Implication of viruses in the etiology of preeclampsia.

Preeclampsia is one of the most common disorders that poses threat to both mothers and neonates and a major contributor to perinatal morbidity and mortality worldwide. Viral infection during pregnancy is not typically considered to cause preeclampsia; however, syndromic nature of preeclampsia etiology and the immunomodulatory effects of viral infections suggest that microbes could trigger a subset of preeclampsia. Notably, SARS-CoV-2 infection is associated with an increased risk of preeclampsia. Herein, we review the potential role of viral infections in this great obstetrical syndrome. According to in vitro and in vivo experimental studies, viral infections can cause preeclampsia by introducing poor placentation, syncytiotrophoblast stress, and/or maternal systemic inflammation, which are all known to play a critical role in the development of preeclampsia. Moreover, clinical and experimental investigations have suggested a link between several viruses and the onset of preeclampsia via multiple pathways. However, the results of experimental and clinical research are not always consistent. Therefore, future studies should investigate the causal link between viral infections and preeclampsia to elucidate the mechanism behind this relationship and the etiology of preeclampsia itself.

Decidual γδT cells of early human pregnancy produce angiogenic and immunomodulatory proteins while also possessing cytotoxic potential.

During pregnancy, the maternal immune system must allow and support the growth of the developing placenta while maintaining the integrity of the mother's body. The trophoblast's unique HLA signature is a key factor in this physiological process. This study focuses on decidual γδT cell populations and examines their expression of receptors that bind to non-classical HLA molecules, HLA-E and HLA-G. We demonstrate that decidual γδT cell subsets, including Vδ1, Vδ2, and double-negative (DN) Vδ1-/Vδ2- cells express HLA-specific regulatory receptors, such as NKG2C, NKG2A, ILT2, and KIR2DL4, each with varying dominance. Furthermore, decidual γδT cells produce cytokines (G-CSF, FGF2) and cytotoxic mediators (Granulysin, IFN-γ), suggesting functions in placental growth and pathogen defense. However, these processes seem to be controlled by factors other than trophoblast-derived non-classical HLA molecules. These findings indicate that decidual γδT cells have the potential to actively contribute to the maintenance of healthy human pregnancy.

[Metformin ameliorates PM2.5-induced functional impairment of placental trophoblasts by inhibiting ferroptosis].

OBJECTIVE: To investigate the protective effect of metformin against PM2.5-induced functional impairment of placental trophoblasts and explore the underlying mechanism. METHODS: Sixteen pregnant Kunming mice were randomly assigned into two groups (n=8) for intratracheal instillation of PBS or PM2.5 suspension at 1.5, 7.5, and 12.5 days of gestation. The pregnancy outcome of the mice was observed, and placental zonal structure and vascular density of the labyrinth area were examined with HE staining, followed by detection of ferroptosis-related indexes in the placenta. In cultured human trophoblasts (HTR8/SVneo cells), the effects of PM2.5 exposure and treatment with metformin on cell viability, proliferation, migration, invasion, and tube formation ability were evaluated using CCK8 assay, EDU staining, wound healing assay, Transwell experiment, and tube formation experiment; the cellular expressions of ferroptosis-related proteins were analyzed using ELISA and Western blotting. RESULTS: M2.5 exposure of the mice during pregnancy resulted in significantly decreased weight and number of the fetuses and increased fetal mortality with a reduced placental weight (all P<0.001). PM2.5 exposure also caused obvious impairment of the placental structure and trophoblast ferroptosis. In cultured HTR8/SVneo cells, PM2.5 significantly inhibited proliferation, migration, invasion, and angiogenesis of the cells by causing ferroptosis. Metformin treatment obviously attenuated PM2.5-induced inhibition of proliferation, migration, invasion, and angiogenesis of the cells, and effectively reversed PM2.5-induced ferroptosis in the trophoblasts as shown by significantly increased intracellular GSH level and SOD activity, reduced MDA and Fe2+ levels, and upregulated GPX4 and SLC7A11 protein expression (P<0.05 or 0.01). CONCLUSION: PM2.5 exposure during pregnancy causes adverse pregnancy outcomes and ferroptosis and functional impairment of placental trophoblasts in mice, and metformin can effectively alleviate PM2.5-induced trophoblast impairment.

Metformin Inhibits Zika Virus Infection in Trophoblast Cell Line.

