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）：系统性多器官损伤是与败血症相关的重要组成部分。败血症期间的多器官功能障碍可能是由多种因素引起的，包括促炎细胞因子（例如TNFALPHA和IL-1BETA）的内毒素和全身产生。肝脏是响应内毒素的细胞因子表达的主要来源，因此在败血症期间介导系统性器官损伤中起着至关重要的作用。控制促炎细胞因子的产生的肝反应包括许多受体介导的信号转导途径，其中NF-kappab是最重要的一种。在这种情况下，肝脏中的NF-kappab激活直接控制TNFALPHA的诱导响应LPS，并介导对肝细胞存活很重要的信号。我们已经确定IL-1BETA和LP在NF-kappab激活机制上具有有趣的相似性及其差异。两者都涉及氧化还原敏感的途径，似乎由NADPH氧化酶激活控制，并在IKB激酶（IKK）复合物的水平上收敛。 NF-kappab的LPS和IL-1BETA激活还利用了具有相似效应子复合物的两个相关受体（TLR4和IL-1R）。尽管这两种途径对活性氧（ROS），LPS和IL-1Beta的细胞内产生的依赖性相似，但通过IKK复合物的不同亚基激活NF-kappab。 LPS和IL-1Beta唯一控制NF-kappab激活NF-kappab的方式尚不清楚。该项目建议剖析使用体外和体内小鼠模型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LP和IL-1BETA反应，以鉴定介导特定IKK激酶激活的TLR4和IL-1R受体复合物的氧化还原调节的成分。这些机制的一个重要方面涉及形成氧化还原活性内体（称为氧化还原体），这些内体（称为氧化还原体）似乎将配体激活的受体聚集到NADPH氧化酶活性内体中。我们假设氧化还原体有助于将ROS分割为依赖氧化还原的TLR4和IL-1R效应子域。通过此过程，ROS的内体隔室化仅允许配体激活的受体/效应子复合物受NADPH氧化酶的影响。体内研究将利用内毒素血症的小鼠模型研究体内的氧化氧合功能及其对肝NF-kappab激活途径的贡献。这些研究的结果可能导致针对肝脏的替代治疗方法，以消除败血症期间全身细胞因子的有害作用。