Peptide p[63–82] induces transcriptomic alterations associated with processes involved in cartilage repair in osteoarthritic human chondrocytes

PURPOSE: Osteoarthritis is a degenerative joint disease that can currently only be treated by alleviating pain or, ultimately, by a total joint replacement. The bone morphogenetic protein 7-derived peptide p[63-82] offers a potentially novel molecular treatment option for osteoarthritis. Mapping peptide-induced transcriptomic changes in human articular chondrocytes is expected to help reveal how p[63-82] confers its chondrocyte phenotype modulating bioactivity. MATERIALS AND METHODS: Human articular chondrocytes were isolated from the articular cartilage of patients with late-stage osteoarthritis undergoing total knee arthroplasty. Cells were stimulated with 100 nM p[63-82] peptide for 24 hours (or vehicle), after which RNA was isolated, and RNAseq was performed. Collagen type 6 levels were measured by immunoblotting, and extracellular matrix content was assessed by glycosaminoglycan measurement. RESULTS: We found a total of 1976 differentially expressed genes. Reactome and GSEA pathway analyses highlighted pathways involved in Collagen Chain Trimerization and in the Assembly of Collagen Fibrils and Other Multimeric Structures. Indeed, expression analysis demonstrated the differential upregulation of COL4A2, COL6A2, COL9A3, COL16A1, and COL18A1 in the p[63-82] condition. The p[63-82] induced upregulation of COL6 gene expression was confirmed by immunoblotting. Furthermore, we observed a p[63-82]-induced increase in glycosaminoglycan content. CONCLUSIONS: The p[63-82] peptide induces profound transcriptomic changes in primary human articular chondrocytes. One of the dominant transcriptomic alterations was the differential expression of several collagen-related genes. Many of these collagen-related genes have established roles in cartilage homeostasis. The here-acquired transcriptomic insights provide clues into the therapeutic mechanisms of action of the p[63-82] peptide in human articular chondrocytes.