Ezetimibe, a Potent Cholesterol Absorption Inhibitor, Inhibits the Development of Atherosclerosis in ApoE Knockout Mice

Abstract

Abstract-Ezetimibe (SCH58235) is a potent, selective, cholesterol absorption inhibitor. The objective of this study was to determine whether ezetimibe reduces plasma cholesterol and inhibits atherogenesis in apolipoprotein E knockout (apoEϪ/Ϫ) mice. Cholesterol absorption was inhibited by Ͼ90% at doses of ezetimibe Ͼ3 mg/kg in apoEϪ/Ϫ mice. Atherosclerosis and lipoprotein changes were determined in apoEϪ/Ϫ mice fed a high-fat (0.15% cholesterol) "western" diet, a low-fat (0.15% cholesterol) diet, or a semisynthetic cholesterol-free diet with or without ezetimibe (5 mg/kg per day) for 6 months. Ezetimibe reduced plasma cholesterol levels from 964 to 374 mg/dL, from 726 to 231 mg/dL, and from 516 to 178 mg/dL in the western, low-fat, and cholesterol-free diet groups, respectively. The reductions occurred in the very low density and low density lipoprotein fractions, whereas high density lipoprotein cholesterol levels were increased by ezetimibe treatment. Ezetimibe reduced aortic atherosclerotic lesion surface area from 20.2% to 4.1% in the western diet group and from 24.1% to 7.0% in the low-fat cholesterol diet group. Ezetimibe reduced carotid artery atherosclerotic lesion cross-sectional area by 97% in the western and low-fat cholesterol groups and by 91% in the cholesterol-free group. Ezetimibe inhibits cholesterol absorption, reduces plasma cholesterol, increases high density lipoprotein levels, and inhibits the progression of atherosclerosis under western, low-fat, and cholesterol-free dietary conditions in apoEϪ/Ϫ mice. Although apoEϪ/Ϫ mice are more hypercholesterolemic than are humans and low density lipoprotein reductions with ezetimibe are not as pronounced clinically, ezetimibe may inhibit atherogenesis in individuals consuming restricted-fat or western diets. Key Words: cholesterol absorption Ⅲ ezetimibe Ⅲ atherosclerosis Ⅲ hypercholesterolemia T he abnormal metabolism and elevation of plasma cholesterol and lipoproteins are well-documented risk factors for the development of atherosclerosis. Evidence from clinical trials indicates that reducing plasma cholesterol by dietary and/or pharmacological means leads to reductions in the incidence of death from cardiovascular disease. 1-4 Present pharmacological interventions include the inhibition of cholesterol biosynthesis by inhibiting 3-hydroxy-3-methylglutaryl coenzyme A (HMGCoA) reductase (statins) either alone or in combination with other agents. Ezetimibe (SCH58235) is the first of a new class of selective cholesterol absorption inhibitors that may represent a new option for the pharmacological treatment of hypercholesterolemia. 5,6 Ezetimibe selectively inhibits the intestinal uptake and absorption of dietary and biliary cholesterol at the brush border of small intestinal enterocytes, confining cholesterol to the intestinal lumen for subsequent excretion. 6,7 Results from preclinical studies in various animal models have demonstrated the lipid-lowering properties of ezetimibe as a single agent [5][6][7][8][9] and the synergistic cholesterol-lowering...

The target of ezetimibe is Niemann-Pick C1-Like 1 (NPC1L1)

“…The binding affinities of 1 to BBMs correlate well across species with the sensitivity to ezetimibe inhibition of cholesterol uptake in vivo (mouse Ͻ rat Ͻ monkey) (2,(26)(27), consistent with the hypothesis that the assay is relevant to the target of ezetimibe in vivo ( Table 1). As evidence that this interaction is very specific, the glucuronide of the enantiomer of ezetimibe was prepared and found to be completely inactive in vitro (K i Ͼ 100 ϫ K D for EZE-gluc in all species) and in vivo (data not shown) in a rat acute cholesterol-absorption model.…”

Effect of Ezetimibe on the Prevention and Dissolution of Cholesterol Gallstones

“…26 These studies [24][25][26] support the notion that high dietary cholesterol through the chylomicron pathway could provide an important source of excess cholesterol molecules for secretion into bile, thereby inducing cholesterol-supersaturated bile and enhancing cholelithogenesis. Since ezetimibe significantly suppresses cholesterol absorption from the small intestine via the NPC1L1 pathway, 27 possibly a transporter-facilitated mechanism, 28 this should diminish the cholesterol content of the liver, which in turn decreases bioavailability of cholesterol for biliary secretion. Indeed, we observed that ezetimibe induces a significant dosedependent reduction in intestinal cholesterol absorption efficiency, coupled with a significant dose-dependent decrease in biliary cholesterol outputs and gallstone prevalence rates.…”

“…However, in this study we observed that at day 30 after the medication, ezetimibe at 20 mg/ day can significantly reduce cholesterol concentrations and CSI values of gallbladder biles in patients with gallstones, mostly attributable to its inhibitory effect on intestinal cholesterol absorption. 27,28 As a result, cholesterol crystallization is retarded so that detection time of cholesterol monohydrate crystals is significantly delayed. Recent research on molecular transporters responsible for biliary lipid secretion suggests that the secretion efficiency of biliary cholesterol is most likely determined by the net effect between efflux and influx of cholesterol molecules across the canalicular membrane of the hepatocyte, which could be regulated by the ABCG5/G8-dependent and independent pathways as well as the NPC1L1 pathway.…”

Regulation of Intestinal Cholesterol Absorption: A Disease Perspective

“…Ezetimibe has been shown to specifically decrease cholesterol absorption after binding to NPC1L1 [91]. Furthermore, ezetimibe has been shown to inhibit the development and progression of atherosclerosis in ApoE knockout mice by reducing cholesterol absorption and plasma cholesterol levels [92]. Similarly, a significant reduction in cholesterol absorption and significant protection from the development of atherosclerosis was observed in NPC1L1 and ApoE double knockout mice [93].…”