A Novel Exosomal Inflammatory Pathway

项目总结 这个计划定义了一些人所说的中性粒细胞炎症的范式转换途径 与IL-8相关的经典模式不同，它可以在慢性炎症性疾病中自我传播 慢性阻塞性肺病等疾病。具体地说，IL-8启动中性粒细胞(PMN)内流，PMN继而释放基质 金属蛋白酶(MMPs)和脯氨酸内肽酶(PE)，它们降解胶原并产生PMN特异性 丙氨酸-甘氨酸-丙氨酸(Pgp)。在更常见的急性炎症情况下，Pgp途径 被破坏Pgp的白三烯A4水解酶(LTA4H)的氨基肽酶活性终止。香烟 吸烟(CS)可以化学修饰和失活LTA4H的氨基肽酶，但不能改变水解酶的活性 作为乙酰化Pgp，使其对LTA4H具有免疫力。这推动了PGP水平的持续升高和慢性 慢性阻塞性肺疾病的中性粒细胞炎症。在该计划了解PGP系统的旅程中，我们已经确定 COPD、CF和ARDS的一种新的潜在预后生物标志物，连接基质降解与血管泄漏， 并发现了一种促炎症酶LTA4H的抗炎作用。PGP最近也被 细胞外基质降解与急性肺损伤、炎症性肠病、脑缺血有关 中风和急性肺部感染的调制。因此，PGP系统的发现具有 在许多疾病和器官中作为病理生理学的基本介体具有特殊的意义。一 我们研究的谜团是无法在体外用胶原蛋白和适当的 溶液中的蛋白酶。这个R35应用的论点是，这个谜团是由于要求PGP 产生酶，如PE，是与外切体相关的。这一想法得到了许多观察结果的支持，大多数 值得注意的是，COPD患者的呼吸道外周体是PMN来源的，并导致COPD样疾病，而不是对照组 当转移到小鼠身上时，表型。总而言之，这些发现导致了我们的假设，即蛋白水解性外切体 构成炎症过程的一个新方面，并可能参与慢性炎症紊乱，如 作为慢性阻塞性肺疾病通过PGP途径。如果成功，该项目的结果将定义一种新的实体，即蛋白质分解 Exosome，它通过Pgp的产生来驱动中性炎症，Pgp由LTA4H和Can调节 在小鼠身上引起一种类似COPD的疾病。在人类研究中，我们将对蛋白水解性外切体进行表型并描绘 它们是否是COPD的生物标志物，与疾病参数相关，并能将病理从 从人到老鼠。在COPD的吸烟小鼠模型中，我们将描述这种外切体的进化和 它们是否能将疾病从吸烟的动物传染给幼稚的动物。虽然，对一种新的致病原的定义 实体是令人望而生畏的，该计划的跟踪记录以及PI和团队的专业知识表明 努力吧。如果是这样的话，对蛋白分解外切体的完全了解可能会导致新的诊断和 治疗慢性阻塞性肺病等慢性炎症性疾病。

PROJECT SUMMARY This Program has defined what some have called a paradigm shifting pathway of neutrophilic inflammation which, unlike the “classic” mode associated with IL-8, can become self-propagating in chronic inflammatory diseases such as COPD. Specifically, IL-8 initiates neutrophil (PMN) influx, the PMNs in turn release matrix metalloproteases (MMPs) and prolyl endopeptidase (PE) which degrade collagen and generate the PMN-specific matrikine, proline-glycine-proline (PGP). In more common acute inflammatory circumstances, the PGP pathway is terminated by the aminopeptidase activity of leukotriene A4 hydrolase (LTA4H) which destroys PGP. Cigarette smoking (CS) can chemically modify and inactivate LTA4H’s aminopeptidase but not hydrolase activity as well as acetylate PGP rendering it immune to LTA4H. This drives persistently elevated PGP levels and chronic neutrophilic inflammation in COPD. In the Program’s journey to understand the PGP system, we have identified a novel potential prognostic biomarker for COPD, CF, and ARDS, linked matrix degradation to vascular leak, and discovered an anti-inflammatory role for a pro-inflammatory enzyme, LTA4H. PGP has also recently been shown to link extracellular matrix degradation to: acute lung injury, inflammatory bowel disease, ischemic brain stroke, and modulation of acute pulmonary infection. Consequently, the discovery of the PGP system has particular significance as a fundamental mediator of pathophysiology in a number of disorders and organs. One enigmatic aspect of our studies has been an inability to generate PGP in vitro with collagen and the appropriate proteases in solution. The thesis of this R35 application is that this enigma is due to the requirement that PGP generating enzymes, such as PE, be exosome associated. This idea is supported by many observations, most notably, that airway exosomes from COPD patients, but not controls, are PMN-derived and cause a COPD-like phenotype when transferred to mice. Collectively, the findings led to our hypothesis that proteolytic exosomes constitute a new aspect of the inflammatory process and may participate in chronic inflammatory disorders such as COPD via the PGP pathway. If successful, the results of this project will define a novel entity, i.e. proteolytic exosome, which drives neutrophilic inflammation via PGP generation which is regulated by LTA4H and can cause a COPD-like disease in mice. In human studies, we will phenotype proteolytic exosomes and delineate whether they are biomarkers of COPD that correlate with disease parameters and can transfer pathology from humans to mice. In a smoking mouse model of COPD we will characterize the evolution of such exosomes and whether they can transfer disease from smoked to naïve animals. Although, the definition of a new pathogenic entity is daunting, the track record of this Program and the expertise of the PI and team suggest a successful endeavor. If so, a complete understanding of the proteolytic exosome may lead to new diagnostics and therapeutics for chronic inflammatory diseases such as COPD.