Role of Endocrine-Disrupting Chemicals in the Pathogenesis of Non-Alcoholic Fatty Liver Disease: A Comprehensive Review

Adipose tissue as target of environmental toxicants: focus on mitochondrial dysfunction and oxidative inflammation in metabolic dysfunction-associated steatotic liver disease

Obesity, diabetes, and their cardiovascular and hepatic comorbidities are alarming public health issues of the twenty-first century, which share mitochondrial dysfunction, oxidative stress, and chronic inflammation as common pathophysiological mechanisms. An increasing body of evidence links the combined exposure to multiple environmental toxicants with the occurrence and severity of metabolic diseases. Endocrine disruptors (EDs) are ubiquitous chemicals or mixtures with persistent deleterious effects on the living organisms beyond the endocrine system impairment; in particular, those known as metabolism-disrupting chemicals (MDCs), increase the risk of the metabolic pathologies in adult organism or its progeny. Being largely lipophilic, MDCs mainly target the adipose tissue and elicit mitochondrial dysfunction by interfering with mitochondrial bioenergetics, biogenesis, dynamics and/or other functions. Plastics, when broken down into micro- and nano-plastics (MNPs), have been detected in several human tissues, including the liver. The harmful interplay between inflammatory and redox processes, which mutually interact in a positive feed-back loop, hence the term oxidative inflammation ("OxInflammation"), occurs both at systemic and organ level. In both liver and adipose tissue, oxinflammation contributes to the progression of the metabolic dysfunction-associated steatotic liver disease (MASLD). Moreover, it has been reported that individuals with MASLD may be more susceptible to the harmful effects of toxicants (mainly, those related to mitochondria) and that chronic exposure to EDs/MDCs or MNPs may play a role in the development of the disease. While liver has been systematically investigated as major target organ for ambient chemicals, surprisingly, less information is available in the literature with respect to the adipose tissue. In this narrative review, we delve into the current literature on the most studied environmental toxicants (bisphenols, polychlorinated biphenyls, phthalates, tolylfluanid and tributyltin, per-fluoroalkyl and polyfluoroalkyl substances, heavy metals and MNPs), summarize their deleterious effects on adipose tissue, and address the role of dysregulated mitochondria and oxinflammation, particularly in the setting of MASLD.

In Vitro Investigation of Biological and Toxic Effects of 4-Octylphenol on Human Cells

Alkylphenols are byproducts of anthropogenic activities that widely contaminate waters, soils and air; among them, the most represented are 4-nonylphenol (4-NP) and 4-octylphenol (4-OP). These compounds tend to bioaccumulate in animal and plant tissues and also represent a risk to human health. Indeed, humans are constantly exposed to alkylphenols through ingestion of contaminated water and food, inhalation and dermal absorption. In the present work, we characterized the cytotoxic ability of 4-OP towards several human cell lines, representing the potential main targets in the human body, also comparing its effect with that of 4-NP and of a mixture of both 4-OP and 4-NP in a range of concentrations between 1 and 100 μM. Viability assays demonstrated that each cell type had a peculiar sensitivity to 4-OP and that, in some cases, a combination of the two alkylphenols displayed a higher cytotoxic activity with respect to the single compound. Then, we focused our attention on a liver cell line (HepG2) in which we observed that 4-OP increased cell death and also caused interference with protective physiological cell processes, such as the unfolded protein response, autophagy and the antioxidant response. Finally, our experimental data were compared and correlated with ADMET properties originating from an in silico analysis. Altogether, our findings highlight a possible contribution of this pollutant to deregulation of the normal homeostasis in human liver cells.

Mechanism of vitamin C alleviating the immunotoxicity of 17α-methyltestosterone in Carassius auratus

BACKGROUND

In recent years, the use of endocrine-disrupting chemicals (EDCs) has become increasingly common, leading to severe environmental pollution and harm to aquatic organisms. 17α-Methyltestosterone (MT) is a synthetic androgen that can cause immunotoxicity in aquaculture, affecting fish health. To address this issue, this study aimed to investigate the effect of Vitamin C (VC) on MT-induced immunotoxicity and determine the optimal VC supplementation.

RESULTS

Carassius auratus was exposed to 50 ng/L MT and treated with 25, 50, and 150 mg/kg VC for 7, 14, and 21 d. Morphological indicators, histological characteristics, hepatic antioxidant capacity, and immune-related gene expression were analyzed. Additionally, RNA-seq was performed on the liver tissues of the control, MT, and MT + 25 mg/kg VC groups after 21 d. Results showed that, MT treatment significantly increased liver malondialdehyde content and inhibited immune-related gene expression (TNF-α, IL-8, INF-γ, IL-10, Caspase-9, and IGF-I), causing oxidative stress and immunotoxicity, leading to hepatic steatosis. However, supplementation with 25-50 mg/kg VC effectively alleviated the MT-induced damage to the hepatic structure and immune system. RNA-seq revealed significant enrichment of differentially expressed genes in multiple signaling pathways, including the mTOR, MAPK, and Wnt pathways.

CONCLUSIONS

In summary, 25-50 mg/kg VC alleviated inhibitory effect of MT on immune-related genes in C. auratus liver, reducing MT-induced tissue damage. VC not only alleviated inflammation, oxidative stress, and immunotoxicity induced by MT through the regulation of the mTOR, MAPK, and Wnt signaling pathways, but also indirectly enhanced cellular antioxidant defense mechanisms by regulating the NRF2 pathway. This provides a theoretical basis for VC application in aquaculture, improving fish health and increasing efficiency.

Associations between per- and polyfluoroalkyl substance exposures and metabolic dysfunction associated steatotic liver disease (MASLD) in adult National Health and Nutrition Examination Survey 2017 to 2018

Per- and polyfluoroalkyl substances (PFAS) are persistent organic pollutants previously associated with elevated liver enzymes in human cohorts and steatotic liver disease in animal models. We aimed to evaluate the associations between PFAS exposures, and liver enzymes and vibration controlled transient elastography (VCTE) biomarkers of metabolic dysfunction associated steatotic liver disease (MASLD) in adult National Health and Nutrition Examination Survey (NHANES) 2017 to 2018. VCTE was determined by FibroScan. Serum PFAS (n = 14), measured by mass spectrometry, were analyzed individually and by principal component (PC). Univariate and multivariable associations were determined between PFAS exposures and liver disease outcome variables: alanine aminotransferase (ALT), controlled attenuation parameter (CAP), liver stiffness measurement (LSM), FibroScan-based Score (FAST), using R. About 1,400 participants including 50% women with a mean age of 48 ± 19 years and a mean BMI of 29 ± 7 kg/m2 were analyzed. Four PFAS clustered to PC1, whereas 3 PFAS clustered to PC2. PC1 was significantly associated with ALT (β = 0.028), CAP (β = 0.041), LSM (β = 0.025), and FAST (β = 0.198) in univariate analysis. Individual PFAS exposures were oftentimes inversely associated with these measurements in multivariate analysis. In adult NHANES 2017-2018, PFAS may not be a significant burden for MASLD, because of the inconsistent associations between the environmental PFAS exposures and biomarkers of liver steatosis, inflammation, and fibrosis. More data are required to better understand the relationships between PFAS exposures and liver disease.

Association Between Ultraprocessed Food Consumption and Metabolic Disorders in Children and Adolescents with Obesity

BACKGROUND/OBJECTIVES

We investigated the effects of ultraprocessed food (UPF) consumption on metabolic disorders (e.g., adiposity, metabolic associated steatotic liver disease [MASLD], and insulin resistance) in children and adolescents with obesity to improve dietary guidelines and public health strategies.

METHODS

The dietary intake of 149 participants (aged 8-17 years) was assessed with food diaries. The NOVA classification system was used to classify food according to the degree of processing. Metabolic outcomes, including the fat mass index (FMI), hepatic fat percentage, and insulin resistance, were measured via dual-energy X-ray absorptiometry (DXA), magnetic resonance imaging proton density fat fraction (MRI-PDFF), and biochemical analysis, respectively.

