The Role of PECAM in Models of Lung Injury

描述（由申请人提供）：血小板内皮细胞粘附分子-1 （PECAM-1, CD31）是一种粘附和信号分子，在内皮细胞（EC）、白细胞和血小板上表达。它是调节白细胞跨内皮迁移的关键分子，尽管在肺循环中有高水平表达，但对其参与的机制或在肺部疾病中的作用知之甚少。使用PECAM-1敲除（KO）小鼠，研究人员发现免疫复合物沉积病的肺中性粒细胞浸润高度依赖pecam。该资助的目的是通过体内和体外模型确定PECAM调节转运的机制，并确定PECAM-1在其他肺部疾病模型中的作用。有待验证的假设是PECAM通过PECAM胞质域局部区域介导的内皮细胞和中性粒细胞信号事件调节转运，PECAM-1仅在特定类型的肺损伤中发挥重要作用。提出了三个独立但相关的特定目的：在Aim 1中，PECAM-1调节中性粒细胞向肺迁移的机制将通过野生型和KO动物之间产生的骨髓嵌合体以及通过重组具有特定PECAM-1亚型的细胞质结构域突变的PECAM-1亚型的PECAM- KO小鼠来确定。在Aim 2中，PECAM-1调节跨内皮迁移的机制将使用体外系统定义，该系统包括人肺EC迁移模型和实验迁移模型，其中PECAM-1突变形式将被转染到pecam阴性的人内皮样细胞系或pecam阴性的来自KO小鼠的小鼠EC中。在Aim 3中，将使用抗PECAM-1抗体和PECAM敲除小鼠来测试PECAM-1在“内皮驱动”vs中调节白细胞迁移到肺中的重要性。在氧化诱导的肺损伤模型和其他免疫介导的肺损伤模型中，“白细胞驱动”的肺部炎症。这些研究将填补对肺和细胞粘附生物学基本认识的空白，并提供潜在有用的治疗信息。

DESCRIPTION (provided by applicant): Platelet-Endothelial Cell Adhesion Molecule-1 (PECAM-1, CD31) is an adhesion and signaling molecule that is expressed on endothelial cells (EC), leukocytes, and platelets. It is a key molecule in regulating transendothelial migration of leukocytes, however little in known about the mechanisms involved or its role in lung disease, despite high levels of expression in the pulmonary circulation. Using PECAM-1 knockout (KO) mice, the investigators have found that lung neutrophil infiltration in immune complex deposition disease is highly PECAM-dependent. The goals of this grant are to define the mechanisms by which PECAM regulates transmigration using in vivo and in vitro models and to define the role of PECAM-1 in other models of lung disease. The hypotheses to be tested are that PECAM regulates transmigration through endothelial and neutrophil signaling events mediated by localized regions of the PECAM cytoplasmic domain and that PECAM-1 will play an important role in only specific types of lung injury. Three independent, but related specific aims are proposed: In Aim 1, the mechanisms by which PECAM-1 regulates migration of neutrophils into the lung will be determined using bone marrow chimeras generated between wild type and KO animals and by reconstituting PECAM KO mice with specific PECAM-1 isoforms that have mutations in their cytoplasmic domains. In Aim 2, the mechanisms by which PECAM-1 regulates transendothelial migration will be defined using in vitro systems that include a human lung EC transmigration model and experimental transmigration models in which mutant forms of PECAM-1 will be transfected into a PECAM-negative human endothelial-like cell line or into PECAM-negative murine EC's derived from the KO mice. In Aim 3, anti-PECAM-1 antibodies and PECAM knockout mice will be used to test the importance of PECAM-1 in regulating leukocyte transmigration into the lung in "endothelial-driven" vs. "leukocyte-driven" lung inflammation, in models of oxidant-induced lung injury, and in other immune-mediated lung injury models. These studies will fill a gap in the basic understanding of lung and cell adhesion biology, as well as provide potentially useful therapeutic information.