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.

Clinical phenotyping of term and preterm labor is imprecise, and disagreement persists on categorization relative to underlying pathobiology, which remains poorly understood. We performed RNA sequencing (RNA-seq) of 31 specimens of human uterine myometrium from 10 term and 21 preterm cesarean deliveries with rich clinical context information. A molecular signature of 4814 transcripts stratified myometrial samples into quiescent (Q) and nonquiescent (NQ) phenotypes, independent of gestational age and incision site. Similar stratifications were achieved using expressed genes in Ca ²⁺ signaling and TGF-β pathways. For maximal parsimony, we evaluated the expression of just 2 Ca ²⁺ transporter genes, ATP2B4 (encoding PMCA4) and ATP2A2 (coding for SERCA2), and we found that their ratio reliably distinguished NQ and Q specimens in the current study, and also in 2 publicly available RNA-seq data sets (GSE50599 and GSE80172), with an overall AUC of 0.94. Cross-validation of the ATP2B4 / ATP2A2 ratio by quantitative PCR in an expanded cohort (by 11 additional specimens) achieved complete separation (AUC of 1.00) of NQ versus Q specimens. While providing additional insight into the associations between clinical features of term and preterm labor and myometrial gene expression, our study also offers a practical algorithm for unbiased classification of myometrial biopsies by their overall contractile program.

The phenotype of human placental extravillous trophoblast (EVT) at the end of pregnancy reflects both differentiation from villous cytotrophoblast (CTB) and later gestational changes, including loss of proliferative and invasive capacity. Invasion abnormalities are central to major obstetric pathologies, including placenta accreta spectrum, early onset preeclampsia, and fetal growth restriction. Characterization of the normal differentiation processes is, thus, essential for the analysis of these pathologies. Our gene expression analysis, employing purified human CTB and EVT cells, demonstrates a mechanism similar to the epithelial–mesenchymal transition (EMT), which underlies CTB–EVT differentiation. In parallel, DNA methylation profiling shows that CTB cells, already hypomethylated relative to non-trophoblast cell lineages, show further genome-wide hypomethylation in the transition to EVT. A small subgroup of genes undergoes gains of methylation (GOM), associated with differential gene expression (DE). Prominent in this GOM-DE group are genes involved in epithelial–mesenchymal plasticity (EMP). An exemplar is the transcription factor RUNX1, for which we demonstrate a functional role in regulating the migratory and invasive capacities of trophoblast cells. This analysis highlights epigenetically regulated genes acting to underpin the epithelial–mesenchymal plasticity characteristic of human trophoblast differentiation. Identification of these elements provides important information for the obstetric disorders in which these processes are dysregulated.

BACKGROUND: Multifetal pregnancies have increased preeclampsia risk, but the underlying pathogenesis may differ from that of singletons. It remains unclear whether twin placentas show molecular signs of preeclampsia synchronously. METHODS: We performed RNA sequencing on 32 individual placental samples from twin gestations grouped by preeclampsia status: 24 dichorionic twin (DT) and 8 monochorionic twin gestations. Ten singleton placentas from preeclamptic pregnancies were also analyzed. A benchmark data set (GSE203507, GSE114691, and GSE1482410) and a test data set (GSE190973) comprised 71 early onset preeclampsia and 69 control singleton placentas. Differential abundance analysis was conducted, and machine learning was used to derive a novel 98-transcript classification signature (accuracy >0.97 in benchmark and test data sets). RESULTS: Across 7 groups, 2946 transcripts were differentially modulated (likelihood-ratio test; false discovery rate <0.05). Placental signature scoring distinguished normotensive from early onset preeclampsia in GSE203507 singletons ( P <0.0001) although normotensive DTs did not differ from DTs with preeclampsia (Kruskal-Wallis/Dunn). Notably, some twin placentas without clinical preeclampsia exhibited preeclampsia-like profiles. Linear mixed-effects regression, which accounted for intertwin correlation structure, revealed increasing signature scores across singleton and DT groups (all P <0.01): normotensive singletons<normotensive DT<DT with preeclampsia<singletons with preeclampsia. Functional analysis in twins showed preeclampsia-like dysregulation but with pronounced variability. Intertwin divergence was more prominent in DT than in monochorionic twin samples, regardless of clinical diagnosis. CONCLUSIONS: These findings highlight the complexity of preeclampsia pathology in twins. In DT pregnancies complicated by preeclampsia, placental involvement may be asymmetrical, suggesting that disease may arise from a single affected placenta; however, these results require replication.