T-Cell Epitope Immunotherapy in Mouse Models of Food Allergy.

Food allergy has been rising in prevalence over the last two decades, affecting more than 10% of the world population. Current management of IgE-mediated food allergy relies on avoidance and rescue medications; research into treatments that are safer and providing guaranteed and durable curative effects is, therefore, essential. T-cell epitope-based immunotherapy holds the potential for modulating food allergic responses without IgE cross-linking. In this chapter, we describe the methods in evaluating the therapeutic capacities of immunodominant T-cell epitopes in animal models of food allergy. Moreover, we explain in detail the methods to measure the allergen-specific antibody levels, prepare single-cell suspension from spleen, and prepare small intestine for immunohistochemical analysis of eosinophils and Foxp3+ cells.

Modulating Shrimp Tropomyosin-Mediated Allergy: Hypoallergen DNA Vaccines Induce Regulatory T Cells to Reduce Hypersensitivity in Mouse Model.

Shellfish allergy is one of the most common food allergies, with tropomyosin as the major cross-reactive allergen. However, no allergen-specific immunotherapy is clinically available. Recently, we designed two shrimp hypoallergens MEM49 and MED171. This study aimed to examine and compare the efficacy of the MEM49- and MED171-based DNA vaccines (pMEM49 and pMED171) in modulating shrimp allergy in a murine model of shrimp tropomyosin sensitivity. Intradermal immunization of BALB/c mice with pMEM49 or pMED171 effectively down-modulated allergic symptoms, tropomyosin-specific IgE levels, intestinal Th2 cytokines expression, and inflammatory cell infiltration. Both pMEM49 and pMED171 increased the frequency of regulatory T cells, but to a greater extent by pMED171 with upregulation of gut-homing molecules integrin-α4ß7. The functionality of the pMED171-induced Treg cells was further illustrated by anti-CD25-mediated depletion of Treg cells and the adoptive transfer of CD4+CD25+Foxp3+Treg cells. Collectively, the data demonstrate that intradermal administration of pMED171 leads to the priming, activation, and migration of dermal dendritic cells which subsequently induce Treg cells, both locally and systemically, to downregulate the allergic responses to tropomyosin. This study is the first to demonstrate the potency of hypoallergen-encoding DNA vaccines as a therapeutic strategy for human shellfish allergy via the vigorous induction of functional Treg cells.

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

BACKGROUND: Shellfish (SF) allergy is a leading cause of systemic anaphylaxis in humans. An adjuvant-free mouse model to evaluate allergenicity and oral anaphylaxis to SF is currently unavailable. Here, we tested the hypothesis that transdermal exposure (TDE) to SF protein extract (SFPE) not only elicits a systemic allergic immune response but also will clinically sensitize mice for oral anaphylaxis. METHODS: Adult BALB/c female mice (6-8 weeks of age) were exposed to saline or SFPE once a week for 4 weeks using a transdermal sensitization method. Systemic SF-specific IgE, IgG1 and IgG2a and total (t)IgE responses were measured using ELISA. Systemic anaphylaxis upon oral SFPE administration was assessed according to clinical symptoms and the hypothermia shock response (HSR). Using individual mouse data, the correlation between the readouts of allergenicity was determined using Pearson's analysis. Spleen-cell IL-4 and IFN-x03B3; responses were determined using primary cell culture and ELISA. RESULTS: TDE to SFPE resulted in marked systemic specific (s)IgE, tIgE, IgG1 and IgG2a responses. Oral challenge with SFPE in sensitized mice (but not controls) elicited systemic anaphylactic clinical reactions and HSR. A strong correlation was observed between sIgE, tIgE and HSR. Spleen cells isolated from allergic mice (but not controls) exhibited memory IL-4 and IFN-x03B3; cytokine responses. CONCLUSION: We report a novel adjuvant-free mouse model of SF allergy with robust quantifiable and correlated readouts of allergenicity that may be used in basic biomedical, preclinical and applied food/nutrition research on SF allergy.