A convergent model for placental dysfunction encompassing combined sub-optimal one-carbon donor and vitamin D bioavailability

Analysis of single nucleotide polymorphisms associated with the vitamin D pathway in the placentas of women with gestational diabetes mellitus: a laboratory study

BACKGROUND

The aim of this study was to analyze the single nucleotide polymorphisms (SNPs) of genes known to be involved in vitamin D metabolism in the placenta using the placental tissue of mothers diagnosed with gestational diabetes mellitus (GDM) to determine whether the SNPs and occurrence of GDM are related.

METHODS

We enrolled 80 women of the same gestational age, 40 with and 40 without GDM. The placenta was obtained from each woman after delivery and SNP genotyping was performed on seven SNPs in the CYP27B1 (rs10877012), CYP24A1 (rs2248359, rs6013897, and rs2209314), and GC (rs2282679, rs16847024, and rs3733359) genes. Maternal serum 25-hydroxyvitamin D levels were measured during the first trimester of pregnancy and before delivery.

RESULTS

At the time of delivery, vitamin D levels were lower (21.05±12.05 mg/dL vs. 31.31±20.72 mg/dL, p=0.012) and the frequency of vitamin D deficiency was higher (60.7% vs. 32.5%, p=0.040) in the GDM group. In women with GDM, the G allele of rs10877012 was more common (86.3% vs. 65.0%, p=0.002). The rs10877012 GG genotype was more common in the GDM group (72.5% vs. 42.5%, p=0.007) and the rs10877012 TT genotype was more common in the control group (12.5% vs. 0%, p=0.007).

CONCLUSION

Mothers with GDM have lower serum concentrations of vitamin D before delivery than healthy controls and vitamin D deficiency is common. A polymorphism in CYP27B1 (rs10877012), is considered to be a cause of GDM pathogenesis.

Effect of epigenetics on vitamin D levels: a systematic review until December 2020

BACKGROUND

The association between epigenetic modification of the genes involved in the vitamin D metabolic pathway and vitamin D metabolites' status has been elucidated incompletely. This study aims to review the studies on the mentioned association and create a brighter view of this topic.

METHODS

A systematic literature search was conducted in Medline database (PubMed), Scopus, and Web of Science up to the end of November 2020. Original articles which reported the effect of epigenetic alteration-methylation level or its changes-of genes involved in vitamin D regulation on the vitamin D metabolites serum level or its changes were included. The National Institutes of Health (NIH) checklist was used to assess the quality of included articles.

RESULTS

Among 2566 records, nine reports were included in the systematic review according to the inclusion and exclusion criteria. Studies discussed the contribution of methylation status of members of the cytochrome P450 family (CYP2R1, CYP27B1, CYP24A1), and Vitamin D Receptor (VDR) genes to vitamin D level variance. CYP2R1 methylation status could regulate the contributing factors affecting the vitamin D serum level and predict response to vitamin D supplementation. Studies revealed that impaired methylation of CYP24A1 occurs in response to an increase in serum level of 25-hydroxyvitamin D (25(OH)D). It is reported that the association between methylation levels of CYP2R1, CYP24A1, and VDR genes and 25(OH)D level is not affected by the methyl-donors bioavailability.

CONCLUSIONS

The epigenetic modification of the vitamin D-related genes could explain the vitamin D levels variation among populations. Large-scale clinical trials in various ethnicities are suggested to find the effect of epigenetics on vitamin D response variation.

REGISTRATION

The systematic review protocol was registered on PROSPERO (registration number: CRD42022306327).

Placenta expression of vitamin D and related genes in pregnant women with gestational diabetes mellitus

OBJECTIVES AND METHODS

A total of 41 GDM and 40 normal glucose tolerance subjects were recruited. Through detecting the level of Serum vitamin D with electrochemical luminescence and vitamin D receptor (VDR) with Enzyme-linked immunosorbent assay (ELISA) in maternal and cord blood, the expression leves of CYP24A1, CYP27B1, VDR protein and mRNA in placenta and umbilical cord with western blotting and RT-PCR, and the DNA methylation levels of CYP24A1 and CYP27B1 gene in placenta with methylation-specific PCR (MSP) and direct bisulfite sequencing (BSP) analysis to explore the potential role of the vitamin D and its related genes in gestational diabetes mellitus (GDM).

