Division of Rheumatology, Department of Internal Medicine, The Konkuk University of Korea, Seoul, South Korea.
Immunol Lett. 2009 May 14;124(1):9-17. doi: 10.1016/j.imlet.2009.02.006. Epub 2009 Feb 20.
This study was undertaken to determine the effect of toll-like receptor-3 (TLR3) on the regulation of osteoclastogenic activity in rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS). The expression of receptor activator of nuclear factor kappa B ligand (RANKL) mRNA and protein in RA-FLS after TLR3 activation was determined using RT-PCR, real-time PCR, western blot analysis, and immunohistochemistry. Human monocytes were cocultured with RA-FLS that had been prestimulated by the TLR3 ligand polyriboinosinic-polyribocytidylic acid and then stained for tartrate-resistant acid phosphatase (TRAP) activity. Other markers of osteoclasts were measured using RT-PCR and real-time PCR. The expression of TLR3 and RANKL was much higher in the RA synovium than in the osteoarthritis (OA) synovium. TLR3 activation induced RANKL expression in RA-FLS, but not in OA-FLS or in normal skin fibroblasts. TLR3 activation also induced the production of IL-1beta but had no effect on IL-17 or TNF-alpha production in RA-FLS. Inhibition of IL-1beta reversed the TLR3-induced upregulation of RANKL expression. Coculture of human monocytes with TLR3-activated RA-FLS or TLR3 ligand-stimulated human monocytes increased the expression of TRAP, RANK, cathepsin K, calcitonin receptor, and MMP-9, reflecting the differentiation of monocytes into osteoclasts. Our results suggest that TLR3 promotes osteoclastogenesis in the RA synovium both directly and indirectly. TLR3 stimulates human monocytes directly to promote osteoclast differentiation. TLR3 induces RANKL expression indirectly in RA-FLS, and the expression of RANKL promotes the differentiation of osteoclasts in the RA synovium. Targeting the TLR3 pathway may be a promising approach to preventing inflammatory bone destruction in RA.
本研究旨在探讨 Toll 样受体 3（TLR3）在类风湿关节炎（RA）成纤维样滑膜细胞（FLS）中破骨细胞生成活性调节中的作用。采用 RT-PCR、实时 PCR、Western blot 分析和免疫组织化学方法检测 TLR3 激活后 RA-FLS 中核因子κB 受体激活物配体（RANKL）mRNA 和蛋白的表达。将 TLR3 配体聚肌苷酸：聚胞苷酸预先刺激后的 RA-FLS 与人类单核细胞共培养，然后对抗酒石酸酸性磷酸酶（TRAP）活性进行染色。采用 RT-PCR 和实时 PCR 检测破骨细胞的其他标志物。RA 滑膜中 TLR3 和 RANKL 的表达明显高于骨关节炎（OA）滑膜。TLR3 激活诱导 RA-FLS 中 RANKL 的表达，但 OA-FLS 或正常皮肤成纤维细胞中无此作用。TLR3 激活也诱导 IL-1β的产生，但对 RA-FLS 中 IL-17 或 TNF-α的产生无影响。IL-1β 抑制逆转了 TLR3 诱导的 RANKL 表达上调。与 TLR3 激活的 RA-FLS 或 TLR3 配体刺激的人类单核细胞共培养增加了 TRAP、RANK、组织蛋白酶 K、降钙素受体和 MMP-9 的表达，反映了单核细胞向破骨细胞的分化。我们的结果表明，TLR3 直接和间接促进 RA 滑膜中的破骨细胞生成。TLR3 直接刺激人类单核细胞促进破骨细胞分化。TLR3 间接诱导 RA-FLS 中 RANKL 的表达，RANKL 的表达促进 RA 滑膜中破骨细胞的分化。靶向 TLR3 途径可能是预防 RA 炎症性骨破坏的一种有前途的方法。
