Placental transcriptional and histologic subtypes of normotensive fetal growth restriction are comparable to preeclampsia

Identification of divergent placental profiles in clinically distinct pregnancy complications revealed by the transcriptome

INTRODUCTION

Pregnancy complications, including preeclampsia (PE), preterm birth (PTB), and intra-uterine growth restriction (IUGR) have individually been associated with inflammation but the combined comparative analysis of their placental profiles at the transcriptomic and histological levels is lacking.

METHODS

Bulk RNA-sequencing of human placental biopsies from uncomplicated term pregnancies (CTL) and pregnancies complicated with early-onset (EO), and late-onset (LO) PE, as well as PTB and term IUGR were used to characterize individual molecular profiles. We also applied immune-cell-specific cellular deconvolution to address local immune cell compositions and analyzed placental lesions by histology to further characterize these complications.

RESULTS

Transcriptome analysis revealed that clinically distinct complications differentiated themselves in unique ways compared to CTLs. Only TMEM136 was commonly modulated. Compared to CTLs, we found that PTB and IUGR were the most distinct, with LOPE being the least distinct. PTB and IUGR revealed differently enhanced inflammatory pathways, where PTB had general inflammatory responses and IUGR had immune cell activation. This inflammation was reflected in the histological profile for PTB only, whereas structural lesions were elevated in all complications. Placental lesions additionally had corresponding enhancement in inflammatory and structural biological processes. We observed that having co-complications, particularly for PTB with or without IUGR, impacted placental transcriptomes. Lastly, cellular deconvolution uncovered shared immune features among the complications.

DISCUSSION

Overall, we provide evidence that these pregnancy complications are not only distinct in their clinical manifestations but also in their placental profiles, which could be leveraged to understand their underlying mechanisms and could offer therapeutic targets.

Prediction of preterm birth in growth-restricted and appropriate-for-gestational-age infants using maternal PlGF and the sFlt-1/PlGF ratio-A prospective study

OBJECTIVE

To assess the utility of placental growth factor (PlGF) levels and the soluble fms-like tyrosine kinase-1/placental growth factor (sFlt-1/PlGF) ratio to predict preterm birth (PTB) for infants with fetal growth restriction (FGR) and those appropriate for gestational age (AGA).

DESIGN

Prospective, observational cohort study.

SETTING

Tertiary maternity hospital in Australia.

POPULATION

There were 320 singleton pregnancies: 141 (44.1%) AGA, 83 (25.9%) early FGR (<32+0 weeks) and 109 (30.0%) late FGR (≥32+0 weeks).

METHODS

Maternal serum PlGF and sFlt-1/PlGF ratio were measured at 4-weekly intervals from recruitment to delivery. Low maternal PlGF levels and elevated sFlt-1/PlGF ratio were defined as <100 ng/L and >5.78 if <28 weeks and >38 if ≥28 weeks respectively. Cox proportional hazards models were used. The analysis period was defined as the time from the first measurement of PlGF and sFlt-1/PlGF ratio to the time of birth or censoring.

MAIN OUTCOME MEASURES

The primary study outcome was overall PTB. The relative risks (RR) of birth within 1, 2 and 3 weeks and for medically indicated and spontaneous PTB were also ascertained.

RESULTS

The early FGR cohort had lower median PlGF levels (54 versus 229 ng/L, p < 0.001) and higher median sFlt-1 levels (2774 ng/L versus 2096 ng/L, p < 0.001) and sFlt-1/PlGF ratio higher (35 versus 10, p < 0.001). Both PlGF <100 ng/L and elevated sFlt-1/PlGF ratio were strongly predictive for PTB as well as PTB within 1, 2 and 3 weeks of diagnosis. For both FGR and AGA groups, PlGF <100 ng/L or raised sFlt-1/PlGF ratio were strongly associated with increased risk for medically indicated PTB. The highest RR was seen in the FGR cohort when PlGF was <100 ng/L (RR 35.20, 95% CI 11.48-175.46).

CONCLUSIONS

Low maternal PlGF levels and elevated sFlt-1/PlGF ratio are potentially useful to predict PTB in both FGR and AGA pregnancies.

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.

Automated detection of microscopic placental features indicative of maternal vascular malperfusion using machine learning

INTRODUCTION

Hypertensive disorders of pregnancy (HDP) and fetal growth restriction (FGR) are common obstetrical complications, often with pathological features of maternal vascular malperfusion (MVM) in the placenta. Currently, clinical placental pathology methods involve a manual visual examination of histology sections, a practice that can be resource-intensive and demonstrates moderate-to-poor inter-pathologist agreement on diagnostic outcomes, dependant on the degree of pathologist sub-specialty training.

METHODS

This study aims to apply machine learning (ML) feature extraction methods to classify digital images of placental histopathology specimens, collected from cases of HDP [pregnancy induced hypertension (PIH), preeclampsia (PE), PE + FGR], normotensive FGR, and healthy pregnancies, according to the presence or absence of MVM lesions. 159 digital images were captured from histological placental specimens, manually scored for MVM lesions (MVM- or MVM+) and used to develop a support vector machine (SVM) classifier model, using features extracted from pre-trained ResNet18. The model was trained with data augmentation and shuffling, with the performance assessed for patch-level and image-level classification through measurements of accuracy, precision, and recall using confusion matrices.

RESULTS

The SVM model demonstrated accuracies of 70 % and 79 % for patch-level and image-level MVM classification, respectively, with poorest performance observed on images with borderline MVM presence, as determined through post hoc observation.

DISCUSSION

The results are promising for the integration of ML methods into the placental histopathological examination process. Using this study as a proof-of-concept will lead our group and others to carry ML models further in placental histopathology.

Quantitative Proteomics of Maternal Blood Plasma in Isolated Intrauterine Growth Restriction

Intrauterine growth restriction (IUGR) remains a significant concern in modern obstetrics, linked to high neonatal health problems and even death, as well as childhood disability, affecting adult quality of life. The role of maternal and fetus adaptation during adverse pregnancy is still not completely understood. This study aimed to investigate the disturbance in biological processes associated with isolated IUGR via blood plasma proteomics. The levels of 125 maternal plasma proteins were quantified by liquid chromatography-multiple reaction monitoring mass spectrometry (LC-MRM MS) with corresponding stable isotope-labeled peptide standards (SIS). Thirteen potential markers of IUGR (Gelsolin, Alpha-2-macroglobulin, Apolipoprotein A-IV, Apolipoprotein B-100, Apolipoprotein(a), Adiponectin, Complement C5, Apolipoprotein D, Alpha-1B-glycoprotein, Serum albumin, Fibronectin, Glutathione peroxidase 3, Lipopolysaccharide-binding protein) were found to be inter-connected in a protein-protein network. These proteins are involved in plasma lipoprotein assembly, remodeling, and clearance; lipid metabolism, especially cholesterol and phospholipids; hemostasis, including platelet degranulation; and immune system regulation. Additionally, 18 proteins were specific to a particular type of IUGR (early or late). Distinct patterns in the coagulation and fibrinolysis systems were observed between isolated early- and late-onset IUGR. Our findings highlight the complex interplay of immune and coagulation factors in IUGR and the differences between early- and late-onset IUGR and other placenta-related conditions like PE. Understanding these mechanisms is crucial for developing targeted interventions and improving outcomes for pregnancies affected by IUGR.

