No abstract

Folate is a key source of one‐carbon groups for DNA methylation; but studies on DNA methylation response to folic acid (FA) supplementation show inconsistent results. We hypothesize that measuring DNA methylation in whole blood (WB), which contains a mixture of distinct leukocyte cell types, may have confounded the results of previous studies. Therefore, the aim of this pilot study was to determine if a single cell type could serve as a more reliable epigenetic reporter. The study was performed in normal weight (BMI 18.5 – 24.9 kg/m2) women (18 – 35 y; n = 12), with blood samples taken before and after eight weeks of supplementation with 800 ug/day of FA. CD16+ cells (CD16) were isolated using antibody‐bound magnetic beads. DNA methylation patterns from WB and CD16 cells were measured across >485,000 CpG sites using the Infinium Human Methylation450 Bead Chip. For each CpG site, the proportion of DNA methylation that changed over the 8 week intervention was evaluated by fitting a separate linear model. Genome‐wide analysis indicated changes in 7887 vs. 8482 CpG sites in response to supplementation in WB and CD16, respectively; with DNA methylation decreased in 77.2% (WB) or 66.3% (CD16) of these sites. Results suggest that there are differences in methylation response in WB and CD16 after FA supplementation. The implication of these methylation differences are being explored in our on‐going gene enrichment analyses. Grant Funding Source: Funded in part by HATCH #GEO00706, #GEO00707 and the Obesity Initiative at the University of Georgia

Folate is a water‐soluble vitamin important for normal fetal development. Maternal obesity is associated with increased risk for birth defects; however the relationship between obesity and folate metabolism is not well understood. Recently, our lab reported a lower short‐term pharmacokinetic response to an acute oral dose of folic acid in obese vs normal weight women of child‐bearing age. This study determined the serum folate (microbiological assay) and whole blood DNA methylation (LC/MS) response to 8 wks of supplementation with 800 µg/d folic acid (FA) in healthy normal weight (n=13, BMI=21.5±0.4) and obese (n=7, BMI=37.6±0.8) women of child‐bearing age. Samples were collected at baseline and after 4 and 8 wks of supplementation. At baseline, serum folate was lower in obese vs normal weight women, whereas global DNA methylation was similar in both groups. Repeated measures ANOVA indicated an effect of FA on increasing serum folate over time (p < 0.0001) for all subjects combined, and a time x group interaction for global methylation (p < 0.05) characterized by a reduction in methylation from baseline to 8 wks in normal weight but not obese women. These data provide additional evidence suggesting differences in metabolic response to folic acid as a function of BMI in women of child‐bearing age and provide support for consideration of a BMI‐adjusted folic acid intake recommendation. Grant Funding Source: Funded in part by HATCH #GEO00706, #GEO00707, #FLA‐FOS‐004797 and the Obesity Initiative at the Univ

It is well established that DNA cytosine methylation epialleles (CG vs 5MeCG) alter the expression of obesity related genes. The current study examined differences in 5MeCG in CD16+ cells isolated from blood using antibody‐bound magnetic beads in normal weight (BMI 18.5‐24.9 kg/m2; n = 12) and obese (BMI > 30 kg/m2; n = 6) women (18‐35y). 5MeCG was measured across > 485,000 CG sites using the HumanMethylation450 BeadChip (Illumina©). 16,969 CG sites were differentially methylated in obese as compared to normal weight women (p < 0.05). 65.4% of these sites had decreased methylation. Six of these CG’s remained associated (p < 10‐7) after adjustment for multiple testing (False Discovery Rate < 0.05), including sites in CRYGB, CDH5, and VASH1. Our results have potential implications in obesity and CDH5 has been shown previously to have differential methylation in peripheral blood leukocytes in obese (Wang et al. doi: 10.1186/1741‐7015‐8‐87). Continued analysis will further examine these methylation differences. Grant Funding Source: Supported by a grant from the UGA Obesity Initiative and the GRA Eminent Scholar Endowment (CAB)

Folate is a key source of one‐carbon groups for DNA methylation; but studies on DNA methylation response to folic acid (FA) supplementation show inconsistent results. We hypothesize that measuring DNA methylation in whole blood (WB), which contains a mixture of distinct leukocyte cell types, may have confounded the results of previous studies. Therefore, the aim of this pilot study was to determine if a single cell type could serve as a more reliable epigenetic reporter. The study was performed in normal weight (BMI 18.5 – 24.9 kg/m2) women (18 – 35 y; n = 12), with blood samples taken before and after eight weeks of supplementation with 800 ug/day of FA. CD16+ cells (CD16) were isolated using antibody‐bound magnetic beads. DNA methylation patterns from WB and CD16 cells were measured across >485,000 CpG sites using the Infinium Human Methylation450 Bead Chip. For each CpG site, the proportion of DNA methylation that changed over the 8 week intervention was evaluated by fitting a separate linear model. Genome‐wide analysis indicated changes in 7887 vs. 8482 CpG sites in response to supplementation in WB and CD16, respectively; with DNA methylation decreased in 77.2% (WB) or 66.3% (CD16) of these sites. Results suggest that there are differences in methylation response in WB and CD16 after FA supplementation. The implication of these methylation differences are being explored in our on‐going gene enrichment analyses. Grant Funding Source: Funded in part by HATCH #GEO00706, #GEO00707 and the Obesity Initiative at the University of Georgia

Folate plays an important role in one‐carbon metabolism including DNA methylation. We reported a lower acute pharmacokinetic response to folic acid (FA) in obesity. Both maternal folate deficiency and obesity are associated with increased risk for neural tube defects (NTDs). However, the impact of folate or obesity on DNA methylation of NTD‐related genes remains unclear. We provided 800 ug/d of FA to healthy normal weight (NW; BMI 18.5‐24.9 kg/m2;n = 12) and obese (BMI > 30 kg/m2; n = 6) women (18‐35y) for 8‐wks and determined changes in DNA methylation in CD 16+ cells, isolated from blood using magnetic bead technology. DNA methylation was examined across 2107 CpG sites in 91 NTD‐ and folate pathway‐ related genes using the Infinium Human Methylation450 Bead Chip. For each CpG site, the proportion of DNA methylation that changed over the supplementation was evaluated by fitting a separate linear model. The analysis indicated changes in 57 vs. 101 CpG sites (36 vs. 47 genes) following the supplementation in NW and obese women, respectively. Among them, 68% vs. 76% of the CpG sites (26 vs 37 genes) decreased in methylation. These data suggest that DNA methylation in NTD‐ and folate pathway‐related genes changed in response to FA supplementation and that the changes were different in NW and obese women. Specific pathways influenced by folate status and exhibiting a differential response in obesity are being explored. Grant Funding Source: Funded in part by HATCH #GEO00706, #GEO00707 and the Obesity Initiative at the University of Georgia