The levels of hypoxia-regulated microRNAs in plasma of pregnant women with fetal growth restriction

Seminar: Extracellular Vesicles as Mediators of Environmental Stress in Human Disease

BACKGROUND

Extracellular vesicles (EVs), membrane-bound particles containing a variety of RNA types, DNA, proteins, and other macromolecules, are now appreciated as an important means of communication between cells and tissues, both in normal cellular physiology and as a potential indicator of cellular stress, environmental exposures, and early disease pathogenesis. Extracellular signaling through EVs is a growing field of research for understanding fundamental mechanisms of health and disease and for the potential for biomarker discovery and therapy development. EVs are also known to play important roles in mediating the effects of exposure to environmental stress.

OBJECTIVES

This seminar addresses the application of new tools and approaches for EV research, developed in part through the National Institutes of Health (NIH) Extracellular RNA Communication Program, and reflects presentations and discussions from a workshop held 27-28 September 2021 by the National Institute of Environmental Health Sciences (NIEHS) and the National Center for Advancing Translational Sciences (NCATS) on "Extracellular Vesicles, Exosomes, and Cell-Cell Signaling in Response to Environmental Stress." The panel of experts discussed current research on EVs and environmental exposures, highlighted recent advances in EV isolation and characterization, and considered research gaps and opportunities toward identifying and characterizing the roles for EVs in environmentally related diseases, as well as the current challenges and opportunities in this field.

DISCUSSION

The authors discuss the application of new experimental models, particularly organ-on-chip (OOC) systems and in vitro approaches and how these have the potential to extend findings in population-based studies of EVs in exposure-related diseases. Given the complex challenges of identifying cell-specific EVs related to environmental exposures, as well as the general heterogeneity and variability in EVs in blood and other accessible biological samples, there is a critical need for rigorous reporting of experimental methods and validation studies. The authors note that these efforts, combined with cross-disciplinary approaches, would ensure that future research efforts in environmental health studies on EV biomarkers are rigorous and reproducible. https://doi.org/10.1289/EHP12980.

Rational Design of Nanomedicine for Placental Disorders: Birthing a New Era in Women's Reproductive Health

The placenta is a transient organ that forms during pregnancy and acts as a biological barrier, mediating exchange between maternal and fetal circulation. Placental disorders, such as preeclampsia, fetal growth restriction, placenta accreta spectrum, and gestational trophoblastic disease, originate in dysfunctional placental development during pregnancy and can lead to severe complications for both the mother and fetus. Unfortunately, treatment options for these disorders are severely lacking. Challenges in designing therapeutics for use during pregnancy involve selectively delivering payloads to the placenta while protecting the fetus from potential toxic side effects. Nanomedicine holds great promise in overcoming these barriers; the versatile and modular nature of nanocarriers, including prolonged circulation times, intracellular delivery, and organ-specific targeting, can control how therapeutics interact with the placenta. In this review, nanomedicine strategies are discussed to treat and diagnose placental disorders with an emphasis on understanding the unique pathophysiology behind each of these diseases. Finally, prior study of the pathophysiologic mechanisms underlying these placental disorders has revealed novel disease targets. These targets are highlighted here to motivate the rational design of precision nanocarriers to improve therapeutic options for placental disorders.

Placenta-specific protein 1 (PLAC1) expression is significantly down-regulated in preeclampsia via a hypoxia-mediated mechanism

OBJECTIVE

Examine a mechanism of PLAC1 regulation and its potential role in preeclampsia (PE).

MATERIALS AND METHODS

Placental tissue samples and detailed clinical information were obtained through the University of Iowa Maternal Fetal Tissue Bank (IRB# 200910784) from gestational and maternal age-matched control (n = 17) and PE affected pregnancies (n = 12). PLAC1 and PLAC1 promoter-specific expression was measured using quantitative polymerase chain reaction (qPCR) and differences were assessed via the standard ΔΔCt method. In addition, the role of hypoxia in PLAC1 transcription was investigated through the exposure of HTR8/SVneo human trophoblast cells to the hypoxia mimic dimethyloxaloylglycine (DMOG).

RESULTS

PLAC1 expression is seen to be 8.9-fold lower in human placentas affected by preeclampsia in comparison with controls (p < .05). Further, this decrease is paralleled by a significantly lower expression of the P2 or proximal PLAC1 promoter (p < .05). Expression of mediator complex subunit 1 (MED1), a known hypoxia-sensitive transcription coactivator and PLAC1 effector, is significantly correlated with PLAC 1 expression (r2 = 0.607, p < .001). These data suggest that PLAC1 expression is significantly down-regulated in preeclampsia at least in part via a MED1 hypoxia-mediated mechanism.

CONCLUSIONS

We confirm that PLAC1 transcription is suppressed in the placentae of women affected by preeclampsia. We further demonstrate that this suppression is driven through the P2 or proximal PLAC1 promoter. This demonstration led to the identification of the MED1-TRAP cofactor complex as the hypoxia-sensitive driver.

The Role of Cluster C19MC in Pre-Eclampsia Development

Pre-eclampsia is a placenta-related complication occurring in 2-10% of all pregnancies. miRNAs are a group of non-coding RNAs regulating gene expression. There is evidence that C19MC miRNAs are involved in the development of the placenta. Deregulation of chromosome 19 microRNA cluster (C19MC) miRNAs expression leads to impaired cell differentiation, abnormal trophoblast invasion and pathological angiogenesis, which can lead to the development of pre-eclampsia. Information was obtained through a review of articles available in PubMed Medline. Articles on the role of the C19MC miRNA in the development of pre-eclampsia published in 2009-2022 were analyzed. This review article summarizes the current data on the role of the C19MC miRNA in the development of pre-eclampsia. They indicate a significant increase in the expression of most C19MC miRNAs in placental tissue and a high level of circulating fractions in serum and plasma, both in the first and/or third trimester in women with PE. Only for miR-525-5p, low levels of plasma expression were noted in the first trimester, and in the placenta in the third trimester. The search for molecular factors indicating the development of pre-eclampsia before the onset of clinical symptoms seems to be a promising diagnostic route. Identifying women at risk of developing pre-eclampsia at the pre-symptomatic stage would avoid serious complications in both mothers and fetuses. We believe that miRNAs belonging to cluster C19MC could be promising biomarkers of pre-eclampsia development.

microRNA signatures associated with fetal growth restriction: a systematic review

Placental-origin microRNA (miRNA) profiles can be useful toward early diagnosis and management of fetal growth restriction (FGR) and associated complications. We conducted a systematic review to identify case-control studies that have examined miRNA signatures associated with human FGR. We systematically searched PubMed and ScienceDirect databases for relevant articles and manually searched reference lists of the relevant articles till May 18th, 2021. Of the 2133 studies identified, 21 were included. FGR-associated upregulation of miR-210 and miR-424 and downregulation of a placenta-specific miRNA cluster miRNA located on C19MC (miR-518b, miR-519d) and miR-221-3p was reported by >1 included studies. Analysis of the target genes of these miRNA as well as pathway analysis pointed to the involvement of angiogenesis and growth signaling pathways, such as the phosphatidylinositol 3-kinase- protein kinase B (PI3K-Akt) pathway. Only 3 out of the 21 included studies reported FGR-associated miRNAs in matched placental and maternal blood samples. We conclude that FGR-associated placental miRNAs could be utilized to inform clinical practice towards early diagnosis of FGR, provided enough evidence from studies on matched placental and maternal blood samples become available.Prospective Register of Systematic Reviews (PROSPERO) registration number: CRD42019136762.

Influence of maternal obesity on the multi-omics profiles of the maternal body, gestational tissue, and offspring

Epidemiological studies show that obesity during pregnancy affects more than half of the pregnancies in the developed countries and is associated with obstetric problems and poor outcomes. Obesity tends to increase the incidence of complications. Furthermore, the resulting offspring are also adversely affected. However, the molecular mechanisms of obesity leading to poor pregnancy outcomes remain unclear. Omics methods are used for genetic diagnosis and marker discovery. The aim of this review was to summarize the maternal and fetal pathophysiological alterations induced by gestational obesity,identified using multi-omics detection techniques, and to generalize the biological functions and potential mechanisms of the differentially expressed molecules.

