Gene expression profiling reveals different molecular patterns in G-protein coupled receptor signaling pathways between early- and late-onset preeclampsia

Prediction of late-onset preeclampsia using plasma proteomics: a longitudinal multi-cohort study

Preeclampsia is a pregnancy disorder with substantial perinatal and maternal morbidity and mortality. Pregnant women at risk of preeclampsia would benefit from early detection for follow-up, timely interventions and delivery. Several attempts have been made to identify protein biomarkers of preeclampsia, but findings vary with demographics, clinical characteristics, and time of sampling. In the current study, we combined three independent longitudinal pregnancy cohorts (Detroit, Stanford and Oslo) resulting in 124 late-onset preeclampsia (LOPE) cases and 178 gestational age matched controls, and analyzed > 1000 proteins in maternal plasma sampled between 12 and 34 weeks of gestation. Differential abundance analysis of combined protein data revealed increased deviation in protein abundance trajectories throughout gestation in women destined to develop LOPE compared to controls. There were no differentially abundant proteins at time interval T1 (12-19 weeks), yet 31 differentially abundant proteins were found at time interval T2 (19-27 weeks), and 48 proteins at time interval T3 (27- 34 weeks). Multi-protein random forest models assessed via cross-validation predicted LOPE with an area under the ROC curve of 0.72 (0.65-0.78), 0.76 (0.71-0.81) and 0.80 (0.75-0.85) at time interval T1, T2 and T3, respectively. The results at T3 were confirmed using a leave-one-cohort-out analysis suggesting cross-cohort consistency, and at T1 and T2 when the largest two cohorts were used as training sets.

Integrated bioinformatics analysis reveals that CCBP2 and GPR87 are new GPCR-associated biomarkers for preeclampsia

BACKGROUND

Preeclampsia (PE) is a multifaceted pregnancy syndrome marked by multiple system involvement and a significant contributor to maternal mortality. This condition is characterized by a critical lack of early diagnostic measures and viable therapeutic options, underscoring an urgent need for the identification of reliable markers with both diagnostic and therapeutic potential.

METHODS

This study utilized Weighted Gene Co-expression Network Analysis (WGCNA) to explore the role of G protein-coupled receptors (GPCRs) in the pathogenesis of PE.

RESULTS

Our analysis pinpointed CCBP2 (ACKR2) and GPR87 as central PE-associated GPCRs. Experimental validation of these findings revealed that both CCBP2 and GPR87 significantly inhibit the proliferation, migration, and invasion of trophoblast cells-core phenomena underlying the pathology of PE.

CONCLUSION

Thus, our findings add valuable candidates to the growing list of biomarkers for preeclampsia and offer promising targets for future therapeutic development.

Detection and assessment of immune and stromal related risk genes to predict preeclampsia: A bioinformatics analysis with dataset

This study aimed to investigate immune score and stromal score-related signatures associated with preeclampsia (PE) and identify key genes for diagnosing PE using bioinformatics analysis. Four microarray datasets, GSE75010, GSE25906, GSE44711, and GSE10588 were obtained from the Gene Expression Omnibus database. GSE75010 was utilized for differential expressed gene (DEGs) analysis. Subsequently, bioinformatic tools such as gene ontology, Kyoto Encyclopedia of Genes and Genomes, weighted gene correlation network analysis, and gene set enrichment analysis were employed to functionally characterize candidate target genes involved in the pathogenesis of PE. The least absolute shrinkage and selection operator regression approach was employed to identify crucial genes and develop a predictive model. This method also facilitated the creation of receiver operating characteristic (ROC) curves, enabling the evaluation of the model's precision. Furthermore, the model underwent external validation through the other three datasets. A total of 3286 DEGs were identified between normal and PE tissues. Gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses revealed enrichments in functions related to cell chemotaxis, cytokine binding, and cytokine-cytokine receptor interaction. weighted gene correlation network analysis identified 2 color modules strongly correlated with immune and stromal scores. After intersecting DEGs with immune and stromal-related genes, 13 genes were selected and added to the least absolute shrinkage and selection operator regression. Ultimately, 7 genes were screened out to establish the risk model for discriminating preeclampsia from controls, with each gene having an area under the ROC curve >0.70. The constructed risk model demonstrated that the area under the ROC curves in internal and the other three external datasets were all greater than 0.80. A 7-gene risk signature was identified to build a potential diagnostic model and performed well in the external validation group for PE patients. These findings illustrated that immune and stromal cells played essential roles in PE during its progression.

