Lipid Metabolism Alteration by Endocrine Disruptors in Animal Models: An Overview

Rhythm- and sex-dependent lipid accumulation in Drosophila melanogaster by phthalates

Phthalates (PAEs) have been linked to obesity prevalence. Their obesogenic effects were influenced by sexes and rhythm, while the underlying mechanisms remained to be explored. In the present study, dimethyl phthalate (DMP), dioctyl phthalate (DOP), diisopentyl phthalate (DIPP) and diisodecyl phthalate (DIDP) were chosen as the PAEs' representatives, and their obesogenic effects were measured in Drosophila melanogaster with consideration on sleep and eclosion rhythms and sex-dependent differences. Results showed that DMP and DOP stimulated body weight, and 4 PAEs commonly influenced the total sleep with less inhibition or more stimulation in males than in females. Biochemical analysis showed that 4 PAEs commonly elevated levels of triglyceride (TG), glucose and lactate with more significant effects in males than in females, with simultaneous more stimulated enzymes in males. Meanwhile, their stimulatory effects on cholesterol and pyruvate were more overwhelmed in females. In addition, the PAEs' effects on TG were more convincing in adults eclosed in afternoon (PM) than those in morning (AM), while their effects on glucose, lactate, cholesterol and pyruvate were more convincing in AM adults with simultaneous more stimulated enzymes than in PM ones. Further analysis on the expressions of the pdk-1/akt/foxo signaling pathway, and the results demonstrated that the PAEs' effects on lipid metabolism connected with their influences on rhythm and hormone regulations. The correlation analysis on the overall results demonstrated that the PAEs' toxicities were also influenced by the molecular weights.

The associations between prenatal plastic phthalate exposure and lipid acylcarnitine levels in humans and mice

Phthalates are ubiquitous environmental pollutants known for their endocrine-disrupting properties, particularly during critical periods such as pregnancy and early childhood. Phthalates alter lipid metabolism, but the role of prenatal exposure on the offspring lipidome is less understood. In particular, we focused on long chain acylcarnitines - intermediates of fatty acid oxidation that serve as potential biomarkers of mitochondrial function and energy metabolism. This study aimed (i) to investigate the association between prenatal phthalate exposure and the child's blood acylcarnitine concentrations and, (ii) to evaluate the impact of prenatal administration of di-(2-ethylhexyl) phthalate (DEHP) on acylcarnitine levels in mouse offspring blood, brain and liver. We conducted analyses of both a prospective birth cohort study and an experimental study in mice. From the Barwon Infant Study cohort (1074 mother-child pairs), prenatal phthalate exposure was assessed at 36 weeks' gestation and its association with acylcarnitine levels was examined in cord blood, and child's blood at 6 months, 12 months and 4 years. In mice, pregnant C57BL/6 J mouse dams were exposed to 20 μg/kg DEHP for 5 days mid-gestation, and offspring tissues were analyzed at 1 month of age postnatally for acylcarnitine profiles. Our findings demonstrate that prenatal phthalate levels (specifically butyl benzyl phthalate (BBzP) and diisobutyl phthalate (DiBP)) are inversely associated with total long chain acylcarnitine levels in human cord blood at birth. In contrast, BBzP was positively associated with the long chain acylcarnitines at 12 months of age. In mice, prenatal DEHP exposure for only 5 days led to decreased palmitoylcarnitine (AC16:0) levels in the brain and liver, but not in blood. Taken together, our findings highlight that prenatal phthalate exposure can alter acylcarnitine profiles, indicating disruptions in fatty acid metabolism that may have long-term effects on metabolic health.

The herbicide acetochlor causes lipid peroxidation by inhibition of glutathione peroxidase activity

Metabolic syndrome is increasing worldwide, particularly in rural communities, where residents have a higher risk of exposure to pesticides. We investigated whether six commonly used agricultural pesticides on corn and soy fields possess adipogenic and metabolic disruption activity. Exposure to two of these pesticides, the herbicides acetochlor and metolachlor, induced adipogenesis in vitro in mouse 3T3-L1 preadipocytes. The most potent compound, acetochlor, was selected for further studies in zebrafish. Acetochlor exposure induced morphological malformations and lethality in zebrafish larvae with an EC50 of 7.8 µM and LC50 of 12 µM. Acetochlor exposure at 10 nM resulted in lipid accumulation in zebrafish larvae when simultaneously fed a high-cholesterol diet. To decipher the molecular mechanisms behind acetochlor action, we performed transcriptomic and lipidomic analyses of exposed animals. The combined omics results suggested that acetochlor exposure increased Nrf2 activity in response to reactive oxygen species, as well as induced lipid peroxidation and ferroptosis. We further discovered that acetochlor structurally shares a chloroacetamide group with known inhibitors of glutathione peroxidase 4 (GPX4). Computational docking analysis suggested that acetochlor covalently binds to the active site of GPX4. Consistent with this prediction, Gpx activity was efficiently repressed by acetochlor in zebrafish, whereas lipid peroxidation was increased. We propose that acetochlor disrupts lipid homeostasis by inhibiting GPX activity, resulting in the accumulation of lipid peroxidation, 4-hydroxynonenal, and reactive oxygen species, which in turn activate Nrf2. Because metolachlor, among other acetanilide herbicides, also contains the chloroacetamide group, inhibition of GPX activity may represent a novel, common molecular initiating event of metabolic disruption.

Probiotics as Potential Tool to Mitigate Nucleotide Metabolism Alterations Induced by DiNP Dietary Exposure in Danio rerio

Diisononyl phthalate, classified as endocrine disruptor, has been investigate to trigger lipid biosynthesis in both mammalian and teleostean animal models. Despite this, little is known about the effects of DiNP exposure at tolerable daily intake level and the possible mechanisms of its toxicity. Probiotics, on the other hand, were demonstrated to have beneficial effects on the organism's metabolism and recently emerged as a possible tool to mitigate the EDC toxicity. In the present study, using a metabolomic approach, the potential hepatic sex-related toxicity of DiNP was investigated in adult zebrafish together with the mitigating action of the probiotic formulation SLAB51, which has already demonstrated its ability to ameliorate gastrointestinal pathologies in animals including humans. Zebrafish were exposed for 28 days to 50 µg/kg body weight (bw)/day of DiNP (DiNP) through their diet and treated with 109 CFU/g bw of SLAB51 (P) and the combination of DiNP and SLAB51 (DiNP + P), and the results were compared to those of an untreated control group (C). DiNP reduced AMP, IMP, and GMP in the purine metabolism, while such alterations were not observed in the DiNP + P group, for which the phenotype overlapped that of C fish. In addition, in male, DiNP reduced UMP and CMP levels in the pyrimidine metabolism, while the co-administration of probiotic shifted the DiNP + P metabolic phenotype toward that of P male and closed to C male, suggesting the beneficial effects of probiotics also in male fish. Overall, these results provide the first evidence of the disruptive actions of DiNP on hepatic nucleotide metabolism and mitigating action of the probiotic to reduce a DiNP-induced response in a sex-related manner.

Exposure of women undergoing in-vitro fertilization to per-and polyfluoroalkyl substances: Evidence on negative effects on fertilization and high-quality embryos

In April 2023, the World Health Organization (WHO) reported that 17.5% of the global adult population experience infertility. What may be the contribution of per-and polyfluoroalkyl (PFAS) to this global public health problem? This study explored the associations between in vitro fertilization (IVF) outcomes and plasma concentrations of individual PFAS and PFAS mixtures in women undergoing in vitro fertilization and embryo transfer (IVF-ET) and how these exposures might affect IVF outcomes. We analyzed 8 PFASs in plasma samples from women (N = 259) who underwent IVF treatment. In multivariable generalized linear mixed models, there were statistically significant associations of higher plasma concentrations of PFNA with reduced numbers of total retrieved oocytes [12.486 (95%CI: 0.446,25.418), p trend = 0.017], 2 PN zygotes [6.467(95%CI: 2.034,14.968), p trend = 0.007], and cleavage embryos [6.039(95%CI: 2.162,14.240), p trend = 0.008]. Similarly, there was a continuous decline in the numbers of retrieved 2 PN zygotes and cleavage embryos with increasing concentration of PFOS [6.467(95%CI: 2.034,14.968), p trend = 0.009 and 6.039(95%CI: 2.162,14.240), p trend = 0.031,respectively] and a negative association between PFHxS concentrations and clinical pregnancy during the initial cycles of frozen ET [0.525(95%CI:0.410,0.640), p trend = 0.021]. To investigate the joint effect of PFAS mixtures, a confounder-adjusted BKMR model analysis showed inverse relationship between PFAS mixtures and the number of high-quality embryos, 2 PN zygotes and cleavage embryos, to which the greatest contributors to the mixture effect are PFDeA and PFBS, respectively. It demonstrated that PFAS exposure might exert negative effects on oocyte yield, fertilization and high-quality embryo in women undergoing IVF. These findings suggest that exposure to PFAS may increase the risk of female infertility and further studies are needed to uncover the potential mechanisms underlying the reproductive effects associated with PFAS.

