A unique co-culture model for fundamental and applied studies of human fetoplacental steroidogenesis and interference by environmental chemicals

Establishment of a 3D multicellular placental microtissues for investigating the effect of antidepressant vortioxetine

The placenta is a unique organ with an active metabolism and dynamically changing physiology throughout pregnancy. It is difficult to elucidate the structure of cell-cell and cell-extracellular matrix interactions of the placenta in in vivo studies due to interspecies differences and ethical constraints. In this study, human umbilical cord vein cells (HUVEC) and human placental choriocarcinoma cells (BeWo) were co-cultured for the first time to form spheroids (microtissues) on a three-dimensional (3D) Petri Dish® mold and compared with a traditional two-dimensional (2D) system. Vortioxetine is an antidepressant with a lack of literature on its use in pregnancy in established cultures, the toxicity of vortioxetine was studied to investigate the response of spheroids representing placental tissue. Spheroids were characterised by morphology and exposed to vortioxetine. Cell viability and barrier integrity were then measured. Intercellular junctions and the localisation of serotonin transporter (SERT) proteins were demonstrated by immunofluorescence (IF) staining in BeWo cells. Human chorionic gonadotropin (beta-hCG) hormone levels were also measured. In the 3D system, cell viability and hormone production were higher than in the 2D system. It was observed that the barrier structure was impaired, the structure of intracellular skeletal elements was altered and SERT expression decreased depending on vortioxetine exposure. These results demonstrate that the multicellular microtissue placenta model can be used to obtain results that more closely resemble in vivo toxicity studies of various xenobiotics than other 2D and mono-culture spheroid models in the literature. It also describes the use of 3D models for soft tissues other than the placenta.

Decamethylcyclopentasiloxane affects estradiol production in female rats but not H295R cells

Sex hormones, such as androgens and estrogens, are predominantly produced in the gonads (ovaries and testes) and adrenal cortex. Endocrine-disrupting chemicals (EDCs) are substances that mimic, block, or interfere with hormones in the endocrine systems of humans and organisms. EDCs mainly act via nuclear receptors and steroidogenesis-related enzymes. In the OECD conceptual framework for testing and assessment of EDCs, several well-known assays are used to identify the potential disruption of nuclear receptors both in vivo and in vitro, whereas the H295R steroidogenesis assay is the only assay that detects the disruption of steroidogenesis. Forskolin and prochloraz are often used as positive controls in the H295R steroidogenesis assay. Decamethylcyclopentasiloxane (D5) was suspected one of EDCs, but the effects of D5 on steroidogenesis remain unclear. To establish a short-term in vivo screening method that detects the disruption of steroidogenesis, rats in the present study were fed a diet containing forskolin, prochloraz, or D5 for 14 days. Forskolin increased plasma levels of 17β-estradiol (E2) and testosterone as well as the mRNA level of Cyp19 in both the adrenal glands and ovaries. Prochloraz induced the loss of cyclicity in the sexual cycle and decreased plasma levels of E2 and testosterone. D5 increased E2 levels and shortened the estrous cycle in a dose-dependent manner; however, potential endocrine disruption was not detected in the H295R steroidogenesis assay. These results demonstrate the importance of comprehensively assessing the endocrine-disrupting effects of chemicals on steroidogenesis in vivo.

Experimental human placental models for studying uptake, transport and toxicity of micro- and nanoplastics

Micro- and nanoplastics (MNPs) are ubiquitous in the environment and have recently been found in human lungs, blood and placenta. However, data on the possible effects of MNPs on human health is extremely scarce. The potential toxicity of MNPs during pregnancy, a period of increased susceptibility to environmental insults, is of particular concern. The placenta provides a unique interface between maternal and fetal circulation which is essential for in utero survival and healthy pregnancy. Placental toxicokinetics and toxicity of MNPs are still largely unexplored and the limited studies performed up to now focus mainly on polystyrene particles. Practical and ethical considerations limit research options in humans, and extrapolation from animal studies is challenging due to marked differences between species. Nevertheless, diverse in vitro and ex vivo human placental models exist e.g., plasma membrane vesicles, mono-culture and co-culture of placental cells, placenta-on-a-chip, villous tissue explants, and placental perfusion that can be used to advance this research area. The objective of this concise review is to recapitulate different human placental models, summarize the current understanding of placental uptake, transport and toxicity of MNPs and define knowledge gaps. Moreover, we provide perspectives for future research urgently needed to assess the potential hazards and risks of MNP exposure to maternal and fetal health.

