Metabolomics-based Approach to Analyze the Therapeutic Targets and Metabolites of a Synovitis Ointment for Knee Osteoarthritis

Abstract

Background: Knee osteoarthritis (KOA) is a clinically common degenerative joint disease that is not fatal but has a high prevalence. Synovitis ointment (HMYG) is a traditional Chinese medicine formula that has been clinically proven to treat KOA; however, its therapeutic targets remain unknown. Objective: This study aimed to identify metabolites and potential targets of synovitis ointment alleviation in rats with KOA using ultra-high-performance liquid-chromatography–mass spectrometry (UHPLC-MS) metabolomics. Methods: The meniscus on each side of the knee was removed to model KOA in rats. The synovitis ointment treatment was provided for 4 weeks. The lateral diameter of the knee was measured once a week, and after 4 weeks, serum was collected to observe changes in the knee through a metabolomic analysis. Results: Synovitis ointment reduced the lateral diameter of the knee joint, relieved knee swelling, and improved knee volume. In total, 28 differential metabolites, which were mainly involved in arginine and proline metabolism and apoptosis, were identified in the Con and HMYG groups. 15-Deoxy-d-12,14-PGJ2 and fomepizole were found to be the key metabolites after the HMYG treatment of KOA. Compared with known drugs (diclofenac diethylamine emulsion and Jin Huang San), 2-(S-Glutathionyl) acetyl glutathione, daidzein, pelargonic acid, and sulfamethoxazole increased in the HMYG, and the metabolic pathways included the oxytocin signaling pathway, platelet activation, olfactory transduction, phototransduction, and cGMP–PKG signaling pathway. The expression levels of cleaved-caspase-3, Bcl-2, PIK3a, TP53, TGFB1, and NFKB1 were reversed after HMYG treatment. Conclusion: It has been observed that synovitis ointment relieves KOA. UHPLC–MS can analyze the potential mechanism of action of the herbal compound of the synovitis ointment.