Endocrine disrupting chemicals and their effects on the reproductive health in men

Sex-specific associations of the endocrine-disrupting chemicals with serum neurofilament light chain among US adults

OBJECTIVE

Endocrine-disrupting chemicals (EDCs) can interfere with endocrine function and lead to neurological damage. Neurofilament light chain (NfL) is a protein released into the blood after neuroaxonal damage, and it has become a dependable biomarker for neurological conditions. The study aimed to investigate the associations between single or combined EDCs exposure and serum NfL levels in adults.

METHODS

The 1372 participants included in the study were from the 2013-2014 National Health and Nutrition Examination Survey. Due to the difference in types of EDCs, participants were divided into two populations. Multiple linear regression models were used to assess the association between 32 EDCs and NfL. The least absolute shrinkage and selection operator regression model was used for EDCs selection and the weighted quantile sum (WQS) regression was used for examining the association of EDCs mixture with NfL and identify the predominant exposure.

RESULTS

Levels of urinary bisphenol S, mono(2-ethylhexyl) phthalate, dibutyl phosphate, glyphosate, and 3,5,6-trichloropyridinol were positively associated with serum NfL levels, while benzophenone-3, methylparaben, and propylparaben showed negative associations. In the WQS regression model, the changes of NfL were 0.154 (95 % CI: 0.014-0.294) and 0.164 (95 % CI: 0.033-0.296) for each quartile increase in WQS index of EDCs mixture in the two populations, respectively. Analysis of the subgroup with gender stratification suggested that the association between EDCs mixture and NfL was only significant in men. The positive mixture β was 0.219 (95 % CI: 0.056-0.380) and 0.257 (95 % CI: 0.082-0.433) in the two population, respectively.

CONCLUSION

The study suggested a potential association between single or combined exposure to EDCs and NfL levels. High-level EDCs exposure might be associated with more severe neurological damage, particularly in men.

Bio-monitoring of endocrine disrupting chemicals in human serum: insights from a study in Central India

In recent years, the health impacts of phthalates and bisphenol-A (BPA) have garnered significant research attention due to their widespread use in consumer products and identification as endocrine disrupting chemicals (EDCs). Human exposure occurs through various pathways, including dietary intake, inhalation of dust, and dermal contact. This study initially aimed to analyze serum samples from 200 participants in Jabalpur city (Central India); however, samples from 173 individuals were ultimately analyzed to assess the occurrence, concentration patterns, and gender-related differences of six phthalates and BPA. Serum samples were collected, processed, and analyzed for EDC content using gas chromatography coupled with mass spectrometry. The findings highlighted differences in detection frequencies among genders and residential areas, shaped by environmental exposure variability, lifestyle variations, and gender-specific metabolic disparities. All the targeted analytes were detected with diethyl phthalate (DEP) having the highest mean concentration of 13.74 ± 6.2 ng/ml, followed by di(2-ethylhexyl) phthalate (DEHP) with mean value of 13.69 ± 99.82 ng/ml in human serum. Studies have linked DEP exposure endocrine disruption and reproductive abnormalities. Subsequent research endeavors should prioritize elucidating EDC sources, pathways, and health impacts, facilitating evidence-based policies to mitigate risks and ensure a healthier future.

Relationship between anogenital distance and testicular position in male infants with cryptorchidism with and without hypospadias

PURPOSE

Anogenital distance (AGD) may indicate hypoverilization and subsequently serve as a predictor future reproduction. In both undescended testis with and without hypospadias, our goal was to study the relationship between testicular position and AGD.

METHODS

From March 2021 to January 2023, this study was conducted on male infants with and without hypospadias and age-matched controls. Based on the infants' ages, we divided them into four. Group I: under six months, Group II: 7-12 months, Group III: between a year and eighteen months, and Group IV: 19 months up to two years of age. From the verge of the anus to the penile base, the AGD was measured. Clinical examination resulted in the classification of testicular location as high scrotal, inguinal, and non-palpable.

RESULTS

Patients with cryptorchidism had AGD means that were substantially lower than those of controls in Groups I, II, III, and IV, respectively (31 ± 2, 33 ± 3), (35.9 ± 4, 37.9 ± 5), (39.9 ± 1.2, 41 ± 1.5), and (40 ± 1.9, 44 ± 1.7). The group of patients with cryptorchidism and hypospadias differed significantly from the controls and those without hypospadias. AGD in patients with upper scrotal locations was substantially shorter. Penile length and AGD of the examined groups exhibited a positive and significant connection.

CONCLUSIONS

Shorter AGD is linked to a higher prevalence of hypospadias and cryptorchidism in male babies in comparison to normal children. The position of the undescended testis is higher in relation to a shorter AGD.

