Mechanisms of Repair of the Alveolar Epithelium after Lung Injury

肺损伤后肺泡上皮的修复机制

基本信息

批准号：
9247828
负责人：
Rachel Lynne Zemans
金额：
$ 5.32万
依托单位：
NATIONAL JEWISH HEALTH
依托单位国家：
美国
项目类别：
财政年份：
2016
资助国家：
美国
起止时间：
2016-04-01 至 2017-08-01
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9247828
关键词：
Address Adult Respiratory Distress Syndrome Air Sacs Alveolar Alveolar Cell Type I Animal Model Area Basement membrane Biological Assay CXCL12 gene CXCR CXCR4 gene Cell Death Cell Line Cell Proliferation Cell division Cells Clinical Data Daughter Development Disease Edema Epithelial Epithelial Cells Epithelium Foundations Genes Goals HIF1A gene Health Care Costs Hour Hydrochloric Acid Hypoxemia Hypoxia Inducible Factor Inflammatory Injury Investigation Label Link Liquid substance Lung Measurement Measures Mechanical ventilation Mediating Methods Mitotic Modeling Molecular Morbidity - disease rate Morphology Mus Outcome Permeability Phase Process Proliferating Pulmonary Edema Recovery Refractory Research Resolution Role Signal Pathway Signal Transduction Surface Techniques Testing Therapeutic Therapeutic Intervention Time alveolar epithelium alveolar type II cell base chemokine clinically relevant daughter cell hypoxia inducible factor 1 in vivo injured innovation keratinocyte loss of function lung injury mortality new therapeutic target novel novel therapeutic intervention public health relevance repaired response restoration targeted treatment therapy design transdifferentiation

项目摘要

DESCRIPTION (provided by applicant): Significance. The Acute Respiratory Distress Syndrome (ARDS) is responsible for significant morbidity and mortality. Aside from lung protective mechanical ventilation strategies and conservative fluid management, there are no specific therapies for ARDS. A hallmark of ARDS is injury to the alveolar epithelium, including cell death, primarily of alveolar type (AT) I cells, resulting in permeability and the influx of edma fluid, which in turn leads to refractory hypoxemia. This injury phase is followed by a reparative response during which surviving ATII cells spread onto the denuded basement membrane, proliferate, and transdifferentiate into ATI cells, thus restoring barrier integrity. Importantly, epithelial repair is a primary determinant of recovery from ARDS. Innovation. Historically, basic ARDS research has focused on the injury phase; unfortunately, therapeutic interventions designed to mitigate injury have generally been unsuccessful. Investigations into reparative mechanisms have explored ATII cell proliferation. In this proposal, we focus on ATII cell spreading onto the denuded basement membrane after the sloughing of ATI cells. This phenomenon has been recognized since the 1970s but has not been well studied in animal models. We define spreading as an increase in surface area resulting in increased coverage of the denuded basement membrane. We have developed a novel method to rigorously measure spreading of genetically-labeled ATII cells using stringent stereologic techniques. We will characterize ATII cell spreading after mild and severe injury in relationship to proliferation, transdifferentiation, and the restitution of barrier integrity. Hypothesis. Based on our preliminar data, we hypothesize that Hypoxia Inducible Factor (HIF) 1α promotes ATII cell spreading and the restitution of barrier integrity via CXCR4/SDF1 signaling. Research Plan. Aim 1 will test whether in limited lung injury, rapid, pre-mitotic ATII cell spreading is associated with barrier restoration; in addition, after severe injury, requiring proliferation to replace lost cells, whethr post-mitotic spreading correlates with barrier restoration. Aim 2 will determine whether HIF1α is critical for spreading. Aim 3 will test the hypothesis that CXCR/SDF1 signaling promotes and mediates the role of HIF1α in ATII cell spreading. We will use both gain- and loss-of-function techniques, including ATII cell specific gene deficient mice. Our primary readout will be morphometric measurement of spreading (area of alveolar surface covered) using stereologic techniques. We will directly link in vivo studies to mechanistic spreading assays in cultured primary ATII cells. Conclusion. Here, we study repair of the injured alveolar epithelium by ATII cell spreading with an emphasis on the restitution of epithelial barrier integrity, a highly cliniclly relevant outcome. These studies will identify novel therapeutic targets to accelerate epithelial repair in ARDS, ultimately promoting the resolution of pulmonary edema and clinical recovery.

描述（适用提供）：意义。急性呼吸窘迫综合征（ARDS）负责明显的发病率和死亡率。除了肺部受保护的机械通气策略和保守的流体管理外，没有针对ARDS的具体疗法。 ARDS的标志受到肺泡上皮的伤害，包括细胞死亡，牙槽类型（AT）I细胞的主要（AT）I细胞，导致渗透性和EDMA液的影响，这又导致难治性低氧血症。在此损伤阶段之后是一种修复反应，在此过程中，生存的ATII细胞扩散到裸露的基底膜上，增殖并转分化到ATI细胞中，从而恢复屏障完整性。重要的是，上皮修复是从ARDS中恢复的主要确定。创新。从历史上看，基本的ARDS研究集中在伤害阶段。不幸的是，旨在减轻伤害的治疗干预措施通常没有成功。对修复机制的研究探索了ATII细胞增殖。在此提案中，我们专注于ATI细胞链路后扩散到裸露的基底膜上的ATII细胞。自1970年代以来，这种现象已被认可，但在动物模型中的研究还不够。我们将扩散定义为表面积的增加，从而增加了裸露地下室膜的覆盖率。我们已经开发了一种新的方法，可以使用严格的立体技术严格测量遗传标记的ATII细胞的扩散。我们将表征在与增殖，转化和屏障完整性的约束中，轻度和严重受伤后的ATII细胞扩散。假设。根据我们的前数据，我们假设缺氧诱导因子（HIF）1α促进了ATII细胞的扩散和通过CXCR4/SDF1信号传导的障碍完整性的约束。研究计划。 AIM 1将测试在有限的肺损伤中，快速，有丝分裂的ATII细胞扩散与屏障恢复有关；另外，在严重受伤之后，需要增殖才能替代损失的细胞，是否与屏障恢复相关。 AIM 2将确定HIF1α是否对扩散至关重要。 AIM 3将检验以下假设：CXCR/SDF1信号促进并介导HIF1α在ATII细胞扩散中的作用。我们将使用功能和功能丧失技术，包括ATII细胞特异性基因缺陷小鼠。我们的主要读数将是使用立体技术对扩散的形态计量测量（牙槽表面覆盖的面积）。我们将直接将体内研究与培养的原代ATII细胞中的机械扩散测定联系起来。结论。在这里，我们通过ATII细胞扩散研究了受伤的肺泡上皮的修复，重点是上皮屏障完整性的约束，这是一个高度临床相关的结果。这些研究将确定新型的热靶标，以加速ARDS中的上皮修复，最终促进肺水肿和临床恢复的分辨率。