Cryptorchidism and endocrine disrupting chemicals

Early Female Transgender Identity after Prenatal Exposure to Diethylstilbestrol: Report from a French National Diethylstilbestrol (DES) Cohort

Diagnostic of transsexualism and gender incongruence are terms to describe individuals whose self-identity does not match their sex assignment at birth. A transgender woman is an individual assigned male at birth (AMAB) on the basis of the external or internal genitalia who identifies and lives as a woman. In recent decades, a significant increase in the number of transgender people has been reported. Although, its etiology is unknown, biological, anatomical, genetic, environmental and cultural factors have been suggested to contribute to gender variation. In XY animals, it has been shown that environmental endocrine disruptors, through their anti-androgenic activity, induce a female identity. In this work, we described four XY individuals who were exposed in utero to the xenoestrogen diethylstilbesterol (DES) and were part of the French HHORAGES cohort. They all reported a female transgender identity starting from childhood and adolescence. This high prevalence of male to female transgenderism (1.58%) in our cohort of 253 DES sons suggests that exposure to chemicals with xenoestrogen activity during fetal life may affect the male sex identity and behavior.

Techniques of staged laparoscopic orchidopexy for high intra-abdominal testes in children: A systematic review and meta-analysis

Background

Laparoscopic exploration is currently considered the gold standard for managing nonpalpable intraabdominal testes. The problem of short vascular pedicle is addressed in Fowler-Stephen (FS) technique by the division of testicular vessels and in Shehata technique (ST) by traction on testicular vessels. There is a lack of the consensus among pediatric surgeons on the choice of one technique over other. This analysis compares the reported outcomes of staged laparoscopic orchidopexy by ST with the time tested FS technique in managing high intraabdominal undescended testis.

Materials and Methods

The present systematic review and meta-analysis was conducted as per the preferred reporting items for the systematic review and meta-analyses guidelines. Only randomized controlled trials and comparative studies were included. The primary outcomes compared were the incidence of testicular atrophy, testicular retraction/ascent rate, and operative time of Stage I and Stage II orchidopexy.

Results

The present analysis was based on three randomized studies with a total of 119 undescended testes in 117 patients satisfying the inclusion criteria. The operative time was less in Stage I FS technique; however, there was no statistically significant difference in operative time of both procedures during the Stage II laparoscopic orchidopexy. Pooled analysis of postintervention testicular atrophy, testicular retraction rate, and duration of postoperative hospitalization showed no difference between both procedures.

Conclusion

Both FS and STs are comparable in terms of postintervention testicular atrophy, testicular retraction/ascent; however, the mean operative time is significantly less with FS technique in Stage I laparoscopic orchidopexy.

Adverse effects of microplastics and nanoplastics on the reproductive system: A comprehensive review of fertility and potential harmful interactions

In recent years, microplastics (MPs) and nanoplastics (NPs) have caused ubiquitous environmental pollution and raised widespread concern about their potential toxicity to human health, especially in the reproductive system. Moreover, infertility affects >15 % of couples worldwide, and the birth rate is decreasing. Environmental factors are some of the most important causes of infertility. However, little is known about the effects of MPs and NPs on the testes and ovaries. These particles can enter the body primarily via ingestion, inhalation, and skin contact, target the reproductive system in a size-dependent manner and disturb germ cell and other somatic cell development. Our study systematically reviewed the adverse effects of plastic particles on reproductive function and offers valuable insights into the different stages of germ cells and the potential mechanisms. Moreover, the synergistic reproductive toxicity of these particles and carried contaminants was summarized. Given the limited research scale, a shift toward innovative technologies and the adoption of multiple omics are recommended for advancing related studies. Further study is needed to explore the reproductive toxicity of MPs and NPs based on their size, polymer type, shape, and carried toxins, establish effective protective measures, and develop precision medicine for targeted reproductive damage.

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

Endocrine Disrupting Chemicals (EDCs) are harmful compounds that enter the environment naturally or through anthropogenic activities and disrupt normal endocrine functions in humans, adversely affecting reproductive health. Among the most significant sources of EDC contaminants are the pharmaceutical, cosmetic, and packaging industries. EDCs have been identified to have a deteriorating effect on male reproductive system, as evidenced by the increasing number of male infertility cases. A large number of case studies have been published in which men exposed to EDCs experienced testicular cancer, undescended testicles, a decrease in serum testosterone levels, and poor semen quality. Furthermore, epidemiological evidence suggested a link between prenatal EDC exposure and cryptorchidism or undescended testicles, hypospadias, and decreased anogenital distance in infants. The majority of these findings, however, are incongruent due to the lack of long-term follow-up studies that would demonstrate EDCs to be associated with male reproductive disorders. This review aims to provide an overview on recent scientific progress on the association of EDCs to male reproductive health with special emphasis on its toxicity and possible mechanism of EDCs that disrupt male reproductive system.

Aryl hydrocarbon receptor activity in human breast milk and cryptorchidism: A case-control study within the prospective Norwegian HUMIS cohort

BACKGROUND

The etiology of cryptorchidism remains poorly understood. Endocrine disrupting chemicals can impact estrogen signaling by interacting with aryl hydrocarbon receptor (AhR) activity.

OBJECTIVE

To evaluate whether AhR activity in breast milk samples is associated with cryptorchidism.

METHOD

We conducted a case-control study based on 199 mother-child pairs (n = 91 cases/108 controls) selected from the Norwegian Human Milk Study (2002-2009). We defined cases for cryptorchidism based on maternal reports at 1-, 6-, 12-, and 24- months after birth. Chemically- and biologically stable AhR activity (pg 2,3,7,8-TCDD equivalent (TEQ)/g lipid) was determined by DR- CALUX® assay in the mothers' milk collected at a median of 33 (10th-90th percentile: 18-57) days after delivery. We used multivariate logistic regression to compare AhR activity levels between cases and controls, and linear regression separately, to establish the relationship with the presence of 27 potential EDCs measured in breast milk and AhR activity.

RESULTS

The average estimated daily intake (EDI) of dioxin and (dioxin-like (dl)-compounds via breast milk is 33.7 ± 17.9 pg TEQ/kg bodyweight per day among Norwegian children. There were no significant differences in AhR activation in breast milk samples between cases with cryptorchidism and controls. Among the 27 chemicals measured in breast milk, AhR activity was (borderline) significantly associated with all dl-PCBs, three non-dioxin-like (ndl)-PCBs (PCB-74, PCB-180, PCB-194) and two organochlorine pesticides (OCPs; HCB, β-HCH). No associations between AhR activity and brominated flame retardants (PBDEs) or poly- and perfluoroalkyl substances (PFASs).

CONCLUSION

No association between AhR activity and cryptorchidism was found among Norwegian boys. The average EDI of dioxin and dl-compounds in exclusively breastfed Norwegian infants remains above the safety threshold and, therefore requires further reduction measures. Consistent with a possible role in the observed AhR activity, all dl-PCBs were associated with AhR activity whereas the association was null for either PBDEs or PFASs.

In vitro testicular toxicity of environmentally relevant endocrine-disrupting chemicals: 2D vs. 3D models of prepubertal Leydig TM3 cells

The testis is a priority organ for developing alternative models to assess male reproductive health hazards of chemicals. This study characterized a 3D in vitro model of murine prepubertal Leydig TM3 cells with improved expression of steroidogenesis markers suitable for image-based screening of testicular toxicity. This 3D scaffold-free spheroid model was applied to explore the impact of prototypical endocrine-disrupting chemicals (EDCs) and environmental reprotoxicants (benzo[a]pyrene, 2- and 9-methylanthracenes, fluoranthene, triclosan, triclocarban, methoxychlor) on male reproductive health. The results were compared to the male reprotoxicity potential of EDCs assessed in a traditional monolayer (2D) culture. The testicular toxicity was dependent not only on the type of culture (2D vs. 3D models) but also on the duration of exposure. Benzo[a]pyrene and triclocarban were the most active compounds, eliciting cytotoxic effects in prepubertal Leydig cells at low micromolar concentrations, which might be a mechanism contributing to their male reprotoxicity.

