Adverse effects of long-term exposure to bisphenol A during adulthood leading to hyperglycaemia and hypercholesterolemia in mice

Protective effect of curcumin against microplastic and nanoplastics toxicity

Microplastics and nanoplastics (MNPs) are present in urban dust and the aquatic environments of industrialized cities. MNPs in the human body accumulate in the lymphoid follicles, Peyer's patches of the gastrointestinal tract, and pulmonary vascular endothelial cells, which slowly result in toxicity. Since previous studies introduced curcumin as a natural protective agent against environmental toxins, we reviewed preclinical studies that had used curcumin to protect organs or cells from toxicity secondary to exposure to MNPs. It was found that exposure to MNPs resulted in osteolysis, immunotoxicity, thyroid disturbances, nephrotoxicity, neurotoxicity, hepatotoxicity, pulmonary toxicity, gastrointestinal toxicity, cardiovascular toxicity, and especially endocrine, and reproductive toxicity. Nevertheless, except for one study reviewed, curcumin restored all oxidative and histopathological damages induced by MNPs to normal due to curcumin's inherent antioxidant, antiapoptotic, anti-inflammatory, and anti-proliferative properties.

Prenatal amoxicillin exposure induces depressive-like behavior in offspring via gut microbiota and myristic acid-mediated modulation of the STING pathway

Amoxicillin is a widely used antibiotic globally, and its pervasive environmental presence poses significant risks to human health and ecosystems. Notably, prenatal amoxicillin exposure (PAmE) may have long-term neurodevelopmental toxicity for offspring. In this study, we investigated the lasting effects of PAmE on depressive-like behaviors in offspring rats, emphasizing the biological mechanisms mediated by changes in gut microbiota and its metabolite, myristic acid. Our results showed that PAmE significantly disrupted the gut microbiota composition in offspring, particularly through the reduction of Lachnospiraceae, leading to decreased levels of myristic acid. This disruption hindered the N-myristoylation of ADP-ribosylation factor 1 (ARF1), impaired the normal degradation of the stimulator of interferon genes protein, inhibited autophagic processes, and promoted M1 polarization of microglia, ultimately leading to depressive-like behaviors in the offspring. Remarkably, supplementation with Lachnospira or myristic acid effectively reversed the PAmE-induced neurodevelopmental and behavioral abnormalities, alleviating depressive-like symptoms. This study reveals how PAmE affects offspring neurodevelopment and behavior through gut microbiota and myristic acid, highlighting the crucial role of the gut-brain axis in the modulation of depressive symptoms. Supplementing Lachnospira or myristic acid could represent a novel strategy to mitigate PAmE-induced fetal-originated depression, providing new biological evidence and potential therapeutic avenues.

Exposure to bisphenol S induces organ toxicity by disrupting oxidative and antioxidant defense system and blood physiology in Labeo rohita (Hamilton, 1822)

Bisphenol S is an emerging pollutant that is contaminating aquatic ecosystems and causing detrimental effects on aquatic organisms, especially fish. Therefore, the study was designed to evaluate the toxicity of bisphenol S (BPS) through genotoxic, biochemical, histopathological, and oxidative damage in the liver, gills, and kidneys of Labeo rohita fish. Fish were exposed to three different concentrations (400 µg/L, 800 µg/L, and 1000 µg/L) of BPS for 21 days. A significant (p ≤ 0.05) decline in antioxidant enzymatic activity of superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), and peroxidase (POD) was observed in all tissues, whereas elevation in oxidative contents (TBARS and ROS) was observed. Comet analysis showed elevated olive tail moment and % of DNA damage. Light microscopy revealed several anomalies including cluster nuclei formation, damaged parenchyma cells, sinusoidal spaces, and melanomacrophage in the kidney, sinusoidal spaces, dilated hepatic vein, pyknotic nuclei, melanomacrophage, and cell necrosis in the liver and bone cell deformities, lamellar aneurysm, hyperplasia, and curved secondary gill lamellae in gills. Results of hematobiochemical analysis revealed a significant (p ≤ 0.05) increment in hematocrit, WBCs, cholesterol, blood glucose, triglycerides, AST, ALT, T3, TSH, T4, urea, and creatinine, whereas decline in RBCs, MCH, hemoglobin, proteins levels was observed. The results of the current study demonstrate that BPS has detrimental effects on the kidneys, gills, and liver. It interferes with normal functioning by inhibiting enzymatic activity, causing DNA damage, and disrupting the normal structure of vital organs. These effects make BPS toxic to fish, even at low concentrations.

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.

Bisphenol A and Its Emergent Substitutes: State of the Art of the Impact of These Plasticizers on Oxidative Stress and Its Role in Vascular Dysfunction

The "One Health approach" has evidenced the significant impact of xenobiotic exposure to health, and humans are a relevant target for their toxic effects. Bisphenol A (BPA) exerts a ubiquitous exposure source in all ecosystems. Given its endocrine-disrupting and harmful consequences on health, several countries have enforced new regulations to reduce exposure to BPA. Cardiovascular diseases (CVDs) are complex conditions that lead to higher mortality worldwide, where family history, lifestyle, and environmental factors, like BPA exposure, have a remarkable contribution. This chemical compound is the most widely used in plastic and epoxy resin manufacturing and has been associated with effects on human health. Therefore, new-generation bisphenols (NGBs) are replacing BPA use, arguing that they do not harm health. Nonetheless, the knowledge about whether NGBs are secure options is scanty. Although BPA's effects on several organs and systems have been documented, the role of BPA and NGBs in CVDs has yet to be explored. This review's goals are focused on the processes of endothelial activation (EA)-endothelial dysfunction (ED), a cornerstone of CVDs development, bisphenols' (BPs) effects on these processes through oxidant and antioxidant system alteration. Despite the scarce evidence on pro-oxidant effects associated with NGBs, our review demonstrated a comparable harmful effect on BPA. The results from the present review suggest that the biological mechanisms to explain BPs cardiotoxic effects are the oxidant stress ↔ inflammatory response ↔ EA ↔ ED → atherosclerotic plate → coagulation promotion. Other effects contributing to CVD development include altered lipid metabolism, ionic channels, and the activation of different intracellular pathways, which contribute to ED perpetuation in a concerted manner.

DHA-enriched phosphatidylserine alleviates bisphenol A-induced liver injury through regulating glycerophospholipid metabolism and the SIRT1-AMPK pathway

To investigate the alleviating effect and mechanism of the docosahexaenoic acid-enriched phosphatidylserine (DHA-PS) on bisphenol A (BPA)-induced liver injury in mice, the murine liver injury model was established by gavage of BPA (5 mg/kg) or co-administration of BPA and DHA-PS (50 mg/kg or 100 mg/kg) for 6 weeks. The results showed that after administration of 100 mg/kg DHA-PS, the liver index, serum levels of AST, ALT, TC, TG, NEFA, and LDL-C in mice were significantly decreased, while HDL-C was significantly increased. The LPS, IL-6, IL-1β, TNF-α, and MDA levels in liver tissues were effectively down-regulated, and IL-10, SOD, GSH-Px, and CAT levels were effectively up-regulated. The H&E and Oil Red O staining results showed that liver damage was notably repaired and lipid deposition was notably reduced after DHA-PS administration. Furthermore, metabolomics and immunohistochemical studies revealed that DHA-PS mainly regulates glycerophospholipid metabolism and the SIRT1-AMPK pathway to improve metabolic disorders of the liver caused by BPA. Therefore, DHA-PS could potentially alleviate BPA-induced murine liver injury through suppressing inflammation and oxidative stress, and modulating lipid metabolism disorders.

