AHR and psoriasis: Similarly, a recent study established a mouse model carrying the human psoriasis-associated mutation Card14E138A/+, confirming that indole-producing gut bacteria promote the accumulation of the host metabolite indole-3-sulfate (I3S), activate the AhR to remodel the epigenetic state of skin Th17 cells and enhance their effector functions, ultimately remotely driving psoriatic inflammation (Wang et al., 2025).