In a dinitrofluorobenzene (DNFB)-induced AD-model, DNFB treatment lowered the concentration of microbial tryptophan catabolites, especially ILA and indole-3-propionic acid, and suppressed AhR expression.62 Both AhR expression and the expression of tryptophan catabolites were restored by L. reuteri strain DYNDL22M62. Here, AHR is linked to Alzheimer disease.