Isoliquiritigenin mitigates intervertebral disc degeneration induced by oxidative stress and mitochondrial impairment through a PPARγ-dependent pathway

Abstract

Objectives: Oxidative stress, mitochondrial dysfunction, and apoptosis play significant roles in the degradation of extracellular matrix (ECM) in nucleus pulposus cells (NPCs), ultimately contributing to intervertebral disc degeneration (IVDD). This study investigates the potential of isoliquiritigenin (ISL), a natural extract known for its antioxidant, anti-inflammatory, and anti-atherosclerotic properties, to alleviate IVDD.

Methods: The viability of NPCs treated with ISL and tert-butyl hydroperoxide (TBHP) was assessed using the CCK-8 assay. Various techniques, including Western blot, qRT-PCR, immunofluorescence (IF), and immunohistochemistry, were employed to measure the expression of ECM components, oxidative stress markers, and apoptosis-related proteins. Mitochondrial function was evaluated through Western blot and IF analyses. Network pharmacology predicted ISL targets, and the expression levels of PPARγ were assessed using the aforementioned methods. The role of PPARγ in the therapeutic effects of ISL on IVDD was examined through siRNA knockdown. The therapeutic impact of ISL on puncture-induced IVDD in rats was evaluated using X-ray, MRI, and histological staining techniques.

Results: In vitro, ISL reduced oxidative stress in NPCs, restored mitochondrial function, inhibited apoptosis, and improved the ECM phenotype. In vivo, ISL slowed the progression of IVDD in a rat model. Further analysis revealed that ISL enhances PPARγ activity and promotes its expression by direct binding, contributing to the delay of IVDD progression.

Conclusion: This study demonstrates that ISL effectively treats puncture-induced IVDD in rats by inhibiting oxidative stress, restoring mitochondrial function, and reducing NPC apoptosis through a PPARγ-dependent mechanism. By balancing ECM synthesis and degradation, ISL presents a novel therapeutic approach for IVDD and identifies a promising target for treatment.

Keywords: Apoptosis; Intervertebral disc degeneration; Isoliquiritigenin; Mitochondrial dysfunction; Oxidative stress; Peroxisome proliferator-activated receptor γ.