Endothelial-specific deletion of autophagy-related 7 (ATG7) attenuates arterial thrombosis in mice

Background: Thrombosis persists as a leading cause of morbidity and mortality. Given that endothelial cells (ECs) play a central role in regulating thrombosis, understanding the molecular endothelial cues that regulate susceptibility or resistance to thrombosis have important translational implications. Accordingly, we evaluated the role of endothelial autophagy in the development of thrombosis. Methods: We generated mice in which the essential autophagy-related 7 (ATG7) gene was conditionally deleted from ECs (EC-ATG7(-/-) mice). Three in vivo models of thrombosis were used, and mechanistic studies were conducted with cultured human umbilical vein endothelial cells (HUVECs). Results: We silenced ATG7 in HUVECs and observed>60% decreases in tumor necrosis factor (TNF)-alpha-induced tissue factor (TF) transcript levels, protein expression, and activity. TF mRNA levels in the carotid arteries of EC-ATG7(-/-) mice subjected to the prothrombotic stimulus FeCl3 were lower than those in the similarly treated wild-type (WT) littermate group. Compared with WT mice, EC-ATG7(-/-) mice exhibited prolonged time to carotid (2-fold greater) and mesenteric (1.3-fold greater) artery occlusion following FeCl3 injury. The thrombi generated in laser-injured cremasteric arterioles were smaller in EC-ATG(-/-) mice compared with WT mice, and took 2.3-fold longer to appear. Conclusions: Taken together, these results provide definitive evidence that loss of endothelial ATG7 attenuates thrombosis and reduces the expression of TF. Our findings demonstrate that endothelial ATG7, and thus autophagy, is a critical and previously unrecognized target for modulating the susceptibility to thrombosis.