Expression and activity of vitamin D receptor in the human placenta and in choriocarcinoma BeWo and JEG-3 cell lines

Vitamin D receptor (VDR) mRNA overexpression is associated with poor prognosis in breast carcinoma

Purpose

The prognostic value of vitamin D receptor gene (VDR) expression in breast cancer development is unclear. Here, we aimed to investigate whether VDR expression can be used as a prognostic indicator of breast cancer.

Methods

We used various public bioinformatics platforms: Oncomine, GEPIA, UALCAN, Kaplan-Meier plotter, UCSC XENA, bc-GenExMiner, WebGestalt, and STRING database.

Results

We found that VDR was upregulated in breast cancer in comparison to normal tissues. Overexpression of VDR was significantly associated with worse overall survival in breast cancer. The expression of VDR was related to age, TNM stages, estrogen receptor status, progesterone receptor status, human epidermal growth factor receptor 2 status, basal-like (PAM 50) status, triple-negative breast cancer (TNBC) status, and basal-like (PAM 50) & TNBC status (P < 0.05). Increased VDR expression in breast cancer was significantly associated with older age. The 5 hub genes for VDR were NCOA1, EP300, CREBBP, and RXRA.

Conclusion

Our investigation offers hints about the prognostic role of VDR in breast cancer. The findings suggest that VDR expression might be used as a marker to determine a breast cancer patient's prognosis. Nevertheless, further validation is warranted.

Sex-differential RXRα gene methylation effects on mRNA and protein expression in umbilical cord of the offspring rat exposed to maternal obesity

Maternal obesity (MO) induces negative consequences in the offspring development. Adiposity phenotype is associated with maternal diet at early pregnancy and DNA methylation marks in the RXRα promotor at birth. Glucocorticoids play an important role in the regulation of metabolism through the activation of nuclear hormone receptors such as the RXRα protein. The aim of the study was to analyze steroid hormone changes at the end of pregnancy in the obese mother and RXRα gene methylation in the umbilical cord. For this purpose, in a well-established MO model, female Wistar rats were fed either standard chow (controls: C) or high-fat obesogenic diet (MO) before and during pregnancy to evaluate at 19 days of gestation (19 dG): 1) maternal concentration of circulating steroid hormones in MO and C groups, 2) maternal and fetal weights, 3) analysis of correlation between hormones concentration and maternal and fetal weights, 4) DNA methylation status of a single locus of RXRα gene near the early growth response (EGR-1) protein DNA binding site, and 5) RXRα mRNA and protein expressions in umbilical cords. Our results demonstrate that at 19 dG, MO body weight before and during pregnancy was higher than C; MO progesterone and corticosterone serum concentrations were higher and estradiol lower than C. There were not differences in fetal weight between male and female per group, therefore averaged data was used; MO fetal weight was lower than C. Positive correlations were found between progesterone and corticosterone with maternal weight, and estradiol with fetal weight, while negative correlation was observed between corticosterone and fetal weight. Additionally, male umbilical cords from MO were hypermethylated in RXRα gene compared to male C group, without differences in the female groups; mRNA and protein expression of RXRα were decreased in F1 male but not in female MO compared to C. In conclusion, MO results in dysregulation of circulating steroid hormones of the obese mothers and low fetal weight in the F1, modifying DNA methylation of RXRα gene as well as RXRα mRNA and protein expression in the umbilical cord in a sex-dependent manner.

Vitamin D-Related Risk Factors for Maternal Morbidity during Pregnancy: A Systematic Review

Vitamin D has well-defined classical functions related to metabolism and bone health but also has non-classical effects that may influence pregnancy. Maternal morbidity remains a significant health care concern worldwide, despite efforts to improve maternal health. Nutritional deficiencies of vitamin D during pregnancy are related to adverse pregnancy outcomes, but the evidence base is difficult to navigate. The primary purpose of this review is to map the evidence on the effects of deficiencies of vitamin D on pregnancy outcome and the dosage used in such studies. A systematic search was performed for studies on vitamin D status during pregnancy and maternal outcomes. A total of 50 studies came from PubMed, 15 studies came from Cochrane, and 150 studies came from Embase, for a total of 215 articles. After screening, 34 were identified as candidate studies for inclusion. Finally, 28 articles met the inclusion criteria, which originated from 15 countries. The studies included 14 original research studies and 13 review studies conducted between 2012 and 2021. This review was finally limited to the 14 original studies. This systematic review was conducted according to the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines, and the quality and strength of the evidence was evaluated using the Navigation Guide Systematic Review Methodology (SING). We found evidence that supports the idea that supplementary vitamin D for pregnant women is important for reducing the risk of gestational diabetes, hypertension, preeclampsia, early labor, and other complications. The data retrieved from this review are consistent with the hypothesis that adequate vitamin D levels might contribute to a healthy pregnancy.

The Influence of Maternal Vitamin D Supplementation in Pregnancies Associated with Preeclampsia: A Case-Control Study

Preeclampsia is a pregnancy-specific illness that is hypothesized to occur due to vitamin D deficiency during pregnancy. Therefore, vitamin D supplementation in early pregnancy should be explored for preventing preeclampsia and promoting neonatal well-being. The present study follows a case-control analysis that aims to determine the effect of vitamin D supplements on reducing the probability of recurrent preeclampsia. We identified 59 patients for the control group without vitamin D supplementation during pregnancy, while 139 patients were included in the cases group of pregnant women with a history of preeclampsia who confirmed taking daily vitamin D supplements in either 2000 UI or 4000 UI until the 36th week of pregnancy. There were 61 (80.3%) patients with a normal serum vitamin D level measured at 32 weeks in the pregnant women who took a daily dose of 4000 UI vitamin D and 43 (68.3%) in those who took a 2000 UI dose of vitamin D, compared to just 32 (54.2%) in those who did not take vitamin D at all. Regarding the blood pressure of pregnant women measured at 32 weeks, it was observed that 20.3% were hypertensive in the no supplementation group, compared to only 11.1% and 6.6% in those who were taking vitamin D during pregnancy (p-value = 0.049). Serum vitamin D levels at 32 weeks were measured at an average value of 23.9 ng/mL, compared with 28.4 ng/mL in the group taking a 2000 UI daily dose and 33.6 in those who supplemented with 4000 UI daily (p-value < 0.001). Proteinuria was identified more often in the group at risk for preeclampsia who did not take vitamin D supplements, while systolic blood pressure (p-value = 0.036) as well as diastolic blood pressure (p-value = 0.012), were all identified to have significantly higher values in the pregnant women with a history of preeclampsia that did not take vitamin D during the current pregnancy. The significant risk factors for preeclampsia development in pregnant patients at risk are: insufficient vitamin D serum levels (<20 ng/mL), OR = 2.52; no vitamin D supplementation, OR = 1.46; more than two pregnancies, OR = 1.89; gestational diabetes mellitus, OR = 1.66; and cardiovascular comorbidities, OR = 2.18. These findings imply that vitamin D has a role in the preservation of placental function and, therefore, in the prevention of the development of late preeclampsia. Pregnant mothers who supplemented their diets with vitamin D were protected against preeclampsia recurrence. Vitamin D supplementation during pregnancy may aid in the prevention of gestational hypertension and preeclampsia.

Effect of 1,25(OH)2-vitamin D3 on decidualization of human endometrial stromal cells

Decidualization is the differentiation of endometrial stromal cells (eSC) to rounded, epithelioid-like cells during menstrual cycle and pregnancy. The impairment of this process leads to infertility and a variety of pregnancy disorders, including recurrent miscarriages and uteroplacental disorders. The aim of this study was to evaluate the effect of 1,25(OH)2-vitamin D3 (VD) on transformation of primary eSC into decidual cells. After isolation of eSC from biopsy samples of healthy fertile women and their characterization, the cells were cultured and propagated, and confluent cultures were decidualized for 12 days with progesterone (P4) and estradiol (E2) in presence or absence of VD. Prolactin (PRL) concentration was measured every 48 h in culture medium of eSCs, and ultrastructural changes were evaluated at the end of treatment. The results showed that PRL concentration in culture medium of eSCs was significantly increased in VD-treated decidual cells compared to control groups in a time-dependent manner. Ultrastructural analysis demonstrated that VD enhances many of the ultrastructural changes of decidualized cells including expansion of rough endoplasmic reticulum (rER), increased lipid droplets and high number of euchromatin round nuclei. These results suggest that VD may play an important role during early pregnancy by promoting cellular transformation associated with decidualization.

