HTR-8/SVneo: A model for epithelial to mesenchymal transition in the human placenta

Phenylbutyric acid inhibits hypoxia-induced trophoblast apoptosis and autophagy in preeclampsia via the PERK/ATF-4/CHOP pathway

Preeclampsia (PE) is a common pregnancy complication with a high mortality rate. Abnormally activated endoplasmic reticulum stress (ERS) is believed to be responsible for the destruction of key placental cells-trophoblasts. Phenylbutyric acid (4-PBA), an ERS inhibitor, is involved in regulating the development of ERS-related diseases. At present, how 4-PBA affects trophoblasts and its mechanisms is still unclear. In this study, PE cell models were established by stimulating HTR-8/SVneo cells with hypoxia. To verify the underlying mechanisms of 4-PBA on PE, CCT020312, an activator of PERK, was also used. The results showed that 4-PBA restored hypoxia-induced trophoblast viability, inhibited HIF-1α protein expression, inflammation, and PERK/ATF-4/CHOP pathway. Hoechst 33342 staining and flow cytometry results confirmed that 4-PBA decreased hypoxia-induced apoptosis in trophoblasts. The results of the JC-1 analysis and apoptosis initiation enzyme activity assay also demonstrated that 4-PBA inhibited apoptosis related to the mitochondrial pathway. Furthermore, by detecting autophagy in trophoblasts, an increased number of autophagic vesicles, damaged mitochondria, enhanced dansylcadaverine fluorescence, enhanced levels of autophagy proteins Beclin-1, LC3II, and decreased p62 were seen in hypoxia-stimulated cells. These changes were reversed by 4-PBA. Furthermore, it was observed that CCT020312 reversed the effects of 4-PBA on the viability, apoptosis, and autophagosome number of hypoxia-induced trophoblasts. In summary, 4-PBA reduces autophagy and apoptosis via the PERK/ATF-4/CHOP pathway and mitochondrial pathway, thereby restoring the viability of hypoxic trophoblasts. These findings provide a solid evidence base for the use of 4-PBA in PE treatment and guide a new direction for improving the outcomes of patients with PE.

Cryptochrome 2 Suppresses Epithelial-Mesenchymal Transition by Promoting Trophoblastic Ferroptosis in Unexplained Recurrent Spontaneous Abortion

Unexplained recurrent spontaneous abortion (URSA) is a serious reproductive issue that affects women of childbearing age. Studies have shown a close association between disrupted circadian rhythm and impaired epithelial-mesenchymal transition (EMT) process in trophoblasts during URSA, although the underlying mechanism has not been elaborated. This study aims to investigate the regulatory relationship between circadian rhythm gene cryptochrome 2 (CRY2) and ferroptosis on the migratory ability of trophoblast cells. Cell proliferation experiments, wound healing assays, and expression of related markers were conducted to verify the EMT efforts. Trophoblastic ferroptosis was confirmed by the expressions of malondialdehyde, glutathione, mitochondrial membrane potential, divalent iron ions, and related genes. The results showed significant increased expression of CRY2 and decreased expression of brain and muscle ARNT-like protein 1 (BMAL1) in the URSA villous tissues, accompanied by iron-dependent oxidative changes and abnormal expression of ferroptosis-related proteins. It was observed that CRY2 and BMAL1 were co-localized and function as a feedback loop, which regulated the dynamic changes of EMT-related markers in trophoblast cells. CRY2 promoted trophoblastic ferroptosis, whereas BMAL1 had the opposite effect. Particularly, the ferroptosis inhibitor (ferrostatin-1) effectively reversed the trophoblastic ferroptosis and EMT inhibition caused by CRY2 overexpression. Collectively, these results suggest that CRY2 regulates trophoblastic ferroptosis and hinders cellular EMT and migratory ability by suppressing BMAL1 expression.

Deciphering the Epigenetic Landscape: Placental Development and Its Role in Pregnancy Outcomes

The placenta stands out as a unique, transitory, and multifaceted organ, essential to the optimal growth and maturation of the fetus. Functioning as a vital nexus between the maternal and fetal circulatory systems, it oversees the critical exchange of nutrients and waste. This exchange is facilitated by placental cells, known as trophoblasts, which adeptly invade and remodel uterine blood vessels. Deviations in placental development underpin a slew of pregnancy complications, notably fetal growth restriction (FGR), preeclampsia (PE), recurrent spontaneous abortions (RSA), and preterm birth. Central to placental function and development is epigenetic regulation. Despite its importance, the intricate mechanisms by which epigenetics influence the placenta are not entirely elucidated. Recently, the scientific community has turned its focus to parsing out the epigenetic alterations during placental development, such as variations in promoter DNA methylation, genomic imprints, and shifts in non-coding RNA expression. By establishing correlations between epigenetic shifts in the placenta and pregnancy complications, researchers are unearthing invaluable insights into the biology and pathophysiology of these conditions. This review seeks to synthesize the latest findings on placental epigenetic regulation, spotlighting its crucial role in shaping fetal growth trajectories and development. Through this lens, we underscore the overarching significance of the placenta in the larger narrative of gestational health.

Validation of the Sw71-spheroid model with primary trophoblast cells

PROBLEM

Human implantation is a limiting factor for the success of natural and IVF reproduction since about 60% of pregnancy losses occur in the peri-implantation period. The in vitro modeling of human implantation challenges the researchers in accurate recreation of the complex in vivo differentiation and function of human blastocyst in the peri-implantation period. In previous studies, we constructed Sw71-spheroid models, which like human blastocyst undergo compactization, attaches to the endometrial epithelium, invade, and migrate. The aim of this study was to validate the trophoblast Sw71-spheroid model with primary trophoblast cells, derived from healthy women in early pregnancy.

METHOD OF STUDY

We performed a direct comparison of Sw71-spheroid model with placenta-derived primary trophoblasts regarding their hybrid phenotype and HLA status, as well as the ability to generate spheroids able to migrate and invade. From the primary trophoblast cells, isolated by mild enzymatic treatment and Percoll gradient separation, were generated long-lived clones, which phenotype was assessed by FACS and immunocytochemistry.