Zika virus (ZIKV) infections have been associated with severe clinical outcomes, which may include neurological manifestations, especially in newborns with intrauterine infection. However, licensed vaccines and specific antiviral agents are not yet available. Therefore, a safe and low-cost therapy is required, especially for pregnant women. In this regard, metformin, an FDA-approved drug used to treat gestational diabetes, has previously exhibited an anti-ZIKA effect in vitro in HUVEC cells by activating AMPK. In this study, we evaluated metformin treatment during ZIKV infection in vitro in a JEG3-permissive trophoblast cell line. Our results demonstrate that metformin affects viral replication and protein synthesis and reverses cytoskeletal changes promoted by ZIKV infection. In addition, it reduces lipid droplet formation, which is associated with lipogenic activation of infection. Taken together, our results indicate that metformin has potential as an antiviral agent against ZIKV infection in vitro in trophoblast cells.

High glucose-induced p66Shc mitochondrial translocation regulates autophagy initiation and autophagosome formation in syncytiotrophoblast and extravillous trophoblast.

BACKGROUND: p66Shc, as a redox enzyme, regulates reactive oxygen species (ROS) production in mitochondria and autophagy. However, the mechanisms by which p66Shc affects autophagosome formation are not fully understood. METHODS: p66Shc expression and its location in the trophoblast cells were detected in vivo and in vitro. Small hairpin RNAs or CRISPR/Cas9, RNA sequencing, and confocal laser scanning microscope were used to clarify p66Shc's role in regulating autophagic flux and STING activation. In addition, p66Shc affects mitochondrial-associated endoplasmic reticulum membranes (MAMs) formation were observed by transmission electron microscopy (TEM). Mitochondrial function was evaluated by detected cytoplastic mitochondrial DNA (mtDNA) and mitochondrial membrane potential (MMP). RESULTS: High glucose induces the expression and mitochondrial translocation of p66Shc, which promotes MAMs formation and stimulates PINK1-PRKN-mediated mitophagy. Moreover, mitochondrial localized p66Shc reduces MMP and triggers cytosolic mtDNA release, thus activates cGAS/STING signaling and ultimately leads to enhanced autophagy and cellular senescence. Specially, we found p66Shc is required for the interaction between STING and LC3II, as well as between STING and ATG5, thereby regulates cGAS/STING-mediated autophagy. We also identified hundreds of genes associated several biological processes including aging are co-regulated by p66Shc and ATG5, deletion either of which results in diminished cellular senescence. CONCLUSION: p66Shc is not only implicated in the initiation of autophagy by promoting MAMs formation, but also helps stabilizing active autophagic flux by activating cGAS/STING pathway in trophoblast.

CircTHBS1 promotes trophoblast cell migration and invasion and inhibits trophoblast apoptosis by regulating miR-136-3p/IGF2R axis.

The precise molecular mechanism behind fetal growth restriction (FGR) is still unclear, although there is a strong connection between placental dysfunction, inadequate trophoblast invasion, and its etiology and pathogenesis. As a new type of non-coding RNA, circRNA has been shown to play a crucial role in the development of FGR. This investigation identified the downregulation of hsa_circ_0034533 (circTHBS1) in FGR placentas through high-sequencing analysis and confirmed this finding in 25 clinical placenta samples using qRT-PCR. Subsequent in vitro functional assays demonstrated that silencing circTHBS1 inhibited trophoblast proliferation, migration, invasion, and epithelial mesenchymal transition (EMT) progression and promoted apoptosis. Furthermore, when circTHBS1 was overexpressed, cell function experiments showed the opposite result. Analysis using fluorescence in situ hybridization revealed that circTHBS1 was primarily found in the cytoplasmic region. Through bioinformatics analysis, we anticipated the involvement of miR-136-3p and IGF2R in downstream processes, which was subsequently validated through qRT-PCR and dual-luciferase assays. Moreover, the inhibition of miR-136-3p or the overexpression of IGF2R partially reinstated proliferation, migration, and invasion abilities following the silencing of circTHBS1. In summary, the circTHBS1/miR-136-3p/IGF2R axis plays a crucial role in the progression and development of FGR, offering potential avenues for the exploration of biological indicators and treatment targets.

Human trophoblast stem cells restrict human cytomegalovirus replication.

