Placenta-specific methylation of the vitamin D 24-hydroxylase gene: implications for feedback autoregulation of active vitamin D levels at the fetomaternal interface

Plasma concentrations of biologically active vitamin D (1,25- (OH)2D) are tightly controlled via feedback regulation of renal 1-hydroxylase (CYP27B1; positive) and 24-hydroxylase (CYP24A1; catabolic) enzymes. In pregnancy, this regulation is uncoupled, and 1,25-(OH)2D levels are significantly elevated, suggesting a role in pregnancy progression. Epigenetic regulation of CYP27B1 and CYP24A1 has previously been described in cell and animal models, and despite emerging evidence for a critical role of epigenetics in placentation generally, little is known about the regulation of enzymes modulating vitamin D homeostasis at the fetomaternal interface. In this study, we investigated the methylation status of genes regulating vitamin D bioavailability and activity in the placenta. No methylation of the VDR (vitamin D receptor) and CYP27B1 genes was found in any placental tissues. In contrast, the CYP24A1 gene is methylated in human placenta, purified cytotrophoblasts, and primary and cultured chorionic villus sampling tissue. No methylation was detected in any somatic human tissue tested. Methylation was also evident in marmoset and mouse placental tissue. All three genes were hypermethylated in choriocarcinoma cell lines, highlighting the role of vitaminDderegulation in this cancer. Gene expression analysis confirmed a reduced capacity for CYP24A1 induction with promoter methylation in primary cells and in vitro reporter analysis demonstrated that promoter methylation directly down-regulates basal promoter activity and abolishes vitamin D-mediated feedback activation. This study strongly suggests that epigenetic decoupling of vitamin D feedback catabolism plays an important role in maximizing active vitamin D bioavailability at the fetomaternal interface

Vitamin D prevents endothelial progenitor cell dysfunction induced by sera from women with preeclampsia or conditioned media from hypoxic placenta

Context: Placenta-derived circulating factors contribute to the maternal endothelial dysfunction underlying preeclampsia. Endothelial colony forming cells (ECFC), a sub-population of endothelial progenitor cells (EPCs), are thought to be involved in vasculogenesis and endothelial repair. Low vitamin D concentrations are associated with an increased risk for preeclampsia. Objective: We hypothesized that the function of human fetal ECFCs in culture would be suppressed by exposure to preeclampsia-related factors-preeclampsia serum or hypoxic placental conditioned medium- in a fashion reversed by vitamin D. Design, Setting, Patients: ECFCs were isolated from cord blood of uncomplicated pregnancies and expanded in culture. Uncomplicated pregnancy villous placenta in explant culture were exposed to either 2% (hypoxic), 8% (normoxic) or 21% (hyperoxic) O2 for 48 h, after which the conditioned media (CM) was collected. Outcome Measures: ECFC tubule formation (Matrigel assay) and migration were examined in the presence of either maternal serum from preeclampsia cases or uncomplicated pregnancy controls, or pooled CM, in the presence or absence of 1,25(OH)2 vitamin D3. Results: 1,25(OH)2 vitamin D3 reversed the adverse effects of preeclampsia serum or CM from hypoxic placenta on ECFCs capillary-tube formation and migration. Silencing of VDR expression by VDR siRNA, VDR blockade, or VEGF pathway blockade reduced ECFC functional abilities. Effects of VDR or VEGF blockade were partially prevented by vitamin D. Conclusion: Vitamin D promotes the capillary-like tubule formation and migration of ECFCs in culture, minimizing the negative effects of exposure to preeclampsia-related factors. Further evaluation of the role of vitamin D in ECFC regulation and preeclampsia is warranted. © 2014 Brodowski et al

Coxiella burnetii, the Agent of Q Fever, Replicates within Trophoblasts and Induces a Unique Transcriptional Response

Q fever is a zoonosis caused by Coxiella burnetii, an obligate intracellular bacterium typically found in myeloid cells. The infection is a source of severe obstetrical complications in humans and cattle and can undergo chronic evolution in a minority of pregnant women. Because C. burnetii is found in the placentas of aborted fetuses, we investigated the possibility that it could infect trophoblasts. Here, we show that C. burnetii infected and replicated in BeWo trophoblasts within phagolysosomes. Using pangenomic microarrays, we found that C. burnetii induced a specific transcriptomic program. This program was associated with the modulation of inflammatory responses that were shared with inflammatory agonists, such as TNF, and more specific responses involving genes related to pregnancy development, including EGR-1 and NDGR1. In addition, C. burnetii stimulated gene networks organized around the IL-6 and IL-13 pathways, which both modulate STAT3. Taken together, these results revealed that trophoblasts represent a protective niche for C. burnetii. The activation program induced by C. burnetii in trophoblasts may allow bacterial replication but seems unable to interfere with the development of normal pregnancy. Such pathophysiologocal processes should require the activation of immune placental cells associated with trophoblasts

Endoglin co-expression with eNOS, SMAD2 and phosphorylated SMAD23 in normocholesterolemic and hypercholesterolemic mice: an immunohistochemical study

Endoglin, a homodimeric transmembrane glycoprotein, is a part of the transforming growth factorß (TGF-ß) receptor cascade. It has been demonstrated that endoglin can affect TGF-ß signaling and eNOS expression by affecting SMAD proteins in vitro. We planned to go one step forward and evaluate whether endoglin is co-expressed with SMAD2, phosphorylated SMAD2/3 protein and eNOS in endothelium of normocholesterolemic C57BL/6J mice, and in advanced atherosclerotic lesions in hypercholesterolemic apoE/LDLr-deficient mice by means of fluorescence immunohistochemistry. Female C57BL/6J mice were fed with a chow diet (standard laboratory diet) for 12 weeks after weaning (at the age of 4 weeks). Two-month-old female apoE/LDLrdeficient mice were fed the western type diet (atherogenic diet) containing 21% fat (11% saturated fat) and 0.15% cholesterol for 2 months. Immunohistochemical analysis of endoglin, SMAD2, phosphorylated SMAD2/3 and eNOS expression was performed in mice aortic sinus. Immunohistochemical analysis showed the expression of endoglin in intact endothelium in both C57BL/6J and apoE/LDLr-deficient mice and in endothelium covering the atherosclerotic lesion in apoE/LDLr-deficient mice. Fluorescence immunohistochemistry revealed co-expression of endoglin with SMAD2, phosphorylated SMAD2/3 and eNOS in intact aortic endothelium in C57BL/6J mice. Moreover, strong co-localization of endoglin, SMAD2, phosphorylated SMAD2/3 and eNOS was also detected in endothelium covering atherosclerotic lesions in apoE/LDLr-deficient mice. In conclusion, we suggest that endoglin, SMAD2, phosphorylated SMAD2/3 and eNOS may be important in vessel endothelium homeostasis underlying their role in atherogenesis