Comparative study on gene expression profiles in the liver of male neonatal mice prenatally exposed to PFOA and its alternative HFPO-DA.

Hexafluoropropylene oxide dimer acid (HFPO-DA), which belongs to the class of perfluoroalkyl ether carboxylic acid (PFECA), is a new alternative to perfluorooctanoic acid (PFOA). However, whether HFPO-DA is a safer alternative to PFOA in neonates remains unclear. In this study, we evaluated neonatal hepatic toxicity on postnatal days 9-10 by orally exposing pregnant CD-1 mice to 0.3 or 3.0 mg/kg/day (low or high doses) of HFPO-DA or PFOA from gestation days 15-17. The results showed that exposure of pregnant mice to HFPO-DA and PFOA induced similar phenotypic effects, including significant decreases in neonatal body weight (BW) and significant increases in liver weight relative to BW in the high-dose. Notably, HFPO-DA exposure significantly decreased in neonatal BW in the low-dose group, whereas PFOA did not. Comprehensive gene expression analysis revealed significant alterations in 408 and 1402 differentially expressed genes (DEGs) in the liver of neonates from the low- and high-dose HFPO-DA groups, respectively, while PFOA significantly altered 0 and 292 DEGs in the corresponding groups. Gene set enrichment analysis indicated that the DEGs induced by HFPO-DA and PFOA were enriched in pathway related to "PPAR signaling", "fatty acid metabolism", and "biological oxidations". In addition, transactivation assays revealed that mouse (m)PPARα and mPPARγ activity of HFPO-DA exceeds that of PFOA and molecular docking simulations analysis predicted that the binding conformation differ between PFOA and HFPO-DA. Overall, our findings demonstrate that HFPO-DA consistently affected neonatal phenotypes, liver gene expression and the molecular initiating events involving PPARα/γ, at lower concentrations than PFOA.