[Expression of peroxisome proliferator-activated receptor-gamma coactivator 1β in synovium in patients with rheumatoid arthritis and its clinical significance].

Objective: To investigate the expression of peroxisome proliferator-activated receptor-gamma coactivator (PGC)1β in synovium of patients with rheumatoid arthritis (RA) and its association with histological synovitis. Methods: This cross-sectional study recruited RA patients at the Department of Rheumatology, Sun Yat-Sen Memorial Hospital from May 2010 to October 2016. Clinical data were collected. Conventional radiographs of bilateral hands and wrists were performed and assessed according to Sharp/van der Heijde-modified Sharp score(mTSS). Synovial tissues from knee joints of all RA patients were obtained by biopsies, and then stained with HE and immunohistochemically for PGC-1β, CD3, CD20, CD38, CD68, CD15 and CD34 to evaluate synovitis, synovial PGC-1β expression and the densities of inflammatory cells and endothelial cells. The relationship between synovial PGC-1β expression and histological synovitis, disease activity and joint destruction in RA was analyzed by Spearman's rank correlation and multivariate linear regression. Results: There were 83 RA patients recruited with 20 (24.1%) males and 63 (75.9%) females, aged (54±14) years. PGC-1β expressed in the nuclei of lining synoviocytes, sublining inflammatory cells and vascular endothelial cells of RA synovium. The percentage of synovial PGC-1β+cells was positively correlated with histological synovitis score (r=0.333) and the densities of sublining CD3+ T cells (r=0.259), CD20+ B cells (r=0.320), CD38+plasma cells (r=0.342) and CD68+ macrophages (r=0.309)(all P<0.05). It was also positively correlated with erythrocyte sedimentation rate, C reactive protein and total mTSS (r=0.219-0.301, all P<0.05). Multiple linear regression analysis further confirmed the positive correlation between the percentage of synovial PGC-1β+cells and mTSS (β=0.312, P=0.004). Conclusion: Synovial PGC-1β is positively associated with local and systemic inflammation as well as joint destruction, which implies that PGC-1β might involve in the pathogenesis of synovitis and joint destruction in RA.