Identification and Characterization of Extrachromosomal Circular DNA in Human Placentas With Fetal Growth Restriction

Many studies have confirmed that extrachromosomal circular DNAs (eccDNAs/ecDNAs) exist in tumor and normal cells independently of the chromosome and are essential for oncogene plasticity and drug resistance. Studies have confirmed that there are many eccDNAs/ecDNAs in maternal plasma derived from the fetus. Fetal growth restriction (FGR) is a pregnancy-related disease associated with high newborn morbidity and mortality. However, the characteristics and nature of eccDNAs/ecDNAs in FGR are poorly understood. This study aims to deconstruct the properties and potential functions of eccDNAs/ecDNAs in FGR. We performed circle-seq to identify the expression profile of eccDNAs/ecDNAs, analyzed by bioinformatics, and verified by real-time Polymerase Chain Reaction (PCR) combined with southern blot in FGR compared with the normal groups. A total of 45,131 eccDNAs/ecDNAs (including 2,118 unique ones) were identified, which had significantly higher abundance in FRG group than in normal group, and was bimodal in length, peaking at ~146bp and ~340bp, respectively. Gestational age may be one independent factor affecting the production of eccDNAs/ecDNAs, most of which come from genomic regions with high gene density, with a 4~12bp repeat around the junction, and their origin had a certain genetic preference. In addition, some of the host-genes overlapped with non-coding RNAs (ncRNAs) partially or even completely. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that host-genes on the differentially expressed eccDNAs/ecDNAs (DEEECs/DEECs) were mainly enriched in immune-related functions and pathways. The presence of some ecDNAs were verified, and whose variability were consistent with the circle-seq results. We identified and characterized eccDNAs/ecDNAs in placentas with FGR, and elucidated the formation mechanisms and the networks with ncRNAs, which provide a new vision for the screening of new biomarkers and therapeutic targets for FGR.

Sexually dimorphic patterns in maternal circulating microRNAs in pregnancies complicated by fetal growth restriction

Background

Current methods fail to accurately predict women at greatest risk of developing fetal growth restriction (FGR) or related adverse outcomes, including stillbirth. Sexual dimorphism in these adverse pregnancy outcomes is well documented as are sex-specific differences in gene and protein expression in the placenta. Circulating maternal serum microRNAs (miRNAs) offer potential as biomarkers that may also be informative of underlying pathology. We hypothesised that FGR would be associated with an altered miRNA profile and would differ depending on fetal sex.

Methods

miRNA expression profiles were assessed in maternal serum (> 36 weeks’ gestation) from women delivering a severely FGR infant (defined as an individualised birthweight centile (IBC) < 3rd) and matched control participants (AGA; IBC = 20–80th), using miRNA arrays. qPCR was performed using specific miRNA primers in an expanded cohort of patients with IBC < 5th (n = 15 males, n = 16 females/group). Maternal serum human placental lactogen (hPL) was used as a proxy to determine if serum miRNAs were related to placental dysfunction. In silico analyses were performed to predict the potential functions of altered miRNAs.

Results

Initial analyses revealed 11 miRNAs were altered in maternal serum from FGR pregnancies. In silico analyses revealed all 11 altered miRNAs were located in a network of genes that regulate placental function. Subsequent analysis demonstrated four miRNAs showed sexually dimorphic patterns. miR-28-5p was reduced in FGR pregnancies (p < 0.01) only when there was a female offspring and miR-301a-3p was only reduced in FGR pregnancies with a male fetus (p < 0.05). miR-454-3p was decreased in FGR pregnancies (p < 0.05) regardless of fetal sex but was only positively correlated to hPL when the fetus was female. Conversely, miR-29c-3p was correlated to maternal hPL only when the fetus was male. Target genes for sexually dimorphic miRNAs reveal potential functional roles in the placenta including angiogenesis, placental growth, nutrient transport and apoptosis.

Conclusions

These studies have identified sexually dimorphic patterns for miRNAs in maternal serum in FGR. These miRNAs may have potential as non-invasive biomarkers for FGR and associated placental dysfunction. Further studies to determine if these miRNAs have potential functional roles in the placenta may provide greater understanding of the pathogenesis of placental dysfunction and the differing susceptibility of male and female fetuses to adverse in utero conditions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13293-021-00405-z.

Detection and treatment of pregnancies at high risk of fetal growth restriction (FGR) and stillbirth remains a major obstetric challenge; circulating maternal serum microRNAs (miRNAs) offer potential as novel biomarkers.

Unbiased analysis of serum miRNAs in women in late pregnancy identified a specific profile of circulating miRNAs in women with a growth-restricted infant.

Some altered miRNAs (miR-28-5p, miR-301a-3p) showed sexually dimorphic expression in FGR pregnancies and others a fetal-sex dependent association to a hormonal marker of placental dysfunction (miR-454-3p, miR-29c-3p).

miR-301a-3p and miR-28-5p could potentially be used to predict FGR specifically in pregnancies with a male or female baby, respectively, however larger cohort studies are required.

Further investigations of these miRNAs and their relationship to placental dysfunction will lead to a better understanding of the pathophysiology of FGR and why there is differing susceptibility of male and female fetuses to FGR and stillbirth.

Large-scale transcriptome-wide profiling of microRNAs in human placenta and maternal plasma at early to mid gestation

MicroRNAs (miRNAs) are increasingly seen as important regulators of placental development and opportunistic biomarker targets. Given the difficulty in obtaining samples from early gestation and subsequent paucity of the same, investigation of the role of miRNAs in early gestation human placenta has been limited. To address this, we generated miRNA profiles using 96 placentas from presumed normal pregnancies, across early gestation, in combination with matched profiles from maternal plasma. Placenta samples range from 6 to 23 weeks' gestation, a time period that includes placenta from the early, relatively low but physiological (6-10 weeks' gestation) oxygen environment, and later, physiologically normal oxygen environment (11-23 weeks' gestation).We identified 637 miRNAs with expression in 86 samples (after removing poor quality samples), showing a clear gestational age gradient from 6 to 23 weeks' gestation. We identified 374 differentially expressed (DE) miRNAs between placentas from 6-10 weeks' versus 11-23 weeks' gestation. We see a clear gestational age group bias in miRNA clusters C19MC, C14MC, miR-17 ~ 92 and paralogs, regions that also include many DE miRNAs. Proportional change in expression of placenta-specific miRNA clusters was reflected in maternal plasma.The presumed introduction of oxygenated maternal blood into the placenta (between ~10 and 12 weeks' gestation) changes the miRNA profile of the chorionic villus, particularly in placenta-specific miRNA clusters. Data presented here comprise a clinically important reference set for studying early placenta development and may underpin the generation of minimally invasive methods for monitoring placental health.

Circulating Nucleic Acids in Maternal Plasma and Serum in Pregnancy Complications: Are They Really Useful in Clinical Practice? A Systematic Review

OBJECTIVE

A systematic review was carried out to summarize the available evidence to assess whether circulating nucleic acids in maternal plasma and serum (CNAPS) have the potential to serve as extra and independent markers for the prediction and/or progression monitoring of the most common and severe complications of pregnancy, including preeclampsia, intrauterine growth restriction, preterm delivery, morbidly adherent placenta, gestational diabetes, antiphospholipid syndrome, threatened abortion, intrahepatic cholestasis of pregnancy, and hyperemesis gravidarum.

METHOD

A comprehensive literature search of the MEDLINE (PubMed), EMBASE, and ISI Web of Knowledge databases was conducted to identify relevant studies that included amounts of CNAPS in the abovementioned pregnancy complications.

RESULTS

Eighty-three studies met the eligibility criteria. The vast majority of studies were conducted on the quantity of total circulating cell free DNA (cfDNA) and cell free fetal DNA (cffDNA), and some were conducted on messenger RNA (mRNA) species. A few studies have instead evaluated the cell free DNA fetal fraction (cfDNAff), but only in a limited number of pregnancy complications. Despite the growing interest and the abundance of the papers available, little information is available for other new CNAPS, including microRNA (miRNA), long noncoding RNA (lncRNA), mitochondrial DNA (mtDNA), and circular RNA.

CONCLUSION

Due to the heterogeneity of the populations enrolled, the scarcity of the studies that adjusted the CNAPS values for possible confounding factors, and the difficulty in interpreting the published data, no conclusion regarding the statistical robustness and clinical relevance of the data can be made at present. If assayed at the third trimester, the CNAPS have, however, shown better performance, and could be used in populations already at risk of developing complications as suggested by the presence of other clinical features. Other CNAPS, including miRNA, are under investigation, especially for the screening of gestational diabetes mellitus, but no data about their clinical utility are available. Circulating DNA (cfDNA, cffDNA, and cfDNAff) and mRNA have not been properly evaluated yet, especially in patients asymptomatic early in pregnancy but who developed complications later, perhaps because of the high cost of these techniques and the availability of other predictors of pregnancy complications (biochemical, biophysical, and ultrasound markers). Therefore, from the analysis of the data, the positive predictive value is not available. As regards the new CNAPS, including miRNA, there are still no sufficient data to understand if they can be promising markers for pregnancy complications monitoring and screening, since CNAPS are statistically weak and expensive. It is reasonable to currently conclude that the use of the CNAPS in clinical practice is not recommended.

