DISTAL EVENTS IN THE HEPATOTOXICITY OF ENDOTOXIN

描述（改编自研究者摘要）：败血症伴 结果暴露于革兰氏阴性细菌脂多糖（LPS）是一种 与高死亡率相关的主要临床问题和无数的 病理生理学改变，包括肝功能衰竭。 体内，LPS 触发一系列事件，涉及细胞和可溶性介质， 炎症，最终导致肝功能障碍和肝脏完整性的丧失。 肝实质细胞 枯否细胞、中性粒细胞和血小板是 在对LPS诱导的肿瘤发生至关重要的细胞介质中， 肝损伤 研究人员最近对老鼠的研究表明， 在体内LPS暴露期间活化的凝血酶对于 发病机制 此外，它的关键作用与其以下能力无关： 在脉管系统中形成阻塞性纤维蛋白凝块，这引起了人们对 其重要作用可能通过受体介导 与细胞的相互作用。 凝血酶似乎在级联反应的后期起作用， 导致肝功能障碍的炎症事件，即， 至实质细胞损伤发生的时间。 了解此类“远端 事件”可能有助于开发有效的临床 干预 本提案的总体目标是了解 凝血酶参与大鼠肝损伤。 在目标1中，体内研究 在离体肝脏中进行，以确定时间关系 凝血酶的关键作用与明显肝损伤的发生之间的关系。 目标2中的实验将检验凝血酶通过以下方式起作用的假设： 增加肝实质细胞（HC）对损伤的敏感性 在LPS暴露期间。 研究将使用分离的、灌注的 肝脏或HC培养，以确定凝血酶暴露是否增加 HC对潜在伤害性损伤的易感性。 的机制 凝血酶对HC的作用将得到解决。 假设凝血酶 通过刺激重要的炎症细胞参与肝损伤， 将在目标3中处理释放有毒产品的问题。 这将是 部分是通过评估凝血酶对人体造成损伤的可能性来实现的。 灌注的肝脏从大鼠已耗尽的中性粒细胞，血小板， 或枯否细胞，然后用LPS处理。 实验采用 HC与中性粒细胞、血小板或枯否细胞的共培养物将 确定凝血酶是否引起受体介导的细胞毒性释放 因子从关键的炎症细胞和/或通过蛋白水解作用 生物活化可溶性炎症介质（目的4）。 从这些 研究将揭示凝血酶和细胞之间的关键相互作用， 它们在LPS暴露期间导致肝损伤的机制。 的 这些研究的长期目标是了解 炎症反应，这将导致有效的干预措施， 在降低因革兰氏阴性杆菌导致的器官衰竭患者的死亡率方面， 细菌性败血症

DESCRIPTION (Adapted from the Investigator's Abstract): Septicemia with resultant exposure to gram-negative bacterial lipopolysaccharide (LPS) is a major clinical problem associated with high mortality and a myriad of pathophysiological alterations, including liver failure. In vivo, LPS triggers a cascade of events involving cellular and soluble mediators of inflammation that culminates in liver dysfunction and loss of integrity of hepatic parenchymal cells. Kupffer cells, neutrophils and platelets are among the cellular mediators critical to the development of LPS-induced liver injury. The investigator's recent studies in rats indicate that thrombin activated during LPS exposure in vivo is essential to the pathogenesis. Moreover, its critical role is independent of its ability to form obstructive fibrin clots in the vasculature, which raises interest in the possibility that its important action occurs through receptor-mediated interaction with cells. Thrombin appears to act late in the cascade of inflammatory events that leads to hepatic dysfunction, that is, close in time to the genesis of parenchymal cell injury. Knowledge of such "distal events" is likely to be useful in developing effective clinical intervention. The overall goal of this proposal is to understand the mechanisms by which thrombin participates in liver injury in the rat. In Aim 1, studies in vivo and in isolated livers will be performed to define the temporal relationship between thrombin's critical action(s) and the onset of overt liver injury. Experiments in Aim 2 will test the hypothesis that thrombin acts by increasing the sensitivity of hepatic parenchymal cells (HCs) to injury during LPS exposure. Studies will be performed using isolated, perfused livers or HCs in culture to determine if thrombin exposure increases susceptibility of HCs to potentially injurious insults. Mechanisms by which thrombin acts on HCs will be addressed. The hypothesis that thrombin participates in hepatic injury by stimulating critical inflammatory cells to release toxic products will be addressed in Aim 3. This will be accomplished in part by evaluating thrombin's potential to cause injury to perfused livers from rats which had been depleted of neutrophils, platelets or Kupffer cells and then treated with LPS. Experiments employing cocultures of HCs with neutrophils, platelets or Kupffer cells will determine if thrombin causes the receptor-mediated release of a cytotoxic factor from a critical inflammatory cell and/or acts by proteolytically bioactivating a soluble inflammatory mediator (Aim 4). Results from these studies will reveal critical interactions between thrombin and cells and mechanisms by which they result in liver injury during LPS exposure. The long-term goal of these studies is to develop an understanding of inflammatory responses that will result in interventions that are effective in reducing mortality in people with organ failure from gram-negative bacterial sepsis.