Trigonelline Shields Chondrocytes from Oxidative Damage in Osteoarthritis through Activation of the Keap1/Nrf2/ARE Signaling Pathway

Oxidative stress-induced chondrocyte damage is a key contributor to the progression of osteoarthritis (OA). While trigonelline (TG) possesses anti-inflammatory and antioxidant activities, its functional role and underlying mechanisms in OA remain unclear. In this study, the human chondrocyte cell line CHON-001 was treated with TG alone or in combination with IL-1 beta or ML385 for 24 h. Chondrocyte injury-related events were assessed using Cell Counting Kit-8 (CCK-8), flow cytometry with Annexin V-FITC/PI kit, Hoechst staining, the probe 2,7-Dichlorofluorescin diacetate (DCFH-DA), SA-beta-gal staining, and SOD and MDA assay kits. Our data revealed that TG alleviated IL-1 beta-induced inflammation, apoptosis, extracellular matrix (ECM) degradation, senescence, and oxidative stress in chondrocytes, accompanied by the downregulation of Keap1 and upregulation of Nrf2, HO-1 and NQO1. ML385 treatment reversed the protective effects of TG against IL-1 beta-induced injury in chondrocytes. In vivo, the anterior cruciate ligament transection (ACLT) was used to induce a rat OA model, and TG was administered by gavage. OA severity and articular cartilage degradation were evaluated by hematoxylin and eosin (H&E), toluidine blue, Safranin-O staining, and Osteoarthritis Research Society International (OARSI) scoring system. The in vivo data showed that TG attenuated the degeneration and erosion of articular cartilage, suppressed inflammation, and downregulated the levels of Keap1 and iNOS, while upregulating the levels of Nrf2 and Col2a1. In conclusion, our study demonstrated that TG inhibits oxidative stress-induced chondrocyte dysfunction and cartilage degradation by activating the Keap1/Nrf2/ARE signaling pathway.