Impact of vitamin D on human embryo implantation-a prospective cohort study in women undergoing fresh embryo transfer

OBJECTIVE

To measure free and total 25-hydroxyvitamin D [25(OH)D] immediately before embryo transfer and analyze its association with early pregnancy outcome parameters such as biochemical pregnancy, implantation rate, and clinical pregnancy rates in women undergoing fresh embryo transfer after their first ovarian hyperstimulation.

DESIGN

Prospective cohort study.

SETTING

Academically affiliated private fertility center.

PATIENT(S)

A total of 2,569 women undergoing fresh embryo transfer after ovarian hyperstimulation.

INTERVENTIONS(S)

None.

MAIN OUTCOME MEASURE(S)

The study end points were biochemical pregnancy rate, implantation rate, clinical pregnancy rate, ectopic pregnancy rate, early miscarriages, and ongoing pregnancy rate. Free and total 25(OH)D concentrations were measured 1 day before embryo transfer.

RESULT(S)

Total 25(OH)D correlated with free 25(OH)D. Total and free 25(OH)D serum concentrations were similar in those patients reaching and not reaching the study outcomes (biochemical pregnancy rate, implantation rate, clinical pregnancy rate, ectopic pregnancy rate, early miscarriages, and ongoing pregnancy rate). There was likewise no statistical difference when analyzing the frequency of all study outcomes in quintiles of either total or free 25(OH)D. In addition, the study population was divided into three groups according to the total vitamin D status based on clinical practice guideline. All outcomes were similar in women with adequate, insufficient, and deficient total 25(OH)D. Multiple linear regression analysis considering confounding likewise indicated no association of free or total vitamin D with any of the study outcomes.

CONCLUSION(S)

Neither free nor total 25(OH)D concentration at embryo transfer was associated with successful embryo implantation in women undergoing fresh transfer after ovarian hyperstimulation.

Investigating a suitable model for the study of vitamin D mediated regulation of human placental gene expression

Transfer and metabolism of vitamin D across the human placenta is required for fetal development. However, these fundamental mechanisms are not well understood and model systems are required to help understand them. The BeWo choriocarcinoma cell line is derived from extravillous trophoblast but is used as a model for villous syncytiotrophoblast and the placental barrier. Questions have been raised about the suitability of the BeWo cell line as a model for villous trophoblast. This study compares the expression of amino acid transporters and vitamin D related genes in human term placenta with the BeWo and human embryonic kidney (HEK)293 cell lines. HEK293 cells, as transporting epithelium may be more similar to placenta. Gene expression in term placenta was much more similar to HEK293 than BeWo. This study provides further evidence that the BeWo cell line is not an appropriate model for villous trophoblast and a model that more closely represents the human placenta is now required to investigate the effects of vitamin D on the placenta ex-vivo.

The role of xenobiotic-metabolizing enzymes in the placenta: a growing research field

Introduction: The placenta is a temporary and unique organ that allows for the physical connection between a mother and fetus; this organ regulates the transport of gases and nutrients mediating the elimination of waste products contained in the fetal circulation. The placenta performs metabolic and excretion functions, on the basis of multiple enzymatic systems responsible for the oxidation, reduction, hydrolysis, and conjugation of xenobiotics. These mechanisms give the placenta a protective role that limits the fetal exposure to harmful compounds. During pregnancy, some diseases require uninterrupted treatment even if it is detrimental to the fetus. Drugs and other xenobiotics alter gene expression in the placenta with repercussions for the fetus and mother's well-being.Areas covered: This review provides a brief description of the human placental structure and function, the main drug and xenobiotic transporters and metabolizing enzymes, placenta-metabolized substrates, and alterations in gene expression that the exposure to xenobiotics may cause.Expert opinion: Research should be focused on the identification and validation of biological markers for the assessment of the harmful effects of some drugs in pregnancy, including the evaluation of polymorphisms and methylation patterns in chorionic villous samples and/or amniotic fluid.

Roles of vitamin D and its receptor in the proliferation and apoptosis of luteinised granulosa cells in the goat

The objective of this study was to investigate the dose-dependent effect of 1α,25-(OH)2VD3 (Vit D3) on invitro proliferation of goat luteinised granulosa cells (LGCs) and to determine the underlying mechanisms of its action by overexpressing and silencing vitamin D receptor (VDR) in LGCs. Results showed that VDR was prominently localised in GCs and theca cells (TCs) and its expression increased with follicle diameter, but was lower in atretic follicles than in healthy follicles. The proliferation rate of LGCs was significantly higher in the Vit D3-treated groups than in the control group, with the highest proliferation rate observed in the 10nM group; this was accompanied by changes in the expression of cell cycle-related genes. These data indicate that Vit D3 affects LGC proliferation in a dose-dependent manner. Contrary to the VDR knockdown effects, its overexpression upregulated and downregulated cell cycle- and apoptosis-related genes respectively; moreover, supplementation with 10nM of Vit D3 significantly enhanced these effects. These results suggest that changes in VDR expression patterns in LGCs may be associated with follicular development by regulation of cell proliferation and apoptosis. These findings will enhance the understanding of the roles of Vit D3 and VDR in goat ovarian follicular development.

Role of vitamin D in cell-cell interaction of fetal endothelial progenitor cells and umbilical cord endothelial cells in a preeclampsia-like model

Maternal endothelial dysfunction is a cental feature of preeclampsia (PE), a hypertensive disorder of pregnancy. Factors in the maternal circulation are thought to contribute to this endothelial dysfunction. Although understudied, factors in the fetal circulation may influence fetal endothelial cell interactions with endothelial progenitor cells as critical steps in placental angiogenesis. We hypothesize that cell-cell interactions that are important for pregnancy health are impaired by fetal serum from PE pregnancies and that 1,25(OH)₂-vitamin D₃ attenuates the negative effects of this serum on cell function. We tested the ability of fetal cord blood-derived endothelial progenitor cells [endothelial colony-forming cells (ECFCs)] to invade into established monolayers and capillary tubule-like structures of human fetal umbilical venous endothelial cells (HUVECs), while in the presence/absence of fetal cord serum from uncomplicated or PE pregnancies, and tested the ability of 1,25(OH)₂-vitamin D₃ to modulate the serum-mediated effects. PE cord serum reduced the invasion of fetal ECFCs into HUVEC monolayers or tubule networks. Vitamin D attenuated these effects of PE fetal serum on endothelial functional properties. Immunocytochemical studies revealed involvement of VE-cadherin contacts in interactions between ECFCs and mature fetal endothelial cells. PE cord serum reduces the ability of fetal endothelial progenitor cells to incorporate into fetal endothelial cell networks. Physiologic concentrations of vitamin D reverse these PE serum-mediated effects. These data appear consistent with lines of evidence that vitamin D has antipreeclampsia effects.

The possible role of maternal and placental vitamin D receptor polymorphisms and haplotypes in pathogenesis of preeclampsia

Purpose: Vitamin D deficiency may be a main causative agent in the pathogenesis of preeclampsia (PE). The actions of the active form of vitamin D are mediated via the vitamin D receptor (VDR), which is expressed in numerous organs including placenta. Therefore, we evaluated the potential relationship between maternal and placental VDR polymorphisms and the predisposition to PE in an Iranian population.Methods: This case-control study surveyed 152 PE and 160 normotensive pregnant women. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was performed to examine the maternal and placental VDR Fok1 rs2228570, Bsm1 rs1544410, Taq1 rs731236, and Apa1 rs7975232 polymorphisms.Results: The maternal but not placental VDR FokI Ff genotype, was significantly lower in PE women (P = .02 and P = .06, respectively). The maternal and placental VDR FokI polymorphism was associated with lower PE risk in the dominant model (Ff+ff vs. FF) and these genotypes could decrease PE risk (OR, 0.5 [95% CI, 0.3-0.8], P = .007 and OR, 0.5 [95% CI, 0.3-0.9], P = .02, respectively). The haplotype analysis revealed that the maternal and placental TABf haplotype may lead to decreased risk of PE. In addition, the placental TABF haplotype was associated with higher risk of PE. No relationship was observed between PE susceptibility and the maternal and placental VDR Bsm1, Taq1 and Apa1 polymorphisms. There was also no relationship between the maternal and placental VDR polymorphisms and PE severity.Conclusions: the maternal and placental VDR FokI variant was associated with decreased risk of PE in the dominant model.

