Sylvie, Girard

ABSTRACT Problem Patients with threatened preterm labor (PTL) are treated with antibiotics, corticosteroids, and magnesium sulfate to mitigate infection, promote fetal lung maturation, provide fetal neuroprotection and overall minimize the impact of prematurity on the neonate. However, the effect of these drugs on the placental inflammatory profile is unknown even though these are given systemically and reach the placenta. We evaluated their action in an ex vivo model of placental inflammation. Method of Study Placental explants from uncomplicated pregnancies were exposed to lipopolysaccharide (LPS) ± azithromycin, betamethasone, and/or magnesium sulfate. Production (lysate) and secretion (supernatant) of pro‐ and anti‐inflammatory cytokines were assessed by ELISA. Results Both pro‐ and anti‐inflammatory cytokines were increased by LPS versus untreated. Azithromycin, or magnesium sulfate did not alter the inflammatory profile by themselves nor when added at the same time or 24 h after LPS. Betamethasone decreased both pro‐ and anti‐inflammatory cytokines only when administered at the same time as LPS, without any effects if delayed. Conclusions Therapeutic interventions classically used for preterm labor (PTL) do not impact the placental inflammatory profile by themselves or in the context of an ex vivo placental explants model of LPS‐induced inflammation, except for betamethasone when administered concurrently with LPS.

Abstract. Introduction: Preterm birth drives adverse perinatal maternal and infant health outcomes through heterogeneous symptoms, severity, and etiologies. Delivery prior to reaching 37 weeks of gestation may result from medically indicated intervention for pregnancy complications or spontaneously in the absence of prior symptoms. Placental tissue collected following preterm birth exhibits differential DNA methylation compared to full-term placentas and may indicate pregnancy health during gestation. Placental DNA currently has limited utility for assessing health of ongoing pregnancy, as sampling placental tissue during gestation increases the risk of infection and miscarriage. Risks associated with placental sampling during pregnancy limit the use of DNA methylation in clinical preterm birth prediction. Assessing preterm birth risk during gestation requires non-invasive methods for characterizing placental DNA methylation. Results: We quantified genome-wide DNA methylation patterns of hypermethylated cell-free DNA in pregnant (n = 99) and non-pregnant (n = 93) plasma using cell-free methylated DNA immunoprecipitation sequencing (cfMeDIP-seq). In each sample, we assessed DNA methylation status in 300-bp genomic windows, examining both sequencing read counts and calculated absolute molar DNA amount. Known hypermethylated placental regions, including RASSF1, STAT5A, and ERG promoters showed significantly increased odds of detection in pregnant samples, suggesting enrichment of cell-free placental DNA. Of the 536,444 300-bp windows examined, 173,071 (32%) showed significant enrichment in pregnant plasma. Linear modeling identified 107,505 differentially methylated regions (DMRs) associated with pregnancies later diagnosed with intrauterine growth restriction (IUGR) (n = 22). Alu elements showed increased representation in these DMRs than expected, while other repetitive elements exhibited underrepresentation. Discussion: These results demonstrate cfMeDIP-seq's ability to enrich for cell-free placental DNA and characterize cell-free DNA methylation signatures of pregnancies complicated by IUGR. Enrichment of cell-free placental DNA enables non-invasive profiling of placental DNA methylation from maternal plasma. Detectable epigenetic signatures in maternal plasma may identify pregnancies at elevated risk for preterm birth before clinical symptoms appear. Our findings further highlight the potential of cell-free placental DNA for monitoring pregnancy health.

