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成分损失的机制诱发肺气肿。解释肺气肿的两种主要范式假设：a)炎症引发的蛋白酶/抗蛋白酶失衡；b)肺泡内皮细胞过度凋亡导致毛细血管萎缩。这两种机制可以解释肺气肿特征肺泡壁的丧失。然而，在肺气肿中，过度的肺结构细胞凋亡与激活的炎症状态共存以及它们相互作用的层次尚未得到解释。我们认为内皮单核细胞激活蛋白（EMAP II）的过量是肺气肿中细胞凋亡和炎症之间联系的统一分子机制。EMAP II是一种由肺气肿肺部疾病诱导的细胞因子，在半胱天冬酶和基质金属蛋白酶的蛋白水解裂解后从细胞中释放出来，已知其参与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活化。考虑到EMAP II对内皮细胞的促凋亡作用，再加上其激活和招募促炎单核细胞的能力，我们假设吸烟时过量的EMAP II释放参与了肺内皮细胞凋亡和单核细胞炎症激活，因此是肺气肿的关键分子介质。我们假设烟雾诱导EMAP II，导致依赖CXCR3的内皮细胞凋亡并激活单核细胞。活化的半胱天冬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相关，因为我们测量了肺气肿患者肺中EMAP II的增加。事实上，我们的数据表明，烟雾诱导的肺气肿在小鼠中先发生EMAP II的产生和凋亡，并且肺特异性EMAP II的增加足以引起肺凋亡和肺气肿。我们将通过中和香烟烟雾诱导小鼠肺气肿中的抗体和条件EMAP II转基因在肺中的过表达来测试分泌的EMAP II及其受体的功能。我们制定了3个具体目标：1。确定EMAP II是否是香烟烟雾引起的肺气肿的生物标志物和分子介质。2 .研究过量的肺EMAP II是否通过触发肺内皮细胞凋亡或单核/巨噬细胞募集诱导肺气肿；探讨EMAPⅱ诱导人原代肺内皮细胞凋亡的机制。如果实现这些目标，有望将EMAP II定位为肺气肿的治疗靶点和/或生物标志物。项目描述：我们提出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可能成为生物体液中可测量的生物标志物，也可能被证明是治疗选择稀缺、发病率和死亡率高的疾病的一个有吸引力的药理学靶点。在细胞应激和持续的蛋白酶激活刺激下，过量的EMAP II释放会导致肺部肺泡破坏的恶性循环。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，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.