Dysregulated Autophagy in Hepatocytes Promotes Bisphenol A-Induced Hepatic Lipid Accumulation in Male Mice

Neuroreceptor Inhibition by Clozapine Triggers Mitohormesis and Metabolic Reprogramming in Human Blood Cells

The antipsychotic drug clozapine demonstrates superior efficacy in treatment-resistant schizophrenia, but its intracellular mode of action is not completely understood. Here, we analysed the effects of clozapine (2.5-20 µM) on metabolic fluxes, cell respiration, and intracellular ATP in human HL60 cells. Some results were confirmed in leukocytes of clozapine-treated patients. Neuroreceptor inhibition under clozapine reduced Akt activation with decreased glucose uptake, thereby inducing ER stress and the unfolded protein response (UPR). Metabolic profiling by liquid-chromatography/mass-spectrometry revealed downregulation of glycolysis and the pentose phosphate pathway, thereby saving glucose to keep the electron transport chain working. Mitochondrial respiration was dampened by upregulation of the F0F1-ATPase inhibitory factor 1 (IF1) leading to 30-40% lower oxygen consumption in HL60 cells. Blocking IF1 expression by cotreatment with epigallocatechin-3-gallate (EGCG) increased apoptosis of HL60 cells. Upregulation of the mitochondrial citrate carrier shifted excess citrate to the cytosol for use in lipogenesis and for storage as triacylglycerol in lipid droplets (LDs). Accordingly, clozapine-treated HL60 cells and leukocytes from clozapine-treated patients contain more LDs than untreated cells. Since mitochondrial disturbances are described in the pathophysiology of schizophrenia, clozapine-induced mitohormesis is an excellent way to escape energy deficits and improve cell survival.

Bis(2-ethylhexyl)-2,3,4,5-tetrabromophthalate Enhances foxo1-Mediated Lipophagy to Remodel Lipid Metabolism in Zebrafish Liver

An emerging environmental contaminant, bis(2-ethylhexyl)-2,3,4,5-tetrabromophthalate (TBPH), can bioaccumulate in the liver and affect hepatic lipid metabolism. However, the in-depth mechanism has yet to be comprehensively explored. In this study, we utilized transgenic zebrafish Tg (Apo14: GFP) to image the interference of TBPH on zebrafish liver development and lipid metabolism at the early development stage. Using integrated lipidomic and transcriptomic analyses to profile the lipid remodeling effect, we uncovered the potential effects of TBPH on lipophagy-related signaling pathways in zebrafish larvae. Decreased lipid contents accompanied by enhanced lipophagy were confirmed by the measurements of Oil Red O staining and transmission electron microscopy in liver tissues. Particularly, the regulatory role of the foxo1 factor was validated via its transcriptional inhibitor. Double immunofluorescence staining integrated with biochemical analysis indicated that the enhanced lipophagy and mitochondrial fatty acid oxidation induced by TBPH were reversed by the foxo1 inhibitor. To summarize, our study reveals, for the first time, the essential role of foxo1-mediated lipophagy in TBPH-induced lipid metabolic disorders and hepatoxicity, providing new insights for metabolic disease studies and ecological health risk assessment of TBPH.

The size-dependence and reversibility of polystyrene nanoplastics-induced lipid accumulation in mice: Possible roles of lysosomes

Nanoplastics (NPs) continue to accumulate in global aquatic and terrestrial systems, posing a potential threat to human health through the food chain and/or other pathways. Both in vivo and in vitro studies have confirmed that the liver is one of the main organs targeted for the accumulation of NPs in living organisms. However, whether exposure to NPs induces size-dependent disorders of liver lipid metabolism remains controversial, and the reversibility of NPs-induced hepatotoxicity is largely unknown. In this study, the effects of long-term exposure to environmentally relevant doses of polystyrene nanoplastics (PS-NPs) on lipid accumulation were investigated in terms of autophagy and lysosomal mechanisms. The findings indicated that hepatic lipid accumulation was more pronounced in mice exposed to 100 nm PS-NPs compared to 500 nm PS-NPs. This effect was effectively alleviated after 50 days of self-recovery for 100 nm and 500 nm PS-NPs exposure. Mechanistically, although PS-NPs exposure activated autophagosome formation through ERK (mitogen-activated protein kinase 1)/mTOR (mechanistic target of rapamycin kinase) signaling pathway, the inhibition of Rab7 (RAB7, member RAS oncogene family), CTSB (cathepsin B), and CTSD (cathepsin D) expression impaired lysosomal function, thereby blocking autophagic flux and contributing to hepatic lipid accumulation. After termination of PS-NPs exposure, lysosomal exocytosis was responsible for the clearance of PS-NPs accumulated in lysosomes. Furthermore, impaired lysosomal function and autophagic flux inhibition were effectively alleviated. This might be the main reason for the alleviation of PS-NPs-induced lipid accumulation after recovery. Collectively, we demonstrate for the first time that lysosomes play a dual role in the persistence and reversibility of hepatotoxicity induced by environmental relevant doses of NPs, which provide novel evidence for the prevention and intervention of liver injury associated with nanoplastics exposure.

