Placenta

The placenta undergoes morphological and functional adaptions to adverse exposures during pregnancy. The effects of suboptimal maternal body mass index (BMI), preterm birth, and infection on placental histopathological phenotypes remain unclear, despite the association between these conditions and poor offspring outcomes. We hypothesized that suboptimal maternal prepregnancy BMI and preterm birth (with and without infection) would associate with altered placental maturity and morphometry, and that altered placental maturity would associate with poor birth outcomes. Clinical data and human placentae were collected from 96 pregnancies where mothers were underweight, normal weight, overweight, or obese, without other major complications. Placental histopathological characteristics were scored with an anatomical pathologist. Associations between maternal BMI, placental pathology (immaturity and hypermaturity), placental morphometry, and infant outcomes were investigated at term and preterm, with and without infection. Fetal vascular endothelium volumetric proportion was decreased, whereas syncytial knot volumetric proportion was increased, in placentae from preterm pregnancies with chorioamnionitis compared to term placentae. At term and preterm, pregnancies with overweight and obesity had a high percentage increase in proportion of immature placentae compared to normal weight. Placental maturity did not associate with infant birth outcomes. We observed placental hypermaturity and altered placental morphometry among preterm pregnancies with chorioamnionitis, suggestive of altered placental development, which may inform about pregnancies susceptible to preterm birth and infection. Our data increase our understanding of how common metabolic exposures and preterm birth, in the absence of other comorbidities or perinatal events, potentially contribute to poor pregnancy outcomes and the programming of offspring development.

The relationship between maternal monocytes and the placenta is crucial for successful pregnancy. As existing reviews focus on the research on decidual macrophages or Hofbauer cells (fetal macrophages), we conducted a scoping review of literature studies examining the relationship between circulating maternal monocytes and the villous trophoblast. The goal of this review was to outline existing research within the field, disseminate further information, and to identify current knowledge gaps within the field. We searched the PubMed (MEDLINE) database for relevant articles published since 1995 that studied human tissue or cell lines. Our results showed clear trends in the type of monocyte and placental primary tissues and cell lines used. Further classification of these articles revealed four primary categories of monocyte-trophoblast interaction research: monocyte presence or recruitment to the placenta, monocyte phenotype in the intervillous space, monocyte-placental adhesion, and monocyte interaction with syncytiotrophoblast-derived extracellular vesicles (STBEVs). Although limited in scope and number, these studies implicate the importance of monocyte-trophoblast interactions, and their significant roles in maternal disease.

Pre-existing and gestationally-developed diabetes mellitus have been linked with impaired metabolic function in placental villous trophoblast cells, that is thought to underlie the development of metabolic diseases early in the lives of the exposed offspring. Previous research using placental cell lines and ex vivo trophoblast preparations have highlighted hyperglycemia as an important independent regulator of placental function. However, it is poorly understood if hyperglycemia directly influences aspects of placental metabolic function, including nutrient storage and mitochondrial respiration, that have been found to be impaired in diabetic placentae. Therefore, the current study examined metabolic and mitochondrial function as well as nutrient storage in both undifferentiated cytotrophoblast and differentiated syncytiotrophoblast BeWo cells cultured under hyperglycemia conditions (25 mM glucose) for 72 hours to further characterize the direct impacts of placental hyperglycemic exposure. Hyperglycemic-exposed BeWo trophoblasts displayed increased triglyceride and glycogen nutrient stores. However, specific functional readouts of metabolic enzyme activity and mitochondrial oxidative respiratory activity were not altered. We speculated that increased glycogen content may reduce free glucose available for oxidation and subsequently protect trophoblast cells from mitochondrial damage during acute high glucose exposures. To further characterize the impacts of independent hyperglycemia, the current study subsequently utilized a multi-omics approach and evaluated the transcriptomic and metabolomic signatures of BeWo cytotrophoblasts. Hyperglycemic exposure was associated with an altered transcriptomic profile (e.g. increased expression of ACSL1 (+1.36 fold-change (FC), HSD11B2 (+1.35 FC), and RPS6KA5 (+1.32 FC)), and metabolome profile (e.g. increased levels lactate (+2.72 FC), malonate (+3.74 FC), and riboflavin (+3.68 FC)) in BeWo cytotrophoblasts that further highlighted trophoblast metabolic function is modulated independently by hyperglycemia. Overall, these results demonstrate that hyperglycemia is an important independent regulator of key areas of placental metabolic function and nutrient storage, and these data continue to expand our knowledge on the mechanisms governing the development of placental dysfunction.

