Site-specific methylation of placental HSD11B2 gene promoter is related to intrauterine growth restriction

Epigenetics of hypertension as a risk factor for the development of coronary artery disease in type 2 diabetes mellitus

Hypertension, a multifaceted cardiovascular disorder influenced by genetic, epigenetic, and environmental factors, poses a significant risk for the development of coronary artery disease (CAD) in individuals with type 2 diabetes mellitus (T2DM). Epigenetic alterations, particularly in histone modifications, DNA methylation, and microRNAs, play a pivotal role in unraveling the complex molecular underpinnings of blood pressure regulation. This review emphasizes the crucial interplay between epigenetic attributes and hypertension, shedding light on the prominence of DNA methylation, both globally and at the gene-specific level, in essential hypertension. Additionally, histone modifications, including acetylation and methylation, emerge as essential epigenetic markers linked to hypertension. Furthermore, microRNAs exert regulatory influence on blood pressure homeostasis, targeting key genes within the aldosterone and renin-angiotensin pathways. Understanding the intricate crosstalk between genetics and epigenetics in hypertension is particularly pertinent in the context of its interaction with T2DM, where hypertension serves as a notable risk factor for the development of CAD. These findings not only contribute to the comprehensive elucidation of essential hypertension but also offer promising avenues for innovative strategies in the prevention and treatment of cardiovascular complications, especially in the context of T2DM.

Select Early-Life Environmental Exposures and DNA Methylation in the Placenta

PURPOSE OF REVIEW

To summarize recent literature relating early-life environmental exposures on DNA methylation in the placenta, to identify how variation in placental methylation is regulated in an exposure-specific manner, and to encourage additional work in this area.

RECENT FINDINGS

Multiple studies have evaluated associations between prenatal environmental exposures and placental methylation in both gene-specific and epigenome-wide frameworks. Specific exposures lead to unique variability in methylation, and cross-exposure assessments have uncovered certain genes that demonstrate consistency in differential placental methylation. Exposure studies that assess methylation effects in a trimester-specific approach tend to find larger effects during the 1st trimester exposure. Earlier studies have more targeted gene-specific approaches to methylation, while later studies have shifted towards epigenome-wide, array-based approaches. Studies focusing on exposures such as air pollution, maternal smoking, environmental contaminants, and trace metals appear to be more abundant, while studies of socioeconomic adversity and circadian disruption are scarce but demonstrate remarkable effects. Understanding the impacts of early-life environmental exposures on placental methylation is critical to establishing the link between the maternal environment, epigenetic variation, and long-term health. Future studies into this field should incorporate repeated measures of exposure throughout pregnancy, in order to determine the critical windows in which placental methylation is most heavily affected. Additionally, the use of methylation-based scores and sequencing technology could provide important insights into epigenetic gestational age and uncovering more genomic regions where methylation is affected. Studies examining the impact of other exposures on methylation, including pesticides, alcohol, and other chemicals are also warranted.

Epigenetics Beyond Fetal Growth Restriction: A Comprehensive Overview

Fetal growth restriction is a pathological condition occurring when the fetus does not reach the genetically determined growth potential. The etiology of fetal growth restriction is expected to be multifactorial and include fetal, maternal, and placental factors, the latter being the most frequent cause of isolated fetal growth restriction. Severe fetal growth restriction has been related to both an increased risk of perinatal morbidity and mortality, and also a greater susceptibility to developing diseases (especially cardio-metabolic and neurological disorders) later in life. In the last decade, emerging evidence has supported the hypothesis of the Developmental Origin of Health and Disease, which states that individual developmental 'programming' takes place via a delicate fine tuning of fetal genetic and epigenetic marks in response to a large variety of 'stressor' exposures during pregnancy. As the placenta is the maternal-fetal interface, it has a crucial role in fetal programming, such that any perturbation altering placental function interferes with both in-utero fetal growth and also with the adult life phenotype. Several epigenetic mechanisms have been highlighted in modulating the dynamic placental epigenome, including alterations in DNA methylation status, post-translational modification of histones, and non-coding RNAs. This review aims to provide a comprehensive and critical overview of the available literature on the epigenetic background of fetal growth restriction. A targeted research strategy was performed using PubMed, MEDLINE, Embase, and The Cochrane Library up to January 2022. A detailed and fully referenced synthesis of available literature following the Scale for the Assessment of Narrative Review Articles guidelines is provided. A variety of epigenetic marks predominantly interfering with placental development, function, and metabolism were found to be potentially associated with fetal growth restriction. Available evidence on the role of environmental exposures in shaping the placental epigenome and the fetal phenotype were also critically discussed. Because of the highly dynamic crosstalk between epigenetic mechanisms and the extra level of complexity in interpreting the final placental transcriptome, a full comprehension of these phenomenon is still lacking and advances in multi-omics approaches are urgently needed. Elucidating the role of epigenetics in the developmental origins of health and disease represents a new challenge for the coming years, with the goal of providing early interventions and prevention strategies and, hopefully, new treatment opportunities.

