Circulating Levels of Pregnancy-Associated, Placenta-Specific microRNAs in Pregnant Women With Placental Abruption

Amniotic Fluid microRNA in Severe Twin-Twin Transfusion Syndrome Cardiomyopathy-Identification of Differences and Predicting Demise

Twin-twin transfusion syndrome (TTTS) is a rare but serious cause of fetal cardiomyopathy with poorly understood pathophysiology and challenging prognostication. This study sought a nonbiased, comprehensive assessment of amniotic fluid (AF) microRNAs from TTTS pregnancies and associations of these miRNAs with clinical characteristics. For the discovery cohort, AF from ten fetuses with severe TTTS cardiomyopathy were selected and compared to ten normal singleton AF. Array panels assessing 384 microRNAs were performed on the discovery cohort and controls. Using a stringent q < 0.0025, arrays identified 32 miRNAs with differential expression. Top three microRNAs were miR-99b, miR-370 and miR-375. Forty distinct TTTS subjects were selected for a validation cohort. RT-PCR targeted six differentially-expressed microRNAs in the discovery and validation cohorts. Expression differences by array were confirmed by RT-PCR with high fidelity. The ability of these miRNAs to predict clinical differences, such as cardiac findings and later demise, was evaluated on TTTS subjects. Down-regulation of miRNA-127-3p, miRNA-375-3p and miRNA-886 were associated with demise. Our results indicate AF microRNAs have potential as a diagnostic and prognostic biomarker in TTTS. The top microRNAs have previously demonstrated roles in angiogenesis, cardiomyocyte stress response and hypertrophy. Further studies of the mechanism of actions and potential targets is warranted.

A Big Role for microRNAs in Gestational Diabetes Mellitus

Maternal diabetes is associated with pregnancy complications and poses a serious health risk to both mother and child. Growing evidence suggests that pregnancy complications are more frequent and severe in pregnant women with pregestational type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) compared to women with gestational diabetes mellitus (GDM). Elucidating the pathophysiological mechanisms that underlie the different types of maternal diabetes may lead to targeted strategies to prevent or reduce pregnancy complications. In recent years, microRNAs (miRNAs), one of the most common epigenetic mechanisms, have emerged as key players in the pathophysiology of pregnancy-related disorders including diabetes. This review aims to provide an update on the status of miRNA profiling in pregnancies complicated by maternal diabetes. Four databases, Pubmed, Web of Science, EBSCOhost, and Scopus were searched to identify studies that profiled miRNAs during maternal diabetes. A total of 1800 articles were identified, of which 53 are included in this review. All studies profiled miRNAs during GDM, with no studies on miRNA profiling during pregestational T1DM and T2DM identified. Studies on GDM were mainly focused on the potential of miRNAs to serve as predictive or diagnostic biomarkers. This review highlights the lack of miRNA profiling in pregnancies complicated by T1DM and T2DM and identifies the need for miRNA profiling in all types of maternal diabetes. Such studies could contribute to our understanding of the mechanisms that link maternal diabetes type with pregnancy complications.

Extracellular vesicle-enriched miRNA profiles across pregnancy in the MADRES cohort

MicroRNA (miRNA) circulating in plasma have been proposed as biomarkers for a variety of conditions and diseases, including complications during pregnancy. During pregnancy, about 15-25% of maternal plasma exosomes, a small size-class of EVs, are hypothesized to originate in the placenta, and may play a role in communication between the fetus and mother. However, few studies have addressed changes in miRNA over the course of pregnancy with repeated measures, nor focused on diverse populations. We describe changes in miRNA in early and late pregnancy from the MADRES cohort of primarily low-income Hispanic women based in Los Angeles, CA. miRNA derived from extracellular-vesicles (EVs) were isolated from maternal blood plasma samples collected in early and late pregnancy. In this study, we identified 64 of 130 detectable miRNA which significantly increased with gestational age at the time of collection (GA), and 26 which decreased with GA. Possible fetal sex-specific associations were observed for 30 of these 90 significant miRNA. Predicted gene targets for miRNA significantly associated with GA were identified using MirDIP and were found to be enriched for Gene Ontology categories that included energetic and metabolic processes but were underrepresented in immune-related categories. Circulating EV-associated miRNA during pregnancy are likely important for maternal-fetal communication, and may play roles in supporting and maintaining a healthy pregnancy, given the changing needs of the fetus.

