A single species bacterial therapy reduces type 2 immune responses in the gut to prevent food allergy

Abstract

Abstract The rising prevalence of food allergy is strongly correlated with dysbiosis of the gut microbiome. Rescuing this dysbiosis by reintroducing specific bacteria is a promising method to prevent or treat food allergy. We have shown that monocolonization with Anaerostipes caccae, a species representative of the healthy infant microbiota, protects against an allergic response to the milk protein b-lactoglobulin (BLG). Recently we developed a synbiotic bacterial therapy (A. caccaeplus prebiotic lactulose) which rescues the allergic phenotype of gnotobiotic mice colonized with the fecal bacteria of a dysbiotic, cow’s milk allergic (CMA) infant. Synbiotic treatment minimizes the anaphylactic response to intragastric BLG challenge and reduces circulating BLG-specific IgE and IgG1. To understand how a single bacterium regulates mucosal immunity during the onset of IgE-mediated allergy we first examined the alarmin response. CMA colonized mice express high transcript levels of both IL25and TLSPin ileal epithelial cells after sensitization with BLG plus cholera toxin. The synbiotic abrogated this alarmin response, potentially via increased mucus production. Synbiotic treatment also reduced the proportion and number of T follicular (Tf) helper cells in the ileal-draining lymph node (LN) and increased Tf-regulatory cells in the colon-draining LN, suggesting a role in T/B cell regulation. Ongoing experiments are examining how the synbiotic affects localization and expansion of IgE producing cells in mucosal tissues including Peyer’s patches and mesenteric LNs. These findings will help to uncover the mechanisms by which specific, protective bacteria prevent food allergy and inform the development of effective live biotherapeutics.