Host Vascular Mechanism for Therapeutic Protection against Select Pathogens

描述(由申请人提供)：一些NIAID A类病原体已经开发出通过破坏内皮屏障以诱导进行性血管渗漏来损害宿主的机制。这会导致肺水肿和呼吸问题、出血热或休克样症状。我们假设，改善血管的韧性和完整性可以保护宿主免受多种感染性病原体的侵袭。在这项研究的R21阶段，我们将使用斑马鱼模型和基于内皮细胞的分析来研究内皮完整性的关键调节因子的作用。使用炭疽致死毒素作为血管渗漏的诱导剂，我们将确定改变宿主血管生成信号如何改善内皮屏障的完整性和血管功能。在这个项目的R33阶段，我们将启动一个大规模的化学库筛选，以识别积极的命中并表征其生物学效应。我们将利用现有的关于3个关键的血管生成因子及其受体的知识，即血管内皮生长因子-A/VEGFR2、血管生成素1/Tie2和ePhinB2/EphB4，来建立可靠的血管完整性模型。这些模型将被用于识别可以改善血管弹性的小分子，作为潜在的宿主靶向治疗。我们建议在R21阶段完成以下具体目标：目的1.通过使用斑马鱼和内皮细胞模型，确定血管配体与炭疽致命毒素(LT)相比在调节通透性方面的独特作用；目的2.通过使用NERCE化学资源，为使用斑马鱼和血管通透性内皮细胞模型进行小规模化合物筛选创造条件。这些目标的实现将通过5个里程碑进行评估，这些里程碑将使本项目进入R33阶段。R33的目标如下：目的3.筛选可改善血管完整性的化合物的化学库，R33，Y3-4；目的4.评估选定阳性化合物的剂量-反应，并确定结构改变是否可以在斑马鱼模型以及血液和淋巴管内皮细胞渗漏分析中改善血管弹性，同时减少不良反应，R33，Y4-5。该项目旨在测试血管保护作为病原体挑战的宿主靶向方法的假说。我们预计R21阶段的积极结果将有助于确定该项目R33阶段的筛选战略。获得当地的化学资源和专门知识将加快这些努力。 公共卫生相关性：病原体在扰乱宿主生理的同时会产生特定的影响。虽然宿主免疫系统的激活是重要的一步，但许多感染性物质通过损伤内皮细胞来改变心血管功能。当这种情况发生时，患者会出现呼吸问题，因为肺部充满了从血管中泄漏出来的液体。内皮细胞排列在人体内的整个血管树上，覆盖了大约100平方米的表面积，为病原体的活动提供了最大的宿主组织。通过了解如何改善血管完整性并确定可以诱导内皮细胞弹性的药物，这些药物可能会对一些与生物防御相关的病原体具有广泛的保护作用。

DESCRIPTION (provided by applicant): A number of NIAID Category A pathogens has developed mechanisms to injure the host through damaging the endothelial barrier to induce progressive vascular leakage. This leads to pulmonary edema and respiratory problems, hemorrhagic fever or shock-like symptoms. We hypothesize that improving vascular resilience and integrity could protect the host against a number of infectious agents. We will investigate the role of key regulators of endothelial integrity using the zebrafish model and in endothelial cell-based assays in the R21 phase of this study. Using anthrax lethal toxin as an inducer of vascular leakage, we will determine how altering host angiogenic signaling could improve endothelial barrier integrity and vascular function. In the R33 phase of this project, we will launch a large-scale chemical library screen, to identify positive hits and characterize their biological effects. We will take advantage of the current knowledge on 3 key angiogenic factors and their receptors, VEGF-A/VEGFR2, Angiopoietin 1/Tie2 and ephrinB2/EphB4, to establish reliable models for vascular integrity. These models will be used to identify small molecules that can improve vascular resilience as potential host-targeted therapies. We propose the following Specific Aims to be completed in the R21 phase: Aim 1. To establish the distinct roles of vascular ligands in comparison with anthrax lethal toxin (LT), in the regulation of permeability using zebrafish and endothelial cell models; Aim 2. To develop conditions for a small scale chemical compound screening using the zebrafish and endothelial cell models of vascular permeability through the use of NERCE chemical resources. Achievement of these Aims will be evaluated through 5 Milestones that would enable progression to the R33 phase of this project. The Aims for the R33 are as follows: Aim 3. To screen chemical libraries for compounds that can improve vascular integrity, R33, Y3-4; Aim 4. To evaluate the dose-response of selected positive compounds and determine whether structural alterations can improve vascular resilience while reducing adverse effects in the zebrafish model, as well as in blood and lymphatic endothelial cell leakage assays, R33, Y4-5. This project is designed to test a hypothesis on vascular protection as a host-targeted approach to pathogen challenge. We envisioned that positive results in the R21 phase will help define the screening strategy in the R33 phase of this project. Access to local chemical resources and expertise will expedite these efforts. PUBLIC HEALTH RELEVANCE: Pathogens induce specific effects while disrupting host physiology. Although activation of the host immune system is an important step, many infectious agents alter cardiovascular function through damage to endothelial cells. When this occurs, the patient suffers from respiratory problems because the lungs are filled with fluid that leaked out o the blood vessels. Endothelial cells line the entire vascular tree in the human body, covering approximately 100 m2 of surface area and providing the largest host tissue for pathogen action. By understanding how to improve vascular integrity and identifying drugs that can induce endothelial resilience, these drugs might be widely protective against a number of biodefense-relevant pathogens.