Rapamycin protects Sertoli cells against BPA-induced autophagy disorders

Bisphenol A (BPA) is a well-known environmental contaminant that can negatively impact reproductive function. Disruption of autophagy is implicated in BPA-induced cell injury, the specific molecular mechanisms through which BPA affects autophagy in Sertoli cells are still unknown. In the present study, TM4 cells were exposed to various doses of BPA (10, 100, and 200 μM), and the results indicated that BPA exposure led to the accumulation of autophagosomes, this change was accompanied by increased expression of p-mTOR and decreased expression of Atg12, a protein involved in regulating autophagy initiation. Additionally, BPA exposure upregulated the expression levels of p62, a protein involved in autophagic degradation. The inhibition of autophagy initiation and autophagic degradation contributes to the accumulation of autophagosomes. Further studies showed that BPA exposure didn't affect the expression of the lysosome protein LAMP1; however, decreased cytoplasmic retention of acridine orange in TM4 cells may explain the disruption of autophagy. The role of rapamycin and chloroquine (CQ), an autophagy inhibitor that impairs lysosomal degradation also confirmed the effect of BPA on autophagy regulation. Specifically, rapamycin can protect Sertoli cells against BPA-induced cell injury by promoting autophagy. These findings contribute to our understanding of the mechanisms underlying reproductive toxicity caused by BPA.

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.

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.

Carnosic acid and rosemary extract reversed the lipid accumulation induced by bisphenol A in the 3T3-L1 preadipocytes and C57BL/6J mice via SIRT1/FoxO1 pathway

Bisphenol A (BPA) is an endocrine-disrupting chemical, widely used to produce polycarbonate plastic. Carnosic acid (CA) is a rosemary diterpene with an anti-obesity effect. In this study, we investigated the anti-adipogenic effect of CA in BPA-treated 3T3-L1 preadipocytes and C57BL/6 J mice. In vitro experiments showed that CA inhibited lipid accumulation by BPA in 3T3-L1 preadipocytes. CA displayed anti-adipogenic effects through the downregulation of differentiation and adipogenesis-related proteins, along with the upregulation of lipolytic protein and SIRT1/FoxO1 pathway. In vivo experiments, mice treated with BPA exhibited an increase in body weight gain and epididymal adipose tissue mass when compared to the control group. CA treatment improved the epididymal adipose tissue mass induced by BPA. CA and rosemary extract (RE) treatment ameliorated dyslipidemia in BPA-treated mice. We further showed that CA and RE exerted anti-adipogenesis effects in liver tissues of BPA-treated mice via increasing SIRT1, FoxO1, and ATGL proteins and decreasing FAS and aP2 proteins. Moreover, SIRT1 inhibitor sirtinol blocked CA to increase SIRT1, FoxO1, FAS, and aP2 proteins, decrease Ac-FoxO1 protein, and reduce lipid accumulation in BPA-treated cells. These findings indicated that CA and RE could reverse BPA-induced lipid accumulation by regulating adipocyte differentiation, adipogenesis, and lipolysis through SIRT1/FoxO1 pathway.

Bisphenol A has a sex-dependent disruptive effect on hepatic lipid metabolism in zebrafish

Bisphenol A (BPA) is an endocrine disruptor that has adverse effects on lipid metabolism. However, most of the current studies on the effects of BPA on lipid metabolism in fish have focused on middle- and short-term exposure tests. The aim of this study was to investigate the effects of long-term BPA exposure on liver lipid metabolism in zebrafish. Post-fertilization embryos were exposed to environmentally relevant concentrations of BPA for 120 days, and the changes in triglyceride (TG), total cholesterol (TC) levels, and gene expression related to liver lipid metabolism were investigated in both male and female fish. The results showed that long-term exposure to BPA led to lipid deposition in liver, and there was a sex difference. In the liver of female fish, there was higher lipid transport and synthesis at low concentration of BPA, while overall metabolic levels were increased at high concentration of BPA. In contrast, BPA showed a dose-dependent effect on the lipid deposition in male fish. The expression of mRNA of TG transport-related and lipid synthesis-related genes was significantly up-regulated and the expression of genes related to lipid catabolism, was significantly down-regulated with increasing BPA dose. Taken together, our results indicate that long-term exposure to BPA can increase lipid deposition in a gender-specific manner. This may be due to the different responses of lipid metabolism related genes to BPA in male and female zebrafish. These results will provide a new reference for a deeper understanding of the ecotoxicological effects of BPA on aquatic animals.