The Prospective Application of Melatonin in Treating Epigenetic Dysfunctional Diseases

In the past, different human disorders were described by scientists from the perspective of either environmental factors or just by genetically related mechanisms. The rise in epigenetic studies and its modifications, i.e., heritable alterations in gene expression without changes in DNA sequences, have now been confirmed in diseases. Modifications namely, DNA methylation, posttranslational histone modifications, and non-coding RNAs have led to a better understanding of the coaction between epigenetic alterations and human pathologies. Melatonin is a widely-produced indoleamine regulator molecule that influences numerous biological functions within many cell types. Concerning its broad spectrum of actions, melatonin should be investigated much more for its contribution to the upstream and downstream mechanistic regulation of epigenetic modifications in diseases. It is, therefore, necessary to fill the existing gaps concerning corresponding processes associated with melatonin with the physiological abnormalities brought by epigenetic modifications. This review outlines the findings on melatonin’s action on epigenetic regulation in human diseases including neurodegenerative diseases, diabetes, cancer, and cardiovascular diseases. It summarizes the ability of melatonin to act on molecules such as proteins and RNAs which affect the development and progression of diseases.

Genomic imbalances in the placenta are associated with poor fetal growth

Background

Fetal growth restriction (FGR) is associated with increased risks for complications before, during, and after birth, in addition to risk of disease through to adulthood. Although placental insufficiency, failure to supply the fetus with adequate nutrients, underlies most cases of FGR, its causes are diverse and not fully understood. One of the few diagnosable causes of placental insufficiency in ongoing pregnancies is the presence of large chromosomal imbalances such as trisomy confined to the placenta; however, the impact of smaller copy number variants (CNVs) has not yet been adequately addressed. In this study, we confirm the importance of placental aneuploidy, and assess the potential contribution of CNVs to fetal growth.

Methods

We used molecular-cytogenetic approaches to identify aneuploidy in placentas from 101 infants born small-for-gestational age (SGA), typically used as a surrogate for FGR, and from 173 non-SGA controls from uncomplicated pregnancies. We confirmed aneuploidies and assessed mosaicism by microsatellite genotyping. We then profiled CNVs using high-resolution microarrays in a subset of 53 SGA and 61 control euploid placentas, and compared the load, impact, gene enrichment and clinical relevance of CNVs between groups. Candidate CNVs were confirmed using quantitative PCR.

Results

Aneuploidy was over tenfold more frequent in SGA-associated placentas compared to controls (11.9% vs. 1.1%; p = 0.0002, OR = 11.4, 95% CI 2.5–107.4), was confined to the placenta, and typically involved autosomes, whereas only sex chromosome abnormalities were observed in controls. We found no significant difference in CNV load or number of placental-expressed or imprinted genes in CNVs between SGA and controls, however, a rare and likely clinically-relevant germline CNV was identified in 5.7% of SGA cases. These CNVs involved candidate genes INHBB, HSD11B2, CTCF, and CSMD3.

Conclusions

We conclude that placental genomic imbalances at the cytogenetic and submicroscopic level may underlie up to ~ 18% of SGA cases in our population. This work contributes to the understanding of the underlying causes of placental insufficiency and FGR, which is important for counselling and prediction of long term outcomes for affected cases.

Associations between in utero exposure to polybrominated diphenyl ethers, pathophysiological state of fetal growth and placental DNA methylation changes

BACKGROUND

Polybrominated diphenyl ethers (PBDEs) are environmental chemicals with harmful effects on pregnancy, but their effects on adverse developmental outcomes are not fully understood. The placental DNA methylation is strongly influenced by prenatal environmental factors and has been linked to fetal growth.

