Genome-wide transcriptome analysis reveals that Bisphenol A activates immune responses in skeletal muscle.

Cumulative human exposure to the environmental toxin, bisphenol A (BPA), has raised important health concerns in recent decades. However, the direct genomic regulation of BPA in skeletal muscles and its clinical significance are poorly understood. Therefore, we conducted a genome-wide transcriptome analysis after daily oral administration of BPA at the lowest observed adverse-effect level (LOAEL, 50 mg/kg) in male mice for six weeks to explore the gene-expression regulations in skeletal muscle induced by BPA. The primary Gene Ontology terms linked to BPA-dependent, differentially expressed genes at LOAEL comprised adaptive-immune response, positive regulation of T cell activation, and immune system process. The gene-set enrichment analysis disclosed increased complement-associated genes [complement components 3 (C3) and 4B, complement factor D, complement receptor 2, and immunoglobulin lambda constant 2] in the group administered with BPA, with a false-discovery rate of <0.05. Subsequent validation analysis conducted in BPA-fed animal skeletal muscle tissue and in vitro experiments confirmed that BPA induced immune activation, as evidenced by increased levels of C3 and C4α proteins in mice, C2C12 myoblasts, and mouse skeletal muscle cells. In addition, BPA markedly upregulated the transcription of tumor necrosis factor-α (Tnfα) in C2C12 myoblasts and mouse skeletal muscle cells, which was substantially inhibited by 5z-7-oxozeanol and parthenolide, providing further evidence of BPA-induced inflammation in muscle cells. Our bioinformatics and subsequent animal and in vitro validations demonstrate that BPA can activate inflammation in skeletal muscle, which could be a risk factor underlying chronic muscle weakness and wastage.

Development of a biomolecular approach to identify sperm functions and fertility using sperm RNAs.

Infertility affects a significant percentage of couples worldwide, and male factors contribute significantly to this problem. Traditional assessments of male fertility rely primarily on parameters such as sperm motility, morphology, viability, and concentration. However, these metrics often do not provide a comprehensive understanding of sperm function, which is critical not only for fertilization but also for successful embryo development. Herein, we used porcine spermatozoa as a model to investigate the potential of sperm RNA markers in assessing various aspects of sperm function from motility to fertility. Using artificial insemination, we evaluated male fertility based on the litter size of sows inseminated with sperm from 20 boars. In addition, we measured parameters such as weaning rate, death births, live births, and mummy births. Sperm functional parameters, including motility and kinematics, were assessed before and after in vitro capacitation. Finally, correlations between various sperm functional parameters and sperm RNA markers were explored. Our results revealed interesting relationships between sperm functional parameters. While motility and kinematics were correlated, they were not correlated with sperm capacitation status. Surprisingly, no significant correlations were found between these parameters and male fertility. However, specific parameters of sperm capacitation status after in vitro capacitation were correlated with weaning rate and live births, highlighting their importance in predicting successful fertilization. Further analysis of sperm RNA markers identified genes related to male fertility, including IZUMO1, known for its role in sperm-egg fusion. These genes showed correlations with motility, capacitation, and fertilization parameters, shedding light on their potential roles in sperm function. In conclusion, our study demonstrates that sperm RNA markers hold promise for the diagnosis and prognosis of various aspects of sperm function, providing valuable insights into male infertility. These markers may serve as diagnostic tools to improve our understanding of male fertility problems, ultimately benefiting couples struggling with infertility.

Bisphenol-A disturbs hormonal levels and testis mitochondrial activity, reducing male fertility.

