Astragaloside IV Protects Against IL-1β-Induced Chondrocyte Damage via Activating Autophagy

Background: Osteoarthritis (OA) is a chronic inflammatory condition that affects the articular cartilage. Astragaloside IV (AS-IV) constitutes the primary active component of the Chinese herbal medicine Huangqi (Radix Astragali Mongolici). AS-IV demonstrates anti-inflammatory and anti-apoptotic attributes, exhibiting therapeutic potential across various inflammatory and apoptosis-related disorders. Nevertheless, its pharmaceutical effects in OA are yet to be fully defined. Objectives: This study aimed to investigate the protective impact of AS-IV on rat chondrocytes treated with IL-1β and ascertain whether autophagy plays a role in this effect. Methods: Chondrocytes were isolated and cultivated from the knee joints of neonatal SD mice. The study included the blank control group, the model group, and the AS-IV concentration gradient group (50, 100, 200 µmol/L) to intervene with chondrocytes. The MTT assay was employed to assess cell viability at varying culture periods, enabling the determination of suitable concentration and duration. Subsequently, chondrocytes were treated with the optimal AS-IV concentration and divided into three groups: the model group replicated IL-1β-induced inflammatory chondrocyte injury, the AS-IV group received a co-culture of AS-IV and IL-1β, and a blank control group was established. Changes in cell morphology and structure were observed using ghost pen cyclic peptide staining. ELISA was used to measure TNF-α and GAG levels in cell supernatants. RT-qPCR assessed p62 and LC3 mRNA expression, while Western Blot evaluated p62 and LC3Ⅱ/Ⅰ protein expression. Results: AS-IV promoted chondrocyte proliferation and concurrently inhibited cell apoptosis. An optimal AS-IV dose of 200 µmol/L and a suitable reaction time of 48 h were identified. Ghost pen cyclic peptide staining indicated that the model group's cytoskeleton exhibited fusiform changes with reduced immunofluorescence intensity, as opposed to the blank control group. The AS-IV group displayed more polygonal cytoskeletal morphology with increased immunofluorescence intensity. AS-IV reduced TNF-α levels and elevated GAG levels in the culture supernatant. Additionally, AS-IV lowered p62 mRNA and protein expression while increasing LC3 mRNA expression in cultured chondrocytes. Conclusion: Our findings suggest that AS-IV mitigates inflammatory chondrocyte injury, safeguarding chondrocytes through a potential autophagy suppression mechanism. These results imply that AS-IV could offer preventive advantages for OA.