PCSK9 and resistin at the crossroads of the atherogenic dyslipidemia

The atherogenic dyslipidemia is a pathophysiological lipid triad, composed of high triglycerides and low-density lipoprotein and low high-density lipoprotein. The dyslipidemia is highly prevalent in individuals who are obese, insulin resistant and those with Type 2 diabetes and is the major contributing factor to the high atherosclerotic cardiovascular disease risk in these subjects. The primary initiating event in atherogenic dyslipidemia development is the hepatic overproduction of very-low-density lipoprotein (VLDL). The intracellular and extracellular protein triggers of hepatic VLDL production were not known until the recent identification of the causal roles of PCSK9 and resistin. Both PCSK9 and resistin act in large part by targeting and reducing the hepatic degradation of VLDL apoB through distinctly different mechanisms. In the current review, we discuss both the individual roles and the interaction of these proteins in driving atherogenic dyslipidemia, and thus, atherosclerotic cardiovascular disease progression in humans. We further explore the important therapeutic implications of these findings.

Common variants associated with plasma triglycerides and risk for coronary artery disease

Triglycerides are transported in plasma by specific triglyceride-rich lipoproteins; in epidemiologic studies, increased triglyceride levels correlate with higher risk for coronary artery disease (CAD). However, it is unclear whether this association reflects causal processes. We used 185 common variants recently mapped for plasma lipids (P<5×10⁻⁸ for each) to examine the role of triglycerides on risk for CAD. First, we highlight loci associated with both low-density lipoprotein cholesterol (LDL-C) and triglycerides, and show that the direction and magnitude of both are factors in determining CAD risk. Second, we consider loci with only a strong magnitude of association with triglycerides and show that these loci are also associated with CAD. Finally, in a model accounting for effects on LDL-C and/or high-density lipoprotein cholesterol, a polymorphism's strength of effect on triglycerides is correlated with the magnitude of its effect on CAD risk. These results suggest that triglyceride-rich lipoproteins causally influence risk for CAD.

Non-HDL cholesterol vs. apo B for risk of coronary heart disease in healthy individuals: the EPIC-Norfolk prospective population study

BACKGROUND

There is an ongoing debate about the performance of non-high-density lipoprotein cholesterol (non-HDL-C) compared with apolipoprotein B (apo B) in the prediction of coronary heart disease (CHD) risk. Therefore, we compared the associations between non-HDL-C and apo B in regard to CHD among apparently healthy Western European individuals.

DESIGN

In the European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk prospective population study, 25,639 men and women aged 45-79 years were followed for 11·4 ± 2·8 years. Those with diabetes or prevalent CHD at baseline were excluded. A total of 2066 (12·1%) participants developed CHD during 195 692 person-years follow-up.

RESULTS

The multivariable-adjusted hazard ratio [HR] of future CHD per one standard deviation increase was 1·22 [95% confidence interval (CI): 1·17-1·27] for LDL-C, 1·26 (95% CI 1·20-1·31) for non-HDL-C and 1·19 (95% CI 1·14-1·24) for apo B, respectively. The multivariable-adjusted HR of future CHD in the highest quartile LDL-C was 1·67 (95% CI: 1·47-1·91). For non-HDL-C and apo B, these respective HRs were 1·87 (95% CI: 1·62-2·15) and 1·56 (95% CI: 1·36-1·78). Kaplan-Meier survival analyses showed that there was incremental and comparable increase in risk of CHD with increasing quartiles of both non-HDL-C and apo B.

CONCLUSIONS

In this prospective study, non-HDL-C and apo B were comparable in their ability to predict risk of future CHD.

C-reactive protein, fatal and nonfatal coronary artery disease, stroke, and peripheral artery disease in the prospective EPIC-Norfolk cohort study

OBJECTIVE

Circulating levels of C-reactive protein (CRP) are associated with an increased risk of coronary artery disease (CAD), stroke, and peripheral artery disease (PAD). Observational and experimental evidence suggest that CRP might differentially predict fatal and nonfatal cardiovascular events. Here, we sought to determine the predictive value of CRP for fatal and nonfatal CAD, stroke, or PAD.

APPROACH AND RESULTS

CRP levels were measured in 18 450 apparently healthy participants in the European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk cohort. Cox proportional hazards models were used to quantify the association between CRP levels and fatal and nonfatal CAD events, strokes, and PAD events. Bootstrapping was applied to test for significant differences between the risk of fatal and nonfatal events. During 208 485 person-years at risk, 2915 CAD events, 361 strokes, and 657 PAD events occurred. CRP was associated with fatal and nonfatal CAD events and nonfatal PAD events. When adding CRP to predictive risk models for fatal and nonfatal events corrected for known cardiovascular risk factors, the net reclassification index was 2.1% for fatal and 1.9% for nonfatal events. Multivariate adjusted hazard ratios for fatal CAD events (hazard ratio, 1.36; 95% confidence interval, 1.27-1.46) differed significantly (mean difference, 13%; 95% confidence interval, 5.1%-21.9%; P<0.001) from the multivariate adjusted hazard ratio for nonfatal CAD events (hazard ratio, 1.21; 95% confidence interval, 1.15-1.26).

CONCLUSIONS

In the EPIC-Norfolk cohort, CRP was associated with fatal and nonfatal CAD events, as well as nonfatal PAD events. Adding CRP to risk stratification models resulted in a small improvement in classification for both fatal and nonfatal events. Importantly, CRP was significantly more strongly associated with fatal CAD events than with nonfatal CAD events.

Effect of aliskiren on progression of coronary disease in patients with prehypertension: the AQUARIUS randomized clinical trial

IMPORTANCE

Blood pressure reduction and renin-angiotensin-aldosterone system inhibition are targets for treatment of atherosclerosis. The effect of renin inhibition on coronary disease progression has not been investigated.

OBJECTIVE

To determine the effects of renin inhibition with aliskiren on progression of coronary atherosclerosis.

DESIGN, SETTING, AND PARTICIPANTS

A double-blind, randomized, multicenter trial (Aliskiren Quantitative Atherosclerosis Regression Intravascular Ultrasound Study) comparing aliskiren with placebo in 613 participants with coronary artery disease, systolic blood pressure between 125 and 139 mm Hg (prehypertension range), and 2 additional cardiovascular risk factors conducted at 103 academic and community hospitals in Europe, Australia, and North and South America (enrollment from March 2009 to February 2011; end of follow-up: January 31, 2013).

INTERVENTIONS

Participants underwent coronary intravascular ultrasound (IVUS) imaging and were randomized to receive 300 mg of aliskiren (n = 305) or placebo (n = 308) taken orally daily for 104 weeks. Disease progression was measured by repeat IVUS examination after at least 72 weeks of treatment.

MAIN OUTCOMES AND MEASURES

The primary efficacy parameter was the change in percent atheroma volume (PAV) from baseline to study completion. Secondary efficacy parameters included the change in normalized total atheroma volume (TAV) and the percentage of participants with atheroma regression. Safety and tolerability were also assessed.

RESULTS

Evaluable imaging data were available at baseline and follow-up for 458 participants (74.7%). The primary IVUS efficacy parameter, PAV, did not differ between participants treated with aliskiren (-0.33%; 95% CI, -0.68% to 0.02%) and placebo (0.11%; 95% CI, -0.24% to 0.45%) (between-group difference, -0.43% [95% CI, -0.92% to 0.05%]; P = .08). The secondary IVUS efficacy parameter, TAV, did not differ between participants treated with aliskiren (-4.1 mm3; 95% CI, -6.27 to -1.94 mm3) and placebo (-2.1 mm3; 95% CI, -4.21 to 0.07 mm3) (between-group difference, -2.04 mm3 [95% CI, -5.03 to 0.95 mm3]; P = .18). There were no significant differences in the proportion of participants who demonstrated regression of PAV (56.9% vs 48.9%; P = .08) and TAV (64.4% vs 57.5%; P = .13) in the aliskiren and placebo groups, respectively.

CONCLUSIONS AND RELEVANCE

Among participants with prehypertension and coronary artery disease, the use of aliskiren compared with placebo did not result in improvement or slowing of progression of coronary atherosclerosis. These findings do not support the use of aliskiren for regression or prevention of progression of coronary atherosclerosis.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00853827.

Levels and changes of HDL cholesterol and apolipoprotein A-I in relation to risk of cardiovascular events among statin-treated patients: a meta-analysis

BACKGROUND

It is unclear whether levels of high-density lipoprotein cholesterol (HDL-C) or apolipoprotein A-I (apoA-I) remain inversely associated with cardiovascular risk among patients who achieve very low levels of low-density lipoprotein cholesterol on statin therapy. It is also unknown whether a rise in HDL-C or apoA-I after initiation of statin therapy is associated with a reduced cardiovascular risk.

METHODS AND RESULTS

We performed a meta-analysis of 8 statin trials in which lipids and apolipoproteins were determined in all study participants at baseline and at 1-year follow-up. Individual patient data were obtained for 38,153 trial participants allocated to statin therapy, of whom 5387 suffered a major cardiovascular event. HDL-C levels were associated with a reduced risk of major cardiovascular events (adjusted hazard ratio [HR], 0.83; 95% confidence interval [CI], 0.81-0.86 per 1 standard deviation increment), as were apoA-I levels (HR, 0.79; 95% CI, 0.72-0.82). This association was also observed among patients achieving on-statin low-density lipoprotein cholesterol levels <50 mg/dL. An increase of HDL-C was not associated with reduced cardiovascular risk (HR, 0.98; 95% CI, 0.94-1.01 per 1 standard deviation increment), whereas a rise in apoA-I was (HR, 0.93; 95% CI, 0.90-0.97).

