Differentially expressed microRNAs and affected biological pathways revealed by modulated modularity clustering (MMC) analysis of human preeclamptic and IUGR placentas

Altered distribution of fatty acid exerting lipid metabolism and transport at the maternal-fetal interface in fetal growth restriction

INTRODUCTION

Fetal growth restriction (FGR) is a common complication of pregnancy. Lipid metabolism and distribution may contribute to the progression of FGR. However, the metabolism-related mechanisms of FGR remain unclear. The aim of this study was to identify metabolic profiles associated with FGR, as well as probable genes and signaling pathways.

METHODS

Metabolomic profiles at the maternal-fetal interface (including the placenta, maternal and fetal serum) from pregnant women with (n = 35) and without (n = 35) FGR were analyzed by gas chromatography-mass spectrometry (GC-MS). Combined with differentially expressed genes (DEGs) from the GSE35574 dataset, analysis was performed for differential metabolites, and identified by the Metabo Analyst dataset. Finally, the pathology and screened DEGs were further identified.

RESULTS

The results showed that fatty acids (FAs) accumulated in the placenta and decreased in fetal blood in FGR cases compared to controls. The linoleic acid metabolism was the focus of placental differential metabolites and genes enrichment analysis. In this pathway, phosphatidylcholine can interact with PLA2G2A and PLA2G4C, and 12(13)-EpOME can interact with CYP2J2. PLA2G2A and CYP2J2 were elevated, and PLA2G4C was decreased in the FGR placenta.

DISCUSSION

In conclusion, accumulation of FAs in the placental ischemic environments, may involve linoleic acid metabolism, which may be regulated by PLA2G2A, CYP2J2, and PLA2G4C. This study may contribute to understanding the underlying metabolic and molecular mechanisms of FGR.

MicroRNAs targeting peroxisome proliferator-activated receptor (PPAR) gene are differentially expressed in low birth weight placentae

INTRODUCTION

Peroxisome proliferator-activated receptors (PPARs) are activated by natural ligands like fatty acids and influence placental angiogenesis and pregnancy outcome. However, the underlying molecular mechanisms are not clear. This study aims to investigate the association of maternal and placental fatty acid levels with DNA methylation and microRNA regulation of PPARs in the placentae of women delivering low birth weight (LBW) babies.

METHODS

This study includes 100 women delivering normal birth weight (NBW) baby and 70 women delivering LBW baby. Maternal and placental fatty acids levels were estimated by gas chromatograph. Gene promoter methylation and mRNA expression of PPARs was analyzed using Epitect Methyl-II PCR assay kit and RT-PCR respectively. Expression of miRNAs targeting PPAR mRNA were analyzed using a Qiagen miRCURY LNA PCR Array on RT-PCR.

RESULTS

Placental docosahexaenoic acid (DHA) levels and placental mRNA expression of PPARα and PPARγ were lower (p < 0.05 for all) in the LBW group. Differential expression of miRNAs (upregulated miR-33a-5p and miR-22-5p; downregulated miR-301a-5p, miR-518d-5p, miR-27b-5p, miR-106a-5p, miR-21-5p, miR-548d-5p, miR-17-5p and miR-20a-5p) (p < 0.05 for all) was observed in the LBW group. Maternal and placental polyunsaturated fatty acids and total omega-3 fatty acids were positively associated while saturated fatty acids were negatively associated with expression of miRNAs (p < 0.05 for all). Placental expression of miRNAs were positively associated with birth weight (p < 0.05 for all).

DISCUSSION

Our data suggests that maternal fatty acid status is associated with changes in the placental expression of miRNAs targeting PPAR gene in women delivering LBW babies.

Diagnostic signature composed of seven genes in HIF-1 signaling pathway for preeclampsia

PURPOSE

In this study, we explored the relationship of genes in HIF-1 signaling pathway with preeclampsia and establish a logistic regression model for diagnose preeclampsia using bioinformatics analysis.

METHOD

Two microarray datasets GSE75010 and GSE35574 were downloaded from the Gene Expression Omnibus database, which was using for differential expression analysis. DEGs were performed the Gene Ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis and Gene set enrichment analysis (GSEA). Then we performed unsupervised consensus clustering analysis using genes in HIF-1 signaling pathway, and clinical features and immune cell infiltration were compared between these clusters, as well as the least absolute shrinkage and selection operator (LASSO) method to screened out key genes to constructed logistic regression model, and receiver operating characteristic (ROC) curve was plotted to evaluate the accuracy of the model.

RESULTS

57 DEGs were identified, of which GO, KEGG and analysis GSEA showed DEGs were mostly involved in HIF-1 signaling pathway. Two subtypes were identified of preeclampsia and 7 genes in HIF1-signaling pathway were screened out to establish the logistic regression model for discrimination preeclampsia from controls, of which the AUC are 0.923 and 0.845 in training and validation datasets respectively.

CONCLUSION

Seven genes (including MKNK1, ARNT, FLT1, SERPINE1, ENO3, LDHA, BCL2) were screen out to build potential diagnostic model of preeclampsia.

Inhibition of the AT1R agonistic autoantibody in a rat model of preeclampsia improves fetal growth in late gestation

Placenta ischemia, the initiating event in preeclampsia (PE), is associated with fetal growth restriction. Inhibition of the agonistic autoantibody against the angiotensin type 1 receptor AT1-AA, using an epitope-binding inhibitory peptide ('n7AAc') attenuates increased blood pressure at gestational day (G)19 in the clinically relevant reduced uterine perfusion pressure (RUPP) model of PE. Thus we tested the hypothesis that maternal administration of 'n7AAc' does not transfer to the fetus, improves uterine blood flow and fetal growth, and attenuates elevated placental expression of miRNAs implicated in PE and FGR. Sham or RUPP surgery was performed at G14 with vehicle or 'n7AAc' (144 µg/day) administered via an osmotic pump from G14 to G20. Maternal plasma levels of the peptide on G20 were 16.28 ± 4.4 nM, and fetal plasma levels were significantly lower at 1.15 ± 1.7 nM (P = 0.0007). The uterine artery resistance index was significantly elevated in RUPP (P < 0.0001) but was not increased in 'n7AAc'-RUPP or 'n7AAc'-Sham versus Sham. A significant reduction in fetal weight at G20 in RUPP (P = 0.003) was not observed in 'n7AAc'-RUPP. Yet, percent survival was reduced in RUPP (P = 0.0007) and 'n7AAc'-RUPP (P < 0.0002). Correlation analysis indicated the reduction in percent survival during gestation was specific to the RUPP (r = 0.5342, P = 0.043) and independent of 'n7AAc'. Placental miR-155 (P = 0.0091) and miR-181a (P = 0.0384) expression was upregulated in RUPP at G20 but was not elevated in 'n7AAc'-RUPP. Collectively, our results suggest that maternal administration of 'n7AAc' does not alter fetal growth in the RUPP implicating its potential as a therapeutic for the treatment of PE.NEW & NOTEWORTHY The seven amino acid inhibitory peptide to the AT1-AA ('n7AAc') has limited transfer to the fetus at gestational day 20, improves uterine blood flow and fetal growth in the reduced uterine perfusion pressure model of preeclampsia (PE), and does not impair fetal survival during gestation in sham-operated or placental ischemic rats. Collectively, these findings suggest that maternal administration of 'n7AAc' as an effective strategy for the treatment of PE is associated with improved outcomes in the fetus.

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.

