Deficiency of IL-22-binding protein enhances the ability of the gut microbiota to protect against enteric pathogens.

Abstract

Interleukin 22 (IL-22) promotes intestinal barrier integrity, stimulating epithelial cells to enact defense mechanisms against enteric infections, including the production of antimicrobial peptides. IL-22 binding protein (IL-22BP) is a soluble decoy encoded by the <i>Il22ra2</i> gene that decreases IL-22 bioavailability, attenuating IL-22 signaling. The impact of IL-22BP on gut microbiota composition and functioning is poorly understood. We found that <i>Il22ra2^-/-</i> mice are better protected against <i>Clostridioides difficile</i> and <i>Citrobacter rodentium</i> infections. This protection relied on IL-22-induced antimicrobial mechanisms before the infection occurred, rather than during the infection itself. Indeed, the gut microbiota of <i>Il22ra2^-/-</i> mice mitigated infection of wild-type (WT) mice when transferred via cohousing or by cecal microbiota transplantation. Indicator species analysis of WT and <i>Il22ra2^-/-</i> mice with and without cohousing disclosed that IL22BP deficiency yields a gut bacterial composition distinct from that of WT mice. Manipulation of dietary fiber content, measurements of intestinal short-chain fatty acids and oral treatment with acetate disclosed that resistance to <i>C. difficile</i> infection is related to increased production of acetate by <i>Il22ra2^-/-</i>-associated microbiota. Together, these findings suggest that IL-22BP represents a potential therapeutic target for those at risk for or with already manifest infection with this and perhaps other enteropathogens.