Role of Eicosanoids In Modulating Endotoxin Induced Live

在脓毒症相关性ARDS的临床环境中，肝功能衰竭的存在显著增加了死亡率，而对动物内毒素所致肺损伤的研究表明，对肝脏的影响对于充分表达损伤具有重要意义。决定对内毒素的生理反应的一系列生化事件可能是关键转录因子的激活，特别是核因子kappaB(NFkappaB)和CCAAT增强子结合蛋白β(C/EBPbeta，又名)。肺和肝脏中的核因子-IL-6)，导致促炎细胞因子的产生。我们的初步数据以及其他人的数据表明二十烷类化合物是这些内毒素效应的调节剂，环氧合酶(COX-前列腺素合成的近端酶)的诱导也涉及NFkappaB和C/EBPβ的激活。为了阐明内毒素反应中与肝-肺相互作用相关的生理、生化、分子和病理生理事件之间的关系，我们在猪的原位灌流模型中进行了一系列研究，在该模型中，肺可以在灌流回路中有或没有肝脏。我们将：1)测定内毒素血症对肺血管阻力、肺血管通透性、肺水含量、组织、灌流液和支气管肺泡灌洗液(BALF)中二十烷类和细胞因子浓度、BALF细胞总数和分类计数、TNFα、COX-1、COX-2和5-脂氧合酶基因表达的影响，以及在有或没有肝脏参与灌流循环的情况下肺(和肝脏)核因子kappaB(NFkappaB)和C/EBPbeta的激活；2)通过局部可控地将前列腺素E_2注入肺或肝脏，将COX抑制剂靶向输送至肝脏或肺，或将表达COX基因的载体导入器官(S)，并确定这些相互作用对类前列腺素生成和内毒素反应的影响；3)通过肝脏部分切除，p20膜转位信号融合蛋白或p20基因转染肝或肺，增加肝脏或肺中C/EBPβ的抑制物异构体p20，并确定这些干预对内毒素反应的影响；4)通过将编码NFkappaB激活的跨显性抑制因子的基因导入肝脏或肺中的任一个器官或给予细胞可穿透的NFkappaB抑制融合蛋白来抑制NFkappaB在肝脏或肺中的激活，并确定对内毒素反应的影响。这些研究将把病理生理学与内毒素反应的发病机制联系起来，为确定新的潜在治疗干预措施提供基础。

In the clinical setting of sepsis related ARDS, the presence of liver failure markedly increases mortality and studies of endotoxin induced lung injury in animals implicate effects on the liver as important for the full expression of the injury. The sequence of biochemical events that dictates the physiologic response to endotoxin may be activation of critical transcription factors, especially nuclear factor kappa B (NFkappaB) and CCAAT enhancer binding protein beta (C/EBPbeta, a.k.a. NF-IL6) in both the lungs and the liver, leading to generation of pro-inflammatory cytokines. Our preliminary data as well as data of others implicate eicosanoids as modulators of these endotoxin effects and induction of the cyclooxygenase (COX-the proximal enzyme in prostanoid synthesis) also involves NFkappaB and C/EBPbeta activation. To elucidate relationships among the physiologic, biochemical, molecular and pathophysiologic events related to liver-lung interactions in the endotoxin response we propose a series of studies in an in situ perfused swine model in which the lungs can be perfused with or without the liver in the perfusion circuit. We will: 1) determine effects of endotoxemia on pulmonary vascular resistance, lung vascular permeability, lung water content, tissue, perfusate and bronchoalveolar lavage fluid (BALF) concentrations of eicosanoids and cytokines, BALF total and differential cell counts, expression of TNFalpha, COX-1, COX- 2 and 5-lipoxygenase genes, activation of nuclear factor kappa B (NFkappaB) and C/EBPbeta in the lungs (and liver) with and without inclusion of the liver in the perfusion circuit; 2) manipulate concentrations of prostanoids in lung or liver by local controlled infusion of PGE2 into either organ, targeted delivery of a COX inhibitor to liver or lungs or transfecting the organ(s) with a construct expressing the COX gene and determine effects of these interactions on generation of eicosanoids and on endotoxin responses; 3) increase p20, the inhibitor isoform of C/EBPbeta, in the liver or the lungs by partial hepatic resection, delivery of a p20 membrane translocation signal fusion protein or transfection of the liver or lungs with a p20 gene and determine effects of these interventions on the endotoxin response; 4) inhibit activation of NFkappaB in liver or lungs by transfection of either organ with a gene encoding a transdominant inhibitor of NFkappaB activation or administration of a cell-permeable NFkappaB inhibitory fusion protein and determine effects on the endotoxin response. These studies will link pathophysiology to pathogenesis of the endotoxin response, providing a basis for identifying new potentially therapeutic interventions.