Comparative Time Course Profiles of Phthalate Stereoisomers in Mice
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ABSTRACT: Analysis of gene expression level in a mouse tumorigenic phthalate, DEHP vs non-tumorigenic DNOP. The hypothesis tested in the present study was to identify early key event thresholds related to tumor outcomes in a two-year carcinogenicity bioassay. Our results highlight marked differences in the toxicity profiles of structurally similar phthalates and demonstrate quantitative relationships between early bioindicators and later tumor outcomes. Total RNA obtained from liver samples subjected to 30wk exposures of cont, DEHP, DNOP. Samples processed with Illumina Mouse WG 8-v 2.0 beadarrays. Gene profiles generated for the compounds support observed key events in mode-of-action for these phthalates.
Project description:Analysis of gene expression level in a mouse tumorigenic phthalate, DEHP vs non-tumorigenic DNOP. The hypothesis tested in the present study was to identify early key event thresholds related to tumor outcomes in a two-year carcinogenicity bioassay. Our results highlight marked differences in the toxicity profiles of structurally similar phthalates and demonstrate quantitative relationships between early bioindicators and later tumor outcomes.
Project description:Dibutyl phthalate (DBP), di-2-ethylhexyl phthalate (DEHP), and benzyl butyl phthalate (BBP) are three phthalates commonly found in consumer products, including the plastic coating of pharmaceuticals and personal care products. Folliculogenesis, a tightly regulated process occurring in the ovary, is the maturation of an immature primordial follicle to a mature antral follicle. Follicles house the oocyte and antral follicles specifically play a crucial role in ovarian steroidogenesis and ovulation. DBP, BBP, and DEHP have been associated with inhibited antral follicle growth in vitro, decreased ovulation rates in vitro, and decreased antral follicle counts in women. However, little is known about the effects of a three-phthalate mixture on antral follicles in vivo. The objective of this study was to evaluate the effects of a human relevant mixture of DBP, BBP, and DEHP on ovarian follicles through proteome profiling analysis. CD-1 female mice (60 days old) were pipet fed tocopherol stripped corn oil (vehicle control) only or a phthalate mixture (52% DBP, 36% DEHP, and 12% BBP dissolved in vehicle) which modeled human follicular fluid concentrations. The mice were treated with 32µg/kg/day (PHT Mix 32; cumulative estimate in general population) and 500µg/kg/day (PHT Mix 500; cumulative estimate in occupationally exposed individuals) for 10 consecutive days. Proteome profiling of antral follicles (>250µm) was performed via label-free tandem mass spectrometry. A total of 5,417 antral follicle proteins were identified in the three groups, of which 194 were differentially abundant between the vehicle and PHT Mix 32 group, and 136 between the vehicle and PHT Mix 500 group. Gene ontology analysis revealed that the two treatments of the phthalate mixture upregulate and downregulate distinctive processes, supporting non-monotonic effects of phthalates on the antral follicle proteome. Taken together, these results reveal that a human relevant mixture of DBP, BBP, and DEHP alters the antral follicle proteome and merits further evaluation to elucidate the molecular mechanisms by which phthalates cause negative reproductive outcomes.
Project description:Di(2-ethylhexyl) phthalate (DEHP; CAS No. 117-81-7) belongs to the phthalate class of chemicals, and is commonly added to plastics for flexibility. DEHP has been identified as an index compound for group-TDI calculations owing to its extensive toxicological dataset. Humans are exposed to this ubiquitous environmental contaminant through multiple routes. DEHP has been designated as probably and possibly carcinogenic to humans based on its ability to induce rodent carcinogenicity, although the relevance of its mode of action (MoA) in humans remains unclear. The aim of this study was to investigate the carcinogenic potential of DEHP using an alternative method and explore the possible mode and mechanisms of action at the molecular level. Special attention has been paid to DEHP dissolution in cell media, leading to the use of a final concentration of 0.5% DMSO. Transcriptomics were conducted on cells treated with a cytotoxic concentration of DEHP (19.7 µg/mL) for 24 h. The aim of the microarray experiment was to analyze the molecular effects of the substance under the specific conditions of the Cell Transformation Assay protocol (BALB c/ 3T3 clone A31-1-1 CTA, according to the method validated by ECVAM, Sasaki et al., 2012), in order to provide mechanistic explanations of the test results derived from the CTA.
