Effect of Gross Saponins of Tribulus terrestris on IL-1β-induced Chondrocyte Injury by Regulating miR-99a Expression
Effect of Gross Saponins of Tribulus terrestris on IL-1β-induced Chondrocyte Injury by Regulating miR-99a Expression
Ji Xu, Zhonghua Liu, Zhenhai Cui and Wenhai Zhao*
ABSTRACT
The objective of this study was to investigate the effect of gross saponins of Tribulus terrestris (GSTT) on chondrocyte injury induced by IL-1β and its possible mechanism. Chondrocytes were isolated from rat knee joints and cultured. Chondrocytes were treated with IL-1β, and chondrocytes were treated with different concentrations of GSTT. ELISA was used to detect the levels of IL-6, TNF-α and IFN-γ. Flow cytometry was used to detect the apoptotic rate. The expressions of Bax, cleaved-caspase3 and Bcl-2 were detected by Western blot. qRT-PCR was used to detect the effect of GSTT on miR-99a expression level. The above methods were used to detect the effects of miR-99a overexpression on IL-1β-induced chondrocyte inflammatory factors and apoptosis rate. Anti-miR-NC and anti-miR-99a were transfected into chondrocytes, respectively, and treated with a culture solution containing GSTT and IL-1β for 24 h. Inflammatory factor levels and apoptotic rates were detected. After IL-1β treatment, the levels of inflammatory factors IL-6, TNF-α, and IFN-γ were significantly increased (P <0.05), and the apoptosis rate was significantly increased (P <0.05), the levels of Bax, cleaved-caspase3 protein were significantly increased (P <0.05), the protein level of Bcl-2 was significantly reduced (P <0.05), and the expression level of miR-99a was significantly reduced (P <0.05). After GSTT treatment, the levels of inflammatory factors IL-6, TNF-α, and IFN-γ were significantly reduced (P <0.05), the apoptosis rate was significantly reduced (P <0.05), and the protein levels of Bax and cleaved-caspase3 were significantly reduced (P <0.05), the protein level of Bcl-2 was significantly increased (P <0.05), the expression level of miR-99a was significantly increased (P <0.05), and there were statistically significant differences between different dose groups of GSTT (P <0.05) . After miR-99a overexpression, the levels of inflammatory factors IL-6, TNF-α, IFN-γ were significantly reduced (P <0.05), the apoptosis rate was significantly reduced (P <0.05), and protein levels of Bax and cleaved-caspase3 were significantly decreased (P <0.05), and the protein level of Bcl-2 was increased significantly (P <0.05). Inhibition of miR-99a expression could attenuate the effect of GSTT on IL-1β-induced chondrocyte injury. To conclude that GSTT could inhibit IL-1β-induced chondrocyte inflammation and apoptosis by up-regulating the expression of miR-99a.
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