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From the Department of Cardiology, Fukuoka University School of Medicine, Fukuoka, Japan.
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 (n=10) or a food admixture of LRC-4 and 0.75% JTT-705 (n=10) for 7 months. JTT-705 significantly inhibited CETP activities, increased HDL cholesterol (HDL-C) levels and the ratio of HDL2-C/HDL3-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.
Conclusion— Inhibition of CETP activity by JTT-705 not only increased the quantity of HDL, including HDL-C levels and charge-based HDL subfractions, but also favorably affected the size distribution of HDL subpopulations and the apolipoprotein and enzyme composition of HDL in rabbits.
The effects of CETP inhibition on the function and composition of HDL particles were examined in rabbits. JTT-705 significantly inhibited CETP activities, decreased FERHDL values, and increased apoE-containing HDL and activities of paraoxonase and HDL-associated PAF-AH. In conclusion, inhibition of CETP activity favorably affected the size distribution of HDL subpopulations and the apolipoprotein and enzyme composition of HDL.
Key Words: cholesteryl ester transfer protein inhibition ? apolipoprotein E-containing high-density lipoprotein ? capillary isotachophoresis ? paraoxonase (PON1) ? platelet-activating factor acetylhydrolase ? lysophosphatidylcholine ? rabbits
Introduction
Increased 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 pro-atherogenic 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 normal4,5 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 HDL2-C levels than in HDL3-C levels, and increased large HDL particles as determined by nuclear magnetic resonance spectroscopy.6 HDL particles can also be resolved into 5 distinct subspecies of different sizes by gradient gel electrophoresis (small to large): HDL3c, HDL3b, HDL3a, HDL2a, and HDL2b.7 Both a decreased concentration of the largest HDL2b particles and an increased concentration of the smallest HDL3b,c particles are highly and significantly correlated with the risk of CHD.7 HDL2b particles are especially important in that they determine the direction of the flow of CE formed on HDL by the lecithin:cholesterol acyltransferase (LCAT) reaction.7 In the presence of a sufficient amount of HDL2b particles, most HDL-CE is directed to the liver by the selective uptake of CE by HDL receptors.7 However, in the absence of HDL2b particles, HDL-CE is transferred to VLDL and LDL by the action of CETP, resulting in an increase in CE in potentially atherogenic particles.7 Although HDL2b particles correlate well with HDL2 by ultracentrifugation, the HDL3b,c subpopulations form only a small component of HDL3.7 Therefore, Dobiasova and Frohlich established a functional assay of HDL size heterogeneity, the fractional esterification rate in HDL (FERHDL).7–15 The FERHDL value reflects the distribution of HDL subpopulations: it negatively correlates with the relative content of HDL2b particles and positively correlates with the relative content of HDL3b,c particles. We previously reported that the FERHDL value, which is a good indicator of the atherogenic potential of plasma, is an independent indicator of coronary atherosclerosis.16 Considering that the inhibition of CETP activity by CETP inhibitors should inhibit the flow of HDL-CE to VLDL and LDL, it would be interesting to determine whether CETP inhibition affects the function of HDL as assessed by FERHDL.
HDL particles are also heterogeneous with regard to electric charge and the composition of lipids and apolipoproteins. Schmitz et al17 developed a new tool to separate plasma lipoprotein subfractions according to their electric charge by capillary isotachophoresis (cITP). The 3 HDL subfractions separated by cITP, ie, fast-migrating HDL (fHDL), intermediate-migrating HDL (iHDL), and slow-migrating HDL (sHDL), can be well-characterized with regard to apolipoprotein and lipid composition.18 The cITP fHDL contains mainly apoA-I–containing lipoproteins and cholesterol esters.18 Slow-migrating HDL contains apoE-rich HDL18 and is designated as apoE-containing HDL.19 Increased apoE-rich HDL has also been shown in patients with genetic CETP deficiency3,20 and in those with LCAT deficiency.21 Clark et al recently reported that the inhibition of CETP activity by torcetrapib caused an apparent increase in the plasma apoE concentration.5 They suggested that the increased apoE may be associated with HDL.5 The importance of apoE has been evidenced in apoE-knockout mice that develop atherosclerosis even on a regular chow diet. ApoE-rich HDL can bind to LDL receptors and scavenger receptors, and may play an important role in cholesterol efflux.22 In fact, the apoE-containing subfraction of HDL, separated by heparin Sepharose affinity chromatography, has been shown to be present at lower concentrations in patients with CHD.22 Therefore, it would also be interesting to determine the effects of the inhibition of CETP activity on apoE in HDL fraction and charged-based HDL subfractions, including apoE-containing HDL.
