Low doses of bisphenol A induce gene expression related to lipid synthesis and trigger triglyceride accumulation in adult mouse liver

Low-dose tire wear chemical 6PPD-Q exposure elicit fatty liver via promoting fatty acid biosynthesis in ICR mice

N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPD-Q) as a major metabolite of tire wear chemical 6PPD has been demonstrated to be an emerging burden of exposure in human populations, via contamination from drinking water, air particulate matter and food sources. Whilst increasing attention has been moved toward its adverse effect, the potential hepatotoxicity of 6PPD-Q in mammals at realistic dose remains unknown. Here, the toxic effects of 6PPD-Q at environmentally relevant dose on the liver of adult mice and its underlying mechanism were investigated through an integrative approach combining transcriptomic and lipidomic analyses. We found that 6PPD-Q exposure induced excessive lipid deposition following three weeks of exposure, ultimately contributing to the pathogenesis of fatty liver disease. Mechanistically, 6PPD-Q exposure caused a remarkable increase in the contents of fatty acids within the hepatic tissue of mice by enhancing their biosynthesis, thereby facilitating lipid deposition. In summary, this study provides a new understanding on the endocrine disrupting effects of 6PPD-Q on hepatic lipid metabolism and how it may contribute to elevated risk of fatty liver disease. Our findings call for a potential public health attention on the risk assessment of 6PPD-Q, particularly towards the risk of chronic metabolic diseases.

Activation of steroid hormone receptors by metabolism-disrupting chemicals

Exposure to metabolism-disrupting chemicals (MDCs), compounds largely belonging to the group of endocrine-disrupting chemicals (EDCs), is associated with metabolic dysfunctions such as dyslipidemia, insulin resistance and hepatic steatosis. Steroid hormone receptors (SHRs) are known targets for MDCs but their regulatory environment in the presence of environmental chemicals remains elusive. Here, we studied the activation and molecular interactions of SHRs exposed to 17 suspected MDCs including pesticides, plasticizers, pharmaceuticals, flame retardants, industrial chemicals and their metabolites by combining in vitro and in silico approaches. We first established and pre-validated reporter gene assays in HepG2 hepatoma cells to assess the activation of estrogen (ER), androgen (AR), glucocorticoid (GR) and progesterone (PR) receptors. Next, using RNA-seq and publicly available protein interaction data, we identified relevant SHR-interacting coregulators expressed in hepatic cells and measured their MDC-dependent interactions with SHRs using the Microarray Assay for Real-time Coregulator-Nuclear receptor Interaction (MARCoNI) technology. Finally, we examined MDC binding to ER and GR using molecular dynamics simulations. These combined approaches lead to identification of MDCs capable of SHR activation at picomolar-to-low micromolar concentrations and paralleled with their ability to induce recruitment of multiple coregulators. MDCs induced distinct SHR-coregulator binding patterns involving multiple coactivators, corepressors and other modulatory proteins. Our results have broadened the test battery to detect MDCs and indicate that the activation of SHRs by MDCs is driven by diverse molecular interactions.

Exposure of Bisphenols (BPA, BPB and BPC) in HepG2 Cells Results in Lysosomal Dysfunction and Lipid Accumulation

Nonalcoholic fatty liver disease poses a significant public health concern, as do the issues surrounding plastic usage. The bisphenols are reported to cause fat accumulation in the liver. However, literature is scanty about the effect of bisphenols on lysosomes or lysosomal functions. We predicted the interaction of bisphenols with lysosomal proteins available in the online databases using in silico tools. Molecular docking revealed that chosen Bisphenols interact with critical lysosomal proteins including lipid hydrolyzing enzymes. Following exposure of BPA, BPB and BPC to HepG2 cells fat accumulation and lysosomal functions were evaluated. Exposure to BPB and BPC results intracellular fat accumulation under experimental conditions like BPA. All three Bisphenols disturb lysosomal homeostasis perhaps by different mechanisms. Overall our results suggest that Bisphenols can also cause fat accumulation in liver by disturbing lysosomal homeostasis.

Avian-Specific Evidence for an Estrogen Receptor Agonism Adverse Outcome Pathway Based on Chicken Embryos and LMH 3D Spheroids Exposed to Ethinylestradiol and Bisphenol A

Several adverse outcome pathways (AOPs) describe the effects of endocrine disrupting compounds on estrogen signaling. Substantial data support an AOP related to estrogen receptor (ER) antagonism, leading to decreased fecundity in fish. In this study, data were generated for an ER agonism AOP leading to reduced fecundity in avian species (AOP537). Chicken embryos and the chicken leghorn male hepatoma cell line, LMH, were used to elucidate key events associated with estrogen signaling following exposure to 17α-ethinylestradiol (EE2) and bisphenol A (BPA). Embryos were exposed via egg injection. Viability and hepatic estrogen-responsive gene expression data were collected at midincubation (embryonic day [ED] 11). Changes in plasma vitellogenin (VTG), gonad morphology and growth were evaluated prior to pipping (ED20). Both chemicals dysregulated estrogen-responsive genes in hepatic tissue and increased plasma VTG concentrations. In LMH spheroids, EE2 and BPA altered estrogen-responsive genes and VTG concentrations at 24 and 48 h, respectively. Gonadal histology revealed oocyte-type cells and loss of testicular cords in male embryos exposed to EE2 and BPA. Overall, EE2 and BPA upregulated VTG mRNA expression, increased plasma VTG, and caused impairments in gonadal development. These results contribute avian-specific evidence to support an endocrine disruption AOP describing the relationship between disrupted VTG synthesis and impaired reproduction.

The obesogenic effects of Bisphenol A and its analogues are differentially regulated via PPARγ transactivation in mouse 3T3-L1 cells

Exposure to environmental pollutants with obesogenic activity is being recognised as one of the contributing factors to the obesity epidemic. Bisphenol A (BPA) has been shown to stimulate adipogenesis in both human and mouse preadipocytes, to increase body weight and affect lipid metabolism in animal and epidemiological studies. Regulatory action and public concern has prompted industry to replace BPA with other structurally similar analogues that may have similar effects. In this study we investigated the effects of fifteen BPA analogues on adipogenesis in the mouse 3 T3-L1 pre-adipocyte cell model in order to determine their adipogenic activity relative to BPA. 3 T3-L1 cells were treated with increasing concentrations of BPA and replacements and mRNA expression of the mature adipocyte markers fatty acid binding protein 4 (Fabp4), perilipin (Plin) lipoprotein lipase (Lpl)and peroxisome proliferator-activated receptor (Ppar)γ and lipid accumulation were assessed. In addition, a luciferase reporter assay for PPARγ transactivation was employed to investigate mechanism of action. Our results show that BPC, BPS-MAE, BPS-MPE and TGSA, were the most adipogenic bisphenols, as shown by a robust increase in lipid accumulation and mRNA expression of adipogenic markers. BPS-MPE, BPC, BTUM, TGSA and D8 increased PPARγ transcriptional activity. Despite its ability to activate PPARγ in the transcriptional assay D8 did not affect adipogenesis in this cell model.

Overview of the hazardous impacts of metabolism-disrupting chemicals on the progression of fatty liver diseases

Background

Given the global increase in obesity, metabolic dysfunction-associated steatotic liver disease (MASLD) is a major health concern. Because the liver is the primary organ for xenobiotic metabolism, the impact of environmental stressors on liver homeostasis and MASLD has garnered significant interest over the past few decades. The concept of metabolism-disrupting chemicals (MDCs) has been introduced to underscore the importance of environmental factors in metabolic homeostasis. Recent epidemiological and biological studies suggest a causal link between exposure to MDCs and prevalence and progression of MASLD.

Objective

This review aims to introduce the emerging concept of MDCs and their representative toxic mechanisms. In particular, this review focuses on broadening the understanding of their impacts on MASLD or metabolic dysfunction-associated steatohepatitis (MASH) progression.

Result

Recent research has highlighted the environmental contaminants, such as heavy metals, microplastics, and pesticides, have the potential to influence hepatic metabolism and aggravate MASLD/MASH progression. These MDCs not only directly affect lipid metabolism in hepatocytes but also affect other cell types, such as immune cells and stellate cells, as well as the gut-liver axis.

Conclusion

Collectively, these findings contribute to establishing a well-defined adverse outcome pathway and identify novel therapeutic options for liver diseases associated with pollutants.

Bisphenol A induces sex-dependent alterations in the neuroendocrine response of Djungarian hamsters to photoperiod

In nature, species synchronize reproduction and energy metabolism with seasons to optimize survival and growth. This study investigates the effect of oral exposure to bisphenol A (BPA) on phenotypic and neuroendocrine seasonal adaptations in the Djungarian hamster, which in contrast to conventional laboratory rodents, is a well-recognized seasonal model. Adult female and male hamsters were orally exposed to BPA (5, 50, or 500 μg/kg/d) or vehicle during a 10-week transition from a long (LP) to short (SP) photoperiod (winter transition) or vice versa (summer transition). Changes in body weight, food intake, and pelage color were monitored weekly and, at the end of the exposure, expression of hypophysio-hypothalamic markers of photoperiodic (TSHβ, deiodinases), reproductive (Rfrp, kisspeptin) and metabolic (somatostatin, Pomc) integration, reproductive organ activity, and glycemia were assessed. Our results revealed sex-specific effects of BPA on acquiring SP and LP phenotypes. During LP to SP transition, females exposed to 500 μg/kg/d BPA exhibited delayed body weight loss and reduced feed efficiency associated with a lower expression of somatostatin, while males exposed to 5 μg/kg/d BPA showed an accelerated acquisition of SP-induced metabolic parameters. During SP to LP transition, females exposed to 5 μg/kg/d BPA displayed a faster LP adaptation in reproductive and metabolic parameters, along with kisspeptin downregulation occurring 5 weeks earlier and Pomc upregulation delayed for up to 10 weeks. In males, BPA exposure led to decreased expression of central photoperiodic integrators, with no effect on the acquisition of the LP phenotype. This pioneering study investigating EDCs' effects on mammalian seasonal physiology shows that BPA alters the dynamics of metabolic adaptation to both SP and LP transitions with marked sex dimorphism, causing temporal discordance in seasonal adaptation between males and females. These findings emphasize the importance of investigating EDCs' effects on non-conventional animal models, providing insights into wildlife physiology.

