Reproductive Alterations in Chronically Exposed Female Mice to Environmentally Relevant Doses of a Mixture of Phthalates and Alkylphenols

Folliculogenesis and steroidogenesis alterations after chronic exposure to a human-relevant mixture of environmental toxicants spare the ovarian reserve in the rabbit model

BACKGROUND

Industrial progress has led to the omnipresence of chemicals in the environment of the general population, including reproductive-aged and pregnant women. The reproductive function of females is a well-known target of endocrine-disrupting chemicals. This function holds biological processes that are decisive for the fertility of women themselves and for the health of future generations. However, insufficient research has evaluated the risk of combined mixtures on this function. This study aimed to assess the direct impacts of a realistic exposure to eight combined environmental toxicants on the critical process of folliculogenesis.

METHODS

Female rabbits were exposed daily and orally to either a mixture of eight environmental toxicants (F group) or the solvent mixture (NE group, control) from 2 to 19 weeks of age. The doses were computed from previous toxicokinetic data to reproduce steady-state serum concentrations in rabbits in the range of those encountered in pregnant women. Ovarian function was evaluated through macroscopic and histological analysis of the ovaries, serum hormonal assays and analysis of the expression of steroidogenic enzymes. Cellular dynamics in the ovary were further investigated with Ki67 staining and TUNEL assays.

RESULTS

F rabbits grew similarly as NE rabbits but exhibited higher total and high-density lipoprotein (HDL) cholesterol levels in adulthood. They also presented a significantly elevated serum testosterone concentrations, while estradiol, progesterone, AMH and DHEA levels remained unaffected. The measurement of gonadotropins, androstenedione, pregnenolone and estrone levels yielded values below the limit of quantification. Among the 7 steroidogenic enzymes tested, an isolated higher expression of Cyp19a1 was measured in F rabbits ovaries. Those ovaries presented a significantly greater density/number of antral and atretic follicles and larger antral follicles without any changes in cellular proliferation or DNA fragmentation. No difference was found regarding the count of other follicle stages notably the primordial stage, the corpora lutea or AMH serum levels.

CONCLUSION

Folliculogenesis and steroidogenesis seem to be subtly altered by exposure to a human-like mixture of environmental toxicants. The antral follicle growth appears promoted by the mixture of chemicals both in their number and size, potentially explaining the increase in atretic antral follicles. Reassuringly, the ovarian reserve estimated through primordial follicles number/density and AMH is spared from any alteration. The consequences of these changes on fertility and progeny health have yet to be investigated.

Levels, distribution, sources and human exposure pathways of alkylphenol and alkylphenol ethoxylates in indoor dust in Turkiye

Environmental phenolic chemicals, due to their widespread occurrence and potent estrogenic properties, pose a risk to human exposure. The phenolic organic contaminants alkylphenols (APs) and alkylphenol polyethoxylates (APEs) are used in various household applications, and they may enter to the environment during production and use, potentially appearing in indoor dust. However, little is known about the levels of environmental phenolics in indoor environments. In this study, five of these compounds namely octylphenol (OP), 4-Octylphenol Monoethoxylate (4-OPME), 4-tert-octylphenol (4-t-OP), 4-n-nonylphenol (4-n-NP) and nonylphenol diethoxylate (di-NPE) were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in household dust samples (n = 148) collected from Ankara, the capital of Turkiye. OP and 4-OPME was not present in any of the analyzed samples. The median concentrations of the 148 settling dust samples were 35, 520, and 1910 ng g-1 dust for 4-t-OP, 4-n-NP, and di-NPE, respectively. An assessment of the human (children and adults) exposure pathway to APs and APEs, which are recognized as endocrine-disrupting chemicals found in residential dust, revealed that it was approximately 3 times higher for children than for adults at both moderate and heavy exposure levels. The association between chemical exposure, house characteristics, and family lifestyle was investigated using a multivariate logistic regression model. According to the results of this model, while the high concentrations measured for 4-t-OP were not found to be associated with any of the household parameters, high levels of 4-n-NP and di-NPE were associated with the frequency of house cleaning, repairs made during the previous year, residential type, the number of occupants, flooring materials, and the purchase of new household items within the past year. This study provides a basis for prioritizing toxicology and exposure studies for EDCs and mixtures and may offer new tools for exposure assessment in health studies.

Molecularly imprinted polymers (MIPs) as efficient catalytic tools for the oxidative degradation of 4-nonylphenol and its by-products

Water pollution is a current global concern caused by emerging pollutants like nonylphenol (NP). This endocrine disruptor cannot be efficiently removed with traditional wastewater treatment plants (WTPs). Therefore, this work aimed to evaluate the adsorption influence of molecularly imprinted polymers (MIPs) on the oxidative degradation (ozone and ultraviolet irradiations) of 4-nonylphenol (4-NP) and its by-products as a coadjuvant in WTPs. MIPs were synthesized and characterized; the effect of the degradation rate under system operating conditions was studied by Box-Behnken response surface design of experiments. The variables evaluated were 4-NP concentration, ozone exposure time, pH, and MIP amount. Results show that the MIPs synthesized by co-precipitation and bulk polymerizations obtained the highest retention rates (> 90%). The maximum adsorption capacities for 4-NP were 201.1 mg L-1 and 500 mg L-1, respectively. The degradation percentages under O3 and UV conditions reached 98-100% at 120 s of exposure at different pHs. The degradation products of 4-NP were compounds with carboxylic and ketonic acids, and the MIP adsorption was between 50 and 60%. Our results present the first application of MIPs in oxidation processes for 4-NP, representing starting points for the use of highly selective materials to identify and remove emerging pollutants and their degradation by-products in environmental matrices.

