Apoptotic T Cell Clearance From Murine Lungs

描述（由申请人提供）：意义：细胞凋亡是肺气肿发病的核心，在急性肺损伤、败血症和病毒性肺炎中广泛存在。凋亡细胞（AC）必须被有效清除，以限制肺部炎症和维持免疫耐受。当肺部感染得到成功处理时，白细胞因凋亡而死亡，肺泡巨噬细胞（AMO）通过分泌tgf - β、PGE2和IL-10加速肺修复，这些免疫抑制介质也可以损害对病原体的防御并促进纤维化。因此，了解AMO对AC反应的机制和后果，这个项目的长期目标，可能会影响肺部医学的许多领域。该项目研究了一种名为MerTK的受体酪氨酸激酶，它对AC的MO摄取至关重要。新的初步数据显示，接触AC可诱导MerTK与先前参与AC摄取的两种MO分子相互作用，即a型清除率受体（SR-A）和脂蛋白受体相关蛋白（LRP）。与SR-A的关联先于MerTK激活，而与LRP的关联之后是LRP信号传导所必需的特定丝氨酸磷酸化。阻断MerTK可阻断AC诱导的ERK活化，而这是趋化因子诱导所必需的。本研究将验证MerTK依次与SR-A、LRP和特定细胞内分子相互作用以诱导MO识别、摄取和产生趋化因子以响应AC的假设。实验将分析AMO细胞系MH-S和来自正常小鼠的AMO细胞系，或来自缺乏SR-A的基因靶向小鼠，或来自MO谱系特异性缺乏LRP的小鼠。技术将包括吞噬和粘附试验；免疫沉淀和Western分析；实时聚合酶链反应;共焦显微镜;瞬时转染;以及利用小干扰rna的慢病毒感染进行基因沉默。相关性：肺细胞死亡是肺气肿、某些肺炎和其他肺损伤的特征。必须正确清除这些死细胞，以防止肺部损伤、瘢痕形成或免疫系统受损。这个项目研究了一种叫做MerTK的分子，它似乎可以控制清除。了解MerTK可能会带来新的治疗方法，以预防多种类型肺损伤的并发症。

DESCRIPTION (provided by applicant): Significance: Apoptosis is central to the pathogenesis of emphysema, and is widespread in acute lung injury, sepsis, and viral pneumonias. Apoptotic cells (AC) must be cleared efficiently to limit lung inflammation and to maintain immunologic tolerance. When lung infections are handled successfully, leukocytes die by apoptosis and their clearance by alveolar macrophages (AMO) hastens lung repair via secretion of TGF-beta, PGE2 and IL-10, immunosuppressive mediators that can also compromise defenses against pathogens and promote fibrosis. Thus, understanding the mechanisms and consequences of the AMO response to AC, the Long-Term Goals of this project, could impact many areas of pulmonary medicine. This project has studied a receptor tyrosine kinase called MerTK, which is essential for MO uptake of AC. Novel preliminary data are presented showing that exposure to AC induces MerTK to interact with two MO molecules previously implicated in AC uptake, the type A scavenger receptor (SR-A) and the lipoprotein receptor-related protein (LRP). Association with SR-A precedes MerTK activation, whereas association with LRP is followed by specific serine phosphorylation essential for LRP signaling. Blocking MerTK ablates AC- induced activation of ERK, which is required for alpha chemokine induction. This proposal will test the hypothesis that MerTK interacts sequentially with SR-A, LRP and specific intracellular molecules to induce MO to recognize, ingest and produce chemokines in response to AC. Experiments will analyze the AMO cell line MH-S and resident AMO from normal mice, or from gene-targeted mice lacking SR-A, or lacking LRP specifically on the MO lineage. Techniques will include assays of phagocytosis and adhesion; immunoprecipitation and Western analysis; real-time PCR; confocal microscopy; transient transfections; and gene silencing using lentiviral infection with small interfering RNAs. Relevance: Death of lung cells is a feature of emphysema, some pneumonias, and other lung injuries. These dead cells must be cleared correctly to prevent worsened lung injury, scarring, or immune compromise. This project studies a molecule called MerTK that appears to control clearance. Understanding MerTK could lead to new treatments to prevent complications of many types of lung damage.