Phthalate Exposures and Placental Health in Animal Models and Humans: A Systematic Review

Phthalates are ubiquitous compounds known to leach from the plastic products that contain them. Due to their endocrine-disrupting properties, a wide range of studies have elucidated their effects on reproduction, metabolism, neurodevelopment, and growth. Additionally, their impacts during pregnancy and on the developing fetus have been extensively studied. Most recently, there has been interest in the impacts of phthalates on the placenta, a transient major endocrine organ critical to maintenance of the uterine environment and fetal development. Phthalate-induced changes in placental structure and function may have significant impacts on the course of pregnancy and ultimately, child health. Prior reviews have described the literature on phthalates and placental health; however to date, there has been no comprehensive, systematic review on this topic. Here, we review 35 papers (24 human and 11 animal studies) and summarize phthalate exposures in relation to an extensive set of placental measures. Phthalate-related alterations were reported for placental morphology, hormone production, vascularization, histopathology, and gene/protein expression. The most consistent changes were observed in vascular and morphologic endpoints, including cell composition. These changes have implications for pregnancy complications such as preterm birth and intrauterine growth restriction as well as potential ramifications for children's health. This comprehensive review of the literature, including common sources of bias, will inform the future work in this rapidly expanding field.

Transcriptomic and targeted metabolomic analysis revealed the toxic effects of prochloraz on larval zebrafish

Prochloraz (PCZ), an imidazole fungicide, has been extensively used in horticulture and agriculture to protect against pests and diseases. To investigate the potential toxicity of PCZ on aquatic organisms, larval zebrafish, as a model, were exposed to a series of concentrations (0, 20, 100, and 500 μg/L) of PCZ for 7 days. With transcriptomic analysis, we found that exposure to high dose PCZ could produce 76 downregulated and 345 upregulated differential expression genes (DEGs). Bioinformatics analysis revealed that most of the DEGs were characterized in the pathways of glycolipid metabolism, amino acid metabolism and oxidative stress in larval zebrafish. Targeted metabolomic analysis was conducted to verify the effects of PCZ on the levels of acyl-carnitines and some amino acids in larval zebrafish. In addition, biochemical indicators related to glycolipid metabolism were affected obviously, manifested as elevated triglyceride (TG) levels and decreased glucose (Glu) levels in whole larvae. The expression levels of genes associated with glycolipid metabolism were affected in larvae after exposure to PCZ (PK, GK, PEPckc, SREBP, ACO). Interestingly, we further confirmed that PCZ could induce oxidative stress by the changing enzyme activities (T-GSH, GSSG) and upregulating several related genes levels in larval zebrafish. Generally, our results revealed that the endpoints related to glycolipid metabolism, amino acid metabolism and oxidative stress were influenced by PCZ in larval zebrafish.

Towards regulation of Endocrine Disrupting chemicals (EDCs) in water resources using bioassays - A guide to developing a testing strategy

Endocrine disrupting chemicals (EDCs) are found in every environmental medium and are chemically diverse. Their presence in water resources can negatively impact the health of both human and wildlife. Currently, there are no mandatory screening mandates or regulations for EDC levels in complex water samples globally. Bioassays, which allow quantifying in vivo or in vitro biological effects of chemicals are used commonly to assess acute toxicity in water. The existing OECD framework to identify single-compound EDCs offers a set of bioassays that are validated for the Estrogen-, Androgen-, and Thyroid hormones, and for Steroidogenesis pathways (EATS). In this review, we discussed bioassays that could be potentially used to screen EDCs in water resources, including in vivo and in vitro bioassays using invertebrates, fish, amphibians, and/or mammalians species. Strengths and weaknesses of samples preparation for complex water samples are discussed. We also review how to calculate the Effect-Based Trigger values, which could serve as thresholds to determine if a given water sample poses a risk based on existing quality standards. This work aims to assist governments and regulatory agencies in developing a testing strategy towards regulation of EDCs in water resources worldwide. The main recommendations include 1) opting for internationally validated cell reporter in vitro bioassays to reduce animal use & cost; 2) testing for cell viability (a critical parameter) when using in vitro bioassays; and 3) evaluating the recovery of the water sample preparation method selected. This review also highlights future research avenues for the EDC screening revolution (e.g., 3D tissue culture, transgenic animals, OMICs, and Adverse Outcome Pathways (AOPs)).