The role of endocrine disruptors in female infertility

INTRODUCTION

 According to the World Health Organization, infertility is a public health problem that affects around 48 million couples and 186 million individuals worldwide. Endocrine disruptors are one of the causes that raise more concern, given that it is a problem that has evolved with the progress of society. Many chemicals are used by food industry, entering food chain, and directly affecting human health. Endocrine disruptors have the capacity of interfering with the normal hormonal action, metabolism, and biosynthesis, which can lead to a variation of the normal hormonal homeostasis. Some of these endocrine disruptors are highly associated with diseases that are positively correlated with female infertility, such as polycystic ovary syndrome, endometriosis, irregular menstrual cycle and also disturbances on processes as steroidogenesis and development of the ovarian follicles.

RESULTS

The present literature review covers various aspects of the possible relationship between endocrine disruptors and female infertility. Bisphenol A and its metabolites, phthalates, dioxins, organochlorine, and organophosphate compounds are groups of chemicals considered to have the capacity to disrupt endocrine activity and herein addressed. The results reported in in vivo studies and in clinical trials addressing endocrine disruptors and female infertility were discussed as well as their possible mechanism of action.

CONCLUSIONS

Large, double-blind, placebo-controlled randomized clinical trials are needed to better understand the mechanisms of action of endocrine disruptors in female infertility, as well as the doses and frequency of exposure responsible for it.

Gestational dibutyl phthalate exposure impairs primordial folliculogenesis in mice through autophagy activation and NOTCH2 signal interruption

Female reproductive lifespan is largely determined by the size of the primordial follicle pool, which is established in early life. Dibutyl phthalate (DBP), a popular plasticiser, is a known environmental endocrine disruptor that poses a potential threat to reproductive health. However, DBP impact on early oogenesis has been rarely reported. In this study, maternal exposure to DBP in gestation disrupted germ-cell cyst breakdown and primordial follicle assembly in foetal ovary, impairing female fertility in adulthood. Subsequently, altered autophagic flux with autophagosome accumulation was observed in DBP-exposed ovaries carrying CAG-RFP-EGFP-LC3 reporter genes, whereas autophagy inhibition by 3-methyladenine attenuated the impact of DBP on primordial folliculogenesis. Moreover, DBP exposure reduced the expression of NOTCH2 intracellular domain (NICD2) and decreased interactions between NICD2 and Beclin-l. NICD2 was observed within the autophagosomes in DBP-exposed ovaries. Furthermore, NICD2 overexpression partially restored primordial folliculogenesis. Furthermore, melatonin significantly relieved oxidative stress, decreased autophagy, and restored NOTCH2 signalling, consequently reversing the effect on folliculogenesis. Therefore, this study demonstrated that gestational DBP exposure disrupts primordial folliculogenesis by inducing autophagy, which targets NOTCH2 signalling, and this impact has long-term consequences on fertility in adulthood, strengthening the potential contribution of environmental chemicals to the development of ovarian dysfunctional diseases.

Cumulative Exposure to Phthalates and Their Alternatives and Associated Female Reproductive Health: Body Burdens, Adverse Outcomes, and Underlying Mechanisms

The global birth rate has recently shown a decreasing trend, and exposure to environmental pollutants has been identified as a potential factor affecting female reproductive health. Phthalates have been widely used as plasticizers in plastic containers, children's toys, and medical devices, and their ubiquitous presence and endocrine-disrupting potential have already raised particular concerns. Phthalate exposure has been linked to various adverse health outcomes, including reproductive diseases. Given that many phthalates are gradually being banned, a growing number of phthalate alternatives are becoming popular, such as di(isononyl) cyclohexane-1,2-dicarboxylate (DINCH), di(2-ethylhexyl) adipate (DEHA), and di(2-ethylhexyl) terephthalate (DEHTP), and they are beginning to have a wide range of environmental effects. Studies have shown that many phthalate alternatives may disrupt female reproductive function by altering the estrous cycle, causing ovarian follicular atresia, and prolonging the gestational cycle, which raises growing concerns about their potential health risks. Herein, we summarize the effects of phthalates and their common alternatives in different female models, the exposure levels that influence the reproductive system, and the effects on female reproductive impairment, adverse pregnancy outcomes, and offspring development. Additionally, we scrutinize the effects of phthalates and their alternatives on hormone signaling, oxidative stress, and intracellular signaling to explore the underlying mechanisms of action on female reproductive health, because these chemicals may affect reproductive tissues directly or indirectly through endocrine disruption. Given the declining global trends of female reproductive capacity and the potential ability of phthalates and their alternatives to negatively impact female reproductive health, a more comprehensive study is needed to understand their effects on the human body and their underlying mechanisms. These findings may have an important role in improving female reproductive health and in turn decreasing the number of complications during pregnancy.

Phthalate toxicity mechanisms: An update

Phthalates are one of the most widely used plasticizers in polymer products, and they are increasingly being exposed to people all over the world, generating health concerns. Phthalates are often used as excipients in controlled-release capsules and enteric coatings, and patients taking these drugs may be at risk. In both animals and human, phthalates are mainly responsible for testicular dysfunction, ovarian toxicity, reduction in steroidogenesis. In this regard, for a better understanding of the health concerns corresponding to phthalates and their metabolites, still more research is required. Significantly, multifarious forms of phthalates and their biomedical effects are need to be beneficial to investigate in the various tissues or organs. Based on these investigations, researchers can decipher their toxicity concerns and related mechanisms in the body after phthalate's exposure. This review summarizes the chemical interactions, mechanisms, and their biomedical applications of phthalates in animals and human.

