Impact of obesity on airway responses to air pollution

描述(申请人提供)：肥胖是哮喘的危险因素。肥胖受试者对空气污染物臭氧(臭氧)也有反应，臭氧(臭氧)是哮喘的诱因，与瘦削的人相比，肺功能的下降更严重。了解肥胖和哮喘之间关系的机制基础是这一应用的重点。我们已经建立了肥胖小鼠肥胖小鼠可以作为此类研究的有用模型。肥胖小鼠有先天的呼吸道高反应性(AHR)，这是哮喘的一个特征。与瘦小鼠相比，肥胖小鼠对急性臭氧暴露的反应也更大。我们的初步数据表明，内皮素可能参与了肥胖的先天AHR：肥胖小鼠肺组织中内皮素的表达增加，内皮素受体拮抗剂可减轻肥胖相关的AHR。我们的数据还表明，增加的核因子？B活性可能有助于肥胖相关的增加对臭氧的反应：在许多由急性臭氧暴露诱导表达的基因中，只有一小部分在肥胖小鼠和瘦小鼠中诱导的程度更大。在很大程度上，这些基因与炎症和免疫有关，而且大多数依赖于核因子？B。越来越多的人认识到肥胖是脂肪组织和全身氧化应激的一种状态。我们的初步数据表明，肥胖还会增加肺部的氧化应激，导致脂质过氧化加剧。值得注意的是，氧化应激和/或脂质过氧化产物已被证明可以诱导内皮素的表达和核因子？B的激活。因此，我们的假设是，肺内氧化应激通过促进内皮素的表达和加剧臭氧诱导的核因子？B的激活，在肺中促进肥胖的影响。为了解决这一假设，我们将在室内空气暴露后或急性臭氧暴露后的不同时间，测量肺和血液中的脂质过氧化和蛋白质羰化产物以及抗氧化剂。为了确定内皮素是否通过诱导内皮素的表达而参与肥胖相关的AHR，我们将用各种内皮素受体特异性拮抗剂治疗肥胖和瘦小鼠，并测量它们对AHR的影响。我们将研究肥胖对内皮素及其受体表达的影响。我们将确定用抗氧化剂治疗肥胖小鼠是否能减缓肥胖相关的肺内皮素表达的升高，并降低肥胖相关的AHR。我们还将确定是否可以通过限制饮食来逆转肺氧化应激及其后遗症。我们将使用EMSA和Western blotting对I？B、P50和P65进行检测，以确定在肥胖小鼠中，臭氧诱导的核因子-B的激活增加。为了确定核因子？B的重要性，我们将测量饮食诱导肥胖的核因子-？B p50-/-和野生型小鼠对臭氧的反应。实验将在表达I？B1突变体的转基因小鼠中重复进行，该突变体可抵抗CC10启动子驱动的降解。这些小鼠对呼吸道上皮细胞中的核因子？B活化具有抵抗力。如果得到证实，这一假说将为人类已经用于其他目的的治疗策略(内皮素受体拮抗剂、抗氧化剂)提供理论基础，并因此可能导致快速转化为肥胖哮喘患者。 与公众健康相关：肥胖是哮喘的一个重要危险因素，也会加剧空气污染物臭氧对肺部的影响。这项研究项目的目标是试图了解肥胖是如何导致这些影响的。我们研究的重点是与肥胖相关的炎症和氧化应激。了解肺部对空气污染反应增强的机制基础可能会导致针对这一日益危险的人群的新的治疗策略。

DESCRIPTION (provided by applicant): Obesity is a risk factor for asthma. Obese subjects also respond to the air pollutant, ozone (O3), an asthma trigger, with greater decrements in lung function than lean individuals. Understanding the mechanistic basis for the relationship between obesity and asthma is the focus of this application. We have established that obese mice obese mice can serve as a useful model for such studies. Obese mice have innate airway hyper- responsiveness (AHR), a characteristic feature of asthma. Compared to lean mice, obese mice also have greater responses to acute O3 exposure. Our preliminary data indicate that endothelin likely contributes to the innate AHR of obesity: endothelin expression is increased in the lungs of obese mice and endothelin receptor antagonists attenuate obesity-related AHR. Our data also indicate that increased NF-?B activation likely contributes to obesity-related increases in the response to O3: of the many genes whose expression is induced by acute O3 exposure, only a fraction are induced to a greater extent in obese versus lean mice. These are, for the most part, genes involved in inflammation and immunity, and most are NF-?B dependent. It is increasingly understood that obesity is a condition of adipose tissue and systemic oxidative stress. Our preliminary data indicate that obesity also increases oxidative stress in the lung, resulting in increased lipid peroxidation. Notably, oxidative stress and/or lipid peroxidation products have been demonstrated to induce to both endothelin expression and NF-?B activation. Hence, our hypothesis is that pulmonary oxidative stress contributes to the effects of obesity in the lung, by driving endothelin expression and by exacerbating O3- induced NF-?B activation. To address this hypothesis, we will measure lipid peroxidation and protein carbonylation products as well as antioxidants in the lungs and blood after room air exposure or at various times after acute O3 exposure. To determine whether endothelin contributes to obesity-related AHR by inducing endothelin expression, we will treat obese and lean mice with a variety of endothelin receptor specific antagonists, and measure their impact on AHR. We will examine the effects of obesity on endothelin and endothelin receptor expression. We will determine whether treatment of obese mice with antioxidants attenuates obesity-related elevations in lung endothelin expression and reduces obesity-related AHR. We will also determine if we can reverse pulmonary oxidative stress and its sequelae with dietary restriction. We will use EMSA and Western blotting for I?B, p50, and p65 to determine O3-induced NF-?B activation is increased in obese mice. To determine the importance of NF-?B, we will measure responses to O3 in NF-?B p50-/- and wildtype mice with diet induced obesity. Experiments will be repeated in transgenic mice expressing an I?B1 mutant that is resistant to degradation driven by a CC10 promoter. These mice are resistant to NF-?B activation in airway epithelial cells. If borne out, this hypothesis would provide the rationale for therapeutic strategies (endothelin receptor antagonists, antioxidants) already in human use for other purposes, and could thus lead to rapid translation to the obese asthmatic. PUBLIC HEALTH RELEVANCE: Obesity is an important risk factor for asthma and also exacerbates the pulmonary effects of the air pollutant, ozone. The goal of this research project is to try and understand how obesity induces these effects. The focus of our research is the inflammation and oxidative stress associated with obesity. Understanding the mechanistic basis for the augmented pulmonary responses to air pollution may lead to new therapeutic strategies for this increasingly at risk population.