Mechanistic Insights into Cartilage Protection and Extracellular Matrix Remodeling: Transcriptome Analysis of Diclofenac Etalhyaluronate-Treated Knee Cartilage in Collagen-Induced Arthritis Rats and Cytokine-Stimulated Human Chondrocytes

Background Diclofenac etalhyaluronate (DF-HA, SI-613/ONO-5704) is a conjugate of hyaluronic acid (HA) and diclofenac (DF), and its intra-articular injection is widely used for the treatment of osteoarthritis in Japan. While novel mechanisms of cartilage protection by DF-HA have been identified, a comprehensive analysis of the biological responses unique to DF-HA has not yet been conducted. Design We used an RNA sequencing (RNA-seq) method to comprehensively analyze gene expression in the knee joint cartilage of arthritic rats and cytokine-stimulated chondrocytes. For the mechanistic analysis of DF-HA, genes that were downregulated or upregulated by DF-HA, HA, or DF were extracted. Pathway analysis was then performed on genes that specifically varied with DF-HA treatment. Results In the cartilage of rats with collagen-induced arthritis, treatment with DF-HA, but not DF or HA, suppressed the extracellular matrix (ECM) remodeling pathway and promoted the parathyroid hormone/parathyroid hormone-related peptide receptor-mediated pathway, which regulates chondrocyte differentiation and bone/cartilage development. In cytokine-stimulated chondrocytes, DF-HA similarly suppressed the ECM remodeling pathway; specifically, gene expression changes in IGFBP4, MMP10, MMP13 , and TIMP1 were consistent with those observed in vivo . Conclusion RNA-seq analysis of cartilage in arthritic rats and cytokine-stimulated chondrocytes provided molecular mechanistic insights, indicating that DF-HA treatment induced cartilage protection through the suppression of ECM remodeling.