Lamas et al. [288] also demonstrated, in mice deficient in the caspase recruitment domain (Card) 9, an IBD susceptibility gene, that the impaired capacity of the dysbiotic GM to catalyze Trp conversion into AhR ligands reflected into lower IL-22 levels and a higher Card9−/− mice susceptibility to SDS-induced colitis. This evidence concerns the gene IL22 and colitis.