Cell-Free mRNA Concentrations of Plasminogen Activator Inhibitor-1 and Tissue-Type Plasminogen Activator Are Increased in the Plasma of Pregnant Women with Preeclampsia

Heterologous expression, purification and single step efficient refolding of recombinant tissue plasminogen activator (Reteplase) from E. coli

Reteplase (recombinant plasminogen activator, rPA) is a mutant non-glycosylated tissue-type plasminogen activator (tPA) containing 355 amino acids with longer half-life and promising thrombolytic activity than its original counterpart, full length tPA. In this study, we aimed to produce and optimize the purification process of recombinant tissue-type plasminogen activator (tPA) known as Reteplase (rPA). Reteplase cDNA synthesized from total mRNA isolated from human placenta was PCR amplified, cloned into a pET-28a(+) E. coli expression vector and expressed in Rosetta-gami 2 E. coli (NovagenⓇ) host. rPA was expressed as an inclusion body in E. coli and its biological activity was achieved after single step solubilization, purification and refolding. We exploited the strategy of Slow Refolding using Gradual Dialysis (SRGD) in which a refolding buffer containing glutathione oxidized (1 mM GSSG) and glutathione reduced (3 mM GSH) and pH 9.0 was used. Using the SRGD method, we were able to successfully obtain the protein in its active form. We obtained 4.26 mg of active refolded protein from a 50 mL culture that was scaled up in a bioreactor. The purity and homogeneity of rPA was evaluated by SDS-PAGE, Western blotting and mass spectrometry. Circular dichroism spectroscopy was conducted to evaluate the refolding and stability of the refolded rPA in comparison to reference standard rPA. The thrombolytic potential of rPA was assessed by fibrin plate assay and In Vitro clot lysis assay. The presented protocol offers a viable approach for enhancing both the yield and refolding efficiency of reteplase, potentially resulting in an increase in yield.

Prediction of preeclampsia using maternal circulating mRNAs in early pregnancy

PURPOSE

Preeclampsia (PE) is one of the most common and serious complications of pregnancy, and novel methods for the early prediction of PE are needed for clinical application.

METHODS

In this study, a circulating cell-free RNA (cfRNA) panel of target genes for PE prediction was designed and validated in a case-control cohort and a nested case-control cohort. The QPCR was applied to quantify the copy number of cfRNA, and the data were normalized as multiples of the median. Ratios of serum placental growth factor (PIGF) and soluble fms-like tyrosine kinase 1 (sFLT-1) were also measured, and transabdominal ultrasonography was conducted for subjects in the prospective cohort. Binary logistic regression models for PE prediction were constructed and tested.

RESULTS

Our results revealed that the women with PE showed significant alterations in serum cfRNA profiles from early pregnancy onward and before the onset of PE symptoms. Compared with PIGF/sFLT-1 measurement and ultrasonographic imaging, cfRNA test can detect PE at a very early stage of pregnancy. The predictive model exhibited the best performance at gestation week 32, with a detection rate of 100%. At 12 weeks of gestation, the model still manifested an area under curve (AUC) of 0.9144, and sensitivity of 1.0000. If combined with clinical parameters and ultrasonographic indicators, the model can achieve the highest AUC for PE prediction at early gestation.

CONCLUSION

Measurement of cfRNA can be used to effectively predict PE with high performance, providing an additional method for monitoring PE throughout the course of pregnancy.

Noninvasive preeclampsia prediction using plasma cell-free RNA signatures

BACKGROUND

Preeclampsia, especially preterm preeclampsia and early-onset preeclampsia, is a life-threating pregnancy disorder, and the heterogeneity and complexity of preeclampsia make it difficult to predict risk and to develop treatments. Plasma cell-free RNA carries unique information from human tissue and may be useful for noninvasive monitoring of maternal, placental, and fetal dynamics during pregnancy.

OBJECTIVE

This study aimed to investigate various RNA biotypes associated with preeclampsia in plasma and to develop classifiers to predict preterm preeclampsia and early-onset preeclampsia before diagnosis.

STUDY DESIGN

We performed a novel, cell-free RNA sequencing method termed polyadenylation ligation-mediated sequencing to investigate the cell-free RNA characteristics of 715 healthy pregnancies and 202 pregnancies affected by preeclampsia before symptom onset. We explored differences in the abundance of different RNA biotypes in plasma between healthy and preeclampsia samples and built preterm preeclampsia and early-onset preeclampsia prediction classifiers using machine learning methods. Furthermore, we validated the performance of the classifiers using the external and internal validation cohorts and assessed the area under the curve and positive predictive value.

RESULTS

We detected 77 genes, including messenger RNA (44%) and microRNA (26%), that were differentially expressed in healthy mothers and mothers with preterm preeclampsia before symptom onset, which could separate participants with preterm preeclampsia from healthy samples and that played critical functional roles in preeclampsia physiology. We developed 2 classifiers for predicting preterm preeclampsia and early-onset preeclampsia before diagnosis based on 13 cell-free RNA signatures and 2 clinical features (in vitro fertilization and mean arterial pressure), respectively. Notably, both classifiers showed enhanced performance when compared with the existing methods. The preterm preeclampsia prediction model achieved 81% area under the curve and 68% positive predictive value in an independent validation cohort (preterm, n=46; control, n=151); the early-onset preeclampsia prediction model had an area under the curve of 88% and a positive predictive value of 73% in an external validation cohort (early-onset preeclampsia, n=28; control, n=234). Furthermore, we demonstrated that downregulation of microRNAs may play vital roles in preeclampsia through the upregulation of preeclampsia-relevant target genes.

CONCLUSION

In this cohort study, a comprehensive transcriptomic landscape of different RNA biotypes in preeclampsia was presented and 2 advanced classifiers with substantial clinical importance for preterm preeclampsia and early-onset preeclampsia prediction before symptom onset were developed. We demonstrated that messenger RNA, microRNA, and long noncoding RNA can simultaneously serve as potential biomarkers of preeclampsia, holding the promise of prevention of preeclampsia in the future. Abnormal cell-free messenger RNA, microRNA, and long noncoding RNA molecular changes may help to elucidate the pathogenic determinants of preeclampsia and open new therapeutic windows to effectively reduce pregnancy complications and fetal morbidity.