Heat stress and hypoxia inhibit the secretion of androgens and induce epithelial-to-mesenchymal transition associated with activated TGF-β/Smad signalling in canine cryptorchidism

Cryptorchidism, as a common congenital disease of canine testes, is mainly caused by factors leading to endocrine abnormalities in testes and infertility in a heat stress and hypoxia microenvironment. Moreover, heat stress and hypoxia, as critical microenvironmental factors, promote epithelial-mesenchymal transition (EMT), which occurs during adult tissue remodelling responses including carcinogenesis and fibrosis and is the main cause of testicular tumours. In this study, we found by haematoxylin-eosin staining that the canine cryptorchid tissue produced a lot of collagen fibres. Also, the quantitative PCR and Western blot results showed that the mRNA and protein levels of the heat stress makers HSP70 and HO-1 and the hypoxia maker HIF-1α are significant higher compared with normal testes. Moreover, we found the expression levels of TGF-βs and its two receptors TGF-βRI and TGF-βRII increased in case of cryptorchidism. From the study in vitro, we found both heat stress and COCl₂ mimic hypoxia inhibited the secretion of testosterone (T) and androstenedione (A4) and promoted the expression of the EMT maker α-SMA and vimentin in Leydig cells, and also that heat stress and COCl₂ stimulated with the TGF-β signalling promoted the expression of TGF-βs and its two type receptors and also the active phosphorylation of Smad2 and Smad3. The use of LY2109761, a receptor inhibitor of TGF-βs/Smad signalling pathway, was associated with heat stress and COCl₂ suppression of androgens' secretion and stimulated EMT in Leydig cells. These findings characterized a novel pathogenesis of cryptorchidism and provided a new idea for therapeutics.

Anti-androgenic compounds in breast milk and cryptorchidism among Norwegian boys in the HUMIS birth cohort

The prevalence of cryptorchidism has increased over the past decades, yet its origins remain poorly understood. Testis descent is dependent on androgens and likely affected by endocrine disrupting compounds (EDCs), targeting the androgen receptor (AR). We investigated the association between anti-androgenic activity, not derived from natural hormones, in maternal breast milk and impaired testis descent among boys. We performed a case-control study based on 199 breast milk samples from 94 mothers of cryptorchid boys and 105 random non-cryptorchid boys participating in the Norwegian HUMIS (Human Milk Study) cohort. For each participant, apolar, and polar fractions were extracted, and combined to reconstitute a mixture. Anti-androgenic activity was measured in all three fractions using the human cell-based in vitro anti-AR CALUX® assay and expressed in μg of flutamide equivalent, a well-known antiandrogen. Results from fraction analyses were compared among boys with cryptorchidism and controls using multiple logistic regression, controlling for appropriate confounders identified using a directed acyclic graph. Children's daily exposure to anti-androgenic EDCs through breastfeeding was estimated to 78 μg flutamide eq./kg of body weigh/day. The activity was higher in the polar fraction (1.48 ± 1.37 μg flutamide eq./g of milk) mainly representing non-persistent chemicals, in contrast to other fractions. However, the activity in the polar extracts was decreased when in mixtures with the apolar fraction, indicating synergistic interactions. No significant difference in the activity was observed according to cryptorchid status for polar, apolar or mixed breast milk fractions. The study showed anti-androgenic activity in nearly all human milk samples, and at levels higher than the advisory threshold. However, no significant association was observed between cryptorchidism and antiandrogenic activity measured in either polar, apolar, or mixture fractions derived from breast milk.

Role of endocrine disruptors in male infertility and impact of COVID-19 on male reproduction

Several epidemiological studies suggest strong association of endocrine disruptors (EDs) with impaired male reproduction. High levels of polychlorinated biphenyls in serum are associated with low sperm count and poor fertility. A high dichloro diphenyl trichloroethane (DDT) concentration results in low serum testosterone (T) and poor semen quality. DDT stimulates estrogen production by acting as estrogen receptor agonist and potent androgen receptor antagonist. Phthalates, another group of EDs, induce seminiferous tubule degeneration with impaired spermatogenesis via disruption of gene expression that regulates cholesterol and lipid homeostasis resulting in low T. Bisphenol A, a strong exogenous estrogen with antiandrogen effect, lowers serum follicle-stimulating hormone, luteinizing hormone, and T, resulting in impaired development of seminiferous tubules and spermatogenesis. Di(2-ethylhexyl) phthalates can exert their antiandrogenic action by directly inhibiting testosterone biosynthesis via cytochrome P-450 dysfunction. Since these EDs are commonly found in plastic bottles, cosmetics, pesticides, some metal food cans, etc., and accumulate in the environment, it is very important to observe caution and avoid their exposure. This updated chapter also reviews the impact of COVID-19-related infection on male reproduction.

A case-cohort study of perinatal exposure to potential endocrine disrupters and the risk of cryptorchidism in the Norwegian HUMIS study

BACKGROUND

Exposure to endocrine-disrupting chemicals (EDCs) during the critical period of testicular descent may increase the risk of cryptorchidism and male fertility.

OBJECTIVE

To investigate 27 potential EDCs measured in breast milk as a proxy for perinatal exposure and the risk of cryptorchidism in a prospective cohort.

METHOD

The Norwegian Human Milk Study (2002-2009) enrolled 2606 mother-infant pairs, of which 1326 were mother-son pairs. In a case-cohort design, we studied 641 male infants who had 27 EDCs already quantified in milk samples: 5 organochlorine pesticides, 14 polychlorinated biphenyls (PCBs), 6 brominated flame retardants, and 2 poly- and perfluoroalkyl substances. We defined cases of congenital, recurrent, persistent and ever-reported cryptorchidism based on questionnaires mothers completed when children were 1, 6, 12 and 24 months old. Variable selection via elastic net logistic regression identified the best cryptorchidism predictors while multivariable logistic regression models determined their effect estimates.

RESULTS

The prevalence of reported congenital cryptorchidism was 6.1%, with half spontaneously descending within six months of birth, after which prevalence stabilized between 2.2 and 2.4%. The ever-reported prevalence of cryptorchidism at 1, 6, 12, or 24 months was 12.2%. Elastic net models identified PCB-74 (OR = 1.31, 95% CI: 1.001-1.703), PCB-114 (OR = 1.36, 95% CI: 1.05-1.77), PCB-194 (OR = 1.28, 95% CI: 1.03-1.53) and β-HCH (OR = 1.26, 95% CI: 1.03-1.53 (per interquartile range increase in concentration of EDCs) as best predictors of congenital cryptorchidism. No EDCs were selected for either recurrent or persistent cryptorchidism, and only PCB-194 was selected by elastic net for ever-reported cryptorchidism (OR = 1.23, 95% CI: 1.01-1.51), in contrast to unpenalized multivariable logistic regression, where most of the individual congeners of PCBs showed significant associations.

CONCLUSION

In the largest multi-pollutant analysis to date considering potential confounding from co-exposure to other chemicals, perinatal exposure to PCB-74, PCB-114, PCB-194 and β-HCH were associated with increased odds of congenital cryptorchidism. Many PCBs may falsely be associated with cryptorchidism when assessed individually, due to confounding by highly correlated chemicals. Experimental studies are warranted to confirm our findings.

Endocrine disruptor chemicals. A review of their effects on male reproduction and antioxidants as a strategy to counter it

Endocrine disruptor chemicals are exogenous molecules that generate adverse effects on human health by destabilizing the homeostasis of endocrine system and affecting directly human reproductive system by inhibiting or activating oestrogenic or androgenic receptors. Endocrine disruptor chemicals generate transgenerational epigenetic problems, besides being associated with male infertility. Epidemiological data indicate that the increase in reproductive problems in males in the last 50 years is correlated with the increase of endocrine disrupting chemicals in the environment, being associated with a decrease in semen quality and direct effects on spermatozoa, such as alterations in motility, viability and acrosomal reaction, due to the generation of oxidative stress, and have also been postulated as a possible cause of testicular dysgenesis syndrome. Diverse antioxidants, such as C and E vitamins, N-acetylcysteine, selenium and natural vegetable extracts, are among the alternatives under study to counter the effects of endocrine disruptor chemicals. In some cases, the usage of them has given positive results and the opposite in others. In this review, we summarize the recent information about the effects of endocrine disruptor chemicals on male reproduction, on sperm cells, and the results of studies that have tested antioxidants as a strategy to diminish their harmful effects.

1,1,1-trichloro-2,2-bis (p-chlorophenyl)-ethane (DDT) and 1,1-Dichloro-2,2-bis (p, p'-chlorophenyl) ethylene (DDE) as endocrine disruptors in human and wildlife: A possible implication of mitochondria

1,1,1-trichloro-2,2-bis (p-chlorophenyl)-ethane (DDT) and its main metabolite 1,1-Dichloro-2,2-bis (p, p'-chlorophenyl) ethylene (DDE) act as endocrine disruptors in humans and wildlife. Immunomodulatory functions have also been attributed to both xenobiotics. DDT was banned in the 1970s due to its toxicity, but it is still produced and used for indoor residual spraying with disease vector control purposes. Due to their persistence and lipophilic properties, DDT and DDE can bioaccumulate through the food chain, being stored in organisms' adipose depots. Their endocrine disruptor function is mediated by agonist or antagonist interaction with nuclear receptors. Present review aimed to provide an overview of how DDT and DDE exposure impacts reproductive and immune systems with estrogen-disrupting action in humans and wildlife. Studies showing DDT and DDE impact on mitochondrial function and apoptosis pathway will also be reviewed, suggesting the hypothesis of direct action on mitochondrial steroid receptors.