Unravelling bisphenol A-induced hepatotoxicity: Insights into oxidative stress, inflammation, and energy dysregulation

Bisphenol A (BPA), a prevalent plastic monomer and endocrine disruptor, negatively impacts metabolic functions. This study examines the chronic effects of eco-relevant BPA concentrations on hepatotoxicity, focusing on redox balance, inflammatory response, cellular energy sensors, and metabolic homeostasis in male Swiss albino mice. Chronic BPA exposure resulted in reactive oxygen species (ROS) accumulation, altered hepatic antioxidant defense, lipid peroxidation, and NOX4 expression, leading to reduced cell viability. Additionally, BPA exposure significantly upregulated hepatic pro-inflammatory cytokine genes (Tnf-α, Il-1β, Il-6), NOS2, and arginase II, correlating with increased TLR4 expression, NF-κB phosphorylation, and a dose-dependent decrease in IκBα levels. BPA-induced NF-κB nuclear localization and inflammasome activation (NLRP3, cleaved caspase-1, IL-1β) established an inflammatory milieu. Perturbations in hepatic AMPKα phosphorylation, SIRT1, and PGC-1α, along with elevated p38 MAPK phosphorylation and ERα expression, indicated BPA-induced energy dysregulation. Furthermore, increased PLA2G4A, COX1, COX2, and PTGES2 expression in BPA-treated liver correlated with hyperlipidemia, hepatic FASN expression, steatosis, and visceral adiposity, likely due to disrupted energy sensors, oxidative stress, and inflammasome activation. Elevated liver enzymes (ALP, AST, ALT) and apoptotic markers indicated liver damage. Notably, N-acetylcysteine (NAC) priming reversed BPA-induced hepatocellular ROS accumulation, NF-κB-inflammasome activation, and intracellular lipid accumulation, while upregulating cellular energy sensors and attenuating ERα expression, suggesting NAC's protective effects against BPA-induced hepatotoxicity. Pharmacological inhibition of the NF-κB/NLRP3 cascade in BAY11-7082 pretreated, or NLRP3 immunodepleted hepatocytes reversed BPA's negative impact on SIRT1/p-AMPKα/PGC-1α and intracellular lipid accumulation, providing mechanistic insights into BPA-induced metabolic disruption.

Oxidative Stress and Keap1-Nrf2 Pathway Involvement in Bisphenol A-Induced Liver Damage in Rats

Bisphenol A (BPA), extensively utilized in the manufacture of epoxy resins and polycarbonate plastics, is prevalent in the environment. Its exposure has been associated with an increased risk of hepatic lesions; however, the underlying mechanisms and the spectrum of its effects remain poorly understood. This study investigates the role of the Keap1-Nrf2 signaling pathway in regulating BPA-induced hepatotoxicity in vivo using a rat model. Over a 30-day period, rats were orally administered either corn oil or BPA (0.5, 5, and 50 mg/kg). Changes in hepatic and kidney histology were assessed via transmission electron microscopy and HE staining. Oxidative stress levels in the liver tissue and serum were quantified, while the mRNA expression of Nrf2, Keap1, GPX2, HO-1, and caspase-3 was evaluated using qRT-PCR. Additionally, the expression of Nrf2 and cleaved caspase-3 in the liver tissue was measured through immunohistochemistry and Western blotting. Results indicated that BPA exposure significantly reduced the liver and adrenal coefficients in the treated rats compared to controls. Notable histomorphological alterations were observed in the liver and kidney tissues of the BPA-treated rats. The serum levels of GOT and TNF-α were significantly elevated in the BPA group relative to the controls. Evidence of oxidative stress was supported by increased malondialdehyde levels and decreased total superoxide dismutase activity in the liver and kidney, alongside a reduction in glutathione peroxidase activity in the liver tissue. Furthermore, BPA exposure enhanced the mRNA expression levels of Nrf2, Keap1, GPX2, HO-1, and caspase-3 in the liver tissue. Concurrently, Nrf2 and cleaved caspase-3 expression levels were elevated in the BPA-treated group compared to the controls. These findings suggest that BPA may contribute to metabolic disorders of liver function and poses a hepatotoxicity risk. Moreover, the activation of the Keap1-Nrf2 pathway may offer protective effects against hepatotoxicity, with potential implications for human liver disease.

Interference with Systemic Negative Feedback Regulation as a Potential Mechanism for Nonmonotonic Dose-Responses of Endocrine-Disrupting Chemicals

Background

Endocrine-disrupting chemicals (EDCs) often exhibit nonmonotonic dose-response (NMDR) relationships, posing significant challenges to health risk assessment and regulations. Several molecular mechanisms operating locally in cells have been proposed, including opposing actions via different receptors, mixed-ligand heterodimer formation, and receptor downregulation. Systemic negative feedback regulation of hormone homeostasis, which is a common feature of many endocrine systems, has also been invoked as a mechanism; however, whether and how exactly such global feedback structure may underpin NMDRs is poorly understood.

Objectives

We hypothesize that an EDC may compete with the endogenous hormone for receptors (i) at the central site to interfere with the feedback regulation thus altering the physiological hormone level, and (ii) at the peripheral site to disrupt the hormone action; this dual-action may oppose each other, producing nonmonotonic endocrine effects. The objective here is to explore - through computational modeling - how NMDRs may arise through this potential mechanism and the relevant biological variabilities that enable susceptibility to nonmonotonic effects.

Methods

We constructed a dynamical model of a generic hypothalamic-pituitary-endocrine (HPE) axis with negative feedback regulation between a pituitary hormone and a terminal effector hormone (EH). The effects of model parameters, including receptor binding affinities and efficacies, on NMDR were examined for EDC agonists and antagonists. Monte Carlo human population simulations were then conducted to systemically explore biological parameter conditions that engender NMDR.

Results

When an EDC interferes sufficiently with the central feedback action of EH, the net endocrine effect at the peripheral target site can be opposite to what is expected of an agonist or antagonist at low concentrations. J/U or Bell-shaped NMDRs arise when the EDC has differential binding affinities and/or efficacies, relative to EH, for the peripheral and central receptors. Quantitative relationships between these biological variabilities and associated distributions were discovered, which can distinguish J/U and Bell-shaped NMDRs from monotonic responses.

Conclusions

The ubiquitous negative feedback regulation in endocrine systems can act as a universal mechanism for counterintuitive and nonmonotonic effects of EDCs. Depending on key receptor kinetic and signaling properties of EDCs and endogenous hormones, some individuals may be more susceptible to these complex endocrine effects.

Medaka liver developed Human NAFLD-NASH transcriptional signatures in response to ancestral bisphenol A exposure

The progression of fatty liver disease to non-alcoholic steatohepatitis (NASH) is a leading cause of death in humans. Lifestyles and environmental chemical exposures can increase the susceptibility of humans to NASH. In humans, the presence of bisphenol A (BPA) in urine is associated with fatty liver disease, but whether ancestral BPA exposure leads to the activation of human NAFLD-NASH-associated genes in the unexposed descendants is unclear. In this study, using medaka fish as an animal model for human NAFLD, we investigated the transcriptional signatures of human NAFLD-NASH and their associated roles in the pathogenesis of the liver of fish that were not directly exposed, but their ancestors were exposed to BPA during embryonic and perinatal development three generations prior. Comparison of bulk RNA-Seq data of the liver in BPA lineage male and female medaka with publicly available human NAFLD-NASH patient data revealed transgenerational alterations in the transcriptional signature of human NAFLD-NASH in medaka liver. Twenty percent of differentially expressed genes (DEGs) were upregulated in both human NAFLD patients and medaka. Specifically in females, among the total shared DEGs in the liver of BPA lineage fish and NAFLD patient groups, 27.69% were downregulated, and 20% were upregulated. Of all DEGs, 52.31% of DEGs were found in ancestral BPA-lineage females, suggesting that NAFLD in females shared the majority of human NAFLD gene networks. Pathway analysis revealed beta-oxidation, lipoprotein metabolism, and HDL/LDL-mediated transport processes linked to downregulated DEGs in BPA lineage males and females. In contrast, the expression of genes encoding lipogenesis-related proteins was significantly elevated in the liver of BPA lineage females only. BPA lineage females exhibiting activation of myc, atf4, xbp1, stat4, and cancerous pathways, as well as inactivation of igf1, suggest their possible association with an advanced NAFLD phenotype. The present results suggest that gene networks involved in the progression of human NAFLD and the transgenerational NAFLD in medaka are conserved and that medaka can be an excellent animal model to understand the development and progression of liver disease and environmental influences in the liver.

