Aberrant 5’-CpG Methylation of Cord Blood TNFα Associated with Maternal Exposure to Polybrominated Diphenyl Ethers

<div><p>Growing evidence suggests that maternal exposures to endocrine disrupting chemicals during pregnancy may lead to poor pregnancy outcomes and increased fetal susceptibility to adult diseases. Polybrominated diphenyl ethers (PBDEs), which are ubiquitously used flame-retardants, could leach into the environment; and become persistent organic pollutants via bioaccumulation. In the United States, blood PBDE levels in adults range from 30–100 ng/g- lipid but the alarming health concern revolves around children who have reported blood PBDE levels 3 to 9-fold higher than adults. PBDEs disrupt endocrine, immune, reproductive and nervous systems. However, the mechanism underlying its adverse health effect is not fully understood. Epigenetics is a possible biological mechanism underlying maternal exposure-child health outcomes by regulating gene expression without changes in the DNA sequence. We sought to examine the relationship between maternal exposure to environmental PBDEs and promoter methylation of a proinflammatory gene, <i>tumor necrosis factor alpha</i> (<i>TNFα</i>). We measured the maternal blood PBDE levels and cord blood <i>TNFα</i> promoter methylation levels on 46 paired samples of maternal and cord blood from the Boston Birth Cohort (BBC). We showed that decreased cord blood <i>TNFα</i> methylation associated with high maternal PBDE47 exposure. CpG site-specific methylation showed significantly hypomethylation in the girl whose mother has a high blood PBDE47 level. Consistently, decreased <i>TNFα</i> methylation associated with an increase in TNFα protein level in cord blood. In conclusion, our finding provided evidence that <i>in utero</i> exposure to PBDEs may epigenetically reprogram the offspring’s immunological response through promoter methylation of a proinflammatory gene.</p></div

Genomic DNA sequence of the 5’ flanking region of TNFα promoter.

<p>The sequence of the primers used for bisulfite genomic sequencing (BS- TNFα-F1, BS- TNFα-R1) are underlined and in italic bold type. There are a total of 12 CpG nucleotides (shaded in gray) located at the promoter region of TNFα encompassing the transcription start site (TSS).</p

Decreased CpG site-specific methylation of TNFα in cord blood associates with high maternal PBDE47 exposure in girls (lower panel) not boys (upper panel).

<p><b>Percentage of</b> methylation of each CpG site of the TNFα promoter represented as mean ± SEM in low- (gray open circles) and high-level (black squares) PBDE47 exposed group. The difference in % methylation in these 12 CpG sites between the two groups was compared by two-way ANOVA. * <i>p</i><0.05, meant % methylation at a CpG site was significantly different between low- and high- level PBDE47 exposed groups (based on t-test).</p

Spearman correlation between cord blood TNFα promoter methylation and cord blood TNFα protein level.

<p>*The Spearman’s rank correlation coefficient (ρ, rho) was calculated to measure the strength of the relationship between the percent of methylation of <i>TNFα</i> promoter and TNFα protein level in cord blood samples. Negative values indicated inverse relationship between cord blood <i>TNFα</i> promoter methylation and cord blood TNFα protein level. The larger the negative value meant greater negative correlation. Statistical significance at individual CpG site was determined with <i>p</i><0.05.</p><p>Spearman correlation between cord blood TNFα promoter methylation and cord blood TNFα protein level.</p

Decreased <i>TNFα</i> promoter methylation associates with high maternal PBDE47 exposure.

<p>Average % methylation of the <i>TNFɑ</i> promoter (y-axis) was calculated by taking an average of the methylation level of a total 12 CpG sites within the <i>TNFɑ</i> promoter region in 46 cord blood DNA samples. Results were compared between low- and high-level PBDE47 exposed groups. Each circle and square represented the average percent methylation level for each subject in low-level PBDE47 exposed group and high-level PBDE47 exposed group, respectively. Boys (in black) and girls (in red) are marked differently. The error bars represented means (±standard error of mean, SEM).</p

A scatter plot showing the relationship between the average % methylation of the <i>TNFα</i> promoter and log10-transformed maternal blood PBDE47 level.

<p>Methylation of each CpG site of the <i>TNFɑ</i> promoter was assayed in 46 cord blood DNA samples by bisulfite genomic sequencing. Average % methylation of the <i>TNFɑ</i> promoter (y-axis) was calculated by taking an average of the methylation level of a total 12 CpG sites within the <i>TNFɑ</i> promoter region.</p

The serum and urine miR-1 levels in patients with the open-heart surgeries and CPB.

<p>n = 20, *P<0.01 vs T₀. T₀, before surgery (pre-surgery); T₁, before CPB (pre-CPB); T₂, 60 min after CPB (post-CPB); and T₃, 24 hours after CPB (post-CPB).</p

The serum levels of cardiac troponin (cTnI) in patients with the open-heart surgeries and CPB.

<p>n = 20, *P<0.01 vs T₀. T₀, before surgery (pre-surgery); T₁, before CPB (pre-CPB); T₂, 60 min after CPB (post-CPB); and T₃, 24 hours after CPB (post-CPB).</p

MOESM1 of Design and synthesis of novel 3-(thiophen-2-yl)-1,5-dihydro-2H-pyrrol-2-one derivatives bearing a hydrazone moiety as potential fungicides

Additional file 1. All the copies of FT-IR, 1H NMR, 13C NMR and EI-MS for title compounds 5a–5w

Effect of adolescent rat's exposure to different doses of ketamine on training trials in the Morris water maze.

<p>A: The latencies for finding the platform for each trial during the 5 day; B: Swim distance for finding the platform for each trial during the 5 day. Values are expressed as mean ± S.E.M, n = 10 for each group. *P<0.05, **P<0.01 vs Control on the fourth and fifth day(repeated-measures ANOVA, followed by Dunnett's test.</p