CONCLUSIONS

Among patients treated with statin therapy, HDL-C and apoA-I levels were strongly associated with a reduced cardiovascular risk, even among those achieving very low low-density lipoprotein cholesterol. An apoA-I increase was associated with a reduced risk of major cardiovascular events, whereas for HDL-C this was not the case. These findings suggest that therapies that increase apoA-I concentration require further exploration with regard to cardiovascular risk reduction.

Two novel mutations in apolipoprotein C3 underlie atheroprotective lipid profiles in families

Apolipoprotein C3 (APOC3) mutations carriers typically display high plasma high-density lipoprotein cholesterol (HDL-C) and low triglycerides (TGs). We set out to investigate the prevalence and clinical consequences of APOC3 mutations in individuals with hyperalphalipoproteinemia. Two novel mutations (c.-13-2A>G and c.55+1G>A) and one known mutation (c.127G>A;p.Ala43Thr) were found. Lipid profiles and apoCIII isoform distributions were measured. c.55+1G>A mutation carriers displayed higher HDL-C percentiles (35.6 ± 35.8 vs 99.0 ± 0, p = 0.002) and lower TGs (0.51 (0.37-0.61) vs 1.42 (1.12-1.81) mmol/l, p = 0.007) and apoCIII levels (4.24 ± 1.57 vs 7.33 ± 3.61 mg/dl, p = 0.18). c.-13-2A>G mutation carriers did not display significantly different HDL-C levels (84.0 ± 30.0 vs 63.7 ± 45.7, p = 0.50), a trend towards lower TGs [0.71 (0.54 to 0.78) vs 0.85 (0.85 to -) mmol/l, p = 0.06] and significantly lower apoCIII levels (3.09 ± 1.08 vs 11.45 ± 1.06 mg/dl, p = 0.003). p.Ala43Thr mutation carriers displayed a trend towards higher HDL-C percentiles (91.2 ± 31.8 vs 41.0 ± 29.7 mmol/l, p = 0.06) and significantly lower TGs [0.58 (0.36-0.63) vs 0.95 (0.71-1.20) mmol/l, p = 0.02] and apoCIII levels (4.92 ± 2.33 vs 6.60 ± 1.60, p = 0.25). Heterozygosity for APOC3 mutations results in high HDL-C and low TGs and apoCIII levels. This favourable lipid profile in patients with genetically low apoCIII levels holds promise for current studies investigating the potential of apoCIII inhibition as a novel therapeutic in cardiovascular disease prevention.

In vivo tissue cholesterol efflux is reduced in carriers of a mutation in APOA1

Atheroprotection by high density lipoprotein (HDL) is considered to be mediated through reverse cholesterol transport (RCT) from peripheral tissues. We investigated in vivo cholesterol fluxes through the RCT pathway in patients with low plasma high density lipoprotein cholesterol (HDL-c) due to mutations in APOA1. Seven carriers of the L202P mutation in APOA1 (mean HDL-c: 20 ± 19 mg/dl) and seven unaffected controls (mean HDL-c: 54 ± 11 mg/dl, P < 0.0001) received a 20 h infusion of (13)C2-cholesterol ((13)C-C). Enrichment of plasma and erythrocyte free cholesterol and plasma cholesterol esters was measured. With a three-compartment SAAM-II model, tissue cholesterol efflux (TCE) was calculated. TCE was reduced by 19% in carriers (4.6 ± 0.8 mg/kg/h versus 5.7 ± 0.7 mg/kg/h in controls, P = 0.02). Fecal (13)C recovery and sterol excretion 7 days postinfusion did not differ significantly between carriers and controls: 21.3 ± 20% versus 13.3 ± 6.3% (P = 0.33), and 2,015 ± 1,431 mg/day versus 1456 ± 404 mg/day (P = 0.43), respectively. TCE is reduced in carriers of mutations in APOA1, suggesting that HDL contributes to efflux of tissue cholesterol in humans. The residual TCE and unaffected fecal sterol excretion in our severely affected carriers suggest, however, that non-HDL pathways contribute to RCT significantly.

Identification of a loss-of-function inducible degrader of the low-density lipoprotein receptor variant in individuals with low circulating low-density lipoprotein

AIMS

Recent genome-wide association studies suggest that IDOL (also known as MYLIP) contributes to variation in circulating levels of low-density lipoprotein cholesterol (LDL-C). IDOL, an E3-ubiquitin ligase, is a recently identified post-transcriptional regulator of LDLR abundance. Briefly, IDOL promotes degradation of the LDLR thereby limiting LDL uptake. Yet the exact role of IDOL in human lipoprotein metabolism is unclear. Therefore, this study aimed at identifying and functionally characterizing IDOL variants in the Dutch population and to assess their contribution to circulating levels of LDL-C.

METHODS AND RESULTS

We sequenced the IDOL coding region in 677 individuals with LDL-C above the 95th percentile adjusted for age and gender (high-LDL-C cohort) in which no mutations in the LDLR, APOB, and PCSK9 could be identified. In addition, IDOL was sequenced in 560 individuals with baseline LDL-C levels below the 20th percentile adjusted for age and gender (low-LDL-C cohort). We identified a total of 14 IDOL variants (5 synonymous, 8 non-synonymous, and 1 non-sense). Functional characterization of these variants demonstrated that the p.Arg266X variant represents a complete loss of IDOL function unable to promote ubiquitylation and subsequent degradation of the LDLR. Consistent with loss of IDOL function, this variant was identified in individuals with low circulating LDL-C.

CONCLUSION

Our results support the notion that IDOL contributes to variation in circulating levels of LDL-C. Strategies to inhibit IDOL activity may therefore provide a novel therapeutic venue to treating dyslipidaemia.

High-dose statin monotherapy versus low-dose statin/ezetimibe combination on fasting and postprandial lipids and endothelial function in obese patients with the metabolic syndrome: The PANACEA study

BACKGROUND

Low-dose statin therapy in combination with ezetimibe, an inhibitor of intestinal cholesterol absorption, lowers plasma LDL-cholesterol levels to a similar degree as high-dose statin monotherapy. This study assessed whether similar LDL-cholesterol lowering with simvastatin/ezetimibe combination therapy improves fasting and postprandial arterial endothelial function compared to high-dose statin therapy alone.

METHODS

Multicenter, double-blind, crossover trial in 100 abdominally obese patients with the metabolic syndrome, randomized to 6 weeks' treatment with simvastatin 80 mg or simvastatin/ezetimibe 10/10 mg. Flow mediated dilatation (FMD) and peripheral arterial tonometry (EndoPAT) as well as plasma lipids were measured in the fasting state and after an oral lipid load at baseline and after both treatments.

RESULTS

Fasting LDL-cholesterol levels (3.57 mmol/L at baseline) were reduced to 1.79 mmol/L following treatment with simvastatin 80 mg and 1.81 mmol/L with simvastatin/ezetimibe 10/10 mg, respectively. Plasma lipids were similar at 4 h after an oral lipid load following both treatments for 6 weeks. Fasting endothelial function was also similar with both treatments when assessed by FMD (adjusted mean ± SE: 4.35 ± 0.19 vs. 4.43 ± 0.18; P = 0.777) and EndoPAT (2.12 ± 0.05 vs 2.20 ± 0.05; P = 0.304). After an oral fat load, changes in endothelial function were also comparable for both treatments as assessed by FMD (-0.34 ± 0.21 vs. -0.43 ± 0.20; P = 0.766) and EndoPAT (0.00 ± 0.07 vs. -0.04 ± 0.08; P = 0.712).

CONCLUSION

Treatment with simvastatin/ezetimibe 10/10 mg induced no difference in endothelial function in the fasting and postprandial state compared to simvastatin 80 mg while attaining similar LDL-c levels in obese patients with metabolic syndrome.

Cardiovascular event reduction versus new-onset diabetes during atorvastatin therapy: effect of baseline risk factors for diabetes

OBJECTIVES

The purpose of this study was to compare the incidence of new-onset diabetes (NOD) with cardiovascular (CV) event reduction at different levels of NOD risk.

BACKGROUND

Statins reduce the number of CV events but increase the incidence of NOD. We previously reported that 4 factors independently predicted NOD: fasting blood glucose >100 mg/dl, fasting triglycerides >150 mg/dl, body mass index >30 kg/m(2), and history of hypertension.

METHODS

We compared NOD incidence with CV event reduction among 15,056 patients with coronary disease but without diabetes at baseline in the TNT (Treating to New Targets) (n = 7,595) and IDEAL (Incremental Decrease in Endpoints Through Aggressive Lipid Lowering) (n = 7,461) trials. CV events included coronary heart disease death, myocardial infarction, stroke, and resuscitated cardiac arrest.

RESULTS

Among 8,825 patients with 0 to 1 of the aforementioned NOD risk factors at baseline, NOD developed in 142 of 4,407 patients in the atorvastatin 80 mg group and in 148 of 4,418 in the atorvastatin 10 mg and simvastatin 20 to 40 mg groups (3.22% vs. 3.35%; hazard ratio [HR]: 0.97; 95% confidence intervals [CI]: 0.77 to 1.22). Among the remaining 6,231 patients with 2 to 4 NOD risk factors, NOD developed in 448 of 3,128 in the atorvastatin 80 mg group and in 368 of 3,103 in the lower-dose groups (14.3% vs. 11.9%; HR: 1.24; 95% CI: 1.08 to 1.42; p = 0.0027). The number of CV events was significantly reduced with atorvastatin 80 mg in both NOD risk groups.

CONCLUSIONS

Compared with lower-dose statin therapy, atorvastatin 80 mg/day did not increase the incidence of NOD in patients with 0 to 1 NOD risk factors but did, by 24%, among patients with 2 to 4 NOD risk factors. The number of CV events was significantly reduced with atorvastatin 80 mg in both NOD risk groups.