STUDY QUESTION: How does bisphenol-A (BPA) influence male fertility, and which mechanisms are activated following BPA exposure? SUMMARY ANSWER: BPA exposure causes hormonal disruption and alters mitochondrial dynamics and activity, ultimately leading to decreased male fertility. WHAT IS KNOWN ALREADY: As public health concerns following BPA exposure are rising globally, there is a need to understand the exact mechanisms of BPA on various diseases. BPA exposure causes hormonal imbalances and affects male fertility by binding the estrogen receptors (ERs), but the mechanism of how it mediates the hormonal dysregulation is yet to be studied. STUDY DESIGN SIZE DURATION: This study consisted of a comparative study using mice that were separated into a control group and a group exposed to the lowest observed adverse effect level (LOAEL) (n = 20 mice/group) after a week of acclimatization to the environment. For this study, the LOAEL established by the US Environmental Protection Agency of 50 mg/kg body weight (BW)/day of BPA was used. The control mice were given corn oil orally. Based on the daily variations in BW, both groups were gavaged every day from 6 to 11 weeks (6-week exposure). Before sampling, mice were stabilized for a week. Then, the testes and spermatozoa of each mouse were collected to investigate the effects of BPA on male fertility. IVF was carried out using the cumulus-oocyte complexes from female hybrid B6D2F1/CrljOri mice (n = 3) between the ages of eight and twelve weeks. PARTICIPANTS/MATERIALS SETTING METHODS: Signaling pathways, apoptosis, and mitochondrial activity/dynamics-related proteins were evaluated by western blotting. ELISA was performed to determine the levels of sex hormones (FSH, LH, and testosterone) in serum. Hematoxylin and eosin staining was used to determine the effects of BPA on histological morphology and stage VII/VIII testicular seminiferous epithelium. Blastocyst formation and cleavage development rate were evaluated using IVF. MAIN RESULTS AND THE ROLE OF CHANCE: BPA acted by binding to ERs and G protein-coupled receptors and activating the protein kinase A and mitogen-activated protein kinase signaling pathways, leading to aberrant hormone levels and effects on the respiratory chain complex, ATP synthase and protein-related apoptotic pathways in testis mitochondria (P < 0.05). Subsequently, embryo cleavage and blastocyst formation were reduced after the use of affected sperm, and abnormal morphology of seminiferous tubules and stage VII and VIII seminiferous epithelial cells (P < 0.05) was observed. It is noteworthy that histopathological lesions were detected in the testes at the LOAEL dose, even though the mice remained generally healthy and did not exhibit significant changes in BW following BPA exposure. These observations suggest that testicular toxicity is more than a secondary outcome of compromised overall health in the mice due to systemic effects. LARGE SCALE DATA: Not applicable. LIMITATIONS REASONS FOR CAUTION: Since the protein expression levels in the testes were validated, in vitro studies in each testicular cell type (Leydig cells, Sertoli cells, and spermatogonial stem cells) would be required to shed further light on the exact mechanism resulting from BPA exposure. Furthermore, the BPA doses employed in this study significantly exceed the typical human exposure levels in real-life scenarios. Consequently, it is imperative to conduct experiments focusing on the effects of BPA concentrations more in line with daily human exposures to comprehensively assess their impact on testicular toxicity and mitochondrial activity. WIDER IMPLICATIONS OF THE FINDINGS: These findings demonstrate that BPA exposure impacts male fertility by disrupting mitochondrial dynamics and activities in the testes and provides a solid foundation for subsequent investigations into the effects on male reproductive function and fertility following BPA exposure, and the underlying mechanisms responsible for these effects. In addition, these findings suggest that the LOAEL concentration of BPA demonstrates exceptional toxicity, especially when considering its specific impact on the testes and its adverse consequences for male fertility by impairing mitochondrial activity. Therefore, it is plausible to suggest that BPA elicits distinct toxicological responses and mechanistic endpoints based on the particular concentration levels for each target organ. STUDY FUNDING/COMPETING INTERESTS: This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2018R1A6A1A03025159). No competing interests are declared.

Modulatory effects of bisphenol A on the hepatic immune response.