Sulforaphane substantially impedes testicular ferroptosis in adult rats exposed to di-2-ethylhexyl phthalate through activation of NRF-2/SLC7A11/GPX-4 trajectory

Di-2-ethylhexyl phthalate (DEHP) is a common plasticizer with a deleterious impact on testicular functionality and male fertility. Growing evidence implicates ferroptosis as one of the plausible mechanisms for DEHP-induced testicular injury. Sulforaphane (SFN) is a natural isothiocyanate displaying beneficial effects on testicular injury in several animal models. Herein, we explored the potential protective effect of SFN on testicular ferroptosis and toxicity evoked by DEHP. Adult male Wistar rats were equally distributed into three groups (n = 6/group): (i) CON group; (ii) DEHP group, received DEHP (2 g/kg PO) for 4 weeks; and (iii) DEHP + SFN group, received SFN (10 mg/kg, PO) 1 week prior to DEHP then concurrently with DEHP for further 4 weeks. Compared to CON group, exposure to DEHP caused testicular atrophy, deteriorated testicular architecture, testicular fibrosis, reduced sperm count and motility, higher sperm deformity, and declined serum testosterone level. All these abnormalities were ameliorated by SFN preconditioning. Additionally, pretreatment with SFN reversed the increased aromatase level and upregulated the steroidogenic markers in testes of DEHP-exposed rats. SFN pretreatment also counteracted DEHP-induced oxidative stress and boosted the total antioxidant capacity in testicular tissue via activation of the nuclear factor erythroid 2-related factor 2 (NRF-2) and its downstream target, hemeoxygenase-1 (HO-1). Moreover, SFN preconditioning mitigated DEHP-induced ferroptosis through up-surging SLC7A11, GPX-4, and GSH, while suppressing iron overload and ACSL4-induced lipid peroxidation in testicular tissue of rats. These findings may nominate SFN as a promising protective intervention to alleviate testicular ferroptosis associated with DEHP exposure through activation of NRF-2/SLC7A11/GPX-4 trajectory.

Paternal DEHP Exposure Triggers Reproductive Toxicity in Offspring via Epigenetic Modification of H3K27me3

Di (2-ethylhexyl) phthalate (DEHP) is an acknowledged endocrine disruptor with male reproductive toxicity; nevertheless, the transgenerational impacts on male offspring resulting from paternal exposure, along with the mechanisms involved, are not well understood. To develop a transgenerational model of DEHP paternal exposure, male C57BL/6J mice (4-week) exposed to DEHP (5, 250, and 500 mg/kg/d) for 35 days were then bred with unexposed female mice at a ratio of 1:2 to produce offspring. Findings indicate that the sperm quality and relative sex hormones were adversely affected in males of F1 and F2 generations, and pathological damage in the testes and the apoptosis of testicular cells were also observed. Interestingly, an increase in the expression levels of H3K27me3 was observed in the testicular tissues of male descendants. It was further confirmed by in vitro approach that H3K27me3 may down-regulate the expression of Bcl-2 and plays a role in regulating the initiation of apoptosis in Leydig cells triggered by MEHP (the primary metabolite of DEHP). Additionally, the down-regulation of Bcl-2 can be reversed by treatment with the H3K27me3 inhibitor GSK126. To conclude, DEHP leads to transgenerational harm to male offspring reproductive systems, with the epigenetic mechanism of H3K27me3 playing a key role in mediating these effects.

Novel Method for Simultaneously Untargeted Metabolome and Targeted Exposome Analysis in One Injection

Serum endogenous metabolites and coexisting exogenous compounds are closely related to human health. Metabolomics often uses high-resolution mass spectrometry (HRMS), but current exposomics studies typically rely on triple quadrupole tandem mass spectrometry due to lower concentrations in the body. As a result, metabolome-exposome-wide association studies (mEWAS) require a combination of untargeted metabolomics and several targeted exposomics methods to measure more exposures, leading to increased time and sample consumption. In this study, a novel method was proposed by leveraging the advantages of recently introduced Zeno MRMHR technology; it allows for the simultaneous acquisition of the metabolome in HRMS and the exposome in multiple reaction monitoring (MRM) modes in one injection. The signal responses for exogenous compounds in MRM were comparable to those of metabolites in HRMS. This method was rigorously validated, and all exogenous standards had relative standard deviations (RSDs) below 20% for intraday and interday repeatability. Over 90% of metabolic features exhibited RSDs below 20% in these assessments. The method also had a broad quantification range, with lower limits of quantification (LLOQ) from 0.1 to 25 ng/mL and higher limits of quantification (HLOQ) from 2.5 to 1000 ng/mL. This approach was demonstratively applied to a type 2 diabetes mellitus cohort to identify serum risk factors and study the metabolome-exposome association. To our knowledge, this study is the first implementation of a unified method for the simultaneous analysis of endogenous metabolites in the untargeted mode and 210 exogenous compounds in the targeted mode in one injection, offering a novel tool for mEWAS research.

