High prebeta1-HDL levels in hypercholesterolemia are maintained by probucol but reduced by a low-cholesterol diet

Modification of High-Density Lipoprotein Functions by Diet and Other Lifestyle Changes: A Systematic Review of Randomized Controlled Trials

High-density lipoprotein (HDL) functional traits have emerged as relevant elements that may explain HDL antiatherogenic capacity better than HDL cholesterol levels. These properties have been improved in several lifestyle intervention trials. The aim of this systematic review is to summarize the results of such trials of the most commonly used dietary modifications (fatty acids, cholesterol, antioxidants, alcohol, and calorie restriction) and physical activity. Articles were screened from the Medline database until March 2021, and 118 randomized controlled trials were selected. Results from HDL functions and associated functional components were extracted, including cholesterol efflux capacity, cholesteryl ester transfer protein, lecithin-cholesterol acyltransferase, HDL antioxidant capacity, HDL oxidation status, paraoxonase-1 activity, HDL anti-inflammatory and endothelial protection capacity, HDL-associated phospholipase A2, HDL-associated serum amyloid A, and HDL-alpha-1-antitrypsin. In mainly short-term clinical trials, the consumption of monounsaturated and polyunsaturated fatty acids (particularly omega-3 in fish), and dietary antioxidants showed benefits to HDL functionality, especially in subjects with cardiovascular risk factors. In this regard, antioxidant-rich dietary patterns were able to improve HDL function in both healthy individuals and subjects at high cardiovascular risk. In addition, in randomized trial assays performed mainly in healthy individuals, reverse cholesterol transport with ethanol in moderate quantities enhanced HDL function. Nevertheless, the evidence summarized was of unclear quality and short-term nature and presented heterogeneity in lifestyle modifications, trial designs, and biochemical techniques for the assessment of HDL functions. Such findings should therefore be interpreted with caution. Large-scale, long-term, randomized, controlled trials in different populations and individuals with diverse pathologies are warranted.

Preβ1-high-density lipoprotein metabolism is delayed in patients with chronic kidney disease not on hemodialysis

BACKGROUND

Preβ1-high-density lipoprotein (HDL) is a lipid-poor cholesterol acceptor that is converted to lipid-rich HDL by lecithin-cholesterol acyltransferase (LCAT). In patients receiving hemodialysis, preβ1-HDL metabolism is hampered even if HDL cholesterol is normal. Hemodialysis may affect preβ1-HDL metabolism by releasing lipases from the vascular wall due to heparin.

OBJECTIVES

We investigated whether preβ1-HDL metabolism is delayed in patients with chronic kidney disease (CKD) who are not receiving hemodialysis.

METHODS

We examined 44 patients with Stage 3 or higher CKD and 22 healthy volunteers (Control group). The patients with CKD were divided into those without renal replacement therapy (CKD group, n = 22) and those undergoing continuous ambulatory peritoneal dialysis (CAPD group, n = 22). Plasma preβ1-HDL concentrations were determined by immunoassay. During incubation at 37°C, we used 5,5-dithio-bis (2-nitrobenzoic acid) (DTNB) to inhibit LCAT activity and defined the conversion halftime of preβ1-HDL (CHT_preβ1) as the time required for the difference in preβ1-HDL concentration in the presence and absence of 5,5-DTNB to reach half the baseline concentration.

RESULTS

The absolute and relative preβ1-HDL concentrations were higher, and CHT_preβ1 was longer in the CKD and CAPD groups than in the Control group. Preβ1-HDL concentration was significantly correlated with CHT_preβ1 but not with LCAT activity in patients with CKD and CAPD.

CONCLUSION

Preβ1-HDL metabolism is delayed in patients with CKD who are not on hemodialysis. This preβ1-HDL metabolic delay may progress as renal function declines.

Elevated levels of preβ1-high-density lipoprotein are associated with cholesterol ester transfer protein, the presence and severity of coronary artery disease

Background

Preβ1-high-density lipoprotein (preβ1-HDL), plays an important role in reverse cholesterol transport and exhibits potent risk for coronary artery disease (CAD). However, the association of plasma preβ1-HDL and cholesterol ester transfer protein (CETP) levels in CAD patients and the relationship of preβ1-HDL with extent of CAD are debatable.

Methods

Preβ1-HDL and CETP levels were measured by enzymed-linked immunosorbent assay (ELISAs) in 88 acute coronary syndromes (ACS), 79 stable coronary artery disease (SCAD) patients and 85 control subjects. The correlation analyses, multiple linear regression analyses and logistic regression analyses were performed, respectively.

Results

The preβ1-HDL and CETP levels in ACS patients were significantly higher than those in SCAD patients and both of them were higher than controls’. Preβ1-HDL levels were positively associated with CETP (R = 0.348, P = 0.000), the diameter of stenosis (R = 0.253, P = 0.005), the number of vessel disease (R = 0.274, P = 0.002) and Gensini score (R = 0.227, P = 0.009) in CAD patients. Stepwise multiple linear regression analyses showed that CETP was one of the determinants of preβ1-HDL levels. Logistic regression analysis revealed that elevated preβ1-HDL and CETP were potential risk factors for both ACS and SCAD.

Conclusion

The elevated preβ1-HDL levels may change with CETP concentrations in CAD patients and were related to the presence and severity of CAD.

Rationale and Design of the PROSPECTIVE Trial: Probucol Trial for Secondary Prevention of Atherosclerotic Events in Patients with Prior Coronary Heart Disease

BACKGROUND

Reduction of serum LDL-cholesterol by statins was shown to improve clinical outcomes in patients with coronary heart disease (CHD). Although intensive statin therapy significantly reduced cardiovascular risks, atherosclerotic cardiovascular events have not been completely prevented. Therefore, effective pharmacologic therapy is necessary to improve "residual risks" in combination with statins. Probucol has a potent antioxidative effect, inhibits the oxidation of LDL, and reduces xanthomas. Probucol Trial for Secondary Prevention of Atherosclerotic Events in Patients with Prior Coronary Heart Disease (PROSPECTIVE) is a multicenter, randomized, prospective study designed to test the hypothesis that the addition of probucol to other lipid-lowering drugs will prevent cerebro- and cardiovascular events in patients with prior coronary events and high LDL cholesterol levels.

