Exposure to volatile organic compounds induces cardiovascular toxicity that may involve DNA methylation

Volatile organic compounds (VOCs) are common air pollutants and water contaminants. We previously found maternal exposure to VOCs was associated with offspring congenital heart disease (CHD). However, little information is available about the effects of VOCs on cardiovascular development at embryonic stage and the underlying mechanism remains unclear. In this study, we aimed to investigate the effects of a mixture of six VOCs on cardiovascular development in zebrafish embryos. Embryos were exposed to different concentrations of VOCs mixture (32 mg/L, 64 mg/L and 128 mg/L) for 96 h, cardiovascular abnormalities including elongated heart shape, increased distance between sinus venosus and bulbus arteriosus, slowed circulation and altered heart rate were observed in a dose- and time-dependent manner. Meanwhile, VOCs exposure increased global DNA methylation levels in embryos. Analysis identified hundreds of differentially methylated sites and the enrichment of differentially methylated sites on cardiovascular development. Two differentially methylated-associated genes involved in MAPK pathway, hgfa and ntrk1, were identified to be the potential genes mediating the effects of VOCs. By enzyme-linked immunosorbent assay, altered human serum hgf and ntrk1 levels were detected in abnormal pregnancies exposed to higher VOCs levels with fetal CHD. For the first time, our study revealed exposure to VOCs induced severe cardiovascular abnormalities in zebrafish embryos. The toxicity might result from alterations in DNA methylation and corresponding expression levels of genes involved in MAPK pathway. Our study provides important information for the risk of VOCs exposure on embryonic cardiovascular development.