RESULTS

Our results showed that cultured primary trophoblasts have the EVT phenotype (Vim+/CK7+/HLA-C+/HLA-G+), like Sw71 cells. In both 3D culture settings, we obtained stable, round-shaped, multilayered spheroids. Although constructed from the same number of cells, the primary trophoblast spheroids were smaller. The primary trophoblast spheroids migrate successfully, and in term of invasion are equally potent but less stable as compared to Sw71 spheroids.

CONCLUSIONS

The Sw71 cell line and cultured native trophoblast cells are interchangeable regarding their EVT phenotype (HLA-C+/HLA-G+/Vim+/CK7+). The blastocyst-like spheroids sourced by both types of cells differentiate in the same time frame and function similarly. We strongly advise the use of Sw71 spheroids as blastocyst surrogate for observation on trophectoderm differentiation and function during early human implantation.

Aspirin protects human trophoblast HTR-8/SVneo cells from H2O2-Induced oxidative stress via NADPH/ROS pathway

INTRODUCTION

Pre-eclampsia (PE) is a pregnancy complication that can lead to maternal, fetal, and neonatal deaths in clinical practice. Accumulation of trophoblastic reactive oxygen species (ROS), which could result in oxidative stress and cell apoptosis, is considered to play an important role in PE pathology. It has been reported that aspirin has a positive effect on PE treatment in high-risk pregnant women.

METHODS

In vitro, extravillous trophoblast cell line (HTR-8/SVneo) were treated with hydrogen peroxide (H2O2, 150 μM) after the presence of aspirin (90 and 120 μM) with or without GKT137831 (a Nox4 inhibitor, 20 μM). A series of experiments including CCK-8 assays, flow cytometry, biochemical testing, and Western Blotting etc. verified the protective effects and potential mechanisms of aspirin against oxidative stress-induced damage in PE.

RESULTS

Our results demonstrated that H2O2 induces oxidative stress and apoptosis in HTR8/SVneo cells. However, aspirin pretreatment rescue cell viability and reduce LDH activity of HTR-8/SVneo cells. Aspirin can suppress the ROS overproduction and MDA level while increase SOD content and CAT activity. In addition, aspirin pretreatment significantly alleviated cell apoptosis and suppressed the expression of Nox4 and its subunits (p22phox and p47phox) at protein and mRNA levels. The above results were more obvious after the combination of aspirin with GKT137831.

DISCUSSION

This study demonstrated that aspirin protects human trophoblasts against H2O2-induced oxidative stress and cell apoptosis via suppressing NADPH/ROS pathway. These findings provide novel insights for the application of aspirin as a protective and curative agent against PE.

The Gut Microbiota of Pregnant Rats Alleviates Fetal Growth Restriction by Inhibiting the TLR9/MyD88 Pathway

Fetal growth restriction (FGR) is a prevalent obstetric condition. This study aimed to investigate the role of Toll-like receptor 9 (TLR9) in regulating the inflammatory response and gut microbiota structure in FGR. An FGR animal model was established in rats, and ODN1668 and hydroxychloroquine (HCQ) were administered. Changes in gut microbiota structure were assessed using 16S rRNA sequencing, and fecal microbiota transplantation (FMT) was conducted. HTR-8/Svneo cells were treated with ODN1668 and HCQ to evaluate cell growth. Histopathological analysis was performed, and relative factor levels were measured. The results showed that FGR rats exhibited elevated levels of TLR9 and myeloid differentiating primary response gene 88 (MyD88). In vitro experiments demonstrated that TLR9 inhibited trophoblast cell proliferation and invasion. TLR9 upregulated lipopolysaccharide (LPS), LPS-binding protein (LBP), interleukin (IL)-1β and tumor necrosis factor (TNF)-α while downregulating IL-10. TLR9 activated the TARF3-TBK1-IRF3 signaling pathway. In vivo experiments showed HCQ reduced inflammation in FGR rats, and the relative cytokine expression followed a similar trend to that observed in vitro. TLR9 stimulated neutrophil activation. HCQ in FGR rats resulted in changes in the abundance of Eubacterium_coprostanoligenes_group at the family level and the abundance of Eubacterium_coprostanoligenes_group and Bacteroides at the genus level. TLR9 and associated inflammatory factors were correlated with Bacteroides, Prevotella, Streptococcus, and Prevotellaceae_Ga6A1_group. FMT from FGR rats interfered with the therapeutic effects of HCQ. In conclusion, our findings suggest that TLR9 regulates the inflammatory response and gut microbiota structure in FGR, providing new insights into the pathogenesis of FGR and suggesting potential therapeutic interventions.

Effects of a combination of cannabidiol and delta-9-tetrahydrocannabinol on key biological functions of HTR-8/SVneo extravillous trophoblast cells

In recent years, cannabis use has increased among pregnant women. In addition, the phytocannabinoids cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC) alone or in combination are being used for therapeutical applications. THC and CBD are able to cross the placenta and a lot remains unknown concerning their impact on angiogenesis and extravillous trophoblasts' (EVTs) migration and invasion, which are essential processes for placentation. Thus, in this study, the HTR-8/SVneo cell line was employed to evaluate the effects of CBD, THC and of their combination (1:1, 2 µM). Cannabinoids affected epithelial-mesenchymal transition, as showed by increased expression of the epithelial protein marker E-cadherin for CBD and CBD plus THC treatments, and decrease of mesenchymal intermediate filament vimentin for all treatments. The gene expression of the metalloproteinases MMP2 and MMP9, and of their inhibitors TIMP1 and TIMP2 was increased, except the latter for THC treatment. Moreover, CBD reduced cell migration and invasion, an effect that was enhanced by its combination with THC. CBD with or without THC also upregulated the gene expression of PGF, while the anti-angiogenic factor sFLT1 was increased for all treatments. VEGFA and FLT1 were not affected. Alone or combined CBD and THC also decreased tube segments' length. Additionally, ERK1/2 and STAT3 phosphorylation was increased in the CBD and CBD plus THC-treated cells, while THC only activated STAT3. AKT activation was only affected by CBD. This work demonstrates that the exposure to cannabinoid-based products containing CBD and/or THC, may interfere with key processes of EVTs differentiation. Therefore, crucial phases of placental development can be affected, compromising pregnancy success.

