Diagnostic potential for miRNAs as biomarkers for pregnancy-specific diseases

MicroRNA expression profiles and networks in placentas complicated with selective intrauterine growth restriction

The microRNA (miRNA) profiles of placentas complicated with selective intrauterine growth restriction (sIUGR) are unknown. In the present study, the sIUGR‑associated placental miRNA expression was investigated using microarray and confirmatory reverse transcriptase‑quantitative polymerase chain reaction studies. Placenta samples around the individual insertion region for each umbilical cord were collected from monochorionic twins complicated with (n=17) or without sIUGR (control, n=16). miRNA profile analysis was performed on two sIUGR cases and one control using an Affymetrix microRNA 4.0 Array system. A total of 14 miRNAs were identified to be specifically differentially expressed (7 upregulated and 7 downregulated) among larger twins of sIUGR cases compared with smaller twins of sIUGR cases. The target genes of the identified miRNAs participate in organ size, cell differentiation, cell proliferation and migration. In addition, according to the miRNA‑pathway network analysis, key miRNAs and pathways (transforming growth factor‑β, mitogen‑activated protein kinase and Wnt) were identified to be associated with the pathogenesis of sIUGR. To the best of our knowledge, the results of the current study have provided the most complete miRNA profiles and the most detailed miRNA regulatory networks of placental tissues complicated with sIUGR.

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.

Mother's Pre-pregnancy BMI and Placental Candidate miRNAs: Findings from the ENVIRONAGE Birth Cohort

There is increasing evidence that the predisposition for development of chronic diseases arises at the earliest times of life. In this context, maternal pre-pregnancy weight might modify fetal metabolism and the child’s predisposition to develop disease later in life. The aim of this study is to investigate the association between maternal pre-pregnancy body mass index (BMI) and miRNA alterations in placental tissue at birth. In 211 mother-newborn pairs from the ENVIRONAGE birth cohort, we assessed placental expression of seven miRNAs important in crucial cellular processes implicated in adipogenesis and/or obesity. Multiple linear regression models were used to address the associations between pre-pregnancy BMI and placental candidate miRNA expression. Maternal pre-pregnancy BMI averaged (±SD) 23.9 (±4.1) kg/m². In newborn girls (not in boys) placental miR-20a, miR-34a and miR-222 expression was lower with higher maternal pre-pregnancy BMI. In addition, the association between maternal pre-pregnancy BMI and placental expression of these miRNAs in girls was modified by gestational weight gain. The lower expression of these miRNAs in placenta in association with pre-pregnancy BMI, was only evident in mothers with low weight gain (<14 kg). The placental expression of miR-20a, miR-34a, miR-146a, miR-210 and miR-222 may provide a sex-specific basis for epigenetic effects of pre-pregnancy BMI.

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.

Peculiarities of placental microRNA expression in pregnancies complicated by gestational diabetes mellitus and preeclampsia

The aim of study was to determine feasible changes of placental miRNAs expression profiles revealed by next generation sequencing (NGS) in pregnancies with GDM complicated or not with PE. Out of 27 miRNAs, studied expression was significantly different (FDR < 0.05) only for his-miR-45a. Comparative analysis of revealed reliable differences in expression of hsa-miR-4532 (p < 0.0001, FDR = 0.0008), hsa-miR-34c-5p (p < 0.0001, FDR = 0.0083), and hsa-miR-193b-5p (p < 0.0001, FDR = 0.0139) in pregnancy complicated by PE, without of GDM. The present results suggest that GDM and PE are associated with specific alterations in the placental miRNA expression profiles. Further studies are needed to verify the role of these microRNA in molecular mechanisms underlying GDM and PE pathogenesis.

miR-27a and miR-449b polymorphisms associated with a risk of idiopathic recurrent pregnancy loss

Objective

MicroRNAs (miRNAs) regulate gene expression during the peri-implantation period. The purpose of this study was to investigate whether genetic polymorphisms in the four miRNAs associated with fetal or placental development play roles in the development of idiopathic recurrent pregnancy loss (RPL) in Korean females.

Study design

A case-control study involving 225 controls and 387 women with at least two consecutively recurrent pregnancy losses between 1999 and 2012 was performed. The genotypes of the four miRNA polymorphisms, including miR-27a rs895819, miR-423 rs6505162, miR-449b rs10061133, and miR-605 rs2043556, were analyzed by the polymerase chain reaction-restriction fragment length polymorphism assay. Odds ratios and 95% confidence intervals were estimated using multivariate analyses after maternal age adjustments. The relationships between each of the four microRNA genotypes and each of the six clinical parameters of the RPL patients (plasma homocysteine and folate levels, natural killer cell number, platelet count, prothrombin time, and, activated partial thromboplastin time) were analyzed using multiple linear regression analyses.

Results

Our results suggest that weak associations between decreased RPL risk and the genotypes of miR-27a (AG and AG+GG), combination genotype of miR-27a/miR-423 (AG/GC), and haplotypes of miR-27a/miR-423/miR-449b/miR-605 (G-C-A-G) and miR-27a/miR-449b/miR-605 (G-A-G), whereas weak associations between increased RPL risk and genotypes of miR-449b (GG and AG+GG), combination genotypes of miR-423/miR-449b (CC/GG and CA/AG), miR-449b/miR-605 (AG/AG), haplotypes of miR-27a/miR-423/miR-449b/miR-605 (A-C-G-A, A-A-A-G, and G-C-G-G), miR-27a/miR-423/miR-449b (A-C-G), miR-27a/miR-449b/miR-605 (A-A-G, A-G-A, and G-G-G), miR-423/miR-449b/miR-605 (C-G-G and A-A-G), and miR-423/miR-449b (C-G and A-A). The genotypes of miR-27a (AG and AG+GG) also showed significant contributions to the prediction of folate levels in RPL patients.

Conclusions

The study showed associations between miRNA polymorphisms (miR-27a rs895819 and miR-449b rs10061133) and RPL development, and between the miRNA polymorphism (miR-27a rs895819) and plasma folate levels.

Blood laboratory testing for early prediction of preeclampsia: chasing the finish line or at the starting blocks?