Body Mass Index, Adverse Pregnancy Outcomes, and Cardiovascular Disease Risk

BACKGROUND

Obesity is a well-established risk factor for both adverse pregnancy outcomes (APOs) and cardiovascular disease (CVD). However, it is not known whether APOs are mediators or markers of the obesity-CVD relationship. This study examined the association between body mass index, APOs, and postpartum CVD risk factors.

METHODS

The sample included adults from the nuMoM2b (Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-To-Be) Heart Health Study who were enrolled in their first trimester (6 weeks-13 weeks 6 days gestation) from 8 United States sites. Participants had a follow-up visit at 3.7 years postpartum. APOs, which included hypertensive disorders of pregnancy, preterm birth, small-for-gestational-age birth, and gestational diabetes, were centrally adjudicated. Mediation analyses estimated the association between early pregnancy body mass index and postpartum CVD risk factors (hypertension, hyperlipidemia, and diabetes) and the proportion mediated by each APO adjusted for demographics and baseline health behaviors, psychosocial stressors, and CVD risk factor levels.

RESULTS

Among 4216 participants enrolled, mean±SD maternal age was 27±6 years. Early pregnancy prevalence of overweight was 25%, and obesity was 22%. Hypertensive disorders of pregnancy occurred in 15%, preterm birth in 8%, small-for-gestational-age birth in 11%, and gestational diabetes in 4%. Early pregnancy obesity, compared with normal body mass index, was associated with significantly higher incidence of postpartum hypertension (adjusted odds ratio, 1.14 [95% CI, 1.10-1.18]), hyperlipidemia (1.11 [95% CI, 1.08-1.14]), and diabetes (1.03 [95% CI, 1.01-1.04]) even after adjustment for baseline CVD risk factor levels. APOs were associated with higher incidence of postpartum hypertension (1.97 [95% CI, 1.61-2.40]) and hyperlipidemia (1.31 [95% CI, 1.03-1.67]). Hypertensive disorders of pregnancy mediated a small proportion of the association between obesity and incident hypertension (13% [11%-15%]) and did not mediate associations with incident hyperlipidemia or diabetes. There was no significant mediation by preterm birth or small-for-gestational-age birth.

CONCLUSIONS

There was heterogeneity across APO subtypes in their association with postpartum CVD risk factors and mediation of the association between early pregnancy obesity and postpartum CVD risk factors. However, only a small or nonsignificant proportion of the association between obesity and CVD risk factors was mediated by any of the APOs, suggesting APOs are a marker of prepregnancy CVD risk and not a predominant cause of postpartum CVD risk.

Similarity network fusion to identify phenotypes of small-for-gestational-age fetuses

Fetal growth restriction (FGR) affects 5-10% of pregnancies, is the largest contributor to fetal death, and can have long-term consequences for the child. Implementation of a standard clinical classification system is hampered by the multiphenotypic spectrum of small fetuses with substantial differences in perinatal risks. Machine learning and multiomics data can potentially revolutionize clinical decision-making in FGR by identifying new phenotypes. Herein, we describe a cluster analysis of FGR based on an unbiased machine-learning method. Our results confirm the existence of two subtypes of human FGR with distinct molecular and clinical features based on multiomic analysis. In addition, we demonstrated that clusters generated by machine learning significantly outperform single data subtype analysis and biologically support the current clinical classification in predicting adverse maternal and neonatal outcomes. Our approach can aid in the refinement of clinical classification systems for FGR supported by molecular and clinical signatures.

Integrated unbiased multiomics defines disease-independent placental clusters in common obstetrical syndromes

BACKGROUND

Placental dysfunction, a root cause of common syndromes affecting human pregnancy, such as preeclampsia (PE), fetal growth restriction (FGR), and spontaneous preterm delivery (sPTD), remains poorly defined. These common, yet clinically disparate obstetrical syndromes share similar placental histopathologic patterns, while individuals within each syndrome present distinct molecular changes, challenging our understanding and hindering our ability to prevent and treat these syndromes.

METHODS

Using our extensive biobank, we identified women with severe PE (n = 75), FGR (n = 40), FGR with a hypertensive disorder (FGR + HDP; n = 33), sPTD (n = 72), and two uncomplicated control groups, term (n = 113), and preterm without PE, FGR, or sPTD (n = 16). We used placental biopsies for transcriptomics, proteomics, metabolomics data, and histological evaluation. After conventional pairwise comparison, we deployed an unbiased, AI-based similarity network fusion (SNF) to integrate the datatypes and identify omics-defined placental clusters. We used Bayesian model selection to compare the association between the histopathological features and disease conditions vs SNF clusters.

RESULTS

Pairwise, disease-based comparisons exhibited relatively few differences, likely reflecting the heterogeneity of the clinical syndromes. Therefore, we deployed the unbiased, omics-based SNF method. Our analysis resulted in four distinct clusters, which were mostly dominated by a specific syndrome. Notably, the cluster dominated by early-onset PE exhibited strong placental dysfunction patterns, with weaker injury patterns in the cluster dominated by sPTD. The SNF-defined clusters exhibited better correlation with the histopathology than the predefined disease groups.

CONCLUSIONS

Our results demonstrate that integrated omics-based SNF distinctively reclassifies placental dysfunction patterns underlying the common obstetrical syndromes, improves our understanding of the pathological processes, and could promote a search for more personalized interventions.

Identification of biomarkers and sex differences in the placenta of fetal growth restriction

AIM

Fetal growth restriction (FGR) can lead to short-term and long-term impairments in the fetus. The placenta functions as an exchanger for substance transport, playing a critical role in fetal growth. However, the mechanism from the placental standpoint is still not fully understood. In this study, we aimed to investigate the pathophysiological mechanisms in the placenta that mediated the development of FGR and sex differences.

METHODS

We analyzed the gene expression profiles of GSE100415 containing specific normotensive FGR placental samples and GSE114691 with canonical samples using three different methods, differentially expressed gene analysis, weighted gene co-expression network analysis, and gene set enrichment analysis. Gene enrichment was performed, including the gene ontology and pathway from the Kyoto Encyclopedia of Genes and Genomes. The important process was then validated in pregnant Wistar rats subcutaneously administered dexamethasone (0.2 mg/kg/d) or saline from gestation Day 9 to 21.

