Review of the environmental prenatal exposome and its relationship to maternal and fetal health

Environmental chemicals comprise a major portion of the human exposome, with some shown to impact the health of susceptible populations, including pregnant women and developing fetuses. The placenta and cord blood serve as important biological windows into the maternal and fetal environments. In this article we review how environmental chemicals (defined here to include man-made chemicals [e.g., flame retardants, pesticides/herbicides, per- and polyfluoroalkyl substances], toxins, metals, and other xenobiotic compounds) contribute to the prenatal exposome and highlight future directions to advance this research field. Our findings from a survey of recent literature indicate the need to better understand the breadth of environmental chemicals that reach the placenta and cord blood, as well as the linkages between prenatal exposures, mechanisms of toxicity, and subsequent health outcomes. Research efforts tailored towards addressing these needs will provide a more comprehensive understanding of how environmental chemicals impact maternal and fetal health.     

暴露组学的概念与应用

暴露组学作为基因组学的补充是指从妊娠开始贯穿整个人生的环境暴露(包括生活方式因素)。暴露源包括外源(污染、辐射、饮食等)和内源(炎症、感染、微生物等)。继全基因组关联研究(GWAS)之后发展的全暴露组关联研究(EWAS)的目的是对在未知方式下暴露的评估。EWAS方法通过比较患者和健康受试者暴露组的分析结果,确定有效的生物标志物,进而利用这些生物标志物来阐明暴露-效应关系(生化流行病学)、暴露和人体动力学来源(暴露生物学),以及作用机制(系统生物学)。"自下而上"和"自上而下"的方法在识别个体暴露上都具有科学价值。"自上而下"法用于揭示人类疾病的未知暴露源,而"自下而上"法是用于分析外暴露以及建立干预与预防的方法。生物标志物不仅可以用于研究外暴露,也可以用于研究内暴露。内暴露组学采用组学的方法进行研究,如基因组学、蛋白质组学、表观基因组学、代谢组学、转录组学、加合物组学等。人类生命早期暴露组学(HELIX)项目是近期启动的描述欧洲人群的早期暴露以及揭示组学标志物和儿童时期健康关系的第一次尝试。该文介绍了其研究方法、工具、思路及其重要意义,同时总结了暴露组学从概念到应用可能面临的挑战。     

A vision for exposome epidemiology: The pregnancy exposome in relation to breast cancer in the Child Health and Development Studies

Etiology of complex diseases, such as breast cancer, involves multiple genetic, behavioral and environmental factors. Gene sequencing enabled detection of genetic risks with relatively small effect size, and high-resolution metabolomics (HRM) to provide omics level data for exposures is poised to do the same for environmental epidemiology. Coupling HRM to the Child Health and Development Studies (CHDS) cohort combines two unique resources to create a prototype for exposome epidemiology, in which omics scale measures of exposure are used for study of distribution and determinants of health and disease. Using this approach, exposures and biologic responses during pregnancy have been linked to breast cancer in the CHDS. With improved chemical coverage and extension to larger populations and other disease processes, development of exposome epidemiology portends discovery of new disease-associated environment factors with small effect size as well as new capabilities to disentangle these from behavioral and other risk factors.     

Adductomics: characterizing exposures to reactive electrophiles

To understand environmental causes of disease, unbiased methods are needed to characterize the human exposome, which represents all toxicants to which people are exposed from both exogenous and endogenous sources. Because they directly modify DNA and important proteins, reactive electrophiles are probably the most important constituents of the exposome. Exposures to reactive electrophiles can be characterized by measuring adducts from reactions between circulating electrophiles and blood nucleophiles. We define an 'adductome' as the totality of such adducts with a given nucleophilic target. Because of their greater abundance and residence times in human blood, adducts of hemoglobin (Hb) and human serum albumin (HSA) are preferable to those of DNA and glutathione for characterizing adductomes. In fact, the nucleophilic hotspot represented by the only free sulfhydryl group in HSA (HSA-Cys(34)) offers particular advantages for adductomic experiments. Although targeted adducts of HSA-Cys(34) have been monitored for decades, an unbiased method has only recently been reported for visualizing the HSA-Cys(34) 'subadductome'. The method relies upon a novel mass spectrometry application, termed fixed-step selected reaction monitoring (FS-SRM), to profile Cys(34) adducts in tryptic digests of HSA. Here, we selectively review the literature regarding the potential of adductomics to partially elucidate the human exposome, with particular attention to the HSA-Cys(34) subadductome.     

