Large HDL Particles Research Articles

Abstract P217: Metabolic Effects of a Nutrient-Dense High Fiber Supplement

Achieving recommended dietary intakes of vitamins and minerals, fiber, and other health-promoting small molecules, such as fruit polyphenolics and essential fatty acids, is difficult, even for healthy adults consuming generally good diets. We assessed the hypothesis that short term consumption of a comprehensive nutrition bar can favorably impact metabolic biomarkers linked to future disease risk. Methods: An approximately 100 kcal nutrition bar containing a vitamin, mineral, and docosahexaenoic acid (DHA)-fortified polyphenolic-rich whole food matrix composed of fruit, walnuts, and dark chocolate blended with insoluble and soluble fiber was developed. Pooled results are presented from 3 pilot trials in which 25 generally healthy adults (15 F, 10 M) were enrolled in 2-wk interventions to study the effect of twice-daily consumption of the bar on plasma lipoprotein subfractions (ion mobility analysis), and redox status (thiol amino acids) in addition to conventional biomarkers associated with dyslipidemia, insulin resistance, and inflammation. All variables were continuous, and paired t-tests were used to test for significant change between baseline and follow-up measures. Results: Mean HDL cholesterol increased by 6.6 + 9.7% ( p = 0.001), predominantly due to a rise in the large buoyant HDL2b subclass which rose from 1665.9 ± 1017.7 to 2089.4 ± 1197.6 nmol/L ( p < 0.0001; 28% increase). Plasma triglyceride and LDL cholesterol levels did not change significantly but there was a trend towards increased LDL peak particle diameter (p = 0.086). Mean plasma homocysteine decreased from 12.6 ± 6.4 to 10.2 ± 3.7 µM (p=0.006, 19.2% decline). Measures of insulin resistance and inflammation did not change. Weight remained stable despite intake of 200 additional daily calories. Participants reported a significant decrease in hunger on an analog scale and compensatory decreased intake of other foods. Summary: Twice daily consumption of a low-calorie complete nutritional supplement increases satiety and large HDL particle concentrations within 2 weeks without weight gain.

Pharmacological LXR activation reduces presence of SR-B1 in liver membranes contributing to LXR-mediated induction of HDL-cholesterol

ObjectivePharmacological LXR activation has anti-atherosclerotic actions in animal models. Part of these beneficial effects may be explained by accelerated reverse cholesterol transport since both plasma high density lipoprotein (HDL) cholesterol and fecal neutral sterol secretion are higher upon LXR activation. Mechanisms underlying these LXR-mediated effects have not been fully elucidated. MethodsWe investigated the roles of the isoforms LXRα and LXRβ and the HDL cholesterol uptake receptor SR-B1 in modulation of cholesterol metabolism upon treatment of mice with the LXR ligand T0901317. ResultsHDL cholesterol was maximally 60% increased in a time-dependent fashion due to appearance of more and larger HDL particles. Fecal neutral sterol secretion was maximally induced after 1week treatment. T0901317 treatment induced fecal neutral sterol secretion by ∼300% in wild-type but not in Lxrα deficient mice. Surprisingly, LXR activation reduced SR-B1 protein amount in hepatic membranes, suggesting that this might contribute to elevated HDL cholesterol. However, T0901317 still elevated plasma HDL cholesterol in Sr-b1 deficient mice, suggesting that SR-B1 is not the only step involved in LXR-mediated induction of plasma HDL cholesterol. In addition, SR-B1 is not essential for LXR-induced cholesterol removal from the body. ConclusionInduction of fecal neutral sterol secretion by T0901317 critically depends on LXRα but not on LXRβ. LXR activation reduces SR-B1 in hepatic membranes, probably partly contributing to elevated HDL cholesterol. SR-B1 is not required to enhance fecal neutral sterol secretion.

Changes in lipoprotein subfraction concentration and composition in healthy individuals treated with the CETP inhibitor anacetrapib

We investigated the effects of the cholesteryl ester (CE) transfer protein inhibitor anacetrapib (ANA) on plasma lipids, lipoprotein subfraction concentrations, and lipoprotein composition in 30 healthy individuals. Participants (n = 30) were randomized to ANA 20 mg/day, 150 mg/day, or placebo for 2 weeks. Changes in concentration of lipoprotein subfractions were assessed using ion mobility, and compositional analyses were performed on fractions separated by density gradient ultracentrifugation. ANA 150 mg/day versus placebo resulted in significant decreases in LDL-cholesterol (26%) and apo B (29%) and increases in HDL-cholesterol (82%). Concentrations of medium and small VLDL, large intermediate density lipoprotein (IDL), and medium and small LDL (LDL2a, 2b, and 3a) decreased whereas levels of very small and dense LDL4b were increased. There was enrichment of triglycerides and reduction of CE in VLDL, IDL, and the densest LDL fraction. Levels of large buoyant HDL particles were substantially increased, and there was enrichment of CE, apo AI, and apoCIII, but not apoAII or apoE, in the mid-HDL density range. Changes in lipoprotein subfraction concentrations and composition with ANA 20 mg/day were similar to those for ANA 150 mg/day but were generally smaller in magnitude. The impact of these changes on cardiovascular risk remains to be determined.