Preeclampsia and the Kidney: Pathophysiology and Clinical Implications

Preeclampsia and other hypertensive disorders of pregnancy are major contributors to maternal morbidity and mortality worldwide. This group of disorders includes chronic hypertension, gestational hypertension, preeclampsia, preeclampsia superimposed on chronic hypertension, and eclampsia. The body undergoes important physiological changes during pregnancy to allow for normal placental and fetal development. Several mechanisms have been proposed that may lead to preeclampsia, including abnormal placentation and placental hypoxia, impaired angiogenesis, excessive pro-inflammatory response, immune system imbalance, abnormalities of cellular senescence, alterations in regulation and activity of angiotensin II, and oxidative stress, ultimately resulting in upregulation of multiple mediators of endothelial cell dysfunction leading to maternal disease. The clinical implications of preeclampsia are significant as there are important short-term and long-term health consequences for those affected. Preeclampsia leads to increased risk of preterm delivery and increased morbidity and mortality of both the developing fetus and mother. Preeclampsia also commonly leads to acute kidney injury, and women who experience preeclampsia or another hypertensive disorder of pregnancy are at increased lifetime risk of chronic kidney disease and cardiovascular disease. An understanding of normal pregnancy physiology and the pathophysiology of preeclampsia is essential to develop novel treatment approaches and manage patients with preeclampsia and hypertensive disorders of pregnancy. © 2023 American Physiological Society. Compr Physiol 13:4231-4267, 2023.

Fibrinolytic Changes in Women with Preeclampsia

Objectives

Preeclampsia (PE) is a serious complication of pregnancy. The fibrinolytic system play crucial roles regarding placentation and evolution of PE.

Aim

To study comprehensively components of the fibrinolytic system and fibrin lysability in women with PE.

Design and Methods

117 women with PE and matched controls were included. Tissue type plasminogen activator (t-PA), plasminogen, PAI-1, plasmin inhibitor (PI), D-dimer, the fibrinolytic potential of dextran sulphate euglobulin fraction (DEF), PAI-2, polymere PAI-2, fibrin clot lysability, thrombin activatable fibrinolysis inhibitor (TAFI) and fibrinogen were assessed.

Results

Women with PE had significantly increased concentrations of t-PA and PAI-1, whereas the plasma concentration of PAI-2 was significantly lower compared to controls, p < 0.0001. Polymere PAI-2 was detected in both groups. DEF, TAFI and fibrinogen were not different between the groups. D-dimer was significantly increased and plasminogen/PI together with fibrin clot lysability time decreased in the PE-group, p  =  0.0004 p  =  0.04, p  =  0.03, p < 0.0001 respectively.

Conclusion

This study demonstrates that PE is associated with an affected t-PA/PAI-1 system, decreased PAI-2 and increased fibrin lysability. Furthermore, PAI-2 has the potential to polymerize during pregnancy.

Circulating adipokine levels and preeclampsia: A bidirectional Mendelian randomization study

Background: Several observational studies have demonstrated that significantly rising circulating adipokine levels are pervasive in preeclampsia or eclampsia disorder (or preeclampsia toxemia (PET)). However, it remains unclear whether this relationship is causal. In this study, we sought to elucidate the causal effects of circulating adipokine levels on PET.

Methods: Summary-level data and independent genetic variants strongly associated with common adipokine molecule (adiponectin, leptin, resistin, sOB-R, and PAI-1) levels were drawn from public genome-wide association study (GWASs). Additionally, the corresponding effects between instrumental variables and PET outcomes were acquired from the FinnGen consortium, including 4,743 cases and 136,325 controls of European ancestry. Subsequently, an inverse-variance weighted (IVW) approach was applied for the principal two-sample Mendelian randomization (MR) and multivariable MR (MVMR) analyses. Various complementary sensitivity analyses were then carried out to determine the robustness of our models.

Results: The results of the IVW method did not reveal any causal relationship shared across genetically predisposed adipokine levels and PET risk (for adiponectin, OR = 0.86, 95% CI: 0.65–1.13, p = 0.274). Additionally, no significant associations were identified after taking into account five circulating adipokines in MVMR research. Complementary sensitivity analysis also supported no significant associations between them. In the reverse MR analysis, genetically predicted PET risk showed a suggestive association with elevating PAI-1 levels by the IVW method (Beta = 0.120, 95% CI: 0.014, 0.227, p = 0.026). Furthermore, there were no strong correlations between genetic liability to PET and other adipokine levels (p > 0.05).

Conclusion: Our MR study did not provide robust evidence supporting the causal role of common circulating adipokine levels in PET, whereas genetically predicted PET may instrumentally affect PAI-1 levels. These findings suggest that PAI-1 may be a useful biomarker for monitoring the diagnosis or therapy of PET rather than a therapeutic target for PET.

The natural compound puerarin alleviates inflammation and apoptosis in experimental cell and rat preeclampsia models

Puerarin (Pue), an isoflavone derived from Radix puerariae, exerts anti-apoptosis and anti-inflammatory effects. However, the protective effect of Pue on PE is still unknown. The present study aimed to investigate whether Pue alleviates symptoms of PE and suppresses inflammation and apoptosis in vitro and in vivo. A cell model of PE was established by exposing HTR8/SVneo cells to LPS and an RNA-SEQ study was performed in LPS-stimulated HTR8/SVneo cells. We also established a rat model of PE by injecting pregnant rats with LPS and the basic preeclamptic symptoms were evaluated. Additionally, the placental histology, placental inflammation cytokines, and apoptosis markers were also measured. Pue protected HTR8/SVneo cells from LPS-evoked cytotoxicity, decreased the levels of sFlt-1, ET-1, and tPA in HTR8/SVneo cells. RNA-SEQ results revealed the significant changes in the expression levels of hub genes (TNF, IL-6, Jun, and NFKBIA) related to multiple inflammatory pathways, including the TNF signaling pathway, IL-17 signaling pathway, inflammatory disease, and NF-κB signaling pathway. After administration of Pue, we observed that LPS-evoked PE symptoms (hypertension, proteinuria, and fetal growth restriction), were reversed. Besides, Pue improved placental pathology change and reducing placental sFlt-1, ET-1, and tPA mRNA expression. Abnormal placental inflammatory cytokines (TNF, IL-6, IFN-γ, and IL-4) and apoptosis markers (Bcl-2, Bax, caspase-3, caspase-8, and caspase-9) expressions in the LPS-treated group were reversed after Pue treatment. Our findings revealed that Pue plays beneficial roles in PE models, and therefore possesses the therapeutic potential for prevention and treatment of PE.