Exploiting the synergistic effect of β-cyclodextrin functionalized-multi-walled carbon nanotubes and Zn-MOF for the detection of endocrine-disrupting chemical methylparaben

BACKGROUND

The buildup of methylparaben (MP), a broad-spectrum antimicrobial preservative with endocrine-disrupting properties, in environmental sources, especially aquatic systems, has become a significant concern due to its adverse health effects, including allergic reactions, promoting the risk of developing cancer, and inducing reproductive disorders. Hence, introducing inexpensive and easy-to-use monitoring devices for rapid, selective, and sensitive detection and quantification of MP is highly desirable. In this context, electrochemical platforms have proven to be attractive options due to their remarkable features, such as ease of fabrication and use, short response time, and acceptable sensitivity, accuracy, and selectivity.

RESULTS

In this regard, Zn-BTC metal-organic framework (MOF) and multi-walled carbon nanotubes (MWCNTs) functionalized with β-Cyclodextrin (β-CD) were utilized to modify the matrix of a carbon paste electrode (CPE). The morphological and electrochemical characteristics of β-CD-MWCNTs/Zn-BTC/CPE were evaluated using conventional material characterization techniques and electroanalytical methods. The sensor exhibited two linear current responses in concentration ranges of 0.01 mM-0.3 mM and 0.3 mM-6 mM. The limit of detection (LOD) and limit of quantification (LOQ) were calculated to be 3.8 μM and 11.5 μM, respectively. The device demonstrated excellent selectivity, repeatability, reproducibility, and stability over two weeks. Evaluating its applicability in real samples, including personal care products, tap and river water, and human blood serum, achieved recoveries in the range of 96.25 %-105 %, proving its reliability in environmental and industrial applications.

SIGNIFICANCE

Overall, the proposed modified graphitic platform is not only a cheaper and more easily fabricable and applicable option for MP detection compared to other reported conventional and electrochemical devices but also demonstrates exceptional selectivity and satisfactory sensitivity among various reported electrochemical sensors. In addition, the developed electroanalytical tool can be employed for MP measurement in a broader range of real sample matrixes compared to alternative electrochemical platforms.

Association between volatile organic compounds exposure and infertility risk among American women aged 18-45 years from NHANES 2013-2020

The risk of infertility is progressively escalating over the years, and it has been established that exposure to environmental pollutants is closely linked to infertility. As a prevalent environmental pollutant in daily life, there is still a lack of substantial evidence on the association between volatile organic compounds (VOCs) exposure and infertility risk. This study aimed to examine the association between VOCs exposure and the risk of female infertility in the United States. Participant data sets from three cycles (2013-2020) were collected and downloaded from the National Health and Nutrition Examination Survey (NHANES), including demographics, examination, laboratory and questionnaire data. The baseline characteristics of the included population were evaluated, and the weighted quartile logistic regression was used to analyze the association between the urinary metabolites of VOCs (mVOCs) levels and the risk of infertility. Further exploration of the relationship between mVOCs and infertility was conducted by using 35 and 25 as the cut-off points for age and BMI subgroup analyses, respectively. Restricted cubic spline (RCS) was employed to elucidate the nonlinear relationship between mVOCs and infertility risk. Additionally, the Bayesian kernel machine regression (BKMR) model with 20,000 iterations was applied to elucidate the link between mVOCs and the risk of infertility when exposed to mixed or individual mVOCs. A total of 1082 women aged 18 to 45 years were included in this study, with 133 in the infertility group and 949 in the control group. The analysis of baseline characteristics suggested that urinary 34MHA, AMCC and DHBMA levels were significantly higher in the infertility group compared to the control group (p < 0.05). Quartile logistic regression analysis indicated that AAMA (Q3), AMCC (Q4), CYMA (Q3) and HPMMA (Q3) were positively associated with infertility risk in all models (p < 0.05). Subgroup analysis revealed different risk factors for infertility among various subgroups, with CYMA consistently showing a positive correlation with infertility risk in two age subgroups (p < 0.05). Furthermore, the association between mVOCs and infertility was observed only in the subgroup with BMI ≥ 25 kg/m2. RCS analysis indicated that 2MHA, ATCA, BMA, BPMA, CYMA, 2HPMA, 3HPMA and PGA exhibited linear dose-response relationships with infertility (p > 0.05), while the remaining variables showed nonlinear relationships (p < 0.05). The BKMR model demonstrated that the risk of female infertility exhibited an increasing trend with the accumulation of mVOCs co-exposure. A positive association between the exposure to mVOCs represented by 34MHA and AMCC and the risk of infertility was observed in this research. However, the inherent limitations associated with the cross-sectional study design necessitate the pursuit of additional prospective and experimental research to further elucidate and validate the relationships between various mVOCs exposure and female infertility.