RESULTS

Our results revealed little difference between the comparison of normal and normotensive FGR placental samples but confirmed the sex difference. Further analyses of the canonical samples identified the occurrence of vascular dysfunction, which was validated by the calculation of the vascular lumen area, showing that the vascular lumen in the FGR group was more than in the control. We also discovered 17 significantly expressed genes from the involved eigengenes.

CONCLUSION

Our study provides an important theoretical and experimental basis to reevaluate the development of FGR from the placental standpoint and suggests a series of biomarkers for future clinical use.

Placental Pathology and Pregnancy Complications

Placental pathology assessment following delivery provides an opportunity to identify the presence and type of disease that can mediate major obstetrical complications, especially in cases where the fetus is growth-restricted, born premature, or stillborn, or if the mother suffers from severe hypertensive morbidities [...].

Transcriptomics-Based Subphenotyping of the Human Placenta Enabled by Weighted Correlation Network Analysis in Early-Onset Preeclampsia With and Without Fetal Growth Restriction

BACKGROUND

Placental disorders contribute to pregnancy complications, including preeclampsia and fetal growth restriction (FGR), but debate regarding their specific pathobiology persists. Our objective was to apply transcriptomics with weighted gene correlation network analysis to further clarify the placental dysfunction in these conditions.

METHODS

We performed RNA sequencing with weighted gene correlation network analysis using human placental samples (n=30), separated into villous tissue and decidua basalis, and clinically grouped as follows: (1) early-onset preeclampsia (EOPE)+FGR (n=7); (2) normotensive, nonanomalous preterm FGR (n=5); (2) EOPE without FGR (n=8); (4) spontaneous idiopathic preterm birth (n=5) matched for gestational age; and (5) uncomplicated term births (n=5). Our data was compared with RNA sequencing data sets from public databases (GSE114691, GSE148241, and PRJEB30656; n=130 samples).

RESULTS

We identified 14 correlated gene modules in our specimens, of which most were significantly correlated with birthweight and maternal blood pressure. Of the 3 network modules consistently predictive of EOPE±FGR across data sets, we prioritized a coexpression gene group enriched for hypoxia-response and metabolic pathways for further investigation. Cluster analysis based on transcripts from this module and the glycolysis/gluconeogenesis metabolic pathway consistently distinguished a subset of EOPE±FGR samples with an expression signature suggesting modified tissue bioenergetics. We demonstrated that the expression ratios of LDHA/LDHB and PDK1/GOT1 could be used as surrogate indices for the larger panels of genes in identifying this subgroup.

CONCLUSIONS

We provide novel evidence for a molecular subphenotype consistent with a glycolytic metabolic shift that occurs more frequently but not universally in placental specimens of EOPE±FGR.

Placental transcriptome analysis of hypertensive pregnancies identifies distinct gene expression profiles of preeclampsia superimposed on chronic hypertension

BACKGROUND

The pathogenesis of preeclampsia superimposed on chronic hypertension (SI) is poorly understood relative to preeclampsia (PreE) occurring in pregnant people without chronic hypertension. Placental transcriptomes in pregnancies complicated by PreE and SI have not been previously compared.

METHODS

We identified pregnant people in the University of Michigan Biorepository for Understanding Maternal and Pediatric Health with hypertensive disorders affecting singleton, euploid gestations (N = 36) along with non-hypertensive control subjects (N = 12). Subjects were grouped as: (1) normotensive (N = 12), (2) chronic hypertensive (N = 13), (3) preterm PreE with severe features (N = 5), (4) term PreE with severe features (N = 11), (5) preterm SI (N = 3), or (6) term SI (N = 4). Bulk RNA sequencing of paraffin-embedded placental tissue was performed. The primary analysis assessed differential gene expression relative to normotensive and chronic hypertensive placentas, where Wald adjusted P values < 0.05 were considered significant. Unsupervised clustering analyses and correlation analyses were performed between conditions of interest, and a gene ontology was constructed.

RESULTS

Comparing samples from pregnant people with hypertensive diseases to non-hypertensive controls, there were 2290 differentially expressed genes. The log2-fold changes in genes differentially expressed in chronic hypertension correlated better with term (R = 0.59) and preterm (R = 0.63) PreE with severe features than with term (R = 0.21) and preterm (R = 0.22) SI. A relatively poor correlation was observed between preterm SI and preterm PreE with severe features (0.20) as well as term SI and term PreE with severe features (0.31). The majority of significant genes were downregulated in term and preterm SI versus normotensive controls (92.1%, N = 128). Conversely, most term and preterm PreE with severe features genes were upregulated compared to the normotensive group (91.8%, N = 97). Many of the upregulated genes in PreE with the lowest adjusted P values are known markers of abnormal placentation (e.g., PAAPA, KISS1, CLIC3), while the downregulated genes with the greatest adjusted P values in SI have fewer known pregnancy-specific functions.

CONCLUSIONS

We identified unique placental transcriptional profiles in clinically relevant subgroups of individuals with hypertension in pregnancy. Preeclampsia superimposed on chronic hypertension was molecularly distinct from preeclampsia in individuals without chronic hypertension, and chronic hypertension without preeclampsia, suggesting that preeclampsia superimposed on hypertension may represent a distinct entity.

Circulating biomarkers associated with placental dysfunction and their utility for predicting fetal growth restriction

Fetal growth restriction (FGR) leading to low birth weight (LBW) is a major cause of neonatal morbidity and mortality worldwide. Normal placental development involves a series of highly regulated processes involving a multitude of hormones, transcription factors, and cell lineages. Failure to achieve this leads to placental dysfunction and related placental diseases such as pre-clampsia and FGR. Early recognition of at-risk pregnancies is important because careful maternal and fetal surveillance can potentially prevent adverse maternal and perinatal outcomes by judicious pregnancy surveillance and careful timing of birth. Given the association between a variety of circulating maternal biomarkers, adverse pregnancy, and perinatal outcomes, screening tests based on these biomarkers, incorporating maternal characteristics, fetal biophysical or circulatory variables have been developed. However, their clinical utility has yet to be proven. Of the current biomarkers, placental growth factor and soluble fms-like tyrosine kinase 1 appear to have the most promise for placental dysfunction and predictive utility for FGR.

