GSE203542
Induction of natural IgE by glucocorticoids
Allergy is one of the most prevalent chronic diseases, affecting hundreds of millions of people worldwide. In allergy, environmental allergens induce B cells to undergo class switch recombination and produce Immunoglobulin E (IgE) antibodies. IgE is a key molecule that mediates allergic responses by coating mast cell or basophil surfaces and inducing degranulation upon binding a specific allergen. IgE can also be spontaneously produced in the absence of exogenous allergens, yet the origin, regulation, and functions of such “natural” IgE still remains largely unknown. Here, we discovered that glucocorticoids, which are steroid stress hormones, enhance IgE isotype class switching in B cells both in vivo and ex vivo without antigenic challenge. Such IgE class switching is promoted by B cell-intrinsic glucocorticoid receptor signaling that reinforces CD40 signaling and synergizes with the IL-4/STAT6 pathway. In addition, we found that rare B cells in the mesenteric lymph nodes are responsible for the production of glucocorticoid-inducible IgE. Furthermore, we showed that locally produced glucocorticoids in the gut may induce natural IgE during perturbations of gut homeostasis such as dysbiosis. Notably, mice preemptively treated with glucocorticoids were protected from subsequent IgE-mediated pathogenic anaphylaxis in vivo. Together, our results suggest that glucocorticoids, classically considered to be broadly immunosuppressive, have a selective immunostimulatory role in B cells. Overall design: RNA-seq data for B cells from ex vivo culture and mLNs in vivo