OBJECTIVE

To evaluate the association between in utero PBDEs exposure, placental DNA methylation changes (growth regulatory genes), and pathophysiology of fetal growth (birth outcomes, fetal growth retardation) in a population-based pregnancy cohort study.

METHODS

This was a nested case-control study within the prospective Wenzhou Birth Cohort including 130 fetal growth retardation (FGR) cases and 130 healthy controls and their mothers recruited from June 2016 to June 2017. FGR was diagnosed based on the comprehensive evaluation of ultrasound results at 24, 28, and 32 weeks of gestation. Neonatal birth measurements were obtained from medical records. Gestational exposure to 19 PBDEs, including 13 lower BDE congeners (BDE-17-190) and 6 higher brominated BDE congeners (BDE-196-209), were determined by gas chromatography tandem mass spectrometry in the umbilical cord blood. Placental DNA methylation changes of one repetitive element (LINE1) and two candidate genes (HSD11B2, IGF2) were characterized by quantitative polymerase chain reaction-pyrosequencing. Multiple linear regression and logistic regression models were used to examine the associations among PBDEs exposure, fetal growth indicators, and DMR (differential methylation region) methylation fractions. Sobel tests were conducted to assess DNA methylation as a mediator in multivariate models.

RESULTS

After excluding women who withdrew from the study or were lost to follow-up or failed to provide placenta or umbilical cord blood, 249 mother-newborn pairs (124 FGR cases, 125 controls) were included in the final analysis. Elevated BDE-206 (OR: 1.569, 95% CIs: 1.053-2.338), BDE-17-190 (OR: 2.860, 95% CIs: 1.233-6.634), BDE-196-209 (OR: 1.688, 95% CIs: 1.024-2.783) and ∑₁₉PBDEs (OR: 2.387, 95% CIs: 1.220-4.668) concentrations were associated with increased risk of FGR in newborns. FGR birth was also associated with increased DNA methylation of HSD11B2 (OR: 1.145, 95% CIs: 1.032-1.270) and decreased DNA methylation of IGF2 (OR: 0.892, 95% CIs: 0.845-0.941). In addition, BDE-17-190 showed significant associations with DNA methylation of HSD11B2 and IGF2 (β: 1.127, 95% CIs: 0.069-2.186; β: -3.452, 95% CIs: -5.512-1.392), indicating placental DNA methylation changes of HSD11B2 and IGF2 were related to both lower BDE congeners exposure and fetal growth. Further mediation analyses showed that IGF2 methylation mediated about 40% of the effects of BDE-17-190 in umbilical cord blood on neonatal FGR.

CONCLUSION

We report an inverse association between in utero exposures to PBDEs and fetal growth and provide evidence supporting epigenetic gene plasticity in these associations. Changes in placental DNA methylation might be part of the underlying biological pathway between prenatal PBDEs exposure and adverse fetal growth.

Epigenetic modification: a regulatory mechanism in essential hypertension

Essential hypertension (EH) is a multifactorial disease of the cardiovascular system that is influenced by the interplay of genetic, epigenetic, and environmental factors. The molecular dynamics underlying EH etiopathogenesis is unknown; however, earlier studies have revealed EH-associated genetic variants. Nevertheless, this finding alone is not sufficient to explain the variability in blood pressure, suggesting that other risk factors are involved, such as epigenetic modifications. Therefore, this review highlights the potential contribution of well-defined epigenetic mechanisms in EH, specifically, DNA methylation, post-translational histone modifications, and microRNAs. We further emphasize global and gene-specific DNA methylation as one of the most well-studied hallmarks among all epigenetic modifications in EH. In addition, post-translational histone modifications, such as methylation, acetylation, and phosphorylation, are described as important epigenetic markers associated with EH. Finally, we discuss microRNAs that affect blood pressure by regulating master genes such as those implicated in the renin-angiotensin-aldosterone system. These epigenetic modifications, which appear to contribute to various cardiovascular diseases, including EH, may be a promising research area for the development of novel future strategies for EH prevention and therapeutics.