Placental pathology is necessary to understand common pregnancy complications and achieve an improved taxonomy of obstetrical disease

The importance of a fully functioning placenta for a good pregnancy outcome is unquestioned. Loss of function can lead to pregnancy complications and is often detected by a thorough placental pathologic examination. Placental pathology has advanced the science and practice of obstetrics and neonatal-perinatal medicine by classifying diseases according to underlying biology and specific patterns of injury. Many past obstacles have limited the incorporation of placental findings into both clinical studies and day-to-day practice. Limitations have included variability in the nomenclature used to describe placental lesions, a shortage of perinatal pathologists fully competent to analyze placental specimens, and a troubling lack of understanding of placental diagnoses by clinicians. However, the potential use of placental pathology for phenotypic classification, improved understanding of the biology of adverse pregnancy outcomes, the development of treatment and prevention, and patient counseling has never been greater. This review, written partly in response to a recent critique published in a major obstetrics-gynecology journal, reexamines the role of placental pathology by reviewing current concepts of biology; explaining the most recent terminology; emphasizing the usefulness of specific diagnoses for obstetrician-gynecologists, neonatologists, and patients; previewing upcoming changes in recommendations for placental submission; and suggesting future improvements. These improvements should include further consideration of overall healthcare costs, cost-effectiveness, the clinical value added of placental assessment, improvements in placental pathology education and practice, and leveraging of placental pathology to identify new biomarkers of disease and evaluate novel therapies tailored to specific clinicopathologic phenotypes of both women and infants.

Histopathologic and Transcriptomic Profiling Identifies Novel Trophoblast Defects in Patients With Preeclampsia and Maternal Vascular Malperfusion

Preeclampsia (PE) is a heterogeneous disease for which the current clinical classification system is based on the presence or absence of specific clinical features. PE-associated placentas also show heterogeneous findings on pathologic examination, suggesting that further subclassification is possible. We combined clinical, pathologic, immunohistochemical, and transcriptomic profiling of placentas to develop integrated signatures for multiple subclasses of PE. In total, 303 PE and 1388 nonhypertensive control placentas were included. We found that maternal vascular malperfusion (MVM) in the placenta was associated with preterm PE with severe features and with small-for-gestational-age neonates. Interestingly, PE placentas with either MVM or no histologic pattern of injury showed a linear decrease in proliferative (p63+) cytotrophoblast per villous area with increasing gestational age, similar to placentas obtained from the nonhypertensive patient cohort; however, PE placentas with fetal vascular malperfusion or villitis of unknown etiology lost this phenotype. This is mainly because of cases of fetal vascular malperfusion in placentas of patients with preterm PE and villitis of unknown etiology in placentas of patients with term PE, which are associated with a decrease or increase, respectively, in the cytotrophoblast per villous area. Finally, a transcriptomic analysis identified pathways associated with hypoxia, inflammation, and reduced cell proliferation in PE-MVM placentas and further subclassified this group into extravillous trophoblast-high and extravillous trophoblast-low PE, confirmed using an immunohistochemical analysis of trophoblast lineage-specific markers. Our findings suggest that within specific histopathologic patterns of placental injury, PE can be subclassified based on specific cellular and molecular defects, allowing the identification of pathways that may be targeted for diagnostic and therapeutic purposes.

Placental transcriptomic signatures of spontaneous preterm birth

BACKGROUND

Spontaneous preterm birth accounts for most preterm births and leads to significant morbidity in the newborn and childhood period. This subtype of preterm birth represents an increasing proportion of all preterm births when compared with medically indicated preterm birth, yet it is understudied in omics analyses. The placenta is a key regulator of fetal and newborn health, and the placental transcriptome can provide insight into pathologic changes that lead to spontaneous preterm birth.

OBJECTIVE

This analysis aimed to identify genes for which placental expression was associated with spontaneous preterm birth (including early preterm and late preterm birth).

STUDY DESIGN

The ECHO PATHWAYS consortium extracted RNA from placental samples collected from the Conditions Affecting Neurocognitive Development and Learning in Early Childhood and the Global Alliance to Prevent Prematurity and Stillbirth studies. Placental transcriptomic data were obtained by RNA sequencing. Linear models were fit to estimate differences in placental gene expression between term birth and spontaneous preterm birth (including gestational age subgroups defined by the American College of Obstetricians and Gynecologists). Models were adjusted for numerous confounding variables, including labor status, cohort, and RNA sequencing batch. This analysis excluded patients with induced labor, chorioamnionitis, multifetal gestations, or medical indications for preterm birth. Our combined cohort contained gene expression data for 14,023 genes in 48 preterm and 540 term samples. Genes and pathways were considered statistically significantly different at false discovery rate-adjusted P value of <.05.

RESULTS

In total, we identified 1728 genes for which placental expression was associated with spontaneous preterm birth with more differences in expression in early preterm samples than late preterm samples when compared with full-term samples. Of those, 9 genes were significantly decreased in both early and late spontaneous preterm birth, and the strongest associations involved placental expression of IL1B, ALPL, and CRLF1. In early and late preterm samples, we observed decreased expression of genes involved in immune signaling, signal transduction, and endocrine function.

CONCLUSION

This study provides a comprehensive assessment of the differences in the placental transcriptome associated with spontaneous preterm birth with robust adjustment for confounding. Results of this study are in alignment with the known etiology of spontaneous preterm birth, because we identified multiple genes and pathways for which the placental and chorioamniotic membrane expression was previously associated with prematurity, including IL1B. We identified decreased expression in key signaling pathways that are essential for placental growth and function, which may be related to the etiology of spontaneous preterm birth. We identified increased expression of genes within metabolic pathways associated exclusively with early preterm birth. These signaling and metabolic pathways may provide clinically targetable pathways and biomarkers. The findings presented here can be used to understand underlying pathologic changes in premature placentas, which can inform and improve clinical obstetrics practice.

Toward a new taxonomy of obstetrical disease: improved performance of maternal blood biomarkers for the great obstetrical syndromes when classified according to placental pathology

BACKGROUND

The major challenge for obstetrics is the prediction and prevention of the great obstetrical syndromes. We propose that defining obstetrical diseases by the combination of clinical presentation and disease mechanisms as inferred by placental pathology will aid in the discovery of biomarkers and add specificity to those already known.

OBJECTIVE

To describe the longitudinal profile of placental growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1), and the PlGF/sFlt-1 ratio throughout gestation, and to determine whether the association between abnormal biomarker profiles and obstetrical syndromes is strengthened by information derived from placental examination, eg, the presence or absence of placental lesions of maternal vascular malperfusion.

STUDY DESIGN

This retrospective case cohort study was based on a parent cohort of 4006 pregnant women enrolled prospectively. The case cohort of 1499 pregnant women included 1000 randomly selected patients from the parent cohort and all additional patients with obstetrical syndromes from the parent cohort. Pregnant women were classified into six groups: 1) term delivery without pregnancy complications (n=540; control); 2) preterm labor and delivery (n=203); 3) preterm premature rupture of the membranes (n=112); 4) preeclampsia (n=230); 5) small-for-gestational-age neonate (n=334); and 6) other pregnancy complications (n=182). Maternal plasma concentrations of PlGF and sFlt-1 were determined by enzyme-linked immunosorbent assays in 7560 longitudinal samples. Placental pathologists, masked to clinical outcomes, diagnosed the presence or absence of placental lesions of maternal vascular malperfusion. Comparisons between mean biomarker concentrations in cases and controls were performed by utilizing longitudinal generalized additive models. Comparisons were made between controls and each obstetrical syndrome with and without subclassifying cases according to the presence or absence of placental lesions of maternal vascular malperfusion.

