[Effect of acupotomy on mitophagy mediated by PINK1/Parkin pathway in cartilage of rabbits with knee osteoarthritis].

OBJECTIVE: To observe the effect of acupotomy on mitophagy mediated by PINK1/Parkin pathway in cartilage of rabbits with knee osteoarthritis (KOA), so as to explore its mechanism in inhibiting cartilage damage. METHODS: Twenty-one New Zealand rabbits were randomly divided into normal, model, and acupotomy groups, with 7 rabbits in each group. The KOA rabbit model was established by using the Videman method. Rabbits in the acupotomy group received regular acupotomy treatment around the knee joint nodules or tendons once a week for 3 consecutive weeks. HE staining and transmission electron microscopy were used to observe the morphological and ultrastructural changes in knee joint cartilage of rabbits. Flow cytometry was used to measure the mitochondrial membrane potential (Δψm) and reactive oxygen species (ROS) average fluorescence intensity in chondrocytes. Immunofluorescence was performed to detect the fluorescence intensity of LC3B, PINK1 and Parkin in cartilage tissue. Western blot was conducted to measure the protein expression levels of p62, LC3Ⅱ/Ⅰ, PINK1, and Parkin in cartilage tissue. RESULTS: Compared to the normal group, the model group showed fissures and tissue fibrosis on the surface of rabbit knee joint cartilages, loose distribution of chondrocytes, decreased autophagosomes, and abnormal mitochondrial morphology. The fluorescence intensity of LC3B, PINK1 and Parkin, the expression levels of LC3Ⅱ/Ⅰ, PINK1 and Parkin proteins in cartilage tissue were significantly decreased (P<0.01), while the percentage of chondrocytes with low Δψm, the average fluorescence intensity of ROS, and the expression of p62 protein in cartilage tissue were significantly increased (P<0.01). Compared to the model group, the acupotomy group showed no obvious defects on the surface of rabbit knee joint cartilage, relatively dense distribution of chondrocytes, increased autophagosomes, and relatively normal mitochondrial morphology. The fluorescence intensity of LC3B, PINK1 and Parkin, the expression of LC3Ⅱ/Ⅰ, PINK1 and Parkin proteins in cartilage tissue were significantly increased (P<0.01, P<0.05), while the percentage of chondrocytes with low Δψm, the average fluorescence intensity of ROS, and the expression of p62 protein in cartilage tissue were significantly decreased (P<0.01). CONCLUSION: Acupotomy may promote mitophagy by regulating the PINK1/Parkin pathway, thereby improving cartilage damage in rabbits with KOA.

Mechanism of Action of Acupotomy in Inhibiting Chondrocyte Apoptosis in Rabbits with KOA through the PI3K/Akt Signaling Pathway.

OBJECTIVE: We examined the effects of acupotomy on the PI3K/Akt signaling pathway to elucidate the mechanism of action of acupotomy on articular chondrocyte apoptosis among rabbits with knee osteoarthritis (KOA). METHODS: New Zealand rabbits were randomly assigned to a healthy control group, placebo group, acupotomy group, and drug group, with 10 rabbits in each group. Changes in chondrocytes were examined by hematoxylin and eosin staining, and articular chondrocyte apoptosis was measured by electron microscopy and immunofluorescence. The mRNA and protein expression levels of PI3K and Akt were measured by real-time quantitative PCR and Western blot. RESULTS: In contrast, less chromatin margination and clear and smooth nuclear envelope boundary were visible in the acupotomy group and drug group. The number of apoptotic chondrocytes in the knee joint of rabbits was significantly higher in the placebo group than that in the acupotomy group and drug group (P < 0.05). The acupotomy group had a nonsignificantly lower number of apoptotic chondrocytes than the drug group (P > 0.05). Furthermore, the mRNA and protein expression levels of PI3K and Akt were significantly higher in the acupotomy group and drug group than those in the placebo group (P < 0.05) and were closer to normal levels in the acupotomy group than those in the drug group (P < 0.05). PI3K and Akt expression levels were negatively correlated with chondrocyte apoptosis in the knee joint of rabbits in all groups. CONCLUSION: Inhibiting chondrocyte apoptosis in the knee joint of KOA rabbits by upregulating the PI3K/Akt signaling pathway may be a possible mechanism of acupotomy in treating KOA.