Synovial expression of osteopontin correlates with angiogenesis in juvenile idiopathic arthritis

Objective. To evaluate the synovial expression of osteopontin (OPN) and its possible correlation with the degree of synovial angiogenesis in human chronic idiopathic arthritis. Methods. Forty-five patients with active juvenile idiopathic arthritis (JIA) were studied. All patients underwent SF aspiration before steroid injection. A paired plasma sample was collected from 22 JIA patients. Plasma from 15 age-matched healthy subjects was used as control. Plasma and SF were tested by ELISA for OPN and vascular endothelial growth factor (VEGF). Synovial tissue was obtained at synovectomy from 10 JIA patients. Immunohistochemistry was performed according to a standard technique with anti-OPN, anti-CD68, anti-CD31 anti-VEGF and anti-αvβ3 antibodies. Results. OPN levels were significantly higher in SF than in paired plasma samples (P