Effects of BBIBP-CorV vaccine on gut microbiota and short-chain fatty acids in mice exposed to bis (2-ethylhexyl) phthalate and dioctyl terephthalate

As the COVID-19 pandemic has progressed, increasing evidences suggest that the gut microbiota may play a crucial role in the effectiveness of SARS-CoV-2 vaccine. Thus, this study was aimed at investigating the influence of SARS-CoV-2 vaccine on the gut microbiota and short-chain fatty acids (SCFAs) of organisms exposed to environmental contaminants, i.e., plasticizers: phthalate esters. We found that in mice, exposure to dioctyl terephthalate (DOTP) and bis -2-ethylhexyl phthalate (DEHP) decreased the blood glucose level and white fat weight, induced inflammatory responses, caused damage to liver and intestinal tissues, and disrupted the gut microbiota composition and SCFAs metabolism. Specifically, the Bacteroidetes phylum was positively correlated with BBIBP-CorV vaccine, while acetic acid was negatively associated with the vaccine. Interestingly, the BBIBP-CorV vaccine somewhat alleviated tissue inflammation and reduced the contents of acetic acid and propionic acid in mice exposed to DEHP and DOTP. These findings were confirmed by a fecal microbiota transplantation assay. Overall, this study revealed that exposure to DEHP and DOTP adversely affects the gut microbiota and SCFAs, while the BBIBP-CorV vaccine can protect mice against these effects. This work highlighted the relationship between BBIBP-CorV vaccination, gut microbiome composition, and responses to plasticizers, which may facilitate the development and risk assessment of SARS-CoV-2 vaccines and environmental contaminants on microbiota health.

Maternal phthalate exposure and BMI trajectory in children-an 18-year birth cohort follow-up study

BACKGROUND

Obesity is a major health concern worldwide. Previous studies have suggested that phthalate plasticizers are obesogens. However, the relationship between early-life phthalate exposure and long-term obesity development remains unknown.

OBJECTIVE

We investigated the association between prenatal phthalate exposure and children's body mass index (BMI) patterns in an 18-year birth cohort follow-up study in Taiwan.

METHODS

Our analytical lab quantified seven phthalate metabolites in maternal urine during pregnancy using quantitative liquid chromatography-tandem mass spectrometry. In addition, we calculated BMI z scores for participated children at each follow-up, utilized trajectory analysis to describe children's BMI z-score patterns at 2-18 years of age, and adopted generalized estimating equations (GEE) and multivariate logistic regression models to assess the association between prenatal phthalate exposure and BMI z scores in children.

RESULTS

A total of 208 mother-child pairs were included in the analysis. Maternal urinary diethyl phthalate (DEP) metabolites were associated with the increase of BMI z scores in children aged 2-18 years in the GEE model. Doubled maternal urinary ∑mDEHP (3 mono hexyl-metabolites of di-ethyl-hexyl phthalate (DEHP) increased the risk of children being in the stable-high BMI trajectory group until the age of eighteen.

IMPACT STATEMENT

We observed that BMI trajectories of children remained stable after the age of 5 years. During each follow-up, a higher frequency of overweight or obese was observed in children, ranging from 15.9% to 35.6% for girls and 15.2-32.0% for boys, respectively. Prenatal phthalate exposure was associated with increasing BMI z scores in children. Prenatal DEHP exposure was associated with a stable-high BMI trajectory in children up to the age of 18 years.

From big data to big insights: statistical and bioinformatic approaches for exploring the lipidome

The goal of lipidomic studies is to provide a broad characterization of cellular lipids present and changing in a sample of interest. Recent lipidomic research has significantly contributed to revealing the multifaceted roles that lipids play in fundamental cellular processes, including signaling, energy storage, and structural support. Furthermore, these findings have shed light on how lipids dynamically respond to various perturbations. Continued advancement in analytical techniques has also led to improved abilities to detect and identify novel lipid species, resulting in increasingly large datasets. Statistical analysis of these datasets can be challenging not only because of their vast size, but also because of the highly correlated data structure that exists due to many lipids belonging to the same metabolic or regulatory pathways. Interpretation of these lipidomic datasets is also hindered by a lack of current biological knowledge for the individual lipids. These limitations can therefore make lipidomic data analysis a daunting task. To address these difficulties and shed light on opportunities and also weaknesses in current tools, we have assembled this review. Here, we illustrate common statistical approaches for finding patterns in lipidomic datasets, including univariate hypothesis testing, unsupervised clustering, supervised classification modeling, and deep learning approaches. We then describe various bioinformatic tools often used to biologically contextualize results of interest. Overall, this review provides a framework for guiding lipidomic data analysis to promote a greater assessment of lipidomic results, while understanding potential advantages and weaknesses along the way.

Bisphenol A and cardiometabolic risk in adolescents: Data from the Generation XXI cohort

BACKGROUND AND AIMS

Bisphenol A (BPA), an endocrine disruptor widely used in food contact materials, has been linked to a worse health profile. This study intends to estimate the association between BPA exposure and cardiometabolic patterns at adolescence.

METHODS AND RESULTS

Data from the Portuguese population-based birth cohort Generation XXI at the age of 13 were used (n = 2386 providing 3-day food diaries and fasting blood samples). BPA exposure was measured in 24-h urine from a subsample (n = 206) and then predicted in all participants using a random forest method and considering dietary intake from diaries. Three cardiometabolic patterns were identified (normal, modified lipid profile and higher cardiometabolic risk) using a probabilistic Gaussian mixture model. Multinomial regression models were applied to associate BPA exposure (lower, medium, higher) and cardiometabolic patterns, adjusting for confounders. The median BPA exposure was 1532 ng/d, corresponding to 29.4 ng/kg/d. Adolescents higher exposed to BPA (compared to medium and lower levels) had higher BMI z-score (kg/m2) (0.68 vs. 0.39 and 0.52, respectively; p = 0.008), higher levels of body fat (kg) (16.3 vs. 13.8 and 14.6, respectively; p = 0.002), waist circumference (76.2 vs. 73.7 and 74.9, respectively; p = 0.026), insulinemia (ug/mL) (14.1 vs. 12.7 and 13.1, respectively; p = 0.039) and triglyceridemia (mg/dL) (72.7 vs. 66.1 and 66.5, respectively; p = 0.030). After adjustment, a significant association between higher BPA and a higher cardiometabolic risk pattern was observed (OR: 2.55; 95%CI: 1.41, 4.63).

CONCLUSION

Higher BPA exposure was associated with a higher cardiometabolic risk pattern in adolescents, evidencing the role of food contaminants in health.

Differential Disruption of Glucose and Lipid Metabolism Induced by Phthalates in Human Hepatocytes and White Adipocytes

Phthalic acid esters (PAEs), commonly used as plasticizers, are pervasive in the environment, leading to widespread human exposure. The association between phthalate exposure and metabolic disorders has been increasingly recognized, yet the precise biological mechanisms are not well-defined. In this study, we explored the effects of monoethylhexyl phthalate (MEHP) and monocyclohexyl phthalate (MCHP) on glucose and lipid metabolism in human hepatocytes and adipocytes. In hepatocytes, MEHP and MCHP were observed to enhance lipid uptake and accumulation in a dose-responsive manner, along with upregulating genes involved in lipid biosynthesis. Transcriptomic analysis indicated a broader impact of MEHP on hepatic gene expression relative to MCHP, but MCHP particularly promoted the expression of the gluconeogenesis key enzymes G6PC and FBP1. In adipocytes, MEHP and MCHP both increased lipid droplet formation, mimicking the effects of the Peroxisome proliferator-activated receptor γ (PPARγ) agonist rosiglitazone (Rosi). Transcriptomic analysis revealed that MEHP predominantly altered fatty acid metabolism pathways in mature adipocytes (MA), whereas MCHP exhibited less impact. Metabolic perturbations from MEHP and MCHP demonstrate shared activation of the PPARs pathway in hepatocytes and adipocytes, but the cell-type discrepancy might be attributed to the differential expression of PPARγ. Our results indicate that MEHP and MCHP disrupt glucose and lipid homeostasis in human liver and adipose through mechanisms that involve the PPAR and adenosine monophosphate-activated protein kinase (AMPK) signaling pathways, highlighting the nuanced cellular responses to these environmental contaminants.

Efficient removal of toxicity associated to wastewater treatment plant effluents by enhanced Soil Aquifer Treatment

The regeneration of wastewater has been recognized as an effective strategy to counter water scarcity. Nonetheless, Wastewater Treatment Plant (WWTP) effluents still contain a wide range of contaminants of emerging concern (CECs) even after water depuration. Filtration through Soil Aquifer Treatment (SAT) systems has proven efficient for CECs removal although the attenuation of their associated biological effects still remains poorly understood. To evaluate this, three pilot SAT systems were monitored, two of them enhanced with different reactive barriers. SATs were fed with secondary effluents during two consecutive campaigns. Fifteen water samples were collected from the WWTP effluent, below the barriers and 15 m into the aquifer. The potential attenuation of effluent-associated biological effects by SATs was evaluated through toxicogenomic bioassays using zebrafish eleutheroembryos and human hepatic cells. Transcriptomic analyses revealed a wide range of toxic activities exerted by the WWTP effluents that were reduced by more than 70% by SAT. Similar results were observed when HepG2 hepatic cells were tested for cytotoxic and dioxin-like responses. Toxicity reduction appeared partially determined by the barrier composition and/or SAT managing and correlated with CECs removal. SAT appears as a promising approach to efficiently reduce effluent-associated toxicity contributing to environmental and human health preservation.

