Methylation levels at IGF2 and GNAS DMRs in infants born to preeclamptic pregnancies

DNA methylation landscape in pregnancy-induced hypertension: progress and challenges

Gestational hypertension (PIH), especially pre-eclampsia (PE), is a common complication of pregnancy. This condition poses significant risks to the health of both the mother and the fetus. Emerging evidence suggests that epigenetic modifications, particularly DNA methylation, may play a role in initiating the earliest pathophysiology of PIH. This article describes the relationship between DNA methylation and placental trophoblast function, genes associated with the placental microenvironment, the placental vascular system, and maternal blood and vascular function, abnormalities of umbilical cord blood and vascular function in the onset and progression of PIH, as well as changes in DNA methylation in the progeny of PIH, in terms of maternal, fetal, and offspring. We also explore the latest research on DNA methylation-based early detection, diagnosis and potential therapeutic strategies for PIH. This will enable the field of DNA methylation research to continue to enhance our understanding of the epigenetic regulation of PIH genes and identify potential therapeutic targets.

Epigenetic implications in maternal diabetes and metabolic syndrome-associated risk of orofacial clefts

Orofacial clefts (OFCs) are one of the most common types of structural birth defects. The etiologies are complicated, involving with genetic, epigenetic, and environmental factors. Studies have found that maternal diabetes and metabolic syndrome are associated with a higher risk of OFCs in offspring. Metabolic syndrome is a clustering of several disease risk factors, including hyperglycemia, dyslipidemia, obesity, and hypertension. Metabolic disease during pregnancy can increase risk of adverse outcomes and significantly influence fetal development, including orofacial formation and fusion. An altered metabolic state may contribute to developmental disorders or congenital defects including OFCs, potentially through epigenetic modulations, such as histone modification, DNA methylation, and noncoding RNA expression to alter activities of critical morphogenetic signaling or related developmental genes. This review summarizes the currently available evidence and underlying mechanisms of how the maternal metabolic syndrome is associated with OFCs in mostly human and some animal studies. It may provide a better understanding of the interactions between intrauterine metabolic status and fetal orofacial development which might be applied toward prevention and treatments of OFCs.

Small RNA sequencing of exosomal microRNAs reveals differential expression of microRNAs in preeclampsia

Preeclampsia (PE) is one of the most common hypertensive disorders of pregnancy. It is a dangerous condition with a high mortality rate in mothers and fetuses and is associated with a lack of early diagnosis and effective treatment. While the etiology of the disease is complex and obscure, it is now clear that the placenta is central to disease progression. Exosomal microRNAs (miRNAs) are possible mediators that regulate placenta-related physiological and pathological processes. Placental mesenchymal stem cells have considerable potential to help us understand the pathogenesis and treatment of pregnancy-related diseases. Here, we investigate the exosomal miRNA profiles of human placenta-derived mesenchymal stem cells between healthy pregnant women and those with PE. We performed small RNA sequencing to obtain miRNA profiles, and conducted enrichment analysis of the miRNA target genes to identify differentially expressed miRNAs associated with PE. Overall, we detected 1795 miRNAs; among them, 206 were differentially expressed in women with PE, including 35 upregulated and 171 downregulated miRNAs, when compared with healthy pregnant women. Moreover, we identified possible functions and pathways associated with PE, including angiogenesis, cell proliferation, migration and invasion, and the coagulation-fibrinolysis balance. Eventually, we proposed hsa-miR-675-5p, hsa-miR-3614-5p, and hsa-miR-615-5p as potential regulators of the pathogenesis of PE, and constructed a miRNA-target gene network. Our study identifies possible candidate biomarkers for the diagnosis of PE, and introduces a new direction for further understanding the pathogenesis of PE.

Severe preeclampsia is not associated with significant DNA methylation changes but cell proportion changes in the cord blood - caution on the importance of confounding adjustment

Epigenome-wide DNA methylation analysis (EWAS) is an important approach to identify biomarkers for early disease detection and prognosis prediction, yet its results could be confounded by other factors such as cell-type heterogeneity and patient characteristics. In this study, we address the importance of confounding adjustment by examining DNA methylation patterns in cord blood exposed to severe preeclampsia (PE), a prevalent and potentially fatal pregnancy complication. Without such adjustment, a misleading global hypomethylation pattern is obtained. However, after adjusting cell type proportions and patient clinical characteristics, most of the so-called significant CpG methylation changes associated with severe PE disappear. Rather, the major effect of PE on cord blood is through the proportion changes in different cell types. These results are validated using a previously published cord blood DNA methylation dataset, where global hypomethylation pattern was also wrongfully obtained without confounding adjustment. Additionally, several cell types significantly change as gestation progress (eg. granulocyte, nRBC, CD4T, and B cells), further confirming the importance of cell type adjustment in EWAS study of cord blood tissues. Our study urges the community to perform confounding adjustments in EWAS studies, based on cell type heterogeneity and other patient characteristics.