Palmitic acid induces inflammation in placental trophoblasts and impairs their migration toward smooth muscle cells through plasminogen activator inhibitor-1

A critical component of early human placental development includes migration of extravillous trophoblasts (EVTs) into the decidua. EVTs migrate toward and displace vascular smooth muscle cells (SMCs) surrounding several uterine structures, including spiral arteries. Shallow trophoblast invasion features in several pregnancy complications including preeclampsia. Maternal obesity is a risk factor for placental dysfunction, suggesting that factors within an obese environment may impair early placental development. Herein, we tested the hypothesis that palmitic acid, a saturated fatty acid circulating at high levels in obese women, induces an inflammatory response in EVTs that hinders their capacity to migrate toward SMCs. We found that SMCs and SMC-conditioned media stimulated migration and invasion of an EVT-like cell line, HTR8/SVneo. Palmitic acid impaired EVT migration and invasion toward SMCs, and induced expression of several vasoactive and inflammatory mediators in EVTs, including endothelin, interleukin (IL)-6, IL-8 and PAI1. PAI1 was increased in plasma of women with early-onset preeclampsia, and PAI1-deficient EVTs were protected from the anti-migratory effects of palmitic acid. Using first trimester placental explants, palmitic acid exposure decreased EVT invasion through Matrigel. Our findings reveal that palmitic acid induces an inflammatory response in EVTs and attenuates their migration through a mechanism involving PAI1. High levels of palmitic acid in pathophysiological situations like obesity may impair early placental development and predispose to placental dysfunction.

Galectin-1-Related Modulation of Trophoblast Endothelial Interactions by Integrins α1 and β1

During normal trophoblast invasion, integrins α6β4 are downregulated, and α1β1 are upregulated in invasive cytotrophoblast cells. In preeclampsia both interstitial and endovascular invasion are shallow and cytotrophoblasts fail to upregulate α1β1 and downregulate α6β4. This study aims to investigate the role of integrins α1β1 and α6β4 on cellular pathways influencing trophoblast integration into endothelial cellular networks in vitro. Red fluorescent-labeled human uterine myometrial microvascular endothelial cells (UtMVECs) were seeded on Matrigel to form endothelial networks. Green fluorescent-labeled trophoblastic HTR-8/SVneo cells pre-incubated with 20 μg/ml of neutralizing antibodies (anti-α1, β1, α6, β4, α1 + β1, or α6 + β4) for 1 h were then co-cultured with endothelial networks with the neutralizing antibodies for 24 h. Fluorescent images were captured, and quantified utilizing Image J. Cells were retrieved to analyze mRNA expression of galectin-1, TIMP-1, and PAI-1 by quantitative PCR. MMP-2, MMP-9, free sFlt-1, and PlGF from conditioned media were measured by ELISA. The integration of trophoblast cells into endothelial cellular networks was inhibited by anti-β1(- 28 ± 3%, p < 0.0001), and increased by anti-α6(+ 19 ± 5%, p < 0.01). Galectin-1 mRNA expression was decreased by anti-α1(- 35 ± 7%, p < 0.001), anti-β1(- 23 ± 5%, p < 0.05), and anti-α1+β1(- 35 ± 5%, p < 0.001). The mRNA expression of TIMP-1 was inhibited by anti-α1(- 59 ± 9%, p < 0.01) and anti-β1(- 63 ± 7%, p < 0.001) while PAI-1 mRNA expression was increased by anti-α1 + β1(+ 285 ± 70%, p < 0.0001). In the conditioned medium, anti-α1 reduced MMP-2(-28 ± 1%, p < 0.001), MMP-9(-27 ± 8%, p < 0.01), and sFlt-1(-27 ± 5%, p < 0.001) production. Anti-β1 reduced MMP-2(- 15 ± 2%, p < 0.05) production. There were no changes in PlGF. Appropriate integrins α1β1 modulate trophoblast cell integration into endothelial cellular networks in vitro through invasive pathways including galectin-1, TIMP-1, PAI-1, MMP-2, and MMP-9 production.

Human placental lactogen mRNA in maternal plasma play a role in prenatal diagnosis of abnormally invasive placenta: yes or no?

Objective: To determine whether maternal plasma human placental lactogen (hPL) mRNA levels can predict abnormally invasive placenta. Study design: Sixty-eight singleton pregnant women with prior Cesarean deliveries were classified into three groups: 35 with normal placentation (control group); 21 with placenta previa alone (placenta previa group); 12 with placenta previa and placenta accreta (placenta accreta group). Maternal plasma hPL mRNA concentrations were measured by real-time reverse-transcription polymerase chain reaction Result: The multiple of the median (median, range) for hPL mRNA was significantly higher for the placenta accreta group (2.78, 1.09-4.56) than the control (1.00, 0.29-2.98) or placenta previa (1.12, 0.33-3.25) groups (Steel-Dwass test, p < .001 and p = .005, respectively), was not significantly different between the women with placenta accreta who underwent hysterectomies (2.96, 1.38-4.56) and the women whose deliveries did not result in hysterectomy (2.36, 1.09-3.25) in the placenta accreta group (Mann-Whitney U test, p = .372). Conclusion: hPL mRNA in maternal plasma may indicate abnormally invasive placenta but cannot predict whether abnormally invasive placenta will result in hysterectomy.