Preeclampsia (PE) affects 2-8% of pregnancies worldwide, thus representing an important cause of maternal and neonatal morbidity, up to death. Many studies have been designed to identify putative biomarkers for accurate and timely diagnosing PE, but only some of them were focused on specific and sensitive biomarkers for early prediction of this life-threatening condition. In particular, some prospective studies aimed to investigate the predictive role of circulating biomarkers before 20 weeks of gestation in the general pregnant population yielded conflicting results. This article is hence centered on results obtained in studies investigating the predictive performances of angiogenic, anti-angiogenic, inflammatory, endocrine, and epigenetic biomarkers. The available evidence suggests that angiogenic and anti-angiogenic molecules, in particular the sFlt1:PlGF ratio, may be considered the biomarkers with the best diagnostic performance in the second trimester. However, doubts remain about their use in clinical settings before the 20th gestational week. Even lower evidence is available for other biomarkers, due to the fact that some positive results have not been confirmed in ensuing investigations, whereas unresolved analytical issues still contribute to make their clinical reliability rather questionable. Differential expression of microRNAs seems also a promising evidence for early prediction of PE, but additional research and well-designed prospective studies are needed to identify and validate routine predictive tests. KEY MESSAGES Preeclampsia affects 2-8% of pregnant women worldwide, thus remaining one of the leading causes of maternal and neonatal morbidity and mortality. Several studies have investigated the predictive role of circulating biomarkers before 20th week of gestation with conflicting results. Additional research and well-designed prospective studies are needed to identify and validate predictive tests in clinical practice.

Evaluation of circulating miRNAs during late pregnancy in the mare

MicroRNAs (miRNAs) are small, non-coding RNAs which are produced throughout the body. Individual tissues tend to have a specific expression profile and excrete many of these miRNAs into circulation. These circulating miRNAs may be diagnostically valuable biomarkers for assessing the presence of disease while minimizing invasive testing. In women, numerous circulating miRNAs have been identified which change significantly during pregnancy-related complications (e.g. chorioamnionitis, eclampsia, recurrent pregnancy loss); however, no prior work has been done in this area in the horse. To identify pregnancy-specific miRNAs, we collected serial whole blood samples in pregnant mares at 8, 9, 10 m of gestation and post-partum, as well as from non-pregnant (diestrous) mares. In total, we evaluated a panel of 178 miRNAs using qPCR, eventually identifying five miRNAs of interest. One miRNA (miR-374b) was differentially regulated through late gestation and four miRNAs (miR-454, miR-133b, miR-486-5p and miR-204b) were differentially regulated between the pregnant and non-pregnant samples. We were able to identify putative targets for the differentially regulated miRNAs using two separate target prediction programs, miRDB and Ingenuity Pathway Analysis. The targets for the miRNAs differentially regulated during pregnancy were predicted to be involved in signaling pathways such as the STAT3 pathway and PI3/AKT signaling pathway, as well as more endocrine-based pathways, including the GnRH, prolactin and insulin signaling pathways. In summary, this study provides novel information about the changes occurring in circulating miRNAs during normal pregnancy, as well as attempting to predict the biological effects induced by these miRNAs.

Review: Placental derived biomarkers of pregnancy disorders

Pregnancy is one of the greatest physiological challenges that a women can experience. The physiological adaptations that accompany pregnancy may increase the risk of developing a number of disorders that can lead to both acute and chronic physiological outcomes. In addition, fetal development may be impaired and, if the fetus survives, the child may be at an increased risk of disease throughout life. Pregnancy disorders are poorly predicted by traditional risk factors and maternal history alone. The identification of biomarkers that can predict incidence and severity of disease would allow for improved and targeted prophylactic therapies to prevent adverse maternal and fetal outcomes. Many of these pregnancy disorders, including preeclampsia, intrauterine growth restriction, gestational diabetes mellitus and preterm birth are known to be regulated at least in part by poor trophoblast invasion and/or dysregulated placental function. Cellular stress within the placenta increases the release of a number of factors into the maternal circulation. While many of these factors minimally impact maternal biology, others affect key physiological systems and contribute to disease. Importantly, these factors may be detected in physiological fluids and have predictive capacity making them ideal candidates as biomarkers of pregnancy disorders. This review will discuss what is known about these placental derived biomarkers of pregnancy disorders and highlight potential clinical opportunities for disease prediction and diagnosis.

Assessment of six commercial plasma small RNA isolation kits using qRT-PCR and electrophoretic separation: higher recovery of microRNA following ultracentrifugation

Growing interest in blood-borne microRNAs (miRNAs) as biomarkers has led to the introduction of a number of commercial kits for isolating small RNAs from plasma/serum. We sought to compare the efficacy of six such kits in isolating miRNAs from either whole plasma or a plasma-derived ultracentrifugation (UC) fraction from 2 healthy volunteers with some of the results being validated in 10 additional subjects. To assess the overall yield and concentration of isolated small RNAs, we measured the levels of one spiked-in and four endogenous miRNAs by quantitative reverse transcription and polymerase chain reaction (qRT-PCR). We also tested the performance of the Agilent Bioanalyzer small RNA assay with these RNA samples. Additionally, we tested the effects of hemolysis on measured miRNA levels in whole plasma and in the UC fraction. Both the efficiency of RNA isolation and the relative levels of specific miRNAs in different samples varied considerably between the tested extraction methods. Of all kits tested, the QIAGEN miRNeasy kits (Mini and Serum/Plasma kits) and the Macherey-Nagel NucleoSpin kit produced the highest RNA yields. The QIAGEN Exo kit produced lesser yields than what could be extracted from the UC fraction using the QIAGEN miRNeasy kits and the Macherey-Nagel NucleoSpin kit. Bioanalyzer results showed an average correlation of R² = 0.8 with endogenous miRNA qRT-PCR results, for sample concentrations >40 pg/µl. The levels of the endogenous miRNAs measured in the two volunteer samples were compared with those in a larger group of subjects (n = 10) and found to be typical. Our comparison favors the use of the QIAGEN Serum/Plasma kit and the Macherey-Nagel NucleoSpin kit for plasma miRNA applications. Furthermore, extraction of miRNAs from the UC fraction results in higher yield than extraction from whole plasma.