The enzyme composition of HDL has been shown to be important in its anti-oxidative and anti-inflammatory properties.23 Paraoxonase (PON1) is exclusively associated with HDL and protects LDL from oxidation. Patients with CETP deficiency have been shown to have increased serum PON1 activity compared with control subjects with the same PON1 genotype.24 Platelet-activating factor acetylhydrolase (PAF-AH), a lipoprotein-associated phospholipase A2, degrades PAF and oxidized phospholipids into lyso-PAF and lysophosphatidylcholine (lyso-PC).25 In human plasma, PAF-AH activity is associated with HDL and LDL. HDL-associated PAF-AH (HDL-PAF-AH) activity has been consistently shown to play an anti-atherogenic and anti-inflammatory role by helping to protect LDL from oxidation and contributing to the HDL-mediated inhibition of cell stimulation induced by oxidized LDL.25 It is not clear whether the inhibition of CETP activity affects the enzyme composition of HDL.
Therefore, in the present study we investigated the effects of the inhibition of CETP activity by the CETP inhibitor JTT-705 on the function of HDL as measured by FERHDL, HDL subfractions as characterized by cITP, activities of HDL-associated enzymes (PON1 and PAF-AH), and the plasma lyso-PC concentration in rabbits.
Methods
A detailed Methods section is available online at http://atvb.ahajournals.org.
Results
Effects of JTT-705 on CETP Activity, Serum HDL-C Levels, and the Distribution of HDL Subfractions
CETP activity was markedly decreased in JTT-705–treated rabbits at 5 and 7 months, as assessed by a 1-way analysis of variance (Figure IA, available online at http://atvb.ahajournals.org). The pattern of the changes in CETP activity significantly differed in control and JTT-705–treated rabbits, as assessed by a 2-way analysis of variance. As shown in Figure IB, treatment with JTT-705 markedly increased serum levels of HDL-C. As shown in Figure IC, the ratio of HDL2-C to HDL3-C was significantly higher in JTT-705–treated rabbits than in control rabbits at 5 and 7 months, indicating that the inhibition of CETP activity by JTT-705 changed the distribution of HDL subfractions and preferentially increased HDL2-C levels. As shown in Figure ID, the FERHDL value in JTT-705–treated rabbits was significantly lower than that in control rabbits at 5 and 7 months, suggesting that the inhibition of CETP activity by JTT-705 increases the proportion of HDL2b particles relative to HDL3b,c particles. These results indicate that the inhibition of CETP activity not only increases the quantity of HDL but also favorably affects the size distribution of HDL subpopulations.
Identifying ApoE-Containing HDL Separated by Capillary Isotachophoresis
The cITP lipoprotein profile in plasma from a male healthy subject is shown in Figure 1A. As shown, plasma lipoproteins were separated into 8 subfractions, including 3 HDL subfractions (peaks 1 to 3: fHDL, iHDL, and sHDL), a chylomicron/remnant fraction (peak 4), a very-low-density lipoprotein (VLDL)/intermediate-density lipoprotein (IDL) fraction (peak 5), and 3 LDL subfractions (peaks 6 to 8: fast LDL, slow LDL, and a minor fraction). Figure 1B shows a cITP profile of plasma that was depleted of apoB-containing lipoprotein by precipitation with phosphotungstate MgCl2. As shown, fractions indicated by peaks 1 to 3 in apoB-depleted plasma (Figure 1B) were similar to those in the whole plasma (Figure 1A), which led us to identify peaks 1 to 3 as the HDL fraction. Fractions indicated by peaks 4 to 8 in the whole plasma (Figure 1A) did not appear in apoB-depleted plasma (Figure 1B), indicating that peaks 4 to 8 were apoB-containing lipoprotein and that precipitation was complete. To confirm that slow HDL is apoE-containing lipoprotein, the cITP lipoprotein profile in plasma from a patient with familial LCAT deficiency was examined before and after depleting apoB-containing and apoE-containing lipoprotein, because familial LCAT deficiency is known to cause increased apoE-rich HDL. As shown in Figure 1C, plasma from the LCAT-deficient patient contained almost no cITP fHDL fraction and much less iHDL fraction than that from the normal subject. However, cITP sHDL in plasma from the LCAT-deficient patient was markedly higher than that in plasma from the normal subject (Figure 1A).