The Role of 11β-Hydroxy Steroid Dehydrogenase Type 2 in Glucocorticoid Programming of Affective and Cognitive Behaviours

Developmental exposure to stress hormones, i.e. glucocorticoids, is central to the process of prenatal programming of later-life health. Glucocorticoid overexposure, through stress or exogenous glucocorticoids, results in a reduced birthweight, as well as affective and neuropsychiatric outcomes in adults, combined with altered hypothalamus-pituitary-adrenal (HPA) axis activity. As such, glucocorticoids are tightly regulated during development through the presence of the metabolizing enzyme 11β-hydroxysteroid dehydrogenase type 2 (HSD2). HSD2 is highly expressed in 2 hubs during development, i.e. the placenta and the fetus itself, protecting the fetus from inappropriate glucocorticoid exposure early in gestation. Through manipulation of HSD2 expression in the mouse placenta and fetal tissues, we are able to determine the relative contribution of glucocorticoid exposure in each compartment. Feto-placental HSD2 deletion resulted in a reduced birthweight and the development of anxiety- and depression-like behaviours in adult mice. The placenta itself is altered by glucocorticoid overexposure, which causes reduced placental weight and vascular arborisation. Furthermore, altered flow and resistance in the umbilical vessels and modification of fetal heart function and development are observed. However, brain-specific HSD2 removal (HSD2BKO) also generated adult phenotypes of depressive-like behaviour and memory deficits, demonstrating the importance of fetal brain HSD2 expression in development. In this review we will discuss potential mechanisms underpinning early-life programming of adult neuropsychiatric disorders and the novel therapeutic potential of statins.

Mechanisms for establishment of the placental glucocorticoid barrier, a guard for life

The fetus is shielded from the adverse effects of excessive maternal glucocorticoids by 11β-HSD2, an enzyme which is expressed in the syncytial layer of the placental villi and is capable of converting biologically active cortisol into inactive cortisone. Impairment of this placental glucocorticoid barrier is associated with fetal intrauterine growth restriction (IUGR) and development of chronic diseases in later life. Ontogeny studies show that the expression of 11β-HSD2 is initiated at a very early stage after conception and increases with gestational age but declines around term. The promoter for HSD11B2, the gene encoding 11β-HSD2, has a highly GC-rich core. However, the pattern of methylation on HSD11B2 may have already been set up in the blastocyst when the trophoblast identity is committed. Instead, hCG-initiated signals appear to be responsible for the upsurge of 11β-HSD2 expression during trophoblast syncytialization. By activating the cAMP/PKA pathway, hCG not only alters the modification of histones but also increases the expression of Sp1 which activates the transcription of HSD11B2. Adverse conditions such as stress, hypoxia and nutritional restriction can cause IUGR of the fetus. It appears that different causes of IUGR may attenuate HSD11B2 expression differentially in the placenta. While stress and nutritional restriction may reduce HSD11B2 expression by increasing its methylation, hypoxia may decrease HSD11B2 expression via alternative mechanisms rather than by methylation. Herein, we summarize the advances in the study of mechanisms underlying the establishment of the placental glucocorticoid barrier and the attenuation of this barrier by adverse conditions during pregnancy.

Physical activity and epigenetic biomarkers in maternal blood during pregnancy

AIM

Investigate associations of leisure time physical activity (LTPA) with DNA methylation and miRNAs during pregnancy. Patients & methods: LTPA, candidate DNA methylation and circulating miRNAs were measured (average 15 weeks gestation) in pregnant women (n = 92).

RESULTS

Each additional hour of prepregnancy LTPA duration was associated with hypermethylation in C1orf212 (β = 0.137, 95% CI: 0.004-0.270) and higher circulating miR-146b-5p (β = 0.084, 95% CI: 0.017-0.151). Each additional metabolic equivalent hour of early-pregnancy LTPA energy expenditure was associated with higher circulating miR-21-3p (β = 0.431, 95% CI: 0.089-0.772) in women carrying female offspring, and lower circulating miR-146b-5p (β = -0.285, 95% CI: -0.528 to -0.043) and miR-517-5p (β = -0.406, 95% CI: -0.736 to -0.076) in women carrying male offspring.

CONCLUSION

Our findings suggest that LTPA may influence maternal epigenetic biomarkers, possibly in an offspring sex-specific manner.

