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Prenatal arsenic exposure alters gene expression in the adult liver to a proinflammatory state contributing to accelerated atherosclerosis.

ABSTRACT: The mechanisms by which environmental toxicants alter developmental processes predisposing individuals to adult onset chronic disease are not well-understood. Transplacental arsenic exposure promotes atherogenesis in apolipoprotein E-knockout (ApoE(-/-)) mice. Because the liver plays a central role in atherosclerosis, diabetes and metabolic syndrome, we hypothesized that accelerated atherosclerosis may be linked to altered hepatic development. This hypothesis was tested in ApoE(-/-) mice exposed to 49 ppm arsenic in utero from gestational day (GD) 8 to term. GD18 hepatic arsenic was 1.2 µg/g in dams and 350 ng/g in fetuses. The hepatic transcriptome was evaluated by microarray analysis to assess mRNA and microRNA abundance in control and exposed pups at postnatal day (PND) 1 and PND70. Arsenic exposure altered postnatal developmental trajectory of mRNA and microRNA profiles. We identified an arsenic exposure related 51-gene signature at PND1 and PND70 with several hubs of interaction (Hspa8, IgM and Hnf4a). Gene ontology (GO) annotation analyses indicated that pathways for gluconeogenesis and glycolysis were suppressed in exposed pups at PND1, and pathways for protein export, ribosome, antigen processing and presentation, and complement and coagulation cascades were induced by PND70. Promoter analysis of differentially-expressed transcripts identified enriched transcription factor binding sites and clustering to common regulatory sites. SREBP1 binding sites were identified in about 16% of PND70 differentially-expressed genes. Western blot analysis confirmed changes in the liver at PND70 that included increases of heat shock protein 70 (Hspa8) and active SREBP1. Plasma AST and ALT levels were increased at PND70. These results suggest that transplacental arsenic exposure alters developmental programming in fetal liver, leading to an enduring stress and proinflammatory response postnatally that may contribute to early onset of atherosclerosis. Genes containing SREBP1 binding sites also suggest pathways for diabetes mellitus and rheumatoid arthritis, both diseases that contribute to increased cardiovascular disease in humans.

SUBMITTER: States JC

PROVIDER: S-EPMC3376138 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Prenatal arsenic exposure alters gene expression in the adult liver to a proinflammatory state contributing to accelerated atherosclerosis.

States J Christopher JC Singh Amar V AV Knudsen Thomas B TB Rouchka Eric C EC Ngalame Ntube O NO Arteel Gavin E GE Piao Yulan Y Ko Minoru S H MS

PloS one 20120615 6

The mechanisms by which environmental toxicants alter developmental processes predisposing individuals to adult onset chronic disease are not well-understood. Transplacental arsenic exposure promotes atherogenesis in apolipoprotein E-knockout (ApoE(-/-)) mice. Because the liver plays a central role in atherosclerosis, diabetes and metabolic syndrome, we hypothesized that accelerated atherosclerosis may be linked to altered hepatic development. This hypothesis was tested in ApoE(-/-) mice exposed ...[more]