Bioinformatic Analysis Identifies Potential Extracellular Matrix Related Genes in the Pathogenesis of Early Onset Preeclampsia

Early-onset preeclampsia (EOPE) is a complex pregnancy complication that poses significant risks to the health of both mothers and fetuses, and research on its pathogenesis and pathophysiology remains insuffcient. This study aims to explore the role of candidate genes and their potential interaction mechanisms in EOPE through bioinformatics analysis techniques. Two gene expression datasets, GSE44711 and GSE74341, were obtained from the Gene Expression Omnibus (GEO) to identify differentially expressed genes (DEGs) between EOPE and gestational age-matched preterm control samples. Functional enrichment analysis was performed utilizing the kyoto encyclopedia of genes and genomes (KEGG), gene ontology (GO), and gene set enrichment analysis (GSEA). A protein-protein interaction (PPI) network was constructed using the STRING database, and hub DEGs were identified through Cytoscape software and comparative toxicogenomics database (CTD) analysis. Furthermore, a diagnostic logistic model was established using these hub genes, which were confirmed through reverse transcription polymerase chain reaction (RT-PCR). Finally, immune cell infiltration was analyzed using CIBERSORT. In total, 807 DEGs were identified in the GSE44711 dataset (451 upregulated genes and 356 downregulated genes), and 787 DEGs were identified in the GSE74341 dataset (446 upregulated genes and 341 downregulated genes). These DEGs were significantly enriched in various molecular functions such as extracellular matrix structural constituent, receptor-ligand activity binding, cytokine activity, and platelet-derived growth factor. KEGG and GSEA annotation revealed significant enrichment in pathways related to ECM-receptor interaction, PI3K-AKT signaling, and focal adhesion. Ten hub genes were identified through the CytoHubba plugin in Cytoscape. Among these hub genes, three key DEGs (COL1A1, SPP1, and THY1) were selected using CTD analysis and various topological methods in Cytoscape. The diagnostic logistic model based on these three genes exhibited high efficiency in predicting EOPE (AUC = 0.922). RT-PCR analysis confirmed the downregulation of these genes in EOPE, and immune cell infiltration analysis suggested the significant role of M1 and M2 macrophages in EOPE. In conclusion, this study highlights the association of three key genes (COL1A1, SPP1, and THY1) with EOPE and their contribution to high diagnostic efficiency in the logistic model. Additionally, it provides new insights for future research on EOPE and emphasizes the diagnostic value of these identified genes. More research is needed to explore their functional and diagnostic significance in EOPE.

Down-regulated Wnt7a and GPR124 in early-onset preeclampsia placentas reduce invasion and migration of trophoblast cells

OBJECTIVES

Preeclampsia (PE) is a disease specific to pregnancy that causes 9-10 % of maternal deaths. Early-onset PE (<34 weeks' gestation) is the most dangerous category of PE. Wnt7a and GPR124 (G protein-coupled receptor 124) are widely expressed in the human reproductive process. Especially during embryogenesis and tumorigenesis, Wnt7a plays a crucial role. However, few studies have examined the association between Wnt7a-GPR124 and early-onset PE. The aim of this study was to examine the significance of Wnt7a and GPR124 in early-onset PE as well as Wnt7a's role in trophoblast cells.

METHODS

Immunohistochemistry (IHC), real-time PCR, and western blotting (WB) were used to investigate Wnt7a and GPR124 expression in normal and early-onset PE placentas. Additionally, FACS, Transwell, and CCK-8 assays were used to diagnose Wnt7a involvement in migration, invasion, and proliferation.

RESULTS

In the early-onset PE group, Wnt7a and GPR124 expression was significantly lower than in the normal group, especially in the area of syncytiotrophoblasts (STBs) and extravillous trophoblasts (EVTs). A negative correlation was found between Wnt7a RNA and GPR124 expression (r=-0.42, p<0.01). However, the Wnt7a RNA expression level was positive correlated with PE severity. In further cellular functional experiments, knockdown of Wnt7a inhibits HTR8/SVeno cells invasion and migration but has little effect on proliferation and apoptosis.

CONCLUSIONS

Through the Wnt pathway, Wnt7a regulates trophoblast cell invasion and migration, and may contribute to early-onset preeclampsia pathogenesis. A molecular level study of Wnt7a will be needed to find downstream proteins and mechanisms of interaction.

Genome-wide association study reveals HSF2, GJA1 and TRIM36 as susceptibility genes for preeclampsia: a community-based population study in Tianjin, China

BACKGROUND

Preeclampsia (PE) mainly occurs in pregnant women and is hereditary. Several genome-wide association studies (GWAS) on Caucasian samples have reported some gene loci that are associated with preeclampsia. However, these studies have not reached consistent conclusions. No previous GWAS has examined preeclampsia in the Chinese Han population.

METHOD

This study aimed to identify common genetic variations associated with preeclampsia in the Chinese Han population through two-stage case‒control studies. The discovery cohort included 92 patients with severe preeclampsia and 187 healthy controls. The validation cohort included 52 patients with preeclampsia and 104 controls. A genome-wide association study was performed to identify putative preeclampsia genes in the discovery cohort, with validation in the validation cohort.

RESULTS

In the discovery cohort, GWAS demonstrated that 19 single-nucleotide polymorphisms (SNPs) were associated with preeclampsia (P < 10-5). The pathway analysis revealed that these 19 SNP representative genes were mainly enriched in the adenylyl cyclase-inhibiting G-protein coupled receptor signaling pathway. After validation in the validation cohort, rs13176432 and rs13210237 remained closely related to preeclampsia (P<0.05). In the combined data set, the frequency of the G allele in rs13176432 was significantly higher in cases with preeclampsia than in controls (P = 5 × 10-6). The frequency of the A allele in rs13210237 was higher in the preeclampsia group (P = 8 × 10-6). The rs13210237 representative genes include HSF2 and GJA1, while the rs13176432 representative gene is TRIM36. There were no differences in genotype distribution between the early-onset and late-onset preeclampsia groups (P > 0.05). Furthermore, rs13210237 and rs13176432 were related to preeclampsia in the adjusted regression model (P < 0.000).

