Relation of DNA Methylation of 59-CpG Island of ACSL3 to Transplacental Exposure to Airborne Polycyclic Aromatic Hydrocarbons and Childhood Asthma Frederica Perera1., Wan-yee Tang2., Julie Herbstman 1 , Deliang Tang1, Linda Levin2, Rachel Miller1,5, Shuk-mei Ho2,3,4* 1 The Columbia Center for Children’s Environmental Health, Columbia University Mailman School of Public Health, New York, New York, United States of America, 2 Department of Environmental Health, University of Cincinnati, Cincinnati, Ohio, United States of America, 3 Center for Environmental Genetics, University of Cincinnati, Cincinnati, Ohio, United States of America, 4 Cancer Center, College of Medicine, University of Cincinnati, Cincinnati, Ohio, United States of America, 5 Division of Pulmonary, Allergy and Critical Care Medicine, Columbia University College of Physicians and Surgeons, New York, New York, United States of America Abstract In a longitudinal cohort of ,700 children in New York City, the prevalence of asthma (.25%) is among the highest in the US. This high risk may in part be caused by transplacental exposure to traffic-related polycyclic aromatic hydrocarbons (PAHs) but biomarkers informative of PAH-asthma relationships is lacking. We here hypothesized that epigenetic marks associated with transplacental PAH exposure and/or childhood asthma risk could be identified in fetal tissues. Mothers completed personal prenatal air monitoring for PAH exposure determination. Methylation sensitive restriction fingerprinting was used to analyze umbilical cord white blood cell (UCWBC) DNA of 20 cohort children. Over 30 DNA sequences were identified whose methylation status was dependent on the level of maternal PAH exposure. Six sequences were found to be homologous to known genes having one or more 59-CpG island(s) (59-CGI). Of these, acyl-CoA synthetase long-chain family member 3 (ACSL3) exhibited the highest concordance between the extent of methylation of its 59-CGI in UCWBCs and the level of gene expression in matched fetal placental tissues in the initial 20 cohort children. ACSL3 was therefore chosen for further investigation in a larger sample of 56 cohort children. Methylation of the ACSL3 59-CGI was found to be significantly associated with maternal airborne PAH exposure exceeding 2.41 ng/m3 (OR = 13.8; p,0.001; sensitivity = 75%; specificity = 82%) and with a parental report of asthma symptoms in children prior to age 5 (OR = 3.9; p,0.05). Thus, if validated, methylated ACSL3 59CGI in UCWBC DNA may be a surrogate endpoint for transplacental PAH exposure and/or a potential biomarker for environmentally-related asthma. This exploratory report provides a new blueprint for the discovery of epigenetic biomarkers relevant to other exposure assessments and/or investigations of exposure- disease relationships in birth cohorts. The results support the emerging theory of early origins of later life disease development. Citation: Perera F, Tang W-y, Herbstman J, Tang D, Levin L, et al. (2009) Relation of DNA Methylation of 59-CpG Island of ACSL3 to Transplacental Exposure to Airborne Polycyclic Aromatic Hydrocarbons and Childhood Asthma. PLoS ONE 4(2): e4488. doi:10.1371/journal.pone.0004488 Editor: Catherine M. Suter, Victor Chang Cardiac Research Institute, Australia Received September 8, 2008; Accepted December 19, 2008; Published February 16, 2009 Copyright: 2009 Perera et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work is in part supported by National Institutes of Health grants: ES009600 (FP), ES008977 (FP), ES015905 (FP, SMH, RM, DT), ES013071 (SMH), ES015584 (SMH), and ES006096 (SMH), ES016817 (WYT), the Department of Defense award DAMD W81XWH-06-1-0373 (WYT), the U.S. Environmental Protection Agency award RD-832141(FP), and the New York Community Trust (FP,RM, DT, JH). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: shuk-mei.ho@uc.edu . These authors contributed equally to this work. Introduction Asthma is the most common chronic childhood disease [1] and its risk may be strongly influenced by prenatal events [2]. Low income communities experience some of the highest childhood asthma rates in the U.S [3] and new preventive strategies are lacking due in part to the absence of predictive biomarkers. In our longitudinal cohort study of children residing in urban low- income, minority communities of New York City [4–6] the asthma rate exceeds 25% and is among the highest in the nation. Preliminary evidence suggests that transplacental exposure to polycyclic aromatic hydrocarbons (PAHs) derived largely from traffic-related air pollutants may be a risk factor for the early development of asthma-related symptoms in this cohort [5]. However, we could not rule out the possibility that postnatal exposure of children in this cohort to these pollutants may also contribute to the symptoms without additional studies. According to the hypothesis of the early origins of chronic disease, exposure to agents that are transmissible from mother to fetus has profound influences on the functional capacity and performance of many organs/tissues later in life [7–11]. Developmental plasticity allows the fetus to make anticipatory responses to the external environment by altering the course of cellular and organ differentiation in utero in order to gain adaptive advantages for later life challenges. However, a pronounced mismatch between ‘‘anticipatory adaptations’’ made during early life and demands in later life could be a cause of disease [10]. More importantly, environmental insults could ‘‘mislead’’ early PLoS ONE | www.plosone.org 1 February 2009 | Volume 4 | Issue 2 | e4488