From the Cover: Metabolomics Reveals a Role of Betaine in Prenatal DBP Exposure-Induced Epigenetic Transgenerational Failure of Spermatogenesis in Rats

Phthalates and uterine disorders

Humans are ubiquitously exposed to environmental endocrine disrupting chemicals such as phthalates. Phthalates can migrate out of products and enter the human body through ingestion, inhalation, or dermal application, can have potential estrogenic/antiestrogenic and/or androgenic/antiandrogenic activity, and are involved in many diseases. As a female reproductive organ that is regulated by hormones such as estrogen, progesterone and androgen, the uterus can develop several disorders such as leiomyoma, endometriosis and abnormal bleeding. In this review, we summarize the hormone-like activities of phthalates, in vitro studies of endometrial cells exposed to phthalates, epigenetic modifications in the uterus induced by phthalate exposure, and associations between phthalate exposure and uterine disorders such as leiomyoma and endometriosis. Moreover, we also discuss the current research gaps in understanding the relationship between phthalate exposure and uterine disorders.

Bugs on Drugs: Paracetamol Exposure Reveals Genotype-Specific Generational Effects on Life History Traits in Drosophila melanogaster

Few investigations have been made to determine whether pharmaceutical drugs cause any generational effects. These effects can be divided into intergenerational and transgenerational effects. In insects, the F1 offspring of exposed individuals are considered to show intergenerational effects (as they have been exposed as germ cells or early embryos), while the F2 generation is fully non-exposed and considered to show transgenerational effects. Here, the common over-the-counter (OTC) drug, paracetamol, is investigated for genotype-specific responses and effects across generations on three life-history traits: fecundity, longevity, and spontaneous locomotor activity levels in the model species Drosophila melanogaster. Seven isofemale D. melanogaster lines were exposed to a high and intermediate dose of paracetamol determined by a dose-response curve. NMR investigations verified the long-term presence of paracetamol in the food substrate. Phenotypic effects of paracetamol ingestion were investigated on flies exposed to the drug and in their offspring and grand-offspring. The dose-response curve indicated genotype-specific responses to paracetamol. In the following experiment, all traits investigated displayed significant effects of paracetamol ingestion for at least one of the seven isofemale lines, and we detected strong genotype-specific responses to paracetamol. Fecundity tended to increase in individuals directly exposed to the drug whereas fecundity in the F2 generation was reduced (transgenerational). Longevity generally decreased in directly exposed individuals but tended to increase in F1 offspring (intergenerational). Paracetamol effects on spontaneous locomotor activity were primarily detected as transgenerational effects and were rarely seen in directly exposed individuals. However, across lines, no clear overall trend could be determined for any trait. The generational effects and marked genotype-specific response to paracetamol warrants further investigation of both genotype-specific responses and generational effects in general.

Differential protein repertoires related to sperm function identified in extracellular vesicles (EVs) in seminal plasma of distinct fertility buffalo (Bubalus bubalis) bulls

Buffalo bulls are backbone of Indian dairy industry, and the quality of semen donating bulls determine the overall production efficiency of dairy farms. Seminal plasma harbor millions of lipid bilayer nanovesicles known as extracellular vesicles (EVs). These EVs carry a heterogenous cargo of essential biomolecules including fertility-associated proteins which contribute to fertilizing potential of spermatozoa. In this study, we explored size, concentration, and complete proteome profiles of SP EVs from two distinct fertility groups to uncover proteins influencing bull fertility. Through Dynamic Light Scattering (DLS) it was found that purified EVs were present in 7-14 size exclusion chromatographic (SEC) fractions with sizes ranging from 146.5 to 258.7 nm in high fertile (HF) and low fertile (LF) bulls. Nanoparticle Tracking Analysis (NTA) confirmed the size of seminal EVs up to 200 nm, and concentrations varying from 2.84 to 6.82 × 1011 and 3.57 to 7.74 × 1011 particles per ml in HF and LF bulls, respectively. No significant difference was observed in size and concentration of seminal EVs between two groups. We identified a total of 1,862 and 1,807 proteins in seminal EVs of HF and LF bulls, respectively using high throughput LC-MS/MS approach. Out of these total proteins, 1,754 proteins were common in both groups and about 87 proteins were highly abundant in HF group while 1,292 were less abundant as compared to LF bulls. Gene ontology (GO) analysis, revealed that highly abundant proteins in HF group were mainly part of the nucleus and involved in nucleosome assembly along with DNA binding. Additionally, highly abundant proteins in EVs of HF group were found to be involved in spermatogenesis, motility, acrosome reaction, capacitation, gamete fusion, and cryotolerance. Two highly abundant proteins, protein disulfide-isomerase A4 and gelsolin, are associated with sperm-oocyte fusion and acrosome reaction, respectively, and their immunolocalization on spermatozoa may indicate that these proteins are transferred through EVs. Our evidences support that proteins in EVs and subsequently their presence on sperm, are strongly associated with sperm functions. Altogether, our investigation indicates that SPEVs possess crucial protein repertoires that are essential for enhancing sperm fertilizing capacity.

