Sphingosine 1-phosphate and PMN Ca2+ entry in trauma

描述（由申请人提供）：在现代武装冲突以及几乎所有恐怖袭击中，创伤是造成死亡和残疾的主要原因。不太为人所知的是，创伤是45岁以下平民死亡的最常见原因。从出生到36岁，创伤超过了所有其他死因的总和。许多患者在受伤后幸存下来，但却遭受了长期的危重疾病，或后来因创伤和休克引发中性粒细胞（PMN）炎症和功能障碍导致器官衰竭或败血症而死亡。因此，pmn介导的休克后炎症是一个关键的国防和公共卫生问题。在我们最后的资助支持期间，我们发现创伤后的炎症反映了钙离子（Ca2+）从环境进入PMN的异常调节。这些途径部分依赖于激动剂引发的细胞Ca2+储存的排空，因此通常被称为储存操作钙进入（SOCE）。我们进一步表明，在PMN中，SOCE是由响应Ca2+储存排空的脂质第二信使鞘氨醇1-磷酸（S1P）的细胞合成介导的。相关脂质也有类似的作用，可以刺激细胞内或细胞外的PMN活化。我们还证明，PMN SOCE通过由“瞬时受体电位”通道蛋白（TRPC）组成的Ca2+进入通道的复杂系统发生。由于SOCE是PMN Ca2+的关键调节因子，并且在损伤后的PMN中受到异常调节，这些发现提出了一种假设，即S1P合成和SOCE特异性Ca2+通道的药理学调节可能会预防PMN介导的休克和创伤的炎症后遗症。进一步的研究表明，在模拟临床相关创伤和休克治疗场景的复杂动物模型中，通过多种策略抑制SOCE可以减少pmn介导的炎症和肺损伤。目前的提案旨在扩展我们之前的工作，从我们之前的基本分子生物学观察的临床应用阶段，到一个易于理解的治疗策略阶段，为战场和平民创伤实践的临床实施做好准备。为此，我们提出实现以下四个具体目标：确定如何利用SOCE抑制预防外伤性休克后器官损伤2。确定休克后SOCE抑制的副作用和并发症。3. 确定损伤对细胞内S1P/SOCE信号的影响确定创伤后循环S1P激活PMN的机制。

DESCRIPTION (provided by applicant): Trauma is the major cause of death and disability in modern armed conflict as well as in almost every terrorist attack. Less well known, trauma is the most common cause of civilian death below age 45. Between birth and age 36, trauma exceeds all other causes of death combined. Many patients survive injury initially only to suffer prolonged critical illness or die later when trauma and shock trigger neutrophil (PMN) inflammation and dysfunction that leads to organ failure or sepsis. Thus PMN-mediated inflammation after shock is a key national defense as well as public health problem. During our last grant support period, we showed that inflammation after trauma reflects aberrant regulation of calcium ion (Ca2+) entry from the environment into PMN. These pathways depend in part on the agonist-initiated emptying of cell Ca2+ stores and are therefore generally termed store-operated calcium entry (SOCE). We further showed that in PMN, SOCE is mediated by cellular synthesis of a lipid second messenger, sphingosine 1-phosphate (S1P) in response to Ca2+ store emptying. Related lipids act similarly, and can stimulate PMN activation whether produced intra- or extra-cellular. We have also demonstrated that PMN SOCE occurs through a complex system of Ca2+ entry channels which are composed of "Transient Receptor Potential" channel proteins (TRPC). Since SOCE is a key regulator of PMN Ca2+ and is abnormally regulated in PMN after injury, these findings suggested the hypothesis that pharmacologic modulation of both S1P synthesis and SOCE-specific Ca2+ channels might prevent PMN-mediated inflammatory sequellae of shock and trauma. Further work has now shown that inhibition of SOCE by a variety of strategies can act to diminish PMN-mediated inflammation and lung injury in complex animal models mimicking clinically relevant trauma and shock treatment scenarios. The present proposal seeks to extend our prior work from the stage of a clinical promising application of our prior basic molecular biologic observations, to the stage of a well-understood treatment strategy ready for clinical implementation both on the battlefield and in civilian trauma practice. We propose to do this by achieving the four following Specific Aims: 1. Determine how to use SOCE inhibition to prevent organ injury after traumatic shock 2. Determine the side effects and complications of SOCE inhibition after shock. 3. Determine the effects of injury on intracellular S1P/SOCE signaling 4. Determine the mechanisms by which circulating S1P activates PMN after trauma.