ROLE OF ANGPTL4, AN ANGIOGENIC MEDIATOR, IN ARTHRITIS

血管生成可能在炎症性关节炎的发病机制中起关键作用。几种血管生成 分子，包括血管内皮生长因子和血管生成素1，增加类风湿性关节炎， 关节炎（RA），并且抑制血管生成抑制动物模型中的关节炎，例如胶原诱导的 关节炎（CIA）。我们最近发现了一个促血管生成基因，血管生成素样4（Angptl4），作为第七个 CIA小鼠关节炎爪中最高度过表达的mRNA。人Angptl4 mRNA的表达 在人类关节炎滑膜中也显著增加。血管生成素样4（Angptl4）在结构上和 在功能上类似于血管生成素，因为它特异性地抑制血管内皮细胞的凋亡。 如在小鼠和人中评估的Angptl4的表达主要限于肝、肾、脂肪组织 和滑膜发炎这种有限的组织分布表明Angptl4可能在血管生成中发挥独特的作用。 在关节炎组织中的作用。发生在关节炎滑膜内的血管生成事件的特异性靶向可能是 有利的治疗。Angptl4结合内皮细胞并可诱导内皮细胞的小管形成 体外由于Angptl4与内皮细胞结合并对内皮细胞发挥特异性作用，因此Angptl4极有可能与内皮细胞结合。 内皮细胞上的Angptl4受体介导这些作用。因此，Angptl4及其推定的受体 代表治疗炎性关节炎的主要靶向轴。在这个项目中，我们将开发 测试Angptl4通过以下方式增加炎症过程的假设所需的关键试剂： 促进关节炎滑膜组织中的血管生成。我们通过以下方式直接检验这一假设：（1）确定 在CIA小鼠模型中Angptl4缺失对关节炎的影响，以及通过（2）鉴定和表征 内皮细胞上Angptl4的受体。

Angiogenesis is likely to play a key role in the pathogenesis of inflammatory arthritis. Several angiogenic molecules, including vascular endothelial growth factor and angiopoietin 1, are increased during rheumatoid arthritis (RA), and inhibition of angiogenesis suppresses arthritis in animal models, such as collagen-induced arthritis (CIA). We recently identified a pro-angiogenic gene, angiopoietin-like 4 (Angptl4), as the seventh most highly over-expressed mRNA in arthritic paws of mice with CIA. Expression of human Angptl4 mRNA was also substantially increased in human arthritic synovium. Angiopoietin-like 4 (Angptl4) is structurally and functionally similar to the angiopoietins, in that it specifically inhibits apoptosis of vascular endothelial cells. Expression of Angptl4 as assessed in mice and humans is limited primarily to liver, kidney, adipose tissue and inflamed synovium. This limited tissue distribution suggests that Angptl4 may play a distinct angiogenic role in arthritic tissue. Specific targeting of angiogenic events occurring within arthritic synovium may be favorable therapeutically. Angptl4 binds endothelial cells and can induce tubule formation of endothelial cells in vitro. Since Angptl4 binds to and exerts specific effects on endothelial cells, it is highly likely that a receptor for Angptl4 on endothelial cells mediates these effects. Therefore, Angptl4 and its putative receptor represent a major, targetable axis in the treatment of inflammatory arthritis. In this proposal we will develop the key reagents needed to test the hypothesis that Angptl4 increases inflammatory processes by promoting angiogenesis in arthritic synovial tissues. We directly test this hypothesis by (1) determining the effects of Angptl4 depletion on arthritis in the CIA mouse model and by (2) identifying and characterizing the receptor(s) for Angptl4 on endothelial cells.