Gene expression analysis of MMPs in women with preeclampsia using cell-free fetal RNA in maternal plasma

OBJECTIVE

Nucleic acids released from the placenta into the mother's blood circulation system provide a valuable source of potential biomarkers for early detection of pregnancy complications such as preeclampsia (PE). PE affects nearly 5-10% of pregnancies worldwide and is a major contributor to the maternal and neonatal mortality and morbidity. It is known that altered placental expression of matrix metalloproteinases (MMPs) may cause shallow cytotrophoblastic invasion and ultimately lead to preeclampsia. The present study aimed to evaluate pattern of placental/fetal expression of the MMP family (MMP-2, MMP-9, MMP-14, MMP-15 and MMP-26) in preeclamptic women and compare it to normal pregnancies, using cell free fetal RNA (cff-RNA).

METHODS

Blood samples were obtained from 20 pregnant women diagnosed with severe PE (28-32 weeks) and 40 control healthy pregnant women in two groups of either matched gestational age (N = 20) or 14 and 28 weeks pregnancies (each 10). cff-RNA was extracted from plasma, followed by reverse transcription of cff-RNA. Expression of MMP genes was measured using quantitative reverse transcription PCR (qRT-PCR).

RESULTS

The expression levels of MMP-2, MMP-9 and MMP-15 were significantly increased, while MMP-14 expression level was significantly reduced and the expression of MMP-26 showed a relative increase in PE pregnancies compared to the control group. Additionally, increased level of MMPs expression was observed by comparing 14 and 28 weeks gestation age in normal pregnancy.

CONCLUSION

Using cff-RNA, circulatory expression level of MMP-2, MMP-9, MMP-14 and MMP-15 were significantly altered in preeclampsia compared to normal pregnancies.

Fibrinolytic proteins of normal pregnancy and pre-eclamptic patients in North West Nigeria

BACKGROUND

The hypercoagulability of pregnancy is exaggerated in pre-eclamptic state because of endothelial activation with resultant production of some endothelial derived proteins that are said to be inhibitors of fibrinolysis. This study compares these proteins like tPA, PAI-1 and D-dimers in normal pregnant women and the pre-eclamptic women.

METHODOLOGY

This was a comparative cross-sectional study. Eighty-five pre-eclamptic women were recruited as subjects and eighty five age, trimester and parity matched normotensive pregnant women as controls. Levels of PT, aPTT, tPA, PAI-1, D-dimer protein were determined in blood samples of subjects and controls. Urinalysis was performed with dipstick method on their urine samples. Data generated was analysed using the IBM®SPSS 20.0 (2011) soft ware packages and the level of significance was a p-value <0.05.

RESULTS

The mean age of the respondents was 29.9±5.2 years. The median(25th-75th percentile) values of D-dimer, tPA, and PAI-1 of subjects were 730 (305.000-1560.000ng/ml), 0.11 (0.065-0,300ng/ml) and 3.65 (2.970-4,400ng/ml) respectively which were significantly higher than the corresponding values in the controls of 520 (24.000-1030.000ng/ml), 0.05 (0.040-0.090ng/ml and 2.650 (2.125-3.400ng/ml) respectively, p<0.05 each.

CONCLUSION

The abnormal levels of PAI-1, D-dimer and tPA imply that they contribute to the exaggerated hypercoagulabilty state in pre-eclampsia thus, measuring their levels can help in the management of the condition.

Effects of gestational hypertension and pre-eclampsia in mRNA expression of fibrinolysis genes in primary cultured human umbilical vein endothelial cells

Hypertension disorders (HD) and pre-eclampsia (PRE) are leading causes of maternal deaths worldwide. PRE is associated with vascular endothelial dysfunction and with deregulation of the fibrinolysis pathway genes. Fibrinolysis is the fibrin clot hydrolysis process catalyzed by plasmin, a proteolytic enzyme formed from plasminogen. Plasminogen is cleaved by tissue-type (tPA) and urokinase-type (uPA) activators and inhibited by the plasminogen activator inhibitors type-1 (PAI-1) and type-2 (PAI-2). The whole process maintains blood hemostasis. This study aims to assess PAI-1, PAI-2, tPA and uPA mRNA expression in primary cultured human umbilical vein endothelial cells (HUVEC) isolated and cultured from healthy, HD and PRE women. Results show that PAI-1 and PAI-2 mRNA decreased in HD-HUVEC, whereas PAI-1 and uPA decreased in PRE-HUVEC cultures compared to control ones. Notably, the expression ratio between pro- and anti-fibrinolytic actors remained unchanged among the studied groups. It seems that newborn's hemostasis is maintained balanced probably by a compensatory mechanism that involves changes in the fibrinolysis gene expression profile. The real impact of these changes in mRNA expression is unknown, however, it is suggested that these changes could be associated with an increased predisposition to vascular disease development in the progeny.

Role of Plasminogen Activator Inhibitor Type 1 in Pathologies of Female Reproductive Diseases

Normal pregnancy is a state of hypercoagulability with diminishing fibrinolytic activity, which is mainly caused by an increase of plasminogen activator inhibitor type 1 (PAI-1). PAI-1 is the main inhibitor of plasminogen activators, including tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA). In human placentas, PAI-1 is expressed in extravillous interstitial trophoblasts and vascular trophoblasts. During implantation and placentation, PAI-1 is responsible for inhibiting extra cellular matrix (ECM) degradation, thereby causing an inhibition of trophoblasts invasion. In the present study, we have reviewed the literature of various reproductive diseases where PAI-1 plays a role. PAI-1 levels are increased in patients with recurrent pregnancy losses (RPL), preeclampsia, intrauterine growth restriction (IUGR), gestational diabetes mellitus (GDM) in the previous pregnancy, endometriosis and polycystic ovary syndrome (PCOS). In general, an increased expression of PAI-1 in the blood is associated with an increased risk for infertility and a worse pregnancy outcome. GDM and PCOS are related to the genetic role of the 4G/5G polymorphism of PAI-1. This review provides an overview of the current knowledge of the role of PAI-1 in reproductive diseases. PAI-1 represents a promising monitoring biomarker for reproductive diseases and may be a treatment target in the near future.