RESULTS

Greater UPF consumption from baseline to the 6-month follow-up was significantly associated with increased insulin and decreased total cholesterol and LDL-cholesterol. UPF consumption was positively associated with the prevalence of MASLD (liver MRI-PDFF ≥ 5%; odds ratio T3 vs. T1 = 1.75; 95% confidence interval [CI] 1.03, 3.00), moderate-to-severe MASLD (liver MRI-PDFF ≥ 10%; OR T3 vs. T1 = 4.19; 95% CI 1.72, 10.22), and insulin resistance (OR T3 vs. T1 = 2.44; 95% CI 1.33, 4.48), after adjusting for covariates. A linear dose-response relationship was observed between UPF consumption and the odds of moderate-to-severe MASLD and insulin resistance.

CONCLUSIONS

Greater UPF consumption was strongly associated with MASLD and insulin resistance in children and adolescents with obesity, underscoring the importance of reducing UPF consumption through dietary guidelines and public health interventions to mitigate the risk of obesity-related metabolic conditions in young populations.

Effects of Perfluorinated Alkyl Substances (PFAS) on Amphibian Body and Liver Conditions: Is Lipid Metabolism Being Perturbed throughout Metamorphosis?

Per- and polyfluoroalkyl substances (PFAS) may interact with peroxisome proliferator activated receptors (PPARs) and alter lipid homeostasis. Using Xenopus laevis, we investigated the effect of PFAS on (a) lipid homeostasis and whether this correlated to changes in body and hepatic condition; (b) the expression of hepatic genes regulated by PPAR; and (c) the hepatic lipidome. We chronically exposed tadpoles to 0.5 µg/L of either PFOS, PFHxS, PFOA, PFHxA, a binary mixture of PFOS and PFHxS (0.5 µg/L of each), or a control, from NF stage 52 through metamorphic climax. Growth, development, and survival were not affected, but we detected a sex-specific decrease in body condition at NF 66 (6.8%) and in hepatic condition (16.6%) across metamorphic climax for male tadpoles exposed to PFOS. We observed weak evidence for the transient downregulation of apolipoprotein-V (apoa5) at NF 62 in tadpoles exposed to PFHxA. Acyl-CoA oxidase 1 (acox1) was downregulated only in males exposed to PFHxS (Ln(Fold Change) = -0.54). We detected PFAS-specific downregulation of structural glycerophospholipids, while semi-quantitative profiling detected the upregulation in numerous glycerophospholipids, sphingomyelins, and diglycerides. Overall, our findings indicate that PFAS can induce sex-specific effects that change across larval development and metamorphosis. We demonstrate that PFAS alter lipid metabolism at environmentally relevant concentrations through divergent mechanisms that may not be related to PPARs, with an absence of effects on body condition, demonstrating the need for more molecular studies to elucidate mechanisms of PFAS-induced lipid dysregulation in amphibians and in other taxa.

Metabolic disrupting chemicals in the intestine: the need for biologically relevant models: Zebrafish: what can we learn from this small environment-sensitive fish?

Although the concept of endocrine disruptors first appeared almost 30 years ago, the relatively recent involvement of these substances in the etiology of metabolic pathologies (obesity, diabetes, hepatic steatosis, etc.) has given rise to the concept of Metabolic Disrupting Chemicals (MDCs). Organs such as the liver and adipose tissue have been well studied in the context of metabolic disruption by these substances. The intestine, however, has been relatively unexplored despite its close link with these organs. In vivo models are useful for the study of the effects of MDCs in the intestine and, in addition, allow investigations into interactions with the rest of the organism. In the latter respect, the zebrafish is an animal model which is used increasingly for the characterization of endocrine disruptors and its use as a model for assessing effects on the intestine will, no doubt, expand. This review aims to highlight the importance of the intestine in metabolism and present the zebrafish as a relevant alternative model for investigating the effect of pollutants in the intestine by focusing, in particular, on cytochrome P450 3A (CYP3A), one of the major molecular players in endogenous and MDCs metabolism in the gut.

Associations of exposure to bisphenol-A or parabens with markers of liver injury/function among US adults in NHANES 2011-2016

BACKGROUND

Bisphenol-A (BPA) and parabens are common endocrine-disrupting compounds (EDCs) that are used extensively in consumer products worldwide and are widely found in the environment.

OBJECTIVE

The purpose of this study was to comprehensively explore the correlations between urinary BPA/parabens levels and liver injury/function markers.

METHODS

In this cross-sectional study, we used National Health and Nutrition Examination Survey (NHANES) data from 2011 to 2016. The exposure variables were urinary BPA and four urinary parabens [methylparaben (MPB), ethylparaben (EPB), propylparaben (PPB), and butylparaben (BPB)], while the outcome variables were indicators of liver function/injury [alanine aminotransferase (ALT), aspartate aminotransferase (AST), AST/ ALT, albumin (ALB), total protein (TP), total bilirubin (TBIL), alkaline phosphatase (ALP), and the fibrosis-4 index (FIB-4)]. Multiple linear regression and weighted quantile sum (WQS) regression analyses were applied to explore the relationships between the individual/combined exposure variables and the liver injury/function indicators, respectively. Furthermore, stratified analysis was employed to detect the associations influenced by age and sex.

RESULTS

A total of 2,179 adults were eligible for the present analysis. Multivariate linear regression analysis revealed positive associations of EPB with AST, ALT, TP, and FIB-4 scores and negative associations of BPA with TP and ALB. The effects of urinary parabens on adverse outcomes in the liver (AST and ALT) were significant in the female and middle-aged subgroups. In addition, the WQS analysis revealed that the mixture of four compounds was negatively associated with ALB. BPA had the greatest effect on the serum ALB concentration (weight = 0.688).

IMPACT

Our present study provided novel evidence of significant associations between BPA or certain parabens and numerous markers of liver injury/function indicators. We found that higher urinary BPA concentrations were associated with worse liver function. Exposure to high EPB/PPB ratios was significantly associated with biomarkers of liver injury.

PFHpA alters lipid metabolism and increases the risk of metabolic dysfunction-associated steatotic liver disease in youth-a translational research framework

To address the growing epidemic of liver disease, particularly in pediatric populations, it is crucial to identify modifiable risk factors for the development and progression of metabolic dysfunction-associated steatotic liver disease (MASLD). Per- and polyfluoroalkyl substances (PFAS) are persistent ubiquitous chemicals and have emerged as potential risk factors for liver damage. However, their impact on the etiology and severity of MASLD remains largely unexplored in humans. This study aims to bridge the gap between human and in vitro studies to understand how exposure to perfluoroheptanoic acid (PFHpA), one of the emerging PFAS replacements which accumulates in high concentrations in the liver, contributes to MASLD risk and progression. First, we showed that PFHpA plasma concentrations were significantly associated with increased risk of MASLD in obese adolescents. Further, we examined the impact of PFHpA on hepatic metabolism using 3D human liver spheroids and single-cell transcriptomics to identify major hepatic pathways affected by PFHpA. Next, we integrated the in vivo and in vitro multi-omics datasets with a novel statistical approach which identified signatures of proteins and metabolites associated with MASLD development triggered by PFHpA exposure. In addition to characterizing the contribution of PFHpA to MASLD progression, our study provides a novel strategy to identify individuals at high risk of PFHpA-induced MASLD and develop early intervention strategies. Notably, our analysis revealed that the proteomic signature exhibited a stronger correlation between both PFHpA exposure and MASLD risk compared to the metabolomic signature. While establishing a clear connection between PFHpA exposure and MASLD progression in humans, our study delved into the molecular mechanisms through which PFHpA disrupts liver metabolism. Our in vitro findings revealed that PFHpA primarily impacts lipid metabolism, leading to a notable increase of lipid accumulation in human hepatocytes after PFHpA exposure. Among the pathways involved in lipid metabolism in hepatocytes, regulation of lipid metabolism by PPAR-a showed a remarkable activation. Moreover, the translational research framework we developed by integrating human and in vitro data provided us biomarkers to identify individuals at a high risk of MASLD due to PFHpA exposure. Our framework can inform policies on PFAS-induced liver disease and identify potential targets for prevention and treatment strategies.