Bisphenol A-induced autophagy ameliorates human B cell death through Nrf2-mediated regulation of Atg7 and Beclin1 expression by Syk activation

The widely used plasticizer bisphenol A (BPA) is known as an endocrine-disrupting chemical (EDC). Many studies have shown that BPA contributes to diseases involving immune system alterations, but the underlying mechanisms have yet to be elucidated. We previously reported that BPA at concentration of 100 μM caused human B cell death in accordance with an increase in nuclear factor (erythroid-derived 2)-like 2(Nrf2) expression. Autophagy is a cellular process that degraded and recycles cytoplasmic constituents. Here, we investigated whether BPA induces autophagy through Nrf2, which is associated with regulation of B cell death using human WiL2-NS lymphoblast B cells. Then, cell viability was assessed by various assays using trypan blue, MTT or Celltiter glo luminescent substrate and DAPI. When WiL2-NS cells were treated with BPA, cell viability was decreased and LC3 autophagy cargo protein/puncta was increased. BPA-induced autophagy was confirmed by the modification of LC3 puncta formation or autophagy flux turnover with the treatment of hydroxychloroquine(HCQ), NH₄Cl and PI3K inhibitors including 3-methyladenine(3-MA), LY294002 and wortmannin. BPA treatment increased the expression of autophagy-related gene(Atg)7 and Beclin1 as well as Nrf2 induced by the production of reactive oxygen species (ROS). The inhibition of autophagy with siAtg7 or siBeclin1 and Nrf2 depletion aggravated BPA-induced cell death. BPA enhanced the bound of Nrf2 to the specific region on Beclin1 and Atg7 promoter. Spleen tyrosine kinase(Syk) activity was enhanced in response to BPA treatment. Bay61-3606, Syk inhibitor, decreased LC3 and the expression of Atg7 and Beclin1, leading to the increase of BPA-induced B cell death. The results suggest that BPA-induced autophagy ameliorates human B cell death through Nrf2-mediated regulation of Atg7 and Beclin1 expression.

Re-evaluation of the risks to public health related to the presence of bisphenol A (BPA) in foodstuffs

In 2015, EFSA established a temporary tolerable daily intake (t-TDI) for BPA of 4 μg/kg body weight (bw) per day. In 2016, the European Commission mandated EFSA to re-evaluate the risks to public health from the presence of BPA in foodstuffs and to establish a tolerable daily intake (TDI). For this re-evaluation, a pre-established protocol was used that had undergone public consultation. The CEP Panel concluded that it is Unlikely to Very Unlikely that BPA presents a genotoxic hazard through a direct mechanism. Taking into consideration the evidence from animal data and support from human observational studies, the immune system was identified as most sensitive to BPA exposure. An effect on Th17 cells in mice was identified as the critical effect; these cells are pivotal in cellular immune mechanisms and involved in the development of inflammatory conditions, including autoimmunity and lung inflammation. A reference point (RP) of 8.2 ng/kg bw per day, expressed as human equivalent dose, was identified for the critical effect. Uncertainty analysis assessed a probability of 57-73% that the lowest estimated Benchmark Dose (BMD) for other health effects was below the RP based on Th17 cells. In view of this, the CEP Panel judged that an additional uncertainty factor (UF) of 2 was needed for establishing the TDI. Applying an overall UF of 50 to the RP, a TDI of 0.2 ng BPA/kg bw per day was established. Comparison of this TDI with the dietary exposure estimates from the 2015 EFSA opinion showed that both the mean and the 95th percentile dietary exposures in all age groups exceeded the TDI by two to three orders of magnitude. Even considering the uncertainty in the exposure assessment, the exceedance being so large, the CEP Panel concluded that there is a health concern from dietary BPA exposure.

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.