Decreased PPP1R3G in pre-eclampsia impairs human trophoblast invasion and migration via Akt/MMP-9 signaling pathway

Pre-eclampsia (PE) is a severe pregnancy complication characterized by impaired trophoblast invasion and spiral artery remodeling and can have serious consequences for both mother and child. Protein phosphatase 1 regulatory subunit 3G (PPP1R3G) is involved in numerous tumor-related biological processes. However, the biological action and underlying mechanisms of PPP1R3G in PE progression remain unclear. We used western blotting and immunohistochemistry to investigate PPP1R3G expression in gestational age-matched pre-eclamptic and normal placental tissues. After lentivirus transfection, wound-healing, Transwell, cell-counting kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), and TdT mediateddUTP Nick End Labeling (TUNEL) assays were used to assess trophoblast migration, invasion, proliferation, and apoptosis, respectively. The relative expression levels of PPP1R3G and the proteins involved in the Akt signaling pathway were determined using western blotting. The results showed that PPP1R3G levels were significantly lower in the placental tissues and GSE74341 microarray of the PE group than those of the healthy control group. We also found that neonatal weight and Apgar score were lower at birth, and peak systolic blood pressure and diastolic blood pressure were higher in the PE group than in the non-PE group. In addition, PPP1R3G knockdown decreased p-Akt/Akt expression and inhibited migration, invasion, and proliferation in HTR-8/SVneo trophoblasts but had no discernible effect on cell apoptosis. Furthermore, PPP1R3G positively regulated matrix metallopeptidase 9 (MMP-9), which was downregulated in placental tissues of pregnant women with PE. These results provided the first evidence that the reduced levels of PPP1R3G might contribute to PE by suppressing the invasion and migration of trophoblasts and targeting the Akt/MMP-9 signaling pathway.

Proposal of Model for Evaluation of Viral Kinetics of African/Asian/Brazilian-Zika virus Strains (Step Growth Curve) in Trophoblastic Cell Lines

The Zika virus (ZIKV) epidemic brought new discoveries regarding arboviruses, especially flaviviruses, as ZIKV was described as sexually and vertically transmitted. The latter shows severe consequences for the embryo/fetus, such as congenital microcephaly and deficiency of the neural system, currently known as Congenital ZIKV Syndrome (CZS). To better understand ZIKV dynamics in trophoblastic cells present in the first trimester of pregnancy (BeWo, HTR-8, and control cell HuH-7), an experiment of viral kinetics was performed for African MR766 low passage and Asian-Brazilian IEC ZIKV lineages. The results were described independently and demonstrated that the three placental cells lines are permissive and susceptible to ZIKV. We noticed cytopathic effects that are typical in in vitro viral infection in BeWo and HTR-8. Regarding kinetics, MR766lp showed peaks of viral loads in 24 and 48 hpi for all cell types tested, as well as marked cells death after peak production. On the other hand, the HTR-8 lineage inoculated with ZIKV-IEC exhibited increased viral production in 144 hpi, with a peak between 24 and 96 hpi. Furthermore, IEC had peak variations of viral production for BeWo in 144 hpi. Considering such in vitro results, the hypothesis that maternal fetal transmission is probably a way of virus transmission between the mother and the embryo/fetus is maintained.

Laminin switches terminal differentiation fate of human trophoblast stem cells under chemically defined culture conditions

Human trophoblast stem cells (hTSCs) have emerged as a powerful tool to model early placental development in vitro. Analogous to the epithelial cytotrophoblast in the placenta, hTSCs can differentiate into cells of the extravillous trophoblast (EVT) lineage or the multinucleate syncytiotrophoblast (STB). Here we present a chemically defined culture system for STB and EVT differentiation of hTSCs. Notably, in contrast to current approaches, we neither utilize forskolin for STB formation, nor transforming growth factor-beta (TGFβ) inhibitors or a passage step for EVT differentiation. Strikingly, presence of a single additional extracellular cue - laminin-111 - switched the terminal differentiation of hTSCs from STB to the EVT lineage under these conditions. In the absence of laminin-111, STB formation occurred, with cell fusion comparable to that obtained with differentiation mediated by forskolin; however, in the presence of laminin-111, hTSCs differentiated to the EVT lineage. Protein expression of nuclear HIF1α and HIF2α was upregulated during EVT differentiation mediated by laminin-111 exposure. A heterogeneous mixture of Notch1⁺ EVTs in colonies and HLA-G⁺ single cell EVTs were obtained without a passage step, reminiscent of heterogeneity in vivo. Further analysis showed that inhibition of TGFβ signaling affected both STB and EVT differentiation mediated by laminin-111 exposure. TGFβ inhibition during EVT differentiation resulted in decreased HLA-G expression and increased Notch1 expression. On the other hand, TGFβ inhibition prevented STB formation of hTSCs. The chemically defined culture system for hTSC differentiation established herein facilitates quantitative analysis of heterogeneity that arises during hTSC differentiation and will enable mechanistic studies in vitro.

