Perinatal administration of bisphenol A alters the expression of tight junction proteins in the uterus and reduces the implantation rate

F-53B mediated ROS affects uterine development in rats during puberty by inducing apoptosis

Perfluoroalkyl and polyfluoroalkyl substances (PFASs), as pollutants, can cause palpable environmental and health impacts around the world, as endocrine disruptors, can disrupt endocrine homeostasis and increase the risk of diseases. Chlorinated polyfluoroalkyl ether sulfonate (F-53B), as a substitute for PFAS, was determined to have potential toxicity. Puberty is the stage when sexual organs develop and hormones change dramatically, and abnormal uterine development can increase the risk of uterine lesions and lead to infertility. This study was designed to explore the impact of F-53B on uterine development during puberty. Four-week-old female SD rats were exposed to 0.125 and 6.25 mg/L F-53B during puberty. The results showed that F-53B interfered with growth and sex hormone levels and bound to oestrogen-related receptors, which affected their function, contributed to the accumulation of reactive oxygen species, promoted cell apoptosis and inhibited cell proliferation, ultimately causing uterine dysplasia.

Adenomyotic Lesions Are Induced in the Mouse Uterus after Exposure to NSAID and EE2 Mixtures at Environmental Doses

The aim of this study was to assess the long-term effect of exposure to environmentally relevant doses of non-steroidal anti-inflammatory drugs (NSAIDs; ibuprofen, and diclofenac) and 17β-ethinylestradiol (EE2) on the mouse uterus. NSAID-EE2 mixtures were administered in the drinking water from gestational day 8 until 8 weeks post-birth (i.e., during embryo development, lactation, puberty, and sexual maturity). The incidence of adenomyosis lesions (presence of endometrial glands in the inner myometrium) increased up to 60% in the uterus of 8-week-old exposed females (F1) and to 85% in F2 females (exposed father). Histological analysis revealed aberrant proliferation and apoptosis, vacuolization of epithelial cells, and increased incidence of abnormal glands in the luminal and glandular epithelium in F1 and F2 uteri. Moreover, myofibroblast proportion (alpha-smooth muscle actin (α-SMA) expression analysis) and collagen expression (Picrosirius red stain; a fibrosis hallmark) were increased in F1 and F2 endometrium. Connexin-43 was aberrantly distributed in the endometrial stroma and glands of F1 and F2 uteri. Conversely, uterine 17β-estradiol and progesterone levels were not affected in F1 and F2 females. These findings demonstrated that in mice, chronic exposure to NSAID and EE2 mixtures at environmental doses intergenerationally affects uterine physiology, particularly the endometrium. It may serve as a model to study the pathophysiology of human adenomyosis.

Invisible Hand behind Female Reproductive Disorders: Bisphenols, Recent Evidence and Future Perspectives

Reproductive disorders are considered a global health problem influenced by physiological, genetic, environmental, and lifestyle factors. The increased exposure to bisphenols, a chemical used in large quantities for the production of polycarbonate plastics, has raised concerns regarding health risks in humans, particularly their endocrine-disrupting effects on female reproductive health. To provide a basis for future research on environmental interference and reproductive health, we reviewed relevant studies on the exposure patterns and levels of bisphenols in environmental matrices and humans (including susceptible populations such as pregnant women and children). In addition, we focused on in vivo, in vitro, and epidemiological studies evaluating the effects of bisphenols on the female reproductive system (the uterus, ovaries, fallopian tubes, and vagina). The results indicate that bisphenols cause structural and functional damage to the female reproductive system by interfering with hormones; activating receptors; inducing oxidative stress, DNA damage, and carcinogenesis; and triggering epigenetic changes, with the damaging effects being intergenerational. Epidemiological studies support the association between bisphenols and diseases such as cancer of the female reproductive system, reproductive dysfunction, and miscarriage, which may negatively affect the establishment and maintenance of pregnancy. Altogether, this review provides a reference for assessing the adverse effects of bisphenols on female reproductive health.