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

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

Maternal plasma levels of cell-free β-HCG mRNA as a prenatal diagnostic indicator of placenta accrete

OBJECTIVE

Several biomarkers, including maternal serum creatinine kinase and α-fetoprotein, have been described as potential tools for the diagnosis of placental abnormalities. This study aimed to determine whether maternal plasma mRNA levels of the β subunit of human chorionic gonadotropin (β-HCG) could predict placenta accreta prenatally.

METHODS

Sixty-eight singleton pregnant women with prior cesarean deliveries (CDs) were classified into three groups: normal placentation (35 women, control group); placenta previa alone (21 women, placenta previa group); and both placenta previa and placenta accreta (12 women, placenta previa/accreta group). Maternal plasma concentrations of cell-free β-HCG mRNA were measured by real-time reverse-transcription polymerase chain reaction and were expressed as multiples of the median (MoM).

RESULTS

Cell-free β-HCG mRNA concentrations (MoM, range) were significantly higher in women with placenta accreta (3.65, 2.78-7.19) than in women with placenta previa (0.94, 0.00-2.97) or normal placentation (1.00, 0.00-2.69) (Steel-Dwass test, P < 0.01 and P < 0.01, respectively). In the placenta previa/accreta group, the concentration of cell-free β-HCG mRNA was significantly higher among women who underwent CDs with hysterectomy (4.41, 3.49-7.19) than among women whose CDs did not result in hysterectomy (3.20, 2.78-3.70) (Mann-Whitney U test, P = 0.012).

DISCUSSION

An increased level of cell-free β-HCG mRNA in the maternal plasma of women with placenta accreta may arise from direct uteroplacental transfer of cell-free placental mRNA molecules.

CONCLUSIONS

The concentration of cell-free β-HCG mRNA in maternal plasma may be applicable to the prenatal diagnosis of placenta accreta, especially to identify women with placenta accreta likely to require hysterectomy.

Maternal Plasma RNA Sequencing for Genome-Wide Transcriptomic Profiling and Identification of Pregnancy-Associated Transcripts

BACKGROUND

Analysis of circulating RNA in the plasma of pregnant women has the potential to serve as a powerful tool for noninvasive prenatal testing and research. However, detection of circulating RNA in the plasma in an unbiased and high-throughput manner has been technically challenging. Therefore, only a limited number of circulating RNA species in maternal plasma have been validated as pregnancy- and placenta-specific biomarkers.

METHODS

We explored the use of massively parallel sequencing for plasma transcriptome profiling in first-, second-, and third-trimester pregnant women. Genotyping was performed for amniotic fluid, placental tissues, and maternal blood cells, with exome-enriched sequencing.

RESULTS

In the early pregnancy group comprising 1 first- and 1 second-trimester pregnancy cases, the fetal contribution to the RNA pool in maternal plasma was 3.70%. The relative proportion of fetal contribution was increased to 11.28% in the late pregnancy group comprising 2 third-trimester pregnancy cases. The placental biallelic expression pattern of PAPPA (pregnancy-associated plasma protein A, pappalysin 1), a known pregnancy-specific gene, and the monoallelic expression pattern of H19 [H19, imprinted maternally expressed transcript (non-protein coding)], an imprinted maternally expressed gene, were also detected in the maternal plasma. Furthermore, by direct examination of the maternal plasma transcriptomic profiles before and after delivery, we identified a panel of pregnancy-associated genes.

CONCLUSIONS

Plasma RNA sequencing provides a holistic view of the maternal plasma transcriptomic repertoire. This technology is potentially valuable for using circulating plasma nucleic acids for prenatal testing and research.

The Role of RNAs and microRNAs in Non-Invasive Prenatal Diagnosis

In this paper, all possible clinical applications of circulating mRNA and miRNA for non-invasive prenatal diagnosis appearing in the medical literature so far are described. Data from the literature have also been reported and commented on along with some possible future applications.

Extracellular nucleic acids in maternal circulation as potential biomarkers for placental insufficiency

Since the placenta is being continuously remodeled during normal placental development, extracellular nucleic acids of both fetal and placental origin, packed into either trophoblast-derived apoptotic bodies or shedding syncytiotrophoblast microparticles, may be detected in maternal circulation during the course of normal gestation. Placental-insufficiency-related pregnancy complications have been shown to be associated with excessive placental trophoblast apoptosis and shedding of placenta debris. Recent advances in the field are reviewed with a focus on the diagnostic potential of particular molecular biomarkers and their eventual implementation in the currently used predictive and diagnostic algorithms for placental-insufficiency-related pregnancy complications.

Measurement of mRNA transcripts of very high placental expression in maternal blood as biomarkers of preeclampsia

CONTEXT

mRNA of placental origin in maternal blood shows potential as a clinical biomarker of obstetric diseases such as preeclampsia (PE). We hypothesized that mRNA transcripts very highly expressed in the placenta relative to other tissues will be differentially expressed in PE and be useful as mRNA biomarkers in maternal blood.

OBJECTIVE

Our objective was to identify a panel of genes highly expressed in the placenta and compare their expression in placenta and maternal whole blood from PE vs. control pregnancies.

SETTING

Placental tissue and maternal whole blood specimens were obtained from normotensive controls (n = 15) and pregnancies complicated by severe preterm PE (n = 21).

INTERVENTION

mRNA expression was evaluated by quantitative real-time RT-PCR.

RESULTS

We identified 20 genes exhibiting highest to fourth highest expression in the placenta relative to all other tissues. All genes were detectable in placenta. Nine of the 20 genes were detectable in maternal whole blood. Four of the nine genes detectable in blood (i.e. PLAC3, PLAC4, CRH, and ERVWE1) were significantly increased in both maternal blood and placenta from PE pregnancies. The remaining five genes detectable in maternal blood were unchanged in both blood and placenta from PE pregnancies. Thus, there was complete correlation of gene expression between maternal blood and placenta.

CONCLUSIONS

Circulating mRNA coding genes of high placental expression show strong correlation with transcript levels in preeclamptic placenta. Such transcripts may be promising candidates to screen as mRNA biomarkers of PE in maternal whole blood.

mRNA induces RANTES production in trophoblast cells via TLR3 only when delivered intracellularly using lipid membrane encapsulation

BACKGROUND

Trophoblasts express Toll-like receptor 3 (TLR3). The artificial TLR3 ligand, PolyI:C, induces an inflammatory response in trophoblasts but an endogenous ligand has not been identified. Notably, inflammatory disorders of pregnancy are associated with increased circulating placenta-derived mRNA. Endogenous degraded, uncapped mRNA is recognized by TLR3 in other cell lines.

