Endothelial autophagy promotes atheroprotective communication between endothelial and smooth muscle cells via exosome-mediated delivery of miR-204-5p
Background: Cellular communication among different types of vascular cells is indispensable for maintenance of vascular homeostasis and prevention of atherosclerosis (AS). However, the biological mechanism involved in cellular communication among these cells and whether this biological mechanism can be used to treat AS remain unknown. This study hypothesizes that endothelial autophagy mediates the cellular communication of vascular tissue through exosome-mediated delivery of AS-related genes.Methods: ApoE-/- mice fed with high-fat diet (HFD) were received rapamycin to activate autophagy, or were intravenously injected with adeno-associated virus (AAV) vectors carrying shRNA against Atg7 mRNA under the Tie (tyrosine kinase) promoter to specifically inhibit endothelial autophagy. miRNA microarray, in vivo and in vitro experiments and human vascular tissues/blood vessels were used to explore the molecular mechanisms of atheroprotective effect of endothelial autophagy. Exosomes were isolated and characterized. Immunofluorescence and exosomes coculture experiments were conducted to examine the role of endothelial autophagy in regulating communication between endothelial cells (ECs) and smooth muscle cells (SMCs) via exosome.Results: Endothelial autophagy was inhibited in ECs of thoracic aortas in HFD fed ApoE-/- mice. Furthermore, rapamycin alleviated HFD-triggered atherosclerotic burden and endothelial dysfunction, while endothelial-specific depletion of Atg7 aggravated atherosclerotic burden. miRNA microarray, in vivo and in vitro experiments and human vascular tissues analysis revealed that endothelial autophagy alleviated endothelial dysfunction by downregulating miR-204-5p expression by directly targeting BCL2 to regulate apoptosis in ECs. Moreover, endothelial autophagy decreased miR-204-5p expression by loading this molecule into multivesicular bodies and secreting them out of cells via exosomes, and ECs-derived exosomal miR-204-5p could be transferred to SMCs, antagonized SMCs calcification.Conclusions: Our study first revealed that endothelial autophagy was a critical regulator of atherogenesis by transferring miR-204-5p from ECs to SMCs by exosomes, and endothelial autophagy activation by rapamycin, could alleviate AS in a “one stone hit two birds” manner. Overall design: The small RNA sequencing in the exosomes of the human umbilical vein endothelial cells treated palmitic acid with/without pretreated with atg7 siRNA or rapamycin were performed on an Illumina SE50 platform