The Role of the Vascular System in Degenerative Diseases: Mechanisms and Implications

Degenerative diseases, encompassing a wide range of conditions affecting various organ systems, pose significant challenges to global healthcare systems. This comprehensive review explores the intricate interplay between the vascular system and degenerative diseases, shedding light on the underlying mechanisms and profound implications for disease progression and management. The pivotal role of the vascular system in maintaining tissue homeostasis is highlighted, as it serves as the conduit for oxygen, nutrients, and immune cells to vital organs and tissues. Due to the vital role of the vascular system in maintaining homeostasis, its dysfunction, characterized by impaired blood flow, endothelial dysfunction, and vascular inflammation, emerges as a common denominator of degenerative diseases across multiple systems. In the nervous system, we explored the influence of vascular factors on neurodegenerative diseases such as Alzheimer's and Parkinson's, emphasizing the critical role of cerebral blood flow regulation and the blood-brain barrier. Within the kidney system, the intricate relationship between vascular health and chronic kidney disease is scrutinized, unraveling the mechanisms by which hypertension and other vascular factors contribute to renal dysfunction. Throughout this review, we emphasize the clinical significance of understanding vascular involvement in degenerative diseases and potential therapeutic interventions targeting vascular health, highlighting emerging treatments and prevention strategies. In conclusion, a profound appreciation of the role of the vascular system in degenerative diseases is essential for advancing our understanding of degenerative disease pathogenesis and developing innovative approaches for prevention and treatment. This review provides a comprehensive foundation for researchers, clinicians, and policymakers seeking to address the intricate relationship between vascular health and degenerative diseases in pursuit of improved patient outcomes and enhanced public health.

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

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

The associations between high-levels of urine benzophenone-type UV filters (BPs) and changes in serum lipid concentrations

Little is known about the potential health impacts of benzophenone-type UV filters (BPs) exposure among the general population. In our study conducted in Wuxi, China, we investigated the associations between the concentrations of eight BP-derivatives and five target lipid molecules. We collected basic information, serum, and urine samples from 120 residents aged 9 to 80 in Wuxi. We determined BPs in urine samples and lipid levels in serum samples. Generalized linear models were used to evaluate the differences in ln-transformed serum target lipids levels (μg/L) with different urine BPs quartiles compared to the lowest quartile. Benzophenone-4 (BP-4) had the highest detection rate (95.0%) and geometric mean concentration (1.96 μg/L) among all the BP-derivatives in our study population. The exposure levels of BPs were generally higher in females than in males. Participants in the 9-17 and 18-50 age groups exhibited greater levels of exposure to BPs than those in the 51-80 age group. We observed statistically significant changes in LysoPC (18:0), LysoPE (18:0), ΣLPL, and ΣTL concentrations between the highest and lowest quartiles of BP-4. Similar changes were found in LysoPE (18:0) concentration between the highest and lowest quartiles of ΣBP-3 and ΣBPs. High urine BP concentrations were associated with variations in our target serum lipids involved in neurological and metabolic disorders, and posed a potential health risk. Future studies are warranted to further validate and elucidate our findings.

Preconceptional and in utero exposure of sheep to a real-life environmental chemical mixture disrupts key markers of energy metabolism in male offspring

Over recent decades, an extensive array of anthropogenic chemicals have entered the environment and have been implicated in the increased incidence of an array of diseases, including metabolic syndrome. The ubiquitous presence of these environmental chemicals (ECs) necessitates the use of real-life exposure models to the assess cumulative risk burden to metabolic health. Sheep that graze on biosolids-treated pastures are exposed to a real-life mixture of ECs such as phthalates, per- and polyfluoroalkyl substances, heavy metals, pharmaceuticals, pesticides, and metabolites thereof, and this EC exposure can result in metabolic disorders in their offspring. Using this model, we evaluated the effects of gestational exposure to a complex EC mixture on plasma triglyceride (TG) concentrations and metabolic and epigenetic regulatory genes in tissues key to energy regulation and storage, including the hypothalamus, liver, and adipose depots of 11-month-old male offspring. Our results demonstrated a binary effect of EC exposure on gene expression particularly in the hypothalamus. Principal component analysis revealed two subsets (B-S1 [n = 6] and B-S2 [n = 4]) within the biosolids group (B, n = 10), relative to the controls (C, n = 11). Changes in body weight, TG levels, and in gene expression in the hypothalamus, and visceral and subcutaneous fat were apparent between biosolid and control and the two subgroups of biosolids animals. These findings demonstrate that gestational exposure to an EC mixture results in differential regulation of metabolic processes in adult male offspring. Binary effects on hypothalamic gene expression and altered expression of lipid metabolism genes in visceral and subcutaneous fat, coupled with phenotypic outcomes, point to differences in individual susceptibility to EC exposure that could predispose vulnerable individuals to later metabolic dysfunction.

Toxicity of Per- and Polyfluoroalkyl Substances to Nematodes

Per- and polyfluoroalkyl substances (PFASs) are a class of compounds that persist in the environment globally. Besides being transported to the soil and sediments, which act as their sinks, PFASs can be transferred to several species of higher organisms directly or via bacteria, eliciting a wide range of adverse effects. Caenorhabditis elegans has been widely used in toxicological studies and life science research owing to its numerous advantages over traditional vertebrate models; notably, C. elegans has 65% conserved human-disease-associated genes and does not require ethical approvals for experimental use. This review covers a range of topics, from reported accumulation characteristics and lethal concentrations of PFAS in C. elegans to the mechanisms underlying the toxicity of PFAS at different levels, including reproductive, developmental, cellular, neurologic, oxidative, metabolic, immune, and endocrine toxicities. Additionally, the toxicity levels of some PFAS substitutes are summarized. Lastly, we discuss the toxicological mechanisms of these PFAS substitutes and the importance and promising potential of nematodes as in vivo models for life science research, epidemiological studies (obesity, aging, and Alzheimer's disease research), and toxicological investigations of PFASs and other emerging pollutants compared with other soil animals or model organisms.

Zebrafish facilitate non-alcoholic fatty liver disease research: Tools, models and applications

Non-alcoholic fatty liver disease (NAFLD) has become an increasingly epidemic metabolic disease worldwide. NAFLD can gradually deteriorate from simple liver steatosis, inflammation and fibrosis to liver cirrhosis and/or hepatocellular carcinoma. Zebrafish are vertebrate animal models that are genetically and metabolically conserved with mammals and have unique advantages such as high fecundity, rapid development ex utero and optical transparency. These features have rendered zebrafish an emerging model system for liver diseases and metabolic diseases favoured by many researchers in recent years. In the present review, we summarize a series of tools for zebrafish NAFLD research and the models established through different dietary feeding, hepatotoxic chemical treatments and genetic manipulations via transgenic or genome editing technologies. We also discuss how zebrafish models facilitate NAFLD studies by providing novel insights into NAFLD pathogenesis, toxicology research, and drug evaluation and discovery.

Lipid metabolic disturbance induced by triphenyl phosphate and hydroxy metabolite in HepG2 cells

Triphenyl phosphate (TPHP) has been widely used as flame retardants and been detected with increasing frequency in environment. TPHP can transform into mono-hydroxylated phosphate (OH-TPHP) and diester diphenyl phosphate (DPHP) through biotransformation. So far, information on the cytotoxicity and molecular regulatory mechanisms of TPHP metabolites are still limit. This study investigated the adverse effects of TPHP, OH-TPHP, and DPHP in HepG2 cells in terms of cell proliferation, lactate dehydrogenase release, reactive oxygen species generation, and mitochondrial membrane potential. The transcriptomic changes were measured using RNA sequencing, and bioinformatics characteristics including biological functions, signal pathways and protein-protein interaction were analyzed to explore the potential molecular mechanisms. Results displayed that the order of cytotoxicity was OH-TPHP> TPHP> DPHP. The prioritized biological functions changes induced by TPHP and OH-TPHP were correlated with lipid metabolism. Significant lipid accumulation was observed as confirmed by increased total cholesterol and triglycerides contents, and enhanced oil red O staining. Enrichment of PPARα/γ and down-stream genes suggested the participation of PPARs signal pathway in lipid metabolism disorder. In addition, TPHP and OH-TPHP induced endoplasmic reticulum stress (ERS), which was further confirmed by the ERS inhibitor experiment. In general, TPHP and OH-TPHP had obvious cytotoxic effects in HepG2 cells. PPARs signal pathway and endoplasmic reticulum stress may be involved in the lipid metabolism disorder induced by TPHP and OH-TPHP.

Impacts of sublethal concentrations of 17 α-ethinylestradiol (EE2) on growth, reproductive performance, and survival in red cherry shrimp Neocaridina davidi (Crustacea, Atyidae) during consecutive spawnings

This study was conducted for the first time to investigate the long-term impacts of sublethal concentrations of 17 α-ethinylestradiol (EE2) on growth, survival, and reproductive performances in a model shrimp, the red cherry (Neocaridina davidi), females during five successive spawning steps for 7.5 months. Females were distributed in eighteen aquariums and continuously exposed to EE2 at six nominal concentrations of 0 (control), 0.02, 0.2, 2, 20, and 200 μg/L. Growth indices increased up to 0.2 μg/L and then sharply declined up to 200 μg/L. Most reproductive indices significantly decreased at levels > 0.02-0.2 μg/L with increasing EE2 levels. The highest absolute, relative, and actual fecundity values were recorded in the control, with the lowest value at 200 μg/L. With increasing EE2 levels, mean egg volume showed an increasing trend from the third spawning event onwards. Except for the time required to reach the first spawning, inter-spawning intervals considerably decreased with increasing EE2 levels at > 0.2 μg/L, especially from the third spawning stage onwards. Survival of exposed females significantly decreased with increasing EE2 levels. Unlike the body size, the juvenile's survival rates in all exposed treatments were considerably lower than the control. Females at concentrations 0.02-0.2 μg/L gained more body weight and length but produced fewer eggs with lower hatching percentages during five consecutive spawns. The results suggest that EE2 depending on the concentrations can cause unbalanced growth, reduce reproductive performances, especially from the third stage of spawning onwards, and reduce survival rates in brooders and subsequent offspring. In terms of growth, survival, and reproductive indices over successive spawns in ecotoxicology studies, the concentrations of 0.02-0.2 μg/L can be considered as chronic levels, but higher levels may have detrimental effects.