CONCLUSION

In this study of two independent cohorts, we found that rs13210237 and rs13176432 might be novel preeclampsia-susceptible genetic factors in the Han population in China. However, there was no association between the onset of preeclampsia and these genotypes.

Elevated expression of glycolytic genes as a prominent feature of early-onset preeclampsia: insights from integrative transcriptomic analysis

Introduction: Preeclampsia (PE), a notable pregnancy-related disorder, leads to 40,000+ maternal deaths yearly. Recent research shows PE divides into early-onset (EOPE) and late-onset (LOPE) subtypes, each with distinct clinical features and outcomes. However, the molecular characteristics of various subtypes are currently subject to debate and are not consistent. Methods: We integrated transcriptomic expression data from a total of 372 placental samples across 8 publicly available databases via combat algorithm. Then, a variety of strategies including Random Forest Recursive Feature Elimination (RF-RFE), differential analysis, oposSOM, and Weighted Correlation Network Analysis were employed to identify the characteristic genes of the EOPE and LOPE subtypes. Finally, we conducted in vitro experiments on the key gene HK2 in HTR8/SVneo cells to explore its function. Results: Our results revealed a complex classification of PE placental samples, wherein EOPE manifests as a highly homogeneous sample group characterized by hypoxia and HIF1A activation. Among the core features is the upregulation of glycolysis-related genes, particularly HK2, in the placenta-an observation corroborated by independent validation data and single-cell data. Building on the pronounced correlation between HK2 and EOPE, we conducted in vitro experiments to assess the potential functional impact of HK2 on trophoblast cells. Additionally, the LOPE samples exhibit strong heterogeneity and lack distinct features, suggesting a complex molecular makeup for this subtype. Unsupervised clustering analysis indicates that LOPE likely comprises at least two distinct subtypes, linked to cell-environment interaction and cytokine and protein modification functionalities. Discussion: In summary, these findings elucidate potential mechanistic differences between the two PE subtypes, lend support to the hypothesis of classifying PE based on gestational weeks, and emphasize the potential significant role of glycolysis-related genes, especially HK2 in EOPE.

Identification of key genes in the pathogenesis of preeclampsia via bioinformatic analysis and experimental verification

Background

Preeclampsia (PE) is the primary cause of perinatal maternal-fetal mortality and morbidity. The exact molecular mechanisms of PE pathogenesis are largely unknown. This study aims to identify the hub genes in PE and explore their potential molecular regulatory network.

Methods

We downloaded the GSE148241, GSE190971, GSE74341, and GSE114691 datasets for the placenta and performed a differential expression analysis to identify hub genes. We performed Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), Disease Ontology (DO), Gene Set Enrichment Analysis (GSEA), and Protein-Protein Interaction (PPI) Analysis to determine functional roles and regulatory networks of differentially expressed genes (DEGs). We then verified the DEGs at transcriptional and translational levels by analyzing the GSE44711 and GSE177049 datasets and our clinical samples, respectively.

Results

We identified 60 DEGs in the discovery phase, consisting of 7 downregulated genes and 53 upregulated genes. We then identified seven hub genes using Cytoscape software. In the verification phase, 4 and 3 of the seven genes exhibited the same variation patterns at the transcriptional level in the GSE44711 and GSE177049 datasets, respectively. Validation of our clinical samples showed that CADM3 has the best discriminative performance for predicting PE.

Conclusion

These findings may enhance the understanding of PE and provide new insight into identifying potential therapeutic targets for PE.

Identification and validation of an angiogenesis-related signature associated with preeclampsia by bioinformatic analysis

Preeclampsia (PE) is a pregnancy disorder with high morbidity and mortality rates for both mothers and newborns. This study explores potential diagnostic indicators of PE. We downloaded the messenger ribonucleic acid profiles of the GSE75010 dataset from the Gene Expression Omnibus database, and used placenta samples to carry out different analyses including differential expression, Gene Ontology, and Kyoto Encyclopedia of Genes and Genomes analyses. Least absolute shrinkage and selection operator regression was constructed and the receiver operating characteristic curve was drawn to evaluate the accuracy of the model. An external validation was conducted to prove the stability of the risk model. We found 140 angiogenesis-related genes and identified 29 angiogenesis-related genes between the 2 groups, including 12 upregulated genes and 17 downregulated genes. In addition, we established a 12-gene risk signature, which has a high accuracy in predicting PE during pregnancy (area under curve = 0.90). The immune infiltration characteristics are differentially distributed in the 2 groups, which may be the cause of hypertension during pregnancy. The external validation with the GSE25906 dataset confirmed the high accuracy of our model (area under curve = 0.87). Our results outline the characteristics of a set of genes potentially involved in PE and its subgroups, contributing to a better understanding of the molecular mechanisms of PE.

