Cell Priming, Receptor Cross-Talk, and Acute Lung Injury

 描述(申请人提供)：创伤相关疾病的负担相当大。失血和/或脑损伤通常导致早期死亡，超过60%的存活患者后来死于与全身炎症反应综合征(SIRS)和急性肺损伤(ALI)相关的原因。由于器官炎症和衰竭发生前的时间滞后，这些患者非常适合于旨在防止这些情况发生的预防性干预措施。尽管如此，几乎没有确定易受SIRS和ALI影响的具体目标。由于内皮细胞在失血性休克(HS)诱导的炎症反应中起着重要而广泛的作用，而EC程序性死亡对炎症的进展有重要影响，深入了解HS诱导的EC下垂(一种依赖于caspase-1的程序性细胞死亡)的发病机制，将为HS后SIRS和ALI提供新的潜在治疗靶点。在更广泛的意义上，拟议的研究将有助于更好地了解一些人类炎症性疾病的发病机制，其中内皮参与了炎症过程。上睑下垂是最近发现的一种宿主细胞死亡，由一系列微生物感染和非感染性刺激，包括中风、心脏病发作或癌症。上睑下垂的特点是质膜迅速破裂，细胞内促炎性物质释放。我们已发表的和初步的研究结果表明，上睑下垂在HS后炎症的发展中起着重要作用。我们观察到：1)HS诱导炎症小体激活后的肺内皮细胞下垂，这一诱导需要HMGB1-TLR4信号；2)肺内皮细胞下垂导致从内皮细胞释放促炎细胞因子，并诱导细胞因子在肺泡巨噬细胞中表达；3)上皮性内皮细胞增加中性粒细胞(PMN)与内皮细胞的黏附；4)上皮性内皮细胞增加内皮通透性；5)通过EC特异性的TLR4基因敲除来阻止HS诱导的EC下垂降低HS后的肺通透性；6)TLR4上调的TLR2信号增强HS诱导的肺内皮细胞下垂。这些结果表明，肺内皮细胞下垂在HS后ALI的发生发展中起着新的重要作用。根据我们的研究结果，我们推测：1)HS通过危险分子激活炎性小体和/或嗜热体，从而诱导肺内皮细胞下垂；2)肺内皮细胞下垂在HS后ALI的发生发展中起重要作用；3)TLR4和TLR2之间的相互作用是介导HS诱导的EC下垂的重要机制。我们提出了三个特定的目标来验证我们的假设：目的1.确定HS诱导肺和肺内皮细胞下垂的机制；目的2.确定内皮细胞下垂在HS后ALI发生中的作用；以及目的3.确定HS诱导的肺和肺内皮细胞下垂对TLR2配体的反应机制。

 DESCRIPTION (provided by applicant): The burden of trauma-related diseases is considerable. Following exsanguination and/or brain injury that commonly result in early phase death, more than 60% of surviving patients later die of causes related to the development of systemic inflammatory response syndrome (SIRS) and acute lung injury (ALI). This patient population is well suited for prophylactic interventions aimed at preventing these occurrences because of the time lag before the onset of organ inflammation and failure. Nonetheless, few specific targets have been identified that predispose to SIRS and ALI. Since endothelial cells (ECs) play important and broad roles in hemorrhagic shock (HS)-induced inflammation, and programed EC death significantly influence the progress of inflammation, an insight of the mechanism of HS-induced EC pyroptosis, a caspase-1-dependent programmed cell death, will provide us novel potential therapeutic targets for post-HS SIRS and ALI. In a broader sense, the proposed studies will contribute to a greater understanding of the pathogenesis of a number of human inflammatory diseases in which endothelium is involved in the inflammatory process. Pyroptosis is a recently identified host cell death that is stimulated by a range of microbial infections and non-infectious stimuli, including stroke, heart attack, or cancer. Pyroptosis features rapid plasma-membrane rupture and release of proinflammatory intracellular contents. Our published and preliminary findings demonstrate an important role for pyroptosis in the development of inflammation following HS. We observed that: 1) HS induces lung EC pyroptosis following inflammasome activation, and this induction requires HMGB1- TLR4 signaling; 2) Lung EC pyroptosis results in pro-inflammatory cytokines release from the ECs and induces cytokines expression in alveolar macrophages; 3) Pyroptotic ECs increase polymorphonuclear neutrophils (PMN) adhesion to the ECs; 4) Pyroptotic ECs increases endothelial permeability; 5) Prevention of HS-induced EC pyroptosis by EC-specific TLR4 knockout reduces lung permeability following HS; and 6) TLR4- upregulated TLR2 signaling augments HS-induced lung EC pyroptosis. These results suggest a novel and important role of lung EC pyroptosis in the development of post-HS ALI. Based on our findings, we hypothesize that: 1) HS through danger molecules activates inflammasome and/or pyroptosome, and thereby induces lung EC pyroptosis; 2) Lung EC pyroptosis serves an important role in the development of ALI after HS; and 3) Interactions between TLR4 and TLR2 serve as an important mechanism mediating HS-primed EC pyroptosis. We propose three specific aims to test our hypotheses: Aim 1. To determine the mechanism by which HS induces pyroptosis in the lung and lung EC; Aim 2. To determine the role of EC pyroptosis in the development of ALI following HS; and Aim 3. To determine the mechanisms of HS-primed induction of pyroptosis in the lung and lung EC in response to TLR2 ligands.