Dysregulated circulating miRNAs in preeclampsia

Preeclampsia (PE) is a pregnancy-related disease with potentially severe consequences with respect to foeto-maternal morbidity and mortality. However, the molecular pathogenesis of PE remains largely unknown. Recent reports have shown that microRNAs (miRNAs or miRs) may play important roles in the development of PE. Analysing the miRNAs in sera from preeclamptic women may improve our understanding of the pathophysiological mechanisms of the disease. The aim of this retrospective study was to identify whether circulating miRNAs were differentially expressed in PE patients compared with controls. Serum samples from 23 women who developed PE were compared with samples from 44 pregnant controls. Seventeen circulating miRNAs previously described in PE were chosen for evaluation of their expression by reverse transcription quantitative polymerase chain reaction (RT-qPCR). In the maternal serum, the miR-210-3p, miR-210-5p, miR-1233-3p, and miR-574-5p levels were found to be significantly higher in the PE patients than in the controls (P<0.05). Using a logistic regression model, we evaluated the discriminant power of those differentially expressed miRNAs, and the combination of miR-210-5p and miR-574-5p yielded an area under the curve of 0.7223 for discriminating PE patients from the controls. In conclusion, the fact that four circulating miRNAs (miR-210-3p, miR-210-5p, miR-1233-3p, and miR-574-5p) were differentially expressed in the sera of women who developed PE compared with controls confirms the possible pathophysiological role of miRNAs in PE.

Placental microRNA Expression Is Not Altered by Maternal Obesity and Fetal Overgrowth

Objective The epigenetic mechanisms underlying fetal metabolic programming are poorly understood. We studied whether obesity is associated with alterations in placental miRNA expression. Study Design A cross-sectional study was performed, including (1) normal-weight women (BMI 20-24.9 kg/m²) and normal-birth-weight (BW) infants (2,700-3,500 g) (n = 20), (2) normal-weight and macrosomic infants (BW ≥ 4,000 g) (n = 10), (3) obese (BMI ≥ 35 kg/m²) and normal BW infants (n = 16), and (4) obese and macrosomic infants (n = 10). All had term deliveries (37-41 weeks) and normal glucose tolerance (1 hour GCT < 7.2 mmol/L [130 mg/dL]). The expression of 5,639 placental miRNAs was assessed using miRNA microarray. Differential miRNA expression was determined using two-way ANOVA and pairwise contrasts, with the Benjamini-Hochberg (BH) correction. MiRNAs with Z-scores ≥ 2 and false discovery rate (FDR) < 20% were considered significant. Results Principal components analysis demonstrated similar global miRNA expression profiles among groups. Of 5,639 miRNAs, only 5 were significantly different between obese and controls, which were not validated by quantitative polymerase reaction. Conclusion There was no difference in placental miRNA expression associated with obesity or overgrowth. Aberrant placental miRNA expression is an unlikely mechanism underlying fetal metabolic programming related to maternal obesity.

Predictive value of miR-210 as a novel biomarker for pre-eclampsia: a systematic review protocol

INTRODUCTION

Pre-eclampsia (PE) is a serious condition affecting 3-5% of all pregnancies worldwide. However, underlying molecular pathogenesis of this disease has largely remained unknown. Recently, several studies have indicated the possibility role of microRNAs, especially miR-210, in the aetiology of PE. The aim of this systematic review is to assess the possible role of miR-210 as a novel biomarker for the prediction of PE.

METHODS AND ANALYSIS

Using a combination of mesh terms 'preeclampsia', 'microRNA' and their equivalents, an electronic search will be performed for all observational studies (cross sectional, case-control and cohort) in PubMed, Web of Science, Scopus, Embase, Cochrane, LILACS and OvidSP MEDLINE from January 2005 to December 2015. Furthermore, other sources are searched, including grey literature, reference lists of relevant primary studies as well as key journals. Study selection, data extraction and quality assessment of studies will be performed independently by 2 reviewers, and any disagreement will be resolved by consensus. If sufficient data are available, it will be combined by either fixed or random effects models. We will investigate the source)s(and degree of heterogeneity using 'Heterogeneity χ2' and I2. Heterogeneity would be investigated through either subgroup analysis or metaregression. Stata V.11.1 will be used for data analysis.

ETHICS AND DISSEMINATION

The results of this study are disseminated in peer-reviewed journal articles and academic presentations. Formal ethical approval is not required, since the secondary data will be collected.

TRIAL REGISTRATION NUMBER

CRD42015032345.

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

The aim of this study was to clarify the association between circulating pregnancy-associated, placenta-specific microRNAs (miRNAs) in maternal plasma and placental abruption. All samples were obtained after receiving written informed consent, and the study protocol was approved by the institutional review board. Maternal blood samples (7 mL) were obtained at 25 to 40 weeks of gestation from 15 cases of placental abruption (placental abruption group) and from 24 cases of uncomplicated pregnancies (uncomplicated pregnancy group). The plasma concentrations of pregnancy-associated, placenta-specific miRNAs (miR-515-3p, -517a, -517c, and -518b) were measured by quantitative real-time reverse transcription-polymerase chain reaction. There were no significant differences in clinical characteristics between the 2 groups. The median concentration of plasma cell-free miR-517c in the placental abruption group was 21 672.2 copies/mL, whereas that in the uncomplicated pregnancy group was 13 452.0 copies/mL (Mann-Whitney U test, P = .047). Receiver operating characteristic curve analysis revealed that plasma cell-free miR-517c levels discriminated placental abruption from uncomplicated pregnancy with an area under the curve of 0.692. When a cutoff negative/positive value of 15 669.6 copies/mL was selected, the sensitivity and specificity were 73.3% and 62.5%, respectively. In addition, the positive and negative predictive values were 55.0% and 78.9%, respectively. Plasma cell-free miR-517a and miR-517c levels in the large abruption (degree of abruption ≥50% of placenta) group were significantly higher than in the small abruption (<50%) group ( P = .03 for both miRNAs). In conclusion, the circulating level of cell-free miR-517c in maternal plasma was increased as a consequence of placental abruption and may be a potential biomedical marker for placental abruption.

Maternal plasma antioxidant status in the first trimester of pregnancy and development of obstetric complications

INTRODUCTION

Oxidative stress is present in pregnancy complications. However, it is unknown if early maternal antioxidant status could influence later development of complications. The use of assisted reproduction techniques (ART) is rising due to the delay of first pregnancy and there is scarce information on its influence on oxidative balance.

OBJECTIVE

To assess the possible relationship between maternal plasma antioxidant status in first trimester of gestation with later development of pregnancy complications, evaluating the influence of ART and nutrition.

METHODS

Plasma from 98 healthy pregnant women was obtained at week 10, nutrition questionnaires filled and women were followed until delivery. We evaluated biomarkers of oxidative damage (carbonyls, malondialdehyde-MDA), antioxidants (thiols, reduced glutathione, phenolic compounds, catalase and superoxide dismutase activities) by spectrophotometry/fluorimetry and melatonin (ELISA). Antioxidant status score (Antiox-S) was calculated as the computation of antioxidants. Diet-antioxidants relationship was evaluated through multiple correspondence analysis.

