Ezetimibe, an inhibitor of Niemann-Pick C1-like 1 protein, decreases cholesteryl ester transfer protein in type 2 diabetes mellitus

Real-time cholesterol sorting in Plasmodium falciparum-erythrocytes as revealed by 3D label-free imaging

Cholesterol, a necessary component of animal cell membranes, is also needed by the lethal human malaria parasite Plasmodium falciparum. Because P. falciparum lacks a cholesterol synthesis pathway and malaria patients have low blood cholesterol, we speculated that it scavenges cholesterol from them in some way. We used time-lapse holotomographic microscopy to observe cholesterol transport in live P. falciparum parasites and structurally investigate erythrocyte membranes, both during and after P. falciparum invasion of human erythrocytes. After P. falciparum initially acquired free cholesterol or inner erythrocytic membrane-derived cholesterol, we observed budding lipid membranes elongating into the cytosol and/or membrane segments migrating there and eventually fusing with the parasite membranes, presumably at the parasitophorous vacuole membrane (PVM). Finally, the cholesterol-containing segments were seen to surround the parasite nucleus. Our imaging data suggest that a novel membrane transport system operates in the cytosol of P. falciparum-infected erythrocytes as a cholesterol import system, likely between the PVM and the erythrocyte membrane, and that this transportation process occurs during the live erythrocyte stages of P. falciparum.

Ezetimibe in Combination With Simvastatin Reduces Remnant Cholesterol Without Affecting Biliary Lipid Concentrations in Gallstone Patients

Background

In randomized trials (SHARP [Study of Heart and Renal Protection], IMPROVE‐IT [Improved Reduction of Outcomes: Vytorin Efficacy International Trial]), combination of statin and ezetimibe resulted in additional reduction of cardiovascular events. The reduction was greater in patients with type 2 diabetes mellitus (T2DM), where elevated remnant cholesterol and high cardiovascular disease risk is characteristic. To evaluate possible causes behind these results, 40 patients eligible for cholecystectomy, randomized to simvastatin, ezetimibe, combined treatment (simvastatin+ezetimibe), or placebo treatment during 4 weeks before surgery, were studied.

Methods and Results

Fasting blood samples were taken before treatment start and at the end (just before surgery). Bile samples and liver biopsies were collected during surgery. Hepatic gene expression levels were assessed with qPCR. Lipoprotein, apolipoprotein levels, and content of cholesterol, cholesteryl ester, and triglycerides were measured after lipoprotein fractionation. Lipoprotein subclasses were analyzed by nuclear magnetic resonance. Apolipoprotein affinity for human arterial proteoglycans (PG) was measured. Biomarkers of cholesterol biosynthesis and intestinal absorption and bile lipid composition were analyzed using mass spectrometry. Combined treatment caused a statistically significant decrease in plasma remnant particles and apolipoprotein B (ApoB)/lipoprotein content of cholesterol, cholesteryl esters, and triglycerides. All treatments reduced ApoB‐lipoprotein PG binding. Simvastatin and combined treatment modified the composition of lipoproteins. Changes in biomarkers of cholesterol synthesis and absorption and bile acid synthesis were as expected. No adverse events were found.

Conclusions

Combined treatment caused atheroprotective changes on ApoB‐lipoproteins, remnant particles, bile components, and in ApoB‐lipoprotein affinity for arterial PG. These effects might explain the decrease of cardiovascular events seen in the SHARP and IMPROVE‐IT trials.

Clinical Trial Registration

URL: www.clinicaltrialsregister.eu. Unique identifier: 2006‐004839‐30).