Niacin extended-release/simvastatin combination therapy produces larger favorable changes in high-density lipoprotein particles than atorvastatin monotherapy

BackgroundThe purpose of this research was to compare the effects of niacin extended-release in combination with simvastatin (NER/S) versus atorvastatin monotherapy on high-density lipoprotein (HDL) particle number and size in patients with hyperlipidemia or dyslipidemia from the SUPREME study.MethodsThis was a post hoc analysis of patients (n = 137) who completed the SUPREME study and who had lipid particle number and size measurements at both baseline and at week 12 by nuclear magnetic resonance spectroscopy. Following ≥4 weeks without lipid-modifying therapy (washout period), the patients received NER/S 1000/40 mg/day for 4 weeks followed by NER/S 2000/40 mg/day for 8 weeks, or atorvastatin 40 mg/day for 12 weeks. Median percent changes in HDL particle number and size from baseline to week 12 were compared between the NER/S and atorvastatin treatment groups using the Wilcoxon rank-sum test. Distribution of HDL particle subclasses at week 12 was compared between the treatment groups using the Cochran–Mantel–Haenszel test.ResultsTreatment with NER/S resulted in a significantly greater percent reduction in small HDL particle number at week 12 compared with atorvastatin monotherapy (−1.8% versus 4.2%, P = 0.014), and a numerically greater percent increase in large HDL particle number (102.4% versus 39.2%, P = 0.078) compared with atorvastatin monotherapy. A significantly greater percent increase in HDL particle size from baseline at week 12 was observed with NER/S compared with atorvastatin (6.0% versus 1.3%, P < 0.001). NER/S treatment also resulted in a significant shift in HDL particle size from small and medium at baseline to large at week 12 (P < 0.0001).ConclusionTreatment with NER/S resulted in larger favorable changes in number and size of HDL particle subclasses compared with atorvastatin monotherapy, including a numerically greater increase in number of large HDL particles, and a significantly greater decrease in number of small HDL particles compared with atorvastatin monotherapy. In addition, NER/S treatment resulted in a significant change in HDL particle size distribution from small and medium to large.

Metabolomics Reveals Reduction of Metabolic Oxidation in Women with Polycystic Ovary Syndrome after Pioglitazone-Flutamide-Metformin Polytherapy

Polycystic ovary syndrome (PCOS) is a variable disorder characterized by a broad spectrum of anomalies, including hyperandrogenemia, insulin resistance, dyslipidemia, body adiposity, low-grade inflammation and increased cardiovascular disease risks. Recently, a new polytherapy consisting of low-dose flutamide, metformin and pioglitazone in combination with an estro-progestagen resulted in the regulation of endocrine clinical markers in young and non-obese PCOS women. However, the metabolic processes involved in this phenotypic amelioration remain unidentified. In this work, we used NMR and MS-based untargeted metabolomics to study serum samples of young non-obese PCOS women prior to and at the end of a 30 months polytherapy receiving low-dose flutamide, metformin and pioglitazone in combination with an estro-progestagen. Our results reveal that the treatment decreased the levels of oxidized LDL particles in serum, as well as downstream metabolic oxidation products of LDL particles such as 9- and 13-HODE, azelaic acid and glutaric acid. In contrast, the radiuses of small dense LDL and large HDL particles were substantially increased after the treatment. Clinical and endocrine-metabolic markers were also monitored, showing that the level of HDL cholesterol was increased after the treatment, whereas the level of androgens and the carotid intima-media thickness were reduced. Significantly, the abundance of azelaic acid and the carotid intima-media thickness resulted in a high degree of correlation. Altogether, our results reveal that this new polytherapy markedly reverts the oxidant status of untreated PCOS women, and potentially improves the pro-atherosclerosis condition in these patients.