OBJECTIVE

We tested the hypothesis that plasma-derived mRNA induces an inflammatory response in a trophoblast cell line via TLR3.

METHODS

Experiments were performed in the human first trimester extravillous trophoblast cell line HTR-8/SV neo. Plasma-derived mRNA was amplified using modified template switching and final in vitro transcription. We compared free mRNA (which favors cell surface interaction) to liposomally encapsulated mRNA (which favors intracellular mRNA delivery). We tested for the specific requirement of TLR3 signaling using siRNA. We tested for involvement of the canonical signaling pathway downstream of TLR3 by measuring NF-κB and IFN regulatory factor transcriptional activity using firefly-luciferase constructs.

RESULTS

Free mRNA did not induce RANTES production. In contrast, liposomal mRNA resulted in marked induction of RANTES production (non-stimulated control 3.4 ± 0.6 pg/mL, liposomal mRNA 169.7 ± 26.2 pg/mL, p < 0.001), and this RANTES production was abolished by siRNA for TLR3. Downstream of TLR3, liposomal mRNA-induced dose-response NF-κB and IFN regulatory factor transcriptional activity, and IFN beta production.

CONCLUSION

Plasma-derived 5' uncapped mRNA delivered intracellularly signals to induce NF-κB activation and increase RANTES production via TLR3.

Gene expression in chorionic villous samples at 11 weeks of gestation in women who develop pre-eclampsia later in pregnancy: implications for screening

OBJECTIVES

To determine the gene expression profile in chorionic villous samples (CVSs) of women destined to develop pre-eclampsia (PE).

METHOD

Case-control study encompassing five women destined to develop PE [cases matched for gestational age with 30 controls]. We quantified mRNA expression on tissue samples from CVS of normal and PE patients. We then assessed mRNA expressions of cathepsin (CTSD), angiopoietin 2 (ANGPT2), interleukin 8, chemokine (C-X-C motif) ligand 10, neurokinin B (NKB), matrix metallopeptidase 9, major histocompatibility complex, class I, C (HLA-C)and human leukocyte antigen-G (HLA-G). Data were analyzed by nonparametric rank analysis.

RESULTS

For all the mRNA species considered in this study, except CTSD and ANGPT2, all the mean observed ranks in the PE group were significantly altered compared with the rank expectation among controls. mRNA for NKB and HLA-C were the markers with the highest degree of aberration in PE, compared with those in controls.

CONCLUSION

Our study has directly showed that gene expressions relating to trophoblastic cell invasion or utero-placental hemodynamic adaptation are altered in the first trimester trophoblasts that go on to develop PE later. These results posit the use of residual CVS as a possible screening method for PE.

PP13 mRNA expression in the cellular component of maternal blood as a marker for preeclampsia

OBJECTIVE

To assess the PP13 expression in the cellular component of blood in both preeclamptic patients and asymptomatic pregnant women during the early second trimester.

METHODS

In the case-control study, peripheral blood samples were obtained from pregnant women with preeclampsia (n = 24) and controls (n = 22). PP13 RNA expression was quantified in the cellular component of the blood by reverse transcription PCR assay. Next, as a cohort study of asymptomatic pregnant women at early gestation, cellular RNA from 41 cases who developed preeclampsia at later gestation and 123 cases of control were analysed, and the possibility of prediction of preeclampsia was assessed.

RESULTS

In symptomatic patients, PP13 level in preeclampsia was significantly lower than that in controls (p < 0.001). In the asymptomatic pregnant women, the PP13 level in preeclampsia was significantly lower than that in the controls (p = 0.008). A receiver-operating characteristics (ROC) curve yielded a detection rate of 24 and 31% at a false positive rate of 5 and 10% respectively.

CONCLUSION

An alteration in the cellular PP13 RNA expression would affect the placental pathophysiological change. The cellular PP13 expression level could therefore potentially be one of the key markers to predict the clinical onset of preeclampsia.

Cell-free placental mRNA in maternal plasma to predict placental invasion in patients with placenta accreta

OBJECTIVE

To evaluate whether measuring cell-free placental mRNA in maternal plasma improves the diagnostic accuracy of ultrasound and color Doppler in detecting placental invasion in patients at risk for placenta accreta.

METHODS

Thirty-five singleton pregnant women of more than 28 weeks of gestation and at risk for placenta accreta underwent ultrasound and color Doppler assessment. Cell-free placental mRNA in maternal plasma was measured using real-time reverse-transcription polymerase chain reaction. Patients were classified into 2 groups based on the findings at cesarean delivery and histological examination: women with placenta accreta (n=7) and women without placenta accreta (n=28).

RESULTS

The median MoM (multiples of the median) value of cell-free placental mRNA was significantly higher in patients with placenta accreta than in those without placenta accreta (6.50 vs 2.60; P<0.001. Moreover, cell-free placental mRNA was significantly elevated in patients with placenta increta and percreta than in those with simple accreta. Six false-positive results were found on ultrasound, all from patients without placenta accreta and an insignificant rise in cell-free placental mRNA levels.

CONCLUSION

Measuring cell-free placental mRNA in maternal plasma may increase the accuracy of ultrasound and color Doppler in prenatal prediction of placental invasion in patients with suspected placenta accreta.

Cellular mRNA expressions of anti-oxidant factors in the blood of preeclamptic women

OBJECTIVE

To assess the alterations of mRNA expressions associated with oxidative stress in the cellular component of blood from pregnant women with pre-eclampsia.

METHODS

Peripheral blood samples were obtained from pregnant women with and without pre-eclampsia. Cellular RNA was subjected to a reverse transcription polymerase chain reaction (PCR) assay in order to examine the mRNA distribution among women with pre-eclampsia (n = 24) and control subjects (n = 24) during 35-41 weeks of gestation. The data were analyzed by non-parametric statistics.