STUDY DESIGN

The study will recruit approximately 860 patients with a prior CHD and dyslipidemia with LDL-C level ≥140 mg/dl without any medication and those treated with any lipid-lowering drugs with LDL-C level ≥100 mg/dl. Lipid-lowering agents are continuously administered during the study period in control group, and probucol (500 mg/day, 250 mg twice daily) is added to lipid-lowering therapy in the test group. The efficacy and safety of probucol with regard to the prevention of cerebro- and cardiovascular events and the intima-media thickness of carotid arteries as a surrogate marker will be evaluated.

SUMMARY

PROSPECTIVE will determine whether the addition of probucol to other lipid-lowering drugs improves cerebro- and cardiovascular outcomes in patients with prior coronary heart disease. Furthermore, the safety of a long-term treatment with probucol will be clarified.

Did we abandon probucol too soon?

PURPOSE OF REVIEW

Probucol is a potent antioxidative drug that has been used for prevention and treatment of atherosclerotic cardiovascular diseases and xanthoma. Probucol has been used as a lipid-lowering drug for a long time especially in Japan, although Western countries quitted its use because of the reduction in serum HDL-cholesterol (HDL-C). This review highlights both basic and clinical studies that provide new insights into the pleiotropic effects of probucol.

RECENT FINDINGS

Recently, the mechanisms for the pharmacologic actions of probucol have been elucidated at the molecular level with a special focus on HDL metabolism and its functions. Probucol enhances plasma cholesteryl ester transfer protein activity and hepatic scavenger receptor class B type I, causing a decrease in HDL-C. It also accelerates the antioxidative function of HDL via increase in paraoxonase 1 activity. Recent retrospective analyses of probucol-treated patients with heterozygous familial hypercholesterolemia and those after coronary revascularization demonstrated a strong beneficial effect of probucol on secondary prevention of cardiovascular events and mortality.

SUMMARY

Probucol has pleiotropic and beneficial therapeutic effects on cardiovascular system. Although statins are effective for lowering LDL-cholesterol (LDL-C) and reducing coronary heart disease risk, probucol should be considered as an option in case statins are not effective.

Preparation and activity analysis of recombinant human high-density lipoprotein

Population studies have consistently shown a highly inverse correlation between plasma concentration of high-density lipoprotein and the risk of atherosclerotic cardiovascular disease in humans. High-density lipoprotein (HDL) as a therapeutic target is an intense area of ongoing investigation. Aiming to solve the shortcomings of native HDL application, we prepared recombinant human HDL (rhHDL) that contains a similar composition and has similar functions with native HDL. Six kinds of recombinant human apolipoproteins (rhapo)-rhapoA-I, rhapoA-II, rhapoA-IV, rhapoC-I, rhapoC-II, and rhapoE-were expressed in Pichia pastoris and purified with chromatography. By the facilitation of cholate, six kinds of rhapo penetrated among the phosphatidylcholine acyl chains. After purification by density-gradient centrifugation, rhHDL was acquired. Based on morphological observation, we confirmed that the micellar complexes of rhapo with phosphatidylcholine and cholesterol were prepared. We carried on comparative studies in vitro and in vivo between native HDL and rhHDL. Cellular cholesterol efflux assays showed that rhHDL could promote the efflux of excess cholesterol from macrophages. Furthermore, rhHDL has similar effects with native HDL on the blood lipid metabolism in hyperlipidemic mice. In conclusion, rhHDL has similar effects on antiatherosclerosis with native HDL through reverse cholesterol transport, antioxidative, and antithrombotic properties. It could be used as a therapeutic HDL-replacement agent.

Development of a method to measure preβHDL and αHDL apoA-I enrichment for stable isotopic studies of HDL kinetics

Our understanding of HDL metabolism would be enhanced by the measurement of the kinetics of preβHDL, the nascent form of HDL, since elevated levels have been reported in patients with coronary artery disease. Stable isotope methodology is an established technique that has enabled the determination of the kinetics (production and catabolism) of total HDL apoA-I in vivo. The development of separation procedures to obtain a preβHDL fraction, the isotopic enrichment of which could then be measured, would enable further understanding of the pathways in vivo for determining the fate of preβHDL and the formation of αHDL. A method was developed and optimised to separate and measure preβHDL and αHDL apoA-I enrichment. Agarose gel electrophoresis was first used to separate lipoprotein subclasses, and then a 4-10 % discontinuous SDS-PAGE used to isolate apoA-I. Measures of preβHDL enrichment in six healthy subjects were undertaken following an infusion of L-[1-¹³C-leucine]. After isolation of preβ and αHDL, the isotopic enrichment of apoA-I for each fraction was measured by gas chromatography-mass spectrometry. PreβHDL apoA-I enrichment was measured with a CV of 0.51 % and αHDL apoA-I with a CV of 0.34 %. The fractional catabolic rate (FCR) of preβHDL apoA-I was significantly higher than the FCR of αHDL apoA-I (p < 0.005). This methodology can be used to selectively isolate preβ and αHDL apoA-I for the measurement of apoA-I isotopic enrichment for kinetics studies of HDL subclass metabolism in a research setting.

Low-fat diets for acquired hypercholesterolaemia

BACKGROUND

Hypercholesterolaemia, characterised by raised blood cholesterol levels, is not a disease itself but a metabolic derangement that often contributes to many diseases, notably cardiovascular disease. In most cases, elevated cholesterol levels are associated with high-fat diet, especially saturated fat, coupled with an inactive lifestyle. Less commonly, raised cholesterol may be related to an inherited disorder, familial hypercholesterolaemia. This systematic review is only concerned with acquired hypercholesterolaemia.

OBJECTIVES

To assess the effects of low-fat diets for acquired hypercholesterolaemia and to investigate the incidence of adverse effects from low-fat dietary interventions. We planned to compare the relative effectiveness of low-fat diets with calorie-restricted diets for acquired hypercholesterolaemia. We also wanted to look into the relative effectiveness of low-fat diets and pharmacological interventions for acquired hypercholesterolaemia.

SEARCH STRATEGY

Studies were obtained from computerised searches of The Cochrane Library, MEDLINE, EMBASE and databases of ongoing trials. Date of last search was February 2010.

SELECTION CRITERIA

Otherwise healthy adults (equal to or greater than 18 years) with acquired (not familial) hypercholesterolaemia. We defined hypercholesterolaemia as either total cholesterol greater than 5.2 mmol/L, LDL-cholesterol greater than 3.0 mmol/L, HDL-cholesterol less than 1.0 mmol/L or a combination thereof, although investigators' definitions were also accepted. We wanted to include any low-fat dietary intervention, like low-fat and low-saturated fat diets, intended to lower serum total and LDL-cholesterol or to raise HDL-cholesterol. A low-fat diet was considered as a fat calorie intake less than 20% of the total calories. The minimum duration of the intervention had to be six months. We excluded studies in unhealthy people.

