Endothelial Toll-Like Receptor Signaling and Inflammation

内皮 Toll 样受体信号转导和炎症

• 批准号: 8577458
• 负责人: DEAN Yaw LI
• 金额: $ 37.25万
• 依托单位: UNIVERSITY OF UTAH
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-02-01 至 2018-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8577458
• 关键词: ADP-ribosylation factor 6; Adherens Junction; Affect; Agonist; American; Animal Model; Bacterial Infections; Blood Vessels; Cadherins; Cause of Death; Cell surface; Cells; Cessation of life; Characteristics; Contracts; Cytokine Activation; Cytokine Signaling; Data; Death Rate; Edema; Endocytosis; Endothelial Cells; Endotoxemia; Family; Functional disorder; Future; Genetic Transcription; Guanine Nucleotide Exchange Factors; Guanosine Triphosphate; Guanosine Triphosphate Phosphohydrolases; IL1R1 gene; Immune response; Immune system; Immunosuppression; Infection; Inflammation; Inflammatory; Inflammatory Response; Intercellular Junctions; Interleukin-1; Interleukin-1 Receptors; Knockout Mice; Leukocytes; Ligands; Ligation; Link; Lipopolysaccharides; Liquid substance; Mediating; Methods; Modeling; Molecular; Monomeric GTP-Binding Proteins; Mus; NF-kappa B; Nature; Nuclear; Organ; Organ failure; Pathologic; Pathway interactions; Patients; Pattern; Peptides; Permeability; Pharmaceutical Preparations; Play; Proteins; Puncture procedure; RNA Interference; Receptor Activation; Receptor Signaling; Research; Role; Salmonella infections; Sepsis; Septic Shock; Signal Pathway; Signal Transduction; Supportive care; Survival Rate; TNF gene; Testing; Therapeutic; Toll-like receptors; Vascular Permeabilities; Vascular System; Wild Type Mouse; adapter protein; apoptosis in lymphocytes; cadherin 5; cytokine; effective therapy; in vivo; inhibitor/antagonist; member; mortality; mouse model; novel; pathogen; prevent; public health relevance; receptor; resilience; septic; small molecule; trafficking; vascular inflammation

DESCRIPTION (provided by applicant): Sepsis is a catastrophic systemic inflammatory response to infection. Despite intense study, few therapeutic strategies other than nonspecific supportive care have been developed and death rates remain as high as 60- 70% in cases of septic shock. Approximately 750,000 Americans contract sepsis each year and more than 90% of these cases are due to bacterial infections that trigger inflammation, vascular leak, edema, organ failure, and death. Our long-term challenge is to find an effective therapy for bacterial sepsis. It is known that inflammatory cytokines and pathogen-associated molecular patterns (PAMPs) induce the vascular instability and edema that trigger septic pathophysiology. Our preliminary data suggest that the direct, immediate, and disruptive effects of various cytokines and PAMPs on the vascular barrier are mediated by cognate receptors that signal via a common convergence point, the intracellular GTPase ARF6. This convergence point controls trafficking of cell-cell junction proteins and is distinct from the canonical transcriptional pathwys that activate the immune response (e.g., those activating NF-kappaB). Many bacterial PAMPs signal through toll-like receptors (TLRs), and PAMP/TLR signaling is thought to play a crucial role in sepsis. We hypothesize that inhibiting ARF6 will offer a platform for treating sepsis by enhancing the resilience of the vascular system to PAMP/TLR signaling without further compromising the immune system. We will test this hypothesis by pursuing three aims. In Aim 1, we will identify the upstream molecular components that activate ARF6 in PAMP/TLR signaling. The ARF family of GTPases is activated by guanine nucleotide exchange factors (GEFs) known as ARF-GEFs, and we have shown that during cytokine activation, adapter proteins that link the receptor to the ARF-GEF are required for ARF6 activation. Therefore, we will identify which adapter proteins and ARF-GEFs are required for PAMP/TLR activation of ARF6 and determine whether these proteins are required for the induction of endothelial permeability. In Aim 2, we determine how PAMP/TLR-activated ARF6 functions to increase endothelial permeability. We have shown that in cytokine signaling, activated ARF6 induces endothelial permeability by reducing VE-cadherin levels at the cell surface, thus disrupting the adherens junctions that hold endothelial cells together. In this aim, we will determine whether PAMP/TLR activation of ARF6 likewise disrupts adherens junctions and will identify the direct effectors of ARF6 activation. In Aim 3, we will definitively determine whether the endothelial expression of Arf6 is required for pathologic vascular leak, organ failure, and death in three different mouse models of bacterial sepsis. We will also determine whether blocking ARF6 function by peptide or small molecule inhibitors can reduce vascular leak, organ failure, and mortality rates in these models of sepsis. The successful completion of these aims will elucidate the role ARF6 plays in bacterial sepsis and will dictate whether ARF6 is a promising target for developing drugs that can treat bacterial sepsis.

描述（由申请人提供）：败血症是对感染的灾难性的全身性炎症反应。尽管进行了激烈的研究，但除非特异性支持护理以外的治疗策略很少，并且在败血性休克病例中，死亡率仍然高达60-70％。每年约有75万美国人败血症，其中90％以上是由于细菌感染引发炎症，血管泄漏，水肿，器官衰竭和死亡。我们的长期挑战是为细菌败血症找到有效的疗法。众所周知，炎性细胞因子和病原体相关的分子模式（PAMP）诱导触发败血性病理生理学的血管不稳定性和水肿。我们的初步数据表明，各种细胞因子和大型PAMP对血管屏障的直接，直接和破坏性作用是由通过公共收敛点（细胞内GTPase ARF6）发出信号的同源受体介导的。该收敛点控制了细胞 - 细胞连接蛋白的运输，并且与激活免疫反应的规范转录路径不同（例如，那些激活NF-kappab的人）。许多细菌症状症状通过TOLL样受体（TLR）信号，并且PAMP/TLR信号传导被认为在败血症中起着至关重要的作用。我们假设抑制ARF6将提供一个平台来治疗败血症，通过增强血管系统对pamp/tlr信号的弹性，而无需进一步损害免疫系统。我们将通过追求三个目标来检验这一假设。在AIM 1中，我们将确定激活PAMP/TLR信号中ARF6的上游分子成分。 GTPases的ARF家族被称为ARF-GEFS的鸟嘌呤核苷酸交换因子（GEF）激活，我们已经表明，在细胞因子激活中，将受体与ARF-GEF联系起来的衔接蛋白是ARF6激活所必需的。因此，我们将确定ARF6的PAMP/TLR激活需要哪些衔接蛋白和ARF-GEF，并确定是否需要这些蛋白质才能诱导内皮渗透性。在AIM 2中，我们确定了PAMP/TLR激活的ARF6的功能如何增加内皮渗透性。我们已经表明，在细胞因子信号传导中，激活的ARF6通过降低细胞表面的VE-钙粘蛋白水平来诱导内皮渗透性，从而破坏将内皮细胞固定在一起的粘附连接处。在此目标中，我们将确定ARF6的PAMP/TLR激活是否同样破坏了粘附连接，并将确定ARF6激活的直接效应子。在AIM 3中，我们将明确确定在细菌败血症的三种不同小鼠模型中，病理血管泄漏，器官衰竭和死亡是否需要ARF6的内皮表达。我们还将确定在这些败血症模型中，通过肽或小分子抑制剂阻断ARF6功能是否可以降低血管泄漏，器官衰竭和死亡率。这些目标的成功完成将阐明ARF6在细菌败血症中的作用，并将决定ARF6是否是开发可以治疗细菌败血症的药物的有希望的靶标。