RESULTS

Melatonin and carbonyls exhibited a negative correlation. No difference in oxidative damage was found between groups, but Antiox-S was significantly lower in women who developed complications. No differences in oxidative damage or Antiox-S were found between ART and no-ART pregnancies. High consumption of foods of vegetable origin cluster with high plasma levels of phenolic compounds and with high Antiox-S.

CONCLUSIONS

In early normal gestation, low plasma antioxidant status, assessed through a global score, associates with later development of pregnancy complications. Larger population studies could help to determine the value of Antiox-S as predictive tool and the relevance of nutrition on maternal antioxidant status.

Circulating MicroRNAs as Potential Molecular Biomarkers in Pathophysiological Evolution of Pregnancy

MicroRNAs represent nonprotein coding small RNA molecules that are very stable to degradation and responsible for gene silencing in most eukaryotic cells. Increased evidence has been accumulating over the years about their potential value as biomarkers for several diseases. MicroRNAs were predicted to be involved in nearly all biological processes from development to oncogenesis. In this review, we address the importance of circulating microRNAs in different conditions associated with pregnancy starting with the implantation period to preeclampsia and we shortly describe the correlation between placental circulating miRNAs and pregnancy status. We also discuss the importance of microRNAs in recurrent abortion and ectopic pregnancy.

MicroRNA-141 is upregulated in preeclamptic placentae and regulates trophoblast invasion and intercellular communication

Preeclampsia (PE) is one of the leading causes of maternal and perinatal morbidity and mortality worldwide. Abnormal expression of microRNAs (miRNAs) occurs in several pregnancy diseases including PE. Placental trophoblast cells express a specific set of miRNAs which changes during pregnancy. These miRNAs can be released within extracellular vesicles (EVs) and mediate intercellular communication. miR-141 is a pregnancy-related miRNA which is expressed by trophoblast cells at increased levels in maternal plasma in the third trimester. We hypothesize that miR-141 is abnormally expressed in PE placentae, controls trophoblast, and immune cell functions and is involved in the intercellular communication between fetal trophoblast and maternal immune cells. Expression of miR-141 was analyzed by quantitative real-time PCR (qPCR) in normal and preeclamptic placentae and in 2 different trophoblastic cell lines, JEG-3 and HTR-8/SVneo. Changes in JEG-3 and HTR-8/SVneo cell proliferation and invasion were investigated after miR-141 inhibition and overexpression by MTS-, BrdU-, and Matrigel assays. EVs from miR-141 transfected cells were isolated from supernatants and characterized by NanoSight analysis and qPCR. Proliferation of Jurkat T cells and invasion of HTR-8/SVneo cells were investigated after treatment with EVs containing different miR-141 levels. miR-141 expression was higher in placentae from PE patients compared with those from normal pregnancies. miR-141 inhibition in trophoblastic cells resulted in decreased cell viability and reduced invasion capability. After transfection with miR-141-mimic, trophoblastic cells secreted EVs with increased miR-141 content. These vesicles did not exert effects on trophoblastic cell invasion but reduced Jurkat T cell proliferation. In conclusion, miR-141 regulates major functions of trophoblastic and immune cells. Trophoblast cells release EVs whose miRNA content can be modified by transfection of origin cells. Furthermore, elevated levels of miR-141 can be transferred from trophoblast to immune cells by release and internalization of EVs suggesting their role in the immune regulation of normal and pathologic pregnancies.

Placental microRNA expression in pregnancies complicated by superimposed pre‑eclampsia on chronic hypertension

Pre-eclampsia (PE) is a complication of pregnancy that affects 5–8% of women after 20 weeks of gestation. It is usually diagnosed based on the de novo onset of hypertension and proteinuria. Preexisting hypertension in women developing PE, also known as superimposed PE on chronic hypertension (SPE), leads to elevated risk of maternal and fetal mortality. PE is associated with an altered microRNA (miRNA) expression pattern in the placenta, suggesting that miRNA deregulation is involved in the pathogenesis of PE. Whether and how the miRNA expression pattern is changed in the SPE placenta remains unclear. The present study analyzed the placental miRNA expression profile in pregnancies complicated by SPE. miRNA expression profiles in SPE and normal placentas were investigated using an Ion Torrent sequencing system. Sequencing data were processed using a comprehensive analysis pipeline for deep miRNA sequencing (CAP-miRSeq). A total of 22 miRNAs were identified to be deregulated in placentas from patients with SPE. They included 16 miRNAs previously known to be associated with PE and 6 novel miRNAs. Among the 6 novel miRNAs, 4 were upregulated (miR-518a, miR-527, miR-518e and miR-4532) and 2 downregulated (miR-98 and miR-135b) in SPE placentas compared with controls. The present results suggest that SPE is associated with specific alterations in the placental miRNA expression pattern, which differ from alterations detected in PE placentas, and therefore, provide novel targets for further investigation of the molecular mechanisms underlying SPE pathogenesis.

Potential role of circulating microRNAs as a biomarker for unexplained recurrent spontaneous abortion

OBJECTIVE

To compare circulating microRNA (miRNA) profiles between unexplained recurrent spontaneous abortion (URSA) and normal early pregnancies (NEP) and to evaluate the potential role of circulating miRNA as a biomarker for URSA.

DESIGN

Laboratory study using human plasma samples.

SETTING

Special hospital and research institutes.

PATIENT(S)

From September 2012 to April 2013, samples of plasma were obtained from 27 URSA patients and 28 NEP patients at 6-10 weeks of gestation at the Department of Reproductive Immunology in Family Planning Special Hospital of Guangdong Province.

INTERVENTION(S)

Differential miRNA profiling analysis of plasma collected from URSA and NEP patients was performed with the use of microarray.

MAIN OUTCOME MEASURE(S)

The circulating miRNA expression profile was assessed by means of microarray and real-time quantitative reverse-transcription polymerase chain reaction (qRT-PCR) analysis.