Nickel nanoparticles exert cytotoxic effects on trophoblast HTR-8/SVneo cells possibly via Nrf2/MAPK/caspase 3 pathway

Nickel nanoparticles are widely used in the industry and may affect the reproductive system. The potential molecular mechanism of exposing the first-trimester trophoblast cell line (HTR-8/SVneo) to nickel nanoparticles remains unclear. Hence, the aim of this study was to investigate the in vitro cytotoxicity of Ni NPs on HTR-8/SVneo cells. HTR-8/SVneo cells were subjected to various concentrations (0, 2.5, 5, 7.5, 10, and 12.5 μg/cm²) of Ni NPs. The toxicity of the Ni NPs was evaluated in HTR-8/SVneo cells by measuring cell viability. The underlying mechanism of nickel nanoparticles toxicity to HTR-8/SVneo cells was determined by measuring the content of intracellular reactive oxygen species, mitochondrial membrane potential, and the rate of cell apoptosis and cell cycle, by measuring adenosine triphosphate levels, intracellular lipid peroxidation malondialdehyde, total superoxide dismutase, and CuZn/Mn-SOD activities, and by determining proteins related to Nrf2, MAPK, and Cytochrome c. Our results showed that the nickel nanoparticles treatment reduced the viability of HTR-8/SVneo cells, while it increased their oxidative stress and lowered their mitochondrial respiratory capacity. Additionally, the nickel nanoparticles treatment induced cell S-phase arrest and apoptosis. These molecular events may be linked to the oxidative stress-Nrf2 pathway/MAPK/Caspase 3 cascade. Thus, nickel nanoparticles exert cytotoxic effects on HTR-8/SVneo cells, which could affect the function of the placenta in human.

Characterization of Three-Dimensional Trophoblast Spheroids: An Alternative Model to Study the Physiological Properties of the Placental Unit

It was postulated that 3D cell culture models more accurately reflect the complex tissue physiology and morphology in comparison to 2D cell monolayers. Currently, there is a shortage of well-characterized and easily maintainable high-throughput experimental models of the human placenta. Here, we characterized three different 3D cultures (e.g., spheroids) derived from trophoblast cell lines and studied their functionality in comparison to primary fetal trophoblasts and placental tissue. The spheroid growth rates of JEG3, BeWo and HTR8/SVneo cell lines were similar among each other and were significantly larger in comparison to primary trophoblast spheroids. All spheroids exhibited migratory properties and shortest distances were registered for JEG3 spheroids. Even though all spheroids displayed invasive capabilities, only the invasive features of HTR8/SVneo spheroids resulted in specific branching. This was in agreement with the invasive properties of the spheroids obtained from primary trophoblasts. Human chorionic gonadotropin production was highest in JEG3 spheroids and only increased when stimulated with cAMP and forskolin in BeWo, but not HTR8/SVneo spheroids. The gene expression analysis confirmed that 3D trophoblast cell cultures and especially HTR8/SVneo spheroids showed considerable similarities with the gene expression profile of primary placental tissue. This study offers a broad characterization of 3D trophoblast spheroids that, in turn, can help in selecting the best model depending on the scientific question that needs to be answered.

Origination of LTR retroelement-derived NYNRIN coincides with therian placental emergence

The emergence of the placenta is a revolutionary event in the evolution of therian mammals, to which some LTR retroelement–derived genes, such as PEG10, RTL1, and syncytin, are known to contribute. However, therian genomes contain many more LTR retroelement–derived genes that may also have contributed to placental evolution. We conducted large-scale evolutionary genomic and transcriptomic analyses to comprehensively search for LTR retroelement–derived genes whose origination coincided with therian placental emergence and that became consistently expressed in therian placentae. We identified NYNRIN as another Ty3/Gypsy LTR retroelement–derived gene likely to contribute to placental emergence in the therian stem lineage. NYNRIN knockdown inhibited the invasion of HTR8/SVneo invasive-type trophoblasts, whereas the knockdown of its nonretroelement-derived homolog KHNYN did not. Functional enrichment analyses suggested that NYNRIN modulates trophoblast invasion by regulating epithelial-mesenchymal transition and extracellular matrix remodeling and that the ubiquitin-proteasome system is responsible for the functional differences between NYNRIN and KHNYN. These findings extend our knowledge of the roles of LTR retroelement–derived genes in the evolution of therian mammals.

[Talin1 is highly expressed in the fallopian tube and chorionic villi to promote trophoblast invasion in tubal pregnancy]

OBJECTIVE

To investigate the expression of Talin1 in the fallopian tube and chorionic villi in patients with tubal pregnancy and its role in regulating invasion and migration of trophoblasts.

METHODS

Immunohistochemistry and Western blotting were used to detect the localization and expression level of Talin1 in the fallopian tube and chorionic villi in patients with tubal pregnancy and in women with normal pregnancy. In the cell experiment, HTR-8/SVneo cells was transfected with Talin1 siRNA and the changes in cell invasion and migration were assessed using scratch assay and Transwell assay. The expressions of MMP-2, MMP-9, N-cadherin and Snail in the transfected cells were detected by qRT-PCR and Western blotting.

RESULTS

Positive expression of Talin1 was detected in both normal fallopian tube tissues and tissues from women tubal pregnancy, and its expression was localized mainly in the cytoplasm of cilia cells. The expression level of Talin1 was significantly higher in both the fallopian tube and chorionic villi in women with tubal pregnancy than in normal fallopian tube and chorionic villi samples (P < 0.01). In HTR-8/SVneo cells, transfection with Talin1 siRNA significantly inhibited cell invasion (P < 0.01) and migration (P < 0.05), down-regulated the expression of N-cadherin, MMP-2 and Snail (P < 0.05), and up-regulated the expression of MMP-9 in the cells (P < 0.05).

CONCLUSION

The expression of Talin1 in the fallopian tube and chorionic villi is significantly increased in women with tubal pregnancy, suggesting the association of Talin1-regulated trophoblast cell invasion with the occurrence of tubal pregnancy.

C1q/tumor necrosis factor related protein 6 (CTRP6) regulates the phenotypes of high glucose-induced gestational trophoblast cells via peroxisome proliferator-activated receptor gamma (PPARγ) signaling

Multiple studies have confirmed that adipokines are compactly relevant to insulin resistance and participate in the pathogenesis of gestational diabetes mellitus (GDM). This paper aimed to study the effects of C1q/tumor necrosis factor related protein (CTRP)6 on the phenotypes of trophoblast cells, covering cell proliferation, invasion and migration, and initially explore the mechanism. High glucose was used to induce trophoblast cells to establish an in vitro model. The expression levels of CTRP6 were firstly determined, and then the effects of CTRP6 knockdown on cell viability, apoptosis, migration and invasion were assessed using CCK8, TUNEL, wound healing, Transwell assays. Moreover, the role of peroxisome proliferator-activated receptor gamma (PPARγ), probable target of CTRP6, was evaluated through co-transfection with PPARγ overexpression vector. The results of the present study revealed that CTRP6 and PPARγ were both upregulated in high glucose-induced cells. And CTRP6 knockdown could significantly elevate the abilities of cell viability, migration and invasion, and avoid cell apoptosis. In addition, PPARγ overexpression was found to restrain the protective effects of CTRP6 knockdown on the above aspects, indicating CTRP6 played a role in trophoblast cells via inhibiting PPARγ expression. In conclusion, CTRP6 regulated the viability, migration and invasion of high glucose-induced gestational trophoblast cells through PPARγ signaling.