Safety and efficacy of resmetirom in the treatment of patients with non-alcoholic steatohepatitis and liver fibrosis: a systematic review and meta-analysis

Introduction

Non-alcoholic fatty liver disease (NAFLD), spanning from non-alcoholic steatohepatitis (NASH) to liver fibrosis, poses a global health challenge amid rising obesity and metabolic syndrome rates. Effective pharmacological treatments for NASH and liver fibrosis are limited.

Objective

This study systematically reviews and meta-analyzes the safety and efficacy of resmetirom, a selective thyroid hormone receptor-β agonist, in NASH and liver fibrosis treatment. By analyzing data from clinical trials, we aim to offer evidence-based recommendations for resmetirom's use in managing these conditions and identify avenues for future research.

Methods

Electronic databases (PubMed, Scopus, Science Direct, Google Scholar, ClinicalTrials.gov, and Cochrane CENTRAL) were systematically searched, supplemented by manual screening of relevant sources. Only English-language randomized controlled trials were included. Data extraction, risk of bias assessment, pooled analyses, and meta-regression were performed.

Results

Three randomized controlled trials involving 2231 participants were analyzed. Resmetirom demonstrated significant reductions in hepatic fat fraction [standardized mean difference (SMD) -4.61, 95% CI -6.77 to -2.44, P < 0.0001], NASH resolution without worsening fibrosis [risk ratio (RR) 2.51, 95% CI 1.74-3.64, P = 0.00001), and liver fibrosis improvement (RR 2.31, 95% CI 1.20-4.44, P = 0.01). Secondary outcomes showed significant improvements in lipid profiles, liver enzymes, and NASH biomarkers with resmetirom treatment. Meta-regression revealed associations between covariates and primary outcomes.

Conclusion

Resmetirom exhibits promising efficacy in reducing hepatic fat, improving NASH resolution, and ameliorating liver fibrosis with a favorable safety profile. Further research is warranted to validate findings and optimize therapeutic strategies for NASH and liver fibrosis management.

Association between endocrine-disrupting chemical mixtures and non-alcoholic fatty liver disease with metabolic syndrome as a mediator among adults: A population-based study in Korea

Endocrine-disrupting chemicals (EDCs) may play a role in non-alcoholic fatty liver disease (NAFLD); however, studies on the combined effects of EDC mixtures on NAFLD development are limited. Here, we explored the association between exposure to EDC mixtures and NAFLD and investigated the potential mediating role of metabolic syndrome (MetS). We included participants from the Korean National Environmental Health Survey Cycle 4 (2018-2020) and quantified the urinary concentrations of various EDCs-eight phthalate metabolites, three phenols, one antibacterial compound, four parabens, four polycyclic aromatic hydrocarbons, and one pyrethroid pesticide metabolite-as well as serum concentrations of five perfluorinated compounds (PFCs). NAFLD was defined as a hepatic steatosis index (HSI) ≥36 or a fatty liver index (FLI) ≥60. Weighted quantile sum (WQS) regression was employed to evaluate the associations between EDC mixtures and the risk of MetS or NAFLD. Causal mediation analysis was conducted to explore the potential mediating effect of MetS on the association between mixtures of EDCs and NAFLD risk. All estimates were adjusted for age, sex, educational level, physical activity, smoking status, involuntary smoking, and drinking habits. A total of 2942 adults were included in the analysis. Moderate-to-high positive correlations were identified between phthalate metabolites and PFCs. Higher WQS scores were associated with an elevated risk of MetS and NAFLD. The sex-stratified WQS regression model showed that the interactions between the WQS index and sex were significant for MetS and NAFLD. According to the causal mediation analysis, both the direct and indirect effects of EDC mixtures on NAFLD, with MetS as a mediator, were significant in females. Collectively, these findings highlight the need for interventions that could address both EDC mixture exposure and metabolic status to effectively reduce the risks associated with NAFLD and its related complications.

Multi-omics approach characterizes the role of Bisphenol F in disrupting hepatic lipid metabolism

Bisphenol F (BPF), a substitute for bisphenol A (BPA), is ubiquitous existed in various environmental media. Exposure to BPF may promote non-alcoholic fatty liver disease (NAFLD), while the potential mechanism is still unknown. In current study, we used in vitro and in vivo model to evaluate its hepatotoxicity and molecular mechanism. Using multi-omics approach, we found that BPF exposure led to changes in hepatic transcriptome, metabolome and chromatin accessible regions that were enriched for binding sites of transcription factors in bZIP family. These alterations were enriched with pathways integral to the endoplasmic reticulum stress and NAFLD. These findings suggested that BPF exposure might reprogram the chromatin accessibility and enhancer landscape in the liver, with downstream effects on genes associated with endoplasmic reticulum stress and lipid metabolism, which relied on bZIP family transcription factors. Overall, our study describes comprehensive molecular alterations in hepatocytes after BPF exposure and provides new insights into the understanding of the hepatoxicity of BPF.

Pesticides impacts on human health and the environment with their mechanisms of action and possible countermeasures

Pesticides are chemical constituents used to prevent or control pests, including insects, rodents, fungi, weeds, and other unwanted organisms. Despite their advantages in crop production and disease management, the use of pesticides poses significant hazards to the environment and public health. Pesticide elements have now perpetually entered our atmosphere and subsequently contaminated water, food, and soil, leading to health threats ranging from acute to chronic toxicities. Pesticides can cause acute toxicity if a high dose is inhaled, ingested, or comes into contact with the skin or eyes, while prolonged or recurrent exposure to pesticides leads to chronic toxicity. Pesticides produce different types of toxicity, for instance, neurotoxicity, mutagenicity, carcinogenicity, teratogenicity, and endocrine disruption. The toxicity of a pesticide formulation may depend on the specific active ingredient and the presence of synergistic or inert compounds that can enhance or modify its toxicity. Safety concerns are the need of the hour to control contemporary pesticide-induced health hazards. The effectiveness and implementation of the current legislature in providing ample protection for human health and the environment are key concerns. This review explored a comprehensive summary of pesticides regarding their updated impacts on human health and advanced safety concerns with legislation. Implementing regulations, proper training, and education can help mitigate the negative impacts of pesticide use and promote safer and more sustainable agricultural practices.

The Interplay between Endocrine-Disrupting Chemicals and the Epigenome towards Metabolic Dysfunction-Associated Steatotic Liver Disease: A Comprehensive Review

Metabolic dysfunction-associated steatotic liver disease (MASLD), described as the most prominent cause of chronic liver disease worldwide, has emerged as a significant public health issue, posing a considerable challenge for most countries. Endocrine-disrupting chemicals (EDCs), commonly found in daily use items and foods, are able to interfere with nuclear receptors (NRs) and disturb hormonal signaling and mitochondrial function, leading, among other metabolic disorders, to MASLD. EDCs have also been proposed to cause transgenerationally inherited alterations leading to increased disease susceptibility. In this review, we are focusing on the most prominent linking pathways between EDCs and MASLD, their role in the induction of epigenetic transgenerational inheritance of the disease as well as up-to-date practices aimed at reducing their impact.

Association between serum perfluoroalkyl substances concentrations and non-alcoholic fatty liver disease among Korean adults: a cross-sectional study using the National Environmental Health Survey cycle 4

Background

Perfluoroalkyl substances (PFAS) are widely used in industry and daily life due to their useful properties. They have a long half-life, accumulate in the body, and there is evidence that they are associated with biomarkers of lipid metabolism and liver damage. This may suggest non-alcoholic fatty liver disease (NAFLD) caused by PFAS. However, since there has been no study analyzing the relationship between PFAS and NAFLD in the entire population in Korea. We sought to confirm the relationship between serum PFAS concentration and NAFLD prevalence in Korean adults using the Korean National Environmental Health Survey (KoNEHS) cycle 4.

Methods

The study was conducted on 2,529 subjects in 2018-2019 among KoNEHS participants. For the diagnosis of NAFLD, the hepatic steatosis index (HSI) was used, and the geometric mean and concentration distribution of serum PFAS were presented. Logistic regression was performed to confirm the increase in the risk of NAFLD due to changes in PFAS concentration, and the odds ratio and 95% confidence interval (CI) were calculated.

Results

In both adjusted and unadjusted models, an increased odds ratio was observed with increasing serum concentrations of total PFAS and perfluorooctane sulfonate (PFOS) in the non-obese group. In the adjusted model, the odds ratios for serum total PFAS and PFOS were 6.401 (95% CI: 1.883-21.758) and 7.018 (95% CI: 2.688-18.319).