Bisphenols as promoters of the dysregulation of cellular junction proteins of the blood-testis barrier in experimental animals: A systematic review of the literature

Daily, people are exposed to chemicals and environmental compounds such as bisphenols (BPs). These substances are present in more than 80% of human fluids. Human exposure to BPs is associated with male reproductive health disorders. Some of the main targets of BPs are intercellular junction proteins of the blood-testis barrier (BTB) in Sertoli cells because BPs alter the expression or induce aberrant localization of these proteins. In this systematic review, we explore the effects of BP exposure on the expression of BTB junction proteins and the characteristics of in vivo studies to identify potential gaps and priorities for future research. To this end, we conducted a systematic review of articles. Thirteen studies met our inclusion criteria. In most studies, animals treated with bisphenol-A (BPA) showed decreased occludin expression at all tested doses. However, bisphenol-AF treatment did not alter occludin expression. Cx43, ZO-1, β-catenin, nectin-3, cortactin, paladin, and claudin-11 expression also decreased in some tested doses of BP, while N-cadherin and FAK expression increased. BP treatment did not alter the expression of α and γ catenin, E-cadherin, JAM-A, and Arp 3. However, the expression of all these proteins was altered when BPA was administered to neonatal rodents in microgram doses. The results show significant heterogeneity between studies. Thus, it is necessary to perform more research to characterize the changes in BTB protein expression induced by BPs in animals to highlight future research directions that can inform the evaluation of risk of toxicity in humans.

Re-evaluation of the risks to public health related to the presence of bisphenol A (BPA) in foodstuffs

In 2015, EFSA established a temporary tolerable daily intake (t-TDI) for BPA of 4 μg/kg body weight (bw) per day. In 2016, the European Commission mandated EFSA to re-evaluate the risks to public health from the presence of BPA in foodstuffs and to establish a tolerable daily intake (TDI). For this re-evaluation, a pre-established protocol was used that had undergone public consultation. The CEP Panel concluded that it is Unlikely to Very Unlikely that BPA presents a genotoxic hazard through a direct mechanism. Taking into consideration the evidence from animal data and support from human observational studies, the immune system was identified as most sensitive to BPA exposure. An effect on Th17 cells in mice was identified as the critical effect; these cells are pivotal in cellular immune mechanisms and involved in the development of inflammatory conditions, including autoimmunity and lung inflammation. A reference point (RP) of 8.2 ng/kg bw per day, expressed as human equivalent dose, was identified for the critical effect. Uncertainty analysis assessed a probability of 57-73% that the lowest estimated Benchmark Dose (BMD) for other health effects was below the RP based on Th17 cells. In view of this, the CEP Panel judged that an additional uncertainty factor (UF) of 2 was needed for establishing the TDI. Applying an overall UF of 50 to the RP, a TDI of 0.2 ng BPA/kg bw per day was established. Comparison of this TDI with the dietary exposure estimates from the 2015 EFSA opinion showed that both the mean and the 95th percentile dietary exposures in all age groups exceeded the TDI by two to three orders of magnitude. Even considering the uncertainty in the exposure assessment, the exceedance being so large, the CEP Panel concluded that there is a health concern from dietary BPA exposure.

Coprophagy Prevention Affects the Reproductive Performance in New Zealand White Rabbits Is Mediated through Nox4-ROS-NFκB Pathway

Coprophagy is of great significance to the growth, development, and reproductive performance of rabbits. This study is aimed at exploring the effect of coprophagy on the reproductive performance of New Zealand white rabbits by coprophagy prevention (CP). The results showed that CP treatment significantly decreased the growth and development performance of female rabbits and the live birth rate of embryos. The results of blood biochemical indexes showed that CP treatment significantly increased the contents of serum ALB, ALP, and MDA, while serum SOD activity was significantly decreased. Transcriptome analysis showed that GO terms were mainly enriched in transport function and reproductive function after CP treatment. In addition, KEGG results showed that inflammation related signal pathways were activated and the expression level of genes related to tight junction proteins was downregulated by CP treatment. Concurrently, western blot further confirmed the results of KEGG. In short, fecal feeding is an important survival strategy for some small rodents, coprophagy prevention will affect the inflammatory level of the body, change the oxidative stress level of the body, and then activate NOX4-ROS-NF-κB pathway, increase the expression level of adhesion protein ICAM-1 and VCAM-1, lead to the damage of uterine epithelial barrier, and then affect the reproductive performance of rabbits.

