PT - JOURNAL ARTICLE AU - Kiori Shio AU - Hiroko Kobayashi AU - Tomoyuki Asano AU - Rie Saito AU - Haruyo Iwadate AU - Hiroshi Watanabe AU - Hirofumi Sakuma AU - Tetsuya Segawa AU - Masahiro Maeda AU - Hiromasa Ohira TI - Thrombin-cleaved Osteopontin Is Increased in Urine of Patients with Rheumatoid Arthritis AID - 10.3899/jrheum.090582 DP - 2010 Feb 15 TA - The Journal of Rheumatology PG - jrheum.090582 4099 - http://www.jrheum.org/content/early/2010/02/11/jrheum.090582.short 4100 - http://www.jrheum.org/content/early/2010/02/11/jrheum.090582.full AB - Objective To measure concentrations of the thrombin-cleaved isoform of osteopontin (OPN) in urine and plasma of patients with rheumatoid arthritis (RA), and to assess whether levels of thrombin-cleaved OPN are associated with measures of RA. Methods Subjects comprised 70 patients with RA, 20 patients with osteoarthritis (OA), and 46 healthy controls. RA disease activity was evaluated by tender joint count, swollen joint count, patient’s global assessment of disease activity, erythrocyte sedimentation rate (ESR), and levels of C-reactive protein (CRP), matrix metalloproteinase-3 (MMP-3), and rheumatoid factor (RF), as well as 28-joint count Disease Activity Score (DAS28). OPN levels in plasma and urine were measured by ELISA. Results Median levels of thrombin-cleaved OPN in urine (U-half) were significantly higher in RA patients (143.5 pmol/mmol Cr) than in healthy controls (67.9 pmol/mmol Cr) or OA patients (69.8 pmol/mmol Cr). Thrombin-cleaved OPN was not detected in plasma. U-half levels correlated significantly with levels of CRP (r = 0.26, p = 0.03), ESR (r = 0.26, p = 0.03), and RF (r = 0.28, p = 0.03). Median U-half levels were significantly higher in patients with stage III (249.9 pmol/mmol Cr) and IV (251.6 pmol/mmol Cr) disease than in patients with stage I (98.6 pmol/mmol Cr) disease. Conclusion Our results suggest that urine levels of the thrombin-cleaved isoform of OPN may reflect the severity of active inflammatory arthritis in patients with RA.