Downregulation of IL-17 and IL-6 in the central nervous system by glatiramer acetate in experimental autoimmune encephalomyelitis

T helper 17 (Th17) cells are pivotal in the immune pathogenesis of EAE. Glatiramer acetate (GA) can enhance Treg FOXp3 expression. We demonstrate that GA downregulates the expression of both IL-17 and IL-6 in two different EAE models. Increased mRNA expression in CNS for RORγt, IL-17, IL-12/ IL-23, IL-6, TNF-α, STAT4 and Th1 cytokines were significantly reduced by GA with a concomitant rise in SMAD3. The increased expression of TNF-α, IL-6, and IL-17 in CNS of CD25+ depleted animals was suppressed by GA treatment. This study demonstrates that both Th1 polarization and Th17 expression are modulated by GA.