Gastrointestinal Immune Response to the Shrimp Allergen Tropomyosin: Histological and Immunological Analysis in an Animal Model of Shrimp Tropomyosin Hypersensitivity

Abstract

Background: Shellfish hypersensitivity is among the most common food allergies. A murine model of IgE-mediated shrimp allergy has been established in our laboratory. The aim of this study is to determine the intestinal histological changes and cytokine expression profile of this model sensitized with the major shellfish allergen tropomyosin. Methods: Female Balb/c mice orally sensitized and challenged with recombinant tropomyosin were sacrificed. Continuous sections of duodenum, jejunum and ileum were prepared using the Swiss roll technique for histological and immunological analysis. Duodenal epithelial cell apoptosis and migration were examined. mRNA expression of IL-4, IL-6, IL-10, IL-13, IL-18 and IFN-γ in intestinal tissue was measured via RT-PCR. Results: In tropomyosin-sensitized and challenged mice, an increased number of eosinophils, mast cells and goblet cells was found 24 h after challenge. There were also increased mast cell and goblet cell numbers at 72 h after challenge, but the level of eosinophils decreased. Differences compared with control mice are most prominent at the duodenum compared to the distal regions. In addition, TUNEL assay indicates a significantly higher apoptosis rate in sensitized mice sacrificed 72 h after challenge, and mRNA expression showed a biased Th2/Th1 cytokine profile and a higher level of murine mast cell protease 1. Conclusions: This study documented a multitude of histological and immunological changes in the gut in a murine model of shrimp allergy. Even without repetitive intragastric challenge, shrimp tropomyosin induces an increase in the number of inflammatory cells to varying degrees within the small intestine. This model provides an important tool for testing new therapeutic interventions.

An Adjuvant-Free Mouse Model of Transdermal Sensitization and Oral Elicitation of Anaphylaxis to Shellfish

“…There are 3 previous elegant studies that reported on the development of shrimp allergy and 1 on mud crab allergy using mouse models with BALB/c and C3H/HeJ mice [25,26,27,28]. Thus, Capobianco et al [27] reported a shrimp tropomyosin allergy mouse model using C3H/HeJ mice with oral exposure to purified shrimp tropomyosin along with cholera toxin adjuvant; their readouts of allergenicity included sIgE (OD values; no titers), spleen-cell IL-4 production and systemic anaphylactic symptom scores upon OC.…”

“…Thus, Capobianco et al [27] reported a shrimp tropomyosin allergy mouse model using C3H/HeJ mice with oral exposure to purified shrimp tropomyosin along with cholera toxin adjuvant; their readouts of allergenicity included sIgE (OD values; no titers), spleen-cell IL-4 production and systemic anaphylactic symptom scores upon OC. Lam et al [25] and Leung et al [26] reported another shrimp tropomyosin allergy model using recombinant protein and BALB/c mice using intragastric exposure with cholera toxin adjuvant [25,26]. Readouts of allergenicity included sIgE responses (OD values; no titers), spleen-cell IL-4 responses, oral allergen-induced symptom scores and histopathological changes in the gut.…”

“…As opposed to previous models of shrimp and mud crab allergy that used purified/recombinant proteins, we chose to use standardized mixed SFPE that is used in clinical testing for humans [25,26,27,28]. The rationale underlying our approach was to simulate the natural TDE to SF proteins in an occupational setting such as the SF industry where exposure is likely to be to multiple types of SF proteins.…”

“…However, there are relatively few efforts reported in the literature on the development of animal models. Three reported mouse models of shrimp tropomyosin allergy and 1 of mud crab allergy share the following features: (1) the use of adjuvants (cholera toxin/complete Freund's adjuvant) and (2) the use of either systemic (intraperitoneal injections) or oral exposure to induce sensitization [25,26,27,28]. These models are highly valuable and useful for studying SF allergy mechanisms in the context of coexposure of allergens with powerful adjuvants.…”

Low-Dose Allergen-Specific Immunotherapy Induces Tolerance in a Murine Model of Shrimp Allergy

“…In this study, we focused on allergic symptoms, rMet e 1-specific antibodies, and histological and immunological changes in the gastrointestinal tract where some of the major clinical symptoms of shrimp allergy occur [11], with an emphasis on the induction of intestinal T reg cells. Our results from this study provide an insight into the effector mechanisms of AIT with different dosages and facilitate the determination of optimal AIT dosing for shrimp allergy.…”