Conclusions

In this study, a higher risk of NAFLD based on HSI was associated with serum total PFAS, PFOS in non-obese group. Further research based on radiological or histological evidence for NAFLD diagnosis and long-term prospective studies are necessary. Accordingly, it is necessary to find ways to reduce exposure to PFAS in industry and daily life.

Analysis and remediation of phthalates in aquatic matrices: current perspectives

Phthalic acid esters (PAEs) are high production volume chemicals used extensively as plasticizers, to increase the flexibility of the main polymer. They are reported to leach into their surroundings from plastic products and are now a ubiquitous environmental contaminant. Phthalate levels have been determined in several environmental matrices, especially in water. These levels serve as an indicator of plasticizer abuse and plastic pollution, and also serve as a route of exposure to different species including humans. Reports published on effects of different PAEs on experimental models demonstrate their carcinogenic, teratogenic, reproductive, and endocrine disruptive effects. Therefore, regular monitoring and remediation of environmental water samples is essential to ascertain their hazard quotient and daily exposure levels. This review summarises the extraction and detection techniques available for phthalate analysis in water samples such as chromatography, biosensors, immunoassays, and spectroscopy. Current remediation strategies for phthalate removal such as adsorption, advanced oxidation, and microbial degradation have also been highlighted.

Toxicological Effects of Naturally Occurring Endocrine Disruptors on Various Human Health Targets: A Rapid Review

Endocrine-disrupting compounds are chemicals that alter the normal functioning of the endocrine system of living organisms. They can be natural (N-EDCs) or synthetic compounds (S-EDCs). N-EDCs can belong to different groups, such as phytoestrogens (PEs), including flavonoids, or mycotoxins originating from plants or fungi, and cyanotoxins, derived from bacteria. Humans encounter these substances in their daily lives. The aim of this rapid review (RR) is to provide a fine mapping of N-EDCs and their toxicological effects on human health in terms of various medical conditions or adverse consequences. This work is based on an extensive literature search and follows a rigorous step-by-step approach (search strategy, analysis strategy and data extraction), to select eligible papers published between 2019 and 2023 in the PubMed database, and to define a set of aspects characterizing N-EDCs and the different human target systems. Of the N-EDCs identified in this RR, flavonoids are the most representative class. Male and female reproductive systems were the targets most affected by N-EDCs, followed by the endocrine, nervous, bone and cardiovascular systems. In addition, the perinatal, pubertal and pregnancy periods were found to be particularly susceptible to natural endocrine disruptors. Considering their current daily use, more toxicological research on N-EDCs is required.

Environment, Endocrine Disruptors, and Fatty Liver Disease Associated with Metabolic Dysfunction (MASLD)

Ecological theories suggest that environmental factors significantly influence obesity risk and related syndemic morbidities, including metabolically abnormal obesity associated with nonalcoholic fatty liver disease (MASLD). These factors encompass anthropogenic influences and endocrine-disrupting chemicals (EDCs), synergistically interacting to induce metabolic discrepancies, notably in early life, and disrupt metabolic processes in adulthood. This review focuses on endocrine disruptors affecting a child's MASLD risk, independent of their role as obesogens and thus regardless of their impact on adipogenesis. The liver plays a pivotal role in metabolic and detoxification processes, where various lipophilic endocrine-disrupting molecules accumulate in fatty liver parenchyma, exacerbating inflammation and functioning as new anthropogenics that perpetuate chronic low-grade inflammation, especially insulin resistance, crucial in the pathogenesis of MASLD.

The brominated flame retardant tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether) as well as hexabromocyclododecane lead to lipid disorders in mice

The brominated flame retardant tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl ether) (TBBPA-DBMPE) is a recommended substitute for hexabromocyclododecane (HBCD), a banned persistent organic pollutant, yet its potential toxicities remains largely unexplored. Here, we investigated the effects of a long-term exposure to TBBPA-DBMPE at nominal doses of 50 and 1000 μg/kg/d on lipid homeostasis in CD-1 mice, in comparison with 50 μg/kg/d HBCD as a positive control. Male pups received chemical treatments through maternal administration via drinking water from postnatal day 0-21, followed by direct administration through drinking water after weaning. On the 23rd week after treatment, the oral lipid tolerance test revealed that low-dose TBBPA-DBMPE as well as HBCD affected lipid tolerance, although the fasting serum triglyceride (TG) levels were not altered. When chemical treatment was extended to the 32nd week, TBBPA-DBMPE-treated animals displayed adipocyte hypertrophy in both white adipose tissue (eWAT) and brown adipose tissue (BAT) and hepatic steatosis, which was largely consistent with the effects of HBCD. These findings indicate that like HBCD, TBBPA-DBMPE led to increased lipid load in mice. Interestingly, we also observed intestinal histological changes, coupled with increased expression of lipid absorption-related genes in both HBCD and TBBPA-DBMPE treatments, suggesting increased lipid absorption. This was supported by in vitro findings that both HBCD and TBBPA-DBMPE promoted lipid accumulation in IEC-6 cells under the stress of oleic acid for 6 h, implying that altered lipid absorption by the intestine may partly contributed to increased lipid load in mice. Overall, the effects of 50 μg/kg/d TBBPA-DBMPE in terms of some parameters were comparable with 50 μg/kg/d HBCD, suggesting that TBBPA-DBMPE may not be an ideal substitute of HBCD.

Ultra-processed food consumption and non-alcoholic fatty liver disease, metabolic syndrome and insulin resistance: A systematic review

Background

High ultra-processed food (UPF) consumption is associated with the development of various diet-related non-communicable diseases, especially obesity and type 2 diabetes. The present study aimed to systematically review the association between UPF consumption and non-alcoholic fatty liver disease (NAFLD) and its leading risk factors; metabolic syndrome (MetS) and insulin resistance (IR).

Methods

A comprehensive search was conducted in PubMed, Scopus, Embase, Web of Science, CINAHL, and Cochrane (March 2023), and references of the identified articles were checked. The search keywords were defined through an exploratory investigation in addition to MeSH and similarly controlled vocabulary thesauruses. Observational and interventional studies were included. Studies that focused only on specific groups of processed foods or overlapping dietary patterns were excluded. The quality assessment was conducted using the Joanna Briggs Institute's critical appraisal tools for observational studies and Cochrane's risk of bias 2 tool for randomized-control trials. A narrative synthesis was employed to report the results.

Results

Fifteen studies were included, with a total of 52,885 participants, one randomized-controlled trial, and fourteen observational studies (nine cross-sectional and five prospective). The review has shown a significant association between UPF consumption and NAFLD in three studies out of six, MetS in five out of eight, and IR in one out of three. All large-scale prospective cohorts that studied NAFLD or MetS outcomes demonstrated a positive association. In contrast, studies that did not demonstrate significant associations were mostly cross-sectional and small. The evidence for an association with IR was insufficient and conflicting.

Conclusion

The included studies are few, observational, and based upon self-reported dietary assessment tools. However, current evidence indicates that UPF is not only associated with obesity and type 2 diabetes but may also be a risk factor for NAFLD and MetS. UPF is a worldwide concern deserving further longitudinal research.

Impact and implications

Overconsumption of ultra-processed food (UPF) may lead to the development of obesity and type 2 diabetes, but the association with non-alcoholic fatty liver disease (NAFLD) is not well established. The present systematic review shows that UPF may be associated with NAFLD, although more large prospective studies are needed. These findings emphasize the importance of minimizing the consumption of UPF to prevent NAFLD and other metabolic diseases among the general adult population. This systematic review and further prospective studies, epidemiological or interventional, can help physicians provide patients with evidence-based nutritional recommendations and will support policymakers in restricting the marketing of UPF as well as promoting affordable, healthy, and minimally processed foods.