The E-Morph Assay: Identification and characterization of environmental chemicals with estrogenic activity based on quantitative changes in cell-cell contact organization of breast cancer cells

Adverse health effects that are caused by endocrine disrupting chemicals (EDCs) in the environment, food or consumer products are of high public concern. The identification and characterization of EDCs including substances with estrogenic activity still necessitates the use of animal testing as most of the approved alternative test methods only address single mechanistic events of endocrine activity. Therefore, novel human-relevant in vitro assays covering more complex functional endpoints of adversity, including hormone-related tumor formation and progression, are needed. This study describes the development and evaluation of a novel high-throughput screening-compatible assay called "E-Morph Assay". This image-based phenotypic screening assay facilitates robust predictions of the estrogenic potential of environmental chemicals using quantitative changes in the cell-cell contact morphology of human breast cancer cells as a novel functional endpoint. Based on a classification model, which was developed using six reference substances with known estrogenic activity, the E-Morph Assay correctly classified an additional set of 11 reference chemicals commonly used in OECD Test Guidelines and the U.S. EPA ToxCast program. For each of the tested substances, a relative ER bioactivity score was derived that allowed their grouping into four main categories of estrogenic activity, i.e. 'strong' (>0.9; four substances, i.e. natural hormones or pharmaceutical products), 'moderate' (0.9-0.6; six substances, i.e. phytoestrogens and Bisphenol AF), 'weak' (<0.6; three substances, i.e Bisphenol S, B, and A), and 'negative' (0.0; four substances). The E-Morph Assay considerably expands the portfolio of test methods providing the possibility to characterize the influence of environmental chemicals on estrogen-dependent tumor progression.

EVs Containing Host Restriction Factor IFITM3 Inhibited ZIKV Infection of Fetuses in Pregnant Mice through Trans-placenta Delivery

Zika virus (ZIKV) infection can lead to neurological complications and fetal defects, and it has attracted global public health concerns. Effective treatment for ZIKV infection remains elusive, and a preventative vaccine is not yet available. Therapeutics for fetuses need to overcome placenta barriers to reach the fetuses and require higher safety standards. In the present study, we engineered mammalian extracellular vesicles (EVs) to deliver a host restriction factor, interferon-induced transmembrane protein 3 (IFITM3), for the treatment of ZIKV infection. Our results demonstrated that the IFITM3-containing EVs (IFITM3-Exos) suppressed ZIKV viremia by a 2-log reduction in pregnant mice. Moreover, the engineered EVs effectively delivered IFITM3 protein across the placental barrier and suppressed ZIKV in the fetuses with significant reduction of viremia in key fetal organs as measured by quantitative real-time PCR. Mechanistic study showed that IFITM3 was delivered to late endosomes/lysosomes where it inhibited viral entry into the host cells. Our study demonstrated that EVs could act as a cross-placenta drug delivery vehicle to the fetus, and IFITM3, an endogenous restriction factor, is a potential treatment for ZIKV infection during pregnancy.

Co-culture model reveals the characteristics of theca cells and the effect of granulosa cells on theca cells at different stages of follicular development