Polymorphisms and haplotypes in VDR gene are associated with female idiopathic infertility

Unexplained infertility refers to the absence of a definable cause of reproductive failure. Vitamin D receptor (VDR) acts as a transcription factor and regulates a number of vitamin D-responsive genes, including those involved in the immune system. Recent finding that VDR is expressed in reproductive tissues suggests a possible importance of vitamin D in pregnancy. We conducted a case-control study to examine the association of polymorphisms in VDR gene with reproductive success. DNA from 117 female patients with unexplained infertility and 130 fertile controls was isolated from peripheral blood and VDR genotypes (FokI, BsmI, ApaI and TaqI) were detected by PCR-RFLP. Haplotypes were determined using Haploview software. Our results show significant association of FokI and BsmI polymorphisms with infertility (p < 0.05). The haplotype analysis confirmed strong linkage disequilibrium between closely positioned BsmI, ApaI and TaqI polymorphisms. Two haplotypes were associated with infertility: (i) haplotype bAT was increasing the risk for secondary infertility; while (ii) haplotype BAT had a protective role against primary infertility (p < 0.05). By changing the expression and the activity of VDR gene, which leads to the change in expression of vitamin D-responsive genes, these polymorphisms and haplotypes could possibly have an effect on immune system in the female reproductive tract.

Expression of Concentrative Nucleoside Transporters ( SLC28A) in the Human Placenta: Effects of Gestation Age and Prototype Differentiation-Affecting Agents

Equilibrative ( SLC29A) and concentrative ( SLC28A) nucleoside transporters contribute to proper placental development and mediate uptake of nucleosides/nucleoside-derived drugs. We analyzed placental expression of SLC28A mRNA during gestation. Moreover, we studied in choriocarcinoma-derived BeWo cells whether SLC29A and SLC28A mRNA levels can be modulated by activity of adenylyl cyclase, retinoic acid receptor activation, CpG islands methylation, or histone acetylation, using forskolin, all- trans-retinoic acid, 5-azacytidine, and sodium butyrate/sodium valproate, respectively. We found that expression of SLC28A1, SLC28A2, and SLC28A3 increases during gestation and reveals considerable interindividual variability. SLC28A2 was shown to be a dominant subtype in the first-trimester and term human placenta, while SLC28A1 exhibited negligible expression in the term placenta only. In BeWo cells, we detected mRNA of SLC28A2 and SLC28A3. Levels of the latter were affected by 5-azacytidine and all- trans-retinoic acid, while the former was modulated by sodium valproate (but not sodium butyrate), all- trans-retinoic acid, 5-azacytidine, and forskolin that caused 25-fold increase in SLC28A2 mRNA; we documented by analysis of syncytin-1 that the observed changes in SLC28A expression do not correlate with the morphological differentiation state of BeWo cells. Upregulated SLC28A2 mRNA was reflected in elevated uptake of [³H]-adenosine, high-affinity substrate of concentrative nucleoside transporter 2. Using KT-5720 and inhibitors of phosphodiesterases, we subsequently confirmed importance of cAMP/protein kinase A pathway in SLC28A2 regulation. On the other hand, SLC29A genes exhibited constitutive expression and none of the tested compounds increased SLC28A1 expression to detectable levels. In conclusion, we provide the first evidence that methylation status and activation of retinoic acid receptor affect placental SLC28A2 and SLC28A3 transcription and substrates of concentrative nucleoside transporter 2 might be taken up in higher extent in placentas with overactivated cAMP/protein kinase A pathway and likely in the term placenta.

Vitamin D, the placenta and early pregnancy: effects on trophoblast function

Pregnancy is associated with significant changes in vitamin D metabolism, notably increased maternal serum levels of active vitamin D, 1,25-dihydroxyvitamin (1,25(OH)₂D). This appears to be due primarily to increased renal activity of the enzyme 25-hydroxyvitamin D-1α-hydroxylase (CYP27B1) that catalyzes synthesis of 1,25(OH)₂D, but CYP27B1 expression is also prominent in both the maternal decidua and fetal trophoblast components of the placenta. The precise function of placental synthesis of 1,25(OH)₂D remains unclear, but is likely to involve localized tissue-specific responses with both decidua and trophoblast also expressing the vitamin D receptor (VDR) for 1,25(OH)₂D. We have previously described immunomodulatory responses to 1,25(OH)₂D by diverse populations of VDR-expressing cells within the decidua. The aim of the current review is to detail the role of vitamin D in pregnancy from a trophoblast perspective, with particular emphasis on the potential role of 1,25(OH)₂D as a regulator of trophoblast invasion in early pregnancy. Vitamin D deficiency is common in pregnant women, and a wide range of studies have linked low vitamin D status to adverse events in pregnancy. To date, most of these studies have focused on adverse events later in pregnancy, but the current review will explore the potential impact of vitamin D on early pregnancy, and how this may influence implantation and miscarriage.

Oral Supplementation of Parturient Mothers with Vitamin D and Its Effect on 25OHD Status of Exclusively Breastfed Infants at 6 Months of Age: A Double-Blind Randomized Placebo Controlled Trial

BACKGROUND

Exclusively breastfed infants are at increased risk of vitamin D deficiency and many lactating mothers have been found deficient in 25OHD stores.

OBJECTIVE

To compare serum vitamin D levels in exclusively breastfed infants at 6 months of age with or without oral supplementation of 600,000 IU of vitamin D3 to mothers in early postpartum period.

METHODS

Exclusively breastfeeding term parturient mothers were randomized 24-48 hours following delivery to receive either 600,000 IU of vitamin D3 (Cholecalciferol) over 10 days in a dose of 60,000 IU/day or placebo. 25OHD levels were measured by Radio Immuno Assay method at recruitment and after 6 months in all mothers and their infants. Urinary calcium and creatinine ratio was measured to monitor adverse effects of vitamin D3 in both mothers and infants at 14 weeks and 6 months of age. X-ray of both wrists in anteroposterior view and serum alkaline phosphatase of infants were done in both groups at 6 months of age to look for evidence of rickets.

RESULTS

Maternal profile was similar in intervention (A) and control (B) groups. Mothers' serum 25OHD levels at recruitment were also similar being 16.2 ± 9.3 ng/mL in group A and 14.1 ± 7.1 ng/mL in group B. After 6 months, 25OHD levels were 40.3 ± 21.6 and 22.9 ± 20.1 ng/mL in group A and group B mothers (p ≤ 0.00), respectively. The serum 25OHD levels in cord blood were 9.9 ± 5.7 and 8.9 ± 5.1 ng/mL, respectively, in infants born to mothers in intervention and control groups (p = 0.433). At 6 months of age, the serum 25OHD levels significantly (p < 0.00) raised to 29.1 ± 14.6 ng/mL in infants of group A compared to those of group B (15.7 ± 17.7 ng/mL). Four infants developed radiological rickets at 6 months of age, two infants each in intervention group and study group. As against 10 infants in the control group (16.94%), no infant in the study group had biochemical rickets. Urinary calcium and creatinine ratio in mothers and infants at 14 weeks and 6 months of age in both intervention and study group was within normal limits, indicating there was no adverse effects of oral administration of 600,000 IU of vitamin D3.

CONCLUSION

Serum 25OHD levels of exclusively breastfed infants significantly rise at 6 months of age when their mothers are orally supplemented with 60,000 IU of vitamin D3 daily for 10 days in the early postpartum period in comparison to infants of vitamin D3 unsupplemented mothers.

Role of Placental VDR Expression and Function in Common Late Pregnancy Disorders

Vitamin D, besides its classical role in bone metabolism, plays a distinct role in multiple pathways of the feto-maternal unit. Calcitriol is the major active ligand of the nuclear vitamin D receptor (VDR). The vitamin D receptor (VDR) is expressed in different uteroplacental parts and exerts a variety of functions in physiologic pregnancy. It regulates decidualisation and implantation, influences hormone secretion and placental immune modulations. This review highlights the role of the vitamin D receptor in physiologic and disturbed pregnancy, as preeclampsia, fetal growth restriction, gestational diabetes and preterm birth. We discuss the existing literature regarding common VDR polymorphisms in these pregnancy disorders.

