Background: T helper (Th) 17 and regulatory T (Treg) cells play a critical role in the pathogenesis of multiple sclerosis (MS) disease. Bu Shen Yi Sui Capsule (BSYSC), a traditional Chinese medicine formula, has been used clinically for the treatment of MS patients in China.

Methods: To evaluate the neuroprotective effects and the underlying mechanisms of BSYSC on MS, experimental autoimmune encephalomyelitis (EAE) model in C57BL/6 mice was induced with myelin oligodendrocyte glycoprotein (MOG) 35-55. Th17 and Treg cells and the related cytokines were detected by flow cytometry, ELISA, real-time quantitative reverse transcription PCR, western blot and immunohistochemistry.

Results: We found that BSYSC improved neurological function, reduced inflammatory cell infiltration and damage to the axons and myelin in the brain and spinal cord. BSYSC down-regulated markedly the ratio of CD4 + IL-17+/CD4 + CD25 + FoxP3+ T cells in the spleen, decreased the cytokines of IL-17A, IL-6, IL-23, TGF-beta1 in the brain, and dropped the ratio of IL-17A and FoxP3 mRNA and protein in the brain or spinal cord at different stages.

Conclusions: The study demonstrated that BSYSC had a strong neuroprotective effect on EAE mice. The protective mechanisms of BSYSC might be associated with mediating the regulation of Th17/Treg cells.