CXCL5 Downregulation in Villous Tissue Is Correlated With Recurrent Spontaneous Abortion

Recurrent spontaneous abortion (RSA) affects 5% of childbearing-age women worldwide. Inadequate trophoblast invasion is one of the main reasons for the development of RSA; however, the underlying molecular mechanisms for RSA have not been fully understood, and further explanation is urgently needed. C-X-C motif chemokine ligand 5 (CXCL5) is reported to contribute to the invasion of cancer cells, and its aberrant expression is associated with the cellular process of tumor pathology. Considering the high behavioral similarity between trophoblast cells and cancer cells, we hypothesized that CXCL5 may influence trophoblast invasion, and its expression levels in villous tissue may be correlated with RSA. In this study, we firstly investigated the CXCL5 expression in placental villous tissues of 15 RSA patients and 13 control patients, and the results showed that CXCL5 levels were significantly lower in villous tissue from RSA patients than those of the controls. Further in vitro experiments presented that recombinant human CXCL5 can enhance trophoblast migration, invasion, and epithelial-to-mesenchymal transition (EMT) process. We also demonstrated that CXCL5 exerted these effects on trophoblast cells through PI3K/AKT/ERK1/2 signaling pathway. In conclusion, these data indicate that CXCL5 downregulation in human villous tissue is correlated with RSA. Additionally, we found that estrogen, progesterone, human chorionic gonadotropin, and decidual stromal cells can regulate CXCL5 and chemokine receptor 2 (CXCR2) expression of trophoblast in a cell manner.

Could the Human Endogenous Retrovirus-Derived Syncytialization Inhibitor, Suppressyn, Limit Heterotypic Cell Fusion Events in the Decidua?

Proper placental development relies on tightly regulated trophoblast differentiation and interaction with maternal cells. Human endogenous retroviruses (HERVs) play an integral role in modulating cell fusion events in the trophoblast cells of the developing placenta. Syncytin-1 (ERVW-1) and its receptor, solute-linked carrier family A member 5 (SLC1A5/ASCT2), promote fusion of cytotrophoblast (CTB) cells to generate the multi-nucleated syncytiotrophoblast (STB) layer which is in direct contact with maternal blood. Another HERV-derived protein known as Suppressyn (ERVH48-1/SUPYN) is implicated in anti-fusogenic events as it shares the common receptor with ERVW-1. Here, we explore primary tissue and publicly available datasets to determine the distribution of ERVW-1, ERVH48-1 and SLC1A5 expression at the maternal-fetal interface. While SLC1A5 is broadly expressed in placental and decidual cell types, ERVW-1 and ERVH48-1 are confined to trophoblast cell types. ERVH48-1 displays higher expression levels in CTB and extravillous trophoblast, than in STB, while ERVW-1 is generally highest in STB. We have demonstrated through gene targeting studies that suppressyn has the ability to prevent ERVW-1-induced fusion events in co-culture models of trophoblast cell/maternal endometrial cell interactions. These findings suggest that differential HERV expression is vital to control fusion and anti-fusogenic events in the placenta and consequently, any imbalance or dysregulation in HERV expression may contribute to adverse pregnancy outcomes.

Iodothyronine deiodinase 2 (DiO2) regulates trophoblast cell line cycle, invasion and apoptosis; and its downregulation is associated with early recurrent miscarriage

INTRODUCTION

Trophoblast development is a crucial event in placentation and pregnancy complications but its underlying mechanisms remain unclear. Thus, we aimed at investigating the role of DiO2 in trophoblast cell line decisions and assessing its placental villous expression in early recurrent miscarriage (ERM) patients.

METHODS

The placental villous expression of DiO2 was determined with immunofluorescence. Cell proliferation was measured with the CCK8 kit while cell-cycle and apoptosis were studied with flow-cytometry. Cell migration and invasion were measured with wound-healing and transwell assays, respectively. Gene expression was then assessed with RT-qPCR and western blotting.

RESULTS

DiO2 is expressed in the CTB, PCT, DCT and STB of the placenta. Its overexpression arrested trophoblast cell line proliferation at the G1 phase of the cell-cycle by downregulating cyclin-D1 and PCNA, while promoting apoptosis via increased caspase-3 activity and inhibition of the AKT and ERK1/2 signaling pathways. Also, it augmented trophoblast cell line migration and invasion via the upregulation of N-cadherin, vimentin, fascin-1, twist-1 and other epithelial-mesenchymal transition genes. DiO2 knockdown elicited the opposite effects. Surprisingly, each of these effects of DiO2 manipulation was not mediated by thyroid hormone metabolism. Assessment of the ERM placental villi revealed a downregulation of DiO2, N-cadherin, vimentin, fascin-1 and twist-1. The expression of E-cadherin remained unchanged in these placentae.

DISCUSSION

During placentation, DiO2 may inhibit trophoblast proliferation while facilitating their differentiation into an invasive phenotype; and that its downregulation may contribute to the shallow trophoblast invasion that precedes ERM. Hence, DiO2 is a potential therapeutic target against ERM.

