Ginsenoside Rg5 mitigates tenocyte death via SIRT6/autophagy-dependent signaling in an aging model

Aim The current study aimed to investigate the effects of the ginsenoside Rg5 (Rg5) on aging-induced apoptosis and ferroptosis in tenocytes and explore its mechanism of action. Methods The expression of various proteins related to this study was assessed via Western blotting. Cell viability and caspase 3 activity assays were conducted. Cellular iron content and oxidative stress markers in tenocytes were evaluated via commercial assay kits. siRNA transfection and inhibitors were used to explore the mechanism involved. In in vivo studies, H&E staining was performed to analyze the histopathology of the tendon tissue of mice. Results Rg5 treatment attenuated apoptosis, ferroptosis, ER stress, and oxidative stress in D-galactose-treated tenocytes. Moreover, it mitigated ECM degradation and enhanced cell migration in tenocytes in the presence of D-galactose. Rg5 treatment dose-dependently increased SIRT6 expression and the levels of autophagy markers, such as those associated with LC3 conversion and p62 degradation. siRNA-mediated suppression of SIRT6 or 3-MA, an autophagy inhibitor, reduced the effects of Rg5 on D-galactose-treated tenocytes. Rg5 administration improved tissue damage as well as ER stress and ferroptosis markers in the Achilles tendons of mouse models established by local injection of D-galactose and collagenase type I. In addition to the in vitro results, it promoted SIRT6 expression and p62 degradation in in vivo studies. Conclusion These results suggest that Rg5 attenuates ER stress and oxidative stress through the SIRT6/autophagy axis, thereby mitigating ferroptosis and apoptosis in aging-conditioned tenocytes. The present study sheds light on a novel therapeutic strategy for aging-mediated tendinopathy involving the use of Rg5.