RICKETTSIAL EFFECTS ON ENDOTHELIAL PROCOAGULANT ACTIVITY

体外培养的血管内皮细胞已被广泛用作模型 系统，用于研究这些细胞的体内功能， 抗血小板屏障 培养的内皮细胞的扰动 通过可溶性试剂如细胞因子、脂多糖、酶、免疫 和物理损伤被认为会诱导促血小板变化， 这些细胞类似于体内存在的细胞。 这些变化包括 组织因子的产生，血栓调节蛋白的下调， von Willebrand因子和增强的血小板粘附。不过有 几乎没有直接的实验证据表明这些内皮细胞 改变和体内实际血栓形成。这样做的目的 应用是使用斑点热群立克次体， Akari作为内皮细胞促血小板变化的精确探针， 培养的内皮细胞，离体人脐带静脉，和 在实验性C3 H/HeJ小鼠模型中体内。立克次体主要感染 导致局部炎症反应的血管内皮 和形成局灶性血栓，引起器官功能障碍， 偶尔对人类造成致命后果。 最初的性质和时间 立克次体感染引起的促血小板变化的过程 将测定培养的内皮细胞并与 炎性刺激物如白细胞介素-1、肿瘤坏死因子α 和脂多糖。 立克次体感染对组织的影响 因子和血栓调节蛋白表达，以及血小板粘附特性， 培养的内皮细胞将被广泛表征。 一旦这些 的变化，立克次体感染引起的变化， 内皮细胞在离体脐带模型和体内 将确定小鼠模型，以确定它们是否具有可比性。 如果 如果成功，该研究将验证体外 内皮细胞培养系统作为体内血栓性疾病的镜子。

Vascular endothelial cells grown in vitro have been widely used as model systems for investigations of the in vivo function of these cells as an anti-thrombocytic barrier. Perturbation of the cultured endothelial cells by soluble agents such as cytokines, lipopolysaccharide, enzymes, immune and physical injury are thought to induce prothrombocytic alterations in these cells which resemble those occurring in vivo. These changes include production of tissue factor, down regulation of thrombomodulin, release of von Willebrand factor, and enhanced platelet adherence. However, there is little direct experimental evidence correlating these endothelial cell alterations and actual thrombus formation in vivo. The purpose of this application is to use the spotted fever group rickettsia, Rickettsia akari, as a precise probe of endothelial cell prothrombocytic changes in cultured endothelial cells, ex vivo in human umbilical cord veins, and in vivo in an experimental C3H/HeJ mouse model. Rickettsiae primarily infect the vascular endothelium resulting in a localized inflammatory response and formation of focal thromboses which induce organ disfunction and occasionally fatal outcome in humans. Initially the nature and time course of prothrombocytic alterations caused by rickettsial infection of cultured endothelial cells will be determined and compared with inflammatory stimuli such as interleukin-1, tumor necrosis factor alpha and lipopolysaccharide. The effects of rickettsial infection on tissue factor and thrombomodulin expression, and platelet adherence properties of cultured endothelial cells will be extensively characterized. Once these changes are understood, the changes induced by rickettsial infection in endothelial cells in the ex vivo umbilical cord model and in the in vivo mouse model will be determined to see if they are comparable. If successful, the study would validate the relevance of the in vitro endothelial cell culture system as a mirror of in vivo thrombotic disease.