Comparing effects and action mechanisms of BPA and BPS on HTR-8/SVneo placental cells

Bisphenol A (BPA) is one of the most investigated compound as a suspected endocrine disrupting chemical. It has been found at nM concentrations in the maternal serum, cord serum, and amniotic fluid and also permeates placental tissues. Attempts are being made to replace BPA with the analog Bisphenol S (BPS). Also BPS was found in maternal and umbilical cord serum, and urine samples from a large population of pregnant women. A few studies investigated BPA impact on the placentation process, and even less are available for BPS. This work aimed to elucidate and compare the effects of BPA and BPS on physiological functions of HTR-8/SVneo cells, derived from extravillous trophoblast of first-trimester pregnancy. Proliferation and migration ability of trophoblast cells were assessed in vitro after exposure to BPA or BPS (10-13 - 10-3 M). Further, induction of the inflammatory response by the bisphenols was studied. To provide insight into the molecular pathways implicated in the responses, experiments were carried out in the presence or absence of tamoxifen as estrogen receptors (ERs) blocker, and U0126 as ERK1/2 phosphorylation inhibitor. Data indicate that BPA significantly affects both proliferation and migration of HTR-8/SVneo cells, through ER and ERK1/2 mediated processes. Differently, BPS only acts on proliferation, again through ER and ERK1/2 mediated processes. BPS, but not BPA, induces secretion of interleukins 6 and 8. Such effect is inhibited by blocking ERK1/2 phosphorylation. To the best of our knowledge, these are the first data showing that BPS affects trophoblast functions through ER/MAPK modulation.

Aspirin facilitates trophoblast invasion and epithelial-mesenchymal transition by regulating the miR-200-ZEB1 axis in preeclampsia

Preeclampsia is a severe gestational hypertensive disorder that occurs after 20 weeks' of gestation. It involves several maternal systems, such as cardiovascular, renal, coagulatory systems, and poses a major threat to the maternal and fetal health. Recent clinical evidence showed that aspirin is an effective preventative treatment for reducing the incidence of premature preeclampsia among high-risk pregnant women, however, the mechanism of drug action is not clear. miR-200 family has been shown to be associated with preeclampsia and upregulated in the plasma and placenta of preeclamptic patients. Here we revealed that miR-200 family inhibited trophoblast invasion and epithelial-mesenchymal transition (EMT) process by stimulating epithelial marker expression (E-cadherin and ZO-1) and repressing mesenchymal marker expression (ZEB1 and TGFβ1). Similarly, EMT markers in the placenta of preeclamptic patients showed higher E-cadherin and lower ZEB1 and TGF-β1 protein expression. Moreover, aspirin was shown to suppress miR-200 family and these miR-200 family-mediated cell functions, including cell invasion and EMT changes, were completely reversed. In conclusion, this study demonstrates the effect of miR-200 family on trophoblast invasion and EMT. For the first time, aspirin was shown to fully reverse miR-200-mediated trophoblast biology and act through the network signaling of TGF-β1/ZEB1/miR-200. These results provide a plausible mechanism explaining aspirin's effect on preeclampsia prevention and a therapeutic target for disease intervention.

Heme Oxygenase-1 Induction in Human BeWo Trophoblast Cells Decreases Toxoplasma gondii Proliferation in Association With the Upregulation of p38 MAPK Phosphorylation and IL-6 Production

Heme oxygenase-1 (HO-1) enzyme exerts beneficial effects at the maternal-fetal interface, especially in trophoblasts, being involved in survival and maturation of these cell phenotypes. Trophoblast cells play essential roles throughout pregnancy, being the gateway for pathogens vertically transmitted, such as Toxoplasma gondii. It was previously shown that HO-1 activity was involved in the control of T. gondii infection in vivo; however, its contribution in trophoblast cells during T. gondii infection, remain undefined. Thus, this study aimed to investigate the influence of HO-1 in T. gondii-infected BeWo and HTR-8/SVneo human trophoblast cells. For this purpose, trophoblast cells were infected and the HO-1 expression was evaluated. T. gondii-infected BeWo cells were treated with hemin or CoPPIX, as inducers of HO-1, or with bilirubin, an end-product of HO-1, and the parasitism was quantified. The involvement of p38 MAPK, a regulator of HO-1, and the cytokine production, were also evaluated. It was found that T. gondii decreased the HO-1 expression in BeWo but not in HTR-8/SVneo cells. When treated with the HO-1 inducers or bilirubin, BeWo cells reduced the parasite proliferation. T. gondii also decreased the p38 MAPK phosphorylation in BeWo cells; on the other hand, HO-1 induction sustained its activation. Finally, the IL-6 production was upregulated by HO-1 induction in T. gondii-infected cells, which was associated with the control of infection.

Integrin β1 regulates proliferation, apoptosis, and migration of trophoblasts through activation of phosphoinositide 3 kinase/protein kinase B signaling

AIMS

Abnormal trophoblast invasion is one of the onsets of preeclampsia (PE). Studies found that integrin β1 (ITGB1) is closely related to PE, but the role of ITGB1 in the progression of trophoblast remained unclear. Therefore, we studied the functional role of ITGB1 in PE and its effects on trophoblast.

METHODS

ITGB1 expression in placenta tissues was determined by quantitative real-time polymerase chain reaction (qRT-PCR). The effects of transfection on HTR-8/SVneo cells were analyzed by qRT-PCR and western blotting. After cell transfection, colony formation assay, flow cytometry, wound healing assay, and transwell assay were performed to detect cell proliferation, apoptosis, migration, and invasion. Western blotting assay was used for determining phosphoinositide 3 kinase (PI3K) and protein kinase B (Akt) signaling pathway. After inhibiting PI3K/Akt pathway, apoptosis-regulated proteins were detected by western blotting, and the effects of inhibitor on the migration and invasion changes were examined.

RESULTS

ITGB1 was downregulated in placenta tissues from PE patients, as compared with normal. ITGB1 overexpression in HTR-8/SVneo cells enhanced cell proliferation, migration, and invasion, reduced cell apoptosis, and improved phosphorylation of PI3K and Akt. However, ITGB1 depletion resulted in an opposite effect to its overexpression. Inhibition of PI3K/Akt pathway completely blocked the effect of ITGB1 overexpression on cells, because we observed that apoptosis-regulated proteins were highly upregulated, and that cell migration and invasion were reduced.