The liver is a primary line of defense for protection from external substances next to the intestinal barrier. As a result, the hepatic immune system plays a central role in liver pathophysiology. Bisphenol A (BPA) is one of the most common endocrine disrupting chemicals and is primarily metabolized in the liver. Due to its ability to bind to estrogen receptors, BPA is well known to possess estrogenic activity and disrupt reproductive functions. The phase I and Phase II metabolism reactions of BPA mainly occur in the liver with the help of enzymes including cytochrome P450 (CYP), uridine 5'-diphospho-glucuronosyltransferase-glucuronosyltransferases, sulfotransferases, and glutathione-S-transferases. Although the majority of BPA is excreted after conjugation by these enzymes, untransformed BPA induces the production of reactive oxygen species through disruption of the enzymatic complex CYP, lipid accumulation, mitochondrial dysfunction, endoplasmic reticulum stress and inflammatory injury in the liver. Moreover, it has been proposed to possess a potential immunomodulatory effect. Indeed, several in vivo and in vitro studies have reported that low doses of BPA increase the population of T cells with type 1 T helper (Th1), Th2, and Th17 cells. Although the current literature lacks clear evidence on the mechanisms by which BPA is involved in T cell mediated immune responses, recent multi-omics studies suggest that it may directly interact with the antigen processing and presentation pathways. In this review, we first discuss the metabolism of BPA in the liver, before exploring currently available data on its effects on liver injury. Finally, we review its modulatory effects on the hepatic immune response, as well as potential mechanisms. By conducting this review, we aim to improve understanding on the relationship between BPA exposure and immune-related liver injury, with a focus on the antigen processing and presentation pathway and T cell-mediated response in the liver.

Boar fertility is controlled through systematic changes of mitochondrial protein expression during sperm capacitation.

Vigorous activation of mitochondria in spermatozoa during capacitation induces the biological and morphological changes of spermatozoa to acquire fertilizing ability. To in-depth understand the dynamic roles of mitochondrial and male fertility, this study was to identify how the mitochondrial proteins are changed during sperm capacitation and regulate male fertility using boar spermatozoa. The mitochondrial proteins were differentially changed during sperm capacitation according to fertility status, i.e., superior litter size (SL) and normal litter size (NL). Following sperm capacitation, ubiquitin-cytochrome c reductase core protein (UQCRC1) and ATP synthase F1 (ATP5F1) increased in NL, while cytochrome c oxidase subunit 5B (COX5B), and cytochrome c1 (CYC1) proteins decreased. In contrast, only and ubiquinone oxidoreductase core subunit 8 (NDUFS8) protein was increased in SL following capacitation. The protein expression difference value of CYC1, COX5B, and NDUFS8 following sperm capacitation was lower in NL than SL boars. Based on these complicated changes during sperm capacitation, the accuracy for predicting male fertility of NDUFS8 was increased to 87 %. Overall, considering the systematic orchestration of mitochondrial protein expression according to sperm capacitation status, it will be possible to better understand male fertility.

Integration of omics studies indicates that species-dependent molecular mechanisms govern male fertility.

BACKGROUND: Comparative and comprehensive omics studies have recently been conducted to provide a comprehensive understanding of the biological mechanisms underlying infertility. However, because these huge omics datasets often contain irrelevant information, editing strategies for summarizing and filtering the data are necessary prerequisite steps for identifying biomarkers of male fertility. Here, we attempted to integrate omics data from spermatozoa with normal and below-normal fertility from boars and bulls, including transcriptomic, proteomic, and metabolomic data. Pathway enrichment analysis was conducted and visualized using g:Profiler, Cytoscape, EnrichmentMap, and AutoAnnotation to determine fertility-related biological functions according to species. RESULTS: In particular, gamete production and protein biogenesis-associated pathways were enriched in bull spermatozoa with below-normal fertility, whereas mitochondrial-associated metabolic pathways were enriched in boar spermatozoa with normal fertility. These results indicate that below-normal fertility may be determined by aberrant regulation of protein synthesis during spermatogenesis, and the modulation of reactive oxygen species generation to maintain capacitation and the acrosome reaction governs boar sperm fertility. CONCLUSION: Overall, this approach demonstrated that distinct molecular pathways drive sperm fertility in mammals in a species-dependent manner. Moreover, we anticipate that searching for species-specific signaling pathways may aid in the discovery of fertility-related biomarkers within large omics datasets.