Theca cells (TCs) play an important role in follicular development, which cannot be separated from granulosa cells (GCs). However, compared with mammals, the TCs and the effects of GCs on TCs at different follicular development stages (FDSs) have specific characteristics in avian species, but none of them have been clearly defined. In this study, we established an in vitro co-culture (with GC at the corresponding stage) model of goose TCs at different FDSs (pre-hierarchical, hierarchical and F1) by using a transwell system. The properties of TCs in co-culture at the three FDSs, including cell morphology, activity and intracellular lipid content, as well as the expression of key genes involved in de novo lipogenesis, steroidogenesis, proliferation and apoptosis, were examined and defined. We further compared the mono-culture and co-culture groups. After co-culture, the activity of TCs showed significant (p < .01) increases in all stages; moreover, in pre-hierarchical TCs, the expression levels of FAS, SREBP, 3β-HSD and CCND1 were promoted, and PPARγ, CYP19, BCL2 and CAS3 were inhibited (p < .05); in the hierarchical TCs, the expression levels of PPARγ, FAS, CYP19, CCND1 and BCL2 were promoted, and SREBP, STAR, 3β-HSD and CAS3 were inhibited (p < .05), whereas in the F1 TCs, the expression levels of PPARγ, FAS, 3β-HSD, CYP19 and CCND1 were promoted, and STAR and CAS3 were inhibited (p < .05). These results suggested that GCs at the three FDSs have dynamic and complex influences on the physiological characteristics of TCs, and the influences on TCs at the three FDSs were varied.

The unique applicability of the human placenta to the Adverse Outcome Pathway (AOP) concept: the placenta provides fundamental insights into human organ functions at multiple levels of biological organization

Despite the short lifespan of the human placenta, the proper formation and function of the organ is of crucial importance for fetal development. Placental dysfunction increases the risk of complications for mother and child during pregnancy and childbirth and beyond as it predisposes to fetal programming. The placenta is an upstream organ of the fetus. It performs the functions of fetal lungs, liver, intestines, kidneys and glands as long as these organs are not fully functional. Furthermore, it is the only human organ that is non-invasively available either after elective abortion or after birth. This is a crucial point given that the conceptual framework of Adverse Outcome Pathway (AOP) requires data on organ function. In vitro and ex vivo placental studies, combined with epidemiological and clinical data on pregnant women, newborns, and infants can uniquely cover all levels of information needed to develop new AOPs and complement existing AOPs related to reproductive toxicity and beyond. To stimulate further research in this area and to support researchers in future studies dealing with the development of AOPs related to the placenta, this review first gives a brief description of placental structure, placental development and relevant pregnancy diseases. The state of knowledge about the available placental models, their particularities and limitations are briefly discussed. Finally, the use of placental research for the development of AOPs is presented with an illustrative example.

Evaluating the effects on steroidogenesis of estragole and trans-anethole in a feto-placental co-culture model

In this study, we determined whether estragole and its isomer trans-anethole interfered with feto-placental steroidogenesis in a human co-culture model composed of fetal-like adrenocortical (H295R) and placental trophoblast-like (BeWo) cells. Estragole and trans-anethole are considered the biologically active compounds within basil and fennel seed essential oils, respectively. After a 24 h exposure of the co-culture to 2.5, 5.2 and 25 μM estragole or trans-anethole, hormone concentrations of estradiol, estrone, dehydroepiandrosterone, androstenedione, progesterone and estriol were significantly increased. Using RT-qPCR, estragole and trans-anethole were shown to significantly alter the expression of several key steroidogenic enzymes, such as those involved in cholesterol transport and steroid hormone biosynthesis, including StAR, CYP11A1, HSD3B1/2, SULT2A1, and HSD17B1, -4, and -5. Furthermore, we provided mechanistic insight into the ability of estragole and trans-anethole to stimulate promoter-specific expression of CYP19 through activation of the PKA pathway in H295R cells and the PKC pathway in BeWo cells, in both cases associated with increased cAMP levels. Moreover, we show new evidence suggesting a role for progesterone in regulating steroid hormone biosynthesis through regulation of the StAR gene.

Essential oils disrupt steroidogenesis in a feto-placental co-culture model

We determined whether 5 common essential oils (basil, fennel seed, orange, black pepper and sage) interfered with feto-placental steroidogenesis in a co-culture model composed of fetal-like adrenocortical (H295R) and placental trophoblast-like (BeWo) cells. After a 24 h exposure, only basil and fennel seed oil significantly increased hormone concentrations of estradiol, estrone, dehydroepiandrosterone (DHEA), androstenedione, progesterone, and estriol. Basil and fennel seed oil were shown to significantly alter the expression of steroidogenic enzymes involved in cholesterol transport and steroid hormone biosynthesis, including StAR, CYP11A1, 3β-HSD1/2, SULT2A1, and HSD17β1, -4, and -5. Also, basil and fennel seed oil stimulated placental-specific promoter I.1 and pII-derived CYP19 mRNA in BeWo and H295R cells, respectively, as well as, increased CYP19 enzyme activity. Our results indicate that further study is necessary to determine the potential risks of using basil and fennel seed oils during pregnancy considering their potential to disrupt steroidogenic enzyme activity and expression in vitro.