ABCA1 mutation carriers with low high-density lipoprotein cholesterol are characterized by a larger atherosclerotic burden

AIMS

Low HDL-C is a potent risk factor for cardiovascular disease (CVD). Yet, mutations in ABCA1, a major determinant of circulating HDL-C levels, were previously not associated with CVD risk in cohort studies. To study the consequences of low plasma levels of high-density lipoprotein cholesterol (HDL-C) due to ATP-binding cassette transporter A1 (ABCA1) dysfunction for atherosclerotic vascular disease in the carotid arteries.

METHODS AND RESULTS

We performed 3.0 Tesla magnetic resonance imaging (MRI) measurements of the carotid arteries in 36 carriers of high impact functional ABCA1 mutations and 36 normolipidemic controls. Carriers presented with 42% lower HDL-C levels (P < 0.001), a larger mean wall area (18.6 ± 6.0 vs. 15.8 ± 4.3 mm(2); P = 0.02), a larger mean wall thickness (0.82 ± 0.21 vs. 0.70 ± 0.14 mm; P = 0.005), and a higher normalized wall index (0.37 ± 0.06 vs. 0.33 ± 0.04; P = 0.005) compared with controls, retaining significance after adjustment for smoking, alcohol consumption, systolic blood pressure, diabetes, body mass index, history of CVD, LDL-C, and statin use (P = 0.002).

CONCLUSION

Carriers of loss of function ABCA1 mutations display a larger atherosclerotic burden compared with age and sex-matched controls, implying a higher risk for CVD. Further studies are needed to elucidate the full function of ABCA1 in the protection against atherosclerosis. These data support the development of strategies to up-regulate ABCA1 in patients with established CVD.

Lipid oxidation in carriers of lecithin:cholesterol acyltransferase gene mutations

OBJECTIVE

Lecithin:cholesterol acyltransferase (LCAT) has been shown to play a role in the depletion of lipid oxidation products, but this has so far not been studied in humans. In this study, we investigated processes and parameters relevant to lipid oxidation in carriers of functional LCAT mutations.

METHODS AND RESULTS

In 4 carriers of 2 mutant LCAT alleles, 63 heterozygotes, and 63 family controls, we measured activities of LCAT, paraoxonase 1, and platelet-activating factor-acetylhydrolase; levels of lysophosphatidylcholine molecular species, arachidonic and linoleic acids, and their oxidized derivatives; immunodetectable oxidized phospholipids on apolipoprotein (apo) B-containing and apo(a)-containing lipoproteins; IgM and IgG autoantibodies to malondialdehyde-low-density lipoprotein and IgG and IgM apoB-immune complexes; and the antioxidant capacity of high-density lipoprotein (HDL). In individuals with LCAT mutations, plasma LCAT activity, HDL cholesterol, apoA-I, arachidonic acid, and its oxidized derivatives, oxidized phospholipids on apo(a)-containing lipoproteins, HDL-associated platelet-activating factor-acetylhydrolase activity, and the antioxidative capacity of HDL were gene-dose-dependently decreased. Oxidized phospholipids on apoB-containing lipoproteins was increased in heterozygotes (17%; P<0.001) but not in carriers of 2 defective LCAT alleles.

CONCLUSIONS

Carriers of LCAT mutations present with significant reductions in LCAT activity, HDL cholesterol, apoA-I, platelet-activating factor-acetylhydrolase activity, and antioxidative potential of HDL, but this is not associated with parameters of increased lipid peroxidation; we did not observe significant changes in the oxidation products of arachidonic acid and linoleic acid, immunoreactive oxidized phospholipids on apo(a)-containing lipoproteins, and IgM and IgG autoantibodies against malondialdehyde-low-density lipoprotein. These data indicate that plasma LCAT activity, HDL-associated platelet-activating factor-acetylhydrolase activity, and HDL cholesterol may not influence the levels of plasma lipid oxidation products.

Relationship between atorvastatin dose and the harm caused by torcetrapib

Development of the cholesteryl ester transfer protein (CETP) inhibitor, torcetrapib, was halted after the ILLUMINATE trial revealed an increase in both all-cause mortality (ACM) and major cardiovascular events (MCVEs) associated with its use. We now report that the harm caused by torcetrapib was confined to those in the 10 mg atorvastatin subgroup for both ACM [hazard ratio (HR) = 2.68, 95% CI (1.58, 4.54), P < 0.0001] and MCVEs [HR = 1.41, 95% CI (1.14, 1.74), P = 0.002], with no evidence of harm when torcetrapib was coadministered with higher doses of atorvastatin. In the atorvastatin 10 mg subgroup, age, prior heart failure and stroke were significantly associated with ACM, independent of torcetrapib treatment, whereas low apoA-I, smoking, hypertension, heart failure, myocardial infarction, and stroke were independently associated with MCVEs. After adjusting for these factors, the HR associated with torcetrapib treatment in the 10 mg atorvastatin subgroup remained elevated for both ACM [HR = 2.67, 95% CI (1.57, 4.54), P < 0.001] and MCVE [HR = 1.36, 95% CI (1.10, 1.69), P = 0.005]. Thus, the harm caused by torcetrapib was confined to individuals taking atorvastatin 10 mg. The harm could not be explained by torcetrapib-induced changes in lipid levels, blood pressure, or electrolytes. It is conceivable that higher doses of atorvastatin protected against the harm caused by torcetrapib.

Segregation of LIPG, CETP, and GALNT2 mutations in Caucasian families with extremely high HDL cholesterol

To date, few mutations are described to underlie highly-elevated HDLc levels in families. Here we sequenced the coding regions and adjacent sequence of the LIPG, CETP, and GALNT2 genes in 171 unrelated Dutch Caucasian probands with HDLc≥90th percentile and analyzed segregation of mutations with lipid phenotypes in family members. In these probands, mutations were most frequent in LIPG (12.9%) followed by GALNT2 (2.3%) and CETP (0.6%). A total of 6 of 10 mutations in these three genes were novel (60.0%), and mutations segregated with elevated HDLc in families. Interestingly, the LIPG mutations N396S and R476W, which usually result in elevated HDLc, were unexpectedly found in 6 probands with low HDLc (i.e., ≤10th percentile). However, 5 of these probands also carried mutations in ABCA1, LCAT, or LPL. Finally, no CETP and GALNT2 mutations were found in 136 unrelated probands with low HDLc. Taken together, we show that rare coding and splicing mutations in LIPG, CETP, and GALNT2 are enriched in persons with hyperalphalipoproteinemia and segregate with elevated HDLc in families. Moreover, LIPG mutations do not overcome low HDLc in individuals with ABCA1 and possibly LCAT and LPL mutations, indicating that LIPG affects HDLc levels downstream of these proteins.

Mutations in LPL, APOC2, APOA5, GPIHBP1 and LMF1 in patients with severe hypertriglyceridaemia

OBJECTIVES

The severe forms of hypertriglyceridaemia (HTG) are caused by mutations in genes that lead to the loss of function of lipoprotein lipase (LPL). In most patients with severe HTG (TG > 10 mmol L(-1) ), it is a challenge to define the underlying cause. We investigated the molecular basis of severe HTG in patients referred to the Lipid Clinic at the Academic Medical Center Amsterdam.

METHODS

The coding regions of LPL, APOC2, APOA5 and two novel genes, lipase maturation factor 1 (LMF1) and GPI-anchored high-density lipoprotein (HDL)-binding protein 1 (GPIHBP1), were sequenced in 86 patients with type 1 and type 5 HTG and 327 controls.

RESULTS

In 46 patients (54%), rare DNA sequence variants were identified, comprising variants in LPL (n = 19), APOC2 (n = 1), APOA5 (n = 2), GPIHBP1 (n = 3) and LMF1 (n = 8). In 22 patients (26%), only common variants in LPL (p.Asp36Asn, p.Asn318Ser and p.Ser474Ter) and APOA5 (p.Ser19Trp) could be identified, whereas no mutations were found in 18 patients (21%). In vitro validation revealed that the mutations in LMF1 were not associated with compromised LPL function. Consistent with this, five of the eight LMF1 variants were also found in controls and therefore cannot account for the observed phenotype.

CONCLUSIONS

The prevalence of mutations in LPL was 34% and mostly restricted to patients with type 1 HTG. Mutations in GPIHBP1 (n = 3), APOC2 (n = 1) and APOA5 (n = 2) were rare but the associated clinical phenotype was severe. Routine sequencing of candidate genes in severe HTG has improved our understanding of the molecular basis of this phenotype associated with acute pancreatitis and may help to guide future individualized therapeutic strategies.

The role of non-HDL cholesterol in risk stratification for coronary artery disease

Despite aggressive lipid-lowering therapy, patients continue to be at significant risk of coronary heart disease (CHD). Assessment of non-high-density lipoprotein cholesterol (non-HDL-C) provides a measure of cholesterol contained in all atherogenic particles. In the third Adult Treatment Panel (ATP III) guidelines of the US National Cholesterol Education Program, non-HDL-C was introduced as a secondary target of therapy in persons with triglycerides ≥200 mg/dL. A recent meta-analysis of the relationship between non-HDL-C reduction and CHD risk showed non-HDL-C as an important target of therapy for CHD prevention. Most lipid-modifying drugs used as monotherapy have a 1:1 relationship between percent non-HDL-C lowering and percent CHD reduction. In the EPIC-Norfolk prospective population study, 21,448 participants without diabetes or CHD between 45 and 79 years of age were followed for 11.0 years. Participants with high non-HDL-C levels were at increased CHD risk independently of their LDL-C levels. Also, compared to apolipoprotein B, non-HDL-C appears to be a better choice given the fact that no additional tests or costs are needed and established cut points are already available. Future guidelines should emphasize the importance of non-HDL-C for guiding cardiovascular prevention strategies with an increased need to have non-HDL-C reported on routine lipid panels.

