Expression of osteopontin in synovial tissue of rheumatoid arthritis: its relation to disease activity and severity

To demonstrate the expression of osteopontin in synovial tissue of patients with rheumatoid arthritis and to correlate it with disease activity and severity in order to find out its possible role in the pathogenesis of the disease. This study was conducted on 30 RA patients and 10 control subjects with post traumatic knee injury. All patients were subjected to full medical history taking, thorough clinical examination with special attention to articular manifestations [Modified disease activity score] [DAS], and spread severity index [SSI]. Laboratory investigations included: CBC, ESR, CRP and RF. Radiological investigations included: plain x-ray of the affected knee joint using Larsen's score for assessment of joint damage and expression of osteopontin [OPN] in synovial tissues of both patients and controls was determined by immunohistochemical staining of formalin fixed, paraffin embedded synovial tissues. We demonstrated by immunohistochemistry that OPN was detected as brown cytoplasmic staining expressed predominantly in the lining layer of rheumatoid synovium rather than the sublining layer and it was absent in the lymphoid aggregates. In contrast, synovial tissue of the control group showed weak scattered staining for OPN. We found a highly statistical significant difference between RA patients and controls regarding the synovial expression of OPN which was highly associated with the activity. Also, percentage of OPN positive cells was highly associated with the severity of RA assessed clinically by SSI and radiological [p<0.01]. Osteopontin is critically involved in the pathogenesis of both inflammatory and joint-destructive processes in rheumatoid arthritis. OPN may reflect disease activity and can be used as a marker of disease severity

Correlation of synovium osteoprotegrin with magnetic resonance imaging in rheumatoid arthritis

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