Abnormal histone replacement following BPA exposure affects spermatogenesis and fertility sequentially.

Bisphenol A (BPA) is an endocrine-disrupting chemical widely distributed in the environment. Its exposure has been linked to male infertility in animals and humans due to its ability to induce epigenetic modification. Despite extensive research confirming the impact of BPA on epigenetic regulation, fundamental concerns about how BPA causes epigenetic changes and the underlying mechanism of BPA on the male reproductive system remain unresolved. Therefore, we sought to investigate the effects of BPA on epigenetic regulation and the histone-to-protamine (PRM) transition, which is fundamental process for male fertility in testes and spermatozoa by exposing male mice to BPA for 6 weeks while giving the mice in the control group corn oil by oral gavage. Our results demonstrated that the mRNA levels of the histone family and PRMs were significantly altered by BPA exposure in testes and spermatozoa. Subsequently, core histone proteins, the PRM1/PRM2 ratio, directly linked to male fertility, and transition proteins were significantly reduced. Furthermore, we discovered that BPA significantly caused abnormal histone-to-protamine replacement during spermiogenesis by increased histone variants-related to histone-to-PRM transition. The levels of histone H3 modification in the testes and DNA methylation in spermatozoa were significantly increased. Consequently, sperm concentration/motility/hyperactivation, fertilization, and early embryonic development were adversely affected as a consequence of altered signaling proteins following BPA exposure. To our knowledge, this is the first study to indicate that BPA exposure influences the histone-to-PRM transition via altering epigenetic modification and eventually causing reduced male fertility.

Establishment of a male fertility prediction model with sperm RNA markers in pigs as a translational animal model.

BACKGROUND: Male infertility is an important issue that causes low production in the animal industry. To solve the male fertility crisis in the animal industry, the prediction of sperm quality is the most important step. Sperm RNA is the potential marker for male fertility prediction. We hypothesized that the expression of functional genes related to fertilization will be the best target for male fertility prediction markers. To investigate optimum male fertility prediction marker, we compared target genes expression level and a wide range of field data acquired from artificial insemination of boar semen. RESULTS: Among the genes related to acrosomal vesicle exocytosis and sperm-oocyte fusion, equatorin (EQTN), zona pellucida sperm-binding protein 4 (ZP4), and sperm acrosome membrane-associated protein 3 exhibited high accuracy (70%, 90%, and 70%, respectively) as markers to evaluate male fertility. Combinations of EQTN-ZP4, ZP4-protein unc-13 homolog B, and ZP4-regulating synaptic membrane exocytosis protein 1 (RIMS1) showed the highest prediction value, and all these markers are involved in the acrosome reaction. CONCLUSION: The EQTN-ZP4 model was efficient in clustering the high-fertility group and may be useful for selection of animal that has superior fertility in the livestock industry. Compared to the EQTN-ZP4 model, the ZP4-RIMS1 model was more efficient in clustering the low-fertility group and may be useful in the diagnosis of male infertility in humans and other animals. The appointed translational animal model and established biomarker combination can be widely used in various scientific fields such as biomedical science.

Hepatic consequences of a mixture of endocrine-disrupting chemicals in male mice.

The global epidemic of metabolic syndrome has been partially linked to ubiquitous exposure to endocrine-disrupting chemicals (EDCs). Although the impacts of exposure to single EDCs have been thoroughly studied, the consequences of simultaneous uncontrolled exposure to multiple EDCs require further investigations. Therefore, in this study, we evaluated how exposure to mixtures containing bisphenol A and seven phthalates impacts liver functions and metabolic homeostasis. Male mice were gavaged with either EDCs at four different dose combinations or corn oil (control) for six weeks. The results showed that exposure to EDCs at the human daily exposure limit had a negligible impact on liver function. However, EDC at ≥ 25 orders of magnitude of human-relevant doses had detrimental impacts on overall liver function, leading to metabolic abnormalities, steatohepatitis, and hepatic fibrosis via the activation of both genomic and non-genomic pathways. The metabolic phenotype was linked to alterations in key genes involved in hepatic lipid and glucose metabolism. In contrast, alterations in cytokine expression, oxidative stress, and apoptosis impacted steatohepatitis and fibrosis. Because EDC exposure does not occur independently, the findings of the combined effects of exposure to multiple EDCs have significant relevance for public health.