The PCSK9 decade

PCSK9 proprotein convertase subtilisin/kexin type (PCSK9) is a crucial protein in LDL cholesterol (LDL-C) metabolism by virtue of its pivotal role in the degradation of the LDL receptor. In recent years, both in vitro and in vivo studies have greatly supplemented our understanding of the (patho)physiological role of PCSK9 in human biology. In the current review, we summarize studies published or in print before May 2012 concerning the physiological role of PCSK9 in cholesterol metabolism. Moreover, we briefly describe the clinical phenotypes encountered in carriers of mutations in the gene encoding PCSK9. As PCSK9 has emerged as a novel target for LDL-C lowering therapy, methods to inhibit PCSK9 will also be reviewed. Initial data from investigations of PCSK9 inhibition in humans are promising and indicate that PCSK9 inhibition may be a viable new therapeutic option for the treatment of dyslipidemia and associated cardiovascular diseases.

Follow-up of children diagnosed with familial hypercholesterolemia in a national genetic screening program

OBJECTIVE

To assess the follow-up of children diagnosed as having familial hypercholesterolemia (FH) in the nationwide DNA-based cascade screening program (the Netherlands).

STUDY DESIGN

Questionnaires covering topics such as demographics, family history, physician consultation, and treatment were sent to parents of patients with FH (age 0-18 years), 18 months after diagnosis.

RESULTS

We retrieved 207 questionnaires of patients aged 10.9 ± 4.2 years (mean ± SD) at diagnosis; 48% were boys, and the mean low-density lipoprotein cholesterol (LDL-C) level at diagnosis was 167 ± 51 mg/dL. Of these patients, 164 (79%) consulted a physician: a general practitioner (35%), lipid-clinic specialist (27%), pediatrician (21%), internist (11%), or another physician (6%). LDL-C level at diagnosis and a positive family history for cardiovascular disease were independent predictors for physician consultation. Of the patients who visited a physician, 62% reported to have received lifestyle advice, and 43 (26%) were prescribed statin treatment. Independent predictors for medication use were age, LDL-C level, and educational level of parents.

CONCLUSION

The follow-up of children with FH after diagnosis established through cascade screening is inadequate. Better education of patients, parents, and physicians, with a structured follow-up after screening, should improve control of LDL-C levels and hence cardiovascular risk in children with FH.

Inhibition of secretory phospholipase A(2) in patients with acute coronary syndromes: rationale and design of the vascular inflammation suppression to treat acute coronary syndrome for 16 weeks (VISTA-16) trial

BACKGROUND

The action of secretory phospholipase A(2) (sPLA(2)) on lipoproteins may render them more susceptible to oxidation, thereby promoting vascular inflammation and increasing cardiovascular risk. Patients with acute coronary syndrome face a high risk of early, recurrent cardiovascular events that is associated with biomarkers of inflammation, including sPLA(2). The Vascular Inflammation Suppression to Treat Acute Coronary Syndrome for 16 Weeks (VISTA-16, NCT01130246) tests the hypothesis that varespladib methyl, an inhibitor of several sPLA(2) isoforms with a causal role in atherosclerosis, reduces cardiovascular risk among patients with acute coronary syndromes.

METHODS

Up to 6,500 patients with acute coronary syndrome will be randomized to receive treatment with varespladib methyl 500 mg daily or placebo for 16 weeks, in addition to background treatment with atorvastatin and other evidence-based therapies. The primary efficacy parameter is the combination of cardiovascular death, nonfatal myocardial infarction, nonfatal stroke or hospitalization for unstable angina with objective evidence of myocardial ischemia. Effects of varespladib methyl on lipid and inflammatory markers, in addition to safety and tolerability, will also be evaluated.

CONCLUSION

sPLA(2) inhibition has the potential to exert a favorable effect on the artery wall. The VISTA-16 study will determine whether varespladib methyl has a beneficial impact on cardiovascular events in patients with an acute coronary syndrome.

On-treatment non-high-density lipoprotein cholesterol, apolipoprotein B, triglycerides, and lipid ratios in relation to residual vascular risk after treatment with potent statin therapy: JUPITER (justification for the use of statins in prevention: an intervention trial evaluating rosuvastatin)

OBJECTIVES

The goal of this study was to determine whether residual risk after high-dose statin therapy for primary prevention individuals with reduced levels of low-density lipoprotein cholesterol (LDL-C) is related to on-treatment apolipoprotein B, non-high-density lipoprotein cholesterol (non-HDL-C), trigylcerides, or lipid ratios, and how they compare with on-treatment LDL-C.

BACKGROUND

Guidelines focus on LDL-C as the primary target of therapy, yet residual risk for cardiovascular disease (CVD) among statin-treated individuals remains high and not fully explained.

METHODS

Participants in the randomized placebo-controlled JUPITER (Justification for the Use of Statins in Prevention: An Intervention Trial Evaluating Rosuvastatin) trial were adults without diabetes or CVD, with baseline LDL-C levels <130 mg/dl, high-sensitivity C-reactive protein levels ≥2 mg/l, and triglyceride concentrations <500 mg/dl. Individuals allocated to receive rosuvastatin 20 mg daily with baseline and on-treatment lipids and lipoproteins were examined in relation to the primary endpoint of incident CVD (nonfatal myocardial infarction or stroke, hospitalization for unstable angina, arterial revascularization, or cardiovascular death).

RESULTS

Using separate multivariate Cox models, statistically significant associations of a similar magnitude with residual risk of CVD were found for on-treatment LDL-C, non-HDL-C, apolipoprotein B, total cholesterol/HDL-C, LDL-C/HDL-C, and apolipoprotein B/A-I. The respective adjusted standardized hazard ratios (95% confidence intervals) for each of these measures were 1.31 (1.09 to 1.56), 1.25 (1.04 to 1.50), 1.27 (1.06 to 1.53), 1.22 (1.03 to 1.44), 1.29 (1.09 to 1.52), and 1.27 (1.09 to 1.49). The overall residual risk and the risk associated with these measures decreased among participants achieving on-treatment LDL-C ≤70 mg/dl, on-treatment non-HDL-C ≤100 mg/dl, or on-treatment apolipoprotein B ≤80 mg/dl. In contrast, on-treatment triglycerides showed no association with CVD.

CONCLUSIONS

In this primary prevention trial of nondiabetic individuals with low LDL-C and elevated high-sensitivity C-reactive protein, on-treatment LDL-C was as valuable as non-HDL-C, apolipoprotein B, or ratios in predicting residual risk. (JUPITER-Crestor 20mg Versus Placebo in Prevention of Cardiovascular [CV] Events; NCT00239681).

Antisense oligonucleotides for the treatment of dyslipidaemia

Antisense oligonucleotides (ASOs) are short synthetic analogues of natural nucleic acids designed to specifically bind to a target messenger RNA (mRNA) by Watson-Crick hybridization, inducing selective degradation of the mRNA or prohibiting translation of the selected mRNA into protein. Antisense technology has the ability to inhibit unique targets with high specificity and can be used to inhibit synthesis of a wide range of proteins that could influence lipoprotein levels and other targets. A number of different classes of antisense agents are under development. To date, mipomersen, a 2'-O-methoxyethyl phosphorothioate 20-mer ASO, is the most advanced ASO in clinical development. It is a second-generation ASO developed to inhibit the synthesis of apolipoprotein B (apoB)-100 in the liver. In Phase 3 clinical trials, mipomersen has been shown to significantly reduce plasma low-density lipoprotein cholesterol (LDL-c) as well as other atherogenic apoB containing lipoproteins such as lipoprotein (a) [Lp(a)] and small-dense LDL particles. Although concerns have been raised because of an increase in intrahepatic triglyceride content, preliminary data from long-term studies suggest that with continued treatment, liver fat levels tend to stabilize or decline. Further studies are needed to evaluate potential clinical relevance of these changes. Proprotein convertase subtilisin/kexin-9 (PCSK9) is another promising novel target for lowering LDL-c by ASOs. Both second-generation ASOs and ASOs using locked nucleic acid technology have been developed to inhibit PCSK9 and are under clinical development. Other targets currently being addressed include apoC-III and apo(a) or Lp(a). By directly inhibiting the synthesis of specific proteins, ASO technology offers a promising new approach to influence the metabolism of lipids and to control lipoprotein levels. Its application to a wide variety of potential targets can be expected if these agents prove to be clinically safe and effective.

Plasma levels of PCSK9 and phenotypic variability in familial hypercholesterolemia

The extent of hypercholesterolemia varies considerably in patients with familial hypercholesterolemia (FH). We hypothesized that the variability of the FH phenotype might be partly explained by variation in proprotein convertase subtilisin kexin type 9 (PCSK9) activity. Individuals between 18 and 53 years of age who had been tested for a pathogenic LDLR or APOB mutation were eligible. Mutation carriers with a LDL-C level below the 75(th) percentile (called "FH low") were selected, as well as those with LDL-C above the 90(th) percentile (called "FH high"). Relatives who tested negative for the mutation were the "controls." PCSK9 plasma levels were assessed in 267 individuals who did not receive cholesterol-lowering treatment at the time of the study. Mean PCSK9 plasma levels (95% CI) were lower in the FH-low group compared with the FH-high group [152 (137-167) ng/ml vs. 186 (165-207) ng/ml, P = 0.010] and the control group [177 (164-190) ng/ml, P = 0.013]. Mean PCSK9 levels did not statistically differ between the FH-high and control groups (P = 0.50). Plasma PCSK9 levels are positively associated with LDL-C levels in FH patients and might contribute to the phenotypic severity in this disorder. Therefore, the results of pharmaceutical inhibition of PCSK9 in FH patients are eagerly awaited.

