Nobiletin ameliorates intervertebral disc degeneration by upregulating HIF-1α to inhibit endoplasmic reticulum stress-induced apoptosis.

Abstract

Intervertebral disc degeneration (IDD) is a significant factor in the etiology of low back pain (LBP); however, existing therapeutic interventions remain inadequate. Growing evidence suggests that endoplasmic reticulum stress (ERS) induced by oxidative stress (OS) promotes apoptosis of nucleus pulposus cells (NPCs) and degradation of the extracellular matrix (ECM), which is a significant pathogenic mechanism of IDD. Nobiletin (NOB), a polymethoxylated flavonoid derived from citrus peels, showcases anti-inflammatory and antioxidative characteristics. Nevertheless, the therapeutic connection with IDD has yet to be thoroughly investigated. This study aimed to demonstrate the protective effects of NOB against ERS induced by tert-butyl hydroperoxide (TBHP) in vitro, and against IDD induced by needle puncture in a rat model in vivo. Therefore, combining network pharmacology and molecular docking identified HIF-1α as a key target, a finding that was subsequently stabilized and validated by molecular dynamics simulations. Western blotting (WB) and immunofluorescence (IF) were used to detect protein expression in vitro. TUNEL staining and Flow cytometry analysis were used to detect apoptosis. Furthermore, utilizing a needle puncture-induced IDD model, the in vivo efficacy of NOB was evaluated by magnetic resonance imaging (MRI), X-ray, HE staining, safranin O-fast green (SO) staining, and immunohistochemical (IHC) staining. The findings demonstrate that NOB elevates HIF-1α expression to suppress ERS, thereby reducing apoptosis and slowing ECM degradation. In vivo experiments revealed that NOB ameliorates the progression of IDD. In conclusion, these findings highlight NOB's potential as a promising novel therapeutic strategy for IDD.