Systematic multi-omics reveals the overactivation of T cell receptor signaling in immune system following bisphenol A exposure.

Bisphenol A (BPA) is pervasive in the environment, and exposure to BPA may increase the incidence of noncommunicable diseases like autoimmune diseases and cancer. Although BPA causes immunological problems at the cellular level, no system-level research has been conducted on this. Hence, in this study, we aimed to gain a better understanding of the biological response to BPA exposure and its association with immunological disorders. For that, we explored the transcriptome and the proteomic modifications at the systems and cellular levels following BPA exposure. Our integrated multi-omics data showed the alteration of the T cell receptor (TCR) signaling pathway at both levels. The proportion of enlarged T cells increased with upregulation of CD69, a surface marker of early T cell activation, even though the number of T cells reduced after BPA exposure. Additionally, on BPA exposure, the levels of pLCK and pSRC increased in T cells, while that of pLAT decreased. Following BPA exposure, we investigated cytokine profiles and discovered that chitinase 3 Like 1 and matrix metalloproteinase 9 were enriched in T cells. These results indicated that T cells were hyperactivated by CD69 stimulation, and phosphorylation of SRC accelerated on BPA exposure. Hence, alteration in the TCR signaling pathway during development and differentiation due to BPA exposure could lead to insufficient and hasty activation of TCR signaling in T cells, which could modify cytokine profiles, leading to increased environmental susceptibility to chronic inflammation or diseases, increasing the chance of autoimmune diseases and cancer. This study enhances our understanding of the effects of environmental perturbations on immunosuppression at molecular, cellular, and systematic levels following pubertal BPA exposure, and may help develop better predictive, preventative, and therapeutic techniques.

Heat shock protein family D member 1 in boar spermatozoa is strongly related to the litter size of inseminated sows.

BACKGROUND: Sperm quality evaluation is the logical first step in increasing field fertility. Spermatozoa contain cytoplasmic organelles and biomolecules known as sperm-intrinsic factors, which play key roles in sperm maturation, sperm-oocyte fusion, and embryo development. In particular, sperm membrane proteins [e.g., arginine vasopressin receptor 2, beta-actin, prohibitin, and heat shock protein family D member 1 (HSPD1)] and RNA could be used as functional indicators of male fertility. We sought to clarify the effects of differential mRNA expression of selected genes on several fertilisation parameters, including sperm motility, motion kinematics, capacitation, and litter size, in a porcine model. RESULTS: Our results demonstrated that HSPD1 expression was significantly correlated with male fertility, as measured by the litter size of inseminated sows. The expression of HSPD1 mRNA was linked to sperm motility and other motion kinematic characteristics. Furthermore, HSPD1 had a 66.7% overall accuracy in detecting male fertility, and the high-litter size group which was selected with the HSPD1 marker had a 1.34 greater litter size than the low-litter size group. CONCLUSIONS: Our findings indicate that HSPD1 might be a helpful biomarker for superior boar selection for artificial insemination, which could boost field fertility.

Low Sperm Motility Is Determined by Abnormal Protein Modification during Epididymal Maturation.