RESULTS

Significant differences between the pre-eclampsia subjects and the controls were observed in the gene expressions associated with oxidative stress. Lower values in the pre-eclampsia group were found for heme oxygenase (HO)-1, HO-2, catalase and superoxide dismutase (SOD). The HO-1, HO-2 and the catalase levels significantly correlated with proteinuria, and the HO-2 level with systolic blood pressure.

CONCLUSION

Significantly lower concentrations of HO-1, HO-2, SOD and catalase are found in the cellular component of blood from pre-eclamptic patients. The values correlate with the severity of pre-eclampsia. These findings indicate that enhanced oxidative stress and a decrease in the number of anti-oxidant enzymes may be associated with pre-eclampsia.

Prediction of preeclampsia by analysis of cell-free messenger RNA in maternal plasma

OBJECTIVE

The purpose of this study was to predict the occurrence of preeclampsia in a series of patients at gestational week 15-20 weeks, with the use of a panel of messenger RNA markers.

STUDY DESIGN

Data from 62 patients with preeclampsia who were asymptomatic at the time of blood testing and 310 control subjects were analyzed. Multivariable analysis was performed with discriminant analysis.

RESULTS

Univariable analysis identified vascular endothelial growth factor receptor 1 as the marker with the highest detection rate; placenta-specific 1 with the lowest. Mean estimated score for preeclampsia was 9.4 for control subjects and 72.5 for subjects who experienced preeclampsia. A receiver operating characteristic curve that was obtained with the estimated score for preeclampsia as a test variable yielded a detection rate of 84% (95% CI, 71.8-91.5) at a 5% false-positive rate with an area under the curve of 0.927 (P < .001). Again, detection rate and score for each patient for classification as preeclamptic correlated with severity.

CONCLUSION

A panel of messenger RNA is able to detect subjects who will experience preeclampsia.

Gene expression in chorionic villous samples at 11 weeks' gestation from women destined to develop preeclampsia

OBJECTIVE

To evaluate the direct alterations in mRNA expression among chorionic villous samples from 11 weeks' pregnant women who would develop preeclampsia (PE) later in the pregnancy.

METHOD

Case-control study encompassing five women destined to develop PE [cases matched 1:5 for gestational age (GA) with 25 controls]. We quantified mRNA expression on tissue samples from chorionic villous sampling (CVS) of normal and PE patients. We then assessed mRNA expressions of vascular endothelial growth factor (VEGFA), VEGFA receptor 1 (Flt-1), endoglin (Eng), placental growth factor (PlGF), transforming growth factor-beta1 (TGF-beta1), heme oxygenase-1 (HO-1) and superoxide dismutase (SOD). Data were analyzed by nonparametric rank analysis.

RESULTS

For all the mRNA species considered in this study, all the mean observed ranks in the PE group were significantly altered compared to the rank expectation among controls. mRNA for Eng and TGF-beta1 were the markers with the highest degree of aberration in PE, in respect to controls. The results are consistent with those already reported for the corresponding circulating proteins. mRNA for HO-1 and SOD were instead associated with the lowest aberration.

CONCLUSION

It is assumed that the pathogenesis of PE is associated with pathophysiological alterations to trophoblasts in early gestation. Our study has directly proved that gene expressions relating to angiogenesis or oxidative stress are altered in the first trimester trophoblasts that go on to develop PE later. These results would put the basis for a possible screening method for PE by using residual CVS.

PP13 mRNA expression in trophoblasts from preeclamptic placentas

To assess the role of placental protein 13 (PP13) in the pathogenesis of preeclampsia, the messenger RNA expression of PP13 was investigated in the trophoblasts from first and third trimester placenta. First, syncytiotrophoblasts and extravillous trophoblasts were separated from frozen section of third trimester placenta obtained from pregnant women with and without preeclampsia by laser microdissection. The PP13 levels of syncytiotrophoblasts were significantly higher than those of extravillous trophoblasts. The expression levels in syncytiotrophoblasts from the preeclampsia were significantly lower than those from normal. Next, the PP13 expression was assessed in trophoblasts from residual samples of chorionic villus sampling at 11 weeks of gestation, who subsequently developed preeclampsia. The levels in the preeclampsia group were significantly lower than those of normal cases. These findings indicate that an alteration in the PP13-messenger RNA expression in the trophoblasts may be associated with the pathogenesis of preeclampsia.

Stability of placental RNA using dried maternal blood spots

Having demonstrated successful recovery and detection of placental transcripts from dried blood spots (DBS), various preanalytical conditions were examined to determine optimal handling of samples. The role of several factors was explored, including temperature (4 degrees C versus 25 degrees C), processing time (24 h to 8 weeks), and addition of preservatives (RNA later and formalin) that may interfere with stability and detection of placental transcripts in DBS. mRNA transcripts encoding human glyceraldehyde-3-phosphate dehydrogenase (GAPDH; internal control) and beta-human chorionic gonadotrophin (beta HCG; placental) were analysed by real-time-polymerase chain reaction using DBS from 23 pregnant women. GAPDH and beta HCG transcripts were detected in all samples 24 h after collection. Although treatment of blood with RNA later did not affect RNA recovery, formalin treatment negatively affected RNA recovery from DBS. Temperature did not have a significant effect on levels of either transcript. Storage time caused a significant decrease in GAPDH after 4 weeks (P = 0.014) and beta HCG after 1 week (P = 0.007). Decrease of beta HCG levels after 1 week followed by steady detectable levels for up to 4 weeks suggests two populations of circulating placental transcript exist, a population susceptible to degradation in blood versus a more stable form. Therefore, defining proper parameters for collection and storage of DBS further reinforces reliable analysis of target sequences for clinical testing.

Non-invasive prenatal diagnosis: implications for antenatal diagnosis and management of high-risk pregnancies

There has been a huge effort in the last 2-3 decades to develop non-invasive prenatal diagnosis to avoid the risks to the fetus caused by invasive procedures. Obtaining fetal nucleic material for molecular analysis without the need of invasive procedures has been a goal of prenatal diagnosis for many years; this is now been made possible by the use of non-cellular fetal nucleic acids circulating in maternal blood. The placenta is the primary source of these nucleic acids, raising the possibility that they could be a marker for pregnancy complications resulting from placental disease/dysfunction such as pre-eclampsia and fetal growth restriction. If so, these markers might be able to identify cases at risk, predict disease and/or its severity or allow early diagnosis. This has the potential to allow improvements in the management of complicated pregnancies.

