Association of Prenatal Polycyclic Aromatic Hydrocarbons Exposure, DNA Hydroxymethylation, and Neurodevelopment at 0 and 2 Years of Age

Maternal exposure to polycyclic aromatic hydrocarbons (PAHs) during pregnancy may have effects on the offspring epigenome. And the change in onset epigenome may be associated with children's neurodevelopment. The current study investigated the relationship between 5-hydroxymethylcytosine (5-hmC) levels in cord blood and PAH metabolites in maternal urine at delivery and children's neurodevelopment at birth and at age 2. We enrolled 400 pregnant women and their newborns and collected their biological samples after obtaining written informed consent. Enzyme linked immunosorbent assay kits and Chromatin immunoprecipitation kits were used to assess the DNA hydroxymethylation level in cord blood. We observed that 1-hydroxypyrene (1-OHPyr) was inversely associated with gesell developmental scale scores, positively associated with global DNA 5-hmC levels, and associated with decreased 5-hmC levels of the brain-derived neurotrophic factor (<i>BDNF</i>) and methyl CpG binding protein 2 (<i>MeCP2</i>) gene promoter. In addition, the 5-hmC levels of the <i>BDNF</i> and <i>MeCP2</i> gene promoters were associated with motor scores. The global DNA 5-hmC was inversely associated with motor scores. Mediation analysis showed mediation effects between 1-OHPyr and motor scores by 5-hmC. The global DNA 5-hmC and <i>MeCP2</i> and <i>BDNF</i> gene promoter 5-hmC contributed 28.51%, 27.29%, and 18.98% of the effect on motor scores changes related to 1-OHPyr. The study results suggested that 5-hmC can be a potential mechanism between prenatal PAH exposure and children's neurodevelopment at age 2 and provide a better understanding of the role of hydroxymethylation in neurodevelopment.