Time and spatial trends of operated cryptorchidism in France and environmental hypotheses: a nationwide study from 2002 to 2014

STUDY QUESTION

Is there an evolution in the risk of operated cryptorchidism in France and does local geographical environment appear as an important trigger for this defect?

SUMMARY ANSWER

We observed an increase of the risk of operated cryptorchidism in boys under the age of 7 years during the period 2002-2014 and a strong spatial heterogeneity, with the detection of spatial clusters suggesting environmental factors.

WHAT IS KNOWN ALREADY

Epidemiologic data on cryptorchidism are scarce and its etiology is poorly understood. As part of the testicular dysgenesis syndrome, cryptorchidism is suspected to be a male genital developmental disorder caused by endocrine disruptor chemical (EDC) exposure during the prenatal period.

STUDY DESIGN, SIZE, DURATION

This was a retrospective and descriptive study using data from the French national hospital discharge database, in the 2002-2014 study period. We built an indicator to reflect incident cases of operated cryptorchidism in boys under the age of 7 years in metropolitan France, with an algorithm using specific codes for diseases (ICD-10 codes) and surgical acts (CCAM codes).

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study population was composed of 89 382 new cases of operated cases of cryptorchidism in boys under the age of 7 years. We estimated the temporal evolution of the incidence rate. We fitted a spatial disease-mapping model to describe the risk of cryptorchidism at the postcode scale. We used Kulldorff's spatial scan statistic and Tango's flexibly shaped spatial scan statistic to identify spatial clusters.

MAIN RESULTS AND THE ROLE OF CHANCE

The estimated increase in the incidence of operated cryptorchidism from 2002 to 2014 was equal to 36.4% (30.8%; 42.1%). Cryptorchidism displayed spatial heterogeneity and 24 clusters (P < 0.0001) were detected. The main cluster was localized in a former coal mining and metallurgic area in northern France, currently an industrial area. The cluster analysis suggests the role of shared socio-economic and environmental factors that may be geographically determined and intertwined. The industrial activities identified in the clusters are potentially the source of persistent environmental pollution by metals, dioxins and polychlorinated biphenyls.

LIMITATIONS, REASONS FOR CAUTION

The indicator we used reflects operated cases of cryptorchidism, with an under-evaluation of the health problem. We cannot exclude a possible role of the evolution and local differences in surgical practices in the observed trends. Our inclusion of boys under 7 years of age minimized the biases related to differences in practices according to age. Regarding the environmental hypothesis, this is an exploratory study and should be considered as a hypothesis-generating process for future research studies.

WIDER IMPLICATIONS OF THE FINDINGS

To our knowledge, this is the first descriptive study to address nationwide trends of operated cryptorchidism with detection of spatial clusters, with a very large sample allowing great statistical power. Our results generate plausible environmental hypotheses, which need to be further tested.

STUDY FUNDING/COMPETING INTEREST(S)

This study was entirely funded by Santé publique France, the French National Public Health Agency. All authors declare they have no actual or potential competing financial interest.

TRIAL REGISTRATION NUMBER

N/A.

Effects of PM2.5 exposure on reproductive system and its mechanisms

With the development of human society, haze has become an important form of air pollution. Haze is a mixture of fog and haze, and the main component of haze is fine particulate matter (PM_2.5), which is the most important indicator of composite air pollution. Epidemiological studies proved that PM_2.5 can break through the respiratory mucosal barrier and enter the human body, causing pathological effects on multiple systems of the body. In the past, people put more attention to PM_2.5 in the respiratory system, cardiovascular system, nervous system, etc, and relatively paid less attention to the reproductive system. Recent studies have shown that PM_2.5 will accumulate in the reproductive organs through blood-testis barrier, placental barrier, epithelial barrier and other barriers protecting reproductive tissues. In addition, PM_2.5 can disrupt hormone levels, ultimately affecting fertility. Prior studies have shown that oxidative stress, inflammation, apoptosis, and the breakdown of barrier structures are now considered to contribute to reproductive toxicity and may cause damage at the molecular and genetic levels. However, the exact mechanism remains to be elucidated. Our review aims to provide an understanding of the pathological effects of PM_2.5 on reproductive system and the existing injury mechanism.

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.

Regional difference in semen quality of young men: a review on the implication of environmental and lifestyle factors during fetal life and adulthood

The prevalence of low semen quality and the incidence of testicular cancer have been steadily increasing over the past decades in different parts of the World. Although these conditions may have a genetic or epigenetic origin, there is growing evidence that multiple environmental and lifestyle factors can act alone or in combination to induce adverse effects. Exposure to these factors may occur as early as during fetal life, via the mother, and directly throughout adulthood after full spermatogenic capacity is reached. This review aims at providing an overview of past and current trends in semen quality and its relevance to fertility as well as a barometer of men’s general health. The focus will be on recent epidemiological studies of young men from the general population highlighting geographic variations in Europe. The impact of some lifestyle and environmental factors will be discussed with their role in both fetal life and adulthood. These factors include smoking, alcohol consumption, psychological stress, exposure to electromagnetic radiation, and Endocrine Disrupting Chemicals (EDCs). Finally, the challenges in investigating the influence of environmental factors on semen quality in a fast changing world are presented.

Residential sources of pesticide exposure during pregnancy and the risks of hypospadias and cryptorchidism: the French ELFE birth cohort

OBJECTIVES

Prenatal occupational exposure to pesticides has been associated with male reproductive tract abnormalities. Little is known about the possible impact of non-occupational pesticide exposure on fetal and child development in the general population. Using data from a nationwide birth cohort, we aimed to assess the association between residential sources of prenatal pesticide exposure and the risks of hypospadias and cryptorchidism.

METHODS

Of the 9281 boys in ELFE (French Longitudinal Study of Children), the national French birth cohort, 53 were diagnosed with hypospadias and 137 with cryptorchidism. We assessed residential exposure sources from self-reported domestic use of eight types of pesticide products and French spatial land use data with acreage within a 1000 m radius around each family's home for 21 crop types. We used logistic regression modelling, adjusted for possible confounders that included estimated dietary pesticide intake. Multiple imputations were used to handle missing data.

RESULTS

An increased risk of hypospadias was associated with domestic pesticide use against fleas and ticks (OR=2.28, 95% CI 1.09 to 4.75); no associations were found between cryptorchidism and any domestic pesticide use. Slightly increased risks of cryptorchidism were observed in association with all crop acreages near homes during pregnancy, especially for orchards, and no association was observed for hypospadias.

CONCLUSIONS

Our results suggest a possible increased risk of hypospadias associated with prenatal use of some domestic pesticide products, likely to contain insecticides, and of cryptorchidism with nearby orchard acreage (crops repeatedly sprayed with pesticides). This work is limited by its modest number of cases.

Perturbation of Nuclear Hormone Receptors by Endocrine Disrupting Chemicals: Mechanisms and Pathological Consequences of Exposure

Much of the early work on Nuclear Hormone Receptors (NHRs) focused on their essential roles as mediators of sex steroid hormone signaling in reproductive development and function, and thyroid hormone-dependent formation of the central nervous system. However, as NHRs display tissue-specific distributions and activities, it is not surprising that they are involved and vital in numerous aspects of human development and essential for homeostasis of all organ systems. Much attention has recently been focused on the role of NHRs in energy balance, metabolism, and lipid homeostasis. Dysregulation of NHR function has been implicated in numerous pathologies including cancers, metabolic obesity and syndrome, Type II diabetes mellitus, cardiovascular disease, hyperlipidemia, male and female infertility and other reproductive disorders. This review will discuss the dysregulation of NHR function by environmental endocrine disrupting chemicals (EDCs), and the associated pathological consequences of exposure in numerous tissues and organ systems, as revealed by experimental, clinical, and epidemiological studies.

Transgenerational Inheritance of Environmentally Induced Epigenetic Alterations during Mammalian Development

Genetic studies traditionally focus on DNA as the molecule that passes information on from parents to their offspring. Changes in the DNA code alter heritable information and can more or less severely affect the progeny's phenotype. While the idea that information can be inherited between generations independently of the DNA's nucleotide sequence is not new, the outcome of recent studies provides a mechanistic foundation for the concept. In this review, we attempt to summarize our current knowledge about the transgenerational inheritance of environmentally induced epigenetic changes. We focus primarily on studies using mice but refer to other species to illustrate salient points. Some studies support the notion that there is a somatic component within the phenomenon of epigenetic inheritance. However, here, we will mostly focus on gamete-based processes and the primary molecular mechanisms that are thought to contribute to epigenetic inheritance: DNA methylation, histone modifications, and non-coding RNAs. Most of the rodent studies published in the literature suggest that transgenerational epigenetic inheritance through gametes can be modulated by environmental factors. Modification and redistribution of chromatin proteins in gametes is one of the major routes for transmitting epigenetic information from parents to the offspring. Our recent studies provide additional specific cues for this concept and help better understand environmental exposure influences fitness and fidelity in the germline. In summary, environmental cues can induce parental alterations and affect the phenotypes of offspring through gametic epigenetic inheritance. Consequently, epigenetic factors and their heritability should be considered during disease risk assessment.