Addressing chemically-induced obesogenic metabolic disruption: selection of chemicals for in vitro human PPARα, PPARγ transactivation, and adipogenesis test methods

Whilst western diet and sedentary lifestyles heavily contribute to the global obesity epidemic, it is likely that chemical exposure may also contribute. A substantial body of literature implicates a variety of suspected environmental chemicals in metabolic disruption and obesogenic mechanisms. Chemically induced obesogenic metabolic disruption is not yet considered in regulatory testing paradigms or regulations, but this is an internationally recognised human health regulatory development need. An early step in the development of relevant regulatory test methods is to derive appropriate minimum chemical selection lists for the target endpoint and its key mechanisms, such that the test method can be suitably optimised and validated. Independently collated and reviewed reference and proficiency chemicals relevant for the regulatory chemical universe that they are intended to serve, assist regulatory test method development and validation, particularly in relation to the OECD Test Guidelines Programme. To address obesogenic mechanisms and modes of action for chemical hazard assessment, key initiating mechanisms include molecular-level Peroxisome Proliferator-Activated Receptor (PPAR) α and γ agonism and the tissue/organ-level key event of perturbation of the adipogenesis process that may lead to excess white adipose tissue. Here we present a critical literature review, analysis and evaluation of chemicals suitable for the development, optimisation and validation of human PPARα and PPARγ agonism and human white adipose tissue adipogenesis test methods. The chemical lists have been derived with consideration of essential criteria needed for understanding the strengths and limitations of the test methods. With a weight of evidence approach, this has been combined with practical and applied aspects required for the integration and combination of relevant candidate test methods into test batteries, as part of an Integrated Approach to Testing and Assessment for metabolic disruption. The proposed proficiency and reference chemical list includes a long list of negatives and positives (20 chemicals for PPARα, 21 for PPARγ, and 11 for adipogenesis) from which a (pre-)validation proficiency chemicals list has been derived.

Sex-specific expression of the human NAFLD-NASH transcriptional signatures in the liver of medaka with a history of ancestral bisphenol A exposure

The progression of fatty liver disease to non-alcoholic steatohepatitis (NASH) is a leading cause of death in humans. Lifestyles and environmental chemical exposures can increase the susceptibility of humans to NASH. In humans, the presence of bisphenol A (BPA) in urine is associated with fatty liver disease, but whether ancestral BPA exposure leads to the activation of human NAFLD-NASH-associated genes in the unexposed descendants is unclear. In this study, using medaka fish as an animal model for human NAFLD, we investigated the transcriptional signatures of human NAFLD-NASH and their associated roles in the pathogenesis of the liver of fish who were not directly exposed but their ancestors were exposed to BPA during embryonic and perinatal development three generations prior. Comparison of bulk RNA-Seq data of the liver in BPA lineage male and female medaka with publicly available human NAFLD-NASH patient data revealed transgenerational alterations in the transcriptional signature of human NAFLD-NASH in medaka liver. Twenty percent of differentially expressed genes (DEGs) were upregulated in both human NAFLD patients and medaka. Specifically in females, among the total shared DEGs in the liver of BPA lineage fish and NAFLD patient groups, 27.69% DEGs were downregulated and 20% DEGs were upregulated. Off all DEGs, 52.31% DEGs were found in ancestral BPA-lineage females, suggesting that NAFLD in females shared majority of human NAFLD gene networks. Pathway analysis revealed beta-oxidation, lipoprotein metabolism, and HDL/LDL-mediated transport processes linked to downregulated DEGs in BPA lineage males and females. In contrast, the expression of genes encoding lipogenesis-related proteins was significantly elevated in the liver of BPA lineage females only. BPA lineage females exhibiting activation of myc, atf4, xbp1, stat4, and cancerous pathways, as well as inactivation of igf1, suggest their possible association with an advanced NAFLD phenotype. The present results suggest that gene networks involved in the progression of human NAFLD and the transgenerational NAFLD in medaka are conserved and that medaka can be an excellent animal model to understand the development and progression of liver disease and environmental influences in the liver.

Deciphering the molecular mechanism of NLRP3 in BPA-mediated toxicity: Implications for targeted therapies

Bisphenol-A (BPA), a pervasive industrial chemical used in polymer synthesis, is found in numerous consumer products including food packaging, medical devices, and resins. Detectable in a majority of the global population, BPA exposure occurs via ingestion, inhalation, and dermal routes. Extensive research has demonstrated the adverse health effects of BPA, particularly its disruption of immune and endocrine systems, along with genotoxic potential. This review focuses on the complex relationship between BPA exposure and the NOD-like receptor protein 3 (NLRP3) inflammasome, a multiprotein complex central to inflammatory disease processes. We examine how BPA induces oxidative stress through the generation of intracellular free radicals, subsequently activating NLRP3 signaling. The mechanistic details of this process are explored, including the involvement of signaling cascades such as PI3K/AKT, JAK/STAT, AMPK/mTOR, and ERK/MAPK, which are implicated in NLRP3 inflammasome activation. A key focus of this review is the wide-ranging organ toxicities associated with BPA exposure, including hepatic, renal, gastrointestinal, and cardiovascular dysfunction. We investigate the immunopathogenesis and molecular pathways driving these injuries, highlighting the interplay among BPA, oxidative stress, and the NLRP3 inflammasome. Finally, this review explores the emerging concept of targeting NLRP3 as a potential therapeutic strategy to mitigate the organ toxicities stemming from BPA exposure. This work integrates current knowledge, emphasizes complex molecular mechanisms, and promotes further research into NLRP3-targeted interventions.

Chronic exposure to 3,6-dichlorocarbazole exacerbates non-alcoholic fatty liver disease in zebrafish by disrupting lipid metabolism and inducing special lipid biomarker accumulation

Most previous studies have focused primarily on the adverse effects of environmental chemicals on organisms of good healthy. Although global prevalence of non-alcoholic fatty liver disease (NAFLD) has reached approximately 25%, the impact of environmentally persistent organic chemicals on organisms with NAFLD is substantially unknown. Polyhalogenated carbazoles (PHCZs) as emerging contaminants have been frequently detected in the environment and organisms. In this study, we investigated the impact of the most frequently detected PHCZs, 3,6-dichlorocarbazole (36-CCZ), on zebrafish with high-fat diet (HFD)-induced NAFLD. After 4 weeks exposure to environmentally relevant concentrations of 36-CCZ (0.16-0.45 μg/L), the accumulation of lipid in zebrafish liver dramatically increased, and the transcription of genes involved in lipid synthesis, transport and oxidation was significantly upregulated, demonstrating that 36-CCZ had exacerbated the NAFLD in zebrafish. Lipidomic analysis indicated that 36-CCZ had significantly affected liver lipid metabolic pathways, mainly including glycerolipids and glycerophospholipids. Additionally, fifteen lipids were identified as potential lipid biomarkers for 36-CCZ exacerbation of NAFLD, including diacylglycerols (DGs), triglycerides (TGs), phosphatidylcholines (PCs), phosphatidylethanolamines (PEs), phosphatidic acid (PA), and phosphatidylinositol (PI). These findings demonstrate that long-term exposure to 36-CCZ can promote the progression of NAFLD, which will contribute to raising awareness of the health risks of PHCZs.

Metabolic effects of nuclear receptor activation in vivo after 28-day oral exposure to three endocrine-disrupting chemicals

Environmental exposure to endocrine-disrupting chemicals (EDCs) can lead to metabolic disruption, resulting in metabolic complications including adiposity, dyslipidemia, hepatic lipid accumulation, and glucose intolerance. Hepatic nuclear receptor activation is one of the mechanisms mediating metabolic effects of EDCs. Here, we investigated the potential to use a repeated dose 28-day oral toxicity test for identification of EDCs with metabolic endpoints. Bisphenol A (BPA), pregnenolone-16α-carbonitrile (PCN), and perfluorooctanoic acid (PFOA) were used as reference compounds. Male and female wild-type C57BL/6 mice were orally exposed to 5, 50, and 500 μg/kg of BPA, 1000, 10 000, and 100 000 µg/kg of PCN and 50 and 300 μg/kg of PFOA for 28 days next to normal chow diet. Primary endpoints were glucose tolerance, hepatic lipid accumulation, and plasma lipids. After 28-day exposure, no changes in body weight and glucose tolerance were observed in BPA-, PCN-, or PFOA-treated males or females. PCN and PFOA at the highest dose in both sexes and BPA at the middle and high dose in males increased relative liver weight. PFOA reduced plasma triglycerides in males and females, and increased hepatic triglyceride content in males. PCN and PFOA induced hepatic expression of typical pregnane X receptor (PXR) and peroxisome proliferator-activated receptor (PPAR)α target genes, respectively. Exposure to BPA resulted in limited gene expression changes. In conclusion, the observed changes on metabolic health parameters were modest, suggesting that a standard repeated dose 28-day oral toxicity test is not a sensitive method for the detection of the metabolic effect of EDCs.

