¿Manipulan los ácaros el sistema inmunológico?

¿Manipulan los ácaros el
sistema inmunitario?
Dr. Enrique Fernández-Caldas
Director Científico,
Inmunotek S.L.
Índice
•
•
•
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Introducción a la manipulación
Inmunidad innata y adaptada
Alérgenos de los ácaros
Alérgenos e inmunidad innata
• Actividad enzimática
– Der p 1
• Mimetismo molecular
– Der p 2 y Der p 7
• ¿Actúan los ácaros solos, o tienen cómplices internos?
• Conclusiones
Manipular (del lat. manipŭlus)
• Operar con las manos o con cualquier
instrumento.
• Trabajar demasiado algo, sobarlo, manosearlo.
• Manejar alguien los negocios a su modo, o
mezclarse en los ajenos.
• Intervenir con medios hábiles y, a veces, arteros,
en la política, en el mercado, en la información,
(sistema inmunológico) etc., con distorsión de la
verdad o la justicia (equilibrio), y al servicio de
intereses particulares.
Real Academia Española; Diccionario de la Lengua Española - Vigésima segunda edición
¿Qué es la Manipulación?
• La Manipulación es el antiguo arte, ciencia y
tecnología de hacer que otros hagan lo que tu
quieres que hagan, mientras piensan que es idea
propia.
• Tiene sus raíces en las primeras épocas de la
civilización: el primer manipulador fue la
serpiente cuando le endulzó los oídos a Eva con
las promesas de omnisciencia y omnipotencia.
• Los griegos perfeccionaron la ciencia pero la
llamaron diplomacia.
Evolución del parasitismo
El problema: los patógenos
Clasificación biológica
Solución: el sistema inmunitario
Patógenos extra- e intracelulares
Líneas de defensa
Innata
(fagocitos)
Adaptativa
(anticuerpos)
El sistema inmunitario: tejidos, células y
moléculas defensivas
Integrated Human Immune System
Turvey SE, Broide DH. Innate Immunity. J Allergy Clin Immunol 2010;125:S24-32
TOLL Like Receptors
Alérgenos de los Ácaros
Patologías mediadas por ácaros
• Rinoconjuntivitis, Asma y Dermatitis atópica
• Anafilaxia por ingestión de harinas contaminadas por varias
especies de ácaros
– 80% son alérgicos a la aspirina; inhibición COX?
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•
•
•
•
•
•
•
Acariasis pulmonar (perros)
Dermatitis (Pyemotes triticum, Pediculoides ventricosus)
Urticaria papular (Cheyletus spp.)
Blefaritis y Acne rosacea (Demodex folliculorum)
Sarna (Sarcoptes scabiei)
Enfermedad de Lyme y otras por Garrapatas (Rickettsias)
Scrapie (TSE) en ovejas
Transmisión de virus, bacteria y priones
Alergenicidad de los ácaros
• Potentes alérgenos que unen IgE especifica in
vivo e in vitro
• Pruebas cutáneas positivas
• Test de provocación positivos
• Estudios de inmunoterapia que demuestran
eficacia
• Estudios de control ambiental con resultados
controvertidos
Association between Indoor Allergens
and Asthma
● IgE mediated sensitization to indoor allergens
is a major risk factor for asthma, as
evidenced by:
● Case control studies (e.g. in Emergency Rooms
and schools)
● Prospective studies in high risk cohorts
● Longitudinal population based cohort*
*Sears et al, NEJM 2003;349:1414-22
A longitudinal, population-based, cohort
study of childhood asthma (onset-26 yr)*
Multivariate Model
Persistence
(Significant Risk Factors)
O.R.
P Value
O.R.
P Value
PC20 ≤ 8mg/ml or BDR > 10%
at any assessment (9-12 yr.)
3.00
<0.001
3.03
<0.001
Positive mite ST at 13 yr.
2.41
0.001
2.18
0.01
Female sex
1.71
0.03
----
----
Smoking at 21 yr.
