Endothelial Toll-Like Receptor-4 Signaling in Sepsis

脓毒症中的内皮 Toll 样受体 4 信号转导

• 批准号: 7031621
• 负责人: JOHN Marshall HARLAN
• 金额: $ 22.21万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-05-01 至 2009-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7031621
• 关键词: apoptosis; genetically modified animals; gram negative bacteria; immune response; inflammation; laboratory mouse; lipopolysaccharides; nuclear factor kappa beta; septicemia; tissue /cell culture; toll like receptor; tumor necrosis factor alpha; vascular endothelium

DESCRIPTION (provided by applicant): Sepsis and sepsis syndromes are life-threatening conditions and are leading causes of death in intensive care units. Sepsis is most commonly caused by Gram-negative bacteria. Lipopolysaccharide (LPS) is an important component of the bacteria wall that contributes to the pathogenesis of sepsis. Endothelial cells (ECs) are a major target of LPS and the pro-inflammatory cytokines interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNFalpha). Lipopolysaccharide, IL- 1beta, and TNFalpha all directly activate ECs and elicit an array of EC responses, including the upregulation of cytokines, chemokines, adhesion molecules, and procoagulant proteins. Most of these pro-inflammatory responses are mediated by the transcription factor NF-KappaB, which is also important for cell survival. Endothelial cell activation is thus thought to play a critical role in the development of both host defense and the systemic inflammatory response in sepsis. Increasing evidence also indicates that EC apoptosis contributes to the pathogenesis of experimental sepsis. Indeed, it has been suggested that a significant component of the beneficial effects of activated protein C, the only approved drug for the treatment of severe sepsis in man, may be due to its anti-apoptotic effects on ECs . The cellular receptor transducing the LPS signal has been identified as Toll-like receptor(TLR)4, a member of the larger family of TLR receptors. In this proposal we will examine further the molecular mechanisms of pro-inflammatory, pro-survival, and pro-apoptotic signaling by TLR4 in EC in vitro and determine the role of EC activation and apoptosis in vivo using transgenic mice in experimental sepsis induced by cecal ligation and puncture (CLP). The specific aims are: 1) To determine the role of phosphoinositide-3 kinase (PI3-K) in EC survival following LPS/TLR4 stimulation; 2) To determine the mechanisms of LPS/TLR4-lnduced pro-apoptotic signaling in ECs; 3) To identify new components of the TLR4-induced TRAF6-signaling complex in ECs; and 4) To determine the effect of inducible, selective blockade of EC NF-KappaB activation and apoptosis on sepsis induced by CLP.

描述（由申请人提供）： 脓毒症和脓毒症综合征是危及生命的疾病，也是重症监护病房死亡的主要原因。脓毒症最常见是由革兰氏阴性菌引起的。脂多糖（LPS）是细菌壁的重要组成部分，有助于脓毒症的发病机制。内皮细胞 (EC) 是 LPS 和促炎细胞因子白介素-1β (IL-1β) 和肿瘤坏死因子-α (TNFα) 的主要靶标。脂多糖、IL-1β和TNFα均直接激活EC并引发一系列EC反应，包括细胞因子、趋化因子、粘附分子和促凝血蛋白的上调。大多数促炎症反应是由转录因子 NF-KappaB 介导的，该因子对于细胞存活也很重要。因此，内皮细胞激活被认为在脓毒症宿主防御和全身炎症反应的发展中发挥着关键作用。越来越多的证据还表明，EC 细胞凋亡有助于实验性脓毒症的发病机制。事实上，有人认为，活化蛋白 C（唯一被批准用于治疗人类严重脓毒症的药物）的有益作用的一个重要组成部分可能是由于其对 EC 的抗凋亡作用。 转导 LPS 信号的细胞受体已被鉴定为 Toll 样受体 (TLR)4，它是 TLR 受体大家族的成员。在本提案中，我们将进一步研究体外 EC 中 TLR4 促炎症、促生存和促凋亡信号传导的分子机制，并使用转基因小鼠在盲肠结扎穿刺 (CLP) 诱导的实验性脓毒症中确定体内 EC 激活和凋亡的作用。具体目标是： 1) 确定磷酸肌醇 3 激酶 (PI3-K) 在 LPS/TLR4 刺激后 EC 存活中的作用； 2) 确定内皮细胞中LPS/TLR4诱导的促凋亡信号传导机制； 3) 鉴定 EC 中 TLR4 诱导的 TRAF6 信号复合物的新成分； 4) 确定诱导性、选择性阻断 EC NF-KappaB 激活和细胞凋亡对 CLP 诱导的脓毒症的影响。