Extracellular vesicle microRNA in early versus late pregnancy with birth outcomes in the MADRES study

Circulating miRNA may contribute to the development of adverse birth outcomes. However, few studies have investigated extracellular vesicle (EV) miRNA, which play important roles in intercellular communication, or compared miRNA at multiple time points in pregnancy. In the current study, 800 miRNA were profiled for EVs from maternal plasma collected in early (median: 12.5 weeks) and late (median: 31.8 weeks) pregnancy from 156 participants in the MADRES Study, a health disparity pregnancy cohort. Associations between miRNA and birth weight, birth weight for gestational age (GA), and GA at birth were examined using covariate-adjusted robust linear regression. Differences by infant sex and maternal BMI were also investigated. Late pregnancy measures of 13 miRNA were associated with GA at birth (P_FDR<0.050). Negative associations were observed for eight miRNA (miR-4454+ miR-7975, miR-4516, let-7b-5p, miR-126-3p, miR-29b-3p, miR-15a-5p, miR-15b-5p, miR-19b-3p) and positive associations for five miRNA (miR-212-3p, miR-584-5p, miR-608, miR-210-3p, miR-188-5p). Predicted target genes were enriched (P_FDR<0.050) in pathways involved in organogenesis and placental development. An additional miRNA (miR-107), measured in late pregnancy, was positively associated with GA at birth in infants born to obese women (P_FDR for BMI interaction = 0.011). In primary analyses, the associations between early pregnancy miRNA and birth outcomes were not statistically significant (P_FDR≥0.05). However, sex-specific associations were observed for early pregnancy measures of 37 miRNA and GA at birth (P_FDR for interactions<0.050). None of the miRNA were associated with fetal growth measures (P_FDR≥0.050). Our findings suggest that EV miRNA in both early and late pregnancy may influence gestational duration.

MicroRNA-210 Mediates Hypoxia-Induced Repression of Spontaneous Transient Outward Currents in Sheep Uterine Arteries During Gestation

[Figure: see text].

MicroRNA-mRNA Networks in Pregnancy Complications: A Comprehensive Downstream Analysis of Potential Biomarkers

Pregnancy complications are a major cause of fetal and maternal morbidity and mortality in humans. The majority of pregnancy complications initiate due to abnormal placental development and function. During the last decade, the role of microRNAs (miRNAs) in regulating placental and fetal development has become evident. Dysregulation of miRNAs in the placenta not only affects placental development and function, but these miRNAs can also be exported to both maternal and fetal compartments and affect maternal physiology and fetal growth and development. Due to their differential expression in the placenta and maternal circulation during pregnancy complications, miRNAs can be used as diagnostic biomarkers. However, the differential expression of a miRNA in the placenta may not always be reflected in maternal circulation, which makes it difficult to find a reliable biomarker for placental dysfunction. In this review, we provide an overview of differentially expressed miRNAs in the placenta and/or maternal circulation during preeclampsia (PE) and intrauterine growth restriction (IUGR), which can potentially serve as biomarkers for prediction or diagnosis of pregnancy complications. Using different bioinformatics tools, we also identified potential target genes of miRNAs associated with PE and IUGR, and the role of miRNA-mRNA networks in the regulation of important signaling pathways and biological processes.

MicroRNA-Mediated Gene Regulatory Mechanisms in Mammalian Female Reproductive Health

Mammalian reproductive health affects the entire reproductive cycle starting with the ovarian function through implantation and fetal growth. Various environmental and physiological factors contribute to disturbed reproductive health status leading to infertility problems in mammalian species. In the last couple of decades a significant number of studies have been conducted to investigate the transcriptome of reproductive tissues and organs in relation to the various reproductive health issues including endometritis, polycystic ovarian syndrome (PCOS), intrauterine growth restriction (IUGR), preeclampsia, and various age-associated reproductive disorders. Among others, the post-transcriptional regulation of genes by small noncoding miRNAs contributes to the observed transcriptome dysregulation associated with reproductive pathophysiological conditions. MicroRNAs as a class of non-coding RNAs are also known to be involved in various pathophysiological conditions either in cellular cytoplasm or they can be released to the extracellular fluid via membrane-bounded extracellular vesicles and proteins. The present review summarizes the cellular and extracellular miRNAs and their association with the etiology of major reproductive pathologies including PCOS, endometritis, IUGR and age-associated disorders in various mammalian species.

miR-16-5p, miR-103-3p, and miR-27b-3p as Early Peripheral Biomarkers of Fetal Growth Restriction

Current tests available to diagnose fetal hypoxia in-utero lack sensitivity thus failing to identify many fetuses at risk. Emerging evidence suggests that microRNAs derived from the placenta circulate in the maternal blood during pregnancy and may be used as non-invasive biomarkers for pregnancy complications. With the intent to identify putative markers of fetal growth restriction (FGR) and new therapeutic druggable targets, we examined, in maternal blood samples, the expression of a group of microRNAs, known to be regulated by hypoxia. The expression of microRNAs was evaluated in maternal plasma samples collected from (1) women carrying a preterm FGR fetus (FGR group) or (2) women with an appropriately grown fetus matched at the same gestational age (Control group). To discriminate between early- and late-onset FGR, the study population was divided into two subgroups according to the gestational age at delivery. Four microRNAs were identified as possible candidates for the diagnosis of FGR: miR-16-5p, miR-103-3p, miR-107-3p, and miR-27b-3p. All four selected miRNAs, measured by RT-PCR, resulted upregulated in FGR blood samples before the 32nd week of gestation. By contrast, miRNA103-3p and miRNA107-3p, analyzed between the 32nd and 37th week of gestation, showed lower expression in the FGR group compared to aged matched controls. Our results showed that measurement of miRNAs in maternal blood may form the basis for a future diagnostic test to determine the degree of fetal hypoxia in FGR, thus allowing the start of appropriate therapeutic interventions to alleviate the burden of this disease.

The expression of miRNA encoded by C19MC and miR-371-3 strongly varies among individual placentas but does not differ between spontaneous and induced abortions

miRNAs of the largest human miRNA gene cluster at all, i.e., C19MC, are almost exclusively expressed in the placenta. Nevertheless, only little is known about the interindividual variation of their expression and even about possible influence of gestational age, conflicting data is reported as well as for miRNAs of the much smaller miR-371-3 cluster. Our present study aims at the analyses of the expression of miRNAs from both clusters at different times of pregnancy, possible differences between placenta samples obtained from spontaneous or induced abortions in the first trimester, and the possible variation of miRNA expression at different sites within same placentas. miR-371a-3p, miR-372-3p, miR-373-3p, miR-517a-3p, and miR-520c-3p were quantified in 85 samples and miR-371a-3p was quantified in maternal serum samples taken immediately before delivery. While for miRNA-517a-3p and miR-520c-3p the expression increased with increasing gestational age, the present study revealed strong interindividual differences in the expression of miR-371-3 in full-term placental tissue as well as for miRNAs of the C19MC cluster, where the levels differed to a much lesser extent than for the former microRNAs. Also, strong interindividual differences were noted between the serum samples but differences related to the site of the placenta where the sample has been taken from were excluded. For neither of the data from placental tissue, the study revealed differences between the spontaneous and induced abortion group. Thus, the differences do not in general seem to be related to first trimester abortion. It remains to be elucidated whether or not they affect other prenatal processes.

Transgenic expression of human C19MC miRNAs impacts placental morphogenesis

INTRODUCTION

The chromosome 19 miRNA cluster (C19MC) encodes a large family of microRNAs (miRNAs) that are abundantly expressed in the placenta of higher primates and also in certain cancers. In the placenta, miRNAs from this cluster account for nearly 40% of all miRNAs present in trophoblasts. However, the function of these miRNAs in the placenta remains poorly understood. Recent observations reveal a role for these miRNAs in cell migration, and suggest that they are involved in the development and function of the human placenta. Here, we examine the placenta in transgenic mice expressing the human C19MC miRNAs.

METHODS

We produced transgenic mice using pronuclear microinjection of a bacterial artificial chromosome plasmid carrying the entire human C19MC locus and derived a homozygous line using crossbreeding. We performed morphological characterization and profiled gene expression changes in the placentas of the transgenic mice.

RESULTS

C19MC transgenic mice delivered on time with no gross malformations. The placentas of transgenic mice expressed C19MC miRNAs and were larger than wild type placentas. Histologically, we found that the transgenic placenta exhibited projections of spongiotrophoblasts that penetrated deep into the labyrinth. Gene expression analysis revealed alterations in the expression of several genes involved in cell migration, with evidence of enhanced cell proliferation.

