ILC3s restrict intestinal inflammation via IL-10 production.

Abstract

Abstract In this study, we investigated the role of IL-10 production by group 3 innate lymphoid cells (ILC3s) in regulating intestinal immunity. Prior work has established the importance of IL-10 as well as ILC3s in promoting immune homeostasis in the gut. However, the requirement of IL-10 in ILC3s for homeostasis remains unknown. We examined an ILC3 focused cluster in a publicly available single-cell RNA sequencing dataset from patients with ileal Crohn’s disease and detected ILC3s expressing IL10. We then developed Rag1−/−; Il10GFP; Rosa26lsltdTomato; RorcCremice and injected them with PBS or anti-CD40 to induce intestinal inflammation and determine if putative ILC3s expressed IL-10. IL-10 was significantly upregulated following treatment with anti-CD40 7 days following disease initiation. To assess whether ILC3 production of IL-10 played a functional role, we targeted IL-10 specifically in ILC3s by generating Rag1−/−; Il10flox/flox; Rosa26lsl−tdTomato; RorcCre(Il10ΔILC3) mice. Il10ΔILC3mice displayed significantly worse colitis induced by anti-CD40 that was attributed to an increase in Ly6C hiMHCII hiintestinal macrophages (Mϕ) at baseline. Given the alterations in the phenotype of intestinal Mϕ, we examined whether unfractionated wild-type CD4 +T cells would be sufficient to cause colitis when transferred to Il10ΔILC3mice despite the presence of regulatory T cells. Mice were monitored weekly for weight loss and colons harvested for histology at 8 weeks. While IL-10-sufficient littermate controls did not develop inflammation as expected, Il10ΔILC3mice developed severe colitis. Collectively, our findings identify an essential role for IL-10 production by ILC3s to maintain intestinal immune homeostasis. Vanderbilt Digestive Disease Research Center Grant (P30DK058404) The National Institute of Diabetes and Digestive and Kidney Diseases R03DK123489