Figure 1. Lipoprotein profiles as determined by capillary isotachophoresis in the whole plasma (A and C) and apoB-depleted and apoE-depleted plasma (B and D) from a normal control subject (A and B) and a patient with familial LCAT deficiency (C and D). Peaks 1 to 3, fast-migrating (f), intermediate-migrating (i), and slow-migrating (s) HDL; peak 4; chylomicron/remnants; peak 5, VLDL/IDL; peaks 6 and 7, fast-migrating and slow-migrating LDL; peak 8, a minor LDL fraction.
Phosphotungstate, a polyanion, precipitates lipoproteins through an ionic interaction between negatively charged polyanion and positively charged lysine and arginine residues of apoB and apoE molecules, in conjunction with a divalent cation such as Mg2+. Therefore, phosphotungstate MgCl2 precipitates apoB-containing and apoE-containing lipoproteins. As shown in Figure 1D, cITP fHDL (peak 1) and iHDL (peak 2) were similar in apoB-depleted and apoE-depleted LCAT-deficient plasma and whole plasma (Figure 1C). However, cITP sHDL (peak 3) in plasma from the LCAT-deficient patient was markedly decreased after apoB and apoE were precipitated (Figure 1C and 1D). This result indicates that cITP sHDL is apoE-containing lipoprotein.
Effects of JTT-705 on the Distribution of cITP HDL Subfractions
Figure 2 A and 2B shows typical cITP lipoprotein profiles in plasma from a normal control rabbit and a JTT-705–treated rabbit. HDL fraction was identified by analyzing apoB-depleted plasma of the JTT-705–treated rabbit (Figure 2C). As shown in Figure 2, rabbit HDL also contained 3 charged-based HDL subfractions (peaks 1 to 3). All of the 3 cITP HDL subfractions, fHDL, iHDL, and sHDL, were increased in the JTT-705–treated rabbit compared with the normal rabbit (Figure 2A and 2B). As shown in Figure 2B and 2C, whereas cITP fHDL was similar in apoB-depleted and apoE-depleted plasma and the whole plasma from a JTT-705–treated rabbit, cITP sHDL was apparently reduced in apoB-depleted and apoE-depleted plasma compared with the whole plasma from the same rabbit. Therefore, although it is not yet clear whether the characteristics of the 3 cITP HDL subfractions in rabbit plasma are the same as those in human plasma, this result indicates that rabbit cITP sHDL is apoE-containing lipoprotein.
Figure 2. Lipoprotein profiles as determined by capillary isotachophoresis in the whole plasma from a normal control rabbit (A) and whole plasma (B) and apoB-depleted and apoE-depleted plasma (C) from a rabbit treated with JTT-705 for 7 months. Peaks 1 to 3, fHDL, iHDL, and sHDL.
Figure 3A to 3C shows the changes in peak area relative to an internal marker for cITP fHDL, iHDL, and sHDL in JTT-705–treated and control rabbits during the study. As shown, cITP fHDL, iHDL, and sHDL in JTT-705–treated and control rabbits showed different patterns of changes during the study, as assessed by a 2-way repeated measures analysis of variance. The cITP fHDL (Figure 3A), iHDL (Figure 3B), and sHDL (Figure 3C) were significantly higher in the treated rabbits than in control rabbits at 7 months. This result indicates that treatment with JTT-705 increased all of the 3 cITP HDL subfractions. However, it is apparent that the extent of the increase in cITP sHDL in treated rabbits was greater than that in cITP fHDL. Therefore, the percentage of sHDL was calculated and is shown in Figure 3D. The percentage of sHDL in JTT-705–treated rabbits was significantly greater than that in control rabbits at 5 and 7 months. These results indicate that treatment with JTT-705 changed the distribution of cITP HDL subfractions by increasing apoE-containing HDL.
