Maternal vitamin C supplementation to decrease effects of smoking during pregnancy on infant lung function and health:Follow-up of 2 randomized trials and association with changes in DNA methylation

项目摘要 尽管大力禁烟，但至少有12%的美国女性在以下情况下无法戒烟 怀孕，导致每年有超过45万名暴露在烟雾中的婴儿出生。母亲吸烟期间 怀孕对肺发育有不利影响，表现为肺功能终生下降和 增加患哮喘的风险。在《美国医学会杂志》上发表的一项随机对照试验(RCT)中，我们提供了 有证据表明，孕妇补充维生素C(怀孕期间每天500毫克)可以减少 母亲孕期吸烟对子代肺功能及随后发生喘息的影响。这个 这种ECHO应用的目的是结合来自两个研究RCT的产前队列的后代 孕期吸烟者补充维生素C对子代呼吸结局的影响 确定孕期补充维生素C的创新疗法是否会导致 子代的肺功能测试(PFTs)和呼吸健康的长期改善。开始，开始 了解产前维生素C可能通过哪些机制防止婴儿的健康发生变化 在吸烟者中，我们检测了来自胎盘、脐带血和口腔的一部分基因特异性DNA甲基化 拭子(2-5岁)收集自预期跟随怀孕安慰剂的受试者的后代。 接受治疗的吸烟者、接受维生素C治疗的吸烟者或不吸烟者。同时维生素C对人体健康的影响 减少母亲吸烟对子代PFTs和喘息的影响，补充维生素C 阻止了母体吸烟引起的大多数DNA甲基化的显著变化 胎盘和脐带血。令人惊讶的是，这种对DNA甲基化改变的预防仍然很明显 几年后，在后代的口腔拭子中。这一初步数据表明，维生素背后的机制 C预防母亲吸烟对子代肺部健康的一些影响涉及 预防母亲吸烟引起的表观遗传学改变。因此，本申请有4个具体目标：1、 建立孕期吸烟者补充维生素C的两个随机对照试验的子代联合队列； 2、确定孕妇补充维生素C对孕期吸烟者的保护作用 子代肺部健康可延续至青春期早期；3、开始表征表观遗传机制 这似乎是怀孕期间吸烟对子代肺部健康和保护儿童健康的影响的基础 4、为整个ECHO研究收集核心数据并与之互动。呼吸性 将通过每半年一次的纵向、有效的呼吸史和每年开始的PFTs来评估健康状况 在3岁的时候。每年将采集口腔拭子，并在6、9和12岁时采集血液，以提供DNA用于 基因分析。DNA甲基化变化将通过甲基化芯片和亚硫酸氢盐测序来测量。 这项研究将解决怀孕期间吸烟如何影响呼吸结果，提供机制和 治疗见解，并为ECHO提供受试者和数据，以解决其他关键结果。

Project Summary Despite strong anti-smoking efforts, at least 12% of American women cannot quit smoking when pregnant, resulting in more than 450,000 smoke-exposed infants born yearly. Maternal smoking during pregnancy adversely affects lung development as seen by lifelong decreases in pulmonary function and increased risk of asthma. In a randomized controlled trial (RCT), published in JAMA, we have provided evidence that maternal vitamin C supplementation (500 mg daily during pregnancy) can decrease the effects of maternal smoking during pregnancy on offspring lung function and the subsequent incidence of wheeze. The purpose of this ECHO application is to combine the offspring from the prenatal cohorts of two RCTs studying the effects of vitamin C supplementation to pregnant smokers on offspring respiratory outcomes and to determine if the innovative therapy of maternal vitamin C supplementation during pregnancy leads to prolonged improvements on offspring’s pulmonary function tests (PFTs) and respiratory health. To begin to understand mechanisms by which prenatal vitamin C may be preventing changes in the health of offspring of smokers, we examined gene specific DNA methylation from a subset of placentas, cord bloods and buccal swabs (ages 2-5) collected from subjects who were the offspring of prospectively-followed pregnant placebo- treated smokers, vitamin C-treated smokers, or non-smokers. In parallel with the effects of vitamin C on the reduction of the effects of maternal smoking on offspring PFTs and wheeze, the supplementary vitamin C prevented the majority of significant changes in DNA methylation induced by maternal smoking in both placentas and cord blood. Strikingly, this prevention of alterations in DNA methylation was still evident 2-5 years later in offspring buccal swabs. This preliminary data suggests that the mechanism underlying vitamin C’s prevention of some of the effects of maternal smoking on offspring pulmonary health involves the prevention of epigenetic changes induced by maternal smoking. Thus this application has 4 specific aims: 1, to create the combined cohort of offspring from the 2 RCTs of vitamin C supplementation to pregnant smokers; 2, to determine if the protective effects of maternal vitamin C supplementation to pregnant smokers on offspring pulmonary health extend to early adolescence; 3, to begin to characterize the epigenetic mechanisms that appear to underlie the effects of smoking during pregnancy on offspring lung health and on the protective effects of vitamin C; and 4, to gather core data for and interact with the overall ECHO study. Respiratory health will be assessed by longitudinal semi-annual, validated respiratory histories and yearly PFTs beginning at 3 years of age. Buccal swabs will be collected yearly and blood at 6, 9 and 12 years to provide DNA for genetic analysis. DNA methylation changes will be measured by methylation chips and bisulfite sequencing. This study will address how smoking during pregnancy affects respiratory outcomes, provide mechanistic and therapeutic insights, and provide subjects and data to ECHO to address other key outcomes.