Association of urinary bisphenol A with hyperlipidemia and all-cause mortality: NHANES 2003-2016

BACKGROUND

The connection between urinary bisphenol A (BPA) and hyperlipidemia is still unclear, and few studies have evaluated whether urinary BPA affects mortality among individuals with hyperlipidemia. Therefore, we aimed to investigate the link between urinary BPA and hyperlipidemia and assess the impact of urinary BPA on mortality risk in subjects with hyperlipidemia.

METHODS

We analyzed data of the National Health and Nutrition Examination Survey from 2003 to 2016. Multivariable logistic analysis was performed to examine the relationship between urinary BPA and hyperlipidemia. Cox regression analysis was carried out to investigate the relationship between urinary BPA and all-cause mortality in subjects with hyperlipidemia.

RESULTS

This study included 8,983 participants, of whom 6,317 (70.3%) were diagnosed with hyperlipidemia. The results showed that urinary BPA was higher in participants with hyperlipidemia group than those without hyperlipidemia (3.87 ± 0.32 vs. 2.98 ± 0.14, P = 0.01). Urinary BPA levels were analyzed in tertiles. Compared with tertile 1 of BPA (reference), the odds ratio (95% confidence interval) of hyperlipidemia related to tertile 3 of BPA was 1.28 (1.11-1.48). The hazard ratio for all-cause death associated with the highest versus lowest tertile of urinary BPA was 1.20 (95% confidence interval: 1.01-1.44; P = 0.04) among participants with hyperlipidemia.

CONCLUSIONS

The study indicated a positive relationship between urinary BPA and the risk of hyperlipidemia. Urinary BPA was associated with a significantly higher risk of all-cause mortality in adults with hyperlipidemia.

Exploring novel insights into the molecular mechanisms underlying Bisphenol A-induced toxicity: A persistent threat to human health

Bisphenol A (BPA) is a ubiquitous industrial chemical used in the production of polycarbonate plastics and epoxy resins, found in numerous consumer products. Despite its widespread use, its potential adverse health effects have raised significant concerns. This review explores the molecular mechanisms and evidence-based literature underlying BPA-induced toxicities and its implications for human health. BPA is an endocrine-disrupting chemical (EDC) which exhibits carcinogenic properties by influencing various receptors, such as ER, AhR, PPARs, LXRs, and RARs. It induces oxidative stress and contributes to cellular dysfunction, inflammation, and DNA damage, ultimately leading to various toxicities including but not limited to reproductive, cardiotoxicity, neurotoxicity, and endocrine toxicity. Moreover, BPA can modify DNA methylation patterns, histone modifications, and non-coding RNA expression, leading to epigenetic changes and contribute to carcinogenesis. Overall, understanding molecular mechanisms of BPA-induced toxicity is crucial for developing effective strategies and policies to mitigate its adverse effects on human health.

The potential Association of Bisphenol A exposure and type 1 diabetes mellitus among Dakahlia Governorate's children sample, Egypt

Background

Bisphenol A (BPA) is an endocrine disrupter affecting glucose homeostasis.

Objectives

This study aimed to investigate BPA's relationship with Type 1 Diabetes Mellitus (T1DM) in Dakahlia Governorate's children, in Egypt.

Subjects materials and methods

The study had two parts: clinical and experimental. Clinical Study was conducted on 200 children, equally divided into control and T1DM groups. They underwent: demographic data, height, weight, body mass index, glycosylated HbA1C, random blood glucose, and urinary BPA measurements. Experimental Study was conducted on 60 adult albino rats. Rats were randomly divided into three equal groups: control group: received 0.5 mL of pure olive oil, group 1: received 20 mg/kg/day BPA, and group 2: received 100 mg/kg/day BPA orally for 6 weeks. Fasting and two hours postprandial glucose levels were measured at the beginning and end of the study. Histopathological examination and imaging study of the pancreas were done.

Results

In clinical study: HbA1C and random blood glucose levels in diabetic children showed a significant increase compared to control. Children in control group showed controlled HbA1C, while the T1DM group showed 86% with poor diabetic control. There was a significant increase in BPA level in the T1DM group compared to the control. Rats that received BPA showed a marked increase in fasting and two hours postprandial glucose levels, histopathological changes in the pancreas with more changes determined in the high dose group, and a significant decrease in the islets of Langerhans diameters with group 2 more affected.

Conclusion

So, BPA exposure could be considered a risk factor for T1DM in children.

Effects and mechanisms of bisphenols exposure on neurodegenerative diseases risk: A systemic review

Environmental bisphenols (BPs) pose a global threat to human health because of their extensive use as additives in plastic products. BP residues are increasing in various environmental media (i.e., water, soil, and indoor dust) and biological and human samples (i.e., serum and brain). Both epidemiological and animal studies have determined an association between exposure to BPs and an increased risk of neurodegenerative diseases (e.g., Parkinson's disease, Alzheimer's disease, and amyotrophic lateral sclerosis), including cognitive abnormalities and behavioral disturbances. Hence, understanding the biological responses to different BPs is essential for prevention, and treatment. This study provides an overview of the underlying pathogenic molecular mechanisms as a valuable basis for understanding neurodegenerative disease responses to BPs, including accumulation of misfolded proteins, reduction of tyrosine hydroxylase and dopamine, abnormal hormone signaling, neuronal death, oxidative stress, calcium homeostasis, and inflammation. These findings provide new insights into the neurotoxic potential of BPs and ultimately contribute to a comprehensive health risk evaluation.

Deciphering the Role of the Gut Microbiota in Exposure to Emerging Contaminants and Diabetes: A Review

Emerging pollutants, a category of compounds currently not regulated or inadequately regulated by law, have recently become a focal point of research due to their potential toxic effects on human health. The gut microbiota plays a pivotal role in human health; it is particularly susceptible to disruption and alteration upon exposure to a range of toxic environmental chemicals, including emerging contaminants. The disturbance of the gut microbiome caused by environmental pollutants may represent a mechanism through which environmental chemicals exert their toxic effects, a mechanism that is garnering increasing attention. However, the discussion on the toxic link between emerging pollutants and glucose metabolism remains insufficiently explored. This review aims to establish a connection between emerging pollutants and glucose metabolism through the gut microbiota, delving into the toxic impacts of these pollutants on glucose metabolism and the potential role played by the gut microbiota.

Emerging Contaminants: An Emerging Risk Factor for Diabetes Mellitus

Emerging contaminants have been increasingly recognized as critical determinants in global public health outcomes. However, the intricate relationship between these contaminants and glucose metabolism remains to be fully elucidated. The paucity of comprehensive clinical data, coupled with the need for in-depth mechanistic investigations, underscores the urgency to decipher the precise molecular and cellular pathways through which these contaminants potentially mediate the initiation and progression of diabetes mellitus. A profound understanding of the epidemiological impact of these emerging contaminants, as well as the elucidation of the underlying mechanistic pathways, is indispensable for the formulation of evidence-based policy and preventive interventions. This review systematically aggregates contemporary findings from epidemiological investigations and delves into the mechanistic correlates that tether exposure to emerging contaminants, including endocrine disruptors, perfluorinated compounds, microplastics, and antibiotics, to glycemic dysregulation. A nuanced exploration is undertaken focusing on potential dietary sources and the consequential role of the gut microbiome in their toxic effects. This review endeavors to provide a foundational reference for future investigations into the complex interplay between emerging contaminants and diabetes mellitus.

