Influence of calcitriol on prolactin and prostaglandin production by human decidua

Immunomodulatory role of decidual prolactin on the human fetal membranes and placenta

The close interaction between fetal and maternal cells during pregnancy requires multiple immune-endocrine mechanisms to provide the fetus with a tolerogenic environment and protection against any infectious challenge. The fetal membranes and placenta create a hyperprolactinemic milieu in which prolactin (PRL) synthesized by the maternal decidua is transported through the amnion-chorion and accumulated into the amniotic cavity, where the fetus is bedded in high concentrations during pregnancy. PRL is a pleiotropic immune-neuroendocrine hormone with multiple immunomodulatory functions mainly related to reproduction. However, the biological role of PRL at the maternal-fetal interface has yet to be fully elucidated. In this review, we have summarized the current information on the multiple effects of PRL, focusing on its immunological effects and biological significance for the immune privilege of the maternal-fetal interface.

Low Prenatal Vitamin D Metabolite Ratio and Subsequent Postpartum Depression Risk

Background: Depression is a common complication of pregnancy and vitamin D deficiency is one biological risk factor for postpartum depression (PPD). Materials and Methods: We evaluated the ratio of 24,25(OH)2D and 25(OH)D serum concentrations referred to as the Vitamin D Metabolite Ratio (VMR), a new candidate biomarker during pregnancyand its relationship with PPD. Women were enrolled in the first trimester of pregnancy and followed through four timepoints. Results: A total of 89 women had complete depression, biomarker and demographic data and 34% were at risk for PPD (CES-D≥16). Stepwise multiple logistic regression models for PPD risk were carried out with eight predictors. Results showed that only lower VMR, OR = 1.43, 95% CI 1.10-1.86, p = 0.007, and Hispanic/Latina identification, OR = 3.83, 95% CI 1.44-10.92, p = 0.007 were significantly associated with higher PPD risk. Conclusion: Routine prenatal screening for vitamin D metabolites, particularly in Hispanic/Latina women, may identify women at risk for PPD.

Placental gene expression and antibody levels of mother-neonate pairs reveal an enhanced risk for inflammation in a helminth endemic country

In utero exposure to environmental factors can modify the development of allergies later in life whereby the mechanisms of the feto-maternal crosstalk still remain largely unknown. Murine studies revealed that inflammatory maternal signals elicited by chronic helminth infection within the placenta imprint a distinct gene expression profile related to the Vitamin-D-receptor (VDR)-inflammation-axis. We thus investigated whether pro- or anti- inflammatory immune responses as well as VDR and related gene expression within the placenta differ between women from helminth-endemic and non-endemic areas. A prospective pilot study was conducted in Munich, Germany (helminth non-endemic) and Lambaréné, Gabon (helminth-endemic). At delivery, clinical information alongside placenta tissue samples and maternal and cord blood were obtained for further laboratory analysis. Schistosoma haematobium infection was detected in 13/54 (23%) Gabonese women. RT PCR revealed significantly lower gene expression of VDR, Cyp27b1, Foxp3 and IL10 in Gabonese compared to German placentae as well as significantly lower levels of plasma IgG4 in newborns resulting in a significantly higher IgE/IgG4 ratio. These findings demonstrate that exposure in utero to different environments alters placental gene expression and thus possibly plays a role in the development and modulation of the immune system of the offspring.

Can Getting Enough Vitamin D during Pregnancy Reduce the Risk of Getting Asthma in Childhood?

The worldwide increase in asthma prevalence during the last decades and the re-emergence of vitamin D deficiency in many populations hinted toward an underlying association between these two conditions. Since asthma is presented with high incidence in childhood and neonatal vitamin D stores depend on maternal vitamin levels, a possible programming effect of maternal vitamin D status during gestation was suggested. Observational and longitudinal studies on this subject led to inconclusive results with glimmer of positivity. In the randomized controlled clinical trials (RCTs) that followed, increased doses of vitamin D were tested in pregnant women being at high risk of having an asthmatic child. Although, the results of RCTs showed a potential association with asthma-related phenotypes rather than asthma per se, the low toxicity of vitamin D supplements make it tempting to speculate that pregnant women at a high risk of obtaining a child with asthma may be benefited, especially if they are vitamin D deficient.

