The Role of Long Non-Coding RNAs in Trophoblast Regulation in Preeclampsia and Intrauterine Growth Restriction

The placental blood perfusion and LINC00473-mediated promotion of trophoblast apoptosis in fetal growth restriction

This study aimed to investigate placental microblood flow perfusion in fetal growth restriction (FGR) both pre- and post-delivery, and explore the influence of LINC00473 and its downstream targets on FGR progression in trophoblast cells. Placental vascular distribution, placental vascular index (VIMV), CD34 expression, and histological changes were compared between control and FGR groups. FGR-related differentially expressed genes (DEGs) were analyzed and validated by quantitative real-time polymerase chain reaction (qPCR) and immunohistochemistry (IHC) in placentae. In vitro experiments examined the regulatory relationships among LINC00473, miR-5189-5p, and StAR, followed by investigations into their impacts on cell proliferation and apoptosis. FGR placentae exhibited irregular shapes, uneven parenchymal echo, stromal dysplasia, ischemic infarction, and variable degrees of thickening in some cases. FGR samples showed less prominent mother vessel lakes, significantly lower VIMV, and decreased CD34 expression. Hematoxylin & eosin (H&E) staining revealed placental fibrosis, fibrin adhesion, infarction, and interstitial dysplasia in FGR. LINC00473, miR-5189-5p, and StAR were identified as DEG, with qPCR demonstrating a significant increase in LINC00473 and a decrease in miR-5189-5p in FGR, while both qPCR and IHC indicated a significant increase in StAR expression. LINC00473 served as an endogenous sponge against miR-5189-5p in human HTR-8/SV neo cells, and StAR expression was regulated by both LINC00473 and miR-5189-5p. Dysregulation of these genes affected cell proliferation and apoptosis. Pathological changes in the placenta are significant contributors to FGR, with placental microblood flow potentially serving as an indicator for monitoring its progression. LINC00473 and its downstream targets may modulate trophoblasts proliferation and apoptosis, thus influencing the onset of FGR, suggesting novel avenues for diagnosis and treatment.

The Underlying Molecular Mechanisms of the Placenta Accreta Spectrum: A Narrative Review

Placenta accreta spectrum (PAS) disorders are characterized by abnormal trophoblastic invasion into the myometrium, leading to significant maternal health risks. PAS includes placenta accreta (invasion < 50% of the myometrium), increta (invasion > 50%), and percreta (invasion through the entire myometrium). The condition is most associated with previous cesarean deliveries and increases in chance with the number of prior cesarians. The increasing global cesarean rates heighten the importance of early PAS diagnosis and management. This review explores genetic expression and key regulatory processes, such as apoptosis, cell proliferation, invasion, and inflammation, focusing on signaling pathways, genetic expression, biomarkers, and non-coding RNAs involved in trophoblastic invasion. It compiles the recent scientific literature (2014-2024) from the Scopus, PubMed, Google Scholar, and Web of Science databases. Identifying new biomarkers like AFP, sFlt-1, β-hCG, PlGF, and PAPP-A aids in early detection and management. Understanding genetic expression and non-coding RNAs is crucial for unraveling PAS complexities. In addition, aberrant signaling pathways like Notch, PI3K/Akt, STAT3, and TGF-β offer potential therapeutic targets to modulate trophoblastic invasion. This review underscores the need for interdisciplinary care, early diagnosis, and ongoing research into PAS biomarkers and molecular mechanisms to improve prognosis and quality of life for affected women.

First Trimester Placental Biomarkers for Pregnancy Outcomes

The placenta plays a key role in several adverse obstetrical outcomes, such as preeclampsia, intrauterine growth restriction and gestational diabetes mellitus. The early identification of at-risk pregnancies could significantly improve the management, therapy and prognosis of these pregnancies, especially if these at-risk pregnancies are identified in the first trimester. The aim of this review was to summarize the possible biomarkers that can be used to diagnose early placental dysfunction and, consequently, at-risk pregnancies. We divided the biomarkers into proteins and non-proteins. Among the protein biomarkers, some are already used in clinical practice, such as the sFLT1/PLGF ratio or PAPP-A; others are not yet validated, such as HTRA1, Gal-3 and CD93. In the literature, many studies analyzed the role of several protein biomarkers, but their results are contrasting. On the other hand, some non-protein biomarkers, such as miR-125b, miR-518b and miR-628-3p, seem to be linked to an increased risk of complicated pregnancy. Thus, a first trimester heterogeneous biomarkers panel containing protein and non-protein biomarkers may be more appropriate to identify and discriminate several complications that can affect pregnancies.