DISCUSSION

Mice that were humanized for transgenically overexpressed C19MC miRNAs exhibit enlarged placentas with aberrant delineation of cell layers. The observed phenotype and the related gene expression changes suggest disrupted migration of placental cell subpopulations.

Placental microRNAs: Responders to environmental chemicals and mediators of pathophysiology of the human placenta

MicroRNAs (miRNAs) are epigenetic modifiers that play an important role in the regulation of the expression of genes across the genome. miRNAs are expressed in the placenta as well as other organs, and are involved in several biological processes including the regulation of trophoblast differentiation, migration, invasion, proliferation, apoptosis, angiogenesis and cellular metabolism. Related to their role in disease process, miRNAs have been shown to be differentially expressed between normal placentas and placentas obtained from women with pregnancy/health complications such as preeclampsia, gestational diabetes mellitus, and obesity. This dysregulation indicates that miRNAs in the placenta likely play important roles in the pathogenesis of diseases during pregnancy. Furthermore, miRNAs in the placenta are susceptible to altered expression in relation to exposure to environmental toxicants. With relevance to the placenta, the dysregulation of miRNAs in both placenta and blood has been associated with maternal exposures to several toxicants. In this review, we provide a summary of miRNAs that have been assessed in the context of human pregnancy-related diseases and in relation to exposure to environmental toxicants in the placenta. Where data are available, miRNAs are discussed in their context as biomarkers of exposure and/or disease, with comparisons made across-tissue types, and conservation across studies detailed.

Placental miRNAs in feto-maternal communication mediated by extracellular vesicles

A complex network composed of at least 1900 microRNA (miRNA) species orchestrates the development and function of the human placenta. These molecules regulate genes and pathways operating major functional processes in trophoblast cells such as proliferation, invasion, differentiation, and metabolism. Nevertheless, the cellular localization and role of most placental miRNAs remain to be determined. The existence of eutherian- (C14MC) and primate-specific miRNA clusters (C19MC), together with human placenta-specific miRNAs, indicate the relevance of these molecules in evolution and diversification of the placenta, including the acquisition of its unique features in humans. They may be related also to diseases that are exclusively present in primates, such as preeclampsia. Changes in the miRNA expression profile have been reported in several placental pathologies. Which miRNAs are involved in the pathomechanism of these diseases or act to maintain placental homeostasis is uncertain. Placenta-derived miRNAs are packed into extracellular vesicles (EVs) and distributed through the maternal circulation to distant organs, where they contribute to adaptations required during pregnancy. Similarly, the placenta also receives molecular information from other tissues to adapt fetoplacental metabolic demands to the maternal energetic supply. These processes can be impaired in pathologic conditions. Therefore, the collection of circulating placental miRNAs constitutes potentially a minimally-invasive approach to assess the fetoplacental status and to diagnose pregnancy diseases. Future therapies may include manipulation of miRNA levels for prevention and treatment of placental complications to protect maternal health and fetal development.

MicroRNA-148b-3p and MicroRNA-25-3p Are Overexpressed in Fetuses with Late-Onset Fetal Growth Restriction

OBJECTIVE

It was the aim of this study to describe a micro-RNA (miRNA) profile characteristic of late-onset fetal growth restriction (FGR) and to investigate the pathways involved in their biochemical action.

METHODS

In this prospective study, 25 fetuses (16 normal and 9 with FGR [estimated fetal weight <10th centile plus cerebroplacental ratio <0.6765 multiples of the median]) were evaluated with Doppler ultrasound after 36 weeks. Afterwards, for every fetus, plasma from umbilical vein blood was collected at birth, miRNA was extracted, and full miRNA sequencing was performed. Subsequently, comparisons were done in order to obtain those miRNAs that were differentially expressed.

RESULTS

The FGR fetuses expressed upregulation of two miRNAs: miR-25-3p and, especially, miR-148b-3p, a miRNA directly involved in Schwann cell migration, neuronal plasticity, and energy metabolism (p = 0.0072, p = 0.0013).

CONCLUSIONS

FGR fetuses express a different miRNA profile, which includes overexpression of miR-25-3p and miR-148b-3p. This information might improve our understanding of the pathophysiological processes involved in late-onset FGR. Future validation and feasibility studies will be required to propose miRNAs as a valid tool in the diagnosis and management of FGR.

Unique microRNA Signals in Plasma Exosomes from Pregnancies Complicated by Preeclampsia

Although preeclampsia is a common and serious complication of pregnancy, insight into its pathobiology and diagnosis is lacking. Circulating plasma exosomes, which contain RNA and other molecules and have recently become accessible for diagnostics, may be informative in this regard. We tested the hypothesis that preeclampsia may affect the miRNA cargo within circulating maternal blood exosomes. We collected plasma from 60 pregnant women at term, including 20 women with pregnancy complicated by preeclampsia, and 20 women with fetal growth restriction and 20 with healthy pregnancy, serving as controls. We isolated exosomes from the maternal plasma by continuous density gradient ultracentrifugation. Our main outcome variable was exosomal miRNA cargo, analyzed by quantitative polymerase chain reaction-based TaqMan advanced miRNA assay in a card format and the expression of differentially expressed exosomal miRNA in whole plasma from the same participants. We found that 7 miRNA species were differentially expressed in exosomes from women with preeclampsia and those from controls. In contrast, there was no significant difference in exosomal miRNA expression between women with fetal growth restriction and controls. The results were not affected by fetal sex. Only one of the preeclampsia-related, differentially expressed exosomal miRNAs was significantly different in whole plasma miRNA analysis. We concluded that unlike whole plasma miRNA, exosomes extracted from the plasma of women with preeclampsia exhibit a unique miRNA profile, suggesting that plasma exosomal miRNA could provide insight into the pathophysiology of preeclampsia, and may play a role in disease diagnostics.

Clinical application of exosomes and circulating microRNAs in the diagnosis of pregnancy complications and foetal abnormalities

During pregnancy in humans, the physiology of the mother and foetus are finely regulated by many factors. Inappropriate regulation can result in pregnancy disorders, such as complications and foetal abnormalities. The early prediction or accurate diagnosis of related diseases is a concern of researchers. Liquid biopsy can be analysed for circulating cells, cell-free nucleic acids, and exosomes. Because exosomes can be detected in the peripheral blood of women in early pregnancy, these vesicles and their contents have become the focus of early prediction or diagnostic biomarker research on pregnancy complications and foetal developmental disorders. In this review, we focus on recent studies addressing the roles of peripheral blood exosomes and circulating miRNAs in pregnancy complications and in pregnancies with abnormal foetal developmental disorders, with particular attention paid to the potential application value of exosomes and circulating miRNAs as disease-specific biomarkers.

Maternal and environmental risk factors for neonatal AKI and its long-term consequences

Acute kidney injury (AKI) is a common and life-threatening complication in critically ill neonates. Gestational risk factors for AKI include premature birth, intrauterine growth restriction and low birthweight, which are associated with poor nephron development and are often the consequence of pre-gestational and gestational factors, such as poor nutritional status. Our understanding of how to best optimize renal development and prevent AKI is in its infancy; however, the identification of pre-gestational and gestational factors that increase the risk of adverse neonatal outcomes and the implementation of interventions, such as improving nutritional status early in pregnancy, have the potential to optimize fetal growth and reduce the risk of preterm birth, thereby improving kidney health. The overall risk of AKI among critically ill and premature neonates is exacerbated postnatally as these infants are often exposed to dehydration, septic shock and potentially nephrotoxic medications. Strategies to improve outcomes - for example, through careful evaluation of nephrotoxic drugs - may reduce the incidence of AKI and its consequences among this population. Management strategies and updated technology that will support neonates with AKI are greatly needed. Extremely premature infants and those who survive an episode of AKI should be screened for chronic kidney disease until early adulthood. Here, we provide an overview of our current understanding of neonatal AKI, focusing on its relationship to preterm birth and growth restriction. We describe factors that prevent optimal nephrogenesis during pregnancy and provide a framework for future explorations designed to maximize outcomes in this vulnerable population.

MicroRNA-30d deficiency during preconception affects endometrial receptivity by decreasing implantation rates and impairing fetal growth

BACKGROUND

Maternal-embryonic crosstalk between the endometrium and the preimplantation embryo is required for normal pregnancy. Our previous results demonstrated that maternal microRNAs secreted into the endometrial fluid, specifically miR-30d, act as a transcriptomic regulator of the preimplantation embryo by the maternal intrauterine environment.

OBJECTIVE

To investigate the reproductive and fetal effects of murine miR-30d deficiency at the maternal-embryonic interface according to the origin of its maternal or embryonic default.

