LIVER-LUNG INTERACTIONS DURING GRAM-NEGATIVE ENDOTOXEMIA

革兰氏阴性杆菌感染时的循环性休克、炎症和器官损伤 脓毒症已被证明是依赖于内源性促炎性 介质，肿瘤坏死因子-α（TNF）和白细胞介素-1（IL-1）， 通过脂多糖（LPS）从宿主细胞诱导。 已经 提示由TNF启动的细胞因子级联反应，由IL-1扩增， 由花生四烯酸代谢物调节，在发病中起主要作用 成人呼吸窘迫综合征（ARDS）多系统 器官衰竭（MSOF）。 然而， 改变的细胞因子动力学和代谢影响ARDS中的器官相互作用 我们对此知之甚少。 该提案的核心前提是， 肝脏，通过调节宿主对急性炎症反应的调节， LPS由TNF、IL-1和花生四烯酸代谢产物介导， 影响脓毒症相关急性肺发病的关键器官 损伤 拟议研究的目的是检验假设 肝脏功能的变化会影响刺激反应， 内源性介质释放和代谢的特征导致 革兰氏阴性菌感染时炎症的肝-肺轴。 我们计划 以表征肝脏释放TNF的时间模式， IL-1在LPS诱导后早期（<3小时），完整细菌， 使用分离的灌注大鼠肝脏（IPRL）的重组（r）TNF 准备. 在非原位无细胞灌注过程中，伴随着 环加氧酶产物，野牡丹素E2，I2，和 血栓素A2和脂氧合酶代谢产物白三烯（LT）B4， 影响细胞因子表达和炎症。 我们 然后将确定持续缺血缺氧的独立影响， 肝损伤，既存肝细胞损伤，巨噬细胞上调 通过BCG引发、先前暴露于LPS和先前暴露于LPS的效应器功能， 在IPRL中对TNF和IL-1动力学的体内环氧合酶抑制。 我们 将进一步确定全身注射无细胞灌注液 从IPRL研究中发现， 具有正常和受损肝脏的完整动物中的炎症 功能 在平行研究中，器官相互作用的机制将被 通过分析肺对个体全身性 注射rTNF和IL-1及脂氧合酶介导的肺损伤 在肝衰竭期间，将通过施用LTB 4来评估。 上清液 来自分离的Kupffer细胞，有和没有共培养的肝细胞， 与IPRL灌注液比较TNF，IL-1， 和花生四烯酸代谢产物的释放及其对功能的影响 培养的肺泡巨噬细胞。 这些研究的结果应该会产生 免疫和炎症反应调节的新信息， 内毒素血症，它们的紊乱与肝功能改变， 与脓毒症引起的急性肺损伤有关。 这将使 肽与非肽信号转导一体化合成 介质与器官系统的相互作用，并提供进一步的见解， 潜在的治疗干预措施，以改善急性呼吸窘迫综合征与多器官功能衰竭。

Circulatory shock, inflammation, and organ damage during gram-negative sepsis have been shown to be dependent of the endogenous pro-inflammatory mediators, tumor necrosis factor-alpha(TNF) and interleukin-1(IL-1), after induction from host cells by lipopolysaccharide (LPS). It has been suggested that a cytokine cascade initiated by TNF, amplified by IL-1 and modulated by arachidonic acid metabolites, plays a major pathogenetic role in the adult respiratory distress syndrome (ARDS) with multiple systems organ failure (MSOF) during sepsis. However, the pathways by which altered cytokine kinetics and metabolism affect organ interactions in ARDS are poorly understood. The central premise of the proposal is that the liver, by modulating host regulation of the acute inflammatory response to LPS mediated by TNF, IL-1 and products of arachidonic acid metabolism, is a pivotal organ influencing the pathogenesis of sepsis-related acute lung injury. The objective of the proposed research is to test the HYPOTHESIS that changes in hepatic performance influencing the stimulus-response characteristics of endogenous mediator release and metabolism result in a liver-lung axis of inflammation during gram-negative infection. We plan to characterize the temporal pattern of release by the liver of TNF and IL-1 early (<3 hours) after induction by LPS, intact bacteria, and recombinant (r) TNF using an isolated, perfused rat liver (IPRL) preparation. During ex situ, cell-free perfusion, accompanying changes in the biosynthesis of the cyclooxygenase products, prostaglandins E2,I2, and thromboxane A2 and the lipoxygenase metabolite leukotriene (LT) B4, which influence cytokine expression and inflammation, will also be defined. We will then determine the independent effects of on-going ischemic-hypoxic liver injury, pre-existing hepatocytic damage, up-regulation of macrophage effector function by BCG priming, previous exposure to LPS, and prior in vivo cyclooxygenase inhibition on TNF and IL-1 kinetics in the IPRL. We will further establish whether systemic injections of cell-free perfusates from the IPRL studies alter lung microvascular permeability and alveolar inflammation in intact animals with both normal and impaired liver function. In parallel studies, mechanisms of organ interactions will be determined by analyzing pulmonary responses to individual systemic injections of rTNF and IL-1, and lipoxygenase mediation of lung injury during liver failure will be assessed by administering LTB4. Supernatants from isolated Kupffer cells with and without co-cultured hepatocytes will be compared with IPRL perfusates regarding the time course of TNF, IL-1, and arachidonic acid metabolite release and their effects on the function of cultured alveolar macrophages. Results from these studies should yield new information on the regulation of immune and inflammatory responses to endotoxemia, their derangement with altered hepatic function, and their relation to sepsis-induced acute lung injury. This will enable a synthesis integrating the signal transduction of peptide and non-peptide mediators with organ system interactions, and provide further insight into potential therapeutic interventions to ameliorate ARDS with MSOF.