Widening the Lens on Prothioconazole and Its Metabolite Prothioconazole-Desthio: Aryl Hydrocarbon Receptor-Mediated Reproductive Disorders through in Vivo, in Vitro, and in Silico Studies

Reproductive disorders are a serious public health problem worldwide. Epidemiological data suggest that exposure to environmental pollutants is associated with the onset of reproductive disorders. However, the effects in reproductive health and exact mechanism of action of representative agricultural compounds prothioconazole (PTC) and its metabolite prothioconazole-desthio (dPTC) on mammals remain unclear. Here, we studied the physiological effects of the exposure to environmentally relevant doses of PTC and dPTC in mice reproductive systems. Combining in vivo, in vitro, and in silico studies, we observed that PTC and dPTC disrupt reproductive health by inducing metabolic perturbation, induction of apoptosis, and inflammation in gonadal tissue, which are achieved via activation of the aryl hydrocarbon receptor (AhR). Convincingly, the addition of alternate-day injections of CH223191 (an AhR inhibitor) to the 30-day exposure regimen ameliorated ovarian tissue damage, as evidenced by decreased TUNEL-positive cells and partially restored the inflammation and apoptotic factor levels. This study comprehensively reports the toxic effects of low-dose PTC and dPTC in the reproductive system in vivo and identifies AhR as a potential therapeutic target for the amelioration of reproductive disorders caused by similar endocrine-disrupting chemicals.

Impact of environmental phthalate on human health and their bioremediation strategies using fungal cell factory- A review

Phthalates are utilized as plasticizers in plastic products to enhance their durability, transparency, and elasticity. However, phthalates are not covalently bonded to the polymer matrix of the phthalate-containing products and can be gradually released into the environment through biogeochemical processes. Hence, phthalates are now pervasive in our environment, including our food. Reports suggested that phthalates exposure to the mammalian systems is linked to various health consequences. It has become vital to develop highly efficient strategies to reduce phthalates from the environment. In this context, the utilization of fungi for phthalate bioremediation (mycoremediation) is advantageous due to their highly effective enzyme secretory system. Extracellular and intracellular enzymes of fungi are believed to break down the phthalates by ester hydrolysis to produce phthalic acid and alcohol, and subsequent digestion of the benzene rings of phthalic acid and their metabolites. The present review scrutinizes and highlights the knowledge gap in phthalate prevalence, exposure to mammals, and associated human health challenges. Furthermore, discusses the role of fungi and their secretory enzymes in the biodegradation of phthalates and gives a perspective to better describe and tackle this continuous threat.

Relationship between exposure of alkylphenols in serum of pregnant women during early pregnancy and adverse birth outcomes

Alkylphenols are a type of endocrine disruptors, which are commonly found in personal care products, food, and water and are more harmful to the human body. To investigate the relationship between exposure of alkylphenols in serum of pregnant women during early pregnancy and adverse birth outcomes, a total of 2035 healthy pregnant women and their neonates were recruited in the birth cohort of Zhuang nationality in Guangxi from 2015 to 2018. The peripheral venous blood samples were collected from pregnant women in early pregnancy; the concentrations of nonylphenol (NP), 4-nonylphenol (4-N-NP), 4-tert-octylphenol (4-T-OP), and 4-n-octylphenol (4-N-OP) in serum were detected by ultra-performance liquid performance chromatography-tandem mass spectrometry (UPLC-MS). Binary logistic regression showed that NP [OR = 1.40 (95% CI: 1.00, 1.94)] was positively associated with preterm birth. Restricted cubic spline analyses showed that logNP and log4-T-OP had non-linearity associations with preterm birth (logNP: P_overall = 0.006, P_non-linear = 0.003; log4-T-OP: P_overall = 0.004, P_non-linear = 0.002). Multiple linear regression analysis showed that maternal serum concentration of NP was negatively associated with birth weight of perinatal infants (β = -14.68, 95% CI: -29.18, -0.19), which may be sensitive in male neonates (β = -26.18, 95% CI: -47.33, -5.02). The findings demonstrate that nonylphenol is a risk factor of preterm birth, and nonylphenol is negatively associated with the birth weight in male infants.

Maternal Perinatal Exposure to Dibutyl Phthalate Promotes Ovarian Dysfunction in Adult Female Offspring via Downregulation of TGF-β2 and TGF-β3

Maternal exposure to dibutyl phthalate (DBP) may result in ovarian dysfunction in female offspring. However, the underlying mechanisms remain elusive. Pregnant Sprague-Dawley rats were intraperitoneally injected with different doses of DBP, estradiol, and corn oil from gestational day 7 until the end of lactation. The reproductive characteristics, mRNA, and protein expression of ovaries for the adult female offspring were compared. KGN cells were cultured in vitro with DBP, estrogen receptor antagonist, or ALK-5 inhibitor. Genes, proteins, estradiol, and progesterone expressed by KGN, cell proliferation, and apoptosis were measured respectively. Maternal perinatal exposure to DBP induced prolonged estrous period, increased secondary follicles, significant decreased mRNA, and protein levels of TGF-β2, TGF-β3, and TGF-βRII in ovaries of the adult female offspring, but none difference for serum levels of sex hormones, ovarian TGF-β1, and estrogen receptor. The mRNA levels of LHR, FSHR, and CYP19a in ovaries were also decreased. DBP might decrease the mRNA of TGF-β2, TGF-β3, and TGF-βR II of KGN. DBP can inhibit the mRNA of CYP19 at 24 h, which might be blocked by the estrogen receptor antagonist, whose effects were attenuated at 48 h. DBP combined with FSH might time-dependently regulate the gene expression of TGF-βR II, inhibitory at 24 h, but stimulative at 48 h, which could be blocked by the ALK5 inhibitor. However, the protein expressed by KGN was not influenced by DBP. DBP stimulated the proliferation of KGN at 24 h, which could be blocked by estrogen receptor antagonist, but attenuated at 48 h. The progesterone in culture medium secreted by KGN was decreased by DBP at 24 h. Maternal perinatal exposure to DBP induced decreased gene expression of TGF-β signaling and functional proteins in ovaries of the adult female offspring. Molecular cross-talk between estrogen receptor and TGF-β signaling pathway may play role in the mechanism of granulosa dysfunction induced by DBP.