Figure 3. Changes in peak area relative to an internal marker for cITP fHDL (A), iHDL (B), and sHDL (C), and percentage of cITP sHDL (D) during the study period (at 0, 5, and 7 months) in JTT-705–treated (–?–) and control rabbits (––). *P<0.05, versus 0 months, as assessed by a 1-way repeated measures analysis of variance. P<0.05, treated versus control, as assessed by a 2-way repeated measures analysis of variance.
Effects of JTT-705 on ApoE Levels in Plasma and HDL Fraction
As shown in Figure 4A, plasma apoE levels in JTT-705–treated rabbits were significantly higher than those in control rabbits at 5 and 7 months. As shown in Figure 4B, apoE levels in HDL fractions were also increased in JTT-705–treated rabbits and showed patterns of change similar to those in plasma apoE levels. This result indicates that the increased plasma apoE levels were mainly caused by an increase in the apoE concentration in the HDL fraction. HDL-C levels in apoE-rich HDL (Figure 4C), calculated as the difference in HDL-C levels between the HDL fraction obtained with 13% polyethylene glycol and that obtained with DS-PT-Mg, were low and did not change significantly during the study in either group of rabbits. However, PL levels in apoE-rich HDL (Figure 4D), calculated as the difference in PL levels between the HDL fraction obtained with 13% polyethylene glycol and that obtained with DS-PT-Mg, were significantly higher in JTT-705–treated rabbits than in control rabbits at 5 and 7 months.
Figure 4. Changes in apoE levels in plasma (A) and the HDL fraction obtained with 13% polyethylene glycol (B) and HDL-C (C) and PL levels (D) in apoE-rich HDL fraction during the study period (at 0, 5, and 7 months) in JTT-705–treated (–?–) and control rabbits (––). *P<0.05, versus 0 months, as assessed by a 1-way repeated measures analysis of variance. P<0.05, treated versus control, as assessed by a 2-way repeated measures analysis of variance.
Effects of JTT-705 on Enzyme Composition and Plasma Lyso-PC Concentration
As shown in Figure IIA (available online at http://atvb.ahajournals.org), PON1 activity in JTT-705–treated rabbits was significantly higher than that in control rabbits at 7 months. Plasma PAF-AH and HDL-associated PAF-AH activities (Figure IIB and IIC) in JTT-705–treated rabbits were also significantly higher than those in control rabbits. Because rabbits have very low levels of LDL, it is apparent that increased plasma PAF-AH activity is caused by increased HDL-PAF-AH (Figure IIB and IIC). Because PAF-AH is known to hydrolyze oxidized phospholipids into lyso-PC, it would be interesting to determine whether lyso-PC is increased by treatment with JTT-705. Surprisingly, the plasma lyso-PC concentration in JTT-705–treated rabbits was significantly lower than that in control rabbits at 5 and 7 months (Figure IID). This result suggests that the inhibition of CETP by JTT-705 may have decreased oxidized phospholipids, substrates for PAF-AH activity, in rabbits.
In summary, the inhibition of CETP activity by JTT-705 increased HDL-C levels and the proportion of HDL2-C, decreased FERHDL values, increased charge-based HDL subfractions including apoE-containing HDL, increased apoE levels in HDL and PL levels in apoE-rich HDL, and increased the activities of the HDL-associated enzymes PON1 and PAF-AH, indicating that the inhibition of CETP activity by JTT-705 favorably affects not only the quantity and the size distribution of HDL subfractions but also the apolipoprotein and enzyme composition of HDL particles.