Long non-coding RNAs: a summary of their roles in placenta development and pathology†

Long non-coding RNAs are cellular transcripts that have ˃200 nucleotides in length and do not code for proteins. Due to their low expression levels, long non-coding RNAs were previously considered as mere transcriptional noise. However, current evidence indicates that they regulate a myriad of biological processes such as cell proliferation, invasion, and apoptosis. Hence, their expression patterns are crucial indicators of the physiological or pathological states of cells, tissues, and organs. The utilization of long non-coding RNAs as biomarkers and therapeutic targets for the clinical management of several diseases have been suggested. Gradually, long non-coding RNAs are gaining a substantial attention in the field of feto-maternal medicine. After embryo implantation, the interactions between the trophoblast cells from the embryo and the uterus of the mother facilitate placenta development and pregnancy progression. These processes are tightly regulated, and their impairments result in pregnancy pathologies such as miscarriage and preeclampsia. Accumulating evidence implicates long non-coding RNAs in these processes. Herein, we have summarized the roles of several long non-coding RNAs in human placenta development, have proposed some mechanisms by which they participate in physiological and pathological placentation, have revealed some knowledge deficits, and have recommended ideal experimental approaches that will facilitate the clarification of the mechanistic actions of each long non-coding RNA at the feto-maternal interface during healthy and pathological pregnancies.

METTL3-mediated lncRNA HOXD-AS1 stability regulates inflammation, and the migration and invasion of trophoblast cells via the miR-135a/ β-TRCP axis

BACKGROUND

Preeclampsia (PE) is a serious pregnancy-specific syndrome associated with the inadequate invasion of trophoblast cells and inflammation of the uterus. A previous study found that lncRNA HOXD-AS1 promotes PE. However, its regulatory network requires additional exploration.

METHODS

HOXD-AS1-targeted miRNAs and genes were predicted by different databases in a bioinformatics analysis. The expression HOXD-AS1 and its potential m6A methylase (METTL3) were detected in placentas from healthy female patients with PE. The targeting relationship and role of the HOXD-AS1/miR-135a/β-TRCP axis in trophoblast cells were demonstrated by overexpression/knockdown assays. The levels of β-TRCP downstream pathway proteins IκBα, NF-κB, and p65 were measured. The levels of inflammatory factors in cell supernatants were detected by ELISA. To verify the molecular mechanism of β-TRCP in PE, IκBα was co-overexpressed in β-TRCP in trophoblast cells.

RESULTS

The levels of METTL3, HOXD-AS1, and β-TRCP were elevated in PE placental tissues, while miR-135a levels were reduced. MiR-135a was found to be targeted by HOXD-AS1, and HOXD-AS1 expression was maintained at a high level by METTL3-mediated m6A methylation. Overexpression of METTL3, HOXD-AS1, and β-TRCP, and knockdown of miR-135a in HTR-8/SVneo cells all inhibited cell invasion and migration, and promoted apoptosis and the secretion of inflammatory factors. Knockdown of METTL3, HOXD-AS1, and β-TRCP, and overexpression of miR-135a had the opposite effects. Furthermore, IκBα expression was negatively associated with β-TRCP expression, and the levels of NF-κB, p65, and NLRP3 were positively regulated by β-TRCP. A high level of β-TRCP expression attenuated the effect of HOXD-AS1 knockdown in trophoblast cells.

CONCLUSION

METTL3 functioned to maintain a high level of HOXD-AS1 expression in PE, which influenced inflammation and the migration and invasion of trophoblast cells via the miR-135a/β-TRCP axis and NF-κB pathway.

Functional Relevance of Extracellular Vesicle-Derived Long Non-Coding and Circular RNAs in Cancer Angiogenesis

Extracellular vesicles (EVs) are defined as subcellular structures limited by a bilayer lipid membrane that function as important intercellular communication by transporting active biomolecules, such as proteins, amino acids, metabolites, and nucleic acids, including long non-coding RNAs (lncRNAs). These cargos can effectively be delivered to target cells and induce a highly variable response. LncRNAs are functional RNAs composed of at least 200 nucleotides that do not code for proteins. Nowadays, lncRNAs and circRNAs are known to play crucial roles in many biological processes, including a plethora of diseases including cancer. Growing evidence shows an active presence of lnc- and circRNAs in EVs, generating downstream responses that ultimately affect cancer progression by many mechanisms, including angiogenesis. Moreover, many studies have revealed that some tumor cells promote angiogenesis by secreting EVs, which endothelial cells can take up to induce new vessel formation. In this review, we aim to summarize the bioactive roles of EVs with lnc- and circRNAs as cargo and their effect on cancer angiogenesis. Also, we discuss future clinical strategies for cancer treatment based on current knowledge of circ- and lncRNA-EVs.

