Decrease of intracellular chloride concentration promotes endothelial cell inflammation by activating nuclear factor-κB pathway

Abstract

Recent evidence suggested that ClC-3 channel/antiporter is involved in regulation of nuclear factor (NF)-κB activation. However, the mechanism explaining how ClC-3 modulates NF-κB signaling is not well understood. We hypothesized that ClC-3-dependent alteration of intracellular chloride concentration ([Cl]i) underlies the effect of ClC-3 on NF-κB activity in endothelial cells. Here, we found that reduction of [Cl]i increased tumor necrosis factor-α (TNFα)-induced expression of intercellular adhesion molecule 1 and vascular cell adhesion molecule 1 and adhesion of monocytes to endothelial cells (P<0.05; n=6). In Cl reduced solutions, TNFα-evoked IκB kinase complex β and inhibitors of κBα phosphorylation, inhibitors of κBα degradation, and NF-κB nuclear translocation were enhanced. In addition, TNFα and interleukin 1β could activate an outward rectifying Cl current in human umbilical vein endothelial cells and mouse aortic endothelial cells. Knockdown or genetic deletion of ClC-3 inhibited or abolished this Cl conductance. Moreover, Cl channel blockers, ClC-3 knockdown or knockout remarkably reduced TNFα-induced intercellular adhesion molecule 1 and vascular cell adhesion molecule 1expression, monocytes to endothelial cell adhesion, and NF-κB activation (P<0.01; n=6). Furthermore, TNFα-induced vascular inflammation and neutrophil infiltration into the lung and liver were obviously attenuated in ClC-3 knockout mice (P<0.01; n=7). Our results demonstrated that decrease of [Cl]i induced by ClC-3-dependent Cl efflux promotes NF-κB activation and thus potentiates TNFα-induced vascular inflammation, suggesting that inhibition of ClC-3-dependent Cl current or modification of intracellular Cl content may be a novel therapeutic approach for inflammatory diseases. © 2012 American Heart Association, Inc.