Pterostilbene inhibits ferritinophagy-mediated ferroptosis via the NRF2/NCOA4/FTH1 axis and alleviates intervertebral disc degeneration through nanoliposomal delivery.

BACKGROUND

Intervertebral disc degeneration (IVDD), a leading contributor to low back pain, is closely linked to redox imbalance. Pterostilbene (PTE) is a natural polyphenol with potent antioxidant properties.

PURPOSE: This study aimed to investigate whether PTE protects nucleus pulposus cells (NPCs) from ferroptosis under conditions of excessive oxidative stress and to evaluate the therapeutic efficacy of nanoliposomal PTE (PTE-LIP) in vivo.

METHODS

NPCs were pretreated with PTE prior to tert-butyl hydroperoxide (TBHP) stimulation. RNA sequencing and biochemical assays were performed to explore the underlying mechanisms. Lentiviral overexpression and siRNA-mediated knockdown were employed to further delineate the molecular pathway. PTE was encapsulated within nanoliposomes to improve its bioavailability and therapeutic efficacy. In vivo therapeutic efficacy was evaluated in the puncture-induced rat IVDD models using radiographic imaging (X-ray and MRI), histological analyses (H&E and SO/FG staining), and immunohistochemistry.

RESULTS

Treatment with 20 μM PTE for 24 hours was identified as the optimal protective condition based on dose- and time-dependent analyses. PTE effectively reversed TBHP-induced alterations in ferroptosis-related markers and extracellular matrix degradation. Mechanistically, PTE suppressed excessive ferritinophagy by downregulating NCOA4 and disrupting the NCOA4-FTH1 interaction. Furthermore, NRF2 functioned as an upstream regulator mediating the inhibitory effect of PTE on ferritinophagy. In vivo, intradiscal administration of PTE-LIP preserved disc structure, restored matrix homeostasis, and suppressed ferroptosis.

CONCLUSION

PTE protects NPCs from ferritinophagy-mediated ferroptosis via modulation of the NRF2/NCOA4/FTH1 axis. PTE-LIP exerted robust protective effects in vivo, underscoring its potential as a targeted nanotherapeutic strategy for IVDD.