DATA COLLECTION AND ANALYSIS

Two authors were planned to independently assess risk of bias and extract data.

MAIN RESULTS

No study met our inclusion criteria.

AUTHORS' CONCLUSIONS

Well designed, adequately powered randomised controlled trials investigating patient-relevant outcomes of low-fat diets for otherwise healthy people with hypercholesterolaemia are required.

High pre-beta1 HDL concentrations and low lecithin: cholesterol acyltransferase activities are strong positive risk markers for ischemic heart disease and independent of HDL-cholesterol

BACKGROUND

We hypothesized that patients with high HDL-cholesterol (HDL-C) and ischemic heart disease (IHD) may have dysfunctional HDL or unrecognized nonconventional risk factors.

METHODS

Individuals with IHD (Copenhagen University Hospital) and either high HDL-C (n = 53; women >or=735 mg/L; men >or=619 mg/L) or low HDL-C (n = 42; women <or=387 mg/L; men <or=341 mg/L) were compared with individuals without IHD (Copenhagen City Heart Study) matched by age, sex, and HDL-C concentrations (n = 110). All participants had concentrations within reference intervals for LDL-C (<1600 mg/L) and triglyceride (<1500 mg/L), and none were treated with lipid-lowering medications. Pre-beta(1) HDL and phospholipid transfer protein concentrations were measured by using commercial kits and lecithin:cholesterol acyltransferase (LCAT) activity by using a proteoliposome cholesterol esterification assay.

RESULTS

Pre-beta(1) HDL concentrations were 2-fold higher in individuals with IHD vs no IHD in both the high [63 (5.7) vs 35 (2.3) mg/L; P < 0.0001] and low HDL-C [49 (5.0) vs 27 (1.5) mg/L; P = 0.001] groups. Low LCAT activity was also associated with IHD in the high [95.2 (6.7) vs 123.0 (5.3) micromol x L(-1) x h(-1); P = 0.002] and low [93.4 (8.3) vs 113.5 (4.9) micromol x L(-1) . h(-1); P = 0.03] HDL-C groups. ROC curves for pre-beta(1) HDL in the high-HDL-C groups yielded an area under the curve of 0.71 (95% CI: 0.61-0.81) for predicting IHD, which increased to 0.92 (0.87-0.97) when LCAT was included. Similar results were obtained for low HDL-C groups. An inverse correlation between LCAT activity and pre-beta(1) HDL was observed (r(2) = 0.30; P < 0.0001) in IHD participants, which was stronger in the low HDL-C group (r(2) = 0.56; P < 0.0001).

CONCLUSIONS

IHD was associated with high pre-beta(1) HDL concentrations and low LCAT levels, yielding correct classification in more than 90% of the IHD cases for which both were measured, thus making pre-beta(1) HDL concentration and LCAT activity level potentially useful diagnostic markers for cardiovascular disease.

Plasma triglyceride levels and body mass index values are the most important determinants of prebeta-1 HDL concentrations in patients with various types of primary dyslipidemia

OBJECTIVE

Experimental studies have shown that the prebeta-1 subclass of high-density lipoprotein particles (prebeta-1 HDL) may play an important role in the reverse cholesterol transport pathway as the initial acceptors of cellular cholesterol. The aim of the present study was the direct comparison of prebeta-1 HDL values in individuals with various types of primary dyslipidemias.

METHODS

Four hundred and eighty-six unrelated individuals were included in the study. According to their lipid values study participants were subdivided into four groups: control group (n=206), type IIA dyslipidemia group (n=148), type IIB dyslipidemia group (n=49) and type IV dyslipidemia group (n=83).

RESULTS

All dyslipidemic patients displayed higher concentrations of prebeta-1 HDL compared to control individuals. However, patients with dyslipidemias characterized by an abnormal catabolism of triglyceride-rich lipoproteins (such as dyslipidemias of type IIB and IV) tend to have higher prebeta-1 HDL values compared to patients with hypercholesterolemia, and this increase is proportional to the degree of hypertriglyceridemia. In addition, patients with metabolic syndrome exhibited significantly higher levels of prebeta-1 HDL compared to individuals that do not fulfill the criteria for the diagnosis of this syndrome. Multiple regression analysis revealed that serum triglyceride concentrations and body mass index (BMI) values were the most important determinants of prebeta-1 HDL levels in our population.

CONCLUSION

All dyslipidemic patients exhibit increased prebeta-1 HDL concentrations as compared to normolipidemic individuals. Whether this increase represents a defensive mechanism against atherosclerosis or it is indicative of impaired maturation of HDL particles and thus of a defective reverse cholesterol transport mechanism remains to be established.

A low‐saturated‐fat, low‐cholesterol diet decreases plasma CETP activity and pre β‐HDL formation but does not affect cellular cholesterol efflux to plasma from type 1 diabetic patients

The aim of this study was to evaluate the effect of a low-saturated-fat, low-cholesterol diet on plasma lipopoproteins, pre beta-high density lipoprotein (HDL) formation, lecithin:cholesterol acyltransferase (LCAT), cholesteryl ester transfer protein (CETP) and phospholipid transfer protein (PLTP) activities, as well as on the ability of plasma to stimulate cellular cholesterol efflux. Twelve male type 1 diabetic patients with plasma cholesterol >5.0 mmol/L were studied while consuming their usual diet and after 6 weeks of a low-fat, low-cholesterol diet. Pre beta-HDL formation was measured using crossed immuno-electrophoresis. Plasma LCAT, CETP and PLTP activities were assayed by exogenous substrate methods. The ability of plasma to promote cellular cholesterol efflux out of Fu5AH rat hepatoma cells and out of human skin fibroblasts was also determined. Saturated fat intake was lowered (p = 0.001) due to replacement with carbohydrates, while mono- and polyunsaturated fat intake remained unchanged. Cholesterol intake decreased as well (p = 0.003). The changes in plasma total cholesterol, very low and low-density lipoprotein (VLDL+LDL) cholesterol, HDL cholesterol, HDL phospholipids, apolipoprotein (apo) A-I, plasma LCAT activity and PLTP activity were not significant. Plasma CETP activity (p = 0.008) and pre beta-HDL formation (p = 0.008) decreased. The ability of plasma to promote cholesterol efflux out of fibroblasts and Fu5AH cells remained unchanged. Reduction in dietary saturated fat and cholesterol intake does not adversely affect cellular cholesterol efflux to plasma from type 1 diabetic patients, despite a drop in pre beta-HDL formation.