RESULT(S)

Twenty-five circulating miRNAs were expressed differentially in URSA compared with NEP. Of these, nine were overexpressed and 16 down-regulated. Six differentially expressed circulating miRNAs were selected to validate the microarray results, and qRT-PCR data confirmed the reliability of the microarray results. Further analysis showed that four circulating miRNAs (miR-320b, miR-146b-5p, miR-221-3p, miR-559) were up-regulated. In URSA, one circulating miRNA (miR-101-3p) was down-regulated in other larger scale samples according to qRT-PCR. Based on target gene analysis, we speculate that these circulating miRNAs regulate URSA by targeting immune, apoptosis, and angiogenic gene functions.

CONCLUSION(S)

Circulating microRNAs may be involved in URSA pathogenesis and provide a promising new diagnostic biomarker for URSA.

A Dormant Microbial Component in the Development of Preeclampsia

Preeclampsia (PE) is a complex, multisystem disorder that remains a leading cause of morbidity and mortality in pregnancy. Four main classes of dysregulation accompany PE and are widely considered to contribute to its severity. These are abnormal trophoblast invasion of the placenta, anti-angiogenic responses, oxidative stress, and inflammation. What is lacking, however, is an explanation of how these themselves are caused. We here develop the unifying idea, and the considerable evidence for it, that the originating cause of PE (and of the four classes of dysregulation) is, in fact, microbial infection, that most such microbes are dormant and hence resist detection by conventional (replication-dependent) microbiology, and that by occasional resuscitation and growth it is they that are responsible for all the observable sequelae, including the continuing, chronic inflammation. In particular, bacterial products such as lipopolysaccharide (LPS), also known as endotoxin, are well known as highly inflammagenic and stimulate an innate (and possibly trained) immune response that exacerbates the inflammation further. The known need of microbes for free iron can explain the iron dysregulation that accompanies PE. We describe the main routes of infection (gut, oral, and urinary tract infection) and the regularly observed presence of microbes in placental and other tissues in PE. Every known proteomic biomarker of "preeclampsia" that we assessed has, in fact, also been shown to be raised in response to infection. An infectious component to PE fulfills the Bradford Hill criteria for ascribing a disease to an environmental cause and suggests a number of treatments, some of which have, in fact, been shown to be successful. PE was classically referred to as endotoxemia or toxemia of pregnancy, and it is ironic that it seems that LPS and other microbial endotoxins really are involved. Overall, the recognition of an infectious component in the etiology of PE mirrors that for ulcers and other diseases that were previously considered to lack one.

AngiomiRs: Potential Biomarkers of Pregnancy's Vascular Pathologies

In recent years, microRNAs (miRNAs) have been the focus of research for their role in posttranscriptional regulation and as potential biomarkers of risk for disease development. Their identification in specific physiological processes, like angiogenesis, a key pathway in placental vascular development in pregnancy, suggests an important role of miRNAs that regulate angiogenesis (angiomiRs). Many complications of pregnancy have in common placental vascular alterations, involving an imbalance in the angiogenesis process in the development of conditions such as preeclampsia, intrauterine growth restriction, and gestational diabetes, complications with the highest rates of morbimortality in pregnancy. Many studies have identified angiomiRs with differential expression profiles in each of these diseases; however, this evidence requires further studies focused on evaluating their potential as biomarkers of risk for the angiomiRs detected, to establish correlations between placental tissue and serum/plasma expression profiles. Therefore, the objective of this review is to highlight the best angiomiRs detected in placental tissue and serum/plasma in each of these three pathologies to show the current data available for potential biomarkers and to propose future research strategies on this topic.

MicroRNAs in placental health and disease

MicroRNAs (miRNAs) constitute a large family of small noncoding RNAs that are encoded by the genomes of most organisms. They regulate gene expression through posttranscriptional mechanisms to attenuate protein output in various genetic networks. The discovery of miRNAs has transformed our understanding of gene regulation and sparked intense efforts intended to harness their potential as diagnostic markers and therapeutic tools. Over the last decade, a flurry of studies has shed light on placental miRNAs but has also raised many questions regarding the scope of their biologic action. Moreover, the recognition that miRNAs of placental origin are released continually in the maternal circulation throughout pregnancy suggested that circulating miRNAs might serve as biomarkers for placental function during pregnancy. Although this generated much enthusiasm, recently recognized challenges have delayed the application of miRNA-based biomarkers and therapeutics in clinical practice. In this review, we summarize key findings in the field and discuss current knowledge related to miRNAs in the context of placental biology.

The omniscient placenta: Metabolic and epigenetic regulation of fetal programming

Fetal development could be considered a sensitive period wherein exogenous insults and changes to the maternal milieu can have long-term impacts on developmental programming. The placenta provides the fetus with protection and necessary nutrients for growth, and responds to maternal cues and changes in nutrient signaling through multiple epigenetic mechanisms. The X-linked enzyme O-linked-N-acetylglucosamine transferase (OGT) acts as a nutrient sensor that modifies numerous proteins to alter various cellular signals, including major epigenetic processes. This review describes epigenetic alterations in the placenta in response to insults during pregnancy, the potential links of OGT as a nutrient sensor to placental epigenetics, and the implications of placental epigenetics in long-term neurodevelopmental programming. We describe the role of placental OGT in the sex-specific programming of hypothalamic-pituitary-adrenal (HPA) axis programming deficits by early prenatal stress as an example of how placental signaling can have long-term effects on neurodevelopment.

Noninvasive nucleic acid-based approaches to monitor placental health and predict pregnancy-related complications

During pregnancy, the placenta releases a variety of nucleic acids (including deoxyribonucleic acid, messenger ribonucleic acid, or microribonucleic acids) either as a result of cell turnover or as an active messaging system between the placenta and cells in the maternal body. The profile of released nucleic acids changes with the gestational age and has been associated with maternal and fetal parameters. It also can directly reflect pathological changes in the placenta. Nucleic acids may therefore provide a rich source of novel biomarkers for the prediction of pregnancy complications. However, their utility in the clinical setting depends, first, on overcoming some technical considerations in their quantification, and, second, on developing a better understanding of the factors that influence their function and abundance.

