DUSP4 alleviates LPS-induced chondrocyte injury in knee osteoarthritis via the MAPK signaling pathway

Knee osteoarthritis (KOA) is characterized by cartilage damage, and the associated pathogenesis is complex. The expression of dual specificity protein phosphatase 4 (DUSP4) is significantly decreased in osteoarthritis (OA); however, the specific role and mechanism underlying DUSP4 in OA are yet to be elucidated. ATDC5 cells were treated with lipopolysaccharide (LPS) to establish the cell injury model. The expression levels of DUSP4 were decreased in OA chondrocytes, demonstrated by reverse transcription-quantitative PCR and western blot analysis. Following overexpression of DUSP4 by cell transfection, Cell Counting Kit-8, ELISA, TUNEL and western blotting assays were used to detect the cell viability, oxidative stress, inflammation and apoptosis levels of LPS-induced ATDC5 cells. Overexpression of DUSP4 inhibited the activation of the MAPK signaling pathway, thereby reducing oxidative stress levels, inflammatory response and apoptosis in the OA cell model. The mechanisms underlying DUSP4 in OA were further explored following the addition of MAPK signaling pathway agonist, phorbol 12-myristate 13-acetate (PMA). The addition of PMA reversed the inhibitory effects of DUSP4 overexpression on oxidative stress, inflammatory response and apoptosis in cells. In summary, DUSP4 alleviated LPS-induced chondrocyte injury in KOA via the MAPK signaling pathway.