STUDY DESIGN

A miR-30d knockout murine model was used as the animal model to investigate the impact of maternal and/or embryonic origin of miR-30d deficiency on embryonic implantation and fetal development. Wild-type and miR-30d knockout pseudopregnant mice were used to study the effect of miR-30d deficiency on the receptivity markers by means of real-time quantitative polymerase chain reaction, immunofluorescence, and western blotting. We assessed receptivity markers and implantation rates in 6 different transfer conditions in which embryos obtained from wild-type, knockout, and knockout embryos pretreated with a miR-30d analog were transferred into either wild-type or knockout pseudopregnant females. The impact of miR-30d deficiency on fetal development was evaluated by analyzing the implantation sites and resorbing sites under physiological conditions at days 5, 6, 8, and 12 of pregnancy. Fetal growth was evaluated by analyzing fetuses and placentas at days 12 and 16 of pregnancy.

RESULTS

Maternal miR-30d deficiency induced a significant downregulation of endometrial receptivity markers. In wild-type recipients, miR-30d knockout embryos had poorer implantation rates than wild-type embryos (48.86 ± 14.33% vs 75.00 ± 10.47%, respectively, P = .0061). In miR-30d knockout recipients, the lowest implantation rate was observed when knockout embryos were transferred compared to wild-type embryos (26.04 ± 7.15% and 49.71 ± 8.59%, respectively, P = .0059). A positive correlation (r = 0.9978) was observed for maternal leukemia inhibitor factor expression with implantation rates. Further, the course of gestation was compromised in miR-30d knockout mothers, which had smaller implantation sites, greater rates of resorption, and fetuses with smaller crown-rump length and fetal/placental weight ratio.

CONCLUSION

Our results demonstrate that maternal and/or embryonic miR-30d deficiency impairs embryonic implantation and fetal development in the animal model. This finding adds a novel miRNA dimension to the understanding of pregnancy and fetal growth restriction in humans.

Placental expression of microRNAs in infants born small for gestational age

INTRODUCTION

The molecular mechanisms behind poor foetal growth are not fully known. The aim of this study was to explore global microRNA expression in placentas of infants born small for gestational age (SGA) compared to infants with a normal birth weight (NBW).

METHODS

Placental biopsies from term infants were identified in a biobank and divided into four groups: infants born SGA with (n = 13) or without (n = 9) exposure to low maternal gestational weight gain (GWG) and infants born with NBWs with (n = 20) or without (n = 26) exposure to low GWG. All women and infants were healthy, and no woman smoked during pregnancy. Only vaginal deliveries were included. Next-generation sequencing was performed with single read sequencing of >9 million reads per sample. Differential microRNA expression was analysed using ANOVA for unequal variances (Welch) with multiple testing corrections through the Benjamini-Hochberg method. A fold change >2 and a corrected p value < 0.05 were considered significant. Adjustments for possible confounding factors were made using a linear regression model.

RESULTS

A total of 1870 known, mature human microRNAs were detected in the sample. MiR-3679-5p and miR-193b-3p were significantly upregulated, and miR-379-3p, miR-335-3p, miR-4532, miR-519e-3p, miR-3065-5p, and miR-105-5p were significantly downregulated after adjustment for potential confounding factors in SGA infants with normal GWG compared to infants with NBWs and normal GWG.

DISCUSSION

Infants born unexplained SGA show differential microRNA expression in their placenta. Important pathways for the differentially expressed microRNAs include inflammation and the insulin-IGF system.

Hypoxia-induced microRNA-141 regulates trophoblast apoptosis, invasion, and vascularization by blocking CXCL12β/CXCR2/4 signal transduction

BACKGROUND

An impaired trophoblast invasion ability contributes to the development of pre-eclampsia (PE), and can be induced by the altered expression of various microRNAs (miRs). MiR-141 and CXCL12β (C-X-C motif chemokine ligand 12) signaling regulate trophoblast invasion and vascularization capabilities during PE pathogenesis; however, their interactions and underlying mechanisms of action remain unclear. We investigated how miR-141 modulates trophoblast invasion, with a focus on its interaction with CXCL12β signaling.

METHODS

A PE model was established by using HTR-8/SVneo cells, which were first cultured with 2% O₂ for 48 h, and then with 5% O₂. The expression of miR-141 in human villous trophoblast HTR-8/SVneo cells was modulated with mimics or an inhibitor, and analyzed by quantitative RT-PCR. CXCL12β levels were determined by ELISA. Cell apoptosis was determined by flow cytometry, and the invasion and vascularization capabilities of trophoblasts were evaluated by Transwell and tube formation assays, respectively. Binding of miR-141 with CXCL12β mRNA was verified by the dual luciferase assay. Protein levels were estimated by western blotting.

RESULTS

MiR-141 expression was significantly induced by hypoxia in HTR-8/SVneo cells. MiR-141 was found to promote apoptosis and inhibit the invasion and vascularization abilities of HTR-8/SVneo cells under conditions of hypoxia. MiR-141 could directly bind with the 3'UTR region of CXCL12β mRNA and inhibit its translation. In addition, we proved that miR-141 could inhibit the invasion and vascularization abilities, and promote the apoptosis of HTR-8/SVneo cells by targeting CXCL12β under hypoxic conditions. Furthermore, we demonstrated that arachidonic acid could reverse the invasion and apoptosis abilities of HTR-8/SVneo cells mediated by CXCL12β during hypoxia. In terms of mechanism, MiR-141 could downregulate MMP2, p62, and LC3B expression, and upregulate ROCK1 and RhoA expression in HTR-8/SVneo cells by targeting the CXCL12β gene during hypoxia. The effects of CXCL12βon HTR-8/SVneo cells could be reversed by arachidonic acid (ARA).

CONCLUSION

Induction of miR-141 by hypoxia promotes apoptosis, and inhibits the invasion and vascularization capabilities of HTR-8/SVneo cells by suppressing the CXCL12β and CXCR2/4 signaling pathways.

Imprinted MicroRNA Gene Clusters in the Evolution, Development, and Functions of Mammalian Placenta

In mammals, the expression of a subset of microRNA (miRNA) genes is governed by genomic imprinting, an epigenetic mechanism that confers monoallelic expression in a parent-of-origin manner. Three evolutionarily distinct genomic intervals contain the vast majority of imprinted miRNA genes: the rodent-specific, paternally expressed C2MC located in intron 10 of the Sfmbt2 gene, the primate-specific, paternally expressed C19MC positioned at human Chr.19q13.4 and the eutherian-specific, maternally expressed miRNAs embedded within the imprinted Dlk1-Dio3 domains at human 14q32 (also named C14MC in humans). Interestingly, these imprinted miRNA genes form large clusters composed of many related gene copies that are co-expressed with a marked, or even exclusive, localization in the placenta. Here, we summarize our knowledge on the evolutionary, molecular, and physiological relevance of these epigenetically-regulated, recently-evolved miRNAs, by focusing on their roles in placentation and possibly also in pregnancy diseases (e.g., preeclampsia, intrauterine growth restriction, preterm birth).

Molecular Principles of Intrauterine Growth Restriction in Plasmodium Falciparum Infection

Malaria in pregnancy still constitutes a particular medical challenge in tropical and subtropical regions. Of the five Plasmodium species that are pathogenic to humans, infection with Plasmodium falciparum leads to fulminant progression of the disease with massive impact on pregnancy. Severe anemia of the mother, miscarriage, stillbirth, preterm delivery and intrauterine growth restriction (IUGR) with reduced birth weight are frequent complications that lead to more than 10,000 maternal and 200,000 perinatal deaths annually in sub-Saharan Africa alone. P. falciparum can adhere to the placenta via the expression of the surface antigen VAR2CSA, which leads to sequestration of infected erythrocytes in the intervillous space. This process induces a placental inflammation with involvement of immune cells and humoral factors. Especially, monocytes get activated and change the release of soluble mediators, including a variety of cytokines. This proinflammatory environment contributes to disorders of angiogenesis, blood flow, autophagy, and nutrient transport in the placenta and erythropoiesis. Collectively, they impair placental functions and, consequently, fetal growth. The discovery that women in endemic regions develop a certain immunity against VAR2CSA-expressing parasites with increasing number of pregnancies has redefined the understanding of malaria in pregnancy and offers strategies for the development of vaccines. The following review gives an overview of molecular processes in P. falciparum infection in pregnancy which may be involved in the development of IUGR.

MicroRNA-210 expression during childbirth and postpartum as a potential biomarker of acute fetal hypoxia

OBJECTIVE

To explore whether miR-210 expression can be used as a diagnostic and prognostic marker in acute fetal hypoxia.

