孕期生活事件应激致婴幼儿发育障碍性别差异的宫内表观遗传机制研究

It is not uncommon that the stress of life events during pregnancy is more harmful to the neurodevelopment of boys than that of girls. However, the intrauterine mechanism is unknown. Based on the gender differences in cortisol reactivity, we hypothesize that "the epigenetic abnormalities of glucocorticoid pathway gene in placenta tissue leading to the expression of glucocorticoid higher in boys than that in girls is the intrauterine mechanism of developmental disorders risk higher in boys than that in girls". To demonstrate the scientific hypothesis, with a prospective cohort study design, we evaluate the level of stress during pregnancy in early, middle and late pregnancy, using Life Events Scale for Pregnant Women and hair cortisol, and assess their offsprings’ neurodevelopment at 12 and 18 months of age using Age and Stages Questionnaires and Bayley Scales of Infant and Toddler Development-Third Edition, respectively. We firstly aims to clarify the type of stress during pregnancy that causes gender differences in infants’ and toddlers’ neurodevelopment. And then, we randomly selected 150 boys’ and girls’ placentae with the higher and lower pregnancy stress of this type. The methylation of HSD11B2, NR3C1 and FKBP5 genes in the placentae DNA will be detected. We will analysize whether there is gender differences in the methylation of these genes under the same level of stress during pregnancy, and whether the methylation of these genes is an intermediate mechanism between abnormal neurodevelopment in young children and the life event stress during pregnancy. It will improve our understanding of the intrauterine mechanism for gender differences in child neurodevelopment.

孕期生活事件应激对男童发育障碍的危害显著高于女童的现象常见但机制不明。基于对皮质醇反映性的性别差异，本项目提出“胎盘组织糖皮质激素通路基因表观遗传异常导致糖皮质激素表达男高于女是孕期生活事件应激导致婴幼儿发育障碍男高于女的宫内机制”的科学假设。拟通过队列研究设计，采用孕妇生活事件量表和发皮质醇共同评估孕早、中、晚三期应激水平，分别采用年龄与发育进程问卷和贝利婴幼儿发展量表－第三版评估12月龄和18月龄婴幼儿发育障碍情况。首先阐明导致婴幼儿发育障碍性别差异的孕期应激类型，然后随机选取该类型应激水平较高和较低者胎盘组织男女各150个，提取DNA，检测HSD11B2、NR3C1和FKBP5基因启动子区甲基化程度，分析同等应激作用下胎盘组织以上基因甲基化程度是否存在性别差异，以及该基因甲基化是否是孕期生活事件应激导致男女童发育障碍差异的中介机制，以论证科学假设，提升对儿童发育性别差异的机制认识。

孕期应激对儿童发育障碍的影响存在复杂的性别差异。胎盘糖皮质激素（glucocorticoids，GC）反应基因甲基化及炎症因子是孕期应激导致儿童发育障碍重要机制。二者是否是这种复杂性别差异的机制还不清楚。本研究基于马鞍山优生优育队列就妊娠相关焦虑（Pregnancy-related anxiety, PRA）开展了三项研究：（1）PRA与婴幼儿发育障碍的性别差异性关联研究；（2）胎盘GC反应基因甲基化在PRA对婴幼儿发育障碍性别差异性影响的中介作用；（3）胎盘炎症因子在PRA对幼儿多动症性别差异性影响的中介作用。基于2019年新建的出生队列就孕期生活事件应激开展了一项研究：（4）孕期生活事件应激与新生儿出生结局的性别差异性关联研究。四项研究结果如下：（1）仅孕晚期PRA可增加6月龄儿童沟通能区（RR= 3.52）、个人-社会能区（RR= 2.46）发育迟滞风险；仅孕晚期PRA可增加18月龄儿童精细运动能区（RR=2.07）、解决问题能区（RR= 2.31）发育迟滞风险。（2）孕晚期PRA会增加4岁男孩多动发生风险（OR=1.54），增加女孩情绪症状发生风险（OR=1.61）。仅男童中，孕晚期PRA与胎盘FKBP5甲基化呈负相关（OR=0.62）。也仅在男童中，NR3C1甲基化与儿童多动症（OR = 1.80）和情绪症状（OR = 1.64）正相关，HSD11B2甲基化与情绪症状负相关（OR = 0.53）。并没有发现FKBP5、NR3C1和HSD11B2甲基化在PRA与儿童情绪症状和多动症状性别差异性关联的中介效应。（3）孕期PRA与3岁多动症的关联性具有性别差异，仅在男童中发现显著关联，胎盘CRP mRNA表达在孕期PRA致男童多动症上具有显著的中介效应（β=0.025）。（4）除在男婴中发现孕晚期不良生活事件暴露与过期产之间有显著关联之外，在两个性别中均未发现孕前、孕早、中、晚四个阶不良生活事件暴露对早产和出生体重的显著影响。母亲孕期PRA对儿童神经行为发育的影响具有性别差异，孕晚期可能是关键期。胎盘CRP 可能是性别差异的中介机制，胎盘GC反应基因是否是性别差异的中介机制有待探讨。

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