Chinese herbal medicine SS-1 inhibits T cell activation and abrogates T_H responses in Sjögren's syndrome

Background/purpose: Sjögren's syndrome (SS) is an autoimmune disease and its conventional treatment has exhibited limited therapeutic efficacy. Traditional Chinese medicine has been demonstrated to ameliorate the sicca symptoms of SS by decreasing the level of T_H1 and T_H2 cytokines and increasing salivary flow rate. A newly designed traditional Chinese medicine, SS-1, showed improved efficacy in alleviating the dryness symptoms of SS patients in the National Taiwan SS cohort investigation. Here, we investigated the effect of SS-1 on T cell responses.

Methods: SS-1 was authenticated and its major compounds were verified by high-performance liquid chromatography. We examined the effects of SS-1 on the activation and T_H1, T_H2, and T_H17 polarization of murine T cells. We also determined the level of T_H1, T_H2, and T_H17 cytokine RNA in peripheral blood mononuclear cells of SS patients before and after SS-1 treatment.

Results: SS-1 treatment inhibits the activation and T_H1, T_H2, and IL-17A⁺IFNγ⁺ T_H polarization of murine T cells. SS-1 treatment also significantly reduces IFN-γ, IL-4, and IL-13 expression, and moderately reduces IL-17A expression in peripheral blood mononuclear cells of SS patients.

Conclusion: Our results suggest that SS-1 inhibits T cell activation and diminishes T_H1, T_H2, and IL-17⁺IFN-γ⁺ T_H responses in SS patients.