Vitamin D Deficiency in BALB/c Mouse Pregnancy Increases Placental Transfer of Glucocorticoids

The prevalence of vitamin D deficiency in pregnancy is increasing and implicated in adverse consequences for the health of offspring in later life. The aim of this study was to determine whether vitamin D deficiency increases fetal exposure to glucocorticoids, which are known to alter fetal development and result in adverse adult health outcomes. Female BALB/c mice were placed on either a vitamin D control (2195 IU/kg) or deficient (0 IU/kg) diet for 5 weeks before and during pregnancy. Maternal serum, placentas and fetal brains were collected at embryonic day 14.5 or 17.5 for morphological and gene expression analysis. Vitamin D deficiency during pregnancy increased maternal corticosterone concentrations and reduced placental weight. Maternal vitamin D deficiency decreased placental expression of 11β-hydroxysteroid dehydrogenase type II, which inactivates glucocorticoids thereby protecting the fetus from inappropriate glucocorticoid exposure. There was a corresponding increase in placental and fetal expression of the highly glucocorticoid-sensitive factor glucocorticoid-induced leucine zipper. Furthermore, placental expression of the angiogenic factor vascular endothelial growth factor-A was reduced in vitamin D-deficient pregnancies, with a corresponding decline in fetal capillary volume within the placenta. Overall, we show that prenatal vitamin D deficiency leads to an increase in maternal corticosterone, alterations in genes indicative of increased fetal glucocorticoid exposure and impairment in placental vascular development. Thus, the long-term adverse health consequences of vitamin D deficiency during early development may not just be due to alteration in direct vitamin D-related pathways but also altered fetal glucocorticoid exposure.

Regulation of calcitriol biosynthesis and activity: focus on gestational vitamin D deficiency and adverse pregnancy outcomes

Vitamin D has garnered a great deal of attention in recent years due to a global prevalence of vitamin D deficiency associated with an increased risk of a variety of human diseases. Specifically, hypovitaminosis D in pregnant women is highly common and has important implications for the mother and lifelong health of the child, since it has been linked to maternal and child infections, small-for-gestational age, preterm delivery, preeclampsia, gestational diabetes, as well as imprinting on the infant for life chronic diseases. Therefore, factors that regulate vitamin D metabolism are of main importance, especially during pregnancy. The hormonal form and most active metabolite of vitamin D is calcitriol. This hormone mediates its biological effects through a specific nuclear receptor, which is found in many tissues including the placenta. Calcitriol synthesis and degradation depend on the expression and activity of CYP27B1 and CYP24A1 cytochromes, respectively, for which regulation is tissue specific. Among the factors that modify these cytochromes expression and/or activity are calcitriol itself, parathyroid hormone, fibroblast growth factor 23, cytokines, calcium and phosphate. This review provides a current overview on the regulation of vitamin D metabolism, focusing on vitamin D deficiency during gestation and its impact on pregnancy outcomes.

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.

The nonskeletal effects of vitamin D: an Endocrine Society scientific statement

Significant controversy has emerged over the last decade concerning the effects of vitamin D on skeletal and nonskeletal tissues. The demonstration that the vitamin D receptor is expressed in virtually all cells of the body and the growing body of observational data supporting a relationship of serum 25-hydroxyvitamin D to chronic metabolic, cardiovascular, and neoplastic diseases have led to widespread utilization of vitamin D supplementation for the prevention and treatment of numerous disorders. In this paper, we review both the basic and clinical aspects of vitamin D in relation to nonskeletal organ systems. We begin by focusing on the molecular aspects of vitamin D, primarily by examining the structure and function of the vitamin D receptor. This is followed by a systematic review according to tissue type of the inherent biological plausibility, the strength of the observational data, and the levels of evidence that support or refute an association between vitamin D levels or supplementation and maternal/child health as well as various disease states. Although observational studies support a strong case for an association between vitamin D and musculoskeletal, cardiovascular, neoplastic, and metabolic disorders, there remains a paucity of large-scale and long-term randomized clinical trials. Thus, at this time, more studies are needed to definitively conclude that vitamin D can offer preventive and therapeutic benefits across a wide range of physiological states and chronic nonskeletal disorders.

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.