CONCLUSION

ITGB1 regulated HTR-8/SVneo cell progression by activation of the PI3K/Akt pathway.

A crossroad between placental and tumor biology: What have we learnt?

Placenta in certain species including the human has evolved as a highly invasive tumor-like organ invading the uterus aned its vasculature to derive oxygen and nutrients for the fetus and exchange waste products. While several excellent reviews have been written comparing hemochorial placentation with tumors, no comprehensive review is available dealing with mechanistic insights into what makes them different, and what tumor biologists can learn from placental biologists, and vice versa. In this review, we analyze the structure-function relationship of the human placenta, emphasizing the functional need of the spatio-temporally orchestrated trophoblast invasiveness for fetal development and growth, and pathological consequences of aberrant invasiveness for fetal and maternal health. We then analyze similarities and differences between the placenta and invasive tumors in terms of hallmarks of cancer, some key molecules regulating their invasive functions, and how placental cancers (choriocarcinomas) or other cancers become refractory or even addicted to these invasion-restraining molecules. We cite in vitro models of human trophoblast and choriocarcinoma cell lines utilized to study mechanisms in normal placental development as well as those responsible for tumor progression. We discuss the pathobiology of hyper-invasive placentas and show thattrophoblastic neoplasias are a unique and heterogeneous class of tumors. We delve into the questions as to why metastasis from other organs rarely occurs at the placental site and whether pregnancy makes the mother more or less vulnerable to cancer-related morbidity/mortality. We attempt to compare trophoblast stem cells and cancer stem cells. Finally, we leave the readers with some thoughts as foods of future investigations.

Conditioned medium from primary cytotrophoblasts, primary placenta-derived mesenchymal stem cells, or sub-cultured placental tissue promoted HUVEC angiogenesis in vitro

Background

As a large capillary network, the human placenta plays an important role throughout pregnancy. Placental vascular development is complex and delicate and involves many types of placental cells, such as trophoblasts, and mesenchymal stem cells. There has been no systematic, comparative study on the roles of these two groups of placental cells and the whole placental tissue in the placental angiogenesis. In this study, primary cytotrophoblasts (CTBs) from early pregnancy and primary human placenta-derived mesenchymal stem cells (hPDMSCs) from different stages of pregnancy were selected as the cell research objects, and full-term placental tissue was selected as the tissue research object to detect the effects of their conditioned medium (CM) on human umbilical vein endothelial cell (HUVEC) angiogenesis.

Methods

We successfully isolated primary hPDMSCs and CTBs, collected CM from these placental cells and sub-cultured placental tissue, and then evaluated the effects of the CM on a series of angiogenic processes in HUVECs in vitro. Furthermore, we measured the levels of angiogenic factors in the CM of placental cells or tissue by an angiogenesis antibody array.

Results

The results showed that not only placental cells but also sub-cultured placental tissue, to some extent, promoted HUVEC angiogenesis in vitro by promoting proliferation, adhesion, migration, invasion, and tube formation. We also found that primary placental cells in early pregnancy, whether CTBs or hPDMSCs, played more significant roles than those in full-term pregnancy. Placental cell-derived CM collected at 24 h or 48 h had the best effect, and sub-cultured placental tissue-derived CM collected at 7 days had the best effect among all the different time points. The semiquantitative angiogenesis antibody array showed that 18 of the 43 angiogenic factors had obvious spots in placental cell-derived CM or sub-cultured placental tissue-derived CM, and the levels of 5 factors (including CXCL-5, GRO, IL-6, IL-8, and MCP-1) were the highest in sub-cultured placental tissue-derived CM.

Conclusions

CM obtained from placental cells (primary CTBs or hPDMSCs) or sub-cultured placental tissue contained proangiogenic factors and promoted HUVEC angiogenesis in vitro. Therefore, our research is helpful to better understand placental angiogenesis regulation and provides theoretical support for the clinical application of placental components, especially sub-cultured placental tissue-derived CM, in vascular tissue engineering and clinical treatments.

A 3-dimensional microfluidic platform for modeling human extravillous trophoblast invasion and toxicological screening

Placental trophoblast cells invasion into the maternal uterus is an essential and complex event in the formation of the maternal-fetal interface. Commonly used two-dimensional (2D) cell invasion tools do not accurately represent the in vivo cell invasion microenvironment. Three-dimensional (3D) silicone polymer polydimethylsiloxane (PDMS) microfluidic platforms are an emerging technology in developing organ-on-a-chip models. Here, we present a placenta-on-a-chip platform that enables the evaluation of trophoblast invasion with intraluminal flow within an engineered PDMS 3D microfluidic chip. This platform reproduces key elements of the placental microenvironment, including endothelial and trophoblast cells, layered with an extracellular matrix, and incorporates dynamic medium flow while allowing for real-time monitoring, imaging, evaluation of trophoblast cell invasion, and heterocellular cell-to-cell interactions. Coupled with fluorescent cell tagging and flow cytometry, this platform also allows collection of the invasive cells. This will help our understanding of pathways that regulate trophoblast cell invasion and may prove important for toxicological screening of exposures that interfere with invasiveness in a complex organ such as the placenta.

Zika virus infection induces endoplasmic reticulum stress and apoptosis in placental trophoblasts