Multidimensional profiling of plasma lipoproteins by size exclusion chromatography followed by reverse-phase protein arrays

The composition of lipoproteins and the association of proteins with various particles are of much interest in the context of cardiovascular disease. Here, we describe a technique for the multidimensional analysis of lipoproteins and their associated apolipoproteins. Plasma is separated by size exclusion chromatography (SEC), and fractions are analyzed by reverse-phase arrays. SEC fractions are spotted on nitrocellulose slides and incubated with different antibodies against individual apolipoproteins or antibodies against various apolipoproteins. In this way, tens of analytes can be measured simultaneously in 100 μl of plasma from a single SEC separation. This methodology is particularly suited to simultaneous analysis of multiple proteins that may change their distribution to lipoproteins or alter their conformation, depending on factors that influence circulating lipoprotein size or composition. We observed changes in the distribution of exchangeable apolipoproteins following addition of recombinant apolipoproteins or interaction with exogenous compounds. While the cholesteryl ester transfer protein (CETP)-dependent formation of pre-β-HDL was inhibited by the CETP inhibitors torcetrapib and anacetrapib, it was not reduced by the CETP modulator dalcetrapib. This finding was elucidated using this technique.

Abstract 9515: NMR Spectroscopy Uncovers Important Atherogenic Lipoprotein Abnormalities in Nonalcoholic Fatty Liver Disease: The Insulin Resistance Atherosclerosis Study (IRAS).

Introduction: Nonalcoholic fatty liver disease may be the most frequent cause of chronically elevated transaminase levels in the general population. One of these inexpensive and routinely measured enzymes, alanine aminotransferase (ALT) is an independent predictor of future cardiovascular disease and diabetes. ALT has been associated with dyslipidemia, but the extent of this relationship is not well described. Hypothesis: Because to its advantage over conventional methods, we hypothesized that proton nuclear magnetic resonance (NMR) spectroscopy could be better for detecting atherogenic lipoprotein abnormalities in nonalcoholic fatty liver disease. Thus, we analyzed the relation of ALT to lipoproteins measured by NMR spectroscopy and conventional methods in non-diabetic participants in the IRAS. Methods: Cross-sectional analysis of lipoproteins and apolipoproteins in 912 non-diabetic participants in the IRAS. In fasting single fresh plasma samples, we measured plasma lipoproteins by conventional methods and NMR spectroscopy and apolipoprotein B (apo B) by immunoprecipitation. Insulin sensitivity was measured by the frequently sampled intravenous glucose tolerance test. Results: After adjusting for age, sex, race/ethnicity, and clinic, ALT was associated with triglycerides, LDL and HDL cholesterol, and apo B ( Table ). ALT had significant relationships with large VLDL, total LDL, IDL, small LDL, and large HDL particle concentrations plus VLDL, LDL, and HDL particle sizes. ALT remained associated with total LDL, IDL, and small LDL particle concentrations, LDL particle size, and apo B after the additional adjustment for waist circumference and insulin sensitivity. Conclusions: NMR spectroscopy uncovers a more extensive relationship between atherogenic lipoprotein abnormalities and ALT in non-diabetic individuals. These abnormalities could partially explain the relation of ALT to future cardiovascular disease.

Plasma High Density Lipoprotein and Anticoagulant Response to Activated Protein C (APC) and Protein S

