Regulation of Hepatic Ischemia/Reperfusion Injury

描述（由申请人提供）： 肝脏缺血/再灌注损伤是创伤外科、肝移植和肝切除手术以及失血性休克的主要并发症。这项建议的长期目标是确定肝I/R导致炎症性肝损伤的诱导和传播的分子和细胞机制。目的1将解决的假设，即NF-κ B激活发生在枯否细胞在缺血期间，这是导致炎症级联反应的初始事件。这一点，沿着匡威的概念，即再灌注后肝细胞中NF-κ B的活化可能是促进肝脏恢复和修复的保护机制，将用原代肝细胞分离物以及我们的整个动物模型进行研究，使用含有NF-κ B抑制蛋白IkappaB α突变形式的新型融合蛋白构建体。目的2将解决的假设，即核受体和转录因子，PPARalpha和PPARgamma，是中央调控因子的炎症和氧化剂诱导的肝细胞损伤的启动，分别。我们提供的证据表明，PPARgamma在缺血期间失活，这可能有助于NF-κ B的反式激活。我们将确定PPARgamma通过缺血下调的机制，以及PPARgamma的激动性调节是否可以抑制I/R损伤。我们的数据表明，PPARa调节诱导型一氧化氮合酶（iNOS）的肝细胞表达。我们将确定再灌注后PPARalpha被激活的机制以及它控制iNOS基因表达的方式。目的3阐明IL-12在I/R后肝脏中的作用机制。我们的实验室发现，IL-12在肝缺血期间在肝脏中产生，并且IL-12是产生TNF α和促进嗜中性粒细胞依赖性肝损伤所必需的。我们将确定IL-12的细胞来源和靶点以及IL-12在肝细胞中发挥作用的信号传导机制。目的4将解决这一假设，即肝脏募集CD 4 T细胞在早期再灌注是必要的中性粒细胞和肝细胞损伤的后续招聘。我们将确定再灌注后CD 4 T细胞被招募到肝脏中的机制，以及这些细胞如何促进中性粒细胞的招募。这些研究将极大地推进我们对肝I/R损伤的病理生理学的认识，并可能确定几个潜在的治疗靶点。

DESCRIPTION (provided by applicant): Hepatic ischemia/reperfusion (I/R) injury is a major complication of trauma surgery, liver transplantation and resectional surgery, and hemorrhagic shock. The long-term goal of this proposal is to determine the molecular and cellular mechanisms by which hepatic I/R leads to induction and propagation of inflammatory liver injury. Aim 1 will address the hypothesis that NF-kB activation occurs in Kupffer cells during the ischemic period and that this is the initial event leading to the inflammatory cascade. This, along with the converse notion that NF-kappaB activation in hepatocytes after reperfusion may be a protective mechanism that promotes liver recovery and repair, will be studied with primary liver cell isolates as well as our whole animal model using novel fusion protein constructs containing mutant forms of the NF-kappaB inhibitory protein, IkappaBalpha. Aim 2 will address the hypothesis that the nuclear receptors and transcription factors, PPARalpha and PPARgamma, are central regulatory factors for the initiation of inflammation and regulation of oxidant-induced hepatocyte injury, respectively. We provide evidence that PPARgamma is deactivated during the ischemic period and that this may facilitate transactivation of NF-kappaB. We will determine the mechanisms by which PPARgamma is down-regulated by ischemia and whether agonistic modulation of PPARgamma can suppress I/R injury. Our data suggest that PPARa modulates hepatocyte expression of inducible nitric oxide synthase (iNOS). We will determine the mechanisms by which PPARalpha is activated after reperfusion and the manner in which it controls iNOS gene expression. Aim 3 will delineate the mechanism of action of IL-12 in the liver after I/R. Our laboratory discovered that IL-12 is Produced in the liver during hepatic ischemia and that IL-12 is required for the production of TNF alpha and the promotion of neutrophil-dependent liver injury. We will determine the cellular source(s) and target(s) of IL-12 as well as the signaling mechanism by which IL-12 functions in liver cells. Aim 4 will address the hypothesis that liver recruitment of CD4 T cells during early reperfusion is prerequisite for the subsequent recruitment of neutrophils and hepatocellular injury. We will determine the mechanisms by which CD4 T cells are recruited into the liver after reperfusion and how these cells promote the recruitment of neutrophils. These studies will greatly advance our knowledge of the pathophysiology of hepatic I/R injury and may identify several potential therapeutic targets.