Prevalence of Congenital Anomalies in the Japan Environment and Children's Study

BACKGROUND

The aims of the present report were to estimate the prevalence of congenital anomalies (CAs) among infants in Japan using data from the Japan Environment and Children's Study (JECS) and to evaluate the validity of CA classification within JECS.

METHODS

Data on CAs were collected at delivery and at age 1 month from the medical records of 101,825 infants at 15 regional centers. The analyses focused on 61 CAs, selected on the basis of reported associations with environmental exposure. Prevalence per 10,000 pregnancies (including miscarriages, stillbirths, and live births) was stratified according to four reporting patterns (at delivery, at age 1 month, at either, and at both). To evaluate the accuracy of observed CA prevalence, the medical records of 179 cases from a single JECS regional center underwent independent, retrospective re-evaluation.

RESULTS

The prevalence of major CAs in four reporting patterns (at delivery, at age 1 month, at either, and at both) was 2.4, 2.6, 3.5, and 1.4 for myelomeningocele/spina bifida; 4.3, 4.2, 5.3, and 3.2 for cleft palate; 18.1, 17.4, 19.5, and 15.1 for cleft lip with or without cleft palate; 73.4, 100.3, 120.8, and 52.8 for congenital heart disease; and 10.5, 14.1, 15.0, and 9.6 for Down's syndrome, respectively. In the subsample re-evaluation, CA diagnoses were confirmed for 92.7%, 93.3%, 90.5%, and 97.8% of cases in the four reporting patterns (at delivery, at age 1 month, at either, and at both), respectively.

CONCLUSIONS

The present report generated reliable data concerning the prevalence of major CAs in JECS.

Hypogonadism and Cryptorchidism

Congenital cryptorchidism (undescended testis) is one of the most common congenital urogenital malformations in boys. Prevalence of cryptorchidism at birth among boys born with normal birth weight ranges from 1.8 to 8.4%. Cryptorchidism is associated with a risk of low semen quality and an increased risk of testicular germ cell tumors. Testicular hormones, androgens and insulin-like peptide 3 (INSL3), have an essential role in the process of testicular descent from intra-abdominal position into the scrotum in fetal life. This explains the increased prevalence of cryptorchidism among boys with diseases or syndromes associated with congenitally decreased secretion or action of androgens, such as patients with congenital hypogonadism and partial androgen insensitivity syndrome. There is evidence to support that cryptorchidism is associated with decreased testicular hormone production later in life. It has been shown that cryptorchidism impairs long-term Sertoli cell function, but may also affect Leydig cells. Germ cell loss taking place in the cryptorchid testis is proportional to the duration of the condition, and therefore early orchiopexy to bring the testis into the scrotum is the standard treatment. However, the evidence for benefits of early orchiopexy for testicular endocrine function is controversial. The hormonal treatments using human chorionic gonadotropin (hCG) or gonadotropin-releasing hormone (GnRH) to induce testicular descent have low success rates, and therefore they are not recommended by the current guidelines for management of cryptorchidism. However, more research is needed to assess the effects of hormonal treatments during infancy on future male reproductive health.

Endocrine disruptors and testicular function

Despite concerns of the scientific community regarding the adverse effects of human exposure to exogenous man-made chemical substances or mixtures that interfere with normal hormonal balance, the so called "endocrine disruptors (EDs)", their production has been increased during the last few decades. EDs' extensive use has been implicated in the increasing incidence of male reproductive disorders including poor semen quality, testicular malignancies and congenital developmental defects such as hypospadias and cryptorchidism. Several animal studies have demonstrated that exposure to EDs during fetal, neonatal and adult life has deleterious consequences on male reproductive system; however, the evidence on humans remains ambiguous. The complexity of their mode of action, the differential effect according to the developmental stage that exposure occurs, the latency from exposure and the influence of the genetic background in the manifestation of their toxic effects are all responsible factors for the contradictory outcomes. Furthermore, the heterogeneity in the published human studies has hampered agreement in the field. Interventional studies to establish causality would be desirable, but unfortunately the nature of the field excludes this possibility. Therefore, future studies based on standardized guidelines are necessary, in order to estimate human health risks and implement policies to limit public exposure.

High Prenatal Exposure to Bisphenol A Reduces Anogenital Distance in Healthy Male Newborns

OBJECTIVE

To estimate the relationship between cord blood bisphenol A (BPA) levels and anogenital measurements in healthy newborns.

METHODS

Pregnancy and birth history, together with body mass and length data, anogenital measurements, penile measurements and cord blood samples were obtained from healthy newborns. Cord blood concentration of BPA was analyzed by sandwich enzyme-linked immunosorbent assays kit.

RESULTS

Among 130 healthy newborns (72 boys, 58 girls), mean anopenile distance was 45.2±6 mm and anoscrotal distance was 21.9±5.4 mm in boys; mean anoclitoral distance was 33.8±6.6 mm and mean anofourchette distance was 12.2±4.9 mm in girls. Mean cord blood BPA level was 4.75±2.18 ng/mL. 90th percentile value for cord blood BPA was 8.26 ng/mL and the analysis showed a statistically significant correlation between anoscrotal distance and cord blood BPA levels above the 90th percentile (p=0.047) in boys. The changes in anogenital distance in girls were not statistically significant.

CONCLUSION

We showed a significant association between high cord blood BPA levels and shortened anoscrotal distance in male newborns. However, this result should be interpreted with caution since there were no significant external genital abnormalities in our study group.

Cryptorchidism and increased risk of neurodevelopmental disorders

Male congenital malformations as cryptorchidism may contribute to the development of neurodevelopmental disorders directly or via shared familial genetic and/or environmental factors, but the evidence is sparse. Using population-based health registries, we conducted a cohort study of all liveborn singleton boys in Denmark during 1979-2008. Boys with a diagnosis of cryptorchidism were categorized into the exposed cohort and the other boys into the unexposed comparison cohort. The outcomes were diagnoses of any neurodevelopmental disorders and their subtypes. We used Cox proportional hazards regression to compute hazard ratios (HRs), taking into consideration several potential confounders. Among 884,083 male infants, 27,505 received a diagnosis of cryptorchidism during follow-up. Boys with cryptorchidism were more likely to be diagnosed with intellectual disability (HR = 1.77; 95%confidence interval [CI]:1.59,1.97), autism spectrum disorders (ASD) (HR = 1.24; 95% CI:1.13,1.35), attention-deficit hyperactivity disorder (ADHD) (HR = 1.17; 95% CI: 1.08,1.26), anxiety (HR = 1.09; 95% CI: 1.01,1.17), and other behavioral/emotional disorders (HR = 1.16; 95% CI: 1.08,1.26) compared to boys without cryptorchidism. The observed risks of intellectual disability, ASD, and ADHD were increased further in boys with bilateral cryptorchidism. Except for anxiety, cryptorchid boys had higher risks of neurodevelopmental disorders than their non-cryptorchid full brothers. The observed increased risks were similar among boys who underwent orchiopexy, as well as among those with shorter waiting times for this surgery. Cryptorchidism may be associated with increased risks of intellectual disability, ASD, ADHD, and other behavioral/emotional disorders. Cryptorchidism and neurodevelopmental disorders may have shared genetic or in-utero/early postnatal risk factors, which need to be further investigated.

Endocrine Disrupting Chemicals Interfere With Leydig Cell Hormone Pathways During Testicular Descent in Idiopathic Cryptorchidism

Cryptorchidism, a frequent genital malformation in male newborn, remains in most cases idiopathic. On the basis of experimental, epidemiological, and clinical data, it has been included in the testicular dysgenesis syndrome and believed to be influenced, together with genetic and anatomic factors, by maternal exposure to endocrine disrupting chemicals (EDCs). Here, we analyze how EDCs may interfere with the control of testicular descent, which is regulated by two Leydig cell hormones, testosterone, and insulin like peptide 3 (INSL3).

Cryptorchidism and pesticides: Is there a connection?

INTRODUCTION

The aim of our study was to compare the level of the most common organophosphate metabolite, dimethyl phosphate, in urine of women giving birth to both boys with cryptorchidism (study group), and healthy boys (control group), as well as to compare the level of dimethyl phosphate in our population with the results obtained in other populations.

