Microglia could also be activated by metabolites of dietary tryptophan produced by the commensal flora, then release TGFα and vascular endothelial growth factor B (VEGF-B) to regulate the pathogenic activities of astrocytes in the experimental autoimmune encephalomyelitis (EAE) mouse model of multiple sclerosis [66]. The gene discussed is VEGFB; the disease is experimental autoimmune encephalomyelitis.