We have previously shown that activation of AhR in intestinal mucosal cells with the AhR agonist 6-formylindolo(3, 2-b)carbazole (Ficz) induces the production of IL-22 and down-regulates the expression of inflammatory cytokines (e.g. IFN-γ), with the down-stream effect of attenuating experimental colitis in mice (Monteleone et al., 2011). This evidence concerns the gene IL22 and colitis.