Indol-3-Carbinol ameliorates colitis in mice by AhR-mediated production of antimicrobial peptides and mucins

Abstract Indole-3-carbinol (I3C) is a dietary compound that acts as a ligand for the aryl hydrocarbon receptor (AhR), an important sensor for environmental polyaromatic chemicals and a regulator of the immune response. The pathogenesis of colitis involves multiple interactions between microbial dysbiosis, dysregulation of the host immune response, environmental factors, and host genetic profile. Indeed, studies have shown defective expression of AhR and antimicrobial peptides (AMPs) particularly defensins in inflammatory bowel disease (IBD) patients. Here, we investigated how I3C influences the production of AMPs, particularly b-defensins, through AhR and colonic microbiota composition in Anti-CD40 or dextran sulfate sodium (DSS)-induced colitis. Our analysis found that I3C attenuates colitis through AhR activation leading to increased expression of murine b-defensins (mBDs) by Colonic Epithelial Cells, resulting in the restoration of healthy gut microbiota and prevention of colonic inflammation. We analyzed the colonic expression of AMPs and mucins. Our analysis found that I3C significantly increased the mRNA expression of AhR, AMPs such as mBDs, Reg4, and mucins, when compared to vehicle-treated mice with colitis. Similarly, the mRNA levels of AhR, AMPs, and mucins were significantly increased in DSS+I3C-treated colon adenocarcinoma cells MC-38 (murine) and Caco2 (human) when compared to DSS-treated cells. To conclude, our findings demonstrate that I3C inhibits colitis primarily through AhR-mediated induction of AMPs and protective mucins, resulting in the enrichment of healthy gut microbiota (This work was supported in part by NIH grants R01ES030144, P01AT003961, P20GM103641, and R01AI123947, R01AI160896). This work was supported in part by NIH grants R01ES030144, P01AT003961, P20GM103641, and R01AI123947, R01AI160896