Antenatal Dietary Supplementation is a Risk Factor for Infant Atopy Through Epige

该申请涉及广泛的挑战领域（03）：生物标志物的发现和验证，主题03- hl -101：确定和验证临床相关的、可量化的血液、血管、心脏和呼吸道功能障碍的诊断和治疗反应的生物标志物。本提案面临的挑战是了解特应性疾病患病率的“流行病”增加，以及表观遗传机制在多大程度上促成了婴幼儿中这些疾病的病因和患病率。最近的小鼠数据表明，在胎儿发育的脆弱时期，子宫内的饮食因素可以通过增强DNA甲基化形式的表观遗传调控来改变过敏性气道疾病的遗传风险。值得注意的是，特应性疾病的增加似乎与产前广泛补充叶酸（一种甲基供体）的制度有关。我们假设，影响特应性相关基因表达的母体CpG甲基化模式在特应性高风险婴儿的孕妇中与在特应性低风险婴儿的孕妇中是不同的，并且在产前膳食中补充甲基供体如叶酸、维生素B12和胆碱会增强特应性婴儿的这些表观遗传差异。CpG甲基化模式从高危母亲传给婴儿将与后代特应性风险增加有关。结合分子遗传学工具，我们将确定产前补充甲基供体是否会对孕妇及其直系后代产生不利影响，通过修改保护性基因增加特应性风险。为了根据父母的特应性病史，确定高、低特应性婴儿风险孕妇的不同甲基化基因，将使用最近开发的综合高通量相对甲基化阵列（CHARM）方法，对分娩时收集的母体PBMC进行全球DNA甲基化分析。我们预测，特定CpG二核苷酸位点的DNA甲基化模式将跟踪具有高特应性风险的母亲。为了评估子宫内传播模式，还将对特应性高风险婴儿的脐带血进行全球DNA甲基化分析，并将其甲基化模式与其母亲的甲基化模式进行比较。我们预测，通过表观遗传修饰的特应性相关基因表达的传递，特应性高风险婴儿的母亲在子宫内将增强的母体DNA甲基化模式传递给胎儿，从而导致其子女的特应性表型。为了研究血液中甲基供体浓度对CpG甲基化的影响，我们将测量高危母亲分娩时血液和婴儿脐带血中叶酸、维生素B12和胆碱的浓度，并将甲基供体浓度与DNA甲基化模式和强度相关联。我们预测，通过产前膳食补充增加母体血液中甲基供体的浓度，特别是叶酸、B12和胆碱，将增强母体DNA甲基化及其传递给胎儿。在婴儿有高特应性风险的孕妇中，甲基供体浓度将通过表观遗传DNA修饰与他们的孩子有特应性婴儿表型的风险增加相关。参与本研究的母亲所生的孩子在出生后的头两年期间的特应性疾病表现的临床数据将通过问卷收集。我们希望确定和验证临床相关的、可量化的特应性生物标志物，并在本项目中更准确地确定孕妇产前补充甲基供体的风险，并确定哪些人最有可能从预防或治疗的特定干预措施中受益。

DESCRIPTION (provided by applicant): Antenatal Dietary Supplementation is a Risk Factor for Infant Atopy Through Epigenetics This application addresses broad Challenge Area (03): Biomarker Discovery and Validation, topic 03-HL-101: Identify and validate clinically relevant, quantifiable biomarkers of diagnostic and therapeutic responses for blood, vascular, cardiac, and respiratory tract dysfunction. The challenge addressed in this proposal is to understand the "epidemic" increase in the prevalence of atopic diseases and the extent to which epigenetic mechanisms contribute to the etiology and prevalence of these diseases in infants and young children. Recent data in mice suggest that in utero dietary factors can modify the heritable risk of allergic airway disease during a vulnerable period of fetal development through epigenetic regulation in the form of enhanced DNA methylation. Remarkably, the increase in atopic diseases appears to correlate with the institution of widespread antenatal supplementation with folate, a methyl donor. We hypothesize that maternal CpG methylation patterns that affect expression of atopy-related genes are different in expectant mothers of infants at high risk as compared to expectant mothers of infants at low risk of atopy, and that antenatal dietary supplementation with methyl donors such as folate, vitamin B12, and choline enhance these epigenetic differences in infants with atopy. Transmission of CpG methylation patterns from high risk mothers to their infants will be associated with an increased risk of atopy in their offspring. Combining molecular genetics tools, we will determine if antenatal supplementation with methyl donors adversely affects pregnant mothers and their immediate offspring, increasing the risk for atopy through modification of protective genes. To identify genes that are differently methylated in expectant mothers at high and low risk of atopic infants, based on the parental history of atopy, global DNA methylation assays will be performed on maternal PBMC collected at the time of delivery using the recently developed Comprehensive High-throughput Arrays for Relative Methylation (CHARM) method. We predict that DNA methylation patterns at specific CpG dinucleotide sites will track with mothers at high risk of atopy. To assess in utero transmission patterns, global DNA methylation assays will also be performed in cord blood of infants at high risk of atopy, and their methylation patterns will be compared with those of their mothers. We predict in utero transmission of enhanced maternal DNA methylation patterns from mothers of infants at high risk of atopy to their fetuses resulting in an atopic phenotype of their children through transmission of epigenetically-modified expression of atopy-related genes. To study the effect of methyl donor concentrations in blood on CpG methylation, we will measure concentrations of folate, vitamin B12, and choline in blood of high risk mothers at delivery and cord blood of their infants, and correlate methyl donor concentrations with DNA methylation patterns and intensity. We predict that increased concentrations of methyl donors in the maternal blood through prenatal dietary supplementation, in particular folate, B12 and choline, will enhance maternal DNA methylation and its transmission to the fetus. In expectant mothers of an infant at high risk of atopy, methyl donor concentrations will correlate with an increased risk of their children having an atopic infant phenotype through epigenetic DNA modification. Clinical data on manifestations of atopic diseases during the first two years of life in children born to mothers participating in this study will be collected by questionnaires. We expect to identify and validate clinically relevant, quantifiable biomarkers of atopy, and in this project to identify more precisely the risks of antenatal supplementation with methyl donors in expectant mothers for having an atopic child and to identify those who are most likely to benefit from specific interventions for prevention or treatment. PUBLIC HEALTH RELEVANCE: There is widespread use of antenatal dietary supplementation with the goal of preventing in utero and neonatal abnormalities, but there has been little investigation about the potential risks of such interventions in expectant mothers. Folic acid, vitamin B12, and choline are methyl donors that, taken during pregnancy, have the potential through hypermethylation to alter the expression of genes that regulate development of allergy, increasing the risk in babies for developing an allergic disease. Our research team proposes to determine if such concerns about methyl donor supplementation are justified and pose a real threat in expectant mothers already at risk for transmitting an atopic genetic predisposition to their infants.