RESULTS

1) When obstetrical syndromes are classified based on the presence or absence of placental lesions of maternal vascular malperfusion, significant differences in the mean plasma concentrations of PlGF, sFlt-1, and the PlGF/sFlt-1 ratio between cases and controls emerge earlier in gestation; 2) the strength of association between an abnormal PlGF/sFlt-1 ratio and the occurrence of obstetrical syndromes increases when placental lesions of maternal vascular malperfusion are present (adjusted odds ratio [aOR], 13.6 vs 6.7 for preeclampsia; aOR, 8.1 vs 4.4 for small-for-gestational-age neonates; aOR, 5.5 vs 2.1 for preterm premature rupture of the membranes; and aOR, 3.3 vs 2.1 for preterm labor (all P<0.05); and 3) the PlGF/sFlt-1 ratio at 28 to 32 weeks of gestation is abnormal in patients who subsequently delivered due to preterm labor with intact membranes and in those with preterm premature rupture of the membranes if both groups have placental lesions of maternal vascular malperfusion. Such association is not significant in patients with these obstetrical syndromes who do not have placental lesions.

CONCLUSION

Classification of obstetrical syndromes according to the presence or absence of placental lesions of maternal vascular malperfusion allows biomarkers to be informative earlier in gestation and enhances the strength of association between biomarkers and clinical outcomes. We propose that a new taxonomy of obstetrical disorders informed by placental pathology will facilitate the discovery and implementation of biomarkers as well as the prediction and prevention of such disorders.

The role of the placenta in spontaneous preterm labor and delivery with intact membranes

OBJECTIVES

To determine whether placental vascular pathology and impaired placental exchange due to maturational defects are involved in the etiology of spontaneous preterm labor and delivery in cases without histologic acute chorioamnionitis.

METHODS

This was a retrospective, observational study. Cases included pregnancies that resulted in spontaneous preterm labor and delivery (<37 weeks), whereas uncomplicated pregnancies that delivered fetuses at term (≥37-42 weeks of gestation) were selected as controls. Placental histological diagnoses were classified into three groups: lesions of maternal vascular malperfusion, lesions of fetal vascular malperfusion, and placental microvasculopathy, and the frequency of each type of lesion in cases and controls was compared. Moreover, we specifically searched for villous maturational abnormalities in cases and controls. Doppler velocimetry of the umbilical and uterine arteries were performed in a subset of patients.

RESULTS

There were 184 cases and 2471 controls, of which 95 and 1178 had Doppler studies, respectively. The frequency of lesions of maternal vascular malperfusion was greater in the placentas of patients with preterm labor than in the control group [14.1% (26/184) vs. 8.8% (217/2471) (p=0.023)]. Disorders of villous maturation were more frequent in the group with preterm labor than in the control group: 41.1% (39/95) [delayed villous maturation in 31.6% (30/95) vs. 2.5% (13/519) in controls and accelerated villous maturation in 9.5% (9/95) vs. none in controls].

CONCLUSIONS

Maturational defects of placental villi were associated with approximately 41% of cases of unexplained spontaneous preterm labor and delivery without acute inflammatory lesions of the placenta and with delivery of appropriate-for-gestational-age fetuses.

The Placental Epigenome as a Molecular Link Between Prenatal Exposures and Fetal Health Outcomes Through the DOHaD Hypothesis

Purpose of Review

The developmental origins of health and disease (DOHaD) hypothesis posits that the perinatal environment can impact fetal and later life health. The placenta is uniquely situated to assess prenatal exposures in the context of DOHaD because it is an essential ephemeral fetal organ that manages the transport of oxygen, nutrients, waste, and endocrine signals between the mother and fetus. The purpose of this review is to summarize recent studies that evaluated the DOHaD hypothesis in human placentas using epigenomics, including DNA methylation and transcriptomic studies of mRNA, lncRNA, and microRNAs.

Recent Findings

Between 2016 and 2021, 28 articles evaluated associations between prenatal exposures and placental epigenomics across broad exposure categories including maternal smoking, psychosocial stressors, chemicals, air pollution, and metals. Sixteen of these studies connected exposures to health outcome such as birth weight, fetal growth, or infant neurobehavior through mediation analysis, identification of shared associations between exposure and outcome, or network analysis. These aspects of infant and childhood health serve as a foundation for future studies that aim to use placental epigenetics to understand relationships between the prenatal environment and perinatal complications (such as preterm birth or fetal growth restriction) or later life childhood health.

Summary

Placental DNA methylation and RNA expression have been linked to numerous prenatal exposures, such as PM2.5 air pollution, metals, and maternal smoking, as well as infant and childhood health outcomes, including fetal growth and birth weight. Placental epigenomics provides a unique opportunity to expand the DOHaD premise, particularly if research applies novel methodologies such as multi-omics analysis, sequencing of non-coding RNAs, mixtures analysis, and assessment of health outcomes beyond early childhood.

Sexually dimorphic patterns in maternal circulating microRNAs in pregnancies complicated by fetal growth restriction

Background

Current methods fail to accurately predict women at greatest risk of developing fetal growth restriction (FGR) or related adverse outcomes, including stillbirth. Sexual dimorphism in these adverse pregnancy outcomes is well documented as are sex-specific differences in gene and protein expression in the placenta. Circulating maternal serum microRNAs (miRNAs) offer potential as biomarkers that may also be informative of underlying pathology. We hypothesised that FGR would be associated with an altered miRNA profile and would differ depending on fetal sex.

Methods

miRNA expression profiles were assessed in maternal serum (> 36 weeks’ gestation) from women delivering a severely FGR infant (defined as an individualised birthweight centile (IBC) < 3rd) and matched control participants (AGA; IBC = 20–80th), using miRNA arrays. qPCR was performed using specific miRNA primers in an expanded cohort of patients with IBC < 5th (n = 15 males, n = 16 females/group). Maternal serum human placental lactogen (hPL) was used as a proxy to determine if serum miRNAs were related to placental dysfunction. In silico analyses were performed to predict the potential functions of altered miRNAs.