Mipomersen, an apolipoprotein B synthesis inhibitor, lowers low-density lipoprotein cholesterol in high-risk statin-intolerant patients: a randomized, double-blind, placebo-controlled trial

Aims

A randomized, double-blind, placebo-controlled study was conducted to investigate the safety and efficacy of mipomersen, an apolipoprotein B-100 (apoB) synthesis inhibitor, in patients who are statin intolerant and at high risk for cardiovascular disease (CVD).

Methods and results

Thirty-three subjects, not receiving statin therapy because of statin intolerance, received a weekly subcutaneous dose of 200 mg mipomersen or placebo (2:1 randomization) for 26 weeks. The primary endpoint was per cent change in LDL cholesterol (LDL-c) from the baseline to Week 28. The other efficacy endpoints were per cent change in apoB and lipoprotein a [Lp(a)]. Safety was determined using the incidence of treatment-emergent adverse events (AEs) and clinical laboratory evaluations. After 26 weeks of mipomersen administration, LDL-c was reduced by 47 ± 18% (P < 0.001 vs. placebo). apoB and Lp(a) were also significantly reduced by 46 and 27%, respectively (P < 0.001 vs. placebo). Four mipomersen (19%) and two placebo subjects (17%) discontinued dosing prematurely due to AEs. Persistent liver transaminase increases ≥3× the upper limit of normal were observed in seven (33%) subjects assigned to mipomersen. In selected subjects, liver fat content was assessed, during and after treatment, using magnetic resonance spectroscopy. Liver fat content in these patients ranged from 0.8 to 47.3%. Liver needle biopsy was performed in two of these subjects, confirming hepatic steatosis with minimal inflammation or fibrosis.

Conclusion

The present data suggest that mipomersen is a potential therapeutic option in statin-intolerant patients at high risk for CVD. The long-term follow-up of liver safety is required.

Clinical Trial Registration: ClinicalTrials.gov identifier: NCT00707746

Interleukin-6 receptor pathways in coronary heart disease: a collaborative meta-analysis of 82 studies

BACKGROUND

Persistent inflammation has been proposed to contribute to various stages in the pathogenesis of cardiovascular disease. Interleukin-6 receptor (IL6R) signalling propagates downstream inflammation cascades. To assess whether this pathway is causally relevant to coronary heart disease, we studied a functional genetic variant known to affect IL6R signalling.

METHODS

In a collaborative meta-analysis, we studied Asp358Ala (rs2228145) in IL6R in relation to a panel of conventional risk factors and inflammation biomarkers in 125,222 participants. We also compared the frequency of Asp358Ala in 51,441 patients with coronary heart disease and in 136,226 controls. To gain insight into possible mechanisms, we assessed Asp358Ala in relation to localised gene expression and to postlipopolysaccharide stimulation of interleukin 6.

FINDINGS

The minor allele frequency of Asp358Ala was 39%. Asp358Ala was not associated with lipid concentrations, blood pressure, adiposity, dysglycaemia, or smoking (p value for association per minor allele ≥0·04 for each). By contrast, for every copy of 358Ala inherited, mean concentration of IL6R increased by 34·3% (95% CI 30·4-38·2) and of interleukin 6 by 14·6% (10·7-18·4), and mean concentration of C-reactive protein was reduced by 7·5% (5·9-9·1) and of fibrinogen by 1·0% (0·7-1·3). For every copy of 358Ala inherited, risk of coronary heart disease was reduced by 3·4% (1·8-5·0). Asp358Ala was not related to IL6R mRNA levels or interleukin-6 production in monocytes.

INTERPRETATION

Large-scale human genetic and biomarker data are consistent with a causal association between IL6R-related pathways and coronary heart disease.

FUNDING

British Heart Foundation; UK Medical Research Council; UK National Institute of Health Research, Cambridge Biomedical Research Centre; BUPA Foundation.

Determinants of residual risk in secondary prevention patients treated with high- versus low-dose statin therapy: the Treating to New Targets (TNT) study

BACKGROUND

Cardiovascular events occur among statin-treated patients, albeit at lower rates. Risk factors for this "residual risk" have not been studied comprehensively. We aimed to identify determinants of this risk above and beyond lipid-related risk factors.

METHODS AND RESULTS

A total of 9251 coronary patients with low-density lipoprotein cholesterol <130 mg/dL randomized to double-blind atorvastatin 10 or 80 mg/d in the Treating to New Targets (TNT) study had complete on-treatment 1-year lipid data. Median follow-up was 4.9 years. The primary end point was major cardiovascular events (n=729): coronary death, nonfatal myocardial infarction, resuscitation after cardiac arrest, or fatal or nonfatal stroke. Multivariable determinants of increased risk were older age (adjusted hazard ratio [aHR], 1.13 per 1 SD [8.8 years]; 95% confidence interval [CI], 1.04-1.23), increased body mass index (aHR, 1.09; 95% CI, 1.02-1.17 per 4.5 kg/m(2)), male sex (aHR, 1.33; 95% CI, 1.07-1.65), hypertension (aHR, 1.38; 95% CI, 1.17-1.63), diabetes mellitus (aHR, 1.33; 95% CI, 1.11-1.60), baseline apolipoprotein B (aHR, 1.19; 95% CI, 1.11-1.28 per 19 mg/dL), and blood urea nitrogen (aHR, 1.10; 95% CI, 1.03-1.17 per 4.9 mg/dL), in addition to current smoking, prior cardiovascular disease, and calcium channel blocker use. Determinants of decreased risk were high-dose statin (aHR, 0.82; 95% CI, 0.70-0.94), aspirin use (aHR, 0.67; 95% CI, 0.56-0.81), and baseline apolipoprotein A-I (aHR, 0.91; 95% CI, 0.84-0.99 per 25 mg/dL). On-treatment 1-year lipids or apolipoproteins were not additionally associated with risk in multivariable models. Known baseline variables performed moderately well in discriminating future cases from noncases (Harrell c index=0.679).

CONCLUSIONS

Determinants of residual risk in statin-treated secondary prevention patients included lipid-related and nonlipid factors such as baseline apolipoproteins, increased body mass index, smoking, hypertension, and diabetes mellitus. A multifaceted prevention approach should be underscored to address this risk.

CLINICAL TRIAL REGISTRATION

URL: http://clinicaltrials.gov. Unique identifier: NCT00327691.

Association of LDL cholesterol, non-HDL cholesterol, and apolipoprotein B levels with risk of cardiovascular events among patients treated with statins: a meta-analysis

CONTEXT

The associations of low-density lipoprotein cholesterol (LDL-C), non-high-density lipoprotein cholesterol (non-HDL-C), and apolipoprotein B (apoB) levels with the risk of cardiovascular events among patients treated with statin therapy have not been reliably documented.

OBJECTIVE

To evaluate the relative strength of the associations of LDL-C, non-HDL-C, and apoB with cardiovascular risk among patients treated with statin therapy.

DESIGN

Meta-analysis of individual patient data from randomized controlled statin trials in which conventional lipids and apolipoproteins were determined in all study participants at baseline and at 1-year follow-up.

DATA SOURCES

Relevant trials were identified by a literature search updated through December 31, 2011. Investigators were contacted and individual patient data were requested and obtained for 62,154 patients enrolled in 8 trials published between 1994 and 2008.

DATA EXTRACTION

Hazard ratios (HRs) and corresponding 95% CIs for risk of major cardiovascular events adjusted for established risk factors by 1-SD increase in LDL-C, non-HDL-C, and apoB.

RESULTS

Among 38,153 patients allocated to statin therapy, 158 fatal myocardial infarctions, 1678 nonfatal myocardial infarctions, 615 fatal events from other coronary artery disease, 2806 hospitalizations for unstable angina, and 1029 fatal or nonfatal strokes occurred during follow-up. The adjusted HRs for major cardiovascular events per 1-SD increase were 1.13 (95% CI, 1.10-1.17) for LDL-C, 1.16 (95% CI, 1.12-1.19) for non-HDL-C, and 1.14 (95% CI, 1.11-1.18) for apoB. These HRs were significantly higher for non-HDL-C than LDL-C (P = .002) and apoB (P = .02). There was no significant difference between apoB and LDL-C (P = .21).

CONCLUSION

Among statin-treated patients, on-treatment levels of LDL-C, non-HDL-C, and apoB were each associated with risk of future major cardiovascular events, but the strength of this association was greater for non-HDL-C than for LDL-C and apoB.

Advances in genetics show the need for extending screening strategies for autosomal dominant hypercholesterolaemia

Aims Autosomal dominant hypercholesterolaemia (ADH) is a major risk factor for coronary artery disease. This disorder is caused by mutations in the genes coding for the low-density lipoprotein receptor (LDLR), apolipoprotein B (APOB), and proprotein convertase subtilisin/kexin 9 (PCSK9). However, in 41% of the cases, we cannot find mutations in these genes. In this study, new genetic approaches were used for the identification and validation of new variants that cause ADH. Methods and results Using exome sequencing, we unexpectedly identified a novel APOB mutation, p.R3059C, in a small-sized ADH family. Since this mutation was located outside the regularly screened APOB region, we extended our routine sequencing strategy and identified another novel APOB mutation (p.K3394N) in a second family. In vitro analyses show that both mutations attenuate binding to the LDLR significantly. Despite this, both mutations were not always associated with ADH in both families, which prompted us to validate causality through using a novel genetic approach. Conclusion This study shows that advances in genetics help increasing our understanding of the causes of ADH. We identified two novel functional APOB mutations located outside the routinely analysed APOB region, suggesting that screening for mutations causing ADH should encompass the entire APOB coding sequence involved in LDL binding to help identifying and treating patients at increased cardiovascular risk.