RESULTS

Serum vitamin D concentrations were significantly higher in normal pregnant than women with GDM in maternal blood (P < 0.01) and cord blood (P = 0.014). Compared to the control group, the expression levels of CYP24A1 protein (P < 0.01) and mRNA (P = 0.021) and VDR protein (P = 0.026) and mRNA (P = 0.023) in the GDM group were significantly higher in placenta and umbilical cord tissues (P = 0.015, P < 0.01, P = 0.028, P < 0.01, respectively), while that of CYP27B1 protein (P < 0.01) and mRNA (P = 0.042) was significantly lower (P = 0.022, P = 0.032, respectively). Moreover, partial DNA methylation of CYP24A1 and CYP27B1 genes was observed in both GDM and control groups.

CONCLUSIONS

Vitamin D deficiency participates in the pathogenesis of GDM, and changes in the expression of genes related to the vitamin D metabolic pathway are closely related to vitamin D levels in the pregnancy and fetus. However, DNA methylation of CYP24A1 and CYP27B1 might not be involved in the pathogenesis of GDM.

Systematic Review of Vitamin D and Hypertensive Disorders of Pregnancy

This narrative systematic review evaluates growing evidence of an association between low maternal vitamin D status and increased risk of hypertensive disorders. The inclusion of interventional, observational, and dietary studies on vitamin D and all hypertensive disorders of pregnancy is a novel aspect of this review, providing a unique contribution to an intensively-researched area that still lacks a definitive conclusion. To date, trial evidence supports a protective effect of combined vitamin D and calcium supplementation against preeclampsia. Conflicting data for an association of vitamin D with gestational hypertensive disorders in observational studies arises from a number of sources, including large heterogeneity between study designs, lack of adherence to standardized perinatal outcome definitions, variable quality of analytical data for 25-hydroxyvitamin D (25(OH)D), and inconsistent data reporting of vitamin D status. While evidence does appear to lean towards an increased risk of gestational hypertensive disorders at 25(OH)D concentrations <50 nmol/L, caution should be exercised with dosing in trials, given the lack of data on long-term safety. The possibility that a fairly narrow target range for circulating 25(OH)D for achievement of clinically-relevant improvements requires further exploration. As hypertension alone, and not preeclampsia specifically, limits intrauterine growth, evaluation of the relationship between vitamin D status and all terms of hypertension in pregnancy is a clinically relevant area for research and should be prioritised in future randomised trials.

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.

Vitamin D in pregnancy: current perspectives and future directions

As neonatal vitamin D status is determined by circulating maternal 25-hydroxyvitamin D [25(OH)D] concentrations, prevention of maternal vitamin D deficiency during pregnancy is essential for the avoidance of neonatal deficiency. However, a high prevalence of vitamin D deficiency has been extensively reported among gravidae and neonates from ethnic minorities and white populations resident at high latitude. Currently, regulatory authorities recommend vitamin D intakes for pregnant women that are similar to non-pregnant adults of the same age, at 10-15 µg/day (400-600 IU), to meet 25(OH)D thresholds of 25-50 nmol/liter. The lack of pregnancy-specific dietary recommendations is due to inadequate data indicating whether nutritional requirements for vitamin D during pregnancy differ from the non-pregnant state. In addition, there are few dose-response studies to determine the maternal 25(OH)D response to vitamin D intake throughout pregnancy at high latitude. These data are also required to determine vitamin D requirements during pregnancy for prevention of neonatal deficiency, an outcome which is likely to require a higher maternal 25(OH)D concentration than prevention of maternal deficiency only. With regard to the impact of vitamin D on perinatal health outcomes, which could guide pregnancy-specific 25(OH)D thresholds, dietary intervention studies to date have been inconsistent and recent systematic reviews have highlighted issues of low quality and a high risk of bias as drawbacks in the trial evidence to date. Many observational studies have been hampered by a reliance on retrospective data, unclear reporting, suboptimal clinical phenotyping and incomplete subject characterization. Current investigations of vitamin D metabolism during pregnancy have potentially exciting implications for clinical research. This paper provides an update of current dietary recommendations for vitamin D in pregnant women and a synopsis of the evidence relating vitamin D status with maternal and infant health.

