AHR and colitis: The DSS-induced colitis mouse model is characterized by a significant loss of TJs proteins (ZO-1, claudin-1, and occludin), which could be markedly reversed by administration of 6-formylindolo [3,2-b] carbazole (FICZ) (Park et al., 2015; Yu et al., 2018), an endogenous AHR ligand (Rannug et al., 1995).