Detection of citrullinated proteins in synovial fluids derived from patients with rheumatoid arthritis by proteomics-based analysis

Abstract

Background: Rheumatoid arthritis (RA) is the most common inflammatory joint disease. The aetiology of RA remains unknown, but autoimmune responses are considered to play an important role in the disease pathophysiology. Currently available data suggests that the process of diagnosing RA may benefit from testing for anticyclic citrullinated peptides. Identification of the presence of citrullinated proteins in rheumatoid synovial fluids is important for the elucidation of the aetiology of RA as well as in the differential diagnosis of rheumatic-related diseases. Methods: A proteomics-based approach using electrophoresis/mass spectrometry was applied to identify the citrullinated proteins in synovial fluids from patients with RA. Synovial fluids from patients with RA were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analysis to detect the citrullinated proteins. Identification bands were then subjected to mass spectrometry. Results: Three proteins - citrullinated fibrinogen, citrullinated fibronectin and citrullinated vimentin - in synovial fluids from RA patients were identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Conclusions: Proteomics-based analysis can be used to detect citrullinated proteins in synovial fluids from RA patients.