Evaluation of physiological alterations of the placenta through analysis of cell-free messenger ribonucleic acid concentrations of angiogenic factors

OBJECTIVE

Placental messenger ribonucleic acid (mRNA) has been shown to circulate in maternal plasma. We investigated concentrations of vascular endothelial growth factor (VEGF), VEGF receptor-1 (VEGFR-1), and endoglin in subjects with preeclampsia, compared with normal pregnancies.

STUDY DESIGN

Peripheral blood samples were obtained from preeclampsia (n = 43) and control subjects (n = 41). Plasma ribonucleic acid was subjected to analysis by reverse transcription-polymerase chain reaction assay to examine the mRNA distribution among women with preeclampsia and control subjects during weeks 35-41 of gestation.

RESULTS

Concentrations of VEGF, VEGFR-1, and endoglin mRNA of women with preeclampsia were significantly increased. The mRNA values were observed to correlate directly with the severity of hypertension and proteinuria. VEGFR-1 mRNA was markedly elevated in women with preeclampsia and hemolysis, elevated liver enzymes, and low platelet syndrome.

CONCLUSION

The mRNA concentrations of VEGF, VEGFR-1, and endoglin were observed to correlate directly with the severity of preeclampsia.

Placenta-derived, cellular messenger RNA expression in the maternal blood of preeclamptic women

OBJECTIVE

To perform gene expression profiling and real-time quantitative reverse-transcription polymerase chain reaction (PCR) analysis to identify biomarkers of preeclampsia in cellular messenger RNA (mRNA) from maternal blood.

METHODS

We performed a microarray analysis with five maternal blood samples from women with preeclampsia and five matched control subjects. Up-regulated gene expression was further analyzed through reverse-transcription PCR analysis with 28 consecutive blood samples from women affected with preeclampsia and 29 controls.

RESULTS

Both pregnancy-specific beta1 glycoprotein and trophoblast glycoprotein were selected based on microarray analysis. Reverse-transcription PCR analysis detected significantly increased mRNA concentrations among women in the preeclampsia group. When stratified according to mild or severe preeclampsia, 19.2-fold and 41.8-fold increases in pregnancy-specific beta1 glycoprotein and 8.3-fold and 10.6-fold increases in trophoblast glycoprotein were observed, respectively. Among women with hemolysis, elevated liver enzymes, and low platelet count syndrome, 51.6-fold and 13.1-fold increases in pregnancy-specific beta1 glycoprotein and trophoblast glycoprotein were observed, respectively. In the preeclampsia group, pregnancy-specific beta1 glycoprotein correlated with severity of proteinuria (P<.001) and systolic blood pressure (P=.01).

CONCLUSION

The mRNA expression of pregnancy-specific beta1 glycoprotein and trophoblast glycoprotein is up-regulated in cells circulating within blood from women with preeclampsia, and pregnancy-specific beta1 glycoprotein expression is positively correlated with the clinical severity of preeclampsia.

LEVEL OF EVIDENCE

II.

Cell-free mRNA concentrations of CRH,PLAC1, and selectin-P are increased in the plasma of pregnant women with preeclampsia

OBJECTIVE

To compare mRNA concentrations of corticotrophin-releasing hormone (CRH), placenta specific-1 (PLAC1), and selectin-P in preeclamptic and normal pregnancies.

METHODS

Peripheral blood samples were obtained from 43 pregnant women with preeclampsia and 41 control subjects. Plasma was harvested from samples and RNA extracted. Plasma RNA was analyzed using reverse transcription polymerase chain reaction (PCR) assay. Median concentrations of CRH, PLAC1, and selectin-P mRNA in plasma were compared, to assess possible differences in distribution. Data were also stratified and compared according to clinical severity of preeclampsia. Finally, CRH, PLAC1, and selectin-P were plotted against quantitative distributions of blood pressure and proteinuria.

RESULTS

All markers were differently distributed between cases and controls. Median values in subgroups correlated with severity of preeclampsia. All markers correlated with both. Selectin-P was identified as the marker with the highest degree of correlation. No correlation was found between any markers in the control group and proteinuria or blood pressure.

CONCLUSION

CRH, PLAC1, and selectin-P are distributed differently in preeclampsia cases compared to controls and correlate with signs of preeclampsia.

Performance of a panel of maternal serum markers in predicting preeclampsia at 11–15 weeks' gestation

OBJECTIVE

We evaluated whether a discriminant model of prediction based on quantitative distribution of a panel of biomolecules in maternal serum can discriminate normal pregnancies from those who will develop preeclampsia (PE) prior to onset of clinical symptoms at 11-15 weeks' gestation.

METHODS

Case control study encompassing 56 women destined to develop PE cases matched 1:3 for gestational age with 168 controls. After multiple of median (MoM) conversion of all available markers, comprising total Activin A (t-activin A), P-selectin, and vascular endothelial growth factor receptor (VEGFR) the combined likelihood ratios generated for each marker were used to calculate, for each patient enrolled in the study, the odds of being affected given a positive results (OAPR) of developing PE. For all the analyses performed, the type II error was < 20% with a type I error fixed at 5%.

RESULTS

Data were expressed in MoM of controls. P-selectin was identified as the marker with the best discriminant ability between controls and PE, followed by (t-activin A). No significant differences in VEGFR were observed between cases and controls. By using a 3% prevalence of PE (or, about 1:33) we found that the median OAPR of developing PE for the 56 cases was 1:9 or 10% (1:1-1:417). The median OAPR of PE for controls was 1:40 or 2.5% (range, 1:6-1:4205). Detection rate of the statistical model, with a 5% false-positive rate was 59%.

CONCLUSION

This analysis revealed that maternal serum markers assessed at the first and second trimester of pregnancy in asymptomatic patients can improve the early detection of cases at higher risk of developing PE.