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Exposure of Ldlr-/- mice to a PFAS mixture increased circulating cholesterol and decreased bile acid excretion with concurrent increases in male ileal ASBT

ABSTRACT: Background: Previous epidemiological studies have repeatedly found per- and polyfluoroalkyl substances (PFAS) exposure associated with higher circulating cholesterol, one of the greatest risk factors for development of coronary artery disease. The main route of cholesterol catabolism is through its conversion to bile acids, which circulate between the liver and ileum via enterohepatic circulation. Patients with coronary artery disease have decreased bile acid excretion, indicating that PFAS-induced changes of enterohepatic circulation may play a critical role in cardiovascular risk. Objectives: Using a mouse model with high LDL-VLDL cholesterol and aortic lesion development similar to humans, the current study investigates mechanisms linking exposure to a PFAS mixture with increased cholesterol. Methods: Male and female Ldlr-/- mice were fed an atherogenic diet (Clinton/Cybulsky low fat, 0.15% cholesterol) and exposed to a mixture of 5 PFAS representing legacy, replacement, and emerging subtypes (i.e., PFOA, PFOS, PFNA, PFHxS, GenX), each at a concentration of 2 mg/L, for 7 weeks. Blood was collected longitudinally for cholesterol measurements and mass spectrometry was used to measure circulating and fecal bile acids. Transcriptomic analysis of ileal samples was performed via RNA-sequencing. Results: After 7 weeks of PFAS exposure, average circulating PFAS levels were measured at 21.6, 20.1, 31.2, 23.5, and 1.5 µg/mL in PFAS-exposed females and 12.9, 9.7, 23, 14.3, and 1.7 µg/mL in PFAS-exposed males for PFOA, PFOS, PFHxS, PFNA, and GenX, respectively. PFAS exposure led to elevated circulating cholesterol levels after 7 weeks compared to vehicle mice, with females increasing 18% and males increasing 24%. Total circulating bile acid levels were elevated in PFAS-exposed mice by 230% in males and 290% in females compared to vehicle. PFAS decreased fecal bile acid levels by 62% in females and 59% in males. In the ileum, expression levels of the bile acid reuptake transporter ASBT were increased due to PFAS exposure. Discussion: Mice exposed to a PFAS mixture display increased circulating cholesterol and bile acids perhaps due to changes in enterohepatic circulation. This study implicates PFAS-mediated effects at the site of the ileum as a possible critical mediator of increased cardiovascular risk due to PFAS.

ORGANISM(S): Mus musculus

PROVIDER: GSE263158 | GEO | 2024/08/14

REPOSITORIES: GEO

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Project description:Morgan2016 - Dynamics of cholesterol metabolism and ageing This model is described in the article: Mathematically modelling the dynamics of cholesterol metabolism and ageing. Morgan AE, Mooney KM, Wilkinson SJ, Pickles NA, Mc Auley MT. BioSystems 2016 Jul; 145: 19-32 Abstract: Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in the UK. This condition becomes increasingly prevalent during ageing; 34.1% and 29.8% of males and females respectively, over 75 years of age have an underlying cardiovascular problem. The dysregulation of cholesterol metabolism is inextricably correlated with cardiovascular health and for this reason low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) are routinely used as biomarkers of CVD risk. The aim of this work was to use mathematical modelling to explore how cholesterol metabolism is affected by the ageing process. To do this we updated a previously published whole-body mathematical model of cholesterol metabolism to include an additional 96 mechanisms that are fundamental to this biological system. Additional mechanisms were added to cholesterol absorption, cholesterol synthesis, reverse cholesterol transport (RCT), bile acid synthesis, and their enterohepatic circulation. The sensitivity of the model was explored by the use of both local and global parameter scans. In addition, acute cholesterol feeding was used to explore the effectiveness of the regulatory mechanisms which are responsible for maintaining whole-body cholesterol balance. It was found that our model behaves as a hypo-responder to cholesterol feeding, while both the hepatic and intestinal pools of cholesterol increased significantly. The model was also used to explore the effects of ageing in tandem with three different cholesterol ester transfer protein (CETP) genotypes. Ageing in the presence of an atheroprotective CETP genotype, conferring low CETP activity, resulted in a 0.6% increase in LDL-C. In comparison, ageing with a genotype reflective of high CETP activity, resulted in a 1.6% increase in LDL-C. Thus, the model has illustrated the importance of CETP genotypes such as I405V, and their potential role in healthy ageing. This model is hosted on BioModels Database and identified by: MODEL1508170000. To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models. To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information.

Project description:Per- and polyfluoroalkyl substances (PFAS) are persistent pollutants known for their bio-accumulative properties and prevalence in water supplies and household products. Although legacy PFAS, such as perfluorooctanoic acid, are phased out in the U.S. due to public health concerns, a PFAS variant hexafluoropropylene oxide-dimer acid (HFPO-DA) is an emerging replacement. HFPO-DA is a potential neurotoxicant that has been shown to cause dopaminergic neurodegeneration. We investigated the bioaccumulative potential of HFPO-DA and its effects on lifespan, locomotor activity, and brain gene expression in female and male Drosophila melanogaster (fruit flies). Flies were collected less than 4 hours post-eclosion and exposed to 0, 10, 10^2, 10^3, or 10^4 mg/kg/day HFPO-DA. To measure the effect of HFPO-DA on lifespan, surviving flies from each exposure were recorded every 24 hours. Flies were subjected to a negative geotaxis assay at 3, 7, and 14 days of exposure to measure the effects of acute, sub-chronic, and chronic exposures on locomotor ability. To capture HFPO-DA-induced sexually dimorphic gene expression responses in the brain, we sequenced brain-specific mRNA from flies exposed for 3, 7, or 14 days. The Bioconcentration Factor was 0.031 for females, and 0.026 for males. Dose and median lifespan were negatively correlated in both female (R^2 adj = 0.77, p<0.0001) and male flies (R^2 adj = 0.77, p<0.0001). Log-rank Mantel-Cox tests and one-way ANOVAs revealed that median lifespan was reduced in females starting at 10 mg/kg/day and in males starting at 10^2 mg/kg/day (p< 0.01). Acute exposure at 10 mg/kg/day significantly decreased locomotor ability in females (p<0.0001) while acute exposures at 1 mg/kg/day decreased locomotor activity in males (p <0.0001). Among 7500 genes analyzed, pairwise gene expression comparison between controls and treatments identified 2496 differentially expressed genes. While HFPO-DA does not readily bioaccumulate in fruit fly bodies, high-dose exposures have sex-specific effects on lifespan, locomotor ability, and brain gene expression. LOAEL for median lifespan is 10 mg/kg/day in females, and 10^2 mg/kg/day in males. Both locomotor ability and brain gene expression exhibited non-conventional dose-response as seen in other endocrine disrupting chemical exposures.

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Exposure of Ldlr-/- mice to a PFAS mixture increased circulating cholesterol and decreased bile acid excretion with concurrent increases in male ileal ASBT

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