Platelet Activating Factor and Epidermal Cytoxicity

酒精的使用可能是全世界发病率和死亡率的重要来源。众所周知，有一半的人 有严重烧伤需要住院的患者乙醇(Etoh)检测呈阳性。从统计上讲， 这些人中的大多数都是偶尔酗酒的人，而不是酗酒者。受伤时使用乙醇 还导致烧伤患者的发病率和死亡率增加(&gt；2倍)。经过验证的小鼠模型 合并无水乙醇+热烧伤显示出大量急性全身细胞因子的释放和毒性 这些联合药物涉及肺、小肠和肝脏，这模拟了人类的病理。这个过程 无水乙醇如何增加热烧伤损伤介导的毒性尚不清楚，但我们已经证明 1-烷基-2-乙酰基-1-烷基-2-乙酰基-脂质介导的血小板活化因子的新作用机制 甘油磷胆碱；PAF)。这项提议是对一项长期赠款的续签，这项赠款有助于 描述PAF的影响，侧重于皮肤的病理生理学。通过一种特定的G蛋白偶联发挥作用 受体(PAFR)广泛表达，急性PAF暴露会导致全身促炎反应， 模仿感染性休克。我们在这笔赠款的最后一个周期中完成的正在进行的和已发表的研究有 发现急性暴露的角质形成细胞在体外或体内与无水乙醇接触后发生热烧伤 结果由胞浆磷脂酶A2(CPLA2)介导的PAF产量显著增加 激活。重要的是，PAFR KO小鼠完全免受醉酒热烧伤的伤害- 诱发多脏器炎症。此外，我们还发现PAF通过亚细胞离开角质形成细胞。 微泡颗粒(MVP)在依赖于PAFR激活和酶酸化的过程中 鞘磷脂酶(ASMase)。我们假设，在MVP中旅行可以保护PAF免受PAF的降解- 乙酰水解酶，并以最佳形式向PAFR提供脂质配体。规划的总体目标 这次更新的研究是为了解决PAF填充的MVP是如何产生的以及它们到底是如何产生的知识空白 产生广泛的多器官全身炎症反应，以应对EtoH+热烧伤。 有三个目的是为了验证这样一个假设，即急性乙醇暴露绕过了严格调控的PAF 合成和降解途径导致热烧伤反应中PAF的过度产生， PAFR的激活通过aSMase产生充满PAF的MVP。填充PAF的Burn-MVP系统旅行 诱导肠道细菌移位，导致“感染性休克”。第一个目标将定义乙醇的机制-- 介导的MVP和PAF产量的增加。第二个目标将定义MVP是否用于保护PAF 防止降解，并通过提供嵌入在膜中的配体来增加PAF的效力。第三个目标 将确定烧伤MVP中PAF产生全身毒性的确切机制。这一目标将建立在 我们的机制研究，以测试可能的治疗策略的中毒性热烧伤。这些研究 将解决知识差距，并为环境伤害产生新的治疗方法。

Ethanol use can be an important source of morbidity and mortality worldwide. It is known that half of individuals with significant burn injuries necessitating hospitalization were positive for ethanol (EtOH). Statistically speaking, the majority of these individuals were occasional binge drinkers, not alcoholics. Ethanol use at the time of injury also results in increased morbidity and mortality (> 2-fold) in the burned patients. Validated murine models combining EtOH + thermal burn injury have demonstrated massive acute systemic cytokine release with toxicity of these combined agents involving lung, small intestine and liver, which mimics human pathology. The process by which EtOH augments thermal burn injury-mediated toxicity has been unknown, yet, we have demonstrated a novel mechanism involving the lipid mediator Platelet-activating Factor (1-alkyl-2-acetyl glycerophosphocholine; PAF). This proposal is the renewal of a long-standing grant that has served to characterize PAF effects, focusing on skin pathophysiology. Exerting its effects via a specific G-protein coupled receptor (PAFR) widely expressed, acute PAF exposure results in a systemic pro-inflammatory response that mimics septic shock. Our ongoing and published studies accomplished in the last cycle of this grant have discovered that acute exposure of keratinocytes in vitro or mice in vivo with EtOH followed by thermal burn injury results in a tremendous increase in PAF production, mediated by augmented cytosolic phospholipase A2 (cPLA2) activation. Of importance, PAFR KO mice were completely protected from intoxicated thermal burn injury- induced multi-organ inflammation. Moreover, we discovered that PAF leaves the keratinocyte via subcellular microvesicle particles (MVP) in a process dependent upon PAFR activation and the enzyme acid sphingomyelinase (aSMase). We hypothesize that traveling in MVP protects PAF from degradation from PAF- acetyl hydrolases, and provides the lipid ligand to the PAFR in optimal form. The overall objective of the planned studies in this renewal is to address knowledge gaps in how PAF-filled MVPs are produced and exactly how they generate widespread multi-organ systemic inflammation in response to combining EtOH + thermal burn injury. Three aims are designed to test the hypothesis that acute EtOH exposure bypasses the tightly regulated PAF synthetic and degradation pathways resulting in exaggerated PAF production in response to thermal burn injury, and that PAFR activation generates PAF-filled MVP via aSMase. The PAF-filled Burn-MVP travel systemically to induce gut bacterial translocation resulting in “septic shock”. The first aim will define the mechanisms for EtOH- mediated augmentation of MVP and PAF production. The second aim will define if MVP serve to protect PAF from degradation and increases PAF's potency by providing the ligand embedded in membrane. The third aim will define the exact mechanisms by which PAF in Burn-MVP generate systemic toxicity. This aim will build upon our mechanistic studies to test potential treatment strategies for intoxicated thermal burn injury. These studies will address knowledge gaps and generate new therapeutic approaches for environmental injuries.