Focusing on the role of secretin/adhesion (Class B) G protein-coupled receptors in placental development and preeclampsia

Preeclampsia, a clinical syndrome mainly characterized by hypertension and proteinuria, with a worldwide incidence of 3–8% and high maternal mortality, is a risk factor highly associated with maternal and offspring cardiovascular disease. However, the etiology and pathogenesis of preeclampsia are complicated and have not been fully elucidated. Obesity, immunological diseases and endocrine metabolic diseases are high-risk factors for the development of preeclampsia. Effective methods to treat preeclampsia are lacking, and termination of pregnancy remains the only curative treatment for preeclampsia. The pathogenesis of preeclampsia include poor placentation, uteroplacental malperfusion, oxidative stress, endoplasmic reticulum stress, dysregulated immune tolerance, vascular inflammation and endothelial cell dysfunction. The notion that placenta is the core factor in the pathogenesis of preeclampsia is still prevailing. G protein-coupled receptors, the largest family of membrane proteins in eukaryotes and the largest drug target family to date, exhibit diversity in structure and function. Among them, the secretin/adhesion (Class B) G protein-coupled receptors are essential drug targets for human diseases, such as endocrine diseases and cardiometabolic diseases. Given the great value of the secretin/adhesion (Class B) G protein-coupled receptors in the regulation of cardiovascular system function and the drug target exploration, we summarize the role of these receptors in placental development and preeclampsia, and outlined the relevant pathological mechanisms, thereby providing potential drug targets for preeclampsia treatment.

Elevated trophoblastic Siglec6 contributes to the impairment of vascular endothelial cell functions by downregulating Wnt6/β-catenin signaling in preeclampsia

Preeclampsia (PE), a systemic vascular disorder, is the leading cause of maternal and perinatal morbidity and mortality, and its pathogenesis has yet to be fully elucidated. Siglec6, a transmembrane protein, is highly expressed in human placental trophoblasts, and previous studies have shown that Siglec6 overexpression correlates with PE, but the role of Siglec6 during PE progression is unknown. Here, we demonstrated that the mRNA and protein expression levels of Siglec6 were upregulated in early-onset PE placentas compared with uncomplicated pregnancies, and Siglec6 was primarily located in syncytiotrophoblasts (STBs) and extravillous trophoblasts (EVTs). Moreover, our results showed that chemical reagent-induced HIF-1α accumulation promoted the mRNA and protein levels of Siglec6 in HTR8/SVneo and BeWo cells. Although Siglec6 overexpression did not affect HTR8/SVneo cell proliferation, migration, and invasion, the conditional medium derived from the Siglec6 overexpressed HTR8/SVneo cells (Siglec6-OE-CM) significantly impaired the proliferation, migration, invasion, and tube formation of human umbilical vein endothelial cells (HUVECs). Subsequently, the transcriptome sequencing results revealed that Siglec6 overexpression led to the downregulation of Wnt6 in HTR8/SVneo cells, which was further confirmed by qPCR and ELISA. Recombinant human Wnt6 reversed Siglec6-OE-CM-mediated suppression of HUVEC functions by reactivating the Wnt/β-catenin signaling pathway. Altogether, our study found that elevated trophoblastic Siglec6 contributed to the impairment of vascular endothelial cell functions by downregulating Wnt6/β-catenin signaling.

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.

Potential biomarkers and molecular mechanisms in preeclampsia progression

This study aimed to explore potential biomarkers and molecular mechanisms in preeclampsia (PE) progression. Gene expression profiles of GSE147776 and GSE96984 were downloaded, followed by the identification of common differentially expressed genes (co-DEGs) and common differentially expressed lncRNAs (co-DElncRNAs) in PE patients between the two datasets. Key genes were identified using gene set enrichment analysis (GSEA), followed by functional enrichment analyses. Subsequently, the miRNAs of key genes and miRNA-related lncRNAs were predicted, followed by the construction of the lncRNA–miRNA–gene ceRNA network. Furthermore, the key genes associated with different gestational stages were identified. As a result, 192 co-DEGs and 16 co-DElncRNAs were revealed from the two datasets. Based on two outstanding PE-associated pathways, including glaucoma and PE, identified by GSEA, ten key genes, including IGFBP1, CORIN, and C3, were revealed. Key genes, including IL1A and IL1B, were enriched in the developmental process involved in reproduction. Furthermore, ceRNAs, such as LINC00473-miR-4476-IL1A, LINC00473-miR-1291-IL1B, and NAV2-AS4-miR-6131-REN, were identified. Moreover, REN expression was significantly upregulated in the first- and second-trimester placentae compared to C-section-term placentae. In conclusion, these key genes may serve as novel biomarkers for PE. The detection of REN expression may help in the early prediction of PE and the initiation of prophylactic medical treatment.

Expression profiles and functions of ferroptosis-related genes in the placental tissue samples of early- and late-onset preeclampsia patients

Background

The accumulation of reactive oxygen species (ROS) resulting from upregulated levels of oxidative stress is commonly implicated in preeclampsia (PE). Ferroptosis is a novel form of iron-dependent cell death instigated by lipid peroxidation that likely plays an important role in PE pathogenesis. This study aimed to investigate the expression profiles and functions of ferroptosis-related genes (FRGs) in early-onset preeclampsia (EOPE) and late-onset preeclampsia (LOPE).

Methods

Gene expression data and clinical information were downloaded from the Gene Expression Omnibus (GEO) database. The “limma” R package was used to screen differentially expressed genes. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and protein–protein interaction (PPI) network analyses were conducted to investigate the bioinformatics functions and molecular interactions of significantly different FRGs. Quantitative reverse transcription polymerase chain reaction (RT-qPCR) was used to verify the expression of hub FRGs in PE.

