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.
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.