Abstract 2249Previously we reported that plasma high density lipoprotein (HDL) enhances activated protein C (APC)/protein S (PS) anticoagulant action in plasma clotting and factor Va inactivation assays (APC/PS enhancement) and that lower HDL levels are found in male venous thrombosis patients or in patients with recurrent venous thrombosis versus controls, giving rise to our hypothesis that HDL helps protect against venous thrombosis. In this study, we sought (1) to identify which HDL particles enhance APC/PS activity, (2) to assess correlations between this activity and HDL particle size, and (3) to evaluate the recent challenge to our HDL anticoagulant activity hypothesis (Oslakovic et al, J Clin Invest, 2010). To identify HDL subfractions with APC/PS enhancing activity, we subfractionated HDL by sequential density gradient ultracentrifugation over the HDL density range of 1.063–1.21 mg/dl. When the anticoagulant property of these HDL subtractions was studied, we found that the less dense HDL subfractions corresponding to HDL2 particles enhanced APC/PS anticoagulant activity much more than other HDL fractions. Thus, we identified larger HDL particles as the key subfraction for this anticoagulant property of HDL. Hence, we hypothesized that plasma levels of large HDL particles would correlate with plasma sensitivity of APC/protein S. To test this hypothesis, we used proton NMR to quantify the levels of large, medium and small HDL particles and to determine the average size of HDL particles in plasmas from 39 normal adults. We performed dilute tissue factor-induced clotting assays in the absence or presence of APC/protein S to define APC/PS sensitivity and assessed correlations. There was a positive correlation between large HDL particle concentration and plasma sensitivity to APC/protein S (r=0.40, p=0.02). The size of HDL particles was also positively correlated with plasma sensitivity to APC/protein S (r=0.42, p=0.01). As previously reported, apoAI concentrations which is major apolipoprotein in HDL correlated with plasma sensitivity to APC/protein S (r=0.52, p=0.0007). Thus, as hypothesized, apoAI-containing large HDL particle concentrations in plasma correlate very well with the anticoagulant response to APC/PS. Recently Oslakovic et al purported to show that APC/PS enhancement was not an intrinsic property of HDL and claimed that this activity was due to negatively charged phospholipid contaminants of HDL based on gel filtration (Superose 6) analysis of their frozen HDL preparation. Therefore, we applied Superose 6 gel filtration analyses to four different fresh, never-frozen HDL preparations coming either from commercial sources or from in-house preparations. Our studies showed that when each HDL prep was subjected to Superose 6 fractionation, the column fractions containing large HDL (apoAI positive fractions) enhanced APC/protein S anticoagulant activity in plasma clotting assays and also for the inactivation of factor Va in purified systems. Moreover, immobilized anti-apoAI-antibodies removed the APC/PS enhancing effect, further establishing the fact that apoAI-containing HDL particles enhance APC/PS activity. When we analyzed HDL preps stored at 4 °C over successive weeks, we found that HDL fractions lost the ability to enhance APC/PS, showing the relatively labile nature of this activity. Freezing and thawing HDL was also deleterious for this activity. Thus, the APC/PS enhancing activity of fresh, never-frozen HDL preps is primarily due to HDL particles. All of our new findings confirm our previous conclusion that HDL enhances APC/PS anticoagulant actions. Our extensive data set strongly contradicts the conclusions from the recent HDL study by Oslakovic et al who unfortunately performed their bioassays using frozen HDL made from previously frozen lipidmic plasma. In summary, freshly purified, non-frozen large HDL particles made from fresh plasma enhance APC/PS activity. The sensitivity of plasma of healthy adults to APC/PS anticoagulant effects is significantly correlated with the plasma levels of large HDL particles, suggesting the physiological importance of large HDL particles as enhancing the anticoagulant APC/PS system and supporting our hypothesis that large HDL particles may be protective against venous thrombosis, at least in part, via this activity. Disclosures:No relevant conflicts of interest to declare.

Dysfunctional HDL containing L159R ApoA-I leads to exacerbation of atherosclerosis in hyperlipidemic mice

The mutation L159R apoA-I or apoA-IL159R (FIN) is a single amino acid substitution within the sixth helical repeat of apoA-I. It is associated with a dominant negative phenotype, displaying hypoalphaproteinemia and an increased risk for atherosclerosis in humans. Mice lacking both mouse apoA-I and LDL receptor (LDL−/−, apoA-I−/−) (double knockout or DKO) were crossed>9 generations with mice transgenic for human FIN to obtain L159R apoA-I, LDLr−/−, ApoA-I−/− (FIN-DKO) mice. A similar cross was also performed with human wild-type (WT) apoA-I (WT-DKO). In addition, FIN-DKO and WT-DKO were crossed to obtain WT/FIN-DKO mice. To determine the effects of the apoA-I mutations on atherosclerosis, groups of each genotype were fed either chow or an atherogenic diet for 12weeks. Interestingly, the production of dysfunctional HDL-like particles occurred in DKO and FIN-DKO mice. These particles were distinct with respect to size, and their enrichment in apoE and cholesterol esters. Two-dimensional gel electrophoresis indicated that particles found in the plasma of FIN-DKO mice migrated as large α3-HDL. Atherosclerosis analysis showed that FIN-DKO mice developed the greatest extent of aortic cholesterol accumulation compared to all other genotypes, including DKO mice which lack any apoA-I. Taken together these data suggest that the presence of large apoE enriched HDL particles containing apoA-I L159R lack the normal cholesterol efflux promoting properties of HDL, rendering them dysfunctional and pro-atherogenic. In conclusion, large HDL-like particles containing apoE and apoA-IL159R contribute rather than protect against atherosclerosis, possibly through defective efflux properties and their potential for aggregation at their site of interaction in the aorta. 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).