Human placental tissues have variable rates of SARS-CoV-2 invasion resulting in consistently low rates of fetal transmission suggesting a unique physiologic blockade against SARS-CoV-2. Angiotensin-converting enzyme (ACE)-2, the main receptor for SARS-CoV-2, is expressed as cell surface and soluble forms regulated by a metalloprotease cleavage enzyme, ADAM17. ACE-2 is expressed in the human placenta, but the regulation of placental ACE-2 expression in relation to timing of maternal SARS-CoV-2 infection in pregnancy is not well understood. In this study, we evaluated ACE-2 expression, ADAM17 activity and serum ACE-2 abundance in a cohort of matched villous placental and maternal serum samples from Control pregnancies (SARS-CoV-2 negative, n=8) and pregnancies affected by symptomatic maternal SARS-CoV-2 infections in the 2nd trimester ("2ndTri COVID", n=8) and 3rd trimester ("3rdTri COVID", n=8). In 3rdTri COVID as compared to control and 2ndTri-COVID villous placental tissues ACE-2 mRNA expression was remarkably elevated, however, ACE-2 protein expression was significantly decreased with a parallel increase in ADAM17 activity. Soluble ACE-2 was also significantly increased in the maternal serum from 3rdTri COVID infections as compared to control and 2ndTri-COVID pregnancies. These data suggest that in acute maternal SARS-CoV-2 infections, decreased placental ACE-2 protein may be the result of ACE-2 shedding. Overall, this work highlights the importance of ACE-2 for ongoing studies on SARS-CoV-2 responses at the maternal-fetal interface.

PurposeTo investigate if maternal, fetal and placental vascular and/or molecular changes predict the risk for retinopathy of prematurity in preterm infants. MethodologyThe postnatal and antenatal data and placental histopathological changes; H&E staining of placental sections and molecular findings; gene expression analysis by qRT-PCR and protein expression by IHC at the maternal-fetal interface were collected from 20 placental samples and categorized into 3 groups: full-term (n=10), preterm without ROP (n=7) and preterm with ROP (n=6). ResultsThe correlation analysis indicated significant association of increased monocytes (p=0.042), fetal growth retardation (p=0.000), apnoeic spell (p=0.033), ventilation (p=0.009), length in hospital stay (p=0.001) and decreased RBC (p=0.02), Hb (p=0.048), PCV (p=0.010), gestational age (p=0.003), birth weight (p=0.000) with increased risk of ROP. Along with these factors, placental weight(p=0.001), diameter (p=0.019), Tenny-Parker changes (p=0.025), alternating area of small and short hyper mature villi (p=0.033) are also found to be significant determinants of the disease. Gene expression analysis revealed significant increase in hypoxia (HIF-1 gene expression; p=0.007) and non-significant increase in the pro-inflammatory marker IL-6. The protein expression also showed the significantly increased activation of complement pathway (CFH) and NF- KB at maternal-fetal interface. ConclusionsOur preliminary results support the changes in the maternal-fetal factors, placental histopathology and molecular alterations related to hypoxia, inflammation and complement activation at maternal-fetal interface in preterm with ROP placentas. These changes have the potential to predict the risk of the disease but the results are required to be further validated in larger cohort.

Roughly 10% of all pregnancies are affected by fetal growth restriction (FGR). The primary etiology of FGR is placental insufficiency: the placenta not providing the appropriate amount of nutrients and oxygen to the fetus. There is currently no treatment for FGR or placental insufficiency. Because of the placentas pivotal role in FGR and supplying nutrients to the fetus, it offers an excellent target for therapeutic intervention. Using a guinea pig maternal nutrient restriction model and a repeated placental nanoparticle-mediated IGF1 treatment, placental IGF1 signaling and nutrient transport pathways were characterized to understand changes with FGR and treatment. This study elucidates the signaling mechanisms in which repeated placental nanoparticle-mediated IGF1 treatment leads to correct fetal growth. Overall, this study resulted in sex-specific kinase signaling and nutrient transporter changes within the placenta in both FGR and treatment groups. Combined with our previous studies using this treatment, we demonstrate the basic molecular signaling of this treatment and recapitulate the plausibility of this therapy for future human translation.

