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

描述（由申请人提供）： 严重的创伤和出血使患者更容易受到第二种炎症刺激，即所谓的“两次打击”模型。创伤后炎症可导致严重的多器官功能衰竭（MOF）和死亡。研究表明，由第一次撞击引起的细胞引发是细胞对第二次撞击的反应增强的机制。急性肺损伤（AL 1）是MOF的重要组成部分，并且经常充当死亡的直接原因。多形核中性粒细胞（PMN）在肺血管系统、肺泡和肺泡腔中的积聚被认为是ALI的关键事件，并且一直是各种预防策略的目标。然而，导致PMN迁移的机制仍不清楚。内皮细胞通过表达细胞因子、趋化因子和粘附分子直接与中性粒细胞相互作用，在启动中性粒细胞迁移中起关键作用。我们已经报道了内皮细胞表达低水平的Toll样受体（TLR）2，其是多种微生物产物的受体，UPS可以通过TLR 4信号转导上调其表达，这表明诱导细胞对感染敏感性的受体串扰机制。我们进一步表明，氧化剂放大LPS诱导的TLR 2在内皮细胞中的表达，并且在功能上与响应于TLR 2激动剂的ICAM-1表达增加和PMN迁移增强相关。基于这些发现，我们假设：（I）肺内皮细胞引发负责增强创伤后PMN在肺中的迁移，（II）TLR 2上调通过增加细胞对病原体的易感性在内皮细胞引发中起作用，以及（III）出血/复苏诱导的氧化剂产生有助于增强内皮细胞中TLR 2上调。我们将在三个相互关联的目的中追求这些假设：1）确定失血性休克对肺和肺内皮细胞中LPS/TLR 4调节TLR 2的作用; 2）确定TLR 2在失血性休克诱导的内皮细胞引发中的作用;和3）确定TLR 2在失血性休克后引发肺部炎症中的作用。我们将使用体内，体外和体外模型，以充分解决TLR 2在休克诱导的细胞引发和肺损伤的作用。从这些研究中获得的见解应显着提高我们对创伤后MOF细胞启动的理解。

DESCRIPTION (provided by applicant): Severe trauma and hemorrhage renders the patient more susceptible to a second inflammatory stimulus, the so-called "two-hit" model. The post-trauma inflammation can lead to severe multi-organ failure (MOF) and death. Studies have suggested that cell priming caused by a first hit is the mechanism for enhanced response of the cell to a second hit. Acute lung injury (ALl) is an important part of the MOF, and often serves as a direct cause of death. The accumulation of polymorphonuclear neutrophils (PMN) in the lung vasculature, interstitium, and alveolar space is considered a critical event in ALI and has been the target of various preventative strategies. However, the mechanisms that prime PMN migration remain unclear. Endothelial cells play a critical role in initiating PMN migration through directly interacting with PMN by expression of cytokines, chemokines, and adhesion molecules. We have reported that endothelial cells express a low level of Toll-like receptor (TLR) 2, the receptor for a variety of microbial products, which could be up-regulated by UPS through TLR4 signaling, suggesting a receptor cross-talk mechanism of inducible cell sensitivity to infection. We have further shown that oxidants amplify LPS-induced TLR2 expression in endothelial cells and which are functionally associated with an increased ICAM-1 expression and enhanced PMN migration in response to TLR2 agonist. Based on the findings we hypothesize that: (I) pulmonary endothelial cell priming is responsible for the enhanced post-trauma PMN migration in the lungs, (II) TLR2 up-regulation serves a role in the endothelial cell priming through increasing cell susceptibility to pathogens, and (III) hemorrhage/ resuscitation-induced generation of oxidants contributes to enhanced TLR2 upregulation in the endothelial cells. We will pursue these hypotheses in three interrelated Aims: 1) to determine the effect of hemorrhagic shock on LPS/TLR4 regulation of TLR2 in the lung and pulmonary endothelial cells; 2) to determine the role of TLR2 in hemorrhagic shock-induced endothelial cell priming; and 3) to determine the role of TLR2 in priming for lung inflammation following hemorrhage shock. We will use in vivo, ex vivo, and in vitro models to fully address the role of TLR2 in shock-induced cell priming and lung injury. Insights gained from these studies should significantly enhance our understanding of cell priming in post-trauma MOF.