Maternal depression attenuates newborn vitamin D concentrations in winter-spring: a prospective population-based study

We aimed to investigate whether the newborns of mothers with maternal depression (MD) had lower vitamin D levels than newborns of non-MD (NMD) mothers and identify the potential mechanism underlying this association. Maternal depressive symptoms in late pregnancy and concentrations of cord blood 25 hydroxyvitamin D (25(OH)D) were measured in 1491 mother-infant pairs. Data on maternal sociodemographic characteristics, health status, lifestyle and birth outcomes were prospectively collected. For infants born in winter-spring, the infants of MD mothers had significantly reduced concentrations of 25(OH) D (adjusted β = −3.51 nmol/L; 95% CI: −6.19, −0.84; P = 0.010) and lower birth weight (3267 ± 470 g vs 3348 ± 598 g, F = 4.64, P = 0.031), compared with the infants of NMD mothers. A significant, inverse linear relationship was noted between maternal depression scores and the concentration of 25(OH)D for infants born in winter-spring (adjusted β = −0.158; 95% CI: −0.259, −0.057). The significant, inverse linear relationship between maternal depression scores and fetomaternal ratios of 25(OH) D was also observed among the infants born in winter-spring (adjusted β = −0.005; 95% CI: −0.008, −0.003). MD appears to significantly attenuate the vitamin D concentrations and birth weight of infants born in winter-spring. A decreased fetomaternal ratio of 25(OH)D might be involved in this biological pathway.

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.

Vitamin D deficiency and placental calcification in low-risk obstetric population: are they related?

OBJECTIVE

We aimed to evaluate the relationship between placental calcification and maternal and cord blood 25-hydroxyvitamin-D3 [25(OH)D] and calcium concentrations in low-risk obstetric population at term and their consequences.

METHODS

Sixty non-complicated pregnant women at term admitted to maternity clinic were included in this prospective case-control study and classified into one of two groups according to grade of placental calcification by defined the Grannum classification: Group 1 (n=30), with Grade 3 placenta and Group 2 (n=30), the control group, no placental calcification noted. Baseline characteristics, maternal serum and umbilical cord 25(OH)D and calcium levels were compared between groups.

RESULTS

The mean age of subjects was 26.4 ± 5.7 years. The mean serum 25(OH)D concentration of women (n=60) was 9.3 ± 3.4 (range 5.59-15.48) ng/mL. The prevalence of vitamin D deficiency [25(OH)D <20 ng/mL] was 100%. Maternal serum and cord blood calcium levels were significantly higher in Group 1 (p=0.036; p=0.037, respectively). In Group 2, maternal serum and cord blood 25(OH)D levels were higher than Group 1 (11.35 ± 6.54 and 10.22 ± 3.59 versus 9.6 ± 4.2 and 9.07 ± 2.43 ng/mL); but the difference is not statistically significant.

CONCLUSIONS

Higher maternal calcium and lower 25(OH)D levels detected in patients with Grade 3 placental calcification indicated the importance of placenta on vitamin D regulation.

Placental vitamin D receptor expression is decreased in human idiopathic fetal growth restriction

Fetal growth restriction (FGR) affects up to 5 % of pregnancies worldwide, and trophoblast function plays a significant role on the outcome. An epidemiological study has linked vitamin D deficiency to adverse perinatal outcomes, which include decreased birth weight. The placenta as an important source of vitamin D regulates its metabolism through the vitamin D receptor (VDR), but the mechanism by which VDR regulates trophoblast function is poorly understood. Our study aimed at determining placental VDR expression in FGR and gestation-matched control (GMC) pregnancies and identifying the actions of VDR in trophoblast differentiation and apoptosis. Placentae were collected from a well-defined cohort of idiopathic FGR and GMC pregnancies. VDR mRNA and protein expressions were determined by PCR, immunohistochemistry and immunoblotting, while functional consequences of VDR inactivation in vitro were determined on BeWo cells by determining changes in differentiation, attachment and apoptosis. Significant decreases in VDR mRNA expression (p = 0.0005) and protein expression (p = 0.0003) were observed in the FGR samples, while VDR inactivation, which showed markers for differentiation, cell attachment and apoptosis, was significantly increased. Thus, decreased placental VDR may contribute to uncontrolled premature differentiation and apoptosis of trophoblasts that are characteristics of idiopathic FGR pregnancies.