The Expression Pattern of MicroRNAs and the Associated Pathways Involved in the Development of Porcine Placental Folds That Contribute to the Expansion of the Exchange Surface Area

The development of the microscopically folded structure of the diffuse epitheliochorial placenta in pigs is important because it expands the surface area for maternal-fetal exchange, resulting in an increase in placental efficiency. To better understand the regulatory mechanisms involved in this process, we characterized miRNA expression profiles in porcine placentas during the initiation and establishment of placental fold development. A total of 42 miRNAs were found to be differentially expressed, and their putative target genes were predicted using four target prediction programs. Following a comparative analysis with published gene expression pattern data obtained from porcine placentas in the corresponding stages of placental fold development, only those genes that were negatively correlated with miRNA expression were retained for further function and pathway enrichment analysis. The results showed that the up-regulated miRNAs were associated mainly with extracellular matrix remodeling and tissue morphogenesis, while the down-regulated miRNAs were related to cell proliferation and signal transduction. Furthermore, we provide evidence that miR-130b may facilitate the expression of HPSE, which has been reported to be a regulator of the folding of the pig placenta, by suppressing the expression of PPARG. In addition, we also reveal that the miRNA-target pairs expressed in the pig placenta may trigger the degradation of the stromal matrix and basement membrane (miR-29a-COL1A2, COL3A1, and LAMC1) and regulate trophoblast epithelial cell adherens junctions (the miR-200 family and miR-205-ZEB2-CDH1) and proliferation (miR-17-92 cluster-HBP1 and ULK1). Taken together, these results indicate that miRNAs and related pathways may have potential roles in porcine placental fold development.

Increased Levels of Cell-Free miR-517a and Decreased Levels of Cell-Free miR-518b in Maternal Plasma Samples From Placenta Previa Pregnancies at 32 Weeks of Gestation

OBJECTIVE

The aim of this study was to clarify the association between placenta previa and circulating levels of cell-free pregnancy-associated placenta-specific microRNAs (miRNAs) in maternal plasma.

METHOD

Twenty singleton pregnancies with placenta previa (placenta previa group) and 26 uncomplicated pregnancies (control group) were recruited. Blood sampling was performed at 32 weeks of gestation, and cesarean delivery in all cases of placenta previa was performed at a mean gestational age of 37 weeks. The maternal plasma concentrations of cell-free pregnancy-associated placenta-specific miRNAs (miR-517a and miR-518b) were measured by absolute quantitative real-time reverse transcription-polymerase chain reaction.

RESULTS

Plasma concentrations of cell-free miR-517a were significantly higher in the placenta previa group than that in the control group (P = .011), while the plasma concentration of cell-free miR-518b was significantly lower in the placenta previa group than that in the control group (P = .004). Plasma concentrations of cell-free miR-517a in placenta previa were significantly higher in placenta previa with alert bleeding later group than those in placenta previa without alert bleeding group or control group (P = .030 or .047, respectively) and correlated with the volume of hemorrhage at delivery (R and P value: .512 and .025).

CONCLUSION

Plasma concentrations of cell-free miR-517a and miR-518b at 32 weeks of gestation were altered in pregnant women with placenta previa, and the circulating level of cell-free miR-517a in placenta previa may be a predictive marker for the risks of alert bleeding later and massive hemorrhage at delivery.

The Function of TrophomiRs and Other MicroRNAs in the Human Placenta

In eutherian organisms, the placenta interfaces the fetal and maternal environments. Located at the placental villous surface, in direct contact with maternal blood, is the trophoblast layer, which mediates the crucial maternal-fetal exchange of gases, nutrients, and waste products, produces hormones that support the pregnancy, and provides immunologic defense. Discovery of microRNAs (miRNAs) and their role in development, differentiation, and homeostatic resilience has increased our understanding of genomic and epigenomic networks that regulate placental function. Moreover, unique miRNA species, which are expressed by human trophoblasts and are termed "trophomiRs," may show specialized functions during normal and pathological pregnancies. Placental miRNAs, packaged within exosomes and other vesicles or bound in protein complexes, are capable of communicating distinctive signals to maternal and/or fetal tissues. Additional research may usher in the use of circulating miRNAs as pregnancy-related disease biomarkers, providing new diagnostic and therapeutic options during pregnancy.

Profiling maternal plasma microRNA expression in early pregnancy to predict gestational diabetes mellitus

OBJECTIVE

To profile the differential expression of plasma miRNAs in gestational diabetes mellitus (GDM).

METHODS

In a pilot study conducted at a tertiary hospital in China between 2010 and 2014, peripheral blood samples were collected from women at 16-19weeks of pregnancy. Pooled samples from 10 women who were subsequently diagnosed with GDM and from 10 healthy controls were used to construct two small RNA libraries. High-throughput sequencing was performed, and differentially expressed miRNAs were validated by quantitative real-time polymerase chain reaction (qRT-PCR), followed by target prediction, Gene Ontology analysis, and pathway identification.

RESULTS

Sequencing revealed 32 miRNAs that were differentially expressed in GDM, including 12 miRNAs that were upregulated and 20 that were downregulated. Differential expression of five upregulated miRNAs (hsa-miR-16-5p, hsa-miR-17-5p, hsa-miR-19a-3p, hsa-miR-19b-3p, hsa-miR-20a-5p) was confirmed by qRT-PCR. Target prediction showed that the major targets of these miRNAs were associated with insulin resistance and abnormal pregnancies.

CONCLUSION

The five miRNAs that were differentially expressed in GDM could serve as noninvasive biomarkers. The results also provide insights into the molecular mechanisms that underlie GDM, thereby contributing to the diagnosis and treatment of this disease.

Upregulation of microRNA processing enzymes Drosha and Dicer in gestational diabetes mellitus

MicroRNAs (miRNAs) have been shown to play important roles in diverse cellular processes and linked to variety of disorders. Dicer and Drosha are two major enzymes in the miRNA biogenesis process. DGCR8 is the assistant of Drosha in the microprocessor complex. In this study, we evaluated the mRNA expression profiles of major miRNA processing machinery Drosha, Dicer, and DGCR8 in gestational diabetes mellitus (GDM), pregnant and healthy women. Our findings indicate that the expression levels of Drosha, Dicer and DGCR8 were upregulated in both pregnant and GDM patients compared to the control group. However, Drosha and Dicer were upregulated more than pregnant group. In conclusion, we detected dysregulation of Drosha, Dicer and DGCR8 expression in pregnant and GDM patients when compared to healthy control participants. Therefore, we favor the hypothesis that miRNAs are involved in the development of GDM.

