Molecular Basis of Arthropod Cross-Reactivity: IgE-Binding Cross-Reactive Epitopes of Shrimp, House Dust Mite and Cockroach Tropomyosins

Abstract

Background: Shrimp may cross-react with other crustaceans and mollusks and nonedible arthropods such as insects (cockroach and chironomids), arachnids (house dust mites) and even nematodes. Since the muscle protein tropomyosin has been implicated as a possible cross-reacting allergen, this study characterized the IgE-binding epitopes in shrimp tropomyosin, Pen a 1, that cross-react with other allergenic invertebrate tropomyosins in house dust mites (Der p 10, Der f 10) and cockroaches (Per a 7). Pen a 1-reactive sera from shrimp-allergic subjects were used to evaluate the effect on IgE binding of different amino acid substitutions in Pen a 1 epitopes based on homologous sequences in Per a 7 and Der p 10/Der f 10. Methods: Peptides were synthesized spanning the length of Pen a 1 IgE-binding epitopes and amino acid substitutions were performed based on homologous amino acid sequences from Per a 7 and Der p 10/Der f 10. Results: 7/8 individually recognized Pen a 1 epitopes (2, 3a, 3b, 4, 5a, 5b and 5c) had an identical amino acid sequence with lobster allergen, Hom a 1, 4/8 (3a, 3b, 4 and 5a) with Der p 10 and Der f 10, and 5/8 (2, 3a, 3b, 4 and 5a) with Per a 7. In addition, even homologous regions of other arthropod tropomyosins that differ in one or more amino acids from the sequences of Pen a 1 epitopes are still recognized by shrimp-allergic IgE antibodies. In total, shrimp-allergic sera recognize 6/8 peptides homologous to Pen a 1 epitopes in Per a 7, 7/8 in Der p 10/Der f 10, and 7/8 epitopes in Hom a 1. Conclusions: The IgE recognition by shrimp-allergic individuals of identified and/or similar amino acid sequences homologous to Pen a 1 epitopes in mite, cockroach and lobster tropomyosins are the basis of the in vitro cross-reactivity among invertebrate species. Based on amino acid sequence similarity and epitope reactivity, lobster tropomyosin has the strongest and cockroach the least cross-reactivity with shrimp. The clinical relevance of these cross-reactivities in developing allergic reactions to different arthropods needs to be determined.

Correlation Of Specific IgE To Shrimp With Cockroach and Dust Mite Exposure and Sensitization in an Inner City Population

“…Nationally representative data from NHANES 2005-2006 demonstrate similar associations to NCICAS between high shrimp sensitization in non-hispanic blacks of lower socioeconomic status (Table 3). It is well-known that cockroach, dust mite and shrimp tropomyosins share high sequence identity (~80%) [8] and with the additional exposure data that was collected in thi s population, we not only found a high correlation between both cockroach IgE and shrimp IgE, but a high correlation between exposure to cockroach and shrimp IgE as well. In contrast, we did not find a correlation between dust mite exposure and shrimp IgE.…”

“…However, it is well known that IgE-binding cross-reactive epitopes between food allergens and environmental allergens may contribute to elevated IgE levels [6][7][8]. In particular, house dust mite and cockroach tropomyosins can account for the presence of detectable IgE to shrimp, even in unexposed individuals [9].…”

A Recombinant Hypoallergenic Parvalbumin Mutant for Immunotherapy of IgE-Mediated Fish Allergy

“…IgE epitopes of Cyp c 1, a prominent class I food allergen, capable of inducing severe systemic anaphylactic reactions, thus seem to be of the conformational type. In case of other class I food allergens, which frequently elicit life-threatening anaphylactic reactions, such as the major peanut allergens Ara h 1, Ara h 2, and Ara h 3 (32-34), the major shrimp allergen, Pen a 1 (35), and major milk allergens (36,37), it has been reported that IgE-binding primarily occurs to linear epitopes (reviewed in Ref. 12).…”

El camarón como una fuente de alérgenos

“…Esta reacción cruzada puede desencadenar una respuesta alérgica en personas con alergia a los ácaros, cuando estos consumen alimentos como el camarón o el caracol (74). Existe alrededor de 81 % de identidad en las secuencias de aminoácidos entre las tropomiosinas del ácaro D. pteronyssinus (Der p 10), la de la cucaracha B. germanica (Bla g 7) y la del camarón P. monodon (Pen m 1) (76). En este importante grado de homología estructural y la presencia epítopos antigénicos compartidos, reside parte de las bases inmunológicas de la reacción cruzada entre estas diversas fuentes de alérgenos.…”