Identification and Validation of a Five-Gene Diagnostic Signature for Preeclampsia

Preeclampsia is the leading cause of morbidity and mortality for mothers and newborns worldwide. Despite extensive efforts made to understand the underlying pathology of preeclampsia, there is still no clinically useful effective tool for the early diagnosis of preeclampsia. In this study, we conducted a retrospectively multicenter discover-validation study to develop and validate a novel biomarker for preeclampsia diagnosis. We identified 38 differentially expressed genes (DEGs) involved in preeclampsia in a case-control study by analyzing expression profiles in the discovery cohort. We developed a 5-mRNA signature (termed PE5-signature) to diagnose preeclampsia from 38 DEGs using recursive feature elimination with a random forest supervised classification algorithm, including ENG, KRT80, CEBPA, RDH13 and WASH9P. The PE5-signature showed high accuracy in discriminating preeclampsia from controls with a receiver operating characteristic area under the curve value (AUC) of 0.971, a sensitivity of 0.842 and a specificity of 0.950. The PE5-signature was then validated in an independent case-control study and achieved a reliable and robust predictive performance with an AUC of 0.929, a sensitivity of 0.696, and a specificity of 0.946. In summary, we have developed and validated a five-mRNA biomarker panel as a risk assessment tool to assist in the detection of preeclampsia. This gene panel has potential clinical value for early preeclampsia diagnosis and may help us better understand the precise mechanisms involved.

MAGE: An Open-Source Tool for Meta-Analysis of Gene Expression Studies

MAGE (Meta-Analysis of Gene Expression) is a Python open-source software package designed to perform meta-analysis and functional enrichment analysis of gene expression data. We incorporate standard methods for the meta-analysis of gene expression studies, bootstrap standard errors, corrections for multiple testing, and meta-analysis of multiple outcomes. Importantly, the MAGE toolkit includes additional features for the conversion of probes to gene identifiers, and for conducting functional enrichment analysis, with annotated results, of statistically significant enriched terms in several formats. Along with the tool itself, a web-based infrastructure was also developed to support the features of this package.

Proteoglycans: Systems-Level Insight into Their Expression in Healthy and Diseased Placentas

Proteoglycan macromolecules play key roles in several physiological processes (e.g., adhesion, proliferation, migration, invasion, angiogenesis, and apoptosis), all of which are important for placentation and healthy pregnancy. However, their precise roles in human reproduction have not been clarified. To fill this gap, herein, we provide an overview of the proteoglycans' expression and role in the placenta, in trophoblast development, and in pregnancy complications (pre-eclampsia, fetal growth restriction), highlighting one of the most important members of this family, syndecan-1 (SDC1). Microarray data analysis showed that of 34 placentally expressed proteoglycans, SDC1 production is markedly the highest in the placenta and that SDC1 is the most upregulated gene during trophoblast differentiation into the syncytiotrophoblast. Furthermore, placental transcriptomic data identified dysregulated proteoglycan genes in pre-eclampsia and in fetal growth restriction, including SDC1, which is supported by the lower concentration of syndecan-1 in maternal blood in these syndromes. Overall, our clinical and in vitro studies, data analyses, and literature search pointed out that proteoglycans, as important components of the placenta, may regulate various stages of placental development and participate in the maintenance of a healthy pregnancy. Moreover, syndecan-1 may serve as a useful marker of syncytialization and a prognostic marker of adverse pregnancy outcomes. Further studies are warranted to explore the role of proteoglycans in healthy and complicated pregnancies, which may help in diagnostic or therapeutic developments.

miR-1227-3p participates in the development of fetal growth restriction via regulating trophoblast cell proliferation and apoptosis

Fetal growth restriction (FGR) is a common obstetric disease, which is harmful to the pregnant women and fetuses. It has many influencing factors, but the specific etiology is not clear. MiRNA plays an important role in the fetal growth and development. In this article, we use TaqMan Low-Density Array to screen and analyze the differently expressed miRNAs in FGR-affected placenta (n = 40) and the normal placenta (n = 40). A total of 139 abnormally expressed miRNAs in the FGR-affected placenta were identified, and miR-1227-3p was the most highly downregulated miRNA. Importantly, miR-1227-3p may promote the proliferation in HTR-8/SVneo cells, while inhibited the apoptosis of HTR-8/SVneo cells. DAVID was used to analyze the pathway enrichment of target genes of miR-1227-3p to predict its mechanism of action. Furthermore, the putative targets of miR-1227-3p were predicted using the TargetScan, PicTar, DIANA LAB, and miRWalk database. The potential expression of target genes of miR-1227-3p, including PRKAB2, AKT1, PIK3R3, and MKNK1 were significantly increased in FGR-affected placenta. Taken together, miR-1227-3p may participate in the development of FGR via regulating trophoblast cell proliferation and apoptosis by targeting genes involved in the insulin pathway. MiR-1227-3p may have a potential clinical value in the prevention and treatment of FGR, we need to study further to prove its value in the future.

Preeclamptic Women Have Disrupted Placental microRNA Expression at the Time of Preeclampsia Diagnosis: Meta-Analysis

Introduction: Preeclampsia (PE) is a pregnancy-associated, multi-organ, life-threatening disease that appears after the 20th week of gestation. The aim of this study was to perform a systematic review and meta-analysis to determine whether women with PE have disrupted miRNA expression compared to women who do not have PE. Methods: We conducted a systematic review and meta-analysis of studies that reported miRNAs expression levels in placenta or peripheral blood of pregnant women with vs. without PE. Studies published before October 29, 2021 were identified through PubMed, EMBASE and Web of Science. Two reviewers used predefined forms and protocols to evaluate independently the eligibility of studies based on titles and abstracts and to perform full-text screening, data abstraction and quality assessment. Standardized mean difference (SMD) was used as a measure of effect size. Results: 229 publications were included in the systematic review and 53 in the meta-analysis. The expression levels in placenta were significantly higher in women with PE compared to women without PE for miRNA-16 (SMD = 1.51,95%CI = 0.55-2.46), miRNA-20b (SMD = 0.89, 95%CI = 0.33-1.45), miRNA-23a (SMD = 2.02, 95%CI = 1.25-2.78), miRNA-29b (SMD = 1.37, 95%CI = 0.36-2.37), miRNA-155 (SMD = 2.99, 95%CI = 0.83-5.14) and miRNA-210 (SMD = 1.63, 95%CI = 0.69-2.58), and significantly lower for miRNA-376c (SMD = -4.86, 95%CI = -9.51 to -0.20). An increased level of miRNK-155 expression was found in peripheral blood of women with PE (SMD = 2.06, 95%CI = 0.35-3.76), while the expression level of miRNA-16 was significantly lower in peripheral blood of PE women (SMD = -0.47, 95%CI = -0.91 to -0.03). The functional roles of the presented miRNAs include control of trophoblast proliferation, migration, invasion, apoptosis, differentiation, cellular metabolism and angiogenesis. Conclusion: miRNAs play an important role in the pathophysiology of PE. The identification of differentially expressed miRNAs in maternal blood creates an opportunity to define an easily accessible biomarker of PE.

Placental expression of miR-21-5p, miR-210-3p and miR-141-3p: relation to human fetoplacental growth

BACKGROUND/OBJECTIVES

Dysregulation of microRNAs (miRNAs) and their target genes in placental tissue is associated with foetal growth restriction. We aimed to evaluate associations of placental miR-21-5p, miR-141-3p and miR-210-3p expression with maternal, placental and newborn parameters and with placental expression of their potential target genes PTEN, VEGF, FLT and ENG in a set of well-characterized small- (SGA) and appropriate- (AGA) for gestational age full-term singleton pregnancies.

SUBJECTS/METHODS

Placental samples (n = 80) from 26 SGA and 54 AGA were collected from full-term singleton pregnancies. Placental transcript abundances of miR-21-5p, miR-141-3p and miR-210-3p were assessed after normalization to a reference miRNA, mir-16-5p by real-time quantitative PCR. Placental transcript abundances of PTEN, VEGF, FLT and ENG were assessed after normalizing to a panel of reference genes.

RESULTS

Placental miR-21-5p transcript abundance was negatively associated with placental weight (n = 80, r = -0.222, P = 0.047) and this association was specific to the AGA births (n = 54, r = -0.292, P = 0.032). Placental transcript abundances of miR-210-3p and miR-141-3p were not associated with placental weight or birth weight in all 80 births. However, placental miR-210-3p transcript abundance was positively associated with birth weight specifically in the SGA births (n = 26, r = 0.449, P = 0.021). Placental transcript abundance of miR-21-5p was negatively associated with PTEN transcript abundance (Spearman's ρ = -0.245, P = 0.028) while that of miR-141-3p was positively associated with FLT (Spearman's ρ = 0.261, P = 0.019) and ENG (Spearman's ρ = 0.259, P = 0.020) transcript abundances in all 80 births.