1.84
0.01
----
----
----
----
0.89
<0.001
Age of onset of wheezing
Relapse
*Odds Ratios for factors predicting persistence or relapses of wheezing
Sears et al., NEJM, 2003: 329:1414-22
Grupo
Alérgenos
MW (kDa)
Identidad Bioquímica
Grupo 1
Bt, Dp, Df, Dm, Em
25
Cisteina proteasas
Grupo 2
Bt, Dp, Df, Ds, Em, Ld, Tp, Gd, As
14
Unión a Lipidos (MD2)
Grupo 3
Bt, Dp, Df, Ds, Em
24-31
Tripsina
Grupo 4
Bt, Dp, Dp, Dm, Em
57
α-Amilasa
Grupo 5
Bt, Dp, Ld
14-17
Desconocida
Grupo 6
Bt, Dp, Df
25
Quimiotripsina
Grupo 7
Dp, Df, Ld
24-31
Desconocida
Grupo 8
Ld, Gd, Bt, Dp
26
Glutatión-S-transferasa
Grupo 9
Dp, Bt
30
Serina proteasa
Grupo 10
BT, Dp,, Df, Ld, Tp
33-37
Tropomiosina
Grupo 11
Bt, Dp, Df
98-110
Paramiosina
Grupo 12
Bt, Ld
14
Unión a quitina
Grupo 13
Bt, Ld, Gd, Tp, As
14-15
Unión a ácidos grasos
Grupo 14
Df, Dp, Em
117
Vitelogenina
Grupo 15
Df, Bt
62,5; 98; 105
Quitinasa
Grupo 16
Df
55
Gelsolina
Grupo 17
Df
33
Proteínas de unión a calcio
Grupo 18
Df, Bt
60
Quitinasa
Grupo 19
Bt
7
Peptido antimicrobiano
Grupo 20
Dp
40,4
Arginina quinasa
Grupo 21
Dp, Bt
13,2
Desconocida
Grupo 22
Df
17
Desconocida
Mite Allergens
• Serve a broad range of functions in their
respective hosts, from structural to enzymatic
• The common house dust mite allergens
include:
– Cysteine proteases (Der p 1, Der p 3)
– Serine proteases (Der p 3, Der p 6, Der p 9)
– Chitinases (Der p 15, Der p 18)
– lipid-binding molecules (Der p 2)
– Tropomyosin (Der p 10)
Cuerpos y heces de ácaros
Bodies
Faecal material
> 90% D. pteronyssinus bodies > 95% D. pteronyssinus faeces
Perfil antigénico de extractos de cuerpos y
heces de D. pteronyssinus
Texto
cuerpos
heces
S B F
Boquete et al. Skin test results with body and faecal extracts of Dermatophagoides pteronyssinus containing variable
quantities of major allergens. EAACI, Gotebörg 12/06/07
Alergenicidad de ambos extractos
Body
extract
Faecal
extract
Protein (%)
31.6
34.3
Der p 1 (µg/mg)
11.6
15.8
Der p 2 (µg/mg)
7.6
12.4
50% inhibition (µg)
1.5
1.5
Boquete et al. Skin test results with body and faecal extracts of Dermatophagoides pteronyssinus containing variable
quantities of major allergens. EAACI, Gotebörg 12/06/07
Correlación entre los niveles de Der p 1 y
Der p 2 en sueros (n = 27)
(IU IgE/ml)
100
Der p 2
120
40
80
60
20
0
0
10
20
30
Der p 1
40
50
60
70
(IU IgE/ml)
Iraola V, Boquete M. et al. Pattern of sensitization to major allergens Der p 1 and Der p 2 in mite sensitized individuals
from Galicia. J. Invest Allergol Clin Immunol 2010; 20(3): in press.
Ratios individuales de los valores de IgE
específica Der p 1/Der p 2
Log Ratio Der p 1/Der p 2
10
1
0,1
0,01
0,001
Iraola V, Boquete M. et al. Pattern of sensitization to major allergens Der p 1 and Der p 2 in mite sensitized individuals
from Galicia. J. Invest Allergol Clin Immunol 2010; 20(3): in press.
Allergens and Innate Immunity
Introduction
• The normal pulmonary response to harmless
airborne particles such as pollen, animal dander
and house dust mites is tolerance, achieved by a
complex network of cells and molecules within
the lung.
• However, asthmatic individuals respond with
inflammatory reactions:
– leading to cellular infiltration of the lungs coupled
with changes to lung function, airway
hyperresponsiveness and bronchospasm, or
‘wheezing’.
