The Role of Pericytes in the Vascular Dysfunction of Sepsis

项目总结/摘要 脓毒性休克合并多器官功能衰竭是非冠心病重症监护病房的主要死亡原因 这仍然是美国的一个主要健康问题。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着关键作用。 多器官衰竭周细胞维持内皮屏障功能，并代表一个潜在的治疗靶点， 败血症然而，在脓毒症中，控制周细胞活力的过程及其在屏障功能中的作用还没有被阐明。 还没有完全阐明。周细胞是嵌入毛细血管基底膜的特化细胞， 包裹全身微循环的内皮细胞， 微循环稳态的调节剂。然而，周细胞在脓毒症内皮功能障碍中的作用 基本上是未知的。我们的数据表明，周细胞在小鼠肺和肾中被耗尽 盲肠结扎穿孔（CLP）诱导的脓毒症和周细胞耗竭导致微血管 血管渗漏转录因子朋友白血病病毒整合1（Fli-1），是周细胞 通过介导周细胞程序性细胞死亡（通过焦亡）在脓毒症中的功能障碍和生存能力。MiR-145 抑制Fli-1表达，并在周细胞中大量表达;然而，在脓毒症期间，miR-145表达 随着Fli-1表达的增加而降低。这表明，miR-145可能发挥重要作用， 在周细胞活力中起作用，因此是血管通透性的重要调节剂。更清楚 了解miR-145/Fli-1轴如何调节脓毒症中周细胞活力的关键知识缺口 这可能会为败血症带来新的治疗方法。此外，了解 周细胞支持脓毒症中血管屏障的完整性也可能具有治疗意义。一个潜在 周细胞与内皮细胞通信的机制是通过外泌体通过旁分泌信号传导。 有趣的是，我们已经证明了周细胞来源的外泌体而不是成纤维细胞来源的外泌体可以改善细胞的增殖。 在遭受CLP诱导脓毒症小鼠中的存活率和周细胞外泌体含有丰富的miR-145。的 我们研究的长期目标是确定新的治疗策略，以维持内皮屏障功能， 败血症该提案的总体目标是确定败血症中周细胞活力的决定因素， 周细胞维持内皮屏障功能的机制。我们假设周细胞活力 由miR-145/Fli-1轴调节的细胞凋亡是通过周细胞介导的脓毒症结局的关键决定因素。 介导的内皮渗透性的稳定。针对这一假设，有三个具体目标：目标1： 确定miR-145/Fli-1轴调节脓毒症中周细胞功能和活力的机制。 目的2：明确周细胞和周细胞外泌体调节EC功能的机制。目标3：阐明 周细胞来源的外泌体在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.