Proteomic analysis of synovial fibroblast-like synoviocytes from rheumatoid arthritis.

Objectives: The purpose of this study was to identity protein expression patterns of fibroblast-like synoviocytes (FLSs) derived from the synovial tissue of patients with rheumatoid arthritis (RA) and osteoarthritis.

Methods: Two-dimensional gel electrophoresis (2-DE) in combination with matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) was used to visualise and identify differential cellular protein expression profiles in FLSs between RA and control groups. Western-blot analysis was performed to further verify selected differentially-expressed proteins.

Results: A total of 1633 and 1603 protein spots were examined in synovial FLSs of RA patients and controls, respectively. Ninety-two spots in the RA group were statistically over- or under-expressed compared with controls. Among them, 33 proteins over-expressed by more than 3-fold were then identified by MALDI-TOF-MS analysis. These proteins included enzymatic and structural proteins (e.g. PKM1/M2, α-enolase, ERp60, lamin-A/C), signal transduction proteins (e.g. annexin 11, peroxiredoxin 1, TrpRS), heat-shock/chaperone proteins (e.g. TCP-1, GRP75, HspB5, Bip) and some unknown protein species. Three proteins, namely α-enolase, GRP75 and PKM2, were verified by Western blot and the results were found to be consistent with proteomic analysis.

Conclusions: The differentially expressed proteins identified in RA synovial FLSs might be candidate RA-associated proteins and may prove to be promising diagnostic indicators or new therapeutic targets for RA.