Influence of C-terminal α-helix hydrophobicity and aromatic amino acid content on apolipoprotein A-I functionality

The apoA-I molecule adopts a two-domain tertiary structure and the properties of these domains modulate the ability to form HDL particles. Thus, human apoA-I differs from mouse apoA-I in that it can form smaller HDL particles; the C-terminal α-helix is important in this process and human apoA-I is unusual in containing aromatic amino acids in the non-polar face of this amphipathic α-helix. To understand the influence of these aromatic amino acids and the associated high hydrophobicity, apoA-I variants were engineered in which aliphatic amino acids were substituted with or without causing a decrease in overall hydrophobicity. The variants human apoA-I (F225L/F229A/Y236A) and apoA-I (F225L/F229L/A232L/Y236L) were compared to wild-type (WT) apoA-I for their abilities to (1) solubilize phospholipid vesicles and form HDL particles of different sizes, and (2) mediate cellular cholesterol efflux and create nascent HDL particles via ABCA1. The loss of aromatic residues and concomitant decrease in hydrophobicity in apoA-I (F225L/F229A/Y236A) has no effect on protein stability, but reduces by a factor of about three the catalytic efficiencies (Vmax/Km) of vesicle solubilization and cholesterol efflux; also, relatively large HDL particles are formed. With apoA-I (F225L/F229L/A232L/Y236L) where the hydrophobicity is restored by the presence of only leucine residues in the helix non-polar face, the catalytic efficiencies of vesicle solubilization and cholesterol efflux are similar to those of WT apoA-I; this variant forms smaller HDL particles. Overall, the results show that the hydrophobicity of the non-polar face of the C-terminal amphipathic α-helix plays a critical role in determining apoA-I functionality but aromatic amino acids are not required. 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).

LXR agonist increases apoE secretion from HepG2 spheroid, together with an increased production of VLDL and apoE-rich large HDL

BackgroundThe physiological regulation of hepatic apoE gene has not been clarified, although the expression of apoE in adipocytes and macrophages has been known to be regulated by LXR.Methods and ResultsWe investigated the effect of TO901317, a LXR agonist, on hepatic apoE production utilizing HepG2 cells cultured in spheroid form, known to be more differentiated than HepG2 cells in monolayer culture. Spheroid HepG2 cells were prepared in alginate-beads. The secretions of albumin, apoE and apoA-I from spheroid HepG2 cells were significantly increased compared to those from monolayer HepG2 cells, and these increases were accompanied by increased mRNA levels of apoE and apoA-I. Several nuclear receptors including LXRα also became abundant in nuclear fractions in spheroid HepG2 cells. Treatment with TO901317 significantly increased apoE protein secretion from spheroid HepG2 cells, which was also associated with the increased expression of apoE mRNA. Separation of the media with FPLC revealed that the production of apoE-rich large HDL particles were enhanced even at low concentration of TO901317, and at higher concentration of TO901317, production of VLDL particles increased as well.ConclusionsLXR activation enhanced the expression of hepatic apoE, together with the alteration of lipoprotein particles produced from the differentiated hepatocyte-derived cells. HepG2 spheroids might serve as a good model of well-differentiated human hepatocytes for future investigations of hepatic lipid metabolism.

Lipoprotein Subclass Abnormalities and Incident Hypertension in Initially Healthy Women

Abnormalities in traditional lipids, particularly decreased HDL cholesterol and increased triglycerides, can precede the onset of hypertension. Whether lipoprotein particle size or subclass concentrations play a role in the development of hypertension is unknown. We followed 17 527 initially healthy women without baseline hypertension prospectively for 8 years. At baseline, information regarding traditional lipids and hypertension risk factors was obtained, and lipoprotein size and subclass concentrations were measured by nuclear magnetic resonance spectroscopy. Baseline lipoprotein size and subclass concentrations were significantly associated with incident hypertension. Although LDL cholesterol was not associated with hypertension [odds ratio (OR) for quintile 5 vs 1: 1.08 (95% CI 0.96-1.20)], increased concentrations of LDL particles were associated with greater risk [OR 1.73 (1.54-1.95)], especially small LDL particles [OR 1.62 (1.45-1.83)]. Increased HDL cholesterol was associated with lower risk of hypertension [OR for quintile 5 vs 1: 0.79 (0.70-0.89)]. By contrast, increased concentrations of HDL particles had greater risk [OR 1.48 (1.32-1.67)], especially small HDL particles [OR 1.36 (1.22-1.53)], whereas large HDL particles had lower risk [OR 0.80 (0.71-0.90)]. Triglycerides and triglyceride-rich VLDL particles were positively associated with hypertension, with large VLDL particles associated with greater risk [OR 1.68 (1.50-1.89)]. Adding particle subclasses improved discrimination over a model with traditional lipids and risk factors (c-statistic 0.671 compared to 0.676; P < 0.001). In this study of initially healthy women, lipoprotein particle size and subclass concentrations were associated with incident hypertension and provided additive information to traditional lipids and risk factors.