Maternal perinatal exposure to bisphenol S induces an estrogenic like effect in glucose homeostasis in male offspring

Bisphenol S (BPS) has been introduced into the industry as a safer alternative to bisphenol A (BPA). However, the recent studies have reported a possible association between BPS and disturbed glucose homeostasis, indicating that it may be a risk factor for type 1 and type 2 diabetes mellitus, obesity, and gestational diabetes mellitus. Nevertheless, the role of BPS in glucose metabolism remains controversial. In this study, we investigated the glucose metabolism of male Wistar rats born from dams that were BPS-exposed (groups: BPS-L (0.05 mg/kg/day), BPS-H (20 mg/kg/day)) during pregnancy and lactation. We observed that both BPS treated groups of animals presented a significant decrease in anogenital distance/weight^1/3 , as compared to control animals, although no alterations in testosterone levels were observed. Furthermore, the BPS-L group presented a significant decrease in body weight from postnatal day (PND) 21 to adult stage. In addition, a significant increase in glucose tolerance, pancreatic β-cell proliferation, the frequency of small islets, and the average β-cell size at PND 36 was observed in this group. However, no changes in insulin serum levels and percentage of β-cells were recorded. Furthermore, these changes were not preserved at the adult stage (PND 120). The results suggest that the administration of low doses of BPS during the perinatal period induced an estrogenic like effect, with males apparently becoming more female-like in their responses to a glucose challenge.

The Effect of BPA-Treated Water on the Small Intestine via an In Vivo Study

Since the major route of BPA exposure is via the oral route, BPA may have effects on the gastrointestinal tract, especially on the intestinal barrier, where most digestion and absorption processes occur. In this study, the effects of BPA-treated water on the small intestine (SI) and SI tight junction proteins (TJPs) of both pregnant Sprague–Dawley rats and their fetuses were investigated. Previously, hybrid photocatalytic filtration treatment by a visible light driven N-doped TiO₂ membrane has successfully removed up to 81.6% of BPA in water. The effect of BPA-untreated (5.00 ± ppm) and BPA-treated water (0.9 ± ppm) after 21 days of exposure on the jejunum and ileum, as well as the expressions of claudin proteins, were investigated by Western blotting (WB) and hematoxylin and eosin (H&E) in order to investigate the potential of the photocatalytic membrane in removing the detrimental effect of BPA. The results suggest that BPA exposure altered the morphology of villi, and affected the expression level of claudin-2, -3, and -4 proteins in the jejunum and ileum of both pregnant rats and their fetuses. Interestingly, villi and claudins expressions were undisrupted in a treated-BPA water group, which indicated that the degradation of BPA via membranes effectively mitigates the effect on BPA on gastrointestinal tract.

Pre-implantation triclosan exposure alters uterine receptivity through affecting tight junction protein†