Placental infection plays a central role in the pathogenesis of congenital human cytomegalovirus (HCMV) infections and is a cause of fetal growth restriction and pregnancy loss. HCMV can replicate in some trophoblast cell types, but it remains unclear how the virus evades antiviral immunity in the placenta and how infection compromises placental development and function. Human trophoblast stem cells (TSCs) can be differentiated into extravillous trophoblasts (EVTs), syncytiotrophoblasts (STBs), and organoids, and this study assessed the utility of TSCs as a model of HCMV infection in the first-trimester placenta. HCMV was found to non-productively infect TSCs, EVTs, and STBs. Immunofluorescence assays and flow cytometry experiments further revealed that infected TSCs frequently only express immediate early viral gene products. Similarly, RNA sequencing found that viral gene expression in TSCs does not follow the kinetic patterns observed during lytic infection in fibroblasts. Canonical antiviral responses were largely not observed in HCMV-infected TSCs and TSC-derived trophoblasts. Rather, infection dysregulated factors involved in cell identity, differentiation, and Wingless/Integrated signaling. Thus, while HCMV does not replicate in TSCs, infection may perturb trophoblast differentiation in ways that could interfere with placental function. IMPORTANCE: Placental infection plays a central role in human cytomegalovirus (HCMV) pathogenesis during pregnancy, but the species specificity of HCMV and the limited availability and lifespan of primary trophoblasts have been persistent barriers to understanding how infection impacts this vital organ. Human trophoblast stem cells (TSCs) represent a new approach to modeling viral infection early in placental development. This study reveals that TSCs, like other stem cell types, restrict HCMV replication. However, infection perturbs the expression of genes involved in differentiation and cell fate determination, pointing to a mechanism by which HCMV could cause placental injury.

Low levels of nicotine and cotinine but not benzo[a]pyrene induce human trophoblast cell proliferation.

E-cigarettes use constitutes a source of thirdhand nicotine exposure. The increasing use of electronic cigarettes in homes and public places increases the risk of exposure of pregnant women to thirdhand nicotine. The effects of exposure of pregnant women to very low levels of nicotine have not been studied in humans but detrimental in experimental animals. The objective of this study is to investigate the effect of nanomolar concentrations of nicotine and its metabolite cotinine on the proliferation of JEG-3, a human trophoblast cell line. We also studied the proliferative effect of nanomolar concentrations of benzo[a]pyrene (B[a]P), a polycyclic hydrocarbon in tobacco smoke, for comparison. We treated JEG-3 cells in culture with nanomolar concentrations of nicotine, cotinine, and B[a]P. Their effect on cell proliferation was determined, relative to untreated cells, by MTT assay. Western blotting was used to assess the mitogenic signaling pathways affected by nicotine and cotinine. In contrast to the inhibitory effects reported with higher concentrations, we showed that nanomolar concentrations of nicotine and cotinine resulted in significant JEG-3 cell proliferation and a rapid but transient increase in levels of phosphorylated ERK and AKT, but not STAT3. Biphasic, non-monotonic effect on cell growth is characteristic of endocrine disruptive chemicals like nicotine. The mitogenic effects of nicotine and cotinine potentially contribute to increased villous epithelial thickness, seen in placentas of some smoking mothers. This increases the diffusion distance for oxygen and nutrients between mother and fetus, contributing to intrauterine growth restriction in infants of smoking mothers.

Pigment epithelium­derived factor inhibits proliferation, invasion and angiogenesis, and induces ferroptosis of extravillous trophoblasts by targeting Wnt­ß­catenin/VEGF signaling in placenta accreta spectrum.

Placenta accreta spectrum (PAS) is one of the most dangerous complications in obstetrics, which can lead to severe postpartum bleeding and shock, and even necessitate uterine removal. The abnormal migration and invasion of extravillous trophoblast cells (EVTs) and enhanced neovascularization occurring in an uncontrolled manner in time and space are closely related to the abnormal expression of pro­angiogenic and anti­angiogenic factors. The pigment epithelium­derived factor (PEDF) is a multifunctional regulatory factor that participates in several important biological processes and is recognized as the most efficient inhibitor of angiogenesis. The present study aimed to explore the effects of PEDF on EVT phenotypes and the underlying mechanisms in PAS. HTR­8/SVneo cells were transfected to overexpress or knock down PEDF. Cell proliferation and invasion were assessed using Cell Counting Kit­8, 5­ethynyl­2'­deoxyuridine and Transwell assays. In vitro angiogenesis was analyzed using tube formation assays. The degree of ferroptosis was assessed by evaluating the levels of lipid reactive oxygen species, total iron, Fe2+, malondialdehyde and reduced glutathione using commercial kits. The expression levels of biomarkers of ferroptosis, angiogenesis, cell proliferation and Wnt signaling were examined by western blotting. PEDF overexpression decreased the proliferation, invasion and angiogenesis, and induced ferroptosis of EVTs. Activation of Wnt signaling with BML­284 and overexpression of vascular endothelial growth factor (VEGF) reversed the PEDF overexpression­induced suppression of cell proliferation, invasion and tube formation. PEDF overexpression­induced ferroptosis was also decreased by Wnt agonist treatment and VEGF overexpression. It was predicted that PEDF suppressed the proliferation, invasion and angiogenesis, and increased ferroptosis in EVTs by decreasing Wnt­ß­catenin/VEGF signaling. The findings of the present study suggested a novel regulatory mechanism of the phenotypes of EVTs and PAS.

