The Role of Pericytes in the Vascular Dysfunction of Sepsis

项目摘要/摘要 感染性休克合并多器官衰竭是非冠脉重症监护病房的主要死亡原因 并且仍然是美国的一个主要健康问题。血管内皮细胞(EC)功能障碍，表现为 血管通透性是感染性休克的重要标志，在感染性休克的发病机制中起关键作用。 多器官衰竭。周细胞维持内皮屏障功能，是一种潜在的治疗靶点 败血症。然而，控制周细胞活性的过程及其在脓毒症屏障功能中的作用还没有。 但还没有完全阐明。周细胞是嵌入在毛细血管基底膜中的特化细胞， 包裹全身微循环的内皮细胞，被认为是重要的 微循环动态平衡调节剂。然而，周细胞在脓毒症内皮功能障碍中的作用 在很大程度上是未知的。我们的数据表明，小鼠肺和肾脏中的周细胞被耗尽。 盲肠结扎和穿孔(CLP)诱导的脓毒症和周细胞耗竭过程中的微血管形成 血管渗漏。转录因子Friend白血病病毒整合1(Fli-1)对周细胞至关重要 脓毒症中通过下垂介导周细胞程序性细胞死亡的功能障碍和生存能力。MIR-145 抑制Fli-1的表达，并在周细胞中大量表达；然而，在脓毒症期间，miR-145的表达 随着Fli-1表达的增加而减少。这表明miR-145可能在 在周细胞活性中起重要作用，因此是血管通透性的重要调节因子。一个更清晰的 在关键知识缺口中了解miR-145/Fli-1轴如何调节脓毒症中周细胞的活性 这可能会导致脓毒症的新治疗方法。此外，了解通过哪些机制 在脓毒症中，周细胞支持血管屏障的完整性也可能具有治疗意义。一种潜力 周细胞与内皮细胞通讯的机制是通过外周小体的旁分泌信号。 有趣的是，我们已经证明了周细胞来源的外切体而不是成纤维细胞来源的外切体可以改善 CLP诱导的脓毒症小鼠存活，周细胞外体含有丰富的miR-145。这个 我们研究的长期目标是寻找新的治疗策略来维持血管内皮细胞屏障的功能 败血症。这项建议的总体目标是确定脓毒症中周细胞活性的决定因素和 周细胞维持内皮细胞屏障功能的机制。我们假设周细胞的生存能力 受miR-145/Fli-1轴调控是败血症预后的关键决定因素，通过周细胞- 介导内皮细胞通透性的稳定。针对这一假设有三个具体目标：目标1： 确定脓毒症时miR-145/Fli-1轴调节周细胞功能和活性的机制。 目的2：明确周细胞和周细胞外切体调节EC功能的机制。目标3：澄清 周细胞来源的外切体在CLP诱导的脓毒症中的治疗潜力。

PROJECT SUMMARY/ABSTRACT Septic shock with multiple organ failure is the leading cause of death in non-coronary intensive care units and remains a major health problem in the US. Endothelial cell (EC) dysfunction, manifested by increases in vascular permeability, is an important hallmark of septic shock and plays a critical role in the pathogenesis of multi-organ failure. Pericytes maintain endothelial barrier function and represent a potential therapeutic target in sepsis. However, the processes that govern pericyte viability and their role in barrier function in sepsis have not yet been fully elucidated. Pericytes are specialized cells embedded in the capillary basement membrane that wrap around endothelial cells of the microcirculation throughout the body and are thought to be important regulators of microcirculatory homeostasis. However, the role of pericytes in the endothelial dysfunction of sepsis is largely unknown. Our data demonstrated that pericytes are depleted in the mouse lung and kidney microvasculature during cecal ligation and puncture (CLP)-induced sepsis and pericyte depletion results in vascular leakage. The transcription factor friend leukemia virus integration 1 (Fli-1), is critical to pericyte dysfunction and viability in sepsis by mediating pericyte programmed cell death through pyroptosis. MiR-145 inhibits Fli-1 expression and is abundantly expressed in pericytes; however, during sepsis, miR-145 expression decreases with a concomitant increase in Fli-1 expression. This suggests that miR-145 may play an important role in pericyte viability and, therefore, be an important regulator of vascular permeability. A clearer understanding of how the miR-145/Fli-1 axis regulates pericyte viability in sepsis in a critical gap in knowledge that may lead to novel therapeutic approaches for sepsis. Furthermore, understanding the mechanisms by which pericytes support the vascular barrier integrity in sepsis may also have therapeutic implications. One potential mechanism whereby pericytes communicate with endothelial cells is through paracrine signaling via exosomes. Intriguingly, we have demonstrated that pericyte-derived exosomes but not fibroblast-derived exosomes improve survival in mice subjected to CLP-induced sepsis and that pericyte exosomes contain abundant miR-145. The long-term goal of our research is to identify novel treatment strategies to maintain endothelial barrier function in sepsis. The overall objective for this proposal is to identify the determinants of pericyte viability in sepsis and the mechanisms by which pericytes maintain endothelial barrier function. We hypothesize that pericyte viability regulated by the miR-145/Fli-1 axis is a critical determinant of sepsis outcomes through pericyte- mediated stabilization of endothelial permeability. Three specific aims address this hypothesis: Aim 1: Determine the mechanisms by which the miR-145/Fli-1 axis regulates pericyte function and viability in sepsis. Aim 2: Define the mechanisms by which pericytes and pericyte exosomes regulate EC function. Aim 3: Elucidate the therapeutic potential of pericyte-derived exosomes in CLP-induced sepsis.