Discussion
Inhibition of CETP activity by small molecular CETP inhibitors has been shown to be an effective way to increase HDL-C and apoA-I levels in humans.4–6 The present study examined the effects of the inhibition of CETP activity on the subpopulation distribution and composition of HDL in rabbits.
Our finding that the inhibition of CETP activity increases HDL-C levels agrees with those of other authors in humans.4–6 We previously reported that the increases in HDL by JTT-705 are attributable to an increased synthesis rate of apoA-I in normal rabbits26 and to both an increased synthesis rate of apoA-I and a decreased catabolic rate of apoA-I in cholesterol-fed rabbits.27 Our finding that the inhibition of CETP activity increases the proportion of HDL2-C particles is also consistent with those of Brousseau et al in humans that the CETP inhibitor torcetrapib increases large HDL particles but not small HDL particles, as determined by nuclear magnetic resonance spectroscopy.6 FERHDL is an established functional assay of HDL heterogeneity and reflects the distribution of HDL2b particles, the increased proportion of which is protective, and HDL3b,c particles, the increased proportion of which is atherogenic.7 We are the first group to our knowledge to examine the effects of CETP inhibition on FERHDL values. Our finding that the inhibition of CETP activity greatly decreases FERHDL values is not unexpected, because the inhibition of CE transfer from HDL to VLDL and LDL should inhibit the rate of production of HDL-CE. However, because the protective HDL2 particles are increased, decreased FERHDL values reflect a favorable change in the distribution of HDL subpopulations.
Our finding that JTT-705-increased plasma apoE levels were mainly caused by an increase in apoE levels in HDL (Figure 4A and 4B) supports the suggestion by Clark et al that much of the increase in plasma apoE in subjects treated with 120 mg torcetrapib could be associated with HDL.5 Capillary isotachophoresis has been shown to be a high-throughput technique for characterizing plasma lipoproteins.17,18 Plasma lipoproteins can be separated into well-characterized subfractions in minutes17,18 (Figure 1). We identified fractions indicated by peaks 1 to 3 as HDL fraction by analyzing apoB-depleted plasma. This finding confirmed those of Bottcher et al and Schmitz et al, who identified lipoprotein fractions by adding purified lipoproteins to plasma.17,18 Bottcher et al demonstrated that cITP sHDL was the major apoE-containing lipoprotein by using preparative free-flow isotachophoresis and immunoblotting in 2D-GGE.18 The cITP sHDL also contains apoA-IV, apoC-III, apoD, and apoJ.18 We used plasma from familial LCAT deficiency, caused by a premature termination by frame-shift caused by a 1-base deletion of G at base 873 in exon 6 of the LCAT gene,28 to identify apoE-containing HDL, because familial LCAT deficiency is associated with increased apoE-containing HDL. Our finding that HDL in familial LCAT deficiency consisted of 2 major HDL fractions, iHDL, and sHDL, agrees with that of Soutar et al,29 who reported a lipoprotein fraction whose sole apolipoprotein was apoA-I and a second major component that contained apoA-I, apoE, and apoA-IV in familial LCAT deficiency. We found that most of the of cITP sHDL fraction in familial LCAT deficiency disappeared after the depletion of apoB and apoE from plasma by precipitation using phosphotungstate MgCl2.
We are the first to our knowledge to apply cITP to the analysis of plasma lipoproteins in animals. We found that rabbit HDL also contained 3 charge-based subfractions. Although the apolipoprotein composition of HDL in humans and rabbits are different in that rabbit HDL contains no apoA-II, our finding using JTT-705–treated rabbits indicates that rabbit sHDL is also apoE-containing lipoprotein (Figure 2B and 2C). We found that JTT-705 increased all 3 cITP subfractions (Figure 3A to 3C) and the percentage of cITP sHDL (Figure 3D). Although the mechanism by which the inhibition of CETP increases apoE-containing HDL is not clear, increased apoE-containing HDL should facilitate reverse cholesterol transport, because plasma from patients with familial LCAT deficiency has been shown to be as efficient as control plasma in cholesterol efflux from cholesterol-loaded fibroblasts.30 ApoE-enriched HDL has also been shown to be a ligand for the LDL receptor-related protein31 and LR11, a mosaic LDL receptor family member,32 which mediates the endocytosis of HDL, and a ligand for the scavenger receptor class B type I (SR-BI),33,34 which mediates the selective uptake of HDL cholesteryl esters. We found that CETP inhibition by JTT-705 increased PL levels in apoE-rich HDL (Figure 4D). Association with phospholipid has been shown to increase the amount of apolipoprotein binding to SR-BI.35 Therefore, increased apoE-containing HDL may also facilitate the transfer of HDL cholesterol esters to the liver, either by apoE receptor-mediated endocytosis or by selective uptake through SR-BI. Further investigation is needed to clarify this point.
