Berberine suppresses apoptosis and extracellular matrix (ECM) degradation in nucleus pulposus cells and ameliorates disc degeneration in a rodent model

Intervertebral disc degeneration (IVDD) is a chronic disease with complicated pathology involving nucleus pulposus (NP) cell apoptosis and extracellular matrix (ECM) degradation. Previous studies have shown that moderate autophagy has a protective effect against apoptosis in NP cells. Berberine (BBR) is an alkaloid compound with many beneficial properties including antimicrobial, anti-inflammatory, antioxidative, and anti-apoptotic activity. Recently, it was found to induce autophagy in various tissues as well. Thus, we hypothesized that BBR may exert a therapeutic effect on IVDD through autophagy activation. In this study, we investigated the effects of BBR on IVDD and delineated a potential mechanism. BBR treatment in vitro inhibited the expression of pro-apoptotic proteins induced by tert-butyl hydroperoxide (TBHP), and increased the expression of anti-apoptotic Bcl-2. Furthermore, it prevented ECM degradation by inhibiting the production of matrix-degrading enzymes. Additionally, BBR treatment significantly activated autophagy in NP cells. However, autophagy inhibition markedly suppressed BBR's effects on NP cell apoptosis and ECM degeneration, indicating that autophagy activation with BBR treatment is protective against IVDD. In vivo, BBR treatment increased the expression of LC3 in disc cells and prevented the development of IVDD in a needle puncture-induced rat model. Thus, BBR stimulates autophagy as a protective mechanism against NP cell apoptosis and ECM degeneration, revealing its therapeutic potential in the treatment of IVDD.