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

## TL;DR

Pterostilbene helps reduce osteoarthritis by boosting autophagy through a key protein called p53, offering a new treatment possibility.

## Contribution

The study reveals a novel p53-dependent mechanism by which pterostilbene activates autophagy to protect cartilage in osteoarthritis.

## Key findings

- Pterostilbene engages p53 and activates autophagy in chondrocytes, reducing ECM degradation and apoptosis.
- In vivo, pterostilbene showed dose-dependent chondroprotective effects and improved autophagy markers in OA rats.
- Mechanistically, pterostilbene activates the p53/AMPK/mTOR pathway, which is inhibited by p53 suppression or autophagy blockade.

## Abstract

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.

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.

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.

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.