Inhibition of Cholesteryl Ester Transfer Protein Activity by JTT-705 Increases Apolipoprotein E–Containing High-Density Lipoprotein and Favorably Affects the Function and Enzyme Composition of High-Density Lipoprotein in Rabbits

Abstract

Background-Inhibition of cholesteryl ester transfer protein (CETP) is an efficient way to increase high-density lipoprotein (HDL) levels in humans. We investigated the effects of the inhibition of CETP activity by a CETP inhibitor, JTT-705, on the function and composition of HDL particles. Methods and Results-Japanese white rabbits were fed either normal rabbit chow LRC-4 (nϭ10) or a food admixture of LRC-4 and 0.75% JTT-705 (nϭ10) for 7 months. JTT-705 significantly inhibited CETP activities, increased HDL cholesterol (HDL-C) levels and the ratio of HDL 2 -C/HDL 3 -C, and decreased the fractional esterification rate of cholesterol in HDL, indicating preferentially increased large HDL particles. Treatment with JTT-705 increased all of the 3 charge-based HDL subfractions as determined by capillary isotachophoresis: fast-migrating, intermediate-migrating, and slow-migrating HDL. The percentage of slow HDL, ie, apolipoprotein E (apoE)-containing HDL and levels of apoE in HDL fraction, was also increased. JTT-705 treatment increased serum paraoxonase activity and HDL-associated platelet-activating factor acetylhydrolase activity, but decreased the plasma lysophosphatidylcholine concentration. Key Words: cholesteryl ester transfer protein inhibition Ⅲ apolipoprotein E-containing high-density lipoprotein Ⅲ capillary isotachophoresis Ⅲ paraoxonase (PON1) Ⅲ platelet-activating factor acetylhydrolase Ⅲ lysophosphatidylcholine Ⅲ rabbits I ncreased levels of low-density lipoprotein cholesterol (LDL-C) and reduced levels of high-density lipoprotein cholesterol (HDL-C) are known risk factors for coronary heart disease (CHD). The balance between HDL-C and LDL-C is known to be important in predicting the risk of CHD. 1 Although statin drugs potently lower LDL-C levels, their ability to raise HDL levels is limited. HDL helps to protect against atherosclerosis mainly because of its role in the reverse cholesterol transport process and its anti-oxidative and anti-inflammatory properties. Cholesteryl ester transfer protein (CETP) mediates the transfer of cholesteryl ester (CE) from HDL to apolipoprotein B (apoB)-containing lipoproteins and of triglyceride from triglyceride-rich remnants to HDL and LDL. 2 The HDL level has been shown to be influenced by CETP based on the fact that patients with genetic CETP deficiency have extremely high levels of HDL. 3 Although whether CETP is anti-atherogenic or proatherogenic depends on the metabolic background, and the exact role that CETP plays in atherosclerosis is still controversial, inhibition of CETP activity by small molecular CETP inhibitors, including JTT-705 and torcetrapib, has been shown to be an efficient way to raise HDL levels in subjects with normal 4,5 and low HDL-C levels. 6 HDL consists of heterogeneous particles that differ in density and size. Inhibition of CETP activity by torcetrapib in subjects with low HDL-C levels caused a much greater percentage increase in HDL 2 -C levels than in HDL 3 -C levels, and increased large HDL particles as determined by nuclear magnetic ...

Relation between insulin resistance and fast-migrating LDL subfraction as characterized by capillary isotachophoresis

“…cITP of lipoproteins in serum, to which was added EDTA-Na 2 at a final concentration of 1 mM before analysis, was performed on a Beckman P/ACE MDQ system (Beckman-Coulter, Inc., Tokyo, Japan) according to the method of Bottcher et al (14) with some modifications, as described previously (19)(20)(21)(22). All of the reagents used for cITP analysis were purchased from SigmaAldrich (Tokyo, Japan) unless indicated otherwise.…”

“…Each peak was identified, and the peak area in relative fluorescence units was analyzed using 32 Karat Software version 5.0 (BeckmanCoulter, Inc., Tokyo, Japan). The peak area for each cITP lipoprotein subfraction relative to that of the internal marker was presented as the level of cITP lipoprotein subfraction (19)(20)(21)(22), unless indicated otherwise.…”

“…ApoB-containing lipoproteins in EDTA plasma were precipitated by the phosphotungstate-Mg 2 ϩ method, as described previously (19). LDL was isolated from fresh EDTA plasma from the same volunteer by sequential ultracentrifugation.…”

“…The two cITP LDL subfractions, fast-migrating (f) and slow-migrating (s) LDL, represent the LDL( Ϫ ) and major LDL subfractions, respectively. We and others (14,15,(19)(20)(21)(22) have previously shown that the absolute amount of lipoprotein subfraction can be determined by reference to an internal marker. In cITP analysis, because lipoproteins are stained by the lipophilic dye 7-nitrobenz-2-oxa-1,3-diazol-4-yl (NBD)-ceramide and monitored by laser-induced fluorescence detection (excitation, 488 nm; emission, 510 nm), lipoproteins can be analyzed without prior separation from other plasma proteins.…”

Potent Capillary Isotachophoresis (cITP) for Analyzing a Marker of Coronary Heart Disease Risk and Electronegative Low-Density Lipoprotein (LDL) in Small Dense LDL Fraction

“…It separates plasma lipoproteins into 8 fractions, comprising 3 high-density liporotein (HDL) fractions with fast (f), intermediate (I), and slow (s) electric mobility, a chylomicron/remnants fraction (fast very low-density lipoprotein (VLDL)), a VLDL/intermediate density lipoprotein (IDL) fraction (slow VLDL), 2 LDL fractions with fast and slow electric mobility, and a minor LDL fraction. [1][2][3][4][5] In our previous reports, the fast LDL fractions corresponded to electronegative LDL in which some oxidized LDL, VLDL, and small dense LDL etc, the so-called "bad cholesterol", are concentrated. 4 After the light LDL fraction is precipitated from whole serum using heparin-Mg 2+ , electronegative LDL in the small dense LDL fraction can be measured using cITP.…”