Results

A total of 4215 differentially expressed genes (DEGs) were identified between EOPE and preterm cases while 556 DEGs were found between LOPE and term controls. Twenty significantly different FRGs were identified in EOPE subtypes, while only 3 FRGs were identified in LOPE subtypes. Functional enrichment analysis revealed that the differentially expressed FRGs were mainly involved in EOPE and enriched in hypoxia- and iron-related pathways, such as the response to hypoxia, iron homeostasis and iron ion binding process. PPI network analysis and verification by RT-qPCR resulted in the identification of the following five FRGs of interest: FTH1, HIF1A, FTL, MAPK8 and PLIN2.

Conclusions

EOPE and LOPE have distinct underlying molecular mechanisms, and ferroptosis may be mainly implicated in the pathogenesis of EOPE. Further studies are necessary for deeper inquiry into placental ferroptosis and its role in the pathogenesis of EOPE.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04423-6.

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.

Upregulation of miR-29a suppressed the migration and invasion of trophoblasts by directly targeting LOXL2 in preeclampsia

OBJECTIVE

Preeclampsia is a pregnancy-specific disorder that is a major cause of maternal and foetal morbidity and mortality, with a prevalence of 6-8% of pregnancies. Although the downregulation of lysyl oxidase (LOX) and LOX-like protein 2 (LOXL2), which leads to reduced trophoblast cell migration and invasion through activation of the TGF-β1/Smad3/collagen pathway, is relevant to preeclampsia, the mechanisms regulating differences in the gene expression of LOX and LOXL2 in placentas are not yet understood. This study aimed to investigate the mechanisms regulating differences in the gene expression of LOX and LOXL2 in placentas.

METHODS

The expression of miRNAs, LOX and LOXL2 in preeclamptic placentas and control placentas was analysed by qPCR. Localisation of miR29a and LOXL2 in preeclamptic placentas was performed by RNA-Fluorescence in-situ hybridization assay. The direct regulation of LOXL2 by miR-29a was assessed by dual-luciferase reporter assays in human extravillous trophoblast cells (HTR8/SVneo). Cell migration and invasion were evaluated by Transwell assays in HTR8/SVneo cells.

RESULTS

miR-29a expression was upregulated in preeclamptic placentas and negatively correlated with LOXL2 mRNA expression levels. RNA-Fluorescence in-situ hybridization assay revealed a clear overlap between miR-29a and LOXL2 in the placentas of preeclampic women. LOXL2 was a direct target gene of miR-29a, as confirmed by a dual-luciferase reporter assay in HTR8/SVneo trophoblast cells. miR-29a suppressed HTR8/SVneo trophoblast cell migration and invasion. LOXL2 overexpression reversed the inhibitory effects of miR-29a on HTR8/SVneo trophoblast cell migration and invasion.

CONCLUSION

Our results suggest that the upregulation of miR-29a suppresses the migration and invasion of HTR8/SVneo trophoblast cells by directly targeting LOXL2 in preeclampsia.

Identification of potential crucial genes associated with early-onset preeclampsia via bioinformatic analysis

INTRODUCTION

Early-onset preeclampsia is a pregnancy complication associated with high maternal and perinatal morbidity, mortality. Intense efforts have been made to elucidate the pathogenesis, but the molecular mechanism is still elusive. This study aimed to identify potential key genes related to early-onset preeclampsia, and to obtain a better understanding of the molecular mechanisms of this disease.

METHODS

We performed a multi-step integrative bioinformatics analysis of microarray dataset GSE74341 downloaded from Gene Expression Omnibus (GEO) database including 7 early-onset preeclampsia and 5 gestational age matched normotensive controls. The differentially expressed genes (DEGs) were identified using the "limma" package, and their potential functions were predicted by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. Furthermore, the protein-protein interaction network (PPI) was obtained from the STRING database and the PPI network was visualized by Cytoscape software. Then, hub modules and hub genes were screened out from the PPI network, and enrichment analysis was performed for them. Also, validation of hub genes expression in early-onset PE was down by using microarray dataset GSE44711.

RESULTS

A total of 628 DEGs (256 down- and 372 up-regulated) were identified in early-onset PE compared to controls. A total of 4 significant hub modules and 26 significant hub genes were identified.

CONCLUSION

In conclusion, the DEGs related to cell-cell or cell-extracellular matrix interaction (ITGA5, SPP1, LUM, VCAN, APP), placenta metabolic or oxidative stress (CCR7, NT5E, CYBB) were predicted to be newly potential crucial genes that may play significant roles in the pathogenesis of early-onset PE.

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.

Association study of hypertension susceptibility genes ITGA9, MOV10, and CACNB2 with preeclampsia in Chinese Han population

OBJECTIVE

Preeclampsia (PE) is a disorder that occurs during the pregnancy and could affect the maternal and perinatal mortality as well as morbidity. The aim of our study is to investigate the associations between the hypertension susceptibility genes ITGA9, MOV10 and CACNB2 with PE in Chinese Han population.