Allergens and Innate Immunity
• Allergens are linked by their ability to activate the innate
immune system of mucosal surfaces, triggering an initial
influx of innate immune cells that subsequently
promote Th2-polarized adaptive immune responses
– Natural exposure is not to single proteins, but to complex
mixtures of molecules
• The innate immune-activating molecules may not be
identical to the proteins recognized by allergic responses
– Why are those particular proteins so recognized among the
many present during exposure ?
Wills-Karp M, et al. New insights into innate immune mechanisms underlying allergenicity.
Mucosal Immunol. 2010 Mar;3(2):104-10.
¿Usan los ácaros otros mecanismos
(manipuladores) para incrementar su
alergenicidad?
• Actividad enzimática
– Der p 1
– Der p 3, Der p 6 y Der p 9
• Mimetismo celular
– Der p 2 y Der p 7
• Otros factores adyuvantes (¿presencia de
bacterias?)
• Inhibición de COX en pacientes alérgicos a
la aspirina
Zymograma: Dermatophagoides pteronyssinus
kDa
97,4
66,2
45,0
31,0
21,5
14,4
1
2
3
4
5
6
7
8
Fernández-Caldas E. et al. Enzymatic activity of Dermatophagoides pteronyssinus extracts after acidic treatment.
Int Arch Allergy Immunol. 2008;145(4):298-304.
Zymograme: Lane 1: Body extract; Lane 2: Faeces extract
Carnés J, Boquete M, Carballada FJ, Iraola V, Gallego MT, Fernández-Caldas E. Enzymatic activity in body
and fecal extracts of the storage mite Chortoglyphus arcuatus. Int Arch Allergy Immunol. 2008;145(3):207-12.
Evidence suggests that proteases may
facilitate allergen sensitization - 1
• Intrinsic protease activity appears to be linked
with sensitization ability in several allergens.
• Removal of proteases decreases airway
inflammation and airway hyperresponsiveness
in mouse models of allergic asthma.
Allergens with cysteine or serine
protease activity
•
•
•
•
•
House dust mites and cockroaches
A. alternata, Cladosporium herbarum
Mammals (e.g., Felis domesticus )
Pollens (ragweed, Phl p 1)
Proteolytic enzymes in the manufacture of
detergents (alkaline detergents), or food
industry (papain).
Evidence suggests that proteases may
facilitate allergen sensitization - 2
• Direct exposure of mice to proteolytic
enzymes such as papain can induce allergic
sensitization.
• Co-administration of active proteases from A.
fumigatus with the tolerogenic antigen OVA
resulted in allergic sensitization.
• Proteases found in ambient air derived from
bacterial and viral species may have accessory
roles.
Evidence suggests that proteases may
facilitate allergen sensitization - 3
• Subcutaneous injection of a serine protease
inhibitor, nafamostat mesilate, during
sensitization to house dust mite extracts
blunted the development of allergic
inflammation and airway hyperresponsiveness.
Mite proteases as potential Th2 adjuvants
in allergic inflammation
Proteases as Th2 adjuvants. Curr Allergy Asthma Rep. 2007 Sep;7(5):363-7.
Immunologically relevant substrate
targets of Der p 1
Shakib F, Ghaemmaghami AM, Sewell HF. The molecular basis of allergenicity. Trends Immunol. 2008
Dec;29(12):633-42.
Reed CE, Kita H. The role of protease activation of inflammation in allergic respiratory diseases. J Allergy Clin Immunol.
2004 Nov;114(5):997-1008.
Shakib F, Ghaemmaghami AM, Sewell HF. The molecular basis of allergenicity. Trends Immunol. 2008 Dec;29(12):633-42.
However, …. other allergens commonly
associated with asthma are not proteases …
• Group 2 allergens, group 5, group 7, and group 10
allergens are not enzymes
• Most animal allergens are lipocalins (or ligandbinding proteins)
• The major cat allergen, Fel d 1, is structurally
homologous to secretoglobin
• Fel d 3 is a cystatin (cysteine protease inhibitor)
• Can f 1 may serve a similar function
Crystal structure of Der p 2
Derewenda et al J Mol Biol 2002;318:189-97
Der p 2: shows structural homology
to lipid binding proteins
● MD-2, binds LPS with high affinity through association
with Toll-like Receptor 4 (TLR4)
● NPC2, cholesterol binding protein associated with Niemann
Pick disease
● GM2, ganglioside activating protein, binds to glycolipids
Fold recognition studies suggest a >95% probability that
Der p 2 and MD-2 share the same structure fold.
