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2017 Conference

Abstract Number: 752 | ID: 2017-752

Histone Modifications of PPARγ Gene in Human Placenta in relation to Prenatal Phthalate Esters Exposures

Kuan-Chih Chiu(*, Institute of Environmental Health, College of Public Health, National Taiwan University, Taiwan, v47526@hotmail.com), Chen-Yu Liu(Institute of Environmental Health, College of Public Health, National Taiwan University, Taiwan)
Background/Aim: Phthalate esters (Phthalates) are plasticizers widely used in polyvinyl chloride products. Prenatal phthalate exposures may inhibit the growth and development of placenta and result in adverse health effects in neonates. Epigenetic studies have reported DNA methylation and miRNA in placenta can mediate the effects of phthalates. However, histone modification changes in this aspect remain unclear. This study is to investigate histone modifications of peroxisome proliferator-activated receptor γ (PPARγ) gene in human placenta, which is contributed to the placental differentiation and transportation of fatty acid, and to investigate the mediation effects between prenatal phthalate exposures and birth outcomes.
Methods: Among the 483 mother-infant pairs in Taiwan Birth Panel Study (TBPS), 163 of them had maternal urine samples collected at third trimester and phthalate metabolites measured. Placenta samples were used to measure PPARγ histone methylation levels by chromatin immunoprecipitation (ChIP). Medical records were used to extract information of birth outcomes. Univariable and multivariable linear regression models were used to study the phthalates exposure effects on PPARγ; histone methylation levels and birth outcomes.
Results: Every natural-log unit increase in maternal urinary concentration of MEP was negatively correlated with birth weight (g) (β=-79.96, p=0.013), birth length (cm) (β=-0.43, p=0.005) and head circumference (cm) (β=-0.28, p=0.018); MEHP was negatively correlated with birth weight (g) (β=-53.88, p=0.034) and gestational age (week) (β=-0.22, p=0.008). After adjusting for maternal age, birth type and infant gender, urinary concentration of MEP was still negatively correlated with birth length (β=-0.37, p=0.014).
Conclusions: Prenatal phthalate exposures may result in adverse health effects in neonates through altering the histone modification levels in placenta. We are now working on ChIP among the 163 subjects' histone modification data. Further analysis regarding the association between phthalate exposures and histone modifications will be tested.