Toxic ties: Unraveling the complex relationship between endocrine disrupting chemicals and chronic kidney disease

Environmental pollution is inherently linked to several metabolic diseases and high mortality. The kidney is more susceptible to environmental pollutants compared to other organs as it is involved in concentrating and filtering most of these toxins. Few epidemiological studies revealed the intrinsic relationship between exposure to Endocrine Disrupting Chemicals (EDCs) and CKD development. Though EDCs have the potential to cause severe pathologies, the specific molecular mechanisms by which they accelerate the progression of CKD remain elusive. In particular, our understanding of how pollutants affect the progression of chronic kidney disease (CKD) through the gut-kidney axis is currently limited. EDCs modulate the composition and function of the gut microbial community and favor the colonization of harmful gut pathogens. This alteration leads to an overproduction of uremic toxin and membrane vesicles. These vesicles carry several inflammatory molecules that exacerbate inflammation and renal tissue damage and aggravate the progression of CKD. Several experimental studies have revealed potential pathways by which uremic toxin further aggravates CKD. These include the induction of membrane vesicle production in host cells, which can trigger inflammatory pathways and insulin resistance. Reciprocally, CKD can also modulate gut bacterial composition that might further aggravate CKD condition. Thus, EDCs pose a significant threat to kidney health and the global CKD burden. Understanding this complicated issue necessitates multidisciplinary initiatives such as strict environmental controls, public awareness, and the development of novel therapeutic strategies targeting EDCs.

How single-cell transcriptomics provides insight on hepatic responses to TCDD

The prototypical aryl hydrocarbon receptor (AHR) ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), has been a valuable model for investigating toxicant-associated fatty liver disease (TAFLD). TCDD induces dose-dependent hepatic lipid accumulation, followed by the development of inflammatory foci and eventual progression to fibrosis in mice. Previously, bulk approaches and in vitro examination of different cell types were relied upon to study the mechanisms underlying TCDD-induced liver pathologies. However, the advent of single-cell transcriptomic technologies, such as single-nuclei RNA sequencing (snRNAseq) and spatial transcriptomics (STx), has provided new insights into the responses of hepatic cell types to TCDD exposure. This review explores the application of these single-cell transcriptomic technologies and highlights their contributions towards unraveling the cell-specific mechanisms mediating the hepatic responses to TCDD.

The Role of Epigenetic Control of Mitochondrial (Dys)Function in MASLD Onset and Progression

Metabolic dysfunction-associated steatotic fatty liver disease (MASLD), a novel definition for NAFLD, represents one of the most common causes of liver disease, and its incidence is increasing worldwide. It is characterized by a complex etiopathogenesis in which mitochondrial dysfunction exerts a pivotal role together with alteration of lipid metabolism, inflammation, and oxidative stress. Nutrients and bioactive compounds can influence such mechanisms so that changes in diet and lifestyle are regarded as important treatment strategies. Notably, natural compounds can exert their influence through changes of the epigenetic landscape, overall resulting in rewiring of molecular networks involved in cell and tissue homeostasis. Considering such information, the present review aims at providing evidence of epigenetic modifications occurring at mitochondria in response to natural and bioactive compounds in the context of liver (dys)function. For this purpose, recent studies reporting effects of compounds on mitochondria in the context of NAFLD/MASLD, as well as research showing alteration of DNA methylation and non-coding RNAs-related circuits occurring at liver mitochondria, will be illustrated. Overall, the present review will highlight the importance of understanding the bioactive compounds-dependent epigenetic modulation of mitochondria for improving the knowledge of MASLD and identifying biomarkers to be employed for effective preventative strategies or treatment protocols.

Preconception and developmental DEHP exposure alter liver metabolism in a sex-dependent manner in adult mouse offspring

Environmental exposure to endocrine disrupting chemicals (EDCs) during critical periods of development is associated with an increased risk of metabolic diseases, including hepatic steatosis and obesity. Di-2-ethylhexyl-phthalate (DEHP) is an EDC strongly associated with these metabolic abnormalities. DEHP developmental windows of susceptibility are unknown yet have important public health implications. The purpose of this study was to identify these windows of susceptibility and determine whether developmental DEHP exposure alters hepatic metabolism later in life. Dams were exposed to control or feed containing human exposure relevant doses of DEHP (50 μg/kg BW/d) and high dose DEHP (10 mg/kg BW/d) from preconception until weaning or only exposed to DEHP during preconception. Post-weaning, all offspring were fed a control diet throughout adulthood. Using the Metabolon Untargeted Metabolomics platform, we identified 148 significant metabolites in female adult livers that were altered by preconception-gestation-lactation DEHP exposure. We found a significant increase in the levels of acylcarnitines, diacylglycerols, sphingolipids, glutathione, purines, and pyrimidines in DEHP-exposed female livers compared to controls. These changes in fatty acid oxidation and oxidative stress-related metabolites were correlated with hepatic changes including microvesicular steatosis, hepatocyte swelling, inflammation. In contrast to females, we observed fewer metabolic alterations in male offspring, which were uniquely found in preconception-only low dose DEHP exposure group. Although we found that preconception-gestational-lactation exposure causes the most liver pathology, we surprisingly found preconception exposure linked to an abnormal liver metabolome. We also found that two doses exhibited non-monotonic DEHP-induced changes in the liver. Collectively, these findings suggest that metabolic changes in the adult liver of offspring exposed periconceptionally to DHEP depends on the timing of exposure, dose, and sex.

Association of volatile methylsiloxanes exposure with non-alcoholic fatty liver disease among Chinese adults

Owing to the wide use of volatile methylsiloxanes (VMSs) in various industries and consumer products, both cyclic VMSs (cVMS) and linear VMSs (lVMS) have been detected in human plasma. Experimental studies suggest that exposure to cVMSs may induce liver disease. Whereas, there is no human evidence of the potential health effects of VMSs yet. In this cross-sectional study, we evaluated the association of plasma VMSs concentrations with liver enzymes and Nonalcoholic fatty liver disease (NAFLD) among adults located in southwestern China. We used the fibrosis 4 calculator (FIB-4) as the NAFLD index and defined FIB-4≥1.45 as the NAFLD case. Among 372 participants, 45 (12.1%) of them were classified as NAFLD. Positive associations of plasma cVMSs concentrations with liver enzymes and NAFLD were observed among all participants. With per doubling increase in the total cVMSs, we observed a 1.40 (95%CI: 0.31, 2.48) increase in Alanine aminotransferase (ALT), a 1.56 (95%CI: 0.52, 2.61) increase in aspartate aminotransferase (AST) and a 0.04 (0.00, 0.09) increase in NAFLD index. A 19% increased risk of NAFLD was also found to be associated with per doubling increase in total cVMSs. In addition, positive associations of total lVMSs with ALT, AST and NAFLD were also detected when restricting our analyses to 230 participants living in industrial areas. Our study first provides epidemiological evidence on the association between VMSs and liver health, indicating more careful usage of VMSs may potentially reduce the burden of NAFLD, though more well-designed cohort studies are needed to confirm these findings.

RISING STARS: Sex differences in toxicant-associated fatty liver disease

Based on biological sex, the consequential health outcomes from exposures to environmental chemicals or toxicants can differ in disease pathophysiology, progression, and severity. Due to basal differences in cellular and molecular processes resulting from sexual dimorphism of organs including the liver and additional factors influencing 'gene-environment' interactions, males and females can exhibit different responses to toxicant exposures. Associations between environmental/occupational chemical exposures and fatty liver disease (FLD) have been well-acknowledged in human epidemiologic studies and their causal relationships demonstrated in experimental models. However, studies related to sex differences in liver toxicology are still limited to draw any inferences on sex-dependent chemical toxicity. The purpose of this review is to highlight the present state of knowledge on the existence of sex differences in toxicant-associated FLD (TAFLD), discuss potential underlying mechanisms driving these differences, implications of said differences on disease susceptibility, and emerging concepts. Chemicals of interest include various categories of pollutants that have been investigated in TAFLD, namely persistent organic pollutants, volatile organic compounds, and metals. Insight into research areas requiring further development is also discussed, with the objective of narrowing the knowledge gap on sex differences in environmental liver diseases. Major conclusions from this review exercise are that biological sex influences TAFLD risks, in part due to (i) toxicant disruption of growth hormone and estrogen receptor signaling, (ii) basal sex differences in energy mobilization and storage, and (iii) differences in chemical metabolism and subsequent body burden. Finally, further sex-dependent toxicological assessments are warranted for the development of sex-specific intervention strategies.

