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

描述（由申请人提供）：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，影响约2300万人。慢性阻塞性肺病（肺气肿和慢性支气管炎）与早衰（肺功能加速下降）和肺部慢性炎症有关，这是由于吸入香烟烟雾衍生的氧化剂和自由基导致的，这些氧化剂和自由基与衰老、衰老、癌症和炎症过程有关。然而，关于香烟烟雾（CS）引发异常和持续肺部炎症和损伤的分子机制知之甚少。NAD+依赖性蛋白去乙酰化酶（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。创始成员酵母Sir2 （ySir2，酵母沉默信息调节因子2）相当于人类sirtuin1 (SIRT1)，通过组蛋白和非组蛋白的去乙酰化来维持沉默染色质。我们发现巨噬细胞、小鼠肺和COPD患者肺中SIRT1水平在CS暴露后急剧降低，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NF-(B)和促炎细胞因子水平升高，与中性粒细胞内流增加相关，而暴露于CS的SIRT1转基因小鼠的肺部这些反应减弱。我们的初步数据还显示SIRT1-/-小鼠在CS暴露后更容易发生肺气肿。我们假设SIRT1是cs诱导的肺部炎症和损伤（肺气肿）的一种新的下调因子，这是由于它对NF- B、组蛋白乙酰化和细胞凋亡/细胞衰老的影响。我们建议在体外单核细胞/巨噬细胞（肺炎症反应的主要协调者和放大器）和体内暴露于CS的小鼠肺中验证这一假设。我们提出：目标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CS炎症反应的机制；目的3：确定SIRT1基因缺失和获得对体内cs介导的肺部炎症/损伤和空气空间扩大（肺气肿）的影响及其机制。这些研究旨在确定CS改变SIRT1导致肺部异常炎症的调控机制，并确定SIRT1在CS诱导的组蛋白乙酰化、细胞凋亡/衰老和空域扩大中的作用。本提案中概述的实验还将确定SIRT1通路中的关键细胞内信号事件，并将使我们能够确定cs介导的COPD发病机制中异常肺部炎症和气道损伤的治疗靶点。这些研究具有很高的翻译潜力，因为SIRT1与衰老、衰老和炎症的控制有关。

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.