NQO1: Linking Oxidant Stress to Inflammation in Airway Epithelial Cells

描述（由申请人提供）：个体对臭氧的反应差异很大，有些个体对肺毒性的臭氧敏感性阈值要低得多。因此，一个复杂的个体遗传因素可能控制臭氧暴露后氧化信号的传递和传播。流行病学研究支持野生型NADPH醌氧化还原酶1 （NQO1）基因型在臭氧存在下作为哮喘易感因子的作用。NQO1催化醌的专性2电子还原，被认为是细胞内抗氧化剂。我们的初步数据表明，NQO1是臭氧诱导小鼠IL-8/ KC表达、中性粒细胞性气道炎症增加和气道高反应性所必需的。这就提出了一个难题来解释氧化还原酶如何循环抗氧化剂传播ROS信号，将氧化应激与炎症反应联系起来。我们将使用原代人气道上皮细胞和小鼠（野生型和NQO1-null）模型系统来测试以下前所未有的假设机制，以解释NQO1如何将氧化应激与上皮炎症联系起来：NQO1和臭氧生成的ROS是臭氧暴露后气道炎症的主要调节剂。我们提出NQO1调节细胞内氧化还原环境，导致异前列腺素（isoP）平衡的改变。在NQO1存在的情况下，ROS和F2-isoP激活NF-(B)，导致IL-8/ KC表达增加，中性粒细胞炎症增加。在缺乏NQO1的情况下，细胞有利于A2-isoP的产生，从而抑制NF-(B)的激活，从而导致阻断IL-8/ KC表达和中性粒细胞炎症的矛盾效应。目的1a：确定臭氧暴露后，NQO1是否通过上调中性粒细胞趋化因子KC/ IL-8介导中性粒细胞炎症和气道高反应性。目的1b：确定肺对臭氧的反应是否需要NQO1在气道结构上皮细胞和/或造血细胞中的表达。目的2a：确定NQO1是否改变细胞氧化还原状态，诱导一个相对还原环境，由还原：氧化-生育酚、还原：氧化泛醌和还原：氧化谷胱甘肽的水平决定。目的2b：确定在臭氧暴露后，NQO1是否会导致异前列腺素产生的变化，导致F2- isoP形成的相对增加，相反，体内NQO1的损失会导致A2-isoP形成的增加。目的3a：确定臭氧暴露后，F2-isoP和/或臭氧生成的ROS是否通过NF-(B)激活上调IL-8/KC表达。目的3b：通过A2-isoP抑制I(B)中NF-(B)的释放，确定在缺乏NQO1的情况下，这种调节是否被取消。

DESCRIPTION (provided by applicant): Individual responses to ozone vary widely with some individuals having a much lower threshold of ozone sensitivity for pulmonary toxicity. Therefore, a complex of individual genetic factors likely controls the transmission and propagation of oxidant signaling following ozone exposure. Epidemiologic studies support the role of the wild-type NADPH quinone oxidoreductase1 (NQO1) genotype as an asthma susceptibility factor in the presence of ozone. NQO1 catalyzes the obligate 2-electron reduction of quinones and is considered an intracellular antioxidant. Our preliminary data demonstrate that NQO1 is required for ozone-induced IL-8/ KC expression, increased neutrophilic airway inflammation, and airway hyperresponsiveness in mice. This poses a conundrum to explain how an oxidoreductase that recycles antioxidants propagates ROS signaling linking oxidant stress to an inflammatory response. We will use primary human airway epithelial cells and mouse (wild-type and NQO1-null) model systems to test the following unprecedented hypothetical mechanism to explain how NQO1 links oxidant stress to epithelial inflammation: NQO1 and ozone-generated ROS are central regulators of airway inflammation following ozone exposure. We propose that NQO1 regulates the intracellular redox environment resulting in a shift in the balance of isoprostanes (isoP). In the presence of NQO1, ROS and F2-isoP activate NF-(B, resulting in increased IL-8/ KC expression and increased neutrophilic inflammation. In the absence of NQO1, the cell favors A2-isoP production, which inhibits NF-(B activation, causing the paradoxical effect of blocking IL-8/ KC expression and neutrophilic inflammation. The specific aims are: Aim 1a: To determine whether following ozone exposure, NQO1 mediates neutrophilic inflammation and airway hyperresponsiveness via upregulation of the neutrophil chemokines KC/ IL-8. Aim 1b: To determine whether NQO1 expression in structural airway epithelial cells and/or in hematopoetic cells is required for pulmonary responses to ozone. Aim 2a: To determine whether NQO1 alters the cellular redox state, inducing a relative reducing environment as determined by levels of reduced: oxidized (-tocopherol, reduced: oxidized ubiquinone and reduced: oxidized glutathione. Aim 2b: To determine whether following ozone exposure, NQO1 causes a shift in isoprostane production with a relative increase in F2- isoP formation and conversely, a loss of NQO1 in vivo, causes increased formation of A2-isoP. Aim 3a: To determine whether following ozone exposure, F2-isoP and/or ozone-generated ROS upregulate IL-8/KC expression by NF-(B activation. Aim 3b: To determine whether this regulation is abrogated in the absence of NQO1 by A2-isoP inhibition of NF-(B release from I(B.