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BACKGROUND AND AIMS: Leukocytosis, the expansion of white blood cells, is associated with increased cardiovascular risk. Studies in animal models have shown that high-density lipoprotein cholesterol (HDL-c) suppresses leukocytosis by mediating cholesterol efflux from hematopoietic stem and progenitor cells. HDL-c showed a moderate negative association with leukocyte numbers in the UK Biobank and Multi-Ethnic Study of Atherosclerosis. Cholesterol efflux capacity of HDL (HDL-CEC) or HDL particle (HDL-P) number has been proposed as improved inverse predictor of CVD compared to plasma HDL-c. In the LifeLines DEEP (LLD) cohort (n = 962), a sub-cohort representing the prospective population-based LL cohort from the North of The Netherlands, we tested the hypothesis that HDL-CEC and HDL-P were associated with lower leukocyte counts.METHODS: We carried out multivariable regression and causal mediation analyses (CMA) to test associations between HDL-c, HDL-CEC, or HDL-P and leukocyte counts. We measured HDL-CEC in THP-1 macrophages and HDL-P and composition using nuclear magnetic resonance.RESULTS: HDL-c associated negatively with leukocyte counts, as did extra-large and large HDL-P, while HDL-CEC showed no association. Each one-standard deviation (SD) increase in extra-large HDL-P was associated with 3.0% and 4.8% lower leukocytes and neutrophils, respectively (q < 0.001). In contrast, plasma concentration of small HDL-P associated positively with leukocyte and neutrophil counts, as did small HDL-P triglycerides (TG) and total plasma TG. CMA showed that the association between S-HDL-P and leukocytes was mediated by S-HDL-TG.CONCLUSIONS: The association between HDL-P and leukocyte counts in the general population is dependent on HDL-P size and composition, but not HDL-CEC.

Objectives: The current literature provides little information on the frequency of mutations in the ATP-binding cassette transporter A1 (ABCA1) in patients with low high-density lipoprotein cholesterol (HDL) levels that are referred to the clinic. In 78 patients with low plasma levels of HDL cholesterol that were referred to our clinic, we routinely screened for ABCA1 gene mutations and studied the functionality of newly identified ABCA1 missense mutations.Methods: The coding regions and exon-intron boundaries of the ABCA1 gene were sequenced in 78 subjects with HDL cholesterol levels below the 10th percentile for age and gender. Novel mutations were studied by assessing cholesterol efflux capacity (using apolipoprotein A-I as acceptor) after transient expression of ABCA1 variants in BHK cells.Results: Sixteen out of 78 patients (21%) were found to carry 19 different ABCA1 gene variants (1 frameshift, 2 splice-site, 4 nonsense and 12 missense variation) of which 14 variations were novel. Of three patients with homozygous mutations and three patients having compound heterozygous mutations only one patient presented with the clinical characteristics of Tangier Disease (TD) in the presence of nearly complete HDL deficiency. Seven out of eight newly identified ABCA1 missense mutations were found to exhibit a statistically significant loss of cholesterol efflux capacity.Conclusion: This study shows that one out of five patients who are referred to our hospital because of low HDL cholesterol levels have a functional ABCA1 gene mutation. It is furthermore demonstrated that in vitro studies are needed to assess functionality of ABCA1 missense mutations. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

Cholesteryl ester transfer protein (CETP) and hepatic lipase (HL) are two HDL modifying proteins that have both pro- and anti-atherogenic properties. We hypothesized that CETP and HL synergistically affect HDL cholesterol and atherosclerotic risk. To test our hypothesis, we analysed the genotype frequencies of CETP Taq 1B (rs708272) and LIPC-514C/T (rs1800588) polymorphisms in male coronary artery disease patients (CAD; n=792) and non-symptomatic controls (n=539). Cases and controls had similar allele frequencies, but the occurrence of the combined genotypes differed (p=0.027). In CAD patients, 1.3% had the CETP-B2B2/LIPC-TT genotype, with only 0.2% in controls (p=0.033). The presence of the CETP lowering B2 allele and the HL lowering LIPC-T allele synergistically increased HDL cholesterol from 0.87 +/- 0.19 mmol/L in the B1B1/CC (n =183) to 1.21 +/- 0.25 mmol/L in the B2B2/TT carriers (n = 10). The B1B1/CC carriers had an increased CAD risk (OR 1.4; p=0.025). Despite their high HDL cholesterol, the B2B2/TT individuals also had an increased CAD risk (OR 3.7; p = 0.033). In a 2-year follow up, the loss of coronary artery lumen diameter in these patients was higher than in all other patients combined (0.34 +/- 0.70 versus 0.10 +/- 0.29 mm; p = 0.044). We conclude that a high HDL cholesterol does not protect against coronary artery disease when associated with combined CETP- and HL-lowering gene variants. (C) 2007 Elsevier Ireland Ltd. All rights reserved.