Altered metabolic homeostasis between vitamin D and long chain polyunsaturated fatty acids in preeclampsia

Sub-optimal maternal nutrition may result in pregnancy complications like preeclampsia. Preeclampsia is known to be of placental origin and a major cause of maternal morbidity and mortality worldwide. Our earlier studies suggest that altered metabolism of folic acid, vitamin B₁₂ and long chain polyunsaturated fatty acid (LCPUFAs) in the one carbon cycle increases homocysteine levels in preeclampsia. Recent reports indicate that vitamin D deficiency may also have a role in preeclampsia, although the mechanisms are unclear. A disturbed one carbon cycle can influence methylation patterns of various genes involved in placental development. Altered expression of cystathionine beta synthase (CBS) gene can result in hyperhomocystenemia. Higher homocysteine levels are known to increase reactive oxygen species (ROS) production which in turn leads to increased expression of phospholipase A2 (PLA2) and cyclooxygenase-2 (COX-2). Higher expression of PLA2 and COX-2 can influence the release of arachidonic acid (AA) from membrane phospholipid and result in increased conversion to thromboxane. Vitamin D [1,25(OH)₂D₃] is known to induce the CBS gene expression while it can suppress the oxidative stress-induced COX-2 up-regulation and thromboxane production. Based on this, we propose a novel hypothesis that a disturbed vitamin D and LCPUFA metabolism influence the regulation of the one carbon cycle which will trigger inflammation through oxidative stress in preeclampsia. This may lead to altered feto-placental growth and development in preeclampsia.

Inhibitory Effects of Quercetin on Progression of Human Choriocarcinoma Cells Are Mediated Through PI3K/AKT and MAPK Signal Transduction Cascades

As a major dietary flavonol, quercetin mitigates proliferation and progression of cancer due to its anti-angiogenic, anti-inflammatory, anti-oxidant, and apoptotic biological effects on cells. Although its apoptotic effects have been reported for various cancers, little is known of the functional role of quercetin in gestational choriocarcinoma. Results of the present study indicated that quercetin reduced proliferation and induced cell death in two choriocarcinoma cell lines, JAR and JEG3 cells, with an increase in the sub-G₁ phase of the cell cycle. In addition, quercetin induced mitochondrial dysfunction significantly reduced mitochondrial membrane potential (MMP) and increased production of reactive oxygen species (ROS) in both JAR and JEG3 cells. Further, quercetin inhibited phosphorylation of AKT, P70S6K and S6 proteins whereas, it increased phosphorylation of ERK1/2, P38, JNK and P90RSK proteins in JAR and JEG3 cells. The decrease in viability of choriocarcinoma cells treated with quercetin was confirmed by using combinations of quercetin and pharmacological inhibitors of the PI3K and MAPK signaling pathways. Classical chemotherapeutic agents, cisplatin (a platinum-based drug) and paclitaxel (a taxene-based drug), inhibited proliferation of JAR and JEG3 cells, and when combined with quercetin, the antiproliferative effects of cisplatin and paclitaxel were enhanced for both choriocarcinoma cell lines. Collectively, these results suggest that quercetin prevents development of choriocarcinoma and may be a valuable therapeutic agent for treatment of choriocarcinoma through its regulation of PI3K and MAPK signal transduction pathways. J. Cell. Physiol. 232: 1428-1440, 2017. © 2016 Wiley Periodicals, Inc.

Decreased expression of the vitamin D receptor in women with recurrent pregnancy loss

The multiple functions of vitamin D3 have stimulated interest in the role that this vitamin may play during pregnancy. The present study investigated the expression of the vitamin D receptor (VDR) in women during the first trimester of pregnancy in order to determine whether VDR is associated with recurrent pregnancy loss (RPL). Forty women at 7-10 weeks gestation with RPL and 40 women of similar gestational age with a healthy pregnancy were recruited. VDR mRNA and protein in chorionic villi and decidua were evaluated by immunohistochemistry, confocal laser scanning microscopy (CLSM), western blot, and quantitative real-time polymerase chain reaction. The serum levels of VDR were measured by an enzyme-linked immunosorbent assay. Women with RPL had a significantly weaker expression of VDR mRNA in villi and decidual tissues compared with the control women (both p < 0.0001). Western blot analysis showed an approximately 46% decrease in VDR expression in villi and a 52% decrease in decidua in the RPL vs. the controls. Serum VDR levels were also significantly lower in the RPL group than in the control group (p = 0.003). Compared with the controls, immunohistochemical and CLSM analysis revealed significantly lower VDR expression in villous cytotrophoblasts and stromal cells, as well as in decidual glandular epithelial and stromal cells (all p < 0.05). In conclusion, these observations show that women with RPL have lower levels of VDR expression in chorionic villi, decidua and serum compared with normal pregnant women, suggesting that decreased VDR expression in the first trimester pregnancy may be associated with RPL.

Green tea (-)-epigallocatechin gallate inhibits the growth of human villous trophoblasts via the ERK, p38, AMP-activated protein kinase, and protein kinase B pathways

Green tea catechins, especially (-)-epigallocatechin gallate (EGCG), have been reported to circulate in the placenta of animals and blood of humans after consumption. Whether EGCG regulates activity of human villous trophoblasts (HVT) is unknown. This study investigated the pathways involved in EGCG modulation of trophoblast mitogenesis. EGCG inhibited trophoblast proliferation in a dose-dependent and time-dependent manner, as indicated by the number of cells and incorporation of bromodeoxyuridine (BrdU). EGCG was more effective than other green tea catechins in inhibiting cell growth. EGCG also increased the phosphorylation of the MAPK pathway proteins, ERK1/2, and p38, but not JNK. Furthermore, EGCG had no effects on the total amounts of ERK1/2, p38 MAPK, and JNK proteins. This suggests that EGCG selectively affects particular MAPK subfamilies. Pretreatment with specific inhibitors of ERK1/2, p38 MAPK, and AMP-activated protein kinase (AMPK) antagonized EGCG-induced decreases in both cell number and BrdU incorporation. These inhibitors also blocked EGCG-induced increases in the levels of phospho-ERK1/2, phospho-p38, and phospho-AMPK proteins, respectively. Moreover, EGCG was similar to the phosphatidylinositol 3-kinase inhibitors wortmannin and LY-294002 to decrease protein kinase B (AKT) phosphorylation, cell number, and BrdU incorporation. These data imply that EGCG inhibits the growth of HVT through the ERK, p38, AMPK, and AKT pathways.

Role of the Placental Vitamin D Receptor in Modulating Feto-Placental Growth in Fetal Growth Restriction and Preeclampsia-Affected Pregnancies

Fetal growth restriction (FGR) is a common pregnancy complication that affects up to 5% of pregnancies worldwide. Recent studies demonstrate that Vitamin D deficiency is implicated in reduced fetal growth, which may be rescued by supplementation of Vitamin D. Despite this, the pathway(s) by which Vitamin D modulate fetal growth remains to be investigated. Our own studies demonstrate that the Vitamin D receptor (VDR) is significantly decreased in placentae from human pregnancies complicated by FGR and contributes to abnormal placental trophoblast apoptosis and differentiation and regulation of cell-cycle genes in vitro. Thus, Vitamin D signaling is important for normal placental function and fetal growth. This review discusses the association of Vitamin D with fetal growth, the function of Vitamin D and its receptor in pregnancy, as well as the functional significance of a placental source of Vitamin D in FGR. Additionally, we propose that for Vitamin D to be clinically effective to prevent and manage FGR, the molecular mechanisms of Vitamin D and its receptor in modulating fetal growth requires further investigation.

Long-term administration of tenofovir or emtricitabine to pregnant rats; effect on Abcb1a, Abcb1b and Abcg2 expression in the placenta and in maternal and fetal organs

OBJECTIVES

Tenofovir and emtricitabine are very effective and well-tolerated antiretrovirals representing current backbone of the antiretroviral combination regimens for the prevention of perinatal HIV transmission. The aim of our study was to determine whether tenofovir or emtricitabine administered in long-term fashion affect expression of two widely described pharmacokinetic determinants, P-glycoprotein (ABCB1) and breast cancer resistance protein (ABCG2), in maternal or fetal biological tissues.

METHODS

For this purpose, pregnant Wistar rats were administered tenofovir (2.25 mg/kg/day), emtricitabine (3.5 mg/kg/day) or saline i.m. for 10 days (from the 12th to 21st gestation day). On the 22nd day, the placenta and maternal/fetal intestine, brain, kidneys and liver were sampled and analysed for Abcb1a, Abcb1b and Abcg2 expression; placental and newborns' weights were also monitored.

KEY FINDINGS

We found that long-term application of tenofovir or emtricitabine did not significantly affect expression of Abcb1a, Abcb1b and Abcg2 in either maternal or fetal organs. However, tenofovir administration significantly increased placenta-to-birthweight ratio, a strong indicator of various diseases occurring later in life.