Prenatal dexamethasone exposure impairs rat blood-testis barrier function and sperm quality in adult offspring via GR/KDM1B/FSTL3/TGFβ signaling

Both epidemiological and animal studies suggest that adverse environment during pregnancy can change the offspring development programming, but it is difficult to achieve prenatal early warning. In this study we investigated the impact of prenatal dexamethasone exposure (PDE) on sperm quality and function of blood-testis barrier (BTB) in adult offspring and the underlying mechanisms. Pregnant rats were injected with dexamethasone (0.1, 0.2 and 0.4 mg·kg-1·d-1, s.c.) from GD9 to GD20. After weaning (PW4), the pups were fed with lab chow. At PW12 and PW28, the male offspring were euthanized to collect blood and testes samples. We showed that PDE significantly decreased sperm quality (including quantity and motility) in male offspring, which was associated with impaired BTB and decreased CX43/E-cadherin expression in the testis. We demonstrated that PDE induced morphological abnormalities of fetal testicle and Sertoli cell development originated from intrauterine. By tracing to fetal testicular Sertoli cells, we found that PDE dose-dependently increased expression of histone lysine demethylases (KDM1B), decreasing histone 3 lysine 9 dimethylation (H3K9me2) levels of follistatin-like-3 (FSTL3) promoter region and increased FSTL3 expression, and inhibited TGFβ signaling and CX43/E-cadherin expression in offspring before and after birth. These results were validated in TM4 Sertoli cells following dexamethasone treatment. Meanwhile, the H3K9me2 levels of FSTL3 promoter in maternal peripheral blood mononuclear cell (PBMC) and placenta were decreased and its expression increased, which was positively correlated with the changes in offspring testis. Based on analysis of human samples, we found that the H3K9me2 levels of FSTL3 promoter in maternal blood PBMC and placenta were positively correlated with fetal blood testosterone levels after prenatal dexamethasone exposure. We conclude that PDE can reduce sperm quality in adult offspring rats, which is related to the damage of testis BTB via epigenetic modification and change of FSTL3 expression in Sertoli cells. The H3K9me2 levels of the FSTL3 promoter and its expression in the maternal blood PBMC can be used as a prenatal warning marker for fetal testicular dysplasia.

Inter- and trans-generational impacts of real-world PM2.5 exposure on male-specific primary hypogonadism

Exposure to PM2.5, a harmful type of air pollution, has been associated with compromised male reproductive health; however, it remains unclear whether such exposure can elicit transgenerational effects on male fertility. Here, we aim to examine the effect of paternal exposure to real-world PM2.5 on the reproductive health of male offspring. We have observed that paternal exposure to real-world PM2.5 can lead to transgenerational primary hypogonadism in a sex-selective manner, and we have also confirmed this phenotype by using an external model. Mechanically, we have identified small RNAs (sRNAs) that play a critical role in mediating these transgenerational effects. Specifically, miR6240 and piR016061, which are present in F0 PM sperm, regulate intergenerational transmission by targeting Lhcgr and Nsd1, respectively. We have also uncovered that piR033435 and piR006695 indirectly regulate F1 PM sperm methylation by binding to the 3'-untranslated region of Tet1 mRNA. The reduced expression of Tet1 resulted in hypermethylation of several testosterone synthesis genes, including Lhcgr and Gnas, impaired Leydig cell function and ultimately led to transgenerational primary hypogonadism. Our findings provide insights into the mechanisms underlying the transgenerational effects of paternal PM2.5 exposure on reproductive health, highlighting the crucial role played by sRNAs in mediating these effects. The findings underscore the significance of paternal pre-conception interventions in alleviating the adverse effects of environmental pollutants on reproductive health.

Redox mechanisms of environmental toxicants on male reproductive function

Humans and wildlife, including domesticated animals, are exposed to a myriad of environmental contaminants that are derived from various human activities, including agricultural, household, cosmetic, pharmaceutical, and industrial products. Excessive exposure to pesticides, heavy metals, and phthalates consequently causes the overproduction of reactive oxygen species. The equilibrium between reactive oxygen species and the antioxidant system is preserved to maintain cellular redox homeostasis. Mitochondria play a key role in cellular function and cell survival. Mitochondria are vulnerable to damage that can be provoked by environmental exposures. Once the mitochondrial metabolism is damaged, it interferes with energy metabolism and eventually causes the overproduction of free radicals. Furthermore, it also perceives inflammation signals to generate an inflammatory response, which is involved in pathophysiological mechanisms. A depleted antioxidant system provokes oxidative stress that triggers inflammation and regulates epigenetic function and apoptotic events. Apart from that, these chemicals influence steroidogenesis, deteriorate sperm quality, and damage male reproductive organs. It is strongly believed that redox signaling molecules are the key regulators that mediate reproductive toxicity. This review article aims to spotlight the redox toxicology of environmental chemicals on male reproduction function and its fertility prognosis. Furthermore, we shed light on the influence of redox signaling and metabolism in modulating the response of environmental toxins to reproductive function. Additionally, we emphasize the supporting evidence from diverse cellular and animal studies.

The Role of Endocrine Disrupting Chemicals in Gestation and Pregnancy Outcomes

Endocrine disrupting chemicals (EDCs) are exogenous substances widely disseminated both in the environment and in daily-life products which can interfere with the regulation and function of the endocrine system. These substances have gradually entered the food chain, being frequently found in human blood and urine samples. This becomes a particularly serious issue when they reach vulnerable populations such as pregnant women, whose hormones are more unstable and vulnerable to EDCs. The proper formation and activity of the placenta, and therefore embryonic development, may get seriously affected by the presence of these chemicals, augmenting the risk of several pregnancy complications, including intrauterine growth restriction, preterm birth, preeclampsia, and gestational diabetes mellitus, among others. Additionally, some of them also exert a detrimental impact on fertility, thus hindering the reproductive process from the beginning. In several cases, EDCs even induce cross-generational effects, inherited by future generations through epigenetic mechanisms. These are the reasons why a proper understanding of the reproductive and gestational alterations derived from these substances is needed, along with efforts to establish regulations and preventive measures in order to avoid exposition (especially during this particular stage of life).