Relationship between apolipoproteins and the alteration of HDL subclasses in hyperlipidemic subjects

BACKGROUND

To elucidate the relationship between the apolipoproteins, especially apoA-I and the alteration of HDL subclasses in hyperlipidemic, HTC and HTG subjects.

METHODS

ApoA-I contents of plasma HDL subclasses were quantitated by two-dimensional gel electrophoresis coupled with immunodetection in 233 normolipidemic subjects and 312 hyperlipidemic subjects (132 HTC and 180 HTG subjects). Making use of the mean +/-1 SD of apoA-I levels, we further subdivided normolipidemic, hyperlipidemic, HTC and HTG subjects into 3 subgroups, respectively.

RESULTS

Subjects in the middle and low apoA-I subgroups had decreased HDL-C and apoA-I while increased TG, apoB100, apoCII, apoCIII and apoE concentrations. With the reduction of apoA-I concentrations, the apoA-I contents of all HDL subclasses decreased successively and significantly. The relative percentage of small-sized HDL increased significantly while those of large-sized HDL(2a), HDL(2b) decreased significantly in hyperlipidemic, especially in HTG group. Multiple liner regression result revealed that apoA-I was positively and significantly correlated with all HDL subclasses and apoA-I level influenced the distribution of HDL subclasses powerfully in hyperlipidemic subjects.

CONCLUSIONS

Both the rate and efficiency of RCT might be weakened more seriously in hyperlipidemic, especially in HTG subjects with low apoA-I levels. ApoA-I level might be a powerful factor correlated with the distributions of HDL subclasses.

Relationship Between Apolipoprotein Concentrations and HDL Subclasses Distribution

Alterations in plasma apolipoproteins levels can influence the composition, content, and distribution of plasma lipoproteins that affect the risk of atherosclerosis. This study assessed the relationship between plasma apolipoproteins levels, mainly apoAI, and HDL subclass distribution. The contents of plasma HDL subclasses were determined by two-dimensional gel electrophoresis coupled with immunodetection in 545 Chinese subjects. Compared with a low apoAI group, the contents of all HDL subclasses increased significantly both in middle and high apoAI group, and the contents of large-sized HDL(2b) increased more significantly relative to those of small-sized prebeta(1)-HDL in a high apoAI group. When apoAI and HDL-C levels increased simultaneously, in comparison to a low apoAI along with HDL-C concentration group, a significant increase (116%) was shown in HDL2b but only a slight increase (26%) in prebeta1-HDL. In addition, Pearson correlation analysis revealed that apoAI levels were positively and significantly correlated with all HDL subclasses. Multiple liner regression demonstrated that the apoAI concentrations were the most powerful predictor for HDL subclass distribution. With the elevation of apoAI concentrations, the contents of all HDL subclasses increased successively and significantly, especially, an increase in large-sized HDL(2b). Further, when apoAI and HDL-C concentrations increased simultaneously, the shift to larger HDL size was more obvious. Which, in turn, indicated that HDL maturation might be enhanced and, the reverse cholesterol transport might be strengthened along with apoAI levels which might be a more powerful factor influencing the distribution of HDL subclasses.

Alterations of high-density lipoprotein subclasses in hypercholesterolemia and combined hyperlipidemia

BACKGROUND

Alterations in plasma lipid levels can influence the composition, content, and distribution of plasma lipoprotein subclasses that effect atherosclerosis risk. Hypercholesterolemia and combined hyperlipidemia are common forms of atherogenic dyslipoproteinemia. This study evaluates the alterations of high-density lipoprotein (HDL) subclasses in hypercholesterolemic and combined hyperlipidemic subjects.

METHODS

Apolipoprotein A-I contents of plasma HDL subclasses were quantitated by 2-dimensional gel electrophoresis in 242 normolipidemic subjects, 66 hypercholesterolemic subjects and 59 combined hyperlipidemic subjects.

RESULTS

Compared with the normolipidemic subjects, apolipoprotein A-I contents of small-sized pre-beta1-HDL, HDL3c, HDL3b and HDL3a were significantly higher in both hypercholesterolemic subjects (p<.01, p<.05, p<.01 and p<.05, respectively) and combined hyperlipidemic subjects (p<.01, p<.05, p<.01 and p<.01, respectively). In contrast, apolipoprotein A-I contents of large-sized HDL2a and HDL2b were significantly lower in hypercholesterolemic subjects (p<.05 and p<.01, respectively) as well as combined hyperlipidemic subjects (p<.01 and p<.01, respectively). In addition, pre-beta1-HDL increased significantly (p<.05) while HDL2a and HDL2b decreased significantly (p<.05 and p<.01, respectively) in combined hyperlipidemic group versus hypercholesterolemic subjects. With the elevation of triglyceride levels, pre-beta1-HDL, and HDL3a increased successively, however, HDL2a and HDL2b decreased successively in subjects with total cholesterol levels greater than 240 mg/dl.

CONCLUSIONS

The particle size of HDL shifted towards smaller size in hypercholesterolemic subjects, and that the shift was more prominent in combined hyperlipidemic subjects. The alternations mentioned above indicate that HDL maturation might be abnormal, and reverse cholesterol transport (RCT) might be weakened.

Relationship between total cholesterol/high-density lipoprotein cholesterol ratio, triglyceride/high-density lipoprotein cholesterol ratio, and high-density lipoprotein subclasses

Alterations in plasma lipid levels can influence the composition, content, and distribution of plasma lipoprotein subclasses that affect atherosclerosis risk. This study evaluated the relationship between plasma total cholesterol (TC)/high-density lipoprotein cholesterol (HDL-C) ratio, triglyceride (TG)/HDL-C ratio, and HDL subclass distribution. The apolipoprotein A-I contents of plasma HDL subclasses were quantitated by 2-dimensional gel electrophoresis coupled with immunodetection in 442 Chinese subjects. The particle size of HDL shifted toward smaller size with the elevation of TC/HDL-C and TG/HDL-C ratios. The ratio of large-sized HDL(2b) to small-sized prebeta(1)-HDL (HDL(2b)/prebeta(1)-HDL) was about 4.7 in the subjects with TC/HDL-C of 3.3 or lower and TG/HDL-C of 2.5 or lower, whereas it was only approximately 1.1 in subjects with TC/HDL-C greater than 6 and TG/HDL-C greater than 5. Pearson correlation analysis revealed that the TC/HDL-C ratio was positively correlated with prebeta(1)-HDL and HDL(3a) but negatively correlated with HDL(2a) and HDL(2b), whereas the TC/HDL-C ratio was only inversely correlated with HDL(2b). The TC/HDL-C and TG/HDL-C ratios together may be a good indicator of HDL subclass distribution. When these 2 ratios increased simultaneously, the trend toward smaller HDL size was obvious, which, in turn, indicated that the maturation of HDL might be impeded and the reverse cholesterol transport might be weakened. In addition, the TG/HDL-C ratio might be a more powerful factor to influence the distribution of HDL subclasses.