Calcitriol stimulates prolactin expression in non-activated human peripheral blood mononuclear cells: breaking paradigms

Calcitriol, the hormonal form of vitamin D(3), exerts immunomodulatory effects through the vitamin D(3) receptor (VDR) and increases prolactin (PRL) expression in the pituitary and decidua. Nevertheless, the effects of calcitriol upon lymphocyte PRL have not been evaluated. Therefore, we investigated calcitriol effects upon PRL in resting and phytohemagglutinin-activated human peripheral blood mononuclear cells (PBMNC) and Jurkat T lymphoma cells. Immunoblots showed constitutive expression of the 50-kDa VDR species in activated PBMNC and Jurkat cells, while a 75-kDa species was recognized in both resting and activated-PBMNC. Only in resting PBMNC calcitriol significantly stimulated PRL expression in a dose-dependent manner. The positive control CYP24A1, a highly VDR-responsive gene, was stimulated by calcitriol, effect that was stronger in resting than in activated-PBMNC (P<0.05), and without effect in Jurkat cells. Calcitriol upregulation of PRL and CYP24A1 was significantly inhibited by the VDR antagonist TEI-9647. EMSA showed that resting PBMNC contain a protein that binds to DR3-type VDRE. Cell activation reduced basal CYP24A1 while induced CYP27B1, VDR and pregnane X receptor (PXR) expression. In summary, calcitriol stimulated PRL and CYP24A1 gene expression in quiescent lymphocytes through a VDR-mediated mechanism. Our results suggest that the 75-kDa VDR species could be participating in calcitriol-mediated effects, and that activation induces factors such as PXR that restrain VDR transcriptional processes. This study supports the presence of a functional VDR in quiescent lymphocytes, providing evidence to reevaluate the VDR paradigm that assumes that lymphocytes respond to calcitriol only after activation. Altogether, our results offer new insights into the mechanisms whereby PRL is regulated in immune cells.

Aberrant nest building and prolactin secretion in vitamin D receptor mutant mice

1Alpha,25(OH)2D3, the hormonal form of vitamin D, is a neuroactive seco-steroid hormone with multiple functions in the brain. Most of these effects are mediated through the nuclear vitamin D receptor (VDR), widely distributed in the central nervous system. Our earlier studies showed that mutant mice lacking functional VDR have specific behavioural abnormalities, including anxiety and aberrant maternal behaviour, which may be hormonally regulated. Here we describe impaired nest building behaviour in VDR mutant mice. Since prolactin plays a key role in the regulation of nest building in both sexes, we also examine whether VDR mutant mice have altered prolactin levels. Overall, serum prolactin levels were increased in VDR mutant mice, accompanied by marked impairments in their nest building activity. In contrast, there were no differences in prolactin mRNA expression levels between wildtype control mice and VDR mutant mice. Collectively, these data suggest that partial genetic ablation of VDR affects prolactin system in mice, and that altered serum prolactin levels in VDR mutants may underlie some of their behavioural abnormalities, such as impaired nest building.

Estradiol and progesterone synthesis in human placenta is stimulated by calcitriol

Calcitriol exerts a diverse range of biological actions including the control of growth and cell differentiation, modulation of hormone secretion, and regulation of reproductive function. The placenta synthesizes calcitriol through the expression of CYP27B1, but little is known about local actions of this hormone in the fetoplacental unit. The objective of this study was to investigate the effects of calcitriol upon progesterone (P(4)) and estradiol (E(2)) secretion in trophoblasts cultured from term human placenta. Cells were incubated in the presence of calcitriol for 18 h and pregnenolone or androstenedione were subsequently added as substrates for the 3beta-hydroxysteroid dehydrogenase (3beta-HSD) or P450-aromatase (CYP19), respectively. Calcitriol stimulated in a dose-dependent manner E(2) and P(4) secretion. The use of a selective inhibitor of PKA prevented the effects of calcitriol upon E(2) secretion, but not on P(4). These results show that calcitriol is a physiological regulator of placental E(2) and P(4) production and suggest a novel role for calcitriol upon placental steroidogenesis.

Behavioural anomalies in mice evoked by “Tokyo” disruption of the Vitamin D receptor gene

Vitamin D is a steroid hormone with many important functions in the brain, mediated through the nuclear Vitamin D receptor (VDR). Mounting clinical data link VDR mutations to various psychiatric phenotypes. We have reported previously that mutant mice lacking functional VDR ("Tokyo" VDR mutant mice) display several behavioural anomalies, including high anxiety and aberrant grooming. Given the important role of Vitamin D and VDR in brain development and functioning, we hypothesized that several other important behavioural domains may be affected by disruption of the VDR gene in mice. Here we report that VDR mutants display unaffected depressive-like behaviour, but show abnormal social behaviours, reduced social barbering and aggressiveness, impaired nest building and aberrant maternal (pup neglect, cannibalism) behaviours. Taken together, these findings confirm the important role postulated for the VDR in the regulation of behaviour, and suggest the mice lacking functional VDR may be a useful tool to model different brain disorders.