Abstract 4143335: Prenatal Dibutyl Phthalate Exposure Dysregulates Fetal-Placental Vascular Function and Spatial Transcriptomic Profile

Introduction: Fetal vascular dysfunction during pregnancy has long-term adverse effects on the cardiovascular health of the offspring. Prenatal exposure to dibutyl phthalate (DBP), is associated with adverse pregnancy/fetal outcomes and cardiovascular diseases in the offspring. To date, the impact of DBP exposure on fetal vascular function during pregnancies is unclear. Hypothesis: Environmentally relevant low-dosage DBP exposure during pregnancy differentially dysregulates fetal placental vascular function. Methods: Adult female CD-1 mice (10-12wks) were treated with vehicle (CT) or DBP at 0.1 μg/kg/day (DBP0.1) daily 30days before pregnancy through gestational day (GD) 18.5. Fetal-placental blood flow was measured non-invasively using a high-frequency ultrasound (Vevo3100, n=6-8dams/group). Spatial transcriptomic sequencing was performed using Visium (10xGenomics)&NovaSeq (Illumina) with GD18.5 placentas (n=3/fetal sex/group). Bioinformatic analysis was performed with SpaceRanger, Suerat and IPA software. Spatial gene expression validation and lipid disposition were performed with IHC and Oil Red O staining (n=6-8 litter/group). Results: DBP0.1 increased the fetal umbilical-placental velocity time integral (7.9±0.6mm vs. 6.5±0.8mm) at GD18.5. DBP0.1 decreased placental efficiency with more dramatic changes seen in female fetuses. Spatial transcriptomic analysis obtained 20,161 spatial-linked units from placentas from CT and DBP0.1 placentas (median: 140k reads&6,174 genes per unit). Bioinformatic analysis revealed 15 distinct clusters of units that were annotated to 10 different cell types (based on gene expression profiles) that precisely mapped to corresponding placental morphological structures. We identified vascular endothelial cells (ECs-1 [microvasculature]&ECs-2 [larger vasculature]) 2 populations in the fetal placental labyrinth. Pseudo-bulk analysis showed that DBP0.1 dysregulated 40 and 6 genes in ECs-1 from female and male placentas, respectively, but did not affect gene expression in ECs-2. Further, DBP0.1 dysregulates lipid metabolism-associated pathways only in female but not in male ECs-1. This is consistent with our Oil Red O data showing prenatal DBP0.1 exposure significantly decreased lipid disposition in the fetal labyrinth of female, but not in male placentas. Conclusions: Prenatal DBP0.1 exposure dysregulates fetal-placental blood flow velocity, placental efficiency, placental spatial transcriptomic profile and lipid disposition.