Gruber et al, JBC 279: 28475-82, 2004
Mite Group 2 Allergens
Mimetismo
• The main house-dust-mite allergen, Der p 2, has
structural homology with MD-2 , the LPS-binding
component of the TLR 4 signaling complex.
• Der p 2 also has functional homology, facilitating
signalling through direct interactions with the TLR4
complex, and reconstituting LPS-driven TLR4 signalling in
the absence of MD-2.
Nature 2009 Jan 29;457(7229):585-8.
Allergic mimicry
• MD2 binds LPS, TLR4 and the co-factor CD14, and is
essential for LPS recognition and the initiation of TLR4
signalling.
• Der p 2 could reconstitute LPS induced TLR4 signalling in
cells that lack MD2 and also could enhance the
response in the presence of MD2
• LPS–Der p 2 complex might mimic the TLR4 activating
properties of the LPS–MD2complex.
Rizzo MC, Naspitz CK, Fernández-Caldas E, et al. Endotoxin exposure and symptoms in asthmatic children.
Pediatr Allergy Immunol. 1997 Aug;8(3):121-6.
Rizzo MC, Naspitz CK, Fernández-Caldas E, et al. Endotoxin exposure and symptoms in asthmatic children.
Pediatr Allergy Immunol. 1997 Aug;8(3):121-6.
Rizzo MC, Naspitz CK, Fernández-Caldas E, et al. Endotoxin exposure and symptoms in asthmatic children.
Pediatr Allergy Immunol. 1997 Aug;8(3):121-6.
Actúan los ácaros solos, o tienen
cómplices internos?
Martínez-Girón R. Antiprotozoal drugs in the treatment of respiratory allergy: a side that should be explored.
Ther Adv Respir Dis. 2009 Feb;3(1):47-8.
Valerio CR, Murray P, Arlian LG, Slater JE. Bacterial 16S ribosomal DNA in house dust mite cultures.
J Allergy Clin Immunol. 2005 Dec;116(6):1296-300.
Conclusions
• The allergenicity of molecules resides in their
ability to activate innate immune pathways at
mucosal surfaces, rather than in any structural
similarities.
• Allergens contain multiple innate immuneactivating components, which trigger the
initial mucosal influx of innate immune cells
that subsequently promote Th2-polarized
adaptive immune responses.
Conclusions
• The function of dust mite allergens, which are
cysteine and serine proteases, enhances their
ability to elicit IgE responses and has
inflammatory effects on the lung including:
– direct damage to the epithelium
– recognition by dendritic antigen-presenting cells
– release of proinflammatory cytokines from
epithelial cells, mast cells, and basophils
Conclusions
• Der p 2 mimics the function of MD2 and can
facilitate TLR4 signalling and airway TH2-type
inflammation under conditions of low levels of
ambient LPS exposure that normally would
induce tolerance.
• More than 50% of major allergens are lipidbinding proteins; such mimicry could also
underline the allergenicity of these allergens.
Conclusions
• The synergistic effects of biologically active
enzyme allergens on Th2 responses and allergic
inflammation may explain why mites are the
predominant allergens associated with asthma.
• A central paradox remains that other important
asthma-associated allergens (eg., cockroach and
animal allergens) are not proteolytic enzymes.
– Enzymatic and nonenzymatic allergens can mediate
Th2 responses, inflammation, and asthma.
Conclusions
• The study of innate activating properties of
allergens is in its infancy.
• A better molecular understanding of the
fundamental origins of allergenicity may lead
to the development of new therapeutic
strategies to block allergen recognition and
the ensuing inflammatory cascade effectively.
Innate immune mechanisms activated by allergens
New insights into innate immune mechanisms underlying allergenicity. Wills-Karp M, Nathan A, Page K, Karp CL.
Mucosal Immunol. 2010 Mar;3(2):104-10.