METHODS

A case-control study including 178 PE patients and 202 healthy controls was conducted to assess the associations between three loci (ITGA9 rs155524, MOV10 rs2932538 and CACNB2 rs4373814) and PE. The TaqMan probe assay was applied for genotyping in our study. Quantitative real-time PCR was performed to detect the mRNA expression levels of ITGA9, MOV10 and CACNB2. ELISA was carried out to detect the concentration of serum sFlt-1 or PLGF.

RESULTS

Our study detected no significant differences in allelic frequencies of three SNPs between PE patients and healthy controls. In the genetic model, the results showed that the patients with ITGA9 rs155524 GA or AA genotypes had a higher risk of PE development compared to those with GG genotype in codominant model. And PE patients had a higher frequency of GA + AA genotypes based on the dominant model. Subgroup analysis showed ITGA9 rs155524 was associated with early-onset PE but not with late-onset PE. No association was observed between MOV10 and CACNB2 with PE in any genetic model and subgroup analysis. Quantitative real-time PCR results showed that ITGA9 mRNA expression level was apparently increased in the placental tissues of PE patients. In addition, ITGA9 expression levels of GA + AA subjects were apparently higher than that in the genotype GG of placental tissues. sFlt-1/PLGF ratio was higher in GA + AA subjects than that in GG subjects. Regression analysis revealed that ratio of sFlt-1/PLGF was positively correlated with ITGA9 mRNA expression level.

CONCLUSION

This study has identified ITGA9 is a promising candidate susceptibility gene for early-onset PE. Our findings demonstrated that the high expression of ITGA9 might be associated with an increased risk of PE.

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

Objectives

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

Materials and Methods

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

Results

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

Conclusion

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

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.

Integrated analysis of the transcriptome-wide m6A methylome in preeclampsia and healthy control placentas

N6-methyladenosine (m6A) is the most prevalent modification in eukaryotic mRNA and potential regulatory functions of m6A have been shown by mapping the RNA m6A modification landscape. m6A modification in active gene regulation manifests itself as altered methylation profiles. The number of reports regarding to the profiling of m6A modification and its potential role in the placenta of preeclampsia (PE) is small. In this work, placental samples were collected from PE and control patients. Expression of m6A-related genes was investigated using quantitative real-time PCR. MeRIP-seq and RNA-seq were performed to detect m6A methylation and mRNA expression profiles. Gene ontology (GO) functional and Kyoto encyclopedia of genes and genomes (KEGG) pathway analyses were also conducted to explore the modified genes and their clinical significance. Our findings show that METTL3 and METTL14 were up-regulated in PE. In total, 685 m6A peaks were differentially expressed as determined by MeRIP-seq. Altered peaks of m6A-modified transcripts were primarily associated with nitrogen compound metabolic process, positive regulation of vascular-associated smooth muscle cell migration, and endoplasmic reticulum organisation. The m6A hyper-methylated genes of Wnt/β-catenin signalling pathway, mTOR signalling pathway, and several cancer-related pathways may contribute to PE. We also verified that the significant increase of HSPA1A mRNA and protein expression was regulated by m6A modification, suggesting m6A plays a key role in the regulation of gene expression. Our data provide novel information regarding m6A modification alterations in PE and help our understanding of the pathogenesis of PE.

Hydroxychloroquine may be beneficial in preeclampsia and recurrent miscarriage

Recurrent miscarriage (RM) and vasculoplacental disorders, such as preeclampsia (PE), affect women of childbearing age worldwide. Vascular endothelial dysfunction and immunological impairment are associated with both RM and PE. To date, there is no effective or optimal therapeutic approach for these conditions. Notably, aspirin use is only partially effective in the prevention of PE. Hydroxychloroquine (HCQ) has demonstrated beneficial effects on disease flares, pregnancy outcomes and cardiovascular impairment in systemic erythaematosus lupus (SLE) through its immunomodulatory, vasculoprotective and antithrombotic properties. Here, in the context of the underlying physiological dysregulation associated with PE and RM, the beneficial properties and potential therapeutic efficacy of HCQ are reviewed in anticipation of the results of current and future trials. Two related trials addressing RM in the absence of maternal autoimmune disease are ongoing. Other trials addressing pregnancy outcomes in the presence of maternal autoimmune disease are forthcoming. In this review, we hypothesise that the immunological and endothelial effects of HCQ may be beneficial in the context of PE and RM, regardless of the maternal autoimmune status.

Gene expression of four targets in situ of the first trimester maternal-fetoplacental interface

EPAS1, FSTL3, IGFBP1, and SEMA3C were localized to determine whether expression is decidual, trophoblastic, or both in the human first trimester maternal-fetoplacental interface. Identified on global genome-wide microarray analysis of chorionic villus sampling tissues in preclinical preeclampsia, these targets were predicted to interact by bioinformatics pathways analysis. In situ hybridization (ISH) with mRNA of each gene was conducted in 10 cases of archived first trimester termination tissues. Randomly selected areas of cells by tissue type yielded the relative proportion of cells expressing mRNA signal in decidual and fetoplacental sites. Data were analyzed using Shapiro-Wilk and Kruskal-Wallis tests (p ≤ .05). The average gestational age was 10.2 weeks. Expression signal for each gene differed by cell type (p < .001). FSTL3 expression was 17 times higher in cells of anchoring columns than areas of decidua without ISH signal. SEMA3C was three times higher in cells of anchoring columns than in decidua. EPAS1 was 1.31 times higher in cells of anchoring columns than in areas of decidua. IGFBP1 was 20 times higher in some decidua versus cells in anchoring columns or villous trophoblast. While all targets were expressed by both maternal and fetoplacental cells, our localizations identified which compartment had relatively higher expression of each gene.