MATERIAL AND METHODS

After the ethical approval we included thirty women in both study and control groups. All newborns were born between 38 and 42weeks' gestation. Urine samples were taken on 3rd postpartal day. Gas chromatography with flame photometric detection was used to analyze dimethyl phosphate in urine following the method of Wu et al. Statistical analysis was done using Mann-Whitney test to compare the results in the two groups.

RESULTS

Geometric mean of dimethyl phosphate in the study group was 7.18±8.26μg/L and the creatinine-corrected level was 5.63±5.95μg/L, and in the control group, the values are 7.98±6.75μg/L and 6.15±7.01μg/L, respectively. There was not a statistically significant difference in levels of dimethyl phosphate between these two groups (p=0.72786). Dimethyl phosphate levels obtained in similar studies are: 14.4μg/L in Israel, 3.7μg/L in Palestine, 10.3μg/L in Jerusalem, 1.60μg/L in Caribbean islands and 2.60μg/L in Canada.

CONCLUSIONS

Pregnant women in our country are exposed to organophosphate pesticides, but a correlation between the exposure to organophosphate pesticides and cryptorchidism was not found.

LEVEL OF EVIDENCE

I.

TYPE OF STUDY

Prognostic study, prospective study.

Sex Hormones, Gonadotropins, and Sex Hormone-binding Globulin in Infants Fed Breast Milk, Cow Milk Formula, or Soy Formula

Measurement of endogenous hormones in early life is important to investigate the effects of hormonally active environmental compounds. To assess the possible hormonal effects of different feeding regimens in different sample matrices of infants, 166 infants were enrolled from two U.S hospitals between 2006 and 2009. The children were classified into exclusive soy formula, cow milk formula or breast milk regimens. Urine, saliva and blood samples were collected over the first 12 months of life. Estradiol, estrone, testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH) and sex hormone-binding globulin (SHBG) levels were measured in the three matrices. Lower estradiol and LH levels were found in urine and saliva samples of soy formula-fed boys compared to cow formula-fed boys. Higher LH level was found in urine samples of soy formula-fed girls compared to cow formula-fed girls. However, we found neither a neonatal testosterone rise in the boys nor a gender-specific difference in testosterone levels, which suggests that urinary testosterone levels may not accurately reflect blood levels during mini-puberty. Nevertheless, our study shows that blood, urine and saliva samples are readily collectible and suitable for multi-hormone analyses in children and allow examination of hypotheses concerning endocrine effects from dietary compounds.

Exomic and Epigenomic Analyses in a Pair of Monozygotic Twins Discordant for Cryptorchidism

Cryptorchidism represents one of the most common human congenital anomalies. In most cases, its etiology remains unclear and seems to be multifactorial. In the present study, a pair of monozygotic twins discordant for cryptorchidism was identified. Twin zygosity was confirmed by microsatellite genotyping. Whole exome sequencing and methylated DNA immunoprecipitation sequencing (MeDIP-Seq) of DNA extract from leucocytes were performed to, respectively, evaluate their exomes and epigenomes. No differences in exome sequencing data were found between the twins after validation. MeDIP-Seq analysis detected 5,410 differentially hypermethylated genes and 2,383 differentially hypomethylated genes. Bioinformatic analysis showed that these genes belonged to several biological processes and signaling pathways, including regulation of actin cytoskeleton, which has been previously implicated in the etiology of cryptorchidism. The findings of the present study suggest that non-genetic factors might contribute to the pathogenesis of cryptorchidism.

A Case-Control Study of Maternal Polybrominated Diphenyl Ether (PBDE) Exposure and Cryptorchidism in Canadian Populations

BACKGROUND

Polybrominated diphenyl ethers (PBDEs) are flame retardants found in North American household products during the past four decades. These chemicals leach out in dust as products age, exposing individuals daily through inhalation and ingestion. Animal studies suggest that PBDEs disrupt sex hormones and adversely affect development of the reproductive system.

OBJECTIVES

In the present study, we examined whether there is a link between maternal hair PBDE concentrations and the risk of cryptorchidism (undescended testes) in male infants; testis descent is known to be dependent on androgens.

METHODS

Full-term male infants were recruited through clinics in Montreal, Toronto, and London, Canada. Boys with cryptorchidism at 3-18 months of age (n=137) were identified by pediatric urologists and surgeons; similar-aged controls (n=158) had no genitourinary abnormalities as assessed by pediatricians. Eight BDE congeners (BDE-28, -47, -99, -100, -153, -154, -183, -209) were measured by GC-MS (gas chromatography-mass spectrometry) in maternal hair samples collected at the time of recruitment.

RESULTS

The ∑PBDE geometric mean for maternal hair was 45.35 pg/mg for controls and 50.27 pg/mg for cases; the concentrations of three BDEs (BDE-99, -100, and -154) were significantly higher in cases than controls in unadjusted models. In adjusted models, every 10-fold increase in the concentration of maternal hair BDE-99 [OR=2.53 (95% CI: 1.29, 4.95) or BDE-100 [OR=2.45 (95% CI: 1.31, 4.56)] was associated with more than a doubling in the risk of cryptorchidism. BDE-154 [OR=1.88 (95% CI: 1.08, 3.28) was also significant.

CONCLUSIONS

Our results suggest that maternal exposure to BDE-99, -100, and -154 may be associated with abnormal migration of testes in the male fetus. This may be due to the anti-androgenic properties of the PBDEs. https://doi.org/10.1289/EHP522.

A comprehensive review of regulatory test methods for endocrine adverse health effects

Development of new endocrine disruption-relevant test methods has been the subject of intensive research efforts for the past several decades, prompted in part by mandates in the 1996 Food Quality Protection Act (FQPA). While scientific understanding and test methods have advanced, questions remain on whether current scientific methods are capable of adequately addressing the complexities of the endocrine system for regulatory health and ecological risk assessments. The specific objective of this article is to perform a comprehensive, detailed evaluation of the adequacy of current test methods to inform regulatory risk assessments of whether a substance has the potential to perturb endocrine-related pathways resulting in human adverse effects. To that end,  approximately 42 existing test guidelines (TGs) were considered in the evaluation of coverage for endocrine-related adverse effects. In addition to evaluations of whether test methods are adequate to capture endocrine-related effects, considerations of further enhancements to current test methods, along with the need to develop novel test methods to address existing test method gaps are described. From this specific evaluation, up to 35 test methods are capable of informing whether a chemical substance perturbs known endocrine related biological pathways. Based on these findings, it can be concluded that current validated test methods are adequate to discern substances that may perturb the endocrine system, resulting in an adverse health effect. Together, these test methods predominantly form the core data requirements of a typical food-use pesticide registration submission. It is recognized, however, that the current state of science is rapidly advancing and there is a need to update current test methods to include added enhancements to ensure continued coverage and public health and environmental protection.

Timing of Maternal Exposure and Foetal Sex Determine the Effects of Low-level Chemical Mixture Exposure on the Foetal Neuroendocrine System in Sheep

We have shown that continuous maternal exposure to the complex mixture of environmental chemicals (ECs) found in human biosolids (sewage sludge), disrupts mRNA expression of genes crucial for development and long-term regulation of hypothalamic-pituitary gonadal (HPG) function in sheep. The present study investigated whether exposure to ECs only during preconceptional period or only during pregnancy perturbed key regulatory genes within the hypothalamus and pituitary gland and whether these effects were different from chronic (life-long) exposure to biosolid ECs. The findings demonstrate that the timing and duration of maternal EC exposure influences the subsequent effects on the foetal neuroendocrine system in a sex-specific manner. Maternal exposure prior to conception, or during pregnancy only, altered the expression of key foetal neuroendocrine regulatory systems such as gonadotrophin-releasing hormone and kisspeptin to a greater extent than when maternal exposure was 'life-long'. Furthermore, hypothalamic gene expression was affected to a greater extent in males than in females and, following EC exposure, male foetuses expressed more 'female-like' mRNA levels for some key neuroendocrine genes. This is the first study to show that 'real-life' maternal exposure to low levels of a complex cocktail of chemicals prior to conception can subsequently affect the developing foetal neuroendocrine system. These findings demonstrate that the developing neuroendocrine system is sensitive to EC mixtures in a sex-dimorphic manner likely to predispose to reproductive dysfunction in later life.