Our finding that JTT-705 increased serum PON1 activity in rabbits is consistent with that of Nato et al that PON1 activity was apparently higher in genetic CETP-deficient patients than in control subjects with the same PON1 genotype.24 For the first time, we demonstrated that the inhibition of CETP activity by JTT-705 in rabbits increased plasma and HDL-associated PAF-AH activity. Because the plasma lyso-PC concentration was decreased by JTT-705, it is possible that HDL-PAF-AH activity is increased because of a decrease in substrates including oxidized phospholipids. Therefore, the inhibition of CETP may improve the anti-oxidative and anti-inflammatory properties of HDL.
In conclusion, the inhibition of CETP activity by JTT-705 not only increases the quantity of HDL including HDL-C and charge-based HDL subfractions but also favorably affects the subpopulation distribution and apolipoprotein and enzyme composition of HDL. Therefore, the inhibition of CETP activity could be a promising approach against atherosclerosis in conjunction with LDL-C–lowering by statins. However, further studies in humans are needed to confirm our findings in animals.
Acknowledgments
We thank Dr Jianglin Fan for his useful instruction in measurement of rabbit apoE. We thank Dr Junko Ono, Hironobu Kawashima, and Sadako Harada for their kind support in measurements using the Hitachi auto-analyzer.
This work was supported by grants-in-aid from the Ministry of Education, Science, and Culture of Japan (12670712, 15790403, and 16590806), by a research grant from the Clinical Research, by research grants from the Ministry of Health and Welfare, by grant of Uehara Memorial Foundation (2002), and by research grants (996006 and 026001) from the Central Research Institute of Fukuoka University.
References
Castelli WP. Cholesterol and lipids in the risk of coronary artery disease–the Framingham Heart Study. Can J Cardiol. 1988; 4 (Suppl A): 5A–10A.
Barter PJ, Brewer HB, Jr, Chapman MJ, Hennekens CH, Rader DJ, Tall AR. Cholesteryl ester transfer protein: a novel target for raising HDL and inhibiting atherosclerosis. Arterioscler Thromb Vasc Biol. 2003; 23: 160–167.
Yamashita S, Sprecher DL, Sakai N, Matsuzawa Y, Tarui S, Hui DY. Accumulation of apolipoprotein E-rich high density lipoproteins in hyperalphalipoproteinemic human subjects with plasma cholesteryl ester transfer protein deficiency. J Clin Invest. 1990; 86: 688–695.
de Grooth GJ, Kuivenhoven JA, Stalenhoef AF, de Graaf J, Zwinderman AH, Posma JL, van Tol A, Kastelein JJ. Efficacy and safety of a novel cholesteryl ester transfer protein inhibitor, JTT-705, in humans: a randomized phase II dose-response study. Circulation. 2002; 105: 2159–2165.
Clark RW, Sutfin TA, Ruggeri RB, Willauer AT, Sugarman ED, Magnus-Aryitey G, Cosgrove PG, Sand TM, Wester RT, Williams JA, Perlman ME, Bamberger MJ. Raising high-density lipoprotein in humans through inhibition of cholesteryl ester transfer protein: an initial multidose study of torcetrapib. Arterioscler Thromb Vasc Biol. 2004; 24: 490–497.
Brousseau ME, Schaefer EJ, Wolfe ML, Bloedon LT, Digenio AG, Clark RW, Mancuso JP, Rader DJ. Effects of an inhibitor of cholesteryl ester transfer protein on HDL cholesterol. N Engl J Med. 2004; 350: 1505–1515.
