AHR and inflammatory bowel disease: However, studies also highlighted the role of AhR ligands in host immunity (Lamas et al., 2018) on a more global view and on other types of cells; for example, AhR ligands are directly made by the gut microbiota from tryptophan transformation and have been connected recently to intestinal diseases such as IBD (Lamas et al., 2016; Agus et al., 2018).