Identifying Environmental Endocrine Disruptors Associated With the Age at Menarche by Integrating a Transcriptome-Wide Association Study With Chemical-Gene-Interaction Analysis

Menarche is the first occurrence of menstrual bleeding and one of the most important events of female puberty. Alarmingly, over the last several decades, the mean age at menarche (AAM) has decreased. Environmental endocrine disruptors (EEDs) are chemicals that may interfere with the endocrine system, resulting in adverse developmental, immunological, neurological, and reproductive effects in humans. Thus, the effects of EEDs on fertility and reproduction are growing concerns in modern societies. In this study, we aimed to determine the influence of genetic and environmental factors on AAM. We used data from an AAM genome-wide association study of 329,345 women to conduct a transcriptome-wide association study (TWAS) with FUSION software. As references, we determined the gene-expression levels in the hypothalamus, pituitary gland, ovaries, uterus, and whole blood. We performed Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses using the significantly dysregulated genes identified by the TWAS. Using the STRING database, we also generated a protein-protein-interaction network to analyze common AAM-specific genes identified by the TWAS with different tissues. We performed chemical-related gene set enrichment analysis (CGSEA) and identified significant TWAS genes to uncover relationships between different chemicals and AAM. The TWAS identified 9,848 genes; among these, 1580 genes were significant (P < 0.05), and 11 genes were significant among the hypothalamus, pituitary, ovary, uterus, and whole blood. CGSEA identified 1,634 chemicals, including 120 chemicals significantly correlated with AAM. In summary, we performed a TWAS (for genetic factors) and CGSEA (for environmental factors) focusing on AAM and identified several AAM-associated genes and EEDs. The results of this study expand our understanding of genetic and environmental factors related to the onset of female puberty.

Removal efficiencies and risk assessment of endocrine-disrupting chemicals at two wastewater treatment plants in South China

Endocrine-disrupting chemicals (EDCs) in the effluent from wastewater treatment plants (WWTPs) are an important pollutant sources of the aquatic system. In this study, the removal efficiencies of eight typical EDCs at two domestic WWTPs in Dongguan City, China, are reported based on instrumental analysis and bioassay results. Bioactivities, including steroidogenesis-disrupting effects, estrogen receptor (ER)-binding activity, and aryl hydrocarbon receptor (AhR)-binding activity were evaluated using the H295R, MVLN, and H4IIE cell bioassays, respectively. The potential environmental risks of these residual EDCs were also evaluated. The results of instrumental analysis showed that nonylphenol was the major chemical type present among the eight tested EDCs. Meanwhile, concentrations of estrogen compounds including estrone, 17β-estradiol (E2), estriol, 17α-ethinyl estradiol, and diethylstilbestrol were relatively low. The removal rates of all eight EDCs were relatively high. Although the chemical analysis indicated high removal efficiency, the bioassay results showed that steroidogenesis-disrupting effects as well as ER-binding and AhR-binding activities remained, with E2-equivalent values of effluent samples ranging from 0.16 to 0.9 ng·L^-1, and 2,3,7,8-tetrachlorodibenzo-p-dioxin-equivalent values ranging from 0.61 to 4.09 ng L^-1. Principal component analysis combined with regression analysis suggests that the chemicals analyzed in this study were partly responsible for these ER and AhR activities. Ecological risk assessment of the residual EDCs showed that estrone was the most hazardous chemical among the eight EDCs tested, with a risk quotient of 1.44-5.50. Overall, this study suggests that, despite high apparent removal efficiencies of typical EDCs, their bioactivities and potential ecological risks cannot be ignored.

Review of endocrine disruptors on male and female reproductive systems

Endocrine disruptors (EDs) interfere with different hormonal and metabolic processes and disrupt the development of organs and tissues, as well as the reproductive system. In toxicology research, various animal models have been utilized to compare and characterize the effects of EDs. We reviewed studies assessing the effect of ED exposure in humans, zebrafish, and mouse models and the adverse effects of EDs on male and female reproductive systems. This review outlines the distinctive morphological characteristics, as well as gene expression, factors, and mechanisms that are known to occur in response to EDs. In each animal model, disturbances in the reproductive system were associated with certain factors of apoptosis, the hypothalamic-pituitary-gonadal axis, estrogen receptor pathway-induced meiotic disruption, and steroidogenesis. The effects of bisphenol A, phthalate, and 17α-ethinylestradiol have been investigated in animal models, each providing supporting outcomes and elaborating the key regulators of male and female reproductive systems.

Intermittent fasting ameliorates di-(2-ethylhexyl) phthalate-induced precocious puberty in female rats: A study of the hypothalamic-pituitary-gonadal axis

Di-(2-ethylhexyl) phthalate has been reported to interfere with the development and function of animal reproductive systems. However, hardly any studies provide methods to minimize or prevent the adverse effects of DEHP on reproduction. The energy balance state of mammals is closely related to reproductive activities, and the reproductive axis can regulate reproductive activities according to changes in the body's energy balance state. In this study, the effects of every other day fasting (EODF), as a way of intermittent fasting, on preventing the precocious puberty induced by DEHP in female rats was studied. EODF significantly improved the advancement of vaginal opening age (as the markers of puberty onset) and elevated serum levels of luteinizing hormone and estradiol (detected by ELISA) induced by 5 mg kg^-1 DEHP exposure (D5). The mRNA and western blot results showed that the EODF could minimized the increase of gonadotropin-releasing hormone expression induced by DEHP exposure. The administration of DEHP could elevate the levels of kisspeptin protein and the number of kisspeptin-immunoreactive neurons in anteroventral periventricular nucleu, and this increase was diminished considerably by EODF treatment. In contrast, the D5 and D0 groups showed no remarkable difference in the level of Kiss1 expression in arcuate nucleus, whereas the D5 + EODF group had a remarkable decrease in kisspeptin expression as compared with the other two groups. Our results indicated that EODF might inhibit the acceleration of puberty onset induced by DEHP exposure via HPG axis.

