ROLE OF SIRTUIN IN CIGARETTE SMOKE-INDUCED LUNG INFLAMMATION AND INJURY

描述(申请人提供)：慢性阻塞性肺疾病(COPD)是美国慢性发病率和死亡率的第四大原因，估计有2300万人受到影响。慢性阻塞性肺病(肺气肿和慢性支气管炎)与过早衰老(肺功能加速下降)和慢性肺部炎症有关，这是由于吸入香烟烟雾衍生的氧化剂和自由基导致的，这些都与衰老、衰老、癌症和炎症过程有关。然而，人们对香烟烟雾(CS)引发异常和持续的肺部炎症和损伤的分子机制知之甚少。NAD+依赖的蛋白脱乙酰酶(Sirtuins)最近被认为是衰老(细胞凋亡/衰老)、慢性炎症性疾病和癌症的重要调节因子。酵母Sir2(ySir2，酵母沉默信息调节因子2)，相当于人类Sirtuin1(SIRT1)，是通过组蛋白和非组蛋白去乙酰化维持沉默染色质所必需的。我们发现，CS暴露后，巨噬细胞、小鼠肺和COPD患者肺组织中SIRT1水平显著降低，并与NF-B激活和促炎介质释放增加有关。同样，SIRT1缺陷小鼠表现出与中性粒细胞流入增加相关的NF-B和促炎细胞因子的夸大水平，而暴露于CS的SIRT1转基因小鼠的这些反应在肺中减弱。我们的初步数据还显示，SIRT1-/-小鼠更容易因接触CS而患上肺气肿。我们推测SIRT1是一种新的下调CS诱导的肺炎症和损伤(肺气肿)的新的下调因子，因为它影响了核因子-B、组蛋白乙酰化和细胞凋亡/细胞衰老。我们建议在体外通过单核/巨噬细胞(肺部炎症反应的主要协调者和放大器)和体内暴露于CS的小鼠肺来验证这一假说。我们建议：目的1：确定CS暴露导致巨噬细胞和小鼠肺中SIRT1减少的机制；目的2：确定SIRT1调节巨噬细胞和小鼠肺中对CS的炎症反应的机制；以及目标3：确定SIRT1基因缺失和获得在体内对CS介导的肺部炎症/损伤和肺气肿(肺气肿)的影响及其机制。这些研究旨在确定CS改变SIRT1导致异常肺部炎症的调节机制，并确定SIRT1在CS诱导组蛋白乙酰化、细胞凋亡/衰老和肺泡扩大中的作用。该提案中概述的实验还将确定SIRT1途径中的关键细胞内信号事件，并将使我们能够确定CS介导的异常肺部炎症和气道损伤在COPD发病机制中的治疗靶点。这些研究具有很高的翻译潜力，因为SIRT1与控制衰老、衰老和炎症有关。 与公共卫生相关：慢性阻塞性肺病是美国慢性疾病发病率和死亡率的第四大原因；因此，它是一个主要的公共卫生问题。慢性阻塞性肺疾病与肺部的过早衰老有关，这是由于吸烟产生的自由基和肺部的炎症过程造成的。我们的研究将确定sirtuin 1(一种抗衰老和抗炎蛋白)途径中的关键细胞内分子事件，这将使我们能够确定COPD-肺气肿和其他与吸烟有关的慢性炎症性疾病的治疗靶点。

DESCRIPTION (provided by applicant): Chronic Obstructive Pulmonary Disease (COPD) is the fourth leading cause of chronic morbidity and mortality in the United States, affecting an estimated 23 million people. COPD (emphysema and chronic bronchitis) is linked with premature aging (accelerated decline in lung function) and chronic inflammation of the lungs due to inhaled cigarette smoke-derived oxidants and free radicals which are implicated in aging, senescence, cancer and inflammatory processes. However, very little is known about the molecular mechanisms whereby cigarette smoke (CS) triggers abnormal and sustained lung inflammation and injury. The NAD+dependent protein deacetylases (sirtuins) have recently emerged as important regulators of aging (apoptosis/senescence), chronic inflammatory diseases and cancer. The founding member yeast Sir2 (ySir2, yeast silent information regulator 2) which is equivalent to human sirtuin1 (SIRT1) is essential for maintaining silent chromatin via the deacetylation of histones and non-histone proteins. We have found that SIRT1 levels are drastically reduced in response to CS exposure in macrophages, mouse lung, and in lungs of patients with COPD, and are associated with increased NF-(B activation and release of pro-inflammatory mediators. Similarly, SIRT1-deficient mice exhibited exaggerated levels of NF-(B and proinflammatory cytokines associated with increased influx of neutrophils, whereas these responses were attenuated in lungs of SIRT1 transgenic mice exposed to CS. Our preliminary data also show that SIRT1-/- mice are more prone to develop emphysema in response to CS exposure. We hypothesize that SIRT1 is a novel down-regulator of CS-induced lung inflammation and injury (emphysema) due to its effects on NF-(B, histone acetylation and apoptosis/cell senescence. We propose to test this hypothesis in vitro in monocytes/macrophages (the main orchestrators and amplifiers of the lung inflammatory response) and in vivo in mouse lungs exposed to CS. We propose to: Aim 1: determine the mechanisms by which CS exposure results in reduction of SIRT1 in macrophages and in mouse lungs; Aim 2: determine the mechanisms whereby SIRT1 regulates the inflammatory response to CS in macrophages and in mouse lungs; and Aim 3: determine the effects of genetic loss and gain of SIRT1 on CS-mediated lung inflammation/injury and airspace enlargement (emphysema) in vivo, and the mechanisms involved. These studies are designed to identify the regulatory mechanism of SIRT1 that is altered by CS leading to abnormal lung inflammation, and to determine the role of SIRT1 in CS-induced acetylation of histone proteins, apoptosis/senescence and airspace enlargement. The experiments outlined in this proposal will also identify key intracellular signaling events in the SIRT1 pathway and will allow us to identify therapeutic targets for CS-mediated abnormal lung inflammation and airway injury in pathogenesis of COPD. These studies have high translational potential as SIRT1 is implicated in control of aging, senescence and inflammation. PUBLIC HEALTH RELEVANCE: COPD is the fourth leading cause of chronic morbidity and mortality in the United States; hence it is a major public health concern. COPD is linked with the premature aging of the lungs due to cigarette smoke-derived free radicals and inflammatory processes in the lung. Our research will identify the key intracellular molecular events in the sirtuin 1 (an anti-aging and anti-inflammatory protein) pathway which will allow us to identify therapeutic targets for COPD-emphysema and other chronic inflammatory diseases linked to smoking.