Alterations of high density lipoprotein subclasses in obese subjects

The object of this study was to investigate the characteristics of lipid metabolism in obese subjects, with particular emphasis on the alteration of HDL subclass contents and distributions. A population of 581 Chinese individuals was divided into four groups (25 underweight subjects, 288 of desirable weight, 187 overweight, and 45 obese) according to body mass index (BMI). Apoprotein A-I (apoA-I) contents of plasma HDL sub-classes were determined by 2-D gel electrophoresis associated with an immunodetection method. The concentrations of TG and the apoA-I content of pre-beta 1-HDL were significantly higher (P < 0.01 and P < 0.01, respectively), but the levels of HDL cholesterol, and the apoA-I contents of HDL2a and HDL2b were significantly lower (P < 0.01, P < 0.05, and P < 0.01, respectively) in obese subjects than in subjects having a desirable weight. Moreover, with the elevation of BMI, small-sized pre-beta 1-HDL increased gradually and significantly, whereas large-sized HDL2b decreased gradually and significantly. Meanwhile, the variations in HDL subclass distribution were more obvious with the elevation of TG levels in obese as well as overweight subjects. In addition, Pearson correlation analysis revealed that BMI and TG levels were positively correlated with pre-beta 1-HDL but negatively correlated with HDL2b. Multiple regression analysis also showed that TG concentrations were associated independently and positively with high pre-beta 1-HDL and independently and negatively with low HDL2b in obese and overweight subjects. The HDL particle size was smaller in obese and overweight subjects. The shift to smaller size was more obvious with the elevation of BMI and TG, especially TG levels. These observations, in turn, indicated that HDL maturation might be abnormal, and reverse cholesterol transport might be impaired.

Alterations of high-density lipoprotein subclasses in endogenous hypertriglyceridemia

BACKGROUND

To investigate the alterations of high-density lipoprotein (HDL) subclasses in endogenous hypertriglyceridemic subjects.

METHODS

Apolipoprotein A-I contents of plasma HDL subclasses were quantitated by 2-dimensional gel electrophoresis in 236 normolipidemic subjects (including 146 males and 90 females) and 176 endogenous hypertriglyceridemic subjects (including 103 males and 73 females).

RESULTS

Apolipoprotein A-I contents of small-sized pre-beta1-HDL and HDL3a were significantly higher (P < .01 and P < .01, respectively), but those of large-sized HDL2a and HDL2b were significantly lower (P < .01 and P < .01, respectively) in hypertriglyceridemic subjects versus normolipidemic subjects. Moreover, with the elevation of triglyceride levels, small-sized pre-beta1-HDL and HDL3a increased successively; however, large-sized HDL2a and HDL2b decreased successively. Males had significantly higher apolipoprotein A-I contents of small-sized pre-beta1-HDL and HDL3b (P < .05 and P < .05, respectively), but lower contents of large-sized HDL2b (P < .01) than females in both normolipidemic and hypertriglyceridemic subjects.

CONCLUSIONS

The particle size of HDL shifted toward smaller size in hypertriglyceridemic subjects, especially in male subjects. Of note, the shift was more obvious with the elevation of triglyceride levels. The changes mentioned above indicate that HDL maturation might be abnormal and reverse cholesterol transport might be weakened.

Relationship between plasma HDL subclasses distribution and apoA-I gene polymorphisms

BACKGROUND

It is generally accepted that apolipoprotein (apo) A-I is the dominant structural apolipoprotein of HDL particles and different HDL subclasses have distinct but interrelated metabolic functions. HDL is known to directly affect the atherogenic process hence changes in HDL subclasses distribution may be related to the incidence and prevalence of atherosclerosis.

METHODS

The ApoA-I contents (mg/l) of plasma HDL subclasses were determined by 2-dimensional gel electrophoresis coupled with immunodetection and apoA-I genotypes were assayed by PCR-RFLP in 307 Chinese subjects (169 males, 138 females).

RESULTS

The G/G and C/C genotypes were the most frequent at -78 bp and +83 bp of apoA-I gene, respectively. There were no significant differences in the frequencies of rare A allele at -78 bp and rare T allele at +83 bp between males and females. Compared with the G/G carriers, G/A and A/A carriers had significantly higher plasma concentrations of TG, apoC-II, apoC-III, apoA-I contents of prebeta(1)-HDL, HDL(3a) and TG/HDL-C ratio. And in addition, A/A carriers had significantly lower apoA-I contents of HDL(2a) and HDL(2b). Females had increased plasma concentrations of apoA-I, HDL-C, apoA-I contents of HDL(2a) and HDL(2b) while decreased apoA-I contents of prebeta(1)-HDL, HDL(3b) and TG/HDL-C ratio as compared to males carrying the same genotype. No significant differences were demonstrated on the concentrations of plasma lipids, lipoproteins, apolipoproteins and apoA-I contents of plasma HDL subclasses between the C/C and C/T subjects.

CONCLUSION

The G/A polymorphism at -78 bp of apoA-I gene was associated with changes of HDL subclasses distribution. There was a general shift towards smaller-sized HDL, which, in turn, indicated that reverse cholesterol transport (RCT) might be weakened and HDL maturation might be abnormal in the subjects with G/A mutation.

LCAT-dependent conversion rate is a determinant of plasma prebeta1-HDL concentration in healthy Japanese

BACKGROUND

Prebeta1-HDL acts as a primary acceptor of cellular cholesterol. Prebeta1-HDL is converted into alpha-migrating high-density lipoprotein (HDL) by lecithin/cholesterol acyltransferase (LCAT). We examined whether the LCAT-dependent conversion rate of prebeta1-HDL is a determinant of the plasma prebeta1-HDL concentration in healthy Japanese.

