Comparison of Molecular Potential for Iron Transfer Across the Placenta in Domestic Pigs with Varied Litter Sizes and Wild Boars

Neonatal iron deficiency anemia is prevalent among domestic pigs but does not occur in the offspring of wild boar. The main causes of this disorder in piglets of modern pig breeds are paucity of hepatic iron stores, high birth weight, and rapid growth. Replenishment of fetal iron stores is a direct result of iron transfer efficiency across the placenta. In this study, we attempted to investigate the molecular potential of iron transfer across the placenta as a possible cause of differences between wild boar and Polish Large White (PLW) offspring. Furthermore, by analyzing placentas from PLW gilts that had litters of different sizes, we aimed to elucidate the impact of the number of fetuses on placental ability to transport iron. Using RNA sequencing, we examined the expression of iron-related genes in the placentas from wild boar and PLW gilts. We did not reveal significant differences in the expression of major iron transporters among all analyzed placentas. However, in wild boar placentas, we found higher expression of copper-dependent ferroxidases such as ceruloplasmin, zyklopen, and hephaestin, which facilitate iron export to the fetal circulation. We also determined a close co-localization of ceruloplasmin and zyklopen with ferroportin, the only iron exporter.