Impact of obesity on airway responses to air pollution

描述（由申请人提供）：肥胖是哮喘的危险因素。肥胖的受试者对空气污染物臭氧（O3）也有反应，这是一种哮喘的触发因素，肺功能比瘦的人下降得更厉害。了解肥胖和哮喘之间关系的机制基础是本申请的重点。我们已经确定肥胖小鼠可以作为此类研究的有用模型。肥胖小鼠具有先天性气道高反应性（AHR），这是哮喘的特征.与瘦小鼠相比，肥胖小鼠对急性O3暴露也有更大的反应。我们的初步数据表明，内皮素可能有助于先天性AHR的肥胖：内皮素的表达增加，肥胖小鼠的肺和内皮素受体拮抗剂减弱肥胖相关的AHR。我们的数据还表明，增加NF-？B激活可能有助于肥胖相关的增加对O3的反应：在急性O3暴露诱导表达的许多基因中，只有一小部分在肥胖小鼠与瘦小鼠中诱导程度更大。这些基因大部分与炎症和免疫有关，大部分是NF-？B依赖型。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况。我们的初步数据表明，肥胖也增加了肺中的氧化应激，导致脂质过氧化反应增加。值得注意的是，氧化应激和/或脂质过氧化产物已被证明诱导内皮素表达和NF-？B激活。因此，我们的假设是，肺氧化应激有助于肥胖的影响，在肺，通过驾驶内皮素的表达和加剧O3诱导的NF-？B激活。为了解决这一假设，我们将测量脂质过氧化和蛋白质羰基化产物以及抗氧化剂在肺和血液后，室内空气暴露或急性O3暴露后的不同时间。为了确定内皮素是否通过诱导内皮素表达而导致肥胖相关的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和内皮素受体表达的影响。我们将确定用抗氧化剂治疗肥胖小鼠是否能减弱与肥胖相关的肺内皮素表达升高，并降低与肥胖相关的AHR。我们还将确定是否可以通过饮食限制来逆转肺氧化应激及其后遗症。我们将使用EMSA和蛋白质印迹法检测I？B，p50和p65，以确定O3诱导的NF-？肥胖小鼠中B活化增加。确定NF-？B，我们将测量NF-？饮食诱导肥胖的B p50-/-和野生型小鼠。实验将重复在转基因小鼠表达的I？B1突变体，其对由CC 10启动子驱动的降解具有抗性。这些小鼠对NF-？气道上皮细胞中的B活化。如果得到证实，这一假设将为已经在人类中用于其他目的的治疗策略（内皮素受体拮抗剂、抗氧化剂）提供基本原理，并因此可能导致快速转化为肥胖哮喘。

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.