CONCLUSION

We conclude that placental miR-21-5p and miR-210-3p may be involved in fetoplacental growth. However, this regulation is unlikely to be mediated through placental expression of PTEN, VEGF, FLT or ENG.

Novel Technologies for Target Delivery of Therapeutics to the Placenta during Pregnancy: A Review

Uterine spiral artery remodeling is essential for placental perfusion and fetal growth and, when impaired, results in placental ischemia and pregnancy complications, e.g., fetal growth restriction, preeclampsia, premature birth. Despite the high incidence of adverse pregnancies, current treatment options are limited. Accordingly, research has shifted to the development of gene therapy technologies that provide targeted delivery of "payloads" to the placenta while limiting maternal and fetal exposure. This review describes the current strategies, including placental targeting peptide-bound liposomes, nanoparticle or adenovirus constructs decorated with specific peptide sequences and placental gene promoters delivered via maternal IV injection, directly into the placenta or the uterine artery, as well as noninvasive site-selective targeting of regulating genes conjugated with microbubbles via contrast-enhanced ultrasound. The review also provides a perspective on the effectiveness of these technologies in various animal models and their practicability and potential use for targeted placental delivery of therapeutics and genes in adverse human pregnancies affected by placental dysfunction.

Placental genomic risk scores and early neurodevelopmental outcomes

Tracing the early paths leading to developmental disorders is critical for prevention. In previous work, we detected an interaction between genomic risk scores for schizophrenia (GRSs) and early-life complications (ELCs), so that the liability of the disorder explained by genomic risk was higher in the presence of a history of ELCs, compared with its absence. This interaction was specifically driven by loci harboring genes highly expressed in placentae from normal and complicated pregnancies [G. Ursini et al., Nat. Med. 24, 792-801 (2018)]. Here, we analyze whether fractionated genomic risk scores for schizophrenia and other developmental disorders and traits, based on placental gene-expression loci (PlacGRSs), are linked with early neurodevelopmental outcomes in individuals with a history of ELCs. We found that schizophrenia's PlacGRSs are negatively associated with neonatal brain volume in singletons and offspring of multiple pregnancies and, in singletons, with cognitive development at 1 y and, less strongly, at 2 y, when cognitive scores become more sensitive to other factors. These negative associations are stronger in males, found only with GRSs fractionated by placental gene expression, and not found in PlacGRSs for other developmental disorders and traits. The relationship of PlacGRSs with brain volume persists as an anlage of placenta biology in adults with schizophrenia, again selectively in males. Higher placental genomic risk for schizophrenia, in the presence of ELCs and particularly in males, alters early brain growth and function, defining a potentially reversible neurodevelopmental path of risk that may be unique to schizophrenia.

High-throughput miRNA sequencing of the human placenta: expression throughout gestation

Aim: To understand miRNA changes across gestation in healthy human placentae. This is essential before miRNAs can be used as biomarkers or prognostic indicators during pregnancy. Materials & methods: Using next-generation sequencing, we characterize the normative human placenta miRNome in first (n = 113) and third trimester (n = 47). Results & conclusion: There are 801 miRNAs expressed in both first and third trimester, including 182 with similar expression across gestation (p ≥ 0.05, fold change ≤2) and 180 significantly different (false discovery rate <0.05, fold change >2). Of placenta-specific miRNA clusters, chromosome 14 miRNA cluster decreases across gestation and chromosome 19 miRNA cluster is overall highly expressed. Chromosome 13 clusters are upregulated in first trimester. This work provides a rich atlas of healthy pregnancies to direct functional studies investigating the epigenetic differences in first and third trimester placentae.

Current approaches and developments in transcript profiling of the human placenta

BACKGROUND

The placenta is the active interface between mother and foetus, bearing the molecular marks of rapid development and exposures in utero. The placenta is routinely discarded at delivery, providing a valuable resource to explore maternal-offspring health and disease in pregnancy. Genome-wide profiling of the human placental transcriptome provides an unbiased approach to study normal maternal–placental–foetal physiology and pathologies.

OBJECTIVE AND RATIONALE

To date, many studies have examined the human placental transcriptome, but often within a narrow focus. This review aims to provide a comprehensive overview of human placental transcriptome studies, encompassing those from the cellular to tissue levels and contextualize current findings from a broader perspective. We have consolidated studies into overarching themes, summarized key research findings and addressed important considerations in study design, as a means to promote wider data sharing and support larger meta-analysis of already available data and greater collaboration between researchers in order to fully capitalize on the potential of transcript profiling in future studies.

SEARCH METHODS

The PubMed database, National Center for Biotechnology Information and European Bioinformatics Institute dataset repositories were searched, to identify all relevant human studies using ‘placenta’, ‘decidua’, ‘trophoblast’, ‘transcriptome’, ‘microarray’ and ‘RNA sequencing’ as search terms until May 2019. Additional studies were found from bibliographies of identified studies.

OUTCOMES

The 179 identified studies were classifiable into four broad themes: healthy placental development, pregnancy complications, exposures during pregnancy and in vitro placental cultures. The median sample size was 13 (interquartile range 8–29). Transcriptome studies prior to 2015 were predominantly performed using microarrays, while RNA sequencing became the preferred choice in more recent studies. Development of fluidics technology, combined with RNA sequencing, has enabled transcript profiles to be generated of single cells throughout pregnancy, in contrast to previous studies relying on isolated cells. There are several key study aspects, such as sample selection criteria, sample processing and data analysis methods that may represent pitfalls and limitations, which need to be carefully considered as they influence interpretation of findings and conclusions. Furthermore, several areas of growing importance, such as maternal mental health and maternal obesity are understudied and the profiling of placentas from these conditions should be prioritized.

WIDER IMPLICATIONS

Integrative analysis of placental transcriptomics with other ‘omics’ (methylome, proteome and metabolome) and linkage with future outcomes from longitudinal studies is crucial in enhancing knowledge of healthy placental development and function, and in enabling the underlying causal mechanisms of pregnancy complications to be identified. Such understanding could help in predicting risk of future adversity and in designing interventions that can improve the health outcomes of both mothers and their offspring. Wider collaboration and sharing of placental transcriptome data, overcoming the challenges in obtaining sufficient numbers of quality samples with well-defined clinical characteristics, and dedication of resources to understudied areas of pregnancy will undoubtedly help drive the field forward.

Network analysis reveals important genes in human placenta

AIM

To determine which genes are important in placenta by network analysis.

METHODS

Placenta expressing genes were screened from RNA-Seq data. Protein-protein interaction data were downloaded from STRING (v11.0) database. Google PageRank (PR) algorithm was used to identify important placental genes from protein interaction network. Six placental disease-related datasets were downloaded from NCBI GEO database, and the differential expression of the 99 genes was identified.

RESULTS

We calculated PR for each placenta expressing gene and defined the top 99 genes with high PR as important genes. GAPDH has the highest PR. The 99 genes had different expression pattern in placental cell types. FN1 is up-regulated in 8 w EVT compared to 8 w CTB and 24 w EVT compared to 8 w EVT. HSPA4 is down-regulated in 8 w EVT compared to 8 w CTB and 24 w EVT compared to 8 w EVT. MIB2, TLR4, and UBB are consistently changed in preeclampsia (PE). UBB and ACTG1 were identified to be down-regulated in fetal growth restriction (FGR). SOD1 is down-regulated in preterm birth placenta.

CONCLUSION

Our findings confirmed that the importance of these genes in placenta-related diseases, and provide new candidates (MIB2, UBB, ACTG1, and SOD1) for placenta-related disease diagnosis and treatment.

