Mulberroside A attenuates cigarette smoke-induced atherosclerosis in ApoE-/- mice via the Sirt1-HIF-1α axis

Objective: This study investigated whether Mulberryside A (MBA) can attenuate cigarette smoke extract (CSE)induced autophagy through a Sirt1-dependent pathway, thereby attenuating atherosclerosis in ApoE-/- mice. Methods: After treating human umbilical vein endothelial cells (HUVECs) with CSE and MBA, an MTT assay was performed to detect cell activity. Immunofluorescence and Western blotting were used to determine the expressions of autophagy-related proteins, Sirt1 and HIF-1 alpha. Lentivirus and siRNA were used to construct overexpression and silencing (Sirt1 and HIF-1 alpha) models. The in vivo inflammatory effects of CS on atherosclerosis in ApoE-/- mice were assessed by exposing mice to CS and MBA treatment. HE staining was used to detect atherosclerosis in mouse aortic tissue, and electron microscopy was used to detect autophagy of endothelial cells. Results: CSE promoted autophagy in HUVECs, down-regulated Sirt1, and up-regulated HIF-1 alpha expression. MBA treatment, overexpression of Sirt1, or silencing of HIF-1 alpha attenuated CSE-induced autophagy, while MBA reversed CSE-induced downregulation of Sirt1 and upregulation of HIF-1 alpha. However, overexpression of HIF-1 alpha increased autophagy in HUVECs and attenuated the protective effect of Sirt1 overexpression or MBA on CSEinduced autophagy in HUVECs. In vivo experiments also demonstrated that MBA attenuates CS-induced aortic autophagy in ApoE-/- mice and up-regulates Sirt1 and downregulates HIF-1 alpha expression. Conclusions: MBA attenuates CSE-induced autophagy through the Sirt1-HIF-1 alpha axis, thereby attenuating atherosclerosis in ApoE-/- mice.