Chronic Exposure to Chlorpyrifos Damages Thyroid Activity and Imbalances Hepatic Thyroid Hormones Signaling and Glucose Metabolism: Dependency of T3-FOXO1 Axis by Hyperglycemia

Early life exposure to Endocrine Disruptor Chemicals (EDCs), such as the organophosphate pesticide Chlorpyrifos (CPF), affects the thyroid activity and dependent process, including the glucose metabolism. The damage of thyroid hormones (THs) as a mechanism of action of CPF is underestimated because the studies rarely consider that TH levels and signaling are customized peripherally. Here, we investigated the impairment of metabolism/signaling of THs and lipid/glucose metabolism in the livers of 6-month-old mice, developmentally and lifelong exposed to 0.1, 1, and 10 mg/kg/die CPF (F1) and their offspring similarly exposed (F2), analyzing the levels of transcripts of the enzymes involved in the metabolism of T3 (Dio1), lipids (Fasn, Acc1), and glucose (G6pase, Pck1). Both processes were altered only in F2 males, affected by hypothyroidism and by a systemic hyperglycemia linked to the activation of gluconeogenesis in mice exposed to 1 and 10 mg/kg/die CPF. Interestingly, we observed an increase in active FOXO1 protein due to a decrease in AKT phosphorylation, despite insulin signaling activation. Experiments in vitro revealed that chronic exposure to CPF affected glucose metabolism via the direct modulation of FOXO1 activity and T3 levels in hepatic cells. In conclusion, we described different sex and intergenerational effects of CPF exposure on the hepatic homeostasis of THs, their signaling, and, finally, glucose metabolism. The data points to FOXO1-T3-glucose signaling as a target of CPF in liver.

The health risk of acetochlor metabolite CMEPA is associated with lipid accumulation induced liver injury

Liver injury may cause many diseases, such as non-alcoholic fatty liver disease (NAFLD). Acetochlor is one of the representative chloroacetamide herbicides, and its metabolite 2-chloro-N-(2-ethyl-6-methyl phenyl) acetamide (CMEPA) is the main form of exposure in the environment. It has been shown that acetochlor can cause mitochondrial damage of HepG2 cells and induce apoptosis by activating Bcl/Bax pathway (Wang et al., 2021). But there has been less research on CMEPA. we explored the possibility of CMEPA and liver injury through biological experiments. In vivo, CMEPA (0-16 mg/L) induced liver damage in zebrafish larvae, including increased lipid droplets, changes in liver morphology (>1.3-fold) and increased TC/TG content (>2.5-fold). In vitro, we selected L02 (human normal liver cells) as the model, and explored its molecular mechanism. We found that CMEPA (0-160 mg/L) induced apoptosis (similar to 40%), mitochondrial damage and oxidative stress in L02 cells. CMEPA induced intracellular lipid accumulation by inhibiting AMPK/ACC/CPT-1A signaling pathway and activating SREBP-1c/FAS signaling pathway. Our study provides evidence of a link between CMEPA and liver injury. This raises concerns regarding the health risks of pesticide metabolites to liver health.

Sex, Nutrition, and NAFLD: Relevance of Environmental Pollution

Non-alcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease and represents an increasing public health issue given the limited treatment options and its association with several other metabolic and inflammatory disorders. The epidemic, still growing prevalence of NAFLD worldwide cannot be merely explained by changes in diet and lifestyle that occurred in the last few decades, nor from their association with genetic and epigenetic risk factors. It is conceivable that environmental pollutants, which act as endocrine and metabolic disruptors, may contribute to the spreading of this pathology due to their ability to enter the food chain and be ingested through contaminated food and water. Given the strict interplay between nutrients and the regulation of hepatic metabolism and reproductive functions in females, pollutant-induced metabolic dysfunctions may be of particular relevance for the female liver, dampening sex differences in NAFLD prevalence. Dietary intake of environmental pollutants can be particularly detrimental during gestation, when endocrine-disrupting chemicals may interfere with the programming of liver metabolism, accounting for the developmental origin of NAFLD in offspring. This review summarizes cause-effect evidence between environmental pollutants and increased incidence of NAFLD and emphasizes the need for further studies in this field.

A review on structural mechanisms of protein-persistent organic pollutant (POP) interactions

With the advent of the industrial revolution, the accumulation of persistent organic pollutants (POPs) in the environment has become ubiquitous. POPs are halogen-containing organic molecules that accumulate, and remain in the environment for a long time, thus causing toxic effects in living organisms. POPs exhibit a high affinity towards biological macromolecules such as nucleic acids, proteins and lipids, causing genotoxicity and impairment of homeostasis in living organisms. Proteins are essential members of the biological assembly, as they stipulate all necessary processes for the survival of an organism. Owing to their stereochemical features, POPs and their metabolites form energetically favourable complexes with proteins, as supported by biological and dose-dependent toxicological studies. Although individual studies have reported the biological aspects of protein-POP interactions, no comprehensive study summarizing the structural mechanisms, thermodynamics and kinetics of protein-POP complexes is available. The current review identifies and classifies protein-POP interaction according to the structural and functional basis of proteins into five major protein targets, including digestive and other enzymes, serum proteins, transcription factors, transporters, and G-protein coupled receptors. Further, analysis detailing the molecular interactions and structural mechanism evidenced that H-bonds, van der Waals, and hydrophobic interactions essentially mediate the formation of protein-POP complexes. Moreover, interaction of POPs alters the protein conformation through kinetic and thermodynamic processes like competitive inhibition and allostery to modulate the cellular signalling processes, resulting in various pathological conditions such as cancers and inflammations. In summary, the review provides a comprehensive insight into the critical structural/molecular aspects of protein-POP interactions.

The association between endocrine disrupting chemicals and MAFLD: Evidence from NHANES survey

Previous studies on the association of endocrine-disrupting chemicals (EDCs) with metabolic dysfunction-associated fatty liver disease (MAFLD) are very limited. This study analyzed the association of EDCs exposure with MAFLD among 5073 American adults from the 2017-2018 National Health and Nutrition Examination Survey. The results showed that increased exposure to 3 EDCs metabolites (namely As, DiNP and PFOA) were significantly associated with MAFLD, the odds ratio of which were 1.819 (95% CI: 1.224, 2.702), 1.959 (95% CI: 1.224, 3.136) and 2.148 (95% CI: 1.036, 4.456), respectively. Further, the bayesian kernel machine regression model also revealed that phthalates exposure was strongly connected with the MAFLD, particularly in females and the elderly over 65. Moderating effect analysis suggested that higher body mass index (BMI) and inflammatory diet habit (indicated by dietary inflammatory index) strengthened the association between EDCs and MAFLD, whereas population with higher level of insulin sensitivity showed lower risk. In conclusion, our results suggest that either single or combined exposure to EDCs metabolites is link to MAFLD. Our findings also encourage people to sustain a healthy diet, normal levels of insulin sensitivity and BMI, which may help to alleviate the association of MAFLD risk in exposure to EDCs. These results also help us to better understand the association of EDCs and MAFLD and provide effective evidences for preventing MAFLD from the EDCs exposure aspect.

AhR-mediated lipid peroxidation contributes to TCDD-induced cardiac defects in zebrafish

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), a persistent environmental contaminant that activates the aryl hydrocarbon receptor (AhR) pathway, has been reported to cause cardiac damage. However, the mechanism underlying AhR-induced cardiac defects in response to TCDD exposure remains unclear. In this study, we characterized the impacts of TCDD exposure on heart morphology and cardiac function in zebrafish. TCDD exposure in the early developmental stage of zebrafish embryos led to morphological heart malformation and pericardial edema, concomitant with reduced cardiac function. These cardiac defects were attenuated by inhibiting AhR activity with CH223191. Transcriptome profiling showed that, along with an upregulation of the AhR signaling pathway by TCDD treatment, the expression of pro-ferroptotic genes was upregulated, while that of genes implicated in glutathione metabolism were downregulated. Moreover, lipid peroxidation, as indicated by malonaldehyde (MDA) production, was increased in TCDD-exposed cardiac tissue. Accordingly, inhibiting lipid peroxidation with liproxstatin-1 reversed the adverse cardiac effects induced by TCDD treatment. Taken together, our findings demonstrate that AhR-mediated lipid peroxidation contributes to cardiac defects in the early developmental stage in zebrafish embryos exposed to TCDD.

