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机制的核心，广泛存在于急性肺损伤、脓毒症和病毒性肺炎中。凋亡细胞（AC）必须被有效地清除，以限制肺部炎症和维持免疫耐受。当肺部感染被成功处理时，白细胞通过凋亡而死亡，并且它们被肺泡巨噬细胞（AMO）清除，通过分泌TGF-β、PGE 2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，本项目的长期目标，可能会影响肺部医学的许多领域。本项目研究了一种称为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，暴露于AC诱导MerTK相互作用与两个MO分子先前牵连的AC摄取，A型清道夫受体（SR-A）和脂蛋白受体相关蛋白（LRP）。与SR-A的关联先于MerTK活化，而与LRP的关联之后是LRP信号传导所必需的特异性丝氨酸磷酸化。阻断MerTK消除AC诱导的ERK活化，这是α趋化因子诱导所需的。该提案将检验MerTK与SR-A、LRP和特异性细胞内分子顺序相互作用以诱导MO识别、摄取和产生响应AC的趋化因子的假设。实验将分析AMO细胞系MH-S和来自正常小鼠或来自缺乏SR-A或缺乏MO谱系特异性LRP的基因靶向小鼠的常驻AMO。技术将包括吞噬和粘附的测定;免疫沉淀和Western分析;实时PCR;共聚焦显微镜;瞬时转染;和使用小干扰RNA的慢病毒感染的基因沉默。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亡细胞，以防止肺损伤、瘢痕形成或免疫功能受损恶化。该项目研究了一种名为MerTK的分子，该分子似乎控制清除。了解MerTK可能会导致新的治疗方法，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.