Glutamine promotes intestinal SIgA secretion through intestinal microbiota and IL-13.

Abstract

Glutamine supplementation enhances secretory IgA (SIgA) production in the intestine, but the mechanism is largely unknown. We examined this issue using a mouse model. In mouse model, glutamine supplementation increased both SIgA abundance in intestinal luminal contents and IgA(+) plasma cell numbers in the mouse ileum, and decreased bacterial loads in mouse mesenteric lymph nodes. Glutamine supplementation increased mouse ileal expression of cytokines associated with T cell-dependent and T cell-independent pathways of SIgA induction, including IL-5, IL-6, IL-13, transforming growth factor (TGF-β), a proliferation-inducing ligand (APRIL), B cell-activating factor (BAFF), vasoactive intestinal peptide (VIP) receptor, and retinal dehydrogenases. Injecting an IL-13 antibody during glutamine supplementation reduced J-chain expression in the mouse ileum. Glutamine supplementation increased bacterial invasion into the mouse ileal wall, while disrupting the mouse intestinal microbiota abrogated the influence of glutamine supplementation on SIgA secretion. Glutamine supplementation appears to enhance SIgA secretion in the mouse intestine through the intestinal microbiota and subsequently through T cell-dependent and T cell-independent pathways.