Correlation of synovium osteoprotegrin with magnetic resonance imaging in rheumatoid arthritis

ABSTRACT

To demonstrate the role of Osteoprote grin [OPG] expression in the synovium in the pathogenesis of rheumatoid arthritis [RA] joint damage, and correlate it with Magnetic Resonance Imaging [MRI] finding. Twenty RA patients and five controls were included. RA disease activity was assessed by disease activity score [DAS 28]. MRI examination of knee joint, including evaluation of inflammation using synovitis score and evaluation of destruction with an erosion score, were performed. Knee joint's synovial biopsy specimens were obtained, by arthroscopy, to demonstrate the degree of expression of OPG by using immunohistochemical staining with monoclonal antibodies, and to study the histopathological activity scores by histopathological examination. The OPG expression was deficient [grade 0, 1] in 70% of synovial cells and 85% of endothelial cells lining of the synovial blood vessels, and grade I and 2 in 70% of infiltrating cells in active RA synovium. There was no significant association between OPG expression score [synovial, endothelial, infiltrating cells] and disease duration, number of tender swollen joints, ESR and Larsen score. There was a significant inverse correlation between OPG expression [synovial, infiltrating] and MRI erosion score. There was a highly significant correlation between MRI synovitis score and ESR, CRP, pain score, histopathological synovium score [p<0.01] and significant negative correlation with erosion score. We concluded that decrease in OPG expression in synovium has a role in pathogenesis of joint damage in RA patients, and MRI is considered a sensitive test to detect pathological lesion in joint damage in RA patients