Effects of Tuina on cartilage degradation and chondrocyte terminal differentiation in rats with knee osteoarthritis (KOA) via the Wnt/β-catenin signaling pathway

ObjectiveTo investigate the therapeutic effects of Tuina (Chinese therapeutic massage) in a knee osteoarthritis (KOA) rat model and its influence on proteins associated with the Wnt/beta-catenin signaling pathway.MethodsA total of 32 specific-pathogen-free grade Sprague-Dawley rats were used. Eight rats were randomly selected as the control group (CG). The remaining 24 rats underwent intra-articular injections with 0.2 mL of 4% papain to prepare the KOA rat models. After the model was established, the 24 rats were randomly and equally assigned to 3 groups, including a model group (MG), a Tuina group (TG), and a positive medicine group (PMG), with 8 rats in each group. The Lequesne score was applied to evaluate the success of model development. After the model was successfully established, the CG did not receive any intervention, and the TG was treated with local, clockwise annular Rou-Kneading around the knee joint with the thumbs. The pressure in the longitudinal direction was 3 N, and the frequency was designed to be 120-140 times/min for 15 min, followed by flexing the joint 10 times. The PMG was intragastrically administered with celecoxib [24 mg/(kg center dot bw)j every day. These interventions were performed once a day, 6 d per week, for a total of 4 weeks. After treatment, the Lequesne score was applied again to assess the severity of the KOA in the rats; hematoxylin-eosin (HE) staining and a mixture of equal volumes of aqueous solutions of safranin O-fast green were used to stain and observe the cartilage morphology and structure; the modified Mankin score was applied to evaluate the pathology; enzyme-linked immunosorbent assay method was used to quantify the C-telopeptide fragments of type II collagen (CTX-II) and cartilage oligomeric matrix protein (COMP); Western blotting was then applied to quantify Wnt4, beta-catenin, matrix metalloproteinase 13 (MMP-13), and bone morphogenetic protein 2 (BMP-2) protein expression; immunohistochemistry was conducted to determine the percentage of collagen type X (ColX)-positive cells.ResultsThe Lequesne score of the TG and PMG was both lower than that of the MG (P<0.01); the HE staining, safranin O-fast green stained morphology and structure, and modified Mankin scores of the TG and the PMG were also better than those in the MG (P<0.01). Compared with the CG, the amounts of CTX-II and COMP in the serum were significantly increased (P<0.01); the expression of Wnt4, beta-catenin, MMP-13, and BMP-2 proteins in the cartilage tissue was significantly increased (P<0.01), and the percentage of ColX-positive chondrocytes was significantly increased (P<0.01) in the MG. In comparison with those in the MG, the amounts of CTX-II and COMP were significantly decreased (P<0.01), the expression of Wnt4, beta-catenin, MMP-13, and BMP-2 proteins was significantly decreased (P<0.01), and the percentage of ColX-positive chondrocytes was significantly decreased (P<0.01) in the TG and PMG. Compared with the PMG, the contents of CTX-II and COMP and the expression of Wnt4, beta-catenin, MMP-13, and BMP-2 proteins were decreased (PP<0.01); the percentage of ColX-positive chondrocytes was significantly decreased (P<0.01) in the TG.ConclusionTuina can relieve the degeneration of KOA, and the mechanism may be related to the down-regulation of the Wnt/beta-catenin signaling pathway, the decrease in MMP-13 and BMP-2 protein expression, the reduction in chondrocyte extracellular matrix degradation, and slowing down the terminal cell differentiation.