A Data-Driven Review of the Genetic Factors of Pregnancy Complications

Over the recent years, many advances have been made in the research of the genetic factors of pregnancy complications. In this work, we use publicly available data repositories, such as the National Human Genome Research Institute GWAS Catalog, HuGE Navigator, and the UK Biobank genetic and phenotypic dataset to gain insights into molecular pathways and individual genes behind a set of pregnancy-related traits, including the most studied ones—preeclampsia, gestational diabetes, preterm birth, and placental abruption. Using both HuGE and GWAS Catalog data, we confirm that immune system and, in particular, T-cell related pathways are one of the most important drivers of pregnancy-related traits. Pathway analysis of the data reveals that cell adhesion and matrisome-related genes are also commonly involved in pregnancy pathologies. We also find a large role of metabolic factors that affect not only gestational diabetes, but also the other traits. These shared metabolic genes include IGF2, PPARG, and NOS3. We further discover that the published genetic associations are poorly replicated in the independent UK Biobank cohort. Nevertheless, we find novel genome-wide associations with pregnancy-related traits for the FBLN7, STK32B, and ACTR3B genes, and replicate the effects of the KAZN and TLE1 genes, with the latter being the only gene identified across all data resources. Overall, our analysis highlights central molecular pathways for pregnancy-related traits, and suggests a need to use more accurate and sophisticated association analysis strategies to robustly identify genetic risk factors for pregnancy complications.

Identification of microRNA signatures in umbilical cord blood associated with maternal characteristics

Background

Umbilical cord blood could serve as useful source of blood markers enabling more efficient and reliable prenatal and neonatal diagnostics. MicroRNAs (miRNAs) are ubiquitous in body fluids where they were used for detecting and monitoring various physiological and pathological conditions. In this descriptive study, we aimed to identify changes in miRNA expression profiles associated with basic maternal somatic and epidemiological characteristics.

Methods

Study is based on 24 mothers from the Pilot phase of CELSPAC: TNG (Central European Longitudinal Studies of Parents and Children: The Next Generation) study. Cord blood was collected at time of delivery and global miRNA profiling was performed using microRNA Ready-to-use PCR Human Panel I+II TaqMan microarrays. Expression profiles were statistically evaluated in relation to maternal age, BMI, pregnancy weight gain, blood type, Rh factor status, allergies during pregnancy, addictive substance abuse and smoking status.

Results

We analyzed expression of 752 human mature miRNAs in 24 samples of umbilical cord blood. For all maternal characteristics tested we described a specific signature of significantly deregulated miRNAs (P < 0.05). Analysis revealed seven miRNA associated with maternal age (three increased and four decreased in women younger than 35 years), 14 miRNAs associated with BMI status (five miRNAs increased and nine miRNAs decreased in women with BMI > 25) and nine miRNAs associated with maternal weight gain during pregnancy (eight miRNAs increased, and one miRNA decreased in women with weight gain < 12 kg). Additionally, 17 miRNAs correlated to blood type (two miRNAs decreased in blood type A, 11 increased in blood type B, two miRNAs increased in blood type AB and two miRNAs increased in blood type 0) and 17 miRNAs to Rh status of mother. We also detected seven miRNAs deregulated in umbilical cord blood of women with allergy (four increased and three decreased in women with allergy), four miRNAs associated to addictive substance abuse status (two up- and two downregulated in women with addictive substance abuse) and eight miRNAs associated with maternal cigarette smoking during pregnancy.

Conclusions

We successfully described differences in miRNA profiles in umbilical cord blood associated with basic characteristics connected with mother. Our data suggest that miRNAs in umbilical cord blood are detectable and associated with a wide range of maternal characteristics. These results indicate that miRNAs could potentially serve, and should be studied, as biomarkers for screening and diagnosis of pregnancy-associated complications and pathologies.

Distinct communication patterns of trophoblastic miRNA among the maternal-placental-fetal compartments

INTRODUCTION

The placenta produces microRNAs (miRNA) that may traffic to the maternal or fetal compartments and influence the physiology of pregnancy. The trafficking patterns of miRNA expressed from the large human chromosome 19 and chromosome 14 clusters (C19MC and C14MC), remains unclear. We interrogated the cross-sectional landscape of miRNA expression within the human placenta, fetal and maternal plasma to elucidate miRNA trafficking. We hypothesized that C19MC and C14MC miRNAs have similar expression patterns across the maternal-fetal compartments.

METHODS

Placental biopsies, maternal and fetal venous plasma were collected from 25 pregnancies, and RNA was quantified using next generation sequencing. We identified expression and correlations differences among the compartments, and uncovered distinct miRNA expression patterns using consensus clustering.

RESULTS

We found that the placenta exhibits the highest total abundance, average miRNA expression and lowest variance of both C19MC and C14MC miRNAs. The C19MC miRNAs had a comparable expression and variance in fetal and maternal plasma and higher expression in the placenta. In contrast, the C14MC miRNAs had comparable expression between the placenta and fetal plasma, which was higher than the maternal plasma. We also identified 5 distinct groups of trophoblastic miRNAs with different expression patterns in each compartment.