METHODS

We measured the conversion half time (CHT(prebeta1)), the time required for 50% of baseline prebeta1-HDL to be changed into alpha-migrating HDL by LCAT, in 100 healthy Japanese (47 men, 53 women, 22-88 years).

RESULTS

Prebeta1-HDL concentration, as determined by immunoassay, was significantly lower in younger women (<50 years, n=24) than in older women (>or=50 years, n=29) (16.8+/-3.3 vs. 21.7+/-8.0 mg/l apolipoprotein AI (apoAI), p<0.01). There was no significant difference in prebeta1-HDL concentration between younger (n=24) and older (n=23) men (21.2+/-6.8 vs. 22.5+/-6.6 mg/l apoAI). The mean CHT(prebeta1) for all subjects was 47.4+/-13.0 min, and was not influenced by gender or age. Prebeta1-HDL concentration was positively correlated with CHT(prebeta1) in both men and women, suggesting that high prebeta1-HDL levels may reflect delayed conversion of prebeta1-HDL.

CONCLUSION

LCAT-dependent conversion rate is a determinant of plasma prebeta1-HDL concentration in healthy Japanese. We speculate that prebeta1-HDL concentration may be used as a metabolic marker for HDL maturation.

Relationship between plasma lipid concentrations and HDL subclasses

BACKGROUND

It is generally accepted that different high-density lipoprotein (HDL) subclasses have distinct but interrelated metabolic functions. HDL is known to directly influence the atherogenic process and changes in HDL subclasses distribution may be related to the incidence and prevalence of atherosclerosis.

METHODS

Apo-AI contents(mg/l) of plasma HDL subclasses were determined by 2-dimensional gel electrophoresis coupled with immunodetection for apo-AI. Four hundred forty-two Chinese adults subjects aged 33 to 78 years were assigned to different groups according to the third Report of NCEP (ATP III) guidelines. The subjects were first divided into 2 groups, normal and high TG, then further classified by plasma TC, HDL-C and LDL-C concentrations. The subjects were also divided into TC desirable and TC high groups.

RESULTS

Apo-A contents of prebeta(1)-HDL were higher while HDL(2b) were lower in high TG subjects vs. the corresponding normal TG subjects according to plasma TC and LDL-C concentrations. With the increase of plasma TC concentrations, apo-AI contents of prebeta(1)-HDL were significantly higher in high TC subgroup vs. TC desirable subgroup in normal TG subjects. With the decrease of HDL-C concentrations, apo-AI contents of HDL(2b) tended to decrease in normal TG subjects. And, with the increases of LDL-C concentration, in normal TG subjects, apo-AI contents of prebeta(1)-HDL and HDL(3b) were significantly higher and those of HDL(2b) were significantly lower in very high LDL-C subgroup vs. LDL-C optimal subgroup. On the other hand, apo-AI contents of prebeta(1)-HDL and HDL(3a) were significantly higher, while HDL(2a) and HDL(2b) were significantly lower in high TG and very high TG subgroup vs. normal TG subgroup within either TC desirable or TC high subjects. In a multivariate linear regression model, TG and TC concentrations were all associated independently and positively with high prebeta(1)-HDL; however, HDL-C were inversely associated with high prebeta(1)-HDL. And TG and TC concentrations were all associated independently and negatively with low HDL(2b), but HDL-C and apo-AI were positively associated with low HDL(2b).

CONCLUSIONS

With the increase of plasma TG, TC, LDL-C or the decrease of plasma HDL-C concentrations, there was a general shift toward smaller-sized HDL, which, in turn, indicates that reverse cholesterol transport might be weakened and HDL maturation might be abnormal. Plasma TG concentration is a more important factor than TC concentration on the changes of HDL subclass distribution. Moreover, when TG is normal and HDL-C decreased, large-size HDL particles tended to decrease.

T13M mutation of lecithin-cholesterol acyltransferase gene causes fish-eye disease

BACKGROUND

Lecithin-cholesterol acyltransferase (LCAT) esterifies free cholesterol (FC) in plasma and plays a crucial role in the maturation of prebeta1-HDL (lipid-poor HDL) into alpha-migrating HDL (spherical HDL). Natural mutations of LCAT gene cause familial LCAT deficiency (FLD) or fish-eye disease (FED). The relationship between mutations and their phenotypes gives important clues to the functions of specific regions of LCAT. We investigated the first homozygous case with a substitution of threonine to methionine at codon 13 (T13M) of LCAT gene.

METHODS

We evaluated LCAT activity, LCAT distribution among HDL subfractions and conversion of prebeta1-HDL to alpha-migrating HDL by native two-dimensional gel electrophoresis (N-2DGE).

RESULTS

The proband had corneal opacity, severe hypo-alpha-lipoproteinemia, half-normal LCAT activity and near normal cholesteryl ester/total cholesterol (TC) ratio in plasma. These features were characteristic of FED. Plasma prebeta1-HDL concentration was near normal, but not converted to alpha-migrating HDL during 37 degrees C incubation. As expected, alpha-migrating HDL (especially large particles) was markedly reduced. In the immunoblot against LCAT, the small alpha-migrating HDL from the proband had much less LCAT in this patient than in controls.

CONCLUSION

T13M mutation of LCAT gene causes FED.

Pharmacological modulation of cholesteryl ester transfer protein, a new therapeutic target in atherogenic dyslipidemia

In mediating the transfer of cholesteryl esters (CE) from antiatherogenic high density lipoprotein (HDL) to proatherogenic apolipoprotein (apo)-B-containing lipoprotein particles (including very low density lipoprotein [VLDL], VLDL remnants, intermediate density lipoprotein [IDL], and low density lipoprotein [LDL]), the CE transfer protein (CETP) plays a critical role not only in the reverse cholesterol transport (RCT) pathway but also in the intravascular remodeling and recycling of HDL particles. Dyslipidemic states associated with premature atherosclerotic disease and high cardiovascular risk are characterized by a disequilibrium due to an excess of circulating concentrations of atherogenic lipoproteins relative to those of atheroprotective HDL, thereby favoring arterial cholesterol deposition and enhanced atherogenesis. In such states, CETP activity is elevated and contributes significantly to the cholesterol burden in atherogenic apoB-containing lipoproteins. In reducing the numbers of acceptor particles for HDL-derived CE, both statins (VLDL, VLDL remnants, IDL, and LDL) and fibrates (primarily VLDL and VLDL remnants) act to attenuate potentially proatherogenic CETP activity in dyslipidemic states; simultaneously, CE are preferentially retained in HDL and thereby contribute to elevation in HDL-cholesterol content. Mutations in the CETP gene associated with CETP deficiency are characterized by high HDL-cholesterol levels (>60 mg/dL) and reduced cardiovascular risk. Such findings are consistent with studies of pharmacologically mediated inhibition of CETP in the rabbit, which argue strongly in favor of CETP inhibition as a valid therapeutic approach to delay atherogenesis. Consequently, new organic inhibitors of CETP are under development and present a potent tool for elevation of HDL in dyslipidemias involving low HDL levels and premature coronary artery disease, such as the dyslipidemia of type II diabetes and the metabolic syndrome. The results of clinical trials to evaluate the impact of CETP inhibition on premature atherosclerosis are eagerly awaited.

