Narrow Results

Dioscin, a steroidal saponin isolated from Dioscorea nipponica Makino, has previously been shown to possess antiarthritic effects. However, the underlying mechanism is still elusive. Herein, we investigated the therapeutic effects of dioscin on collagen-induced arthritis (CIA) in DBA/1 mice and related mechanism. Cytokine production in CII-specific immune responses were measured by enzyme-linked immunosorbent assay (ELISA); Th17 cell-related gene expression, including IL-17A, ROR$\gamma \tau$ and IL-23p19, were detected by qPCR analysis; Surface marker, T regulatory (Treg) cells and intracellular cytokines (IL-17A and IFN-$\gamma$) were evaluated by flow cytometry. We performed Th17 cell differentiation assay in vitro. Results showed that, in vivo, dioscin treatment significantly reduced the severity of CIA, which was accompanied by decreased Th17 response, but not Th1 and Treg response; dioscin-treated mice also showed lower percentage of CD11b${}^{+}$ Gr-1${}^{+}$ neutrophils; In vitro, dioscin treatment suppressed the differentiation of naive CD4${}^{+}$ T cells into Th17 cell and decreased IL-17A production. Collectively, our results indicate that dioscin exerts antiarthritic effects by inhibiting Th17 cell immune response.

Multiple sclerosis (MS) is a neuroinflammatory disease characterized by CD4${}^{+}$ T cell-mediated immune cell infiltration and demyelination in the central nervous system (CNS). The subtypes of CD4${}^{+}$ T cells are T helper cells 1 (Th1), Th2, Th17, and regulatory T cells (Treg), while three other types of cells besides Th2 play a key role in MS and its classic animal model, experimental autoimmune encephalomyelitis (EAE). Tregs are responsible for immunosuppression, while pathogenic Th1 and Th17 cells cause autoimmune-associated demyelination. Therefore, suppressing Th1 and Th17 cell differentiation and increasing the percentage of Treg cells may contribute to the treatment of EAE/MS. Astragali Radix (AR) is a representative medicine with immunoregulatory, anti-inflammatory, antitumor, and neuroprotective effects.The active ingredients in AR include astragalus flavones, polysaccharides, and saponins. In this study, it was found that the total flavonoids of Astragus (TFA) could effectively treat EAE in mice by ameliorating EAE motor disorders, reducing inflammatory damage and demyelination, inhibiting the proportion of Th17 and Th1 cells, and promoting Tregs differentiation by regulating the JAK/STAT and NF$\kappa$B signaling pathways. This novel finding may increase the possibility of using AR or TFA as a drug with immunomodulatory effects for the treatment of autoimmune diseases.