Sequencing the exposome: developing an integrated approach using nontargeted mass spectrometry and computational chemistry

曝光组包含一生中所有环境暴露的总和。在化学和化学生物学中，这些暴露表现为内源性和外源性化学物质，它们是由饮食、生活方式、辐射、压力和暴露于环境污染物造成的。与基因组不同，暴露组是可变的，因此需要对随时间演变的暴露进行频繁、经济有效和可靠的测量，最合适的方法是对少量血液(例如干血点)进行采样。这种测量对于确定大多数慢性疾病的原因至关重要，但进一步进展的障碍是巨大的：c.一滴血中90%的未知污染物无法使用现有的分析平台进行检测；大多数环境毒物的身份及其在导致慢性病中的作用也是未知的！ 我的团队的研究将通过开发创新的质谱学(MS)技术来应对这些挑战，即。流动调制多维气相色谱-大气压电离(GCxGC-API)，辅之以最先进的计算工具。建议的分析平台提供了无与伦比的分离，并在与具有高流量弹性的API源配合使用时显著提高了检测极限。尽管它承诺了这一点，但此前从未有人尝试过！这一方法的发展将使以下方面成为可能：用3-50微升的血液(1个Phd，1个BSc)识别未知污染物；与需要汇集采样和过量血液容量的现有方法相比，这是一个显著的改进；以及创新的电离(1个MSc)和激活(1个Phd，1个BSc)联用技术，这些技术将提供识别未知毒物至关重要的新信息。 非靶向筛选(NTS)是一种定性实验的术语，目的是利用MS鉴定未知的有机化合物。目前流行的想法是在评估环境意义之前必须弄清化合物的结构，但考虑到样品的复杂性，这种方法是不切实际的。我们认为，一种未知化学物质的环境意义可以从它在质谱仪中的行为(和反应)中推断出来，而不需要事先知道它的结构。我实验室的学员将：开发加速污染物发现的自动化软件(1个博士学位，1个学士学位)；调查和利用质谱仪中发生的丰富的化学物质，它反映了体内的新陈代谢，可以用来区分有毒和无毒的化学物质(1个博士学位，1个学士学位)；最后，进行旨在回答以下问题的勘测研究(3个硕士学位，1个学士学位)：这些新发现的污染物对环境和健康构成什么风险？预计这项研究计划的结果将有助于指导制定有效的环境法规，并指导工业开发更安全、更可持续的化学品。

The exposome encompasses the totality of environmental exposures during a lifetime. In chemistry and chemical biology, these exposures manifest as endogenous and exogenous chemicals that result from diet, lifestyle, radiation, stress, and exposure to environmental pollutants. Unlike the genome, the exposome is variable and thus requires frequent, cost-effective and reliable measurements of exposures that evolve over time, most appropriately by sampling small quantities of blood (e.g. dried-blood spots). Such measurements will be vital in order to identify the causes of most chronic diseases, but the obstacles to further progress are formidable: c. 90% of unknown pollutants in a drop of blood are not detectable using existing analytical platforms; and the identities of most environmental toxicants and their role in causing chronic disease are unknown! My group's research will address these challenges through the development of innovative mass spectrometry (MS) techniques, viz. flow modulated multidimensional gas chromatography-atmospheric pressure ionization (GCxGC-API), complemented by state-of-the-art computational tools. The proposed analytical platform affords unparalleled separation and significantly improves detection limits when coupled with an API source that is resilient to high flows. Despite its promise, this has not been previously attempted! The development of this approach will enable: the identification of unknown pollutants with 3-50 microliters of blood (1 PhD, 1 BSc), a remarkable improvement over existing methodologies that require pooled sampling and excessive blood volumes >300uL; and innovative hyphenation of ionization (1 MSc) and activation (1 PhD, 1 BSc) techniques that will provide new information critically needed to identify unknown toxicants. Nontargeted screening (NTS) is the term-of-art for qualitative experiments aimed at identifying unknown organic compounds using MS. The prevailing thought is that a compound's structure must be elucidated prior to assessing environmental significance, but this approach is impractical considering sample complexity. We suggest that that the environmental significance of an unknown chemical may be inferred from its behavior (and reactivity) in the mass spectrometer without a priori knowledge of its structure. Trainees in my lab will: develop automated software that accelerates pollutant discovery (1 PhD, 1 BSc); investigate and exploit the rich chemistry occurring in the mass spectrometer that mirrors in vivo metabolism and can be used to differentiate toxic from non-toxic chemicals (1 PhD, 1 BSc); and finally, conduct reconnaissance studies (3 MSc, 1 BSc) aimed at answering the question: What risk do these newfound pollutants pose to the environment and health? It is anticipated that the results from this research program will help guide the creation of effective environmental regulation; and guide industry on the development of safer, more sustainable chemicals.