Protective role of complement factor H against the development of preeclampsia.

Pregnancy is an immunologically regulated, complex process. A tightly controlled complement system plays a crucial role in the successful establishment of pregnancy and parturition. Complement inhibitors at the feto-maternal interface are likely to prevent inappropriate complement activation to protect the fetus. In the present study, we aimed to understand the role of Factor H (FH), a negative regulator of complement activation, in normal pregnancy and in a model of pathological pregnancy, i.e. preeclampsia (PE). The distribution and expression of FH was investigated in placental tissues, various placental cells, and in the sera of healthy (CTRL) or PE pregnant women via immunohistochemistry, RT-qPCR, ELISA, and Western blot. Our results showed a differential expression of FH among the placental cell types, decidual stromal cells (DSCs), decidual endothelial cells (DECs), and extravillous trophoblasts (EVTs). Interestingly, FH was found to be considerably less expressed in the placental tissues of PE patients compared to normal placental tissue both at mRNA and protein levels. Similar results were obtained by measuring circulating FH levels in the sera of third trimester CTRL and PE mothers. Syncytiotrophoblast microvesicles, isolated from the placental tissues of PE and CTRL women, downregulated FH expression by DECs. The present study appears to suggest that FH is ubiquitously present in the normal placenta and plays a homeostatic role during pregnancy.

The Impact of SLC2A8 RNA Interference on Glucose Uptake and the Transcriptome of Human Trophoblast Cells.

While glucose is the primary fuel for fetal growth, the placenta utilizes the majority of glucose taken up from the maternal circulation. Of the facilitative glucose transporters in the placenta, SLC2A8 (GLUT8) is thought to primarily function as an intracellular glucose transporter; however, its function in trophoblast cells has not been determined. To gain insight into the function of SLC2A8 in the placenta, lentiviral-mediated RNA interference (RNAi) was performed in the human first-trimester trophoblast cell line ACH-3P. Non-targeting sequence controls (NTS RNAi; n = 4) and SLC2A8 RNAi (n = 4) infected ACH-3P cells were compared. A 79% reduction in SLC2A8 mRNA concentration was associated with an 11% reduction (p ≤ 0.05) in ACH-3P glucose uptake. NTS RNAi and SLC2A8 RNAi ACH-3P mRNA were subjected to RNAseq, identifying 1525 transcripts that were differentially expressed (|log2FC| > 1 and adjusted p-value < 0.05), with 273 transcripts derived from protein-coding genes, and the change in 10 of these mRNAs was validated by real-time qPCR. Additionally, there were 147 differentially expressed long non-coding RNAs. Functional analyses revealed differentially expressed genes involved in various metabolic pathways associated with cellular respiration, oxidative phosphorylation, and ATP synthesis. Collectively, these data indicate that SLC2A8 deficiency may impact placental uptake of glucose, but that its likely primary function in trophoblast cells is to support cellular respiration. Since the placenta oxidizes the majority of the glucose it takes up to support its own metabolic needs, impairment of SLC2A8 function could set the stage for functional placental insufficiency.

SFRP2 suppresses trophoblast cell migration by inhibiting the Wnt/ß­catenin pathway.

