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Effect of structural stability on endolysosomal degradation and T-cell reactivity of major shrimp allergen tropomyosin.

ABSTRACT: Background: Tropomyosins are highly conserved proteins, an attribute that forms the molecular basis for their IgE antibody cross-reactivity. Despite sequence similarities, their allergenicity varies greatly between ingested and inhaled invertebrate sources. In this study, we investigated the relationship between the structural stability of different tropomyosins, their endolysosomal degradation patterns, and T-cell reactivity.

Methods: We investigated the differences between four tropomyosins-the major shrimp allergen Pen m 1 and the minor allergens Der p 10 (dust mite), Bla g 7 (cockroach), and Ani s 3 (fish parasite)-in terms of IgE binding, structural stability, endolysosomal degradation and subsequent peptide generation, and T-cell cross-reactivity in a BALB/c murine model.

Results: Tropomyosins displayed different melting temperatures, which did not correlate with amino acid sequence similarities. Endolysosomal degradation experiments demonstrated differential proteolytic digestion, as a function of thermal stability, generating different peptide repertoires. Pen m 1 (T_m 42°C) and Der p 10 (T_m 44°C) elicited similar patterns of endolysosomal degradation, but not Bla g 7 (T_m 63°C) or Ani s 3 (T_m 33°C). Pen m 1-specific T-cell clones, with specificity for regions highly conserved in all four tropomyosins, proliferated weakly to Der p 10, but did not proliferate to Bla g 7 and Ani s 3, indicating lack of T-cell epitope cross-reactivity.

Conclusions: Tropomyosin T-cell cross-reactivity, unlike IgE cross-reactivity, is dependent on structural stability rather than amino acid sequence similarity. These findings contribute to our understanding of cross-sensitization among different invertebrates and design of suitable T-cell peptide-based immunotherapies for shrimp and related allergies.

SUBMITTER: Kamath SD

PROVIDER: S-EPMC7687109 | biostudies-literature | 2020 Nov

REPOSITORIES: biostudies-literature

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Effect of structural stability on endolysosomal degradation and T-cell reactivity of major shrimp allergen tropomyosin.

Kamath Sandip D SD Scheiblhofer Sandra S Johnson Christopher M CM Machado Yoan Y McLean Thomas T Taki Aya C AC Ramsland Paul A PA Iyer Swati S Joubert Isabella I Hofer Heidi H Wallner Michael M Thalhamer Josef J Rolland Jennifer J O'Hehir Robyn R Briza Peter P Ferreira Fatima F Weiss Richard R Lopata Andreas L AL

Allergy 20200618 11

<h4>Background</h4>Tropomyosins are highly conserved proteins, an attribute that forms the molecular basis for their IgE antibody cross-reactivity. Despite sequence similarities, their allergenicity varies greatly between ingested and inhaled invertebrate sources. In this study, we investigated the relationship between the structural stability of different tropomyosins, their endolysosomal degradation patterns, and T-cell reactivity.<h4>Methods</h4>We investigated the differences between four tr ...[more]

PMID: 32436591

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Project description:BACKGROUND:Many types of shellfish including oysters are sometime cooked before ingestion and it has been demonstrated that cooking may affect the allergenicity of food. Therefore, the aim of our present study is to identify major and minor allergens of tropical oyster (Crassostrea belcheri) and to investigate the effect of different cooking processing on the allergenicity of this oyster. METHODS:Raw, boiled, fried and roasted extracts of oyster were prepared. Protein profiles were analysed using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Major and minor allergens and allergenicity patterns of all extracts were then determined by immunoblotting with sera from patients with positive skin prick tests (SPT) to the raw oyster extract. Mass-spectrometry was used to identify the major allergenic proteins of this oyster. RESULTS:SDS-PAGE of the raw extract showed 15 protein bands (20-180 kDa). In contrast, smaller numbers of protein bands were demonstrated in the boiled extract, those ranging between 40-42 and 55-150 kDa were denatured, whereas the protein profiles were altered to a similar degree by frying or roasting. The 37 kDa proteins had the highest frequency of IgE-binding (95 %), thus identified as the major allergen of this tropical oyster. Other minor IgE-binding proteins were observed at various molecular weights. Immunoblot of raw extract yielded 11 IgE-binding proteins. The cooked extracts showed only a single IgE-binding protein at 37 kDa. Mass spectrometry analysis of the 37 kDa major allergen identified this spot as tropomyosin. CONCLUSIONS:Cooked extracts produce lower IgE-binding than raw extract, which suggest that thermal treatment can be used as a tool in attempting to reduce oyster allergenicity by reducing the number of IgE-reactive bands. The degree of allergenicity of this oyster was demonstrated in the order raw > boiled > fried ≈ roasted. A heat-resistent 37 kDa protein, corresponding to tropomyosin, was identified as the major allergen of this tropical oyster.

Dataset Information

Effect of structural stability on endolysosomal degradation and T-cell reactivity of major shrimp allergen tropomyosin.

Publications

Effect of structural stability on endolysosomal degradation and T-cell reactivity of major shrimp allergen tropomyosin.

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