Peroxisome Proliferator-Activated Receptors (PPAR), fatty acids and microRNAs: Implications in women delivering low birth weight babies

Low birth weight (LBW) babies are associated with neonatal morbidity and mortality and are at increased risk for noncommunicable diseases (NCDs) in later life. However, the molecular determinants of LBW are not well understood. Placental insufficiency/dysfunction is the most frequent etiology for fetal growth restriction resulting in LBW and placental epigenetic processes are suggested to be important regulators of pregnancy outcome. Early life exposures like altered maternal nutrition may have long-lasting effects on the health of the offspring via epigenetic mechanisms like DNA methylation and microRNA (miRNA) regulation. miRNAs have been recognized as major regulators of gene expression and are known to play an important role in placental development. Angiogenesis in the placenta is known to be regulated by transcription factor peroxisome proliferator-activated receptor (PPAR) which is activated by ligands such as long-chain-polyunsaturated fatty acids (LCPUFA). In vitro studies in different cell types indicate that fatty acids can influence epigenetic mechanisms like miRNA regulation. We hypothesize that maternal fatty acid status may influence the miRNA regulation of PPAR genes in the placenta in women delivering LBW babies. This review provides an overview of miRNAs and their regulation of PPAR gene in the placenta of women delivering LBW babies.Abbreviations: AA - Arachidonic Acid; Ago2 - Argonaute2; ALA - Alpha-Linolenic Acid; ANGPTL4 - Angiopoietin-Like Protein 4; C14MC - Chromosome 14 miRNA Cluster; C19MC - Chromosome 19 miRNA Cluster; CLA - Conjugated Linoleic Acid; CSE - Cystathionine γ-Lyase; DHA - Docosahexaenoic Acid; EFA - Essential Fatty Acids; E2F3 - E2F transcription factor 3; EPA - Eicosapentaenoic Acid; FGFR1 - Fibroblast Growth Factor Receptor 1; GDM - Gestational Diabetes Mellitus; hADMSCs - Human Adipose Tissue-Derived Mesenchymal Stem Cells; hBMSCs - Human Bone Marrow Mesenchymal Stem Cells; HBV - Hepatitis B Virus; HCC - Hepatocellular Carcinoma; HCPT - Hydroxycamptothecin; HFD - High-Fat Diet; Hmads - Human Multipotent Adipose-Derived Stem; HSCS - Human Hepatic Stellate Cells; IUGR - Intrauterine Growth Restriction; LA - Linoleic Acid; LBW - Low Birth Weight; LCPUFA - Long-Chain Polyunsaturated Fatty Acids; MEK1 - Mitogen-Activated Protein Kinase 1; MiRNA - MicroRNA; mTOR - Mammalian Target of Rapamycin; NCDs - NonCommunicable Diseases; OA - Oleic Acid; PASMC - Pulmonary Artery Smooth Muscle Cell; PLAG1 - Pleiomorphic Adenoma Gene 1; PPAR - Peroxisome Proliferator-Activated Receptor; PPARα - PPAR alpha; PPARγ - PPAR gamma; PPARδ - PPAR delta; pre-miRNA - precursor miRNA; RISC - RNA-Induced Silencing Complex; ROS - Reactive Oxygen Species; SAT - Subcutaneous Adipose Tissue; WHO - World Health Organization.

Integrated analysis of multiple microarray studies to identify novel gene signatures in preeclampsia

INTRODUCTION

Preeclampsia (PE) is one of the major causes of maternal and fetal morbidity and mortality in pregnancy worldwide. However, the intrinsic molecular mechanisms underlying the pathogenesis of PE have not yet been fully elucidated.

METHODS

Robust rank aggregation (RRA), weighted correlation network analysis (WGCNA) and protein-protein interaction (PPI) methods were used to identify robust differentially expressed genes (DEGs) and hub genes in preeclampsia and subgroups based on 10 Gene Expression Omnibus (GEO) datasets. Subsequently, enrichment analysis and correlation analysis were performed to explore the potential function of the robust DEGs and hub genes. The diagnostic role of hub genes was further investigated by GSE12767. The miRNA regulators and the effect of hypoxia on hub genes were explored by using GSE84260 and GSE65271, respectively.

RESULTS

Robust DEGs were identified in each subgroup including preeclampsia. Totally, 24 hub genes enriched in inflammatory response, renin-angiotensin system and JAK-STAT pathway, and 24 related miRNA regulators were identified.

DISCUSSION

Our integrated analysis identified novel gene signatures in preeclampsia and subgroups and will contribute to the understanding of comprehensive molecular changes in preeclampsia.

Information on dysregulation of microRNA in placenta linked to preeclampsia

MicroRNAs are single-stranded, non-coding RNA molecules, regulate gene expression at the post-transcriptional level. They are expressed in the human body and have a significant impact on the different processes of pathological illness. A developing placenta undergoes a series of stages after successful fertilization, such as cell division, migration, adhesion, apoptosis, and angiogenesis. MicroRNAs dysregulation in placenta has been linked to pregnancy-related complications such as preeclampsia. Therefore, it is of interest to document known information (list of microRNA) on this issue in the development of biological tools for diagnosis, treatment and prevention of the disease.

Maternal plasma miRNAs as potential biomarkers for detecting risk of small-for-gestational-age births

Background

Small-for-gestational-age fetuses (SGA) (birthweight <10th centile) are at high risk for stillbirth or long-term adverse outcomes. Here, we investigate the ability of circulating maternal plasma miRNAs to determine the risk of SGA births.

Methods

Maternal plasma samples from 29 women of whom 16 subsequently delivered normally grown babies and 13 delivered SGA (birthweight <5th centile) were selected from a total of 511 women recruited to form a discovery cohort in which expression data for a total of 800 miRNAs was determined using the Nanostring nCounter miRNA assay. Validation by RT-qPCR was performed in an independent cohort.

Findings

Partial least-squares discriminant analysis (PLS-DA) of the Nanostring nCounter miRNA assay initially identified seven miRNAs at 12–14⁺⁶ weeks gestation, which discriminated between SGA cases and controls. Four of these were technically validated by RT-qPCR. Differential expression of two miRNA markers; hsa-miR-374a-5p (p = 0•0176) and hsa-let-7d-5p (p = 0•0036), were validated in an independent population of 95 women (SGA n = 12, Control n = 83). In the validation cohort, which was enriched for SGA cases, the ROC AUCs were 0•71 for hsa-miR-374a-5p, and 0•74 for hsa-let-7d-5p, and 0•77 for the two combined.

Interpretation

Whilst larger population-wide studies are required to validate their performance, these findings highlight the potential of circulating miRNAs to act as biomarkers for early prediction of SGA births.

Funding

This work was supported by Genesis Research Trust, March of Dimes, and the National Institute for Health Research Biomedical Research Centre (NIHR BRC) based at Imperial Healthcare NHS Trust and Imperial College London.

MicroRNAs 363 and 149 are differentially expressed in the maternal circulation preceding a diagnosis of preeclampsia

Preeclampsia is a pregnancy complication associated with angiogenic dysbalance, maternal endothelial dysfunction and end-organ injury. A predictive test to identify those who will develop preeclampsia could substantially decrease morbidity and mortality. MicroRNAs (miRs) are small RNA molecules involved in post-transcriptional gene regulation. We screened for circulating miRs differentially expressed at 36 weeks’ gestation in pregnancies before the development of preeclampsia. We used a case–control group (198 controls, 34 pre-preeclampsia diagnosis) selected from a prospective cohort (n = 2015) and performed a PCR-based microarray to measure the expression of 41 miRs. We found six circulating miRs (miRs 363, 149, 18a, 1283, 16, 424) at 36 weeks' had significantly reduced expression (p < 0.0001–0.04). miR363 was significantly downregulated at 28 weeks’ gestation, 10–12 weeks before the onset of clinical disease. In the circulation of another cohort of 34 participants with established preterm preeclampsia (vs 23 controls), we found miRs363, 18a, 149 and 16 were significantly down regulated (p < 0.0001–0.04). Combined expression of miRs149 and 363 in the circulation at 36 weeks’ gestation provides a test with 45% sensitivity (at a specificity of 90%) which suggests measuring both miRs may have promise as part of a multi-marker test to predict preeclampsia.