CONCLUSIONS

Our data broaden current knowledge on safety profile of tenofovir and emtricitabine use in pregnancy. Nevertheless, further research in other mammal species, including humans, is important to fully elucidate this issue.

Vitamin D Receptor Gene Ablation in the Conceptus Has Limited Effects on Placental Morphology, Function and Pregnancy Outcome

Vitamin D deficiency has been implicated in the pathogenesis of several pregnancy complications attributed to impaired or abnormal placental function, but there are few clues indicating the mechanistic role of vitamin D in their pathogenesis. To further understand the role of vitamin D receptor (VDR)-mediated activity in placental function, we used heterozygous Vdr ablated C57Bl6 mice to assess fetal growth, morphological parameters and global gene expression in Vdr null placentae. Twelve Vdr^+/- dams were mated at 10–12 weeks of age with Vdr^+/- males. At day 18.5 of the 19.5 day gestation in our colony, females were euthanised and placental and fetal samples were collected, weighed and subsequently genotyped as either Vdr^+/+, Vdr^+/-or Vdr^-/-. Morphological assessment of placentae using immunohistochemistry was performed and RNA was extracted and subject to microarray analysis. This revealed 25 genes that were significantly differentially expressed between Vdr^+/+ and Vdr^-/- placentae. The greatest difference was a 6.47-fold change in expression of Cyp24a1 which was significantly lower in the Vdr^-/- placentae (P<0.01). Other differentially expressed genes in Vdr^-/- placentae included those involved in RNA modification (Snord123), autophagy (Atg4b), cytoskeletal modification (Shroom4), cell signalling (Plscr1, Pex5) and mammalian target of rapamycin (mTOR) signalling (Deptor and Prr5). Interrogation of the upstream sequence of differentially expressed genes identified that many contain putative vitamin D receptor elements (VDREs). Despite the gene expression differences, this did not contribute to any differences in overall placental morphology, nor was function affected as there was no difference in fetal growth as determined by fetal weight near term. Given our dams still expressed a functional VDR gene, our results suggest that cross-talk between the maternal decidua and the placenta, as well as maternal vitamin D status, may be more important in determining pregnancy outcome than conceptus expression of VDR.

Vitamin D3 inhibits lipopolysaccharide-induced placental inflammation through reinforcing interaction between vitamin D receptor and nuclear factor kappa B p65 subunit

It is increasingly recognized that vitamin D3 (VitD3) has an anti-inflammatory activity. The present study investigated the effects of maternal VitD3 supplementation during pregnancy on LPS-induced placental inflammation and fetal intrauterine growth restriction (IUGR). All pregnant mice except controls were intraperitoneally injected with LPS (100 μg/kg) daily from gestational day (GD)15–17. In VitD3 + LPS group, pregnant mice were orally administered with VitD3 (25 μg/kg) before LPS injection. As expected, maternal LPS exposure caused placental inflammation and fetal IUGR. Interestingly, pretreatment with VitD3 repressed placental inflammation and protected against LPS-induced fetal IUGR. Further analysis showed that pretreatment with VitD3, which activated placental vitamin D receptor (VDR) signaling, specifically suppressed LPS-induced activation of nuclear factor kappa B (NF-κB) and significantly blocked nuclear translocation of NF-κB p65 subunit in trophoblast gaint cells of the labyrinth layer. Conversely, LPS, which activated placental NF-κB signaling, suppressed placental VDR activation and its target gene expression. Moreover, VitD3 reinforced physical interaction between placental VDR and NF-κB p65 subunit. The further study demonstrates that VitD3 inhibits placental NF-κB signaling in VDR-dependent manner. These results provide a mechanistic explanation for VitD3-mediated anti-inflammatory activity. Overall, the present study provides evidence for roles of VDR as a key regulator of placental inflammation.

A Proposed Molecular Mechanism of High-Dose Vitamin D3 Supplementation in Prevention and Treatment of Preeclampsia

A randomized prospective clinical study performed on a group of 74 pregnant women (43 presenting with severe preeclampsia) proved that urinary levels of 15-F(2t)-isoprostane were significantly higher in preeclamptic patients relative to the control (3.05 vs. 2.00 ng/mg creatinine). Surprisingly enough, plasma levels of 25-hydroxyvitamin D3 in both study groups were below the clinical reference range with no significant difference between the groups. In vitro study performed on isolated placental mitochondria and placental cell line showed that suicidal self-oxidation of cytochrome P450scc may lead to structural disintegration of heme, potentially contributing to enhancement of oxidative stress phenomena in the course of preeclampsia. As placental cytochrome P450scc pleiotropic activity is implicated in the metabolism of free radical mediated arachidonic acid derivatives as well as multiple Vitamin D3 hydroxylations and progesterone synthesis, we propose that Vitamin D3 might act as a competitive inhibitor of placental cytochrome P450scc preventing the production of lipid peroxides or excess progesterone synthesis, both of which may contribute to the etiopathogenesis of preeclampsia. The proposed molecular mechanism is in accord with the preliminary clinical observations on the surprisingly high efficacy of high-dose Vitamin D3 supplementation in prevention and treatment of preeclampsia.

N-myc downstream-regulated gene 1 (NDRG1) mediates pomegranate juice protection from apoptosis in hypoxic BeWo cells but not in primary human trophoblasts

INTRODUCTION

N-Myc downstream-regulated gene 1 (NDRG1) expression is increased in placentas of human pregnancies with intrauterine growth restriction and in hypoxic cultured primary trophoblasts. We previously showed that elevated NDRG1 decreases trophoblast apoptosis induced by hypoxia. Separately, we found that pomegranate juice (PJ) decreases cell death induced by hypoxia in trophoblasts. Here, we test the hypothesis that PJ protects trophoblasts from hypoxia-induced apoptosis by modulating NDRG1 expression.

METHODS

Quantitative rtPCR was used to investigate the effects of PJ treatment on mRNA levels of 22 candidate genes involved in apoptosis, oxidative stress, and differentiation in trophoblasts. Western blotting and immunofluorescence were used to analyze NDRG1 protein levels. siRNA-mediated NDRG1 knockdown was used to investigate the role of NDRG1 in response to PJ in hypoxic BeWo choriocarcinoma cells and hypoxic cultured primary human trophoblasts.

RESULTS

The mRNA levels of eight genes were altered, with NDRG1 showing the largest response to PJ and thus, we pursued the role of NDRG1 here. PJ significantly increased NDRG1 protein expression in primary trophoblasts and in BeWo cells. Knockdown of NDRG1 in hypoxic BeWo cells in the presence of PJ yielded increased apoptosis. In contrast, knockdown of NDRG1 in hypoxic primary trophoblasts in the presence of PJ did not increase apoptosis.

DISCUSSION

We conclude that the PJ-mediated decrease in cell death in hypoxia is partially mediated by NDRG1 in BeWo cells but not in primary trophoblasts. The disparate effects of NDRG1 between BeWo cells and primary trophoblasts indicate caution is required when extrapolating from results obtained with cell lines to primary trophoblasts.

The pleiotropic effects of vitamin D in gynaecological and obstetric diseases: an overview on a hot topic

The traditionally recognized role of vitamin D consists in the regulation of bone metabolism and calcium-phosphorus homeostasis but recently a lot of in vitro and in vivo studies recognized several “noncalcemic” effects of vitamin D metabolites. Accumulating evidence suggests that the metabolic pathways of this vitamin may play a key role in the developing of gynaecological/obstetric diseases. VDR-mediated signalling pathways and vitamin D levels seem to (deeply) affect the risk of several gynaecological diseases, such as polycystic ovary syndrome (PCOS), endometriosis, and ovarian and even breast cancer. On the other hand, since also the maternal-fetal unit is under the influence of vitamin D, a breakdown in its homeostasis may underlie infertility, preeclampsia, and gestational diabetes mellitus (GDM). According to our literature review, the relationship between vitamin D and gynaecological/obstetric diseases must be replicated in future studies which could clarify the molecular machineries behind their development. We suggest that further investigation should take into account the different serum levels of this vitamin, the several actions which arise from the binding between it and its receptor (taking into account its possible polymorphism), and finally the interplay between vitamin D metabolism and other hormonal and metabolic pathways.