Dobiasova M, Frohlich J. Understanding the mechanism of LCAT reaction may help to explain the high predictive value of LDL/HDL cholesterol ratio. Physiol Res. 1998; 47: 387–397.
Dobiasova M, Adler L, Ohta T, Frohlich J. Effect of labeling of plasma lipoproteins with cholesterol on values of esterification rate of cholesterol in apolipoprotein B-depleted plasma. J Lipid Res. 2000; 41: 1356–1357.
Frohlich J, Dobiasova M. Fractional esterification rate of cholesterol and ratio of triglycerides to HDL-cholesterol are powerful predictors of positive findings on coronary angiography. Clin Chem. 2003; 49: 1873–1880.
Dobiasova M, Frohlich JJ. Advances in understanding of the role of lecithin cholesterol acyltransferase (LCAT) in cholesterol transport. Clin Chim Acta. 1999; 286: 257–271.
Dobiasova M, Frohlich JJ. Assays of lecithin cholesterol acyltransferase (LCAT). Methods Mol Biol. 1998; 110: 217–230.
Dobiasova M, Frohlich J. Measurement of fractional esterification rate of cholesterol in plasma depleted of apolipoprotein B containing lipoprotein: methods and normal values. Physiol Res. 1996; 45: 65–73.
Dobiasova M, Stribrna J, Frohlich JJ. Relation of cholesterol esterification rate to the plasma distribution of high-density lipoprotein subclasses in normal and hypertensive women. Clin Invest Med. 1995; 18: 449–454.
Dobiasova M, Frohlich JJ. Structural and functional assessment of high-density lipoprotein heterogeneity. Clin Chem. 1994; 40: 1554–1558.
Dobiasova M, Stribrna J, Pritchard PH, Frohlich JJ. Cholesterol esterification rate in plasma depleted of very low and low density lipoproteins is controlled by the proportion of HDL2 and HDL3 subclasses: study in hypertensive and normal middle-aged and septuagenarian men. J Lipid Res. 1992; 33: 1411–1418.
Saku K, Zhang B, Ohta T, Arakawa K. Quantity and function of high density lipoprotein as an indicator of coronary atherosclerosis. J Am Coll Cardiol. 1999; 33: 436–443.
Schmitz G, Mollers C, Richter V. Analytical capillary isotachophoresis of human serum lipoproteins. Electrophoresis. 1997; 18: 1807–1813.
Bottcher A, Schlosser J, Kronenberg F, Dieplinger H, Knipping G, Lackner KJ, Schmitz G. Preparative free-solution isotachophoresis for separation of human plasma lipoproteins: apolipoprotein and lipid composition of HDL subfractions. J Lipid Res. 2000; 41: 905–915.
Barlage S, Frohlich D, Bottcher A, Jauhiainen M, Muller HP, Noetzel F, Rothe G, Schutt C, Linke RP, Lackner KJ, Ehnholm C, Schmitz G. ApoE-containing high density lipoproteins and phospholipid transfer protein activity increase in patients with a systemic inflammatory response. J Lipid Res. 2001; 42: 281–290.
Chiba H, Eto M, Fujisawa S, Akizawa K, Intoh S, Miyata O, Noda K, Matsuno K, Kobayashi K. Increased plasma apolipoprotein E-rich high-density lipoprotein and its effect on serum high-density lipoprotein cholesterol determination in patients with familial hyperalphalipoproteinemia due to cholesteryl ester transfer activity deficiency. Biochem Med Metab Biol. 1993; 49: 79–89.
Mitchell CD, King WC, Applegate KR, Forte T, Glomset JA, Norum KR, Gjone E. Characterization of apolipoprotein E-rich high density lipoproteins in familial lecithin: cholesterol acyltransferase deficiency. J Lipid Res. 1980; 21: 625–634.
Wilson HM, Patel JC, Russell D, Skinner ER. Alterations in the concentration of an apolipoprotein E-containing subfraction of plasma high density lipoprotein in coronary heart disease. Clin Chim Acta. 1993; 220: 175–187.