Placental microRNA expression associates with birthweight through control of adipokines: results from two independent cohorts

MicroRNAs are non-coding RNAs that regulate gene expression post-transcriptionally. In the placenta, the master regulator of foetal growth and development, microRNAs shape the basic processes of trophoblast biology and specific microRNA have been associated with foetal growth. To comprehensively assess the role of microRNAs in placental function and foetal development, we have performed small RNA sequencing to profile placental microRNAs from two independent mother-infant cohorts: the Rhode Island Child Health Study (n = 225) and the New Hampshire Birth Cohort Study (n = 317). We modelled microRNA counts on infant birthweight percentile (BWP) in each cohort, while accounting for race, sex, parity, and technical factors, using negative binomial generalized linear models. We identified microRNAs that were differentially expressed (DEmiRs) with BWP at false discovery rate (FDR) less than 0.05 in both cohorts. hsa-miR-532-5p (miR-532) was positively associated with BWP in both cohorts. By integrating parallel whole transcriptome and small RNA sequencing in the RICHS cohort, we identified putative targets of miR-532. These targets are enriched for pathways involved in adipogenesis, adipocytokine signalling, energy metabolism, and hypoxia response, and included Leptin, which we further demonstrated to have a decreasing expression with increasing BWP, particularly in male infants. Overall, we have shown a robust and reproducible association of miR-532 with BWP, which could influence BWP through regulation of adipocytokines Leptin and Adiponectin.

Inhibition of microRNA-149 protects against recurrent miscarriage through upregulating RUNX2 and activation of the PTEN/Akt signaling pathway

AIM

Recently, microRNA-149 (miR-149) has been indicated to act as an oncogene or a tumor suppressor in various malignant tumors, while its inner mechanisms in recurrent miscarriage (RM) are still in infancy. Therein, this study intends to decode the mechanism of miR-149 in RM.

METHODS

miR-149 and RUNX2 expression in the chorionic tissues of normal pregnant women and RM patients were first examined, and the correlation between miR-149 and RUNX2 was analyzed. Subsequently, miR-149 was upregulated in HTR-8 cells or downregulated in BEWO cells, and then the changes in biological functions of trophoblasts in RM were detected. Furthermore, the expression of PTEN/Akt signaling pathway-related factors in trophoblasts was detected by western blot analysis.

RESULTS

miR-149 expression was increased while RUNX2 expression was suppressed in RM patients, and miR-149 was negatively correlated with RUNX2. Overexpressed miR-149 induced cell apoptosis and inhibited cell activity, while reduced miR-149 in trophoblasts contributed to opposite experimental results. Moreover, miR-149 promoted the expression of PTEN and inhibited Akt phosphorylation by targeting RUNX2, thereby inhibiting trophoblast activity and promoting their apoptosis.

CONCLUSION

Our study demonstrates that miR-149 knockdown halted the RM development through upregulating RUNX2 and activation of the PTEN/Akt signaling pathway.

The effect of baicalin on microRNA expression profiles in porcine aortic vascular endothelial cells infected by Haemophilus parasuis

Glässer's disease, caused by Haemophilus parasuis (H. parasuis), is associated with vascular damage and vascular inflammation in pigs. Therefore, early assessment and treatment are essential to control the inflammatory disorder. MicroRNAs have been shown to be involved in the vascular pathology. Baicalin has important pharmacological functions, including anti-inflammatory, antimicrobial and antioxidant effects. In this study, we investigated the changes of microRNAs in porcine aortic vascular endothelial cells (PAVECs) induced by H. parasuis and the effect of baicalin in this model by utilizing high-throughput sequencing. The results showed that 155 novel microRNAs and 76 differentially expressed microRNAs were identified in all samples. Subsequently, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of the target genes of the differentially expressed microRNAs demonstrated that regulation of actin cytoskeleton, focal adhesion, ECM-receptor interaction, bacterial invasion of epithelial cells, and adherens junction were the most interesting pathways after PAVECs were infected with H. parasuis. In addition, when the PAVECs were pretreated with baicalin, mismatch repair, peroxisome, oxidative phosphorylation, DNA replication, and ABC transporters were the most predominant signaling pathways. STRING analysis showed that most of the target genes of the differentially expressed microRNAs were associated with each other. The expression levels of the differentially expressed microRNAs were negatively co-regulated with their target genes' mRNA following pretreatment with baicalin in the H. parasuis-induced PAVECs using co-expression networks analysis. This is the first report that microRNAs might have key roles in inflammatory damage of vascular tissue during H. parasuis infection. Baicalin regulated the microRNAs changes in the PAVECs following H. parasuis infection, which may represent useful novel targets to prevent or treat H. parasuis infection.

Identification of Differentially Expressed Genes and Signaling Pathways in Placenta Tissue of Early-Onset and Late-Onset Pre-Eclamptic Pregnancies by Integrated Bioinformatics Analysis

Background

Pre-eclampsia (PE) can be divided into 2 sub-groups: early-onset and late-onset PE. Although these sub-groups show overlapping molecular and cellular mechanisms and similar clinical manifestations, they are regarded as 2 different phenotypes with heterogeneous manifestations. The pathophysiological mechanisms underlying early-onset and late-onset PE still remain unclear. Therefore, the present study aimed to identify the key genes and pathways related to early-onset and late-onset PE, and to investigate the molecular mechanisms that are involved in gene regulation.

Material/Methods

Our analysis involved the Gene Expression Series (GSE) 74341 and GSE22526 from the National Center of Biotechnology Information (NCBI) Gene Expression Omnibus Database. These 2 microarray datasets included 15 patients with early-onset PE and 15 patients with late-onset PE.

Results

Our analyses identified 15 differentially expressed genes (DEGs), including CGA, EGR1, HBB, HBA2, LEP, and LHB. Gene Ontology (GO) functional annotation showed that the biological functions of these DEGs were mainly associated with steroid biosynthetic, oxidative stress, angiogenesis, and sex differentiation. Signaling pathway analyses showed that these DEGs were mainly involved in the prolactin signaling pathway, hormone metabolism, the AMPK signaling pathway, and the FoxO signaling pathway. Protein-protein interaction (PPI) network analysis identified 4 genes with the highest degree of interaction. The hub genes for this selection of DEGS were EGR1, LEP, and HBB.

Conclusions

Integrated bioinformatic analyses provide us with a new approach to further understand the pathophysiology and molecular mechanisms underlying early-onset and late-onset PE. The DEGs identified in this study represent potential biomarkers for the early diagnosis of PE and may provide significant options the treatment of these 2 subtypes of PE.

Umbilical Cord miRNAs in Small-for-Gestational-Age Children and Association With Catch-Up Growth: A Pilot Study

CONTEXT

Catch-up growth in infants who are small for gestational age (SGA) is a risk factor for the development of cardiometabolic diseases in adulthood. The basis and mechanisms underpinning catch-up growth in newborns who are SGA are unknown.

OBJECTIVE

To identify umbilical cord miRNAs associated with catch-up growth in infants who are SGA and study their relationship with offspring's cardiometabolic parameters.

DESIGN

miRNA PCR panels were used to study the miRNA profile in umbilical cord tissue of five infants who were SGA with catch-up (SGA-CU), five without catch-up (SGA-nonCU), and five control infants [appropriate for gestational age (AGA)]. The miRNAs with the smallest nominal P values were validated in 64 infants (22 AGA, 18 SGA-nonCU, and 24 SGA-CU) and correlated with anthropometric parameters at 1 (n = 64) and 6 years of age (n = 30).

RESULTS

miR-501-3p, miR-576-5p, miR-770-5p, and miR-876-3p had nominally significant associations with increased weight, height, weight catch-up, and height catch-up at 1 year, and miR-374b-3p, miR-548c-5p, and miR-576-5p had nominally significant associations with increased weight, height, waist, hip, and renal fat at 6 years. Multivariate analysis suggested miR-576-5p as a predictor of weight catch-up and height catch-up at 1 year, as well as weight, waist, and renal fat at 6 years. In silico studies suggested that miR-576-5p participates in the regulation of inflammatory, growth, and proliferation signaling pathways.

CONCLUSIONS

Umbilical cord miRNAs could be novel biomarkers for the early identification of catch-up growth in infants who are SGA. miR-576-5p may contribute to the regulation of postnatal growth and influence the risk for cardiometabolic diseases associated with a mismatch between prenatal and postnatal weight gain.

