Adenosine and Lung Endothelial Injury

项目总结(见说明)： 脓毒症所致急性肺损伤(ALI)时血浆腺苷升高。腺苷脱氨酶(ADA-/-)小鼠体内腺苷持续升高导致通透性肺水肿增加。吸烟是ALI的一个危险因素，暴露于香烟烟雾(CS)会降低大鼠和人类的ADA活性。基本假设是，长期暴露在腺苷增加的环境中会增加肺血管的通透性。长期目标是开发新的治疗方法来预防/治疗与持续增加的腺苷和CS暴露相关的肺部疾病。这项建议的总体目标是通过体内和体外方法阐明腺苷长期暴露对肺内皮细胞(EC)屏障功能有害影响的机制。初步研究表明，亚急性CS暴露可增加肺腺苷含量，加重肺水肿，长时间暴露于升高的腺苷可通过依赖转运体(Enti)而非受体介导的线粒体氧化应激和p38激活导致肺内皮细胞屏障功能障碍。我推测，持续暴露于升高的腺苷导致EC屏障功能障碍，通过依赖ENT1的摄取和线粒体氧化应激介导的p38激活，导致肺水肿。具体目标1将确定ENT1和氧化应激在多大程度上介导了腺苷诱导的动物模型中持续升高的肺水肿。目的2明确腺苷持续暴露对培养的肺微血管内皮细胞(LMVEC)屏障功能损害的机制。我预计，持续暴露于升高的腺苷会导致ENT1介导的EC屏障功能破坏和肺水肿，CS会增加腺苷，类似地破坏EC屏障功能。该方法具有创新性，因为它使用ADA缺乏作为腺苷持续升高的模型和CS引发ALI的新模型。这些研究将阐明细胞内摄取腺苷所介导的腺苷效应的新途径。抑制ENT1促进的腺苷转运和下游信号传导可能为治疗与持续升高的腺苷和CS暴露相关的疾病提供重要和迫切需要的新方法。

PROJECT SUMMARY (See instructions): Plasma adenosine is increased in sepsis-induced acute lung injury (ALI). Sustained elevation of adenosine in adenosine deaminase (ADA-/-) mice causes increased permeability lung edema. ADA activity is decreased in rats and humans by cigarette smoke (CS) exposure, a risk< factor of ALI. The fundamental hypothesis is that prolonged exposure to increased adenosine increases lung vascular permeability. The long-range goal is to develop novel therapeutic approaches to prevent/treat lung diseases associated with sustained increased adenosine and CS exposure. The overall objective of this proposal is to elucidate the mechanisms of deleterious effects of prolonged adenosine exposure on lung endothelial (EC) barrier function using in vivo and in vitro approaches. Preliminary studies show that subacute CS exposure elevates lung adenosine and worsens lung edema and that prolonged exposure to elevated adenosine causes lung EC barrier dysfunction via transporter (ENTI)-dependent, not receptor-mediated, mitochondrial oxidative stress and p38 activation. I hypothesize that sustained exposure to elevated adenosine causes EC barrier dysfunction, leading to lung edema, via ENT1-dependent uptake and mitochondrial oxidative stress mediated p38 activation. Specific Aim 1 will determine the extent to which ENT1 and oxidative stress mediate sustained elevated adenosine-induced lung edema in animal models. Specific Aim 2 will identify the mechanism of deleterious effects of sustained exposure to elevated adenosine on barrier function in cultured lung microvascular endothelial cells (LMVEC). I anticipate that sustained exposure to elevated adenosine causes ENT1-mediated disruption of EC barrier function and lung edema and that CS increases adenosine and similarly disrupts EC barrier function. The approach is innovative since it uses ADA deficiency as a model for sustained adenosine elevation and a novel model of CS priming ALI. These studies will elucidate a novel pathway for adenosine effects mediated by intracellular uptake of adenosine. Inhibition of ENT1- facilitated adenosine transport and downstream signaling may likely provide significant and greatly needed new approaches to treat diseases associated with sustained elevated adenosine and CS exposure.