Comprehensive analysis of transcriptomic profiling of 5-methylcytosin modification in placentas from preeclampsia and normotensive pregnancies

Increasing evidence suggests that RNA m5C modification and its regulators have been confirmed to be associated with the pathogenesis of many diseases. However, the distribution and biological functions of m5C in mRNAs of placental tissues remain unknown. we collected placentae from normotensive pregnancies (CTR) and preeclampsia patients (PE) to analyze the transcriptomic profiling of m5C RNA methylation through m5C RNA immunoprecipitation (UMI-MeRIP-Seq). we discovered that overall m5C methylation peaks were decreased in placental tissues from PE patients. And, 2844 aberrant m5C peaks were identified, of which respectively 1304 m5C peaks were upregulated and 1540 peaks were downregulated. The distribution of m5C peaks were mainly located in CDS (coding sequences) regions in placental tissues of both groups, but compared with the CTR group, the m5C peak in PE group before the stop code of CDS was significantly increased and even higher than the peak value after start code in CDS. Differentially methylated genes were mainly enriched in MAPK/cAMP signaling pathway. Moreover, the up-regulated genes with hypermethylated modification were enriched in the processes of hypoxia, inflammation/immune response. Finally, through analyzing the mRNA expression levels of m5C RNA methylation regulators, we found only DNMT3B and TET3 were significantly upregulated in PE samples than in control group. And they are not only negatively correlated with each other, but also closely related to those differentially expressed genes modified by differential methylation.Our findings provide new insights regarding alterations of m5C RNA modification into the pathogenic mechanisms of PE.

Hypertensive disorders of pregnancy share common cfDNA methylation profiles

Hypertensive disorders of pregnancy (HDP) contribute substantially to perinatal morbidity and mortality. Epigenetic changes point towards cardio-metabolic dysregulation for these vascular disorders. In early pregnancy, epigenetic changes using cell free DNA (cfDNA) are largely unexplored. We aimed to investigate these in HDP between 11 and 14 weeks of gestation by analysis of cfDNA methylation profiles in patients with hypertensive disorders. We identified patients without chronic hypertension but with subsequent development of preeclampsia (PE) (n = 11), with chronic hypertension (HT) but without PE development (n = 14), and lacking both PE and HT (n = 422). We matched patients according to PE risk factors into three groups (n = 5 each group): (1) PE: no HT but PE development, (2) HT: chronic hypertension but no PE and (3) Control: no PE or HT. We successfully optimized our cfDNA isolation process prior to whole genome bisulfite sequencing. Analysis of cfDNA methylation changes indicate a common predisposition in PE and HT groups, chiefly of maternal origin. Assessment of significant differentially methylated regions and annotated genes point towards a common cardiovascular predisposition in preeclampsia and hypertension groups in the first trimester. We postulate the pivotal role of the maternal cardiovascular system in HDP, which is already evident in the first trimester.

Aging, inflammation and DNA damage in the somatic testicular niche with idiopathic germ cell aplasia

Molecular mechanisms associated with human germ cell aplasia in infertile men remain undefined. Here we perform single-cell transcriptome profiling to highlight differentially expressed genes and pathways in each somatic cell type in testes of men with idiopathic germ cell aplasia. We identify immaturity of Leydig cells, chronic tissue inflammation, fibrosis, and senescence phenotype of the somatic cells, as well markers of chronic inflammation in the blood. We find that deregulated expression of parentally imprinted genes in myoid and immature Leydig cells, with relevant changes in the ratio of Lamin A/C transcripts and an active DNA damage response in Leydig and peritubular myoid cells are also indicative of senescence of the testicular niche. This study offers molecular insights into the pathogenesis of idiopathic germ cell aplasia.

Molecular mechanisms associated with human germ cell aplasia in infertile men remain undefined. Here the authors perform single-cell transcriptome profiling to highlight differentially expressed genes and pathways in each somatic cell type in testes of men with idiopathic germ cell aplasia.

The Prenatal Hormone Milieu in Autism Spectrum Disorder

Though the etiology of autism spectrum disorder (ASD) remains largely unknown, recent findings suggest that hormone dysregulation within the prenatal environment, in conjunction with genetic factors, may alter fetal neurodevelopment. Early emphasis has been placed on the potential role of in utero exposure to androgens, particularly testosterone, to theorize ASD as the manifestation of an "extreme male brain." The relationship between autism risk and obstetric conditions associated with inflammation and steroid dysregulation merits a much broader understanding of the in utero steroid environment and its potential influence on fetal neuroendocrine development. The exploration of hormone dysregulation in the prenatal environment and ASD development builds upon prior research publishing associations with obstetric conditions and ASD risk. The insight gained may be applied to the development of chronic adult metabolic diseases that share prenatal risk factors with ASD. Future research directions will also be discussed.

Systemic transcriptome comparison between early- And late-onset pre-eclampsia shows distinct pathology and novel biomarkers

Objectives

Pre‐eclampsia is a leading cause of morbidity and mortality during pregnancy. Although the two forms of this disorder, early‐ (EOPE) and late‐onset of pre‐eclampsia (LOPE) are different, the underlying pathology remains elusive. We aim to unravel the difference and to identify novel biomarkers for EOPE and LOPE.

Materials and Methods

A complete comparison of both placental and peripheral blood transcriptomes was performed to investigate the pathology of pre‐eclampsia. Single‐cell transcriptomics of the maternal‐fetal interface were integrated to identify novel biomarkers for EOPE and LOPE which were further verified at protein or mRNA level in patients.