Cardiovascular risk in relation to functionality of sequence variants in the gene coding for the low-density lipoprotein receptor: a study among 29,365 individuals tested for 64 specific low-density lipoprotein-receptor sequence variants

AIMS

A plethora of mutations in the LDL-receptor gene (LDLR) underlie the clinical phenotype of familial hypercholesterolaemia (FH). For the diagnosis of FH, it is important, however, to discriminate between pathogenic and non-pathogenic mutations. The aim of the current study was to assess whether true pathogenic mutations were indeed associated with the occurrence of coronary artery disease (CAD) when compared with non-functional variants. The latter variants should not exhibit such an association with CAD.

METHODS AND RESULTS

We assessed 29 365 individuals tested the 64 most prevalent LDLR variants. First, we determined pathogenicity for each of these sequence variants. Subsequently, a Cox-proportional hazard model was used to compare event-free survival, defined as the period from birth until the first CAD event, between carriers and non-carriers of LDLR mutations. Fifty-four sequence variants in the LDLR gene were labelled as pathogenic and 10 as non-pathogenic. The 9 912 carriers of a pathogenic LDLR mutation had a shorter event-free survival than the 18 393 relatives who did not carry that mutation; hazard ratio 3.64 [95% confidence interval (CI): 3.24-4.08; P< 0.001]. In contrast, the 355 carriers of a non-pathogenic LDLR variant had similar event-free survival as the 705 non-carrying relatives; hazard ratio 1.00 (95% CI: 0.52-1.94; P= 0.999).

CONCLUSION

These findings with respect to clinical outcomes substantiate our criteria for functionality of LDLR sequence variants. They also confirm the CAD risk associated with FH and underline that these criteria can be used to decide whether a specific sequence variant should be used in cascade screening.

Monocyte gene expression signature of patients with early onset coronary artery disease

The burden of cardiovascular disease (CVD) cannot be fully addressed by therapy targeting known pathophysiological pathways. Even with stringent control of all risk factors CVD events are only diminished by half. A number of additional pathways probably play a role in the development of CVD and might serve as novel therapeutic targets. Genome wide expression studies represent a powerful tool to identify such novel pathways. We compared the expression profiles in monocytes from twenty two young male patients with premature familial CAD with those from controls matched for age, sex and smoking status, without a family history of CVD. Since all patients were on statins and aspirin treatment, potentially affecting the expression of genes in monocytes, twelve controls were subsequently treated with simvastatin and aspirin for 6 and 2 weeks, respectively.

By whole genome expression arrays six genes were identified to have differential expression in the monocytes of patients versus controls; ABCA1, ABCG1 and RGS1 were downregulated in patients, whereas ADRB2, FOLR3 and GSTM1 were upregulated. Differential expression of all genes, apart from GSTM1, was confirmed by qPCR. Aspirin and statins altered gene expression of ABCG1 and ADBR2. All finding were validated in a second group of twenty four patients and controls. Differential expression of ABCA1, RSG1 and ADBR2 was replicated. In conclusion, we identified these 3 genes to be expressed differently in CAD cases which might play a role in the pathogenesis of atherosclerotic vascular disease.

Vascular effects and safety of dalcetrapib in patients with or at risk of coronary heart disease: the dal-VESSEL randomized clinical trial

AIMS

High-density lipoprotein cholesterol (HDL-C) is inversely associated with cardiovascular (CV) events and thus an attractive therapeutic target. However, in spite of marked elevations in HDL-C, the first cholesterol transport protein (CETP) inhibitor torcetrapib raised blood pressure (BP), impaired endothelial function, and increased CV mortality and morbidity. Dalcetrapib is a novel molecule acting on CETP with a different chemical structure to torcetrapib. As HDL stimulates nitric oxide (NO), suppresses inflammation, and exerts protective CV effects, we investigated the effects of dalcetrapib on endothelial function, blood pressure, inflammatory markers, and lipids in patients with, or at risk of, coronary heart disease (CHD) in a double-blind randomized placebo-controlled trial (clinicaltrials.gov number NCT00655538).

METHODS AND RESULTS

Patients with target low-density lipoprotein cholesterol (LDL-C) levels received dalcetrapib 600 mg/day or placebo for 36 weeks on top of standard therapy (including statins). The primary outcome measures were the change from baseline of flow-mediated dilatation (%FMD) of the right brachial artery after 5 min of cuff occlusion at 12 weeks and the 24 h ambulatory blood pressure monitoring (ABPM) at week 4. Secondary outcomes included change from baseline in FMD after 36 weeks and the change in ABPM at 12 and 36 weeks, changes in HDL-C, LDL-C, triglycerides, CETP activity, as well as standard safety parameters. Four hundred seventy-six patients were randomized. Baseline FMD was 4.1 ± 2.2 and 4.0 ± 2.4% with placebo or dalcetrapib, respectively and did not change significantly from placebo after 12 and 36 weeks (P = 0.1764 and 0.9515, respectively). After 4, 24, and 36 weeks of treatment with dalcetrapib, CETP activity decreased by 51, 53, and 56% (placebo corrected, all P < 0.0001), while at weeks 4, 12, and 36 HDL-C increased by 25, 27, and 31% (placebo corrected, all P < 0.0001). Low-density lipoprotein cholesterol levels did not change. At baseline, ABPM was 125 ± 12/74 ± 8mmHg in the placebo and 128 ± 11/75 ± 7mmHg in the dalcetrapib group (P = 0.3372 and 0.1248, respectively, placebo-corrected change from baseline) and did not change for up to 36 weeks. Biomarkers of inflammation, oxidative stress, and coagulation did not change during follow-up except for Lp-PLA(2) mass levels which increased by 17% (placebo corrected). Overall 7 patients given dalcetrapib and 8 patients given placebo experienced at least one pre-specified adjudicated event (11 events with dalcetrapib and 12 events with placebo).

CONCLUSION

The dal-VESSEL trial has established the tolerability and safety of CETP-inhibition with dalcetrapib in patients with or at risk of CHD. Dalcetrapib reduced CETP activity and increased HDL-C levels without affecting NO-dependent endothelial function, blood pressure, or markers of inflammation and oxidative stress. The dal-OUTCOMES trial (NCT00658515) will show whether dalcetrapib improves outcomes in spite of a lack of effect on endothelial function.

Carriers of lecithin cholesterol acyltransferase gene mutations have accelerated atherogenesis as assessed by carotid 3.0-T magnetic resonance imaging [corrected]

OBJECTIVES

The aim of this study was to investigate the role of reduced lecithin: cholesterol acyltransferase (LCAT) function on atherogenesis using 3.0-T carotid magnetic resonance imaging (MRI) and B-mode ultrasound.

BACKGROUND

The role of low high-density lipoprotein cholesterol as a causal factor in atherogenesis has recently been questioned. LCAT plays a key role in high-density lipoprotein cholesterol metabolism.

METHODS

Carotid 3.0-T MRI and B-mode ultrasound measurements were performed in 40 carriers of LCAT gene mutations and 40 controls, matched for age. Patients with cardiovascular disease were excluded.

RESULTS

Carriers had 31% lower LCAT activity levels and 38% decreased high-density lipoprotein cholesterol levels (both p < 0.001 vs. controls). Carriers presented with a 10% higher normalized wall index (0.34 ± 0.07 vs. 0.31 ± 0.04, p = 0.002), a 22% higher mean wall area (17.3 ± 8.5 mm(2) vs. 14.2 ± 4.1 mm(2), p = 0.01), and a 22% higher total wall volume (1,039 ± 508 mm(3) vs. 851 ± 247 mm(3), p = 0.01 vs. controls) as measured by MRI. The prevalence (20 vs. 5, p = 0.002) and the total volume (102 mm(3) vs. 3 mm(3)) of atherosclerotic plaque components on MRI relating to lipid-rich tissue or calcification were also higher in carriers than in controls. All differences retained significance after adjustment for age, sex, blood pressure, low-density lipoprotein cholesterol, body mass index, smoking, and family history of cardiovascular disease. Common carotid intima-media thickness measured with ultrasound was increased in carriers by 12.5% (0.72 ± 0.33 mm vs. 0.64 ± 0.15 mm, p = 0.14).

CONCLUSIONS

Carriers of LCAT gene mutations exhibit increased carotid atherosclerosis, indicating an increased risk of cardiovascular disease. The present findings imply that increasing LCAT activity may be an attractive target in cardiovascular prevention strategies.

Infusion of a lipid emulsion in healthy men decreases the serotonergic response

Subjects with obesity and insulin resistance display a low response to a serotonergic challenge test. One of the hallmarks of obesity and insulin resistance is elevated plasma free fatty acids (FFAs). We hypothesize that increasing plasma FFA by infusion of a lipid emulsion, may be a contributing component leading to decreased serotonergic responsivity in healthy young men. Ten lean healthy men, 23.6 ± 5.0 years and BMI 22.6 ± 1.9 kg/m(2), were included. Serotonergic responsivity was assessed using the prolactin response to infusion with citalopram, a selective serotonin reuptake inhibitor, which is a validated tool to assess serotonergic tone. All participants received a lipid/heparin emulsion (Intralipid) infusion during 6 h. Saline infusion was used as a control. To evaluate a possible effect of heparin per se on prolactin, four out of the ten subjects also received heparin only during 6 h without the serotonergic challenge test. Plasma prolactin increased by 74.3 ± 15.5% during saline infusion. Intralipid infusion increased plasma FFA from 0.5 ± 0.05 to 2.3 ± 0.2 mmol/l (p < 0.001). The increase in plasma prolactin during Intralipid infusion was significantly lower (39.3 ± 10%; p < 0.001 compared to saline infusion). Heparin infusion per se increased plasma prolactin by 14.0 ± 1.9%. We found that during the Intralipid infusion with concomitant high plasma FFA levels the serotonergic response was decreased in healthy young men. Higher FFA levels may be the mediator of the decreased serotonergic response reported in patients with insulin resistance and obesity.

