DNA Methylomic Profiling of Preeclampsia Across Pregnancy

Preeclampsia (PE) is a hypertensive, multi-system disorder of pregnancy that significantly impacts maternal and infant morbidity/mortality across the globe, as it increases risk of cardiovascular disease and remains a leading killer of women and babies. Despite PE's significant impact on morbidity/mortality, there are no clinically reliable biomarkers that predict PE. DNA methylation, a dynamic regulator of gene expression, represents a mechanism that is known to be impacted by the environment. Because PE stems from a dysfunctional placenta that releases debris into the maternal circulation, we hypothesized that the in-vivo environment created by the dysfunctional placenta will impact DNA methylation in the maternal circulation, and that these blood-based methylation profiles would serve as a systemic biomarker of the maternal response to placental dysfunction. Our overall objective of this pilot study was to longitudinally characterize DNA methylation profiles across the three trimesters of pregnancy in the maternal blood at time points before and after clinically overt PE using a targeted (endoglin and endoglin-related genes) and a discovery-based approach. For this pilot study, 28 normotensive control participants and 28 PE case participants enrolled in the NICHD funded pregnancy study entitled Prenatal Exposures and Preeclampsia Prevention: Mechanisms of Preeclampsia and the Impact of Obesity (PEPP3; P01HD30367) were 1:1 frequency matched on self-reported race, pre-pregnancy BMI, smoking history, and gestational age at sample collection. Methylation data were collected with the Infinium® MethylationEPIC Beadchip. Methylation assay data collection were carried out at Johns Hopkins University Genetic Resources Core Facility, The SNP Center, Baltimore, MD, USA.]]>
This project capitalized on our unique collection of rigorously-characterized, archived samples originating from the NICHD funded pregnancy study entitled Prenatal Exposures and Preeclampsia Prevention: Mechanisms of Preeclampsia and the Impact of Obesity (PEPP3; P01HD30367). PEPP3 was conducted at the Magee-Womens Hospital of the University of Pittsburgh Medical Center from 2008-2014. The overarching purpose of PEPP3 was to investigate factors associated with obesity and PE. Given PEPP3's interest in obesity, recruitment of PEPP3 participants was weighted towards overweight and obese women who attended the Magee-Womens Hospital prenatal clinic. Overweight and obese women recruited from the prenatal clinic were also more likely to be African American, which is reflected in the racial distribution for this proposed study. The proposed study will utilize biologic samples and clinical/demographic data collected from participants who were enrolled in the longitudinal arm of the PEPP3 cohort. The longitudinal cohort included overweight/obese (BMI ≥ 25 kg/m2) and lean (BMI 19-25 kg/m2) participants who were enrolled at their first prenatal appointment (≤ 16 6/7ths weeks gestation) and followed through the postpartum period. PEPP3 inclusion criteria: 14-40 years of age, singleton pregnancy, and no past medical history of disorders associated with an increased risk of PE (e.g., chronic hypertension, diabetes, chronic renal disease). A peripheral blood sample, along with anthropometric measurements, vital signs, questionnaires (e.g., demographics, tobacco use, physical activity, diet), and a urine sample, were collected at each study visit across pregnancy. Additional inclusion criteria for the pilot study (DNA methylomic profiling of preeclampsia across pregnancy) included: available DNA sample for all three trimesters of pregnancy, ability to be 1:1 frequency matched to an appropriate PE case or normotensive control participant on self-reported race, pre-pregnancy BMI, smoking status, and gestational age at sample collection. Pregnancy outcome phenotypes: Pregnancy outcome classification was based on a rigorous review of clinical data and adjudication by an expert panel of clinicians and researchers. PE (case) was classified as new-onset gestational hypertension (HTN) and proteinuria in a previously normotensive woman after 20 weeks gestation. Gestational HTN was defined as the presence of absolute increases in BP that returned to baseline by 12 weeks postpartum (absolute BP criteria: systolic BP ≥ 140 mmHg and/or diastolic BP ≥ 90 mmHg). The average of the last four BPs taken in the hospital prior to therapeutic intervention (e.g., antihypertensive medication) were compared to the average BP prior to 20 weeks gestation. Proteinuria was defined as (1) ≥ 300mg/24 hours, (2) ≥ 0.3 protein/creatinine ratio, (3) ≥ 2+ on random urine specimen, or (4) ≥ 1+ on a catheterized urine specimen. Uncomplicated pregnancy (control) was identified when a clinically evaluated woman remained normotensive throughout gestation, did not develop proteinuria, and delivered a healthy infant. All control participants included in pilot study delivered at ≥ 37 weeks gestation. ]]>
Please see description provided under Inclusion/Exclusion Criteria.]]>