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

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

Mitochondrial alterations in fatty liver diseases

Fatty liver diseases can result from common metabolic diseases, as well as from xenobiotic exposure and excessive alcohol use, all of which have been shown to exert toxic effects on hepatic mitochondrial functionality and dynamics. Invasive or complex methodology limits large-scale investigations of mitochondria in human livers. Nevertheless, abnormal mitochondrial function, such as impaired fatty acid oxidation and oxidative phosphorylation, drives oxidative stress and has been identified as an important feature of human steatohepatitis. On the other hand, hepatic mitochondria can be flexible and adapt to the ambient metabolic condition to prevent triglyceride and lipotoxin accumulation in obesity. Experience from studies on xenobiotics has provided important insights into the regulation of hepatic mitochondria. Increasing awareness of the joint presence of metabolic disease-related (lipotoxic) and alcohol-related liver diseases further highlights the need to better understand their mutual interaction and potentiation in disease progression. Recent clinical studies have assessed the effects of diets or bariatric surgery on hepatic mitochondria, which are also evolving as an interesting therapeutic target in non-alcoholic fatty liver disease. This review summarises the current knowledge on hepatic mitochondria with a focus on fatty liver diseases linked to obesity, type 2 diabetes and xenobiotics.

Butylparaben Exposure Induced Darker Skin Pigmentation in Nile Tilapia (Oreochromis niloticus)

Butylparaben (BuP), as an emerging contaminant with endocrine-disrupting effects, may exert effects on skin pigmentation in fish by interfering with the neuroendocrine system. Therefore, models of BuP exposure in Nile tilapia (Oreochromis niloticus) were established by adding different doses of BuP (0, 5, 50, 500, and 5000 ng/L) for 56 days. The obtained results showed that BuP exposure induced darker skin pigmentation, manifested as increased melanin content of skin, while genes related to melanin synthesis, including α-MSH and Asip2, significantly changed. In addition, BuP exposure reduced dopamine and γ-aminobutyric acid content in the brain, which is related to the synthesis of α-MSH. Furthermore, the release of neurotransmitters from the brain is affected by light. Thus, the relative gene expression levels in the phototransduction pathway were evaluated to explore the molecular mechanism of BuP-induced darker skin pigmentation, and the obtained results showed that Arr3a and Arr3b expression was significantly upregulated, whereas Opsin expression was significantly downregulated in a BuP dose-dependent manner, indicating that BuP inhibited phototransduction from the retina to the brain. Importantly, correlation analysis results showed that all melanin indexes were significantly positively correlated with Arr3b expression and negatively correlated with Opsin expression. This study indicated that BuP induced darker skin pigmentation in Nile tilapia via the neuroendocrine circuit, which reveals the underlying molecular mechanism for the effects of contaminants in aquatic environments on skin pigmentation in fish.

Phytoestrogens and Health Effects

Phytoestrogens are literally estrogenic substances of plant origin. Although these substances are useful for plants in many aspects, their estrogenic properties are essentially relevant to their predators. As such, phytoestrogens can be considered to be substances potentially dedicated to plant-predator interaction. Therefore, it is not surprising to note that the word phytoestrogen comes from the early discovery of estrogenic effects in grazing animals and humans. Here, several compounds whose activities have been discovered at nutritional concentrations in animals and humans are examined. The substances analyzed belong to several chemical families, i.e., the flavanones, the coumestans, the resorcylic acid lactones, the isoflavones, and the enterolignans. Following their definition and the evocation of their role in plants, their metabolic transformations and bioavailabilities are discussed. A point is then made regarding their health effects, which can either be beneficial or adverse depending on the subject studied, the sex, the age, and the physiological status. Toxicological information is given based on official data. The effects are first presented in humans. Animal models are evoked when no data are available in humans. The effects are presented with a constant reference to doses and plausible exposure.

Application of In Vitro Models for Studying the Mechanisms Underlying the Obesogenic Action of Endocrine-Disrupting Chemicals (EDCs) as Food Contaminants-A Review

Obesogenic endocrine-disrupting chemicals (EDCs) belong to the group of environmental contaminants, which can adversely affect human health. A growing body of evidence supports that chronic exposure to EDCs can contribute to a rapid increase in obesity among adults and children, especially in wealthy industrialized countries with a high production of widely used industrial chemicals such as plasticizers (bisphenols and phthalates), parabens, flame retardants, and pesticides. The main source of human exposure to obesogenic EDCs is through diet, particularly with the consumption of contaminated food such as meat, fish, fruit, vegetables, milk, and dairy products. EDCs can promote obesity by stimulating adipo- and lipogenesis of target cells such as adipocytes and hepatocytes, disrupting glucose metabolism and insulin secretion, and impacting hormonal appetite/satiety regulation. In vitro models still play an essential role in investigating potential environmental obesogens. The review aimed to provide information on currently available two-dimensional (2D) in vitro animal and human cell models applied for studying the mechanisms of obesogenic action of various industrial chemicals such as food contaminants. The advantages and limitations of in vitro models representing the crucial endocrine tissue (adipose tissue) and organs (liver and pancreas) involved in the etiology of obesity and metabolic diseases, which are applied to evaluate the effects of obesogenic EDCs and their disruption activity, were thoroughly and critically discussed.

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

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

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

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

Analysis of environmental chemical mixtures and nonalcoholic fatty liver disease: NHANES 1999-2014

We aimed to investigate the associations between chemical mixtures and the risk of nonalcoholic fatty liver disease (NAFLD) in this study. A total of 127 exposure analytes within 13 chemical mixture groups were included in the current analysis. Associations between chemical mixture exposure and prevalence of NAFLD were examined using weighted quantile sum (WQS) regressions. NAFLD was diagnosed by hepatic steatosis index (HSI) and US fatty liver index (USFLI). In USFLI-NAFLD cohort, chemical mixtures positively associated with NAFLD development included urinary metals (OR: 1.10, 95% CI: 1.04-1.16), urinary perchlorate, nitrate and thiocyanate (OR: 1.06, 95% CI: 1.02-1.11), urinary pesticides (OR: 1.24, 95% CI: 1.09-1.40), urinary phthalates (OR: 1.18, 95% CI: 1.09-1.28), urinary polyaromatic hydrocarbons (PAHs) (OR: 1.08, 95% CI: 1.03-1.14), and urinary pyrethroids, herbicides, and organophosphate pesticides metabolites (OR: 1.32, 95% CI: 1.15-1.51). All of the above mixtures were also statistically significant in WQS regressions in the HSI-NAFLD cohort. Besides, some chemical mixtures were only significant in HSI-NAFLD cohort including urinary arsenics (OR: 1.07, 95% CI: 1.02-1.12), urinary phenols (OR: 1.10, 95% CI: 1.02-1.19) and blood polychlorinated dibenzo-p-dioxins (OR: 1.10, 95% CI: 1.03-1.17). Three types of chemical mixtures only showed significant associations in the healthy lifestyle score (HLS) of 3-4 subgroup, including urinary perchlorate, nitrate and thiocyanate, urinary PAHs and blood polychlorinated dibenzo-p-dioxins. In conclusion, the exposure of specific types of chemical mixtures were associated with elevated NAFLD risk, and the effects of some chemical mixtures on NAFLD development exhibited differences in participants with different lifestyles.

The mediating function of obesity on endocrine-disrupting chemicals and insulin resistance in children

OBJECTIVES

To explore the association of endocrine-disrupting chemicals (EDCs) with insulin resistance (IR) in children as well as whether obesity played a mediation role between EDCs and IR.

METHODS

In this cross-sectional study, the data of 878 subjects were included, and divided into the non-IR group (n=501) and IR group (n=377). The associations of EDC and IR, obesity, abdominal obesity were shown by restricted cubic spline (RCS). Univariate and multivariable logistic analysis were applied to explore the associations between EDCs and IR as well as EDCs and obesity, respectively. Bootstrap coefficient product was used to analyze the medication effect of obesity on EDCs and IR.

