Endothelial Toll-Like Receptor Signaling and Inflammation

内皮 Toll 样受体信号转导和炎症

基本信息

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
项目类别：
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

项目摘要

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全身炎症反应。尽管进行了大量研究，但除了非特异性支持治疗外，几乎没有制定出治疗策略，脓毒性休克病例的死亡率仍然高达 60-70%。每年大约有 75 万美国人患败血症，其中 90% 以上是由于细菌感染引发炎症、血管渗漏、水肿、器官衰竭和死亡。我们的长期挑战是找到治疗细菌性败血症的有效疗法。众所周知，炎症细胞因子和病原体相关分子模式（PAMP）会诱发血管不稳定和水肿，从而引发脓毒症病理生理学。我们的初步数据表明，各种细胞因子和 PAMP 对血管屏障的直接、即时和破坏性作用是由同源受体介导的，这些受体通过共同的汇聚点（细胞内 GTP 酶 ARF6）发出信号。该汇聚点控制细胞-细胞连接蛋白的运输，并且不同于激活免疫反应的典型转录路径（例如，激活 NF-κB 的转录路径）。许多细菌 PAMP 通过 Toll 样受体 (TLR) 发出信号，PAMP/TLR 信号被认为在脓毒症中发挥着至关重要的作用。我们假设抑制 ARF6 将提供一个平台，通过增强血管系统对 PAMP/TLR 信号传导的恢复能力来治疗脓毒症，而不会进一步损害免疫系统。我们将通过追求三个目标来检验这个假设。在目标 1 中，我们将鉴定在 PAMP/TLR 信号传导中激活 ARF6 的上游分子成分。 GTPase 的 ARF 家族由被称为 ARF-GEF 的鸟嘌呤核苷酸交换因子 (GEF) 激活，我们已经表明，在细胞因子激活过程中，将受体与 ARF-GEF 连接的衔接蛋白是 ARF6 激活所必需的。因此，我们将确定哪些接头蛋白和 ARF-GEF 是 ARF6 的 PAMP/TLR 激活所必需的，并确定这些蛋白是否是诱导内皮通透性所必需的。在目标 2 中，我们确定 PAMP/TLR 激活的 ARF6 如何发挥作用以增加内皮通透性。我们已经证明，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通透性，从而破坏将内皮细胞固定在一起的粘附连接。为此，我们将确定 ARF6 的 PAMP/TLR 激活是否同样会破坏粘附连接，并确定 ARF6 激活的直接效应器。在目标 3 中，我们将明确确定 Arf6 的内皮表达是否是三种不同的细菌性脓毒症小鼠模型中病理性血管渗漏、器官衰竭和死亡所必需的。我们还将确定通过肽或小分子抑制剂阻断 ARF6 功能是否可以减少这些脓毒症模型中的血管渗漏、器官衰竭和死亡率。这些目标的成功完成将阐明 ARF6 在细菌性脓毒症中的作用，并将决定 ARF6 是否是开发治疗细菌性脓毒症药物的有希望的靶点。