AHRR and colitis: In a systemic LPS-induced shock model, AHR-deficient mice are more susceptible while AHRR-deficient mice showed increased survival.31,42,43 This contrasts with experimental dextran sulfate sodium–induced colitis, in which both AHR- and AHRR-deficient mice exhibit increased disease severity, indicating that the local tissue environment affects the role of AHRR in limiting or promoting inflammatory reactions.