Zika virus (ZIKV) infection to a pregnant woman can be vertically transmitted to the fetus via the placenta leading to Congenital Zika syndrome. This is characterized by microcephaly, retinal defects, and intrauterine growth retardation. ZIKV induces placental trophoblast apoptosis leading to severe abnormalities in the growth and development of the fetus. However, the molecular mechanism behind ZIKV-induced apoptosis in placental trophoblasts remains unclear. We hypothesize that ZIKV infection induces endoplasmic reticulum (ER) stress in the trophoblasts, and sustained ER stress results in apoptosis. HTR-8 (HTR-8/SVneo), a human normal immortalized trophoblast cell and human choriocarcinoma-derived cell lines (JEG-3 and JAR) were infected with ZIKV. Biochemical and structural markers of apoptosis like caspase 3/7 activity and percent apoptotic nuclear morphological changes, respectively were assessed. ZIKV infection in placental trophoblasts showed an increase in the levels of CHOP mRNA and protein expression, which is an inducer of apoptosis. Next, we also observed increased levels of ER stress markers such as phosphorylated forms of inositol-requiring transmembrane kinase/endoribonuclease 1α (P-IRE1α), and its downstream target, the spliced form of XBP1 mRNA, phosphorylated eukaryotic initiation factor 2α (P-eIF2α), and activation of cJun N-terminal Kinase (JNK) and p38 mitogen activated protein kinase (MAPK) after 16-24 h of ZIKV infection in trophoblasts. Inhibition of JNK or pan-caspases using small molecule inhibitors significantly prevented ZIKV-induced apoptosis in trophoblasts. Further, JNK inhibition also reduced XBP1 mRNA splicing and viral E protein staining in ZIKV infected cells. In conclusion, the mechanism of ZIKV-induced placental trophoblast apoptosis involves the activation of ER stress and JNK activation, and the inhibition of JNK dramatically prevents ZIKV-induced trophoblast apoptosis.

miR-193a-3p Mediates Placenta Accreta Spectrum Development by Targeting EFNB2 via Epithelial-Mesenchymal Transition Pathway Under Decidua Defect Conditions

Objective: To clarify the role of microRNA-193a-3p (miR-193a-3p) in the pathogenesis of placenta accreta spectrum.

Methods: The placental tissue expression levels of miR-193a-3p and Ephrin-B2 (EFNB2) were compared between a placenta accreta spectrum group and a control group. Transwell migration and invasion assays were used to verify the effect of miR-193a-3p and EFNB2 on HTR-8/SVneo cells cultured in human endometrial stromal cell (hESC)-conditioned medium. Epithelial-mesenchymal transition (EMT)-related proteins were examined by western blotting to establish whether the EMT pathway was altered in placenta accreta spectrum. To determine whether EFNB2 is a target gene of miR-193a-3p, luciferase activity assays were performed.

Results: miR-193a-3p was upregulated but EFNB2 downregulated in the placenta accreta spectrum group and EFNB2 was a direct target of miR-193a-3p. Overexpression or inhibition of miR-193a-3p revealed that miR-193a-3p promoted the migration and invasion of HTR-8/SVneo cells cultured in hESC-conditioned medium. Furthermore, EMT was induced, as shown by increased N-cadherin, vimentin, MMP2, and MMP9 and decreased E-cadherin in the placenta accreta spectrum group and in HTR-8/SVneo cells transfected with miR-193a-3p mimics or si-EFNB2. The negative effect of miR-193a-3p inhibitor was reversed by co-transfection with si-EFNB2 in function studies and in analyses of EMT-related proteins in vitro.

Conclusion: miR-193a-3p which upregulated in placenta accreta spectrum group increases HTR-8/SVneo cell migration and invasion by targeting EFNB2 via the EMT pathway under decidua defect conditions to lead to placenta accreta spectrum.

Aberrantly Expressed Non-Coding RNAs in the Placenta and Their Role in the Pathophysiology of Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM), one of the most common complications during pregnancy, is associated with a high risk of short- and long-term adverse effects on the mother and offspring. Placenta-derived hormones and cytokines aggravate maternal insulin resistance (IR) during pregnancy, which in turn contribute to GDM. The hyperglycemia and IR in GDM result in aberrant placental structure and function adversely affecting fetal growth and well-being. Therefore, it is reasonable to assume that structural and functional alterations in the placenta contribute to the pathogenesis of GDM and GDM-related complications. Increasing evidence suggests that multiple non-coding RNAs (ncRNAs), including microRNAs, long non-coding RNAs, and circular RNAs, are dysregulated in placentas of patients with GDM and linked to abnormal placental structure, metabolism, and function. Manipulation of ncRNA expression led to some key pathophysiological features of GDM, such as trophoblast dysfunction, changes in intracellular glucose metabolism, and inflammation. Moreover, placenta-specific ncRNAs may be potential diagnostic biomarkers and even therapeutic targets for GDM. This review summarizes data published on the involvement of aberrantly expressed placental ncRNAs in GDM and provides information on their role in the pathogenesis of GDM and GDM-associated complications.

Anti-Tumor Effects of Biomimetic Sulfated Glycosaminoglycans on Lung Adenocarcinoma Cells in 2D and 3D In Vitro Models

Lung cancer development relies on cell proliferation and migration, which in turn requires interaction with extracellular matrix (ECM) components such as glycosaminoglycans (GAGs). The mechanisms through which GAGs regulate cancer cell functions are not fully understood but they are, in part, mediated by controlled interactions with cytokines and growth factors (GFs). In order to mechanistically understand the effect of the degree of sulfation (DS) of GAGs on lung adenocarcinoma (LUAD) cells, we synthesized sulfated alginate (AlgSulf) as sulfated GAG mimics with DS = 0.0, 0.8, 2.0, and 2.7. Human (H1792) and mouse (MDA-F471) LUAD cell lines were treated with AlgSulf of various DSs at two concentrations 10 and 100 µg/mL and their anti-tumor properties were assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), trypan blue exclusion, and wound healing assays for 2D models and sphere formation assay for the 3D model. The proliferation and number of live MDA-F471 cells at the concentration of 100 µg/mL decreased significantly with the increase in the DS of biomimetic GAGs. In addition, the increase in the DS of biomimetic GAGs decreased cell migration (p < 0.001 for DS = 2.0 and 2.7 compared to control) and decreased the diameter and number of spheres formed (p < 0.001). The increased DS of biomimetic GAGs attenuated the expression of cancer stem cell (CSC)/progenitor markers in the 3D cultures. In conclusion, GAG-mimetic AlgSulf with increased DS exhibit enhanced anti-proliferative and migratory properties while also reducing growth of KRAS-mutant LUAD spheres in vitro. We suggest that these anti-tumor effects by GAG-mimetic AlgSulf are possibly due to differential binding to GFs and consequential decreased cell stemness. AlgSulf may be suitable for applications in cancer therapy after further in vivo validation.