Pterostilbene attenuates osteoarthritis progression through p53-dependent autophagy activation: evidence from network analysis and experimental validation.

BACKGROUND: Osteoarthritis (OA) is a prevalent degenerative joint disease characterized by cartilage destruction and functional impairment. Dysregulated autophagy plays a pivotal role in chondrocyte apoptosis and extracellular matrix (ECM) degradation. Pterostilbene (PT), a natural polyphenolic metabolite with high bioavailability, exhibits potent anti-inflammatory and antioxidant activities. However, its precise role in regulating autophagy during OA progression remains unclear. METHODS: Network analysis was employed to predict PT's potential molecular targets and signaling pathways. To experimentally evaluate the drug-target interaction, the cellular thermal shift assay (CETSA) was performed. Functional validation was subsequently conducted in vitro using IL-1β-stimulated C28/I2 chondrocytes and in vivo in a monosodium iodoacetate-induced OA rat model. The p53 inhibitor pifithrin-α was applied to verify the mechanistic dependency. RESULTS: Network analysis and molecular docking suggested p53 as a core target of PT. CETSA results supported the cellular target engagement of p53 by PT, showing that PT enhanced the thermal stability of p53 protein. In chondrocytes, PT mitigated IL-1β-induced ECM imbalance and apoptosis while enhancing Beclin1 expression and the LC3II/I ratio with reduced p62 accumulation. Mechanistically, PT promoted p53 nuclear accumulation, activated AMPK, and inhibited mTOR phosphorylation; these effects were attenuated by 3-methyladenine or pifithrin-α. In vivo, PT exhibited a dose-dependent chondroprotective effect, significantly reducing OARSI scores and restoring autophagy marker expression in cartilage tissue. CONCLUSION: This study demonstrates that PT exerts chondroprotective effects by activating autophagy through the p53/AMPK/mTOR axis, supported by evidence of specific p53 target engagement. These findings unveil a previously unrecognized molecular mechanism and underscore the translational potential of PT as a promising disease-modifying metabolite for OA therapy.