Asperosaponin VI mitigates mitochondrial dysfunction and chondrocyte apoptosis in osteoarthritis by modulating the AMPK-SIRT3 pathway

OBJECTIVE: To investigate the therapeutic potential of Asperosaponin VI (ASA VI) from Clematis chinensis in mitigating osteoarthritis (OA) progression by modulating the AMPK-SIRT3 pathway, specifically addressing ER stress, mitochondrial dysfunction, and chondrocyte apoptosis. METHODS: In vitro studies were conducted using tert-Butyl hydroperoxide (TBHP)-treated chondrocytes to evaluate the effects of ASA VI on apoptosis, extracellular matrix (ECM) degradation, and mitochondrial function. In vivo studies were performed using a Destabilization of the Medial Meniscus (DMM) rat model to assess cartilage protection and joint integrity. Key molecular markers of ER stress (GRP78, CHOP, ATF4) and mitochondrial biogenesis (PGC-1α, TFAM, NRF-2) were analyzed through Western blotting and PCR. Histological assessments, including Safranin O and H&E staining, were used to evaluate joint architecture and cartilage degradation, while Osteoarthritis Research Society International (OARSI) scores quantified the extent of cartilage destruction. RESULTS: ASA VI treatment significantly enhanced chondrocyte viability and reduced apoptosis, as evidenced by a decrease in TUNEL-positive cells. It also preserved cartilage matrix integrity by upregulating Collagen II and Aggrecan, while reducing MMP-13 expression. Mechanistic studies revealed that ASA VI activates the AMPK-SIRT3 pathway, reducing ER stress and enhancing mitochondrial biogenesis, as indicated by increased PGC-1α, TFAM, and NRF-2 expression. Improvements in mitochondrial function were confirmed by increased ATP production and the preservation of mitochondrial membrane potential. In the DMM rat model, ASA VI treatment led to a significant reduction in cartilage degradation and OARSI scores, with histological analysis confirming improved joint architecture. Molecular analysis further validated the reduction in ER stress markers, linking these improvements to the activation of the AMPK-SIRT3 pathway. CONCLUSION: ASA VI from Clematis chinensis offers a promising therapeutic approach for OA by leveraging the AMPK-SIRT3 pathway to alleviate ER stress and mitochondrial dysfunction. This comprehensive protective mechanism contributes to reduced chondrocyte apoptosis and preserved cartilage integrity, highlighting ASA VI's potential as a novel disease-modifying agent in OA management.