An Overview of the Health Effects of Bisphenol A from a One Health Perspective

Bisphenol A (BPA) is a chemical compound, considered as an "emerging pollutant", that appears ubiquitously, contaminating the environment and food. It is an endocrine disruptor, found in a multitude of consumer products, as it is a constituent of polycarbonate used in the manufacture of plastics and epoxy resins. Many studies have evaluated the effects of BPA, using a wide range of doses and animal models. In this work, we carried out a review of relevant research related to the effects of BPA on health, through studies performed at different doses, in different animal models, and in human monitoring studies. Numerous effects of BPA on health have been described; in different animal species, it has been reported that it interferes with fertility in both females and males and causes alterations in their offspring, as well as being associated with an increase in hormone-dependent pathologies. Similarly, exposure to BPA has been related to other diseases of great relevance in public health such as obesity, hypertension, diabetes, or neurodevelopmental disorders. Its ubiquity and nonmonotonic behavior, triggering effects at exposure levels considered "safe", make it especially relevant when both animal and human populations are constantly and inadvertently exposed to this compound. Its effects at low exposure levels make it essential to establish safe exposure levels, and research into the effects of BPA must continue and be focused from a "One Health" perspective to take into account all the factors that could intervene in the development of a disease in any exposed organism.

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.

Potential effects of bisphenol A on diabetes mellitus and its chronic complications: A narrative review

Diabetes mellitus (DM) is a metabolic disease caused by multiple factors such as genetics, environment, and lifestyle. Bisphenol A (BPA), as one of the most common endocrine-disrupting chemicals (EDCs), has been strongly implicated in the development of type 2 diabetes mellitus (T2DM). BPA exposure is associated with target organ damage in DM and may exacerbate the progression of some chronic complications of DM. This paper reviews relevant epidemiological, in vivo, and in vitro studies to better understand BPA's potential risk associations and pathological mechanisms in several chronic diabetic complications.

BPA and its alternatives BPF and BPAF exaggerate hepatic lipid metabolism disorders in male mice fed a high fat diet

Alternatives to Bisphenol A (BPA), such as BPF and BPAF, have found increasing industrial applications. However, toxicological research on these BPA analogues remains limited. This study aimed to investigate the effects of BPA, BPF, and BPAF exposure on hepatotoxicity in mice fed with high-fat diets (HFD). Male mice were exposed to the bisphenols at a dose of 0.05 mg per kg body weight per day (mg/kg bw/day) for eight consecutive weeks, or 5 mg/kg bw/day for the first week followed by 0.05 mg/kg bw/day for seven weeks under HFD. The low dose (0.05 mg/kg bw/day) was corresponding to the tolerable daily intake (TDI) of BPA and the high dose (5 mg/kg bw/day) was corresponding to its no observed adverse effect level (NOAEL). Biochemical analysis revealed that exposure to these bisphenols resulted in liver damage. Metabolomics analysis showed disturbances of fatty acid and lipid metabolism in bisphenol-exposed mouse livers. BPF and BPAF exposure reduced lipid accumulation in HFD mouse liver by lowering glyceride and cholesterol levels. Transcriptomics analysis demonstrated that expression levels of genes related to fatty acid synthesis and metabolism were changed, which might be related to the activation of the PPAR signaling pathway. Besides, a feedback regulation mechanism might exist to maintain hepatic metabolic homeostasis. For the first time, this study demonstrated the effects of BPF and BPAF exposure in HFD-mouse liver. Considering the reality of the high prevalence of obesity nowadays and the ubiquitous environmental distribution of bisphenols, this study provides insight and highlights the adverse effects of BPA alternatives, further contributing to the consideration of the safe use of such compounds.

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.

Current Evidence on Bisphenol A Exposure and the Molecular Mechanism Involved in Related Pathological Conditions

Bisphenol A (BPA) is one of the so-called endocrine disrupting chemicals (EDCs) and is thought to be involved in the pathogenesis of different morbid conditions: immune-mediated disorders, type-2 diabetes mellitus, cardiovascular diseases, and cancer. The purpose of this review is to analyze the mechanism of action of bisphenol A, with a special focus on mesenchymal stromal/stem cells (MSCs) and adipogenesis. Its uses will be assessed in various fields: dental, orthopedic, and industrial. The different pathological or physiological conditions altered by BPA and the related molecular pathways will be taken into consideration.

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.

Relation of urinary bisphenol concentration and diabetes or prediabetes in French adults: A cross-sectional study

BACKGROUND

International research has recently shown an association between exposure to bisphenol A (BPA) and the risk of diabetes, although limited results are available for exposure to bisphenol S (BPS) and bisphenol F (BPF). The aim of this study was to examine the relationships between impregnation with BPA, BPS, and BPF and the prevalence of diabetes or prediabetes in the French adult population.

METHODS

Based on the Esteban cross-sectional study, 852 adults aged 18 to 74 years living in France were included. To assess the link between urinary concentration of BPA, BPS and BPF and a state of dysglycemia (diabetes or prediabetes), logistic regression multivariable models were performed and adjusted for known risk factors for diabetes and urine creatinine concentration.

RESULTS

The percentage of included individuals with diabetes or prediabetes was 17.8% (95% CI = [15.3-20.4]). Urinary BPA concentration was significantly higher in people with diabetes or prediabetes, independent of the known risk factors for diabetes (OR for an increase of 0.1 units in log-transformed concentration of BPA (μg/L) = 1.12; 95%CI = [1.05-1.19], p < 0.001). However, we did not find any significant independent association between urinary BPS and BPF levels and the prevalence of diabetes or prediabetes.

CONCLUSIONS

In this sample, considering the diabetes risk factors, diabetes or prediabetes was positively associated with higher urinary BPA concentration but not with urinary BPS and BPF concentrations. However, analysis of prospective longitudinal studies are still necessary to demonstrate a causal link between bisphenol exposure and the risk of diabetes or prediabetes.

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.

Association of serum BPA levels with changes in lipid levels and dyslipidemia risk in middle-aged and elderly Chinese

Previous evidences exploring the associations of BPA with lipid changes and dyslipidemia did not obtain consistent results. To evaluate whether serum BPA concentration was associated with changes in blood lipid levels and incident dyslipidemia risk in middle-elderly Chinese adults, we conducted a prospective study with 1093 participants (average 62.65 years old) derived from the Dongfeng-Tongji cohort which was founded in 2008 and followed up each 5 years. Serum BPA levels were measured by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS). Changes in lipid levels were named as Δ lipids which equal to Lipid₂₀₁₃ - Lipid₂₀₀₈. The diagnosis of dyslipidemia was according to Chinese Guidelines on Prevention and Treatment of Dyslipidemia in 2016. We used multivariable linear regression and Logistic regression to explore the relations between serum BPA levels and changes in lipid levels and incident dyslipidemia risk, respectively. Besides, restricted cubic splines were used to explore the dose-response relations. After 5 years' follow-up, 51 individuals developed with hypercholesterolemia, 87 with hypertriglyceridemia, 34 with high-LDL-cholesterolemia, 74 with low-HDL-cholesterolemia, and 199 with dyslipidemia. At baseline serum BPA levels were positively related to TC, LDL-c, and Non-HDL-c levels. In the prospective study, each Ln-BPA increase was associated with 0.05 (95% CI: 0.02, 0.09) mmol/L increase in Δ TC, 0.07 (95% CI:0.03, 0.11) mmol/L increase in Δ Non-HDL-c, 0.05 (95% CI: 0.01, 0.08) increase in Δ TC/HDL-c, and 0.05 (95% CI: 0.01, 0.08) increase in Δ Non-HDL-c/HDL-c. We only observed significant associations in females but not in males. Besides, serum BPA levels were positively associated with hypercholesterolemia (OR=1.12, 95% CI: 1.01, 1.25). The restricted cubic splines obtained similar results. In conclusion, serum BPA was associated TC and Non-HDL-c changes, and BPA was also associated with increased risk of hypertriglyceridemia. Further prospective studies with large sample size are warranted to validate our findings.

