Project 2Asthma in Children Exposed to Heavy Metals

摘要 环境中肺暴露于含有混合重金属的空气颗粒物(PM) 导致慢性肺部疾病的发展，包括哮喘。这些疾病是典型的 与上皮-间充质间通讯失调有关。PM，颗粒物尺寸为≤2.5um (PM2.5)含有高水平的重金属，包括镉(Cd)、砷(As)和锰(Mn)。 然而，这些重金属如何在疾病发病机制中发挥作用的机制尚不清楚。在……里面 在这个项目的支持下，我们检测到居民的血清/尿液中的重金属水平从 环境保护局(EPA)在北部指定国家优先名单(NPL)超级基金地点 伯明翰。来自这个受影响地区的哮喘儿童有全身接触重金属的证据，因为 尿砷水平较高就是证据。经支气管镜检查获得支气管肺泡灌洗液 来自这个受影响区域的哮喘患者含有包装在一起的上皮细胞衍生的外切体 线粒体。此外，来自人类哮喘受试者的BAL来源的外体偏向于 更高浓度的抗凋亡鞘磷脂(神经鞘氨醇-1-磷酸和神经酰胺)通过条带- 脂质组学分析。这些外切体是纤维化的，因为它们诱导成纤维细胞重新编程为 抗细胞凋亡和纤维化表型。动物研究表明，气管内滴注 重金属诱导小鼠支气管周围纤维化，提供了一个机会来产生概念验证前 临床数据支持在环境中靶向促炎和促纤维化鞘磷脂通路 哮喘。 在这个项目中要检验的假设是，儿童接触重金属会引起呼吸道反应。 上皮损伤/激活，触发胞外脂的释放以激活成纤维细胞/平滑肌 导致哮喘患者气道高反应性和重塑的细胞。具体目标是：(1) 确定重金属诱导的胞外脂肪信号激活上皮亚细胞的机制 间充质细胞(SMCs/FBS)；(2)确定由支气管释放的脂质介质/外切体的作用 上皮细胞在重金属暴露小鼠气道高反应性和重塑中的作用 确定重金属暴露是否与哮喘严重程度和血尿酸水平升高有关 居住在北伯明翰NPL超级基金站点的儿童的血浆、EBC和痰脂质生物标记物。 这些研究将为重金属暴露对哮喘易感性的影响提供新的见解。 和严重性；关于纤维形成的外切体上皮-间充质沟通的新机制；以及 重金属相关性慢性哮喘治疗新方法的研究进展 曝光。

SUMMARY Environmental exposure of the lung to airborne particulate matter (PM) containing mixed heavy metals contributes to development of chronic lung diseases, including asthma. These diseases are classically associated with dysregulated epithelial-mesenchymal communication. PM with a particulate size of ≤2.5 µm (PM2.5) contain high levels of heavy metals, including cadmium (Cd), arsenic (As), and manganese (Mn). However, the mechanisms of how these heavy metals contribute to disease pathogenesis are unknown. In support of this project, we detected elevated levels of heavy metals in the serum/urine of residents from the Environmental Protection Agency (EPA) designated National Priorities List (NPL) Superfund site in North Birmingham. Asthmatic children from this Affected Area have evidence of systemic heavy metals exposure, as evidenced by higher urinary levels of arsenic. Bronchoalveolar lavage (BAL) fluid obtained by bronchoscopy of asthmatic individuals from this Affected Area contain epithelial cell-derived exosomes that package mitochondria. Additionally, BAL-derived exosomes from human asthmatic subjects are skewed towards a higher concentration of anti-apoptotic sphingolipids (sphingosine-1-phoshate > ceramide) by SWATH- lipidomics analysis. These exosomes are fibrogenic as they induce reprogramming of fibroblasts to an apoptosis-resistant and fibrogenic phenotype. Animal studies demonstrate that intra-tracheal instillation of heavy metals induces peribronchial fibrosis in mice, providing an opportunity to generate proof-of-concept pre- clinical data in support of targeting pro-inflammatory and pro-fibrotic sphingolipid pathways in environmental asthma. The hypothesis to be tested in this project is that heavy metal exposures in children induce airway epithelium injury/activation that triggers the release of exosomal lipids to activate fibroblasts/smooth muscle cells that contribute to airway hyper-responsiveness and remodeling in asthma. The specific aims are to: (1) determine the mechanisms of heavy metal-induced exosomal lipid signaling that activates sub-epithelial mesenchymal cells (SMCs/Fbs); (2) determine the role of lipid mediators/exosomes released by bronchial epithelial cells in airway hyper-responsiveness and remodeling in mice exposed to heavy metals; and (3) determine whether heavy metal exposures are associated with asthma severity and increased levels of plasma, EBC and sputum lipid biomarkers in children residing in the North Birmingham NPL Superfund site. These studies will provide new insights into the impact of heavy metal exposure on asthma susceptibility and severity; on novel mechanisms of epithelial-mesenchymal communication by fibrogenic exosomes; and development of new therapeutic approaches to the treatment of chronic asthma associated with heavy metal exposures.