ABSTRACT
Atherosclerosis preferentially occurs in areas with low shear stress (LSS) and oscillatory flow. LSS has been demonstrated to correlate with the development of atherosclerosis. The sphingosine 1-phosphate receptor 1 (S1PR1), involving intravascular blood flow sensing, regulates vascular development and vascular barrier function. However, whether LSS affects atherosclerosis via regulating S1PR1 remains incompletely clear. In this study, immunostaining results of F-actin, ß-catenin, and VE-cadherin indicated that LSS impaired endothelial barrier function in human umbilical vein endothelial cells (HUVECs). Western blot analysis showed that LSS resulted in blockage of autophagic flux in HUVECs. In addition, autophagy agonist Rapamycin (Rapa) antagonized LSS-induced endothelial barrier dysfunction, whereas autophagic flux inhibitor Bafilomycin A1 (BafA1) exacerbated it, indicating that LSS promoted endothelial barrier dysfunction by triggering autophagic flux blockage. Notably, gene expression analysis revealed that LSS downregulated S1PR1 expression, which was antagonized by Rapa. Selective S1PR1 antagonist W146 impaired endothelial barrier function of HUVECs under high shear stress (HSS) conditions. Moreover, our data showed that expression of GAPARAPL2, a member of autophagy-related gene 8 (Atg8) proteins, was decreased in HUVECs under LSS conditions. Autophagic flux blockage induced by GAPARAPL2 knockdown inhibited S1PR1, aggravated endothelial barrier dysfunction of HUVECs in vitro, and promoted aortic atherosclerosis in ApoE-/- mice in vivo. Our study demonstrates that autophagic flux blockage induced by LSS downregulates S1PR1 expression and impairs endothelial barrier function. GABARAPL2 inhibition is involved in LSS-induced autophagic flux blockage, which impairs endothelial barrier function via downregulation of S1PR1.
Subject(s)
Atherosclerosis , Autophagy , Human Umbilical Vein Endothelial Cells , Sphingosine-1-Phosphate Receptors , Stress, Mechanical , Animals , Autophagy/drug effects , Atherosclerosis/metabolism , Atherosclerosis/pathology , Atherosclerosis/genetics , Humans , Human Umbilical Vein Endothelial Cells/metabolism , Sphingosine-1-Phosphate Receptors/metabolism , Sphingosine-1-Phosphate Receptors/genetics , Mice , Mice, Inbred C57BL , Male , Endothelium, Vascular/metabolism , Endothelium, Vascular/pathology , Endothelium, Vascular/drug effectsABSTRACT
An 84-year-old woman complaining of acute-onset chest distress for 2 hours was referred to the Department of Cardiology, Guangzhou Red Cross Hospital, China. A physical examination showed signs of acute pulmonary edema with considerably elevated blood pressure of 186/120 mmHg. An electrocardiogram showed ST segment depression in leads I, II, and III, and from V4 to V6. A laboratory test showed markedly elevated creatine, high-sensitivity cardiac troponin T, and N-terminal pro-brain natriuretic peptide levels. Echocardiography showed a mildly enlarged left ventricle with an ejection fraction of 43%. The patient was diagnosed with acute coronary syndrome, non-ST segment elevation myocardial infarction, and Killip 3 grade heart function. The non-ST segment elevation myocardial infarction Global Registry of Acute Coronary Events score was 156. Emergency coronary angiography showed severe three-vessel disease with a global ejection fraction of 50% based on left ventricular angiography. Selective renal artery angiography was performed and major stenosis at the ostia in both renal arteries was found. We did not touch the coronary artery, but performed intervention of the renal artery by implanting two bare metal stents in both ostia of bilateral renal arteries. An unexpected clinical benefit was obtained.