The present study investigates the role of Secreted Frizzled­Related Protein 2 (SFRP2) in trophoblast cells, a key factor in preeclampsia (PE) progression. Elevated levels of Secreted Frizzled­Related Protein 1/3/4/5 (SFRP1/3/4/5) are associated with PE, but the role of SFRP2 is unclear. We analyzed SFRP2 expression in PE placental tissue using the GSE10588 dataset and overexpressed SFRP2 in JEG­3 cells via lentiviral transfection. The viability, migration, apoptosis, and proliferation of SFRP2­overexpressing JEG­3 cells were assessed using Cell Counting Kit­8, Transwell assays, flow cytometry, and EdU staining. Additionally, we evaluated the impact of SFRP2 overexpression on key proteins in the Wnt/ß­catenin pathway and apoptosis markers (Bax, cleaved­caspase 3, BCL­2, MMP9, E­cadherin, Wnt3a, Axin2, CyclinD1, c­Myc, p­ß­catenin, ß­catenin, phosphorylated Glycogen Synthase Kinase 3 beta (p­GSK3ß), and GSK3ß) through western blotting. Results showed high SFRP2 mRNA and protein expression in PE placenta and JEG­3 cells post­transfection. SFRP2 overexpression significantly reduced JEG­3 cell viability, proliferation, and migration, while increasing apoptosis. It also altered expression levels of Wnt pathway proteins, suggesting SFRP2's potential as a therapeutic target for PE by inhibiting trophoblast cell migration through the Wnt/ß­catenin signaling cascade.

Immunological regulation and the role of autophagy in preeclampsia.

Autophagy is a bulk degradation system that maintains cellular homeostasis by producing energy and/or recycling excess proteins. During early placentation, extravillous trophoblasts invade the decidua and uterine myometrium, facing maternal immune cells, which participate in the immune suppression of paternal and fetal antigens. Regulatory T cells will likely increase in response to a specific antigen before and during early pregnancy. Insufficient expansion of antigen-specific Treg cells, which possess the same T cell receptor, is associated with the pathophysiology of preeclampsia, suggesting sterile systemic inflammation. Autophagy is involved in reducing inflammation through the degradation of inflammasomes and in the differentiation and function of regulatory T cells. Autophagy dysregulation induces protein aggregation in trophoblasts, resulting in placental dysfunction. In this review, we discuss the role of regulatory T cells in normal pregnancies. In addition, we discuss the association between autophagy and regulatory T cells in the development of preeclampsia based on reports on the role of autophagy in autoimmune diseases.

Histological Analysis of Trophoblast Cells in the Mouse Placental Labyrinth Zone.

The mouse is a common animal species used for translational studies. In reproductive studies, this animal is typically preferred over other models as the rodent placenta shows similarities to the human but has a relatively short gestational period. In mice, the transport of oxygen and nutrients between mother and fetus occurs in a restricted area of the placenta called the labyrinth zone. Here, we provide a detailed protocol to study labyrinth zone trophoblast proliferation and syncytial trophoblast identification using paraffin-embedded histological sections of the mouse placenta and immunohistochemistry. By describing step by step how to collect the mouse placenta and process and analyze the labyrinth zone, we hope to help other scientists understand the contribution of changes in placental transport function in their experimental model and therefore advance our understanding of mechanisms underlying pregnancy complications.

In Vitro Culturing of Human Trophoblasts from Term Placenta.

Since the early 1960s, researchers began culturing placental cells to establish an in vitro model to study the biology of human trophoblasts, including their ability to differentiate into syncytiotrophoblasts and secrete steroid and peptide hormones that help sustain a viable pregnancy. This task was addressed by testing different serum concentrations, cell culture media, digestive enzymes, growth factors, substrate coating with diverse proteins from the extracellular matrix, and so on. Among the many methodological challenges, the contamination of trophoblasts with other cell types, such as immune and stromal cells, was a matter of concern. However, introducing the Percoll gradient to isolate cytotrophoblasts was an excellent contribution, and later, the depletion of contaminating cells by using magnetic bead-conjugated antibodies also helped increase the purity of cytotrophoblasts. Herein, with some modifications, we describe a rapid and easy method for cytotrophoblast isolation from the term human placenta based on the previously reported method by Harvey Kliman et al. (Endocrinology 118:1567-1582, 1986). This method yields about 40-90 million cells from a single placenta, with a purity of around 85-90%.

Placental Trophoblast Cell Isolation from the Term Placenta.

Multiple cell lines have been utilized over time in studying placental biology. Still, most of them rely on choriocarcinoma cells or immortalized trophoblast cells that may not be entirely comparable with actual human placental trophoblast cells. Term placentas can be a source of primary villous trophoblasts. However, challenges remain in isolating them and maintaining them in extended culture. This manuscript describes our three-phase protocol utilizing enzymatic/mechanical digestion, modified Percoll gradient density separation, and immunopurification using magnetic beads. The resulting trophoblast culture remains viable for an extended period and highly pure after initial passaging.