KEY MESSAGE

Fetal growth restriction (FGR) affects up to 5 % of all pregnancies worldwide. FGR is the second highest cause of perinatal mortality and morbidity. The placenta plays a pivotal role in vitamin D metabolism during pregnancy. Vitamin D deficiency is associated with adverse pregnancy outcomes. Placental vitamin D receptor expression is decreased in FGR.

Vitamin D deficiency in gestational diabetes mellitus and the role of the placenta

OBJECTIVE

The aim of this study was to evaluate the relationships between maternal vitamin D levels and gestational diabetes mellitus (GDM) and differences in the placental production of vitamin D receptor (VDR), CYP24A, and CYP27B1.

STUDY DESIGN

Forty normal pregnant women and 20 women with GDM were included in this study. Serum levels of 25-hydroxyvitamin D (25[OH]D) were measured with enzyme-linked immunosorbent assay. The expression and production of VDR, CYP27B1, and CYP24A1 in the placenta were evaluated with real time-polymerase chain reaction and Western blot, respectively.

RESULTS

We found that 27.5% of normal pregnant women and 85% of women with GDM had vitamin D deficiency, with serum 25(OH)D levels <20 ng/mL. Serum levels of 25(OH)D were lower in women with GDM than normal pregnant women (P < .01). The production of CYP24A1 protein and messenger RNA expression was significantly higher in placental tissue from patients with GDM than in those from normal pregnancies; however, the production of CYP27B1 and VDR protein and messenger RNA expression were not different between 2 the groups.

CONCLUSION

In this study, vitamin D deficiency was associated with GDM. Given that 25(OH)D is hydroxylated by CYP27B1 to the bioactive 1,25(OH)2D form, and CYP24A1 catabolizes both 25(OH)D and 1,25(OH)2D to the inactive metabolites, respectively, our data indicate that the elevated activity of CYP24A1 in the placenta may play a key role in the development of vitamin D deficiency in GDM.

Maternal vitamin D predominates over genetic factors in determining neonatal circulating vitamin D concentrations

BACKGROUND

There are multiple potential regulators of neonatal vitamin D status of environmental, genetic, and epigenetic origins. The relation between these factors and circulating neonatal vitamin D has yet to be fully characterized.

OBJECTIVE

The aim of this study was to examine the relative contribution of genetic factors, maternal circulating 25-hydroxyvitamin D [25(OH)D] concentrations, and the placental methylation level of the gene that encodes the primary catabolic enzyme of active vitamin D [25(OH)D-24-hydroxylase encoded by CYP24A1] to neonatal 25(OH)D concentrations.

DESIGN

We used the classical twin study design to determine the genetic contribution to neonatal 25(OH)D. A total of 86 twin pairs (32 monozygotic and 54 dizygotic twin pairs) were included in this study. Serum 25(OH)D was measured by using a 25(OH)D kit. CYP24A1 promoter DNA methylation was measured by means of matrix-assisted laser desorption time-of-flight mass spectrometry.

RESULTS

Maternal and neonatal 25(OH)D showed a strong association (R² = 0.19). Monozygotic and dizygotic within-pair serum 25(OH)D correlations were similar (R² = 0.71 and 0.67, respectively), which suggested no genetic effect. Placental CYP24A1 methylation did not show an association with maternal or neonatal 25(OH)D concentrations.

CONCLUSIONS

Our results suggest that maternal circulating 25(OH)D is the most significant regulator of neonatal circulating 25(OH)D concentrations, with underlying genetic factors playing a limited role. The placental methylation of the CYP24A1 promoter appears subject to a genetic influence, although no evidence of a relation between the methylation level of this gene and circulating maternal or neonatal 25(OH)D was apparent.

Micronutrients in pregnancy: current knowledge and unresolved questions

Micronutrient status is increasingly recognized to play an important role in the health and well-being of pregnant women and in the development and long-term health of the offspring. On 26th - 28th February 2009, The Child Health Foundation invited leading experts in this area to a scientific workshop at Obergurgl, Austria to review and critically discuss current knowledge, to identify issues that may need to be addressed in future recommendations, and to highlight priorities and opportunities for future research. This report summarizes updated key conclusions of the workshop with regards to micronutrients' intake and physiological role related to mother, placenta and fetus, as well as relevance for adverse pregnancy and long-term outcomes.