Polydatin protects against articular cartilage degeneration by regulating autophagy mediated by the AMPK/mTOR signaling pathway.

BACKGROUND: Knee osteoarthritis (KOA) is one of the leading causes of disability. Polydatin has a potential effect on KOA treatment but the therapeutic mechanism is not clear. This study aims to investigate the therapeutic action of polydatin in KOA and its mechanism in activating autophagy via the AMP-activated protein kinase (AMPK)/mTOR signaling pathway. METHODS: After a KOA rat model was established by anterior cruciate ligament transection surgery, model rats were treated with polydatin 40 mg/kg for 30 days. Subsequently, cartilage tissues were collected, and hematoxylin-eosin (HE), Safranin-O, and TUNEL staining, and western blotting were performed to evaluate the pathological damage and autophagy-related protein expression. Then, human chondrocyte C28/I2 cells were stimulated with lipopolysaccharide (LPS), and the effects of polydatin on C28/I2 cell viability, apoptosis, and autophagy-related protein expression were detected by MTT, Flow Cytometry, and western blot. In addition, an AMPK inhibitor (Dorsomorphin 2HCl) was used to probe the cell proliferation and apoptosis of polydatin-administered C28/I2 cells. RESULTS: Polydatin ameliorated the pathological damage in rat cartilage tissues and inhibited cell apoptosis in KOA rats. Meanwhile, in C28/I2 cells, polydatin promoted viability and reduced apoptosis. In addition, the protein expression of collagen II, LC3II/LC3I, Beclin-1, and p-AMPK/AMPK were upregulated, and p62 and p-mTOR/mTOR were downregulated by polydatin treatment. Interestingly, relative results showed that the protective effect of polydatin in LPS-stimulated-C28/I2 cells was blocked by the AMPK/mTOR inhibitor, dorsomorphin 2HCl. CONCLUSION: Our research showed that polydatin reduced apoptosis and activated autophagy both in vivo and in vitro by the AMPK/mTOR signaling pathway to protect against KOA, which provided the basis for further investigation into the potential therapeutic impact of polydatin on KOA.

Chondroprotective Effect of Wufu Decoction on Tumor Necrosis Factor-α-Induced Chondrocytes via the Extracellular Signal Regulated Kinase 1/2 Signaling Pathway.

OBJECTIVE: Wufu Decoction (WFD) is a herbal formulation composed of five traditional Chinese herbs that is used clinically for arthritis treatment in China. The current study investigated the chondroprotective effects and the underlying mechanism of WFD for osteoarthritis (OA) therapy. METHODS: The chondroprotective effects of WFD were investigated based on vitro study. Following the successful isolation of chondrocytes from rat cartilage tissues and the identification of collagen II expression with immunofluorescence staining, chondrocytes were co-incubated with tumor necrosis factor-α (TNF-α) to induce an inflammation model; WFD was also administered. After the treatment, cell viability was determined by MTT assay, cell apoptosis was assessed by DAPI staining, the concentration of inflammation cytokines interleukin (IL)-1ß and IL-6 were detected with ELISA assay, the expression of collagen II, MEK1/2-ERK1/2 signaling pathway proteins was detected using western blotting, and mRNA expression of MMP-1, MMP-9 and MMP-13 were determined with quantitative real-time polymerase chain reaction. RESULTS: Wufu Decoction significantly restored the cell viability suppressed by TNF-α and inhibited the cell apoptosis induced by TNF-α in chondrocytes. The high concentrations of IL-1ß and IL-6 in TNF-α-induced model cells were significantly decreased in WFD-treated chondrocytes, and the immunofluorescence staining and western blot results showed that the inhibited expression of collagen II in the TNF-α-induced model group was significantly increased in WFD-treated chondrocytes. The protein expressions of MEK1/2, p-ERK1/2, and P53 were significantly reduced in the WFD-treated group compared with those in the model group, and the mRNA expressions of MMP-1, MMP-9, and MMP-13 were also significantly reduced with WFD treatment. CONCLUSION: The present study indicated that WFD exerted a chondroprotective effect in TNF-α-induced chondrocytes via the regulation of the ERK1/2 signaling pathway, suggesting that WFD has therapeutic potential for OA therapy.

Anti­chondrocyte apoptosis effect of genistein in treating inflammation­induced osteoarthritis.

Osteoarthritis (OA) is a chronic disease that is mainly characterized by chondrocyte degeneration. Inflammatory mediators participate in the development of OA, leading to chondrocyte apoptosis and destruction of the cartilage. Genistein is the major active component of isoflavone, with a chemical composition and a biological effect that is similar to that of estrogens, which prevents the degradation of cartilage; however, its underlying mechanisms of action remain unknown. The aim of the present study was to investigate the anti­apoptotic effects of genistein on chondrocytes for the treatment of inflammation­induced OA. Interleukin (IL)­1ß was used to establish a chondrocyte OA model. After treatment with different concentrations of genistein, western blotting identified that expression levels of collagen II and aggrecan were increased in a concentration­dependent manner, while caspase 3 expression gradually decreased after genistein application. Moreover, flow cytometry and ELISA results demonstrated that genistein could decrease chondrocyte apoptosis and reduce the levels of tumor necrosis factor (TNF)­α in a dose­dependent manner. Furthermore, the in vitro data were evaluated in an OA rat model. Genistein increased the collagen and acid glycosaminoglycan content, as well as decreased the levels of TNF­α and IL­1ß. Genistein also promoted the expression levels of collagen II and aggrecan in the articular cartilage, and decreased the expression of caspase 3, thus alleviating cartilage degradation. In conclusion, the results indicated that genistein mediated inflammation and had an anti­apoptotic role in treating OA. Therefore, genistein may serve as an alternative treatment for OA.