MicroRNAs in Uteroplacental Vascular Dysfunction

Pregnancy complications of preeclampsia and intrauterine growth restriction (IUGR) are major causes of maternal and perinatal/neonatal morbidity and mortality. Although their etiologies remain elusive, it is generally accepted that they are secondary to placental insufficiency conferred by both failure in spiral artery remodeling and uteroplacental vascular malfunction. MicroRNAs (miRNAs) are small no-coding RNA molecules that regulate gene expression at the post-transcriptional level. Increasing evidence suggests that miRNAs participate in virtually all biological processes and are involved in numerous human diseases. Differentially expressed miRNAs in the placenta are typical features of both preeclampsia and IUGR. Dysregulated miRNAs target genes of various signaling pathways in uteroplacental tissues, contributing to the development of both complications. In this review, we provide an overview of how aberrant miRNA expression in preeclampsia and IUGR impacts the expression of genes involved in trophoblast invasion and uteroplacental vascular adaptation.

The decreased lncRNA ZEB2-AS1 in pre-eclampsia controls the trophoblastic cell line HTR-8/SVneo's invasive and migratory abilities via the miR-149/PGF axis

Pre-eclampsia (PE) is a pregnancy disease that causes maternal death and threatens the health of newborns. Accumulating evidence has revealed the essential roles of long noncoding RNAs (lncRNAs) in the progression of PE. The present investigation determined lncRNA ZEB2 antisense RNA 1 (ZEB2-AS1) expression in PE and looked into the potential role of ZEB2-AS1 in modulating trophoblastic cell functions. Quantitative real-time polymerase chain reaction evaluated gene expression. Western blot analyzed the placental growth factor (PGF) protein level. Cell counting kit-8 and Transwell invasion assays assessed the proliferative and invasive abilities of placental trophoblast cells, respectively. Wound healing assay determined cell migratory potentials. Dual-luciferase reporter assay assessed the targeting relationship among ZEB2-AS1, miR-149, and PGF. Downregulation of lncRNA ZEB2-AS1 was detected in placentas from patients with PE when compared with those from normal pregnancies. Moreover, ZEB2-AS1 upregulation markedly promoted proliferative, migratory, and invasive potentials in HTR-8/SVneo cells, while knockdown of ZEB2-AS1 had the opposite effects. The effects on HTR-8/SVneo cells mediated by ZEB2-AS1 was correlated with the miR-149/PGF axis. These findings indicate that ZEB2-AS1 contributes to PE progression by affecting cell proliferative and invasive capacities via the miR-149/PGF axis in HTR-8/SVneo cells. In sum, we identified that ZEB2-AS1 was a novel aberrantly expressed lncRNA in the placentas of PE patients and lncRNA ZEB2-AS1 modulated trophoblastic cell line HTR-8/SVneo's proliferative and invasive potentials via targeting the miR-149/PGF axis.

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.

Identification of Key circRNAs/lncRNAs/miRNAs/mRNAs and Pathways in Preeclampsia Using Bioinformatics Analysis

BACKGROUND This study aimed to identify significantly altered circRNAs/lncRNAs/miRNAs/mRNAs pathways in preeclampsia (PE), investigate their target relationships, and determine their biological functions. MATERIAL AND METHODS Base on RNA-seq technique and the GEO database, expression profiles of circRNAs/lncRNAs/miRNAs/mRNAs related to PE were obtained. Differentially expressed RNAs were determined using the Limma package in R. Gene set enrichment analysis (GSEA) was performed using GSEA software (v. 3.0) and illustrated by ClusterProfiler and ggplot2 package in R. DAVID database (v. 6.8) was implemented to analyze functional categories and the association between genes and the corresponding Gene Ontology (GO) classification. The R visualization package GOPlot was used to get a better visualization of the relationships between genes and the selected functional categories. CeRNA networks which visualized the correlations between circRNA/lncRNA-miRNA-mRNA were constructed using Cytoscape software (v. 3.6.0). Targetscan and miRanda database were used to predict target relationships between circRNA/lncRNA-miRNA-mRNA. QRT-PCR and luciferase reporter assay were used to verify the expression and target relationship of has_circ_0088196/LINC01492/miR-100-5p/LIF (leukemia inhibitory factor). RESULTS The jak-stat signaling pathway was activated and miR-100-5p was downregulated in PE compared with normal tissues both in collected placental tissue samples and GEO database. Upregulated LIF, LINC01492, and hsa_circ_0088196 were negatively correlated with miR-100-5p expression and had a targeted relationship with miR-100-5p. CONCLUSIONS miR-100-5p may suppress PE development, while LIF, LINC01492, and hsa_circ_0088196 may promote it though inhibiting miR-100-5p. The jak-stat signaling pathway was activated and involved in PE progression.

Trophoblastic microRNAs are downregulated in a diabetic pregnancy through an inhibition of Drosha

MicroRNAs are promising biological markers for prenatal diagnosis. They regulate placental development and are present in maternal plasma. Maternal metabolic diseases are major risk factors for placental deterioration. We analysed the influence of a maternal insulin-dependent diabetes mellitus on microRNA expression in maternal plasma and in blastocysts employing an in vivo rabbit diabetic pregnancy model and an in vitro embryo culture in hyperglycaemic and hypoinsulinaemic medium. Maternal diabetes led to a marked downregulation of Dicer protein in embryoblast cells and Drosha protein in trophoblast cells. MiR-27b, miR-141 and miR-191 were decreased in trophoblast cells and in maternal plasma of diabetic rabbits. In vitro studies indicate, that maternal hyperglycaemia and hypoinsulinaemia partially contribute to the downregulation of trophoblastic microRNAs. As the altered microRNA expression was detectable in maternal plasma, too, the plasma microRNA signature could serve as an early biological marker for the prediction of trophoblast function during a diabetic pregnancy.

Down-regulated miR-149-5p contributes to preeclampsia via modulating endoglin expression

OBJECTIVE

Endoglin is expressed in human placenta and plays an important role in the pathogenesis of preeclampsia. Dysregulation of microRNAs in placental tissues has been recently suggested to be involved in the pathogenesis of preeclampsia. Until now, few studies have shed light on the correlation between endoglin and microRNAs, the latter of which may regulate the expression of ENG, a gene encoding endoglin, in placenta. In this study, we aim to investigate the regulation of ENG by microRNAs.

STUDY DESIGN

We located the microRNAs that might regulate the expression of ENG. Candidate microRNAs were tested if they had an impact on trophoblast function.

MAIN OUTCOME MEASURES

We compared endoglin expression between normotensive and preeclamptic placentas by using immunohistochemistry and real-time PCR. Downregulated microRNAs in preeclamptic placenta were revealed from a literature review. A bioinformatics assay was performed to predict those that might target ENG. Real-time PCR, Western blotting and dual luciferase assay were used to verify the targeting. The effects of the microRNAs on trophoblasts were evaluated by transwell invasion assay.

RESULTS

The endoglin level was significantly higher in preeclamptic placenta than in normotensive placenta. ENG was validated as the direct target of miR-149-5p and was inversely correlated with it. MiR-149-5p promoted the invasion of trophoblast cells, and this promotion was abrogated by the overexpression of ENG.

CONCLUSIONS

Our findings highlight the importance of miR-149-5p in the pathogenesis of preeclampsia and provide new insight into the development of the disease.

Identification of placental nutrient transporters associated with intrauterine growth restriction and pre-eclampsia

Background

Gestational disorders such as intrauterine growth restriction (IUGR) and pre-eclampsia (PE) are main causes of poor perinatal outcomes worldwide. Both diseases are related with impaired materno-fetal nutrient transfer, but the crucial transport mechanisms underlying IUGR and PE are not fully elucidated. In this study, we aimed to identify membrane transporters highly associated with transplacental nutrient deficiencies in IUGR/PE.

