Translationally, the administration of indole, indole derivatives, or microbial tryptophanase enzyme to antibiotic-treated experimental autoimmune encephalomyelitis mice—a multiple sclerosis model system—reduced CNS inflammation and improved disease scores by the activation of the aryl hydrocarbon receptor (AhR) pathway in astrocytes (40). Here, AHR is linked to experimental autoimmune encephalomyelitis.