Yasuda T, Kakinuma T, Julovi S M, Yoshida M, Hiramitsu T, Akiyoshi M, Nakamura T
Department of Orthopaedic Surgery, Kyoto University Graduate School of Medicine, Japan.
Rheumatology (Oxford). 2004 Sep;43(9):1116-20. doi: 10.1093/rheumatology/keh274. Epub 2004 Jun 22.
To examine the mechanism of nitric oxide (NO) production by a COOH-terminal heparin-binding fibronectin fragment (HBFN-f) in rheumatoid arthritis (RA) cartilage.
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.
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.
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.
研究类风湿关节炎（RA）软骨中羧基末端肝素结合纤连蛋白片段（HBFN-f）产生一氧化氮（NO）的机制。
将RA膝关节和正常髋关节的关节软骨切片与HBFN-f一起培养。测定条件培养基中分泌的NO水平。用抗CD44抗体或HBFN-f衍生的合成肽（肽V；WQPPRARI）预处理培养物，以评估CD44在HBFN-f作用中的作用。使用异硫氰酸荧光素偶联的抗CD44抗体进行免疫荧光组织化学。
HBFN-f以剂量依赖性方式刺激NO产生。虽然RA软骨中CD44表达上调，但抗CD44抗体阻断了HBFN-f刺激的NO产生。具有肝素结合能力的肽V显著降低了HBFN-f升高的NO水平。与正常软骨相比，RA软骨对HBFN-f的反应以及抗CD44抗体对HBFN-f作用的阻断作用更强。
本研究清楚地表明，HBFN-f通过RA软骨中的CD44刺激NO产生。RA软骨中CD44表达的增加可能通过与HBFN-f等纤连蛋白片段结合增强NO产生而在关节破坏中起病理作用。