Systematic transcriptome-wide meta-analysis across endocrine disrupting chemicals reveals shared and unique liver pathways, gene networks, and disease associations

Cardiometabolic disorders (CMD) are a growing public health problem across the world. Among the known cardiometabolic risk factors are compounds that induce endocrine and metabolic dysfunctions, such as endocrine disrupting chemicals (EDCs). To date, how EDCs influence molecular programs and cardiometabolic risks has yet to be fully elucidated, especially considering the complexity contributed by species-, chemical-, and dose-specific effects. Moreover, different experimental and analytical methodologies employed by different studies pose challenges when comparing findings across studies. To explore the molecular mechanisms of EDCs in a systematic manner, we established a data-driven computational approach to meta-analyze 30 human, mouse, and rat liver transcriptomic datasets for 4 EDCs, namely bisphenol A (BPA), bis(2-ethylhexyl) phthalate (DEHP), tributyltin (TBT), and perfluorooctanoic acid (PFOA). Our computational pipeline uniformly re-analyzed pre-processed quality-controlled microarray data and raw RNAseq data, derived differentially expressed genes (DEGs) and biological pathways, modeled gene regulatory networks and regulators, and determined CMD associations based on gene overlap analysis. Our approach revealed that DEHP and PFOA shared stable transcriptomic signatures that are enriched for genes associated with CMDs, suggesting similar mechanisms of action such as perturbations of peroxisome proliferator-activated receptor gamma (PPARγ) signaling and liver gene network regulators VNN1 and ACOT2. In contrast, TBT exhibited highly divergent gene signatures, pathways, network regulators, and disease associations from the other EDCs. In addition, we found that the rat, mouse, and human BPA studies showed highly variable transcriptomic patterns, providing molecular support for the variability in BPA responses. Our work offers insights into the commonality and differences in the molecular mechanisms of various EDCs and establishes a streamlined data-driven workflow to compare molecular mechanisms of environmental substances to elucidate the underlying connections between chemical exposure and disease risks.

Bisphenol A (BPA) exposure aggravates hepatic oxidative stress and inflammatory response under hypertensive milieu - Impact of low dose on hepatocytes and influence of MAPK and ER stress pathways

Human exposure to the hazardous chemical, Bisphenol A (BPA), is almost ubiquitous. Due to the prevalence of hypertension (CVD risk factor) in the aged human population, it is necessary to explore its adverse effect in hypertensive subjects. The current study exposed the Nω-nitro-l-arginine methyl ester (L-NAME) induced hypertensive Wistar rats to human exposure relevant low dose of BPA (50 μg/kg) for 30 days period. The liver biochemical parameters, histopathology, immunohistochemistry, gene expression (RT-qPCR), trace elements (ICP-MS), primary rat hepatocytes cell culture and metabolomic (1H NMR) assessments were performed. Results illustrate that BPA exposure potentiates/aggravates hypertension induced tissue abnormalities (hepatic fibrosis), oxidative stress, ACE activity, malfunction of the antioxidant system, lipid abnormalities and inflammatory factor (TNF-α and IL-6) expression. Also, in cells, BPA increased ROS generation, mitochondrial dysfunction and lipid peroxidation without any impact on cytotoxicity and caspase 3 and 9 activation. Notably, BPA exposure modulate lipid metabolism (cholesterol and fatty acid) in primary hepatocytes. Finally, the influence of ERK1/2, p38MAPK, ER stress and oxidative stress during relatively high dose of BPA elicited cytotoxicity was observed. Therefore, a precise hazardous risk investigation of BPA exposure in hypertensive populations is highly recommended.

Gestational exposure to bisphenol S induces microvesicular steatosis in male rat offspring by modulating metaflammation

Prenatal exposure to endocrine-disrupting bisphenol A (BPA) shows a long-lasting programming effect on an organ's metabolic function and predisposes it to the risk of adult metabolic diseases. Although a reduced contaminant risk due to "BPA-free" exposure is proposed, limited data on a comparative assessment of gestational exposure to BPS and BPA and their effects on metaflammation in predisposing liver metabolic disease is reported. Pregnant Wistar rats were exposed to BPS and BPA (0.0, 0.4, 4.0 μg/kg bw) via gavage from gestational day 4 to 21, and effects were assessed in the 90 d male offspring. Prenatal BPS-exposed offspring showed a more obesogenic effect than BPA, including changes in body fat distribution, feed efficiency, and leptin signalling. The BPS exposure induced the adipocyte hypertrophy of visceral adipose to a greater extent than BPA. The adipose hypertrophy was augmented by tissue inflammation, endoplasmic reticulum (ER) stress, and apoptosis due to increased expression of pro-inflammatory (IL6, IL1β, CRP, COX2) cytokines, ER stress modulator (CHOP), and apoptotic effector (Caspase 3). The enlarged, stressed, inflamed adipocytes triggered de novo lipogenesis in the bisphenol-exposed offspring liver due to increased expression of cholesterol and lipid biogenesis mediators (srebf1, fasn, acaca, PPARα) concomitant with elevated triacylglycerol (TG) and cholesterol (TC), resulted in impaired hepatic clearance of lipids. The lipogenic effects were also promoted by increased expression of HSD11β1. BPS exposure increased absolute liver weight, discoloration, altered liver lobes more than in BPA. Liver histology showed numerous lipid droplets, and hepatocyte ballooning, upregulated ADRP expression, an increased expression of pro-inflammatory mediators (IL6, CRP, IL1β, TNFα, COX2), enhanced lipid peroxidation in the BPS-exposed offspring's liver suggest altered metaflammation leads to microvesicular steatosis. Overall, gestational BPS exposure demonstrated a higher disruption in metabolic changes than BPA, involving excess adiposity, liver fat, inflammation, and predisposition to steatosis in the adult male offspring.

Bisphenol A (BPA) and Cardiovascular or Cardiometabolic Diseases

Bisphenol A (BPA; 4,4'-isopropylidenediphenol) is a well-known endocrine disruptor. Most human exposure to BPA occurs through the consumption of BPA-contaminated foods. Cardiovascular or cardiometabolic diseases such as diabetes, obesity, hypertension, acute kidney disease, chronic kidney disease, and heart failure are the leading causes of death worldwide. Positive associations have been reported between blood or urinary BPA levels and cardiovascular or cardiometabolic diseases. BPA also induces disorders or dysfunctions in the tissues associated with these diseases through various cell signaling pathways. This review highlights the literature elucidating the relationship between BPA and various cardiovascular or cardiometabolic diseases and the potential mechanisms underlying BPA-mediated disorders or dysfunctions in tissues such as blood vessels, skeletal muscle, adipose tissue, liver, pancreas, kidney, and heart that are associated with these diseases.

In vitro to in vivo extrapolation for predicting human equivalent dose of phenolic endocrine disrupting chemicals: PBTK model development, biological pathways, outcomes and performance

In vitro to in vivo (IVIVE) leverages in vitro high-throughput biological responses to predict the corresponding in vivo exposures and further estimate the human safe dose. However, for phenolic endocrine disrupting chemicals (EDCs) linked with complicated biological pathways and adverse outcomes (AO), such as bisphenol A (BPA) and 4-nonylphenol (4-NP), plausible estimation of human equivalent doses (HED) by IVIVE approaches considering various biological pathways and endpoints is still challenging. To explore the capabilities and limitations of IVIVE, this study conducted physiologically based toxicokinetic (PBTK)-IVIVE approaches to derive pathway-specific HEDs using BPA and 4-NP as examples. In vitro HEDs of BPA and 4-NP varied in different adverse outcomes, pathways, and testing endpoints and ranged from 0.0013 to 1.0986 mg/kg bw/day and 0.0551 to 1.7483 mg/kg bw/day, respectively. In vitro HEDs associated with reproductive AOs initiated by PPARα activation and ER agonism were the most sensitive. Model verification suggested the potential of using effective in vitro data to determine reasonable approximation of in vivo HEDs for the same AO (fold differences of most AOs ranged in 0.14-2.74 and better predictions for apical endpoints). Furthermore, system-specific parameters of cardiac output and its fraction, body weight, as well as chemical-specific parameters of partition coefficient and liver metabolic were most sensitive for the PBTK simulations. The results indicated that the application of fit for-purpose PBTK-IVIVE approach could provide credible pathway-specific HEDs and contribute to high throughput prioritization of chemicals in a more realistic scenario.

A lipidomic approach to bisphenol F-induced non-alcoholic fatty liver disease-like changes: altered lipid components in a murine model

Bisphenol A (BPA), a typical environmental endocrine disruptor, is an "obesogen" that can induce lipid accumulation in the liver. Highly similar in structure to BPA, bisphenol F (BPF) is becoming the dominant BPA substitute on the market, which attracts more and more attention due to its potential adverse effects. Recently, BPF exposure is found to cause non-alcoholic fatty liver disease (NAFLD)-like changes; however, the underlying toxic effects remain poorly understood. Therefore, in the current study, we focused on BPF-mediated lipid homeostasis, especially the alterations of lipid components and metabolism. In human serum, the BPF levels in healthy controls and NAFLD patients were assessed by ELISA, and BPF-induced disturbance of lipid metabolism was evaluated in mouse model via non-targeted lipomic methods with ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry. It suggested that BPF exposure was positively correlated with NAFLD severity and triglyceride level in patients. Based on the relationships, lipid metabolites were assessed in mouse livers between control and BPF-treated group, and it revealed that twenty-six lipid metabolites (including phospholipids, sphingolipids, and glycerides) were significantly changed in mouse livers. Phosphatidylcholine, phosphatidylethanolamine, and diglyceryl ester levels were lower than those in the control mice; hexose ceramide content in sphingolipids markedly increased in BPF-treated mouse livers. Noteworthily, the glycerophospholipid metabolic pathway was found to be the most pronounced in BPF-induced disturbance of lipid metabolism. Therefore, the current study, for the first time, is deciphering the BPF-induced lipid metabolic disturbance, which may provide novel intervention strategies for BPF-induced NAFLD-like changes.

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.