Changes in gene expression following long-term in vitro exposure of Macaca mulatta trophoblast stem cells to biologically relevant levels of endocrine disruptors

Trophoblast stem cells (TSCs) are crucial for embryo implantation and placentation. Environmental toxicants that compromise TSC function could impact fetal viability, pregnancy, and progeny health. Understanding the effects of low, chronic EDC exposures on TSCs and pregnancy is a priority in developmental toxicology. Differences in early implantation between primates and other mammals make a nonhuman primate model ideal. We examined effects of chronic low-level exposure to atrazine, tributyltin, bisphenol A, bis(2-ethylhexyl) phthalate, and perfluorooctanoic acid on rhesus monkey TSCs in vitro by RNA sequencing. Pathway analysis of affected genes revealed negative effects on cytokine signaling related to anti-viral response, most strongly for atrazine and tributyltin, but shared with the other three EDCs. Other affected processes included metabolism, DNA repair, and cell migration. Low-level chronic exposure of primate TSCs to EDCs may thus compromise trophoblast development in vivo, inhibit responses to infection, and negatively affect embryo implantation and pregnancy.

Profile of CYP19A1 mRNA expression and aromatase activity during syncytialization of primary human villous trophoblast cells at term

Estrogen production by the human villous trophoblast is dependent on the biosynthetic enzyme aromatase (CYP19; CYP19A1) and is crucial for successful placental development and pregnancy outcome. Using villous cytotrophoblast cells (vCTs) freshly isolated from normal term placenta, we characterized the promoter-specific expression of CYP19A1 mRNA (derived from promoters I.1, I.4, I.8 or total transcript) and aromatase activity during villous trophoblast syncytialization. CYP19A1 mRNA levels and aromatase activity in vCTs reached a maximum after about 48 h of culture. The cAMP inducer forskolin (10 μM) and protein kinase C stimulant phorbol myristate acetate (1 μM) increased CYP19A1 mRNA levels by 1.8- and 1.6-fold, respectively, as well as inducing aromatase catalytic activity. Dexamethasone (100 nM) and vascular endothelial growth factor (5 ng/mL) decreased CYP19A1 mRNA levels, while having no effect on aromatase activity. Our results emphasize the importance of not solely studying CYP19A1 regulation and function at the mRNA level but also considering posttranslational mechanisms that alter the final catalytic activity of aromatase.

Atrazine affects the morphophysiology, tissue homeostasis and aromatase expression in the efferent ductules of adult rats with mild alterations in the ventral prostate

The widely used herbicide atrazine is a potent endocrine disruptor known to cause increased aromatase expression and transient increase in testicular weight followed by remarkable testis atrophy. However, whether the effects of atrazine on the testes are primary or secondary to dysfunctions in other components of male reproductive tract remains unknown. Given the high sensitivity of the efferent ductules to estrogen imbalance and the similarity to alterations previously described for other disruptors of these ductules function, and the testicular alterations observed after atrazine exposure, we hypothesized that the efferent ductules could be a target for atrazine. Herein we characterized the efferent ductules and the ventral prostate of adult Wistar rats treated with 200 mg/kg/day of atrazine for 7, 15, and 40 days. Additionally, we evaluated if the effects of atrazine in these organs could be reduced after discontinuation of the treatment. Atrazine exposure resulted in mild effects on the ventral prostate, but remarkable alterations on the efferent ductules, including luminal dilation, reduced epithelial height, and disruption of the epithelial homeostasis, which coincides with increased aromatase expression. Together with our previous data, these results suggest that at least part of the testicular effects of atrazine may be secondary to the alterations in the efferent ductules.