Risks associated with cosmetic ingredients

The media and social networks often echo fears about the potential toxicity of cosmetics and the dangers they pose to the environment. Dermatologists may be asked about these topics, but despite regulatory labelling constraints and the proliferation of specialized sites and applications, they do not always have access to reliable information. It is for this reason that we are providing the present overview of current knowledge on the subject.

Endocrine Disruption of the Follicle-Stimulating Hormone Receptor Signaling During the Human Antral Follicle Growth

An increasing number of pollutants with endocrine disrupting potential are accumulating in the environment, increasing the exposure risk for humans. Several of them are known or suspected to interfere with endocrine signals, impairing reproductive functions. Follicle-stimulating hormone (FSH) is a glycoprotein playing an essential role in supporting antral follicle maturation and may be a target of disrupting chemicals (EDs) likely impacting female fertility. EDs may interfere with FSH-mediated signals at different levels, since they may modulate the mRNA or protein levels of both the hormone and its receptor (FSHR), perturb the functioning of partner membrane molecules, modify intracellular signal transduction pathways and gene expression. In vitro studies and animal models provided results helpful to understand ED modes of action and suggest that they could effectively play a role as molecules interfering with the female reproductive system. However, most of these data are potentially subjected to experimental limitations and need to be confirmed by long-term observations in human.

Endocrine disrupting chemicals and reproductive disorders in women, men, and animal models

This chapter covers the known effects of endocrine disrupting chemicals (EDCs) on reproductive disorders. The EDCs represented are highly studied, including plasticizers (bisphenols and phthalates), chemicals in personal care products (parabens), persistent environmental contaminants (polychlorinated biphenyls), and chemicals in pesticides or herbicides. Both female and male reproductive disorders are reviewed in the chapter. Female disorders include infertility/subfertility, irregular reproductive cycles, early menopause, premature ovarian insufficiency, polycystic ovarian syndrome, endometriosis, and uterine fibroids. Male disorders include infertility/subfertility, cryptorchidism, and hypospadias. Findings from both human and animal studies are represented.

Hypothetical roadmap towards endometriosis: prenatal endocrine-disrupting chemical pollutant exposure, anogenital distance, gut-genital microbiota and subclinical infections

BACKGROUND

Endometriosis is a gynaecological hormone-dependent disorder that is defined by histological lesions generated by the growth of endometrial-like tissue out of the uterus cavity, most commonly engrafted within the peritoneal cavity, although these lesions can also be located in distant organs. Endometriosis affects ~10% of women of reproductive age, frequently producing severe and, sometimes, incapacitating symptoms, including chronic pelvic pain, dysmenorrhea and dyspareunia, among others. Furthermore, endometriosis causes infertility in ~30% of affected women. Despite intense research on the mechanisms involved in the initial development and later progression of endometriosis, many questions remain unanswered and its aetiology remains unknown. Recent studies have demonstrated the critical role played by the relationship between the microbiome and mucosal immunology in preventing sexually transmitted diseases (HIV), infertility and several gynaecologic diseases.

OBJECTIVE AND RATIONALE

In this review, we sought to respond to the main research question related to the aetiology of endometriosis. We provide a model pointing out several risk factors that could explain the development of endometriosis. The hypothesis arises from bringing together current findings from large distinct areas, linking high prenatal exposure to environmental endocrine-disrupting chemicals with a short anogenital distance, female genital tract contamination with the faecal microbiota and the active role of genital subclinical microbial infections in the development and clinical progression of endometriosis.

SEARCH METHODS

We performed a search of the scientific literature published until 2019 in the PubMed database. The search strategy included the following keywords in various combinations: endometriosis, anogenital distance, chemical pollutants, endocrine-disrupting chemicals, prenatal exposure to endocrine-disrupting chemicals, the microbiome of the female reproductive tract, microbiota and genital tract, bacterial vaginosis, endometritis, oestrogens and microbiota and microbiota-immune system interactions.

OUTCOMES

On searching the corresponding bibliography, we found frequent associations between environmental endocrine-disrupting chemicals and endometriosis risk. Likewise, recent evidence and hypotheses have suggested the active role of genital subclinical microbial infections in the development and clinical progression of endometriosis. Hence, we can envisage a direct relationship between higher prenatal exposure to oestrogens or estrogenic endocrine-disrupting compounds (phthalates, bisphenols, organochlorine pesticides and others) and a shorter anogenital distance, which could favour frequent postnatal episodes of faecal microbiota contamination of the vulva and vagina, producing cervicovaginal microbiota dysbiosis. This relationship would disrupt local antimicrobial defences, subverting the homeostasis state and inducing a subclinical inflammatory response that could evolve into a sustained immune dysregulation, closing the vicious cycle responsible for the development of endometriosis.

WIDER IMPLICATIONS

Determining the aetiology of endometriosis is a challenging issue. Posing a new hypothesis on this subject provides the initial tool necessary to design future experimental, clinical and epidemiological research that could allow for a better understanding of the origin of this disease. Furthermore, advances in the understanding of its aetiology would allow the identification of new therapeutics and preventive actions.