Results

We found that the transcriptomes of placentae from EOPE, but not LOPE, were significantly different from their respective controls. Conversely, the transcriptomes of peripheral blood from LOPE were more different from their controls than EOPE. Importantly, we identified that several classical biomarkers of pre‐eclampsia were expressed specifically in extravillous trophoblast and syncytiotrophoblast and only upregulated in EOPE, suggesting they should not be applied to all pre‐eclampsia patients in general. We further identified novel biomarkers for EOPE and LOPE from differentially expressed genes (DEGs) of placental and peripheral blood, respectively. The new biomarkers EBI3, IGF2, ORMDL3, GATA2 and KIR2DL4 were experimentally verified with patient blood samples.

Conclusion

Our data demonstrate distinct pathology of EOPE and LOPE, and uncover new biomarkers that can be applied in diagnosis for pre‐eclampsia.

The effect of blastomere loss during frozen embryo transfer on the transcriptome of offspring's umbilical cord blood

Blastomere loss is a common issue during frozen-thawed embryo transfer (FET). Our previous study showed that blastomere loss was associated with an increased risk of small-for-gestational-age (SGA) neonates. The present study assessed the impact of blastomere loss during cryopreservation by comparing the mRNA profiles of umbilical cord blood of FET offspring from the prospective cohort study. Umbilical cord blood samples were collected from 48 neonates, including 12 from the loss group, 11 from the intact group, and 25 from the matched spontaneous pregnancy group. RNA-seq technology was used to compare the global gene expression profiles of the lymphocytes. Then, we used TopHat software to map the reads and quantitative real-time PCR to validate some important differentially expressed genes (DEGs). We identified 92 DEGs between the loss group and the spontaneous pregnancy group, including IGF2 and H19. Ingenuity Pathway Analysis (IPA) showed that the DEGs were most affected in the blastomere loss group. Downstream analysis also predicted the activation of organismal death pathways. In conclusions, our pilot study sheds light on the mechanism underlying how human blastomere loss may affect offspring at the gene expression level. These conclusions are, however, only suggestive, as the current study is based on a very limited sample size and type or nature of biological samples. Additional studies with larger sample sizes and independent experiments with placental samples should be conducted to verify these findings.

High blood pressure in pregnancy, DNA methylation, and later blood pressure in African American women enrolled in the InterGEN Study

BACKGROUND

Few studies have examined the effects of high blood pressure (BP) in pregnancy, preeclampsia, or eclampsia on later BP, and the epigenetics of this phenomenon is similarly poorly understood, especially among African Americans. The purpose of this study was to examine the association between high BP in pregnancy, epigenomics, and later BP in African American women in the InterGEN Study (n = 250).

METHODS

In cross-sectional analyses, regression and linear mixed-effects models were employed to examine the effects of high BP in pregnancy on: (a) epigenetic associations (DNA methylation) and (b) BP 3-5 years after birth. The 850K Illumina EPIC BeadChip was used for evaluating epigenome-wide DNA methylation. High BP in pregnancy, preeclampsia, or eclampsia was self-reported by women, and BP was measured 3-5 years after birth, per JNC-7 guidelines. DNA methylation and clinical BP were the main outcomes.

RESULTS

Mean age of enrolled women was 31.2 years, 21.8% were smokers, 58% had some college or higher education, 46.6% reported an annual income <$15 000, and 13.6% reported high BP in pregnancy. After adjustment for obesity, smoking, and age, women with a history of high BP in pregnancy had significantly higher BP than those who did not report this complication (5.39 ± 2.4 mm Hg, P = .030). Epigenome-wide analysis revealed no significant sites after multiple testing correction.

CONCLUSIONS

We observed a small, but clinically significant, increase in BP in women who reported high BP in pregnancy 3-5 years after that pregnancy. Future studies with larger sample sizes should examine epigenetic contributions to this finding.

Differences in DNA methylation of insulin-like growth factor 2 and cadherin 13 in patients with preeclampsia

OBJECTIVES

In a previous mass spectrometry study of our research group, 25 proteins were found to be differentially expressed in cerebrospinal fluid of patients with preeclampsia compared to controls. The objective of the current study was to investigate DNA methylation of the genes encoding for the former mentioned proteins in an independent dataset.

STUDY DESIGN

In a nested case-control study of the Rotterdam Periconceptional Cohort, placental tissue, umbilical cord white blood cells and human umbilical vein endothelial cells (HUVEC) were obtained of 13 patients with early-onset preeclampsia, 16 patients with late-onset preeclampsia and 83 normotensive controls (27 patients with fetal growth restriction, 20 patients with spontaneous preterm birth and 36 uncomplicated pregnancies). DNA methylation of 783 CpGs in regions of 25 genes was measured.

MAIN OUTCOME MEASURES

DNA methylation of selected candidate genes in early- and late-onset preeclampsia compared to fetal growth restriction, spontaneous preterm birth and uncomplicated controls.

RESULTS

From the 783 CpGs of the 25 selected genes, 15 CpGs were differentially methylated between early-onset preeclampsia and spontaneous preterm birth (3.80 E-5 ≤ p ≤ 0.036). Four CpGs were differentially methylated between early-onset preeclampsia and fetal growth restriction (0.0002 ≤ p ≤ 0.037) and 13 CpGs were differentially methylated between early onset preeclampsia and uncomplicated controls (0.0001 ≤ p ≤ 0.04).

CONCLUSION

Differences in DNA methylation were found in placental tissue, umbilical cord white blood cells and HUVEC of patients with early onset preeclampsia compared to (un)complicated controls, but not in patients with late-onset preeclampsia. The genes showing the largest differential methylation encode insulin-like growth factor 2 binding protein and receptor and cadherin 13.

