IL-25 and CD4+ TH2 cells enhance type 2 innate lymphoid cell–derived IL-13 production, which promotes IgE-mediated experimental food allergy

Background Food-mediated allergic reactions have emerged as a major health problem. The underlying mechanisms that promote uncontrolled type 2 immune responses to dietary allergens in the gastrointestinal tract remain elusive. Objective We investigated whether altering IL-25 signaling enhances or attenuates allergic responses to food allergens. Methods Mice of an IL-25 transgenic mouse line (iIL-25Tg mice), which constitutively overexpress intestinal IL-25, and Il17rb −/− mice, in which Il17rb gene expression is disrupted, were sensitized and gavage fed with ovalbumin (OVA). We assessed symptomatic characteristics of experimental food allergy, including incidence of diarrhea, incidence of hypothermia, intestinal T H 2 immune response, and serum OVA-specific IgE and mast cell protease 1 production. Results Rapid induction of Il25 expression in the intestinal epithelium preceded onset of the anaphylactic response to ingested OVA antigen. iIL-25Tg mice were more prone and Il17rb −/− mice were more resistant to experimental food allergy. Resident intestinal type 2 innate lymphoid cells (ILC2s) were identified as the major producers of IL-5 and IL-13 in response to IL-25. Reconstituting irradiated wild-type mice with Rora −/− or Il17rb −/− bone marrow resulted in a deficiency or dysfunction of the ILC2 compartment, respectively, and resistance to experimental food allergy. Repeated intragastric antigen challenge induced a significant increase in numbers of CD4 + T H 2 cells, which enhance IL-25–stimulated IL-13 production by ILC2s ex vivo and in vivo . Finally, reconstituted IL-13–deficient ILC2s had reduced capability to promote allergic inflammation, resulting in increased resistance to experimental food allergy. Conclusion IL-25 and CD4 + T H 2 cells induced by ingested antigens enhance ILC2-derived IL-13 production, thereby promoting IgE-mediated experimental food allergy.