Alterations of HDL subclasses in hyperlipidemia

BACKGROUND

It is generally accepted that different high-density lipoprotein (HDL) subclasses have distinct but interrelated metabolic functions. HDL is known to directly influence the atherogenic process and changes in HDL subclasses distribution may be related to the incidence and prevalence of atherosclerosis.

METHOD

The relative apolipoprotein (apo)A-I contents (% apoA-I) of plasma HDL subclasses were determined by two-dimensional gel electrophoresis coupled with immunodetection for apoA-I, in 39 hypercholesterolemic (HTC) subjects, 97 hypertriglyceridemic (HTG) subjects and 32 mixed hyperlipidemic (MHL) subjects, and 124 normolipidemic subjects.

RESULTS

The relative apoA-I contents of prebeta(1)-HDL, prebeta(2)-HDL, HDL(3c), HDL(3b) and HDL(3a) significantly increased while HDL(2a) and HDL(2b) significantly decreased in hyperlipidemic subjects. In HTC subjects of hyperlipidemia, the concentrations of prebeta(1)-HDL were significantly lower and HDL(2b) concentrations were significantly higher than in HTG and MHL subjects. In HTG subjects, the concentrations of HDL(3a) were significantly higher and the concentrations of HDL(2b) were lower than in HTC and MHL subjects. In total hyperlipidemic subjects, plasma triglyceride (TG) concentrations showed positive correlation with prebeta(1)-HDL, prebeta(2)-HDL, HDL(3b) and HDL(3a) and negative correlation with HDL(2a) and HDL(2b). The total cholesterol (TC) concentrations showed positive correlation with the relative apoA-I contents of prebeta(1)-HDL and HDL(3b), whereas the HDL-C concentrations showed negative correlation with the relative apoA-I contents of prebeta(1)-HDL and HDL(3a) and positive correlation with those of HDL(2a) and HDL(2b). The relative apoA-I contents of prebeta(1)-HDL, prebeta(2)-HDL, HDL(3b), and HDL(3a) were positively correlated whereas those of HDL(2a) and HDL(2b) were negatively correlated with TG/HDL-C ratio.

CONCLUSION

The particle size of HDL in hyperlipidemic subjects shifted towards smaller sizes, which, in turn, indicates that the maturation of HDL may be abnormal in hyperlipidemic subjects.

LCAT-dependent conversion of prebeta1-HDL into alpha-migrating HDL is severely delayed in hemodialysis patients

Prebeta1-HDL is a minor HDL subfraction that acts as an efficient initial acceptor of cell-derived free cholesterol. During 37 degrees C incubation, plasma prebeta1-HDL decreases over time due to its conversion to alpha-migrating HDL by lecithin:cholesterol acyltransferase (LCAT). This conversion may be delayed in hemodialysis patients who have decreased LCAT activity. To clarify whether LCAT-dependent conversion of prebeta1-HDL to alpha-migrating HDL is delayed in hemodialysis patients, prebeta1-HDL concentrations were determined in 45 hemodialysis patients and 45 gender-matched control subjects before and after 37 degrees C incubation with and without the LCAT inhibitor. It was found that the baseline prebeta1-HDL concentration in hemodialysis patients was more than twice that in the controls (44.9 +/- 21.4 versus 19.8 +/- 6.7 mg/L apoAI; P < 0.001). After 2-h incubation, the LCAT-dependent decrease in prebeta1-HDL in hemodialysis patients was about one-third of that in the controls (30 +/- 27 versus 97 +/- 17% of baseline; P < 0.01). The LCAT-dependent rate of decrease in prebeta1-HDL levels (DR(prebeta1)) was the same for samples from hemodialysis patients exhibiting normal (> or =1.03 mmol/L) and low HDL-cholesterol levels (32 +/- 32 versus 28 +/- 23% of baseline; NS). DR(prebeta1) was positively correlated with LCAT activity (r = 0.617; P < 0.001). In conclusion, the LCAT-dependent conversion of prebeta1-HDL to alpha-migrating HDL is severely delayed in hemodialysis patients. The impaired catabolism of prebeta1-HDL may accelerate atherosclerosis in hemodialysis patients.

Single session exercise stimulates formation of pre beta 1-HDL in leg muscle

Physical activity can raise the level of circulating HDL cholesterol. Pre beta 1-HDL is thought to be either the initial acceptor of cellular cholesterol or virtually the first particle in the pathway of the formation of HDL from apolipoprotein A-I and cellular lipids. We have therefore sought to identify pre beta 1-HDL in arterial and venous circulations of exercising legs in healthy individuals and in subjects with stable Type 2 diabetes mellitus. Blood samples were taken simultaneously from the femoral artery and vein before and after 25 min cycling exercise. The major findings were, first, that exercise significantly increased plasma concentration of pre beta 1-HDL (20% increase, P < 0.05) and second, that the pre beta 1-HDL concentration was significantly higher in the venous compared with the arterial blood both before and after exercise in both diabetics and controls. In the combined population, formation of pre beta 1-HDL at rest was 9.9 +/- 5.2 mg/min and exercise enhanced pre beta 1-HDL formation 6.6-fold in both groups.

