Exploring the role and potential mechanisms of SIK1 in cartilage damage in osteoarthritis based on metabolomics.

Abstract

OBJECTIVE: To investigate the role of salt induced kinases 1 (SIK1) in osteoarthritis (OA)-related cartilage damage and its underlying metabolic mechanisms. METHODS: An OA mouse model was established using destabilization of the medial meniscus (DMM) technique. Pathological changes in cartilage tissue were evaluated using hematoxylin-eosin staining (HE) and safranin O-fast green staining. SIK1 expression levels in OA mice were assessed using immunohistochemistry and Western blot analysis. Metabolomic analysis revealed differential metabolites and signaling pathways between normal and OA mice. An adeno-associated virus (AAV) overexpressing SIK1 was constructed and used to transfect interleukin-1β (IL-1β) induced chondrocytes. Chondrocyte survival rate, DNA damage, inflammatory response, matrix degradation, and metabolic markers were assessed using CCK8 assays, immunofluorescence, ELISA, and Western blot. Subsequently, arachidonic acid (AA) was introduced to activate specific metabolic pathways, and in vivo changes in cartilage damage and metabolic homeostasis were evaluated. RESULTS: SIK1 expression was significantly downregulated in the cartilage of OA mice. Compared with the Model group, SIK1 overexpression significantly improved cartilage degeneration, reduced extracellular matrix (ECM) degradation, and lowered the Mankin score. Metabolomic analysis revealed significant activation of the AA metabolic pathway in the OA model group. SIK1 overexpression protected chondrocytes from IL-1β-induced apoptosis and inflammation. It also maintained ECM balance by increasing collagen II and aggrecan while decreasing matrix metallopeptidase 13 (MMP13). Mechanistically, AA intervention reversed the protective effects of SIK1 overexpression against OA chondrocyte injury. CONCLUSION: SIK1 ameliorated OA-related cartilage damage by inhibiting AA metabolic pathway.