Phage-displayed recombinant single-chain antibody fragments with high affinity for cholesteryl ester transfer protein (CETP): cDNA cloning, characterization and CETP quantification

Cholesterol Efflux Capacity and Cardiovascular Disease: The Ludwigshafen Risk and Cardiovascular Health (LURIC) Study

(1) Background and Aims: Efforts to reduce coronary artery disease (CAD) by raising high-density lipoprotein (HDL) cholesterol (HDL-C) have not been uniformly successful. A more important factor than HDL-C may be cellular cholesterol efflux mediated by HDL, which has been shown to be associated with CAD. In this report, we analyzed the influence of cardiovascular biomarkers and risk factors on cholesterol efflux in a prospective observational study of patients referred to coronary angiography. (2) Methods: HDL-mediated efflux capacity was determined for 2468 participants of the Ludwigshafen Risk and Cardiovascular Health (LURIC) study who were referred to coronary angiography at baseline between 1997 and 2000. Median follow-up time was 9.9 years. Primary and secondary endpoints were cardiovascular and all-cause mortality, respectively. (3) Results: Cholesterol efflux strongly correlated with HDL-related markers including HDL cholesterol, HDL phospholipids, and apolipoproteins AI and AII, as well as HDL particle concentration, which was not seen for low density lipoprotein (LDL) markers including LDL cholesterol and apoB. Cholesterol efflux was associated negatively with C-reactive protein (CRP), fibrinogen, interleukin-6 (IL-6), and serum amyloid A. Cardiovascular mortality was higher in patients in the lowest cholesterol efflux quartile. This association was weakened, but not fully abolished, after adjustment for HDL cholesterol. (4) Conclusions: We demonstrate that cholesterol efflux was associated with HDL-composition as well as inflammatory burden in patients referred for coronary angiography, and that this inversely predicts cardiovascular mortality independently of HDL cholesterol.

Decreased cholesterol efflux capacity in patients with low cholesteryl ester transfer protein plasma levels

BACKGROUND

Cholesteryl ester transfer protein (CETP) has been considered as a possible target for treatment of cardiovascular disease. However, first clinical studies employing CETP inhibitors have failed to demonstrate clinical benefit. Additionally, we have previously shown that low endogenous plasma levels of CETP are associated with increased mortality in coronary artery disease (CAD) patients. We hypothesized that low CETP plasma levels are associated with decreased high-density lipoprotein (HDL) function.

MATERIALS AND METHODS

Serum HDL efflux capacity was measured in 154 patients of the Ludwigshafen Risk and Cardiovascular Health (LURIC) study displaying extremely low (< 0·68 μg/mL, n = 77) or high (> 2·13 μg/mL, n = 77) CETP concentrations in their plasma, respectively. The LURIC study is a prospective observational study of patients referred to coronary angiography at baseline with a median follow-up time of 7·75 years. Primary and secondary endpoints were cardiovascular and all-cause mortality, respectively.

RESULTS

High CETP patients showed a significant increase in the capacity of their plasma to mediate cholesterol efflux from cholesterol laden macrophages when compared to the efflux capacity observed in low CETP patients (+ 5·4%, P = 0·015). As shown by multiregression analysis, the impact of CETP on cholesterol efflux capacity was independent from classical risk and lifestyle factors, as well as from lipid parameters including HDL cholesterol, LDL cholesterol and triglycerides.

CONCLUSIONS

Our findings indicate that low plasma concentrations of CETP might indeed lead to impaired HDL function within the reverse cholesterol transport pointing towards an atheroprotective role of CETP at least in patients with high risk of CAD.

Cholesteryl ester transfer protein in patients with coronary heart disease

BACKGROUND

The impact of cholesteryl ester transfer protein (CETP) in the development of atherosclerosis is a matter for ongoing debate. In this study, we analyse associations of CETP with cardiovascular endpoints in a cohort of patients with stable coronary artery disease (CAD).

DESIGN

KAROLA is a prospective observational study of patients with CAD and a median follow-up of 8 years (n = 1132). CETP levels were measured using an enzyme-linked immunosorbent assay.

