LIVER-LUNG INTERACTIONS DURING GRAM-NEGATIVE ENDOTOXEMIA

革兰氏阴性患者的循环系统休克、炎症和器官损害 脓毒症已被证明依赖于内源性促炎因子 中介物，肿瘤坏死因子-α和白细胞介素1，在 内毒素(LPS)诱导宿主细胞分化。一直以来 提示由肿瘤坏死因子启动的细胞因子级联反应，由IL-1和 受花生四烯酸代谢产物调节，起主要致病作用 成人呼吸窘迫综合征(ARDS)合并多系统 败血症期间的器官衰竭(MSOF)。然而，它所经过的路径 细胞因子动力学和代谢改变影响ARDS的器官相互作用 人们对此了解甚少。该提案的中心前提是 肝脏，通过调节宿主对急性炎症反应的调节 由肿瘤坏死因子、白介素1和花生四烯酸代谢产物介导的内毒素是 影响脓毒症相关急性肺发病的关键器官 受伤。拟议研究的目的是检验这一假说。 肝脏功能的改变会影响刺激反应 内源性介质释放和代谢的特点导致 革兰氏阴性菌感染时炎症的肝-肺轴。我们计划 描述肝脏释放肿瘤坏死因子和肿瘤坏死因子的时间模式。 IL-1在内毒素诱导后早期(&lt；3小时)、完整细菌和 利用分离、灌流的大鼠肝脏(IPRL)重组(R)肿瘤坏死因子 准备工作。在非原位、无细胞灌流过程中，伴随着 环氧合酶产物前列腺素E_2、I_2和 血栓素A2和脂氧合酶代谢产物白三烯(LT)B4，它 影响细胞因子表达和炎症，也将被定义。我们 将确定持续的缺血-缺氧的独立影响 肝损伤、原有肝细胞损伤、巨噬细胞上调 卡介苗启动的效应器功能，以前接触过的内毒素，以及之前 环氧合酶对IPRL中肿瘤坏死因子和白介素1动力学的抑制作用。我们 将进一步确定全身注射的无细胞灌流液 来自IPRL的研究改变了肺微血管通透性和肺泡 肝脏正常和受损的完整动物的炎症反应 功能。在平行研究中，器官相互作用的机制将是 通过分析个体全身的肺反应来确定 注射rTNF和IL-1与脂氧合酶介导的肺损伤 在肝功能衰竭期间将通过给予LTB4进行评估。上清液 从分离的Kupffer细胞中分离出来的肝细胞将 与IPRL灌流液在肿瘤坏死因子、白介素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 关于免疫和炎症反应调节的新信息 内毒素血症及其与肝功能异常的关系 与脓毒症所致急性肺损伤的关系。这将使 整合多肽和非肽信号转导的合成 与器官系统相互作用的介体，并提供对 改善合并多器官功能衰竭的ARDS的潜在治疗干预。

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.