Developmental exposure to perfluorooctanoic acid (PFOA) or GenX disrupts biologic pathways in maternal and fetal liver in CD-1 mice

There is growing evidence that developmental exposure to per- and polyfluoroalkyl substances (PFAS) may program adult nonalcoholic fatty liver disease (NAFLD). We implemented whole-transcriptome gene expression analysis to investigate the molecular mechanisms of liver toxicity after developmental exposure to two different PFAS, perfluorooctanoic acid (PFOA) and its replacement, GenX. Pregnant CD-1 mice were exposed via daily oral gavage beginning on embryonic day (E) 1.5 to PFOA (0, 1, or 5 mg/kg) or GenX (0, 2, or 10 mg/kg) until euthanasia on E11.5 or E17.5. Maternal and fetal liver were collected, snap-frozen, and then processed for RNA isolation. Collected RNA (N=5 per dose/group) was run on Affymetrix Mouse Clariom D arrays, and data sets were normalized and evaluated for outliers. Differentially expressed genes (DEG; fold-change ≥ 1.5, p-value ≤ 0.05) and differentially enriched pathways (DEP; Normalized Pathway Enrichment score ≥ 1.5, p-value ≤ 0.05) were determined using Broad Institute’s Molecular Signature Database Hallmark Pathways. Ingenuity Pathway Analysis was used to identify key genes involved in the hallmark pathways. Alterations in multiple hallmark pathways were consistent across maternal and fetal liver at all doses tested for both PFOA and GenX. Upregulated DEPs identified across all dose and tissue groups included Fatty Acid Metabolism, Peroxisome, Oxidative Phosphorylation, Adipogenesis, and Bile Acid Metabolism. Key altered genes identified in these pathways included reduced cytochrome P450s (Cyp1a2, Cyp3a5), increased lipogenic and lipid transporter genes (Acaa1, Acsl1, Scp2, and Slc27a1), and increased estrogen reductase (Hsd17b7). These findings suggest the molecular mechanisms of liver toxicity are nearly identical for PFOA and GenX in both maternal and fetal livers in CD-1 mice and provide critical insight into pathways that may underlie developmental programming of adult NAFLD. The views expressed are those of the authors and do not necessarily represent the views or policies of the US EPA.

Impact/Purpose

This abstract will be presented as a poster at the 2021 U.S. Developmental Origins of Health and Disease (DOHaD) meeting. The work examines the gene expression changes and biological pathways disrupted in maternal and fetal/developing mouse livers after developmental exposure to two different per- and polyfluoroakyl substances (PFAS). PFAS are ubiquitous environmental contaminants and have been associated with increased risk for elevated liver enzymes in humans and non-alcoholic fatty liver disease (NAFLD) in mice. This work is important because it is the first to use whole-transcriptome gene expression analyses to investigate the biologic pathways altered in both maternal and fetal mouse livers after exposure to PFAS.  

Citation

Blake, B., T. Phan, H. Nguyen, C. Miller, D. Mav, R. Shah, D. Phadke, AND S. Fenton. Developmental exposure to perfluorooctanoic acid (PFOA) or GenX disrupts biologic pathways in maternal and fetal liver in CD-1 mice. U.S. Developmental Origins of Health and Disease, Durham, NC, November 07 - 09, 2021.