Navab M, Berliner JA, Subbanagounder G, Hama S, Lusis AJ, Castellani LW, Reddy S, Shih D, Shi W, Watson AD, Van Lenten BJ, Vora D, Fogelman AM. HDL and the inflammatory response induced by LDL-derived oxidized phospholipids. Arterioscler Thromb Vasc Biol. 2001; 21: 481–488.
Noto H, Kawamura M, Hashimoto Y, Satoh H, Hara M, Iso-o N, Togo M, Kimura S, Tsukamoto K. Modulation of HDL metabolism by probucol in complete cholesteryl ester transfer protein deficiency. Atherosclerosis. 2003; 171: 131–136.
Tselepis AD, John Chapman M. Inflammation, bioactive lipids and atherosclerosis: potential roles of a lipoprotein-associated phospholipase A2, platelet activating factor-acetylhydrolase. Atheroscler Suppl. 2002; 3: 57–68.
Shimoji E, Zhang B, Fan P, Saku K. Inhibition of cholesteryl ester transfer protein increases serum apolipoprotein (apo) A-I levels by increasing the synthesis of apo A-I in rabbits. Atherosclerosis. 2004; 172: 247–257.
Zhang B, Shimoji E, Fan P, Saku K. Metabolic background modulates the effects of cholesteryl ester transfer protein (CETP) inhibition on the kinetics, function, and composition of high density lipoprotein (HDL) particles. Circulation. 2003; 108: IV-196(abstract).
Moriyama K, Sasaki J, Arakawa F, Takami N, Maeda E, Matsunaga A, Takada Y, Midorikawa K, Yanase T, Yoshino G, et al. Two novel point mutations in the lecithin: cholesterol acyltransferase (LCAT) gene resulting in LCAT deficiency: LCAT (G873 deletion) and LCAT (Gly344–>Ser). J Lipid Res. 1995; 36: 2329–2343.
Soutar AK, Knight BL, Myant NB. The characterization of lipoproteins in the high density fraction obtained from patients with familial lecithin: cholesterol acyltransferase deficiency and their interaction with cultured human fibroblasts. J Lipid Res. 1982; 23: 380–390.
Berard AM, Clerc M, Brewer B, Jr., Santamarina-Fojo S. A normal rate of cellular cholesterol removal can be mediated by plasma from a patient with familial lecithin-cholesterol acyltransferase (LCAT) deficiency. Clin Chim Acta. 2001; 314: 131–139.
Fagan AM, Bu G, Sun Y, Daugherty A, Holtzman DM. Apolipoprotein E-containing high density lipoprotein promotes neurite outgrowth and is a ligand for the low density lipoprotein receptor-related protein. J Biol Chem. 1996; 271: 30121–30125.
Taira K, Bujo H, Hirayama S, Yamazaki H, Kanaki T, Takahashi K, Ishii I, Miida T, Schneider WJ, Saito Y. LR11, a mosaic LDL receptor family member, mediates the uptake of ApoE-rich lipoproteins in vitro. Arterioscler Thromb Vasc Biol. 2001; 21: 1501–1506.
Li X, Kan HY, Lavrentiadou S, Krieger M, Zannis V. Reconstituted discoidal ApoE-phospholipid particles are ligands for the scavenger receptor BI. The amino-terminal 1–165 domain of ApoE suffices for receptor binding. J Biol Chem. 2002; 277: 21149–21157.
Bultel-Brienne S, Lestavel S, Pilon A, Laffont I, Tailleux A, Fruchart JC, Siest G, Clavey V. Lipid free apolipoprotein E binds to the class B Type I scavenger receptor I (SR-BI) and enhances cholesteryl ester uptake from lipoproteins. J Biol Chem. 2002; 277: 36092–36099.
Thuahnai ST, Lund-Katz S, Anantharamaiah GM, Williams DL, Phillips MC. A quantitative analysis of apolipoprotein binding to SR-BI: multiple binding sites for lipid-free and lipid-associated apolipoproteins. J Lipid Res. 2003; 44: 1132–1142.