AHR and experimental autoimmune encephalomyelitis: Natural ligand–mediated AhR activation results in an increased Th17 population and exacerbated experimental autoimmune encephalomyelitis (EAE) symptoms in mice (15, 16), whereas synthetic ligand–stimulated AhR activation results in an enhanced regulatory T (Treg) cell population and ameliorated EAE symptoms in mice (15, 17).