MECHANISMS OF MICROVASCULAR THROMBOSIS IN ENDOTOXEMIA

描述（由申请人提供）：本项目将研究脓毒症实验模型中微血管血栓形成的机制。脓毒症是对感染的全身反应，是美国成人重症监护病房的主要死亡原因，微血管血栓形成是该疾病的严重并发症。我们将使用的主要模型涉及细菌内毒素（脂多糖，LPS），它介导了一种常见形式的脓毒症患者的许多表现。此外，我们将使用临床相关的腹部来源的人多微生物脓毒症模型，盲肠结扎穿孔（CLP）。我们的初步数据表明，这两种脓毒症模型增强体内微血管血栓形成，在这个项目中，我们将探讨相关的分子机制。我们的中心假设是LPS诱导的内皮细胞Toll样受体4（TLR 4）的刺激介导内毒素血症中的微血管血栓形成，其机制依赖于血小板粘附分子，糖蛋白Ibct。我们提出了四个目标：在目标1中，我们将确定哪些LPS受体介导体内微血管血栓形成的增强。在目标2中，我们将确定骨髓或非骨髓来源的细胞是否在体内介导LPS诱导的应答。在目标3中，我们将使用离体流动系统来检查内毒素血症和CLP对血小板活化和粘附到特定粘附分子（例如，vWf、P-选择素、纤维蛋白原）。在目标4中，我们将使用体内模型来定义负责LPS和CLP增强的微血管血栓形成的血小板和内皮粘附分子。这些目标的完成将拓宽我们对脓毒症模型中微血管血栓形成机制的理解。这将允许确定新的治疗靶点微血管血栓形成在这种疾病。我们的长期目标是应用从这些研究中获得的知识，使脓毒症患者及其相关的微血管改变的最佳管理。与公共卫生的相关性：脓毒症，身体对感染的反应，是美国死亡的主要原因。我们的目标是了解这种疾病严重并发症的原因，即微小血管中的凝块。这些信息将有助于为患有这种毁灭性疾病的患者开发新的治疗方法。

DESCRIPTION (provided by applicant): This project will study the mechanisms responsible for microvascular thrombosis in experimental models of sepsis. Sepsis, a systemic response to an infection, is the main cause of death in adult intensive care units in the United States, and microvascular thrombosis is a severe complication of the disease. The main model we will use involves bacterial endotoxin (lipopolysaccharide, LPS), which mediates many manifestations of patients with a common form of sepsis. In addition, we will use a clinically relevant model of human polymicrobial sepsis of abdominal origin, cecal ligation and perforation (CLP). Our preliminary data demonstrate that both sepsis models enhance microvascular thrombosis in vivo; in this project, we will explore the molecular mechanisms involved. Our central hypothesis is that LPS-induced stimulation of toll-like receptor 4 (TLR4) on endothelial cells mediates microvascular thrombosis in endotoxemia, by a mechanism dependent on the platelet adhesive molecule, glycoprotein Ibct. We propose four aims: in aim 1, we will identify which LPS receptors mediate enhancement of microvascular thrombosis in vivo. In aim 2, we will determine whether bone marrow- or non-bone marrow-derived cells mediate LPS- induced responses in vivo. In aim 3, we will use an ex vivo flow system to examine the effects of endotoxemia and CLP on platelet activation and adhesion to specific adhesion molecules (e.g.-vWf, P- selectin, fibrinogen) under physiologic flow. In aim 4, we will use the in vivo model to define the platelet and endothelial adhesion molecules responsible for LPS- and CLP-enhanced microvascular thrombosis. Completion of these aims will broaden our understanding of the mechanisms of microvascular thrombosis in models of human sepsis. This will allow identification of novel therapeutic targets for microvascular thrombosis in this disease. Our long-term goal is to apply the knowledge gained from these studies to allow optimal management of patients with sepsis and their associated microvascular alterations. Relevance to public health: Sepsis, the body's response to an infection, is a major cause of death in the U.S. Our goal is to understand the causes of a severe complication of this illness, clots in tiny blood vessels. This information would help develop new treatments for patients with this devastating illness.