The Effect of bisphenol A and Photobiomodulation Therapy on Autophagy-Related Genes Induction in Adipose Tissue-Derived Stem Cells

Introduction: As adipose tissue-derived stem cells (ADSCs) can divide rapidly and be prepared non-invasively, they have extensively been used in regenerative medicine. On the other hand, a new method of therapy, known as photobiomodulation (PHT), has been used to treat many diseases, such as inflammatory conditions, wound healing and pain. Besides, exposure to chemical substances such as bisphenol A (BPA), at low levels, can lead to autophagy. This study investigated the effects of BPA and PHT on the expression of autophagy-related genes, including LC3, NRF2, P62, in rat ADSCs as a model. Methods: ADSCs isolation and purification were confirmed by immunocytochemistry (ICC). The cells were then treated with different concentrations of BPA and also subjected to PHT. Reverse transcription polymerase chain reaction (RT-PCR) was used for the evaluation of LC3, NRF2 and P62 gene expressions. Oil red O staining was used for adipogenic vacuole formation. Result: ICC showed that the isolated cells were CD 49-positive but CD 31 and CD 34-negative. The viability test indicated that the number of live cells after 24 hours in the BPA groups at concentrations of 0, 1, 50, 100 and 200 μM was 100%, 93%, 81%, 72%, and 43% respectively. The difference in cell viability between groups 50, 100 and 200 μM was significant as compared with the control groups (P<0.05). Moreover, in the group with 1 μM concentration of BPA, the expressions of LC3, NRF2 and P62 genes were upregulated. However, in the treatment group at the concentration of 200 μM of BPA, the LC3 gene was expressed, but NRF2 and P62 genes were downregulated. Conclusion: BPA and PHT induce autophagy and adiposeness in ADSCs in a dose-dependent manner.

Obesity III: Obesogen assays: Limitations, strengths, and new directions

There is increasing evidence of a role for environmental contaminants in disrupting metabolic health in both humans and animals. Despite a growing need for well-understood models for evaluating adipogenic and potential obesogenic contaminants, there has been a reliance on decades-old in vitro models that have not been appropriately managed by cell line providers. There has been a quick rise in available in vitro models in the last ten years, including commercial availability of human mesenchymal stem cell and preadipocyte models; these models require more comprehensive validation but demonstrate real promise in improved translation to human metabolic health. There is also progress in developing three-dimensional and co-culture techniques that allow for the interrogation of a more physiologically relevant state. While diverse rodent models exist for evaluating putative obesogenic and/or adipogenic chemicals in a physiologically relevant context, increasing capabilities have been identified for alternative model organisms such as Drosophila, C. elegans, zebrafish, and medaka in metabolic health testing. These models have several appreciable advantages, including most notably their size, rapid development, large brood sizes, and ease of high-resolution lipid accumulation imaging throughout the organisms. They are anticipated to expand the capabilities of metabolic health research, particularly when coupled with emerging obesogen evaluation techniques as described herein.

Role of Bisphenol A in Autophagy Modulation: Understanding the Molecular Concepts and Therapeutic Options

Abstract:

Bisphenol A (4,4′-isopropylidenediphenol) is an organic compound, commonly used in the plastic bottles, packaging containers, beverages and resin industry. The adverse effects of bisphenol A were studied in various systems of the body. Autophagy is a lysosomal degradation process meant for the regeneration of new cells. The role of bisphenol A on autophagy modulation in the pathogenesis of diseases is still debatable. Few research studies showed that bisphenol A-induced adverse effects were associated with autophagy dysregulation, while few showed the activation of autophagy by bisphenol A. Such contrasting views make the subject more interesting and debatable. In the present review, we discuss the different steps of autophagy, genes involved, and the effect of bisphenol A in autophagy modulation on different systems of the body. We also discuss the methods for monitoring autophagy and the roles of drugs such as chloroquine, verteporfin, and rapamycin in autophagy. Proper understanding of the role of bisphenol A in the modulation of autophagy may be important for future treatment and drug discovery.

Mechanisms for Improving Hepatic Glucolipid Metabolism by Cinnamic Acid and Cinnamic Aldehyde: An Insight Provided by Multi-Omics

Cinnamic acid (AC) and cinnamic aldehyde (AL) are two chemicals enriched in cinnamon and have been previously proved to improve glucolipid metabolism, thus ameliorating metabolic disorders. In this study, we employed transcriptomes and proteomes on AC and AL treated db/db mice in order to explore the underlying mechanisms for their effects. Db/db mice were divided into three groups: the control group, AC group and AL group. Gender- and age-matched wt/wt mice were used as a normal group. After 4 weeks of treatments, mice were sacrificed, and liver tissues were used for further analyses. Functional enrichment of differentially expressed genes (DEGs) and differentially expressed proteins (DEPs) were performed using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. DEPs were further verified by parallel reaction monitoring (PRM). The results suggested that AC and AL share similar mechanisms, and they may improve glucolipid metabolism by improving mitochondrial functions, decreasing serotonin contents and upregulating autophagy mediated lipid clearance. This study provides an insight into the molecular mechanisms of AC and AL on hepatic transcriptomes and proteomes in disrupted metabolic situations and lays a foundation for future experiments.