Multi-Omics Analyses Reveal the Mechanisms of Early Stage Kidney Toxicity by Diquat

Diquat (DQ), a widely used bipyridyl herbicide, is associated with significantly higher rates of kidney injuries compared to other pesticides. However, the underlying molecular mechanisms are largely unknown. In this study, we identified the molecular changes in the early stage of DQ-induced kidney damage in a mouse model through transcriptomic, proteomic and metabolomic analyses. We identified 869 genes, 351 proteins and 96 metabolites that were differentially expressed in the DQ-treated mice relative to the control mice (p < 0.05), and showed significant enrichment in the PPAR signaling pathway and fatty acid metabolism. Hmgcs2, Cyp4a10, Cyp4a14 and Lpl were identified as the major proteins/genes associated with DQ-induced kidney damage. In addition, eicosapentaenoic acid, linoleic acid, palmitic acid and (R)-3-hydroxybutyric acid were the major metabolites related to DQ-induced kidney injury. Overall, the multi-omics analysis showed that DQ-induced kidney damage is associated with dysregulation of the PPAR signaling pathway, and an aberrant increase in Hmgcs2 expression and 3-hydroxybutyric acid levels. Our findings provide new insights into the molecular basis of DQ-induced early kidney damage.

Physiological, biochemical, and hormonal changes in rats exposed to bottled water left in a hot car and the freezer

The aim of this study was to investigate the effects of bottled water left in the car and those left in the refrigerator on the physiological and biochemical parameters of male rats. Eighteen male albino rats were randomly divided into control, warmed bottled water (WBW), and cooled bottled water (CBW) groups. The concentrations of bisphenol A (BPA) and antimony (Sb) in the water samples were measured. Results showed that the levels of BPA and Sb were higher in bottled water left in the car and those kept at room temperature (control), relative to the bottled water samples kept in the fridge. Bodyweight, some metabolic indicators, cTnT and CRP levels, hematological parameters, testosterone level, and sperm quality were significantly affected by storage conditions. These results indicate that storage conditions can potentially affect the quality of bottled water, which in turn can affect the biological parameters of living organisms. Moreover, since the concentrations of BPA and Sb were least in bottled water kept in the refrigerator, we recommend that manufacturers and households should endeavor to keep bottled water under cold storage.

Repair mechanism of Wuwei Fuzheng Yijing formula in di-2-ethylhexyl phthalate-induced sperm DNA fragmentation in mice

CONTEXT

Di-2-ethylhexyl phthalate (DEHP), a known persistent organic pollutant, can increase the sperm DNA fragmentation index (DFI).

OBJECTIVE

To investigate the mechanism underlying the repair of DEHP-induced sperm DNA damage in mice by Wuwei Fuzheng Yijing (WFY) formula.

MATERIALS AND METHODS

The potential targets of WFY and sperm DNA fragment (SDF) were obtained from the TCMSP, BATMAN-TCM, OMIM and GeneCards. The protein-protein interaction (PPI) network, GO and KEGG pathway analyses of WFY-SDF were constructed. An animal model of DEHP-induced sperm DNA damage was replicated by gavage of SPF ICR (CD1) mice DEHP at 1 g/kg/d and treated with WFY at 8.92, 17.84 and 35.67 g/kg, respectively, for 60 d. Sperm DFI of each group was detected and compared. The target genes of WFY identified by transcriptomic and proteomic analyses were validated by qRT-PCR and Western blotting.

RESULTS

Network pharmacology pathway analysis indicated that PI3K/Akt was the potential target of WFY on SDF. The DFI of the DEHP group (25.48%) was significantly higher than that of the control group (4.02%). The high-dose WFY group (19.05%) exhibited the most significant repairing effect. The related pathways were PI3K/Akt and metabolic. Aass, Aldh1a7, GSTA3, betaine homocysteine S-methyltransferase (Bhmt), Mug2 and Svs1 were screened and Bhmt was validated.

DISCUSSION AND CONCLUSIONS

WFY can repair sperm DNA damage caused by DEHP, and the mechanism may be related to PI3K/Akt and metabolic pathways, and Bhmt. This provides a new direction for using traditional Chinese medicine to prevent and repair reproductive system injury caused by pollutants.

Multi- and Transgenerational Effects of Environmental Toxicants on Mammalian Reproduction

Environmental toxicants (ETs) are an exogenous chemical group diffused in the environment that contaminate food, water, air and soil, and through the food chain, they bioaccumulate into the organisms. In mammals, the exposure to ETs can affect both male and female fertility and their reproductive health through complex alterations that impact both gametogeneses, among other processes. In humans, direct exposure to ETs concurs to the declining of fertility, and its transmission across generations has been recently proposed. However, multi- and transgenerational inheritances of ET reprotoxicity have only been demonstrated in animals. Here, we review recent studies performed on laboratory model animals investigating the effects of ETs, such as BPA, phthalates, pesticides and persistent contaminants, on the reproductive system transmitted through generations. This includes multigenerational effects, where exposure to the compounds cannot be excluded, and transgenerational effects in unexposed animals. Additionally, we report on epigenetic mechanisms, such as DNA methylation, histone tails and noncoding RNAs, which may play a mechanistic role in a nongenetic transmission of environmental information exposure through the germline across generations.

The selected epigenetic effects of phthalates: DBP, BBP and their metabolites: MBP, MBzP on human peripheral blood mononuclear cells (In Vitro)

Phthalates are classified as non-genotoxic carcinogens. These compounds do not cause direct DNA damage but may induce indirect DNA lesions leading to cancer development. In the presented paper we have studied the effect of di-n-butyl phthalate (DBP), butylbenzyl phthalate (BBP), and their metabolites, such as mono-n-butyl phthalate (MBP) and monobenzyl phthalate (MBzP) on selected epigenetic parameters in human peripheral blood mononuclear cells (PBMCs). The cells were incubated with tested phthalates at 0.001, 0.01 and 0.1 μg/mL for 24 h. Next, global DNA methylation, methylation in the promoter regions of tumor suppressor genes (P16, TP53) and proto-oncogenes (BCL2, CCND1) were assessed as well as the expression profile of the indicated genes was analysed. The obtained results have revealed significant reduction of global DNA methylation level in PBMCs exposed to BBP, MBP and MBzP. Phthalates changed methylation pattern of the tested genes, decreased expression of P16 and TP53 genes and increased the expression of BCL2 and CCND1. In conclusion, our results have shown that the examined phthalates disturbed the processes of methylation and expression of tumor suppressor genes (P16, TP53) and protooncogenes (BCL2, CCND1) in human PBMCs.

