PDGFR-beta+ stromal cells as critical regulators of immune response to tissue injury

 描述(申请人提供)：周细胞是一组未被充分研究的血管周围基质细胞群，与包括肺在内的大多数组织中的微血管系统相关。本次拨款申请的初步数据显示：1)FoxD1来源的PDGFRü+周细胞表达多个MyD88依赖的Toll样受体；2)在正常小鼠和肺损伤小鼠的支气管肺泡灌洗液(BAL)中，PDGFRü+细胞表达炎性趋化因子并通过MyD88依赖的信号下调Angpt1；以及3)PDGFRü+细胞在肺损伤期间在体内具有类似的转录反应。这些数据支持这一应用的中心假设，即FoxD1来源的PDGFRü+细胞作为间质哨兵，检测和响应在肺泡破裂后释放到间质中的结构性肺泡腔分子。激活的PDGFRç+细胞通过促进微血管通透性和白细胞募集来做出反应。为了验证这一假说，我们提出了三个目标。第一个目的是评估肺泡室分子激活PDGFRç+细胞的机制(S)。BAL液激活PDGFFR？+细胞所需的受体(S)将被确定。激活BAL液中“危险信号”的PDGFRü+细胞将使用一种称为正交色谱的新的、无偏倚的方法来识别。将评估不同的PDGFR？+亚群的作用。第二个目标是使用与原代内皮细胞共培养的独特3D-微流体设备来研究PDGFRç+细胞在炎症过程中对内皮功能的调节作用，重点是Angpt1-Tie2信号。将测量内皮屏障完整性、白细胞粘附性和血小板粘附性。第三个目标将在体内确定肺损伤期间周细胞激活的功能后果。肺损伤过程中PDGFR？+细胞的“翻译转录组”将被用来识别关键的信号网络和PDGFR？？细胞的新功能反应。肺损伤将在正常小鼠和PDGFR？限制性MyD88缺失小鼠之间进行比较。该项目将检验PDGFRü+细胞是无法识别的“间质哨兵细胞”的假设，这些细胞随时准备检测和应对严重的肺泡上皮损伤和屏障完整性的丧失。急性呼吸窘迫综合征(ARDS)或严重的急性肺损伤是危重患者死亡和发病的主要原因，仅在美国估计每年就有19万名患者受到影响。尽管经过了几十年的研究，但ARDS的生物学机制尚不完全清楚，也没有有效的药物治疗方法。该项目代表了该领域的一个新方向，有可能推动新的、创新的治疗策略的发展。

 DESCRIPTION (provided by applicant): Pericytes are an understudied population of perivascular stromal cell associated with the microvasculature in most tissue, including the lung. Preliminary data in this grant application show that 1) FoxD1-derived, PDGFRß+ putative pericytes express multiple MyD88-dependent Toll-like receptors, 2) following exposure to broncho-alveolar lavage (BAL) fluid collected from normal mice and mice with lung injury, PDGFRß+ cells express inflammatory chemokines and downregulate Angpt1 via MyD88-dependent-signaling, and 3) PDGFRß+ cells have similar transcriptional responses in vivo during lung injury. These data support the central hypothesis of this application that FoxD1-derived, PDGFRß+ cells function as interstitial sentinels, which detect and res-pond to constitutive alveolar luminal molecules that are released into the interstitium following alveolar disruption. Activated PDGFRß+ cells respond by promoting microvascular permeability and leukocyte recruitment. To test this hypothesis, three aims are proposed. The first aim will evaluate mechanism(s) by which PDGFRß+ cells are activated by alveolar compartment molecules. Receptor(s) required for PDGFRß+ cell activation by BAL fluid will be identified. PDGFRß+ cell activating "danger signals" in BAL fluid will be identified, using a novel, unbiased approach termed orthogonal chromatography. The role of different PDGFRß+ subpopulations will be evaluated. The second aim will use a unique 3D-microfluidic device with co-culture of primary endothelial cells to examine the role of PDGFRß+ cells in regulation of endothelial function during inflammation, focusing on Angpt1-Tie2 signaling. Endothelial barrier integrity, leukocyte adhesion, and platelet adhesion will be measured. The third aim will determine in vivo functional consequences of pericyte activation during lung injury. The "translated transcriptome" of PDGFRß+ cells during lung injury will be used to identify critical signaling networks and new functional responses of PDGFRß+ cells. Lung injury will be compared between normal mice and mice with PDGFRß-restricted MyD88 deletion. This project will test the hypothesis that PDGFRß+ cells are unrecognized "interstitial sentinel cells", which stand ready to detect and respond to significant alveolar epithelial injury and loss of barrier integrity. The acute respiratry distress syndrome (ARDS) or severe acute lung injury is a major cause of death and morbidity among critically ill patients, affecting an estimated 190,000 patients annually in the United States alone. Despite decades of research, the biology of ARDS is incompletely understood, and no effective pharmacological treatments exist. This project represents a new direction in the field with the potential to drive the development of novel, innovative therapeutic strategies.