LPS INDUCED ENDOTHELIAL CELL ACTIVATION AND APOPTOSIS

感染性休克是革兰氏阴性杆菌感染的潜在致命后果 和阳性细菌感染，是受害者的重要并发症 创伤性损伤有多种细菌产物与 致病分子包括细菌脂蛋白，脂多糖， (LPS)、脂磷壁酸、肽聚糖、细胞壁产物等。 实验动物被证明激活了内在细胞“自杀”程序， 导致多种细胞类型的凋亡。深入了解分子基础 脓毒症引起的细胞活化/凋亡的强度 希望能找到新的治疗方法。的信号传导 细菌产物通过最近描述的Toll样受体发生 (TLR)在细胞表面。导致NF κ B的细胞内途径 TLR-2和TLR-4的激活沿着沿着类似的途径进行（这两个 显示对细菌产物有反应的受体）。然而，凋亡途径 受到的关注较少。研究人员将检查败血症引起的 细胞凋亡和一种新的体外激活途径以及基因的作用 改变导致单核细胞、淋巴细胞和 内皮细胞在体内。他们最近表明，细胞凋亡途径 用LPS刺激后，通过FADD依赖性信号传导进行， 阻断NF κ B不会使内皮细胞对死亡敏感。这些 观察导致关于死亡途径和内在的问题， 细胞保护途径。由于LPS抵抗细胞中存在大量的凋亡， 我们还推测TLR-2在脓毒症中提供了 TLR-4缺陷小鼠的激活信号和死亡信号。而且他们 已经观察到导致内皮细胞活化的两种途径。首先，老鼠 缺乏功能性Fas（lpr）或FasL（gld）的人对LPS的应答降低， 他们假定Fas-FasL系统是促炎性的。第二，具体 caspase-8抑制剂降低LPS诱导的VCAM-1表达。他们假设， 这种蛋白酶也发出内皮细胞活化的信号。具体目标 1）探讨MyD 88、IL-1受体在MyD 88中的作用。 相关激酶和TNF受体相关因子-6在脓毒症诱导的 单核细胞/巨噬细胞和内皮细胞的凋亡; 2）确定 Fas-FasL等分子在细胞凋亡途径中作用 LPS诱导的内皮细胞的炎症反应;和3）检测LPS诱导的内皮细胞的炎症反应。 单核细胞、淋巴细胞或内皮细胞中凋亡基因改变的影响 在小鼠中诱导脓毒症后的存活率。

Septic shock is a potentially lethal consequence of gram negative and positive bacterial infection and is a significant complication in victims of traumatic injury. There are multiple bacterial products implicated as pathogenic molecules including bacterial lipoproteins, lipopolysaccharide, (LPS), lipoteichoic acid, peptidoglycans, cell wall products, etc. Sepsis in experimental animals was shown to activate the intrinsic cell "suicide" program leading to apoptosis in multiple cell types. Insights into the molecular basis of cellular activation/apoptosis in response to sepsis are under intense investigation in the hope of finding new approaches to therapy. Signaling by bacterial products occurs through the recently described Toll-like receptors (TLR) on the surface of cells. Intracellular pathways leading to NFkappaB activation proceed along similar pathways for TLR-2 and TLR-4 (the two receptors shown to respond to bacterial products). However, apoptosis pathways have received less attention. The investigators will examine sepsis-induced apoptosis and a novel activation pathway in vitro as well as the effect of gene alterations that lead to decreased apoptosis in monocytes, lymphocytes and endothelial cells in vivo. They have recently shown that the apoptotic pathway following stimulation with LPS proceeds through FADD dependent signaling and that blockade of NFkappaB does not sensitize endothelial cells to death. These observation lead to questions regarding the death pathway and intrinsic cyto-protective pathways. Since considerable apoptosis occurs in LPS resistant (TLR-4 deficient) mice during sepsis, we also speculate that TLR-2 provides both activation signals and death signals in TLR-4 deficient mice. Also, they have observed two pathways leading to endothelial cell activation. First, mice lacking functional Fas (lpr) or FasL (gld) have reduced responses to LPS, and they postulate that the Fas-FasL system is pro-imflammatory. Second, a specific caspase-8 inhibitor reduces LPS-induced VCAM-1 expression. They postulate that this protease also signals for endothelial cell activation. The specific aims of this project are: 1) To determine the role of MyD88, Il-1 receptor- associated kinase and TNF receptor- associated factor-6 in sepsis-induced apoptosis of monocytes/macrophages and endothelial cells; 2) To determine the contribution of Fas-FasL and other molecules in that apoptosis pathway in LPS-induced inflammatory response of endothelial cells; and 3) To examine the effects of apoptotic gene alterations in monocytes, lymphocytes or endothelial in survival following induction of sepsis in mice.