Effects of BPA Exposure and Recovery on the Expression of Genes Involved in the Hepatic Lipid Metabolism in Male Mice

Exposure to Bisphenol A (BPA) has led to an increased risk of obesity and nonalcoholic fatty liver diseases (NAFLDs). However, it is as yet unclear if the damage caused by BPA is able to be repaired sufficiently after exposure has ceased. Therefore, this project aims to investigate the effects of BPA on the hepatic lipid metabolism function and its potential mechanisms in mice by comparing the BPA exposure model and the BPA exposure + cessation of drug treatment model. Herein, the male C57BL/6 mice were exposed in the dose of 50 μg/kg/day and 500 μg/kg/day BPA for 8 weeks, and then transferred to a standard chow diet for another 8 weeks to recover. Based on our previous RNA-seq study, we examined the expression patterns of some key genes. The results showed that the mice exposed to BPA manifested NAFLD features. Importantly, we also found that there was a significant expression reversion for SCD1, APOD, ANGPT4, PPARβ, LPL and G0S2 between the exposure and recovery groups, especially for SCD1 and APOD (p < 0.01). Notably, BPA could significantly decrease the level of APOD protein (p < 0.01) whereas there was an extremely significant increase after the exposure ceased. Meanwhile, APOD over-expression suppressed TG accumulation in the AML12 cells. In conclusion, the damage caused by BPA is able to be repaired by the upregulation of APOD and exposure to BPA should be carefully examined in chronic liver metabolic disorders or diseases.

Curcumin protects against bisphenol A-induced hepatic steatosis by inhibiting cholesterol absorption and synthesis in CD-1 mice

Curcumin is a polyphenol extracted from the rhizome of turmeric, and our previous research showed that curcumin inhibited cholesterol absorption and had cholesterol-lowering effect. Bisphenol A (BPA), a common plasticizer, is widely used in the manufacture of food packaging and is associated with non-alcoholic fatty liver disease (NAFLD). We hypothesized that curcumin could protect against BPA-induced hepatic steatosis by inhibiting cholesterol absorption and synthesis. Male CD-1 mice fed BPA-contaminated diet with or without curcumin for 24 weeks were used to test our hypothesis. We found that chronic low-dose BPA exposure significantly increased the levels of serum triglyceride (TG), total cholesterol (TC), and low-density lipoprotein cholesterol and the contents of liver TG and TC, resulting in liver fat accumulation and hepatic steatosis while curcumin supplementation could alleviate BPA-induced dyslipidemia and hepatic steatosis. Moreover, the anti-steatosis and cholesterol-lowering effects of curcumin against BPA coincided with a significant reduction in intestinal cholesterol absorption and liver cholesterol synthesis, which was modulated by suppressing the expression of sterol regulatory element-binding protein-2 (SREBP-2), Niemann-Pick C1-like 1 (NPC1L1), and 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) in the small intestine and liver. In addition, the expression levels of liver lipogenic genes such as liver X receptor alpha (LXRα), SREBP-1c, acetyl-CoA carboxylase 1 (ACC1), and ACC2 were also markedly down-regulated by curcumin. Overall, our findings indicated that curcumin inhibited BPA-induced intestinal cholesterol absorption and liver cholesterol synthesis by suppressing SREBP-2, NPC1L1, and HMGCR expression, subsequently reducing liver cholesterol accumulation and fat synthesis, thereby preventing hepatic steatosis and NAFLD.

The PCOS-NAFLD Multidisease Phenotype Occurred in Medaka Fish Four Generations after the Removal of Bisphenol A Exposure

As a heterogeneous reproductive disorder, polycystic ovary syndrome (PCOS) can be caused by genetic, diet, and environmental factors. Bisphenol A (BPA) can induce PCOS and nonalcoholic fatty liver disease (NAFLD) due to direct exposure; however, whether these phenotypes persist in future unexposed generations is not currently understood. In a previous study, we observed that transgenerational NAFLD persisted in female medaka for five generations (F4) after exposure to an environmentally relevant concentration (10 μg/L) of BPA. Here, we demonstrate PCOS in the same F4 generation female medaka that developed NAFLD. The ovaries contained immature follicles, restricted follicular progression, and degenerated follicles, which are characteristics of PCOS. Untargeted metabolomic analysis revealed 17 biomarkers in the ovary of BPA lineage fish, whereas transcriptomic analysis revealed 292 genes abnormally expressed, which were similar to human patients with PCOS. Metabolomic-transcriptomic joint pathway analysis revealed activation of the cancerous pathway, arginine-proline metabolism, insulin signaling, AMPK, and HOTAIR regulatory pathways, as well as upstream regulators esr1 and tgf signaling in the ovary. The present results suggest that ancestral BPA exposure can lead to PCOS phenotypes in the subsequent unexposed generations and warrant further investigations into potential health risks in future generations caused by initial exposure to EDCs.

BPA interferes with granulosa cell development and oocyte meiosis in mouse preantral follicles

Bisphenol A (BPA) is an established environmental endocrine disruptor and can interfere with the development of female germ cells. However, the underlying mechanisms are still unclear. We investigated the effects of BPA on granulosa cell development and meiosis of oocytes using in vitro culture system of mouse preantral follicles. Preantral follicles from D14 mouse ovary were treated with 10 μg/mL BPA in vitro for 11 days. The adherent area of follicles was measured. On D11, cumulus cell expansion was observed. The meiosis recovery rate was calculated. Western blot detected P53, proliferating cell nuclear antigen (PCNA), estrogen receptor α (ERα), and cyclin B1. ELISA measured estrogen and progesterone levels. Immunofluorescence detected Cx37 on oocyte membrane. Gap junction communication was assessed. We found that BPA significantly promoted the expressions of PCNA and ERα in granulosa cells and the secretion of estrogen and progesterone by granulosa cells on D10 and significantly increased the attachment area of the follicles on D8 and D10. However, it reduced the expansion of cumulus cells, Cx37 expression, and the gap junction communication between cumulus cells and oocytes on D11. BPA promoted the recovery of oocytes from meiosis, interrupted the expression of cyclin B1 protein in arrested germinal vesicle breakdown (GVBD) oocytes, and reduced the in vitro maturation rate of oocytes. These GVBD oocytes were live without apoptosis or death. Conclusively, BPA disturbs the development of granulosa cells and the meiosis progression of oocytes by decreasing gap junction communication between oocytes and the granulosa cells as well as regulating cyclin B1 expression in GVBD oocytes.

Interaction of metabolism-related pathway gene variants with bisphenol A exposure on serum lipid profiles

Bisphenol A (BPA) can be metabolized by metabolic enzymes and may induce abnormal lipid metabolism. We hypothesized that BPA exposure and its interaction with metabolism-related genes might be associated with serum lipid profiles. We performed a two-stage study among 955 middle-aged and elderly participants in Wuhan, China. Urinary BPA level was estimated without (BPA, μg/L) or with (BPA/Cr, μg/g) adjustments for urinary creatinine and ln-transformed values (ln-BPA or ln-BPA/Cr) were used to normalize the asymmetrical distributions. A total of 412 metabolism-related gene variants were selected and used for gene-BPA interaction analysis. Multiple linear regression was used to analyze the interactions between BPA exposure and metabolism-related genes on serum lipid profiles. In the discovery stage, both ln-BPA and ln-BPA/Cr was associated with decreased high-density lipoprotein cholesterol (HDL-C). Gene-urinary BPA interaction for IGFBP7 rs9992658 was observed to associate with HDL-C levels in both discovery and validation stages, with P_interaction equal to 9.87×10^-4 (ln-BPA) and 1.22×10^-3 (ln-BPA/Cr) in combined analyses. In addition, the inverse association of urinary BPA with HDL-C levels was only observed among individuals carrying rs9992658 AA genotype, but not in individuals carrying rs9992658 AC or CC genotypes. The interaction between BPA exposure and metabolism-related gene IGFBP7 (rs9992658) was associated with HDL-C levels. AVAILABILITY OF DATA AND MATERIAL: Not applicable.

Endocrine disruptors in plastics alter β-cell physiology and increase the risk of diabetes mellitus

Plastic pollution breaks a planetary boundary threatening wildlife and humans through its physical and chemical effects. Of the latter, the release of endocrine disrupting chemicals (EDCs) has consequences on the prevalence of human diseases related to the endocrine system. Bisphenols (BPs) and phthalates are two groups of EDCs commonly found in plastics that migrate into the environment and make low-dose human exposure ubiquitous. Here we review epidemiological, animal, and cellular studies linking exposure to BPs and phthalates to altered glucose regulation, with emphasis on the role of pancreatic β-cells. Epidemiological studies indicate that exposure to BPs and phthalates is associated with diabetes mellitus. Studies in animal models indicate that treatment with doses within the range of human exposure decreases insulin sensitivity and glucose tolerance, induces dyslipidemia, and modifies functional β-cell mass and serum levels of insulin, leptin, and adiponectin. These studies reveal that disruption of β-cell physiology by EDCs plays a key role in impairing glucose homeostasis by altering the mechanisms used by β-cells to adapt to metabolic stress such as chronic nutrient excess. Studies at the cellular level demonstrate that BPs and phthalates modify the same biochemical pathways involved in adaptation to chronic excess fuel. These include changes in insulin biosynthesis and secretion, electrical activity, expression of key genes, and mitochondrial function. The data summarized here indicate that BPs and phthalates are important risk factors for diabetes mellitus and support a global effort to decrease plastic pollution and human exposure to EDCs.