Analytical performance of a sandwich enzyme immunoassay for pre beta 1-HDL in stabilized plasma

We have established an immunoassay for pre beta 1-HDL (the initial acceptor of cellular cholesterol) using a monoclonal antibody, MAb55201. Because pre beta 1-HDL is unstable during storage, fresh plasma must be used for pre beta 1-HDL measurements. In this study, we describe a method of stabilizing pre beta 1-HDL, and evaluate the analytical performance of the immunoassay for pre beta 1-HDL. Fresh plasma was stored under various conditions with or without a pretreatment consisting of a 21-fold dilution into 50% (v/v) sucrose. Pre beta 1-HDL concentration was measured by immunoassay. In nonpretreated samples, pre beta 1-HDL decreased significantly from the baseline after 6 h at room temperature. Although pre beta 1-HDL was more stable at 0 degrees C than at room temperature, it increased from 30.2 +/- 8.5 (SE) to 56.5 +/- 5.5 mg/l apolipoprotein A-I (apoA-I) (P < 0.001) in hyperlipidemics, and from 18.4 +/- 1.2 to 37.9 +/- 3.3 mg/l apoA-I (P < 0.001) in normolipidemics after 5-day storage. After 30-day storage at -80 degrees C, pre beta 1-HDL increased from 29.0 +/- 4.0 to 38.0 +/- 5.7 mg/l apoA-I (P < 0.001) in hyperlipidemics, whereas it did not change in normolipidemics. In pretreated samples, pre beta 1-HDL concentration did not change significantly under any of the above conditions. Moreover, pre beta 1-HDL concentrations determined by immunoassay correlated with those determined by native two-dimensional gel electrophoresis (n = 24, r = 0.833, P < 0.05). An immunoassay using MAb55201 with pretreated plasma is useful for clinical measurement of pre beta 1-HDL.

Dynamics of reverse cholesterol transport: protection against atherosclerosis

This review considers the antiatherogenic function of high density lipoprotein (HDL) from the point of view of its dynamics within the sequential steps of reverse cholesterol transport (RCT). It is postulated that the efficiency of cholesterol flux through the RCT pathways is clinically more relevant than the HDL cholesterol concentration. The particular role of pre-beta(1)-HDL is reviewed drawing attention to the relationship between its concentration and the flux of cholesterol through the RCT system.

Bezafibrate increases prebeta 1-HDL at the expense of HDL2b in hypertriglyceridemia

Prebeta1-high density lipoprotein (prebeta1-HDL), the initial acceptor of cell-derived cholesterol, can be generated from HDL(2) by hepatic lipase. Because bezafibrate elevates lipase activity, it may increase prebeta1-HDL at the expense of HDL(2). To answer this question, we determined the apolipoprotein A-I (apoA-I) distribution in 20 hypertriglyceridemics (triglycerides>2.26 mmol/L) and 20 sex-matched normolipidemics by native 2-dimensional gel electrophoresis. At baseline, prebeta1-HDL was 70% higher in hypertriglyceridemics than in normolipidemics (123.5+/-49.9 versus 72.5+/-34.1 mg/L apoA-I, P<0.01). Prebeta1-HDL was positively correlated with triglyceride (r=0.624, P<0.0001). A 4-week bezafibrate treatment (400 mg daily) increased prebeta1-HDL by 30% (160.2+/-64.5 mg/L apoA-I, P<0.05) but decreased HDL(2b) by 31% (from 188.8+/-94.9 to 129.3+/-78.7 mg/L apoA-I, P<0.05). Hepatic lipase activity increased by 24% (P<0.005). Prebeta1-HDL was generated either from ultracentrifugally isolated HDL(2) or from plasma during incubation with triglyceride lipase. In conclusion, bezafibrate increases prebeta1-HDL at the expense of HDL(2). We speculate that such an effect might partly contribute to the antiatherogenic action of bezafibrate.

Effect of weight reduction on the distribution of apolipoprotein A-I in high-density lipoprotein subfractions in obese non-insulin-dependent diabetic subjects

High-density lipoprotein (HDL) plays an important role in the process of reverse cholesterol transport, which may become suboptimal with increasing body fatness. HDL cholesterol that is reduced in obese subjects paradoxically decreases during weight reduction. To determine how weight reduction affects HDL subclasses that are involved in reverse cholesterol transport, we studied HDL from obese diabetic subjects before and after energy restriction within background diets high in either carbohydrate or monounsaturated fatty acids (MUFAs). Body weight, blood glucose, total cholesterol, and LDL cholesterol decreased after 8 and 12 weeks of weight reduction. With the very-low-fat diet, HDL cholesterol decreased significantly at 8 weeks, but recovered to initial levels after 12 weeks as body weight began to stabilize. Plasma apolipoprotein A-I (apo A-I) decreased substantially and significantly at 8 and 12 weeks with both diets, and was reflected in the reduction of apo A-I in HDL subclasses alpha1, alpha2, pre-beta1, and pre-beta2 + pre-beta3. The calculation of the percentage distribution of apo A-I among HDL species showed that only the proportion of pre-beta1-HDL decreased, whereas alpha2-HDL increased. This led to a significant increase in the alpha1 + alpha2/pre-beta ratio, ie, the ratio of the large cholesterol "storage" or "sink" HDL to the HDL "shuttle" fraction considered to be the initial acceptor of cell cholesterol. These data suggest that despite the reduction in HDL cholesterol and apo A-I, the redistribution of apo A-I in pre-beta1-HDL and alpha-HDL observed with weight reduction appears to revert to the pattern that we have previously reported in lean as opposed to overweight subjects.

Prebeta1-high-density lipoprotein (prebeta1-HDL) concentration can change with low-density lipoprotein-cholesterol (LDL-C) concentration independent of cholesteryl ester transfer protein (CETP)

To clarify whether prebeta1-high-density lipoprotein (prebeta1-HDL) concentration changes with low-density lipoprotein-cholesterol (LDL-C) concentration independent of cholesteryl ester transfer protein (CETP), we determined prebeta1-HDL concentration by native two-dimensional gel electrophoresis in 58 subjects with normal triglyceride and HDL-cholesterol concentrations. We also measured LDL-C and CETP concentrations. In 17 subjects, a second blood sample was taken 1-6 months after the first. We found that prebeta1-HDL concentration was positively correlated with LDL-C concentration (r=0.529, P<0.0001) and with CETP mass (r=0.398, P<0.01). In 17 patients, Deltaprebeta1-HDL was positively correlated with DeltaLDL-C (r=0.635, P<0.01), but not with DeltaCETP mass (r=0.275). In conclusion, prebeta1-HDL concentration changes with LDL-C concentration independent of CETP. These results suggest that prebeta1-HDL concentration may reflect the balance between several regulatory factors, including LDL-C and CETP concentrations.