EMAP II, a molecular link of inflammation and apoptosis in pulmonary emphysema.

描述(由申请人提供)：香烟烟雾通过导致肺基质和细胞元素丢失的机制导致肺气肿。解释肺气肿的两种主要模式是：a)炎症引发的蛋白水解酶/抗蛋白水解酶失衡；b)肺泡内皮细胞过度凋亡导致毛细血管退缩。这两种机制可以解释肺气肿的肺泡壁丢失。然而，肺气肿中过度的肺结构细胞凋亡和激活的炎症状态的共存及其相互作用的等级尚未被解释。我们认为内皮细胞-单核细胞激活蛋白II(EMAP II)的过度表达是肺气肿细胞凋亡和炎症之间联系的统一分子机制。Emap II是一种细胞因子，由肺气肿肺中存在的条件诱导，在caspase和基质金属蛋白酶的蛋白分解作用下从细胞中释放出来，这两种酶都参与了COPD。我们发现CXCR3是EMAP II的功能性受体，介导EMAP II诱导的内皮细胞凋亡和单核细胞激活。鉴于EMAP II对内皮细胞具有强大的促凋亡作用，再加上其激活和募集促炎单核细胞的能力，我们推测吸烟导致的EMAP II过度释放既参与了肺内皮细胞的凋亡，也参与了单核细胞的炎症激活，因此是肺气肿的关键分子介质。我们推测，吸烟可诱导EMAP II，导致依赖于CXCR3的内皮细胞凋亡并激活单核细胞。激活的半胱氨酸天冬氨酸酶和基质金属蛋白酶可能进一步增加肺中的EMAP II，放大最终导致肺气肿的损伤信号。这些研究与人类肺气肿有关，因为我们测量了肺气肿患者肺中EMAP II的升高。事实上，我们的数据表明，在吸烟诱导的肺气肿之前，小鼠体内会产生EMAP II和细胞凋亡，而肺特异性EMAP II的增加足以导致肺细胞凋亡和肺气肿。我们将通过中和香烟烟雾诱导的小鼠肺气肿抗体和有条件地在肺中过度表达EMAP II来检测分泌的EMAP II及其受体的功能。1.确定EMAP II是否是香烟烟雾所致肺气肿的生物标志物和分子介质。2.探讨过量的EMAP II是通过触发肺内皮细胞的凋亡还是通过单核/巨噬细胞的募集而诱发肺气肿；3.探讨EMAP II诱导原代培养的人内皮细胞凋亡的机制。这些目标如果实现，预计将把EMAP II定位为肺气肿的治疗目标和/或生物标志物。项目简介：我们建议，我们的实验计划将使我们能够确定肺气肿的关键参与者；EMAP II，它可能成为可在生物液中测量的生物标记物，也可能被证明是一种具有吸引力的药理学靶点，用于治疗一种缺乏治疗选择、发病率和死亡率高的疾病。细胞应激和持续的蛋白酶激活刺激的EMAP II的过度释放将导致肺泡破坏的恶性和值得靶向的循环。此外，我们的工作将允许完善内皮细胞凋亡的机制，同时统一该领域的两种理论，即过度炎症和过度凋亡。

DESCRIPTION (provided by applicant): Cigarette smoke induces emphysema through mechanisms which cause a loss of both matrix and cellular elements of the lung. The two main paradigms to explain emphysema postulate a) an imbalance of protease/antiproteases triggered by inflammation and b) a state of excessive alveolar endothelial apoptosis causing capillary regression. These two mechanisms would explain the loss of alveolar wall characterizing emphysema. However, the coexistence of an excessive lung structural cell apoptosis with that of an activated inflammatory state in emphysema and the hierarchy of their interaction have not yet been explained. We propose the excess of endothelial-monocyte-activating protein (EMAP II) is a unifying molecular mechanism to link apoptosis and inflammation in emphysema. EMAP II is a cytokine induced by conditions present in emphysematous lungs, being released from cells upon proteolytic cleavage by caspases and matrix metalloproteinases, which are known to participate in COPD. We identified CXCR3 as a functional receptor for EMAP II which mediates EMAP II-induced endothelial cell apoptosis and monocyte activation. Given the potent pro-apoptotic effect of EMAP II on endothelial cells, coupled with its ability to activate and recruit pro-inflammatory monocytes, we hypothesize that excessive EMAP II release in response to cigarette smoking engages both lung endothelial cell apoptosis and monocyte inflammatory activation, and therefore is a key molecular mediator of emphysema. We postulate that smoke induces EMAP II, which causes CXCR3- dependent endothelial apoptosis and activates monocytes. Activated caspases and matrix metalloproteinases may further increase EMAP II in the lung, amplifying damage signals that culminate in emphysema. These studies are relevant to human emphysema, as we measured increased EMAP II in the lungs of emphysema patients. Indeed, our data indicate that smoke-induced emphysema is preceded by EMAP II production and apoptosis in mice and lung-specific EMAP II increases are sufficient to cause lung apoptosis and emphysema. We will test the function of the secreted EMAP II and its receptor by neutralizing antibodies in cigarette smoke-induced emphysema in mice and conditional EMAP II transgenic overexpression in the lung. We developed 3 specific aims: 1. To determine whether EMAP II is a biomarker and molecular mediator of cigarette smoke-induced emphysema. 2 To investigate whether excessive lung EMAP II induces emphysema by triggering lung endothelial cell apoptosis or by recruitment of monocytes/macrophages, and 3. To determine the mechanism of EMAP II-induced cell apoptosis in primary human endothelial lung cells. These aims, if achieved are expected to position EMAP II as a therapeutic target and/or biomarker of emphysema. PROJECT NARRATIVE: We propose that our experimental plan will allow us to identify a key player in emphysema; EMAP II, which may become a biomarker measurable in biological fluids, and may also prove to be an attractive pharmacological target in a disease with scarce therapeutical options, and a high morbidity and mortality. The excessive EMAP II release stimulated by cellular stresses and ongoing protease activation would account for a vicious and worth targeting cycle of alveolar destruction in the lung. Furthermore, our work will allow to refine mechanisms of endothelial cell apoptosis while unifying the two theories in the field, that of excessive inflammation with that of excessive apoptosis.