PFAS Induces Salt-Sensitive Hypertension Through Epithelial Sodium Channel in Mice

Per- and polyfluoroalkyl substances (PFAS) are a large class of environmental chemicals found in the plasma of 98% of Americans. PFAS exposure is associated with hypertension (HTN) and kidney dysfunction in epidemiological studies, but the causal effect has not been established. We investigated the effects of a mixture of 4 PFAS species most abundant in human blood, at exposure levels observed in humans, on blood pressure (BP), salt sensitivity, and renal injury in 129S6 mice. Exposure to a PFAS lower dose (18.8 μg/kg/day) and an upper dose (1.88 mg/kg/day) in drinking water for 3 weeks elevated plasma PFAS levels (perfluorooctanoic acid in μg/mL: no PFAS control 0.006 ± 0.004, lower dose 1.47 ± 0.36, upper dose 39.65 ± 6.21, p<0.01), comparable to those seen in the general population and occupationally exposed groups, respectively. PFAS induced dose-dependent pressor effects in male but not female mice on a 0.4% low salt diet. In response to 4% high salt diet for 7 days, PFAS augmented salt sensitive (SS)HTN in male mice (SBP increases in mmHg, Male: Ctrl 6.0±1.3, lower dose 9.2±1.6, upper dose 10.7±1.5; Female: Ctrl 1.6±2.0, lower dose 1.8±1.8, upper dose 7.0±1.5, 2-way ANOVA p exposure <0.05; p sex <0.01). PFAS-induced SSHTN in male mice was accompanied by striking interstitial fibrosis and albuminuria, indicative of hypertensive kidney damage. Single-cell RNAseq identified the most differentially expressed genes in the proximal tubule, thick ascending limb and collecting duct of PFAS exposed male mice, with top enriched pathways in transmembrane transporter activity and mitochondria respiration/metabolism. PFAS markedly downregulated Slc9a3 (Na + -H + exchanger 3) but upregulated Scnn1a encoding the pore-forming α subunit of the epithelial sodium channel (ENaC). There was no change in Slc12a1, Slc12a3, Scnn1b or Scnn1g in scRNAseq or rtPCR analyses. In cultured mCCDcl1 cells, 24-hour incubation with PFAS at 90 ng/mL induced amiloride-sensitive transepithelial currents. Amiloride at 10 mg/kg/day completely abolished salt-induced BP elevation in control and the lower dose groups (SBP reductions in mmHg, -7.3±1.4 vs -12.2±1.9, p<0.01), but only partially reduced BP in the upper dose group (-4.4±1.5), supporting a role of ENaC in PFAS-induced SSHTN but additional mechanisms may be involved. To our knowledge, this is the first mechanistic evidence supporting a causal role of PFAS exposure in the pathogenesis of HTN, salt sensitivity of BP, and kidney damage.