Food-induced immediate response of the esophagus in pediatric eosinophilic esophagitis

Circulating Food Allergen-Specific Antibodies, Beyond IgG4, Are Elevated in Eosinophilic Esophagitis

INTRODUCTION

Eosinophilic esophagitis (EoE) is a chronic inflammatory condition with an incompletely understood immuno-pathogenesis involving a T2 response. EoE is triggered by food allergens although, unlike IgE-mediated allergies, it exhibits high IgG4 levels in oesophageal biopsies and in circulation. We investigated whether other antibody isotypes specific for food allergens are elevated in EoE and vary with disease activity.

METHODS

Plasma samples from patients with active EoE (n = 51), inactive EoE (n = 82) and non-EoE controls (n = 14) were analysed for food-specific IgG and IgA subclasses against casein, whey, wheat, egg and individual cow's milk allergens by ELISA. α-lactalbumin (Bos d 4)- and β-lactoglobulin (Bos d 5)-specific B cells were measured by flow cytometry in a subset of patients.

RESULTS

Food allergen-specific antibodies in the plasma varied across EoE subgroups and non-EoE controls. Elevated IgG4 in EoE patients confirmed a strong antibody response to food allergens, including casein, wheat and egg. αS1-casein (Bos d 9)-specific IgG, IgG2, IgG4, IgA1 and IgA2 differed between EoE and non-EoE controls and between active and inactive EoE. β-casein (Bos d 11, A1 variant) measurements showed higher levels of specific IgG2 and IgG4 in both EoE groups, whereas whey-derived allergens showed opposing responses: Bos d 4 responses favoured IgG4, and Bos d 5 responses were elevated across multiple IgG and IgA subclasses in EoE. Allergen-specific B cells could not be isolated from the circulation.

CONCLUSION

Our findings reveal distinct antibody profiles in EoE plasma, with elevated IgG and IgA subclasses beyond IgG4, highlighting a complex immune response to food allergens. Differential antibody responses support their clinical relevance in dietary management strategies, while the absence of allergen-specific B cells in circulation likely restricts antibody production to the inflamed oesophagus. Future research should explore whether these antibody profiles can guide personalised treatment and novel therapeutic targets in EoE.

Plant and Arthropod IgE-Binding Papain-like Cysteine Proteases: Multiple Contributions to Allergenicity

Papain-like cysteine proteases are widespread and can be detected in all domains of life. They share structural and enzymatic properties with the group's namesake member, papain. They show a broad range of protein substrates and are involved in several biological processes. These proteases are widely exploited for food, pharmaceutical, chemical and cosmetic biotechnological applications. However, some of them are known to cause allergic reactions. In this context, the objective of this review is to report an overview of some general properties of papain-like cysteine proteases and to highlight their contributions to allergy reactions observed in humans. For instance, the literature shows that their proteolytic activity can cause an increase in tissue permeability, which favours the crossing of allergens through the skin, intestinal and respiratory barriers. The observation that allergy to PLCPs is mostly detected for inhaled proteins is in line with the reports describing mite homologs, such as Der p 1 and Der f 1, as major allergens showing a frequent correlation between sensitisation and clinical allergic reactions. In contrast, the plant food homologs are often digested in the gastrointestinal tract. Therefore, they only rarely can cause allergic reactions in humans. Accordingly, they are reported mainly as a cause of occupational diseases.