Environmentally-relevant doses of bisphenol A and S exposure in utero disrupt germ cell programming across generations resolved by single nucleus multi-omics

Background

Exposure to endocrine-disrupting chemicals (EDCs), such as bisphenol A (BPA), disrupts reproduction across generations. Germ cell epigenetic alterations are proposed to bridge transgenerational reproductive defects resulting from EDCs. Previously, we have shown that prenatal exposure to environmentally relevant doses of BPA or its substitute, BPS, caused transgenerationally maintained reproductive impairments associated with neonatal spermatogonial epigenetic changes in male mice. While epigenetic alterations in germ cells can lead to transgenerational phenotypic variations, the mechanisms sustaining these changes across generations remain unclear.

Objectives

This study aimed to systematically elucidate the mechanism of transgenerational inherence by prenatal BPA and BPS exposure in the murine germline from F1 to F3 generations at both transcriptomic and epigenetic levels.

Methods

BPA or BPS with doses of 0 (vehicle control), 0.5, 50, or 1000 μg/kg/b.w./day was orally administered to pregnant CD-1 females (F0) from gestational day 7 to birth. Sperm counts and motility were examined in F1, F2, and F3 adult males. THY1+ germ cells on postnatal day 6 from F1, F2, and F3 males at a dose of 50 μg/kg/b.w./day were used for analysis by single-nucleus (sn) multi-omics (paired snRNA-seq and snATAC-seq on the same nucleus).

Results

Prenatal exposure to BPA and BPS with 0.5, 50, and 1000 μg/kg/b.w./day reduced sperm counts in mice across F1 to F3 generations. In the F1 neonatal germ cells, ancestral BPA or BPS exposure with 50 μg/kg/b.w./day resulted in increased differentially expressed genes (DEGs) associated with spermatogonial differentiation. It also disrupted the balance between maintaining the undifferentiated and differentiating spermatogonial populations. Differentially accessible peaks (DAPs) by snATAC-seq were primarily located in the promoter regions, with elevated activity of key transcription factors, including SP1, SP4, and DMRT1. Throughout F1-F3 generations, biological processes related to mitosis/meiosis and metabolic pathways were substantially up-regulated in BPA- or BPS-exposed groups. While the quantities of DEGs and DAPs were similar in F1 and F2 spermatogonia, with both showing a significant reduction in F3. Notably, approximately 80% of DAPs in F1 and F2 spermatogonia overlapped with histone post-translational modifications linked to transcription activation, such as H3K4me1/2/3 and H3K27ac. Although BPA exerted more potent effects on gene expression in F1 spermatogonia, BPS induced longer-lasting effects on spermatogonial differentiation across F1 to F3 males. Interestingly, DMRT1 motif activity was persistently elevated across all three generations following ancestral BPA or BPS exposure.

Discussion

Our work provides the first systematic analyses for understanding the transgenerational dynamics of gene expression and chromatin landscape following prenatal exposure to BPA or BPS in neonatal spermatogonia. These results suggest that prenatal exposure to environmentally relevant doses of BPA or BPS alters chromatin accessibility and transcription factor motif activities, consequently contributing to disrupted transcriptional levels in neonatal germ cells, and some are sustained to F3 generations, ultimately leading to the reduction of sperm counts in adults.

The potential mechanisms underlying phthalate-induced hypospadias: a systematic review of rodent model studies

Objectives

Maternal exposure to environmental endocrine disruptors, such as phthalates, during pregnancy is a significant risk factor for the development of hypospadias. By consolidating existing research on the mechanisms by which phthalates induce hypospadias in rodent models, this systematic review aims to organize and analyze the discovered mechanisms and their potential connections.

Methods

The study involved all articles that explored the mechanisms of phthalate-induced hypospadias using rodent models. A comprehensive search of the PubMed and Web of Science databases was conducted using the terms "hypospadias" and "phthalates" before January 20, 2024. Then, two investigators screened for studies worthy of inclusion by setting inclusion and exclusion criteria.

Results

Of the initial 326 search results, 22 were included in the subsequent analysis. Based on the commonalities among different results, the mechanisms of phthalate-induced hypospadias could be categorized into the following five groups: sex steroids-related signaling pathways (n=10), epithelial-mesenchymal transition (n=6), autophagy (n=5), apoptosis (n=4) and angiogenesis (n=2). Among these, sex steroids-related signaling pathways might serve as a central regulator among all mechanisms, and reactive oxygen species (ROS) also played an important mediating role.

Conclusion

The systematic review indicates that phthalates may initially disrupt the balance of sex steroids-related pathways, leading to abnormally elevated levels of ROS and subsequently to other functional abnormalities, ultimately resulting in the development of hypospadias. All these findings will help to improve prevention strategies during pregnancy to reduce the adverse effects of phthalates on the offspring.