BACKGROUND: Overexpression of lipoprotein lipase (LPL) protects against atherosclerosis in genetically engineered mice. We tested whether a gene therapy vector that delivers human (h) LPL(S447X) cDNA to skeletal muscle could induce similar effects. METHODS: LDL receptor knockout (LDLr-/-) mice were injected intramuscular (i.m.) with adeno-associated virus serotype 1 (AAV1) LPL(S447X) or PBS. Four weeks later they were started on an atherogenic diet for 12 weeks. After termination, atherosclerosis was assessed and homogenates of muscle and liver tissue were analyzed. RESULTS: AAV1-treated mice showed hLPL concentrations of 768+/-293 ng/mL in post-heparin plasma associated with 48% reductions of fasting triglycerides (TG) levels (p

Background: Fecal bile acid and neutral sterol excretion are the obligate endpoints of the reverse cholesterol transport pathway (RCT). In studies in mice, no evidence was found for a relation between HDL-cholesterol (HDL-c) levels and fecal sterol excretion. In this study, we have evaluated this relationship in patients with isolated low HDL-c versus controls. Results: Fecal sterol excretion was studied in 12 subjects with familial hypoalphalipoproteinemia (FHA) and 11 healthy controls. Compared to the controls (8.9 +/- 6.3 mg/kg/day), neutral sterol excretion was significantly lower in the FHA group (4.0 +/- 2.4 mg/kg/day). Fecal bile acid excretion showed a similar pattern. Across the groups, a strong positive correlation between HDL-c and fecal neutral sterol excretion was found (r = 0.53; p = 0.01). Conclusions: Isolated low HDL-c levels in humans are associated with reduced fecal sterol excretion suggesting that in humans HDL regulates the final step in the RCT pathway at low HDL-c levels. (c) 2009 Elsevier Ireland Ltd. All rights reserved

Insulin resistance often occurs with dyslipidemia as part of the metabolic syndrome and the current dominant paradigm is that insulin resistance leads to dyslipidemia. However, dyslipidemia may also cause insulin resistance; this was postulated 30 years ago, but has never been substantiated. Establishing whether dyslipidemia plays a causal role in the etiology of insulin resistance is important since it could reveal new avenues for combating type 2 diabetes. In this review we summarize recent evidence from epidemiological, genetic and intervention studies to re-address this old hypothesis.

Background Apolipoprotein M (apoM) has been identified as a specific sphingosine-1-phosphate (S1P) binding protein of HDL. Objectives and methods To investigate the in vivo effects of disturbed apoM or HDL metabolism we quantified S1P and apoM in plasmas of wild-type, apoM-knock-out, and apoM transgenic mice as well as 50 patients with seven different monogenic disorders of HDL metabolism and their 51 unaffected relatives. Results Compared to wild type mice, S1P plasma levels in apoM knock-out and apoM transgenic mice were decreased by 30% and increased by 270%, respectively. Compared to family controls, S1P and apoM levels in apoB-depleted plasma were significantly decreased by in average 34% and 12%, respectively, in heterozygous carriers of mutations in APOA1, LCAT or ABCA1, and by 70% and 48%, respectively, in carriers of two defective alleles in LCAT or ABCA1. Heterozygous mutations in CETP, SCARB1, LIPC, or LIPG did not significantly affect S1P or apoM concentrations. Albumin-corrected molar S1P-to-apoM ratios varied from 0.12 to 0.8 (median 0.3) and were not affected by any mutation. S1P levels in apoB-depleted plasma correlated significantly with HDL-cholesterol and less so with apoM both if apoA-I plasma concentrations were below the median. Conclusion In the context of previous data, our findings can be explained by the existence of a specific apoM and S1P containing HDL subclass which contains a considerable molar excess of apoM over S1P and is critically determined by apoA-I up to a threshold concentration around the median found in a Caucasian population.

Introduction Familial lecithin:cholesterol acyltransferase (LCAT) deficiency (FLD) is a rare recessive disorder of cholesterol metabolism characterized by the absence of high density lipoprotein (HDL) and the triad of corneal opacification, hemolytic anemia and glomerulopathy. Patients We here report on FLD in three siblings of a kindred of Moroccan descent with HDL deficiency. In all cases (17, 12 and 3 years of age) corneal opacification and proteinuria were observed. In the 17-year-old female proband, anemia with target cells was observed. Results Homozygosity for a mutation in LCAT resulted in the exchange of cysteine to tyrosine at position 337, disrupting the second disulfide bond in LCAT. LCAT protein and activity were undetectable in the patients’ plasma and in media of COS7 cells transfected with an expression vector with mutant LCAT cDNA. Upon treatment with an ACE inhibitor and a thiazide diuretic, proteinuria in the proband decreased from 6 g to 2 g/24 h. Conclusion This is the first report that FLD can cause nephropathy at a very early age.

Contains fulltext : 57142.pdf (Publisher’s version ) (Closed access) BACKGROUND: Cholesteryl ester transfer protein (CETP) mediates the transfer of neutral lipids between lipoproteins. The role of CETP in atherogenesis is controversial. To better understand the relationships between plasma CETP levels, lipoproteins and atherosclerosis, we assessed these parameters in patients with an enhanced risk for atherosclerosis. METHODS AND RESULTS: We investigated 281 patients with familial hypercholesterolemia (FH) in which the effects of two statins were compared in a 2-year, randomized, double-blinded study. Patients were stratified in quartiles according to their CETP baseline levels. In addition to correlations with decreased high-density lipoprotein cholesterol (HDL-c), increased low-density lipoprotein cholesterol (LDL-c) and enhanced triglyceride levels, higher CETP levels were also associated with reduced HDL particle size, and smaller and denser LDL. Statins reduced plasma CETP levels and atherogenic lipoproteins. Nevertheless, baseline CETP concentration was positively associated with IMT after 2 years of therapy. CONCLUSION: This study provides evidence that CETP levels are associated with a more atherogenic lipid profile and increased progression of atherosclerosis. Statin treatment improved the lipoprotein profile in FH patients, but to a lesser extent in those with high CETP levels. These findings might imply that statin treatment does not entirely counteract the lipoprotein abnormalities associated with high CETP levels.