Increased perfluorooctanesulfonic acid (PFOS) toxicity and accumulation is associated with perturbed DHA and prostaglandin metabolism and increased OATP-transporter expression
Perfluorooctanesulfonate (PFOS) is a widespread environmental pollutant with a long half-life and clearly negative outcomes on metabolic diseases such as fatty liver and diabetes. Male and female Cyp2b-null and humanized CYP2B6-transgenic (hCYP2B6-Tg) mice were treated with 0, 1, or 10 mg/kg/day PFOS for 21 days, and surprisingly it was found that PFOS was retained at greater concentrations in the serum and liver of hCYP2B6-Tg mice than Cyp2b-null mice with greater differences in the females. Thus, Cyp2b-null and hCYP2B6-Tg mice provide new models for investigating individual mechanisms for PFOS bioaccumulation and toxicity. Overt toxicity was greater in hCYP2B6-Tg mice (especially females) as measured by mortality; however, steato-sis occurred more readily in Cyp2b-null mice despite the lower PFOS liver concentrations. Tar-geted lipidomics and transcriptomics from PFOS treated Cyp2b-null and hCYP2B6-Tg mouse livers were performed and compared to PFOS retention and serum markers of toxicity by PCA. Several oxylipins, including prostaglandins, thromboxanes, and docosahexaenoic acid metabo-lites are associated or inversely associated with PFOS toxicity. Both lipidomics and tran-scriptomics indicate PFOS toxicity is associated with PPAR activity in all models. GO terms as-sociated with reduced steatosis were sexually dimorphic with lipid metabolism and transport increased in females and circadian rhythm associated genes increased in males. However, we can rule out that steatosis was initially protective from PFOS toxicity. Moreover, several transporters are associated with increased retention probably due to increased uptake. The strongest associa-tions are the organic anion transport proteins (Oatp1a4-6) genes and a long-chain fatty acid transport protein (fatp1), enriched in female hCYP2B6-Tg mice. PFOS uptake was also reduced in cultured murine hepatocytes by OATP inhibitors. The role of OATP1A6 and FATP1 in PFOS transport has not been tested. In summary, Cyp2b-null and hCYP2B6-Tg mice provided unique models for estimating the importance of novel mechanisms in PFOS retention and toxicity. Overall design: The goal of this experiment was to determine the gene expression differences between our Cyp2b-null and hCYP2B6-Tg mouse models that led to increased PFOS retention in the livers of hCYP2B6-Tg mice. The Cyp2b-null mouse model was generated via Crispr-Cas9 knockout, and the hCYP2B6-Tg mouse was generated on the null background by breeding it with a CYP2B6/2A13/2F1-transgenic mouse (Wei, 2012). Male and female Cyp2b-null and hCYP2B6-Tg mice were treated with 0, 1, or 10 mg/kg/day PFOS, and greater PFOS retention was observed in the hCYP2B6-Tg mice livers. Total RNA was then extracted  from 4 mouse livers in each group for RNA-seq. Differential gene expression analysis was performed to compare expression profiles betwen PFOS treatments within a genotype and across genotypes at each particular PFOS concentration.