Mechanism by which Eucommia ulmoides leaves Regulate Nonalcoholic fatty liver disease based on system pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Eucommia ulmoides (E. ulmoides) leaves are included in the Chinese Pharmacopoeia, and are traditionally used to treat hypertension, obesity, diabetes, and other diseases. Numerous pharmacological studies have shown that E. ulmoides has a good effect on lowering blood lipids and can improve obesity and nonalcoholic fatty liver.

AIM

To study the mechanism of E. ulmoides leaves in regulating nonalcoholic fatty liver disease by combining prediction and validation.

METHODS

Using network pharmacology, and molecular docking to predict E. ulmoides in regulating the action mechanism and potential active ingredients of nonalcoholic fatty liver, large hole adsorption resin enrichment active sites, in vitro experiments were performed to verify its fat-lowering effect and mechanism.

RESULTS

The major components of E. ulmoides leaves exhibited good combination with lipid metabolism-regulating core proteins, particularly flavonoids. EUL 50 significantly reduced lipid accumulation, and increased PPARγ. Compared with the control group, the autophagy level increased after the administration of EUL 50. PPARγ decreased significantly after the addition of chloroquine (CQ, autophagy inhibitor).

CONCLUSION

The active ingredients in E. ulmoides leaves regulating nonalcoholic fatty liver disease are mainly flavonoids and phenolics. EUL 50 may play a role in lowering lipids by regulating PPARγ expression through inducing autophagy.

1,3-dichloro-2-propanol induced hepatic lipid accumulation by inhibiting autophagy via AKT/mTOR/FOXO1 pathway in mice

Our study investigated the effects of food contaminant 1,3-dichloro-2-propanol (1,3-DCP) on hepatic lipid metabolism and its mechanism. We found that triglyceride (TG), total cholesterol (TC) and the number of lipid droplets (LDs) were increased in the liver of C57BL/6 mice given intragastric administration of 1,3-DCP for 30 days. Meanwhile, 1,3-DCP inhibited autophagosomes and lysosomes formation, reflected by decreased LC3-II, LAMP1, LAMP2, CTSD, CTSB expression, increased p62 expression and decreased LC3 fluorescence. Subsequently, we detected the changes of hepatic lipid accumulation caused by 1,3-DCP using an autophagy inducer or inhibitor. In vivo, Hepatic lipid accumulation caused by 1,3-DCP was mitigated by the autophagy inducer Rapa. On the contrary, the autophagy inhibitor (chloroquine or 3-methyladenine) further exacerbated hepatic lipid accumulation caused by 1,3-DCP. 1,3-DCP reduced the number of autophagosomes encapsulated LDs, assessed by colocalization of LD and LC3. These data demonstrated that 1,3-DCP induced lipid accumulation by inhibiting autophagy. We further investigated the mechanism of 1,3-DCP-inhibited autophagy and found 1,3-DCP increased the ratios of p-AKT/AKT, p-mTOR/mTOR, p-FOXO1/FOXO1, decreased FOXO1 nuclear localization in vivo. These proteins may be involved in the regulation of 1,3-DCP-mediated autophagy. We detected the changes in autophagy marker protein LC3-II and lipid accumulation using an AKT inhibitor ARQ-092 or a mTOR inhibitor rapamycin in HepG2 cells. Compared with 1,3-DCP group, lipid accumulation was decreased, LC3-II and FOXO1 nuclear localization were increased, p-FOXO1 levels were decreased in HepG2 cells pretreated with ARQ-092 or rapamycin. Taken together, these data revealed that the effects of 1,3-DCP on lipid accumulation by inhibiting autophagy were dependent on AKT/mTOR/FOXO1 signaling pathway. Our study not only supplied the mechanism of 1,3-DCP toxicity, but also provided experimental basis for effective intervention measures of 1,3-DCP toxicity.

Alteration of lipid metabolism, autophagy, apoptosis and immune response in the liver of common carp (Cyprinus carpio) after long-term exposure to bisphenol A