PURPOSE: During epididymal sperm maturation, spermatozoa acquire progressive motility through dynamic protein modifications. However, the relationship between sequential protein modifications during epididymal sperm maturation and sperm motility and fertility has not yet been investigated. This study investigated whether sequential changes in fertility-related protein expression including that of enolase 1 (ENO1), ubiquinol-cytochrome c reductase core protein 1 and 2 (UQCRC1 and UQCRC2), and voltage-dependent anion channel 2 (VDAC2) in spermatozoa during epididymal maturation are related to bovine sperm motility. Moreover, we found that mitochondrial metabolism is closely related to fertility-related proteins. Therefore, we investigated how the sequential modification of mitochondrial proteins during epididymal maturation regulates sperm motility. MATERIALS AND METHODS: To determine the differential protein expression in caput and cauda epididymal spermatozoa from low and high motility bulls, western blot analysis was performed. Moreover, signaling pathways were identified to understand the mechanisms of regulation of sperm motility through the differential protein expression associated with fertility-related proteins. RESULTS: We found that ENO1 was substantially higher in the caput spermatozoa from low motility bulls than the caput and cauda spermatozoa from high motility bulls. However, ENO1 expression in low motility bull spermatozoa was downregulated to a level comparable to that in the high motility bull spermatozoa during epididymal maturation. Moreover, there was a lack of modification of mitochondrial proteins, including glutathione peroxidase 4 and NADH:Ubiquinone Oxidoreductase Core Subunit S8, in low motility bull spermatozoa during epididymal maturation, whereas active changes were detected in high motility bull spermatozoa. CONCLUSIONS: Irregular modifications of mitochondrial proteins during epididymal sperm maturation may increase excessive ROS production and premature activation of spermatozoa during epididymal maturation. Consequently, spermatozoa may lose their motility by the earlier consumption of their energy source and may be damaged by ROS during epididymal maturation, resulting in a decline in sperm motility and bull fertility.

Bisphenol A damages testicular junctional proteins transgenerationally in mice.

Testicular junctions are pivotal to male fertility and regulated by constituent proteins. Increasing evidence suggests that environmental chemicals, including bisphenol A (BPA), may impact these proteins, but whether the impacts persist for generations is not yet known. Here, we investigate the effect of BPA (a ubiquitous endocrine-disrupting chemical) on testis and sperm functions and whether the effects are transferred to subsequent generations. Male mice (F0) were exposed to corn oil (Control) or 5 or 50 mg BPA/kg body weight/day from 6 to 12 weeks of age. The F0 were mated with wild-type females to produce the first filial (F1) generation. F2 and F3 were produced using similar procedures. Our results showed that BPA doses decreased the levels of some junctional proteins partly via binding with estrogen receptors (ERα and Erß), upregulation of p-ERK1/2, P85, p-JNK and activation of p38 mitogen-activated protein kinase signaling. Consequently, testicular histological abnormalities, disrupted spermatogenesis, decreased sperm count, and inability to fertilize eggs were observed in mice exposed to BPA. These effects were transferred to successive generations (F2), partly through DNA methylation, but mostly alleviated in F3 males. Our findings suggest that paternal exposure to chemicals promoting alteration of testicular junctional proteins and its transgenerational inheritance is a key component of the origin of male reproductive health problems.

Short-term storage of semen samples in acidic extender increases the proportion of females in pigs.

BACKGROUND: Sex preselection is a desired goal of the animal industry to improve production efficiency, depending on industry demand. In the porcine industry, there is a general preference for pork from female and surgically castrated male pigs. Therefore, the birth of more females than males in a litter leads to economic benefits and improved animal welfare in the pig production industry. Our previous study suggested that the porcine semen extender (BTS) adjusted to pH 6.2 maximises the differences in viability between X-chromosome-bearing (X) spermatozoa and Y-chromosome-bearing (Y) spermatozoa without affecting sperm's functional parameters. In this study we aimed to evaluate whether the pH 6.2 extender is applicable at the farm level for increasing the number of female piglets without a decline in spermatozoa fertility. Artificial insemination (AI) was carried out with spermatozoa stored at pH 6.2 and pH 7.2 (original BTS) at day 1 and day 2 of storage. Next, the functional parameters of the spermatozoa, litter size, farrowing rate, and female-to-male ratio of offspring were determined. RESULTS: Although sperm motility decreased significantly after 2 d of storage, the viability of spermatozoa was preserved at pH 6.2 for 3 d. There was no significant difference in the farrowing rate and average litter size between the group inseminated with the spermatozoa stored in (pH 7.2) and that inseminated with spermatozoa stored in acidic BTS. The percentage of female piglets was approximately 1.5-fold higher in sows inseminated on day 1 in the pH 6.2 than in the pH 7.2 group. Furthermore, although there was no significant difference in the female-to-male ratio, the percentage of female piglets born was slightly higher in the pH 6.2 group than in the pH 7.2 group on day 2. CONCLUSIONS: The method optimised in our study is simple, economical, and may enhance the number of female births without any decline in spermatozoa fertility.