Exposure to endocrine disruptor alkylphenols and the occurrence of endometrial cancer

Exposure to environmental chemicals with oestrogenic effects has been associated with the development of endometrial cancer (EMCa). EMCa has become the most commonly diagnosed cancer of the female genital tract. To further understand the potential association between exposure to environmental endocrine disruptors and the occurrence of EMCa, we performed a case-control study between 2011 and 2014. We aimed to detect and compare concentrations of a known hormone disruptor, alkylphenol, between women diagnosed with either EMCa or uterine leiomyoma, and those who did not have either of these. Subjects were women diagnosed with either EMCa or uterine leiomyoma (LM) and healthy controls. A structured questionnaire was administered to collect information on lifestyle and health status. Gas chromatography/mass spectrometry was used to measure urinary NP and OP concentrations in participants. Multiple regression analysis was used to examine the association between exposure and outcomes. Overall, 397 women were recruited, including 49 with EMCa, 247 with LM, and 101 controls. Among them, 73.6% showed detectable levels of NP and 61.0% showed detectable levels of OP. The EMCa group had a significantly higher NP concentration than the control group. Higher OP concentrations were also found in participants with EMCa than those with LM and controls. In addition, women in the upper tertile of the NP group had a significantly increased risk of EMCa occurrence (odds ratio [95% confidence interval] = 4.47 [1.69-11.84] for EMCa vs. control). The same was found in the group of women with more than the median level of OP (odds ratio [95% confidence interval] = 4.32 [2.01-9.30] for EMCa vs. LM). Stratification of pre- and post-menopausal groups resulted in a similar association. The results show that NP/OP exposure is associated with EMCa. Further investigations and exposure minimisation are suggested.

Female Fertility and Environmental Pollution

A realistic picture of our world shows that it is heavily polluted everywhere. Coastal regions and oceans are polluted by farm fertilizer, manure runoff, sewage and industrial discharges, and large isles of waste plastic are floating around, impacting sea life. Terrestrial ecosystems are contaminated by heavy metals and organic chemicals that can be taken up by and accumulate in crop plants, and water tables are heavily contaminated by untreated industrial discharges. As deadly particulates can drift far, poor air quality has become a significant global problem and one that is not exclusive to major industrialized cities. The consequences are a dramatic impairment of our ecosystem and biodiversity and increases in degenerative or man-made diseases. In this respect, it has been demonstrated that environmental pollution impairs fertility in all mammalian species. The worst consequences are observed for females since the number of germ cells present in the ovary is fixed during fetal life, and the cells are not renewable. This means that any pollutant affecting hormonal homeostasis and/or the reproductive apparatus inevitably harms reproductive performance. This decline will have important social and economic consequences that can no longer be overlooked.

Effects and Mechanisms of Phthalates' Action on Reproductive Processes and Reproductive Health: A Literature Review

The production of plastic products, which requires phthalate plasticizers, has resulted in the problems for human health, especially that of reproductive health. Phthalate exposure can induce reproductive disorders at various regulatory levels. The aim of this review was to compile the evidence concerning the association between phthalates and reproductive diseases, phthalates-induced reproductive disorders, and their possible endocrine and intracellular mechanisms. Phthalates may induce alterations in puberty, the development of testicular dysgenesis syndrome, cancer, and fertility disorders in both males and females. At the hormonal level, phthalates can modify the release of hypothalamic, pituitary, and peripheral hormones. At the intracellular level, phthalates can interfere with nuclear receptors, membrane receptors, intracellular signaling pathways, and modulate gene expression associated with reproduction. To understand and to treat the adverse effects of phthalates on human health, it is essential to expand the current knowledge concerning their mechanism of action in the organism.

Updates on molecular and environmental determinants of luteal progesterone production

Progesterone, a critical hormone in reproduction, is a key sex steroid in the establishment and maintenance of early pregnancy and serves as an intermediary for synthesis of other steroid hormones. Progesterone production from the corpus luteum is a tightly regulated process which is stimulated and maintained by multiple factors, both systemic and local. Multiple regulatory systems, including classic mediators of gonadotropin stimulation such as the cAMP/PKA pathway and TGFβ-mediated signaling pathways, as well as local production of hormonal factors, exist to promote granulosa cell function and physiological fine-tuning of progesterone levels. In this manuscript, we provide an updated narrative review of the known mediators of human luteal progesterone and highlight new observations regarding this important process, focusing on studies published within the last five years. We will also review recent evidence suggesting that this complex system of progesterone production is sensitive to disruption by exogenous environmental chemicals that can mimic or interfere with the activities of endogenous hormones.

Emerging pollutants (EPs) in Latin América: A critical review of under-studied EPs, case of study -Nonylphenol

Emerging contaminants (EPs) represent a significant risk to human, ecological and environmental health. Although progress has been made in establishing monitoring in environmental matrices, health effects, legislation and control, there are still problems associated with regional bias and the types of EPs commonly assessed, which may underestimate the risk to health. In Latin America there are limited reports on environmental monitoring of EPs and it is generally focused on wastewater. This review identifies the current research deficiencies for emerging contaminants in the Latin American region, and we address the case of nonylphenol as an under-studied EP in the region. Nonylphenol is a degradation product of nonylphenol ethoxylate, which is a surfactant widely used in the manufacture of detergents in Latin America, environmental concentrations have been reported, predominantly in water, and the possible effects on species in this region have been also described. The importance of the review of this compound in the region lies in the fact that the Rotterdam Convention has catalogued nonylphenol as a severely restricted compound, so it is necessary to establish measures for its restriction and change to a sustainable technology. Finally, the example of NP presented in this review highlights the lack of regulation in Latin America regarding to EPs, resulting in the contamination of wastewater, effluents, rivers and drinking water. It is imperative to determine the potential effects, occurrence and concentration levels to improve the regulation of these pollutants in a timely manner.

