Deficiency of IL-22-binding protein enhances the ability of the gut microbiota to 2 protect against enteric pathogens

Interleukin 22 (IL-22) promotes intestinal barrier integrity, stimulating epithelial cells to enact defense mechanisms against enteric infections, including production of antimicrobial peptides. IL-22 binding protein (IL-22BP) is a soluble decoy encoded by the Il22ra2 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 Il22ra2-/- mice are better protected against Clostridioides difficile and Citrobacter rodentium 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 Il22ra2-/- mice mitigated infection of WT mice when transferred via co-housing or by cecal microbiota transplantation. Indicator species analysis of WT and Il22ra2-/- 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 Clostridioides difficile infection is related to increased production of acetate by Il22ra2-/- 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.