Role of Insulin in Health and Disease: An Update.

Insulin is a polypeptide hormone mainly secreted by ß cells in the islets of Langerhans of the pancreas. The hormone potentially coordinates with glucagon to modulate blood glucose levels; insulin acts via an anabolic pathway, while glucagon performs catabolic functions. Insulin regulates glucose levels in the bloodstream and induces glucose storage in the liver, muscles, and adipose tissue, resulting in overall weight gain. The modulation of a wide range of physiological processes by insulin makes its synthesis and levels critical in the onset and progression of several chronic diseases. Although clinical and basic research has made significant progress in understanding the role of insulin in several pathophysiological processes, many aspects of these functions have yet to be elucidated. This review provides an update on insulin secretion and regulation, and its physiological roles and functions in different organs and cells, and implications to overall health. We cast light on recent advances in insulin-signaling targeted therapies, the protective effects of insulin signaling activators against disease, and recommendations and directions for future research.

Drivers of owning more BPA.

Bisphenol A (BPA) is a ubiquitous environmental toxin worldwide. Despite the many studies documenting the toxicity of this substance, it remains a popular choice for consumer products. The internet, magazine articles, and newspaper reports are replete with tips on how to avoid BPA exposure, which mostly spread contradictory and often unscientific information. Therefore, based on a comprehensive search of the available biomedical literature, we summarized several confounding factors that may be directly or indirectly related to human BPA exposure. We found that the unique properties of BPA materials (i.e. low cost, light-weight, resistance to corrosion, and water/air-tightness), lack of personal health and hygiene education, fear of BPA-substitutes (with yet unknown risks), inappropriate production, processing, and marketing of materials containing BPA, as well as the state of regulatory guidance are influencing the increased exposure to BPA. Besides, we detailed the disparities between scientifically derived safe dosages of BPA and those designated as "safe" by government regulatory agencies. Therefore, in addition to providing a current assessment of the states of academic research, government policies, and consumer behaviors, we make several reasonable and actionable recommendations for limiting human exposure to BPA through improved labeling, science-based dosage limits, and public awareness campaigns.

Multigenerational impacts of gestational bisphenol A exposure on the sperm function and fertility of male mice.

Growing evidence suggests that developmental exposure to bisphenol A (BPA)-a synthetic endocrine disruptor-causes atypical reproductive phenotypes that may persist for generations. However, the precise mechanism(s) by which BPA causes these adverse consequences is unclear. Here, pregnant female mice were orally exposed to 50 µg, 5 mg, and 50 mg BPA/kg body weight (bw)/day from 7 to 14 days of gestation. Corn oil treatments were used as control. The first filial generation (F1) and F2 males were used to generate F3 by mating them with unexposed females. High BPA doses impaired F1 and/or F1-F2 (multigenerational effect) male reproduction (i.e., disrupted testicular germ cell organization and spermatogenesis, altered sperm biochemical properties, and decreased sperm count, motility, and fertility) but not that of F3 males (transgenerational effect). Moreover, the observed multigenerational transmission of the abnormal reproductive traits was associated with alterations in the sperm DNA methylation patterns of specific male generations, with substantial proteomic changes in F1-F3 at the highest BPA dose. Given that the proteins related to male fertility and epigenetic modification are highly conserved among vertebrates, our findings may shed light on how exposure to environmental factors during pregnancy affects fertility in future generations in both humans and the other animals.

Endocrine-Disrupting Chemicals and Infectious Diseases: From Endocrine Disruption to Immunosuppression.