Genetic variation in APOB, PCSK9, and ANGPTL3 in carriers of pathogenic autosomal dominant hypercholesterolemic mutations with unexpected low LDL-Cl Levels

Autosomal Dominant Hypercholesterolemia (ADH) is caused by LDLR and APOB mutations. However, genetically diagnosed ADH patients do not always exhibit the expected hypercholesterolemic phenotype. Of 4,669 genetically diagnosed ADH patients, identified through the national identification screening program for ADH, 75 patients (1.6%) had LDL-cholesterol (LDL-C) levels below the 50th percentile for age and gender prior to lipid-lowering therapy. The genes encoding APOB, PCSK9, and ANGPTL3 were sequenced in these subjects to address whether monogenic dominant loss-of-function mutations underlie this paradoxical phenotype. APOB mutations, resulting in truncated APOB, were found in five (6.7%) probands, reducing LDL-C by 56%. Rare variants in PCSK9, and ANGPTL3 completely correcting the hypercholesterolemic phenotype were not found. The common variants p.N902N, c.3842+82T>A, p.D2312D, and p.E4181K in APOB, and c.1863+94A>G in PCSK9 were significantly more prevalent in our cohort compared to the general European population. Interestingly, 40% of our probands carried at least one minor allele for all four common APOB variants compared to 1.5% in the general European population. While we found a low prevalence of rare variants in our cohort, our data suggest that regions in proximity of the analyzed loci, and linked to specific common haplotypes, might harbor additional variants that correct an ADH phenotype.

Reducing cardiovascular disease risk in patients with type 2 diabetes and concomitant macrovascular disease: can insulin be too much of a good thing?

Despite improvement of microvascular outcomes as a consequence of optimal glucose control in patients with type 2 diabetes, prevention of macrovascular complications is still a major challenge. Of interest, large-scale intervention studies (Action to Control Cardiovascular Risk in Diabetes, Action in Diabetes and Vascular Disease-Preterax and Diamicron Modified Release Controlled Evaluation and Veterans Affairs Diabetes Trial) comparing standard therapy versus more intensive glucose-lowering therapy failed to report beneficial impacts on macrovascular outcomes. Consequently, it is currently under debate whether the high doses of exogenous insulin that were administered in these trials to achieve strict target glucose levels could be responsible for these unexpected outcomes. Additionally, a potential role for plasma insulin levels in predicting macrovascular outcomes has emerged in patients with or without type 2 diabetes. These observations, combined with evidence from in vitro and animal experiments, suggest that insulin might have intrinsic atherogenic effects. In this review, we summarize clinical trials, population-based studies as well as data emerging from basic science experiments that point towards the hypothesis that the administration of high insulin doses might not be beneficial in patients with type 2 diabetes and established macrovascular disease.

The 719Arg variant of KIF6 and cardiovascular outcomes in statin-treated, stable coronary patients of the treating to new targets and incremental decrease in end points through aggressive lipid-lowering prospective studies

BACKGROUND

Carriers of the KIF6 719Arg variant may be at increased risk for CVD and may benefit more from statin therapy, in terms of CVD risk reduction, than noncarriers. Our objective was to investigate whether carriers of the KIF6 719Arg genetic variant (rs20455) are at increased cardiovascular risk and obtain more benefit from high-dose statin therapy than do noncarriers.

METHODS AND RESULTS

We used an adjusted Cox proportional hazard model to assess the hazard ratio (HR) for the reduction of major cardiovascular events by 80 mg/d atorvastatin over 10 mg/d atorvastatin in 4599 patients of the Treating to New Targets (TNT) study and by 80 mg/d atorvastatin over 20-40 mg/d simvastatin in 6541 patients of the Incremental Decrease in End Points Through Aggressive Lipid-Lowering (IDEAL) study. A total of 381 and 648 patients had a cardiovascular event during follow-up in TNT and IDEAL, respectively. Heterozygotes and homozygotes for the minor allele were not at increased risk compared with noncarriers. In TNT, for noncarriers of the 719Arg allele, the HR for high- versus low-dose atorvastatin was 0.81 (95% confidence interval, 0.59-1.11). In carriers of 1 or 2 minor alleles, the HR was 0.85 (0.66-1.11) and carriers of 2 copies of the minor allele obtained a significant risk reduction (HR: 0.44, 95% confidence interval, 0.23-0.84). In IDEAL, the respective HRs were 0.85 (0.67-1.10), 0.88 (0.62-1.07) and 0.91 (0.58-1.43). The interaction term for carrier status by treatment was also nonsignificant (P=0.810 in TNT and P=0.909 in IDEAL).

CONCLUSIONS

In these 2 large, randomized clinical trials, carriers of the KIF6 719Arg allele were not at increased cardiovascular risk and did not obtain consistent cardiovascular benefit from high-dose statin therapy compared with noncarriers.

Effects of the CETP inhibitor evacetrapib administered as monotherapy or in combination with statins on HDL and LDL cholesterol: a randomized controlled trial

CONTEXT

Interest remains high in cholesteryl ester transfer protein (CETP) inhibitors as cardioprotective agents. Few studies have documented the efficacy and safety of CETP inhibitors in combination with commonly used statins.

OBJECTIVE

To examine the biochemical effects, safety, and tolerability of evacetrapib, as monotherapy and in combination with statins, in patients with dyslipidemia.

DESIGN, SETTING, AND PARTICIPANTS

Randomized controlled trial conducted among 398 patients with elevated low-density lipoprotein cholesterol (LDL-C) or low high-density lipoprotein cholesterol (HDL-C) levels from April 2010 to January 2011 at community and academic centers in the United States and Europe.

INTERVENTIONS

Following dietary lead-in, patients were randomly assigned to receive placebo (n = 38); evacetrapib monotherapy, 30 mg/d (n = 40), 100 mg/d (n = 39), or 500 mg/d (n = 42); or statin therapy (n = 239) (simvastatin, 40 mg/d; atorvastatin, 20 mg/d; or rosuvastatin, 10 mg/d) with or without evacetrapib, 100 mg/d, for 12 weeks.

MAIN OUTCOME MEASURES

The co-primary end points were percentage changes from baseline in HDL-C and LDL-C after 12 weeks of treatment.

RESULTS

The mean baseline HDL-C level was 55.1 (SD, 15.3) mg/dL and the mean baseline LDL-C level was 144.3 (SD, 26.6) mg/dL. As monotherapy, evacetrapib produced dose-dependent increases in HDL-C of 30.0 to 66.0 mg/dL (53.6% to 128.8%) compared with a decrease with placebo of -0.7 mg/dL (-3.0%; P < .001 for all compared with placebo) and decreases in LDL-C of -20.5 to -51.4 mg/dL (-13.6% to -35.9%) compared with an increase with placebo of 7.2 mg/dL (3.9%; P < .001 for all compared with placebo). In combination with statin therapy, evacetrapib, 100 mg/d, produced increases in HDL-C of 42.1 to 50.5 mg/dL (78.5% to 88.5%; P < .001 for all compared with statin monotherapy) and decreases in LDL-C of -67.1 to -75.8 mg/dL (-11.2% to -13.9%; P < .001 for all compared with statin monotherapy). Compared with evacetrapib monotherapy, the combination of statins and evacetrapib resulted in greater reductions in LDL-C (P <.001) but no greater increase in HDL-C (P =.39). Although the study was underpowered, no adverse effects were observed.

CONCLUSIONS

Compared with placebo or statin monotherapy, evacetrapib as monotherapy or in combination with statins increased HDL-C levels and decreased LDL-C levels. The effects on cardiovascular outcomes require further investigation.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01105975.

Apolipoprotein isoform E4 does not increase coronary heart disease risk in carriers of low-density lipoprotein receptor mutations

BACKGROUND

In humans, the E4 allele of the apolipoprotein E gene is associated with increased coronary heart disease risk. Surprisingly, in rodents, apolipoprotein E4 only accelerates the atherosclerotic process when transgenic for the human low-density lipoprotein receptor (LDLR) protein. We therefore investigated whether the LDLR locus interacted with the apolipoprotein E gene genotype on coronary heart disease risk in patients clinically diagnosed with familial hypercholesterolemia with and without LDLR mutation. We investigated whether the presence of an LDLR mutation diminishing LDLR function was protective in E4/E4 carriers.

METHODS AND RESULTS

In a cohort of 2400 patients clinically diagnosed with familial hypercholesterolemia, we found an LDLR gene mutation in 1383 patients, whereas in 1013 patients, such mutation was not present. In 92 patients homozygous for the apolipoprotein E4, the presence of an LDLR mutation conferred lower coronary heart disease risk (hazard ratio, 0.16; 95% CI, 0.05-0.58; P=0.005). Mirroring these results, the apolipoprotein E4/E4 genotype was also associated with lower coronary heart disease risk in patients with familial hypercholesterolemia with an LDLR mutation (hazard ratio, 0.26; hazard ratio, 0.08-0.80; P=0.02).

CONCLUSIONS

LDLR function is key to the detrimental effects of apolipoprotein E4 in humans. Kinetic studies in humans are now required to study the consequences of our observation for prevention of both coronary heart disease and Alzheimer disease.

Extreme xanthomatosis in patients with both familial hypercholesterolemia and cerebrotendinous xanthomatosis

Two unrelated individuals were referred to Lipid Clinics in The Netherlands and Chile with extreme xanthomatosis and hypercholesterolemia. Both were diagnosed with heterozygous familial hypercholesterolemia (heFH) after molecular genetic analysis of the low-density lipoprotein (LDL) receptor gene. Since heFH by itself could not account for the massive xanthomas, the presence of an additional hereditary lipid or lipoprotein disorder was suspected. Further genetic analysis revealed homozygozity for mutations in the sterol 27-hydroxylase gene, confirming the diagnosis of cerebrotendinous xanthomatosis (CTX). Markedly, the typical neurological manifestations of CTX were absent, suggestive of a protective role of LDL-receptor deficiency against the severe neurological consequences of CTX.