Bisphenol A (BPA), as a phenolic compound, is harmful to human health, and its residue in the aquatic environment also threatens the health of aquatic animals. In this research, the toxicity effects of BPA on liver tissues were evaluated in common carp (Cyprinus carpio) after long-term exposure. Fish were exposed to five concentrations of BPA (0, 0.01, 0.1, 0.5 and 2 mg/L) for 30 days. The blood and liver tissues were gathered to analyze biochemical indices and genes transcription levels. The data related to lipid metabolism showed that BPA exposure increased serum total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) levels, upregulated the expressions of fatp1, pparγ, fas, atgl, hsl, pparα, cpt1b, acox-1, and downregulated the expression of dgat1 in liver. Antioxidative parameters displayed a reduced antioxidant ability and increased lipid peroxidation after BPA exposure. Meanwhile, the upregulations of nrf2, ho-1, cyp1a and cyp1b genes revealed an adaptive response mechanism against oxidative stress-induced adverse effects. After 30 days of exposure, BPA induced apoptosis and endoplasmic reticulum stress (ERS) via upregulating the expression levels of apoptosis and ERS-related genes and increasing Ca²⁺ concentration in liver. Moreover, the downregulation of mtor and the upregulation of atg3, atg7, tfeb, uvrag and mcoln1 indicated that BPA could influence the normal process of autophagy. Furthermore, BPA exposure activated toll like receptors (TLRs) pathway to mediate the inflammatory response. Our results demonstrated that BPA exposure disturbed lipid metabolism, and induced oxidative stress, ERS, apoptosis, autophagy and inflammatory response in the liver of common carp. These findings contributed to the understanding of hepatotoxicity mechanism induced by BPA in fish.

1,3-dichloro-2-propanol induced lipid accumulation by blocking autophagy flux in HepG2 cells

Great attention has been paid to 1,3-dichloro-2-propanol (1,3-DCP) due to its presence in food and concerns about toxic potential as carcinogens. In our previous study, we found that long-term low-dose 1,3-DCP exposure induced lipid accumulation in mouse liver. Recent studies have demonstrated that autophagy plays an important role in regulating lipid metabolism. So, we speculated that 1,3-DCP induced lipid accumulation by regulating autophagy in hepatocytes. In this study, we first studied the effect of 100 μM 1,3-DCP on autophagy flux in HepG2 cells. The data showed that 1,3-DCP (100 μM) impaired autophagy flux mainly through the attenuation of autophagosomes via AKT/mTOR signaling pathway and inhibition of lysosomes biosynthesis. Furthermore, we demonstrated that treatment with 100 μM 1,3-DCP for 24 h affected lipid metabolism through the colocalization of LC3 and Bodipy. We used an autophagy activator or an autophagy inhibitor to test the effect of 1,3-DCP on lipid accumulation through detecting lipid droplets staining, triglyceride (TG) and total cholesterol (TC). The data showed that 1,3-DCP-induced lipid accumulation was alleviated in the presence of Rapamycin (an autophagy activator). On the contrary, 1,3-DCP-induced lipid accumulation was significantly exacerbated in the presence of an autophagy inhibitor (3-methyladenine or chloroquine). These results suggested that 1,3-DCP might induce lipid accumulation by the impairment of autophagy flux in HepG2 cells.

In vitro evaluation of the hepatic lipid accumulation of bisphenol analogs: A high-content screening assay

Bisphenol A (BPA) has a variety of adverse effects on human health; therefore, BPA analogs are increasingly used as replacements. Notably, recent studies have revealed that BPA exposure induced hepatic lipid accumulation, but few studies are available regarding the similar effects of other bisphenol analogues (BPs). Thus, in the present study, a high-content screening (HCS) assay was performed to simultaneously evaluate the hepatic lipid accumulation of 13 BPs in vitro. The BPs induced lipid deposition in HepG2 cells ranking as below: 4,4'-thiodiphenol (TDP) < bisphenol S (BPS) < 4,4'-dihydroxybenzophenone (DHBP) < tetrabromobisphenol A (TBBPA) < tetrachlorobisphenol A (TCBPA) < bisphenol E (BPE) < bisphenol F (BPF) < bisphenol B (BPB) < bisphenol AF (BPAF) < bisphenol A (BPA) < bisphenol C (BPC) < tetramethylbisphenol A (TMBPA) < bisphenol AP (BPAP). Meanwhile, Oil Red O staining and triacylglycerol detection further validated the lipid accumulation elicited by the latter 8 BPs, which exhibited the more significant effects on lipid deposition. Mechanistically, significantly increased expressions of genes involved in fatty acid synthesis and nuclear receptors and decreased levels of genes associated with fatty acid β-oxidation were observed under BPs treatment. Therefore, the present work is the first to systematically provide direct evidence for BPs-induced hepatic lipid accumulation in vitro via HCS, which can be helpful for safety assessments of BPs.