Maternal distress in late pregnancy alters obstetric outcomes and the expression of genes important for placental glucocorticoid signalling

The experience of maternal distress in pregnancy is often linked with poorer obstetric outcomes for women as well as adverse outcomes for offspring. Alterations in placental glucocorticoid signalling and subsequent increased fetal exposure to cortisol have been suggested to underlie this relationship. In the current study, 121 pregnant women completed the Perceived Stress Scale, State Trait Anxiety Inventory and Edinburgh Postnatal Depression Scale in the third trimester of pregnancy. Placental samples were collected after delivery. Maternal history of psychiatric illness and miscarriage were significant predictors of poorer mental health in pregnancy. Higher anxiety was associated with an increase in women delivering via elective Caesarean Section, and an increase in bottle-feeding. Birth temperature was mildly reduced among infants of women with high levels of depressive symptomology. Babies of mothers who scored high in all stress (cumulative distress) measures had reduced 5-min Apgar scores. High cumulative distress reduced the expression of placental HSD11B2 mRNA and increased the expression of placental NR3C1 mRNA. These data support a role for prenatal distress as a risk factor for altered obstetric outcomes. The alterations in placental gene expression support a role for altered placental glucocorticoid signalling in the relationship between maternal prenatal distress and adverse outcomes.

11 beta-hydroxysteroid dehydrogenase 2 promoter methylation is associated with placental protein expression in small for gestational age newborns

Small for gestational age infants have greater risk of developing metabolic diseases in adult life. It has been suggested that low birth weight may result from glucocorticoid excess in utero, a key mechanism in fetal programming. The placental enzyme 11-beta hydroxysteroid dehydrogenase type 2 (11β-HSD2, HSD11B2 gene) acts as a barrier protecting the fetus from maternal corticosteroid deleterious effects. Low placental 11β-HSD2 transcription and activity have been associated with low birth weight, yet the mechanism regulating its protein expression is not fully understood. In the present study we aimed to analyze 11β-HSD2 protein expression in placentas of adequate and small for gestational age (AGA and SGA, respectively) newborns from healthy mothers, and to explore whether 11β-HSD2 protein expression could be modulated by DNA methylation. 11β-HSD2 protein levels were measured by western blot in placental biopsies from term AGA and SGA infants (n=10 per group). DNA methylation was profiled both globally and in the HSD11B2 promoter by liquid chromatography with UV detection and methylation-specific melting curve analysis, respectively. We found lower placental 11β-HSD2 protein expression and higher HSD11B2 promoter methylation in SGA compared to AGA. Promoter methylation was inversely correlated with both protein expression and, importantly, birth weight. No changes in global placental methylation were found. In conclusion, lower 11β-HSD2 protein expression is associated with higher HSD11B2 promoter methylation, correlating with birth weight in healthy pregnancy. Our data support the role of 11β-HSD2 in determining birth weight, providing evidence of its regulation by epigenetic mechanisms, which may affect postnatal metabolic disease risk.

Molecular mechanisms of intrauterine growth restriction

Intrauterine growth restriction (IUGR) is a pregnancy specific disease characterized by decreased growth rate of fetus than the normal growth potential at particular gestational age. In the current scenario it is a leading cause of fetal and neonatal morbidity and mortality. In the last decade exhilarating experimental studies from several laboratories have provided fascinating proof for comprehension of molecular basis of IUGR. Atypical expression of enzymes governed by TGFβ causes the placental apoptosis and altered expression of TGFβ due to hyper alimentation causes impairment of lung function. Crosstalk of cAMP with protein kinases plays a prominent role in the regulation of cortisol levels. Increasing levels of NOD1 proteins leads to development of IUGR by increasing the levels of inflammatory mediators. Increase in leptin synthesis in placental trophoblast cells is associated with IUGR. In this review, we emphasize on the regulatory mechanisms of IUGR and its associated diseases. They may help improve the in-utero fetal growth and provide a better therapeutic intervention for prevention and treatment of IUGR.

