Awakening endogenous repair: salidroside boosts mitophagy in NPMSCs via SIRT1/FOXO3 to combat intervertebral disc degeneration.

BACKGROUND

Intervertebral disc degeneration (IVDD) is a major cause of low back pain, characterized by mitochondrial dysfunction and impaired mitophagy in nucleus pulposus-derived mesenchymal stem cells (NPMSCs). Sirtuin 1 (SIRT1), a key regulator of mitochondrial quality control, is downregulated in degenerated discs. Salidroside (Sal), a natural compound from Rhodiola rosea, has shown potential in enhancing mitophagy, but its mechanism in IVDD remains unclear.

METHODS

Using network pharmacology, molecular docking, and dynamics simulations, we identified SIRT1 as a key target of Sal. Human and rat NPMSCs were isolated and treated with tert-butyl hydroperoxide (TBHP) to induce degeneration. In vitro assays included CCK-8, EdU, SA-β-Gal, JC-1, Western blot, immunofluorescence, and transmission electron microscope (TEM). An in vivo rat IVDD model was established via needle puncture and treated with Sal and/or the autophagy inhibitor 3-MA. Histological, immunohistochemical, and imaging analyses were performed to evaluate IVDD.

RESULTS

Sal bound stably to SIRT1 and activated SIRT1/FOXO3 pathway, promoting mitophagic flux, reducing reactive oxygen species accumulation, and suppressing apoptosis in NPMSCs. SIRT1 knockdown or 3-MA treatment abolished Sal's protective effects. In vivo, Sal treatment preserved disc height, reduced apoptosis, and enhanced mitophagy, while 3-MA exacerbated degeneration.

CONCLUSIONS

Sal attenuates IVDD by activating SIRT1/FOXO3-mediated mitophagy, restoring mitochondrial homeostasis, and reducing NPMSCs apoptosis. These results suggest that the activation of the SIRT1/FOXO3-mitophagy axis may represent a potential therapeutic strategy for mitigating IVDD.