Role of Eicosanoids In Modulating Endotoxin Induced Live

在败血症相关急性呼吸窘迫综合征的临床环境中，肝功能衰竭的存在显著增加了死亡率，对动物内毒素诱导的肺损伤的研究表明，内毒素对肝脏的影响对于损伤的充分表达同样重要。决定内毒素生理反应的生化事件序列可能是关键转录因子的激活，特别是肺和肝脏中的核因子κ B （NFkappaB）和CCAAT增强子结合蛋白β (C/EBPbeta，又称NF-IL6)，导致促炎细胞因子的产生。我们的初步数据以及其他数据表明，二十烷类化合物是这些内毒素效应的调节剂，并诱导环氧合酶（cox -前列腺素合成的近端酶）也涉及NFkappaB和C/EBPbeta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，我们提出了一系列原位灌注猪模型的研究，其中肺可以在灌注回路中灌注肝脏或不灌注肝脏。我们将：1)确定内毒素血症对肺血管阻力、肺血管通透性、肺含水量、组织、灌注液和支气管肺泡灌洗液（BALF）中类胶质细胞和细胞因子浓度、BALF总细胞计数和差异细胞计数、TNFalpha、COX-1、COX- 2和5-脂氧合酶基因的表达、肺（和肝脏）中核因子κ B （NFkappaB）和C/EBPbeta的激活的影响，无论是否将肝脏纳入灌注回路；2)通过局部控制PGE2输注到肺或肝中的前列腺素浓度，将COX抑制剂靶向递送到肝或肺，或用表达COX基因的构建体转染器官，确定这些相互作用对类二十烷的产生和内毒素反应的影响；3)通过肝部分切除、传递p20膜易位信号融合蛋白或转染p20基因来增加肝或肺中C/EBPbeta抑制剂异构体p20，并确定这些干预措施对内毒素反应的影响；4)通过转染编码NFkappaB激活跨显性抑制剂的基因或给予细胞可渗透的NFkappaB抑制融合蛋白来抑制肝脏或肺部的NFkappaB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.