Abstract：Objective：To investigate the mechanism of Vaccarin in inhibiting the formation of atherosclerosis in ApoE-/- mice by suppressing the NOD-like receptor family pyrin domain-containing protein 3 （NLRP3） inflammasome. Methods：Twenty male ApoE-/- mice were divided into the normal control group （Con group），a high-fat diet model group（ HFD group），a low-dose Vaccarin group（ 1 mg/kg），and a high-dose Vaccarin group（ 2 mg/kg），with 5 mice in each group. Except for the Con group，mice in the other groups were fed a high-fat diet. The medicine intervention groups were administered Vaccarin at corresponding doses by gavage，while the model group received an equal volume of distilled water. After 4 weeks，body weight of mice in each group was measured；serum lipid levels and the levels of interleukin-18 （IL-18） and interleukin-1β （IL-1β） were detected. The distribution of atherosclerotic plaques in the aorta was observed by Oil Red O staining. Histomorphological changes of the aorta were observed by hematoxylineosin （HE） staining. The expression of platelet endothelial cell adhesion molecule-1 （CD31），NLRP3，and Caspase- 1 in the aorta was detected by immunofluorescence assay. The mRNA expression levels of NLRP3， gasdermin D （GSDMD），Caspase-1，IL-1β，and IL-18 were detected by real-time fluorescence quantitative PCR. The protein expression levels of NLRP3，GSDMD，and Caspase-1 in aortic tissue were determined by Western blotting. Results： Compared with the Con group， the HFD group showed significantly elevated serum levels of IL-18， IL-1β， triglycerides （TG），total cholesterol （TC），and low-density lipoprotein cholesterol （LDL-C） （P＜0.05），along with reduced high-density lipoprotein cholesterol （HDL-C） levels （P＜0.05）. Compared with the HFD group，both highand low-dose Vaccarin groups exhibited lower serum levels of IL-18， IL-1β， and LDL-C （P＜0.05）， high-dose Vaccarin group exhibited lower serum levels of TC and TG （P＜0.05）. Compared with the low-dose Vaccarin group， the high-dose group showed further reductions in TC and TG levels （P＜0.05）. Oil Red O staining revealed plaque formation in the aortas of all groups except the Con group；the red-stained plaque areas were smaller in the high- and low-dose Vaccarin groups than in the HFD group， with more significant plaque reduction observed in the high-dose group. HE staining showed intact aortic structure in the Con group， whereas the HFD group displayed structural deformation，thickened intima，multiple endothelial disruptions，and plaque deposition. The Vaccarin-treated groups also showed structural abnormalities but had thinner intima and less plaque accumulation compared with the model group. Immunofluorescence staining indicated that，compared with the Con group，the HFD group exhibited decreased CD31 protein expression and increased NLRP3 and Caspase-1 protein expression. Compared with the HFD group，both high- and low-dose Vaccarin groups showed enhanced CD31 expression and reduced NLRP3 and Caspase-1 expression，with more pronounced suppression in the high-dose group. Compared with the Con group，the HFD group showed significantly increased mRNA expression of NLRP3， GSDMD， Caspase-1， IL-1β， and IL-18 （P＜0.05）. Compared with the HFD group， the high-dose Vaccarin group exhibited decreased mRNA expression of NLRP3， GSDMD， Caspase-1， IL-1β， and IL-18 （P＜0.05）； the low-dose Vaccarin group showed reduced mRNA expression of NLRP3， IL-1β， and IL-18 （P＜0.05）， while no significant difference was observed in the mRNA expression of GSDMD and Caspase-1 （P＞0.05）. Compared with the low-dose Vaccarin group， the high-dose group showed further decreased NLRP3，GSDMD，Caspase-1，and IL-1β mRNA expression （P＜0.05）. Western blotting analysis revealed that， compared with the Con group， the HFD group showed significantly higher activation ratios of NLRP3/GAPDH， cleaved-GSDMD/pro-GSDMD， and cleaved Caspase-1/Caspase-1 （P＜0.05）. Compared with the HFD group， the low-dose Vaccarin group showed a marked decrease in the cleaved-GSDMD/pro-GSDMD activation ratio （P＜0.05），and the high-dose group demonstrated significant reductions in NLRP3/GAPDH，cleaved-GSDMD/ pro-GSDMD，and cleaved Caspase-1/Caspase-1 （P＜0.05）. Compared with the low-dose Vaccarin group，the highdose group showed further suppression of NLRP3/GAPDH， cleaved-GSDMD/pro-GSDMD， and cleaved Caspase-1/ Caspase-1 activation ratios （P＜0.05）. Conclusion：Vaccarin can exert its anti-atherosclerotic effect by inhibiting the expression of GSDMD and Caspase-1-related proteins and suppressing the activation of the NLRP3 inflammasome.