Probing immunovascular mechanobiology in pneumonia-associated acute lung injury at the single capillary level

项目总结/摘要 急性呼吸窘迫综合征（ARDS）及其不太严重的形式，急性肺损伤（ALI），是毁灭性的， 可能由肺炎引起的危及生命的呼吸道疾病。肺泡上皮-内皮损伤 ARDS中的屏障导致肺泡水肿，其机械地损害肺泡扩张性，阻碍气体进入， 交换，并促进炎症。正常肺力学和生物学的破坏表明需要 在肺免疫生物学和物理科学的交叉点上研究ARDS。肺的重要性 机械生物学反映在目前有效的治疗干预，目标肺力学，如 保护性机械通气和俯卧位。虽然已知ARDS水肿会损害肺泡 力学，对毛细血管力学，血液动力学和氧气运输的下游后果是 不太出名。因此，仍然不清楚ARDS中毛细血管功能的改变如何影响运输， 隔离、迁移和吞噬关键免疫细胞类型，如常驻和招募 巨噬细胞我们对ARDS微生理学的理解受到研究肺的技术差距的限制 在细胞尺度上实时监测血液循环功能。目前的成像方式，如MRI/CT 组织学分析缺乏必要的空间和时间分辨率来探测动态事件， 血管流动、细胞运输和迁移以及气体交换。为了满足这些需求，我们 开发了一种新的“LungEx”系统，该系统允许对肺的呼吸循环功能进行机械探测， 在单个毛细管尺度上实时。LungEx是离体通气和灌注的鼠肺， 物理学和生物学接近体内肺，结合透明的“水晶”胸腔， 毛细管功能的实时分辨率光学显微镜。将LungEx与实验小鼠组合 在肺炎引起的ALI模型（PNA-ALI）中，我们初步观察到毛细血管功能的改变， 水肿的PNA-ALI区域。在这里，利用LungEx，我们将测试以下假设： PNA-ALI中的力学损害毛细血管力学，限制RBC流动运输，从而减少氧气 毛细血管规模上的运输（目标1）; PNA-ALI的力学改变不同地阻碍了居民与 募集巨噬细胞功能，促进机械敏感性炎症特征（目的2）。这些研究将 提高我们对肺炎相关的机械生物学和机械免疫学的理解 开始于单毛细血管水平的ARDS发病机制及其如何影响关键免疫血管 肺的组成部分。作为博士前奖学金培训的一部分，以医生科学家的职业生涯， 拟议的工作将强调基于假设的实验设计，科学交流和 导师制，研究与临床实践相结合，并将在波士顿大学进行。

PROJECT SUMMARY/ABSTRACT Acute respiratory distress syndrome (ARDS) and its less severe form, acute lung injury (ALI), are devastating, life-threatening respiratory illnesses that can result from pneumonia. Injury to the alveolar epithelial-endothelial barrier in ARDS results in alveolar edema that mechanically impairs alveolar distensibility, hinders gas exchange, and promotes inflammation. Disruption of normal lung mechanics and biology demonstrate the need to study ARDS at the intersection of lung immunobiology and physical sciences. The importance of lung mechanobiology is reflected by current effective therapeutic interventions that target lung mechanics, such as protective mechanical ventilation and prone positioning. While ARDS edema is known to compromise alveolar mechanics, the downstream consequences on capillary mechanics, hemodynamics, and oxygen transport are not well known. As a result, it remains unknown how altered capillary function in ARDS affects the trafficking, sequestration, migration, and phagocytosis of key immune cell types, such as resident and recruited macrophages. Our understanding of ARDS microphysiology is limited by a technological gap to study lung respiratory-circulatory function at the cellular scale in real-time. Current imaging modalities such as MRI/CT and histological analyses lack the necessary spatial and temporal resolution to probe dynamic events such as vascular flow, cellular trafficking and migration, and gas exchange. To address these needs, we have developed a novel “LungEx” system that allows mechanistic probing of lung respiratory-circulatory function in real-time at the single capillary scale. LungEx is an ex vivo ventilated and perfused murine lung with preserved physics and biology near that of in vivo lungs, combined with a transparent “crystal” ribcage to allow high- resolution optical microscopy of capillary function in real-time. Combining LungEx with experimental murine models of ALI caused by pneumonia (PNA-ALI), we have preliminarily observed altered capillary function in edematous PNA-ALI regions. Here, utilizing LungEx, we will test the hypotheses that: altered alveolar mechanics in PNA-ALI impairs capillary mechanics, restricts RBC flow trafficking, and hence reduces oxygen transport on the capillary scale (Aim 1); and altered mechanics in PNA-ALI differentially impedes resident vs recruited macrophage function, promoting a mechanosensitive inflammatory profile (Aim 2). These studies will improve our understanding of the mechanobiology and mechanoimmunity underlying pneumonia-associated ARDS pathogenesis that begins on the single capillary level and how it affects key immunovascular components of the lung. As part of the pre-doctoral fellowship training towards a physician-scientist career, the proposed work will emphasize hypothesis-based experimental design, scientific communication and mentorship, integration of research with clinical practice, and will be carried out at Boston University.