The Role of Food Allergy in Eosinophilic Esophagitis

Abstract

Food allergy is often understood as an IgE-mediated hypersensitivity, characterized by allergic symptoms which occur "immediately" after the ingestion of a relevant food allergen. Increasingly, however, other food-related immune-mediated disorders are recognized in which symptoms can have a delayed onset and IgE does not play a central role. One of the described examples of the latter is eosinophilic esophagitis (EoE) - a disease defined pathologically by local eosinophilic inflammation in the esophagus in the setting of symptoms of esophageal dysfunction. The evidence that EoE is a food-mediated allergic disease includes i) almost all patients respond to an elemental diet and many respond to a diet in which dairy, wheat, eggs and/or soy are eliminated, ii) the presence of food-specific IgE and Th2 cells are consistent with a loss of tolerance to trigger foods and iii) many EoE patients have concomitant IgE-mediated food allergy and other allergic co-morbidities. This narrative review focuses on the hypothesis that EoE is a form of chronic food allergy. The goal is to describe similarities and differences in EoE and IgE-mediated food allergy, and to consider ways that these two increasingly common forms of food allergy are related to each other.

Keywords: IgE; IgG4; Th2; Treg; barrier hypothesis; eosinophilic esophagitis; food allergy.

Figure 1

EoE is a local inflammatory disease of the esophagus and FA is a systemic allergic disorder, but both represent a continuum of food-related allergic disease. Th2 cells and Tregs are present in different relative amounts, but share similar surface markers and cytokine-expression profiles in both EoE and FA. Food-specific IgE and IgG4 are common in both EoE and FA, but the relative ratio of IgE is higher in FA. Changes that occur with diet or treatment (eg, oral immunotherapy) will influence the adaptive immune response and may change the dynamic equilibrium between EoE and FA. Notes: Adapted from Annals of Allergy, Asthma & Immunology, Vol 22/edition 6, McGowan EC, Platts-Mills TAE, Wilson JM. Food allergy, eosinophilic esophagitis, and the enigma of IgG4, pages 563–564, Copright 2019, with permission from Elsevier.