A repressive role of enhancer of zeste homolog 2 in 11β-hydroxysteroid dehydrogenase type 2 expression in the human placenta

The expression of 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2), which acts as a placental glucocorticoid barrier, is silenced in cytotrophoblasts but substantially up-regulated during syncytialization. However, the repressive mechanism of 11β-HSD2 expression before syncytialization and how this repression is lifted during syncytialization remain mostly unresolved. Here we found that enhancer of zeste homolog 2 (EZH2) accounts for the silence of 11β-HSD2 expression via trimethylation of histone H3 lysine 27 at the promoter of the 11β-HSD2 gene. Further studies revealed that, upon syncytialization, human chorionic gonadotropin reduced the phosphorylation of retinoblastoma protein (pRB) via activation of the cAMP/PKA pathway, which sequesters E2F transcription factor 1 (E2F1), the transcription factor for EZH2 expression. As a result of inactivation of the pRB-E2F1-EZH2 pathway, the repressive marker trimethylation of histone H3 lysine 27 at the 11β-HSD2 promoter is removed, which leads to the robust expression of 11β-HSD2 during syncytialization.

Tissue differences in DNA methylation changes at AHRR in full term low birth weight in maternal blood, placenta and cord blood in Chinese

INTRODUCTION

Very few study addressed the relationship between Aryl-hydrocarbon receptor repressor (AHRR) DNA methylation and low birth weight, especially in multiple tissues of mother-infant pairs. In this study, we aimed to investigate AHRR DNA methylation modification in cord blood, placenta and maternal blood between full term low birth weight (FT-LBW) and full term normal birth weight (FT-NBW) newborns.

METHODS

We enrolled 90 FT-LBW and 90 FT-NBW mother-infant pairs, of which all placenta and cord blood samples were collected while 45 maternal blood samples of each group were collected. We measured AHRR DNA methylation (Chr5: 373013-373606) using Sequenom MassARRAY, and assessed associations between AHRR DNA methylation and FT-LBW using logistic regression adjusting for maternal age, education, family income, delivery mode, and passive smoking.

RESULTS

FT-LBW babies had 3% lower methylation at Chr5: 373378 (CpG 13) in cord blood, and 4-9% higher methylation levels at Chr5: 373315, 373378, 373423, 373476 and 373490/373494 (CpG 10; 13; 15; 16; 17/18 respectively) in maternal blood, comparing with FT-NBW. The methylation of Chr5: 373378 (CpG 13) remained significant association with FT-LBW both in cord blood (OR = 0.90; 95% CI: 0.82, 0.98) and maternal blood (OR = 1.14; 95% CI: 1.04, 1.25) further adjusting for each other in the same model. We observed no significant difference at any CpG sites in placenta.

DISCUSSION

AHRR DNA methylation of cord and maternal blood might be independently associated with FT-LBW in different ways.

Variants of HSD11B2 gene in hypertensive disorders of pregnancy

INTRODUCTION

One of the hypotheses concerning the etiology of gestational hypertension (GH) and pre-eclampsia (PE) assumes that they develop as a result of placenta malfunctioning at the early stage of pregnancy. Placental dysfunction is also associated with the decreased activity of 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2), which in normal pregnancy protects the fetus from the excess of maternal cortisol.

OBJECTIVE

The aim of the study was to analyze the sequence of HSD11B2, a gene that encodes 11β-HSD2, searching for mutations and haplotypes associated with the increased risk of GH or PE. Those may serve as potential genetic markers of GH and PE.

METHODS

The study was performed in case-control structure and included pregnant women (in third trimester) diagnosed with: GH, PE or being normotensive (control group). The research comprised DNA sequencing of HSD11B2, followed by restriction analysis (PCR-RFLP). The linkage disequilibrium analysis and haplotype-based case-control analysis were performed.

RESULTS

Six sequence variations were observed. Four mutations were indicated in the coding region of HSD11B2 and the other two in 3'-UTR. Two SNPs: c.468C > A and c.534G > A were found to be in total disequilibrium.

CONCLUSIONS

High variability in HSD11B2 sequence was indicated in the study population, but the relevance of observed SNPs to GH or PE development was not confirmed.

Adverse maternal exposures, methylation of glucocorticoid-related genes and perinatal outcomes: a systematic review

Aim: Maternal environmental exposures affect perinatal outcomes through epigenetic placental changes. We examine the literature addressing associations between adverse maternal exposures, perinatal outcomes and methylation of key genes regulating placental cortisol metabolism. Methods: We searched three databases for studies that examined NR3C1 and HSD11β1/HSD11 β 2 methylation with maternal exposures or perinatal outcomes. Nineteen studies remained after screening. We followed Cochrane's PRISMA reporting guidelines (2009). Results: NR3C1 and HSD11 β methylation were associated with adverse infant neurobehavior, stress response, blood pressure and physical development. In utero exposure to maternal stress, nutrition, preeclampsia, smoking and diabetes were associated with altered NR3C1 and HSD11 β methylation. Conclusion: NR3C1 and HSD11 β methylation are useful biomarkers of specific environmental stressors associated with important perinatal outcomes that determine pediatric and adult disease risk.

