Folate transporter expression in placenta from pregnancies complicated with birth defects

Nutraceuticals in Pregnancy: A Special Focus on Probiotics

The placenta is crucial to fetal development and performs vital functions such as nutrient exchange, waste removal and hormone regulation. Abnormal placental development can lead to conditions such as fetal growth restriction, pre-eclampsia and stillbirth, affecting both immediate and long-term fetal health. Placental development is a highly complex process involving interactions between maternal and fetal components, imprinted genes, signaling pathways, mitochondria, fetal sexomes and environmental factors such as diet, supplementation and exercise. Probiotics have been shown to make a significant contribution to prenatal health, placental health and fetal development, with associations with reduced risk of preterm birth and pre-eclampsia, as well as improvements in maternal health through effects on gut microbiota, lipid metabolism, vaginal infections, gestational diabetes, allergic diseases and inflammation. This review summarizes key studies on the influence of dietary supplementation on placental development, with a focus on the role of probiotics in prenatal health and fetal development.

Altered placental immune cell composition and gene expression with isolated fetal spina bifida

PROBLEM

Fetal spina bifida (SB) is more common in pregnant people with folate deficiency or anomalies of folate metabolism. It is also known that fetuses with SB have a higher risk of low birthweight, a condition that is typically placental-mediated. We therefore hypothesized that fetal SB would associate with altered expression of key placental folate transporters and an increase in Hofbauer cells (HBCs), which are folate-dependent placental macrophages.

METHOD OF STUDY

Folate receptor-α (FRα), proton coupled folate receptor (PCFT), and reduced folate carrier (RFC) protein localization and expression (immunohistochemistry) and HBC phenotypes (HBC abundance and folate receptor-β [FRβ] expression; RNA in situ hybridization) were assessed in placentae from fetuses with SB (cases; n = 12) and in term (n = 10) and gestational age (GA) - and maternal body mass index - matched (n = 12) controls without congenital anomalies.

RESULTS

Cases had a higher proportion of placental villous cells that were HBCs (6.9% vs. 2.4%, p = .0001) and higher average HBC FRβ expression (3.2 mRNA molecules per HBC vs. 2.3, p = .03) than GA-matched controls. HBCs in cases were largely polarized to a regulatory phenotype (median 92.1% of HBCs). In sex-stratified analyses, only male cases had higher HBC levels and HBC FRβ expression than GA-matched controls. There were no differences between groups in the total percent of syncytium and stromal cells that were positive for FRα, PCFT, or RFC protein immunolabeling.

CONCLUSIONS

HBC abundance and FRβ expression by HBCs are increased in placentae of fetuses with SB, suggesting immune-mediated dysregulation in placental phenotype, and could contribute to SB-associated comorbidities.

Dexamethasone may inhibit placental growth by blocking glucocorticoid receptors via phosphatidylinositol 3-kinase/AKT/mammalian target of rapamycin and reactive oxygen species/AMP-activated protein kinase signalling pathways in human placental JEG-3 cells

This study explored the molecular mechanism underlying the effects of dexamethasone (DEX, 1µM) on glucose transporters (GLUT) in JEG-3 human placental choriocarcinoma cells. JEG-3 cells were treated with DEX, an expression plasmid encoding human glucocorticoid receptor α (GRα), pcDNA3.1-GRα, GRα short interference (si) RNA, LY294002, xanthine oxidase (XO)/hypoxanthine (HX), rapamycin, insulin-like growth factor (IGF) 1, N-acetylcysteine (NAC) or phosphatidic acid (PA), and cell proliferation, apoptosis, mitochondrial membrane potential (MMP), human chorionic gonadotrophin (hCG) content, human placental lactogen (hPL) content, glucose uptake, reactive oxygen species levels and signalling pathway modulation were evaluated. Treatment of JEG-3 cells with DEX (1µM), GRα siRNA, LY294002 (50µM), XO/HX (7.2µM/36nM) or rapamycin (80nM) inhibited cell proliferation, induced apoptosis, significantly decreased MMP and hCG and hPL content and increased ROS levels. In addition, glucose uptake was decreased through downregulation of the mRNA and protein expression of GRα, GLUT1 and GLUT3. Treatment of JEG-3 cells with GRα siRNA, LY294002, XO/HX or rapamycin inhibited phosphorylation of phosphatidylinositol 3-kinase (PI3K), Akt, glycogen synthase kinase 3 and mammalian target of rapamycin (mTOR) and induced the phosphorylation of AMP-activated protein kinase (AMPK) and tuberous sclerosis complex 2. The effects of GRα overexpression and IGF1 (100nM), NAC (5nM) or PA (100µM) treatment on JEG-3 cells contrasted with those of DEX treatment. DEX blocked glucose uptake by downregulating GRα expression, which reduced GLUT1 and GLUT3 mRNA and protein expression, which, in turn, may have inhibited the PI3K/AKT/mTOR pathway and activated the ROS/AMPK pathway.

Epigenetic regulation of folate receptor-α (FOLR1) in human placenta of preterm newborns

INTRODUCTION

Folates are essential nutrients for fetal development and pregnancy outcomes; they are transported to the fetus during gestation through specific folate transporters located in the placenta. In preterm newborns, we previously showed a lower placental mRNA expression of FOLR1 along with higher folate and lower vitamin B12 cord blood levels. Thereby we aimed to explore FOLR1 methylation in placentas of preterm newborns and hypothesized an increased FOLR1 methylation associated with cord blood folates and vitamin B12 concentrations.

METHODS

FOLR1 methylation and mRNA were determined by methylation sensitive - high resolution melting (MS-HRM) and by real-time PCR respectively, in two placental sides of placental tissues: maternal (basal, BP) and fetal plates (chorionic, CP) of moderate preterm infants (32-36 gestational age) and term birth (37-41 gestational weeks). Folates and vitamin B12 were determined by electrochemiluminescence in umbilical cord blood samples from term and preterm newborns.

RESULTS

We found that in preterm newborns, FOLR1 mRNA was lower in both plates of placenta compared with term newborns (p < 0,05) and was negatively associated with methylation of FOLR1 in CP. Preterm newborns presented higher folate and lower vitB12 concentrations in cord blood which correlated with increased placental FOLR1 methylation.

DISCUSSION

In preterm newborns, placental FOLR1 expression is regulated by epigenetic mechanisms and presumably by maternal concentrations of folate and vitamin B12.

Associations between the Level of Trace Elements and Minerals and Folate in Maternal Serum and Amniotic Fluid and Congenital Abnormalities

Congenital birth defects may result in a critical condition affecting the baby, including severe fetal/neonatal handicap and mortality. Several studies have shown that genetic, nutritional, and environmental factors may have an impact on fetal development and neonatal health. The relevance of essential and toxic elements on fetal development has not yet been fully investigated, and the results of recent research indicate that these elements may be crucial in the assessment of the risk of malformations in neonates. We determined the association between essential and toxic elements and the level of folate in maternal serum (MS) and amniotic fluid (AF), along with neonatal abnormalities. A total of 258 pregnant Polish women in the age group of 17⁻42 years participated in this study. AF and MS were collected during vaginal delivery or during cesarean section. An inductively coupled plasma mass spectrometry technique was used to determine the levels of various elements in AF and MS. The results of this exploratory study indicate that the levels of essential and toxic elements are associated with fetal and newborn anatomical abnormalities and growth disorders.