Results

In silico analyses on the identification of differentially expressed nutrient transporters were conducted using seven eligible microarray datasets (from Gene Expression Omnibus), encompassing control and IUGR/PE placental samples. Thereby 46 out of 434 genes were identified as potentially interesting targets. They are involved in the fetal provision with amino acids, carbohydrates, lipids, vitamins and microelements. Targets of interest were clustered into a substrate-specific interaction network by using Search Tool for the Retrieval of Interacting Genes. The subsequent wet-lab validation was performed using quantitative RT-PCR on placentas from clinically well-characterized IUGR/PE patients (IUGR, n = 8; PE, n = 5; PE+IUGR, n = 10) and controls (term, n = 13; preterm, n = 7), followed by 2D-hierarchical heatmap generation. Statistical evaluation using Kruskal-Wallis tests was then applied to detect significantly different expression patterns, while scatter plot analysis indicated which transporters were predominantly influenced by IUGR or PE, or equally affected by both diseases. Identified by both methods, three overlapping targets, SLC7A7, SLC38A5 (amino acid transporters), and ABCA1 (cholesterol transporter), were further investigated at the protein level by western blotting. Protein analyses in total placental tissue lysates and membrane fractions isolated from disease and control placentas indicated an altered functional activity of those three nutrient transporters in IUGR/PE.

Conclusions

Combining bioinformatic analysis, molecular biological experiments and mathematical diagramming, this study has demonstrated systematic alterations of nutrient transporter expressions in IUGR/PE. Among 46 initially targeted transporters, three significantly regulated genes were further investigated based on the severity and the disease specificity for IUGR and PE. Confirmed by mRNA and protein expression, the amino acid transporters SLC7A7 and SLC38A5 showed marked differences between controls and IUGR/PE and were regulated by both diseases. In contrast, ABCA1 may play an exclusive role in the development of PE.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-4518-z) contains supplementary material, which is available to authorized users.

Maternal Circulating microRNAs and Pre-Eclampsia: Challenges for Diagnostic Potential

Pre-eclampsia (PE) is a common hypertensive disorder of pregnancy with a significant impact on maternal and neonatal mortality and morbidity. While the pathogenesis of PE has been well described, identification of a biomarker(s) with robust predictive utility in identifying women at the highest risk of developing the condition has yet to be identified. In the search for diagnostic markers, those that may be obtained from the circulation are preferred alternatives to those derived from organ tissue samples. Because of their stability in plasma, microRNAs (miRNAs) have been explored as biomarkers in a host of disease states, although there is comparably little literature available on the circulating miRNAome of PE. This article provides a narrative review on the current state of knowledge on miRNAs associated with PE. Literature on circulating miRNAs is presented and the challenges to developing the diagnostic and prognostic utility of miRNAs in this context is discussed.

Inflammatory Diseases and Growth: Effects on the GH-IGF Axis and on Growth Plate

This review briefly describes the most common chronic inflammatory diseases in childhood, such as cystic fibrosis (CF), inflammatory bowel diseases (IBDs), juvenile idiopathic arthritis (JIA), and intrauterine growth restriction (IUGR) that can be considered, as such, for the changes reported in the placenta and cord blood of these subjects. Changes in growth hormone (GH) secretion, GH resistance, and changes in the insulin-like growth factor (IGF) system are described mainly in relationship with the increase in nuclear factor-κB (NF-κB) and pro-inflammatory cytokines. Changes in the growth plate are also reported as well as a potential role for microRNAs (miRNAs) and thus epigenetic changes in chronic inflammation. Many mechanisms leading to growth failure are currently known; however, it is clear that further research in the field is still warranted.

Placental Homing Peptide-microRNA Inhibitor Conjugates for Targeted Enhancement of Intrinsic Placental Growth Signaling

Suboptimal placental growth and development are the underlying cause of many pregnancy complications. No treatments are available, primarily due to the risk of causing fetal teratogenicity. microRNAs (miRNAs) are short, non-coding RNA sequences that regulate multiple downstream genes; miR-145 and miR675 have previously been identified as negative regulators of placental growth. In this proof of principle study, we explored the feasibility of delivering miRNA inhibitors to the placentas of pregnant mice and developed novel placental homing peptide-microRNA inhibitor conjugates for targeted enhancement of intrinsic placental growth signalling. Scrambled-, miR-145- or miR-675 inhibitor sequences were synthesised from peptide nucleic acids and conjugated to the placental homing peptide CCGKRK. Intravenous administration of the miR-145- and miR-675 conjugates to pregnant C57BL/6J mice significantly increased fetal and placental weights compared to controls; the miR-675 conjugate significantly reduced placental miR-675 expression. When applied to human first trimester placental explants, the miR-145 conjugate significantly reduced placental miR-145 expression, and both conjugates induced significant enhancement of cytotrophoblast proliferation; no effect was observed in term placental explants. This study demonstrates that homing peptide-miRNA inhibitor conjugates can be exploited to promote placental growth; these novel therapeutics may represent an innovative strategy for targeted treatment of compromised placental development.

Double hit of NEMO gene in preeclampsia

The precise etiology of preeclampsia is unknown. Family studies indicate that both genetic and environmental factors influence its development. One of these factors is NFkB, whose activation depends on NEMO (NFkB essential modulator. This is the first study to investigate the association between the existence of single nucleotide variant of the NEMO gene and the appearance of preeclampsia. A total of 151 women (72 preeclamptic women and 79 controls) and their children were examined. Sanger sequencing was performed to identify variants in the NEMO gene in the preeclamptic mothers. The maternal identified variants were then sought in the studied groups of children, and in the maternal and child controls, using RFLP-PCR. Real-time RT-PCR was performed to assess NEMO gene expression in maternal blood, umbilical cord blood and placentas. The sequencing process indicated the existence of two different variants in the 3'UTR region of the NEMO gene of preeclamptic women (IKBKG:c.*368C>A and IKBKG:c.*402C>T). The simultaneous occurrence of the TT genotype in the mother and the TT genotype in the daughter or a T allele in the son increased the risk of preeclampsia development 2.59 fold. Additionally, we found that the configuration of maternal/fetal genotypes (maternal TT/ daughter TT or maternal TT/son T) of IKBKG:c.*402C/T variant is associated with the level of NEMO gene expression. Our results showed that, the simultaneous occurrence of the maternal TT genotype (IKBKG:c.*402C>T variants) and TT genotype in the daughter or T allele in the son correlates with the level of NEMO gene expression and increases the risk of preeclampsia development. Our observations may offer a new insight into the genetic etiology and pathogenesis of preeclampsia.

Differential microRNA expression in human placentas of term intra-uterine growth restriction that regulates target genes mediating angiogenesis and amino acid transport

Placental insufficiency leading to intrauterine growth restriction (IUGR) demonstrates perturbed gene expression affecting placental angiogenesis and nutrient transfer from mother to fetus. To understand the post-transcriptional mechanisms underlying such placental gene expression changes, our objective was to identify key non-coding microRNAs that express biological function. To this end, we initially undertook microarrays targeting microRNAs in a small sub-set of placentas of appropriate (AGA) versus small for gestational age (SGA) weight infants, and observed up-regulation of 97 miRs and down-regulation of 44 miRs in SGA versus AGA. In a larger cohort of samples (AGA, n = 21; SGA, n = 11; IUGR subset, n = 5), we validated by qRT-PCR differential expression of three specific microRNAs (miR-10b, -363 and -149) that target genes mediating angiogenesis and nutrient transfer. Validation yielded an increase in miR-10b and -363 expression of ~2.5-fold (p<0.02 each) in SGA versus AGA, and of ~3-fold (p<0.005) in IUGR versus AGA, with no significant change despite a trending increase in miR-149. To further establish a cause-and-effect paradigm, employing human HTR8 trophoblast cells, we assessed the effect of nutrient deprivation on miR expression and inhibition of endogenous miRs on target gene expression. In-vitro nutrient deprivation (~50%) increased the expression of miR-10b and miR-149 by 1.5-fold (p<0.02) while decreasing miR-363 (p<0.0001). Inhibition of endogenous miRs employing antisense sequences against miR-10b, -363 and -149 revealed an increase respectively in the expression of the target genes KLF-4 (transcription factor which regulates angiogenesis), SNAT1 and 2 (sodium coupled neutral amino acid transporters) and LAT2 (leucine amino acid transporter), which translated into a similar change in the corresponding proteins. Finally to establish functional significance we performed dual-luciferase reporter assays with 3'-insertion of miR-10b alone and observed a ~10% reduction in the 5'-luciferase activity versus the control. Lastly, we further validated by microarray and employing MirWalk software that the pathways and target genes identified by differentially expressed miRs in SGA/IUGR compared to AGA are consistent in a larger cohort. We have established the biological significance of various miRs that target common transcripts mediating pathways of importance, which are perturbed in the human IUGR placenta.

