593 - Placental DNA methylation differences in stress response and neurologic genes in opioid-exposed versus non-exposed pregnancies

Publication Number: 4581.593

Willa Molho, Boston University School of Medicine, Boston, MA, United States; Audrey Cantillon, Boston Medical Center, Brighton, MA, United States; Elizabeth Taglauer, Boston University School of Medicine, Boston, MA, United States; Sorraya Jaiprasert, Boston Medical Center, Boston, MA, United States; Huiping Zhang, Boston University School of Medicine, Boston, MA, United States; Elisha Wachman, Boston Medical Center, Newton, MA, United States

Background: Rates of opioid use disorder (OUD) in pregnancy are significantly increasing and can potentially impact pregnancy and neonatal outcomes. The placenta's susceptibility to exposures gives it the potential to help elucidate the mechanisms behind these effects. Recent studies highlight associations between epigenetics, specifically DNA methylation, and opioid exposed infant outcomes. However, there are few studies investigating the impact of OUD in pregnancy on epigenetic modification in stress-response-involved genes, which are known to be associated with differences in infant neurobehavior.

Objective: The primary goal of this study is to compare placental DNA methylation levels in targeted stress response and neurologic genes between opioid exposed and non-exposed pregnancies in a prospectively enrolled cohort.

Design/Methods: Pregnant individuals with and without OUD were enrolled at a single center. Fresh placental villous tissue samples were collected after delivery and analyzed using Targeted Next-Generation Bisulfite Sequencing (tNGBS). This process included bisulfite conversion, PCR amplification, and DNA sequencing with a custom DNA methylation panel covering 175 CpG sites across 11 genes (Table 1). Mean DNA methylation levels were compared between opioid-exposed and non-exposed groups using t-tests (p < 0.05 for point-wise significance; p< 0.0003 for experiment-wide significance, accounting for testing 180 CpG sites). Linear regression models were then applied to the top CpG sites, adjusting for relevant clinical covariates.

Results: 87 participants were included in the cohort, including 48 non-exposed and 39 opioid-exposed mother-infant dyads. Demographics and pregnancy outcomes (Table 2) showed notable differences in race and ethnicity, co-exposures, and breastfeeding. Across 175 CpG sites, 15 met point-wise significance (p < 0.05) in linear regression models (Table 3). In adjusted analyses, the opioid-exposed cohort showed hypermethylation at CpG sites in HSB11B2 and HTR1A, and hypomethylation in NR3C1 and OXT, compared with the non-exposed cohort. However, none of these CpG associations met experiment-wide significance.

Conclusion(s): This study provides initial evidence that prenatal opioid exposure is associated with placental DNA methylation changes in genes specifically involved in stress response. These epigenetic alterations may have implications for neonatal opioid withdrawal syndrome (NOWS) severity as well as infant neurobehavior and development. Future larger scale studies are needed to further elucidate the impact of prenatal opioid exposure on placental epigenetic modifications.

Table 1: Genes and Number of CpG Sites


Table 2: Maternal and Infant Demographics and Birth Outcomes
Abbreviations: GA = gestational age; MOUD = medication for opioid use disorder; SSRIs = selective serotonin reuptake inhibitors

Table 3: Top 15 CPG associations comparing opioid exposed and non-exposed placentas
Abbreviations: CpG = cytosine-guanine dinucleotide; MD = mean difference; CI = confidence interval
*Control group was used as the reference group; adjusted for infant sex and maternal race