Amiloride attenuates lipopolysaccharide-accelerated atherosclerosis via inhibition of NHE1-dependent endothelial cell apoptosis

作者：Cui, Gui-mei; Zhao, Yu-xi; Zhang, Na-na; Liu, Zeng-shan; Sun, Wan-chun; Peng, Qi-sheng^*

来源：Acta Pharmacologica Sinica, 2013, 34(2): 231-238.

DOI：10.1038/aps.2012.155

• atherosclerosis
• lipopolysaccharide
• amiloride
• BAPTA
• ZLLal
• NHE1
• intracellular free Ca2+ level
• calpain
• human umbilical vein endothelial cell
• ApoE(-/-) mice

Aim: To investigate the effects of the potassium-sparing diuretic amiloride on endothelial cell apoptosis during lipopolysaccharide (LPS)-accelerated atherosclerosis. @@@ Methods: Human umbilical vein endothelial cells (HUVECs) were exposed to LPS (100 ng/mL) in the presence of drugs tested. The activity of Na+/H+ exchanger 1 (NHE1) and calpain, intracellular free Ca2+ level ([Ca2+](i)), as well as the expression of apoptosis-related proteins in the cells were measured. For in vivo study, ApoE-deficient (ApoE(-/-)) mice were fed high-fat diets with 0.5% (w/w) amiloride for 4 weeks and LPS (10 mu g/mouse) infusion into caudal veins. Afterwards, atherosclerotic lesions, NHE1 activity and Bcl-2 expression in the aortic tissues were evaluated. @@@ Results: LPS treatment increased NHE1 activity and [Ca2+](i) in HUVECs in a time-dependent manner, which was associated with increased activity of the Ca2+-dependent protease calpain. Amiloride (1-10 mu mol/L) significantly suppressed LPS-induced increases in NHE1 activity, [Ca2+](i). and calpain activity. In the presence of the Ca2+ chelator BAPTA (0.5 mmol/L), LPS-induced increase of calpain activity was also abolished. In LPS-treated HUVECs, the expression of Bcl-2 protein was significantly decreased without altering its mRNA level. In the presence of amiloride (10 mu mol/L) or the calpain inhibitor ZLLal (50 mu mol/L), the down-regulation of Bcl-2 protein by LPS was blocked. LPS treatment did not alter the expression of Bax and Bak proteins in HUVECs. In the presence of amiloride, BAPTA or ZLLal, LPS-induced HUVEC apoptosis was significantly attenuated. In ApoE(-/-) mice, administration of amiloride significantly suppressed LPS-accelerated atherosclerosis and LPS-induced increase of NHE1 activity, and reversed LPS-induced down-regulation of Bcl-2 expression. @@@ Conclusion: LPS stimulates NHE1 activity, increases[Ca2+](i), and activates calpain, which leads to endothelial cell apoptosis related to decreased Bcl-2 expression. Amiloride inhibits NHE1 activity, thus attenuates LPS-accelerated atherosclerosis in mice.

• 出版日期2013-2
• 单位吉林大学