Effects of 34 Risk Loci for Type 2 Diabetes or Hyperglycemia on Lipoprotein Subclasses and Their Composition in 6,580 Nondiabetic Finnish Men

OBJECTIVEWe investigated the effects of 34 genetic risk variants for hyperglycemia/type 2 diabetes on lipoprotein subclasses and particle composition in a large population-based cohort.RESEARCH DESIGN AND METHODSThe study included 6,580 nondiabetic Finnish men from the population-based Metabolic Syndrome in Men (METSIM) study (aged 57 ± 7 years; BMI 26.8 ± 3.7 kg/m2). Genotyping of 34 single nucleotide polymorphism (SNPs) for hyperglycemia/type 2 diabetes was performed. Proton nuclear magnetic resonance spectroscopy was used to measure particle concentrations of 14 lipoprotein subclasses and their composition in native serum samples.RESULTSThe glucose-increasing allele of rs780094 in GCKR was significantly associated with low concentrations of VLDL particles (independently of their size) and small LDL and was nominally associated with low concentrations of intermediate-density lipoprotein, all LDL subclasses, and high concentrations of very large and large HDL particles. The glucose-increasing allele of rs174550 in FADS1 was significantly associated with high concentrations of very large and large HDL particles and nominally associated with low concentrations of all VLDL particles. SNPs rs10923931 in NOTCH2 and rs757210 in HNF1B genes showed nominal or significant associations with several lipoprotein traits. The genetic risk score of 34 SNPs was not associated with any of the lipoprotein subclasses.CONCLUSIONSFour of the 34 risk loci for type 2 diabetes or hyperglycemia (GCKR, FADS1, NOTCH2, and HNF1B) were significantly associated with lipoprotein traits. A GCKR variant predominantly affected the concentration of VLDL, and the FADS1 variant affected very large and large HDL particles. Only a limited number of risk loci for hyperglycemia/type 2 diabetes significantly affect lipoprotein metabolism.

Hyperlycemia affects CVD risk by modulating cholesterol LDL and HDL lipoprotein distribution in Mexican‐American adults

To assess if CVD risk is associated with glucose and lipoprotein particle size in Mexican Americans, we randomly selected 80 overweight adults (age = 41.6±7.8 y; BMI = 32.2±7.1 kg/m2; LDL‐C = 112±31 mg/dL; HDL‐C = 35±11 mg/dL; fasting glucose [FG] = 101±38 mg/dL; 2‐hr glucose [2hGlu] = 154±70 mg/dL) from the Arizona Insulin Resistance Registry. HDL‐C was negatively correlated with FG (r = −0.38; p = 0.001) and 2hGlu (r = −0.30; p = 0.01). LDL‐C was positively correlated with FG (r = 0.26; p = 0.02) and 2hGlu (r = 0.40; p &lt; 0001). When stratified by FG, participants in the lowest quartile had a significantly lower percentage of cholesterol in smaller LDL particles (1.2±1.8 %) than those in the 3rd and 4th quartiles (6.1±4.3 % and 5.4±4.5 %, respectively; p = 0.004), with no differences in the amount of cholesterol in larger LDL particles. Participants in the lowest quartile of FG had the highest amount of HDL‐C in larger HDL particles (26.1±8.3 %) relative to the 3rd and 4th quartiles (17.7±6.6 % and 16.4±6.0 % respectively; p &lt; 0.001) and the least amount in smaller HDL particles (73.8±8.4 %) compared to the 3rd and 4th quartiles (82.3±6.4 % and 83.6±5.9 %, respectively; p = 0.002). Findings were similar when stratifying by 2hGlu. Thus, hyperglycemia may affect CVD risk by modulating cholesterol distribution in LDL and HDL particles in this population. Funded by ASU and the Health Research Alliance AZ/Arizona Insulin Resistance Registry.

Comparison of the effects of n-3 long chain polyunsaturated fatty acids and fenofibrate on markers of inflammation and vascular function, and on the serum lipoprotein profile in overweight and obese subjects

Background and aimsTo compare the effects of n-3 long chain polyunsaturated fatty acids (n-3 LCPUFA), with those of fenofibrate, on markers of inflammation and vascular function, and on the serum lipoprotein profile in overweight and obese subjects. Methods and resultsTwenty overweight and obese subjects participated in a randomized, double-blind, placebo-controlled intervention trial and received 3.7 g/d n-3 fatty acids (providing 1.7 g/d EPA and 1.2 g/d DHA), 200 mg fenofibrate or placebo treatment for 6 weeks separated by a 2 weeks wash-out period. Fish oil and fenofibrate treatment reduced triglyceride (−0.61 ± 0.81 mmol/L, P < 0.001, and −0.34 ± 0.85 mmol/L, P = 0.048, respectively) and increased HDL cholesterol concentrations (0.13 ± 0.21 mmol/L, P = 0.013, and 0.10 ± 0.18 mmol/L, P = 0.076), as reflected by a decrease of large very VLDL particles and increases of large HDL particles and medium size HDL particles. Fish oil increased serum LDL cholesterol concentrations (0.34 ± 0.59 mmol/L, P = 0.013). Fenofibrate reduced concentrations of soluble endothelial selectin (sE-selectin) (−4.1 ± 7.5 ng/mL, P = 0.032), but increased those of macrophage chemoattractant protein 1 (MCP1) (28 ± 55 ng/mL, P = 0.034). Fish oil had no effects on these markers. ConclusionAlthough n-3 LCPUFA and fenofibrate can both activate PPARα, they have differential effects on cardiovascular risk markers. In overweight and obese subjects fenofibrate (200 mg/d) or n-3 LCPUFA (3.7 g/d) treatment for 6 weeks did not improve markers for low-grade systemic inflammation, while fenofibrate had more profound effects on plasma lipids and markers for vascular activity compared to fish oil.Registration number clinical trials EudraCT 2006-005743-28.