METHODS

Whole blood samples of 29 women and their fetuses without hypoxia and 24 women and their fetuses with hypoxia were analysed in this study. Reverse transcription and quantitative real-time PCR were used to measure the expression of miR-210. Expression level differences between the control and hypoxic group in labour time and postpartum change fold were analyzed by standard statistical tests.

RESULTS

We confirmed that miR-210 is significantly more upregulated in fetal blood with acute hypoxia when compared to maternal blood (P Conclusions: Our study confirmed miR-210 upregulation in the blood of pregnant women with acute fetal hypoxia at the time of labour compared to pregnant women without acute fetal hypoxia. Additional investigation should be done to determine miR-210 clearance and the possibility of using miR-210 as a diagnostic and prognostic marker.

Contribution of regulatory T cells to immune tolerance and association of microRNA‑210 and Foxp3 in preeclampsia

Increasing evidence suggests that an exaggerated maternal systemic inflammatofrery response may play a central role in the pathogenesis of preeclampsia (PE). Considering the growing evidence on microRNAs (miRNAs) and tissue‑specific regulators of gene expression, we investigated the potential association of miR‑210 and forkhead box p3 (Foxp3) in preeclamptic patients. Serum levels of the cytokines interleukin (IL)‑6, IL‑10, IL‑17, and transforming grown factor‑β1 were detected with ELISA. Reverse‑transcription‑quantitative polymerase chain reaction was performed to detect mRNA expression for maternal placenta retinoic acid‑related orphan receptor C, Foxp3 and miRNA (miR)‑210. Foxp3 protein expression was evaluated by western blot analysis. Serum levels of cytokines IL‑10 were significantly lower in preeclamptic patients than in normal pregnant women. mRNA expression of Foxp3 was significantly lower in placenta of PE. mRNA expression of miR‑210 was significantly increased in PE. Results of western blot analysis indicated that Foxp3 protein expression was lower in PE than in normal pregnant women. Our data suggest that PE manifests as a decreased number of regulatory T cells (Tregs), which regulate maternal tolerance of the fetus. In placenta from women with PE, compared with normal pregnant women, mRNA expression of Foxp3 was significantly decreased, and expression of miR‑210 was significantly increased.

RNA-sequencing analysis of umbilical cord plasma microRNAs from healthy newborns

MicroRNAs are a class of small non-coding RNA that regulate gene expression at a post-transcriptional level. MicroRNAs have been identified in various body fluids under normal conditions and their stability as well as their dysregulation in disease has led to ongoing interest in their diagnostic and prognostic potential. Circulating microRNAs may be valuable predictors of early-life complications such as birth asphyxia or neonatal seizures but there are relatively few data on microRNA content in plasma from healthy babies. Here we performed small RNA-sequencing analysis of plasma processed from umbilical cord blood in a set of healthy newborns. MicroRNA levels in umbilical cord plasma of four male and four female healthy babies, from two different centres were profiled. A total of 1,004 individual microRNAs were identified, which ranged from 426 to 659 per sample, of which 269 microRNAs were common to all eight samples. Many of these microRNAs are highly expressed and consistent with previous studies using other high throughput platforms. While overall microRNA expression did not differ between male and female cord blood plasma, we did detect differentially edited microRNAs in female plasma compared to male. Of note, and consistent with other studies of this type, adenylation and uridylation were the two most prominent forms of editing. Six microRNAs, miR-128-3p, miR-29a-3p, miR-9-5p, miR-218-5p, 204-5p and miR-132-3p were consistently both uridylated and adenylated in female cord blood plasma. These results provide a benchmark for microRNA profiling and biomarker discovery using umbilical cord plasma and can be used as comparative data for future biomarker profiles from complicated births or those with early-life developmental disorders.

Diabetes in Pregnancy and MicroRNAs: Promises and Limitations in Their Clinical Application

Maternal diabetes is associated with an increased risk of complications for the mother and her offspring. The latter have an increased risk of foetal macrosomia, hypoglycaemia, respiratory distress syndrome, preterm delivery, malformations and mortality but also of life-long development of obesity and diabetes. Epigenetics have been proposed as an explanation for this long-term risk, and microRNAs (miRNAs) may play a role, both in short- and long-term outcomes. Gestation is associated with increasing maternal insulin resistance, as well as β-cell expansion, to account for the increased insulin needs and studies performed in pregnant rats support a role of miRNAs in this expansion. Furthermore, several miRNAs are involved in pancreatic embryonic development. On the other hand, maternal diabetes is associated with changes in miRNA both in maternal and in foetal tissues. This review aims to summarise the existing knowledge on miRNAs in gestational and pre-gestational diabetes, both as diagnostic biomarkers and as mechanistic players, in the development of gestational diabetes itself and also of short- and long-term complications for the mother and her offspring.

MiR-199a-5p regulates sirtuin1 and PI3K in the rat hippocampus with intrauterine growth restriction

In humans, malnutrition during pregnancy results in intrauterine growth restriction (IUGR) and an increased risk of neurological morbidities; altered miRNA characteristics have been suggested to contribute to IUGR neurological pathogenesis. A miRNA microarray was used to identify differentially expressed miRNA molecules in the hippocampi of rats with IUGR. Five of the molecules in question were selectively validated using real-time PCR in rats with IUGR. We then investigated the role of miR-199a-5p in hippocampal pathology. Bioinformatics analysis results suggested that TNF-α, caspase-3 and SIRT1 were potential targets of miR-199a-5p. Changes in PI3K, SIRT1 and caspase-3 protein expressions levels in the hippocampus were confirmed by Western blot analysis (all P < 0.05). Studies using the pheochromocytoma cell line PC12 cells and primary neurons demonstrated that miR-199a-5p modulated PI3K, caspase-3 and SIRT1 expression. Additionally, there was an inverse correlation between miR-199a-5p and caspase-3 expression, though dual-luciferase reporter assays showed that caspase-3 is not a target of miR-199a-5p. We conclude that IUGR affects hippocampal miRNAs characteristics. Our results also indicated that aberrantly high expression levels of miR-199a-5p may play an important role in the pathogenesis of IUGR by regulating SIRT1 and PI3K.

Cardiac remodeling and pre-eclampsia: an overview of microRNA expression patterns

Pre-eclampsia (PE) is strongly associated with heart failure (HF) later in life. During PE pregnancy, the left ventricle undergoes concentric remodeling which often persists after delivery. This aberrant remodeling can induce a molecular signature that can be evaluated in terms of microRNAs (miRNAs) and which may help to explain the associated increased risk of HF. For this review, we performed a literature search of PubMed (National Center for Biotechnology Information), identifying studies on miRNA expression in concentric remodeling and on miRNA expression in PE. The miRNA data were stratified based on origin (isolated from humans or animals and from tissue or the circulation) and both datasets compared in order to generate a list of miRNA expression patterns in concentric remodeling and in PE. The nine miRNAs identified in both concentric remodeling and PE-complicated pregnancy were: miR-1, miR-18, miR-21, miR-29b, miR-30, miR-125b, miR-181b, miR-195 and miR-499-5p. We found five of these miRNAs (miR-18, miR-21, miR-125b, miR-195 and miR-499-5p) to be upregulated in both PE pregnancy and cardiac remodeling and two (miR-1 and miR-30) to be downregulated in both; the remaining two miRNAs (miR-29b and miR-181b) showed upregulation during PE but downregulation in cardiac remodeling. This innovative approach may be a step towards finding relevant biomarkers for complicated pregnancy and elucidating their relationship with remote cardiovascular disease. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Exploring maternal serum microRNAs during early pregnancy in cattle

Confirmation of the pregnancy establishment at the very earliest day post-insemination increases the reproduction efficiency of high yielding dairy cows and farm profitability by allowing rebreeding of the non-pregnant cows. Inaccuracies in the currently available pregnancy detection tools to detect pregnancy establishment within the first 3 weeks post insemination extends the inter-calving interval and have contributed to the decline in profitability. Thus, development of non-invasive early pregnancy detection biomarkers could be proposed as alternative tools. MicroRNAs (miRNAs), a subclass of small non-coding RNAs are abundantly expressed in virtually all bio fluids circulation and have been associated with various pregnancy-related pathophysiological conditions. The study aimed to determine the expression of circulatory miRNAs in serum samples of pregnant and non-pregnant cows at day 19 and 24 post-insemination. Lactating Holstein-Friesian cows were estrous synchronized and inseminated with frozen semen. Blood samples were taken 19 and 24 days post-insemination. Serum samples were retrospectively categorized according to the pregnancy status of cows diagnosed 35 later using ultrasonography. Total RNA enriched with miRNAs was isolated from pooled (4 animals/pool) serum samples of pregnant and non-pregnant cows and subjected to cDNA synthesis. The expression of circulatory miRNAs was performed using PCR array containing primers 748 mature miRNAs. Results showed that a total of 302 and 316 miRNAs were detected in day 19 pregnant and non-pregnant cows, respectively. Similarly, 356 and 325 miRNAs were detected in day 24 pregnant and non-pregnant cows, respectively. Principal component analysis showed clear separation between pregnant and non-pregnant cows both at 19 and 24 days. We identified 8 and 23 differentially expressed miRNAs in the serum of pregnant cows of day 19 and 24, respectively. Interestingly, miR-433 and 4 other miRNAs (miR-487b, miR-495-3p, miR-376b-3p, and miR-323a-3p), which are homologous to the human pregnancy-associated C14MC miRNAs were among the differentially expressed miRNAs in day 19 and 24 pregnant cows, respectively. The adherens junction and ECM-interaction are among the pathways significantly enriched by predicted target genes of differentially expressed miRNAs. In conclusion, the expression of circulatory miRNAs in maternal blood serum of pregnant and non-pregnant cows showed distinct expression pattern and could suggest their potential involvement in early pregnancy establishment.

