Oligomeric proanthocyanidins inhibit apoptosis of chondrocytes induced by interleukin-1β

Oligomeric proanthocyanidin (OPC) is a water-soluble plant polyphenolic compound known for its cytoprotective effects in various tissue types. However, its effect on chondrocytes has not been well characterized. The present study aimed to investigate the effect of OPC on interleukin‑1β (IL‑1β)‑induced apoptosis in chondrocytes, and to determine the mechanisms underlying the protective effects of OPC. Knee articular chondrocytes obtained from 6‑week‑old SPF Kunming mice were cultured and serially passaged. First‑generation chondrocytes were selected for subsequent experiments following toluidine blue staining. Subsequent to IL‑1β and OPC administration, an MTT assay was performed to examine the viability rate of chondrocytes, and the optimal drug concentration was determined. The fluorescence dye 2',7'-dichlorofluorescein diacetate was used to determine the intracellular content of reactive oxygen species (ROS). Mitochondrial membrane potential (MMP) was measured using a 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethyl-benzimidazolylcarbocyanine iodide (JC‑1) assay. The apoptosis rate of chondrocytes was assessed using an Annexin V‑FITC/PI assay and ultrastructural changes were observed under an electron microscope. The results demonstrated that OPC increased the survival rate of chondrocytes against IL‑1β‑induced apoptosis. The most significant protective effect of OPC was observed at the concentration of 0.050 mg/ml. OPC reversed the increased ROS content and MMP levels, and inhibited IL‑1β‑induced apoptosis in chondrocytes. In addition, OPC was revealed to protect the ultrastructural integrity of chondrocytes. Taken together, the results of the present study suggest that OPC protects chondrocytes against IL‑1β‑induced damage by decreasing ROS content and MMP levels.