RESULTS

Cholesteryl ester transfer protein levels were lower in men (P = 0.0016), positively correlated to low-density lipoprotein cholesterol, and inversely correlated to triglyceride levels (P < 0.0001 and P = 0.011 respectively). There was no significant difference in mortality between patients in different CETP quartiles; the hazard ratio of lowest vs. highest quartile was 1.33 (95% confidence interval (CI): 0.77-2.30) for mortality and 1.24 (95% CI: 0.75-2.03) for secondary events. In post hoc analyses, comparing nondiabetic subjects with CETP below vs. above median, the adjusted hazard ratio for death in patients with low CETP levels was 1.84 (95% CI: 1.10-3.09).

CONCLUSION

Although statistically significant associations were found only in post hoc analyses, the effect sizes in this study were in line with previous findings in the Framingham and LURIC population. In combination, the emerging evidence challenges the concept of pharmacological CETP inhibition.

Cholesteryl ester transfer protein and mortality in patients undergoing coronary angiography: the Ludwigshafen Risk and Cardiovascular Health study

BACKGROUND

The role of cholesteryl ester transfer protein (CETP) in the development of atherosclerosis is still open to debate. In the Investigation of Lipid Level Management to Understand its Impact in Atherosclerotic Events (ILLUMINATE) trial, inhibition of CETP in patients with high cardiovascular risk was associated with increased high-density lipoprotein levels but increased risk of cardiovascular morbidity and mortality. In this report, we present a prospective observational study of patients referred to coronary angiography in which CETP was examined in relation to morbidity and mortality.

METHODS AND RESULTS

CETP concentration was determined in 3256 participants of the Ludwigshafen Risk and Cardiovascular Health (LURIC) study who were referred to coronary angiography at baseline between 1997 and 2000. Median follow-up time was 7.75 years. Primary and secondary end points were cardiovascular and all-cause mortality, respectively. CETP levels were higher in women and lower in smokers, in diabetic patients, and in patients with unstable coronary artery disease, respectively. In addition, CETP levels were correlated negatively with high-sensitivity C-reactive protein and interleukin-6. After adjustment for age, sex, medication, coronary artery disease status, cardiovascular risk factors, and diabetes mellitus, the hazard ratio for death in the lowest CETP quartile was 1.33 (1.07 to 1.65; P=0.011) compared with patients in the highest CETP quartile. Corresponding hazard ratios for death in the second and third CETP quartiles were 1.17 (0.92 to 1.48; P=0.19) and 1.10 (0.86 to 1.39; P=0.46), respectively.

CONCLUSIONS

We interpret our data to suggest that low endogenous CETP plasma levels per se are associated with increased cardiovascular and all-cause mortality, challenging the rationale of pharmacological CETP inhibition.

The Taq1B-variant in the cholesteryl ester-transfer protein gene and the risk of metabolic syndrome

The metabolic syndrome is associated with low high-density lipoprotein-cholesterol (HDL-C) and decreased low-density lipoprotein (LDL) particle size. The Taq1B-polymorphism in the cholesteryl ester-transfer protein (CETP)-gene influences HDL-C, CETP concentration, and LDL-size. We investigated the effect of the Taq1B-polymorphism on the risk of the metabolic syndrome in 1,503 participants (973 men, 530 women) of the Salzburg Atherosclerosis Prevention program in subjects at High Individual Risk study. CETP concentration was determined in a subgroup (n = 486) by an enzyme-linked immunosorbent assay. Prevalence of the metabolic syndrome was 16.7% (18.5% in men, 13.5% in women). The Taq1B-polymorphism influenced significantly CETP concentrations, HDL-C levels, and LDL-size (P < 0.001 for all). The relative risk of the metabolic syndrome was reduced by 32% (odds ratio (OR) 0.68 (95% CI: 0.51-0.89), P = 0.005) in carriers of the B2 variant. This risk reduction persisted after adjustment for age and sex (OR 0.69 (0.53-0.92), P = 0.01) and after further adjustment for body mass index, waist-to-hip ratio, blood pressure, insulin resistance (IR), HDL-C, and triglycerides (TGs) (OR 0.43 (0.26-0.72), P = 0.001). Furthermore, the risk reduction was more pronounced in men than in women. We conclude that CETP plays an important role in the metabolic syndrome, possibly involving novel functions of CETP.

Plasma cholesteryl ester transfer protein concentrations predict cardiovascular events in patients with coronary artery disease treated with pravastatin

OBJECTIVE

The B1B1 variant of the cholesteryl ester transfer protein (CETP) TaqIB polymorphism and high plasma CETP concentrations are associated with favourable angiographic outcomes in pravastatin-treated patients suffering from coronary artery disease (CAD). The purpose of the present study was to test whether CETP TaqIB genotypes and/or plasma CETP concentrations at baseline also predict clinical end-points in patients with CAD.