Effect of early postnatal nutrition on chronic kidney disease and arterial hypertension in adulthood: a narrative review

Intrauterine growth restriction (IUGR) has been identified as a risk factor for adult chronic kidney disease (CKD), including hypertension (HTN). Accelerated postnatal catch-up growth superimposed to IUGR has been shown to further increase the risk of CKD and HTN. Although the impact of excessive postnatal growth without previous IUGR is less clear, excessive postnatal overfeeding in experimental animals shows a strong impact on the risk of CKD and HTN in adulthood. On the other hand, food restriction in the postnatal period seems to have a protective effect on CKD programming. All these effects are mediated at least partially by the activation of the renin-angiotensin system, leptin and neuropeptide Y (NPY) signaling and profibrotic pathways. Early nutrition, especially in the postnatal period has a significant impact on the risk of CKD and HTN at adulthood and should receive specific attention in the prevention of CKD and HTN.

Gestational Hypoxia and Developmental Plasticity

Hypoxia is one of the most common and severe challenges to the maintenance of homeostasis. Oxygen sensing is a property of all tissues, and the response to hypoxia is multidimensional involving complicated intracellular networks concerned with the transduction of hypoxia-induced responses. Of all the stresses to which the fetus and newborn infant are subjected, perhaps the most important and clinically relevant is that of hypoxia. Hypoxia during gestation impacts both the mother and fetal development through interactions with an individual's genetic traits acquired over multiple generations by natural selection and changes in gene expression patterns by altering the epigenetic code. Changes in the epigenome determine "genomic plasticity," i.e., the ability of genes to be differentially expressed according to environmental cues. The genomic plasticity defined by epigenomic mechanisms including DNA methylation, histone modifications, and noncoding RNAs during development is the mechanistic substrate for phenotypic programming that determines physiological response and risk for healthy or deleterious outcomes. This review explores the impact of gestational hypoxia on maternal health and fetal development, and epigenetic mechanisms of developmental plasticity with emphasis on the uteroplacental circulation, heart development, cerebral circulation, pulmonary development, and the hypothalamic-pituitary-adrenal axis and adipose tissue. The complex molecular and epigenetic interactions that may impact an individual's physiology and developmental programming of health and disease later in life are discussed.

MicroRNAs: crucial regulators of placental development

MicroRNAs (miRNAs) are small non-coding single-stranded RNAs that are integral to a wide range of cellular processes mainly through the regulation of translation and mRNA stability of their target genes. The placenta is a transient organ that exists throughout gestation in mammals, facilitating nutrient and gas exchange and waste removal between the mother and the fetus. miRNAs are expressed in the placenta, and many studies have shown that miRNAs play an important role in regulating trophoblast differentiation, migration, invasion, proliferation, apoptosis, vasculogenesis/angiogenesis and cellular metabolism. In this review, we provide a brief overview of canonical and non-canonical pathways of miRNA biogenesis and mechanisms of miRNA actions. We highlight the current knowledge of the role of miRNAs in placental development. Finally, we point out several limitations of the current research and suggest future directions.

Foetoplacental communication via extracellular vesicles in normal pregnancy and preeclampsia

Intercellular communication is a critical process in biological mechanisms. During pregnancy foetoplacental tissues release a heterogeneous group of extracellular vesicles (EVs) that include exosomes, microvesicles, apoptotic bodies, and syncytial nuclear aggregates. These vesicles contain a complex cargo (proteins, DNA, mRNA transcripts, microRNAs, noncoding RNA, lipids, and other molecules) that actively participate in the maternal-foetal communication by modulating different processes during gestation for a successful foetal development. Each stage of human gestation is marked by events such as immunomodulation, proliferation, invasion, migration, and differentiation, among others, requiring EVs-mediated signalling to be nearby or distant target cells. Furthermore, EVs also associate with pregnancy pathologies such as preeclampsia and intrauterine growth restriction. This review addresses the role of EVs in human foetomaternal communication in normal pregnancy and preeclampsia.

Circulating levels of specific members of chromosome 19 microRNA cluster are associated with preeclampsia development

PURPOSE

To perform serum microRNA expression profiling to identify members of chromosome 19 miRNA cluster involved in preeclampsia development.

METHODS

Serum chromosome 19 miRNA cluster microRNA expression profiling was evaluated at 12, 16, and 20 gestational weeks and at the time of preeclampsia diagnosis, in women who developed preeclampsia (WWD-PE; n = 16) and controls (n = 18) using TaqMan low density array plates.

RESULTS

A total of 51 chromosome 19 microRNA cluster members were evaluated. The circulating hsa-miRs 512-3p, 518f-3p, 520c-3p, and 520d-3p, were differentially expressed between groups (P < 0.05). Compared with controls, serum levels of hsa-miR-518f-3p at 20 GW were useful for identifying WWD-Mild-PE (P = 0.035) and WWD-Severe-PE (P = 0.007).

CONCLUSIONS

Serum hsa-miRs 512-3p, 518f-3p, 520c-3p, and 520d-3p, are differentially expressed between WWD-PE and controls and their role in the development of preeclampsia should be investigated further.

The diagnostic value of microRNA-4787-5p and microRNA-4306 in patients with acute aortic dissection

Acute aortic dissection (AAD) is a life-threatening cardiovascular disease with the high morbidity and mortality. Imaging modalities are the gold standard for the diagnosis of AAD; however, they are not always available in emergency department. Biomarker-assisted diagnosis is important for the early treatment of AAD. The aim of the present study was to identify potential microRNA (miRNA) biomarkers for AAD. Differentially expressed plasma miRNAs between AAD patients and age-matched healthy volunteers were analyzed by miRNA microarray. Quantitative RT-PCR was further performed to verify the expression of selected miRNAs (miR-4787-5p and miR-4306) with an increased number of samples. Receiver operating characteristic (ROC) analysis was used to assess the diagnostic value of miR-4787-5p and miR-4306 as biomarkers for distinguishing AAD. Using TargetScan and miRanda, miR-4787-5p and miR-4306 were selected to predict target gene related to cytokines detecting by dual luciferase assay and western blotting. Nine upregulated and twelve downregulated miRNAs were identified in the circulating plasma of AAD patients. qRT-PCR verified statistically consistent expression of two selected miRNAs with microarray analysis. ROC analyses demonstrated that miR-4787-5p and miR-4306 were specific and sensitive for the early diagnosis of AAD. Bioinformatic predictions and dual luciferase assay suggested that polycystin-1 (PKD1) and transforming growth factor-β1 (TGF-β1) were respectively direct target of miR-4787-5p and miR-4306. Furthermore, the protein expression of the downstream targets of PKD1 and TGF-β1 were significantly reduced following overexpression of miR-4787-5p and miR-4306. These results revealed that miR-4787-5p and miR-4306 could be developed as diagnostic potential biomarkers for AAD, and they could be involved in the pathogenesis of AAD.