HDL Measures, Particle Heterogeneity, Proposed Nomenclature, and Relation to Atherosclerotic Cardiovascular Events

A growing body of evidence from epidemiological data, animal studies, and clinical trials supports HDL as the next target to reduce residual cardiovascular risk in statin-treated, high-risk patients. For more than 3 decades, HDL cholesterol has been employed as the principal clinical measure of HDL and cardiovascular risk associated with low HDL-cholesterol concentrations. The physicochemical and functional heterogeneity of HDL present important challenges to investigators in the cardiovascular field who are seeking to identify more effective laboratory and clinical methods to develop a measurement method to quantify HDL that has predictive value in assessing cardiovascular risk. In this report, we critically evaluate the diverse physical and chemical methods that have been employed to characterize plasma HDL. To facilitate future characterization of HDL subfractions, we propose the development of a new nomenclature based on physical properties for the subfractions of HDL that includes very large HDL particles (VL-HDL), large HDL particles (L-HDL), medium HDL particles (M-HDL), small HDL particles (S-HDL), and very-small HDL particles (VS-HDL). This nomenclature also includes an entry for the pre-β-1 HDL subclass that participates in macrophage cholesterol efflux. We anticipate that adoption of a uniform nomenclature system for HDL subfractions that integrates terminology from several methods will enhance our ability not only to compare findings with different approaches for HDL fractionation, but also to assess the clinical effects of different agents that modulate HDL particle structure, metabolism, and function, and in turn, cardiovascular risk prediction within these HDL subfractions.

Algal Docosahexaenoic Acid Affects Plasma Lipoprotein Particle Size Distribution in Overweight and Obese Adults1–3

Fish oils containing both EPA and DHA have been shown to have beneficial cardiovascular effects, but less is known about the independent effects of DHA. This study was designed to examine the effects of DHA on plasma lipid and lipoprotein concentrations and other biomarkers of cardiovascular risk in the absence of weight loss. In this randomized, controlled, double-blind trial, 36 overweight or obese adults were treated with 2 g/d of algal DHA or placebo for 4.5 mo. Markers of cardiovascular risk were assessed before and after treatment. In the DHA-supplemented group, the decrease in mean VLDL particle size (P ≤ 0.001) and increases in mean LDL (P ≤ 0.001) and HDL (P ≤ 0.001) particle sizes were significantly greater than changes in the placebo group. DHA supplementation also increased the concentrations of large LDL (P ≤ 0.001) and large HDL particles (P = 0.001) and decreased the concentrations of small LDL (P = 0.009) and medium HDL particles (P = 0.001). As calculated using NMR-derived data, DHA supplementation reduced VLDL TG (P = 0.009) and total TG concentrations (P = 0.006). Plasma IL-10 increased with DHA supplementation to a greater extent than placebo (P = 0.021), but no other significant changes were observed in glucose metabolism, insulin sensitivity, blood pressure, or markers of inflammation with DHA. In summary, DHA supplementation resulted in potentially beneficial changes in some markers of cardiometabolic risk, whereas other markers were unchanged.