Bisphenol A exposure in relation to altered lipid profile and dyslipidemia among Chinese adults: A repeated measures study

Animal experiments suggest that bisphenol A (BPA) could potentially induce lipid abnormalities. However, whether BPA exposure associates with altered lipid metabolism in humans has not been fully elucidated. We thus comprehensively investigated the relationship of BPA exposure and its change with lipid profile and development of incident dyslipidemia among Chinese adults. We initially included 1872 participants aged 40 years or older who were free of dyslipidemia at baseline in 2009, and followed them for 4 years. Urinary BPA and serum lipids including total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG) were determined at baseline and follow-up. Linear mixed models were used for repeated measures analyses and linear and logistic regression models were used to evaluate longitudinal changes in lipid profile and risk of incident dyslipidemia. In repeated measures analyses, per doubling of urinary BPA concentrations was associated with higher serum levels of LDL-C, non-HDL-C, TC to HDL-C ratio, and lower levels of HDL-C and TG. In longitudinal change analyses, participants with high BPA at both baseline and follow-up showed an additional 2.94% increase in LDL-C (95% CI: 0.02%, 5.95%) and 6.12% increase in TG (95% CI: 0.74%, 11.8%), as compared with those who maintained low BPA. Furthermore, participants with sustained high BPA at two time points had increased odds of developing hyper-LDL cholesterolemia (odds ratio = 1.93, 95% CI: 1.02, 3.66). Our results suggested that high BPA exposure, especially maintained a long time period apart, was associated with deterioration of lipid profiles among middle-aged and elderly adults, supporting a detrimental role of BPA in lipid metabolism.

Autophagy role in environmental pollutants exposure

During the last decades, the potential harmfulness derived from the exposure to environmental pollutants has been largely demonstrated, with associated damages ranging from geno- and cyto-toxicity to tissue malfunction and alterations in organism physiology. Autophagy is an evolutionarily-conserved cellular mechanism essential for cellular homeostasis, which contributes to protect cells from a wide variety of intracellular and extracellular stressors. Due to its pivotal importance, its correct functioning is directly linked to cell, tissue and organismal fitness. Environmental pollutants, particularly industrial compounds, are able to impact autophagic flux, either by increasing it as a protective response, by blocking it, or by switching its protective role toward a pro-cell death mechanism. Thus, the understanding of the effects of chemicals exposure on autophagy has become highly relevant, offering new potential approaches for risk assessment, protection and preventive measures to counteract the detrimental effects of environmental pollutants on human health.

Prenatal Bisphenol A Exposure in Mice Induces Multitissue Multiomics Disruptions Linking to Cardiometabolic Disorders

The health impacts of endocrine-disrupting chemicals (EDCs) remain debated, and their tissue and molecular targets are poorly understood. In this study, we leveraged systems biology approaches to assess the target tissues, molecular pathways, and gene regulatory networks associated with prenatal exposure to the model EDC bisphenol A (BPA). Prenatal BPA exposure at 5 mg/kg/d, a dose below most reported no-observed-adverse-effect levels, led to tens to thousands of transcriptomic and methylomic alterations in the adipose, hypothalamus, and liver tissues in male offspring in mice, with cross-tissue perturbations in lipid metabolism as well as tissue-specific alterations in histone subunits, glucose metabolism, and extracellular matrix. Network modeling prioritized main molecular targets of BPA, including Pparg, Hnf4a, Esr1, Srebf1, and Fasn as well as numerous less studied targets such as Cyp51 and long noncoding RNAs across tissues, Fa2h in hypothalamus, and Nfya in adipose tissue. Lastly, integrative analyses identified the association of BPA molecular signatures with cardiometabolic phenotypes in mouse and human. Our multitissue, multiomics investigation provides strong evidence that BPA perturbs diverse molecular networks in central and peripheral tissues and offers insights into the molecular targets that link BPA to human cardiometabolic disorders.

Non-alcoholic Fatty Liver Disease Induced by Perinatal Exposure to Bisphenol a Is Associated With Activated mTOR and TLR4/NF-κB Signaling Pathways in Offspring Rats