DISCUSSION

This is the first comprehensive analysis of C19MC and C14MC miRNA expression patterns in the human placental, maternal and fetal compartments. Our findings suggest that C14MC miRNAs are produced by both the fetus and placenta, but C19MC miRNAs are produced primarily in the placenta and are trafficked to the fetal and maternal compartments.

Reference values for circulating pregnancy-associated microRNAs in maternal plasma and their clinical usefulness in uncomplicated pregnancy and hypertensive disorder of pregnancy

AIM

The aim of this study was to establish the reference values for circulating pregnancy-associated placental microRNAs in maternal plasma and clarify their clinical significance in patients with hypertensive disorder of pregnancy (HDP).

METHODS

Blood samples were collected from 145 women with uncomplicated pregnancies (24, 26, 31 and 32 women at 12, 23, 30 and 36 weeks of gestation, respectively, and 32 women 1 day after delivery). Plasma concentrations of pregnancy-associated placental microRNAs (miR-515-3p, miR-517a, miR-517c and miR-518b) were measured by quantitative real-time reverse-transcription polymerase chain reaction. Reference values for each microRNA were determined by the line of best fit and 95% prediction interval and are expressed as logarithmic transformation. To clarify the clinical significance of these reference values, we measured the plasma concentrations of pregnancy-associated microRNAs in a different population comprising 33 pregnant women with HDP and 44 women with uncomplicated pregnancies.

RESULTS

Reference values for circulating pregnancy-associated placental microRNAs on chromosome 19 miRNA clusters showed an increasing tendency as pregnancy progressed and decreased significantly 1 day after delivery (P < 0.05). The sensitivity and specificity of each reference value were 57.6% and 93.2% for miR-515-3p, 63.6% and 75.0% for miR-517a, 75.8% and 79.5% for miR-517c and 63.6% and 75.0% for miR-518b, respectively. The positive and negative predictive values of each reference value were 86.4% and 74.5% for miR-515-3p, 65.6% and 73.3% for miR-517a, 73.5% and 81.4% for miR-517c and 65.6% and 73.3% for miR-518b, respectively.

CONCLUSION

Establishing the reference values for circulating pregnancy-associated placental microRNAs in maternal plasma could be useful for the evaluation of HDP.

MicroRNAs in Pregnancy and Gestational Diabetes Mellitus: Emerging Role in Maternal Metabolic Regulation

PURPOSE OF THE REVIEW

This review focuses on the recent emergence of microRNAs (miRNAs) as metabolic and developmental regulators in pregnancy and their role in the development of gestational diabetes mellitus (GDM). MiRNAs are short and stable RNA sequences that repress protein synthesis through interference with messenger RNA translation.

RECENT FINDINGS

The placenta produces numerous miRNAs with some of them being released in the maternal circulation. These miRNA genes are encoded into specific clusters and expressed preferentially by placental cells, in a time-dependent manner. They were shown to be dysregulated in plasma and placenta from women suffering from GDM and associated with pregnancy and birth-related outcomes. The discovery of pregnancy-related miRNAs and their respective characterization will provide us with important information as to their function in maternal and placental metabolic regulation. More studies are needed to determine whether they will be useful for early screening of GDM.

Feasibility of placenta-derived mesenchymal stem cells as a tool for studying pregnancy-related disorders

The cellular and molecular mechanisms responsible for pregnancy-related disorders remain unclear. We investigated the feasibility of using placenta-derived mesenchymal stem cells (MSCs) as a tool to study such pregnancy-related disorders. We isolated and expanded adequate numbers of cells with characteristic features of MSCs from the chorionic plate (CP-MSCs), chorionic villi (CV-MSCs), and decidua basalis (DB-MSCs) of human term placental tissues. All placenta-derived MSCs expressed pregnancy-associated C14MC microRNA (miRNA) (miR-323-3p). Interestingly, the placenta-specific C19MC miRNAs (miR-518b and miR517a) were clearly expressed in CP-MSCs and CV-MSCs of foetal origin, but were barely expressed in DB-MSCs of maternal origin. Furthermore, expression levels of placenta-specific C19MC miRNAs in CV-MSCs remained stable during the ex vivo expansion process and across different pregnancy phases (first trimester versus third trimester). High-efficiency siRNA transfection was confirmed in twice-passaged CV-MSCs with little toxicity, and microarray analysis was used to screen for miR-518b target genes. Placenta-derived MSCs, especially CV-MSCs, are a potential tool for investigating the role of placental miRNAs in pregnancy-related disorders.