PMID: 22719926

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Project description:Developmental exposures play a role in adult onset chronic disease. The mechanisms by which environmental toxicants alter developmental processes predisposing individuals to chronic disease are not understood. arsenic exposure via drinking water causes cancer and cardiovascular disease. Transplacental arsenic exposure accelerates and exacerbates atherosclerosis in ApoE-knockout mice. The liver plays a central role in the interlinked diseases diabetes, metabolic syndrome and atherosclerosis. The hypothesis that accelerated atherosclerosis is a consequence of altered hepatic development was investigated by microarray profiling of mRNA and microRNA abundance in livers isolated from 10 week old (PND70) and newborn (PND1) mice exposed or not exposed to arsenic from day 8 post-fertilization to birth. The results show that arsenic exposure alters the trajectory of both mRNA and microRNA expression as mice age. A 51-gene signature of arsenic exposure in both PND1 and PND70 mice was identified. Pathway Architect analysis of this signature identified nodes of interaction including Hspa8, IgM and Hnf4a. Gene ontology analysis of arsenic exposure-altered mRNAs indicated that pathways for gluconeogenesis and glycolysis were suppressed in PND1 mice and pathways for protein export, ribosome, antigen processing and presentation, and complement and coagulation cascades were induced in PND70 mice. Analysis of promoters of differentially expressed genes identified enriched transcription factor binding sites and cluster analyses revealed groups of genes sharing sets of transcription factor binding sites suggesting common regulation. Srebp1 binding sites are present in ~1/6 of the genes differentially expressed in PND70 livers. Western blot analyses of PND70 liver proteins showed that the inducible form of heat shock protein 70 (Hspa1, Hsp70) and the active form of Srebp1 were induced in arsenic-exposed mice as were plasma AST and ALT levels. These results suggest that transplacental ar Samples from three frozen livers from each group (newborn exposed and unexposed, 10 week old exposed and unexposed), and from separate litters, were homogenized and total RNA purified using mirVANA RNA pufification kits (Ambion, Carlsbad, CA). RNA was quantitated and intergrity determined on a Nanochip using a Bioanalyzer (Agilent, Santa Clara, CA). Microarray analyses for miRNAs abundance in total liver RNAs was performed by Exiqon (Woburn, MA) using two-color design against mouse standard total RNA (Ambion, now part of Applied Biosystems) and Exiqon LNA 1500 microarrays. Microarray analyses for mRNA abundance was performed using 2 color design against mouse standard total RNA (Stratgene, LaJolla, CA) and 44k arrays produced at the NIA . The processed data on Exiqon LNA-1500 are attached as a Series supplementary file. The data are based on the same samples as described in Agilent data submitted here. The supplementary data includes only the murine miRNA data on the array because these are the only data supplied by Exiqon. The relationship between GEO's sample names here (Agilent data) and column heads of spreadsheets (Exiqon data) are described in the first sheet of supplemental file: Project_Summary_Report_Heather_Miller_01042009_MTE.xls

Project description:Prenatal alcohol exposure (PAE) is associated with alterations in numerous physiological systems, including the stress and immune systems. We have previously shown that PAE increases the course and severity of arthritis in an adjuvant-induced arthritis (AA) model. While the molecular mechanisms underlying these effects are not fully known, changes in neural gene expression are emerging as important factors in the etiology of PAE effects. As the prefrontal cortex (PFC) and hippocampus (HPC) play key roles in neuroimmune function, PAE-induced alterations to their transcriptome may underlie abnormal steady-state functions and responses to immune challenge. This study examined brains from adult PAE and control females from our recent AA study to determine whether PAE causes long-term alterations in gene expression and whether these mediate the altered severity and course of arthritis in PAE females.Adult females from PAE, pair-fed (PF), and ad libitum-fed control (C) groups were injected with either saline or complete Freund's adjuvant. Animals were terminated at the peak of inflammation or during resolution (Days 16 and 39 postinjection, respectively); cohorts of saline-injected PAE, PF, and C females were terminated in parallel. Gene expression was analyzed in the PFC and HPC using whole-genome mRNA expression microarrays.Significant changes in gene expression in both the PFC and HPC were found in PAE compared to controls in response to ethanol exposure alone (saline-injected females), including genes involved in neurodevelopment, apoptosis, and energy metabolism. Moreover, in response to inflammation (adjuvant-injected females), PAE animals showed unique expression patterns, while failing to exhibit the activation of genes and regulators involved in the immune response observed in control and pair-fed animals.These results support the hypothesis that PAE affects neuroimmune function at the level of gene expression, demonstrating long-term effects of PAE on the central nervous system response under steady-state conditions and following an inflammatory insult.

Project description:Background: Prenatal alcohol exposure (PAE) is associated with alterations in numerous physiological systems, including the stress and immune systems. We have previously shown that PAE increases the course and severity of arthritis in an adjuvant-induced arthritis (AA) model. While the molecular mechanisms underlying these effects are not fully known, changes in neural gene expression are emerging as important factors in the etiology of PAE effects. As the prefrontal cortex (PFC) and hippocampus (HPC) play key roles in neuroimmune function, PAE-induced alterations to their transcriptome may underlie abnormal steady-state functions and responses to immune challenge. The current study examined brains from adult PAE and control females from our recent AA study to determine whether PAE causes long-term alterations in gene expression and whether these mediate the altered severity and course of arthritis in PAE females Methods: Adult females from PAE, pair-fed [PF], and ad libitum-fed control [C]) groups were injected with either saline or complete FreundM-bM-^@M-^Ys adjuvant. Animals were terminated at the peak of inflammation or during resolution (days 16 and 39 post-injection, respectively); cohorts of saline-injected PAE, PF and C females were terminated in parallel. Gene expression was analyzed in the PFC and HPC using whole genome mRNA expression microarrays. Results: Significant changes in gene expression in both the PFC and HPC were found in PAE compared to controls in response to ethanol exposure alone (saline-injected females), including genes involved in neurodevelopment, apoptosis, and energy metabolism. Moreover, in response to inflammation (adjuvant-injected females), PAE animals showed unique expression patterns, while failing to exhibit the activation of genes and regulators involved in the immune response observed in control and pair-fed animals. Conclusions: These results support the hypothesis that PAE affects neuroimmune function at the level of gene expression, demonstrating long-term effects of PAE on the CNS response under steady-state conditions and following an inflammatory insult. Key words: prenatal alcohol exposure (PAE), ethanol, inflammation, arthritis, gene expression, rat. 192 samples, including 20 hybridization replicates

