Effect of Crosstalk Between Th17 and Th9 Cells on the Activation of Dermal Vascular Smooth Muscle Cells in Systemic Sclerosis and Regulation of Tanshinone IIA

Background: To evaluate the effect of T helper 17 (Th17) cells and Th9 cells on the activation of dermal vascular smooth muscle cells (DVSMCs) in systemic sclerosis (SSc) and regulation of tanshinone IIA. Methods: The expression of interleukin 17 receptor (IL-17R) and interleukin 9 receptor (IL-9R) in the skin of SSc patients was assessed by immunofluorescence. The expression of IL-9 and IL-9R mRNA in peripheral blood mononuclear cells (PBMCs) of SSc patients were detected by quantitative real-time polymerase chain reaction (qRT-PCR). The proportion of Th9 cells in PBMCs of SSc patients was sorted by flow cytometry. The effect of IL-9 on the differentiation of Th17 and IL-17 on that of Th9 was detected by flow cytometry. The proportion of Th9 and Th17 cells in SSc patients was detected by flow cytometry. The level of collagen I, III, α-SMA, IL-9R, IL-17R, JNK, P38, and ERK were analyzed using Western blot (WB).Results: Th9 cells were highly expressed in SSc. IL-9 stimulated the differentiation of immature T cells into Th17 cells. IL-17 induced the differentiation of immature T cells into Th9 cells. Tanshinone IIA inhibited the differentiation of immature T lymphocytes into Th17 and Th9. WB showed that the combined action of IL-17 and IL-9 upregulated the inflammation and proliferation of DVSMCs. Anti-IL17, anti-IL9, and tanshinone IIA inhibited the functional activation of DVSMCs.Conclusions: The current results suggested that Th17 and Th9 cells induced the activation of DVSMCs in SSc through crosstalk in vitro, and tanshinone IIA inhibited the process.