Disorders in angiogenesis and redox pathways are main factors contributing to the progression of rheumatoid arthritis: A comparative proteomics study

Wang JG et al. – Up–regulation of vasculature development–related proteins and down–regulation of redox–related proteins in fibroblast–like synoviocytes (FLS) are predominant factors that may contribute to the pathogenesis of rheumatoid arthritis (RA).

Methods

• Proteins extracted from primary cultures of FLS obtained from 50 patients with RA and 10 normal subjects were analyzed by automated 2–dimensional nano–electrospray ionization liquid chromatography tandem mass spectometry.
• Differentially expressed proteins were screened by 2–sample t–test (P < 0.05) and fold change (>1.5), based on the bioinformatics analysis.
• The expression of vasculature development–related proteins (Thy–1, connective tissue growth factor [CTGF], and thrombospondin 1 [TSP–1]) and redox–related proteins (superoxide dismutase 2 [SOD2]) in synovial tissue was confirmed by real–time polymerase chain reaction and Western blotting.
• The effect of Thy–1 and CTGF knockdown on Thy–1, CTGF, TSP–1, and vascular endothelial growth factor (VEGF) was analyzed by RNA interference experiments.

Results

• According to the criteria of having >1 unique peptide per protein present and a false discovery rate of ≤5%, 1,060 proteins were identified from patients with RA, and 1,292 proteins were identified from normal subjects, from which 100 differentially expressed proteins were screened out from the RA proteins.
• Of these, 46 proteins were up–regulated, and the remaining 54 proteins were down–regulated.
• Gene ontology and pathway analyses showed that 6 vasculature development–related proteins were up–regulated, including Thy–1, CTGF, and TSP–1, while 11 redox–related proteins were down–regulated, including SOD2.
• The results were consistent with those obtained using mass spectrometry.
• Thy–1, VEGF, CTGF, and TSP–1 were down–regulated after Thy–1 knockdown, and VEGF and CTGF were down–regulated after CTGF knockdown.
• Recombinant human CTGF could enhance proliferation and Transwell migration of human umbilical vein endothelial cells.

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