Bisphenol A damages testicular junctional proteins transgenerationally in mice

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

Are BPA Substitutes as Obesogenic as BPA?

Metabolic diseases, such as obesity, Type II diabetes and hepatic steatosis, are a significant public health concern affecting more than half a billion people worldwide. The prevalence of these diseases is constantly increasing in developed countries, affecting all age groups. The pathogenesis of metabolic diseases is complex and multifactorial. Inducer factors can either be genetic or linked to a sedentary lifestyle and/or consumption of high-fat and sugar diets. In 2002, a new concept of “environmental obesogens” emerged, suggesting that environmental chemicals could play an active role in the etiology of obesity. Bisphenol A (BPA), a xenoestrogen widely used in the plastic food packaging industry has been shown to affect many physiological functions and has been linked to reproductive, endocrine and metabolic disorders and cancer. Therefore, the widespread use of BPA during the last 30 years could have contributed to the increased incidence of metabolic diseases. BPA was banned in baby bottles in Canada in 2008 and in all food-oriented packaging in France from 1 January 2015. Since the BPA ban, substitutes with a similar structure and properties have been used by industrials even though their toxic potential is unknown. Bisphenol S has mainly replaced BPA in consumer products as reflected by the almost ubiquitous human exposure to this contaminant. This review focuses on the metabolic effects and targets of BPA and recent data, which suggest comparable effects of the structural analogs used as substitutes.

Urinary bisphenol concentrations and its association with metabolic disorders in the US and Korean populations

Bisphenol A (BPA) is a representative endocrine disrupting compound used in a vast array of consumer products, and are being frequently substituted by its analogues, bisphenol S (BPS) and bisphenol F (BPF). We aimed to examine the association between urinary bisphenol levels with obesity and lipid profiles in the general population to comprehensively evaluate its potential of metabolic disturbance. A representative sample of 1046 US adults from the National Health and Nutrition Examination Survey (2013-2016) and 3268 Korean adults from the Korean National Environmental Health Survey (2015-2017) was analyzed. We examined the exposure levels of bisphenols and determined their associations with obesity, high-density lipoprotein cholesterol (HDL-C) and triglyceride (TG) levels, and hypercholesterolemia prevalence through multiple linear, and binary/ordinal logistic regression models. In both populations, high BPA levels (lowest tertile vs. 2nd, 3rd tertiles) showed corresponding associations with lipid profile and obesity. BPA levels were associated with decreased HDL-C levels (Q3: β = -0.053, p = 0.08 (US); Q2: β = -0.030, p-0.03), increased TG levels (Q3: β = 0.121, p = 0.029 (US); Q3: β = 0.089, p = 0.021, and higher odds for obesity (Q3: OR = 1.58, 95% CI: 1.06, 2.35 (US); Q3: OR = 1.41, 95% CI: 1.11, 1.78). Higher BPS levels were positively associated with obesity status, especially in US men (Q2: OR = 1.84, 95% CI: 1.15, 2.96) and Korean women (Q3: OR = 1.27, 95% CI: 0.99, 1.64). A significant decrease in HDL-C (Q3: β = -0.088, p = 0.01) and elevated odds for obesity at higher BPF levels (Q3: OR = 1.60, 95% CI: 1.00, 2.56) was observed in US women. The findings of our study indicate that BPA and its analogues, BPS and BPF, are associated with lipid metabolism disorders in addition to obesity in adults. Given the increase in exposure to BPA alternatives, continuous biomonitoring, and further investigation of their health effects through prospective cohort studies are warranted.

Analysis of Indirect Biomarkers of Effect after Exposure to Low Doses of Bisphenol A in a Study of Successive Generations of Mice

Simple Summary

Living beings are constantly and inadvertently exposed to a series of environmental and food pollutants, triggering effects on health that are transmitted over generations. Bisphenol A is a compound produced in large amounts world-wide and used in the manufacture of plastic containers and other utensils for daily use. It is an environmental and food pollutant with a demonstrated capacity to produce effects on the health of organisms exposed to it. The objective of our study was to identify possible indirect biomarkers of effect by means of the analysis of the blood biochemistry, and of certain reproductive parameters of animals exposed to Bisphenol A in doses considered to be safe over different generations. Our results did not show any modifications in the reproduction parameters evaluated, such as the duration of the estrous cycle, the size of the litters, or the percentage of the young alive at weaning time. However, they showed that there were alterations in biochemical parameters like glucose, total proteins, and albumin, which could therefore, be regarded as indirect indicators of an early effect of alterations in health caused by this compound.

Abstract

Bisphenol A (BPA) is considered as being an emerging pollutant, to which both animal and human populations are continuously and inadvertently exposed. The identification of indirect biomarkers of effect could be a key factor in determining early adverse outcomes from exposure to low doses of BPA. Thus, this study on mice aims to evaluate and identify indirect biomarkers of effect through the analysis of their blood biochemistry, and of certain reproduction parameters after exposure to different BPA concentrations (0.5, 2, 4, 50, and 100 µg/kg BW/day) in drinking water over generations. Our results showed that there were no modifications in the reproductive parameters evaluated, like estrous cycle duration, litter size, or the percentage of the young alive at reaching the weaning stage, at the exposure levels evaluated. However, there were modifications in the biochemical parameters, e.g., alterations in the glucose levels, that increased significantly (p < 0.05) in the breeders at the higher exposure doses (50 and 100 µg/kg BW/day in F1; 50 µg/kg BW/day in F2 and 100 µg/kg BW/day in F3), that would suggest that the BPA could induce hyperglycemia and its complications in adult animals, probably due to some damage in the pancreas cells; albumin, that increased in the breeders exposed to the highest dose in F1 and F3, inferring possible hepatic alterations. Further, total proteins showed a diminution in their values in F1 and F2, except the group exposed to 100 µg/kg BW/day, whereas in F3 the values of this parameter increased with respect to the control group, this aspect likely being related to a possible hepatic and renal alteration. Based on these results, glucose, albumin, and total proteins could initially be considered as early indicators of indirect effect after prolonged exposure to low BPA doses over generations.

Integrated Genomic and Bioinformatics Approaches to Identify Molecular Links between Endocrine Disruptors and Adverse Outcomes

Exposure to Endocrine Disrupting Chemicals (EDC) has been linked with several adverse outcomes. In this review, we examine EDCs that are pervasive in the environment and are of concern in the context of human, animal, and environmental health. We explore the consequences of EDC exposure on aquatic life, terrestrial animals, and humans. We focus on the exploitation of genomics technologies and in particular whole transcriptome sequencing. Genome-wide analyses using RNAseq provides snap shots of cellular, tissue and whole organism transcriptomes under normal physiological and EDC perturbed conditions. A global view of gene expression provides highly valuable information as it uncovers gene families or more specifically, pathways that are affected by EDC exposures, but also reveals those that are unaffected. Hypotheses about genes with unknown functions can also be formed by comparison of their expression levels with genes of known function. Risk assessment strategies leveraging genomic technologies and the development of toxicology databases are explored. Finally, we review how the Adverse Outcome Pathway (AOP) has exploited this high throughput data to provide a framework for toxicology studies.