Association of Sperm Methylation at LINE-1, Four Candidate Genes, and Nicotine/Alcohol Exposure With the Risk of Infertility

In this study, we examined whether smoking and drinking affect sperm quality and the DNA methylation of the repetitive element LINE-1, MEST, P16, H19, and GNAS in sperm. Semen samples were obtained from 143 male residents in a minority-inhabited district of Guizhou province in southwest China. Quantitative DNA methylation analysis of the samples was performed using MassARRAY EpiTYPER assays. Sperm motility was significantly lower in both the nicotine-exposed (P = 0.0064) and the nicotine- and alcohol-exposed (P = 0.0008) groups. Follicle-stimulating hormone (FSH) levels were higher in the nicotine-exposed group (P = 0.0026). The repetitive element LINE-1 was hypermethylated in the three exposed groups, while P16 was hypomethylated in the alcohol and both the alcohol and nicotine exposure groups. Our results also show that alcohol and nicotine exposure altered sperm cell quality, which may be related to the methylation levels of MEST and GNAS. In addition, MEST, GNAS, and the repetitive element LINE1 methylation was significantly associated with the concentration of sperm as well as FSH and luteinizing hormone levels.

Hypertensive Disorders of Pregnancy and DNA Methylation in Newborns

Hypertensive disorders of pregnancy (HDP) are associated with low birth weight, shorter gestational age, and increased risk of maternal and offspring cardiovascular diseases later in life. The mechanisms involved are poorly understood, but epigenetic regulation of gene expression may play a part. We performed meta-analyses in the Pregnancy and Childhood Epigenetics Consortium to test the association between either maternal HDP (10 cohorts; n=5242 [cases=476]) or preeclampsia (3 cohorts; n=2219 [cases=135]) and epigenome-wide DNA methylation in cord blood using the Illumina HumanMethylation450 BeadChip. In models adjusted for confounders, and with Bonferroni correction, HDP and preeclampsia were associated with DNA methylation at 43 and 26 CpG sites, respectively. HDP was associated with higher methylation at 27 (63%) of the 43 sites, and across all 43 sites, the mean absolute difference in methylation was between 0.6% and 2.6%. Epigenome-wide associations of HDP with offspring DNA methylation were modestly consistent with the equivalent epigenome-wide associations of preeclampsia with offspring DNA methylation (R2=0.26). In longitudinal analyses conducted in 1 study (n=108 HDP cases; 550 controls), there were similar changes in DNA methylation in offspring of those with and without HDP up to adolescence. Pathway analysis suggested that genes located at/near HDP-associated sites may be involved in developmental, embryogenesis, or neurological pathways. HDP is associated with offspring DNA methylation with potential relevance to development.

The Role of Epigenetics in Placental Development and the Etiology of Preeclampsia

In this review, we comprehensively present the function of epigenetic regulations in normal placental development as well as in a prominent disease of placental origin, preeclampsia (PE). We describe current progress concerning the impact of DNA methylation, non-coding RNA (with a special emphasis on long non-coding RNA (lncRNA) and microRNA (miRNA)) and more marginally histone post-translational modifications, in the processes leading to normal and abnormal placental function. We also explore the potential use of epigenetic marks circulating in the maternal blood flow as putative biomarkers able to prognosticate the onset of PE, as well as classifying it according to its severity. The correlation between epigenetic marks and impacts on gene expression is systematically evaluated for the different epigenetic marks analyzed.

Gestational diabetes mellitus alters DNA methylation profiles in pancreas of the offspring mice

Gestational diabetes mellitus (GDM), which has an increasing global prevalence, contributes to the susceptibility to metabolic dysregulation and obesity in the offspring via epigenetic modifications. However, the underlying mechanism remains largely obscure. The current study established a GDM mice model to investigate the alternations in the metabolic phenotypes and genomic DNA methylation in the pancreas of the offspring. We found that in the GDM offspring, intrauterine hyperglycemia induced dyslipidemia, insulin resistance, and glucose intolerance. Meanwhile, altered DNA methylation patterns were exhibited in the pancreas and many differentially methylated regions (DMRs)-related genes were involved in glycolipids metabolism and related signaling pathways, including Agap2, Plcbr, Hnf1b, Gnas, Fbp2, Cdh13, Wnt2, Kcnq1, Lhcgr, Irx3, etc. Additionally, the overall hypermethylation of Agap2, verified by bisulfite sequencing PCR (BSP), was negatively correlated with its mRNA expression level. In conclusion, these findings suggest that the DNA methylation changes in the pancreatic genome of the GDM offspring may be associated with the glycolipid metabolism abnormalities, T2DM susceptibility, and obesity in the adult GDM offspring.

Prenatal exposure to preeclampsia is associated with accelerated height gain in early childhood

Background

Preeclampsia is associated with low birth weight, both because of increased risks of preterm and of small-for-gestational-age (SGA) births. Low birth weight is associated with accelerated childhood height gain and cardiovascular diseases later in life. The aim was to investigate if prenatal exposure to preeclampsia is associated with accelerated childhood height gain, also after adjustments for SGA-status and gestational age at birth.

Methods

In a cohort of children prenatally exposed to preeclampsia (n = 865) or unexposed (n = 22,898) we estimated height gain between birth and five years of age. The mean difference in height gain between exposed and unexposed children was calculated and adjustments were done with linear regression models.

