Air Pollution on Adiposity and Vascular Dysfunction: White or Brown Matters?

描述(申请人提供)：由于肥胖症的增加，发达国家的预期寿命可能首次开始下降。越来越多的人发现环境因素与肥胖的发展有关。为了研究空气污染暴露是否导致脂肪组织中的肥胖和炎症，从而导致胰岛素抵抗和血管功能障碍，我们假设暴露于细颗粒物(PM2.5)污染通过依赖活性氧(ROS)激活内质网(ER)应激和增强胰岛素抵抗而导致脂肪功能障碍。为了实现这一目标，我们首先评估了PM2.5诱导的内脏(白色脂肪组织)和血管周围组织(棕色脂肪组织)的ER应激，以及野生型(C57BL/6)和CHOP[CCAAT/增强子结合蛋白(C/EBP)同源蛋白]-/-小鼠和CHOP-/-小鼠体内脂肪血管功能障碍的增强情况。磁共振成像(MRI)评估身体脂肪质量/分布，综合正电子发射断层扫描和计算机断层扫描(microPET-CT)评估棕色脂肪组织的活性，组织学检查评估线粒体含量，脂肪细胞增生和肥大，脂肪组织中血管生长，肌拍片研究大血管功能。还将评估脂肪组织中PERK介导的UPR途径对线粒体功能、炎症和细胞凋亡的影响。含有镍的PM2.5或含有钒的PM2.5将与单独接触PM2.5进行比较，以评估生物反应的差异。然后，我们通过流式分选和激光捕获显微镜研究PM2.5暴露诱导的巨噬细胞内质网应激反应是否是脂肪炎症和功能障碍的核心，并评估内质网应激和细胞凋亡、线粒体含量、关键线粒体基因表达和线粒体氧耗(功能)的指标。体内成脂实验将通过注射CD24、CD24-或CD34细胞进行脂肪组织重建，或与脂肪组织巨噬细胞联合作用于未暴露的裸鼠。最后，我们研究了PM2.5是否通过未折叠蛋白反应(UPR)激活和perk-eIF21-CHOP途径的内质网(ER)应激诱导NAD(P)H氧化酶关键成分缺失的p47Phox-/-和gp91Phox-/-小鼠的改变。因此，我们打算将重点放在脂肪组织上，但系统地、机械地研究单核/巨噬细胞在空气污染引起的肥胖和血管功能障碍中的作用。通过在4周大的小鼠身上开始暴露，并暴露到24周，我们模拟了人类从童年到成年的肥胖发展。这项提案的发现有望为更好地理解空气污染暴露对肥胖发生和相关血管功能障碍的机制做出重大贡献，这可能导致更绿色的能源工厂和汽车的新政策/干预，更严格的空气质量标准，以及更好的全面肥胖预防。

DESCRIPTION (provided by applicant): Owing to the increase in obesity, life expectancy may start to decrease in developed countries for the first time. Environmental factors are increasingly found to be associated with the development of obesity. To investigate if air pollution exposure contributes to adiposity and inflammation in adipose tissues that induces insulin resistance and vascular dysfunction, we hypothesize that exposure to fine particulate matter (PM2.5) pollution induces adipose dysfunction via reactive oxygen species (ROS)-dependent activation of endoplasmic reticulum (ER) stress and potentiation of insulin resistance. To achieve this goal, we first assess PM2.5-induced ER stress in visceral (white adipose tissue) and perivascular tissue (brown adipose tissue) and potentiation of adipose vascular dysfunction in wild type (C57BL/6) and CHOP[CCAAT/enhancer binding protein (C/EBP) homologous protein]-/- mice in wild type and CHOP-/- mice in a whole body exposure system "Ohio's Air Pollution Exposure System for the Interrogation of Systemic Effects (OASIS)-1" up to 24 weeks. Magnetic resonance imaging (MRI) to evaluate body fat mass/distribution, integrated positron-emission tomography and computed tomography (microPET-CT) to evaluate the activity of brown adipose tissue, tissue histological examination to assess mitochondria content, adipocyte hyperplasia and hypertrophy, and vascular growth in the fat tissues, myograph to investigate macrovascular function will be performed. Fat tissues will also be assessed for PERK-mediated UPR pathway on mitochondrial function, inflammation and apoptosis. PM2.5 with Nickel or PM2.5 with vanadium will be compared to PM2.5 exposure alone to evaluate differences in biological responses. We then investigate if PM2.5 exposure induced ER stress response in macrophages is central to adipose inflammation and dysfunction by flow sorting and laser capture microscopy and assessed for indices for ER stress and apoptosis, mitochondria content, expression of key-mitochondrial genes and mitochondrial oxygen consumption (function). An in vivo adipogenesis assay will be performed by adipose tissue reconstitution via cell injection of CD24+, CD24-, or CD34+, or combined with adipose tissue macrophages into non-exposed nude mice. We finally study if PM2.5-induced alteration in p47phox-/- and gp91phox-/- mice that are deficient in critical component of NAD(P)H oxidase through unfolded protein response (UPR) activation and endoplasmic reticulum (ER) stress of PERK-eIF21-CHOP pathway. Therefore, we intend to focus on adipose tissues but systemically, mechanistically investigate the role of monocyte/macrophage in air pollution-induced adiposity and vascular dysfunction. By starting the exposure at age of 4 weeks in mice and exposure up to 24 weeks, we mimic the obesity development from childhood to adulthood in human. The findings from this proposal are expected to make significant contribution to better understanding the mechanisms of air pollution exposure on obesity development and associated vascular dysfunction, which may lead to the new policies/interventions in greener energy plants and automobiles, stricter air quality standards, and better, comprehensive obesity prevention.