Per- and Polyfluoroalkyl Substances Induces Salt-Sensitive Hypertension by Upregulating Epithelial Sodium Channel - The First Experimental Evidence Supporting Causality

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals found in the plasma of 98% of Americans. Epidemiological studies associate PFAS exposure with hypertension and kidney dysfunction, but causality and mechanisms remain unclear. We examined the effects of a mixture of 4 PFAS commonly detected in humans, including PFOA, PFOS, PFHxS, and PFNA, on blood pressure, salt sensitivity, and renal injury in 129S6 mice. Exposure to a lower dose for 3 weeks produced plasma PFAS levels in mice resembling occupational and regional environmental exposures; while a upper dose achieved levels similar to PFAS production workers. PFAS induced dose-dependent pressor effects in male but not female mice on a 0.4% low salt diet. During 4% high salt feeding, PFAS induced greater salt-sensitive hypertension in male mice, accompanied by glomerulopathy, interstitial fibrosis, and a trend towards increased albuminuria. Pressor effects were independent of plasma norepinephrine. Single-cell RNA sequencing of kidneys revealed most transcriptional changes in proximal tubule, thick ascending limb, and collecting duct, with enrichment of pathways in cholesterol synthesis, mitochondria respiration, ATP production, and transmembrane transporter activity. PFAS markedly increased the mRNA and protein of the pore-forming α subunit of epithelial sodium channel (αENaC), with no change in βENaC and a slight reduction in γENaC protein. Elevated αENaC coincided with a 30% decrease in Nedd4-2 phosphorylation (Ser448), suggesting reduced ENaC ubiquitination and degradation. However, protein expression of α1 Na+-K+-ATPase and serum- and glucocorticoid-regulated kinase 1 (SGK1) as well as SGK1 phosphorylation (Ser78) were unaltered. Amiloride abolished salt-induced hypertension in lower-dose mice but only partially corrected hypertension in the upper dose group. Taken together, our results provide causal evidence that PFAS exposure promotes hypertension, salt sensitivity, and kidney injury via renal epithelial mechanisms, supporting and extending human epidemiologic observations.