Mitochondrial dysfunction induced by Bisphenol A is a factor of its hepatotoxicity in rats

Bisphenol A (BPA), an estrogenic and endocrine disrupting agent, is widely used in manufacturing of polycarbonate plastics and epoxy resins. BPA and other endocrine disrupting chemicals (EDCs) act via multiple mechanisms including interference with mitochondrial functions. Mitochondria are the hub of cellular energy pool and hence are the target of many EDCs. We studied perturbation of activities of mitochondrial enzymes by BPA and its possible role in hepatotoxicity in Wistar rats. Rats were exposed to BPA (150 mg/kg, 250 mg/kg, 500 mg/kg per os, for 14 days) and activities of enzymes of mitochondrial electron transport chain (ETC) were measured. Besides, other biochemical parameters such as superoxide generation, protein oxidation, and lipid peroxidation (LPO) were also measured. Our results indicated a significant decrease in the activities of enzymes of mitochondrial ETC complexes, i.e., complex I, II, III, IV, and V along with significant increase in LPO and protein oxidation. Additionally, a significant increase in mitochondrial superoxide generation was also observed. All these findings could be attributed to enhanced oxidative stress, decrease in reduced glutathione level, and decrease in the activity of superoxide dismutase in rat liver mitochondria isolated from BPA-treated rats. BPA treatment also caused a significant increase in serum alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and lactate dehydrogenase indicating its potential hepatotoxicity. Furthermore, histopathological findings revealed marked edema formation, hepatocellular degeneration, and necrosis of liver tissue in BPA-exposed rats. In conclusion, this study provides an evidence of impaired mitochondrial bioenergetics and liver toxicity after high-dose BPA exposure in rats. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1922-1934, 2016.

Parental Occupational Exposure to Heavy Metals and Welding Fumes and Risk of Testicular Germ Cell Tumors in Offspring: A Registry-Based Case-Control Study

BACKGROUND

Data are scarce on the association between prenatal/preconception environmental exposure and testicular germ cell tumor (TGCT) in offspring. We examined parental occupational exposures to heavy metals and welding fumes in relation to TGCT in offspring in a registry-based case-control study (NORD-TEST Study).

METHODS

We identified TGCT cases diagnosed at ages 14-49 years in Finland (1988-2012), Norway (1978-2010), and Sweden (1979-2011) through nationwide cancer registries. These cases were individually matched by country and year of birth to controls selected from population registries. Information on parental occupations was retrieved from censuses. From this, we estimated prenatal/preconception exposures of chromium, iron, nickel, lead, and welding fumes (all three countries), and cadmium (Finland only) for each parent using job-exposure matrices specifying prevalence (P) and mean exposure level (L). Exposure indices were calculated as a product of P and L (P × L), and exposure categories were based on P × L or different combinations of P and L.

RESULTS

The study comprised 8,112 cases and 26,264 controls. We observed no statistically significant TGCT risk associated with presence of heavy metals/welding fumes (P × L > 0) and no dose-response relationship (Ptrend ≥ 0.32). A statistically significant elevated TGCT risk was found in paternal exposure category where both P and L of chromium were high (vs. no chromium; OR = 1.37, 95% confidence interval; 1.05-1.79).

CONCLUSIONS

Our study provides little evidence of associations between parental exposures to heavy metals/welding fumes and TGCT in offspring with the potential exception of high paternal chromium exposure.

IMPACT

Further research on paternal chromium exposure is warranted. Cancer Epidemiol Biomarkers Prev; 25(10); 1426-34. ©2016 AACR.

A allele of SNP12 in estrogen receptor 1 was a risk factor for cryptorchidism in Asians: a systematic review with meta-analysis and trial sequential analysis

OBJECTIVE

Some studies have been carried out to evaluate the association between SNP12 in estrogen receptor 1 and cryptorchidism, but the results remain inconsistent. We carried out a meta-analysis to explore the association between this polymorphism and cryptorchidism risk.

METHODS

All eligible studies were searched in PubMed, Web of Science, Embase and Cochrane Library. Pooled odds ratios, with 95 % confidence intervals, were assessed for the association using fixed- and random-effects models.

RESULTS

Overall, four case-control studies (363 cases, 415 controls) were included in the meta-analysis. No significant publication bias (P Begg = 0.308, P Egger = 0.288) was found. A allele of SNP12 in estrogen receptor 1 was protective factor to cryptorchidism in allele model, dominant genetic model and heterozygote comparison in Caucasians, but the result was turned out to be false positive by trial sequential analysis. However, A in allele model was risk factor to cryptorchidism in Asians (odds ratio 2.02, 95 % confidence interval 1.03-3.01, p = 0.946 for heterogeneity) and the result was turned out to be true positive by trial sequential analysis, even though there were merely two original studies.

CONCLUSIONS

The results of this meta-analysis suggest that A allele of SNP12 in estrogen receptor 1 may increase the risk of cryptorchidism in Asians. Meanwhile, further well-designed studies with large sample sizes are required to confirm the present findings, especially in Caucasians.

Endocrine Disruptors in Domestic Animal Reproduction: A Clinical Issue?

Contents The objective of this review was to discuss whether endocrine disruption is a clinical concern in domestic animal reproduction. To that end, we firstly summarize the phenomenon of endocrine disruption, giving examples of the agents of concern and their effects on the mammalian reproductive system. Then there is a brief overview of the literature on endocrine disruptors and domestic animal reproduction. Finally, the clinical implications of endocrine disruptors on the reproductive system of farm animals as well as in dogs and cats are discussed. It is concluded that the evidence for clinical cases of endocrine disruption by chemical pollutants is weak, whereas for phytooestrogens, it is well established. However, there is concern that particular dogs and cats may be exposed to man-made endocrine disruptors.

Undescended testes: an update

PURPOSE OF REVIEW

This article summarizes the latest evidence on the risk factors, management and outcomes of undescended testes (UDTs).

RECENT FINDINGS

UDTs remain common, with increasing evidence that acquired UDT or the ascending testis syndrome should be considered part of the spectrum of this disease. Prompt diagnosis and early referral for surgical evaluation and treatment would seem most likely to result in an optimal functional and cosmetic outcome. Hormonal treatment, rather than orchidopexy, remains popular in some centers, despite a lack of good evidence to support its efficacy, although it may have an important adjunct role in optimizing fertility. Although often performed, ultrasound does not generally assist in the diagnosis and management of UDT, with enhanced education of primary care physicians more likely to facilitate early referral. The testis, rather than quiescent, appears biologically active in the male infant, with increasing evidence of an adverse impact on future spermatogenesis and fertility in men with a UDT.

SUMMARY

Male infants with a UDT should be diagnosed and referred early for surgical evaluation. It seems likely that the optimal timing for surgery should be before the boy's first birthday. There remains a need for high-quality, long-term outcomes data to guide optimal management.

Organic Food Consumption during Pregnancy and Hypospadias and Cryptorchidism at Birth: The Norwegian Mother and Child Cohort Study (MoBa)

BACKGROUND

The etiologies of the male urogenital anomalies hypospadias and cryptorchidism remain unclear. It has been suggested that maternal diet and environmental contaminants may affect the risk of these anomalies via placental or hormonal disturbances.

OBJECTIVES

We examined associations between organic food consumption during pregnancy and prevalence of hypospadias and cryptorchidism at birth.

METHODS

Our study includes 35,107 women participating in the Norwegian Mother and Child Cohort Study (MoBa) who delivered a singleton male infant. Information about use of six groups of organically produced food (vegetables, fruit, bread/cereal, milk/dairy products, eggs, and meat) during pregnancy was collected by a food frequency questionnaire. Women who indicated that they sometimes, often, or mostly consumed organic foods in at least one of the six food groups were classified as organic food consumers in analyses. Hypospadias and cryptorchidism diagnoses were retrieved from the Medical Birth Registry of Norway. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) using multiple logistic regression.

RESULTS

Seventy-four male newborns were diagnosed with hypospadias (0.2%), and 151 with cryptorchidism (0.4%). Women who consumed any organic food during pregnancy were less likely to give birth to a boy with hypospadias (OR = 0.42; 95% CI: 0.25, 0.70, based on 21 exposed cases) than women who reported they never or seldom consumed organic food. Associations with specific organic foods were strongest for vegetable (OR = 0.36; 95% CI: 0.15, 0.85; 10 exposed cases) and milk/dairy (OR = 0.43; 95% CI: 0.17, 1.07; 7 exposed cases) consumption. No substantial association was observed for consumption of organic food and cryptorchidism.

CONCLUSIONS

Consumption of organically produced foods during pregnancy was associated with a lower prevalence of hypospadias in our study population. These findings were based on small numbers of cases and require replication in other study populations.

Environmental Chemical Assessment in Clinical Practice: Unveiling the Elephant in the Room

A growing body of evidence suggests chemicals present in air, water, soil, food, building materials and household products are toxicants that contribute to the many chronic diseases typically seen in routine medical practice. Yet, despite calls from numerous organisations to provide clinicians with more training and awareness in environmental health, there are multiple barriers to the clinical assessment of toxic environmental exposures. Recent developments in the fields of systems biology, innovative breakthroughs in biomedical research encompassing the "-omics" fields, and advances in mobile sensing, peer-to-peer networks and big data, provide tools that future clinicians can use to assess environmental chemical exposures in their patients. There is also a need for concerted action at all levels, including actions by individual patients, clinicians, medical educators, regulators, government and non-government organisations, corporations and the wider civil society, to understand the "exposome" and minimise the extent of toxic exposures on current and future generations. Clinical environmental chemical risk assessment may provide a bridge between multiple disciplines that uses new technologies to herald in a new era in personalised medicine that unites clinicians, patients and civil society in the quest to understand and master the links between the environment and human health.