Tris(4-chlorophenyl)methane and tris(4-chlorophenyl)methanol disrupt pancreatic organogenesis and gene expression in zebrafish embryos

OBJECTIVES

Tris(4-chlorophenyl) methane (TCPM) and tris(4-chlorophenyl)methanol (TCPMOH) are anthropogenic environmental contaminants believed to be manufacturing byproducts of the organochlorine pesticide dichlorodiphenyltrichloroethane (DDT) due to environmental co-occurrence. TCPM and TCPMOH are persistent, bioaccumulate in the environment, and are detected in human breast milk and adipose tissues. DDT exposures have been previously shown to disrupt insulin signaling and glucoregulation, increasing risk for diabetes. We have previously shown that embryonic exposures organochlorines such as polychlorinated biphenyls disrupted pancreatic development and early embryonic glucoregulatory networks. Here, we determined the impacts of the similar compounds TCPM and TCPMOH on zebrafish pancreatic growth and gene expression following developmental exposures.

METHODS

Zebrafish embryos were exposed to 50 nM TCPM or TCPMOH beginning at 24 hr postfertilization (hpf) and exposures were refreshed daily. At 96 hpf, pancreatic growth and islet area were directly visualized in Tg(ptf1a::GFP) and Tg(insulin::GFP) embryos, respectively, using microscopy. Gene expression was assessed at 100 hpf with RNA sequencing.

RESULTS

Islet and total pancreas area were reduced by 20.8% and 13% in embryos exposed to 50 nM TCPMOH compared to controls. TCPM did not induce significant morphological changes to the developing pancreas, indicating TCPMOH, but not TCPM, impairs pancreatic development despite similarity in molecular responses. Transcriptomic responses to TCPM and TCPMOH were correlated (R²  = .903), and pathway analysis found downregulation of processes including retinol metabolism, circadian rhythm, and steroid biosynthesis.

CONCLUSION

Overall, our data suggest that TCPM and TCPMOH may be hazardous to embryonic growth and development.

Nimbin analogs N5 and N7 regulate the expression of lipid metabolic genes and inhibit lipid accumulation in high-fat diet-induced zebrafish larvae: An antihyperlipidemic study

BACKGROUND

Excess accumulation of lipids leads to obesity. Triterpenoids are a group of plant compounds which poses various biological activities. The biological activities of Nimbin analogs N5 and N7 were addressed in this study on inhibiting lipid aggregation and underlying the derivatives molecular mechanisms for a therapeutical approach.

AIM

This study aims to evaluate the anti-adipogenic activity of semi-natural Nimbin analogs, N5 and N7, on zebrafish larvae induced with oxidative stress due to a high-fat diet (HFD) and adipogenesis using specific fluorescent stains.

MATERIALS AND METHODS

Zebrafish at 4 days post fertilized (dpf) larvae were divided into groups for the HFD diet along with exposure to various concentrations of N5 and N7. HFD induced accumulation of neutral lipids and triglycerides (Oil Red O and Nile red staining, respectively) with weight gain, which generated intracellular ROS (DCFH-DA staining) and superoxide anion production (DHE staining) with depleted glutathione levels (NDA staining) were assayed. HFD exposure promoted the accumulation of inflammatory macrophages (Neutral red staining) and impaired glucose metabolism (2NBDG staining). The ability of N5 and N7 to reduce total regulating lipogenic specific genes C/EBP-α, SREBP-1 and FAS were evaluated using relative gene expression.

KEY FINDINGS

The Nimbin analogues N5 and N7 suppressed adipogenesis, forming intracellular ROS and superoxide anion while simultaneously restoring glutathione levels. The analogues significantly lowered total TC and TG levels, prevented inflammatory macrophage build-up and boosted glucose absorption. Also, N5 and N7 down-regulate the lipogenic-specific genes.

SIGNIFICANCE

Nimbin analogs N5 and N7 enhance lipolysis and inhibit adipogenesis in in-vivo zebrafish larvae model.

Triclocarban and triclosan exacerbate high-fat diet-induced hepatic lipid accumulation at environmental related levels: The potential roles of estrogen-related receptors pathways

Triclosan (TCS) and triclocarban (TCC) have become ubiquitous pollutants detected in human body with concentrations up to hundreds of nanomolar levels. Previous studies about the hepatic lipid accumulation induced by TCS and TCC were focused on pollutant itself, which showed weak or no effects. High-fat diet (HFD), as a known environmental factor contributing to lipid metabolism-related disorders, its synergistic action with environmental pollutants deserves concern. The present study aimed to demonstrate the combined effects and potential molecular mechanisms of TCS and TCC with HFD at cellular and animal levels. The in vitro studies showed that TCC and TCS alone had negligible impact on lipid accumulation in HepG2 cells but induced lipid deposition at nanomolar levels when co-exposure with fatty acid. TCC exhibited much higher induction effects than TCS, which was related to their differential regulatory roles in adipogenic-related genes expression. The in vivo studies showed that TCC had little influence on hepatic lipid accumulation in mice fed with normal diet (ND) but could exacerbate the lipid accumulation in mice fed with HFD. Meanwhile, TCC-induced dyslipidemia in mice fed with HFD was more significant than that fed with ND. Therefore, we speculated that TCC might increase the risk of nonalcoholic fatty liver disease (NAFLD) and atherosclerosis in HFD humans. Molecular mechanism studies showed that TCC and TCS could bind to and activate estrogen-related receptor α (ERRα) and ERRγ as well as regulate their expression. TCC had higher activity on ERRα and ERRγ than TCS, which explained partly the differential regulatory roles of two receptors in the lipid accumulation induced by TCC and TCS. This work revealed synergistic effects and molecular mechanisms of TCC and TCS with excessive fatty acid on the hepatic lipid metabolism, which provided a novel insight into the toxic mechanism of pollutants from the perspective of dietary habits.

Perfluoroalkyl Acids in Follicular Fluid and Embryo Quality during IVF: A Prospective IVF Cohort in China

BACKGROUND

Perfluoroalkyl acids (PFAA) have been measured in ovarian follicular fluid from women using in vitro fertilization (IVF), although associations between follicular fluid PFAA and IVF outcomes have been inconsistent.

OBJECTIVES

We investigated the association between follicular fluid PFAA and embryo quality in women undergoing IVF.

METHODS

We prospectively enrolled 729 women undergoing IVF treatment in Guangxi province, China, from July 2018 to December 2018. We measured 32 PFAA, including branched isomers, in follicular fluid using ultra-performance liquid chromatography coupled to tandem mass spectrometry. We applied restricted cubic splines, linear regression, and log-binominal regression models to investigate associations between follicular fluid PFAA and embryo quality, adjusting for confounding variables and investigated oocyte maturity as an intervening variable using causal mediation analysis. We further estimated the overall effect of the PFAA mixture on outcomes using Bayesian kernel machine regression (BKMR).

RESULTS

We detected 8 of 32 measured PFAA in >85% of follicular fluid samples. Higher PFAA concentrations were associated with fewer high-quality embryos from IVF. The high-quality embryo rates at the 50th percentile of linear perfluoro-1-octanesulfonate acid (n-PFOS), all branched PFOS isomers (Br-PFOS) and linear perfluoro-n-octanoic acid (n-PFOA) were -6.34% [95% confidence interval (CI): -9.45, -3.32%], -16.78% (95% CI: -21.98, -11.58%) and -8.66% (95% CI: -11.88, -5.43%) lower, respectively, than the high quality embryo rates at the reference 10th percentile of PFAA. Oocyte maturity mediated 11.76% (95% CI: 3.18, 31.80%) and 14.28% (95% CI: 2.95, 31.27%) of the n-PFOS and n-PFOA associations, respectively. The results of the BKMR models showed a negative association between the PFAA mixture and the probability of high-quality embryos, with branched PFOS isomers having posterior inclusion probabilities of 1 and accounting for the majority of the association.

DISCUSSION

Exposure to higher PFAA concentrations in follicular fluid was associated with poorer embryo quality during IVF. Branched PFOS isomers may have a stronger effect than linear PFOS isomers. More studies are needed to confirm these findings and to directly estimate the effects on pregnancy and live-birth outcomes. https://doi.org/10.1289/EHP10857.

Associations of individual and cumulative urinary phthalate and replacement biomarkers with gestational weight gain through late pregnancy

BACKGROUND/AIMS

Phthalates and their replacements are endocrine/metabolic disruptors that may impact gestational weight gain (GWG) - a pregnancy health indicator. We investigated overall and fetal sex-specific associations of individual and cumulative phthalate/replacement biomarkers with GWG.