Generation of Knockout Mouse Trophoblast Stem Cells by CRISPR/Cas9.

The placenta is the organ that dictates the reproductive outcome of mammalian pregnancy by supplying nutrients and oxygen to the developing fetus to sustain its normal growth. During early mammalian development, trophoblast cells are the earliest cell type to differentiate with multipotent capacity to generate the trophoblast components of the placenta. The isolation and use of mouse trophoblast stem cells (mTSCs) to model in vitro trophoblast differentiation, in combination with CRISPR/Cas9 genome editing technology, has provided tremendous insight into the molecular mechanisms governing early mouse placentation. By knocking out a specific gene of interest in mTSCs, researchers are shedding light onto the molecular pathways involved in normal placental development and pregnancy disorders associated with abnormal placentation. In this chapter, we provide a detailed protocol for the genetic modification of mTSCs by using CRISPR/Cas9 genome editing system.

CRISPR Activation in Mouse Trophoblast Stem Cells.

The placenta is a vital organ that regulates nutrient supply to the developing embryo during gestation. In mice, the placenta is composed of trophoblast lineage and mesodermal derivatives, which merge through the chorioallantoic fusion process in a critical event for the progression of placenta development. The trophoblast lineage is derived from self-renewing, multipotent cells known as mouse trophoblast stem cells (mTSCs). These cells are a valuable tool that allows scientists to comprehend the signals regulating major placental cell types' self-renewal and differentiation capacity. Recent advances in CRISPR-Cas9 genome editing applied in mTSCs have provided novel insights into the molecular networks involved in placentation. Here, we present a comprehensive CRISPR activation (CRISPRa) protocol based on the CRISPR/gRNA-directed synergistic activation mediator (SAM) method to overexpress specific target genes in mTSCs.

Culture and Maintenance of Immune Cells to Model Innate Immune Status at the Feto-maternal Interface.

The inflammatory process leading to human labor is mostly facilitated by immune cells, which can be studied by isolating and characterizing primary immune cells from the feto-maternal interface. However, difficulty and inconsistency in sampling approaches of immune cells and short lifespan in vitro prevent their usage in mechanistic studies to understand the maternal-fetal immunobiology. To address these limitations, existing cell line models can be differentiated into immune-like cells for use in reproductive biology experiments. In this chapter, we discussed cell culture methods of maintaining and differentiating HL-60, THP-1, and NK-92 cells to obtain neutrophil-like, macrophage-like, and decidual natural killer-like cells, respectively, which can then be used together with intrauterine cells to elucidate and investigate immune mechanisms that contribute to parturition.

Nox2 inhibition reduces trophoblast ferroptosis in preeclampsia via the STAT3/GPX4 pathway.

AIMS: Ferroptosis, a novel mode of cell death characterized by lipid peroxidation and oxidative stress, plays an important role in the pathogenesis of preeclampsia (PE). The aim of this study is to determine the role of Nox2 in the ferroptosis of trophoblast cells, along with the underlying mechanisms. METHODS: The mRNA and protein levels of Nox2, STAT3, and GPX4 in placental tissues and trophoblast cells were respectively detected by qRT-PCR and western blot analysis. CCK8, transwell invasion and tube formation assays were used to evaluate the function of trophoblast cells. Ferroptosis was evaluated using flow cytometry and the lipid peroxidation assay. Glycolysis and mitochondrial respiration were investigated by detecting the extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) using Seahorse extracellular flux technology. The t-test or one-way ANOVA was used for statistical analysis. KEY FINDINGS: Nox2 was up-regulated while STAT3 and GPX4 were down-regulated in PE placental tissues. Nox2 knockdown inhibited ferroptosis in trophoblast cells, which was shown by enhanced proliferation and invasion, decreased ROS and lipid peroxide levels, and reduced glycolysis and mitochondrial dysfunction. Nox2 negatively correlated with MVD in PE placentas, and Nox2 knockdown restored ferroptosis-inhibited tube formation. Nox2 could interact with STAT3. Inhibiting Nox2 restored ferroptosis-induced alterations in the mRNA and protein levels of STAT3 and GPX4. SIGNIFICANCE: Nox2 may trigger ferroptosis through the STAT3/GPX4 pathway, subsequently leading to regulation of mitochondrial respiration, transition of glycolysis, and inhibition of placental angiogenesis. Therefore, targeted inhibition of Nox2 is expected to become a new therapeutic target for PE.