RT Journal Article
SR Electronic
T1 Thrombin-Cleaved Osteopontin in Synovial Fluid of Subjects with Rheumatoid Arthritis
JF The Journal of Rheumatology
JO J Rheumatol
FD The Journal of Rheumatology
SP 240
OP 245
DO 10.3899/jrheum.080753
VO 36
IS 2
A1 MASAHIRO HASEGAWA
A1 YUTAKA NAKOSHI
A1 TAKAHIRO IINO
A1 AKIHIRO SUDO
A1 TATSUYA SEGAWA
A1 MASAHIRO MAEDA
A1 TOSHIMICHI YOSHIDA
A1 ATSUMASA UCHIDA
YR 2009
UL http://www.jrheum.org/content/36/2/240.abstract
AB Objective. Osteopontin (OPN) is an extracellular matrix glycoprotein that has been recognized as a potential inflammatory cytokine. The function of OPN is modulated by protease digestion, and a thrombin-cleaved form of OPN is involved in the pathogenesis of various inflammatory disorders. We examined thrombin-cleaved OPN products in synovial fluid from patients with rheumatoid arthritis (RA) and osteoarthritis (OA). Methods. Synovial fluid samples were obtained from knees of 20 patients with RA and 111 patients with OA. Thrombin-cleaved OPN product was determined using Western blotting. Levels of thrombin- cleaved and full-length OPN in synovial fluid were determined by ELISA. Synovia were analyzed by immunohistochemistry using an antibody specific to the thrombin-cleaved form. Results. Immunoblotting showed the presence of thrombin-cleaved OPN in synovial fluid from patients with RA and OA. ELISA results showed no difference between concentrations of full-length OPN in the synovial fluid of RA and OA patients; however, thrombin-cleaved OPN concentrations in RA synovial fluid samples were roughly 30-fold higher compared with OA samples (p < 0.001). Synovial fluid concentrations of thrombin-cleaved OPN in RA did not correlate with C-reactive protein levels. Immunohistochemistry of the synovium showed stronger reactivity in RA than in OA samples. Conclusion. Local generation of thrombin-cleaved OPN was increased in RA joints. Thrombin-cleaved OPN may be a useful biochemical marker of RA.