Ketorolac tromethamine alleviates IL-1β-induced chondrocyte injury by inhibiting COX-2 expression

Osteoarthritis (OA) is one of the most frequently diagnosed chronic diseases, and its prevalence is rising as life expectancy increases. The present study was designed to investigate the role of ketorolac tromethamine (KT) in OA by establishing an in vitro model in ATDC5 cells. The OA model was established through induction using 10 ng/ml IL-1β. KT was then used to treat the ATDC5 cells. An MTT assay was adopted to detect the viability of ATDC5 cells with or without IL-1β induction, and cyclo-oxygenase-2 (COX-2) expression in IL-1β-induced ATDC5 cells was measured via reverse transcription-quantitative (RT-q)PCR and western blotting. To explore the effects of KT on proliferation and apoptosis in IL-1β-induced ATDC5 cells, COX-2 was overexpressed and RT-qPCR was employed to detect the mRNA expression of COX-2. The viability of IL-1β-induced ATDC5 cells was detected by using a Cell Counting Kit-8 assay. In addition, levels of apoptosis and apoptosis-related proteins were determined using TUNEL staining and western blotting, respectively. Additionally, the effects of KT on oxidative stress in IL-1β-induced ATDC5 cells were also investigated. The expression levels of nitric oxide (NO) and inducible NO synthase (iNOS) were detected via NO kit assay and western blotting, respectively. In addition, the expression levels of oxidative stress-related proteins, including reactive oxygen species (ROS), superoxide dismutase (SOD) and prostaglandin E2 (PGE2), were determined using ELISA. To investigate the effects of KT on the inflammatory response and extracellular matrix (ECM) degradation, ELISA and western blotting were adopted to detect inflammatory-related proteins and ECM degradation-related proteins. Results from MTT assay indicated that KT decreased ATDC5 cell viability in a concentration-dependent manner. The expression of COX-2 was found to be downregulated in IL-1β-induced ATDC5 cells after treatment with KT, according to RT-qPCR and western blotting results. KT inhibited apoptosis and the expression levels of NO, iNOS and inflammatory-related proteins in IL-1β-induced ATDC5 cells, while COX-2 overexpression reversed these inhibitory effects. However, the increased proliferation of IL-1β-induced ATDC5 cells after the stimulation of KT was decreased by COX-2 overexpression. Additionally, KT upregulated Bcl-2, SOD, type II collagen and aggrecan expression levels in IL-1β-induced ATDC5 cells, whereas Bax, ROS, matrix metallopeptidase (MMP)1 and MMP13 expression levels were downregulated. KT promoted the proliferation of IL-1β-induced ATDC5 cells, whereas COX-2 overexpression reversed the promotive effects of KT, revealing that KT could alleviate IL-1β-induced chondrocyte injury by suppressing COX-2 expression.