An Electrical Impedance-Based Assay to Examine Functions of Various Placental Cell Types In Vitro

In vitro functional analyses of cells are widely used to investigate the molecular mechanisms involved in preeclampsia. Common cellular functions studied include adhesion, apoptosis, proliferation, migration, and invasion. At present, most researchers will use endpoint experimental assays that only allow the determination of cell function at a single time point, with the need to repeat the experiment for an alternate time point. Here, we describe an electrical impedance-based tool that allows real-time monitoring of cells, which enables the efficient assessment of multiple time points over the duration of a single experiment.

Co-culture of H295R Adrenocortical Carcinoma and BeWo Choriocarcinoma Cells to Study Feto-placental Interactions: Focus on Estrogen Biosynthesis

Estrogens are produced in large amounts during pregnancy, as a result of a tightly regulated cooperation between the maternal and fetal adrenal cortex, which produce androgen precursors, and the placental villous trophoblast, which transforms these precursors into estrogens. These estrogens play an important role in proper placental function, in adaptation of the mother to pregnancy, as well as in adequate fetal development. Disruption of estrogen production is associated with poor pregnancy outcomes and fetal malformation or altered fetal programming. Pregnant women may be exposed to endocrine disruptors from environmental sources or medications, and it is crucial to study the effects of such compounds on feto-placental steroidogenesis. The H295R/BeWo co-culture model offers the opportunity to study these interactions, by making it possible to evaluate the effects of chemical exposures on androgen and estrogen biosynthesis, as well as on various other aspects of feto-placental communication.

Co-culture of JEG-3, BeWo and syncBeWo cell lines with adrenal H295R cell line: an alternative model for examining endocrine and metabolic properties of the fetoplacental unit

Monocultures of different placental cells are used for many physiological and toxicological studies; however, they are not a true reflection of the interaction between placenta and fetus. To develop the most appropriate model to study endocrine and metabolic properties of fetoplacental unit we used three co-culture models of placental cells nonfusogenic JEG-3, unsyncytialised BeWo (BeWo) and syncytialised BeWo (syncBeWo) cultured with adrenal (H295R) cells. As an end point of endocrine properties we investigated steroids receptors expression and steroid secretion, while as metabolic properties AhR, CYP1A1and COMT expression. Progesterone (P4), estradiol (E2) and human chorionic gonadotropin (hCG) secretion (ELISA) and 3βHSD, CYP19, estrogen (ERα/β), progesterone (PR) and aryl hydrocarbon (AhR) receptors, CYP1A1 and COMT protein expression (Western blot) were evaluated. Comparing three co-culture models we observed: (1) there were no differences between JEG-3 and BeWo in the PR expression, however it was higher in BeWo compared to syncBeWo; (2) there were no differences in ERα protein expression in all models, while profile of ERβ expression was the highest in syncBeWo; (3) high P4 secretion in JEG-3 and BeWo while low in syncBeWo; (4) high E2 levels in JEG-3 and syncBeWo, while low E2 secretion in BeWo; (5) the highest hCG secretion in the JEG-3 and syncBeWo than in BeWo (6) the highest AhR, CYP1A1 and COMT expression in syncBeWo. Based on the results showing higher hCG secretion in the JEG-3 than in BeWo, representing villous and extravillous phenotype we suggest that JEG-3 model could be used to study fetoplacental steroidogenesis at the 1st, while BeWo model at the 3rd. Results showing comparable profiles of AhR, CYP1A1 and COMT expression in JEG-3 and BeWo models and the significantly higher expression in synBeWo points to synBeWo as a good model for study the metabolic properties.

Persistent testicular structural and functional alterations after exposure of adult rats to atrazine

Atrazine is an endocrine disruptor affecting testicular steroidogenesis, and promoting testicular atrophy and 3β-HSD reduction. However, it remains unknown whether these effects are reversible or permanent. To address this issue was the aim of this study. Exposition of rats to 200mg/kg of atrazine resulted in transient increase in testicular weight, seminiferous tubules dilation and atrophy, and reduction in Leydig cell 3β-HSD. Testicular atrophy and 3β-HSD reduction were more pronounced after the recovery period of 75days. There was increase in aromatase expression after long-term exposure but it returned to control level after recovery. Moreover, there was increase in ED1^-/ED2⁺, ED1⁺/ED2⁺ and ED1⁺/ED2^- macrophages, in the recovery group. These macrophages were positive for 3β-HSD, thereby raising possibility of their involvement in steroidogenesis. These findings further emphasize the adverse effects of atrazine on male reproduction, highlighting that testicular damages may be irreversible even after a recovery period longer than the spermatogenic cycle.

