Similarly, the intestinal microbiome in mice that lack the caspase recruitment domain family member 9 (CARD9) is altered and these animals fail to metabolize Trp into activators of the AHR, exhibit defective expression of IL-22 and antimicrobial peptides (AMPs) such as RegIIIβ and RegIIIγ in the colon, and are more susceptible to colitis [19]. This evidence concerns the gene AHR and colitis.