Abstract 14050: The Gut Flora Promotes Endothelial Dysfunction Through Vascular MicroRNA-204-mediated Down-regulation of Endothelial Sirtuin1

Abstract

The gut flora contributes to development of atherosclerosis. Endothelial dysfunction, one manifestation of which is impaired endothelium-dependent vasorelaxation, accompanies and promotes atherosclerotic vascular disease. Here we show that gut flora impair endothelium-dependent vasorelaxation by remotely up-regulating microRNA-204 (miR-204) which downregulates SIRTUIN1 (SIRT1) in the vascular wall. Microarray analysis in aortas of germ-free mice revealed a set of down-regulated microRNAs, including miR-204, which target SIRT1. Suppression of gut flora in mice with antibiotics in drinking water decreased aortic miR-204, increased aortic SIRT1, and improved endothelium-dependent vasorelaxation, effects that were reversed with discontinuation of antibiotics. In addition, miR-204 mimic impaired endothelium-dependent aortic vasorelaxation ex vivo. Moreover, high-fat diet feeding stimulated aortic miR-204, suppressed SIRT1, and impaired endothelial function, all of which were mitigated by administration of antibiotics, and reversed with stoppage of antibiotics. In contrast, antibiotics did not improve high-fat diet-induced endothelial dysfunction in mice conditionally lacking endothelial SIRT1. In addition, anti-miR-204 delivered systemically prevented high-fat diet-induced endothelial dysfunction and vascular SIRT1 decrease. Finally, serum from mice on antibiotics suppressed miR-204, and increased SIRT1, in endothelial cells, effects that were not observed with serum from mice in which antibiotics were discontinued. Therefore, the gut flora remotely downregulates endothelial SIRT1 through miR-204, leading to impairment of endothelial function.