A comparative study of five physiological key parameters between four different human trophoblast-derived cell lines

The human placenta plays a crucial role as the interface between mother and fetus. It represents a unique tissue that undergoes morphological as well as functional changes on the cellular and tissue level throughout pregnancy. To better understand how the placenta works, a variety of techniques has been developed to re-create this complex physiological barrier in vitro. However, due to the low availability of freshly isolated primary cells, choriocarcinoma cell lines remain the usual suspects as in vitro models for placental research. Here, we present a comparative study on the functional aspects of the choriocarcinoma cell lines BeWo, JAR and Jeg-3, as well as the first trimester trophoblast cell line ACH-3P as placental in vitro barrier models for endocrine and transport studies. Functional assays including tight junction immunostaining, sodium fluorescein retardation, trans epithelial resistance, glucose transport, hormone secretion as well as size-dependent polystyrene nanoparticle transport were performed using the four cell types to evaluate key functional parameters of each cell line to act a relevant in vitro placental barrier model.

Fluoxetine and its active metabolite norfluoxetine disrupt estrogen synthesis in a co-culture model of the feto-placental unit

The effects of fluoxetine, one of the most prescribed selective serotonin-reuptake inhibitors (SSRIs) during pregnancy, and its active metabolite norfluoxetine were studied on placental aromatase (CYP19) and feto-placental steroidogenesis. Fluoxetine did not alter estrogen secretion in co-culture of fetal-like adrenocortical (H295R) and trophoblast-like (BeWo) cells used as a model of the feto-placental unit, although it induced CYP19 activity, apparently mediated by the serotonin (5-HT)_2A receptor/PKC signaling pathway. Norfluoxetine decreased estrogen secretion in the feto-placental co-culture and competitively inhibited catalytic CYP19 activity in BeWo cells. Decreased serotonin transporter (SERT) activity in the co-culture was comparable to 17β-estradiol treatment of BeWo cells. This work shows that the complex interaction of fluoxetine and norfluoxetine with placental estrogen production, involves 5-HT-dependent and -independent mechanisms. Considering the crucial role of estrogens during pregnancy, our results raise concern about the impact of SSRI treatment on placental function and fetal health.

Effects of long-term endocrine disrupting compound exposure on Macaca mulatta embryonic stem cells

Endocrine disrupting chemicals (EDCs) exert significant effects on health and physiology, many traceable to effects on stem cell programming underlying development. Understanding risk of low-level, chronic EDC exposure will be enhanced by knowledge of effects on stem cells. We exposed rhesus monkey embryonic stem cells to low levels of five EDCs [bisphenol A (BPA), atrazine (ATR), tributyltin (TBT), perfluorooctanoic acid (PFOA), and di-(2-ethylhexyl) phthalate (DEHP)] for 28days, and evaluated effects on gene expression by RNAseq transcriptome profiling. We observed little effect of BPA, and small numbers of affected genes (≤119) with other EDCs. There was substantial overlap in effects across two, three, or four treatments. Ingenuity Pathway analysis indicated suppression of cell survival genes and genes downstream of several stress response mediators, activation of cell death genes, and modulations in several genes regulating pluripotency, differentiation, and germ layer development. Potential adverse effects of these changes on development are discussed.