Results

Children exposed to preeclampsia were on average born shorter than unexposed. Exposed children grew on average two cm more than unexposed from birth to five years of age. After adjustments for maternal characteristics including socioeconomic factors, height, body mass index (BMI) and diabetes, as well as for parents smoking habits, infant’s breastfeeding and childhood obesity, the difference was 1.6 cm (95% CI 1.3–1.9 cm). Further adjustment for SGA birth only slightly attenuated this estimate, but adjustment for gestational age at birth decreased the estimate to 0.5 cm (95% CI 0.1–0.7 cm).

Conclusion

Prenatal exposure to preeclampsia is associated with accelerated height gain in early childhood. The association seemed independent on SGA-status, but partly related to shorter gestational age at birth.

Epigenetics and Preeclampsia: Programming of Future Outcomes

Pregnancy is known to induce rapid, progressive, and substantial changes to the cardiovascular system, ultimately facilitating successful pregnancy outcomes. Women who develop hypertensive disorders during pregnancy are considered to have "failed" the cardiovascular stress test of pregnancy and likely represent a subpopulation with inadequate cardiovascular accommodation. Preeclampsia is a serious complication with a myriad of manifestations in both mother and offspring. This pregnancy syndrome is a polygenic disease and has now been linked to a greater incidence of cardiovascular disease. Moreover, offsprings born to preeclamptic mothers exhibit an elevated risk of cardiovascular disease, stroke, and mental disorders during adulthood. This suggests that preeclampsia not only exposes the mother and the fetus to complications during pregnancy but also programs chronic diseases during adulthood in the offspring. The etiology of preeclampsia remains unknown, with various theories being suggested to explain its origin. It is primarily thought to be associated with poor placentation and entails excessive maternal inflammation and endothelial dysfunction. It is well established now that the maternal immune system and the placenta are involved in a highly choreographed cross talk that underlies adequate spiral artery remodeling required for uteroplacental perfusion and free flow of nutrients to the fetus. Although it is not clear whether immunological alterations occur early during pregnancy, studies have proposed that dysregulated systemic and placental immunity contribute to impaired angiogenesis and the onset of preeclampsia. Recently emerged strong evidence suggests a potential link among epigenetics, microRNAs (miRNAs), and pregnancy complications. This chapter will focus on important aspects of epigenetics, immunological aspects, and cardiovascular and vascular remodeling of preeclampsia.

Maternal and paternal periconceptional nutrition as an indicator of offspring metabolic syndrome risk in later life through epigenetic imprinting: A systematic review

AIMS

This review examined whether maternal and paternal periconceptional nutrition effects an offspring's likelihood of developing chronic metabolic related conditions due to epigenetic imprinting.

METHODS

A literature search was conducted in multiple science databases and limited to studies published after 2012, in English language and peer reviewed. The data from selected articles were extracted and a qualitative approach was employed due to heterogeneity of results.

RESULTS

Newborns from obese fathers showed altered methylation overall and significant hypomethylation at the Insulin-like Growth Factor 2 (IGF2) gene. High maternal pre-pregnancy body mass index (BMI) was associated with altered offspring DNA methylation levels and gestational diabetes mellitus induced significantly increased methylation levels in offspring. Gestational weight gain was not associated with differentially methylated cord blood. Birth weight was higher in offspring exposed to famine in early gestation. Offspring born post maternal bariatric surgery showed a lower percentage of body fat and improved fasting insulin levels compared to siblings born pre-maternal bariatric surgery.

CONCLUSIONS

The available evidence suggests that poor maternal and paternal periconceptional nutrition can increase the risk of metabolic syndrome in offspring, through epigenetic imprinting. Potential parents should be advised that maintaining a healthy diet and BMI is likely to reduce the risk of metabolic syndrome in offspring.

Alteration in methylation level at differential methylated regions of MEST and DLK1 in fetus of preeclampsia

OBJECTIVES

Offspring born to preeclamptic women are at high risk for metabolic diseases in later life, but the mechanisms are not known. The purposes of the current investigation were to clarify the changes in DNA methylation at MEST and DLK1 DMRs in fetus of preeclampsia and to explore the possible mechanisms behind the high risk of adult diseases in the offspring of preeclampsia.

METHODS

Fetal lymphocytes were isolated from umbilical cord blood of 78 women with preeclampsia and 95 women with normal pregnancy. Genomic DNA was extracted and then DNA methylation levels of MEST and DLK1 DMRs were determined by MassARRAY quantitative methylation analysis.

RESULTS

The methylation levels were detected in 20 CpG sites of MEST DMR and 16 sites of DLK1 DMR. Methylation changes were significantly different at CPG1, 3, 4, 7.8, 15, 18.19, and 20 of MEST between preeclampsia and normal pregnancy (P = 0.014, 0.001, <0.001, <0.001, = 0.001,  = 0.005, and = 0.003, respectively). Significant differences were also observed at CPG 3 and 9 of DLK1 (P = 0.002 and 0.027, respectively). However, overall methylation at these DMRs were not affected.

CONCLUSION

We conclude methylation changes at some CpG sites of MEST and DLK DMRs in preeclamptic group. This may be among the mechanisms behind the high risk of adult diseases in the later life of offspring born to preeclamptic pregnancies.

ABBREVIATIONS

DMR: Differentially Methylated Region; MEST: Mesoderm Specific Transcript.