BackgroundPreeclampsia (PE) is a multisystem pregnancy complication constituting a major cause of maternal and fetal morbidity and mortality. Factors pointing to a placental origin are the development of the pathology only during pregnancy, and its disappearance in the post-partum period. MethodsHere, we aim to identify new early predictive biomarkers based on a transcriptional signature of PE using RNAseq. Whole blood and serum samples were collected at the time of the first event of PE (V1) and same samples after remote delivery (30-60 postpartum days, V2). These two samples enabled investigation of PE markers found in V1 but absent in V2. To confirm that these candidates are associated with PE, an investigation of associated placental biopsy was also realized (J0). ResultsOur study identified a specific signature of PE including five Gene Ontology clusters including "angiogenesis and differentiation", "cell cycle", "cell adhesion", "inflammatory response" and "cellular metabolism". Interestingly, DUSP1 gene was found specifically modulated in PE. Pregnant women with PE have a higher concentration of DUSP1 in serum compared to healthy donors. Interesting, at a distance from childbirth (V2), DUSP1 finds a rate like the control group showing the predictive interest of DUSP1 as a promising predictive biomarker of PE. ConclusionsThe investigation of DUSP1 in a prospective study with a larger cohort, including the severity aspect of the disease, is necessary to confirm its value as a predictive biomarker in PE.

Placental immune responses to Human Immunodeficiency Virus (HIV) and Human Cytomegalovirus (CMV) vary across gestational stages and may influence postnatal outcomes. This study investigates the innate immunity of Hofbauer cells from placentae obtained at early/mid-gestation (18-21.6 weeks) and term (>37 weeks). RNA sequencing and cytokine profiling reveal that early/mid-gestation HCs exhibit heightened differential gene expression responses compared to term HCs, indicating a distinct transcriptional activity in early pregnancy. Significant overlap in gene expression profiles of early/mid-gestation cells in response to CMV and HIV suggest similar innate immune responses, while term cells exhibit distinct patterns, reflecting the temporal evolution of placental immunity. Integration with Human Protein Atlas database reveals more placental-specific differentially expressed genes in early/mid-gestation HCs exposed to HIV and CMV compared to term cells. Functional analysis reveals downregulation of pathways related to oxygen stress, estrogen response, and KRAS signaling pathway in early/mid-gestation HCs, with HIV uniquely upregulating reactive oxygen species and CMV uniquely disrupting WNT {beta}-Catenin signaling. In term HCs, CMV exposure upregulates antiviral interferon (IFN) signaling and inflammatory pathways. Co-expression analysis highlights distinct molecular pathway enrichments across gestation, particularly with upregulation of IFN signaling and disruption of lipid metabolism in term CMV-exposed HCs. Cytokine profiling shows enhanced expression of GM-CSF, IFN-{gamma}, and Th2-associated cytokines in early/mid-gestation HCs, indicating heightened immune responsiveness. These findings reveal the dynamic nature of placental immunity and underscore the need for targeted interventions to address unique immune and metabolic disruptions caused by viral infections at distinct stages of pregnancy to improve fetal and infant health outcomes.