Results

Initial analyses revealed 11 miRNAs were altered in maternal serum from FGR pregnancies. In silico analyses revealed all 11 altered miRNAs were located in a network of genes that regulate placental function. Subsequent analysis demonstrated four miRNAs showed sexually dimorphic patterns. miR-28-5p was reduced in FGR pregnancies (p < 0.01) only when there was a female offspring and miR-301a-3p was only reduced in FGR pregnancies with a male fetus (p < 0.05). miR-454-3p was decreased in FGR pregnancies (p < 0.05) regardless of fetal sex but was only positively correlated to hPL when the fetus was female. Conversely, miR-29c-3p was correlated to maternal hPL only when the fetus was male. Target genes for sexually dimorphic miRNAs reveal potential functional roles in the placenta including angiogenesis, placental growth, nutrient transport and apoptosis.

Conclusions

These studies have identified sexually dimorphic patterns for miRNAs in maternal serum in FGR. These miRNAs may have potential as non-invasive biomarkers for FGR and associated placental dysfunction. Further studies to determine if these miRNAs have potential functional roles in the placenta may provide greater understanding of the pathogenesis of placental dysfunction and the differing susceptibility of male and female fetuses to adverse in utero conditions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13293-021-00405-z.

Detection and treatment of pregnancies at high risk of fetal growth restriction (FGR) and stillbirth remains a major obstetric challenge; circulating maternal serum microRNAs (miRNAs) offer potential as novel biomarkers.

Unbiased analysis of serum miRNAs in women in late pregnancy identified a specific profile of circulating miRNAs in women with a growth-restricted infant.

Some altered miRNAs (miR-28-5p, miR-301a-3p) showed sexually dimorphic expression in FGR pregnancies and others a fetal-sex dependent association to a hormonal marker of placental dysfunction (miR-454-3p, miR-29c-3p).

miR-301a-3p and miR-28-5p could potentially be used to predict FGR specifically in pregnancies with a male or female baby, respectively, however larger cohort studies are required.

Further investigations of these miRNAs and their relationship to placental dysfunction will lead to a better understanding of the pathophysiology of FGR and why there is differing susceptibility of male and female fetuses to FGR and stillbirth.

Childhood neurodevelopmental disorders and maternal hypertensive disorder of pregnancy

AIM

To examine the association of maternal chronic hypertension and pregnancy-induced hypertension (PIH)/preeclampsia with childhood neurodevelopmental disorders (NDDs) in a large-scale population-based cohort.

METHOD

We conducted a linked Taiwan National Health Insurance Research Database cohort study of children born between 2004 and 2008 (n=877 233). Diagnoses of autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), developmental delay, intellectual disability, cerebral palsy (CP), and epilepsy/infantile spasms were identified from birth to the end of 2015. Cox proportional hazards models were fitted with adjustment for potential confounders to estimate the effect of maternal hypertensive disorder of pregnancy on childhood outcomes.

RESULTS

Compared with the offspring of unexposed mothers, offspring of mothers with chronic hypertension or PIH/preeclampsia exhibited increased risk of developing a wide spectrum of NDDs. Chronic hypertension was associated with increased risks of ADHD (hazard ratio 1.22, 95% confidence interval [CI] 1.13-1.​31), developmental delay (1.29, 1.21-1.38), intellectual disability (1.67, 1.43-1.95), CP (1.45, 1.14-1.85), and epilepsy/infantile spasms (1.31, 1.10-1.56) in the offspring, whereas PIH/preeclampsia was associated with increased risks of ASD (1.27, 1.12-1.43), ADHD (1.23, 1.17-1.29), developmental delay (1.29, 1.24-1.35), intellectual disability (1.53, 1.37-1.71), CP (1.44, 1.22-1.70), and epilepsy/infantile spasms (1.36, 1.22-1.52) in the offspring after adjustment for potential confounders. The co-occurrence of maternal diabetes, preterm deliveries, or fetal growth restriction further increased the risk.

INTERPRETATION

Chronic hypertension or PIH/preeclampsia seems to be sufficient to increase the risk of childhood NDDs. What this paper adds Children exposed to maternal hypertensive disorders have a higher cumulative incidence of neurodevelopmental disorders (NDDs) than unexposed children. Chronic hypertension or pregnancy-induced hypertension/preeclampsia seems to be sufficient to increase the risk of childhood NDDs. Co-occurrence of maternal diabetes, preterm deliveries, or fetal growth restriction further increases the risk.

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.

Urothelial Cancer Associated 1 (UCA1) and miR-193 Are Two Non-coding RNAs Involved in Trophoblast Fusion and Placental Diseases

A bioinformatics screen for non-coding genes was performed from microarrays analyzing on the one hand trophoblast fusion in the BeWo cell model, and on the other hand, placental diseases (preeclampsia and Intra-Uterine Growth Restriction). Intersecting the deregulated genes allowed to identify two miRNA (mir193b and miR365a) and one long non-coding RNA (UCA1) that are pivotal for trophoblast fusion, and deregulated in placental diseases. We show that miR-193b is a hub for the down-regulation of 135 cell targets mainly involved in cell cycle progression and energy usage/nutrient transport. UCA1 was explored by siRNA knock-down in the BeWo cell model. We show that its down-regulation is associated with the deregulation of important trophoblast physiology genes, involved in differentiation, proliferation, oxidative stress, vacuolization, membrane repair and endocrine production. Overall, UCA1 knockdown leads to an incomplete gene expression profile modification of trophoblast cells when they are induced to fuse into syncytiotrophoblast. Then we performed the same type of analysis in cells overexpressing one of the two major isoforms of the STOX1 transcription factor, STOX1A and STOX1B (associated previously to impaired trophoblast fusion). We could show that when STOX1B is abundant, the effects of UCA1 down-regulation on forskolin response are alleviated.

Physiological and pathological functions of sphingolipids in pregnancy

Signaling by the bioactive sphingolipid, sphingosine 1-phosphate (S1P), and its precursors are emerging areas in pregnancy research. S1P and ceramide levels increase towards end of gestation, suggesting a physiological role in parturition. However, high levels of circulating S1P and ceramide are correlated with pregnancy disorders such as preeclampsia, gestational diabetes mellitus and intrauterine growth restriction. Expression of placental and decidual enzymes that metabolize S1P and S1P receptors are also dysregulated during pregnancy complications. In this review, we provide an in-depth examination of the signaling mechanism of S1P and ceramide in various reproductive tissues during gestation. These factors determine implantation and early pregnancy success by modulating corpus luteum function from progesterone production to luteolysis through to apoptosis. We also highlight the role of S1P through receptor signaling in inducing decidualization and angiogenesis in the decidua, as well as regulating extravillous trophoblast migration to anchor the placenta into the uterine wall. Recent advances on the role of the S1P:ceramide rheostat in controlling the fate of villous trophoblasts and the role of S1P as a negative regulator of trophoblast syncytialization to a multinucleated placental barrier are discussed. This review also explores the role of S1P in anti-inflammatory and pro-inflammatory signaling, its role as a vasoconstrictor, and the effects of S1P metabolizing enzymes and receptors in pregnancy.

