Cardiovascular Response to CAP Microbial Components in Controlled Human Exposures

描述(申请人提供)：环境颗粒物污染，可能是心肌梗塞的触发因素，已被估计为导致过早死亡的第13大原因，也是全球疾病负担的十大贡献者之一。尽管有证据表明，周围的颗粒物携带不同数量的革兰氏阴性细菌成分内毒素，但污染颗粒物上的微生物群落对其炎症和心血管影响的贡献尚不清楚。研究表明，由于气候影响了空气中微生物的模式，北美的暖季正在延长。在我们完成的55名多伦多成年人的随机交叉对照人体暴露研究中，我们发表了初步数据，证明了浓缩环境颗粒物(CAP)的内毒素成分与全身炎症、氧化应激和血压增加的相关性。高达40%的白细胞计数增加归因于颗粒 质量可能归因于其内毒素含量。内毒素可能是一系列复杂微生物暴露的哨兵标志，这些微生物暴露于其他病原体相关分子模式(PAMPs)，这些模式刺激人类先天免疫炎症，可能与心血管结果相关。在我们多伦多研究的基础上，我们将结合16S、18S及其rRNA基因和选择性全基因组鸟枪测序与创新的生物信息学方法，在门和属水平(目标1)表征粗略、精细和超细CAP暴露下的细菌和真菌群落。我们将在测试前两周评估环境温度和湿度水平如何影响帽上微生物分类群的相对丰度(目标4)。我们将测试这一假设，即帽上革兰氏阴性变形杆菌的丰度增加将与血压升高、臂动脉狭窄相关，其次与血管刺激(血管内皮生长因子)、全身炎症(例如白细胞计数)和氧化应激(例如8-羟基脱氧鸟苷)的中间生物标志物的增加有关，并将评估变形杆菌中个别细菌属对这些关联的相对贡献(目标2)。我们将评估帽子上最丰富的真菌分类群是否与我们的结果独立相关(目标3)。最后，我们将把生物信息学方法应用于我们的元基因组数据，以量化PAMPS活性成分合成途径的相对丰度，并探索途径丰度如何影响血压、炎症和氧化应激。了解微生物对颗粒物毒性的贡献将有助于确定颗粒物污染增加心血管风险的机制，并将为估计控制颗粒物污染以改善心血管健康的益处的监管机构提供信息。

DESCRIPTION (provided by applicant): Ambient particle pollution, which can be a trigger for myocardial infarction, has been estimated to be the 13th leading cause of premature death and one of the top ten contributors to the global burden of disease world- wide. Despite evidence that ambient particles carry variable amounts of the gram-negative bacterial component endotoxin, the contribution of microbial communities on pollution particles to their inflammatory and cardiovascular effects is poorly defined. Studies suggest that the warm season is lengthening in North America with climate influences on patterns of airborne microbes. We have published and preliminary data demonstrating associations of the endotoxin component of concentrated ambient particles (CAPs) with increased systemic inflammation, oxidative stress and blood pressure in our completed randomized cross-over controlled human exposure study of 55 Toronto adults. Up to forty-percent of the increase in leukocyte count attributed to particle mass could be attributed to its endotoxin content. Endotoxin may be a sentinel marker for a complex array of microbial exposures with other pathogen-associated-molecular patterns (PAMPs) that stimulate human innate immune inflammation potentially relevant to cardiovascular outcomes. Leveraging on our Toronto study, we will combine 16S,18S, ITS rRNA gene and selective whole genome shotgun sequencing with innovative bioinformatic methods to characterize the bacterial and fungal communities on coarse, fine and ultrafine CAP exposures, at the phylum and genus level (Aim 1). We will evaluate how the relative abundance of microbial taxa on CAPS is influenced by ambient temperature and humidity levels in the two weeks prior to testing (Aim 4). We will test the hypothesis that increased abundance of gram-negative phylum Proteobacteria on CAPs will be associated with increased blood pressure, brachial artery narrowing and, secondarily, with increases in intermediate biomarkers of vascular stimulation(vascular endothelial growth factor), systemic inflammation (e.g., white blood cell count), and oxidative stress (e.g., 8-hydroxy-deoxy-guanosine), and will assess the relative contribution of individual bacterial genera within Proteobacteria to these associations (Aim 2). We will evaluate whether the most abundant fungal taxa on CAPs are independently associated with our outcomes (Aim 3). Finally, we will apply bioinformatic methods to our metagenomic data to quantify the relative abundance of synthesis pathways for active components of PAMPS, and explore how pathway abundance influences blood pressure, inflammation and oxidative stress. Understanding the microbial contributions to particle toxicity will help define mechanisms whereby particle pollution increases cardiovascular risk, and will inform regulators estimating the benefits of controlling particle pollution to improve cardiovascular health.