New understandings of the genetic regulatory relationship between non-coding RNAs and m6A modification

One of the most frequent epigenetic modifications of RNA in eukaryotes is N6 methyladenosine (m6A), which is mostly present in messenger RNAs. Through the influence of several RNA processing stages, m6A modification is a crucial approach for controlling gene expression, especially in cancer progression. It is universally acknowledged that numerous non-coding RNAs (ncRNAs), such as microRNAs, circular RNAs, long non-coding RNAs, and piRNAs, are also significantly affected by m6A modification, and the complex genetic regulatory relationship between m6A and ncRNAs plays a pivotal role in the development of cancer. The connection between m6A modifications and ncRNAs offers an opportunity to explore the oncogene potential regulatory mechanisms and suggests that m6A modifications and ncRNAs could be vital biomarkers for multiple cancers. In this review, we discuss the mechanisms of interaction between m6A methylation and ncRNAs in cancer, and we also summarize diagnostic and prognostic biomarkers for clinical cancer detection. Furthermore, our article includes some methodologies for identifying m6A sites when assessing biomarker potential.

Exploring perinatal biopsychosocial factors and epigenetic age in 1-year-old offspring

Background: Little is known about the determinants of epigenetic aging in pediatric populations. Methods: Epigenetic age was estimated from 258 1-year-olds, using pediatric buccal epigenetic and Horvath clocks. We explored associations between epigenetic age and maternal indicators of mental and relational health, substance use and general physical health assessed during trimester three. Results: Higher anxiety and stress, BMI and higher parent-parent relationship quality were associated with pediatric buccal epigenetic clock differences. High blood pressure during pregnancy was associated with Horvath age acceleration. Third-trimester smoking and pre-pregnancy weight were associated with acceleration and deceleration respectively, and concordant across clocks. Conclusion: A broad range of maternal factors may shape epigenetic age in infancy; further research is needed to explore the possible effects on health and development.

Long non-coding RNA TLR8-AS1 induces preeclampsia through increasing TLR8/STAT1 axis

OBJECTIVE

Our current study tried to assay the role of long noncoding RNAs (lncRNAs) TLR8-AS1 in regulating preeclampsia.

METHODS

TLR8-AS1 expression was examined in the clinical placental tissues of preeclampsia patients and the trophoblast cells induced by lipopolysaccharide (LPS). Then, different lentivirus was infected into trophoblast cells to study the role of TLR8-AS1 in cell functions. Furthermore, interactions among TLR8-AS1, signal transducer and activator of transcription 1 (STAT1) and toll-like receptor 8 (TLR8) were determined. A rat model of preeclampsia induced by N(omega)-nitro-L-arginine methyl ester was developed to validate the in-vitro findings.

RESULTS

High expression of TLR8-AS1 was detected in placental tissues of preeclampsia patients and LPS-induced trophoblast cells. In addition, overexpression of TLR8-AS1 arrested the proliferation, migration and invasion of trophoblast cells, which was related to the upregulation of TLR8 expression. Mechanistically, TLR8-AS1 recruited STAT1 to bind to the TLR8 promoter region, and thus promoted the transcription of TLR8. Meanwhile, overexpression of TLR8-AS1 was shown to aggravate preeclampsia by elevating TLR8 in vivo .

CONCLUSION

Our study confirmed that TLR8-AS1 aggravated the progression of preeclampsia through increasing the expression of STAT1 and TLR8.

YTHDC1 maintains trophoblasts function by promoting degradation of m6A-modified circMPP1

N6-methyladenosine (m6A) is the most abundant mRNA internal modification in eukaryotic mRNAs. This study focuses on the effect of circMPP1 on placental villi function and the molecular mechanism. First, differentially expressed circular RNAs (circRNAs) in placenta tissues of large-for-gestational-age(LGA) neonates were screened by m6A-circRNA Epitranscriptomic Microarray and bioinformatics analyses. The abnormal expression of circMPP1 in placental tissues and cell lines was validated by RT-qPCR. In-vitro and in-vivo functional experiments were performed to evaluate the role of circMPP1 in placental impairment and fetal dysplasia. The interacting proteins of circMPP1 were identified and validated using RNA pull-down, RNA immunoprecipitation, fluorescence in situ hybridization, and immunofluorescence experiments. Protein interactions and expression levels were detected by Co-immunoprecipitation and western blot analysis. The m6A modification in circMPP1 was verified by methylated RNA immunoprecipitation assay. Bioinformatics analyses showed that circMPP1 was highly expressed in tissues with disordered placental function. In-vitro and in-vivo functional experiments showed that circMPP1 inhibited the function of placental villi. Further mechanism analyses showed that circMPP1 activated the NF-kappa B and MAPK3 signaling pathways. In addition, the m6A "reader" protein YTHDC1 was found to reduce circMPP1 expression via m6A modification. In conclusion, this study demonstrates that YTHDC1 maintains trophoblasts function by promoting degradation of m6A-mediated circMPP1.