Triclosan (TCS) is a broad-spectrum antibacterial agent and widely exists in environmental media and organisms. TCS exposure was reported to have adverse effects on reproduction including embryo implantation disorder. During the embryo implantation window, it is vital that the endometrium develops into a receptive state under the influence of ovarian hormones. However, the effect of TCS on embryo implantation and endometrial receptivity remains unclear. In current study, we found decreased embryo implantation rate, serum estrogen (E2) and progesterone (P4) levels in mice exposed to TCS from gestation day (GD) 0.5 to 5.5. Through RNA-seq, we identified nearly 800 differentially expressed genes (DEGs), which were enriched in pathways including uterus development, inflammatory response and immune system process. Among those enriched pathways, the tight junction pathway is essential for the establishment of receptive state of endometrium. Then, genes involved in tight junction pathway including Cldn7, Cldn10 and Crb3 were validated by RT-qPCR and the results were consistent with the RNA-seq. Through immunofluorescence staining and western blotting, we confirmed that the tight junction protein levels of CLDN7 and CRB3 were increased. All these findings suggest that pre-implantation TCS exposure reduces the rate of embryo implantation through up-regulating the expression of tight junction genes and affecting the receptivity of endometrium. Our data could be used to determine the sensitive time frame for TCS exposure and offer new strategy to prevent implantation failure.

Integrating Statistical and Machine-Learning Approach for Meta-Analysis of Bisphenol A-Exposure Datasets Reveals Effects on Mouse Gene Expression within Pathways of Apoptosis and Cell Survival

Bisphenols are important environmental pollutants that are extensively studied due to different detrimental effects, while the molecular mechanisms behind these effects are less well understood. Like other environmental pollutants, bisphenols are being tested in various experimental models, creating large expression datasets found in open access storage. The meta-analysis of such datasets is, however, very complicated for various reasons. Here, we developed an integrating statistical and machine-learning model approach for the meta-analysis of bisphenol A (BPA) exposure datasets from different mouse tissues. We constructed three joint datasets following three different strategies for dataset integration: in particular, using all common genes from the datasets, uncorrelated, and not co-expressed genes, respectively. By applying machine learning methods to these datasets, we identified genes whose expression was significantly affected in all of the BPA microanalysis data tested; those involved in the regulation of cell survival include: Tnfr2, Hgf-Met, Agtr1a, Bdkrb2; signaling through Mapk8 (Jnk1)); DNA repair (Hgf-Met, Mgmt); apoptosis (Tmbim6, Bcl2, Apaf1); and cellular junctions (F11r, Cldnd1, Ctnd1 and Yes1). Our results highlight the benefit of combining existing datasets for the integrated analysis of a specific topic when individual datasets are limited in size.

Molecular mechanisms of mammary gland remodeling: A review of the homeostatic versus bisphenol a disrupted microenvironment

Mammary gland (MG) undergoes critical points of structural changes throughout a woman's life. During the perinatal and pubertal stages, MG develops through growth and differentiation to establish a pre-mature feature. If pregnancy and lactation occur, the epithelial compartment branches and differentiates to create a specialized structure for milk secretion and nurturing of the newborn. However, the ultimate MG modification consists of a regression process aiming to reestablish the smaller and less energy demanding structure until another production cycle happens. The unraveling of these fascinating physiologic cycles has helped the scientific community elucidate aspects of molecular regulation of proliferative and apoptotic events and remodeling of the stromal compartment. However, greater understanding of the hormonal pathways involved in MG developmental stages led to concern that endocrine disruptors such as bisphenol A (BPA), may influence these specific development/involution stages, called "windows of susceptibility". Since it is used in the manufacture of polycarbonate plastics and epoxy resins, BPA is a ubiquitous chemical present in human everyday life, exerting an estrogenic effect. Thus, descriptions of its deleterious effects on the MG, especially in terms of serum hormone concentrations, hormonal receptor expression, molecular pathways, and epigenetic alterations, have been widely published. Therefore, allied to a didactic description of the main physiological mechanisms involved in different critical points of MG development, the current review provides a summary of key mechanisms by which the endocrine disruptor BPA impacts MG homeostasis at different windows of susceptibility, causing short- and long-term effects.

