Intracellulan signal : ry pathways involving bone destruction

探讨核因子κ B受体激活因子配体（RANKL）参与类风湿滑膜细胞破骨形成的机制。采用北方印迹法检测5例类风湿关节炎（RA）患者滑膜组织和骨关节炎（OA）患者滑膜组织中RANKL的表达。在存在或不存在1，25（OH）2D 3的情况下，在与PBMC共培养中研究RANKL表达和滑膜成纤维细胞支持破骨细胞生成的能力，并通过酶联免疫吸附试验测量可溶性RANKL/ODF和骨保护素（OPG）。观察OPG对类风湿关节炎滑膜细胞原代培养及共培养体系中破骨细胞生成的影响。滑膜成纤维细胞与PBMC单独共培养时，不诱导破骨细胞生成。北方印迹显示RANKL/ODF在RA和GCT患者的所有组织中均高表达，但在OA和OS患者中不表达。在1，25（OH）2D 3存在下，培养的类风湿性滑膜成纤维细胞有效地诱导破骨细胞生成，这伴随着RANKL的表达上调和OPG/OCIF的产生减少。OPG剂量依赖性地抑制滑膜细胞的破骨细胞生成。结论：滑膜成纤维细胞上表达的RANKL/ODF通过诱导破骨细胞生成参与类风湿性骨破坏，因此将是良好的治疗靶点。

To clarify the mechanism by which osteoclasts are formed in culture of rheumatoid synoviocytes by exploring the involvement of receptor activator of nuclear factor kappaB ligand (RANKL). RANKL expression was examined by Northern blotting in synovial tissues from 5 rheumatoid arthritis (RA) patients and tissues from patients with osteoarthritis (OA). RANKL expression and the ability of synovial fibroblasts to support osteoclastogenesis were investigated in coculture with PBMC in the presence or absence of 1, 25(OH)2D3, and soluble RANKL/ODF and osteoprotegerin (OPG) were measured by enzyme-linked immunosorbent assay. The effects of OPG on the osteoclastogenesis in the primary culture of rheumatoid synoviocytes and the coculture system were determined. Synovial fibroblasts did not induce osteoclastogenesis when separately cocultured with PBMC. Northern blotting revealed that RANKL/ODF was highly expressed in all tissues from RA and GCT patients, but not from OA or OS patients. Cultured rheumatoid synovial fibroblasts efficiently induced osteoclastogenesis in the presence of 1, 25(OH)2D3, which was accompanied by up-regulated expression of RANKL and decreased production of OPG/OCIF. Osteoclastogenesis from synoviocytes was dose-dependently inhibited by OPG. CONCLUSION : RANKL/ODF expressed on synovial fibroblasts is involved in rheumatoid bone destruction by inducing osteoclastogenesis and would therefore be a good therapeutic target.