Associations between maternal prenatal stress, methylation changes in IGF1 and IGF2, and birth weight

Maternal stress has been linked to low birth weight in newborns. One potential pathway involves epigenetic changes at candidate genes that may mediate the effects of prenatal maternal stress on birth weight. This relationship has been documented in stress-related genes, such as NR3C1. There is less literature exploring the effect of stress on growth-related genes. IGF1 and IGF2 have been implicated in fetal growth and development, though via different mechanisms as IGF2 is under imprinting control. In this study, we tested for associations between prenatal stress, methylation of IGF1 and IGF2, and birth weight. A total of 24 mother-newborn dyads in the Democratic Republic of Congo were enrolled. Ethnographic interviews were conducted with mothers at delivery to gather culturally relevant war-related and chronic stressors. DNA methylation data were generated from maternal venous, cord blood and placental tissue samples. Multivariate regressions were used to test for associations between stress measures, DNA methylation and birth weight in each of the three tissue types. We found an association between IGF2 methylation in maternal blood and birth weight. Previous literature on the relationship between IGF2 methylation and birth weight has focused on methylation at known differentially methylated regions in cord blood or placental samples. Our findings indicate there may be links between the maternal epigenome and low birth weight that rely on mechanisms outside known imprinting pathways. It thus may be important to consider the effect of maternal exposures and epigenetic profiles on birth weight even in the setting of maternally imprinted genes such as IGF2.

Abnormal Placentation Associated with Infertility as a Marker of Overall Health

Infertility and fertility treatments utilized are associated with abnormal placentation leading to adverse pregnancy outcomes related to placentation, including preterm birth, low birth weight, placenta accrete, and placenta previa. This may be due to the underlying genetics predisposing to infertility or the epigenetic changes associated with the fertility treatments utilized, as specific disease states leading to infertility are at increased risk of adverse outcomes, including placental abruption, fetal loss, gestational diabetes mellitus, and outcomes related to placentation, as well as the treatments utilized including in vitro fertilization (IVF) and non-IVF fertility treatment. Placentation defects, leading to adverse maternal and fetal outcomes, which are more pronounced in the infertile population, occur due to changes in trophoblast invasion, vascular defects, changes in the environmental milieu, chronic inflammation, and oxidative stress. These similar processes are recognized as major contributors to lifelong risk of cardiovascular and metabolic disease for both the mother and her offspring. Thus, abnormal placentation, found to be more prevalent in the infertile population, may be the key to better understand how infertility affects overall and long-term health.

Fetal sex and maternal risk of pre-eclampsia/eclampsia: a systematic review and meta-analysis

BACKGROUND

A preponderance of male fetuses in pregnancies complicated by pre-eclampsia was described over 40 years ago. Since then, however, there has been conflicting evidence in the literature, with some studies supporting a male preponderance, some demonstrating no relationship with fetal sex, and others reporting increased risk in pregnancies bearing females.

OBJECTIVES

In this context, we sought to conduct a systematic review and meta-analysis to objectively evaluate the relationship between fetal sex and maternal risk of pre-eclampsia/eclampsia.

SEARCH STRATEGY

Studies from January 1950 to April 2015 were identified from PUBMED and EMBASE.

SELECTION CRITERIA

This systematic review and meta-analysis evaluated 22 articles reporting data on fetal sex and prevalence of pre-eclampsia/eclampsia.

DATA COLLECTION AND ANALYSIS

Data were extracted by two independent reviewers. Pooled estimates of the relative risk (RR) were calculated by random-effects model.

MAIN RESULTS

Male fetus was considered the exposure and prevalence of maternal pre-eclampsia/eclampsia was the outcome of interest. We identified 534 studies through electronic searches and three studies through manual searches. Twenty-two studies fulfilled the inclusion criteria, yielding data on 3 163 735 women. Pooled analyses of these studies showed no association between male fetal sex and maternal risk of pre-eclampsia/eclampsia (RR 1.01; 95% confidence interval, 95% CI 0.97-1.05); however, a subgroup analysis including only studies that evaluated the non-Asian population (n = 2 931 771 women) demonstrated that male fetal sex was associated with increased maternal risk of pre-eclampsia/eclampsia (RR 1.05; 95% CI 1.03-1.06; I2 = 10%; P = 0.33).

CONCLUSION

Male fetal sex is associated with maternal risk of pre-eclampsia/eclampsia in the non-Asian population.

TWEETABLE ABSTRACT

Fetal sex is associated with maternal risk of pre-eclampsia/eclampsia in the non-Asian population.

Effects of maternal folic acid supplementation on gene methylation and being small for gestational age

BACKGROUND

Being small for gestational age (SGA), a foetal growth abnormality, has a long-lasting impact on childhood health. Its aetiology and underlying mechanisms are not well understood. Underlying epigenetic changes of imprinted genes have emerged as a potential pathological pathway because they may be associated with growth, including SGA. As a common methyl donor, folic acid (FA) is essential for DNA methylation, synthesis and repair, and FA supplementation is widely recommended for women planning pregnancy. The present study aimed to investigate the inter-relationships among methylation levels of two imprinted genes [H19 differentially methylated regions (DMRs) and MEST DMRs], maternal FA supplementation and SGA.