METHODS

Illinois women (n = 299) self-reported their weight pre-pregnancy and at their final obstetric appointment before delivery (median 38 weeks). We calculated pre-pregnancy body mass index and gestational age-specific GWG z-scores (GWGz). We quantified 19 phthalate/replacement metabolites (representing 10 parent compounds) in pools of up-to-five first-morning urine samples, collected approximately monthly between 8 and 40 weeks gestation. We used linear regression, quantile-based g-computation (QGComp), and weighted quantile sum regression (WQSR) to evaluate associations of ten biomarkers (individual metabolites or parent molar-sums) individually or as mixtures (in interquartile range intervals) with GWGz. We evaluated associations in all women and stratified by fetal sex.

RESULTS

Individually, sums of metabolites of di(2-ethylhexyl) phthalate (ƩDEHP), di(isononyl) cyclohexane-1,2-dicarboxylate (ƩDiNCH), and di(2-ethylhexyl) terephthalate (ƩDEHTP) had consistent inverse associations with GWGz, and some associations were fetal sex-specific. When evaluating phthalates/replacements as a mixture, QGComp identified ƩDEHP, ƩDEHTP, and mono-(3-carboxypropyl) phthalate, along with sum of di(isononyl) phthalate metabolites (ƩDiNP) and monobenzyl phthalate as notable contributors to lower and higher GWGz, respectively, resulting in a marginal inverse joint association in all women (β: -0.29; 95% CI: -0.70, 0.12). In women carrying females, ƩDEHP contributed to the marginal inverse joint association (β: -0.54; 95% CI: -1.09, 0.03). However, there was no overall association in women carrying males (β: 0.00; 95% CI: -0.60, 0.59), which was explained by approximately equal negative (driven by ƩDEHTP) and positive (driven by ƩDiNP) partial associations. WQSR analyses consistently replicated these QGComp findings.

CONCLUSIONS

Biomarkers of phthalates/replacements were fetal sex-specifically associated with GWGz. Because ƩDEHTP contributed substantively to mixture associations, additional studies in pregnant women may be needed around this plasticizer replacement.

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.

The p-Phthalates Terephthalic Acid and Dimethyl Terephthalate Used in the Manufacture of PET Induce In Vitro Adipocytes Dysfunction by Altering Adipogenesis and Thermogenesis Mechanisms

Public health concerns associated with the potential leaching of substances from Polyethylene terephthalate (PET) packaging have been raised due to the role of phthalates as endocrine-disrupting chemicals or obesogens. In particular, changes in the environment such as pH, temperature, and irradiation can improve contaminant migration from PET food packaging. In this study, the in vitro effects of p-phthalates terephthalic acid (TPA) and dimethyl terephthalate (DMT) on murine adipocytes (3T3-L1) were evaluated using concentrations that might be obtained in adult humans exposed to contaminated sources. TPA and, in particular, DMT exposure during 3T3-L1 differentiation increased the cellular lipid content and induced adipogenic markers PPAR-γ, C/EBPß, FABP4, and FASN, starting from low nanomolar concentrations. Interestingly, the adipogenic action of TPA- and DMT-induced PPAR-γ was reverted by ICI 182,780, a specific antagonist of the estrogen receptor. Furthermore, TPA and DMT affected adipocytes’ thermogenic program, reducing pAMPK and PGC-1α levels, and induced the NF-κB proinflammatory pathway. Given the observed effects of biologically relevant chronic concentrations of these p-phthalates and taking into account humans’ close and constant contact with plastics, it seems appropriate that ascertaining safe levels of TPA and DMT exposure is considered a high priority.

Utilizing Skyline to analyze lipidomics data containing liquid chromatography, ion mobility spectrometry and mass spectrometry dimensions

Lipidomics studies suffer from analytical and annotation challenges because of the great structural similarity of many of the lipid species. To improve lipid characterization and annotation capabilities beyond those afforded by traditional mass spectrometry (MS)-based methods, multidimensional separation methods such as those integrating liquid chromatography, ion mobility spectrometry, collision-induced dissociation and MS (LC-IMS-CID-MS) may be used. Although LC-IMS-CID-MS and other multidimensional methods offer valuable hydrophobicity, structural and mass information, the files are also complex and difficult to assess. Thus, the development of software tools to rapidly process and facilitate confident lipid annotations is essential. In this Protocol Extension, we use the freely available, vendor-neutral and open-source software Skyline to process and annotate multidimensional lipidomic data. Although Skyline ( https://skyline.ms/skyline.url ) was established for targeted processing of LC-MS-based proteomics data, it has since been extended such that it can be used to analyze small-molecule data as well as data containing the IMS dimension. This protocol uses Skyline's recently expanded capabilities, including small-molecule spectral libraries, indexed retention time and ion mobility filtering, and provides a step-by-step description for importing data, predicting retention times, validating lipid annotations, exporting results and editing our manually validated 500+ lipid library. Although the time required to complete the steps outlined here varies on the basis of multiple factors such as dataset size and familiarity with Skyline, this protocol takes ~5.5 h to complete when annotations are rigorously verified for maximum confidence.

The reproductive effects of the cancer chemotherapy agent, Carmofur, on Daphnia magna are mediated by its metabolite, 5-Fluorouracil

Carmofur is an antineoplastic agent that inhibits ceramidase, a key enzyme in the sphingolipid pathway. Previous research suggests carmofur represses reproductive maturity in Daphnia magna. The purpose of this experiment was to confirm carmofur's effects on fecundity and reproductive maturity over two generations. A chronic toxicity test found reproductive maturity was delayed from 9 to 19 days by 0.80 μM carmofur with a 99.7% drop in reproduction, probably caused by delayed ovarian development. Second generation effects were even greater with 0% reproductive success at 0.40 μM. To our surprise, carmofur was not measured in the media by HPLC 24 h after exposure. Previous research indicated that carmofur is unstable in water and hydrolyzed into 5-fluorouracil (5-FU). Therefore, the chronic toxicity study was repeated with 5-FU and similar effects on reproductive maturity were observed at similar concentrations despite very different acute toxicities (48 h carmofur LC50 = 1.93 μM; 5-FU LC50 = 207 μM). 5-FU delayed reproductive maturity from 9 to 21 days with a 71.12% drop in reproduction at 0.80 μM and greater effects in the 2^nd generation similar to carmofur. 5-FU was found stable in aquatic media and HPLC confirmed 5-FU was hydrolyzed from carmofur within 24 h. In conclusion, carmofur and 5-FU reduce fecundity because they delay reproductive maturity and ovarian development in Daphnia magna. We conclude that the reproductive effects observed after carmofur treatment are primarily mediated by its breakdown product, 5-FU. This further underscores the importance of measuring chemical concentrations and evaluating chemical metabolism and decomposition when determining toxicity, especially of chemotherapeutic agents.Clinical trials registration Not applicable.

Effects of dibutyl phthalate and di (2-ethylhexyl) phthalate on hepatic structure and function of adult male mice

The objective of the present research was to determine if dibutyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP) alone and combined exposure induced pathological alterations in laboratory reared albino mice. Adult male mice were equally divided (n = 10) into Control, corn oil (CO), DBP, DEHP, and DBP+DEHP treated groups. Dibutyl phthalate (250 mg/kg), DEHP (300 mg/kg), and DBP+DEHP (250+300 mg/kg), respectively, were administered by oral gavage mixed in corn oil (0.2 mL) for 28 days. All animals were sacrificed following 28 days of treatment and blood was collected for serum lipid profiles and liver function tests. Liver samples were also collected for observation of histological changes. Microphotographs of hematoxylin and eosin-stained sections were used for computer-based micrometry. CO, DBP, DEHP, and DBP+DEHP treatment resulted in a significant increase in the mean body and liver weights as compared with the Control group. Histological examination of the livers with DBP and/or DEHP treatment showed marked alterations leading to hepatic hypertrophy. In the treated groups, a significant increase in the mean number of mononucleated, binucleated cells, and oval cells per unit area was noticed with disorganized trabecular arrangement as compared with the Control group. Treatment with DBP and/or DEHP resulted in large regeneration zones in the liver and an increased relative nucleo-cytoplasmic index of mononuclear shepatocytes when compared with the Control group. All treatments caused a significant increases in the liver enzymes and proteins as well as altered serum cholesterol, triglycerides, LDL, and VLDL levels. The histopathological and serological findings confirmed the toxic potentials to hepatic tissue of DBP and DEHP either given alone or in combination.

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.

Emerging concepts and opportunities for endocrine disruptor screening of the non-EATS modalities

Endocrine disrupting chemicals (EDCs) are ubiquitous in the environment and involve diverse chemical-receptor interactions that can perturb hormone signaling. The Organization for Economic Co-operation and Development has validated several EDC-receptor bioassays to detect endocrine active chemicals and has established guidelines for regulatory testing of EDCs. Focus on testing over the past decade has been initially directed to EATS modalities (estrogen, androgen, thyroid, and steroidogenesis) and validated tests for chemicals that exert effects through non-EATS modalities are less established. Due to recognition that EDCs are vast in their mechanisms of action, novel bioassays are needed to capture the full scope of activity. Here, we highlight the need for validated assays that detect non-EATS modalities and discuss major international efforts underway to develop such tools for regulatory purposes, focusing on non-EATS modalities of high concern (i.e., retinoic acid, aryl hydrocarbon receptor, peroxisome proliferator-activated receptor, and glucocorticoid signaling). Two case studies are presented with strong evidence amongst animals and human studies for non-EATS disruption and associations with wildlife and human disease. This includes metabolic syndrome and insulin signaling (case study 1) and chemicals that impact the cardiovascular system (case study 2). This is relevant as obesity and cardiovascular disease represent two of the most significant health-related crises of our time. Lastly, emerging topics related to EDCs are discussed, including recognition of crosstalk between the EATS and non-EATS axis, complex mixtures containing a variety of EDCs, adverse outcome pathways for chemicals acting through non-EATS mechanisms, and novel models for testing chemicals. Recommendations and considerations for evaluating non-EATS modalities are proposed. Moving forward, improved understanding of the non-EATS modalities will lead to integrated testing strategies that can be used in regulatory bodies to protect environmental, animal, and human health from harmful environmental chemicals.