Project description:Phthalates are industrial additives widely used as plasticizers. In addition to deleterious effects on male genital development, population studies have documented correlations between phthalates exposure and impacts on reproductive tract development and on the metabolic syndrome in male adults. In this study we investigated potential mechanisms underlying the impact of di-(2-ethylhexyl)-phthalate (DEHP) on adult mouse liver in vivo. A parallel analysis of hepatic transcript and metabolic profiles from adult mice exposed to varying DEHP doses was performed. Hepatic genes modulated by DEHP are predominantly PPARα targets. However, the induction of prototypic cytochrome P450 genes strongly supports the activation of additional NR pathways, including Constitutive Androstane Receptor (CAR). Integration of transcriptomic and metabonomic profiles revealed a correlation between the impacts of DEHP on genes and metabolites related to heme synthesis and on the Rev-erbα pathway that senses endogenous heme level. Keywords: Treatment effect One-color macroarrays, 4 experimental conditions: Control mice (vehicle treated), mice treated with di-(2-ethylhexyl)-phthalate (DEHP) at 30 mg/kg/day (D30), 180 mg/kg/day (D180) or 1100 mg/kg/day (D1100) for 14 days, Biological replicates: 6 controls, 4 D30, 4 D180, 5 D1100, One replicate per array
Project description:DEHP study Phthalate plasticizers are ubiquitous chemicals linked to several cardiovascular diseases in animal models and in humans. In spite of this, the mechanisms by which phthalate exposures cause adverse cardiac health outcomes are unclear. In particular, whether phthalate exposures during pregnancy interfere with normal developmental programming of the cardiovascular system, and the resulting implications this may have for long-term disease risk, are unknown. Recent studies suggest that the effects of phthalates on metabolic and neurobehavioral outcomes are sex-specific. However, the influence of sex on cardiac susceptibility to phthalate exposures has not been investigated. One mechanism by which developmental exposures may influence long-term health is through altered programming of DNA methylation. In this work, we utilized an established mouse model of human-relevant perinatal exposure and enhanced reduced representation bisulfite sequencing to investigate the long-term effects of diethylhexyl phthalate (DEHP) exposure on DNA methylation in the hearts of adult male and female offspring at 5 months of age (n=5-7 mice per sex and exposure). Perinatal DEHP exposure led to hundreds of sex-specific, differentially methylated cytosines (DMCs) and differentially methylated regions (DMRs) in the heart. Pathway analysis of DMCs revealed enrichment for several pathways in females, including insulin signaling, regulation of histone methylation, and tyrosine phosphatase activity. In males, DMCs were enriched for glucose transport, energy generation, and developmental programs. Notably many sex-specific genes differentially methylated with DEHP exposure in our mouse model were also differentially methylated in published data of heart tissues collected from human heart failure patients. Together these data highlight the potential role for DNA methylation in DEHP-induced cardiac effects, and emphasize the importance of sex as a biological variable in environmental health studies. Lead study Environmental factors play an important role in the etiology of cardiovascular diseases. Cardiovascular diseases exhibit marked sexual dimorphism; however, the sex-specific effects of environmental exposures on cardiac health are incompletely understood. Perinatal and adult exposures to the metal lead (Pb) are linked to several adverse cardiovascular outcomes, but the sex-specific effects of this toxicant on the heart have received little attention. Perinatal environmental exposures can lead to disease through disruption of the normal epigenetic programming that occurs during early development. Using a mouse model of human-relevant perinatal environmental exposure, we investigated the effects of exposure to Pb during gestation and lactation on DNA methylation in the hearts of adult offspring mice (n=6 per sex). Two weeks prior to mating, dams were assigned to control or Pb acetate (32 ppm) water, and exposure continued until offspring were weaned at 3 weeks of age. Enhanced reduced-representation bisulfite sequencing was used to measure DNA methylation in the hearts of offspring at 5 months of age. Although Pb exposure stopped at 3 weeks of age, we discovered hundreds of differentially methylated cytosines (DMCs) and regions (DMRs) in males and females at 5 months of age. DMCs/DMRs and their associated genes were sex-specific, with a small, but statistically significant subset overlapping between sexes. Pathway analysis revealed altered methylation of genes important for cardiac and other tissue development in males, and histone demethylation in females. Together, these data demonstrate that perinatal exposure to Pb induces sex-specific changes in cardiac DNA methylation that are present long after cessation of exposure, and highlight the importance of considering sex in environmental epigenetics and mechanistic toxicology studies.