Pre-eclampsia: pathophysiology and clinical implications

Pre-eclampsia is a common disorder that particularly affects first pregnancies. The clinical presentation is highly variable but hypertension and proteinuria are usually seen. These systemic signs arise from soluble factors released from the placenta as a result of a response to stress of syncytiotrophoblast. There are two sub-types: early and late onset pre-eclampsia, with others almost certainly yet to be identified. Early onset pre-eclampsia arises owing to defective placentation, whilst late onset pre-eclampsia may center around interactions between normal senescence of the placenta and a maternal genetic predisposition to cardiovascular and metabolic disease. The causes, placental and maternal, vary among individuals. Recent research has focused on placental-uterine interactions in early pregnancy. The aim now is to translate these findings into new ways to predict, prevent, and treat pre-eclampsia.

Sexual Dimorphisms of Preeclampsia-Dysregulated Transcriptomic Profiles and Cell Function in Fetal Endothelial Cells

Preeclampsia impairs fetoplacental vascular function and increases risks of adult-onset cardiovascular disorders in children born to preeclamptic mothers, implicating that preeclampsia programs fetal vasculature in utero. However, the underlying mechanisms remain elusive. We hypothesize that preeclampsia alters fetal endothelial gene expression and disturbs cytokines- and growth factors-induced endothelial responses. RNA sequencing analysis was performed on unpassaged human umbilical vein endothelial cells (HUVECs) from normotensive and preeclamptic pregnancies. Functional assays for endothelial monolayer integrity, proliferation, and migration were conducted on passage 1 HUVECs from normotensive and preeclamptic pregnancies. Compared with normotensive cells, 926 and 172 genes were dysregulated in unpassaged female and male HUVECs from preeclamptic pregnancies, respectively. Many of these preeclampsia-dysregulated genes are associated with cardiovascular diseases (eg, heart failure) and endothelial function (eg, cell migration, calcium signaling, and endothelial nitric oxide synthase signaling). TNF (tumor necrosis factor)-α-, TGF (transforming growth factor)-β1-, FGF (fibroblast growth factor)-2-, and VEGFA (vascular endothelial growth factor A)-regulated gene networks were differentially disrupted in unpassaged female and male HUVECs from preeclamptic pregnancies. Moreover, preeclampsia decreased endothelial monolayer integrity in responses to TNF-α in both female and male HUVECs. Preeclampsia decreased TGF-β1-strengthened monolayer integrity in female HUVECs, whereas it enhanced FGF-2-strengthened monolayer integrity in male HUVECs. Preeclampsia promoted TNF-α-, TGF-β1-, and VEGFA-induced cell proliferation in female, but not in male HUVECs. Preeclampsia inhibited TNF-α-induced cell migration in female HUVECs, but had an opposite effect on male HUVECs. In conclusion, preeclampsia differentially dysregulates cardiovascular diseases- and endothelial function-associated genes/pathways in female and male fetal endothelial cells in association with the sexual dimorphisms of preeclampsia-dysregulated fetal endothelial function.

GPCRomics: An Approach to Discover GPCR Drug Targets

G protein-coupled receptors (GPCRs) are targets for ∼35% of approved drugs but only ∼15% of the ∼800 human GPCRs are currently such targets. GPCRomics, the use of unbiased, hypothesis-generating methods [e.g., RNA-sequencing (RNA-seq)], with tissues and cell types to identify and quantify GPCR expression, has led to the discovery of previously unrecognized GPCRs that contribute to functional responses and pathophysiology and that may be therapeutic targets. The combination of GPCR expression data with validation studies (e.g., signaling and functional activities) provides opportunities for the discovery of disease-relevant GPCR targets and therapeutics. Here, we review insights from GPCRomic approaches, gaps in knowledge, and future directions by which GPCRomics can advance GPCR biology and the discovery of new GPCR-targeted drugs.

Downregulated low-density lipoprotein receptor-related protein 6 induces the maldevelopment of extravillous trophoblast via Wnt/β-catenin signaling pathway

Preeclampsia (PE), a special type of hypertensive disorder complicating pregnancy (HDCP), is highly associated with the migratory and invasive capacity of extravillous trophoblasts (EVTs). Here, we aimed to study the functions of low-density lipoprotein receptor-related protein 6 (LRP6) in PE pathogenesis. A comparative analysis of cellular gene expressions between placenta tissues collected from PE patients and normal pregnant women showed that the expressions of LRP6, β-catenin and matrix metallopeptidases/TIMP metallopeptidase inhibitors (MMPs/TIMPs) ratio in placentas of PE patients were much lower than the normal. Then, we constructed and transfected LRP6 siRNA (siLRP6) and LRP6 overexpression vectors into HTR6/SVneo cells. On the contrary to siLRP6, LRP6 overexpression could significant enhance cell viability, and strengthen the abilities of cell migration and invasion. Importantly, the overexpression of LRP6 could induce the upregulation of MMP-2 and MMP-9 levels, and downregulation of TIMPs. The mRNA and protein levels of β-catenin, an intracellular signal transducer of Wnt signaling pathway, were significantly up-regulated under the effects of LRP6 overexpression. XAV939, a Wnt/β-catenin pathway inhibitor, was introduced to confirm the involvement of Wnt/β-catenin pathway in functions of LRP6. The results of cell viability detection showed that XAV939 could significantly inhibit the positive effects of LRP6 overexpression on cell viability. Taken together, low-expressed LRP6 may be responsible of lower migration and invasion of EVTs and subsequent PE, and the mechanisms show a highly association with Wnt/β-catenin pathway.