11β-Hydroxysteroid Dehydrogenase 2 in Preeclampsia

Preeclampsia is a serious medical problem affecting the mother and her child and influences their health not only during the pregnancy, but also many years after. Although preeclampsia is a subject of many research projects, the etiology of the condition remains unclear. One of the hypotheses related to the etiology of preeclampsia is the deficiency in placental 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2), the enzyme which in normal pregnancy protects the fetus from the excess of maternal cortisol. The reduced activity of the enzyme was observed in placentas from pregnancies complicated with preeclampsia. That suggests the overexposure of the developing child to maternal cortisol, which in high levels exerts proapoptotic effects and reduces fetal growth. The fetal growth restriction due to the diminished placental 11β-HSD2 function may be supported by the fact that preeclampsia is often accompanied with fetal hypotrophy. The causes of the reduced function of 11β-HSD2 in placental tissue are still discussed. This paper summarizes the phenomena that may affect the activity of the enzyme at various steps on the way from the gene to the protein.

Fetal growth restriction and methylation of growth-related genes in the placenta

AIM

To examine the associations between fetal growth restriction (FGR) and DNA methylation of six growth-related genes in human placenta.

MATERIALS & METHODS

A total of 181 mother-newborn pairs (80 FGR cases and 101 controls) were enrolled in this case-control study. Placental DNA methylation was measured by bisulfite pyrosequencing.

RESULTS

DNA methylation levels of IGF2 and AHRR were positively associated with newborn birth weight and Quetelet's index, while DNA methylation levels of HSD11B2 and WNT2 were negatively associated with those fetal growth indicators. In addition, significantly elevated odds of FGR birth were associated with increasing DNA methylation of HSD11B2 and WNT2, and decreasing DNA methylation of IGF2.

CONCLUSION

Our findings demonstrated that placental DNA methylation levels of IGF2, AHRR, HSD11B2 and WNT2 were associated with measures of fetal growth.

Heritable IUGR and adult metabolic syndrome are reversible and associated with alterations in the metabolome following dietary supplementation of 1-carbon intermediates

Metabolic syndrome (MetS), following intrauterine growth restriction (IUGR), is epigenetically heritable. Recently, we abrogated the F2 adult phenotype with essential nutrient supplementation (ENS) of intermediates along the 1-carbon pathway. With the use of the same grandparental uterine artery ligation model, we profiled the F2 serum metabolome at weaning [postnatal day (d)21; n = 76] and adulthood (d160; n = 12) to test if MetS is preceded by alterations in the metabolome. Indicative of developmentally programmed MetS, adult F2, formerly IUGR rats, were obese (621 vs. 461 g; P < 0.0001), dyslipidemic (133 vs. 67 mg/dl; P < 0.001), and glucose intolerant (26 vs. 15 mg/kg/min; P < 0.01). Unbiased gas chromatography-mass spectrometry (GC-MS) profiling revealed 34 peaks corresponding to 12 nonredundant metabolites and 9 unknowns to be changing at weaning [false discovery rate (FDR) < 0.05]. Markers of later-in-life MetS included citric acid, glucosamine, myoinositol, and proline (P < 0.03). Hierarchical clustering revealed grouping by IUGR lineage and supplementation at d21 and d160. Weanlings grouped distinctly for ENS and IUGR by partial least-squares discriminate analysis (PLS-DA; P < 0.01), whereas paternal and maternal IUGR (IUGR(pat)/IUGR(mat), respectively) control-fed rats, destined for MetS, had a distinct metabolome at weaning (randomForest analysis; class error < 0.1) and adulthood (PLS-DA; P < 0.05). In sum, we have found that alterations in the metabolome accompany heritable IUGR, precede adult-onset MetS, and are partially amenable to dietary intervention.

