COOH-terminal heparin-binding fibronectin fragment induces nitric oxide production in rheumatoid cartilage through CD44.
OBJECTIVE
To examine the mechanism of nitric oxide (NO) production by a COOH-terminal heparin-binding fibronectin fragment (HBFN-f) in rheumatoid arthritis (RA) cartilage.


METHODS
Articular cartilage slices from RA knee joints and normal hip joints were cultured with HBFN-f. Secreted NO levels in conditioned media were determined. Cultures were pretreated with anti-CD44 antibody or HBFN-f-derived synthetic peptide (peptide V; WQPPRARI) to evaluate the role of CD44 in HBFN-f action. Immunofluorescence histochemistry was performed using fluorescein isothiocyanate-conjugated anti-CD44 antibody.


RESULTS
HBFN-f stimulated NO production in a dose-dependent manner. Whereas CD44 expression was up-regulated in RA cartilage, anti-CD44 antibody blocked HBFN-f-stimulated NO production. Peptide V with heparin-binding ability significantly reduced NO levels elevated by HBFN-f. Compared with normal cartilage, cartilage response to HBFN-f and the blocking effects of anti-CD44 antibody on HBFN-f action were stronger in RA cartilage.


CONCLUSIONS
The present study clearly demonstrated that HBFN-f stimulated NO production through CD44 in RA cartilage. Increased expression of CD44 in RA cartilage may play a pathological role in joint destruction through enhanced NO production by binding to fibronectin fragments such as HBFN-f.
Yasuda
T
T
Department of Orthopaedic Surgery, Kyoto University Graduate School of Medicine, Japan. tyasuda-jsb@umin.ac.jp
Kakinuma
T
T
Julovi
S M
SM
Yoshida
M
M
Hiramitsu
T
T
Akiyoshi
M
M
Nakamura
T
T
D000368:Aged; D000906:Antibodies / Q000276:immunology; D001172:Arthritis, Rheumatoid / Q000276:immunology / Q000378:metabolism*; D002358:Cartilage, Articular / Q000276:immunology / Q000378:metabolism*; D046508:Culture Techniques; D004305:Dose-Response Relationship, Drug; D005260:Female; D005353:Fibronectins / Q000378:metabolism*; D006801:Humans; D018960:Hyaluronan Receptors / Q000276:immunology*; D007150:Immunohistochemistry / Q000379:methods; D007719:Knee Joint; D008856:Microscopy, Fluorescence / Q000379:methods; D008875:Middle Aged; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D015854:Up-Regulation
D000906:Antibodies; D005353:Fibronectins; D018960:Hyaluronan Receptors; D009569:Nitric Oxide; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II