Integrated Analysis of Key Genes and Pathways Involved in Fetal Growth Restriction and Their Associations With the Dysregulation of the Maternal Immune System

Fetal growth restriction (FGR) is a common pregnancy complication and a risk factor for infant death. Most patients with FGR have preeclampsia, gestational diabetes mellitus, or other etiologies, making it difficult to determine the specific molecular mechanisms underlying FGR. In this study, an integrated analysis was performed using gene expression profiles obtained from Gene Expression Omnibus. Differentially expressed genes (DEGs) between healthy and FGR groups were screened and evaluated by functional enrichment and network analyses. In total, 80 common DEGs (FDR < 0.05) and 17 significant DEGs (FDR < 0.005) were screened. These genes were enriched for functions in immune system dysregulation in the placenta based on Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses. Among hub genes identified as candidates for FGR and fetal reprogramming, LEP, GBP5, HLA–DQA1, and CTGF were checked by quantitative polymerase chain reaction, immunohistochemistry, and western blot assays in placental tissues. Immune imbalance could cause hypoxia environment in placenta tissues, thus regulating the fetal-reprogramming. A significant association between CTGF and HIF-1α levels was confirmed in placenta tissues and HTR8 cells under hypoxia. Our results suggest that an immune imbalance in the placenta causes FGR without other complications. We provide the first evidence for roles of CTGF in FGR and show that CTGF may function via HIF-1α-related pathways. Our findings elucidate the pathogenesis of FGR and provide new therapeutic targets.

Monochorionic twins with selective fetal growth restriction: insight from placental whole-transcriptome analysis

BACKGROUND

The underlying pathomechanism in placenta-related selective fetal growth restriction in monochorionic diamniotic twin pregnancy is not known.

OBJECTIVE

This study aimed to investigate any differences in placental transcriptomic profile between the selectively growth-restricted twins and the normally grown cotwins in monochorionic diamniotic twin pregnancies.

STUDY DESIGN

This was a prospective study of monochorionic diamniotic twin pregnancies complicated by selective fetal growth restriction. Placental biopsy specimens were obtained from the subjects in the delivery suite. The placental transcriptome of the selectively growth-restricted twin was compared with that of the normally grown cotwin. This study was divided into 2 stages: (1) gene discovery phase in which placental tissues from 5 monochorionic diamniotic twin pregnancies complicated by selective fetal growth restriction plus 2 control twin pregnancies underwent transcriptome profiling, and transcriptome profiling was carried out using whole-genome RNA sequencing; and (2) validation phase in which placental tissues from 13 monochorionic diamniotic twin pregnancies with selective fetal growth restriction underwent RNA and protein validation. RNA and protein expression levels of candidate genes were determined using quantitative real-time polymerase chain reaction and immunohistochemistry staining.

RESULTS

A total of 1429 transcripts were differentially expressed in the placentae of selectively growth-restricted twin pairs, where 610 were up-regulated and 819 were down-regulated. Endoplasmic reticulum lectin and mannose 6-phosphate receptor were consistently differentially up-regulated in all placentae of selectively growth-restricted twins. Quantitative real-time polymerase chain reaction and immunohistochemistry staining were used to validate the results (P<.05).

CONCLUSION

The expression of endoplasmic reticulum lectin and mannose 6-phosphate receptor, which are important for angiogenesis and fetal growth, was significantly increased in the placentae of selectively growth-restricted twin of a monochorionic twin pair.

The first-trimester serum decorin levels as a potential predictor of preeclampsia

Background Preeclampsia (PE) is a multisystem disease and is still among the leading causes of maternal and neonatal morbidity and mortality. Inadequate trophoblast invasion plays a key role in the PE pathogenesis. The proliferation, migration, and invasion of extravillous trophoblasts (EVTs) is primarily controlled by the decidua-derived transforming growth factor beta (TGF-β) and decorin. In this study, we aimed to investigate the clinical utility of serum decorin levels measured in the 11th to 14th gestational weeks to predict preeclampsia during the following weeks of gestation. Materials and Methods A total of 600 pregnant women, whose age and gestational age ranged from 18 to 40 years and 11 to 14 weeks, were included. Venous blood samples were obtained and stored at -80 °C. Subsequently, the patients who developed preeclampsia and healthy controls with a similar body mass index were identified and their first-trimester blood samples were analyzed for serum decorin levels. Results The mean serum decorin level was 8.76 ± 6.88 ng/mL for the PE group while 9.75 ± 9.82 ng/mL for the control group. No statistically significant difference was found between the two groups (p=0.838). Conclusion We observed that the serum decorin levels during the 11th to 14th weeks of gestation showed no predictive value for preeclampsia in pregnant women. However, more accurate conclusions about the clinical utility of decorin as a biomarker of preeclampsia would require further studies with larger samples including more patients with EOS-PE.

Tracking placental development in health and disease

Pre-eclampsia and fetal growth restriction arise from disorders of placental development and have some shared mechanistic features. Initiation is often rooted in the maldevelopment of a maternal-placental blood supply capable of providing for the growth requirements of the fetus in later pregnancy, without exerting undue stress on maternal body systems. Here, we review normal development of a placental bed with a safe and adequate blood supply and a villous placenta-blood interface from which nutrients and oxygen can be extracted for the growing fetus. We consider disease mechanisms that are intrinsic to the maternal environment, the placenta or the interaction between the two. Systemic signalling from the endocrine placenta targets the maternal endothelium and multiple organs to adjust metabolism for an optimal pregnancy and later lactation. This signalling capacity is skewed when placental damage occurs and can deliver a dangerous pathogenic stimulus. We discuss the placental secretome including glycoproteins, microRNAs and extracellular vesicles as potential biomarkers of disease. Angiomodulatory mediators, currently the only effective biomarkers, are discussed alongside non-invasive imaging approaches to the prediction of disease risk. Identifying the signs of impending pathology early enough to intervene and ameliorate disease in later pregnancy remains a complex and challenging objective.

Cluster Analysis: A New Approach for Identification of Underlying Risk Factors and Demographic Features of First Trimester Pregnancy Women

Thyroid pathology is reported internationally in 5-10% of all pregnancies. The overall aim of this research was to determine the prevalence of hypothyroidism and risk factors during the first trimester screening in a Mexican patients sample. We included the records of 306 patients who attended a prenatal control consultation between January 2016 and December 2017 at the Women's Institute in Monterrey, Mexico. The studied sample had homogeneous demographic characteristics in terms of age, weight, height, BMI (body mass index) and number of pregnancies. The presence of at least one of the risk factors for thyroid disease was observed in 39.2% of the sample. Two and three clusters were identified, in which patients varied considerably among risk factors, symptoms and pregnancy complications. Compared to Cluster 0, one or more symptoms or signs of hypothyroidism occurred, while Cluster 1 was characterized by healthier patients. When three clusters were used, Cluster 2 had a higher TSH (thyroid stimulating hormone) value and pregnancy complications. There were no significant differences in perinatal variables. In addition, high TSH levels in first trimester pregnancy are characterized by pregnancy complications and decreased newborn weight. Our findings underline the high degree of disease heterogeneity with existing pregnant hypothyroid patients and the need to improve the phenotyping of the syndrome in the Mexican population.