暴露组与暴露组学

人类复杂疾病主要是由环境因素或者环境与遗传因素相互作用所致.自人类基因组计划开展以来,有关遗传因索与复杂疾病发病关系的研究进展非常迅速,相比之下,环境暴露与复杂疫病关系的研究却没有得到应有的重视和发展.暴露组与暴露组学的提出,为推动环境因素与人类健康之间关系的研究提供了新思路.     

自身免疫性疾病发病机制新进展

自身免疫性疾病(AD)是一种免疫紊乱状态,机体正常的保护性免疫应答不能区分自身抗原和外源性抗原转而攻击人体正常的组织和细胞,因而会出现一系列的异常症状.目前国际上对AD有了很多新的认识,基因和环境的共同作用增加了发病倾向人群的患病风险,而环境因素是多方面的,有学者针对人体内外的环境暴露提出了暴露组学的概念,暴露组学涵盖了除人体外的各种外界因素.根据目前的研究进展,拟从暴露组学、微生物组学及感染组学等多个方面详细阐述AD发病机理提出了致病假说,为进一步研究提供理论依据.     

Monitoring of drug intake during pregnancy by questionnaires and LC‐MS/MS drug urine screening: evaluation of both monitoring methods

Various studies pointed towards a relationship between chronic diseases such as asthma and allergy and environmental risk factors, which are one aspect of the so‐called Exposome. These environmental risk factors include also the intake of drugs. One critical step in human development is the prenatal period, in which exposures might have critical impact on the child's health outcome. Thereby, the health effects of drugs taken during gestation are discussed controversially with regard to newborns' disease risk. Due to this, the drug intake of pregnant women in the third trimester was monitored by questionnaire, in addition to biomonitoring using a local birth cohort study, allowing correlations of drug exposure with disease risk. Therefore, 622 urine samples were analyzed by an untargeted liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) urine screening and the results were compared to self‐administered questionnaires. In total, 48% (n = 296) reported an intake of pharmaceuticals, with analgesics as the most frequent reported drug class in addition to dietary supplements. 182 times compounds were detected by urine screening, with analgesics (42%; n = 66) as the predominantly drug class. A comparison of reported and detected drug intake was performed for three different time spans between completion of the questionnaires and urine sampling. Even if the level of accordance was low in general, similar percentages (~25%, ~19%, and ~ 20%) were found for all groups. This study illustrates that a comprehensive evaluation of drug intake is neither achieved by questionnaires nor by biomonitoring alone. Instead, a combination of both monitoring methods, providing complementary information, should be considered. Copyright © 2014 John Wiley & Sons, Ltd.     

La influencia del exposoma en el cáncer de piel

Skin cancer is the most frequent type of cancer in humans. While exposure to solar radiation is the most widely known and relevant causal factor, the different degrees of individual risk have not been fully elucidated. Epidemiological studies show how the risk of skin cancer is affected by other types of radiation (eg, ionizing radiation), pesticides, particulate matter in air pollution, toxins (eg, arsenic) in water and some foods. Some living entities, such as polyomavirus and human papillomavirus, can also cause specific types of cancer. Lastly, lifestyle factors such as stress, sleep, and exercise may play a role, although only a few studies shed light on these factors. The abovementioned factors make up the exposome of skin cancer, that is, the set of environmental exposures that, together with the genome and microbiome, determine the onset of disease.     

The study of interactions between genome and exposome in the development of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a systemic inflammatory autoimmune disease characterized by a broad spectrum of clinical and serological manifestations. This may reflect a complex and multifactorial etiology involving several identified genetic and environmental factors, though not explaining the full risk of SLE. Established SLE risk genotypes are either very rare or with modest effect sizes and twin studies indicate that other factors besides genetics must be operative in SLE etiology. The exposome comprises the cumulative environmental influences on an individual and associated biological responses through the lifespan. It has been demonstrated that exposure to silica, smoking and exogenous hormones candidate as environmental risk factors in SLE, while alcohol consumption seems to be protective. Very few studies have investigated potential gene-environment interactions to determine if some of the unexplained SLE risk is attributable hereto. Even less have focused on interactions between specific risk genotypes and environmental exposures relevant to SLE pathogenesis. Cohort and case-control studies may provide data to suggest such biological interactions and various statistical measures of interaction can indicate the magnitude of such. However, such studies do often have very large sample-size requirements and we suggest that the rarity of SLE to some extent can be compensated by increasing the ratio of controls. This review summarizes the current body of knowledge on gene-environment interactions in SLE. We argue for the prioritization of studies that comprise the increasing details available of the genome and exposome relevant to SLE as they have the potential to disclose new aspects of SLE pathogenesis including phenotype heterogeneity.