There is accumulating evidence that environmental, dietary, microbial, and immunological cues regulate intestinal inflammation in mouse models by targeting AhR in epithelial cells 7, 8, innate lymphoid cells (ILCs) 9, 10, intraepithelial lymphocytes 11, and T cells 12-14; however, little is known about the exact role of AhR in regulating intestinal macrophage functions in IBD pathogenesis. Here, AHR is linked to inflammatory bowel disease.