DESIGN

Prospective longitudinal observational study.

SETTING

Primary care doctors (n=88) and hospitals (n=7) in Austria.

SUBJECTS

A total of 1620 men and women with preexisting CAD were recruited and plasma lipids were determined at study entry. 1389 hypercholesterolaemic patients were included and 1002 patients completed the follow-up.

INTERVENTIONS

In all patients treatment with pravastatin was started and patients were followed up for 2 years.

MAIN OUTCOME MEASURES

Cardiovascular events.

RESULTS

One hundred patients suffered at least one cardiovascular event. We observed significantly more events in patients within the lowest compared with the highest quartile of plasma CETP concentrations (odds ratio 3.20, CI95 1.65-6.23; P=0.001, adjusted for known risk factors of CAD). No significantly different numbers of cardiovascular events were found between CETP TaqIB genotypes.

CONCLUSIONS

Plasma CETP concentrations, but not CETP TaqIB genotypes, predict cardiovascular events in patients with CAD treated with pravastatin. Despite higher LDL cholesterol concentrations, high plasma CETP concentrations at baseline are associated with fewer cardiovascular events compared with low plasma CETP concentrations in CAD patients treated with pravastatin.

Cholesteryl ester transfer protein in metabolic syndrome

OBJECTIVE

Low high-density lipoprotein cholesterol (HDL-C), hypertriglyceridemia, and small dense-low density lipoprotein (LDL) are key components of metabolic syndrome (MS). Cholesteryl ester transfer protein (CETP) mediates the transfer of triglycerides (TGs) from TG-rich lipoproteins to HDL and LDL particles in exchange for cholesteryl esters, leading to low HDL-C and small dense-LDL. The aim of this study was to investigate the role of CETP in subjects with MS.

RESEARCH METHODS AND PROCEDURES

In a cross-sectional cohort of 234 middle-aged men and 252 women randomly selected from the Salzburg Atherosclerosis Prevention Program in Subjects at High Individual Risk (SAPHIR) study, MS was diagnosed according to the National Cholesterol Education Program guidelines. CETP mass was determined by enzyme-linked immunosorbent assay and LDL size-by-gradient polyacrylamide gel electrophoresis.

RESULTS

Men and women with MS had lower HDL-C (45 +/- 7 vs. 58 +/- 13 and 48 +/- 10 vs. 71 +/- 14 mg/dL for men and women, respectively; p < 0.001 for all) and higher TG levels (222 +/- 71 vs. 98 +/- 54 and 167 +/- 67 vs. 90 +/- 35 mg/dL for men and women, respectively; p < 0.001 for all) than healthy subjects. LDL size was lower in subjects with MS (256 +/- 11 A vs. 267 +/- 11 A and 262 +/- 10 A vs. 273 +/- 8 A for men and women, respectively; p < 0.001 for all). CETP mass was higher in men with MS (1.87 +/- 0.78 vs. 1.40 +/- 0.65 mug/mL; p < 0.001) but not in women (1.74 +/- 0.79 vs. 1.62 +/- 0.62 mug/mL). CETP mass correlated inversely with LDL size in both men and women (r = -0.19, p < 0.01 and r = -0.13, p < 0.05 in men and women, respectively).

DISCUSSION

MS is associated with increased CETP mass in men. Increased CETP mass may be responsible for reduced HDL-C and reduced LDL particle diameter in MS.

Survey of the year 2004 commercial optical biosensor literature

The year 2004 represents a milestone for the biosensor research community: in this year, over 1000 articles were published describing experiments performed using commercially available systems. The 1038 papers we found represent an approximately 10% increase over the past year and demonstrate that the implementation of biosensors continues to expand at a healthy pace. We evaluated the data presented in each paper and compiled a 'top 10' list. These 10 articles, which we recommend every biosensor user reads, describe well-performed kinetic, equilibrium and qualitative/screening studies, provide comparisons between binding parameters obtained from different biosensor users, as well as from biosensor- and solution-based interaction analyses, and summarize the cutting-edge applications of the technology. We also re-iterate some of the experimental pitfalls that lead to sub-optimal data and over-interpreted results. We are hopeful that the biosensor community, by applying the hints we outline, will obtain data on a par with that presented in the 10 spotlighted articles. This will ensure that the scientific community at large can be confident in the data we report from optical biosensors.