Combined effects and potential mechanisms of phthalate metabolites on serum sex hormones among reproductive-aged women: An integrated epidemiology and computational toxicology study

The reproductive age is a crucial stage for women to bear offspring. However, reproductive-aged women are simultaneously exposed to various phthalates, which may pose a threat to their reproductive health. This study employed generalized linear regression and weighted quantile sum (WQS) regression to explore the associations between monoesters of phthalates (MPAEs) and sex hormones in 913 reproductive-aged women in the National Health and Nutrition Examination Survey. Key risk factors driving hormone disruption were identified based on the weights of the WQS models. Interaction models were used to unravel the synergistic or antagonistic effects between MPAEs. The potential toxicological targets of MPAEs interfering with sex hormone-binding globulin (SHBG) levels were revealed based on prior knowledge and molecular docking of hepatocyte nuclear factor 4α (HNF4α). Compared with the first quartile, mono-benzyl phthalate (MBZP) in the second quartile exhibited a decrease in total testosterone (TT) and TT/E2 (estradiol) ratio. Mono-2-ethyl-5-carboxypentyl phthalate (MECPP) in the fourth quartile showed a decrease in SHBG and TT/E2. Additionally, mono-(carboxyoctyl) phthalate and mono-(carboxynonyl) phthalate (MCNP) were negatively associated with SHBG. Each unit increase in the WQS index of MPAE mixtures was associated with 6.73 % lower SHBG levels (95 %CI: -12.80 %, -0.24 %) with mono-(3-carboxypropyl) phthalate, MCNP, MBZP, and MECPP identified as major risk factors. Interaction analyses revealed that the effects of high-risk MPAEs on SHBG were predominantly antagonistic. Molecular docking suggested that MPAEs might compete to bind tryptophan residues of HNF4α. This study provides key information to help develop the most effective phthalate interventions and improve the reproductive health of reproductive-aged women.

The associations between exposure to mixed environmental endocrine disruptors and sex steroid hormones in men: a comparison of different statistical models

In recent years, worldwide fertility rates have continued to decrease. Humans are frequently exposed to a combination of environmental endocrine disruptors, which can cause male reproductive disorders. The study employed three distinct analytical models to examine the correlation between exposure to a combination of 25 chemicals and sex steroid hormone levels in adult males. This involved evaluating 12 chemicals and their metabolites from personal care and consumer products, as well as 13 metabolites linked to phthalates and plasticisers. The study analysed 25 chemicals and 3 measured sex steroid hormone outcomes, as well as two calculated hormonal outcomes (free androgen index, TT/E2 ratio) in 1262 adult men who participated in the National Health and Nutrition Examination Survey (NHANES) 2013-2016 in the United States. The study employed several statistical methods to estimate the relationships between single chemicals or chemical blends and sex hormones. These methods included linear regression, weighted quantile sum (WQS) regression, and Bayesian kernel machine (BKMR) regression. The results of the linear regression analysis indicate that chemical exposure has a negative correlation with E2, TT, and FAI, and a positive correlation with SHBG and TT/E2. The mixture effect analyses using the WQS and BKMR models further confirmed that BP3, MECPP, and MECOP were the most highly weighted chemical mixtures. The analyses also suggested that there were differences in the effects of different concentrations of EDCs on sex steroid hormones. Exposure to environmental endocrine-disrupting chemicals (EDCs) has been found to have a negative correlation with estradiol and total testosterone, as well as FAI. Conversely, this exposure has been found to have a positive correlation with sex hormone binding globulin and the TT/E2 ratio. The study also revealed differences in the effects of different concentrations of EDCs.

Metal-oxide nanocatalysts for spontaneous sequestration of endocrine-disrupting compounds from wastewater

The quest for a good life, urbanization, and industrialization have led to the widespread distribution of endocrine-disrupting chemicals (EDCs) in water bodies through anthropogenic activities. This poses an imminent threat to both human and environmental health. In recent years, the utilization of advance materials for the removal of EDCs from wastewater has attracted a lot of attention. Metal-oxide nanocatalysts have emerged as promising candidates due to their high surface area, reactivity, and tunable properties, as well as enhanced surface properties such as mesoporous structures and hierarchical morphologies that allow for increased adsorption capacity, improved photocatalytic activity, and enhanced selectivity towards specific EDCs. As a result, they have shown extraordinary efficacy in removing a wide range of EDCs from aqueous solutions, including pharmaceuticals, agrochemicals, personal care items, and industrial chemicals. This study give insight into the unique physicochemical characteristics of metal-oxide nanocatalysts to effectively and efficiently remove harmful EDCs from wastewater. It also discussed the advances in the synthesis, and properties of metal-oxide nanocatalysts, and insight into understanding the fundamental mechanisms underlying the adsorption and degradation of EDCs on metal-oxide nanocatalysts using advanced characterization techniques such as spectroscopic analysis and electron microscopy. The findings of the study present metal-oxide nanocatalysts as a good candidate for the spontaneous sequestration of EDCs from wastewater is an intriguing approach to mitigating water pollution and safeguarding public health and the environment.