METHODS

We conducted a case-control study. Umbilical cord blood was taken from 39 SGA infants and 49 controls whose birth weights are appropriate for gestational age (AGA). DNA methylation levels of H19 and MEST DMRs were determined by an analysis of mass array quantitative methylation.

RESULTS

Statistically significantly higher methylation levels were observed at sites 7.8, 9 and 17.18 of H19 (P = 0.030, 0.016 and 0.050, respectively) in the SGA infants compared to the AGA group. In addition, the association was stronger in male births where the mothers took FA around conception at six H19 sites (P = 0.004, 0.005, 0.048, 0.002, 0.021 and 0.005, respectively).

CONCLUSIONS

Methylation levels at H19 DMRs were higher in SGA infants compared to AGA controls. It appears that the association may be influenced by maternal peri-conception FA supplementation and also be sex-specific.

Maternal supplementation of omega-3 fatty acids and micronutrients reduces cardiometabolic variables in pregnancy induced hypertension rats

AIMS

Reports indicate that during pregnancy hypertension is known to have long term adverse effects both in the mother and offspring. However, the effect of maternal micronutrient supplementation on this association of in utero exposure and risk of non-communicable diseases in the later life remains unclear. The present study examines the effect of maternal micronutrient and omega-3 fatty acid supplementation either individual or in combination on cardiometabolic risk factors both in the mother and offspring using an animal model of hypertension.

MAIN METHODS

Pregnant Wistar rats were randomly assigned to the following groups; control, PIH (Pregnancy induced hypertention) Induced, PIH+vitamin B12, PIH+ folic acid, PIH+omega-3 fatty acids and PIH+combined smicronutrient supplementation (vitamin B12+folic acid + omega-3 fatty acids). The dams and their offspring were shifted to a control diet after delivery and the offspring continued on these diets till 3mo of age. Hypertension during pregnancy was induced using l-Nitroarginine methylester (50mg/kgbody weight/day).

KEY FINDINGS

Omega-3 fatty acid supplementation during pregnancy demonstrated lower levels (p<0.05) of plasma cholesterol while a combined supplementation of folic acid, vitamin B12 and omega 3 fatty acids demonstrated lower (p<0.05) triglyceride levels as compared to PIH induced dams. PIH induction increased (p<0.01) the triglyceride levels in the offspring at 3mo of age and maternal supplementation of either individual or combined micronutrients demonstrated lower (p<0.01) triglyceride levels.

SIGNIFICANCE

Our findings have implications for planning intervention studies in women with pregnancy induced hypertension.

5-Hydroxymethylcytosine-mediated alteration of transposon activity associated with the exposure to adverse in utero environments in human

Preeclampsia and gestational diabetes mellitus (GDM) are the most common clinical conditions in pregnancy that could result in adverse in utero environments. Fetal exposure to poor environments may raise the long-term risk of postnatal disorders, while epigenetic modifications could be involved. Recent research has implicated involvement of 5-hydroxymethylcytosine (5hmC), a DNA base derived from 5-methylcytosine, via oxidation by ten-eleven translocation (TET) enzymes, in DNA methylation-related plasticity. Here, we show that the TET2 expression and 5hmC abundance are significantly altered in the umbilical veins of GDM and preeclampsia. Genome-wide profiling of 5hmC revealed its specific reduction on intragenic regions from both GDM and preeclampsia compared to healthy controls. Gene Ontology analysis using loci bearing unique GDM- and preeclampsia-specific loss-of-5hmC indicated its impact on several critical biological pathways. Interestingly, the substantial alteration of 5hmC on several transposons and repetitive elements led to their differential expression. The alteration of TET expression, 5hmC levels and 5hmC-mediated transposon activity was further confirmed using established hypoxia cell culture model, which could be rescued by vitamin C, a known activator of TET proteins. Together, these results suggest that adverse pregnancy environments could influence 5hmC-mediated epigenetic profile and contribute to abnormal development of fetal vascular systems that may lead to postnatal diseases.

Preeclampsia As Modulator of Offspring Health

A balanced intrauterine homeostasis during pregnancy is crucial for optimal growth and development of the fetus. The intrauterine environment is extremely vulnerable to multisystem pregnancy disorders such as preeclampsia, which can be triggered by various pathophysiological factors, such as angiogenic imbalance, immune responses, and inflammation. The fetus adapts to these conditions by a mechanism known as developmental programming that can lead to increased risk of chronic noncommunicable diseases in later life. This is shown in a substantial number of epidemiological studies that associate preeclampsia with increased onset of cardiovascular and metabolic diseases in the later life of the offspring. Furthermore, animal models based predominantly on one of the pathophysiological mechanism of preeclampsia, for example, angiogenic imbalance, immune response, or inflammation, do address the susceptibility of the preeclamptic offspring to increased maternal blood pressure and disrupted metabolic homeostasis. Accordingly, we extensively reviewed the latest research on the role of preeclampsia on the offspring's metabolism and cardiovascular phenotype. We conclude that future research on the pathophysiological changes during preeclampsia and methods to intervene in the harsh intrauterine environment will be essential for effective therapies.