Bayesian matrix completion for hypothesis testing

We aim to infer bioactivity of each chemical by assay endpoint combination, addressing sparsity of toxicology data. We propose a Bayesian hierarchical framework which borrows information across different chemicals and assay endpoints, facilitates out-of-sample prediction of activity for chemicals not yet assayed, quantifies uncertainty of predicted activity, and adjusts for multiplicity in hypothesis testing. Furthermore, this paper makes a novel attempt in toxicology to simultaneously model heteroscedastic errors and a nonparametric mean function, leading to a broader definition of activity whose need has been suggested by toxicologists. Real application identifies chemicals most likely active for neurodevelopmental disorders and obesity.

Urinary bisphenol A and S are associated with diminished ovarian reserve in women from an infertility clinic in Northern China

Bisphenol A (BPA) has been demonstrated to cause ovarian toxicity including disruption of steroidogenesis and inhibition of follicle growth. Still, human evidence is lacking on its analogs such as bisphenol F (BPF) and bisphenol S (BPS). In this study, we aimed to investigate the associations between exposure to BPA, BPF, and BPS with ovarian reserve in women of childbearing age. We recruited 111 women from an infertility clinic in Shenyang, North China between September 2020 and February 2021. Anti-müllerian hormone (AMH), follicle-stimulating hormone (FSH), and estradiol (E2) were measured as indicators of ovarian reserve. Urinary BPA, BPF, and BPS concentrations were quantified by ultra-high-performance liquid chromatography-triple quadruple mass spectrometry (UHPLC-MS/MS). Linear and logistic regression models were applied to assess the associations between urinary BPA, BPF, and BPS levels and indicators of ovarian reserve and DOR, respectively. Restricted cubic spline (RCS) models were further utilized to explore potential non-linear associations. Our results showed that urinary BPS concentrations were negatively associated with AMH (β = - 0.287, 95 %CI: - 0.505, - 0.070, P = 0.010) and this inverse relationship was further confirmed in the RCS model. In addition, higher levels of BPA and BPS exposure were associated with increased DOR risk (BPA: OR = 7.112, 95 %CI: 1.247, 40.588, P = 0.027; BPS: OR = 6.851, 95 %CI: 1.241, 37.818, P = 0.027). No significant associations of BPF exposure with ovarian reserve. Our findings implied that higher BPA and BPS exposure may be related to decreased ovarian reserve.

Increased levels of IL-17 and autoantibodies following Bisphenol A exposure were associated with activation of PI3K/AKT/mTOR pathway and abnormal autophagy in MRL/lpr mice

Bisphenol A (BPA) is a common environmental endocrine disruptor which mimic the effect of estrogen. The immunotoxicity of BPA has attracted widespread attention in recent years. However, the effects and mechanism of BPA on autoimmune disease were rarely reported. Systemic lupus erythematosus (SLE) is a typical autoimmune disease, and its etiology and mechanism are complex and unclear. Currently, inflammation and the production of autoantibodies are considered to be important pathological mechanisms of SLE, and estrogen contributes to the occurrence and development of SLE. Therefore, in order to explore whether BPA exposure can affect the development of SLE and its possible mechanism, we used MRL/lpr (lupus-prone mice) and C57/BL6 female mice exposed to 0.1 and 0.2 µg/mL BPA for 6 weeks. We discovered that BPA exposure increased the concentration of serum anti-dsDNA antibody and IL-17, and the level of RORγt protein (the transcription factor of Th17 cells). Moreover, there were higher expression of p-PI3K, p-AKT, p-mTOR, ULK, Rubicon, P62, Becline1 and LC3 protein in spleen tissue of BPA exposed MRL/lpr mice compared with the control. However, there were no significant changes in the expression of IL-17, RORγt or mTOR in C57 mice exposed to BPA at the same dose. Our study implied that BPA exposure induced the development of SLE, which might be related to the up-regulation of PI3K/AKT/mTOR signaling pathway and abnormal autophagy. Our study indicated that lupus mice were more susceptible to BPA, and provided a new insight into the mechanism by which BPA exacerbated SLE. Therefore, our study suggested that autoimmune patients and susceptible population should be considered when setting thresholds for environmental BPA exposure.

A New In Vivo Zebrafish Bioassay Evaluating Liver Steatosis Identifies DDE as a Steatogenic Endocrine Disruptor, Partly through SCD1 Regulation

Non-alcoholic fatty liver disease (NAFLD), which starts with liver steatosis, is a growing worldwide epidemic responsible for chronic liver diseases. Among its risk factors, exposure to environmental contaminants, such as endocrine disrupting compounds (EDC), has been recently emphasized. Given this important public health concern, regulation agencies need novel simple and fast biological tests to evaluate chemical risks. In this context, we developed a new in vivo bioassay called StAZ (Steatogenic Assay on Zebrafish) using an alternative model to animal experimentation, the zebrafish larva, to screen EDCs for their steatogenic properties. Taking advantage of the transparency of zebrafish larvae, we established a method based on fluorescent staining with Nile red to estimate liver lipid content. Following testing of known steatogenic molecules, 10 EDCs suspected to induce metabolic disorders were screened and DDE, the main metabolite of the insecticide DDT, was identified as a potent inducer of steatosis. To confirm this and optimize the assay, we used it in a transgenic zebrafish line expressing a blue fluorescent liver protein reporter. To obtain insight into DDE's effect, the expression of several genes related to steatosis was analyzed; an up-regulation of scd1 expression, probably relying on PXR activation, was found, partly responsible for both membrane remodeling and steatosis.

Metabolism-Disrupting Chemicals Affecting the Liver: Screening, Testing, and Molecular Pathway Identification

The liver is the central metabolic organ of the body. The plethora of anabolic and catabolic pathways in the liver is tightly regulated by physiological signaling but may become imbalanced as a consequence of malnutrition or exposure to certain chemicals, so-called metabolic endocrine disrupters, or metabolism-disrupting chemicals (MDCs). Among different metabolism-related diseases, obesity and non-alcoholic fatty liver disease (NAFLD) constitute a growing health problem, which has been associated with a western lifestyle combining excessive caloric intake and reduced physical activity. In the past years, awareness of chemical exposure as an underlying cause of metabolic endocrine effects has continuously increased. Within this review, we have collected and summarized evidence that certain environmental MDCs are capable of contributing to metabolic diseases such as liver steatosis and cholestasis by different molecular mechanisms, thereby contributing to the metabolic syndrome. Despite the high relevance of metabolism-related diseases, standardized mechanistic assays for the identification and characterization of MDCs are missing. Therefore, the current state of candidate test systems to identify MDCs is presented, and their possible implementation into a testing strategy for MDCs is discussed.

Untargeted Lipidomics Revealed the Protective Effects of Cyanidin-3-O-glucoside on Bisphenol A-Induced Liver Lipid Metabolism Disorder in Rats

Bisphenol A (BPA) is an estrogenic endocrine disruptor that induces metabolic disorders. Cyanidin-3-O-glucoside (C3G) has multiple functional activities and is the most abundant anthocyanin belonging to the flavonoid subgroup. This study aimed to investigate the protective effect of C3G on BPA-induced liver lipid metabolism disorder and explore its mechanism via lipidomics analysis. The results showed that C3G supplementation significantly ameliorated the serum levels of low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, total cholesterol, triacylglycerols (TG), and alanine and aspartate aminotransferase (ALT and AST). Furthermore, liver lipidomics indicated that C3G effectively facilitated the recovery of differential lipid metabolites, including TGs, phosphatidylethanolamines, phosphatidylcholines, lysophosphatidylcholines, phosphatidylinositol, cholesteryl esters, and phosphatidylserine, and reversed the levels of hepatic lipid synthesis-related genes. Our results suggest that C3G has an effective regulatory effect on BPA-induced disorders of lipid metabolism.

Ancestral BPA exposure caused defects in the liver of medaka for four generations

Environmental chemicals can induce liver defects in experimental animals due to their direct and acute exposure. It is not clear whether environmental chemical exposures result in the transgenerational passage of liver defects in subsequent generations living in an uncontaminated environment. Bisphenol A (BPA), a plasticizer chemical, has been ubiquitous in the environment in the recent decade. Every organism is exposed to this chemical at some point during its lifetime. Literature suggests that direct BPA exposure can result in several metabolic diseases, including non-alcoholic fatty liver disease (NAFLD). Despite the phasing out of BPA from several consumer goods, it is unclear whether ancestral BPA exposure causes liver health problems in the unexposed future generations. Here, we demonstrate an advanced stage of NAFLD in the grandchildren (F2 generation) of medaka fish (Oryzias latipes) due to embryonic BPA exposure in the grandparental generation (F0), which persists for five generations (F4) even in the absence of BPA. The severity of transgenerational NAFLD phenotype included steatosis together with perisinusoidal fibrosis and apoptosis of hepatocytes. Adult females developed more severe histopathological conditions in the liver than males. Genes encoding enzymes involved in lipolytic pathways were significantly decreased. The present results suggest that ancestral BPA exposure can result in transgenerational metabolic diseases that can persist for five generations and that the NAFLD trait is sexually dimorphic. Given that ancestral BPA exposure can lead to altered metabolic health outcomes in the subsequent unexposed generations, the development of the methods and strategies to mitigate the transgenerational onset of metabolic diseases seem imperative to protect future generations.

Serum glycolipids mediate the relationship of urinary bisphenols with NAFLD: analysis of a population-based, cross-sectional study

BACKGROUND

Bisphenol A (BPA) and its substitutes bisphenol S (BPS) and bisphenol F (BPF) are endocrine-disrupting chemicals widely used in consumer products, which have been proposed to induce various human diseases. In western countries, one of the most common liver diseases is non-alcoholic fatty liver disease (NAFLD). However, studies on the associations of the three bisphenols with NAFLD in human beings are scarce.

