Pulmonary Vascular Regeneration via Venous Endothelial Progenitors

项目摘要 呼吸道病毒感染是发展为急性呼吸窘迫的主要危险因素。 综合症。此外，严重的流感损伤会导致无效的修复和持续的肺损失。 功能。由于强烈的炎症，肺内皮细胞，特别是微血管系统受到损害。 病毒感染的应答，但重症后肺内皮细胞再生的机制 尽管血管系统在气体交换中起着核心作用，但流感的损伤还没有完全阐明。这 该提案旨在回答有关肺血管再生的基本问题，即肺血管再生的起源 血管祖细胞(S)和流感损伤反应中内皮细胞修复的驱动机制。我们最近 证实了Coup-TFII，一种富含于增殖内皮细胞的血管特异性转录因子，是 对于肺的再生来说是必要的。静脉内皮细胞日益被认为是血管祖细胞 斑马鱼和小鼠不同器官内皮细胞再生的种群，提示肺静脉 /小静脉可能同样含有强大的祖细胞。在我自己的初步数据中，我观察到静脉 内皮细胞克隆具有高度的增殖性，可以延伸到微血管系统。本提案的目标1将 利用克隆谱系示踪和原位移植技术确定静脉内皮细胞 在肺再生过程中具有强大的祖细胞和增殖潜能。这项提案的第二个重点是 是阐明内皮细胞增殖所需的机制和相互作用。与.一起 静脉标志物的表达，增殖内皮细胞分泌C-C基序趋化因子配体2，a 趋化因子参与介导损伤时的炎症反应。CCL2-CCR2信号轴 通过募集单核细胞源性炎性细胞促进小鼠炎性血管生成 巨噬细胞，表明在组织修复过程中内皮细胞特异性释放CCL2的作用。因此，目标2 将使用有条件的、暂时删除内皮细胞中的CCL2和氯膦酸盐-脂质体介导的方法 耗尽巨噬细胞以研究内皮源性CCL2的缺失是否影响内皮细胞的增殖和 随之而来的血管新生修复。这项提议将解决一个中心假设，即一个肺内皮细胞 存在于预先存在的静脉内皮细胞中的祖细胞群体分泌CCL2以招募间质 单核细胞来提供血管生成的利基。该项目的完成将验证静脉内皮细胞作为一种 对肺再生的重要贡献，也将有助于识别特定的旁分泌/ 能够精确调节和保存有益的免疫反应的免疫途径。

Project Summary Respiratory viral infections represent a major risk factor for the development of acute respiratory distress syndrome. Moreover, severe influenza injury can result in ineffective repair and persistent loss of pulmonary function. The lung endothelium, especially the microvasculature, is damaged due to the robust inflammatory response from viral infections, but the mechanisms of pulmonary endothelium regeneration after severe influenza injury are not completely elucidated despite the vasculature’s central importance in gas exchange. This proposal aims to answer fundamental questions about pulmonary vascular regeneration regarding the origin of vascular progenitor(s) and the mechanisms driving endothelial repair in response to influenza injury. We recently demonstrated that COUP-TFII, a vein-specifying transcription factor enriched in proliferating endothelial cells, is necessary for lung regeneration. The venous endothelium is increasingly recognized as a vascular progenitor population for endothelial regeneration in various organs in zebrafish and mice, suggesting that pulmonary veins / venules may similarly harbor potent progenitor cells. In my own preliminary data, I observed that venous endothelial cell clones are highly proliferative and can span into the microvasculature. Aim 1 of this proposal will utilize clonal lineage tracing and orthotopic transplantation techniques to determine if the venous endothelium harbors potent progenitor and proliferative potential during lung regeneration. The second focus of this proposal is to elucidate the mechanisms and interactions that are required for endothelial proliferation. Along with expression of venous markers, proliferating endothelial cells secrete C-C Motif Chemokine Ligand 2 (CCL2), a chemokine involved in mediating the inflammatory response during injury. The CCL2-CCR2 signaling axis promotes inflammatory angiogenesis in mice through recruitment of monocyte derived inflammatory macrophages, indicating a role for endothelial-specific release of CCL2 during tissue repair. Therefore, Aim 2 will employ conditional, temporal deletion of CCL2 in endothelial cells and clodronate-liposome mediated depletion of macrophages to investigate if loss of endothelial-derived CCL2 impacts endothelial proliferation and consequent angiogenic repair. This proposal will address the central hypothesis that a pulmonary endothelial progenitor population present in the preexisting venous endothelium secretes CCL2 to recruit interstitial monocytes to provide an angiogenic niche. Completion of this project will validate the venous endothelium as an important contributor to pulmonary regeneration and will also facilitate identification of specific paracrine / immune pathways that could allow for precise regulation and preservation of the beneficial immune response.