Redox-mediated NF-kappaB activation by LPS and IL-1

LPS 和 IL-1 介导的氧化还原介导的 NF-κB 激活

• 批准号: 7071802
• 负责人: JOHN F ENGELHARDT
• 金额: $ 28.81万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-06-01 至 2009-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7071802
• 关键词: Kupffer' s cell; MCF7 cell; NAD(P)H dehydrogenase; athymic mouse; biological signal transduction; cytokine receptors; endotoxins; enzyme activity; free radical oxygen; gene expression; genetically modified animals; immunoprecipitation; interleukin 1; intracellular transport; lipopolysaccharides; molecular pathology; neoplastic cell culture for noncancer research; nuclear factor kappa beta; septicemia; serine threonine protein kinase; toll like receptor; tumor necrosis factor alpha; vesicle /vacuole

DESCRIPTION (provided by applicant): Systemic multi-organ injury is an important component associated with sepsis. Multi-organ dysfunction during sepsis can be caused by a myriad of factors, including endotoxin and systemic production of proinflammatory cytokines, such as TNFalpha and IL-1beta. The liver is a major source of cytokine expression in response to endotoxin and hence plays a critical role in mediating systemic organ injury during sepsis. Hepatic responses to LPS that control proinflammatory cytokine production include a number of receptor-mediated signal transduction pathways, of which NF-kappaB is one of the most important. In this context, NF-kappaB activation in the liver directly controls the induction of TNFalpha in response to LPS and mediates signals that are important to hepatic cell survival. We have determined that IL-1beta and LPS share interesting similarities and differences in their mechanisms of NF-kappaB activation. Both involve redox-sensitive pathways that appear to be controlled by NADPH oxidase activation and converge at the level of the IKB kinase (IKK) complex. LPS and IL-1beta activation of NF-kappaB also utilize two related receptors (TLR4 and IL-1R) that share similar effector complexes. Despite the similar dependence of both these pathways on the intracellular production of reactive oxygen species (ROS), LPS and IL-1beta activate NF-kappaB through distinct subunits of the IKK complex. The manner in which ROS uniquely control NF-kappaB activation by LPS and IL-1beta remains unclear. This project proposes to dissect the redox-mediated events that control these activation pathways using both in vitro and in vivo mouse models. In vitro studies will evaluate LPS and IL-1beta responses in hepatocytes and Kupffer cell line models in order to identify the redox-regulated components of the TLR4 and IL-1R receptor complexes that mediate activation of specific IKK kinases. An important aspect of these mechanisms involves the formation of redox-active endosomes (termed redoxosomes) that appear to cluster ligand-activated receptors into NADPH oxidase active endosomes. We hypothesize that redoxosomes help partition ROS to redox-dependent TLR4 and IL-1R effector domains. Through this process, endosomal compartmentalization of ROS allows only ligand-activated receptor/effector complexes to be influenced by NADPH oxidase. In vivo studies will utilize mouse models of endotoxemia to study redoxosomal functions in vivo and their contribution to hepatic NF-kappaB activation pathways. Findings from these studies may lead to alternative therapeutic approaches targeting the liver by which to abrogate the detrimental effects of systemic cytokine production during sepsis.

描述（由申请人提供）：全身性多器官损伤是与脓毒症相关的一个重要组成部分。脓毒症期间的多器官功能障碍可由多种因素引起，包括内毒素和促炎细胞因子（如 TNFα 和 IL-1β）的全身产生。肝脏是响应内毒素的细胞因子表达的主要来源，因此在脓毒症期间介导全身器官损伤中发挥着关键作用。肝脏对控制促炎细胞因子产生的 LPS 的反应包括许多受体介导的信号转导途径，其中 NF-κB 是最重要的途径之一。在这种情况下，肝脏中 NF-κB 的激活直接控制响应 LPS 的 TNFα 的诱导，并介导对肝细胞存活很重要的信号。我们已经确定 IL-1beta 和 LPS 在 NF-kappaB 激活机制方面具有有趣的相似点和差异。两者都涉及氧化还原敏感途径，这些途径似乎受 NADPH 氧化酶激活控制，并在 IKB 激酶 (IKK) 复合物水平上汇聚。 NF-kappaB 的 LPS 和 IL-1beta 激活也利用两个共享相似效应复合物的相关受体（TLR4 和 IL-1R）。尽管这两条途径对细胞内活性氧 (ROS) 产生的依赖性相似，但 LPS 和 IL-1beta 通过 IKK 复合物的不同亚基激活 NF-κB。 ROS 通过 LPS 和 IL-1beta 独特控制 NF-kappaB 激活的方式仍不清楚。该项目建议使用体外和体内小鼠模型来剖析控制这些激活途径的氧化还原介导的事件。体外研究将评估肝细胞和 Kupffer 细胞系模型中的 LPS 和 IL-1β 反应，以确定介导特定 IKK 激酶激活的 TLR4 和 IL-1R 受体复合物的氧化还原调节成分。这些机制的一个重要方面涉及氧化还原活性内体（称为氧化还原体）的形成，其似乎将配体激活受体聚集成 NADPH 氧化酶活性内体。我们假设氧化还原体有助于将 ROS 划分为氧化还原依赖性 TLR4 和 IL-1R 效应域。通过这个过程，ROS 的内体区室化仅允许配体激活的受体/效应器复合物受到 NADPH 氧化酶的影响。体内研究将利用内毒素血症小鼠模型来研究体内氧化还原体功能及其对肝脏 NF-κB 激活途径的贡献。这些研究的结果可能会导致针对肝脏的替代治疗方法，从而消除脓毒症期间全身细胞因子产生的有害影响。