Placental circadian lincRNAs and spontaneous preterm birth

Long non-coding RNAs (lncRNAs) have a much higher cell- and/or tissue-specificity compared to mRNAs in most cases, making them excellent candidates for therapeutic applications to reduce off-target effects. Placental long non-coding RNAs have been investigated in the pathogenesis of preeclampsia (often causing preterm birth (PTB)), but less is known about their role in preterm birth. Preterm birth occurs in 11% of pregnancies and is the most common cause of death among infants in the world. We recently identified that genes that drive circadian rhythms in cells, termed molecular clock genes, are deregulated in maternal blood of women with spontaneous PTB (sPTB) and in the placenta of women with preeclampsia. Next, we focused on circadian genes-correlated long intergenic non-coding RNAs (lincRNAs, making up most of the long non-coding RNAs), designated as circadian lincRNAs, associated with sPTB. We compared the co-altered circadian transcripts-correlated lincRNAs expressed in placentas of sPTB and term births using two published independent RNAseq datasets (GSE73712 and GSE174415). Nine core clock genes were up- or downregulated in sPTB versus term birth, where the RORA transcript was the only gene downregulated in sPTB across both independent datasets. We found that five circadian lincRNAs (LINC00893, LINC00265, LINC01089, LINC00482, and LINC00649) were decreased in sPTB vs term births across both datasets (p ≤ .0222, FDR≤.1973) and were negatively correlated with the dataset-specific clock genes-based risk scores (correlation coefficient r = -.65 ∼ -.43, p ≤ .0365, FDR≤.0601). Gene set variation analysis revealed that 65 pathways were significantly enriched by these same five differentially expressed lincRNAs, of which over 85% of the pathways could be linked to immune/inflammation/oxidative stress and cell cycle/apoptosis/autophagy/cellular senescence. These findings may improve our understanding of the pathogenesis of spontaneous preterm birth and provide novel insights into the development of potentially more effective and specific therapeutic targets against sPTB.

PVT1/miR-145-5p/HK2 modulates vascular smooth muscle cells phenotype switch via glycolysis: The new perspective on the spiral artery remodeling

INTRODUCTION

Vascular smooth muscle cells (VSMC) switched from a contractile phenotype to a synthetic phenotype during the decidual spiral artery (SPAs) remodeling process. The lncRNA plasmacytoma variant translocation 1 (PVT1) and glucose metabolism have been found to regulate the VSMC phenotype switch. This study aimed to analyze the dynamic expression of PVT1 and glycolytic key enzymes hexokinase2 (HK2) at different remodeling stages in early human pregnancy and elucidate the underlying mechanism of the PVT1/miR-145-5p/HK2 axis involved in the spiral artery remodeling.

METHODS

qRT-PCR, Western blot (WB) analysis, Immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) were used to detect the expression and localization of PVT1 and HK2 in decidual tissue. HA-VSMCs were transfected with specific siRNA, shRNA and plasmids to regulate corresponding genes. Extracellular lactate, cellular ATP, ROS, and intracellular NADPH levels were measured using the corresponding assay kits. Migration was measured by wound-healing and Transwell assays. Contractile phenotypic markers α-SMA, MYH11 with calponin and synthetic phenotypic markers OPN and vimentin were detected by WB. The PDC model was used to detect the degree of spiral arterial remodeling.

RESULTS

PVT1 and HK2 were upregulated with gestational age (GA) increasing in decidual tissue during the early pregnancy. HK2 regulated the glycolytic activity and VSMC phenotype switch in vitro. PVT1 regulated the glycolytic activity and VSMC phenotype switch through HK2. PVT1 played a ceRNA role in regulating HK2 expression by sponging miR-145-5p. PVT1 and HK2 influenced spiral artery remodeling in the PDC model.