Trophoblast invasion is essential for normal placentation, with failure resulting in a fetal growth restriction (FGR) phenotype. Utilizing a calorie-restricted mouse model, we report progressive epigenetic, molecular, and phenotypic placental changes throughout gestation. Following maternal caloric restriction initiated at E9, we observed a significant reduction in fetal and placental weights beginning at E12.5, with persistent growth restriction at E14.5, E16.5, and E17.5. Immunohistochemistry of the decidual invasion site at E17.5 demonstrated reduced 1) decidual depth, 2) trophoblast invasion distance, and 3) trophoblast quantity within the decidua. Preceding these phenotypic changes, RT-qPCR revealed downregulation of trophoblast invasion and angiogenesis genes, including MMP2, MMP9, EFNA1, Rac1, Rras, ASCL2, TRAP2C, Prl7b1, VEGFa, VEGFb, PDGF, and AKT3, beginning as early as E14.5. Notably, microRNA sequencing at E12.5, prior to these transcriptional changes, identified significant upregulation of miR-503-5p, a predicted inhibitor of several of these pathways. The summation of these observations suggests miR-503-5p may be an early driver of placental dysfunction in FGR, linking maternal malnutrition to impaired trophoblast invasion and angiogenesis. These findings provide insight into the molecular mechanisms underlying placental insufficiency and highlight miR-503-5p as a potential therapeutic target for improving pregnancy outcomes in FGR.

BackgroundPregnant females affected with COVID-19 are reported to have poorer disease outcomes as compared to non-pregnant females of a similar age group. COVID-19 may lead to adverse changes in the placenta, which needs to be studied. MethodsThis is a case series of 63 pregnant women hospitalized with COVID-19 from May 2020 to February 2021.The primary outcomes were maternal death or complications. Results63 women were studied. 83.3% of women were in the age group of 26 to 35 years. 33% women had associated comorbidities. 68.3% of women tested positive in their third trimester, 15.9% and 11% tested positive in their second and first trimesters respectively. 73% women had mild disease and 27% women required oxygen support. 3/63 women died. One woman in the second and two women in the third trimester died respectively. Histopathological examination in 13 placentae (of 19 placentae examined) were suggestive of maternal and fetal malperfusion. ConclusionPregnant COVID-19 women may develop disease-related as well as obstetric complications.

Early onset preeclampsia is a placental disorder characterized by shallow implantation, whereas placenta accreta spectrum is a placental disorder of deep placental attachment. This study compares the transcriptome of these two obstetric syndromes. By integrating available microarray and single-cell placenta/decidua transcriptomic datasets, we demonstrated that early onset preeclampsia genes are inversely expressed in placenta accreta, with the most marked differences noted in cell types of decidua, endothelial, and extravillous trophoblasts. Our findings highlight the key functions of trophoblast cell migration and invasion, decidua cell signaling, hypoxia pathways, and global growth factor and collagen contributions to these pregnancy disorders. This research provides new insights into the mechanisms of placentation and unifies these clinical siloes of disease by focusing on the fundamental biology of placental development at the maternal-fetal interface.

ObjectiveThe immune system plays a role in the occurrence and progression of numerous pregnancy complications, particularly preeclampsia (PE). This study aims to identify critical immune biomarkers via machine learning and assess their predictive ability. MethodsGene expression data were retrieved from the GEO database, while immune-related genes were obtained from the ImmPort repository. Differential expression analysis was then conducted to identify immune genes associated with PE. Different immune-related genes (DIRGs) were subjected to functional and pathway enrichment analysis. We adopted protein-protein interaction (PPI) networks for exploring the connections among various DIRGs and integrated two machine-learning to pinpoint candidate biomarkers in PE. Diagnostic performance was assessed via ROC curve analysis, with predictive accuracy further quantified using nomogram calibration. Findings were validated through integrated computational and experimental analyses. In silico validation utilized additional GEO datasets, while experimental confirmation involved qRT-PCR and IHC assessment of placental tissues. We developed a nomogram to predict PE utilizing two immune-related genes. Cellular composition was inferred from transcriptomic data using CIBERSORT deconvolution.. ResultsWe identified 66 differentially expressed genes (DEGs) and 10 DIRGs between PE pregnancies and normotensive pregnancies. The GO analyses revealed that the DIRGs were enriched in gonadotropin secretion, the regulation of gonadotropin secretion, and the regulation of endocrine processes. Functional annotation revealed enrichment in cytokine and neuroactive ligand-receptor pathways. SERPINA3 and NDRG1 emerged as top-performing biomarkers (training AUCs: 0.812 and 0.866; external validation: 0.795 and 0.781), with overexpression validated in clinical specimens. Both genes inversely regulated M2 macrophage abundance (P < 0.05). ConclusionPE is fundamentally an immune-mediated disorder. SERPINA3 and NDRG1 can be identified as key immune genes associated with M2 macrophages, and these findings provide novel perspectives for the diagnosis and pathogenesis of PE.

