We previously showed that increased epithelial sodium channel (ENaC) activity in endothelial cells induced by oxidized low-density lipoprotein (ox-LDL) contributes to vasculature dysfunction. Here, we investigated whether ENaC participates in the pathological process of atherosclerosis using LDL receptor-deficient (LDLr-/-) mice. Male C57BL/6 and LDLr-/- mice were fed a normal diet (ND) or high fat diet (HFD) for 10 weeks. Our data show that treatment of LDLr-/- mice with a specific ENaC blocker, benzamil, significantly decreased atherosclerotic lesion formation and expression of matrix metalloproteinase 2 (MMP2) and metalloproteinase 9 (MMP9) in aortic arteries. Furthermore, benzamil ameliorated HFD-induced impairment of aortic endothelium-dependent dilation by reducing expression of proinflammatory cytokines, including TNF-α, IL-1β, and IL-6 and production of adhesion molecules including VCAM-1 and ICAM-1 in both C57BL/6 and LDLr-/- mice fed with HFD. In addition, HFD significantly increased ENaC activity and the levels of serum lipids, including ox-LDL. Our in vitro data further demonstrated that exogenous ox-LDL significantly increased the production of TNF-α, IL-1β, IL-6, VCAM-1 and ICAM-1. This ox-LDL-induced increase in inflammatory cytokines and adhesion molecules was reversed by γ-ENaC silencing or by treatment with the cyclooxygenase-2 (COX-2) antagonist celecoxib. Benzamil inhibited HFD-induced increase in COX-2 expression in aortic tissue in both C57BL/6 and LDLr-/- mice, and γ-ENaC gene silencing attenuated ox-LDL-induced COX-2 expression in HUVECs. These data together suggest that HFD-induced activation of ENaC stimulates inflammatory signaling, thereby contributes to HFD-induced endothelial dysfunction and atherosclerotic lesion formation. Thus, targeting endothelial ENaC may be a promising strategy to halt atherogenesis.
Keywords: Atherosclerosis; ENaC; Inflammation; Ox-LDL.
Copyright © 2020 Elsevier B.V. All rights reserved.