Efficacy and Safety of a Novel Oral Inducer of Apolipoprotein A-I Synthesis in Statin-Treated Patients With Stable Coronary Artery Disease: A Randomized Controlled Trial

The purpose of this study was to investigate the safety, tolerability, and efficacy of RVX-208, the first oral agent designed to enhance apolipoprotein (apo) A-I synthesis. No agent that selectively induces synthesis of apoA-I has reached an advanced stage of clinical development. A total of 299 statin-treated patients with coronary artery disease were treated with placebo or with RVX-208 at a dose of 50, 100, or 150 mg twice daily for 12 weeks. Changes in lipid-related biomarkers, in addition to safety and tolerability, of RVX-208 were investigated. For each dose of RVX-208, individual pairwise comparisons of apoA-I changes with placebo, the primary end point, did not achieve statistical significance. However, treatment with RVX-208 was associated with a dose-dependent increase in apoA-I levels by up to 5.6% (p = 0.035 for trend). Administration of RVX-208 resulted in significant increases in levels of high-density lipoprotein cholesterol (HDL-C) ranging from 3.2% to 8.3% (p = 0.02), and large HDL particles increased by 11.1% to 21.1% (p = 0.003). ApoA-I levels increased rapidly from 8 to 12 weeks, suggesting that peak pharmacological effect has not been achieved by the end of the 12-week study. Transient and reversible elevations in liver transaminases >3 times the upper limit of normal were observed in 18 patients treated with RVX-208, with no associated increase in bilirubin levels. Administration of RVX-208 for 12 weeks was associated with increases in apoA-I, HDL-C, and concentration of large HDL particles, consistent with facilitation of cholesterol mobilization. Maximal increases in apoA-I may require longer exposure. An increase in liver enzymes was observed with active treatment. (Clinical Trial for Dose Finding and Safety of RVX000222 in Subjects With Stable Coronary Artery Disease; NCT01058018).

Comparison of effects of diet versus exercise weight loss regimens on LDL and HDL particle size in obese adults

BackgroundObesity is associated with an atherogenic lipid profile characterized by a predominance of small LDL and HDL particles. Weight loss, by dietary restriction or exercise, increases LDL particle size. Whether these interventions can augment HDL size in conjunction with LDL size remains unknown.ObjectiveThis study compared the effects of alternate day fasting (ADF), calorie restriction (CR), and endurance exercise on LDL and HDL particle size in overweight and obese subjects.MethodsIn a 12-week parallel-arm trial, adult subjects (n = 60) were randomized to 1 of 4 groups: 1) ADF (75% energy restriction for 24-h alternated with ad libitum feeding for 24-h), 2) CR (25% energy restriction every day), 3) exercise (moderate intensity training 3 x/week), or 4) control.ResultsBody weight was reduced (P < 0.001) by ADF, CR, and exercise (5.2 ± 1.1%, 5.0 ± 1.4%, 5.1 ± 0.9%, respectively). Plasma LDL cholesterol decreased (P < 0.05) with ADF (10 ± 4%) and CR (8 ± 4%), whereas HDL cholesterol increased (P < 0.05) with exercise (16 ± 5%). Integrated LDL particle size was augmented (P = 0.01) by ADF and CR. The proportion of small LDL particles decreased (P = 0.04) with ADF only, and the proportion of large HDL particles increased (P = 0.03) with exercise only.ConclusionThese results indicate that dietary restriction increases LDL particle size, while endurance training augments HDL particle size, with minimal weight loss. None of these interventions concomitantly increased both LDL and HDL particle size, however.

Effects of smoking and smoking cessation on lipids and lipoproteins: Outcomes from a randomized clinical trial

the effects of smoking and smoking cessation on lipoproteins have not been studied in a large contemporary group of smokers. This study was designed to determine the effects of smoking cessation on lipoproteins. this was a 1-year, prospective, double-blind, randomized, placebo-controlled clinical trial of the effects of 5 smoking cessation pharmacotherapies. Fasting nuclear magnetic resonance spectroscopy lipoprotein profiles were obtained before and 1 year after the target smoking cessation date. The effects of smoking cessation and predictors of changes in lipoproteins after 1 year were identified by multivariable regression. the 1,504 current smokers were (mean [SD]) 45.4 (11.3) years old and smoked 21.4 (8.9) cigarettes per day at baseline. Of the 923 adult smokers who returned at 1 year, 334 (36.2%) had quit smoking. Despite gaining more weight (4.6 kg [5.7] vs 0.7 kg [5.1], P < .001], abstainers had increases in high-density lipoprotein cholesterol (HDL-C) (2.4 [8.3] vs 0.1 [8.8] mg/dL, P < .001), total HDL (1.0 [4.6] vs -0.3 micromol/L [5.0], P < .001), and large HDL (0.6 [2.2] vs 0.1 [2.1] micromol/L, P = .003) particles compared with continuing smokers. Significant changes in low-density lipoprotein (LDL) cholesterol and particles were not observed. After adjustment, abstinence from smoking (P < .001) was independently associated with increases in HDL-C and total HDL particles. These effects were stronger in women. despite weight gain, smoking cessation improved HDL-C, total HDL, and large HDL particles, especially in women. Smoking cessation did not affect LDL or LDL size. Increases in HDL may mediate part of the reduced cardiovascular disease risk observed after smoking cessation.