Biomarker-assisted assessment of aquatic health using the cosmopolitan common carp, Cyprinus carpio (L): a case study of bisphenol-A exposures

Monitoring aquatic health from environmental pollutants is critical, none more so than bisphenol-A (BPA), a ubiquitous endocrine-disrupting chemical (EDC). The present study brings out the responses of selected transcripts, hormone levels, and tissue histomorphology in a widely distributed fish species Cyprinus carpio (Linn.), following exposure to environmentally relevant (10, 100 ng/L) and higher (1000 ng/L) concentration of BPA. The response of cyp19a1a, cyp19a1b, and c3 significantly decreased, while that of vtg increased in their respective tissue domains. The hematological parameters TEC, Hb, and Hct decreased significantly in contrast to TLC (p < 0.05) at all exposure concentrations, whereas none of the erythrocytic indices (MCV, MCH, and MCHC) was perturbed. The steroidogenic hormone levels, such as estradiol and progesterone, increased significantly with increasing BPA concentrations. In contrast, the testosterone and all the thyroid hormones (T₃, T₄, and TSH) were suppressed significantly (p < 0.05). At the histological level, the BPA induced chondrocyte proliferation, which was accompanied by hemorrhage of the gill lamellae, increased melanomacrophagic centers (MMCs), and degeneration of tubules and fluid accumulation in the kidney. In parallel, binucleated hepatocytes and inflammations were prominent in the liver. Collectively, the histomorphology confirmed induction of degenerative effects in all the tissues investigated, while the cyclic responses of biochemical markers suggest an ability to regulate the impacts. However, a chronic exposure could result in overriding the endemic reproductive pathways with potential population-level effects. In conclusion, the study identified multiple molecular, cellular, and physiological markers that could be employed to detect early signs of BPA and more broadly EDC exposures. These markers in combination with a wide distribution of C. carpio should allow comparative studies of pollutants at environmental concentrations.

Endocrine-Disrupting Chemicals and Their Adverse Effects on the Endoplasmic Reticulum

There is growing concern regarding the health and safety issues of endocrine-disrupting chemicals (EDCs). Long-term exposure to EDCs has serious adverse health effects through both hormone-direct and hormone-indirect ways. Accordingly, some EDCs can be a pathogen and an inducer to the susceptibility of disease, even if they have a very low affinity on the estrogen receptor, or no estrogenic effect. Endoplasmic reticulum (ER) stress recently attracted attention in this research area. Because ER and ER stress could be key regulators of the EDC’s adverse effects, such as the malfunction of the organ, as well as the death, apoptosis, and proliferation of a cell. In this review, we focused on finding evidence which shows that EDCs could be a trigger for ER stress and provide specific examples of EDCs, which are known to cause ER stress currently.

Development and Application of Multidimensional Lipid Libraries to Investigate Lipidomic Dysregulation Related to Smoke Inhalation Injury Severity

The implication of lipid dysregulation in diseases, toxic exposure outcomes, and inflammation has brought great interest to lipidomic studies. However, lipids have proven to be analytically challenging due to their highly isomeric nature and vast concentration ranges in biological matrices. Therefore, multidimensional techniques such as those integrating liquid chromatography, ion mobility spectrometry, collision-induced dissociation, and mass spectrometry (LC-IMS-CID-MS) have been implemented to separate lipid isomers as well as provide structural information and increased identification confidence. These data sets are however extremely large and complex, resulting in challenges for data processing and annotation. Here, we have overcome these challenges by developing sample-specific multidimensional lipid libraries using the freely available software Skyline. Specifically, the human plasma library developed for this work contains over 500 unique lipids and is combined with adapted Skyline functions such as indexed retention time (iRT) for retention time prediction and IMS drift time filtering for enhanced selectivity. For comparison with other studies, this database was used to annotate LC-IMS-CID-MS data from a NIST SRM 1950 extract. The same workflow was then utilized to assess plasma and bronchoalveolar lavage fluid (BALF) samples from patients with varying degrees of smoke inhalation injury to identify lipid-based patient prognostic and diagnostic markers.

Role of Hepatocyte- and Macrophage-Specific PPARγ in Hepatotoxicity Induced by Diethylhexyl Phthalate in Mice

BACKGROUND

Phthalates may disturb metabolic homeostasis in the liver by interfering with the peroxisome proliferator-activated receptors (PPARs). However, the role of hepatic macrophages in the lipid metabolic dysregulation induced by diethylhexyl phthalate (DEHP) remains unclear.

OBJECTIVES

We aimed to evaluate the respective role of hepatocyte- and macrophage-specific PPARγ in the hepatotoxicity induced by DEHP.

METHODS

Wild-type (WT), hepatocyte-specific PPARγ knockout (Hep-KO), and macrophage-specific PPAR knockout (Mac-KO) mice were administered DEHP (625mg/kg body weight) by daily gavage for 28 d, followed by hepatotoxicity examination and macrophage analysis. RNA sequencing and lipid metabolomic analysis were used to characterize the molecular changes in mouse liver. Mouse bone marrow-derived macrophages (BMDMs) and human monocytic THP-1 cell-derived macrophages were used to investigate the mechanistic regulation of macrophages' polarization by DEHP and mono(2-ethylhexyl) phthalate (MEHP).

RESULTS

The levels of hepatic steatosis and triglyceride were significantly higher in the mice treated with DEHP compared with the control mice in the WT and Hep-KO model. Lipid accumulation induced by DEHP was notably attenuated in the Mac-KO mice, but M2-polarization of hepatic macrophages in the Mac-KO mice was significantly higher compared with the WT mice under DEHP treatment. The M2-polarization of BMDMs and human macrophages was suppressed by DEHP and MEHP. Transcriptomic and lipidomic data suggested lower levels of lipid biosynthesis, fatty acid oxidation, and oxidative phosphorylation in the Mac-KO mice compared with the WT and Hep-KO mice under DEHP treatment.

CONCLUSIONS

Our data suggested that the orchestrated activation of PPARα and PPARγ by MEHP may reprogram hepatic macrophages' polarization, thereby affecting lipid homeostasis in the mouse liver. Although this conclusion was based on studies conducted in mice and in vitro, these findings may aid in elucidating the health effect of environmental phthalate exposure. https://doi.org/10.1289/EHP9373.

Trans-disciplinary diagnosis for an in-depth reform of regulatory expertise in the field of environmental toxicology and security

Repeated health and environmental scandals, the loss of biodiversity and the recent burst of chronic diseases constantly remind us the inability of public authorities and risk assessment agencies to protect health and the environment. After reviewing the main shortcomings of our evaluation system of chemicals and new technologies, supported by some concrete examples, we develop a number of proposals to reform both the risk assessment agencies and the evaluation processes. We especially propose the establishment of an independent structure, a High Authority of Expertise, supervising, either at European level or at national level, all the evaluation agencies, and ensuring the transparency, the methodology and the deontology of the expertise. In addition to modifying the evaluation protocols, both in their nature and in their content, especially in order to adapt them to current pollutants such as endocrine disruptors, we propose a reform of the expertise processes based on transparency, contradiction, and greater democracy, including close collaboration between the institutional and scientific parties on the one hand and the whole civil society on the other. All the proposals we make are inspired by the desire to prevent, through appropriate mechanisms, the human, health, ecological, but also economic consequences of contemporary technological choices.

Endocrine disrupting chemicals: Friend or foe to brown and beige adipose tissue?

The effects of Endocrine Disrupting Chemicals (EDCs) on the current obesity epidemic is a growing field of interest. Numerous EDCs have shown the potential to alter energy metabolism, which may increase the risk of obesity, in part, through direct actions on adipose tissue. While white adipose tissue has historically been the primary focus of this work, evidence of the EDC-induced disruption of brown and beige adipose tissues continues to build. Both brown and beige fat are thermogenic adipose depots rich in mitochondria that dispense heat when activated. Due to these properties, brown and beige fat are implicated in metabolic diseases such as obesity, diabetes, and cachexia. This review delves into the current literature of different EDCs, including bisphenols, dioxins, air pollutants, phthalates, and phytochemicals. The possible implications that these EDCs have on thermogenic adipose tissues are covered. This review also introduces the possibility of using brown and beige fat as a therapeutic target organ by taking advantage of some of the properties of EDCs. Collectively, we provide a comprehensive discussion of the evidence of EDC disruption in white, brown, and beige fat and highlight gaps worthy of further exploration.