Abstract SARS-CoV-2 infection disrupts iron homeostasis in organs such as the lung. Emerging evidence suggests similar dysregulation in the placenta may impair function and fetal growth. Ferroptosis, an iron-dependent form of cell death, is driven by the accumulation of labile ferrous iron, catalyzing the peroxidation of polyunsaturated fatty acids in the absence of sufficient iron storage or antioxidant defenses. This pathway has been implicated in SARS-CoV-2-related tissue damage in other organs and may contribute to placental dysfunction during pregnancy. However, the influence of infection timing, symptom severity, and fetal sex on placental iron regulation remains unexamined. We analyzed placental samples from a cohort of SARS-CoV-2-exposed pregnancies in the first (n = 6), second (n = 14), or third trimester (n = 30), classified by symptom severity (asymptomatic n = 23, symptomatic n = 27) and fetal sex, alongside unexposed controls (n = 47). We assessed placental iron deposition, lipid peroxidation, and mRNA and protein expression of ferroptosis markers. Publicly available RNA-sequencing datasets from human placenta tissue, exposed or not to SARS-CoV-2, were analyzed to assess ferroptosis-related gene expression. SARS-CoV-2 infection, particularly in symptomatic cases, was associated with reduced placental weight and birth weight. Asymptomatic cases showed increased placental iron deposition, which correlated with lower birthweight and was accompanied by elevated expression of nuclear receptor coactivator 4, a cytosolic adaptor protein that mediates the selective autophagic degradation of ferritin (ferritinophagy) and iron release. Placentas from symptomatic patients exhibited evidence of altered iron transport and sex-specific down-regulation of antioxidant defenses. Transcriptomic analyses further suggested widespread disruption of ferroptosis pathways in placentas from infected patients. Our findings reveal that SARS-CoV-2 infection alters placental iron homeostasis and is associated with ferroptosis-related changes, with distinct molecular responses based on timing of infection, symptom severity, and fetal sex.

Abstract Since the beginning of the COVID-19 pandemic, vulnerable populations such as pregnant persons have been at higher risk of severe symptoms and poor outcomes. Although reports of SARS-CoV-2 vertical transmission remain rare, several studies showed that maternal infection during pregnancy can induce histomorphological and inflammatory alterations in the placenta. However, the permissiveness of human trophoblasts to various variants of the virus remains poorly characterized. In this study, human primary villous cytotrophoblasts isolated from term placentas, along with trophoblastic cell lines BeWo, JEG-3, and HIPEC-65 were infected with the ancestral SARS-CoV-2 strain, which disseminated worldwide in early 2020. Permissiveness was assessed with quantitative RT-PCR, immunostaining of viral protein Nucleocapsid, and plaque assays. To investigate viral entry routes, cells were treated with Camostat mesylate (an inhibitor of the co-entry factor TMPRSS2) or chloroquine phosphate (an endosomal entry inhibitor) and viral fitness was assessed by plaque assays. Primary villous cytotrophoblasts and JEG-3 cells were also tested for infection with three pre-omicron SARS-CoV-2 variants of concern. Our results show that primary villous cytotrophoblasts are permissive to all tested SARS-CoV-2 strains in vitro. Infection with the ancestral SARS-CoV-2 strain relies mainly on a non-canonical endosomal entry pathway. Notably, JEG-3 cells represent an appropriate and convenient model for studying trophoblast infection by SARS-CoV-2, as they exhibit high permissiveness to the ancestral strain, and the SARS-CoV-2 entry pathway is similar to that in villous cytotrophoblasts. Overall, this study reveals that the cytotrophoblastic permissiveness to SARS-CoV-2 depends on the viral genetic nature and provides new insights into its entry route in human trophoblasts.

Abstract Background and objective The placenta is crucial for fetal development; altered function is associated with complications and adverse neonatal outcomes. Our goal was to ascertain changes in the placental transcriptome in relation to neonatal outcome and fetal/placental sex. Study design Seventy-two mother-baby dyads were included. Demographic, obstetrical, neonatal, and infant health data were obtained through medical charts. Adverse neonatal outcome was defined as the presence of a pulmonary, cardiac, neurological or other health complication. Bulk RNA-sequencing of placental biopsies was obtained. P-value <0.05 was considered statistically significant. Results Neonates experiencing adverse outcomes were more likely to be premature or have lower birth weights. Analysis of the placental transcriptome revealed a predominant inflammatory profile in pregnancies associated with adverse neonatal outcomes with the top pathways being related to immune and inflammatory responses. Among differently expressed genes (DEGs), 1237 were upregulated and 239 were downregulated in adverse vs no adverse outcomes. Furthermore, sex-specific differences in gene expression were observed and indicated that male and female placentas displayed unique DEGs in association with adverse outcomes. Indeed, no DEG was observed in female placentas when comparing those without vs with adverse neonatal outcomes, as opposed to 1279 DEGs in male placentas, of which 91% were up-regulated in adverse subgroups. Conclusions These findings highlight that inflammatory pathways are upregulated in placentas in association with adverse neonatal outcomes, and showcase the importance of the fetal sex in understanding neonatal health. The placenta provides a unique tool for early identification of high-risk infants rapidly after delivery.

