A Critical Role for the Microvasculature in Airway Transplantation

描述（由申请人提供）：微血管损失可能是所有实体器官移植慢性排斥反应的一个未被认识到的根本原因。目前还没有关于移植或同种异体免疫损伤后气道微血管如何立即修复的知识。维持肺移植物中健康的微血管系统可能是预防终末气道纤维化（也称为闭塞性细支气管炎综合征（BOS））的关键。因此，了解内皮细胞如何促进血管修复可能有助于促进微血管恢复的治疗，从而预防BOS。小鼠原位气管移植（OTT）是研究气道微血管损失和祖细胞如何促进血管重建的理想模型。人和小鼠气道在移植后都是缺氧的。在OTT中，观察到缺氧诱导因子1 α（HIF-1 α）升高，伴有进行性缺氧，可能是移植后受体和供体循环之间连接的原因。这项提议将确定是否增加HIF-1 α，以及同种异体特异性T细胞，诱导血管生成信号，促进携带内皮抗原Tie 2的脓毒症修复性内皮细胞的流入。谱系分析将用于确定迁移内皮细胞在血管源性微血管系统恢复中的命运。有待检验的总体假设是气道移植受体通过发送Tie 2细胞对移植物衍生的HIF-1 α信号作出反应，Tie 2细胞随后并入移植物微血管。Specific Aim 1将使用内皮特异性表达Cre重组酶（Tie-2 Cre）的小鼠与报告小鼠Rosa 26 R（loxP Stop loxP yfp）杂交，以确定迁移到供体气道中的受体Tie 2细胞的命运。本研究还将探讨低氧和T细胞亚群对Tie 2细胞迁移的影响。具体目标2将阐明HIF-1 α的影响，通过获得和损失的功能实验，对气道血管重建，组织pO 2，移植排斥反应，Tie 2细胞迁移。这些研究的结果可能揭示气道血管修复的基本机制，并可能促进限制纤维化的新血管生成疗法。 公共卫生相关性：虽然肺移植是治疗终末期肺部疾病的一种方法，但接受该手术的大多数患者最终将死于气道瘢痕。这可能发生，部分原因是由于气道血流的暂时损失。拟议的研究将调查身体的正常修复过程如何用血管重新供应气道，以及如何利用这一过程来防止气道损伤。

DESCRIPTION (provided by applicant): Microvascular loss may be an unappreciated root cause of chronic rejection for all solid organ transplants. There is currently no knowledge about how airway microvasculature is repaired immediately following transplantation or alloimmune injury. Maintaining healthy microvasculature in lung allografts could be key for preventing terminal airway fibrosis, also known as the bronchiolitis obliterans syndrome (BOS). Therefore understanding how endothelial cells contribute to vascular repair may facilitate therapies which enhance microvascular recovery and, in so doing, prevent BOS. Mouse orthotopic tracheal transplantation (OTT) is an ideal model for examining microvascular loss in airways and how recipient-derived progenitor cells contribute to revascularization. Both human and mouse airways are hypoxic following transplantation. In OTT, rising hypoxia-inducible factor 1 alpha (HIF-1alpha) is observed with progressive hypoxia and may be responsible for the connection between recipient and donor circulations soon after transplantation. This proposal will determine if increased HIF-1alpha, as well as allospecific T cells, induce angiogenic signals that promote the influx of putatively reparative endothelial cells bearing the endothelial antigen, Tie2. Lineage analysis will be used to determine the fate of migrating endothelial cells in restoration of the recipient-derived microvasculature. The global hypothesis to be tested is that airway transplant recipients respond to graft- derived HIF-1alpha signals by sending Tie2 cells that subsequently incorporate into graft microvasculature. Specific Aim 1 will use mice with endothelial-specific expression of Cre-recombinase (Tie-2 Cre) intercrossed with reporter mice Rosa26R (loxP Stop loxp yfp) to determine the fate of recipient Tie2 cells migrating into donor airways. This aim will also study the effects of hypoxia and T cell subsets on Tie2 cell migration. Specific Aim 2 will elucidate the effects of HIF-1alpha, through gain- and loss- of function experiments, on airway revascularization, tissue pO2, graft rejection, and Tie2 cell migration. The results of these studies are likely to reveal fundamental mechanisms of vascular repair in airways and may promote novel angiogenic therapies that limit fibrogenesis. PUBLIC HEALTH RELEVANCE: While lung transplantation is a cure for end-stage pulmonary disease, the majority of patients undergoing this procedure will eventually die from scarring of the airways. This may happen, in part, because of a temporary loss of airway blood flow. The proposed studies will investigate how the body's normal reparative processes resupply airways with blood vessels and how this process might be utilized to prevent airway injury.