Lack of Receptor of Advanced Glycation End Products (RAGE) Attenuates Long‐Term Cigarette Smoke Exposure‐Induced Vascular Dysfunction in C57BL6 Mice.

Abstract

BackgroundThe evidence that active smoking is a risk factor for cardiovascular diseases (CVD). Chronic secondhand smoke (SHS) exposure also has deleterious effects on mediated endothelial‐dependent vasodilation through nitric oxide (NO) synthase with increasing inflammation. Recently, there are growing evidences that receptor for advanced glycation end product (RAGE) may play a critical role in inflammation and endothelial dysfunction, likely to promote the processes of vascular diseases. However, there is no evidence whether SHS exposure may induce RAGE expression leading to arterial inflammation and endothelial dysfunction. Therefore, the purpose of this study was to determine whether RAGE signaling play a role in long‐term cigarette smoke exposure‐induced endothelial dysfunction.MethodsTwelve month old C57BL/6 mice were randomly assigned to one of four experimental groups (n=8/group); 1) control (CON), 2) animals with 8 months of cigarette smoke exposure (SM), 3) RAGE knock out animals (R −/−), 4) RAGE knock out animals with 8 months of cigarette smoke exposure (RSM −/−). After 8 months of cigarette smoke, using an in vitro preparation, endothelium‐dependent and ‐independent vasodilation were assessed in arteries in response to three stimuli 1) flow‐induced shear stress, 2) acetylcholine (ACh), and 3) sodium nitroprusside (SNP). Endothelial NOS (eNOS), NFkB, RAGE protein expression were analyzed via Western blot analysis.Results8 months of cigarette smoke exposure significantly attenuated endothelial‐dependent vasodilatory function in response to the intraluminal flow (CON: 84 ± 3; SM: 25 ± 2%, P < 0.05) and ACh (CON: 92 ± 3, SM: 33 ± 3 %, P < 0.05). However, RAGE knock out mice significantly restored endothelial function following 8 months of cigarette smoke exposure(flow: 72± 2%, P < 0.05; ACh: 83 ± 3 %, P < 0.05). There is no difference between control and RAGE knock out groups (flow: 85± 2%, ACh: 92± 2%). All groups had no significant effect on endothelium‐independent vasodilation (SNP). P‐eNOS/eNOS protein expression was significantly decreased with 8 months secondhand smoking but RAGE knock out group apparently increases protein expression. In addition, SM group showed that one of the inflammation marker, NFkB protein expression, is significantly increased but deletion of RAGE prevents smoke exposure‐induced NFkB protein overexpression. Furthermore, SM group showed increased RAGE protein expression compared to control group.ConclusionsOverall, these findings suggest that secondhand smoke induces endothelial dysfunction through reduction in NO bioavailability and increase in RAGE abundance. Our data showed that deletion of RAGE restores smoke exposure‐induced endothelium vasodilatory function. Therefore, RAGE signaling in endothelium may play a critical role in smoke exposure‐associated endothelial dysfunction. Furthermore, TLR4 signaling could be a novel therapeutic target to restore endothelial function and NO bioavailability.