MECHANISMS OF MICROVASCULAR THROMBOSIS IN ENDOTOXEMIA

描述(申请人提供)：本项目将在脓毒症的实验模型中研究微血管血栓形成的机制。败血症是对感染的一种全身反应，是美国成人重症监护病房的主要死亡原因，微血管血栓形成是这种疾病的严重并发症。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人类腹源性多菌败血症、盲肠结扎和穿孔(CLP)的模型。我们的初步数据表明，两种脓毒症模型都能在体内增强微血管血栓形成；在本项目中，我们将探索其中涉及的分子机制。我们的中心假设是，内毒素诱导内皮细胞刺激Toll样受体4(TLR4)，通过依赖于血小板黏附分子糖蛋白IBCT的机制，介导内毒素血症的微血管血栓形成。我们提出了四个目标：在目标1中，我们将确定哪些内毒素受体介导体内微血管血栓的增强。在目标2中，我们将确定骨髓来源的细胞或非骨髓来源的细胞是否在体内介导了内毒素诱导的反应。在目标3中，我们将使用体外流动系统来检测生理性流动下内毒素血症和CLP对血小板活化和与特定黏附分子(如-VWF、P-选择素、纤维蛋白原)黏附的影响。在目标4中，我们将使用体内模型来确定与内毒素和CLP增强的微血管血栓形成有关的血小板和内皮细胞黏附分子。这些目标的完成将拓宽我们对人类脓毒症模型中微血管血栓形成机制的理解。这将有助于确定该疾病微血管血栓形成的新治疗靶点。我们的长期目标是应用从这些研究中获得的知识，以便对脓毒症患者及其相关的微血管改变进行最佳管理。与公共健康相关：败血症是身体对感染的反应，在美国是一个主要的死亡原因。我们的目标是了解这种疾病的严重并发症--微小血管中的血栓--的原因。这些信息将有助于为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.