Feto-placental adaptations to maternal obesity in the baboon

Abstract

Maternal obesity is present in 20-34% of pregnant women and has been associated with both intrauterine growth restriction and large-for-gestational age fetuses. While fetal and placental functions have been extensively studied in the baboon, no data are available on the effect of maternal obesity on placental structure and function in this species. We hypothesize that maternal obesity in the baboon is associated with a maternal inflammatory state and induces structural and functional changes in the placenta. The major findings of this study were: 1) decreased placental syncytiotrophoblast amplification factor, intact syncytiotrophoblast endoplasmic reticulum structure and decreased system A placental amino acid transport in obese animals; 2) fetal serum amino acid composition and mononuclear cells (PBMC) transcriptome were different in fetuses from obese compared with non-obese animals; and 3) maternal obesity in humans and baboons is similar in regard to increased placental and adipose tissue macrophage infiltration, increased CD14 expression in maternal PBMC and maternal hyperleptinemia. In summary, these data demonstrate that in obese baboons in the absence of increased fetal weight, placental and fetal phenotype are consistent with those described for large-for-gestational age human fetuses.

Fig. 1

A. Maternal serum leptin (a), adiponectin (b), IL-6 (c), and VEGF (d) concentrations in non-obese (CTR, open bars, n=4) and obese (OB, gray, n=4) pregnant baboons at term (mean±SEM, *p<0.05 compared to non-obese group). B. Serum leptin (a), adiponectin (b), and glutamate (GLU) (c) concentrations in fetuses from non-obese (open bars, n=4) and obese (gray bars, n=4) mothers (Mean ± SEM, *p< 0.05 compared to non-obese group).

Fig. 2

A. Relative CD14 expression in maternal PBMCs, fetal and maternal visceral fat and placenta from non-obese (open bars, n=4) and obese (OB, gray bars, n=4) pregnant baboons at term (mean±SEM, *p<0.05 compared to non-obese group). B. Macrophage number in the intermediate villi (IV) and terminal villi (TV) of placentas from obese (filled bars, n=3) and non-obese (white bars, n=3) animals. CD68 immunostaining quantified by stereology (number of macrophages per villi section) (mean ± SEM, *p<0.05 compared to non-obese group).

Fig. 3

A. Representative photomicrographs of placental villi from (a) non-obese and (b) obese baboon placentas at 0.9 gestation. Magnification is 30,000×. B. Surface area amplification factor, microvilli length and diameter in placentas from non-obese (open bars; n=4) and obese (gray bars; n=4) mothers (*p<0.05 compared to non-obese group).