Endothelial Toll-Like Receptor Signaling and Inflammation

内皮 Toll 样受体信号转导和炎症

• 批准号: 8794450
• 负责人: DEAN Yaw LI
• 金额: $ 36.69万
• 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/8794450
• 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; Health; 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; 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)：败血症是对感染的一种灾难性的全身炎症反应。尽管进行了密集的研究，但除了非特异性支持性护理外，很少有治疗策略被开发出来，感染性休克病例的死亡率仍高达60%-70%。每年约有75万美国人患上败血症，其中90%以上是由细菌感染引起的，这些感染会引发炎症、血管渗漏、水肿、器官衰竭和死亡。我们的长期挑战是找到一种有效的治疗细菌性败血症的方法。已知炎性细胞因子和病原体相关分子模式(PAMPs)可导致血管不稳定和水肿，从而触发败血症的病理生理过程。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、即时和破坏性影响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传递信号。这个汇聚点控制着细胞-细胞连接蛋白的运输，不同于激活免疫反应的规范转录途径(例如，那些激活核因子-kappaB的途径)。许多细菌PAMP通过Toll样受体(TLRs)传递信号，PAMP/TLR信号被认为在脓毒症中起关键作用。我们假设，抑制ARF6将通过增强血管系统对PAMP/TLR信号的弹性而不进一步损害免疫系统，为治疗脓毒症提供一个平台。我们将通过追求三个目标来检验这一假设。在目标1中，我们将确定在PAMP/TLR信号中激活ARF6的上游分子成分。ARF家族的GTP酶是由鸟嘌呤核苷酸交换因子(GEF)激活的，我们已经证明在细胞因子激活过程中，ARF6的激活需要连接受体和ARF-GEF的适配蛋白。因此，我们将确定哪些接头蛋白和ARF-GEF是激活ARF6的PAMP/TLR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，我们确定了PAMP/TLR激活的ARF6如何作用于增加内皮通透性。我们已经证明，在细胞因子信号转导中，激活的ARF6通过降低细胞表面的VE-钙粘附素水平来诱导内皮细胞通透性，从而破坏将内皮细胞结合在一起的黏附连接。为此，我们将确定ARF6的PAMP/TLR激活是否同样破坏了粘连连接，并将确定ARF6激活的直接影响因素。在目标3中，我们将明确确定在三种不同的细菌性脓毒症小鼠模型中，血管内皮细胞Arf6的表达是否与病理性血管渗漏、器官衰竭和死亡有关。我们还将确定在这些脓毒症模型中，用多肽或小分子抑制剂阻断ARF6功能是否可以减少血管渗漏、器官衰竭和死亡率。这些目标的成功完成将阐明ARF6在细菌性脓毒症中所起的作用，并将决定ARF6是否是开发治疗细菌性败血症药物的有前途的靶点。