Paternal obesity is associated with hypoxia and angiogenesis in female placenta and mediates placental development

Abstract

While the impacts of maternal obesity on placental development have been extensively studied, the role of the father’s health in regulating placentation is less understood. Paternal obesity is associated with offspring metabolic dysfunction, but the mechanism regulating this association is unclear. We investigated how paternal diet-induced obesity impacted placental vascular development, associated cellular stress pathways, and markers of placental endocrine function and macronutrient transport across gestation in a murine model. We found that paternal obesity is associated with placental hypoxia as measured by CAIX and HIF1α at E14.5 which persisted to E18.5. Hypoxia was associated with increased VEGF protein levels, as well as its pro-angiogenic receptor, VEGFR2 in male and female E14.5 placentae, although, this increase was apparent only in females at E18.5. The proportion of placental tissue that was immunopositive for the endothelial cell marker CD31 was increased in female but not male E18.5 placentae. Paternal obesity was associated with cellular stress as measured by the three branches of the unfolded protein response (UPR): ATF6, PERK, and IRE1α. However, despite increased phosphorylation of PERK and IRE1α in placental tissue derived from obese fathers, there was no impact on downstream signal transducers. Pro-apoptotic Bcl2 family members’ transcript levels were reduced at E18.5 in placentae from obese fathers, but this did not correspond to any changes in cleaved casp-3 protein levels. Placental lactogen and macronutrient transporter transcript levels were similar between groups across gestation, although Igf2 transcripts were increased in female placenta from obese fathers at both mid and late gestation. Thus, paternal obesity results in placental hypoxia and VEGF mediated sex specific changes in vascularization with a pro-angiogenic response occurring in females. Future studies will investigate whether paternal obesity impairs early placental implantation, resulting in poor vascularization and hypoxia at E18.5.