Acute uterine effects and long-term reproductive alterations in postnatally exposed female rats to a mixture of commercial formulations of endosulfan and glyphosate

Endosulfan and glyphosate are widely used pesticides and have been associated to reproductive disorders. We examine the acute and long-term effects of postnatal exposure to commercial formulations of endosulfan (EF), glyphosate (glyphosate-based herbicide, GBH) and a mixture of both pesticides (MIX). After birth, female pups of Wistar rats received saline solution (CONTROL), EF (600 μg/kg of b.w/day), GBH (2 mg/kg of b.w/day) or a mixture (at the same doses) from postnatal day (PND) 1 to PND7. The uterine histology and expression of Hoxa10, estrogen (ERα) and progesterone (PR) receptors were evaluated on PND8. Reproductive performance was evaluated on gestational day 19. GBH and MIX rats showed an increment of 1) the incidence of luminal epithelial hyperplasia, 2) PR and Hoxa10 expression. EF modified ERα and Hoxa10 expression. During adulthood, MIX and GBH rats showed higher post-implantation losses while EF alone produced an increase of pre-implantation losses. We showed that the co-administration of both pesticides produced acute uterine effects and long-term deleterious reproductive effects that were similar to those induced by GBH alone. We consider important to highlight the necessity to evaluate the commercial pesticide mixture as a more representative model of human exposure to a high number of pesticides.

Adverse Effect of Nonylphenol on the Reproductive System in F1 Male Mice: A Subchronic Low-Dose Exposure Model

Nonylphenols (NPs) are widely used industrial materials, and are considered as potent endocrine disrupting chemical. Present study was undertaken to clarify the effect of subchronic low-dose NP exposure to F1 generation male mice. Mice were divided into 2 groups; (1) CON, control animals and (2) NP-50 (50 μg/L), animals were treated with NP via drinking water. NP exposures were continuously conducted from parental pre-mating period until the postnatal day (PND) 55 of F1 offsprings. Mice were sacrificed on PND 55 and the tissue weights were measured. The initial body weights (at PND 21) and terminal body weights (PND 55) of the NP-50 animals were significantly lower than those of control animals (p<0.05). NP exposure induced a significant increase in the absolute weight of the testes (p<0.05). Conversely, the NP exposure caused significant decrease in the absolute weights of the epididymis (p<0.01), prostate (p<0.05) and seminal vesicle (p<0.05). Histopathological studies revealed that NP-treated animals exerted decreased seminiferous tubule diameters, reduced luminal area, and lower number of germ cells. Also some sloughing morphologies in the tubules were observed. In the caudal epididymis, fewer mature sperms and swollen epithelial cells were found in the NP-treated group. Our results confirmed that the subchronic low-dose NP exposure altered some male parameters and induced histopathological abnormalities in testis and epididymis of F1 mice. Since the NP dose used in this study is close to the average human daily NP exposure, our results could provide practically meaningful understanding of adverse effect of EDC in human.

Associations of Phthalates and Phthalate Replacements With CRH and Other Hormones Among Pregnant Women in Puerto Rico

CONTEXT

Phthalates are endocrine-disrupting chemicals that may be associated with adverse birth outcomes. Dysregulation of maternal endocrine homeostasis could be a possible biological pathway between phthalates and birth outcomes.

OBJECTIVE

Examine associations between 19 maternal urinary phthalate or phthalate replacement metabolites and 9 serum hormones measured over two time points during pregnancy.

DESIGN

Longitudinal study conducted in the PROTECT pregnancy cohort.

SETTING

Puerto Rico.

PATIENTS

Six hundred seventy-seven women in the first trimester of pregnancy.

MAIN OUTCOME MEASURES SERUM

CRH, estriol, SHBG, progesterone, TSH, total T3, free T4, total T4, and testosterone.

RESULTS

T3 was significantly associated with most metabolites. CRH was inversely associated with mono carboxyisononyl phthalate [MCNP; percent change (%Δ), -4.08; 95% CI, -7.24, -0.804], mono-3-carboxypropyl phthalate (MCPP; %Δ, -5.25; 95% CI, -8.26, -2.14), mono-2-ethyl-5-carboxypentyl phthalate (MECPP; %Δ, -18.4; 95% CI, -30.4, -4.37), mono-2-ethyl-5-hydroxyhexyl phthalate (MEHHP; %Δ, -13.4; 95% CI, -22.7, -2.92), and mono-2-ethyl-5-oxohexyl phthalate (MEOHP; %Δ, -12.7; 95% CI, -22.2, -2.20). Positive associations were found between numerous phthalate metabolites and free T4, T4, and the T3/T4 ratio. Testosterone was positively associated with mono hydroxybutyl phthalate (MHBP; %Δ, 4.71; 95% CI, 0.27, 9.35) and inversely associated with monoethyl phthalate (MEP; %Δ, -14.5; 95% CI, -24.3, -3.42), and relationships with MCNP and mono carboxyisooctyl phthalate (MCOP) were significantly modified by study visit. Finally, an inverse association was found between mono-2-ethyl-5-hydrohexyl terephthalate (MEHHTP), a terephthalate metabolite, and progesterone at visit 3 only (%Δ, -13.1; 95% CI, -22.3, -2.75).

CONCLUSIONS

These results indicate that exposure to phthalates may differentially impact the maternal endocrine system at different points during pregnancy, and that exposures to phthalate replacement chemicals may be particularly important to consider in future human health studies.

