Curcumenol regulates Histone H3K27me3 demethylases KDM6B affecting Succinic acid metabolism to alleviate cartilage degeneration in knee osteoarthritis

Background: Cartilage metabolism dysregulation is a crucial driver in knee osteoarthritis (KOA). Modulating the homeostasis can mitigate the cartilage degeneration in KOA. Curcumenol, derived from traditional Chinese medicine Curcuma Longa L., has demonstrated potential in enhancing chondrocyte proliferation and reducing Apoptosis. However, the specific mechanism of Curcumenol in treating KOA remains unclear. This study aimed to demonstrate the molecular mechanism of Curcumenol in treating KOA based on the transcriptomics and metabolomics, and both in vivo and in vitro experimental validations.

Materials and methods: In this study, a destabilization medial meniscus (DMM)-induced KOA mouse model was established. And the mice were intraperitoneally injected with Curcumenol at 4 and 8 mg/kg concentrations. The effects of Curcumenol on KOA cartilage and subchondral was evaluated using micro-CT, histopathology, and immunohistochemistry (IHC). In vitro, OA chondrocytes were induced with 10 μg/mL lipopolysaccharide (LPS) and treated with Curcumenol to evaluate the proliferation, Apoptosis, and extracellular matrix (ECM) metabolism through CCK8 assay, flow cytometry, and chondrocyte staining. Furthermore, transcriptomics and metabolomics were utilized to identify differentially expressed genes (DEGs) and metabolites. Finally, integrating multi-omics analysis, virtual molecular docking (VMD), and molecular dynamics simulation (MDS), IHC, immunofluorescence (IF), PCR, and Western blot (WB) validation were conducted to elucidate the mechanism by which Curcumenol ameliorates KOA cartilage degeneration.

Results: Curcumenol ameliorated cartilage destruction and subchondral bone loss in KOA mice, promoted cartilage repair, upregulated the expression of COL2 while downregulated MMP3, and improved ECM synthesis metabolism. Additionally, Curcumenol also alleviated the damage of LPS on the proliferation activity and suppressed Apoptosis, promoted ECM synthesis. Transcriptomic analysis combined with weighted gene co-expression network analysis (WGCNA) identified a significant downregulation of 19 key genes in KOA. Metabolomic profiling showed that Curcumenol downregulates the expression of d-Alanyl-d-alanine, 17a-Estradiol, Glutathione, and Succinic acid, while upregulating Sterculic acid and Azelaic acid. The integrated multi-omics analysis suggested that Curcumenol targeted KDM6B to regulate downstream protein H3K27me3 expression, which inhibited methylation at the histone H3K27, consequently reducing Succinic acid levels and improving KOA cartilage metabolism homeostasis. Finally, both in vivo and in vitro findings indicated that Curcumenol upregulated KDM6B, suppressed H3K27me3 expression, and stimulated collagen II expression and ECM synthesis, thus maintaining cartilage metabolism homeostasis and alleviating KOA cartilage degeneration.

Conclusion: Curcumenol promotes cartilage repair and ameliorates cartilage degeneration in KOA by upregulating KDM6B expression, thereby reducing H3K27 methylation and downregulating Succinic Acid, restoring metabolic stability and ECM synthesis.

Cartilage degeneration; Curcumenol; KDM6B; Knee osteoarthritis; Metabolomics; Transcriptomics.