iTRAQ proteomic analysis of exosomes derived from synovial fluid reveals disease patterns and potential biomarkers of Osteoarthritis.

Exosomes extracted from synovial fluid (SF-exo) reflect the status of their originating cells. The proteomic profiles of SF-exo are important for the diagnosis of osteoarthritis (OA). To delineate the proteomic differences between SF-exo from OA patients and healthy individuals, a quantitative proteomic study based on iTRAQ technology was performed. In this study, a total of 439 proteins were identified, with 20 proteins exhibiting increased expression in the OA patient group, while 5 showed decreased expression levels. Bioinformatic analysis showed these differentially expressed proteins (DEPs) were involved in a variety of immune-related processes, including complement activation and antigen binding. For further screening, we downloaded a publicly available dataset of synovial fluid (PXD023708) and compared it with our dataset. The comparative Results identified that 5 DEPs overlapped in two datasets, and protein-protein interaction revealed that C3, C4B and APOM were key members of a tightly interactive network. Through receiver operating characteristic (ROC) curve analysis and enzyme-linked immunosorbent assay (ELISA), we confirmed 5 DEPs (C3, C4B, APOM, MMP3, DPYSL2) as potential diagnostic biomarkers for OA. And Pearson correlation analysis confirmed that most of these biomarkers had no significant linear correlation with age. Overall, our study provides the first comprehensive description of the proteomic landscape of SF-exo in OA and identifies several potential biomarkers. These findings are expected to provide valuable insights into the diagnosis and treatment of OA.