The Role of Placental 11-Beta Hydroxysteroid Dehydrogenase Type 1 and Type 2 Methylation on Gene Expression and Infant Birth Weight

Maternal stress has been linked to infant birth weight outcomes, which itself may be associated with health later in life. The placenta acts as a master regulator for the fetal environment, mediating intrauterine exposures to stress through the activity of genes regulating glucocorticoids, including the 11beta-hydroxysteroid dehydrogenase (HSD11B) type 1 and 2 genes, and so we hypothesized that variation in these genes will be associated with infant birth weight. We investigated DNA methylation levels at six sites across the two genes, as well as mRNA expression for each, and the relationship to infant birth weight. Logistic regressions correcting for potential confounding factors revealed a significant association between methylation at a single CpG site within HSD11B1 and being born large for gestational age. In addition, our analysis identified correlations between methylation and gene expression, including sex-specific transcriptional regulation of HSD11B2. Our work is one of the first comprehensive views of DNA methylation and expression in the placenta for both HSD11B types 1 and 2, linking epigenetic alterations with the regulation of fetal stress and birth weight outcomes.

Epigenetics and arterial hypertension: the challenge of emerging evidence

Epigenetic phenomena include DNA methylation, post-translational histone modifications, and noncoding RNAs, as major marks. Although similar to genetic features of DNA for their heritability, epigenetic mechanisms differ for their potential reversibility by environmental and nutritional factors, which make them potentially crucial for their role in complex and multifactorial diseases. The function of these mechanisms is indeed gaining interest in relation to arterial hypertension (AH) with emerging evidence from cell culture and animal models as well as human studies showing that epigenetic modifications have major functions within pathways related to AH. Among epigenetic marks, the role of DNA methylation is mostly highlighted given the primary role of this epigenetic feature in mammalian cells. A lower global methylation was observed in DNA of peripheral blood mononuclear cells of hypertensive patients. Moreover, DNA hydroxymethylation appears modifiable by salt intake in a Dahl salt-sensitive rat model. The specific function of DNA methylation in regulating the expression of AH-related genes at promoter site was described for hydroxysteroid (11-beta) dehydrogenase 2 (HSD11B2), somatic angiotensin converting enzyme (sACE), Na+/K+/2Cl- cotransporter 1 (NKCC1), angiotensinogen (AGT), α-adducin (ADD1), and for other crucial genes in endocrine hypertension. Post-translational histone methylation at different histone 3 lysine residues was also observed to control the expression of genes related to AH as lysine-specific demethylase-1(LSD1), HSD11B2, and epithelial sodium channel subunit α (SCNN1A). Noncoding RNAs including several microRNAs influence genes involved in steroidogenesis and the renin-angiotensin-aldosterone pathway. In the present review, the current knowledge on the relationship between the main epigenetic marks and AH will be presented, considering the challenge of epigenetic patterns being modifiable by environmental factors that may lead toward novel implications in AH preventive and therapeutic strategies.

Alteration in methylation level at 11β-hydroxysteroid dehydrogenase type 2 gene promoter in infants born to preeclamptic women

Background

Preeclampsia reduces placental expression and activity of 11β-hydroxysteroid dehydrogenase type 2 (HSD11B2), leading to an increase in fetal glucocordicoids. The latter has been proposed to be associated with low birth weight and high risk of metabolic diseases in later life of the offspring. This investigation aims to delineate the alteration in methylation levels at CpG sites of HSD11B2 promoter.

Results

Methylation levels of HSD9-2, HSD9-3, HSD23-2 and HSD23-3 and the mean methylation level were significantly lower in preeclampsia than in normal pregnancy (P = 0.002, 0.031, 0.047 and 0.001, respectively and P < 0.001 in mean). The mean methylation level was significantly correlated with preeclampsia after the adjustment of birth weight, maternal age, gestational age at delivery and fetal gender (r = 0.325, P < 0.001).

Conclusions

Preeclampsia reduced methylation level at fetal HSD11B2 promoter. A positive correlation existed between HSD11B2 promoter methylation and preeclampsia. Our findings suggest that the methyaltion status of HSD11B2 promoter is a potentially accessible biomarker for preeclampsia. However, further studies are required to address the mechanisms of thehypomethylation at HSD11B2 promoter and the significance of the hypomethylation in the development of metabolic diseases of the fetals born to preeclamptic women.