam 3 Department of Radiology and Nuclear Medicine, VU University Medical Center, Amsterdam Abstract Background + objective: In multiple sclerosis (MS), emotional memory is relatively understudied. However, the amygdala of MS patients can show various abnormalities, including demyelination, atrophy, iron deposition and functional alterations during processing of emotional faces. The aim of this study was to explore the relationship between emotional memory and amygdala activation in patients with MS. Methods: Neuropsychological testing, psychiatric interview, and (f)MRI (1.5T) were performed in 39 MS patients (24 female; mean age 48.04±8.33 years) and 25 healthy controls (HCs; 16 female; mean age 46.76±8.74 years). The fMRI paradigm consisted of neutral to highly negative emotional pictures which subjects had to rank in an emotional category (neutral (1) to highly emotional (4)). Two weeks after scanning, a recognition task was performed. Based on recognition of highly emotional pictures, patients were categorized as emotional memory impaired (EMI; n=12) when they performed 1.5 SD below the mean score of HCs. Otherwise, patients were categorized as emotional memory preserved (EMP; n=27). Results: None of the subjects met the criteria for a mental disorder. Compared to HCs, EMP and EMI patients scored significantly lower on verbal learning and memory and information processing speed. Left amygdala volume was significantly lower in EMP patients compared to HCs, whereas the right amygdala was significantly smaller in both EMP and EMI patients compared to HCs. During processing of emotional pictures, decreased activation of the right amygdala, right parahippocampal areas and hypothalamus was observed in EMI patients versus HCs (unclustered, z≥3.1, p≤.001). Decreased hypothalamic activation was also observed in EMI patients compared to EMP patients (unclustered, z≥3.1, p≤.001). A regions of interest analysis confirmed decreased activation in de amygdala in EMI patients versus HCs. Conclusions: The present results indicate that reduced activation in the amygdala (important for emotion regulation), parahippocampal areas (essential for memory) and the hypothalamus can be related to impaired emotional memory in patients with MS. 93 94 Leidseweg 557-1 2253 JJ Voorschoten Postbus 200 2250 AE Voorschoten T 071 - 5 600 500 www.msresearch.nl