Effects of Endocrine-Disrupting Chemicals on Endometrial Receptivity and Embryo Implantation: A Systematic Review of 34 Mouse Model Studies

Several available studies have already analyzed the systemic effects of endocrine-disrupting chemicals (EDCs) on fertile woman and neonatal outcomes, but little is still known in humans about the precise mechanisms of interference of these compounds with the endometrial receptivity. There is consistent evidence that continuous and prolonged exposure to EDCs is a risk factor for reduced fertility and fecundity in women. Preliminary studies on mammalian models provide robust evidence about this issue and could help gynecologists worldwide to prevent long term injury caused by EDCs on human fertility. In this systematic review, we aimed to systematically summarize all available data about EDC effects on blastocyst endometrial implantation. We performed a systematic review using PubMed^®/MEDLINE^® to summarize all in vivo studies, carried out on mice models, analyzing the molecular consequences of the prolonged exposure of EDC on the implantation process. 34 studies carried out on mouse models were included. Primary effects of EDC were a reduction of the number of implantation sites and pregnancy rates, particularly after BPA and phthalate exposure. Furthermore, the endometrial expression of estrogen (ER) and progesterone receptors (PR), as well as their activation pathways, is compromised after EDC exposure. Finally, the expression of the primary endometrial markers of receptivity (such as MUC1, HOXA10, Inn and E-cadherin) after EDC contact was analyzed. In conclusion EDC deeply affect blastocyst implantation in mouse model. Several players of the implantation mechanism are strongly influenced by the exposure to different categories of EDC.

Scorpio D, Scozzoli M, Bettini G, Forni M, Bacci ML. Preliminary Assessment of the Mucosal Toxicity of Tea Tree (Melaleuca alternifolia) and Rosemary (Rosmarinus officinalis) Essential Oils on Novel Porcine Uterus Models

Antimicrobial resistance, an ever-growing global crisis, is strongly linked to the swine production industry. In previous studies, Melaleucaalternifolia and Rosmarinusofficinalis essential oils have been evaluated for toxicity on porcine spermatozoa and for antimicrobial capabilities in artificial insemination doses, with the future perspective of their use as antibiotic alternatives. The aim of the present research was to develop and validate in vitro and ex vivo models of porcine uterine mucosa for the evaluation of mucosal toxicity of essential oils. The in vitro model assessed the toxicity of a wider range of concentrations of both essential oils (from 0.2 to 500 mg/mL) on sections of uterine tissue, while the ex vivo model was achieved by filling the uterine horns. The damage induced by the oils was assessed by Evans Blue (EB) permeability assay and histologically. The expression of ZO-1, a protein involved in the composition of tight junctions, was assessed through immunohistochemical and immunofluorescence analysis. The results showed that low concentrations (0.2–0.4 mg/mL) of both essential oils, already identified as non-spermicidal but still antimicrobial, did not alter the structure and permeability of the swine uterine mucosa. Overall, these findings strengthen the hypothesis of a safe use of essential oils in inseminating doses of boar to replace antibiotics.

Claudins: New Players in Human Fertility and Reproductive System Cancers

Claudins are major integral proteins of tight junctions (TJs), the apical cell-cell adhesions that enable maintaining polarity of epithelial cells, their differentiation, and cell signaling. A number of studies have indicated that claudins might play a crucial role in both physiology and pathogenesis. Their tissue-specific expression was originally linked to the development of different types of cancer and triggered a hope to use them as diagnostic or prognostic markers. However, it seems that their expression is more complex than that, and undoubtedly, claudins participate in one of the most important molecular events in cells. This review summarizes the recent research evaluating the role of claudins in fertility and the most common endocrine-dependent cancers in the reproductive system and highlights the crucial role of claudins both in human fertility and the most common cancers.

Endocrine Disruptors in Water and Their Effects on the Reproductive System

Anthropogenic contaminants in water can impose risks to reproductive health. Most of these compounds are known to be endocrine disrupting chemicals (EDCs). EDCs can impact the endocrine system and subsequently impair the development and fertility of non-human animals and humans. The source of chemical contamination in water is diverse, originating from byproducts formed during water disinfection processes, release from industry and livestock activity, or therapeutic drugs released into sewage. This review discusses the occurrence of EDCs in water such as disinfection byproducts, fluorinated compounds, bisphenol A, phthalates, pesticides, and estrogens, and it outlines their adverse reproductive effects in non-human animals and humans.