HIF3A DNA Methylation Is Associated with Childhood Obesity and ALT

Gene polymorphisms associated so far with body mass index (BMI) can explain only 1.18–1.45% of observed variation in BMI. Recent studies suggest that epigenetic modifications, especially DNA methylation, could contribute to explain part of the missing heritability, and two epigenetic genome-wide analysis studies (EWAS) have reported that Hypoxia Inducible Factor 3 Alpha Subunit (HIF3A) methylation was associated with BMI or BMI change. We therefore assessed whether the HIF3A methylation is associated with obesity and other obesity-related phenotypes in Chinese children. The subjects included 110 severe obese cases aged 7–17y and 110 normal-weight controls matched by age and gender for measurement of blood DNA methylation levels at the HIF3A gene locus using the Sequenom’s MassARRAY system. We observed significantly higher methylation levels in obese children than in controls at positions 46801642 and 46801699 in HIF3A gene (P<0.05), and found positive associations between methylation and alanine aminotransferase (ALT) levels adjusted by gender, age and BMI at the position 46801699 (r = 0.226, P = 0.007). These results suggest that HIF3A DNA methylation is associated with childhood obesity, and has a BMI-independent association with ALT. The results provide evidence for identifying epigenetic factors of elivated ALT and may be useful for risk assessment and personalized medicine of liver diseases such as non-alcoholic fatty liver disease (NAFLD).

A meta-analysis of neonatal health outcomes from oocyte donation

Donated oocytes are a treatment modality for female infertility which is also associated with increased risks of preeclampsia. Subsequently it is important to evaluate if there is concomitant increased risks for adverse neonatal events in donated oocyte neonates. A structured search of the literature using PubMed, EMBASE and Cochrane Reviews was performed to investigate the perinatal health outcomes of offspring conceived from donor oocytes compared with autologous oocytes. Meta-analysis was performed on comparable outcomes data. Twenty-eight studies were eligible and included in the review, and of these, 23 were included in a meta-analysis. Donor oocyte neonates are at increased risk of being born with low birth weight (<2500 g) [risk ratio (RR): 1.18, 95% confidence interval (CI): 1.14–1.22, P-value (P)<0.00001], very low birth weight (<1500 g) (RR: 1.24, CI: 1.15–1.35, P<0.00001), preterm (<37 weeks) (RR: 1.26, CI: 1.23–1.30, P<0.00001), of lower gestational age (mean difference −0.3 weeks, CI: −0.35 weeks to −0.25 weeks, P<0.00001), and preterm with low birth weight (RR: 1.24, CI: 1.19–1.29, P<0.00001), when compared with autologous oocyte neonates. Conversely, low birth weight outcomes were improved in term donor oocyte neonates (RR: 0.86, CI: 0.8–0.93, P=0.0003). These negative outcomes remained significant when controlling for multiple deliveries. The donor oocyte risk rates are higher than those found in general ART outcomes, are important considerations for the counselling of infertile patients and may also influence the long term health of the offspring.

Epigenetic and developmental influences on the risk of obesity, diabetes, and metabolic syndrome

Metabolic syndrome is a growing cause of morbidity and mortality worldwide. Metabolic syndrome is characterized by the presence of a variety of metabolic disturbances including obesity, hyperlipidemia, hypertension, and elevated fasting blood sugar. Although the risk for metabolic syndrome has largely been attributed to adult lifestyle factors such as poor nutrition, lack of exercise, and smoking, there is now strong evidence suggesting that predisposition to the development of metabolic syndrome begins in utero. First posited by Hales and Barker in 1992, the "thrifty phenotype" hypothesis proposes that susceptibility to adult chronic diseases can occur in response to exposures in the prenatal and perinatal periods. This hypothesis has been continually supported by epidemiologic studies and studies involving animal models. In this review, we describe the structural, metabolic and epigenetic changes that occur in response to adverse intrauterine environments including prenatal and postnatal diet, maternal obesity, and pregnancy complications. Given the increasing prevalence of metabolic syndrome in both the developed and developing worlds, a greater understanding and appreciation for the role of the intrauterine environment in adult chronic disease etiology is imperative.

Increased methylation at differentially methylated region of GNAS in infants born to gestational diabetes

BACKGROUND

Offspring of pregnancy complicated with gestational diabetes (GDM) are at high risk for metabolic diseases. The mechanisms behind the association of intrauterine exposure to GDM and high risk of health problems in later life remain largely unknown. The aim of this study was to clarify the alteration in methylation levels at differentially methylated regions (DMRs) of GNAS and IGF2 in fetuses of GDM women and to explore the possible mechanisms linking maternal GDM with high risk of metabolic diseases in later life of GDM offspring.

METHODS

Lymphocytes were isolated from umbilical cord blood of infants born to 87 women with GDM and 81 women with normal pregnancy. Genomic DNA was extracted and DNA methylation levels of GNAS and IGF2 DMRs were determined by Massarray quantitative methylation analysis.

RESULTS

The methylation levels were detected in 7 CpG sites of GNAS DMRs and 6 sites of IGF2 DMRs. Methylation levels were significantly higher at sites 4, 5 and 7 of GNAS DMR in GDM compared to normal pregnancy (P = 0.007, 0.008 and 0.008, respectively). The methylation level at site 4 of GNAS was significantly correlated with the presence of GDM (P = 0.003), the methylation levels at site 5 and 7 were significantly correlated with the presence of GDM (P = 0.002 for both) and gestational age (P = 0.027 for both). There was no significant difference in any sites of IGF2 DMR (P > 0.05 for all).

CONCLUSIONS

We concluded maternal GDM-induced hypermethylation at GNAS DMR and this condition may be among the mechanisms associating maternal GDM with increased risk of metabolic diseases in later life of offspring.

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.