Studying the human placenta through in vitro cell culture methods is necessary due to limited access and amenability of human placental tissue to certain experimental methods as well as distinct anatomical and physiological differences between animal and human placentas. Selecting an in vitro culture model of the human placenta is challenging due to representation of different trophoblast cell types with distinct biological roles and limited comparative studies that define key characteristics of these models. Therefore, the aim of this research was to create a comprehensive transcriptomic comparison of common in vitro models of the human placenta compared to bulk placental tissue from the CANDLE and GAPPS cohorts (N=1083). We performed differential gene expression analysis on publicly available RNA sequencing data from 6 common in vitro models of the human placenta (HTR-8/SVneo, BeWo, JEG-3, JAR, Primary Trophoblasts, and Villous Explants) and compared to CANDLE and GAPPS bulk placental tissue or cytotrophoblast, syncytiotrophoblast, and extravillous trophoblast cell types derived from bulk placental tissue. All in vitro placental models had a substantial number of differentially expressed genes (DEGs, FDR<0.01) compared to the CANDLE and GAPPS placentas (Average DEGs=10,873), and the individual trophoblast cell types (Average DEGs=5,346), indicating that there are vast differences in gene expression compared to bulk and cell-type specific human placental tissue. Hierarchical clustering identified 53 gene clusters with distinct expression profiles across placental models, with 22 clusters enriched for specific KEGG pathways, 7 clusters enriched for high-expression placental genes, and 7 clusters enriched for absorption, distribution, metabolism, and excretion genes. In vitro placental models were classified by fetal sex based on expression of Y-chromosome genes that identified HTR-8/SVneo cells as being of female origin, while JEG-3, JAR, and BeWo cells are of male origin. Overall, none of the models were a close approximation of the transcriptome of bulk human placental tissue, highlighting the challenges with model selection. To enable researchers to select appropriate models, we have compiled data on differential gene expression, clustering, and fetal sex into an accessible web application: "Comparative Transcriptomic Placental Model Atlas (CTPMA)" which can be utilized by researchers to make informed decisions about their selection of in vitro placental models.

Gestational diabetes mellitus (GDM) affects 2-5% of all pregnancies and is known to place the fetus at risk for adverse fetal outcomes. Previous studies have reported the increased presence of villous immaturity in the placentas of women with gestational diabetes. Villous immaturity poses a great risk of restricted diffusion capacity across the placenta and may be a marker for some of the placental insufficiency associated with diabetes mellitus. The present study looks at the possibility of using fibrin stabilizing factor, or Factor XIII (FXIII), as a biomarker of villous immaturity. The aim of the present study is to establish a baseline pattern of FXIII expression in placentas of women in Saint John, NB with GDM, without villous immaturity using a scoring formula adapted from surgical pathology. While the small sample size precludes definitive conclusions regarding the expression of FXIII in normal placentas in women with GDM, there appears to a baseline of strong FXIII expression in normal placental tissues from the second and third trimester of pregnancy. Further study using a larger sample size is required to determine if a correlation exists between level of FXIII expression and degree of villous maturity in patients with GDM, which could improve the histologic assessment of placental development.