Polygenic inheritance of cryptorchidism susceptibility in the LE/orl rat

STUDY HYPOTHESIS

Susceptibility to inherited cryptorchidism in the LE/orl rat may be associated with genetic loci that influence developmental patterning of the gubernaculum by the fetal testis.

STUDY FINDING

Cryptorchidism in the LE/orl rat is associated with a unique combination of homozygous minor alleles at multiple loci, and the encoded proteins are co-localized with androgen receptor (AR) and Leydig cells in fetal gubernaculum and testis, respectively.

WHAT IS KNOWN ALREADY

Prior studies have shown aberrant perinatal gubernacular migration, muscle patterning defects and reduced fetal testicular testosterone in the LE/orl strain. In addition, altered expression of androgen-responsive, cytoskeletal and muscle-related transcripts in the LE/orl fetal gubernaculum suggest a role for defective AR signaling in cryptorchidism susceptibility.

STUDY DESIGN, SAMPLES/MATERIALS, METHODS

The long-term LE/orl colony and short-term colonies of outbred Crl:LE and Crl:SD, and inbred WKY/Ncrl rats were maintained for studies. Animals were intercrossed (LE/orl X WKY/Ncrl), and obligate heterozygotes were reciprocally backcrossed to LE/orl rats to generate 54 F2 males used for genotyping and/or linkage analysis. At least five fetuses per gestational time point from two or more litters were used for quantitative real-time RT-PCR (qRT-PCR) and freshly harvested embryonic (E) day 17 gubernaculum was used to generate conditionally immortalized cell lines. We completed genotyping and gene expression analyses using genome-wide microsatellite markers and single nucleotide polymorphism (SNP) arrays, PCR amplification, direct sequencing, restriction enzyme digest with fragment analysis, whole genome sequencing (WGS), and qRT-PCR. Linkage analysis was performed in Haploview with multiple testing correction, and qRT-PCR data were analyzed using ANOVA after log transformation. Imaging was performed using custom and commercial antibodies directed at candidate proteins in gubernaculum and testis tissues, and gubernaculum cell lines.

MAIN RESULTS AND THE ROLE OF CHANCE

LE/orl rats showed reduced fertility and fecundity, and higher risk of perinatal death as compared with Crl:LE rats, but there were no differences in breeding outcomes between normal and unilaterally cryptorchid males. Linkage analysis identified multiple peaks, and with selective breeding of outbred Crl:LE and Crl:SD strains for alleles within two of the most significant (P < 0.003) peaks on chromosomes 6 and 16, we were able to generate a non-LE/orl cryptorchid rat. Associated loci contain potentially functional minor alleles (0.25-0.36 in tested rat strains) including an exonic deletion in Syne2, a large intronic insertion in Ncoa4 (an AR coactivator) and potentially deleterious variants in Solh/Capn15, Ankrd28, and Hsd17b2. Existing WGS data indicate that homozygosity for these combined alleles does not occur in any other sequenced rat strain. We observed a modifying effect of the Syne2(del) allele on expression of other candidate genes, particularly Ncoa4, and for muscle and hormone-responsive transcripts. The selected candidate genes/proteins are highly expressed, androgen-responsive and/or co-localized with developing muscle and AR in fetal gubernaculum, and co-localized with Leydig cells in fetal testis.

LIMITATIONS, REASONS FOR CAUTION

The present study identified multiple cryptorchidism-associated linkage peaks in the LE/orl rat, containing potentially causal alleles. These are strong candidate susceptibility loci, but further studies are needed to demonstrate functional relevance to the phenotype.

WIDER IMPLICATIONS OF THE FINDINGS

Association data from both human and rat models of spontaneous, nonsyndromic cryptorchidism support a polygenic etiology of the disease. Both the present study and a human genome-wide association study suggest that common variants with weak effects contribute to susceptibility, and may exist in genes encoding proteins that participate in AR signaling in the developing gubernaculum. These findings have potential implications for the gene-environment interaction in the etiology of cryptorchidism.

LARGE SCALE DATA

Sequences were deposited in the Rat Genome Database (RGD, http://rgd.mcw.edu/).

STUDY FUNDING AND COMPETING INTERESTS

This work was supported by: R01HD060769 from the Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD), 2P20GM103446 and P20GM103464 from the National Institute of General Medical Sciences (NIGMS), and Nemours Biomedical Research. The authors have no competing interests to declare.

Effects of Low-Dose Diethylstilbestrol Exposure on DNA Methylation in Mouse Spermatocytes

Evidence from previous studies suggests that the male reproductive system can be disrupted by fetal or neonatal exposure to diethylstilbestrol (DES). However, the molecular basis for this effect remains unclear. To evaluate the effects of DES on mouse spermatocytes and to explore its potential mechanism of action, the levels of DNA methyltransferases (DNMTs) and DNA methylation induced by DES were detected. The results showed that low doses of DES inhibited cell proliferation and cell cycle progression and induced apoptosis in GC-2 cells, an immortalized mouse pachytene spermatocyte-derived cell line, which reproduces primary cells responses to E2. Furthermore, global DNA methylation levels were increased and the expression levels of DNMTs were altered in DES-treated GC-2 cells. A total of 141 differentially methylated DNA sites were detected by microarray analysis. Rxra, an important component of the retinoic acid signaling pathway, and mybph, a RhoA pathway-related protein, were found to be hypermethylated, and Prkcd, an apoptosis-related protein, was hypomethylated. These results showed that low-dose DES was toxic to spermatocytes and that DNMT expression and DNA methylation were altered in DES-exposed cells. Taken together, these data demonstrate that DNA methylation likely plays an important role in mediating DES-induced spermatocyte toxicity in vitro.

Pathway analysis supports association of nonsyndromic cryptorchidism with genetic loci linked to cytoskeleton-dependent functions

STUDY QUESTION

What are the genetic loci that increase susceptibility to nonsyndromic cryptorchidism, or undescended testis?

SUMMARY ANSWER

A genome-wide association study (GWAS) suggests that susceptibility to cryptorchidism is heterogeneous, with a subset of suggestive signals linked to cytoskeleton-dependent functions and syndromic forms of the disease.

WHAT IS KNOWN ALREADY

Population studies suggest moderate genetic risk of cryptorchidism and possible maternal and environmental contributions to risk. Previous candidate gene analyses have failed to identify a major associated locus, although variants in insulin-like 3 (INSL3), relaxin/insulin-like family peptide receptor 2 (RXFP2) and other hormonal pathway genes may increase risk in a small percentage of patients.

STUDY DESIGN, SIZE, DURATION

This is a case-control GWAS of 844 boys with nonsyndromic cryptorchidism and 2718 control subjects without syndromes or genital anomalies, all of European ancestry.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All boys with cryptorchidism were diagnosed and treated by a pediatric specialist. In the discovery phase, DNA was extracted from tissue or blood samples and genotyping performed using the Illumina HumanHap550 and Human610-Quad (Group 1) or OmniExpress (Group 2) platform. We imputed genotypes genome-wide, and combined single marker association results in meta-analyses for all cases and for secondary subphenotype analyses based on testis position, laterality and age, and defined genome-wide significance as P = 7 × 10(-9) to correct for multiple testing. Selected markers were genotyped in an independent replication group of European cases (n = 298) and controls (n = 324). We used several bioinformatics tools to analyze top (P < 10(-5)) and suggestive (P < 10(-3)) signals for significant enrichment of signaling pathways, cellular functions and custom gene lists after multiple testing correction.

MAIN RESULTS AND THE ROLE OF CHANCE

In the full analysis, we identified 20 top loci, none reaching genome-wide significance, but one passing this threshold in a subphenotype analysis of proximal testis position (rs55867206, near SH3PXD2B, odds ratio = 2.2 (95% confidence interval 1.7, 2.9), P = 2 × 10(-9)). An additional 127 top loci emerged in at least one secondary analysis, particularly of more severe phenotypes. Cytoskeleton-dependent molecular and cellular functions were prevalent in pathway analysis of suggestive signals, and may implicate loci encoding cytoskeletal proteins that participate in androgen receptor signaling. Genes linked to human syndromic cryptorchidism, including hypogonadotropic hypogonadism, and to hormone-responsive and/or differentially expressed genes in normal and cryptorchid rat gubernaculum, were also significantly overrepresented. No tested marker showed significant replication in an independent population. The results suggest heterogeneous, multilocus and potentially multifactorial susceptibility to nonsyndromic cryptorchidism.

