Mechanisms of Repair of the Alveolar Epithelium after Lung Injury

肺损伤后肺泡上皮的修复机制

• 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
• 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

 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（由申请人提供）：意义。急性呼吸窘迫综合征（ARDS）是导致严重发病率和死亡率的主要原因。除了肺保护性机械通气策略和保守的液体管理外，ARDS没有特异性治疗方法。ARDS的标志是肺泡上皮细胞的损伤，包括细胞死亡，主要是肺泡I型（AT）细胞，导致渗透性和水肿液的流入，这又导致难治性低氧血症。该损伤阶段之后是修复反应，在此期间，存活的ATII细胞扩散到裸露的基底膜上，增殖并转分化为ATI细胞，从而恢复屏障完整性。重要的是，上皮修复是从ARDS恢复的主要决定因素。创新从历史上看，基本的ARDS研究集中在损伤阶段;不幸的是，旨在减轻损伤的治疗干预措施通常是不成功的。对修复机制的研究已经探索了ATII细胞增殖。在这个提议中，我们专注于ATI细胞脱落后，ATI细胞扩散到裸露的基底膜上。这种现象自20世纪70年代以来就已被认识到，但尚未在动物模型中得到充分研究。我们将扩散定义为表面积的增加，导致裸露基底膜的覆盖范围增加。我们已经开发了一种新的方法，使用严格的体视学技术严格测量遗传标记的ATII细胞的扩散。我们将描述轻度和重度损伤后ATII细胞扩散与增殖、转分化和屏障完整性恢复的关系。假说.基于我们的实验数据，我们假设缺氧诱导因子（HIF）1 α通过CXCR4/SDF 1信号通路促进ATII细胞扩散和屏障完整性的恢复。研究计划。目的1将测试在有限的肺损伤中，快速的、有丝分裂前的ATII细胞扩散是否与屏障恢复相关;此外，在严重损伤后，需要增殖以替换丢失的细胞，有丝分裂后的扩散是否与屏障恢复相关。目标2将确定HIF 1 α是否对传播至关重要。目的3验证CXCR/SDF 1信号通路促进和介导HIF 1 α在ATII细胞扩散中的作用。我们将使用功能获得和功能丧失技术，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体视学技术进行的扩散（肺泡表面覆盖面积）的形态测量。我们将直接将体内研究与培养的原代ATII细胞中的机械扩散试验联系起来。结论在这里，我们研究了ATII细胞扩散修复受损的肺泡上皮，重点是上皮屏障完整性的恢复，这是一个高度临床相关的结果。这些研究将确定新的治疗靶点，以加速ARDS中的上皮修复，最终促进肺水肿的消退和临床恢复。