Seasonally Related Disruption of Metabolism by Environmental Contaminants in Male Goldfish (Carassius auratus)

Endocrine disrupting chemicals mimic or disrupt action of the natural hormones, adversely impacting hormonal function as well as cardiovascular, reproductive, and metabolic health. Goldfish are seasonal breeders with an annual reproductive cycle regulated by neuroendocrine signaling which involves allocation of metabolic energy to sustain growth and reproduction. We hypothesize that seasonal changes in physiology alter overall vulnerability of goldfish to metabolic perturbation induced by environmental contaminants. In this study, we assess effects of endogenous hormones, individual contaminants and their mixture on metabolism of goldfish at different reproductive stages. Exposure effects were assessed using ¹H-NMR metabolomics profiling of male goldfish midbrain, gonad and liver harvested during early recrudescence (October), mid-recrudescence (February) and late recrudescence (June). Compounds assessed include bisphenol A, nonylphenol, bis(2-ethylhexyl) phthalate, fucosterol and a tertiary mixture (DEHP + NP + FS). Metabolome-level responses induced by contaminant exposure across tissues and seasons were benchmarked against responses induced by 17β-estradiol, testosterone and thyroid hormone (T3). We observe a clear seasonal dependence to metabolome-level alteration induced by hormone or contaminant exposures, with February (mid-recrudescence) the stage at which male goldfish are most vulnerable to metabolic perturbation. Responses induced by contaminant exposures differed from those induced by the natural hormones in a season-specific manner. Exposure to the tertiary mixture induced a functional gain at the level of biochemical pathways modeling over responses induced by individual components in select tissues and seasons. We demonstrate the importance of seasonally driven changes in physiology altering overall vulnerability of goldfish to metabolic perturbation induced by environmental contaminants, the relevance of which likely extends to other seasonally-breeding species.

Wild longnose dace downstream of wastewater treatment plants display an obese phenotype

Wild fish living downstream of wastewater treatment plants (WWTPs) often have increased body condition factors or body mass indices compared to upstream fish. This observation has been largely attributed to increased nutrient loading and food availability around wastewater effluent outflows. While a higher condition factor in fish is generally considered a predictor of healthy ecosystems, the metabolic status and capacity of the animals downstream of WWTPs may be a better predictor of fitness and potential population level effects. To address this, we sampled wild longnose dace (Rhinichthys cataractae), a native species in North American waterways, from sites upstream and downstream of WWTPs. Downstream fish had higher body mass indices, which corresponded with higher nutrient (lipid, protein, and glycogen) storage in somatic tissues compared to upstream fish. Liver transcriptome analysis revealed metabolic reprogramming favoring lipid synthesis, including higher hepatic triglyceride levels and transcript abundance of targeted lipogenic genes. This suggests that effluent exposure-mediated obesity in dace is a result of changes at the transcriptional level. To determine potential ecological consequences, we subjected these fish to an acute stressor in situ to determine their stress performance. Downstream fish failed to mobilize metabolites post-stress, and showed a reduction in liver aerobic and anaerobic metabolic capacity. Taken together, fish living downstream of WWTPs exhibit a greater lipid accumulation that results in metabolic disruption and may compromise the ability of these fish to cope with subsequent environmental and/or anthropogenic stressors.

A Comprehensive Assessment of Associations between Prenatal Phthalate Exposure and the Placental Transcriptomic Landscape

BACKGROUND

Phthalates are commonly used endocrine-disrupting chemicals that are ubiquitous in the general population. Prenatal phthalate exposure may alter placental physiology and fetal development, leading to adverse perinatal and childhood health outcomes.

OBJECTIVE

We examined associations between prenatal phthalate exposure in the second and third trimesters and the placental transcriptome at birth, including genes and long noncoding RNAs (lncRNAs), to gain insight into potential mechanisms of action during fetal development.

METHODS

The ECHO PATHWAYs consortium quantified 21 urinary phthalate metabolites from 760 women enrolled in the CANDLE study (Shelby County, TN) using high-performance liquid chromatography-tandem mass spectrometry. Placental transcriptomic data were obtained using paired-end RNA sequencing. Linear models were fitted to estimate separate associations between maternal urinary phthalate metabolite concentration during the second and third trimester and placental gene expression at birth, adjusted for confounding variables. Genes were considered differentially expressed at a Benjamini-Hochberg false discovery rate (FDR) p<0.05. Associations between phthalate metabolites and biological pathways were identified using self-contained gene set testing and considered significantly altered with an FDR-adjusted p<0.2.

RESULTS

We observed significant associations between second-trimester phthalate metabolites mono (carboxyisooctyl) phthalate (MCIOP), mono-2-ethyl-5-carboxypentyl phthalate, and mono-2-ethyl-5-oxohexyl phthalate and 18 genes in total, including four lncRNAs. Specifically, placental expression of NEAT1 was associated with multiple phthalate metabolites. Third-trimester MCIOP and mono-isobutyl phthalate concentrations were significantly associated with placental expression of 18 genes and two genes, respectively. Expression of genes within 27 biological pathways was associated with mono-methyl phthalate, MCIOP, and monoethyl phthalate concentrations.

DISCUSSION

To our knowledge, this is the first genome-wide assessment of the relationship between the placental transcriptome at birth and prenatal phthalate exposure in a large and diverse birth cohort. We identified numerous genes and lncRNAs associated with prenatal phthalate exposure. These associations mirror findings from other epidemiological and in vitro analyses and may provide insight into biological pathways affected in utero by phthalate exposure. https://doi.org/10.1289/EHP8973.

Probiotic Administration Mitigates Bisphenol A Reproductive Toxicity in Zebrafish

Although the use of bisphenol A (BPA) has been banned in a number of countries, its presence in the environment still creates health issues both for humans and wildlife. So far, BPA toxicity has been largely investigated on different biological processes, from reproduction to development, immune system, and metabolism. In zebrafish, Danio rerio, previous studies revealed the ability of environmentally relevant concentrations of this contaminant to significantly impair fertility via epigenetic modification. In addition, several studies demonstrated the ability of different probiotic strains to improve organism health. This study provides information on the role of the probiotic mixture SLAb51 to counteract adverse BPA effects on reproduction. A 28-day trial was set up with different experimental groups: BPA, exposed to 10 µg/L BPA; P, receiving a dietary supplementation of SLAb51 at a final concentration of 10⁹ CFU/g; BPA+P exposed to 10 µg/L BPA and receiving SLAb51 at a final concentration of 10⁹ CFU/g and a C group. Since oocyte growth and maturation represent key aspects for fertility in females, studies were performed on isolated class III (vitellogenic) and IV (in maturation) follicles and liver, with emphasis on the modulation of the different vitellogenin isoforms. In males, key signals regulating spermatogenesis were investigated. Results demonstrated that in fish exposed to the combination of BPA and probiotic, most of the transcripts were closer to C or P levels, supporting the hypothesis of SLAb51 to antagonize BPA toxicity. This study represents the first evidence related to the use of SLAb51 to improve reproduction and open new fields of investigation regarding its use to reduce endocrine disrupting compound impacts on health.

Microparticle formulations alter the toxicity of fenofibrate to the zebrafish Danio rerio embryo

A wide variety of active pharmaceutical ingredients are released into the environment and pose a threat to aquatic organisms. Drug products using micro- and nanoparticle technology can lower these emissions into the environment by their increased bioavailability to the human patients. However, due to this enhanced efficacy, micro- and nanoscale drug delivery systems can potentially display an even higher toxicity, and thus also pose a risk to non-target organisms. Fenofibrate is a lipid-regulating agent and exhibits species-related hazards in fish. The ecotoxic effects of a fenofibrate formulation embedded into a hydroxypropyl methylcellulose microparticle matrix, as well as those of the excipients used in the formulation process, were evaluated. To compare the effects of fenofibrate without a formulation, fenofibrate was dispersed in diluted ISO water alone or dissolved in the solvent DMF and then added to diluted ISO water. The effects of these various treatments were assessed using the fish embryo toxicity test, acridine orange staining and gene expression analysis assessed by quantitative RT polymerase chain reaction. Exposure concentrations were assessed by chemical analysis. The effect threshold concentrations of fenofibrate microparticle precipitates were higher compared to the formulation. Fenofibrate dispersed in 20%-ISO-water displayed the lowest toxicity. For the fenofibrate formulation as well as for fenofibrate added as a DMF solution, greater ecotoxic effects were observed in the zebrafish embryos. The chemical analysis of the solutions revealed that more fenofibrate was present in the samples with the fenofibrate formulation as well as fenofibrate added as a DMF solution compared to fenofibrate dispersed in diluted ISO water. This could explain the higher ecotoxicity. The toxic effects on the zebrafish embryo thus suggested that the formulation as well as the solvent increased the bioavailability of fenofibrate.

Zebrafish as the toxicant screening model: Transgenic and omics approaches

The production of large amounts of synthetic industrial and biomedical compounds, together with environmental pollutants, poses a risk to our ecosystem and induces negative effects on the health of wildlife and human beings. With the emergence of the global problem of chemical contamination, the adverse biological effects of these chemicals are gaining attention among the scientific communities, industry, governments, and the public. Among these chemicals, endocrine disrupting chemicals (EDCs) are regarded as one of the major global issues that potentially affecting our health. There is an urgent need of understanding the potential hazards of such chemicals. Zebrafish have been widely used in the aquatic toxicology. In this review, we first discuss the strategy of transgenic lines that used in the toxicological studies, followed by summarizing the current omics approaches (transcriptomics, proteomics, metabolomics, and epigenomics) on toxicities of EDCs in this model. We will also discuss the possible transgenerational effects in zebrafish and future prospective of the integrated omics approaches with customized transgenic organism. To conclude, we summarize the current findings in the field, and provide our opinions on future environmental toxicity research in the zebrafish model.