Genome-wide association studies in atherosclerosis

Cardiovascular disease remains the major cause of worldwide morbidity and mortality. Its pathophysiology is complex and multifactorial. Because the phenotype of cardiovascular disease often shows a marked heritable pattern, it is likely that genetic factors play an important role. In recent years, large genome-wide association studies have been conducted to decipher the molecular mechanisms underlying this heritable and prevalent phenotype. The emphasis of this review is on the recently identified 17 susceptibility loci for coronary artery disease. Implications of their discovery for biology and clinical medicine are discussed. A description of the landscape of human genetics in the near future in the context of next-generation sequence technologies is provided at the conclusion of this review.

High prevalence of mutations in LCAT in patients with low HDL cholesterol levels in The Netherlands: identification and characterization of eight novel mutations

Lecithin:cholesterol acyltransferase (LCAT) is crucial to the maturation of high-density lipoprotein (HDL). Homozygosity for LCAT mutations underlies rare disorders characterized by HDL-cholesterol (HDL-c) deficiency while heterozygotes have half normal HDL-c levels. We studied the prevalence of LCAT mutations in referred patients with low HDL-c to better understand the molecular basis of low HDL-c in our patients. LCAT was sequenced in 98 patients referred for HDL-c <5th percentile and in four patients referred for low HDL-c and corneal opacities. LCAT mutations were highly prevalent: in 28 of the 98 participants (29%), heterozygosity for nonsynonymous mutations was identified while 18 patients carried the same mutation (p.T147I). The four patients with corneal opacity were compound heterozygotes. All previously identified mutations are documented to cause loss of catalytic activity. Nine novel mutations-c.402G>T (p.E134D), c.403T>A (p.Y135N), c.964C>T (p.R322C), c.296G>C (p.W99S), c.736G>T (p.V246F), c.802C>T (p.R268C), c.945G>A (p.W315X), c.1012C>T (p.L338F), and c.1039C>T (p.R347C)--were shown to be functional through in vitro characterization. The effect of several mutations on the core protein structure was studied by a three-dimensional (3D) model. Unlike previous reports, functional mutations in LCAT were found in 29% of patients with low HDL-c, thus constituting a common cause of low HDL-c in referred patients in The Netherlands.

Obesity and dyslipidemia

Dyslipidemia associated with obesity and the metabolic syndrome is one of the central features contributing to the increased CV risk in these patients. In view of the pandemic of the metabolic syndrome, it is imperative to fully understand the mechanisms leading to the metabolic lipid phenotype before embarking upon optimal treatment strategies. The traditional concept that insulin resistance causes increased FFA flux via increased TG hydrolysis in adipose tissue is still of a central theme in the general hypothesis. The combination of increased hepatic VLDL secretion with impaired LPL-mediated TG clearance explains the hypertriglyceridemia phenotype of the metabolic syndrome. Hence, central IR may be an important factor contributing to peripheral hypertriglyceridemia. Recently recognized regulatory systems include the profound impact of the hypothalamus on TG secretion and glucose control. In addition, dysfunctional (or inflamed) intra abdominal adipose tissue has emerged as a potent regulator of dyslipidemia and IR. It will be a challenge to design novel treatment modalities that target “dysfunctional” fat or central IR to attempt to prevent the epidemic of CV disease secondary to the metabolic syndrome.

Novel mutations in scavenger receptor BI associated with high HDL cholesterol in humans

The scavenger receptor class B, member 1 (SR-BI), is a key cellular receptor for high-density lipoprotein (HDL) in mice, but its relevance to human physiology has not been well established. Recently a family was reported with a mutation in the gene encoding SR-BI and high HDL cholesterol (HDL-C). Here we report two additional individuals with extremely high HDL-C (greater than the 90th percentile for age and gender) with rare mutations in the gene encoding SR-BI. These mutations segregate with high HDL-C in family members of each proband and are associated with a 37% increase in plasma HDL-C in heterozygous individuals carrying them. Both mutations occur at highly conserved positions in the large extracellular loop region of SR-BI and are predicted to impair the function of the SR-BI protein. Our findings, combined with the prior report of a single mutation in the gene encoding SR-BI, further validate that mutations in SR-BI are a rare but recurring cause of elevated HDL-C in humans.

Increased risk of coronary artery disease in Caucasians with extremely low HDL cholesterol due to mutations in ABCA1, APOA1, and LCAT

Mutations in ABCA1, APOA1, and LCAT reduce HDL cholesterol (HDLc) in humans. However, the prevalence of these mutations and their relative effects on HDLc reduction and risk of coronary artery disease (CAD) are less clear. Here we searched for ABCA1, APOA1, and LCAT mutations in 178 unrelated probands with HDLc <10th percentile but no other major lipid abnormalities, including 89 with ≥1 first-degree relative with low HDLc (familial probands) and 89 where familial status of low HDLc is uncertain (unknown probands). Mutations were most frequent in LCAT (15.7%), followed by ABCA1 (9.0%) and APOA1 (4.5%), and were found in 42.7% of familial but only 14.6% of unknown probands (p=2.44∗10(-5)). Interestingly, only 16 of 24 (66.7%) mutations assessed in families conferred an average HDLc <10th percentile. Furthermore, only mutation carriers with HDLc <5th percentile had elevated risk of CAD (odds ratio (OR)=2.26 for 34 ABCA1 mutation carriers vs. 149 total first-degree relative controls, p=0.05; OR=2.50 for 26 APOA1 mutation carriers, p=0.04; OR=3.44 for 38 LCAT mutation carriers, p=1.1∗10(-3)). These observations show that mutations in ABCA1, APOA1, and LCAT are sufficient to explain >40% of familial hypoalphalipoproteinemia in this cohort. Moreover, individuals with mutations and large reductions in HDLc have increased risk of CAD. This article is part of a Special Issue entitled Advances in High Density Lipoprotein Formation and Metabolism: A Tribute to John F. Oram (1945-2010).

Relationship of IgG and IgM autoantibodies and immune complexes to oxidized LDL with markers of oxidation and inflammation and cardiovascular events: results from the EPIC-Norfolk Study

Levels of IgG and IgM autoantibodies (AA) to malondialdehyde (MDA)-LDL and apoB-immune complexes (ICs) were measured in 748 cases and 1,723 controls in the EPIC-Norfolk cohort and their association to coronary artery disease (CAD) events determined. We evaluated whether AA and IC modify CAD risk associated with secretory phospholipase A(2) (sPLA(2)) type IIA mass and activity, lipoprotein-associated PLA(2) activity, lipoprotein (a) [Lp(a)], oxidized phospholipids on apoB-100 (OxPL/apoB), myeloperoxidase, and high sensitivity C-reactive protein. IgG ICs were higher in cases versus controls (P = 0.02). Elevated levels of IgM AA and IC were inversely associated with Framingham Risk Score and number of metabolic syndrome criteria (p range 0.02-0.001). In regression analyses adjusted for age, smoking, diabetes, LDL-cholesterol, HDL-cholesterol, and systolic blood pressure, the highest tertiles of IgG and IgM AA and IC were not associated with higher risk of CAD events compared with the lowest tertiles. However, elevated levels of IgM IC reduced the risk of Lp(a) (P = 0.006) and elevated IgG MDA-LDL potentiated the risk of sPLA(2) mass (P = 0.018). This epidemiological cohort of initially healthy subjects shows that IgG and IgM AA and IC are not independent predictors of CAD events but may modify CAD risk associated with elevated levels of oxidative biomarkers.

Adiponectin and risk of coronary heart disease in apparently healthy men and women (from the EPIC-Norfolk Prospective Population Study)

The objective of the present study was to evaluate the association between adiponectin levels and incidence of coronary heart disease (CHD). We performed a prospective case-control analysis nested in the EPIC-Norfolk cohort. Participants were apparently healthy men and women 45 to 79 years of age who developed fatal or nonfatal CHD during an average follow-up period of 7.7 ± 1.1 years. In total 1,035 participants with incident CHD were matched for age, gender, and enrollment time to 1,920 controls who remained free of CHD over the study follow-up. Baseline nonfasting plasma adiponectin concentrations were determined by enzyme-linked immunosorbent assay. Adiponectin levels were lower in participants with CHD than in matched controls (men 8.74 vs 9.13 μg/ml, p = 0.01; women 12.6 vs 13.4 μg/ml, p = 0.03). A 1-μg/ml increment in adiponectin was associated with decreased CHD risk (odds ratio 0.78, 95% confidence interval 0.63 to 0.96, p = 0.02, in men; odds ratio 0.73, 95% confidence interval 0.55 to 0.96, p = 0.03, in women). However, this association was no longer significant after adjustment for established cardiovascular risk factors. Stratification of participants according to metabolic syndrome status showed that men and women with metabolic syndrome had a higher CHD risk, irrespective of their adiponectin levels. In conclusion, although a low adiponectin concentration is associated with an increased CHD risk, findings of the present study do not suggest that its measurement is useful to refine CHD risk assessment once traditional risk factors and clinical features of the metabolic syndrome have been considered.

Triglycerides and cardiovascular risk

In 1996 a meta-analysis was published showing that an increase in plasma triglyceride (TG) levels was associated with an increase in CHD risk, even after adjustment for high density lipoprotein cholesterol (HDL-C) levels. Very recently, two studies were published that further extent the early observation and showed the importance of nonfasting plasma triglyceride (TG) levels in the prediction of risk on coronary heart disease (CHD). In the current review we have summarized all available evidence obtained in clinical studies showing that treatment guidelines should reconsider to include nonfasting TG in their risk assessments as nonfasting TG levels may better predict CVD risk.