A Critical Regulation of Th17 Cell Responses and Autoimmune Neuro-Inflammation by Ginsenoside Rg3

Among diverse helper T-cell subsets, Th17 cells appear to be pathogenic in diverse autoimmune diseases, and thus, targeting Th17 cells could be beneficial for the treatment of the diseases in humans. Ginsenoside Rg3 is one of the most potent components in Korean Red Ginseng (KRG; Meyer) in ameliorating inflammatory responses. However, the role of Rg3 in Th17 cells and Th17-mediated autoimmunity is unclear. We found that Rg3 significantly inhibited the differentiation of Th17 cells from naïve precursors in a dendritic cell (DC)-T co-culture system. While Rg3 minimally affected the secretion of IL-6, TNFα, and IL-12p40 from DCs, it significantly hampered the expression of IL-17A and RORγt in T cells in a T-cell-intrinsic manner. Moreover, Rg3 alleviated the onset and severity of experimental autoimmune encephalomyelitis (EAE), induced by transferring myelin oligodendrocyte glycoprotein (MOG)-reactive T cells. Our findings demonstrate that Rg3 inhibited Th17 differentiation and Th17-mediated neuro-inflammation, suggesting Rg3 as a potential candidate for resolving Th17-related autoimmune diseases.