Accumulating evidence suggests a role of bisphenol A (BPA) in non-alcoholic fatty liver disease (NAFLD), and its mechanism may be related to the up-regulation of lipogenic genes, but the mechanism of BPA induced lipogenic gene expression remains unknown. The aim of this study was to investigate the effects of perinatal exposure to BPA on NAFLD and its mechanisms. Pregnant Sprague-Dawley rats had access to drinking water containing 1 or 10 μg/ml BPA from gestational day 6 to post-natal day 21. For 5 weeks after weaning, offspring drank normal water without BPA. Body weight, lipid profile and the expression of genes or proteins involved in mTOR mediated lipid metabolism and autophagy, as well as inflammatory response were investigated in the 8-wk-old offspring of different genders. The results showed that body weight was increased only in females, however, males, and females from dams treated with BPA had significantly excess visceral adipose tissue, which was consistent with adipocyte hypertrophy. Elevated TG levels and up-regulation of lipogenic genes or proteins in liver, such as sterol regulatory element binding protein 1 (SREBP1), acetyl-CoA carboxylase 1 (ACC1), and fatty acid synthase (FAS) were consistent with increased liver lipid droplets in offspring exposed to BPA. Compared with controls, the protein levels of InsR, p-IRS-1, IRS-1, TSC1, and TSC2 were decreased, p-PI3K, p-Akt (S473), p-Akt (T308), p-mTOR, and mTOR were increased, and the impaired autophagic degradation was evidenced by increased protein levels of p62, although the levels of p-ULK1, Beclin1, and LC3B proteins were increased in liver of BPA-exposed offspring. The levels of TLR4 and NF-κB proteins were also significantly increased, and ERα protein was significantly decreased in BPA-exposed offspring. Our findings indicate that perinatal exposure to BPA causes the development of NAFLD in both female and male offspring, which is associated with up-regulation of lipogenic genes, dysregulated autophagy and activated inflammatory response involving the PI3K/Akt/mTOR and TLR4/NF-κB pathways.

Diphenyl diselenide regulates Nrf2/Keap-1 signaling pathway and counteracts hepatic oxidative stress induced by bisphenol A in male mice

Bisphenol A (BPA) is a chemical toxicant that has deleterious effects on human. BPA causes oxidative stress in tissues, including the liver. Diphenyl diselenide (PhSe)₂ improves the antioxidant response via activation of the nuclear factor (erythroid-derived 2)-like 2 (Nrf2)/Kelch-like ECH-associated protein (keap 1) pathway in macrophage cells. In the present study, we investigated whether (PhSe)₂ counteracts hepatic oxidative stress induced by BPA in male and female Swiss mice. Three-week-old mice received by the intragastric (i.g.) route BPA (5 mg/kg) from 21st to 60th postnatal day (PND). At PND 61, the mice were treated with (PhSe)₂ (1 mg/kg, i.g.) for seven days. Parameters of hepatic damage and oxidative stress were determined in male and female mice. The results show that BPA increased the activity of aspartate aminotransferase in female mice, and in male mice the activity of alanine aminotranseferase was increased. Male and female mice had an increase in fat mass accumulation. Male mice showed an increase in hepatic oxidative damage of proteins and a decrease in non-enzymatic (ascorbic acid and non-protein thiol) and enzymatic (superoxide dismutase) defenses, which are consistent with oxidative stress status. Male mice were more susceptible than female mice to hepatic oxidative stress induced by BPA. BPA decreased Nrf2/Keap1 protein content in male mice. (PhSe)₂ reduced hepatic oxidative stress induced by BPA in male mice. Our results demonstrate that male mice were more susceptible to hepatic oxidative stress induced by BPA than female mice. (PhSe)₂ regulated Nrf2/Keap-1 signaling pathway and countered hepatic oxidative stress induced by BPA in male mice.

Developmental Effects and Estrogenicity of Bisphenol A Alternatives in a Zebrafish Embryo Model

In order to understand the negative effects of bisphenol A (BPA) alternatives comprehensively, zebrafish embryos were used to assess the lethality, developmental effects, and estrogenic activity of bisphenol analogues. The in silico estrogenic activities of bisphenol analogues were assayed by binding simulation. According to our results, the lethality of bisphenol analogues decreased in order of bisphenol AF (BPAF) > BPA > bisphenol F (BPF) > bisphenol S (BPS). BPAF and BPF induced significant effects on zebrafish embryos, including decreased heart rate, hatching inhibition, and teratogenic effects. The binding potentials of bisphenol analogues toward zebrafish ERs (zfERS) decreased in the following order: BPAF > BPA > BPF > BPS. Among the three subtypes of zfERs, zfERβ2 showed the highest binding activity toward the bisphenols, followed by zfERα and zfERβ1. In vivo estrogenic activity tests showed that BPAF, BPA, and BPF significantly enhanced the protein levels of ERα along with the mRNA levels of esr1, esr2a, esr2b, and vtg1 in zebrafish embryos. Esr2b showed the strongest response to BPAF and BPA exposure among the three esrs. In contrast, BPS did not significantly regulate ER protein level or ER transcription. In conclusion, BPAF showed the highest lethality, developmental effects, and estrogenic activity (both in silico and in vivo) followed by BPA and BPF. BPS showed the weakest toxicity and estrogenic activity. zfERβ2 might act as the main target among the three ER subtypes of zebrafish after exposure to BPAF and BPA.