A cross-species comparative approach to assessing multi- and transgenerational effects of endocrine disrupting chemicals

A wide range of chemicals have been identified as endocrine disrupting chemicals (EDCs) in vertebrate species. Most studies of EDCs have focused on exposure of both male and female adults to these chemicals; however, there is clear evidence that EDCs have dramatic effects when mature or developing gametes are exposed, and consequently are associated with in multigenerational and transgenerational effects. Several publications have reviewed such actions of EDCs in subgroups of species, e.g., fish or rodents. In this review, we take a holistic approach synthesizing knowledge of the effects of EDCs across vertebrate species, including fish, anurans, birds, and mammals, and discuss the potential mechanism(s) mediating such multi- and transgenerational effects. We also propose a series of recommendations aimed at moving the field forward in a structured and coherent manner.

Gut microbiota may contribute to the postnatal male reproductive abnormalities induced by prenatal dibutyl phthalate exposure

Phthalate is an environmental endocrine disruptor that causes direct and intergenerational male reproductive damage. However, its mechanisms require further investigation. The role of gut microbiota in male reproductive function has been gradually revealed in the past. To explore the intergenerational testicular injury and the influence on offspring gut microbiota of the widely used phthalate dibutyl phthalate (DBP), we conducted a prenatal DBP exposure experiment with microbiota sequencing. We finally explained the gestational DBP exposure-induced gut dysbacteriosis, which is one of the mechanisms of testicular injury in the offspring. The occurrence of seminiferous atrophy and spermatogenic cells apoptosis showed a slight increase. Our study partially supported the results of previous research works on the characteristics of gut dysbacteriosis, which featured the increased relative abundance of Bacteroidetes, Prevotella and P. copri. Focusing on the role of gut microbiota in reproductive function is important. Future studies need to investigate the relationship between environmental pollution and human health.

Developmental toxicant exposures and sex-specific effects on epigenetic programming and cardiovascular health across generations

Despite substantial strides in diagnosis and treatment, cardiovascular diseases (CVDs) continue to represent the leading cause of death in the USA and around the world, resulting in significant morbidity and loss of productive years of life. It is increasingly evident that environmental exposures during early development can influence CVD risk across the life course. CVDs exhibit marked sexual dimorphism, but how sex interacts with environmental exposures to affect cardiovascular health is a critical and understudied area of environmental health. Emerging evidence suggests that developmental exposures may have multi- and transgenerational effects on cardiovascular health, with potential sex differences; however, further research in this important area is urgently needed. Lead (Pb), phthalate plasticizers, and perfluoroalkyl substances (PFAS) are ubiquitous environmental contaminants with numerous adverse human health effects. Notably, recent evidence suggests that developmental exposure to each of these toxicants has sex-specific effects on cardiovascular outcomes, but the underlying mechanisms, and their effects on future generations, require further investigation. This review article will highlight the role for the developmental environment in influencing cardiovascular health across generations, with a particular emphasis on sex differences and epigenetic mechanisms. In particular, we will focus on the current evidence for adverse multi and transgenerational effects of developmental exposures to Pb, phthalates, and PFAS and highlight areas where further research is needed.

Legislation to limit the environmental plastic and microplastic pollution and their influence on human exposure

Plastic pollution is an emerging problem and is a consequence of the post-consumer plastic waste accumulation in the environment coupled to mismanaged waste programmes. Countries are counteracting the continuous growth of plastic litter with different strategies: introducing bans and limits on both plastic items and materials, promoting plastic recycling and recovery strategies and encouraging voluntary clean up actions, as well as raising public awareness. However, the toxicity of plastics to the environment and organisms is not only related to their polymer chains, but also to the fact that plastic materials contain hazardous additives and can adsorb environmental pollutants (i.e. heavy metals and persistent organic contaminants, respectively). The plastic/additives/pollutants combination may be ingested by marine organisms and then enter in the food chain. Therefore, legislation for additives and contaminants is crucial both to reduce environmental pollution and their toxic effects on organisms, which of course includes humans. In this review, the current policies on plastics and related contaminants are described focusing on current laws. Moreover, recommendations for seafood consumption are suggested, since each fish or mollusc eaten may potentially result in plastic particles, additives or contaminants ingestion.

Inheritable testicular metabolic memory of high-fat diet causes transgenerational sperm defects in mice

The consumption of energy-dense diets has contributed to an increase in the prevalence of obesity and its comorbidities worldwide. The adoption of unhealthy feeding habits often occurs at early age, prompting the early onset of metabolic disease with unknown consequences for reproductive function later in life. Recently, evidence has emerged regarding the intergenerational and transgenerational effects of high-fat diets (HFD) on sperm parameters and testicular metabolism. Hereby, we study the impact of high-fat feeding male mice (F₀) on the testicular metabolome and function of their sons (F₁) and grandsons (F₂). Testicular content of metabolites related to insulin resistance, cell membrane remodeling, nutritional support and antioxidative stress (leucine, acetate, glycine, glutamine, inosine) were altered in sons and grandsons of mice fed with HFD, comparing to descendants of chow-fed mice. Sperm counts were lower in the grandsons of mice fed with HFD, even if transient. Sperm quality was correlated to testicular metabolite content in all generations. Principal Component Analysis of sperm parameters and testicular metabolites revealed an HFD-related phenotype, especially in the diet-challenged generation and their grandsons. Ancestral HFD, even if transient, causes transgenerational "inherited metabolic memory" in the testicular tissue, characterized by changes in testicular metabolome and function.

