Manipulation of the feedback control of AHR signaling cytochrome P4501 (CYP1) enzymes results in a loss of AHR-dependent ILC3 and Th17 cells, which can be reversed by supplementation of AHR ligands in the diet.32 Recently, impaired tryptophan metabolism by the microbiome due to a deficiency in the CARD-9 gene has also been associated with susceptibility to colonic inflammation.33 Other metabolites, such as inosine, may be remodeled by Lactobacillus reuteri, which then suppress the autoimmunity caused by Treg deficiency.34 This evidence concerns the gene AHR and Autoimmunity.