Effects of bisphenol A on pancreas and thyroid gland of young and adult female Sprague Dawlеy rats

Bisphenol A (BPA), a chemical involved in formation of plastic vessels, is one of the most widespread endocrine disrupting chemicals. The study was designed to investigate the effect of BPA on pancreas and thyroid gland of young and adult female Sprague Dawley rats. The rats were exposed to 330 mg/kg BPA orally every other day for 12 weeks; control rats were exposed orally to ethyl alcohol and corn oil. Samples were collected at 4, 8 and 12 weeks for hormonal, biochemical assays and histopathological examination. The insulin hormone in exposed young rats was decreased, but its level in adult ones was increased; the biochemical assay for blood sugar level showed a significant increase in young rats and decrease in adult ones. T3 hormone was increased in treated young and adult rats; T4 hormone was increased in treated adults, while calcium level was decreased in treated adult rats. The histopathological findings of pancreas revealed vacuolation in its endocrine parts in young rats, while in adult ones there was intralobular fatty infiltration - a typical picture of diabetes. The thyroid gland in treated young female rats showed increased cellularity of parafollicular cells; moreover there was parafollicular haemorrhage, and in adult ones - desquamation in lining epithelium of follicular cells. In conclusion, exposure of young and adult female rats to BPA resulted in changes in the pancreatic and thyroid gland cells manifested by morphological, hormonal and biochemical parameters.

Multi-parameter risk assessment of forty-one selected substances with endocrine disruptive properties in surface waters worldwide

The increasing use of substances with endocrine disruptive properties (EDs) not only impacts aquatic organisms but can also have a direct negative effect on human health. In this comprehensive worldwide review, we collected ecotoxicology and concentration data observed in surface water for 53 high-potency EDs and performed a risk assessment. The compounds were selected from the EU watchlist of priority substances, expanded with new compounds of emerging concern (total 41), where quantifiable data were available for the past three years (2018-2020). The risk quotients ranged from <0.01 for 22 substances to 1974 for tamoxifen. The frequency of samples in which the predicted no-effect concentrations were exceeded also varied, from 1.8% to 92.7%. By using the comprehensive multi-parameter risk assessment in our study, the most current to date, we determined that tamoxifen, imidacloprid, clothianidin, four bisphenols (BPA, BPF, BPS, and BPAF), PFOA, amoxicillin, and three steroid hormones (estriol, estrone, and cyproterone) pose significant risks in the environment. Comparing two structurally very similar bisphenols, BPA and BPB, suggested that the risk from BPB is currently underestimated by at least four orders of magnitude due to the lack of ecotoxicological data availability. The methodological limitations encountered suggest that a standardized methodology for data selection and assessment is necessary, highlighting the fact that some substances are currently under-represented in the field of ecotoxicological research. A new prioritization system is therefore presented, which provides a potential basis for new substances to be included in environmental monitoring lists.

Protracted Impairment of Maternal Metabolic Health in Mouse Dams Following Pregnancy Exposure to a Mixture of Low Dose Endocrine-Disrupting Chemicals, a Pilot Study

Pregnancy, a period of increased metabolic demands coordinated by fluctuating steroid hormones, is an understudied critical window of disease susceptibility for later-life maternal metabolic health. Epidemiological studies have identified associations between exposures to various endocrine-disrupting chemicals (EDCs) with an increased risk for metabolic syndrome, obesity, and diabetes. Whether such adverse outcomes would be heightened by concurrent exposures to multiple EDCs during pregnancy, consistent with the reality that human exposures are to EDC mixtures, was examined in the current pilot study. Mouse dams were orally exposed to relatively low doses of four EDCs: (atrazine (10 mg/kg), bisphenol-A (50 µg/kg), perfluorooctanoic acid (0.1 mg/kg), 2,3,7,8-tetrachlorodibenzo-p-dioxin (0.036 µg/kg)), or the combination (MIX), from gestational day 7 until birth or for an equivalent 12 days in non-pregnant females. Glucose intolerance, serum lipids, weight, and visceral adiposity were assessed six months later. MIX-exposed dams exhibited hyperglycemia with a persistent elevation in blood glucose two hours after glucose administration in a glucose tolerance test, whereas no such effects were observed in MIX-exposed non-pregnant females. Correspondingly, MIX dams showed elevated serum low-density lipoprotein (LDL). There were no statistically significant differences in weight or visceral adipose; MIX dams showed an average visceral adipose volume to body volume ratio of 0.09, while the vehicle dams had an average ratio of 0.07. Collectively, these findings provide biological plausibility for the epidemiological associations observed between EDC exposures during pregnancy and subsequent maternal metabolic dyshomeostasis, and proof of concept data that highlight the importance of considering complex EDC mixtures based of off common health outcomes, e.g., for increased risk for later-life maternal metabolic effects following pregnancy.

Potential role of green tea extract and epigallocatechin gallate in preventing bisphenol A-induced metabolic disorders in rats: Biochemical and molecular evidence

BACKGROUND

Bisphenol A (BPA) is an artificial chemical widely used in the production of polycarbonate plastics and epoxy resins. Accumulating evidence indicates that BPA exposure is associated with metabolic disorders. The beneficial effects of green tea and epigallocatechin gallate (EGCG), major catechin present in green tea, on alleviating BPA-induced metabolic disorders have been shown in various studies.

PURPOSE

Protective effects of green tea extract and EGCG on BPA-induced metabolic disorders and possible underlying mechanisms were investigated.

METHODS

Rats were randomly divided into control, green tea extract (50 and 100 mg/kg, IP), EGCG (20 and 40 mg/kg, IP), BPA (10 mg/kg, gavage), BPA plus green tea extract (25, 50, and 100 mg/kg, IP), BPA plus EGCG (10, 20, and 40 mg/kg, IP), and BPA plus vitamin E (200 IU/kg, IP). After two months, body weight, blood pressure, biochemical blood tests, hepatic malondialdehyde (MDA), and glutathione (GSH) were assessed. By enzyme-linked immunosorbent assay, serum levels of insulin, leptin, adiponectin, TNFα, and IL-6, and by western blotting, hepatic insulin signaling (IRS-1, PI3K, Akt) were measured.

RESULTS

BPA increased body weight, blood pressure, and MDA, decreased GSH, elevated serum levels of low-density lipoprotein cholesterol, total cholesterol, triglyceride, glucose, insulin, leptin, TNFα, IL-6, and liver enzymes including alanine aminotransferase and alkaline phosphatase, and lowered high-density lipoprotein cholesterol and adiponectin levels. In western blot, decreased phosphorylation of IRS-1, PI3K, and Akt was obtained. Administration of green tea extract, EGCG, or vitamin E with BPA reduced the detrimental effects of BPA.

CONCLUSION

These findings indicate that green tea extract and EGCG can be effective in preventing or reducing metabolic disorders induced by BPA linked to their antioxidant and anti-inflammatory activity, regulating the metabolism of lipids, and improving insulin signaling pathways.

Perturbation of serum metabolome in relation to type 2 diabetes mellitus and urinary levels of phthalate metabolites and bisphenols

BACKGROUND

Emerging evidence has proved the associations between exposure to phthalates (PAEs) and bisphenols and type 2 diabetes mellitus (T2DM), but the underlying mechanisms for these associations are poorly understood. Metabolomics is a powerful tool to identify differential metabolites and metabolic pathways related to diseases and chemical exposure, which may reveal underlying mechanisms. However, little is known about the roles of metabolism in the associations for PAE and bisphenol exposure with T2DM.

OBJECTIVES

The purpose of the study was to investigate the roles of metabolism in the associations for exposure to PAEs and bisphenols with T2DM.

METHODS

In this study, 60 T2DM cases and 60 controls, who were matched in age, sex, and body mass index (BMI), were selected from the total study population in our previous studies. Fasting blood and spot urine samples of the volunteers were used for non-targeted metabolomics analysis and determination of phthalate metabolites (mPAEs) and bisphenols, respectively. The associations of urinary mPAEs and bisphenols with screened metabolic biomarkers in metabolomics analysis were analyzed using multiple linear regression models.