LIMITATIONS, REASONS FOR CAUTION

The present study failed to identify genome-wide significant markers associated with cryptorchidism that could be replicated in an independent population, so further studies are required to define true positive signals among suggestive loci.

WIDER IMPLICATIONS OF THE FINDINGS

As the only GWAS to date of nonsyndromic cryptorchidism, these data will provide a basis for future efforts to understand genetic susceptibility to this common reproductive anomaly and the potential for additive risk from environmental exposures.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by R01HD060769 (the Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD)), P20RR20173 (the National Center for Research Resources (NCRR), currently P20GM103464 from the National Institute of General Medical Sciences (NIGMS)), an Institute Development Fund to the Center for Applied Genomics at The Children's Hospital of Philadelphia, and Nemours Biomedical Research. The authors have no competing interests to declare.

Male reproductive disorders, diseases, and costs of exposure to endocrine-disrupting chemicals in the European Union

INTRODUCTION

Increasing evidence suggests that endocrine-disrupting chemicals (EDCs) contribute to male reproductive diseases and disorders.

PURPOSE

To estimate the incidence/prevalence of selected male reproductive disorders/diseases and associated economic costs that can be reasonably attributed to specific EDC exposures in the European Union (EU).

METHODS

An expert panel evaluated evidence for probability of causation using the Intergovernmental Panel on Climate Change weight-of-evidence characterization. Exposure-response relationships and reference levels were evaluated, and biomarker data were organized from carefully identified studies from the peer-reviewed literature to represent European exposure and approximate burden of disease as it occurred in 2010. The cost-of-illness estimation utilized multiple peer-reviewed sources.

RESULTS

The expert panel identified low epidemiological and strong toxicological evidence for male infertility attributable to phthalate exposure, with a 40-69% probability of causing 618,000 additional assisted reproductive technology procedures, costing €4.71 billion annually. Low epidemiological and strong toxicological evidence was also identified for cryptorchidism due to prenatal polybrominated diphenyl ether exposure, resulting in a 40-69% probability that 4615 cases result, at a cost of €130 million (sensitivity analysis, €117-130 million). A much more modest (0-19%) probability of causation in testicular cancer by polybrominated diphenyl ethers was identified due to very low epidemiological and weak toxicological evidence, with 6830 potential cases annually and costs of €848 million annually (sensitivity analysis, €313-848 million). The panel assigned 40-69% probability of lower T concentrations in 55- to 64-year-old men due to phthalate exposure, with 24 800 associated deaths annually and lost economic productivity of €7.96 billion.

CONCLUSIONS

EDCs may contribute substantially to male reproductive disorders and diseases, with nearly €15 billion annual associated costs in the EU. These estimates represent only a few EDCs for which there were sufficient epidemiological studies and those with the highest probability of causation. These public health costs should be considered as the EU contemplates regulatory action on EDCs.

Cord blood insulin-like peptide 3 (INSL3) but not testosterone is reduced in idiopathic cryptorchidism

BACKGROUND

Cryptorchidism, the most frequent congenital malformation in full-term male newborns, increases the risk of hypofertility and testicular cancer. Most cases remain idiopathic but epidemiological and experimental studies have suggested a role of both genetic and environmental factors. Physiological testicular descent is regulated by two major Leydig hormones: insulin-like peptide 3 (INSL3) and testosterone.

OBJECTIVES

To study the endocrine context at birth as a reflection of late pregnancy in isolated idiopathic cryptorchidism and to analyse the possible disruptions of INSL3 and/or testosterone.

METHODS

From a prospective case-control study at Nice University Hospital, we assessed 180 boys born after 34 weeks gestation: 52 cryptorchid (48 unilateral, 4 bilateral; 26 transient, 26 persistent), and 128 controls matched for term, weight and time of birth. INSL3 and testosterone were measured in cord blood and compared in both groups as were other components of the pituitary-gonadic axis: LH, HCG, FSH, AMH and SHBG.

RESULTS

INSL3 was decreased in cryptorchid boys (P = 0·031), especially transient cryptorchid (P = 0·029), while testosterone was unchanged as were the other hormones measured. INSL3 was significantly decreased (P = 0·018) in the group of 20 with nonpalpable testes compared with the group of 21 with palpable testes (15 suprascrotal, five inguinal, one high scrotal) according to Scorer classification. In the whole population, INSL3 correlated positively with LH and negatively with AMH, but with no other measured hormones.

CONCLUSIONS

INSL3 but not testosterone is decreased at birth in idiopathic cryptorchidism, especially in transient forms. This hormonal decrease may contribute to the impaired testicular descent along with genetic and anatomical factors. Whether foetal environment (nutritional and/or toxicological) interferes with INSL3 secretion in humans remains to be confirmed.

A negative correlation between insulin-like peptide 3 and bisphenol A in human cord blood suggests an effect of endocrine disruptors on testicular descent during fetal development

STUDY QUESTION

Does a relationship exist between insulin-like peptide 3 (INSL3) and selected environmental endocrine disruptors (EEDs) in human cord blood (cb)?

SUMMARY ANSWER

In the whole population (cryptorchid and control boys) cbINSL3 correlated negatively with cb free bisphenol A (BPA) providing indirect evidence for an impact of EEDs on fetal Leydig cell INSL3 production.

WHAT IS KNOWN ALREADY

INSL3 is a major regulator of testicular descent. This hormone has been shown to be decreased in cord blood from boys with idiopathic cryptorchidism, the most frequent male malformation. Fetal exposure to several EEDs has been suspected to be involved in the occurrence of idiopathic cryptorchidism.

STUDY DESIGN, SIZE, DURATION

Correlations between cb INSL3 or testosterone and cb free bioactive BPA and maternal milk polychlorinated biphenyls (PCB153), dichlorodiphenyldichloroethylene (DDE), and monobutyl phthalate (mBP) were assessed in newborn boys in a prospective case-control study. All boys (n = 6246) born after 34 weeks of gestation were systematically screened at birth for cryptorchidism over a 3-year period (2002-2005), and a diagnosis of cryptorchidism confirmed by a senior paediatrician.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We studied 52 cryptorchid (26 transient, 26 persistent) and 128 control boys born at two hospitals in southern France. INSL3 was assayed in CB by a modified validated enzyme-linked immunosorbent assay. Testosterone was measured in CB after diethyl-ether extraction by means of ultra-pressure liquid chromatography-tandem mass spectrometry. Free cbBPA was measured after an extraction step with a radioimmunoassay validated after comparison of values obtained by high-pressure liquid chromatography-mass spectrometry. The xenobiotic analysis in mothers' milk was performed after fat extraction by gas chromatography-mass spectrometry.

MAIN RESULTS AND THE ROLE OF CHANCE

EED concentrations were not increased in the cryptorchid versus control group although a trend for increased mBP (P = 0.09) was observed. In the whole study population, cb levels of BPA correlated negatively with INSL3 (P = 0.01; R² = 0.05) but not with testosterone. No other EED correlated with INSL3 or with testosterone.

LIMITATIONS, REASONS FOR CAUTION

The levels of BPA and INSL3 in cb may not reflect chronic fetal exposure to EEDs. The deleterious impact of EEDs on fetal testicular descent during specific windows of development has yet to be demonstrated.

WIDER IMPLICATIONS OF THE FINDINGS

The negative correlation between cb free BPA and INSL3 provides indirect evidence for an impact of EEDs on human fetal Leydig cell INSL3 production and points to cbINSL3 as a possible target of EED action during fetal testis development.

A new chapter in the bisphenol A story: bisphenol S and bisphenol F are not safe alternatives to this compound

Bisphenol A (BPA) is a widely studied typical endocrine-disrupting chemical, and one of the major new issues is the safe replacement of this commonly used compound. Bisphenol S (BPS) and bisphenol F (BPF) are already or are planned to be used as BPA alternatives. With the use of a culture system that we developed (fetal testis assay [FeTA]), we previously showed that 10 nmol/L BPA reduces basal testosterone secretion of human fetal testis explants and that the susceptibility to BPA is at least 100-fold lower in rat and mouse fetal testes. Here, we show that addition of LH in the FeTA system considerably enhances BPA minimum effective concentration in mouse and human but not in rat fetal testes. Then, using the FeTA system without LH (the experimental conditions in which mouse and human fetal testes are most sensitive to BPA), we found that, as for BPA, 10 nmol/L BPS or BPF is sufficient to decrease basal testosterone secretion by human fetal testes with often nonmonotonic dose-response curves. In fetal mouse testes, the dose-response curves were mostly monotonic and the minimum effective concentrations were 1,000 nmol/L for BPA and BPF and 100 nmol/L for BPS. Finally, 10,000 nmol/L BPA, BPS, or BPF reduced Insl3 expression in cultured mouse fetal testes. This is the first report describing BPS and BPF adverse effects on a physiologic function in humans and rodents.