Placental calcitriol synthesis and IGF-I levels in normal and preeclamptic pregnancies

Placenta is an extrarenal source of calcitriol and pregnancy is associated with increased maternal serum levels of this hormone. It has been reported that insulin-like growth factor I (IGF-I) stimulates placental calcitriol synthesis and that circulating levels of both hormones are low in preeclampsia. Since calcitriol production has not been determined in placental homogenates in preeclampsia, the aim of the present study was to establish if placental calcitriol synthesis and IGF-I concentration are altered in this tissue obtained from preeclamptic pregnancies. Placental samples were obtained from 8 preeclamptic (PE group) and 8 normotensive (NT group) pregnant women. Calcitriol synthesis was determined using [(3)H]-25(OH)D3 (2.94nM) as precursor and [(3)H]-1,25(OH)2D3 produced was calculated as the percentage of radioactivity co-eluting with unlabelled 1,25(OH)2D3 after two successive high pressure liquid chromatographies. Placental IGF-I levels were determined by RIA. In addition, maternal and umbilical calcitriol and IGF-I levels were also determined in these 2 groups using radioreceptor assay and RIA, respectively. The results of the present study showed that placentas from both groups were able to convert [(3)H]-25(OH)D3 into more polar metabolites. In the PE group, placental [(3)H]-1,25(OH)2D3 synthesis was significantly lower than in the NT group (19.6±6.2 vs 29.9±8.1fmoles/200mg wet weight, P=0.013). Regarding IGF-I, its levels were significantly lower in placentas of the PE group than in the NT group (15.2±3.9 vs 21.6±4.9ng/g wet weight, P=0.012). Maternal and umbilical calcitriol levels were significantly lower in the PE than in the NT group (P<0.001). In the PE group, serum IGF-I levels were significantly lower only in the maternal circulation (P<0.05). In conclusion, placental calcitriol synthesis and IGF-I levels are low in preeclampsia which may contribute to decreased local placental functions related to these two hormones and/or to decreased maternal and fetal pool of 1,25(OH)2D3 during preeclamptic pregnancies. This article is part of a Special Issue entitled '16th Vitamin D Workshop'.

Maternal vitamin D status in preeclampsia: seasonal changes are not influenced by placental gene expression of vitamin D metabolizing enzymes

Preeclampsia, a hypertensive disorder in pregnancy develops in 2–8% of pregnancies worldwide. Winter season and vitamin D deficiency have been associated with its onset.

Objective

To investigate the influence of season on maternal vitamin D status and placental vitamin D metabolism.

Methods

25-OH vitamin D and 1,25-(OH)₂ vitamin D were measured in maternal serum obtained during the winter or summer months from 63 pregnant women at delivery (43 healthy, 20 preeclampsia). In a subgroup, mRNA expression of CYP24A1 (24-hydroxylase), CYP27B1 (1α-hydroxylase) and VDR (vitamin D receptor) were quantified by real time PCR in placental samples of 14 women with normal pregnancies and 13 with preeclampsia.

Results

In patients with preeclampsia,25-OH vitamin D levels were lower, but differed significantly from controls only in summer (18.21±17.1 vs 49.2±29.2 ng/mL, P<0.001), whereas 1,25-(OH)₂ vitamin D levels were significantly lower only in winter (291±217 vs 612.3±455 pmol/mL, P<0.05). A two-factorial analysis of variance produced a statistically significant model (P<0.0001) with an effect of season (P<0.01) and preeclampsia (P = 0.01) on maternal 25-OH vitamin D levels, as well as a significant interaction between the two variables (P = 0.02). Placental gene expression of CYP24A1, CYP27B1, and VDR did not differ between groups or seasons. A negative correlation between placental gene expression of CYP24A1 and CYP27B1 was observed only in healthy controls (r = −0.81, P<0.0001).

Summary

Patients with preeclampsia displayed lower vitamin D serum levels in response to seasonal changes.The regulation of placental CYP24A1, but not of the VDR or CYP27B1 might be altered in preeclampsia.

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.

U0126, a mitogen-activated protein kinase kinase 1 and 2 (MEK1 and 2) inhibitor, selectively up-regulates main isoforms of CYP3A subfamily via a pregnane X receptor (PXR) in HepG2 cells

Hepatocyte tumor cell lines lack the expression or induction properties of major cytochrome P450 (CYP) enzymes compared to primary human hepatocytes. The Ras/Raf/MEK/ERK signaling cascade contributes to hepatocarcinogenesis, dedifferentiation and loss of hepatocyte drug metabolism in hepatocyte tumors. In the present study, we examined whether MEK1/2 inhibitors can restore the expression of CYP genes in hepatocarcinoma HepG2 cells. We found that U0126, a prototype dual MEK1/2 inhibitor, is a potent inducer of CYP3A4, CYP3A5 and CYP3A7 mRNA expression (>100-fold) in HepG2 cells and CYP3A4 mRNA expression in primary human hepatocytes. This U0126-mediated induction is sensitive to the transcriptional inhibitor actinomycin D and was not detected for CYP2B6 or MDR1 mRNA expression. In gene reporter assays, U0126 activates a CYP3A4 promoter luciferase reporter construct containing PXR response elements (PXREs), but not a construct containing mutated PXREs. Based on a ligand binding assay and the examination of a PXR mutant expressing an obstructed ligand binding pocket, we found that U0126 is a ligand of PXR. We also found that U0126 up-regulates the mRNA expression of the nuclear receptors HNF4α, CAR, VDR and PXR but abolishes small heterodimer partner (SHP) corepressor expression in HepG2 cells. The MEK1/2 inhibitors PD0325901 and PD184352, as well as dominant-negative MEK1 expression, also down-regulate SHP mRNA expression. In contrast, dominant-negative MEK1 expression does not significantly induce CYP3A4 gene in HepG2 cells. In conclusion, we found that U0126 is an atypical PXR ligand that via direct (binding and activation of PXR) and indirect (SHP dowregulation) mechanisms selectively restores CYP3A genes in HepG2 cells.

The importance of the retinoid X receptor alpha in modulating inflammatory signaling in acute murine colitis

BACKGROUND

In order for vitamin D to signal and regulate inflammatory pathways, it must bind to its receptor (VDR) which must heterodimerize with the retinoid X receptor alpha (RXRα). Although the role that vitamin D signaling plays in the development and progression of colitis, a disease characterized by excessive inflammation, has been suggested, little research has been done on determining the role that RXRα plays in acute colitis development.

AIMS

This study sought to determine the effects that reduced availability of RXRα would have on the development of acute murine colitis. Expression of inflammatory markers, VDR and RXRα were investigated to determine if the reduction in expression of RXRα in RXRα(+/-) mice would result in increased inflammatory signaling and receptor downregulation as compared to their wild-type littermates.

METHODS

An acute murine model of colitis, the axozymethane (AOM) and dextran sulfate sodium (DSS) model was utilized in wild-type and RXRα(+/-) mice. Gross manifestations of colitis measured included weight loss and colitis score. Immunblots and real-time PCR were performed for inflammatory markers and receptor expression.

RESULTS

RXRα(+/-) mice induced with AOM/DSS colitis demonstrated increased gene expression of Snail and Snail2, transcription factors downstream of inflammatory mediators, as compared to their wild-type littermates.

CONCLUSIONS

This demonstrates the importance of RXRα in regulating inflammation in acute colitis and also identifies RXRα expression as a new consideration when developing successful interventions for acute colitis due to the requirement of numerous receptors for RXRα.

Placental CYP27B1 and CYP24A1 expression in human placental tissue and their association with maternal and neonatal calcitropic hormones

CONTEXT

Placental CYP27B1 may contribute to circulating maternal calcitriol concentrations across gestation, but determinants of CYP27B1 and CYP24A1 expression in term human placental tissue are not well established.

OBJECTIVE

We hypothesized that higher CYP27B1 protein expression would be associated with increased maternal calcitriol during gestation and that CYP27B1 expression would be impacted by substrate availability.

DESIGN

This was a prospective, longitudinal study.

SETTING

The study was completed in an urban, prenatal clinic located in Rochester, New York.

PATIENTS

The study was undertaken in a cohort of 70 pregnant adolescents (≤18 y of age) and their term neonates.

INTERVENTION

There was no intervention.

MAIN OUTCOMES

Protein and mRNA expressions of CYP27B1, CYP24A1, and vitamin D receptor were measured in term placental tissue and related to 25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyvitamin D, PTH, serum total calcium, IL-6, leptin, and osteoprotegerin measured in maternal serum at midgestation and delivery and in umbilical cord serum at birth.