Transgenerational Effects of Di(2-Ethylhexyl) Phthalate on Anogenital Distance, Sperm Functions and DNA Methylation in Rat Offspring

Di(2-ethylhexyl) phthalate (DEHP) is widely used as a plasticizer in the manufacture of polyvinylchloride plastics and has been associated with concerns regarding male reproductive toxicity. In this study, we hypothesized that maternal exposure to DEHP induces transgenerational inheritance of adult-onset adverse reproductive outcomes through the male germline in the F1, F2, and F3 generations of male offspring. Pregnant rats were treated with 5 or 500 mg of DEHP/kg/day through gavage from gestation day 0 to birth. The offspring body weight, anogenital distance (AGD), anogenital index (AGI), sperm count, motility, and DNA fragmentation index (DFI) were measured for all generations. Methyl-CpG binding domain sequencing was performed to analyze sperm DNA methylation status in the F3. DEHP exposure at 500 mg/kg affected AGD, AGI, sperm count, mean DFI, and %DFI in the F1; AGD, sperm count, and mean DFI in the F2; and AGD, AGI, mean DFI, and %DFI in the F3. DEHP exposure at 5 mg/kg affected AGD, AGI, sperm count, and %DFI in the F1; sperm count in the F2; and AGD and AGI in F3. Compared with the control group, 15 and 45 differentially hypermethylated genes were identified in the groups administered 5 mg/kg and 500 mg/kg DEHP, respectively. Moreover, 130 and 6 differentially hypomethylated genes were observed in the groups administered 5 mg/kg and 500 mg/kg DEHP. Overall, these results demonstrated that prenatal exposure to DEHP caused transgenerational epigenetic effects, which may explain the observed phenotypic changes in the male reproductive system.

Exposure to phthalates: germline dysfunction and aneuploidy

Epidemiological studies continue to reveal the enduring impact of exposures to environmental chemicals on human physiology, including our reproductive health. Phthalates, a well characterized class of endocrine disrupting chemicals and commonly utilized plasticizers, are among one of the many toxicants ubiquitously present in our environment. Phthalate exposure has been linked to increases in the rate of human aneuploidy, a phenomenon that is detected in 0.3% of livebirths resulting in genetic disorders including trisomy 21, approximately 4% of stillbirths, and over 35% of miscarriages. Here we review recent epidemiological and experimental studies that have examined the role that phthalates play in germline dysfunction, including increases in apoptosis, oxidative stress, DNA damage, and impaired genomic integrity, resulting in aneuploidy. We will further discuss subject variability, as it relates to diet and polymorphisms, and the sexual dimorphic effects of phthalate exposure, as it relates to sex-specific targets. Lastly, we discuss some of the conserved effects of phthalate exposure across humans, mammalian models and nonmammalian model organisms, highlighting the importance of using model organisms to our advantage for chemical risk assessment and unveiling potential mechanisms that underlie phthalate-induced reproductive health issues across species.

Ecological and toxicological assessments of anthropogenic contaminants based on environmental metabolomics

There has long been a great concern with growing anthropogenic contaminants and their ecological and toxicological effects on living organisms and the surrounding environment for decades. Metabolomics, a functional readout of cellular activity, can capture organismal responses to various contaminant-related stressors, acquiring direct signatures to illustrate the environmental behaviours of anthropogenic contaminants better. This review entails the application of metabolomics to profile metabolic responses of environmental organisms, e.g. animals (rodents, fish, crustacean and earthworms) and microorganisms (bacteria, yeast and microalgae) to different anthropogenic contaminants, including heavy metals, nanomaterials, pesticides, pharmaceutical and personal products, persistent organic pollutants, and assesses their ecotoxicological impacts with regard to literature published in the recent five years. Contaminant-induced metabolism alteration and up/down-regulation of metabolic pathways are revealed in typical organisms. The obtained insights of variations in global metabolism provide a distinct understanding of how anthropogenic contaminants exert influences on specific metabolic pathways on living organisms. Thus with a novel ecotechnique of environmental metabolomics, risk assessments of anthropogenic contaminants are profoundly demonstrated.

Different exposure windows to low doses of genistein and/or vinclozolin result in contrasted disorders of testis function and gene expression of exposed rats and their unexposed progeny

Living species including humans are continuously exposed to low levels of a myriad of endocrine active compounds that may affect their reproductive function. In contrast, experimental designs scrutinizing this question mostly consider the gestational/lactational period, select high unrealistic doses and, have rarely investigated the possible reproductive consequences in the progeny. The present study aimed at assessing comparatively a set of male reproductive endpoints according to exposure windows, gestational/lactational versus pre-pubertal to adulthood, using low doses of endocrine active substances in male rats as well as their unexposed male progeny. Animals were orally exposed to 1 mg/kg bw/d of genistein and/or vinclozolin, from conception to weaning or from prepuberty to young adulthood. A number of reproductive endpoints were assessed as well as testicular mRNA expression profiles, in the exposed rats and their unexposed progeny. Overall, the low dosage used only affected weakly most of classical reproductive endpoints. However, the gestational/lactational exposure to vinclozolin alone or combined to genistein significantly delayed the puberty onset. Contrasting with the gestational/lactational exposure, a decreased sperm production was found in the animals exposed to genistein and vinclozolin from the pre-pubertal period but also in their progeny for vinclozolin and the mixture. The expression level of several genes involved in meiosis, apoptosis and steroidogenesis was also affected differentially as a function of the exposure window in both exposed rats and unexposed offspring. We also provide further evidence that doses of endocrine active substances relevant with human exposure may affect the male reproductive phenotype and testicular transcriptome in the exposed generation as well as in the indirectly exposed offspring.