Placental Microarray Profiling Reveals Common mRNA and lncRNA Expression Patterns in Preeclampsia and Intrauterine Growth Restriction

Preeclampsia (PE) and Intrauterine Growth Restriction (IUGR) are major contributors to perinatal morbidity and mortality. These pregnancy disorders are associated with placental dysfunction and share similar pathophysiological features. The aim of this study was to compare the placental gene expression profiles including mRNA and lncRNAs from pregnant women from four study groups: PE, IUGR, PE-IUGR, and normal pregnancy (NP). Gene expression microarray analysis was performed on placental tissue obtained at delivery and results were validated using RTq-PCR. Differential gene expression analysis revealed that the largest transcript variation was observed in the IUGR samples compared to NP (n = 461; 314 mRNAs: 252 up-regulated and 62 down-regulated; 133 lncRNAs: 36 up-regulated and 98 down-regulated). We also detected a group of differentially expressed transcripts shared between the PE and IUGR samples compared to NP (n = 39), including 9 lncRNAs with a high correlation degree (p < 0.05). Functional enrichment of these shared transcripts showed that cytokine signaling pathways, protein modification, and regulation of JAK-STAT cascade are over-represented in both placental ischemic diseases. These findings contribute to the molecular characterization of placental ischemia showing common epigenetic regulation implicated in the pathophysiology of PE and IUGR.

Trophoblast lineage-specific differentiation and associated alterations in preeclampsia and fetal growth restriction

The human placenta is a poorly-understood organ, but one that is critical for proper development and growth of the fetus in-utero. The epithelial cell type that contributes to primary placental functions is called "trophoblast," including two main subtypes, villous and extravillous trophoblast. Cytotrophoblast and syncytiotrophoblast comprise the villous compartment and contribute to gas and nutrient exchange, while extravillous trophoblast invade and remodel the uterine wall and vessels, in order to supply maternal blood to the growing fetus. Abnormal differentiation of trophoblast contributes to placental dysfunction and is associated with complications of pregnancy, including preeclampsia (PE) and fetal growth restriction (FGR). This review describes what is known about the cellular organization of the placenta during both normal development and in the setting of PE/FGR. It also explains known trophoblast lineage-specific markers and pathways regulating their differentiation, and how these are altered in the setting of PE/FGR, focusing on studies which have used human placental tissues. Finally, it also highlights remaining questions and needed resources to advance this field.

Recurrent Placental Transcriptional Profile With a Different Histological and Clinical Presentation: A Case Report

Statistically, patients with severe pregnancy complications are at risk of recurrent complications, but it is less understood if patients present with similar or different placental pathologies in subsequent pregnancies. In this case report, we describe 2 consecutive adverse pregnancies in the same woman 4 years apart. The first pregnancy was diagnosed as early-onset preeclampsia and hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome, with placental maternal vascular malperfusion features, such as syncytial knots and accelerated villous maturity. In contrast, the second pregnancy was associated with normotensive fetal growth restriction and placental "immunological" lesions, such as massive perivillous fibrin deposition and chronic intervillositis. However, based on the expression of FLT1, LIMCH1, and TAP1 by quantitative polymerase chain reaction, the placentas from both pregnancies were found to exhibit an "immunological" transcriptional signature. This suggests that this small panel of gene expression markers may be able to predict the future reoccurrence of an immunological placental pathology despite no histological evidence within the first pregnancy. These results call for more studies looking at paired pregnancies of individuals with recurrent obstetric complications and confirm the importance of assessing matched transcriptional and histopathological placental information.

Pro-inflammatory immune cell gene expression during the third trimester of pregnancy is associated with shorter gestational length and lower birthweight

PROBLEM

Altered maternal immune function predicts risk for shorter gestation and low birthweight. Few studies examine associations between prenatal immune cell gene expression and gestational length or birthweight. No studies examine which cell types drive associations. The purpose of this study is to explore associations between peripheral blood immune cell gene expression and gestational length and birthweight, using transcript origin analysis.

METHOD OF STUDY

Eighty-nine women were drawn from the Community Child Health Network cohort. Third trimester maternal dried blood spots were used for genome-wide transcriptional (mRNA) profiling. Gestational length and birthweight were obtained from medical charts. Covariates were age, race/ethnicity, pre-pregnancy body mass index, smoking, gestational age at blood sampling, and pregnancy infections. Associations between gene expression profiles and gestational length and birthweight were tested using general linear models. The Transcription Element Listening System (TELiS) bioinformatics analysis quantified upstream transcription factor activity. Transcript origin analysis identified leukocyte subsets mediating observed effects.

RESULTS

Shorter gestation was predicted by increased NF-kB (TFBM ratio = -0.582 ± 0.172, P < .001) and monocyte activity (diagnosticity score = 0.172 ± 0.054, P < .001). Longer gestation was associated with increased dendritic cell activity (diagnosticity score = 0.194 ± 0.039, P < .001). Increased AP-1 activity predicted lower birthweight (TFBM ratio = -0.240 ± 0.111, P = .031). Dendritic cells and CD4+ and CD8+ T cells predicted birthweight-related gene expression differences (diagnosticity score P's < 0.021).

CONCLUSION

Higher third trimester pro-inflammatory gene expression predicted shorter gestation and lower birthweight. Variations in monocyte and dendritic cell biology contributed to both effects, and T-cell biology contributed to higher birthweight. These analyses clarify the role of myeloid/lymphoid lineage immune regulation in pregnancy outcomes.

Different morphological and gene expression profile in placentas of the same sickle cell anemia patient in pregnancies of opposite outcomes

IMPACT STATEMENT

Environmentally induced changes in placental morphological and molecular phenotypes may provide relevant insight towards pathophysiology of diseases. The rare opportunity to evaluate the same patient, with sickle cell anemia (SCA), in two different pregnancies, of opposite outcomes (one early onset severe preeclampsia (PE) and the other mostly non-complicated) can prove such concept. In addition, the comparison to other conditions of known placental and vascular/inflammatory involvement strengthens such findings. Our results suggest that the clinical association between SCA and PE can be supported by common pathophysiological mechanisms, but that pathways involving response to copper and triglyceride metabolism may be important drivers of the pathophysiology of PE. Future studies using in a larger number of samples should confirm these findings and explore pathways involved in the pathophysiology of PE and its relationship with SCA.