Abstract BACKGROUND Postpartum preeclampsia (PPPE) is a maternal condition characterized by de novo hypertension in the postpartum period with end-organ damage. We investigated the use of perinatal immune changes, through routine complete blood count (CBC), to identify high-risk individuals before PPPE development. METHODS We performed a retrospective matched case-control study of 100 individuals with PPPE, 200 term pregnancies (Ctrl) and 200 antenatal preeclampsia (PE). Detailed demographic, obstetrical, and laboratory data were retrieved from medical records. Statistical analysis was performed using one-way ANOVA, multivariate regression, and paired or unpaired t-tests, as appropriate. RESULTS Individuals who developed PPPE were significantly older and predominantly Black vs Ctrl and PE. Both PE and PPPE had higher pre-pregnancy BMI and increased personal and family history of hypertension/PE vs Ctrl (P < 0.001). Before delivery, individuals who later developed PPPE, had lower total leukocyte counts vs Ctrl (9.61 vs 10.75 × 109/L, P < 0.05) whereas monocytes percentage was elevated (8.07 vs 7.27%, P < 0.01). Comparing the postpartum/antenatal ratio in-between each condition revealed elevated leukocyte ratio in PPPE vs Ctrl (P < 0.001). The Neutrophils ratio was also increased, whereas lymphocytes and monocytes were decreased in PPPE vs both Ctrl and PE. After adjusting for race, maternal age, pre-pregnancy BMI, personal history of PE/HT, and diabetes mellitus, perinatal immune changes were still significantly associated with PPPE. CONCLUSIONS Globally, perinatal immune changes were observed in individuals with a seemingly uncomplicated pregnancy prior to the development of PPPE. This strongly supports that such changes could be used to identify high-risk individuals prior to disease onset.

Abstract Pre-eclampsia (PE) affects 5–8% of pregnancies and has detrimental effects on maternal–fetal health. PE is characterized by de novo hypertension after 20 wk of gestation and end-organ damage. Systemic inflammatory imbalance has been associated with PE, but its contribution to the pathology is poorly understood. Our objective was to investigate maternal systemic immune changes in early-onset PE (EOPE) and late-onset PE (LOPE) versus uncomplicated pregnancies (control [CTRL]), and their contribution to endothelial activation, hallmark of hypertension. Blood samples were analyzed by flow cytometry, multiplex assay, intracellular cytokine staining, and single-cell RNA sequencing. We performed cocultures between circulating immune cells and HUVECs to assess endothelial activation. We found that EOPE had decreased regulatory T cells (4.64±0.33, p < 0.05) and monocytes (33.92±3.08, p < 0.01), whereas LOPE had decreased regulatory T cells (4.60±0.30, p < 0.05) and Th2 cells (7.50±0.62, p < 0.01) versus CTRL. Compared to CTRL, elevated cytokines/chemokines, and growth factors were observed in LOPE, whereas EOPE primarily showed decreased levels. Using intracellular cytokine staining, we observed more monocytes producing IL-12, TNF-α, and IL-1β (all p < 0.05) in LOPE versus CTRL. At the transcriptomic level, we found differentially expressed genes between EOPE and CTRL, predominantly related to upregulation of immune activation pathways. Lastly, EOPE PBMCs induced heightened endothelial activation in vitro observed by increased ICAM-1 and ET-1 (p < 0.05), whereas LOPE PBMCs required LPS stimulation. Although significant proteomic changes are observed in the LOPE group, the EOPE displayed changes mostly at the transcriptomic levels and could induce endothelial activation in vitro.