RESULTS

Based on non-targeted metabolomics, 19 serum metabolic biomarkers were screened between T2DM cases and controls, mostly related to galactose metabolism, amino acid metabolism, and pyrimidine metabolism. More than half of mPAEs were mostly positively associated with up-regulated metabolic biomarkers and negatively associated with down-regulated biomarkers. Different from PAEs, no evident results suggested the roles of metabolism in the associations between bisphenol exposure and T2DM.

CONCLUSIONS

Combined with the positive associations between most urinary mPAEs and T2DM in our previous study, our findings indicated that PAE exposure may contribute to T2DM risk through disturbing galactose metabolism, amino acid metabolism (especially arginine biosynthesis and alanine, aspartate and glutamate metabolism), and pyrimidine metabolism.

Activation of pregnane X receptor induces atherogenic lipids and PCSK9 by a SREBP2-mediated mechanism

BACKGROUND AND PURPOSE

Many drugs and environmental contaminants induce hypercholesterolemia and promote the risk of atherosclerotic cardiovascular disease. We tested the hypothesis that pregnane X receptor (PXR), a xenobiotic-sensing nuclear receptor, regulates the level of circulating atherogenic lipids in humans and utilized mouse experiments to identify the mechanisms involved.

EXPERIMENTAL APPROACH

We performed serum NMR metabolomics in healthy volunteers administered rifampicin, a prototypical human PXR ligand or placebo in a crossover setting. We used high-fat diet fed wild-type and PXR knockout mice to investigate the mechanisms mediating the PXR-induced alterations in cholesterol homeostasis.

KEY RESULTS

Activation of PXR induced cholesterogenesis both in pre-clinical and clinical settings. In human volunteers, rifampicin increased intermediate-density lipoprotein (IDL), low-density lipoprotein (LDL) and total cholesterol and lathosterol-cholesterol ratio, a marker of cholesterol synthesis, suggesting increased cholesterol synthesis. Experiments in mice indicated that PXR activation causes widespread induction of the cholesterol synthesis genes including the rate-limiting Hmgcr and upregulates the intermediates in the Kandutsch-Russell cholesterol synthesis pathway in the liver. Additionally, PXR activation induced plasma proprotein convertase subtilisin/kexin type 9 (PCSK9), a negative regulator of hepatic LDL uptake, in both mice and humans. We propose that these effects were mediated through increased proteolytic activation of sterol regulatory element-binding protein 2 (SREBP2) in response to PXR activation.

CONCLUSION AND IMPLICATIONS

PXR activation induces cholesterol synthesis, elevating LDL and total cholesterol in humans. The PXR-SREBP2 pathway is a novel regulator of the cholesterol and PCSK9 synthesis and a molecular mechanism for drug- and chemical-induced hypercholesterolemia.

Gestational bisphenol A exposure induces fatty liver development in male offspring mice through the inhibition of HNF1b and upregulation of PPARγ

Bisphenol A (BPA) is an endocrine-disrupting chemical (EDC) associated with non-alcoholic fatty liver disease (NAFLD). The effects of gestational BPA exposure on hepatic lipid accumulation in offspring are not fully understood. Here, we investigate the sex-dependent effects of gestational BPA exposure on hepatic lipid and glucose metabolism in the offspring of mice to reveal the mechanisms underlying gestational BPA exposure-associated NAFLD. Pregnant mice were administered gavage with or without 1 μg kg-1 day-1 BPA at embryonic day 7.5 (E7.5)-E16.5. Hepatic glucose and lipid metabolism were evaluated in these models. Both male and female offspring mice exhibited hepatic fatty liver after BPA treatment. Lipid accumulation and dysfunction of glucose metabolism were observed in male offspring. We revealed abnormal expression of lipid regulators in the liver and that inhibition of peroxisome proliferator-activated receptor γ (PPARγ) repressed hepatic lipid accumulation induced by gestational BPA exposure. We also found a sex-dependent decrease of hepatocyte nuclear factor 1b (HNF1b) expression in male offspring. The transcriptional repression of PPARγ by HNF1b was confirmed in L02 cells. Downregulation of HNF1b, upregulation of PPARγ, and subsequent upregulation of hepatic lipid accumulation were essential for NAFLD development in male offspring gestationally exposed to BPA as well as BPA-exposed adult male mice. Dysregulation of the HNF1b/PPARγ pathway may be involved in gestational BPA exposure-induced NAFLD in male offspring. These data provide new insights into the mechanism of gestational BPA exposure-associated sex-dependent glucose and lipid metabolic dysfunction. Graphical abstract Schematic of the mechanism of gestational BPA exposure-induced glucose and lipid metabolic dysfunction.

Bisphenol A and Type 2 Diabetes Mellitus: A Review of Epidemiologic, Functional, and Early Life Factors

Type 2 diabetes mellitus (T2DM) is characterised by insulin resistance and eventual pancreatic β-cell dysfunction, resulting in persistent high blood glucose levels. Endocrine disrupting chemicals (EDCs) such as bisphenol A (BPA) are currently under scrutiny as they are implicated in the development of metabolic diseases, including T2DM. BPA is a pervasive EDC, being the main constituent of polycarbonate plastics. It can enter the human body by ingestion, through the skin, and cross from mother to offspring via the placenta or breast milk. BPA is a xenoestrogen that alters various aspects of beta cell metabolism via the modulation of oestrogen receptor signalling. In vivo and in vitro models reveal that varying concentrations of BPA disrupt glucose homeostasis and pancreatic β-cell function by altering gene expression and mitochondrial morphology. BPA also plays a role in the development of insulin resistance and has been linked to long-term adverse metabolic effects following foetal and perinatal exposure. Several epidemiological studies reveal a significant association between BPA and the development of insulin resistance and impaired glucose homeostasis, although conflicting findings driven by multiple confounding factors have been reported. In this review, the main findings of epidemiological and functional studies are summarised and compared, and their respective strengths and limitations are discussed. Further research is essential for understanding the exact mechanism of BPA action in various tissues and the extent of its effects on humans at environmentally relevant doses.

Advances in BPA-induced Oxidative Stress and Related Effects and Mechanisms in Liver, 1991-2017

Bisphenol A (BPA) is a widely spreading environmental endocrine disruptor . Its characteristics, including small doses and frequent contact, make it easy to enter human body through drinking water, food, air and other pathways, leading to tumors, infertility, and liver damage. The present review summarizes the underlying mechanism of oxidative stress and its related effects induced by BPA in the liver. The progress of the mechanism for oxidative stress induced by BPA is summarized, including mitochondrial dysfunction, lipid peroxidation and inflammation reaction, liver dyslipidemia, apoptosis, and cell death mechanism. In the future, it is necessary to elucidate the molecular mechanisms and timing of oxidative stress to clarify the effects on different exposures to different genders and growth stages. Besides, studying the toxic effects on BPA surrogates, BPA metabolites and BPA combined with other pollutants in the environment is beneficial to clarify the environmental and human health effects of BPA and provide technical reference for the development of practical control measures.

The Effect of Korean Red Ginseng on Bisphenol A-Induced Fatty Acid Composition and Lipid Metabolism-Related Gene Expression Changes

Bisphenol A (BPA), which is known to be an endocrine-disrupting chemical (EDC), is associated not only with estrogen activity and reproductive toxicity but also with a variety of metabolic disorders. BPA affects glucose tolerance, cholesterol biosynthesis, and fatty acid synthesis. Ginseng is a traditional medicinal plant that has been widely used in East Asia for more than 2000 years, and a number of health effects have been reported. Korean Red Ginseng (KRG) has also been shown to have effects on lipid metabolism and body weight reduction in vivo in obese mice. In this study, we administered BPA and KRG to ovariectomized (OVX) ICR mice. BPA (800 mg/kg/day) and KRG (1.2 g/kg/day) were orally administered to OVX mice for 3 days. KRG inhibited the increase in total fatty acid level by BPA as determined by lipid profiling in the liver of OVX mice. In addition, transcriptome analysis showed that KRG inhibited BPA-induced changes in lipid metabolic process-related genes. Our findings suggest that KRG can regulate BPA-induced changes in lipid metabolism.

