Proteomic analysis of synovial tissue in rheumatoid arthritis, OLFM4 promotes fibroblast like synoviocytes proliferation in RA

Background To understand the roles of synovial tissue in rheumatoid arthritis (RA), we comprehensively investigated the protein profiles of synovial tissues in patients with RA and osteoarthritis (OA). Methods Protein were isolated from synovial tissues of 46 patients (22 with RA, 24with OA). Proteins were digested and labeled with TMT kit. All the peptide were send to LC-MS/MS analysis, and processed with Mascot and Proteome Discovery (version 1.4) search engines. All the protein data were analysis with Gene ontology (GO) and KEGG on line database. Four up-regulated protein were examined with western blotting and IHC. The RNAi were used for revealing the OLFM4 function in FLS. Results In total, over 500 proteins were identified as the different expression protein compared RA and OA synovia tissues, including 239 proteins were up-regulated in RA, and 271 proteins were up-regulated in OA. GO and KEGG analysis of the different expressed protein mostly identified as developmental processes and protein processing in ER. RT-qPCR, western blotting and IHC confirmed that there was a strong over expressed OLFM4 in RA synovia tissues. OLFM4 could be up-regulated under inflammatory stimulation, and participate in fibroblast like synoviocytes proliferation. Conclusion patients with RA possessed considerably different protein profiles of synovial tissues from with OA. The unique protein profiles of RA synovial tissues, such as the OLFM4 and MZB1 had been up-regulated compared to the OA, may reflect the pathophysiology of RA.