METHODS

We included 960 participants aged ≥ 20 years from the NHANES 2013-16 who had available data on levels of urinary BPA, BPS and BPF. The hepatic steatosis index (HSI) > 36 was used to predict NAFLD. Logistic regression analysis and mediation effect analysis were used to evaluate the associations among bisphenols, glycolipid-related markers and NAFLD.

RESULTS

A total of 540 individuals (56.3%) were diagnosed with NAFLD, who had higher concentrations of BPA and BPS but not BPF than those without NAFLD. An increasing trend in NAFLD risks and HSI levels was observed among BPA and BPS tertiles (p for trend < 0.05). After adjustment for confounders, elevated levels of BPA or BPS but not BPF were significantly associated with NAFLD. The odds ratio for NAFLD was 1.581 (95% confidence intervals [CI]: 1.1-2.274, p = 0.013) comparing the highest with the lowest tertile of BPA and 1.799 (95%CI: 1.2462.597, p = 0.002) for BPS. Mediation effect analysis indicated that serum high-density lipoprotein cholesterol and glucose had a mediating effect on the relationships between bisphenols and NAFLD.

CONCLUSIONS

The present study showed that high exposure levels of BPA and BPS increased NAFLD incidence, which might be mediated through regulating glycolipids metabolism. Further studies on the role of bisphenols in NAFLD are warranted.

Endocrine disrupting chemicals: A promoter of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the most prevalent liver disorder. With the improvement in human living standards, the prevalence of NAFLD has been increasing in recent years. Endocrine-disrupting chemicals (EDCs) are a class of exogenous chemicals that simulate the effects of hormones in the body. There has been growing evidence regarding the potential effects of EDCs on liver health, especially in NAFLD. This paper aims to summarize the major EDCs that contribute to the growing burden of NAFLD and to raise public awareness regarding the hazards posed by EDCs with the objective of reducing the incidence of NAFLD.

Combinatorial pathway disruption is a powerful approach to delineate metabolic impacts of endocrine disruptors

The prevalence of metabolic diseases, such as obesity, diabetes, metabolic syndrome and chronic liver diseases among others, has been rising for several years. Epidemiology and mechanistic (in vivo, in vitro and in silico) toxicology have recently provided compelling evidence implicating the chemical environment in the pathogenesis of these diseases. In this review, we will describe the biological processes that contribute to the development of metabolic diseases targeted by metabolic disruptors, and will propose an integrated pathophysiological vision of their effects on several organs. With regard to these pathomechanisms, we will discuss the needs, and the stakes of evolving the testing and assessment of endocrine disruptors to improve the prevention and management of metabolic diseases that have become a global epidemic since the end of last century.

Bisphenol A is a carcinogen that induces lipid accumulation, peroxisome proliferator‑activated receptor‑γ expression and liver disease

Bisphenol (BP) A is an exogenous endocrine disruptor that mimics hormones closely associated with health complications, e.g., obesity and cancers. The present study aimed to evaluate the effects of BPA on human liver cells and tissue. The peroxisome proliferator-activated receptor (PPAR)-γ expression profile across tumour samples and paired normal tissue was first analysed using GEPIA. Subsequently, BPA-treated liver THLE-2 cell viability was evaluated using an MTT assay. Clusterin, PPARα and PPARγ gene expression in BPA-treated THLE-2 cells was assessed using GEPIA before validating the gene expression using real-time PCR and analysing overall survival using TCGA data in GEPIA. Cytoplasmic lipid accumulation was examined in BPA-treated THLE-2 cells using Oil Red O staining, and liver tissue was examined using haematoxylin and eosin staining. Finally, cytochrome P450 (CYP) gene expression was assessed in BPA-treated THLE-2 cells using real-time PCR. PPARγ is likely the primary nuclear receptor protein involved in lipid accumulation in THLE-2 cells following BPA treatment and is associated with liver disease. THLE-2 cells exposed to BPA showed a decrease in viability and lipid accumulation after 48 h treatment. Higher PPARγ gene expression was significantly associated with survival of patients with liver cancer, with an average survival time of <80 months. Haematoxylin and eosin-stained sections showed notable disruption of the liver architecture in tissue exposed to BPA. Downregulated CYP1A1 and CYP1B1 gene expression implied that BPA-treated THLE-2 cells decreased capacity for carcinogen metabolism, while upregulated CYP2S1 gene expression exerted minimal cytotoxicity. The present study revealed that BPA served as a carcinogen, enhanced tumorigenesis susceptibility and may induce other types of liver disease.

Analysis of Blood Biochemistry and Pituitary-Gonadal Histology after Chronic Exposure to Bisphenol-A of Mice

Bisphenol-A is an emerging pollutant that is widespread in the environment, and to which live beings are continuously and inadvertently exposed. It is a substance with an endocrine-disrupting capacity, causing alterations in the reproductive, immunological, and neurological systems, among others, as well as metabolic alterations. Our study aimed to assess its clinical signs, and effects on the most relevant blood biochemical parameters, and to evaluate pituitary and gonadal histology after a chronic exposure of adult mice to different BPA doses (0.5, 2, 4, 50 and 100 µg/kg BW/day) through their drinking water. The biochemical results showed that a marked significant reduction (p < 0.05) was produced in the levels of serum glucose, hypoproteinaemia and hypoalbuminemia in the groups exposed to the highest doses, whereas in the group exposed to 50 µg/kg BW/day the glucose and total protein levels dropped, and the animals exposed to 100 µg/kg BW/day experienced a diminution in albumin levels. In the case of the group exposed to 50 µg/kg BW/day, however, hypertriglyceridemia and hypercholesterolemia were determined, and the blood parameters indicating kidney alterations such as urea and creatinine experienced a significant increase (p < 0.05) with respect to the controls. Regarding the pituitary and gonads, none of the animals exposed presented histological alterations at the doses tested, giving similar images to those of the control group. These results suggest that continuous exposure to low BPA doses could trigger an inhibition of hepatic gluconeogenesis, which would result in a hypoglycaemic state, together with an induction of the enzymes responsible for lipidic synthesis, a mechanism by which the increase in the lipid and serum cholesterol levels could be explained. Likewise, the decline in the protein and albumin levels would be indicative of a possible hepatic alteration, and the increase in urea and creatinine would point to a possible renal perturbation, derived from continuous exposure to this xenobiotic. Based on our results, it could be said that chronic exposure to low BPA doses would not produce any clinical signs or histological pituitary-gonadal effects, but it could cause modifications in some blood biochemical parameters, that could initially indicate a possible hepatic and renal effect.

Effects of Dietary Resveratrol, Bile Acids, Allicin, Betaine, and Inositol on Recovering the Lipid Metabolism Disorder in the Liver of Rare Minnow Gobiocypris rarus Caused by Bisphenol A

The fatty liver is one of the main problems in aquaculture. In addition to the nutritional factors, endocrine disrupter chemicals (EDCs) are one of the causes of fatty liver in fish. Bisphenol A (BPA) is a plasticizer widely used in the production of various plastic products and exhibits certain endocrine estrogen effects. Our previous study found that BPA could increase the accumulation of triglyceride (TG) in fish liver by disturbing the expression of lipid metabolism-related genes. How to recover the lipid metabolism disorder caused by BPA and other environmental estrogens remains to be explored. In the present study, Gobiocypris rarus was used as a research model, and 0.01% resveratrol, 0.05% bile acid, 0.01% allicin, 0.1% betaine, and 0.01% inositol were added to the feed of the G. rarus that exposed to 15 μg/L BPA. At the same time, a BPA exposure group without feed additives (BPA group) and a blank group with neither BPA exposure nor feed additives (Con group) were setted. The liver morphology, hepatosomatic index (HSI), hepatic lipid deposition, TG level, and expression of lipid metabolism-related genes were analyzed after 5 weeks of feeding. The HSI in bile acid and allicin groups was significantly lower than that in Con group. The TG in resveratrol, bile acid, allicin, and inositol groups returned to Con level. Principal component analysis of TG synthesis, decomposition, and transport related genes showed that dietary bile acid and inositol supplementation had the best effect on the recovery of BPA-induced lipid metabolism disorder, followed by allicin and resveratrol. In terms of lipid metabolism-related enzyme activity, bile acid and inositol were the most effective in recovering BPA-induced lipid metabolism disorders. The addition of these additives had a restorative effect on the antioxidant capacity of G. rarus livers, but bile acids and inositol were relatively the most effective. The results of the present study demonstrated that under the present dosage, bile acids and inositol had the best improvement effect on the fatty liver of G. rarus caused by BPA. The present study will provide important reference for solving the problem of fatty liver caused by environmental estrogen in aquaculture.

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.

Environmental Toxicants and NAFLD: A Neglected yet Significant Relationship

The liver is an organ of vital importance in the body; it is the center of metabolic activities and acts as the primary line of defense against toxic compounds. Exposure to environmental toxicants is an unavoidable fallout from rapid industrialization across the world and is even higher in developing countries. Technological development and industrialization have led to the release of toxicants such as pollutant toxic gases, chemical discharge, industrial effluents, pesticides and solvents, into the environment. In the last few years, a growing body of evidence has shed light on the potential impact of environmental toxicants on liver health, in particular, on non-alcoholic fatty liver disease (NAFLD) incidence and progression. NAFLD is a multifactorial disease linked to metabolic derangement including diabetes and other complications. Environmental toxicants including xenobiotics and pollutants may have a direct or indirect steatogenic/fibrogenic impact on the liver and should be considered as risk factors associated with NAFLD. This review discusses the contribution of environmental toxicants toward the increasing disease burden of NAFLD.