Maternal plasma miRNAs as biomarkers during mid-pregnancy to predict later spontaneous preterm birth: a pilot study

More than 10% of babies are born too early resulting in over 15 million preterm births and more than one million new-born deaths globally. Although women with a previous spontaneous preterm birth (SPTB) are considered at high risk for recurrence, the majority occur in women without prior history. Prediction of SPTB risk allows for improved care and potential for targeting novel and existing therapeutics to prevent SPTB, which may result in improved outcomes for infant and mother. In this pilot study, a miRNA array was used to analyse plasma from healthy women in their first pregnancy at 20 weeks of gestation who then went on to deliver either at term or experience SPTB at 28-32 weeks. We identified specific miRNA expression profiles that differentiated between those mothers who delivered at term or delivered following SPTB. miR302b, miR1253 and a clustering of miR548 miRNAs were underexpressed in SPTB cases compared to term controls. Conversely, miR223 was elevated in mothers that later experienced a SPTB. The circulating miRNAs identified in the present study may therefore be attractive candidates as non-invasive biomarkers for the early prediction of SPTB. Further larger studies are now warranted to investigate the potential clinical utility of these markers.

Do miRNAs Play a Role in Fetal Growth Restriction? A Fresh Look to a Busy Corner

Placenta is the crucial organ for embryo and fetus development and plays a critical role in the development of fetal growth restriction (FGR). There are increasing evidences on the role of microRNAs (miRNAs) in a variety of pregnancy-related complications such as preeclampsia and FGR. More than 1880 miRNAs have been reported in humans and most of them are expressed in placenta. In this paper, we aimed to review the current evidence about the topic. According to retrieved data, controversial results about placental expression of miRNAs could be due (at least in part) to the different experimental methods used by different groups. Despite the fact that several authors have demonstrated a relatively easy and feasible detection of some miRNAs in maternal whole peripheral blood, costs of these tests should be reduced in order to increase cohorts and have stronger evidence. In this regard, we take the opportunity to solicit future studies on large cohort and adequate statistical power, in order to identify a panel of biomarkers on maternal peripheral blood for early diagnosis of FGR.

Accelerated placental aging in early onset preeclampsia pregnancies identified by DNA methylation

Aim:

To determine whether dynamic DNA methylation changes in the human placenta can be used to predict gestational age.

Materials & methods:

Publicly available placental DNA methylation data from 12 studies, together with our own dataset, using Illumina Infinium Human Methylation BeadChip arrays.

Results & conclusion:

We developed an accurate tool for predicting gestational age of placentas using 62 CpG sites. There was a higher predicted gestational age for placentas from early onset preeclampsia cases, but not term preeclampsia, compared with their chronological age. Therefore, early onset preeclampsia is associated with placental aging. Gestational age acceleration prediction from DNA methylation array data may provide insight into the molecular mechanisms of pregnancy disorders.

Identifying miRNA regulatory mechanisms in preeclampsia by systems biology approaches

BACKGROUND

Preeclampsia (PE) is the major cause of maternal and fetal morbidity and mortality, affecting 3-8% of all pregnancies around the globe. miRNAs are small, noncoding RNA molecules, which negatively regulate gene expression. Abnormally expressed miRNAs contribute to pregnancy complications such as PE. The aim of our study was to find possible regulatory mechanisms by system biology approaches, which are connected to the pathogenesis of PE.

METHODS

We integrated publicly available miRNA and gene expression profiles and created a network from the significant miRNA-mRNA pairs with the help of MAGIA and Cytoscape softwares. Two subnetworks were expanded by adding protein-protein interactions. Differentially expressed miRNAs were identified for the evaluation of their regulatory effect. We analyzed the miRNAs and their targets using different bioinformatics tools and through literature research.

RESULTS

Altogether, 52,603 miRNA-mRNA interactions were generated by the MAGIA web tool. The top 250 interactions were visualized and pairs with q < 0.0001 were analyzed, which included 85 nodes and 80 edges signalizing the connections between 52 regulated genes and 33 miRNAs. A total of 11 of the regulated genes are PE related and 9 of them were targeted by multiple miRNAs. A total of 8 miRNAs were associated with PE before, and 13 miRNAs regulated more than 1 mRNA. Hsa-mir-210 was the highest degree node in the network and its role in PE is well established.

CONCLUSIONS

We identified several miRNA-mRNA regulatory mechanisms which may contribute to the pathogenesis of PE. Further investigations are needed to validate these miRNA-mRNA interactions and to enlighten the possibilities of developing potential therapeutic targets.

Systematic Review of Micro-RNA Expression in Pre-Eclampsia Identifies a Number of Common Pathways Associated with the Disease

Background

Pre-eclampsia (PE) is a complex, multi-systemic condition of pregnancy which greatly impacts maternal and perinatal morbidity and mortality. MicroRNAs (miRs) are differentially expressed in PE and may be important in helping to understand the condition and its pathogenesis.

Methods

Case-control studies investigating expression of miRs in PE were collected through a systematic literature search. Data was extracted and compared from 58 studies to identify the most promising miRs associated with PE pathogenesis and identify areas of methodology which could account for often conflicting results.

Results

Some of the most frequently differentially expressed miRs in PE include miR-210, miR-223 and miR-126/126* which associate strongly with the etiological domains of hypoxia, immunology and angiogenesis. Members of the miR-515 family belonging to the imprinted chromosome 19 miR cluster with putative roles in trophoblast invasion were also found to be differentially expressed. Certain miRs appear to associate with more severe forms of PE such as miR-210 and the immune-related miR-181a and miR-15 families. Patterns of miR expression may help pinpoint key pathways (e.g. IL-6/miR-223/STAT3) and aid in untangling the heterogeneous nature of PE. The detectable presence of many PE-associated miRs in antenatal circulatory samples suggests their usefulness as predictive biomarkers. Further progress in ascertaining the clinical value of miRs and in understanding how they might contribute to pathogenesis is predicated upon resolving current methodological challenges in studies. These include differences in diagnostic criteria, cohort characteristics, sampling technique, RNA isolation and platform-dependent variation in miR profiling.

Conclusion

Reviewing studies of PE-associated miRs has revealed their potential as informants of underlying target genes and pathways relating to PE pathogenesis. However, the incongruity in results across current studies hampers their capacity to be useful biomarkers of the condition.

A curated transcriptome dataset collection to investigate the development and differentiation of the human placenta and its associated pathologies

Compendia of large-scale datasets made available in public repositories provide a precious opportunity to discover new biomedical phenomena and to fill gaps in our current knowledge. In order to foster novel insights it is necessary to ensure that these data are made readily accessible to research investigators in an interpretable format. Here we make a curated, public, collection of transcriptome datasets relevant to human placenta biology available for further analysis and interpretation via an interactive data browsing interface. We identified and retrieved a total of 24 datasets encompassing 759 transcriptome profiles associated with the development of the human placenta and associated pathologies from the NCBI Gene Expression Omnibus (GEO) and present them in a custom web-based application designed for interactive query and visualization of integrated large-scale datasets ( http://placentalendocrinology.gxbsidra.org/dm3/landing.gsp). We also performed quality control checks using relevant biological markers. Multiple sample groupings and rank lists were subsequently created to facilitate data query and interpretation. Via this interface, users can create web-links to customized graphical views which may be inserted into manuscripts for further dissemination, or e-mailed to collaborators for discussion. The tool also enables users to browse a single gene across different projects, providing a mechanism for  developing new perspectives on the role of a molecule of interest across multiple biological states. The dataset collection we created here is available at: http://placentalendocrinology.gxbsidra.org/dm3.

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.