BackgroundOxytocin signaling may play an important role in the human placenta during pregnancy, where abnormal function can cause pregnancy complications such as preeclampsia, a hypertension syndrome with elusive etiology, treatment, and diagnosis. As pregnancy progresses, the clinical effects of high blood pressure tend to worsen. Therefore, an early diagnosis of preeclampsia is necessary for a successful pregnancy. MethodThis study examined placenta and plasma samples from normal and preeclamptic pregnancies, approved by the Institutional Review Board. qRT-PCR, western blot, ELISA, gelatin zymography, and ChIP were performed on placental tissues. JEG-3 cells and HUVECs were cultured under normoxia or hypoxia with oxytocin or atosiban. siRNA/miRNA transfections and RUPP rat models assessed oxytocins effects. Data were analyzed using ANOVA and Duncans test (P [&le;] 0.05) in SPSS. ResultHere, we assessed the effects of oxytocin signaling on key placental functions and its correlation with preeclampsia, revealing a significant association with placental dysfunction. Our findings revealed that oxytocin increased trophoblast invasion via ERK1/2- and JNK/AP-1-dependent pathways. Notably, oxytocin signaling was inhibited by hsa-miR-193b-5p and hypoxia. Administering atosiban to pregnant rats hindered placental invasion activity, mirroring symptoms of preeclampsia, and disrupted placental development. Finally, we examined oxytocin signaling in patients with preeclampsia by analyzing oxytocin levels in the first trimester. Oxytocin levels were higher in those who later developed preeclampsia than normal pregnant women. ConclusionThese results indicate that changes in oxytocin signaling are related with preeclampsia throughout pregnancy, emphasizing its potential as a novel early diagnostic biomarker.

The most common pregnancy complication is gestational diabetes mellitus (GDM), which is a glucose tolerance disorder. Obesity and older maternal age, which are associated with low-grade systemic inflammation, are the main risk factors for GDM. To evaluate the complexity and differences in the immune landscape at the fetal-maternal interface, we examined the maternally derived tissue, decidua basalis (DB), from healthy women, women with obesity, and women with GDM using flow cytometry, western blot, and gene expression analysis. Our results showed that the immune cell composition of DB is not altered by obesity; however, in GDM pregnancies, the DB displays a dysregulated PD-1/PD-L1 axis and significantly reduced regulatory T cell (Treg) infiltration, suggesting reduced local immunosuppression. Our study provides a detailed picture of the immune landscape at the fetal-maternal interface in normal, obese, and GDM pregnancies. This will aid our understanding of possible dysfunctional immune mechanisms in GDM.

Uterine Natural Killer (uNK) cells, predominant leukocytes in mouse and human pregnant uteruses, play crucial roles in angiogenesis and pregnancy protection. In mice, DBA lectin-reactive uNK cells expressing Gal-N-Ac sugar exhibit angiogenic functions essential for pregnancy maintenance. This study compares the impact of different nutritional imbalances on mouse pregnancy and the activation of angiogenic DBA+ uNK cells to safeguard against pregnancy complications. High Fat (HF), High Carbohydrate (HC), High Protein (HP), and Food Restriction (FR) diets were administered from gestation day (GD) 1 to GD10 or until parturition. HF and HC diets led to reduced expression of DBA-identified N-acetyl-D-galactosamine, akin to LPS-induced inflammation, and decreased uNK perforin levels. Additionally, HF and HC diets resulted in elevated endometrial cleaved caspase-3 and decreased smooth muscle alpha-actin, causing blood vessel wall thinning without jeopardizing pregnancy term. FR impaired uNK differentiation, manifesting as an "all-or-none" phenomenon with 50% pregnancy failure. Our findings highlight the intricate relationship between nutritional imbalances and mouse pregnancy outcomes. Notably, high-fat diets elicited pronounced responses from DBA+ uNK cells, while high-protein diets had relatively weaker effects. This study underscores the importance of comprehending uNK cell dynamics in maintaining pregnancy homeostasis under diverse dietary conditions, paving the way for elucidating molecular mechanisms governing these interactions. By shedding light on these complex relationships, this research offers valuable insights for improving maternal and fetal health in the context of nutritional interventions during pregnancy.