Staphylococcal Enterotoxin C2 Mutant-Directed Fatty Acid and Mitochondrial Energy Metabolic Programs Regulate CD8+ T Cell Activation

CD8⁺ T cells can switch between fatty acid catabolism and mitochondrial energy metabolism to sustain expansion and their cytotoxic functions. ST-4 is a TCR-enhanced mutant derived from superantigen staphylococcal enterotoxin C2 (SEC2), which can hyperactivate CD4⁺ T cells without MHC class II molecules. However, whether ST-4/SEC2 can enhance metabolic reprogramming in CD8⁺ T cells remains poorly understood. In this study, we found that ST-4, but not SEC2, could induce proliferation of purified CD8⁺ T cell from BALB/c mice in Vβ8.2- and -8.3-specific manners. Results of gas chromatography-mass spectroscopy analysis showed that fatty acid contents in CD8⁺ T cells were increased after ST-4 stimulation. Flow cytometry and Seahorse analyses showed that ST-4 significantly promoted mitochondrial energy metabolism in CD8⁺ T cells. We also observed significantly upregulated levels of gene transcripts for fatty acid uptake and synthesis, and significantly increased protein expression levels of fatty acid and mitochondrial metabolic markers of mTOR/PPARγ/SREBP1 and p38-MAPK signaling pathways in ST-4-activated CD8⁺ T cells. However, blocking mTOR, PPARγ, SREBP1, or p38-MAPK signals with specific inhibitors could significantly relieve the enhanced fatty acid catabolism and mitochondrial capacity induced by ST-4. In addition, blocking these signals inhibited ST-4-stimulated CD8⁺ T cell proliferation and effector functions. Taken together, our findings demonstrate that ST-4 enhanced fatty acid and mitochondria metabolic reprogramming through mTOR/PPARγ/SREBP and p38-MAPK signaling pathways, which may be important regulatory mechanisms of CD8⁺ T cell activation. Understanding the effects of ST-4-induced regulatory metabolic networks on CD8⁺ T cells provide important mechanistic insights to superantigen-based tumor therapy.

Acute and long-term metabolic consequences of early developmental Bisphenol A exposure in zebrafish (Danio rerio)

Bisphenol A (BPA) is an estrogenic contaminant linked to metabolic disruption. Developmental BPA exposure is of particular concern, as organizational effects may irreversibly disrupt metabolism at later life-stages. While BPA exposures in adult fish elicit metabolic perturbations similar to effects described in rodents, the metabolic effects of developmental BPA exposure in juvenile fish remain largely unknown. Following embryonic zebrafish exposure to BPA (0.1, 1 and 4 mg/L) and EE₂ (10 ng/L) from 2 to 5 dpf, we assessed the metabolic phenotype in larvae (4-6 dpf) and juveniles (43-49 dpf) which had been divided into regular-fed and overfed groups at 29 dpf. Developmental BPA exposure in larvae dose-dependently reduced food-intake and locomotion and increased energy expenditure. Juveniles (29 dpf) exhibited a transient increase in body weight after developmental BPA exposure and persistent diet-dependent locomotion changes (43-49 dpf). At the molecular level, glucose and lipid metabolism-related transcript abundance clearly separated BPA exposed fish from controls and EE₂ exposed fish at the larval stage, in juveniles on a regular diet and, to a lesser extent, in overfed juveniles. In general, the metabolic endpoints affected by BPA exposure were not mimicked by EE₂ treatment. We conclude that developmental BPA exposure elicits acute metabolic effects in zebrafish larvae and fewer transient and persistent effects in juveniles and that these metabolic effects are largely independent of BPA's estrogenicity.

Chronic exposure of bisphenol A impairs carbohydrate and lipid metabolism by altering corresponding enzymatic and metabolic pathways

Bisphenol-A (BPA), a widespread endocrine-disrupting chemical, has been recognized as a risk factor for metabolic disorders. BPA is considered to be involved in the impairment of carbohydrate and lipid metabolism but the underlying mechanisms still need to be elucidated. Present study was aimed to investigate the impact of BPA exposure on enzymatic and metabolic pathways that are responsible to regulate the carbohydrate and lipid metabolism. Experimental rats were exposed to different doses of BPA (50, 500, 2500 and 5000 μg/kg/day orally) dissolved in 1.5% dimethyl sulfoxide for a period of 3 months. Serum level of key metabolic enzymes (α-amylase, α-glucosidase, hexokinase, glucose-6-phosphatase and HMG-CoA-reductase) was measured by ELISA method. BPA-exposure suppressed the mRNA expression of gene encoding insulin resulting in poor insulin production. While hexokinase, acetyl-CoA carboxylase and squalene epoxide were up-regulated upon BPA exposure that justified the increased lipid profile. Moreover, BPA exposure showed considerably decreased glucose uptake through insulin signaling via Akt/GLUT4 pathways. There was a significant (p < 0.001) reduction in tissue level of glucose transporters. BPA significantly (p < 0.001) decreased the serum levels of oxidative stress biomarkers (GSH, CAT, and SOD). Serum levels of leptin, TNF-α, and IL-6 were rapidly increased upon exposure to BPA (p < 0.001). It was clearly evident from this study that BPA disturbed the carbohydrate and lipid metabolism after chronic exposure. It also accelerated the inflammatory processes by increasing the oxidative stress which ultimately lead towards the insulin resistance and impaired carbohydrate and lipid metabolism.

Cardiovascular toxicity and mechanism of bisphenol A and emerging risk of bisphenol S

Epidemiological and animal studies indicate that increased exposure to bisphenol A (BPA) induces various human cardiovascular diseases (CVDs), including myocardial infarction, arrhythmias, dilated cardiomyopathy, atherosclerosis, and hypertension. Bisphenol S (BPS), an alternative to BPA, is increasingly present in various consumer products and human bodies worldwide. Recently, emerging evidence has shown that BPS might be related to cardiovascular disorders. In this review, we present striking evidence of the correlation between BPA exposure and various CVDs, and show that a nonmonotonic dose-response curve (NMDRC) was common in studies of the CV effects of BPA in vivo. The CV impairment induced by low doses of BPA should be highlighted, especially during developmental exposure or during coexposure with other risk factors. Furthermore, we explored the possible underlying mechanisms of these effects-particularly nuclear receptor signaling, ion channels, and epigenetic mechanisms-and the possible participation of lipid metabolism, oxidative stress and cell signaling. As the potential risks of BPA exposure in humans are still noteworthy, studies of BPA in CVDs should be strengthened, especially with respect to the mechanisms, prevention and treatment. Moreover, the potential CV risk of BPS reported by in vivo studies calls for immediate epidemiological investigations and animal studies to reveal the relationships of BPS and other BPA alternatives with human CVDs.