RESULTS

RCS showed that increase of benzophenone-3 (BP-3) level was associated with increased risk of IR, obesity and abdominal obesity. After adjusting for confounders, BP-3>100 ng/mL was a risk factor for IR (OR=1.42, 95%CI: 1.11-1.81). In the adjusted model, we found BP-3>100 ng/mL was a risk factor for both obesity (OR=1.52, 95%CI: 1.13-2.04) and abdominal obesity (OR=1.68, 95%CI: 1.11-2.54). The indirect effect of obesity as a mediator on the relationship between BP-3 and IR was 0.038 (95%CI: 0.016-0.090) and the direct effect of obesity as a mediator on the relationship between BP-3 and IR was 0.077 (95%CI: 0.001-0.160). As for abdominal obesity, the indirect effect of it on the relationship between BP-3 and IR was 0.039 (95%CI: 0.007-0.070).

CONCLUSIONS

BP-3 level might be a risk factor for IR and obesity in children, and obesity was a mediator on the relationship between BP-3 and IR in children.

Association between organochlorine pesticides and nonalcoholic fatty liver disease in the National Health and Nutrition Examination Survey 2003-2004

While endocrine disruptors are emerging as a cause of nonalcoholic fatty liver disease (NAFLD), little is known about the link between NAFLD and organochlorine pesticides (OCPs), one of the endocrine disruptors. We retrospectively analyzed the U.S. National Health and Nutrition Examination Survey 2003-2004 and compared the baseline demographics in individuals according to the presence of NAFLD (fatty liver index [FLI] ≥ 60). Logistic regression analysis was performed to determine whether OCP concentration affected NAFLD prevalence and subgroup analyses regarding NAFLD-related variables and advanced hepatic fibrosis (FIB-4 ≥ 2.67) were performed. Of the 1515 individuals, 579 (38.2%) had NAFLD. Oxychlordane showed concentration-dependent risk for NAFLD (OR 3.471 in fourth quartile [Q4]; 95% CI 1.865-6.458; P = 0.007). p,p'-DDE and trans-nonachlor showed similar trends without statistical significance. Conversely, mirex showed the lowest risk for NAFLD in the highest concentration quartile (OR 0.29 in Q4; 95% CI 0.175-0.483; P < 0.001). Oxychlordane showed the most pronounced association with the levels of each component of FLI and liver enzymes. None of the OCPs were significantly associated with advanced fibrosis. In conclusion, among OCPs, exposure to oxychlordane showed the most prominent impact associated with NAFLD.

Association of Prenatal Exposure to Endocrine-Disrupting Chemicals With Liver Injury in Children

Importance

Prenatal exposures to endocrine-disrupting chemicals (EDCs) may increase the risk for liver injury in children; however, human evidence is scarce, and previous studies have not considered potential EDC-mixture effects. Furthermore, the association between prenatal EDC exposure and hepatocellular apoptosis in children has not been studied previously.

Objective

To investigate associations of prenatal exposure to EDC mixtures with liver injury risk and hepatocellular apoptosis in childhood.

Design, Setting, and Participants

This prospective cohort study used data collected from April 1, 2003, to February 26, 2016, from mother-child pairs from the Human Early-Life Exposome project, a collaborative network of 6 ongoing, population-based prospective birth cohort studies from 6 European countries (France, Greece, Lithuania, Norway, Spain, and the UK). Data were analyzed from April 1, 2021, to January 31, 2022.

Exposures

Three organochlorine pesticides, 5 polychlorinated biphenyls, 2 polybrominated diphenyl ethers (PBDEs), 3 phenols, 4 parabens, 10 phthalates, 4 organophosphate pesticides, 5 perfluoroalkyl substances, and 9 metals.

Main Outcomes and Measures

Child serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), γ-glutamyltransferase (GGT), and CK-18 were measured at 6 to 11 years of age. Risk for liver injury was defined as having ALT, AST, and/or GGT levels above the 90th percentile. Associations of liver injury or cytokeratin 18 (CK-18) levels with each chemical group among the 45 EDCs measured in maternal blood or urine samples collected in pregnancy were estimated using 2 complimentary exposure-mixture methods: bayesian weighted quantile sum (BWQS) and bayesian kernel machine regression.

Results

The study included 1108 mothers (mean [SD] age at birth, 31.0 [4.7] years) and their singleton children (mean [SD] age at liver assessment, 8.2 [1.6] years; 598 [54.0%] boys). Results of the BWQS method indicated increased odds of liver injury per exposure-mixture quartile increase for organochlorine pesticides (odds ratio [OR], 1.44 [95% credible interval (CrI), 1.21-1.71]), PBDEs (OR, 1.57 [95% CrI, 1.34-1.84]), perfluoroalkyl substances (OR, 1.73 [95% CrI, 1.45-2.09]), and metals (OR, 2.21 [95% CrI, 1.65-3.02]). Decreased odds of liver injury were associated with high-molecular-weight phthalates (OR, 0.74 [95% CrI, 0.60-0.91]) and phenols (OR, 0.66 [95% CrI, 0.54-0.78]). Higher CK-18 levels were associated with a 1-quartile increase in polychlorinated biphenyls (β, 5.84 [95% CrI, 1.69-10.08] IU/L) and PBDEs (β, 6.46 [95% CrI, 3.09-9.92] IU/L). Bayesian kernel machine regression showed associations in a similar direction as BWQS for all EDCs and a nonlinear association between phenols and CK-18 levels.

Conclusions and Relevance

With a combination of 2 state-of-the-art exposure-mixture approaches, consistent evidence suggests that prenatal exposures to EDCs are associated with higher risk for liver injury and CK-18 levels and constitute a potential risk factor for pediatric nonalcoholic fatty liver disease.

Effects of bone marrow-derived mesenchymal stem cells exposed to endocrine-disrupting chemicals on the differentiation of umbilical cord blood hematopoietic stem cells

Endocrine-disrupting chemicals (EDCs), a class of peripheral toxic substances, can cause many environmental and clinical side effects, particularly on the human body's endocrine system. Bisphenol A (BPA) and diethylhexyl phthalate (DEHP) are two well-known EDCs in the medicine industry. However, there are no comprehensive studies on their effects on hematopoiesis. Hence, this study aimed to investigate the effect of these two aforementioned substances on the clonogenic capacity of umbilical cord blood hematopoietic stem cells (CB-HSCs). The HSCs which express CD34 + were isolated from umbilical cord blood by the magnetic-activated cell sorting (MACS) system. To investigate the effects of different optimized concentrations of BPA and DEHP, CB-CD34⁺ HSCs were exposed to EDCs in semisolid medium. For evaluation of coexposures, CB-CD34⁺ HSCs were cocultured with bone marrow-derived mesenchymal stem cells (BM-MSCs) in the presence of BPA and DEHP. Finally, the number and types of colonies were evaluated after 14 days. Statistical analysis was performed by GraphPad Prism through ANOVA. CB-HSC treated by BPA and DEHP showed a lower absolute colony count than the control group (P < 0.05). Decrease in clonogenic potential of HSCs was more significant in coculture condition by MSCs. In particular, there was a significant decrease in the BFU-E colonies in comedicated-derived fractions (P < 0.0001). In the presence of EDCs such as BPA and DEHP, the patterns of differentiation in CD34⁺ CB-HSCs changed from suppressed erythroid differentiation toward stimulated myelogenesis pathways.

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.

PPAR-Targeted Therapies in the Treatment of Non-Alcoholic Fatty Liver Disease in Diabetic Patients

Peroxisome proliferator-activated receptors (PPAR), ligand-activated transcription factors of the nuclear hormone receptor superfamily, have been identified as key metabolic regulators in the liver, skeletal muscle, and adipose tissue, among others. As a leading cause of liver disease worldwide, non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) cause a significant burden worldwide and therapeutic strategies are needed. This review provides an overview of the evidence on PPAR-targeted treatment of NAFLD and NASH in individuals with type 2 diabetes mellitus. We considered current evidence from clinical trials and observational studies as well as the impact of treatment on comorbid metabolic conditions such as obesity, dyslipidemia, and cardiovascular disease. Future areas of research, such as possible sexually dimorphic effects of PPAR-targeted therapies, are briefly reviewed.