AhR expression on both Rorc-specific immune cells and Vil1-expressing colonic epithelial cells are essential for I3C-mediated protection against colitis

Abstract

Abstract Colitis is an inflammatory bowel disease (IBD) characterized by dysregulation of the immune system. In our previous reports, we showed indole-3-carbinol (I3C), an aryl hydrocarbon receptor (AhR) ligand, was able to reduce colitis-induced disease severity in an interleukin-22 (IL-22) dependent manner, mainly though innate lymphoid type 3 (ILC3) cells. In the current study, we generated cell-specific conditional knockout (KO) mice that had AhR deficiency in either Rorc-expressing immune cells (ILC3s), or Vil1-expressing colonic epithelial cells (CECs). We induced colitis using the dextran sodium sulfate (DSS) model in control mice and conditional KO strains, those deficient of AhR in Rorc (AR mice) or Vil1 (AV mice) cells. Results showed that compared to control mice, both AR and AV mice lost the expected efficacy effects of I3C treatment during colitis, with higher disease score and inflammation in the colon. Interestingly, immune cell profiling by single-cell RNAseq and flow cytometry showed only AR mice lost the ability to increase IL-22 secretion by ILC3s after I3C treatment during colitis. Since AV mice were still able to increase IL-22 via ILC3s, this suggests AhR deficiency in the CECs leads to alterations in other I3C-mediated mechanisms used to prevent colitis development, independent of the IL22-ILC3 axis. Collectively these data show AhR expression in both specific immune cells and CECs play a pivotal role in I3C-mediated prevention of colitis, though their mechanisms differ.