ABSTRACTProblemPreeclampsia (PE) and fetal growth restriction (FGR) are often associated with maternal inflammation and an increased risk of cardiovascular and metabolic disease in the affected mothers. The mechanism responsible for this increased risk of subsequent disease may involve reprogramming of innate immune cells, characterized by epigenetic modifications.Method of StudyCirculating monocytes from women with PE, FGR, or uncomplicated pregnancies (control) were isolated before labor. Cytokine release from monocytes following exposure to lipopolysaccharide (LPS) and the presence of lysine 4‐trimethylated histone 3 (H3K4me3) within TNF promoter sequences were evaluated. Single‐cell transcriptomic profiles of circulating monocytes from women with PE or uncomplicated pregnancies were assessed.ResultsMonocytes from women with PE or FGR exhibited increased IL‐10 secretion and decreased IL‐1β and GM‐CSF secretion in response to LPS. While TNFα secretion was not significantly different in cultures of control monocytes versus those from complicated pregnancies with or without LPS exposure, monocytes from complicated pregnancies had significantly decreased levels of H3K4me3 associated with TNF promoter sequences. Cluster quantification and pathway analysis of differentially expressed genes revealed an increased proportion of anti‐inflammatory myeloid cells and a lower proportion of inflammatory non‐classical monocytes among the circulating monocyte population in women with PE.ConclusionsMonocytes from women with PE and FGR exhibit an immune tolerance phenotype before initiation of labor. Further investigation is required to determine whether this tolerogenic phenotype persists after the affected pregnancy and contributes to increased risk of subsequent disease.

AbstractProblemThe COVID‐19 pandemic has been shown to have a detrimental impact on the mental health of pregnant individuals, and chronic stress can alter the immune profile. However, the effects of the COVID‐19 pandemic on the immune system in pregnancy are still poorly understood. We aimed to evaluate the impact of pandemic exposure on the maternal immune profile in uncomplicated pregnancies.Method of studyWe collected blood and placenta samples from pregnant individuals exposed and unexposed to the pandemic to compare their immune and inflammatory profiles. We performed co‐culture with circulating maternal immune cells and endothelial cells to assess endothelial activation. Statistical analysis was performed using unpaired t‐test, Mann‐Whitney, or Fisher's exact test as appropriate.ResultsIn exposed individuals, we observed a decreased proportion of Th2 cells (p < .0001) and Treg/Th17 ratio (p < .05), as well as an increased Th1/Th2 ratio (p < .0001). Levels of IL‐1β (p < .01) and IL‐18 (p < .01) were increased in the circulation of exposed participants, whilst other mediators were significantly decreased (IFNγ, IL‐8, MCP‐1, amongst others). Furthermore, we observed increased production of ICAM, hallmark of endothelial activation, when we co‐cultured endothelial cells with immune cells from exposed individuals. Vaccination status impacted the cellular profile with increased proportions of Th1 and B cells in vaccinated participants.ConclusionOverall, we observed a pro‐inflammatory bias in the circulation of pregnant individuals exposed to the COVID‐19 pandemic, with otherwise uncomplicated pregnancies. Our work also supports an association between the increased risk of endothelial activation/hypertension and SARS‐CoV2 infection, which might be driven in part by exposure to the pandemic and associated stressors.

AbstractProblemIt is now recognized that SARS‐CoV‐2 infection and pandemic‐related stress impacts maternal health. However, their effects at the maternal‐fetal interface are still debated.Method of studyWe recruited 199 women between March 2020 and July 2021, 79 SARS‐CoV‐2+ and 120 negative (the latter exposed to pandemic stress only). We also included 40 historic controls (i.e. pre‐pandemic uncomplicated pregnancies recruited before March 2020). Placental samples were collected for protein and histological analysis.ResultsThe majority of SARS‐CoV‐2+ women were multiethnic, had higher pre‐pregnancy BMI and elevated preterm birth rate (17%) vs SARS‐CoV‐2– or historic control. Placental inflammatory profile revealed increased IL‐1Ra and CRP, independently of SARS‐CoV‐2 status, whilst MCP‐1, IL‐6 and IFNγ were elevated in the negative, but pandemic stress‐exposed, group. These changes were predominant in placentas with inflammatory lesions on histopathological analysis. Furthermore, we observed elevated immune cells (CD45+) in placentas from SARS‐CoV‐2+ and negative pregnancies vs historic controls, even when individuals with pregnancy complications were excluded.ConclusionsPlacental inflammatory profiles differed between SARS‐CoV‐2 statuses, namely exposed to pandemic stress +/‐ SARS‐CoV‐2 infection. This highlights the need to understand the differences between the effects of pandemic‐related stress and the added burden of SARS‐CoV‐2 infection on placental health.