Reproductive toxicology: keeping up with our changing world

Reproductive toxicology testing is essential to safeguard public health of current and future generations. Traditional toxicological testing of male reproduction has focused on evaluating substances for acute toxicity to the reproductive system, with fertility assessment as a main endpoint and infertility a main adverse outcome. Newer studies in the last few decades have significantly widened our understanding of what represents an adverse event in reproductive toxicology, and thus changed our perspective of what constitutes a reproductive toxicant, such as endocrine disrupting chemicals that affect fertility and offspring health in an intergenerational manner. Besides infertility or congenital abnormalities, adverse outcomes can present as increased likelihood for various health problems in offspring, including metabolic syndrome, neurodevelopmental problems like autism and increased cancer predisposition, among others. To enable toxicologic studies to accurately represent the population, toxicologic testing designs need to model changing population characteristics and exposure circumstances. Current trends of increasing importance in human reproduction include increased paternal age, with an associated decline of nicotinamide adenine dinucleotide (NAD), and a higher prevalence of obesity, both of which are factors that toxicological testing study design should account for. In this perspective article, we highlighted some limitations of standard testing protocols, the need for expanding the assessed reproductive endpoint by including genetic and epigenetic sperm parameters, and the potential of recent developments, including mixture testing, novel animal models, in vitro systems like organoids, multigenerational testing protocols, as well as in silico modelling, machine learning and artificial intelligence.

Mono-2-ethylhexyl phthalate-induced downregulation of MMP11 in foreskin fibroblasts contributes to the pathogenesis of hypospadias

Hypospadias is one of the most common congenital anomalies of the male urogenital system, and di(2-ethylhexyl) phthalate (DEHP), a widely used endocrine-disrupting chemical (EDC), is considered a significant risk factor for this condition. Mono-2-ethylhexyl phthalate (MEHP), the toxic active metabolite of DEHP, has been proven to affect penile development and ultimately result in the hypospadias phenotype. However, while it is acknowledged that hypospadias arises from the aberrant development of multiple penile tissues, the specific impact of MEHP on human foreskin tissue development and its underlying molecular mechanisms of action remain unclear. In this study, we constructed an in vitro toxicity assay for MEHP using human foreskin fibroblasts and employed high-throughput RNA sequencing to investigate the molecular mechanisms subserving the defects in cellular function. We subsequently conducted multi-omics data analysis using public databases to analyze key target genes, and identified MMP11 as a chief downstream gene responsible for the effects of MEHP on HFF-1 cell migration. Through molecular docking analysis and molecular biology experiments, we further demonstrated that the nuclear receptor PPAR-gamma was activated upon binding with MEHP, leading to the suppression of MMP11 expression. Additionally, we found that epigenetic modifications induced by MEHP were also involved in its pathogenic effects on hypospadias. Our research highlights the crucial role of impaired cellular proliferation and migration in MEHP-induced hypospadias. We identified the MEHP/PPAR-gamma/MMP11 pathway as a novel pathogenic mechanism, providing important potential targets for future preventive strategies with respect to hypospadias.

Association between spectrum of mycotoxins and semen quality: A cross-sectional study in Beijing, China

Exposure to mycotoxins is unavoidable in daily life through ingestion, dermal, and inhalation routes. Toxicological studies found that exposure to mycotoxins might affect male reproductive function. However, there is still a lack of population evidence. We aimed to assess the association of individual and joint exposure to spectrum of mycotoxins with semen quality. The present study included 192 participants in Beijing, China. We measured conventional semen parameters and assessed semen quality. Sixty-seven traditional or emerging mycotoxins were determined to describe the spectrum of mycotoxins. The participants were widely exposed to multiple mycotoxins, and nearly half were simultaneously exposed to more than six mycotoxins. After adjusting potential confounders, logistic regression indicated that the number and concentration of plasma mycotoxin were correlated to the risk of low semen quality. Plasma beauvericin and citrinin concentrations were associated with lower semen quality. The least absolute shrinkage and selection operator regression showed similar results to logistic regression. Quantile-based g-computation and Bayesian kernel machine regression models found that the mixture of mycotoxins was harmful to semen quality, especially in sperm motility. In conclusion, both individual and mixture of mycotoxin exposure were correlated with lower semen quality. More regulations and measures should be taken to reduce mycotoxin contamination.

