Characterization of Hofbauer cell polarization and VEGF localization in human term placenta from active and inactive pregnant individuals

Physical activity (PA) during pregnancy is associated with parental and fetal health benefits; however, the mechanisms through which these benefits arise are yet to be fully understood. In healthy pregnancies Hofbauer cells (HBCs) comprise a heterogenous population containing CD206+ and CD206− phenotypes. In healthy pregnancies, CD206+ represent the majority, while dysregulations have been associated with pathological conditions. HBCs have also been identified as potential drivers of angiogenesis. As PA induces changes in macrophage polarization in non‐pregnant populations, this novel study examined the relationship between PA and HBC polarization and to identify which HBC phenotypes express VEGF. Participants were classified as active or inactive, and immunofluorescence cell‐labelling was used to quantify total HBCs, CD206+ HBCs, and the proportion of total HBCs expressing CD206. Immunofluorescent colocalization assessed which phenotypes expressed VEGF. Protein and mRNA expression of CD68 and CD206 were measured in term placenta tissue using Western blot and RT‐qPCR, respectively. Both CD206+ and CD206− HBCs expressed VEGF. The proportion of CD206+ HBCs was elevated in active individuals; however, CD206 protein expression was observed to be lower in active participants. Combined with a lack of significant differences in CD206 mRNA levels, these findings suggest potential PA‐mediated responses in HBC polarization and CD206 translational regulation. In healthy pregnancies, placental macrophages, Hofbauer cells (HBCs) comprise a heterogenous population containing M1 and M2 phenotypes. This novel study aimed to examine the relationship between PA and HBC polarization and to identify which distinct HBC phenotypes express VEGF. We found that most HBCs were the M2 phenotype and all expressed VEGF.