Circulating microRNAs as clinical biomarkers in the predictions of pregnancy complications

Predicting pregnancy complications is a major topic for clinicians and biologists for maternal and fetal monitoring. Noninvasive biomarkers in maternal blood such as circulating microRNAs (miRNAs) are promising molecules to predict pregnancy disorders. miRNAs are noncoding short RNAs that regulate mRNA expression by repressing the translation or cleaving the transcript. miRNAs are released to the extracellular systemic circulation via exosomes. The discovery of plasma- or serum-derived miRNAs and of free-circulating exosomes that contain miRNAs provides useful information about the physiological or pathophysiological roles of the miRNAs. Specific placental miRNAs are present in maternal plasma in different ways depending on whether the pregnancy is normal or pathological or if there is no pregnancy. This paper focuses on placental miRNAs and extracellular miRNAs to the placenta whose misregulation could lead to pregnancy complications.

The Effect of an Obesogenic Maternal Environment on Expression of Fetal Umbilical Cord Blood miRNA

OBJECTIVE

Exposure to maternal obesity in utero predisposes offspring to obesity and metabolic disease. This study investigated whether maternal obesity is associated with alterations in expression of fetal microRNA (miRNA).

STUDY DESIGN

A cohort study of women with body mass index (BMI) ≥35 kg/m(2) (n = 16) versus those with normal BMI 20 to 24.9 (n = 20) was performed. All participants had normal glucose tolerance (1-hour glucose challenge test <130) and normally grown neonates (2700-3500 g). Umbilical cord samples were collected immediately after delivery. Expression of miRNA was assessed using Affymetrix GeneChip miRNA 3.0 Arrays. Differential miRNA expression was determined using Student t tests with Benjamini-Hocherg correction.

RESULTS

For 1733 human mature miRNAs, the expression levels were not statistically different in umbilical cord blood samples from pregnancies of obese women compared to controls.

CONCLUSION

Expression of fetal miRNA is not altered in umbilical cord blood in response to in utero exposure to obesity. Alternate mechanisms underlying the fetal effects of maternal obesity should be explored.

MicroRNA signatures as biomarkers and therapeutic target for CNS embryonal tumors: the pros and the cons

Embryonal tumors of the central nervous system represent a heterogeneous group of childhood cancers with an unknown pathogenesis; diagnosis, on the basis of histological appearance alone, is controversial and patients’ response to therapy is difficult to predict. They encompass medulloblastoma, atypical teratoid/rhabdoid tumors and a group of primitive neuroectodermal tumors. All are aggressive tumors with the tendency to disseminate throughout the central nervous system. The large amount of genomic and molecular data generated over the last 5–10 years encourages optimism that new molecular targets will soon improve outcomes. Recent neurobiological studies have uncovered the key role of microRNAs (miRNAs) in embryonal tumors biology and their potential use as biomarkers is increasingly being recognized and investigated. However the successful use of microRNAs as reliable biomarkers for the detection and management of pediatric brain tumors represents a substantial challenge. This review debates the importance of miRNAs in the biology of central nervous systemembryonal tumors focusing on medulloblastoma and atypical teratoid/rhabdoid tumors and highlights the advantages as well as the limitations of their prospective application as biomarkers and candidates for molecular therapeutic targets.

Molecular diagnostics and therapeutics for ectopic pregnancy

Ectopic pregnancies are a serious gynaecological emergency that can be fatal. As such, prompt diagnosis and safe timely treatment is essential. Here, we review the literature on the development of molecularly targeted diagnostics and therapeutics for ectopic pregnancy. A blood-based biomarker that accurately identifies an ectopic pregnancy could be used to offer early diagnostic certainty in cases where ultrasound cannot determine the location of the embryo ('a pregnancy of unknown location'). Molecules examined so far can be broadly grouped into biological themes of relevance to reproduction: (i) Fallopian tube (dys)function, (ii) embryo/trophoblast growth, (iii) corpus luteum function, (iv) inflammation, (v) uterine function and (vi) angiogenesis. While a sensitive and specific biomarker for ectopic pregnancy has yet to be identified, it is possible that improvements in platform technologies or a multi-modal biomarker approach may yield an accurate diagnostic biomarker test. Furthermore, with the advent of better imaging technology, the need for a blood-based biomarker test may be superseded by improvements in ultrasound or magnetic resonance imaging technology. There have been some recent preclinical studies describing molecularly targeted therapeutic approaches for ectopic pregnancy. Notably, bench-to-bedside studies have examined the use of combination gefitinib (orally available epidermal growth factor receptor inhibitor) and methotrexate. Preclinical studies suggest that combination gefitinib and methotrexate is highly effective in inducing placental cell death, and is significantly more effective than methotrexate alone. In early human trials, encouraging preliminary efficacy data have shown that combination gefitinib and methotrexate can rapidly resolve tubal ectopic pregnancies, and large extra-tubal ectopic pregnancies. If a large clinical randomized controlled trial confirms these findings, combination gefitinib and methotrexate could become a new medical treatment option for ectopic pregnancy.

Effect of labor on plasma concentrations and postpartum clearance of cell-free, pregnancy-associated, placenta-specific microRNAs

OBJECTIVE

This study aimed to investigate the effect of labor on plasma concentrations of cell-free, pregnancy-associated, placenta-specific microRNAs (miRNAs) before and after delivery.

METHOD

In the non-labor group (32 women), cesarean section (C/S) was performed before the beginning of labor. In the labor group (32 women), C/S was performed after the beginning of labor. Plasma concentrations of cell-free, pregnancy-associated, placenta-specific miRNAs (miR-515-3p, miR-517a, miR-517c, and miR-518b) were measured by real-time quantitative PCR. Each miRNA concentration was compared between the non-labor and labor groups.

RESULTS

Before C/S, plasma concentrations of cell-free, pregnancy-associated, placenta-specific miRNAs in the labor group were significantly higher than those in the non-labor group (P = 0.001 for 515-3p, P = 0.002 for 517a, P = 0.001 for 517c, and P = 0.003 for 518b). Twenty-four hours after delivery, plasma concentrations of cell-free, pregnancy-associated, placenta-specific miRNAs in the labor group were significantly higher than those in the non-labor group (P = 0.002 for 515-3p, P = 0.017 for 517a, P = 0.043 for 517c, and P = 0.009 for 518b).

CONCLUSION

The presence of labor affects cell-free, pregnancy-associated, placenta-specific miRNA levels in maternal plasma. Labor also affects postpartum clearance of these miRNAs 24 h after delivery.