Gestational exposure to an epidemiologically defined mixture of phthalates leads to gonadal dysfunction in mouse offspring of both sexes

The increasing concern for the reproductive toxicity of abundantly used phthalates requires reliable tools for exposure risk assessment to mixtures of chemicals, based on real life human exposure and disorder-associated epidemiological evidence. We herein used a mixture of four phthalate monoesters (33% mono-butyl phthalate, 16% mono-benzyl phthalate, 21% mono-ethyl hexyl phthalate, and 30% mono-isononyl phthalate), detected in 1st trimester urine of 194 pregnant women and identified as bad actors for a shorter anogenital distance (AGD) in their baby boys. Mice were treated with 0, 0.26, 2.6 and 13 mg/kg/d of the mixture, corresponding to 0x, 10x, 100x, 500x levels detected in the pregnant women. Adverse outcomes detected in the reproductive system of the offspring in pre-puberty and adulthood included reduced AGD index and gonadal weight, changes in gonadal histology and altered expression of key regulators of gonadal growth and steroidogenesis. Most aberrations were apparent in both sexes, though more pronounced in males, and exhibited a non-monotonic pattern. The phthalate mixture directly affected expression of steroidogenesis as demonstrated in a relevant in vitro model. The detected adversities at exposures close to the levels detected in pregnant women, raise concern on the existing safety limits for early-life human exposures and emphasizes the need for re-evaluation of the exposure risk.

Antigen retrieval by citrate solution improves western blot signal

In the present work, we describe and evaluate an additional step to the standard western blot protocol to increase signal strength after revealing. Weak or absence of signal is a common issue in western blot protocol leading to unexpected results. In our Antigen Retrieval for Western Blot Method (ARWB method), after transfer, the membrane was incubated in a citrate buffer following normal antigen retrieval procedure used for immunohistochemistry. Later, standard protocol was performed in order to reveal and compare with unexposed membranes to this antigen retrieval step. Signal in bands obtained by the modified protocol resulted significantly higher (in all 13 antibodies analyzed) compared to standard protocol. Some bands were only visible after citrate incubation. This method is a simple and economical way to improve results in western blot analysis.

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The ARWB method significantly increases band’s density in all antibodies analyzed.

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Protein localization does not influence the efficacy of the ARWB method since membrane and citoplasmatic proteins bands increase their signal in a similar way after the protocol is performed.

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This ARWB method is simple, safe, economical and undoubtedly helpful in immunoblotting for proteins with weak signal.

Endocrine-disrupting metabolites of alkylphenol ethoxylates - A critical review of analytical methods, environmental occurrences, toxicity, and regulation

Despite the fact that metabolites of alkylphenol ethoxylates (APEO) are classified as hazardous substances, they continue to be released into the environment from a variety of sources and are not usually monitored. Their wide use has led to an increase in the possible exposure pathways for humans, which is cause for alarm. Moreover, there is a lack of knowledge about the behaviour of these metabolites with respect to the environment and toxicity, and their biological effects on human health. The aim of this work is to give an overview of the APEO metabolites and their analysis, occurrences and toxicity in various environmental and human samples. APEO metabolites have adverse effects on humans, wildlife, and the environment through their release into the environment. Currently, there are some reviews available on the behaviour of alkylphenols in soil, sediments, groundwater, surface water and food. However, none of these articles consider their toxicity in humans and especially their effect on the nervous and immune system. This work summarises the environmental occurrences of metabolites of APEOs in matrices, e.g. water, food and biological matrices, their effect on the immune and nervous systems, and isomer-specific issues. With that emphasis we are able to cover most common occurrences of human exposure, whether direct or indirect.

Bisphenol-A and Nonylphenol Induce Apoptosis in Reproductive Tract Cancer Cell Lines by the Activation of ADAM17

Endocrine-disruptor chemicals (EDCs), such as bisphenol A (BPA) and nonylphenol (NP), have been widely studied due to their negative effects on human and wildlife reproduction. Exposure to BPA or NP is related to cell death, hormonal deregulation, and cancer onset. Our previous studies showed that both compounds induce A Disintegrin And Metalloprotease 17 (ADAM17) activation. Here, we show that BPA and NP induce apoptosis in prostate and ovary cancer cell lines, in a process dependent on ADAM17 activation. ADAM17 knockdown completely prevented apoptosis as well as the shedding of ADAM17 substrates. Both compounds were found to induce an increase in intracellular calcium (Ca²⁺) only in Ca²⁺-containing medium, with the NP-treated cells response being more robust than those treated with BPA. Additionally, using a phosphorylated protein microarray, we found that both compounds stimulate common intracellular pathways related to cell growth, differentiation, survival, and apoptosis. These results suggest that BPA and NP could induce apoptosis through ADAM17 by activating different intracellular signaling pathways that may converge in different cellular responses, one of which is apoptosis. These results confirm the capacity of these compounds to induce cell apoptosis in cancer cell lines and uncover ADAM17 as a key regulator of this process in response to EDCs.

Current Knowledge on Endocrine Disrupting Chemicals (EDCs) from Animal Biology to Humans, from Pregnancy to Adulthood: Highlights from a National Italian Meeting

Wildlife has often presented and suggested the effects of endocrine disrupting chemicals (EDCs). Animal studies have given us an important opportunity to understand the mechanisms of action of many chemicals on the endocrine system and on neurodevelopment and behaviour, and to evaluate the effects of doses, time and duration of exposure. Although results are sometimes conflicting because of confounding factors, epidemiological studies in humans suggest effects of EDCs on prenatal growth, thyroid function, glucose metabolism and obesity, puberty, fertility, and on carcinogenesis mainly through epigenetic mechanisms. This manuscript reviews the reports of a multidisciplinary national meeting on this topic.