The Protein C Pathway in Mitigation of Radiation-Induced Endothelial and Vascular Dysfunction

项目摘要/摘要 核事故或核袭击的威胁使制定医学对策变得至关重要。临床前 研究表明血管功能障碍与慢性器官辐射损伤之间存在联系，但几乎没有。 了解潜在的保护机制。因此，要确定缓解的目标，研究是 需要阐明辐射引起的血管功能障碍和血管保护的途径。 辐射诱导的内皮功能障碍与蛋白C途径中的有害变化有关。 内皮细胞表面血栓调节蛋白(ThBD)的缺失导致活化蛋白C(APC)水平降低 血浆中的一种重要成分，具有抗凝和消炎的特性，可增强 内皮细胞存活。我们先前已经证明，重组APC是一种有效的急性缓解药物 在小鼠模型中全身照射后24小时给予辐射损伤。我们将进一步探索 蛋白C途径在辐射引起的血管功能障碍中起中心作用的范式 APC是一种有效的缓解多器官急性和晚期放射毒性的药物。在体外研究中 野生型和重组人内皮细胞辐射培养的APC将决定 APC的结构特征及其内皮APC受体在辐射后增强中的作用 内皮功能。对野生型小鼠、Thbd缺陷小鼠和增强型 小肠、心脏和大脑中的血管对辐射的反应--这三个器官系统在 内源性APC水平将决定Thbd-蛋白C通路在急性期和晚期的作用 对辐射反应迟缓。以小鼠内皮细胞为研究对象的基因表达谱 确定辐射诱导的翻译组的变化以及APC对这些基因表达的影响 配置文件。来自同一只小鼠的血浆样本将被用来识别指示辐射的代谢物特征 损伤并反映了APC如何改变宿主反应。这样的代谢数据可能会导致新的生物标志物，如 并启发我们了解辐射和放射减量如何影响各种代谢途径。在……里面 综上所述，这些研究将为Thbd-Protein C途径的机制提供新的见解 其组成成分，即APC及其内皮受体，可实现内皮放射减影。血管内皮细胞的研究 基因表达谱将提供对哪些内皮调节系统发生显著变化的洞察 被辐射并被APC营救。该项目的基本知识将提供所需的关键数据 应对放射性血管内损伤的对策的深思熟虑的发展。

PROJECT SUMMARY/ABSTRACT The threat of nuclear accidents or attacks makes it critical to develop medical countermeasures. Preclinical studies have shown a relation between vascular dysfunction and chronic organ radiation damage, but little is known about the underlying protective mechanisms. Hence, to identify targets for mitigation, research is needed to elucidate pathways involved in radiation-induced vascular dysfunction and vascular protection. Radiation-induced endothelial dysfunction is associated with detrimental alterations in the protein C pathway. Loss of endothelial surface thrombomodulin (Thbd) leads to reduced levels of activated protein C (APC), a critical component in plasma that has anticoagulant and anti-inflammatory properties and that enhances endothelial cell survival. We have previously shown that recombinant APC is an effective mitigator of acute radiation injury when administered 24 h after total-body irradiation in a mouse model. We will further explore the paradigm that the protein C pathway plays a central role in radiation-induced vascular dysfunction and that APC is an effective mitigator of both acute and late radiation toxicity in multiple organs. In vitro studies with wild-type and recombinant APC using irradiated human endothelial cells in culture will determine which structural features of APC and which endothelial APC receptors are critical for enhancing post-radiation endothelial function. In vivo studies with wild-type mice, Thbd-deficient mice, and mice with enhanced vascular responses to radiation in the small intestine, heart and brain—three organ systems critical in the endogenous levels of APC will determine the role of the Thbd–protein C pathway in both the acute and the late delayed response to radiation. Gene expression profiling focused on endothelial cells extracted from mice will identify radiation-induced changes in the translatome and the effects of APC on those gene expression profiles. Plasma samples from the same mice will be used to identify metabolite profiles indicative of radiation injury and reflective of how APC alters host responses. Such metabolic data may lead to novel biomarkers, as well as enlightening us about how radiation and radiomitigation affect various metabolic pathways. In summary, these studies will provide novel insights into mechanisms by which the Thbd–protein C pathway components, i.e., APC and its endothelial receptors, achieve endothelial radiomitigation. Studies of endothelial gene expression profiles will provide insights into which endothelial regulatory systems are significantly altered by radiation and rescued by APC. Basic knowledge from this project will provide key data required for thoughtful development of countermeasures addressing radiation-induced endovascular injury.