Sex-Specific Programming of Cardiac DNA Methylation by Developmental Phthalate Exposure

Phthalate plasticizers are ubiquitous chemicals linked to several cardiovascular diseases in animal models and humans. Despite this, the mechanisms by which phthalate exposures cause adverse cardiac health outcomes are unclear. In particular, whether phthalate exposures during pregnancy interfere with normal developmental programming of the cardiovascular system, and the resulting implications this may have for long-term disease risk, are unknown. Recent studies suggest that the effects of phthalates on metabolic and neurobehavioral outcomes are sex-specific. However, the influence of sex on cardiac susceptibility to phthalate exposures has not been investigated. One mechanism by which developmental exposures may influence long-term health is through altered programming of DNA methylation. In this work, we utilized an established mouse model of human-relevant perinatal exposure and enhanced reduced representation bisulfite sequencing to investigate the long-term effects of diethylhexyl phthalate (DEHP) exposure on DNA methylation in the hearts of adult male and female offspring at 5 months of age (n = 5-7 mice per sex and exposure). Perinatal DEHP exposure led to hundreds of sex-specific, differentially methylated cytosines (DMCs) and differentially methylated regions (DMRs) in the heart. Pathway analysis of DMCs revealed enrichment for several pathways in females, including insulin signaling, regulation of histone methylation, and tyrosine phosphatase activity. In males, DMCs were enriched for glucose transport, energy generation, and developmental programs. Notably, many sex-specific genes differentially methylated with DEHP exposure in our mouse model were also differentially methylated in published data of heart tissues collected from human heart failure patients. Together, these data highlight the potential role for DNA methylation in DEHP-induced cardiac effects and emphasize the importance of sex as a biological variable in environmental health studies.

Fetal-Maternal Exposure to Endocrine Disruptors: Correlation with Diet Intake and Pregnancy Outcomes

Endocrine-disrupting chemicals (EDCs) are exogenous substances able to mimic or to interfere with the endocrine system, thus altering key biological processes such as organ development, reproduction, immunity, metabolism and behavior. High concentrations of EDCs are found in several everyday products including plastic bottles and food containers and they could be easily absorbed by dietary intake. In recent years, considerable interest has been raised regarding the biological effects of EDCs, particularly Bisphenol A (BPA) and phthalates, on human pregnancy and fetal development. Several evidence obtained on in vitro and animal models as well as by epidemiologic and population studies strongly indicated that endocrine disruptors could negatively impact fetal and placental health by interfering with the embryonic developing epigenome, thus establishing disease paths into adulthood. Moreover, EDCs could cause and/or contribute to the onset of severe gestational conditions as Preeclampsia (PE), Fetal Growth Restriction (FGR) and gestational diabetes in pregnancy, as well as obesity, diabetes and cardiovascular complications in reproductive age. Therefore, despite contrasting data being present in the literature, endocrine disruptors must be considered as a therapeutic target. Future actions aimed at reducing or eliminating EDC exposure during the perinatal period are mandatory to guarantee pregnancy success and preserve fetal and adult health.

Environmental contaminants and male infertility: Effects and mechanisms

The escalating prevalence of male infertility and decreasing trend in sperm quality have been correlated with rapid industrialisation and the associated discharge of an excess of synthetic substances into the environment. Humans are inevitably exposed to these ubiquitously distributed environmental contaminants, which possess the ability to intervene with the growth and function of male reproductive organs. Several epidemiological reports have correlated the blood and seminal levels of environmental contaminants with poor sperm quality. Numerous in vivo and in vitro studies have been conducted to investigate the effect of various environmental contaminants on spermatogenesis, steroidogenesis, Sertoli cells, blood-testis barrier, epididymis and sperm functions. The reported reprotoxic effects include alterations in the spermatogenic cycle, increased germ cell apoptosis, inhibition of steroidogenesis, decreased Leydig cell viability, impairment of Sertoli cell structure and function, altered expression of steroid receptors, increased permeability of blood-testis barrier, induction of peroxidative and epigenetic alterations in spermatozoa resulting in poor sperm quality and function. In light of recent scientific reports, this review discusses the effects of environmental contaminants on the male reproductive function and the possible mechanisms of action.

Transgenerational epigenetic effects from male exposure to endocrine-disrupting compounds: a systematic review on research in mammals

Assessing long-term health effects from a potentially harmful environment is challenging. Endocrine-disrupting compounds (EDCs) have become omnipresent in our environment. Individuals may or may not experience clinical health issues from being exposed to the increasing environmental pollution in daily life, but an issue of high concern is that also the non-exposed progeny may encounter consequences of these ancestral exposures. Progress in understanding epigenetic mechanisms opens new perspectives to estimate the risk of man-made EDCs. However, the field of epigenetic toxicology is new and its application in public health or in the understanding of disease etiology is almost non-existent, especially if it concerns future generations. In this review, we investigate the literature on transgenerational inheritance of diseases, published in the past 10 years. We question whether persistent epigenetic changes occur in the male germ line after exposure to synthesized EDCs. Our systematic search led to an inclusion of 43 articles, exploring the effects of commonly used synthetic EDCs, such as plasticizers (phthalates and bisphenol A), pesticides (dichlorodiphenyltrichloroethane, atrazine, vinclozin, methoxychlor), dioxins, and polycyclic aromatic hydrocarbons (PAHs, such as benzo(a)pyrene). Most studies found transgenerational epigenetic effects, often linked to puberty- or adult-onset diseases, such as testicular or prostate abnormalities, metabolic disorders, behavioral anomalies, and tumor development. The affected epigenetic mechanisms included changes in DNA methylation patterns, transcriptome, and expression of DNA methyltransferases. Studies involved experiments in animal models and none were based on human data. In the future, human studies are needed to confirm animal findings. If not transgenerational, at least intergenerational human studies and studies on EDC-induced epigenetic effects on germ cells could help to understand early processes of inheritance. Next, toxicity tests of new chemicals need a more comprehensive approach before they are introduced on the market. We further point to the relevance of epigenetic toxicity tests in regard to public health of the current population but also of future generations. Finally, this review sheds a light on how the interplay of genetics and epigenetics may explain the current knowledge gap on transgenerational inheritance.