Endocrine-disrupting chemicals (EDCs) are hormonally active compounds in the environment that interfere with the body's endocrine system and consequently produce adverse health effects. Despite persistent public health concerns, EDCs remain important components of common consumer products, thus representing ubiquitous contaminants to humans. While scientific evidence confirmed their contribution to the severity of Influenza A virus (H1N1) in the animal model, their roles in susceptibility and clinical outcome of the coronavirus disease (COVID-19) cannot be underestimated. Since its emergence in late 2019, clinical reports on COVID-19 have confirmed that severe disease and death occur in persons aged ≥65 years and those with underlying comorbidities. Major comorbidities of COVID-19 include diabetes, obesity, cardiovascular disease, hypertension, cancer, and kidney and liver diseases. Meanwhile, long-term exposure to EDCs contributes significantly to the onset and progression of these comorbid diseases. Besides, EDCs play vital roles in the disruption of the body's immune system. Here, we review the recent literature on the roles of EDCs in comorbidities contributing to COVID-19 mortality, impacts of EDCs on the immune system, and recent articles linking EDCs to COVID-19 risks. We also recommend methodologies that could be adopted to comprehensively study the role of EDCs in COVID-19 risk.

Effects of phthalates on the functions and fertility of mouse spermatozoa.

Phthalates are common environmental pollutants that are presumed to negatively impact male fertility including animals and humans. Particularly, these potential xenoestrogens may alter male fertility by binding to specific sperm receptors. Although several studies have characterized the toxic effects of single phthalates, epidemiological studies indicate that humans are typically exposed to phthalate mixtures. Here, we tested an environmental-related phthalate combination composed of 21 % di(2-ethylhexyl) phthalate, 15 % diisononyl phthalate, 8% diisobutyl phthalate, 15 % dibutyl phthalate, 35 % diethyl phthalate, and 5% benzylbutyl phthalate. Specifically, the effects of short-term exposure (90 min) to various concentrations (1, 10, 100, and 500 µg/mL) of this phthalate mixture on several important sperm processes, oocyte fertilization, and embryo production were assessed. All phthalate concentrations significantly decreased sperm motility and hyperactivity by compromising the sperm's ability to generate ATP. Additionally, short-term phthalate exposure (>10 µg/mL) also induced abnormal capacitation and the acrosome reaction by upregulating protein tyrosine phosphorylation via a protein kinase-A-dependent pathway. Furthermore, phthalate exposure (particularly at doses exceeding 10 µg/mL) significantly affected fertilization and early embryonic development. Together, our findings indicate that the studied phthalate mixtures adversely affected sperm motility, capacitation, and acrosome reaction, which resulted in poor fertilization rates and repressed embryonic development. Moreover, the lowest-observed-adverse-effect dose of the phthalate mixture tested can be assumed to be < 1 µg/mL in vitro.

Mitochondrial Functionality in Male Fertility: From Spermatogenesis to Fertilization.

Mitochondria are structurally and functionally distinct organelles that produce adenosine triphosphate (ATP) through oxidative phosphorylation (OXPHOS), to provide energy to spermatozoa. They can also produce reactive oxidation species (ROS). While a moderate concentration of ROS is critical for tyrosine phosphorylation in cholesterol efflux, sperm-egg interaction, and fertilization, excessive ROS generation is associated with male infertility. Moreover, mitochondria participate in diverse processes ranging from spermatogenesis to fertilization to regulate male fertility. This review aimed to summarize the roles of mitochondria in male fertility depending on the sperm developmental stage (from male reproductive tract to female reproductive tract). Moreover, mitochondria are also involved in testosterone production, regulation of proton secretion into the lumen to maintain an acidic condition in the epididymis, and sperm DNA condensation during epididymal maturation. We also established the new signaling pathway using previous proteomic data associated with male fertility, to understand the overall role of mitochondria in male fertility. The pathway revealed that male infertility is associated with a loss of mitochondrial proteins in spermatozoa, which induces low sperm motility, reduces OXPHOS activity, and results in male infertility.