Lactational delivery of Triclosan promotes non-alcoholic fatty liver disease in newborn mice

Here we show that Triclosan (TCS), a high-volume antimicrobial additive that has been detected in human breastmilk, can be efficiently transferred by lactation to newborn mice, causing significant fatty liver (FL) during the suckling period. These findings are relevant since pediatric non-alcoholic fatty liver disease (NAFLD) is escalating in the United States, with a limited mechanistic understanding. Lactational delivery stimulated hepatosteatosis, triglyceride accumulation, endoplasmic reticulum (ER) stress, signs of inflammation, and liver fibrosis. De novo lipogenesis (DNL) induced by lactational TCS exposure is shown to be mediated in a PERK-eIF2α-ATF4-PPARα cascade. The administration of obeticholic acid (OCA), a potent FXR agonist, as well as activation of intestinal mucosal-regenerative gp130 signaling, led to reduced liver ATF4 expression, PPARα signaling, and DNL when neonates were exposed to TCS. It is yet to be investigated but mother to child transmission of TCS or similar toxicants may underlie the recent increases in pediatric NAFLD.

Exposure to Bisphenol A Caused Hepatoxicity and Intestinal Flora Disorder in Rats

Bisphenol A (BPA) is a globally utilized industrial chemical and is commonly used as a monomer of polycarbonate plastics and epoxy resins. Recent research reveals that BPA could cause potential adverse biological effects and liver dysfunction. However, the underlying mechanisms of BPA-induced hepatoxicity and gut dysbiosis remain unclear and deserve further study. In this study, male Sprague Dawley rats were exposed to different doses (0, 30, 90, and 270 mg/kg bw) of BPA by gavage for 30 days. The results showed that the high dose of BPA decreased superoxide dismutase (SOD), glutathione (GSH), and increased malondialdehyde (MDA) levels. Moreover, a high dose of BPA caused a significant increase in serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C), while high-density lipoprotein cholesterol (HDL-C) was significantly decreased in BPA-treated rats. The gene expression of PGC-1α and Nrf1 were decreased in the liver of high doses of BPA-administrated rats, as well as the protein levels of SIRT1, PGC-1α, Nrf2, and TFAM. However, the protein expression of IL-1β was significantly increased in BPA-treated rats. In addition, BPA weakened the mitochondrial function of hepatocytes and promoted cell apoptosis in the liver by up-regulating the protein levels of Bax, cleaved-Caspase3, and cleaved-PARP1 while down-regulating the Bcl-2 in the liver. More importantly, a high dose of BPA caused a dramatic change in microbiota structure, as characterized at the genus level by increasing the ratio of Firmicutes to Bacteroidetes (F/B), and the relative abundance of Proteobacteria in feces, while decreasing the relative abundance of Prevotella_9 and Ruminococcaceae_UCG-014, which is positively correlated with the content of short-chain fatty acids (SCFAs). In summary, our data indicated that BPA exposure caused hepatoxicity through apoptosis and the SIRT1/PGC-1α pathway. BPA-induced intestinal flora and SCFA changes may be associated with hepatic damage. The results of this study provide a new sight for the understanding of BPA-induced hepatoxicity.

Early-life exposure to bisphenol A induces dysregulation of lipid homeostasis by the upregulation of SCD1 in male mice

Exposure of Bisphenol A (BPA) is closely associated with an increased prevalence of obesity-related metabolic syndrome. However, the potential mechanism of BPA-induced adipogenesis remains to be fully elucidated. Herein, potential mechanisms of BPA-induced adipogenesis in 3T3-L1 preadipocytes were evaluated using RNA-Seq. Then, using an early-life BPA exposure model, we further evaluated the effects of BPA exposure on lipid and glucose homeostasis. The results showed that lipid content in 3T3-L1 adipocytes was significantly increased after BPA exposure (p < 0.01) and male C57BL/6 mice with the dose of 500 μg/kg/day BPA by once-a-day oral administration for 8 weeks displayed a NAFLD-like phenotype. RNA-Seq analysis of preadipocytes showed that BPA exposure affected multiple biological processes including glycosphingolipid biosynthesis, regulation of lipolysis in adipocytes, PPAR signaling pathway and fatty acid metabolism. The dysregulation in a series of genes of mice was associated to de novo lipogenesis and lipid transport, which was linked to obesity. Importantly, we also found a significant expression increase of stearoyl-CoA desaturase 1 (SCD1) and a significant decrease of apolipoprotein D (APOD) in both fat (p < 0.01) and livers (p < 0.01) of male mice. Besides, the dysregulation of pro-inflammatory genes (TNF-α,IL-6 and SAA3) showed that BPA exposure promoted progression of hepatic inflammation. In conclusion, this study elucidated a novel mechanism in which obesity associated with BPA exposure by targeting SCD1. Exposure to BPA should be carefully examined in the chronic liver metabolic diseases.

Metabolic Syndrome: Lessons from Rodent and Drosophila Models

Overweight and obesity are health conditions tightly related to a number of metabolic complications collectively called “metabolic syndrome” (MetS). Clinical diagnosis of MetS includes the presence of the increased waist circumference or so-called abdominal obesity, reduced high density lipoprotein level, elevated blood pressure, and increased blood glucose and triacylglyceride levels. Different approaches, including diet-induced and genetically induced animal models, have been developed to study MetS pathogenesis and underlying mechanisms. Studies of metabolic disturbances in the fruit fly Drosophila and mammalian models along with humans have demonstrated that fruit flies and small mammalian models like rats and mice have many similarities with humans in basic metabolic functions and share many molecular mechanisms which regulate these metabolic processes. In this paper, we describe diet-induced, chemically and genetically induced animal models of the MetS. The advantages and limitations of rodent and Drosophila models of MetS and obesity are also analyzed.

Effects of gestational exposure to bisphenol A on the hepatic transcriptome and lipidome of rat dams: Intergenerational comparison of effects in the offspring

Our previous studies demonstrated that prenatal bisphenol A (BPA) exposure affected the hepatic transcriptome and lipidome in rat offspring in a sex- and age-dependent manner. In this study, we investigated the effects of gestational exposure to BPA on the rat dams, after weaning period, and compared them with those of their offspring. Our results showed alterations in hepatic transcriptome related to insulin signaling, circadian rhythm, and infectious disease pathways in BPA-treated dams even 4 weeks after the exposure, whereas slight modifications on the lipid profile were found. Alterations in lipid and transcriptome profiles were more prominent in the prenatally BPA-exposed offspring at postnatal day (PND) 1 and 21 than those in the dams, suggesting that in utero exposure to BPA is more serious than exposure in the adulthood. Cryptochrome-1 (Cry1) and peroxisome proliferator-activated receptor delta (Ppard) were commonly altered in both dams and offspring. Nevertheless, the results of DIABLO (Data Integration Analysis for Biomarker discovery using Latent cOmponents), showed that multi-omics data successfully distinguished the exposed dams from the corresponding controls and their offspring with a high level of accuracy. The accuracy rates in BPA50 models (including control and 50 μg BPA/kg bw/day exposed groups) were smaller than those in BPA5000 models (control and 5000 μg BPA/kg bw/day exposed groups), suggesting dose-dependent severity in BPA effects. Palmitic acid and genes related to circadian rhythm, insulin responses, and lipid metabolism (e.g., 1-acylglycerol-3-phosphate O-acyltransferase 2 (Agpat2), B-cell CLL/lymphoma 10 (Bcl10), Cry1, Harvey rat sarcoma virus oncogene (Hras), and NLR family member X1 (Nlrx1)) were identified through DIABLO models as novel biomarkers of effects of BPA across two generations.

Bisphenol A Coupled with a High-Fat Diet Promotes Hepatosteatosis through Reactive-Oxygen-Species-Induced CD36 Overexpression

Bisphenol A (BPA) is an endocrine-disrupting chemical that affects lipid metabolism and contributes to non-alcoholic fatty liver disease (NAFLD). The mechanism of BPA exposure in hepatic lipid accumulation and its potential effect on NAFLD remain unclear. This study investigated the effect of BPA-exposure-induced hepatic lipid deposition on the pathology of NAFLD and its underlying mechanism in vitro and in vivo. BPA increased intracellular reactive oxygen species (ROS) levels, and promoted fatty acid uptake through upregulation of a free fatty acid uptake transporter, cluster of differentiation 36 (CD36), in HUH-7 cells. Additionally, C57BL/6 mice administered a high-fat/high-cholesterol/high-cholic acid diet (HFCCD) and BPA (50 mg/kg body weight) for 8 weeks developed a steatohepatitis-like phenotype, characterized by alpha-smooth muscle actin (α-SMA, an indicator of hepatic fibrosis) and cleaved caspase 3 (an indicator of apoptosis) in hepatic tissue; moreover, they had a higher oxidative stress index of 8-hydroxydeoxyguanosine (8-OHdG) in liver tissue compared to the control group. Treatment with ROS scavenger n-acetylcysteine (NAC) ameliorated BPA-mediated HFCCD-induced lipid accumulation and steatohepatitis in the livers of treated mice. Our study indicates that BPA acts synergistically to increase hepatic lipid uptake and promote NAFLD development by stimulating ROS-induced CD36 overexpression.