Background

Exposure to air pollution during the first 1000 days of life (from conception to the 2nd year of life) might be of particular relevance for long-term child health. Changes in molecular markers such as DNA methylation and telomere length could underlie the association between air pollution exposure and pollution-related diseases as well as serve as biomarkers for past exposure. The objective of this systematic review was to assess the association between air pollution exposure during pregnancy and the first two years of life and changes in DNA methylation or telomere length in children.

Methods

PubMed was searched in October 2020 by using terms relative to ambient air pollution exposure, DNA methylation, telomere length and the population of interest: mother/child dyads and children. Screening and selection of the articles was completed independently by two reviewers. Thirty-two articles matched our criteria. The majority of the articles focused on gestational air pollution exposure and measured DNA methylation/telomere length in newborn cord blood or placental tissue, to study global, candidate-gene or epigenome-wide methylation patterns and/or telomere length. The number of studies in children was limited.

Results

Ambient air pollution exposure during pregnancy was associated with global loss of methylation in newborn cord blood and placenta, indicating the beginning of the pregnancy as a potential period of susceptibility. Candidate gene and epigenome-wide association studies provided evidence that gestational exposure to air pollutants can lead to locus-specific changes in methylation, in newborn cord blood and placenta, particularly in genes involved in cellular responses to oxidative stress, mitochondrial function, inflammation, growth and early life development. Telomere length shortening in newborns and children was seen in relation to gestational pollutant exposure.

Conclusions

Ambient air pollution during pregnancy is associated with changes in both global and locus-specific DNA methylation and with telomere length shortening. Future studies need to test the robustness of the association across different populations, to explore potential windows of vulnerability and assess the role of the methylation and telomere length as mediators in the association between early exposure to ambient air pollutants and specific childhood health outcomes.

中文翻译：

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生命的前1000天暴露于环境空气污染中以及儿童DNA甲基化组和端粒长度的改变：系统评价

背景

在生命的前1000天内（从受孕到生命的第二年）暴露于空气污染可能与儿童长期健康特别相关。DNA甲基化和端粒长度等分子标记的变化可能是空气污染暴露与污染相关疾病之间关联的基础，并且可以用作过去暴露的生物标记。这项系统评价的目的是评估怀孕期间和出生后头两年的空气污染暴露与儿童DNA甲基化或端粒长度的变化之间的关系。

方法

2020年10月，通过使用与周围空气污染暴露，DNA甲基化，端粒长度和关注人群（母子二倍体和儿童）相关的术语对PubMed进行了搜索。文章的筛选和选择由两名审稿人独立完成。有32篇文章符合我们的标准。大多数文章集中于妊娠空气污染暴露和新生儿脐带血或胎盘组织中DNA甲基化/端粒长度的测量，以研究整体，候选基因或表观基因组范围内的甲基化模式和/或端粒长度。对儿童的研究数量有限。

结果

怀孕期间暴露于空气中的环境污染与新生儿脐带血和胎盘中甲基化的整体丧失有关，表明怀孕开始是潜在的易感期。候选基因和整个表观基因组的关联研究提供了证据，表明妊娠暴露于空气污染物可导致新生儿脐带血和胎盘中甲基化的特定位点变化，尤其是涉及细胞对氧化应激，线粒体功能，炎症，生长的反应的基因和早期的生活发展。观察到新生儿和儿童端粒长度的缩短与妊娠污染物的暴露有关。

结论

怀孕期间的环境空气污染与总体和特定于位点的DNA甲基化变化以及端粒长度缩短有关。未来的研究需要测试不同人群之间关联的稳健性，探索潜在的脆弱性窗口，并评估甲基化和端粒长度作为早期暴露于环境空气污染物与特定的儿童健康结局之间的中介的作用。