AHR and colitis: Takamura et al. (2010) proposed that the inhibition of colitis by the AHR may be due to the increased production of Prostaglandin E2 (PGE2) and that the inhibition of PGE2 reduced the inhibitory effects of the AHR on colitis. These confirmed the positive effect of AHR activation on intestinal inflammation. Consistently, the AHR agonist medication attenuates colitis in mice models (Benson and Shepherd, 2011; Monteleone et al., 2011; Huang et al., 2013).