RESULTS

Placental CYP27B1 protein expression was significantly positively associated with maternal 25(OH)D at both midgestation (n = 68, P = .009) and delivery (n=67, P = .006). Maternal serum 1,25-dihydroxyvitamin D concentrations at midgestation were positively correlated with term placental CYP27B1 mRNA expression (n = 49, P = .002). Significant positive associations were evident between placental CYP27B1 and CYP24A1 protein expression (P = .001, n = 70). Maternal PTH concentrations at midgestation or delivery did not significantly impact placental protein or transcript level of either enzyme. Variability in placental CYP27B1 protein expression was best captured by a model that included maternal midgestation 25(OH)D concentration, placental vitamin D receptor protein expression, and maternal midgestation IL-6 concentrations (P = .002, n = 60, R(2) = 0.22).

CONCLUSIONS

Higher maternal 25(OH)D during pregnancy was associated with significantly higher placental protein expression of CYP27B1 at term supportive of a link between substrate availability and placental production of calcitriol.

Vitamin D receptor polymorphism FokI is associated with spontaneous idiopathic preterm birth in an Israeli population

OBJECTIVE

The active form of vitamin D (1,25[OH]2D3) has been established to have potent anti-proliferative, immuno-modulatory, and anti-microbial action in addition to its effects on bone. The nuclear vitamin D receptor (VDR) is expressed in the placenta-decidua, regulating genes associated with implantation and implantation immuno-tolerance. If VDR polymorphisms regulate VDR functionality at the placenta-decidua interface, VDR genotypes may be involved in idiopathic preterm birth (PTB).

STUDY DESIGN

Maternal and fetal (umbilical cord) blood samples from 33 Jewish and Arab mothers with PTB of a singleton neonate were compared to 98 samples from Jewish and Arab maternal and fetal blood samples from full-term, uncomplicated singleton births. Maternal age and ethnicity were comparable between groups. PCR amplification/digestion identified the VDR SNPs: FokI, ApaI, TaqI, and BsmI.

RESULTS

Allele frequency for the FokI VDR in maternal blood samples from preterm births (but not umbilical cord samples) was significantly different (p=0.01) from that in maternal and umbilical cord blood samples from full-term singleton births, with an odds ratio for FokI carriers of 3.317 (95% CI, 1.143, 9.627) for preterm birth. The FokI VDR variant may therefore be a maternal risk trait for PTB among these women.

CONCLUSION

This study may support a future platform for the study of vitamin D during pregnancy and treatment of selective target populations with vitamin D and/or VDR "tissue-specific therapeutic intervention" for prevention of PTB.

Dexamethasone accelerates degradation of aryl hydrocarbon receptor (AHR) and suppresses CYP1A1 induction in placental JEG-3 cell line

The JEG-3 choriocarcinoma cell line has been proposed as a model cell line of human placental trophoblast for induction studies via aryl hydrocarbon receptor (AHR). We examined whether glucocorticoid dexamethasone influences AHR-mediated induction of CYP1A1 enzyme in the JEG-3 cell line. We found that dexamethasone dose- and time-dependently suppresses CYP1A1 transactivation in gene reporter assays, CYP1A1 mRNA induction, and upregulation of 7-ethoxyresorufin-O-deethylase (EROD) activity by 3-methylcholanthrene (MC) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in JEG-3 cells. Co-transfection of JEG-3 cells with glucocorticoid receptor (GR) expression construct and treatment with dexamethasone abolished the effect of MC on CYP1A1 promoter construct in transient transfection gene reporter assays. RU486, a GR antagonist, suppressed the effect of dexamethasone on MC-induced transactivation of AHR responsive reporter constructs. We also found that dexamethasone stimulates both ligand-dependent and ligand-independent degradation of AHR but not of aryl hydrocarbon receptor nuclear translocator (ARNT) protein in JEG-3 cells. In experiments with proteasome inhibitors MG132 and bortezomib, we found that the degradation is not sensitive to proteasome inhibition in JEG-3. We can conclude that dexamethasone suppresses AHR-mediated CYP1A1 induction in JEG-3 cells through the unique mechanism of AHR-GR crosstalk, which involves accelerated degradation of AHR.

Nuclear receptors in regulation of biotransformation enzymes and drug transporters in the placental barrier

Over the past 20 years, the toxicological and protective roles of the placental barrier with respect to drug detoxification and transporter-controlled protection of the fetus have been intensively examined. Several cytochrome P450 enzymes are expressed in placental trophoblast at different stages of pregnancy, though only a few of these have functional activity to metabolize xenobiotics. Drug transporters such as P-glycoprotein/MDR1 or breast cancer resistance protein (BCRP) are highly expressed in the placenta, and their functional activities have been demonstrated in the placenta both in vitro and in vivo. In addition, several studies have reported on ligand-activated transcription factors and nuclear receptors referred to as "xenosensors" in the placenta. The xenosensors control transcriptional regulation of both xenobiotic-metabolizing enzymes and drug transporters in different organs. Their ligands include toxic compounds and environmental pollutants, drugs, as well as herbal, dietary or vitamin supplements. Nevertheless, it remains debatable whether the placental barrier adapts to toxic injuries coming either from maternal medication or environmental contamination and whether the placenta contains a mechanism to respond dynamically in protecting the developing fetus. In the present paper, we summarize current knowledge about the activity and expression of major ligand-activated transcriptional mechanisms involved in biotransformation enzymes and transporters regulation in human placenta. In particular, we highlight the emerging roles of aryl hydrocarbon (AHR), vitamin D (VDR), glucocorticoid (GR) and pregnane X (PXR) receptors in that regulation. We show that the placenta constitute a unique metabolizing organ with significant overlap of exogenous and endogenous compounds metabolism controlled by nuclear receptors.

Calcitriol downregulates TNF-α and IL-6 expression in cultured placental cells from preeclamptic women

Placenta is an important source and target of hormones that contribute to immunological tolerance and maintenance of pregnancy. In preeclampsia (PE), placental calcitriol synthesis is low; whereas pro-inflammatory cytokines levels are increased, threatening pregnancy outcome. Previously, we showed that calcitriol inhibits Th-1 cytokines under experimental inflammatory conditions in normal trophoblasts. However, a study of the regulation of inflammatory cytokines by calcitriol in trophoblasts from a natural inflammatory condition, such as PE, is still lacking. Therefore, the aim of the present study was to investigate calcitriol effects upon TNF-α, IFN-γ, IL-6 and IL-1β in cultured placental cells from preeclamptic women by using qPCR and ELISA. Placentas were collected after cesarean section from preeclamptic women and enriched trophoblastic preparations were cultured in the absence or presence of different calcitriol concentrations during 24h. In these cell cultures, pro-inflammatory cytokines TNF-α and IL-6 secretion and mRNA expression were downregulated by calcitriol (P<0.05). No significant effects of calcitriol upon IFN-γ and IL-1β were observed. In addition, basal expression of TNF-α, IL-6 and IL-1β decreased as the cells formed syncytia. Our study supports an important autocrine/paracrine role of placental calcitriol in controlling adverse immunological responses at the feto-maternal interface, particularly in gestational pathologies associated with exacerbated inflammatory responses such as preeclampsia.

Epigenetic Methylation of Parathyroid CaR and VDR Promoters in Experimental Secondary Hyperparathyroidism

Secondary hyperparathyroidism (s-HPT) in uremia is characterized by decreased expression in the parathyroids of calcium sensing (CaR) and vitamin D receptors (VDR). Parathyroid hormone (PTH) is normalized despite low levels of CaR and VDR after experimental reversal of uremia. The expression of CaR in parathyroid cultures decreases rapidly. Methylation of promoter regions is often detected during epigenetic downregulation of gene expression. Therefore, using an experimental rat model, we examined changes in methylation levels of parathyroid CaR and VDR promoters in vivo and in vitro. Methods. Uremia was induced by 5/6 nephrectomy. Melting temperature profiling of CaR and VDR PCR products after bisulfite treatment of genomic DNA from rat parathyroids was performed. Real-time PCR measured expression of PTH, CaR, VDR, and klotho genes in vitro. Results. Parathyroids from uremic rats had similar low levels of methylation in vivo and in vitro. In culture, a significant downregulation of CaR, VDR, and klotho within two hours of incubation was observed, while housekeeping genes remained stable for 24 hours. Conclusion. In uremic s-HPT and in vitro, no overall changes in methylation levels in the promoter regions of parathyroid CaR and VDR genes were found. Thus, epigenetic methylation of these promoters does not explain decreased parathyroid expression of CaR and VDR genes in uremic s-HPT.

