Evaluation of Transcriptomic Responses in Livers of Mice Exposed to the Short-Chain PFAS Compound HFPO-DA

HFPO-DA (ammonium 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)-propanoate; CASRN 62037-80-3; trade name “GenX”) is an alternative to environmentally persistent per- and poly-fluorinated alkyl substances (PFAS). The liver is the primary target of toxicity for HFPO-DA in rodents and previous examination of hepatic transcriptomic responses in mice following oral exposure to HFPO-DA for 90 days showed induction of peroxisome proliferator-activated receptor (PPAR) signaling pathways, predominantly by PPAR alpha, as well as increased gene expression of both peroxisomal and mitochondrial fatty acid metabolism. To further investigate the mechanism of liver toxicity, transcriptomic analysis was conducted on liver tissue from mice orally exposed to 0, 0.1, 0.5 or 5 mg/kg-bw/day HFPO-DA in a reproduction/developmental toxicity study. Hepatic gene expression changes were consistent with the previous 90-day mouse study, demonstrating activation of the PPAR alpha signaling pathway. Peroxisomal and mitochondrial fatty acid beta-oxidation gene sets were enriched at lower HFPO-DA concentrations, and complement cascade, cell cycle and apoptosis related gene sets were enriched at higher HFPO-DA concentrations. These results support the reported histopathological findings in livers of mice from this study and indicate that these effects are mediated through rodent-specific PPAR alpha signaling mechanisms. Comparative gene expression profiling analysis of RNA-seq data from FFPE liver tissue of male and female CD1 mice orally exposed to 0, 0.1, 0.5 or 5 mg/kg-bw/day HFPO-DA (n= 5 per treatment group) once daily for a total of 84 – 85 or 53 – 65 doses in male or female mice, respectively.