Endocrine Disruptors in Water and Their Effects on the Reproductive System

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

Acute and sub-acute bisphenol-B exposures adversely affect sperm count and quality in adolescent male mice

Bisphenol-B (BPB), an analogue of bisphenol-A is used in the plastic industry. It has been found to leach from plastic containers leading to its contamination in canned food products. Moreover, it has also been detected in human samples such as sera and urine. BPB is recognized as a potential endocrine disrupting chemical owing to its estrogenic and anti-androgenic nature. Therefore, it was pertinent to study the effect of BPB exposure during the adolescence age (5-6 weeks old) in male mice. Weekly intraperitoneal injections of 5, 10 and 15% LD₅₀ of BPB were given for 2 weeks to acute exposure groups and for 4 weeks to sub-acute exposure groups. BPB exposure induces change in enzymatic and non-enzymatic oxidative stress markers in sperm samples. DNA damage was also observed in sperm cells on acute and sub-acute exposures. Furthermore, BPB exposure led to a marked decline in sperm count and compromised sperm morphology. Computer assisted sperm analysis (CASA) revealed a significant decrease in sperm quality and progressive motility. Thus, both the acute and sub-acute exposures of adolescent male mice to BPB adversely affect the sperms' quality, functions and morphology.

Follistatin-like 3, an activin A binding protein, is involved in early pregnancy loss

BACKGROUND

Early pregnancy loss (EPL), a common and severe complication in pregnancy, has a long-term personal and social impact. It was previously reported that follistatin-like 3(FSTL3), an activin A binding protein, contributes to the invasion and migration of trophoblast. Simultaneously, activin A induces the release of FSTL3 and the elevated activin A is found to be associated with pregnancy loss in women. This study aimed to identify the roles of FSTL3 in the establishment and maintenance of pregnancy, and to determine whether FSTL3 is involved in the pathophysiology of EPL.

METHODS

Endometrial Ishikawa cells and JAR cells were cultured and FSTL3 siRNA was used to silence FSTL3. The trophoblast spheroids mimicking embryos were used in an embryonic adhesion system. The system aimed to investigate the role of FSTL3 silence on embryonic adhesion onto endometrial cell in vitro. The ICR mice model in vivo was used to investigate whether the FSTL3 works in embryonic implantation. The western blotting was used to determine the expression of FSTL3 and activin A.

RESULTS

In the in vitro study, silence of FSTL3 in JAR cells significantly reduced the number of trophoblast spheroids adhered onto Ishikawa cells compared with the scramble siRNA. For the in vivo study, the number of embryos implanted in the uterine horn injected with FATL3 siRNA mixture was significantly less than that in control group. In the case control study, both the expression of FSTL3 and activin A in EPL women were significantly higher than that in controls.

CONCLUSIONS

FSTL3 plays a biological role in the establishment and maintenance of normal pregnancy. Moreover, FSTL3 may be involved in the early pregnancy loss via neutralizing the elevated activin A.

Glycylglycine plays critical roles in the proliferation of spermatogonial stem cells

Glial cell line‑derived neurotrophic factor (GDNF) is critical for the proliferation of spermatogonial stem cells (SSCs), but the underlying mechanisms remain poorly understood. In this study, an unbiased metabolomic analysis was performed to examine the metabolic modifications in SSCs following GDNF deprivation, and 11 metabolites were observed to decrease while three increased. Of the 11 decreased metabolites identified, glycylglycine was observed to significantly rescue the proliferation of the impaired SSCs, while no such effect was observed by adding sorbitol. However, the expression of self‑renewal genes, including B‑cell CLL/lymphoma 6 member B, ETS variant 5, GDNF family receptor α1 and early growth response protein 4 remained unaltered following glycylglycine treatment. This finding suggests that although glycylglycine serves an important role in the proliferation of SSCs, it is not required for the self‑renewal of SSCs.

Transgenerational Effects of Endocrine-Disrupting Chemicals on Male and Female Reproduction

Endocrine-disrupting chemicals are known to interfere with normal reproductive function and hormone signaling. Phthalates, bisphenol A, pesticides, and environmental contaminants such as polychlorinated biphenyls and dioxins are known endocrine-disrupting chemicals that have been shown to negatively affect both male and female reproduction. Exposure to these chemicals occurs on a daily basis owing to these compounds being found in plastics, personal care products, and pesticides. Recently, studies have shown that these chemicals may cause transgenerational effects on reproduction in both males and females. This is of concern because exposure to these chemicals prenatally or during adult life can negatively impact the reproductive health of future generations. This mini-review summarizes the endocrine-disrupting chemicals that humans are exposed to on a daily basis and what is known about the transgenerational effects that these chemicals may have on male and female reproduction.