Significance and therapeutic value of miRNAs in embryonal neural tumors

Embryonal tumors of the nervous system are the leading cause of childhood cancer-related morbidity and mortality. Medulloblastoma, supratentorial primitive neuroectodermal tumors, atypical teratoid/rhabdoid tumor and neuroblastoma account for more than 20% of childhood malignancies and typify the current neural embryonal tumor model in pediatric oncology. Mechanisms driving the formation of these tumors point towards impaired differentiation of neuronal and neuron-associated cells during the development of the nervous system as an important factor. The importance of microRNAs (miRNAs) for proper embryonic cell function has been confirmed and their aberrant expressions have been linked to tumor development. The role of miRNAs in controlling essential regulators of key pathways implicated in tumor development makes their use in diagnostics a powerful tool to be used for early detection of cancer, risk assessment and prognosis, as well as for the design of innovative therapeutic strategies. In this review we focus on the significance of miRNAs involved in the biology of embryonal neural tumors, delineate their clinical significance and discuss their potential as a novel therapeutic target.

Decidual cell regulation of natural killer cell-recruiting chemokines: implications for the pathogenesis and prediction of preeclampsia

First trimester human decidua is composed of decidual cells, CD56(bright)CD16(-) decidual natural killer (dNK) cells, and macrophages. Decidual cells incubated with NK cell-derived IFN-γ and either macrophage-derived TNF-α or IL-1β synergistically enhanced mRNA and protein expression of IP-10 and I-TAC. Both chemokines recruit CXCR3-expressing NK cells. This synergy required IFN-γ receptor 1 and 2 mediation via JAK/STAT and NFκB signaling pathways. However, synergy was not observed on neutrophil, monocyte, and NK cell-recruiting chemokines. Immunostaining of first trimester decidua localized IP-10, I-TAC, IFN-γR1, and -R2 to vimentin-positive decidual cells versus cytokeratin-positive interstitial trophoblasts. Flow cytometry identified high CXCR3 levels on dNK cells and minority peripheral CD56(bright)CD16(-) pNK cells and intermediate CXCR3 levels on the majority of CD56(dim)CD16(+) pNK cells. Incubation of pNK cells with either IP-10 or I-TAC elicited concentration-dependent enhanced CXCR3 levels and migration of both pNK cell subsets that peaked at 10 ng/mL, whereas each chemokine at a concentration of 50 ng/mL inhibited CXCR3 expression and pNK cell migration. Deciduae from women with preeclampsia, a leading cause of maternal and fetal morbidity and mortality, displayed significantly lower dNK cell numbers and higher IP-10 and I-TAC levels versus gestational age-matched controls. Significantly elevated IP-10 levels in first trimester sera from women eventually developing preeclampsia compared with controls, identifying IP-10 as a novel, robust early predictor of preeclampsia.

The Lin28/Let-7 system in early human embryonic tissue and ectopic pregnancy

Our objective was to determine the expression of the elements of the Lin28/Let-7 system, and related microRNAs (miRNAs), in early stages of human placentation and ectopic pregnancy, as a means to assess the potential role of this molecular hub in the pathogenesis of ectopic gestation. Seventeen patients suffering from tubal ectopic pregnancy (cases) and forty-three women with normal on-going gestation that desired voluntary termination of pregnancy (VTOP; controls) were recruited for the study. Embryonic tissues were subjected to RNA extraction and quantitative PCR analyses for LIN28B, Let-7a, miR-132, miR-145 and mir-323-3p were performed. Our results demonstrate that the expression of LIN28B mRNA was barely detectable in embryonic tissue from early stages of gestation and sharply increased thereafter to plateau between gestational weeks 7–9. In contrast, expression levels of Let-7, mir-132 and mir-145 were high in embryonic tissue from early gestations (≤6-weeks) and abruptly declined thereafter, especially for Let-7. Opposite trends were detected for mir-323-3p. Embryonic expression of LIN28B mRNA was higher in early stages (≤6-weeks) of ectopic pregnancy than in normal gestation. In contrast, Let-7a expression was significantly lower in early ectopic pregnancies, while miR-132 and miR-145 levels were not altered. Expression of mir-323-3p was also suppressed in ectopic embryonic tissue. We are the first to document reciprocal changes in the expression profiles of the gene encoding the RNA-binding protein, LIN28B, and the related miRNAs, Let-7a, mir-132 and mir-145, in early stages of human placentation. This finding suggests the potential involvement of LIN28B/Let-7 (de)regulated pathways in the pathophysiology of ectopic pregnancy in humans.

Elsevier Trophoblast Research Award Lecture: origin, evolution and future of placenta miRNAs

MicroRNAs (miRNAs) regulate the expression of a large number of genes in plants and animals. Placental miRNAs appeared late in evolution and can be found only in mammals. Nevertheless, these miRNAs are constantly under evolutionary pressure. As a consequence, miRNA sequences and their mRNA targets may differ between species, and some miRNAs can only be found in humans. Their expression can be tissue- or cell-specific and can vary time-dependently. Human placenta tissue exhibits a specific miRNA expression pattern that dynamically changes during pregnancy and is reflected in the maternal plasma. Some placental miRNAs are involved in or associated with major pregnancy disorders, such as preeclampsia, intrauterine growth restriction or preterm delivery and, therefore, have a strong potential for usage as sensitive and specific biomarkers. In this review we summarize current knowledge on the origin of placental miRNAs, their expression in humans with special regard to trophoblast cells, interspecies differences, and their future as biomarkers. It can be concluded that animal models for human reproduction have a different panel of miRNAs and targets, and can only partly reflect or predict the situation in humans.

MicroRNA-323-3p with clinical potential in rheumatoid arthritis, Alzheimer's disease and ectopic pregnancy

INTRODUCTION

MicroRNAs (miRNAs) are a group of noncoding RNAs,∼ 20 - 22 nucleotides in length, that repress target gene expression through mRNA degradation and translation inhibition. The gene encoding miR-323-3p, which is a biomarker in immune and inflammatory responses, exists in a miRNA cluster in chromosomal region 14q32.31. It has been shown that miR-323-3p associates with the pathogenesis of several diseases, such as rheumatoid arthritis, Alzheimer's disease and ectopic pregnancy.

AREAS COVERED

This review provides a current view on the association of miR-323-3p with several human diseases and is focused on the recent studies of miR-323-3p regulation, discussing its potential as an epigenetic biomarker and therapeutic target for these diseases. In particular, the mechanisms of miR-323-3p in these diseases and how miR-323-3p is regulated are also discussed.

EXPERT OPINION

Although the exact role of miR-323-3p in these diseases has not been fully elucidated, targeting miR-323-3p may serve as a promising therapy strategy.