The interactions of diet-induced obesity and organophosphate flame retardant exposure on energy homeostasis in adult male and female mice

Previously, sex-dependent alterations in energy homeostasis were reported in adult mice fed a standard chow attributed to exposure to a mixture of organophosphate flame retardants (OPFRs) via estrogen receptors (ERα). In this study, adult male and female mice (C57BL/6J; Taconic) were treated with the same mixture of OPFRs (1 mg/kg each of tricresyl phosphate (TCP), triphenyl phosphate (TPP), and tris(1-3-dichloro-2propyl)phosphate (TDCPP)) for 7 weeks on a low-fat diet (LFD, 10% kcal fat) or a high fat (HFD, 45% kcal fat) in a diet-induced obesity model. Consistent with our previous observations, OPFRs altered weight gain in males, differentially with diet, while females remained unaffected. OPFR treatment also revealed sex-dependent perturbations in metabolic activity. During the night (approximately 0100-0400 hr), males exhibited elevated activity and oxygen consumption, while in females these parameters were decreased, irrespective of diet. OPFR disrupted feeding behavior and abolished diurnal water intake patterns in females while increasing nighttime fluid consumption in males. Despite no marked effect of OPFRs on glucose or insulin tolerance, OPFR treatment altered circulating insulin and leptin in females and ghrelin in males. Data indicate that adult OPFR exposure might influence, and perhaps exacerbate, the effects of diet-induced obesity in adult mice by altering activity, ingestive behavior, and metabolism.

Global liver proteomic analysis of Wistar rats chronically exposed to low-levels of bisphenol A and S

Exposure to bisphenol A (BPA) and bisphenol S (BPS) has been associated with the development of metabolic disorders, such as obesity, dyslipidemias, and nonalcoholic fatty liver disease. Nonetheless, the associated mechanisms are still not fully understood. BPS is being used with no restrictions to replace BPA, which increases the concern regarding its safety and claims for further investigation on its potential mechanisms of toxicity. The present study aims to access liver molecular disturbances which could be associated with systemic metabolic disorders following exposure to BPA or BPS. Therefore, body weight gain and serum biochemical parameters were measured in male Wistar rats chronically exposed to 50 or 500 µg/kg/day of BPA or BPS, while an extensive evaluation of liver protein expression changes was conducted after exposure to 50 µg/kg/day of both compounds. Exposure to the lowest dose of BPA led to the development of hyperglycemia and hypercholesterolemia, while the BPS lowest dose led to the development of hypertriglyceridemia. Besides, exposure to 500 µg/kg/day of BPS significantly increased body weight gain and LDL-cholesterol levels. Hepatic proteins differentially expressed in BPA and BPS-exposed groups compared to the control group were mostly related to lipid metabolism and synthesis, with upregulation of glucokinase activity-related sequence 1 (1.8-fold in BPA and 2.4-fold in BPS), which is involved in glycerol triglycerides synthesis, and hydroxymethylglutaryl-CoA synthase cytoplasmic (2-fold in BPS), an enzyme involved in mevalonate biosynthesis. Essential mitochondrial proteins of the electron transport chain were upregulated after exposure to both contaminants. Also, BPA and BPS dysregulated expression of liver antioxidant enzymes, which are involved in cellular reactive oxygen species detoxification. Altogether, the results of the present study contribute to expand the scientific understanding of how BPA and BPS lead to the development of metabolic disorders and reinforce the risks associated with exposure to these contaminants.

The Mechanism of Bisphenol A Atherogenicity Involves Apolipoprotein A-I Downregulation through NF-κB Activation

Apolipoprotein A-I (apoA-I) is the major protein component of high-density lipoproteins (HDL), mediating many of its atheroprotective properties. Increasing data reveal the pro-atherogenic effects of bisphenol A (BPA), one of the most prevalent environmental chemicals. In this study, we investigated the mechanisms by which BPA exerts pro-atherogenic effects. For this, LDLR-/- mice were fed with a high-fat diet and treated with 50 µg BPA/kg body weight by gavage. After two months of treatment, the area of atherosclerotic lesions in the aorta, triglycerides and total cholesterol levels were significantly increased, while HDL-cholesterol was decreased in BPA-treated LDLR-/- mice as compared to control mice. Real-Time PCR data showed that BPA treatment decreased hepatic apoA-I expression. BPA downregulated the activity of the apoA-I promoter in a dose-dependent manner. This inhibitory effect was mediated by MEKK1/NF-κB signaling pathways. Transfection experiments using apoA-I promoter deletion mutants, chromatin immunoprecipitation, and protein-DNA interaction assays demonstrated that treatment of hepatocytes with BPA induced NF-κB signaling and thus the recruitment of p65/50 proteins to the multiple NF-κB binding sites located in the apoA-I promoter. In conclusion, BPA exerts pro-atherogenic effects downregulating apoA-I by MEKK1 signaling and NF-κB activation in hepatocytes.

Evaluation of single and combined effects of cadmium and micro-plastic particles on biochemical and immunological parameters of common carp (Cyprinus carpio)

The growing accumulation of microplastics (MPs) in aquatic environments is a global concern. MPs are capable to interact with other environmental contaminants, including heavy metals, altering their toxicity. The aim of the study was to investigate the sub-lethal effects of cadmium chloride (Cd) alone and in combination with MPs on common carp (Cyprinus carpio). Multi-biomarkers, including plasma biochemical parameters and intrinsic immunological factors, were measured after 30 days of exposure. Exposure to Cd or NPs reduced the plasma activities of acetylcholinesterase (AChE) and gamma-glutamyl-transferase (GGT) and increased aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH) and alkaline phosphatase (ALP). Exposure to both compounds enhanced the observed effects except for AST activity and ALP at the highest concentrations, whereas evidenced an antagonistic interaction in ALT. Plasma total protein, albumin, and globulin levels were decreased, and the levels of glucose, triglyceride, and cholesterol levels increased mainly in the Cd groups with no additional effects derived from the co-exposure to both stressors. Lysozyme and alternative complement (ACH50) activities and the levels of total immunoglobulins, and complement C3 and C4 in fish exposed to Cd and MPs were lower than those in the control group and this decrease was more significant by the mixture of both compounds. These findings showed that the exposure to Cd or MPs alone is toxic to fish altering the biochemical and immunological parameters. Moreover, these alterations are even greater when the Cd and the MPS are combined suggesting synergistic effects in increasing Cd toxicity and vice versa.

Bisphenol A-induced oxidative damage in the hepatic and cardiac tissues of rats: The modulatory role of sesame lignans

Bisphenol A (BPA) is an environmental pollutant that is widely produced throughout the world. It is primarily used in the manufacture of polycarbonate plastics, epoxy resins, paints and dental materials. BPA has been reported to promote hepatotoxicity and cardiotoxicity. The antioxidant activity of sesame lignans is well established. The current study assessed the protective efficiency of sesame lignans against BPA-induced hepatotoxicity and cardiotoxicity. Rats were divided into 4 groups: A control group, a BPA-treated group, a sesame lignans-treated group and a sesame lignans and BPA-treated group. Rats were orally administered their respective doses daily [30 mg/kg body weight (BW) BPA and/or 20 mg/kg BW sesame lignans] for 6 weeks. Liver function tests were performed using serum of all groups. Lipid profile and antioxidant status were also measured in liver tissue of the studied groups. The results were confirmed by histopathological examination of liver and heart tissues. The oral administration of BPA was revealed to elicit significant decreases in the activities of hepatic glutathione peroxidase, glutathione reductase, superoxide dismutase and glutathione. It also significantly increased levels of malondialdehyde. Furthermore, BPA-treatment resulted in lipid accumulation, elevated activities of alanine aminotransferase, creatine kinase MB and lactate dehydrogenase, and histological changes of liver and heart tissues. However, the co-administration of sesame lignans and BPA attenuated hepatotoxicity, cardiotoxicity and BPA-induced histological changes. The results of the current study indicated that sesame lignans may be helpful in the development of novel natural drugs to treat hepatic and cardiovascular disorders.