Objective:To investigate the effect of quercetin on ATP binding cassette transporter A1 (ABCA1),liver X receptor (LXR),and proprotein convertase subtilisin/kexin type 9 (PCSK9) expressions in apoE-knockout (ApoE-/-) mice.Methods:The high-fat diet-induced atherosclerosis (AS) in ApoE-/-mice was established.Thirtysix mice were divided into 3 groups using random number table method:model group (n=12),quercetin group (n=12),and atorvastatin group (n=12),with C57BL/6J mice of the same strain and age as the control group (n=12).Quercetin group and atorvastatin group were administrated with quercetin and atorvastatin by oral gavage,with doses of 12.5 and 4 mg/(kg·d),respectively.Animals in the control and model groups were given an equal volume of distilled water by oral gavage once per day for a total of 12 weeks.Western blot and immunohistochemical methods were employed to determine the aortic ABCA1,LXR-α and PCSK9 protein expression.Enzyme linked immunosorbent assay method was used to detect the expression of serum total cholesterol (TC),triglyceride (TG),high density lipoprotein-cholesterol (HDL-C),low density lipoproteincholesterol (LDL-C),tumor necrosis factor-α (TNF-α),interleukin-6 (IL-6),and IL-10,combined with tissue pathological examination.Results:ApoE-/-mice fed with a high-fat diet had notable atherosclerosis lesions,with reduced ABCA1,LXR-α and IL-10 levels (all P＜0.01),elevated PCSK9,TNF-α and IL-6 expression,and increased TC and LDL-C contents (all P＜0.01).After quercetin intervention,the areas of AS plaques and the expressions of PCSK9,TNF-α and IL-6 were significantly reduced (all P＜0.01),while the expressions of ABCA1 and LXR-α were increased significantly (all P＜0.01).Conclusion:Quercetin effectively interfered with AS development by regulating the expressions of ABCA1,LXR-α and PCSK9 in ApoE-/-mice.