Adenomatous polyposis coli as a predictor of environmental chemical-induced transgenerational effects related to male infertility

Exposure to toxic environmental chemicals during pregnancy is a ubiquitous threat to health with potentially transgenerational consequences. However, the underlying mechanism of how transgenerational effects occur as part of environmental chemical exposure are not well understood. We investigated the potential molecular changes associated with dibutyl phthalate exposure that induced transgenerational effects, using a rat model. Through the analysis of the Gene Expression Omnibus database, we found some similar studies of environmental exposure induced transgenerational effects. Then, we analyzed one of the studies and our results to identify the adenomatous polyposis coli (APC) gene. This gene participated the most of the pathways and was upregulated in both studies. We used the miRWALK data set to predict the microRNAs which targeted the APC gene. We confirmed the miR-30 family were significantly downregulated in F3 testis tissues and targeted the APC gene. In conclusion, the miR-30 family/APC interaction is a potential mechanism for the transgenerational effects induced by the environmental chemical.

Effect of Nano-SiO2 on Expression and Aberrant Methylation of Imprinted Genes in Lung and Testis

Nanotechnology has been developing rapidly and is now used in many cutting-edge medical therapeutics. However, there is increasing concern that exposure to nanoparticles (NPs) may induce different systemic diseases as epigenetic mechanisms are associated with more and more disease. The role of NP epigenomic modification is important to disease etiology. Our study aimed to determine the epigenetic mechanisms of damage in lung and testis cells by exposing cells to SiO₂ NPs. We used male C57BL/6 mice to characterize the damaging effect of SiO₂ NPs on lung and testis cells as well as the resulting methylation state at the imprinted Dlk1/Dio3 domain region. The A549 cells exposed to SiO₂ NPs had cell apoptosis, and male mice exposed to SiO₂ NPs had altered lung and testis tissues. The genes in the imprinted domains Dlk1/Dio3 region changed in both tissues; Dlk1, Rtl1, and Dio3 are upregulated in testis while Dlk1 and Dio3 are also upregulated in lung tissues. Bisulfite sequencing PCR of male adult lung and testis were mostly hypomethylated, with a few hypermethylated CpGs. These findings indicate that nanoparticles play an important role in DNA methylation of imprinted genes.

Transgenerational impaired spermatogenesis with sperm H19 and Gtl2 hypomethylation induced by the endocrine disruptor p,p'-DDE

The hypothesis of fetal origins unraveled that environmental exposures in early life could alter epigenetic modifications in the male germ-line, increasing the susceptibility to adult-onset diseases for generations. In our previous study, p,p'-dichlorodiphenoxydichloroethylene (p,p'-DDE), a representative endocrine disruptor, was found to induce transgenerational impaired male fertility with sperm Igf2 hypomethylation. However, whether other imprinted genes involved remains uncovered. In the present study, we administered p,p'-DDE (100 mg/kg body weight) to pregnant Sprague-Dawley rats from gestational day (GD) 8 to GD15. Male F1 offspring were mated with the females from the same group to obtain F2 progeny. F3 progeny was obtained by inter-crossing the control and exposed F2 generation. Gestational exposure to p,p'-DDE impaired the testis histology and decreased the sperm fertility with H19 and Gtl2 hypomethylation in F1 offspring. Interestingly, this impaired spermatogenesis and DNA hypomethylation were maintained through F2 and F3 generations. DNA methyltransferase DNMT1 and 3a were significantly decreased in the embryonic testis of p,p'-DDE-treated F1 and F2 generation and returned to control levels by the F3 generation. p,p'-DDE induced a transgenerational impaired spermatogenesis with altered epigenetic modification, posing significant implications for disease etiology.

Proteomic profile and toxicity pathway analysis in zebrafish embryos exposed to bisphenol A and di-n-butyl phthalate at environmentally relevant levels

Bisphenol A (BPA) and di-n-butyl phthalate (DBP) are well-known endocrine-disrupting chemicals (EDCs) that have human health risks. Chronic exposure to BPA and DBP increases the occurrence of human disease. Despite the potential for exposure in embryonic development, the mechanism of action of BPA and DBP on vertebrate development and disease still remains unclear. In the present study, we identified proteins and protein networks that are perturbed by BPA and DBP during zebrafish (Danio rerio) development. Zebrafish embryos were exposed to environmentally relevant levels of BPA (10 μg/L) and DBP (50 μg/L) for 96 h. By iTRAQ labeling quantitative proteomics, a set of 26 and 41 differentially expressed proteins were identified in BPA- and DBP-treated zebrafish embryos, respectively. Integrated toxicity analysis predicted that these proteins function in common regulatory networks that are significantly associated with developmental and metabolic disorders. Exposure to low concentrations of BPA and DBP has potential health risks in zebrafish embryos. Our results also show that BPA and DBP significantly up-regulate the expression levels of multiple network proteins, providing valuable information about the molecular actions of BPA and DBP on the developmental systems.

MiR-301b-3p/3584-5p enhances low-dose mono-n-butyl phthalate (MBP)-induced proliferation by targeting Rasd1 in Sertoli cells

To investigate the possible molecular mechanism of low concentration plasticizer mono-n-butyl phthalate (MBP) -induced juvenile Sertoli cells (SCs) proliferation, we evaluated global alterations of miRNA and mRNA expression in rat SCs treated with 0.1mM MBP. Microarray analysis revealed that miR-3584-5p and miR-301b-3p were up-regulated and their common target gene Dexamethasone-induced Ras-related protein 1 (Rasd1) was down-regulated. Further work suggested that SCs proliferation induced by low concentration MBP in vitro might be mediated by Rasd1 regulating ERK1/2 signaling pathway. The present study is first to investigate the effect of low-dose MBP on SCs proliferation and may enhance our understanding on the modes of action of low concentration MBP on male reproductive system. We hope the results will contribute to explain the causes of precocious puberty and testicular tumors induced by exogenous chemicals.