Project description:Role of PPARalpha in the effects of DEHP on the hepatic expression of a selection of mouse genes related to nuclear receptor signaling. Di-(2-ethylhexyl)-phthalate (DEHP), a widely used plasticizer, is detected in consumerâs body fluids. Contamination occurs through environmental and food chain sources. In mouse liver, DEHP activates the peroxisome proliferator-activated receptor alpha (PPARalpha) and regulates the expression of its target genes. Several in vitro investigations support the simultaneous recruitment of additional nuclear receptor pathways. We investigated, in vivo, the hepatic impact of low doses of DEHP on PPARalpha activation, and the putative activation of additional signalling pathways. Wild-type and PPARalpha-deficient mice were exposed to different doses of DEHP. Gene expression profiling delineated the role of PPARalpha and revealed a PPARalpha-independent regulation of several prototypic Constitutive Androstane Receptor (CAR) target genes. This finding demonstrates that CAR also represents a transcriptional regulator sensitive to phthalates. CAR-mediated effects of DEHP provide a new rationale for most endpoints of phthalates toxicity described previously, including endocrine disruption, hepatocarcinogenesis and the metabolic syndrome. Keywords: Treatment effect One-color macroarrays, 6 experimental conditions: Wild type (WT) and PPARalpha-deficient mice (PPAR) were treated with vehicle (Ctrl) or with di-(2-ethylhexyl)-phthalate (DEHP) at 20 mg/kg/day (D20) or 200 mg/kg/day (D200) for 21 days, Biological replicates: 10 for each group, One replicate per array
Project description:Di (2-ethylhexyl) phthalate (DEHP) is a common plasticizer. Studies have revealed that DEHP exposure can cause liver damage. Green tea is one of the most popular beverages in China. Green tea polyphenols (GTPs) have been proven to have therapeutic effects on organ damage induced by heavy metal exposure. However, few study report on GTP relieving DEHP-induced liver damage.
Project description:Phthalates are ubiquitous pollutants in the environment; however, the mechanisms of phthalate-associated reproductive disorders in men are not fully understood. The aim of this study is to investigate associations between urinary phthalate metabolite concentrations and sperm DNA methylation. The study was conducted on 697 men from three prospective pregnancy cohorts: Longitudinal Investigation of Fertility and the Environment (LIFE) Study, Sperm Environmental Epigenetics and Development Study (SEEDS), and Environment and Reproductive Health (EARTH) Study.
Project description:Phthalates are industrial additives widely used as plasticizers. In addition to deleterious effects on male genital development, population studies have documented correlations between phthalates exposure and impacts on reproductive tract development and on the metabolic syndrome in male adults. In this study we investigated potential mechanisms underlying the impact of di-(2-ethylhexyl)-phthalate (DEHP) on adult mouse liver in vivo. A parallel analysis of hepatic transcript and metabolic profiles from adult mice exposed to varying DEHP doses was performed. Hepatic genes modulated by DEHP are predominantly PPARα targets. However, the induction of prototypic cytochrome P450 genes strongly supports the activation of additional NR pathways, including Constitutive Androstane Receptor (CAR). Integration of transcriptomic and metabonomic profiles revealed a correlation between the impacts of DEHP on genes and metabolites related to heme synthesis and on the Rev-erbα pathway that senses endogenous heme level. Keywords: Treatment effect
Project description:Phthalate esters, such as DEHP (bis(2-ethylhexyl) phthalate, are a ubiquitous class of chemicals used as plasticizers in plastic products such as toys and hospital supplies. They are not covalently bound to the polymer matrix and can leach out of products. The goal of this study is to determine whether DEHP adversely affect the zebrafish (Danio rerio) microbiome-gut axis, specifically gut transcriptome. We exposed the fish to 3 ppm DEHP via food for 8 weeks to stimulate chronic exposure. To identify genomic responses of DEHP in gut, we used microarrays followed by differential gene expression analysis. The data were then mapped to changes in cell processes and signaling pathways using Pathway Studio.