Resorcinol as "endocrine disrupting chemical": Are thyroid-related adverse effects adequately documented in reptiles? In vivo experimentation in lizard Podarcis siculus

The endocrine system and particularly thyroid hormones regulate almost all physiological processes in a timely manner in all vertebrates, from fish to reptiles to mammals, so risk assessment of endocrine disrupting chemicals (EDCs) is extremely important given their persistent presence in all environmental matrices. Resorcinol, as well as nonylphenol, octylphenol, and bisphenol A, F, S, are non-Halogenated Phenolic (non-HPCs) Chemicals known as EDCs. Resorcinol is a particular example in that most studies are based exclusively on humans while animal studies are few and often inadequate. The aim of this study was to assess the effects of exposure to different doses of resorcinol on the thyroid gland of the lizard Podarcis siculus during different periods of the thyroid gland activity cycle. Our results showed histopathologic changes in thyroid (follicular cell height increase and colloid area decrease), a thyroid weight increase in combination with serum T4 and T3 decrease, serum TSH, TRH increase in male lizards treated with 0.8,3.9,13.1, and 36.9 mg/kg/d of resorcinol. Besides, we also investigated the impacts of resorcinol treatments on hepatic 5'ORD (type II) deiodinase and hepatic content of T3 and T4. Our findings showed that they are in agreement with in vivo in humans and in rodents data and therefore, resorcinol in reptiles may meet the WHO definition of ECDs.

Paternal exposures to endocrine-disrupting chemicals induce intergenerational epigenetic influences on offspring: A review

Endocrine-disrupting chemicals (EDCs) are ubiquitous in ecological environments and have become a great issue of public health concern since the 1990 s. There is a deep scientific understanding of the toxicity of EDCs. However, recent studies have found that the abnormal physiological functions of the parents caused by EDCs could be transmitted to their unexposed offspring, leading to intergenerational toxicity. We questioned whether sustained epigenetic changes occur through the male germline. In this review, we (1) systematically searched the available research on the intergenerational impacts of EDCs in aquatic and mammal organisms, including 42 articles, (2) summarized the intergenerational genetic effects, such as decreased offspring survival, abnormal reproductive dysfunction, metabolic disorders, and behavioral abnormalities, (3) summarized the mechanisms of intergenerational toxicity through paternal interactions, and (4) propose suggestions on future research directions to develop a deeper understanding of the ecological risk of EDCs.

Occurrence and Health Risk Assessment of Phthalates in Municipal Drinking Water Supply of a Central Indian City

In this study, the occurrence of phthalates in the municipal water supply of Nagpur City, India, was studied for the first time. The study aimed to provide insights into the extent of phthalate contamination and identify potential sources of contamination in the city's tap water. We analyzed fifteen phthalates and the total concentration (∑15phthalates) ranged from 0.27 to 76.36 µg L-1. Prominent phthalates identified were di-n-butyl phthalate (DBP), di-isobutyl phthalate (DIBP), benzyl butyl phthalate (BBP), di (2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (DNOP), and di-nonyl phthalate (DNP). Out of the fifteen phthalates analyzed, DEHP showed the highest concentration in all the samples with the median concentration of 2.27 µg L-1, 1.39 µg L-1, 1.83 µg L-1, 2.02 µg L-1, respectively in Butibori, Gandhibaag, Civil Lines, and Kalmeshwar areas of the city. In 30% of the tap water samples, DEHP was found higher than the EPA maximum contaminant level of 6 µg L-1. The average daily intake (ADI) of phthalates via consumption of tap water was higher for adults (median: 0.25 µg kg-1 day-1) compared to children (median: 0.07 µg kg-1 day-1). The hazard index (HI) calculated for both adults and children was below the threshold level, indicating no significant health risks from chronic toxic risk. However, the maximum carcinogenic risk (CR) for adults (8.44 × 10-3) and children (7.73 × 10-3) was higher than the threshold level. Knowledge of the sources and distribution of phthalate contamination in municipal drinking water is crucial for effective contamination control and management strategies.

Genistein prevents the production of hypospadias induced by Di-(2-ethylhexyl) phthalate through androgen signaling and antioxidant response in rats

Environmental estrogen exposure has increased dramatically over the past 50 years. In particular, prenatal exposure to estrogen causes many congenital diseases, among which reproductive system development disorders are extremely serious. In this study, the molecular mechanism of hypospadias and the therapeutic effect of genistein (GEN) were investigated through in vivo models prepared by Di-(2-ethylhexyl) phthalate (DEHP) exposure between 12 and 19 days of gestation. With increased DEHP concentrations, the incidence of hypospadias increased gradually. DEHP inhibited the key enzymes involved in steroid synthesis, resulting in decreasing testosterone synthesis. At the same time, DEHP increased reactive oxygen species (ROS) and produced inflammatory factors via NADPH oxidase-1 (NOX1) and NADPH oxidase-4 (NOX4) pathways. It also inhibited Steroid 5 α Reductase 2 (Srd5α2) and decreased dihydrotestosterone (DHT) synthesis. Additionally, DEHP inhibited the androgen receptor (AR), resulting in reduced DHT binding to the AR that ultimately retarded the development of the external reproductive system. GEN, a phytoestrogen, competes with DEHP for binding to estrogen receptor β (ERβ). This competition, along with GEN's antiestrogen and antioxidant properties, could potentially reverse impairments. The findings of this study provide valuable insights into the role of phytoestrogens in alleviating environmental estrogen-induced congenital diseases.