Maternal high-fat diet associated with altered gene expression, DNA methylation, and obesity risk in mouse offspring

We investigated maternal obesity in inbred SM/J mice by assigning females to a high-fat diet or a low-fat diet at weaning, mating them to low-fat-fed males, cross-fostering the offspring to low-fat-fed SM/J nurses at birth, and weaning the offspring onto a high-fat or low-fat diet. A maternal high-fat diet exacerbated obesity in the high-fat-fed daughters, causing them to weigh more, have more fat, and have higher serum levels of leptin as adults, accompanied by dozens of gene expression changes and thousands of DNA methylation changes in their livers and hearts. Maternal diet particularly affected genes involved in RNA processing, immune response, and mitochondria. Between one-quarter and one-third of differentially expressed genes contained a differentially methylated region associated with maternal diet. An offspring high-fat diet reduced overall variation in DNA methylation, increased body weight and organ weights, increased long bone lengths and weights, decreased insulin sensitivity, and changed the expression of 3,908 genes in the liver. Although the offspring were more affected by their own diet, their maternal diet had epigenetic effects lasting through adulthood, and in the daughters these effects were accompanied by phenotypic changes relevant to obesity and diabetes.

Intrauterine growth restriction and placental gene expression in severe preeclampsia, comparing early-onset and late-onset forms

OBJECTIVE

To evaluate placental gene expression in severe early- or late-onset preeclampsia with intrauterine growth restriction compared to controls.

STUDY DESIGN

Chorionic villus sampling was conducted after cesarean section from the placentas of five women with early- or late-onset severe preeclampsia and five controls for each preeclampsia group. Microarray analysis was performed to identify gene expression differences between the groups.

RESULTS

Pathway analysis showed over-representation of gene ontology (GO) biological process terms related to inflammatory and immune response pathways, platelet development, vascular development, female pregnancy and reproduction in early-onset preeclampsia. Pathways related to immunity, complement and coagulation cascade were overrepresented in the hypergeometric test for the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. Ten genes (ABI3BP, C7, HLA-G, IL2RB, KRBOX1, LRRC15, METTL7B, MPP5, RFLNB and SLC20A) had a ≥±1 fold expression difference in severe early-onset preeclampsia group compared to early controls. There were 362 genes that had a ≥±1 fold expression difference in severe early-onset preeclampsia group compared to late-onset preeclampsia group including ABI3BP, C7, HLA-G and IL2RB.

CONCLUSION

There are significant differences in placental gene expression between severe early- and late-onset preeclampsia when both are associated with intrauterine growth restriction. ABI3BP, C7, HLA-G and IL2RB might contribute to the development of early form of severe preeclampsia.

LncRNAs expression in adjuvant-induced arthritis rats reveals the potential role of LncRNAs contributing to rheumatoid arthritis pathogenesis

BACKGROUND

Long non-coding RNAs (LncRNAs) are an important class of widespread molecules involved in diverse biological functions, which are exceptionally expressed in numerous types of diseases. Currently, limited study on LncRNA in rheumatoid arthritis (RA) is available. In this study, we aimed to identify the specifically expressed LncRNA that are relevant to adjuvant-induced arthritis (AA) in rats, and to explore the possible molecular mechanisms of RA pathogenesis.

METHODS

To identify LncRNAs specifically expressed in rheumatoid arthritis, the expression of LncRNAs in synoviums of rats from the model group (n=3) was compared with that in the control group (n=3) using Arraystar Rat LncRNA/mRNA microarray and real-time polymerase chain reaction (RT-PCR).

RESULTS

Up to 260 LncRNAs were found to be differentially expressed (≥1.5-fold-change) in the synoviums between AA model and the normal rats (170 up-regulated and 90 down-regulated LncRNAs in AA rats compared with normal rats). Coding-non-coding gene co-expression networks (CNC network) were drawn based on the correlation analysis between the differentially expressed LncRNAs and mRNAs. Six LncRNAs, XR_008357, U75927, MRAK046251, XR_006457, DQ266363 and MRAK003448, were selected to analyze the relationship between LncRNAs and RA via the CNC network and GO analysis. Real-time PCR result confirmed that the six LncRNAs were specifically expressed in the AA rats.

CONCLUSIONS

These results revealed that clusters of LncRNAs were uniquely expressed in AA rats compared with controls, which manifests that these differentially expressed LncRNAs in AA rats might play a vital role in RA development. Up-regulation or down-regulation of the six LncRNAs might contribute to the molecular mechanism underlying RA. To sum up, our study provides potential targets for treatment of RA and novel profound understanding of the pathogenesis of RA.