Increased miR-223 expression in foetal organs is a signature of acute chorioamnionitis with systemic consequences

Acute chorioamnionitis, frequently observed in preterm placentas, is a major risk factor for the development of infection and non-infection-related adverse perinatal outcomes. MicroRNAs play important roles in immune cell development and function as well as in the development of cancers and neurologic diseases. We sought to investigate the changes in microRNA-223 (miR-223) expression and the functional significance of the changes in miR-223 expression in foetal organs in the presence of acute chorioamnionitis. Using formalin-fixed, paraffin-embedded (FFPE) tissue samples from foetal or neonatal autopsy cases, which are the most practical option to study the changes in several organs simultaneously, miR-223 expression profiles in foetal thymus, lung and liver were compared between cases with and without acute chorioamnionitis. Total RNA was extracted from FFPE specimens and qRT-PCR was conducted. miR-223-3p expression levels in foetal thymus (2.55-fold), lung (1.93-fold) and liver (1.70-fold) were significantly higher in cases with acute chorioamnionitis than in those without. Transfection of pre-miR-223-3p in Jurkat cells and luciferase assay and ribonucleoprotein immunoprecipitation followed by qRT-PCR analysis confirmed the binding of miR-223 to the 3' untranslated region (3'UTR) of forkhead box O1 (FoxO1) mRNA and the regulation of FoxO1 by miR-223. We report for the first time that foetuses with inflammation in the chorioamniotic membranes show increased expression of miR-223 in the thymus, lung and liver. Furthermore, FoxO1 is a target of miR-223. These findings suggest that post-transcriptional regulation of genes by miR-223 is a component of the foetal inflammatory response, which has systemic consequences in the foetus.

Second trimester extracellular microRNAs in maternal blood and fetal growth: An exploratory study

Healthy feto-maternal communication is critical during pregnancy and is orchestrated by the placenta. Dysfunction of the placenta leads to fetal growth complications; however, the underlying biological mechanisms have yet to be fully elucidated. Circulating extracellular microRNAs (exmiRNAs) in the blood have been implicated in cell-to-cell communication. Therefore, exmiRNAs may provide useful biological information about communication between the mother, the fetus, and the placenta during pregnancy. We used logistic regression to determine the association of exmiRNAs with abnormal fetal growth by comparing mothers of infants classified as small-for-gestational age (SGA) (n = 36) and large-for-gestational age (LGA) (n = 13) to appropriate-for-gestational age (AGA), matched by gestational age at delivery and infant sex. In addition, we used linear regression to determine associations between exmiRNAs and birth weight-for-gestational age (BWGA) z-score (n = 100), adjusting for maternal age, body mass index, and parity. We found that higher levels of miR-20b-5p, miR-942-5p, miR-324-3p, miR-223-5p, and miR-127-3p in maternal serum were associated with lower odds for having a SGA vs. AGA infant, and higher levels of miR-661, miR-212-3p, and miR-197-3p were associated with higher odds for having a LGA vs. AGA infant. We also found associations between miR-483-5p, miR-10a-5p, miR-204-5p, miR-202-3p, miR-345-5p, miR-885-5p, miR-127-3p, miR-148b-3p, miR-324-3p, miR-1290, miR-597-5p, miR-139-5p, miR-215-5p, and miR-99b-5p and BWGA z-score. We also found sex-specific associations with exmiRNAs and fetal growth. Our findings suggest that exmiRNAs circulating in maternal blood at second trimester are associated with fetal growth. Validation of our findings may lead to the development of minimally-invasive biomarkers of fetal growth during pregnancy.

MicroRNA Signaling in Embryo Development

Expression of microRNAs (miRNAs) is essential for embryonic development and serves important roles in gametogenesis. miRNAs are secreted into the extracellular environment by the embryo during the preimplantation stage of development. Several cell types secrete miRNAs into biological fluids in the extracellular environment. These fluid-derived miRNAs have been shown to circulate the body. Stable transport is dependent on proper packaging of the miRNAs into extracellular vesicles (EVs), including exosomes. These vesicles, which also contain RNA, DNA and proteins, are on the forefront of research on cell-to-cell communication. Interestingly, EVs have been identified in many reproductive fluids, such as uterine fluid, where their miRNA content is proposed to serve as a mechanism of crosstalk between the mother and conceptus. Here, we review the role of miRNAs in molecular signaling and discuss their transport during early embryo development and implantation.

Central nervous system development-related microRNAs levels increase in the serum of gestational diabetic women during the first trimester of pregnancy

MicroRNAs are heterochronic molecules important during brain development, which could be altered by gestational diabetes mellitus (GDM). To explore these molecules in maternal serum, we performed an RT-qPCR analysis. Our results revealed the heterochronic character of some neural development-related microRNA in serum samples of pregnant women. In relation to the first trimester, higher levels of miR-183-5p, -200b-3p, and -125-5p in the second trimester, and higher levels of miR-137 in the third trimester, were found. Furthermore, an insult such as GDM led to higher levels of miR-183-5p, -200b-3p, -125-5p, and -1290 relative to the control in the first trimester, which might be related to changes in neurogenesis and cell proliferation. An in silico analysis suggested that increased microRNAs in the second trimester in the control contributed to cell proliferation and neuron differentiation and that the rise in miR-137 in the third trimester led to neuron maturation. In the diabetic, higher levels of the microRNAs in the first trimester suggested alterations in cell proliferation and neuron differentiation. In conclusion, we showed that fetal-related microRNAs can be detected in the serum of pregnant woman and exhibit temporary regulation during pregnancy and that microRNAs involved in cell proliferation and neuron differentiation are upregulated under GDM.

Cell-free Fetal Nucleic Acid Identifier Markers in Maternal Circulation

From the discovery of cell-free fetal (cff)-DNA in 1997 so far, many studies have been performed on various aspects of cff-nucleic acid. It is undoubted that currently, invasive prenatal diagnosis progresses to the noninvasive test. However, there are many problems. One of the most challenging issues in this field is differentiation and detection of the small amount of cff-nucleic acid in maternal plasma. Many markers and methods have been used for this purpose. This review makes an attempt to review and compare the studies in the field. Six identifier markers including Y-specific sequence, polymorphisms, epigenetic difference, DNA size difference, fetal mRNA, and microRNA as well as the advantages and disadvantages of each marker are discussed. This review provides a relatively perfect set on cff-nucleic acid biomarkers in various physiological and pathological status of pregnancy, helping to review and compare the prior obtained results, and improving designation in future studies.

Differential miR-346 and miR-582-3p Expression in Association with Selected Maternal and Fetal Complications

Several miRNAs are expressed in human gestational tissue, and some have been shown to be associated with placental dysfunction and complicated pregnancy outcomes. To investigate the roles of miR-346 and miR-582-3p in adverse obstetric events, we analyzed these 2 miRNAs in three samples (maternal blood, umbilical cord blood and placenta) obtained from pregnant women in four groups, including healthy control (n = 60), preeclampsia (n = 31), preterm delivery (n = 29) and small for gestational age (n = 19) patients. The expression levels of miR-346 and miR-582-3p in all included adverse obstetric outcome groups were significantly higher in the maternal plasma samples but lower in the placenta samples (all p value < 0.05). In addition, the miR-346 expression levels in fetal cord blood were also significantly lower in all of the included adverse obstetric outcome groups (all p < 0.05). Multivariate analysis of the three specimens after adjusting for maternal age and gestational age at delivery gave the same results. In conclusion, aberrant miR-346 and miR-582-3p expression level in pregnancy was associated with multiple maternal and fetal complications. Their differential expression in maternal blood, umbilical cord blood and placenta could be potential biomarkers or therapeutic targets for adverse obstetric outcomes

Dysregulation of Placental miRNA in Maternal Obesity Is Associated With Pre- and Postnatal Growth

CONTEXT

Human placenta exhibits a specific microRNA (miRNA) expression pattern. Some of these miRNAs are dysregulated in pregnancy disorders such as preeclampsia and intrauterine growth restriction and are potential biomarkers for these pathologies.

OBJECTIVE

To study the placental miRNA profile in pregnant women with pregestational overweight/obesity (preOB) or gestational obesity (gestOB) and explore the associations between placental miRNAs dysregulated in maternal obesity and prenatal and postnatal growth.

METHODS

TaqMan Low Density Arrays and real-time polymerase chain reaction were used to profile the placental miRNAs in 70 pregnant women (20 preOB, 25 gestOB, and 25 control). Placentas and newborns were weighed at delivery, and infants were weighed at 1, 4, and 12 months of age.

RESULTS

Eight miRNAs were decreased in placentas from preOB or gestOB (miR-100, miR-1269, miR-1285, miR-181, miR-185, miR-214, miR-296, and miR-487) (all P < 0.05). Among them, miR-100, miR-1285, miR-296, and miR-487 were associated with maternal metabolic parameters (all P < 0.05) and were predictors of lower birth weight (all P < 0.05; R2 > 30%) and increased postnatal weight gain (all P < 0.05; R2 > 20%). In silico analysis showed that these miRNAs were related to cell proliferation and insulin signaling pathways. miR-296 was also present in plasma samples and associated with placental expression and prenatal and postnatal growth parameters (all P < 0.05).

CONCLUSIONS

We identified a specific placental miRNA profile in maternal obesity. Placental miRNAs dysregulated in maternal obesity may be involved in mediation of growth-promoting effects of maternal obesity on offspring and could be used as early markers of prenatal and postnatal growth.