Expressions of vitamin D metabolic components VDBP, CYP2R1, CYP27B1, CYP24A1, and VDR in placentas from normal and preeclamptic pregnancies

Vitamin D insufficiency/deficiency during pregnancy has been linked to increased risk of preeclampsia. Placenta dysfunction plays an important role in the pathogenesis of this pregnancy disorder. In this study, we tested the hypothesis that disturbed vitamin D metabolism takes place in preeclamptic placentas. Protein expressions of vitamin D binding protein (VDBP), 25-hydroxylase (CYP2R1), 1α-hydroxylase (CYP27B1), 24-hydroxylase (CYP24A1), and vitamin D receptor (VDR) were examined in placentas from normotensive and preeclamptic pregnancies. By immunostaining we found that in normal placenta VDBP, CYP24A1, and VDR expressions are localized mainly in trophoblasts, whereas CYP2R1 and CYP27B1 expressions are localized mainly in villous core fetal vessel endothelium. Protein expressions of CYP2R1 and VDR are reduced, but CYP27B1 and CYP24A1 expressions are elevated, in preeclamptic compared with normotensive placentas. Because increased oxidative stress is an underlying pathophysiology in placental trophoblasts in preeclampsia, we further determined whether oxidative stress contributes to altered vitamin D metabolic system in placental trophoblasts. Trophoblasts isolated from normal-term placentas were treated with hypoxic-inducing agent CoCl(2), and protein expressions of VDBP, CYP2R1, CYP27B1, CYP24A1, and VDR were determined. We found that hypoxia-induced downregulation of VDBP, CYP2R1, and VDR and upregulation of CYP27B1 and CYP24A1 expressions were consistent with that seen in preeclamptic placentas. CuZnSOD expression was also downregulated in trophoblasts treated with CoCl(2). These results provide direct evidence of disrupted vitamin D metabolic homeostasis in the preeclamptic placenta and suggest that increased oxidative stress could be a causative factor of altered vitamin D metabolism in preeclamptic placentas.

Epigenetics mediate environment : gene effects on occupational sensitization

PURPOSE OF REVIEW

Epigenetics is the study of stable modifications of fixed genomes that direct which genes are expressed and which are silenced. Epigenetic changes are modulated by environmental exposures, making epigenetics the interface between genes and environment. This has particular relevance in understanding the effect of occupational exposures on the expression of allergic disease. The goal of this review is to describe how epigenetic changes affect transcription potential, and to examine more closely the effect of specific environmental and occupational exposures on epigenetic variations that alter allergy gene transcripts and the inflammatory milieu.

RECENT FINDINGS

Gene transcription is activated when specific CpG sites are demethylated and histones are acetylated, and, conversely, silenced when sites are methylated and histones deacetylated. The development of Th1 and Th2 phenotypes, and expression of Treg cells, are now known to be modulated by epigenetic mechanisms. Workplace exposures such as tobacco smoke, particulates, diesel exhaust, polyaromatic hydrocarbons, ozone, and endotoxin, among others, suppress Treg development, and enhance expression of inflammatory cytokines and allergic phenotypes by epigenetic means.

SUMMARY

Epigenetic manipulation to open and close transcription sites provides flexibility of gene expression in response to changing environmental cues. It may also be the window whereby allergic disease in the workplace can be reduced by targeted environmental interventions.

Rifampicin Does not Significantly Affect the Expression of Small Heterodimer Partner in Primary Human Hepatocytes

The small/short heterodimer partner (SHP, NR0B2) is a nuclear receptor corepressor lacking a DNA binding domain. SHP is induced by bile acid-activated farnesoid X receptor (FXR) resulting in CYP7A1 gene suppression. In contrast, Pregnane X receptor (PXR) activation by its ligands was recently suggested to inhibit SHP gene transactivation to maximize the induction of PXR target genes. However, there are also conflicting reports in literature whether PXR or rodent Pxr activation down-regulates SHP/Shp expression. Moreover, the PXR-mediated regulation of the SHP gene has been studied only at the SHP mRNA and transactivation (gene reporter assay) levels. In this study, we studied the effect of rifampicin, a prototype PXR ligand, on SHP mRNA, and protein expression in three primary human hepatocyte cultures. We found that SHP mRNA is not systematically down-regulated in hepatocyte in culture after 24 h treatment with rifampicin. Consistently, we did not observe down-regulation of SHP protein in primary human hepatocytes after 24 and 48 h of incubation with rifampicin. We can conclude that although we observed slight down-regulation of SHP mRNA and protein in several hepatocyte preparations, the phenomenon is unlikely critical for PXR-mediated induction of its target genes.

Lantana macrophylla Schauer (Verbenaceae) ethanolic extract induces activation of ERK1/2 and p38 MAPKs pathway and Ca2+ imbalance in human trophoblasts derived cell lines

Lantana macrophylla Schauer (Verbenaceae) a medicinal plant used to treat menstrual and respiratory disorders was investigated. The ethanolic extract from leaves was subjected to phytochemical and biological analysis. BeWo and JEG-3 cells were used to evaluate human chorionic gonadotropin hormone (hCG) production, syncytial formation, Ca2+ uptake and Ca2+ handling protein expression. The cAMP production and the mitogen-activated protein kinases (MAPKs) phosphorylation were also investigated. Phytochemical analysis yield three triterpenes: oleanolic, ursolic and latonolic acid. Viability assay showed no significant cytotoxic effect. A significant decrease in hCG production but not a disturbance on BeWo cell fusion were observed. The cAMP pathway was not affected by L. macrophylla extract alone; although the cAMP production inducted by forskolin was diminished. Both ERK1/2 and p38 MAPKs pathways were activated. Increased intracellular Ca2+ concentration ([Ca2+]i) was observed after 24 h treatment in a time and dose dependent manner; however only L. macrophylla at 10 μg/mL induced increased [Ca2+]i after 10 min treatment. CaBP28K and PMCA1/4 were modulated at protein and mRNA levels, respectively. This study showed for the first time the effect of triterpenoids from L. macrophylla leaves on trophoblasts-like cells and indicates a potential toxic effect of this plant in the placental development and fetal growth.

Vitamin D, the placenta and pregnancy

Impaired vitamin D status is common to many populations around the world. However, data suggest that this is a particular problem for specific groups such as pregnant women. This has raised important questions concerning the physiological and clinical impact of low vitamin D levels during pregnancy, with implications for classical skeletal functions of vitamin D, as well as its diverse non-classical actions. The current review will discuss this with specific emphasis on the classical calciotropic effects of vitamin D as well as the less well established immunological functions of vitamin D that may influence pregnancy outcome. The review also describes the pathways that are required for metabolism and function of vitamin D, and the various clinical complications that have been linked to impaired vitamin D status during pregnancy.

Effects of 1,25(OH)2 vitamin D3 on cytokine production by endometrial cells of women with recurrent spontaneous abortion

OBJECTIVE

To investigate immunomodulatory effect of 1,25(OH)2 vitamin D3 (1,25(OH)2D3) on cytokine production by endometrial cells of women with unexplained recurrent spontaneous abortion (URSA).

DESIGN

In vitro study.

SETTING

Academic research center.

PATIENT(S)

Patients with URSA and healthy controls.

INTERVENTION(S)

Treatment with 1,25(OH)2D3.

MAIN OUTCOME MEASURE(S)

Production of interferon γ (IFN-γ), interleukin-10 (IL-10), transforming growth factor β (TGF-β), IL-17, IL-6, and IL-8 by whole endometrial cells (WECs) and endometrial stromal cells in the presence and absence of 1,25(OH)2D3 and 1α-hydroxylase activity of these cell populations were measured in patients with URSA and healthy controls.

RESULT(S)

1,25(OH)2D3 interfered with production of cytokines by WECs of the control and URSA groups, except IL-8 which was increased in URSA group. In endometrial stromal cells, 1,25(OH)2D3 down-regulated cytokine production as well with stimulatory effect on the production of TGF-β in patients with URSA. Cytokine profile of WECs from patients with URSA skewed toward TH2 phenotype after treatment with 1,25(OH)2D3. Endometrial cells of both groups had comparable capacity to produce 1,25(OH)2D3.

CONCLUSION(S)

Considering the complex network of immunoregulation at the fetomaternal interface, potential beneficial effects of vitamin D3 in patients with URSA need to be investigated in clinical practice. Comparable levels of 1,25(OH)2D3 production and similar trend of cytokine expression by WECs of URSA and control groups after vitamin D3 treatment reflect the same local metabolic machinery of this hormone.