DISCUSSION

PVT1 and HK2 were upregulated, and miR-145-5p was downregulated in decidua with the GA increasing. Meanwhile, the PVT1/miR-145-5p/HK2 axis may be involved in regulating the phenotypic switch and migratory capacity of VSMCs by affecting glycolysis in decidual SPAs remodeling.

Epigenetics Beyond Fetal Growth Restriction: A Comprehensive Overview

Fetal growth restriction is a pathological condition occurring when the fetus does not reach the genetically determined growth potential. The etiology of fetal growth restriction is expected to be multifactorial and include fetal, maternal, and placental factors, the latter being the most frequent cause of isolated fetal growth restriction. Severe fetal growth restriction has been related to both an increased risk of perinatal morbidity and mortality, and also a greater susceptibility to developing diseases (especially cardio-metabolic and neurological disorders) later in life. In the last decade, emerging evidence has supported the hypothesis of the Developmental Origin of Health and Disease, which states that individual developmental 'programming' takes place via a delicate fine tuning of fetal genetic and epigenetic marks in response to a large variety of 'stressor' exposures during pregnancy. As the placenta is the maternal-fetal interface, it has a crucial role in fetal programming, such that any perturbation altering placental function interferes with both in-utero fetal growth and also with the adult life phenotype. Several epigenetic mechanisms have been highlighted in modulating the dynamic placental epigenome, including alterations in DNA methylation status, post-translational modification of histones, and non-coding RNAs. This review aims to provide a comprehensive and critical overview of the available literature on the epigenetic background of fetal growth restriction. A targeted research strategy was performed using PubMed, MEDLINE, Embase, and The Cochrane Library up to January 2022. A detailed and fully referenced synthesis of available literature following the Scale for the Assessment of Narrative Review Articles guidelines is provided. A variety of epigenetic marks predominantly interfering with placental development, function, and metabolism were found to be potentially associated with fetal growth restriction. Available evidence on the role of environmental exposures in shaping the placental epigenome and the fetal phenotype were also critically discussed. Because of the highly dynamic crosstalk between epigenetic mechanisms and the extra level of complexity in interpreting the final placental transcriptome, a full comprehension of these phenomenon is still lacking and advances in multi-omics approaches are urgently needed. Elucidating the role of epigenetics in the developmental origins of health and disease represents a new challenge for the coming years, with the goal of providing early interventions and prevention strategies and, hopefully, new treatment opportunities.

Identification of LOC101927355 as a Novel Biomarker for Preeclampsia

Preeclampsia, a disorder with a heterogeneous physiopathology, can be attributed to maternal, fetal, and/or placental factors. Long non-coding RNAs (lncRNAs) refer to a class of non-coding RNAs, the essential regulators of biological processes; their differential expression has been associated with the pathogenesis of multiple diseases. The study aimed to identify lncRNAs, expressed in the placentas and plasma of patients who presented with preeclampsia, as potential putative biomarkers of the disease. In silico analysis was performed to determine lncRNAs differentially expressed in the placentas of patients with preeclampsia, using a previously published RNA-Seq dataset. Seven placentas and maternal plasma samples collected at delivery from preterm preeclamptic patients (≤37 gestational weeks of gestation), and controls were used to validate the expression of lncRNAs by qRT-PCR. Six lncRNAs were validated and differentially expressed (p < 0.05) in the preeclampsia and control placentas: UCA1 and HCG4 were found upregulated, and LOC101927355, LINC00551, PART1, and NRAD1 downregulated. Two of these lncRNAs, HCG4 and LOC101927355, were also detected in maternal plasma, the latter showing a significant decrease (p = 0.03) in preeclamptic patients compared to the control group. In silico analyses showed the cytoplasmic location of LOC101927355, which suggests a role in post-transcriptional gene regulation. The detection of LOC101927355 in the placenta and plasma opens new possibilities for understanding the pathogenesis of preeclampsia and for its potential use as a biomarker.

(Dis)similarities between the Decidual and Tumor Microenvironment

Placenta-specific trophoblast and tumor cells exhibit many common characteristics. Trophoblast cells invade maternal tissues while being tolerated by the maternal immune system. Similarly, tumor cells can invade surrounding tissues and escape the immune system. Importantly, both trophoblast and tumor cells are supported by an abetting microenvironment, which influences invasion, angiogenesis, and immune tolerance/evasion, among others. However, in contrast to tumor cells, the metabolic, proliferative, migrative, and invasive states of trophoblast cells are under tight regulatory control. In this review, we provide an overview of similarities and dissimilarities in regulatory processes that drive trophoblast and tumor cell fate, particularly focusing on the role of the abetting microenvironments.

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

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