Freeze-drying as suitable method to achieve ready-to-use yeast biosensors for androgenic and estrogenic compounds

Recombinant yeast assays (RYAs) have been proved to be a suitable tool for the fast screening of compounds with endocrine disrupting activities. However, ready-to-use versions more accessible to less equipped laboratories and field studies are scarce and far from optimal throughputs. Here, we have applied freeze-drying technology to optimize RYA for the fast assessment of environmental compounds with estrogenic and androgenic potencies. The effects of different cryoprotectants, initial optical density and long-term storage were evaluated. The study included detailed characterization of sensitivity, robustness and reproducibility of the new ready-to-use versions, as well as comparison with the standard assays. Freeze-dried RYAs showed similar dose-responses curves to their homolog standard assays, with Lowest Observed Effect Concentration (LOEC) and Median effective Concentration (EC50) of 1 nM and 7.5 nM for testosterone, and 0.05 nM and 0.5 nM for 17β-estradiol, respectively. Freeze-dried cells stored at 4 °C retained maximum sensitivity up to 2 months, while cells stored at -18 °C showed no decrease in sensitivity throughout the study (10 months). This ready-to-use RYA is easily accessible and may be potentially used for on-site applications.

Effects of Neonicotinoids on Promoter-Specific Expression and Activity of Aromatase (CYP19) in Human Adrenocortical Carcinoma (H295R) and Primary Umbilical Vein Endothelial (HUVEC) Cells

The enzyme aromatase (CYP19; cytochrome P450 19) in humans undergoes highly tissue- and promoter-specific regulation. In hormone-dependent breast cancer, aromatase is over-expressed via several normally inactive promoters (PII, I.3, I.7). Aromatase biosynthesizes estrogens, which stimulate breast cancer cell proliferation. The placenta produces estrogens required for healthy pregnancy and the major placental CYP19 promoter is I.1. Exposure to certain pesticides, such as atrazine, is associated with increased CYP19 expression, but little is known about the effects of neonicotinoid insecticides on CYP19. We developed sensitive and robust RT-qPCR methods to detect the promoter-specific expression of CYP19 in human adrenocortical carcinoma (H295R) and primary umbilical vein endothelial (HUVEC) cells, and determined the potential promoter-specific disruption of CYP19 expression by atrazine and the commonly used neonicotinoids imidacloprid, thiacloprid, and thiamethoxam. In H295R cells, atrazine concentration-dependently increased PII- and I.3-mediated CYP19 expression and aromatase catalytic activity. Thiacloprid and thiamethoxam induced PII- and I.3-mediated CYP19 expression and aromatase activity at relatively low concentrations (0.1-1.0 µM), exhibiting non-monotonic concentration-response curves with a decline in gene induction and catalytic activity at higher concentrations. In HUVEC cells, atrazine slightly induced overall (promoter-indistinct) CYP19 expression (30 µM) and aromatase activity (≥ 3 µM), without increasing I.1 promoter activity. None of the neonicotinoids increased CYP19 expression or aromatase activity in HUVEC cells. Considering the importance of promoter-specific (over)expression of CYP19 in disease (breast cancer) or during sensitive developmental periods (pregnancy), our newly developed RT-qPCR methods will be helpful tools in assessing the risk that neonicotinoids and other chemicals may pose to exposed women.

Towards a non-animal risk assessment for anti-androgenic effects in humans

Toxicology testing is undergoing a transformation from a system based on high-dose studies in laboratory animals to one founded primarily on in vitro methods that evaluate changes in normal cellular signalling pathways using human-relevant cells or tissues. We review the tools and approaches that could be used to develop a non-animal safety assessment for anti-androgenic effects in humans, with a focus on the molecular initiating events (MIEs) that human disorders indicate critical for normal functioning of the hypothalamus-pituitary-testicular (HPT) axis. In vitro test systems exist which can be used to characterize the effects of test chemicals on some MIEs such as androgen receptor antagonism, inhibition of steroidogenic enzymes or 5α-reductase inhibition. When used alongside information describing the pharmacokinetics of a specific chemical exposure, these could be used to inform a pathways-based safety assessment. However, some parts of the HPT axis such as events occurring in the hypothalamus or pituitary are not well represented by accepted in vitro methods. In vitro tools to characterize perturbations in these events need to be developed before a fully integrated model of the HPT axis can be described. Knowledge gaps also exist which prevent us from using in vitro data to predict the type and severity of in vivo effect(s) that could arise from a given level of in vitro anti-androgenic activity. This means that more work is needed to reliably link an MIE with an adverse outcome. However, especially for chemicals with low anti-androgenic activity, human exposure data can be used to put in vitro mode of action data into context for risk-based safety decision-making.