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

Non-alcoholic fatty liver disease (NAFLD) is considered the most common liver disorder, affecting around 25% of the population worldwide. It is a complex disease spectrum, closely linked with other conditions such as obesity, insulin resistance, type 2 diabetes mellitus, and metabolic syndrome, which may increase liver-related mortality. In light of this, numerous efforts have been carried out in recent years in order to clarify its pathogenesis and create new prevention strategies. Currently, the essential role of environmental pollutants in NAFLD development is recognized. Particularly, endocrine-disrupting chemicals (EDCs) have a notable influence. EDCs can be classified as natural (phytoestrogens, genistein, and coumestrol) or synthetic, and the latter ones can be further subdivided into industrial (dioxins, polychlorinated biphenyls, and alkylphenols), agricultural (pesticides, insecticides, herbicides, and fungicides), residential (phthalates, polybrominated biphenyls, and bisphenol A), and pharmaceutical (parabens). Several experimental models have proposed a mechanism involving this group of substances with the disruption of hepatic metabolism, which promotes NAFLD. These include an imbalance between lipid influx/efflux in the liver, mitochondrial dysfunction, liver inflammation, and epigenetic reprogramming. It can be concluded that exposure to EDCs might play a crucial role in NAFLD initiation and evolution. However, further investigations supporting these effects in humans are required.

Cross-species physiological interactions of endocrine disrupting chemicals with the circadian clock

Endocrine disrupting chemicals (EDCs) are endocrine-active chemical pollutants that disrupt reproductive, neuroendocrine, cardiovascular and metabolic health across species. The circadian clock is a transcriptional oscillator responsible for entraining 24-hour rhythms of physiology, behavior and metabolism. Extensive bidirectional cross talk exists between circadian and endocrine systems and circadian rhythmicity is present at all levels of endocrine control, from synthesis and release of hormones, to sensitivity of target tissues to hormone action. In mammals, a range of hormones directly alter clock gene expression and circadian physiology via nuclear receptor (NR) binding and subsequent genomic action, modulating physiological processes such as nutrient and energy metabolism, stress response, reproductive physiology and circadian behavioral rhythms. The potential for EDCs to perturb circadian clocks or circadian-driven physiology is not well characterized. For this reason, we explore evidence for parallel endocrine and circadian disruption following EDC exposure across species. In the reviewed studies, EDCs dysregulated core clock and circadian rhythm network gene expression in brain and peripheral organs, and altered circadian reproductive, behavioral and metabolic rhythms. Circadian impacts occurred in parallel to endocrine and metabolic alterations such as impaired fertility and dysregulated metabolic and energetic homeostasis. Further research is warranted to understand the nature of interaction between circadian and endocrine systems in mediating physiological effects of EDC exposure at environmental levels.

Effects of endocrine disrupting chemicals on myelin development and diseases

In the central and peripheral nervous systems, myelin is essential for efficient conduction of action potentials. During development, oligodendrocytes and Schwann cells differentiate and ensure axon myelination, and disruption of these processes can contribute to neurodevelopmental disorders. In adults, demyelination can lead to important disabilities, and recovery capacities by remyelination often decrease with disease progression. Among environmental chemical pollutants, endocrine disrupting chemicals (EDCs) are of major concern for human health and are notably suspected to participate in neurodevelopmental and neurodegenerative diseases. In this review, we have combined the current knowledge on EDCs impacts on myelin including several persistent organic pollutants, bisphenol A, triclosan, heavy metals, pesticides, and nicotine. Besides, we presented several other endocrine modulators, including pharmaceuticals and the phytoestrogen genistein, some of which are candidates for treating demyelinating conditions but could also be deleterious as contaminants. The direct impacts of EDCs on myelinating cells were considered as well as their indirect consequences on myelin, particularly on immune mechanisms associated with demyelinating conditions. More studies are needed to describe the effects of these compounds and to further understand the underlying mechanisms in relation to the potential for endocrine disruption.

An integrated approach to evaluate port sediment quality: From chemical characterization to multispecies bioassays

Management of dredged sediments results in an environmental and social cost. Based on their level of contamination, they can be intended for beach nourishment or for alternative uses. Sediment quality is established considering their specific chemical contamination level and setting up bioassays to evaluate their toxic effects on living organisms. The integration of these different Line of Evidence (LOE) generates toxicity indexes, the Hazard Chemical Quotient (HQc), and the Hazard Ecotoxicological Quotient (HQe), which are further elaborated using the SediQualSoft software, finally providing evidence on the levels of sediment contamination. In this study, four different dredged sediments were analysed. Except for one, which was sampled in a reference area, the others were assigned to the same class of toxicity, despite they presented different levels of chemical and ecotoxicological toxicity. As a novelty, this study introduces transcriptomics as a new LOE, to provide a new tool to better categorize sediment toxicity. C. gigas embryos were exposed to sediment elutriates, sampled at 5 and 18 h post-fertilization (hpf), and the expression of a set of genes involved in immune and stress response (hsp70, gpx, sod, dehf1, galectin, lysozyme, tg) was analysed by Real-time PCR. Molecular results suggested that the 18 hpf stage represents a sensitive window of exposure during development and can be suggested as a critical time point for ecotoxicity studies. Finally, by multivariate statistical analysis, integrating the well-established LOEs with molecular data, it was demonstrated that transcriptomics could be a useful and novel LOE with the ability to provide greater accuracy in the assessment of sediment toxicity.

Acute and chronic effects of environmental realistic concentrations of clofibric acid in Danio rerio: Behaviour, oxidative stress, biotransformation and lipid peroxidation endpoints

Due to their widespread use, pharmaceuticals can be metabolized, excreted and ultimately discarded in the environment, thereby affecting aquatic organisms. Lipid-regulating drugs are among the most prescribed medications around the world, controlling human cholesterol levels, in more than 20 million patients. Despite this growing use of lipid-regulating drugs, particularly those whose active metabolite is clofibric acid, the potential toxicological effects of these pharmaceuticals in the environment is not fully characterized. This work intended to characterize the toxicity of an acute (120 hours post-fertilization) and chronic (60 days post-fertilization) exposures to clofibric acid in concentrations of 10.35, 20.7, 41.4, 82.8, and 165.6 μg L^-1 in zebrafish (Danio rerio). The concentrations which were implemented in both exposures were based on predicted environmental concentrations for Portuguese surface waters. The acute effects were analysed focusing on behavioural endpoints (small and large distance travelled, swimming time and total distance travelled), biomarkers of oxidative stress (activity of the enzymes superoxide dismutase, Cu/Zn- and Mn SOD; catalase, CAT; glutathione peroxidase, Se- and total GPx), biotransformation (activity of glutathione S-transferases, GSTs) and lipid peroxidation (thiobarbituric acid reactive substances, TBARS). Chronically exposed individuals were also histologically analysed for sex determination and gonadal developmental stages. In terms of acute exposure, significant alterations were reported, in terms of behavioural alterations (hypoactivity), followed by an overall increase in all tested biomarkers. Chronically exposed organisms did not show alterations in terms of sex ratio and maturation stages, suggesting that clofibric acid did not act as an endocrine disruptor. Moreover, the metabolism of clofibric acid resulted in increased levels of both forms of SOD activity, especially for animals exposed to higher levels of this drug. An increase of CAT activity was observed in fish exposed to low levels, and a decrease in those exposed to higher amounts of clofibric acid. Both GPx forms had their activities increased. The enzyme of biotransformation GSTs were increased at low levels of clofibric acid but inhibited at higher amounts of this substance. Lipid peroxidation levels were also changed, with an induction of this parameter with increasing amounts of clofibric acid. Changes also occurred in behavioural endpoints and patterns for control organisms and for those exposed to clofibric acid were significantly distinct, for all types (light and darkness) of exposure, and for the two analysed endpoints (small and large distance). Results from this assay allow inferring that clofibric acid can have an ecologically relevant impact in living organisms exposed to this substance, with putative effects on the metabolism of individuals, affecting their behaviour and ultimately their survival.

Metabolism-Disrupting Chemicals and the Constitutive Androstane Receptor CAR

During the last two decades, the constitutive androstane receptor (CAR; NR1I3) has emerged as a master activator of drug- and xenobiotic-metabolizing enzymes and transporters that govern the clearance of both exogenous and endogenous small molecules. Recent studies indicate that CAR participates, together with other nuclear receptors (NRs) and transcription factors, in regulation of hepatic glucose and lipid metabolism, hepatocyte communication, proliferation and toxicity, and liver tumor development in rodents. Endocrine-disrupting chemicals (EDCs) constitute a wide range of persistent organic compounds that have been associated with aberrations of hormone-dependent physiological processes. Their adverse health effects include metabolic alterations such as diabetes, obesity, and fatty liver disease in animal models and humans exposed to EDCs. As numerous xenobiotics can activate CAR, its role in EDC-elicited adverse metabolic effects has gained much interest. Here, we review the key features and mechanisms of CAR as a xenobiotic-sensing receptor, species differences and selectivity of CAR ligands, contribution of CAR to regulation hepatic metabolism, and evidence for CAR-dependent EDC action therein.