Inhibition of the p38-MAPK signaling pathway suppresses the apoptosis and expression of proinflammatory cytokines in human osteoarthritis chondrocytes

This study aims to investigate the effects of p38-MAPK signaling pathway on the apoptosis and expression of proinflammatory cytokines in human osteoarthritis (OA) chondrocytes. Human articular cartilage specimens were obtained from 57 OA patients and 31 patients with lower extremity traumatic amputations. The expressions of p38-MAPK pathway-related proteins in cartilage tissue were detected by immunochemistry. Cultured chondrocytes isolated from human OA cartilage were assigned into the blank group, the IL-1β group, the PD (PD980959, ERK pathway inhibitors) + IL-1β group, the SB (SB203580, p38 pathway inhibitors) + IL-1β group, and the SP (SP600125, JNK signaling pathway inhibitors) + IL-1β group. Cell proliferation and apoptosis were detected by MTT assay and flow cytometry. Western blotting was used to detect the expressions of MAPK pathway-related proteins. The mRNA expressions of IL-1, IL-6, and TNF-α were detected by qRT-PCR. The positive rates of p-p38, p-JNK and p-ERK in OA cartilage were higher than those in normal cartilage. Compared with the blank group, cell proliferation rate was decreased, cell apoptotic rate was increased, the mRNA expressions of IL-1, IL-6, TNF-α and the expressions of p-p38, p-JNK and p-ERK were increased in the IL-1β group, while opposite trends were observed in the PD + IL-1β, SB + IL-1β, and SP + IL-1β groups. Our study provides evidence that inhibition of the p38-MAPK signaling pathway could suppress the apoptosis and expression of proinflammatory cytokines in human OA chondrocytes.