Cigarette Smoke-derived Electrophilic Aldehydes and Airway Inflammation

描述（由申请人提供）：吸烟仍然是全球主要的健康负担，并与儿童呼吸道感染的增加和慢性肺部疾病（如COPD、哮喘和肺癌）的发展密切相关。香烟烟雾（CS）对健康的不良影响在很大程度上与其免疫抑制特性有关，导致先天免疫反应、宿主防御和肿瘤监测受损。尽管人们普遍认为这些作用是由于CS衍生的活性氧（ROS），主要是基于对硫醇基抗氧化剂保护作用的观察，但CS中的主要硫醇反应剂是丙烯醛（2,3- propenal）和其他相关的不饱和醛。我们最近对小鼠的研究表明丙烯醛对肺泡巨噬细胞的免疫抑制作用与CS相似。在这方面，与氧化还原敏感蛋白靶点的直接和短暂烷基化相关的急性机制似乎是至关重要的，直接影响NF-？B或AP-1改变细胞氧化还原调节。然而，这些蛋白质烷基化的具体功能后果尚不清楚。丙烯醛暴露也通过促进过敏致敏和抑制过敏性炎症来模仿吸烟对哮喘发展和严重程度的一些可变影响。丙烯醛的这些作用与上皮损伤增加有关，可能是由上皮屏障完整性的改变和与肺中主要抗原呈递细胞树突状细胞的相互作用介导的，尽管丙烯醛影响上皮完整性和产生调节树突状细胞成熟的介质的机制尚不清楚。本提案的主要目的是阐明丙烯醛改变先天巨噬细胞和上皮免疫反应以及过敏性炎症的机制，并确定关键酶系统直接烷基化的重要性。我们计划使用新开发的蛋白质组学方法和分析这些修饰在靶蛋白中的功能重要性，确定丙烯醛诱导的先天免疫应答抑制（Aim 1）中直接蛋白质修饰的重要性，并探索丙烯醛暴露对过敏性炎症和致敏的影响（Aim 2）。重点关注上皮屏障功能的改变和与直接烷基化或相关靶蛋白相关的介质产生。此外，基于最近的研究表明，丙烯醛可以通过谷胱甘肽s -转移酶P1 （GSTP1）和硫化氢（H2S）解毒，硫化氢是一种新发现的内源性介质，由半胱氨酸合成酶（CBS）代谢（homo）半胱氨酸产生，我们将探讨GSTP1和CBS/H2S在调节丙烯醛诱导的免疫反应改变中的重要性（Aim 3）。总的来说，这些研究不仅将为丙烯醛对cs相关疾病的潜在贡献提供重要见解，而且还可能与了解其他相关内源性或环境亲电试剂的作用有关。

DESCRIPTION (provided by applicant): Cigarette smoking remains a major global health burden and is strongly associated with increased childhood respiratory infections and development of chronic lung diseases such as COPD, asthma and lung cancer. The adverse health effects of cigarette smoke (CS) are largely related to its immuno-suppressive properties leading to impaired innate immune responses, host defense, and tumor surveillance. Although it is commonly thought that these effects are due to CS-derived reactive oxygen species (ROS), largely based on observations of protective effects of thiol-based antioxidants, the main thiol-reactive agents within CS are acrolein (2,3- propenal) and other related unsaturated aldehydes. Our recent studies in mice have demonstrated immunosuppressive effects of acrolein on alveolar macrophages that mimic those of CS. Acute mechanisms associated with direct and transient alkylation of redox-sensitive protein targets appear to be critical in this respect, diretly affecting activation of NF-?B or AP-1 and altering cellular redox regulation. However, the specific functional consequences of these protein alkylations are not known. Acrolein exposure also mimics some of the variable effects of cigarette smoking on asthma development and severity, by promoting allergic sensitization but also by suppressing allergic inflammation. These effects of acrolein were associated with increased epithelial injury and are likely mediated by altered epithelial barrier integrity and interaction with dendritic cells, the main antigen-presentng cell in the lung, although the mechanisms by which acrolein impacts on epithelial integrity and production of mediators that regulate dendritic cell maturation are not known. The main goal of the present proposal is to elucidate the mechanisms by which acrolein alters innate macrophage and epithelial immune responses as well as allergic inflammation, and to identify the importance of direct alkylation of critical enzyme systems. We plan to determine the importance of direct protein modifications in acrolein-induced suppression of innate immune responses (Aim 1), using newly developed proteomic approaches and analysis of the functional importance of these modifications in target proteins, and explore the consequences of acrolein exposure on allergic inflammation and sensitization (Aim 2), focusing on alterations in epithelial barrier function and mediator production in association with direct alkylation or relevant target proteins. Also, based on recent studies indicating that acrolein is detoxified by glutathione S-transferase P1 (GSTP1) and by hydrogen sulfide (H2S), a newly recognized endogenous mediator produced by (homo)cysteine metabolism by cystathionine ¿-synthase (CBS), we will explore the importance of GSTP1 and CBS/H2S in modulating acrolein-induced alterations in immune responses (Aim 3). Collectively, these studies will not only offer important insights into the potential contribution of acrolein to CS-related disease, but may also be relevant to understanding the actions of other relevant endogenous or environmental electrophiles. PUBLIC HEALTH RELEVANCE: Many lines of evidence indicate that the health effects of cigarette smoking are related to alterations of the immune system. While cigarette smoking is generally associated with chronic inflammation, it also possesses immunosuppressive properties that result in increased sensitivity to respiratory bacterial or viral infection. Moreovr, cigarette smoking also variably contributes to allergic asthma, by promoting allergic sensitization but also altering inflammation altering the development or severity of allergic airway disease. The mechanistic aspects of such effects of smoking are poorly understood. Although it is popular belief that the adverse effects of CS are due to oxidative stress, based on protective effects of thiol-based antioxidants, our studies performed with previous NIH support indicate that acrolein (2,3-propenal), an important reactive component of CS, is responsible for many of the effects of CS due to its reactivity to thiols and redox-sensitive pathways. Moreover, acrolein exposure mimics many of the adverse effects of CS on the immune system, and can similarly affect allergic inflammation. Using proteomics approaches, we have identified the major cell targets for acrolein and show that acrolein directly targets several critical cell proteins involve in inflammatory signaling and immune responses. The main goal of the current proposal is to address the importance for such direct protein modifications in in vivo mouse models of acute lung injury and of allergic asthma. Secondly, we will address the importance of enzymatic and metabolic systems that mediate detoxification of acrolein, to determine whether changes in these systems alter the susceptibility to acrolein. Collectively, these studies will provide important insights into the importance of acrolein in development of respiratory disease associated with smoking or other environmental exposure, and will help determine factors that may contribute to susceptibility to CS-induced respiratory infections or allergic airways disease.