Syncytiotrophoblast of Placentae from Women with Zika Virus Infection Has Altered Tight Junction Protein Expression and Increased Paracellular Permeability

The cytotrophoblast of human placenta transitions into an outer multinucleated syncytiotrophoblast (STB) layer that covers chorionic villi which are in contact with maternal blood in the intervillous space. During pregnancy, the Zika virus (ZIKV) poses a serious prenatal threat. STB cells are resistant to ZIKV infections, yet placental cells within the mesenchyme of chorionic villi are targets of ZIKV infection. We seek to determine whether ZIKV can open the paracellular pathway of STB cells. This route is regulated by tight junctions (TJs) which are present in the uppermost portion of the lateral membranes of STB cells. We analyzed the paracellular permeability and expression of E-cadherin, occludin, JAMs -B and -C, claudins -1, -3, -4, -5 and -7, and ZO-1, and ZO-2 in the STB of placentae from ZIKV-infected and non-infected women. In ZIKV-infected placentae, the pattern of expression of TJ proteins was preserved, but the amount of claudin-4 diminished. Placentae from ZIKV-infected women were permeable to ruthenium red, and had chorionic villi with a higher mean diameter and Hofbauer hyperplasia. Finally, ZIKV added to the basolateral surface of a trophoblast cell line reduced the transepithelial electrical resistance. These results suggest that ZIKV can open the paracellular pathway of STB cells.

Dose exposure of Bisphenol- A on female Wistar rats fertility

Background 2, 2-Bis (4-hydroxyphenyl propane [bisphenol A (BPA)] is one of the major environmental pollutants and has the adverse effects on human health. BPA mimics the structure of estrogen and binds to estrogen receptors and alters the secretion of the hormone. It is ingested in humans through the regular use of plastic containers, bottles and food cans. Materials and methods Female Wistar rats were exposed orally to 5, 50, 300, 600 and 800 mg BPA/kg body weight (bd. wt.)/week mixed in olive oil and administered every 168 h for 3 months continuing through the mating, gestation and lactation and its effects on fertility, reproductive organ weight and hormones [LH (luteinizing hormone), FSH (follicle stimulating hormone), estradiol (E2), progesterone (PROG) and PRL (prolactin)] were evaluated. Results The findings revealed that females exposed to BPA exhibited a decrease in female fertility rate and weight of reproductive organs (ovary and uterus) with significant decreased levels of LH, FSH, E2, PROG and PRL in the non-pregnancy phase whereas in cesarean and post-term females, no significance difference was found in fertility rate, reproductive organ weight and hormonal levels. Conclusions These data indicate an increased sensitivity to BPA needs careful evaluation of the current levels of exposure.

Parental perinatal exposure to bisphenol A reduces the threshold to disrupt blastocyst implantation via decreasing talin, occudin and E-cadherin levels

The aim was to evaluate the effect of perinatal BPA exposure of one or both parents on the implantation index and expression of talin, occludin and E-cadherin in the uterine epithelial cells (UEC) of the offspring. Pregnant Wistar dams (F0) received BPA or vehicle from gestational day (GD) 6 to lactation day 21. F1 animals were mated forming four groups: Control dam-Control sire (C♀-C♂), BPA dam -Control sire (B♀-C♂), Control dam -BPA sire (C♀-B♂), BPA dam -BPA sire (B♀-B♂). F1 dams were sacrificed at GD 6. Significantly decreased number of implantation sites was observed in the B♀-B♂ group as compared to the C♀-C♂ group, which correlated with decreased talin apical/basal expression ratio, occludin apical expression, and E-cadherin apical/lateral expression ratio in the UEC. Furthermore, decreased E-cadherin expression in the blastocyst was observed. Our data suggest that reduced protein expressions in F1 BPA offspring could result from decreased progesterone serum levels.