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 尽管有强大的反吸烟努力，至少12%的美国妇女不能戒烟时， 每年有超过450，000名婴儿出生时暴露在烟雾中。母亲吸烟期间 妊娠对肺发育产生不利影响，表现为肺功能终身下降， 增加哮喘的风险。在发表于JAMA的随机对照试验（RCT）中，我们提供了 有证据表明，母亲补充维生素C（怀孕期间每天500毫克）可以减少 母亲在怀孕期间吸烟对后代肺功能和随后的喘息发生率的影响。的 本ECHO应用程序的目的是将来自两个RCT的产前队列的后代联合收割机， 妊娠吸烟者补充维生素C对后代呼吸结果的影响， 确定在怀孕期间补充孕妇维生素C的创新疗法是否会导致 长期改善后代的肺功能测试（PFT）和呼吸系统健康。开始 了解产前维生素C可能阻止后代健康变化的机制， 吸烟者中，我们检测了胎盘、脐带血和口腔粘膜的基因特异性DNA甲基化， 从前瞻性随访妊娠安慰剂组的后代受试者中采集拭子（2-5岁）， 治疗的吸烟者、维生素C治疗的吸烟者或非吸烟者。与维生素C的作用平行， 减少母亲吸烟对后代PFT和喘息的影响，补充维生素C 阻止了母亲吸烟引起的DNA甲基化的大部分显著变化， 胎盘和脐带血引人注目的是，这种对DNA甲基化改变的预防仍然是明显的2-5 几年后的后代口腔拭子中。这些初步数据表明，维生素D的潜在机制 预防母亲吸烟对后代肺部健康的某些影响涉及 预防由母亲吸烟引起的表观遗传变化。因此，本申请具有4个具体目的：1， 创建怀孕吸烟者补充维生素C的2项随机对照试验的后代组合队列; 2、确定母亲补充维生素C对妊娠吸烟者的保护作用 后代肺部健康延长到青春期早期; 3、开始表征表观遗传机制 这似乎是怀孕期间吸烟对后代肺部健康和保护性肺功能的影响的基础。 维生素C的影响;和4，收集核心数据，并与整体ECHO研究互动。呼吸 健康状况将通过每半年一次的经验证的纵向呼吸史和每年一次的PFT进行评估， 在3岁的时候。将每年采集口腔拭子，并在6、9和12岁时采集血液，以提供DNA， 遗传分析将通过甲基化芯片和亚硫酸氢盐测序测量DNA甲基化变化。 这项研究将探讨怀孕期间吸烟如何影响呼吸系统的结果，提供机制和 治疗见解，并为ECHO提供受试者和数据，以解决其他关键结局。

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.