Project description:The glucocorticoid system, which plays a critical role in a host of cellular functions including mood disorders and learning and memory, has been reported to be disrupted by arsenic. In previous work we have developed and characterized a prenatal moderate arsenic exposure (50ppb) model and identified several deficits in learning and memory and mood disorders, as well as alterations within the glucocorticoid receptor signaling system in the adolescent mouse. In these present studies we assessed the effects of arsenic on the glucocorticoid receptor (GR) pathway in both the placenta and the fetal brain in response at two critical periods, embryonic days 14 and 18. The focus of these studies was on the 11?-hydroxysteroid dehydrogenase enzymes (11?-HSD1 and 11?-HSD2) which play a key role in glucorticoid synthesis, as well as the expression and set point of the GR negative feedback regulation. Negative feedback regulation is established early in development. At E14 we found arsenic exposure significantly decreased expression of both protein and message in brain of GR and the 11?-HSD1, while 11?-HSD2 enzyme protein levels were increased but mRNA levels were decreased in the brain. These changes in brain protein continued into the E18 time point, but mRNA levels were no longer significantly altered. Placental HSD11B2 mRNA was not altered by arsenic treatment but protein levels were elevated at E14. GR placental protein levels were decreased at E18 in the arsenic exposed condition. This suggests that arsenic exposure may alter GR expression levels as a consequence of a prolonged developmental imbalance between 11?-HSD1 and 11?-HSD2 protein expression despite decreased 11HSDB2 mRNA. The suppression of GR and the failure to turn down 11?-HSD2 protein expression during fetal development may lead to an altered set point for GR signaling throughout adulthood. To our knowledge, these studies are the first to demonstrate that gestational exposure to moderate levels of arsenic results in altered fetal programming of the glucocorticoid system.

Project description:Background: Prenatal alcohol exposure (PAE) is associated with alterations in numerous physiological systems, including the stress and immune systems. We have previously shown that PAE increases the course and severity of arthritis in an adjuvant-induced arthritis (AA) model. While the molecular mechanisms underlying these effects are not fully known, changes in neural gene expression are emerging as important factors in the etiology of PAE effects. As the prefrontal cortex (PFC) and hippocampus (HPC) play key roles in neuroimmune function, PAE-induced alterations to their transcriptome may underlie abnormal steady-state functions and responses to immune challenge. The current study examined brains from adult PAE and control females from our recent AA study to determine whether PAE causes long-term alterations in gene expression and whether these mediate the altered severity and course of arthritis in PAE females Methods: Adult females from PAE, pair-fed [PF], and ad libitum-fed control [C]) groups were injected with either saline or complete Freund’s adjuvant. Animals were terminated at the peak of inflammation or during resolution (days 16 and 39 post-injection, respectively); cohorts of saline-injected PAE, PF and C females were terminated in parallel. Gene expression was analyzed in the PFC and HPC using whole genome mRNA expression microarrays. Results: Significant changes in gene expression in both the PFC and HPC were found in PAE compared to controls in response to ethanol exposure alone (saline-injected females), including genes involved in neurodevelopment, apoptosis, and energy metabolism. Moreover, in response to inflammation (adjuvant-injected females), PAE animals showed unique expression patterns, while failing to exhibit the activation of genes and regulators involved in the immune response observed in control and pair-fed animals. Conclusions: These results support the hypothesis that PAE affects neuroimmune function at the level of gene expression, demonstrating long-term effects of PAE on the CNS response under steady-state conditions and following an inflammatory insult. Key words: prenatal alcohol exposure (PAE), ethanol, inflammation, arthritis, gene expression, rat.

Dataset Information

Prenatal arsenic exposure alters gene expression in the adult liver to a proinflammatory state contributing to accelerated atherosclerosis.

Publications

Prenatal arsenic exposure alters gene expression in the adult liver to a proinflammatory state contributing to accelerated atherosclerosis.

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