Phthalate metabolites and sex steroid hormones in relation to obesity in US adults: NHANES 2013-2016

Background

Obesity and metabolic syndrome pose significant health challenges in the United States (US), with connections to disruptions in sex hormone regulation. The increasing prevalence of obesity and metabolic syndrome might be associated with exposure to phthalates (PAEs). Further exploration of the impact of PAEs on obesity is crucial, particularly from a sex hormone perspective.

Methods

A total of 7780 adult participants in the National Health and Nutrition Examination Survey (NHANES) from 2013 to 2016 were included in the study. Principal component analysis (PCA) coupled with multinomial logistic regression was employed to elucidate the association between urinary PAEs metabolite concentrations and the likelihood of obesity. Weighted quartiles sum (WQS) regression was utilized to consolidate the impact of mixed PAEs exposure on sex hormone levels (total testosterone (TT), estradiol and sex hormone-binding globulin (SHBG)). We also delved into machine learning models to accurately discern obesity status and identify the key variables contributing most to these models.

Results

Principal Component 1 (PC1), characterized by mono(2-ethyl-5-carboxypentyl) phthalate (MECPP), mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), and mono(2-ethyl-5-oxohexyl) phthalate (MEOHP) as major contributors, exhibited a negative association with obesity. Conversely, PC2, with monocarboxyononyl phthalate (MCNP), monocarboxyoctyl phthalate (MCOP), and mono(3-carboxypropyl) phthalate (MCPP) as major contributors, showed a positive association with obesity. Mixed exposure to PAEs was associated with decreased TT levels and increased estradiol and SHBG. During the exploration of the interrelations among obesity, sex hormones, and PAEs, models based on Random Forest (RF) and eXtreme Gradient Boosting (XGBoost) algorithms demonstrated the best classification efficacy. In both models, sex hormones exhibited the highest variable importance, and certain phthalate metabolites made significant contributions to the model's performance.

Conclusions

Individuals with obesity exhibit lower levels of TT and SHBG, accompanied by elevated estradiol levels. Exposure to PAEs disrupts sex hormone levels, contributing to an increased risk of obesity in US adults. In the exploration of the interrelationships among these three factors, the RF and XGBoost algorithm models demonstrated superior performance, with sex hormones displaying higher variable importance.

Effects of Pharmaceutical Substances with Obesogenic Activity on Male Reproductive Health

Obesogens have been identified as a significant factor associated with increasing obesity rates, particularly in developed countries. Substances with obesogenic traits are prevalent in consumer products, including certain pharmaceuticals. Specific classes of pharmaceuticals have been recognized for their ability to induce weight gain, often accompanied by hormonal alterations that can adversely impact male fertility. Indeed, research has supplied evidence underscoring the crucial role of obesogens and therapeutic agents in the normal functioning of the male reproductive system. Notably, sperm count and various semen parameters have been closely linked to a range of environmental and nutritional factors, including chemicals and pharmacological agents exhibiting obesogenic properties. This review aimed to explore studies focused on analyzing male fertility parameters, delving into the intricacies of sperm quality, and elucidating the direct and adverse effects that pharmacological agents may have on these aspects.

The adverse role of endocrine disrupting chemicals in the reproductive system

Reproductive system diseases pose prominent threats to human physical and mental well-being. Besides being influenced by genetic material regulation and changes in lifestyle, the occurrence of these diseases is closely connected to exposure to harmful substances in the environment. Endocrine disrupting chemicals (EDCs), characterized by hormone-like effects, have a wide range of influences on the reproductive system. EDCs are ubiquitous in the natural environment and are present in a wide range of industrial and everyday products. Currently, thousands of chemicals have been reported to exhibit endocrine effects, and this number is likely to increase as the testing for potential EDCs has not been consistently required, and obtaining data has been limited, partly due to the long latency of many diseases. The ability to avoid exposure to EDCs, especially those of artificially synthesized origin, is increasingly challenging. While EDCs can be divided into persistent and non-persistent depending on their degree of degradation, due to the recent uptick in research studies in this area, we have chosen to focus on the research pertaining to the detrimental effects on reproductive health of exposure to several EDCs that are widely encountered in daily life over the past six years, specifically bisphenol A (BPA), phthalates (PAEs), polychlorinated biphenyls (PCBs), parabens, pesticides, heavy metals, and so on. By focusing on the impact of EDCs on the hypothalamic-pituitary-gonadal (HPG) axis, which leads to the occurrence and development of reproductive system diseases, this review aims to provide new insights into the molecular mechanisms of EDCs' damage to human health and to encourage further in-depth research to clarify the potentially harmful effects of EDC exposure through various other mechanisms. Ultimately, it offers a scientific basis to enhance EDCs risk management, an endeavor of significant scientific and societal importance for safeguarding reproductive health.