BACKGROUNDDysregulated myometrial contractility contributes to obstetric complications. Sphingosine-1-phosphate (S1P) is an important inflammatory regulator in the myometrium and decidua, yet its metabolic dynamics during pregnancy are poorly characterized. This study aimed to profile the expression of S1P metabolic enzymes and receptors, and quantify sphingolipid metabolism in human gestational tissues across pregnancy. METHODSMyometrium, decidua parietalis, and chorioamnion were collected from women undergoing cesarean sections at term ([&ge;]37 weeks gestation) without labor (TNL), at term with labor (TL), and preterm (<37 weeks gestation) without labor (PTNL). Messenger RNA (mRNA) expression of S1P metabolic enzymes and receptors was assessed using quantitative polymerase chain reaction, while sphingolipids were quantified using targeted liquid chromatography-tandem mass spectrometry. RESULTSS1P metabolic enzymes and receptors were differentially expressed across gestational tissues. At TNL, SPHK1 expression was significantly higher in the decidua parietalis than in the chorioamnion and myometrium. The myometrium exhibited the highest mRNA expression of S1P receptors (S1PR1-4) compared to the decidua and chorioamnion. At term, S1P was more abundant in the myometrium than in the decidua parietalis and chorioamnion. Both SPHK1 and S1P were significantly increased in TL compared to TNL myometrium. S1P levels were higher in the myometrium at TNL compared to PTNL, while no significant differences were observed in the decidua and chorioamnion. Overall, sphingolipid metabolism was highest in the decidua and myometrium and lowest in the chorioamnion at term. CONCLUSIONThese findings reveal tissue-specific regulation of S1P metabolism and signaling in human gestational tissues, suggesting a therapeutic role of S1P in modulating myometrial contractility.

Regulatory T lymphocytes are essential for maternal immunotolerance. Their de novo differentiation in the placenta is regulated by local intercellular interactions involving primed uterine immune cells, fetal syncytiotrophoblasts, and the cytokine environment. Trophoblast-derived, HLA-G-positive extracellular vesicles (EVs) can bind to T lymphocytes, thereby influencing their differentiation and cytokine production. Thus, these EVs play a role in establishing and maintaining a tolerogenic environment. In our study, we used the BeWo choriocarcinoma cell line to model the effects of trophoblast-derived EVs. Large EVs derived from BeWo cells (BeWo-12.5K lEVs) reduce IL-6R expression on CD4+ T cells. This modifies the IL-6 pathway by downregulating the transcription factors STAT3 and NFKB1, and PIAS3, while upregulating STAT1. This may be caused by specific microRNAs (miRNAs), such as hsa-mir-92a-3p, hsa-mir-520f-3p, and hsa-mir-25-3p. These microRNAs are present in BeWo-12.5K lEVs and target the IL-6 pathway. BeWo-12.5K lEVs induce phenotypic and functional changes in T cells, enhancing the ratio of CD4+/CD25+ T cells that produce IL-10. Pregnancy-associated IL-6R downregulation has been demonstrated in clinical samples. Significantly lower levels of IL-6R were detected on circulating CD4+CD25+ T cells in healthy pregnant women than in healthy non-pregnant individuals. This finding reflects the in vivo significance of our in vitro studies. Our studies suggest that communication between maternal and fetal cells significantly influences the development and maintenance of local T cell polarity. The microRNA content of HLA-G+ 12.5K lEVs appears to be key to this process, as it alters the IL-6 pathway.

Maternal intervillous monocytes (MIMs) and fetal Hofbauer cells (HBCs) are myeloid-derived immune cells at the maternal-fetal interface. Little is known regarding the molecular phenotypes and roles of these distinct monocyte/macrophage populations. Here, we used RNA sequencing to investigate the transcriptional profiles of MIMs and HBCs in six normal term pregnancies. Our analyses revealed distinct transcriptomes of MIMs and HBCs. Genes involved in differentiation and cell organization pathways were more highly expressed in MIMs vs. HBCs. In contrast, HBCs had higher expression of genes involved in inflammatory responses and cell surface receptor signaling. Maternal gravidity influenced monocyte programming, as expression of pro-inflammatory molecules was significantly higher in MIMs from multigravidas compared to primigravidas. In HBCs, multigravidas displayed enrichment of gene pathways involved in cell-cell signaling and differentiation. In summary, our results demonstrated that MIMs and HBCs have highly divergent transcriptional signatures, reflecting their distinct origins, locations, functions, and roles in inflammatory responses. Our data further suggested that maternal gravidity influences the gene signatures of MIMs and HBCs, potentially modulating the interplay between tolerance and trained immunity. The phenomenon of reproductive immune memory may play a novel role in the differential susceptibility of primigravidas to pregnancy complications.