Chlorinated lipids in sepsis

 描述(申请人提供)：败血症是成人和儿童发病和死亡的主要原因，据估计，美国每年有75万例败血症。为了改善这些患者的预后，增加我们对疾病病理生理学的理解并确定新的治疗靶点是至关重要的。当受到严格控制的宿主对感染的反应超出局部环境并进入体循环时，就会发生败血症。这导致了复杂的相互作用，涉及微生物、血细胞和 微循环中的内皮屏障，可进展为血管衰竭和器官衰竭。中性粒细胞是感染的关键早期反应者。中性粒细胞通过吞噬和氧化剂介导的微生物杀死周围环境中的微生物。髓过氧化物酶(MPO)是氧依赖性杀菌活性的主要介体。MPO催化过氧化氢转化为强氧化剂次氯酸(HOCl)，次氯酸与微生物和宿主分子靶标包括蛋白质和脂质发生反应。圣路易斯大学(SLU)的Ford小组使用生理、生化和生物有机方法证明，血浆原脂质sn-1位的乙烯基醚键是HOCl的靶标，导致2-氯脂肪醛的产生，在生理和病理生理条件下，2-氯脂肪醛被代谢成2-氯脂肪酸。这些氯化脂质在激活的中性粒细胞以及体内炎症模型中都会升高，这些炎症模型包括内毒素治疗、信代病毒暴露和腹膜炎。初步研究表明，与对照组相比，脓毒症大鼠模型和脓毒症患者的人类血浆中氯化脂质水平升高。更多的初步数据提供了强有力的证据，表明氯化脂质在微循环和分离细胞系统中调节白细胞、血小板和内皮细胞的功能。因此，我们组建了一个由三个PI组成的多学科小组来验证我们的假设，即脓毒症期间激活的白细胞产生的氯化脂质是导致多器官衰竭的严重内皮功能障碍的介质。这一假设将通过三个具体目标进行检验。具体目标1将验证中性粒细胞产生的氯化脂质是脓毒症期间内皮功能障碍和器官损害的关键介质的假设。《特定目标2》将检验氯化脂质介导人类内皮细胞功能障碍的假设。具体目标3将检验这一假设，即血浆2-ClFA水平表明脓毒症患者的严重程度和治疗效果。总体而言，多学科方法将检查由于白细胞产生的氯化脂质的作用。 脓毒症期间的激活作为人类脓毒症严重程度的指示器，以及血管内皮功能障碍的介体，在体内和体外进行了大鼠微循环和体外机制的研究。该项目具有创新性和重大意义。这些研究旨在发现中性粒细胞在引发内皮功能障碍中的作用的新范例，为治疗败血症患者提供新的靶点。

 DESCRIPTION (provided by applicant): Sepsis is a major cause of morbidity and mortality in both adults and children with an estimated 750,000 cases per year in the United States. To improve outcomes in these patients, it is vital to increase our understanding of the pathophysiology of the disease and identify new therapeutic targets. Sepsis occurs when the tightly controlled host response to infection extends beyond the local environment and into the systemic circulation. This results in complex interactions involving microbes, blood cells, and the endothelial barrier in the microcirculation that can progress to vascular collapse and organ failure. Neutrophils are key early responders to infection. Neutrophils kill microbes by phagocytosis and by oxidant-mediated microbe killing in the surrounding environment. Myeloperoxidase (MPO) is a major mediator of oxygen-dependent microbicidal activity. MPO catalyzes the conversion of H2O2 to the potent oxidant, hypochlorous acid (HOCl), which reacts with both microbial and host molecular targets including proteins and lipids. The Ford group at Saint Louis University (SLU) has used physiological, biochemical and bio-organic approaches to demonstrate that the vinyl ether bond at the sn-1 position of plasmalogen lipids is targeted by HOCl, resulting in the production of 2-chlorofatty aldehyde, which is metabolized to 2-chlorofatty acid under physiological and pathophysiological conditions. These chlorinated lipids are elevated in activated neutrophils as well as in in vivo inflammation models including LPS treatment, Sindai virus exposure and peritonitis. Pilot studies show elevated levels of chlorinated lipids in a rat model of sepsis, and in human plasma of sepsis patients compared to controls. Additional preliminary data provide strong evidence that chlorinated lipids modulate leukocyte, platelet and endothelial cell function in the microcirculation and in isolated cell systems. Accordingly, we have assembled a multidisciplinary group with three PIs to test our hypothesis that chlorinated lipids produced by activated leukocytes during sepsis are mediators of severe endothelial dysfunction resulting in multiple organ failure. This hypothesis will be tested by three specific aims. Specific Aim 1 will test the hypothesis that chlorinated lipids produced by neutrophils are key mediators of endothelial dysfunction and organ damage during sepsis. Specific Aim 2 will test the hypothesis that chlorinated lipids mediate dysfunction in human endothelial cells. Specific Aim 3 will test the hypothesis that plasma 2-ClFA levels indicate both severity and therapeutic effectiveness in sepsis patients. Overall, a multi-disciplinary approach will examine the role of chlorinated lipids produced as a result of leukocyte activation during sepsis as indicators of the severity of human sepsis, and mediators of vascular endothelial dysfunction examined both in vivo in the rat microcirculation and in vitro for mechanistic insights. The project is innovative and significant. These studies are designed to discover new paradigms for the role of neutrophils in eliciting endothelial dysfunction providing new targets for therapeutics to treat septic patients.