HDL Cholesterol Efflux Capacity Research Articles

Unravelling HDL-Looking beyond the Cholesterol Surface to the Quality Within.

High-density lipoprotein (HDL) particles have experienced a turbulent decade of falling from grace with widespread demotion from the most-sought-after therapeutic target to reverse cardiovascular disease (CVD), to mere biomarker status. HDL is slowly emerging from these dark times due to the HDL flux hypothesis wherein measures of HDL cholesterol efflux capacity (CEC) are better predictors of reduced CVD risk than static HDL-cholesterol (HDL-C) levels. HDL particles are emulsions of metabolites, lipids, protein, and microRNA (miR) built on the backbone of Apolipoprotein A1 (ApoA1) that are growing in their complexity due to the higher sensitivity of the respective “omic” technologies. Our understanding of particle composition has increased dramatically within this era and has exposed how our understanding of these particles to date has been oversimplified. Elucidation of the HDL proteome coupled with the identification of specific miRs on HDL have highlighted the “hormonal” characteristics of HDL in that it carries and delivers messages systemically. HDL can dock to most peripheral cells via its receptors, including SR-B1, ABCA1, and ABCG1, which may be a critical step for facilitating HDL-to-cell communication. The composition of HDL particles is, in turn, altered in numerous disease states including diabetes, auto-immune disease, and CVD. The consequence of changes in composition, however, on subsequent biological activities of HDL is currently poorly understood and this is an important avenue for the field to explore in the future. Improving HDL particle quality as opposed to HDL quantity may, in turn, prove a more beneficial investment to reduce CVD risk.

Theobromine Does Not Affect Fasting and Postprandial HDL Cholesterol Efflux Capacity, While It Decreases Fasting miR-92a Levels in Humans.

ScopeChocolate consumption lowers cardiovascular disease risk, which might be attributed to the methylxanthine theobromine. These effects may be mediated through effects on HDL‐mediated cholesterol efflux, which may be affected by microRNA (miRNA) levels in the HDL particles. Therefore, the aim of this study is to investigate effects of theobromine consumption on fasting and postprandial cholesterol efflux and miRNAs levels.Methods and resultsThirty overweight and 14 obese healthy men and women participated in this randomized, double‐blind crossover study. Participants consumed 500 mg d−1 of theobromine or placebo for 4 weeks. ABCA1‐mediated cholesterol efflux was measured using J774 macrophages. MiRNAs levels (miR‐92a, miR‐223, miR‐135a*) were quantified in apolipoprotein B‐depleted serum. Theobromine consumption did not affect fasting and postprandial cholesterol efflux. Fasting miR‐223 and miR‐135a levels were unchanged, while miR‐92a levels were decreased (−0.21; p < 0.05). The high‐fat meal increased postprandial cholesterol efflux capacity (+4.3 percentage points; p ≤ 0.001), miR‐92a (+1.21; p < 0.001), and miR‐223 (+1.79; p < 0.001) levels, while a trend was found for miR‐135a (+1.08; p = 0.06).ConclusionTheobromine did not improve fasting and postprandial ABCA1‐mediated cholesterol efflux capacity, but decreased fasting miR‐92a levels. High‐fat meal intake increased postprandial cholesterol efflux and the three selected miRNAs levels.

Longitudinal Changes in Cholesterol Efflux Capacities in Patients With Coronary Artery Disease Undergoing Lifestyle Modification Therapy.

BackgroundOur objective was to identify the determinants of high‐density lipoprotein cholesterol efflux capacity (HDL‐CEC) changes in patients with coronary artery disease who participated in a lifestyle modification program aimed at increasing physical activity levels and improving diet quality.Methods and ResultsA total of 86 men with coronary artery disease aged between 35 and 80 years participated in a 1‐year lifestyle modification program that aimed to achieve a minimum of 150 minutes of aerobic physical activity weekly and improve diet quality. HDL‐CECs were measured before and after the 1‐year intervention using 3H‐cholesterol–labeled J774 and HepG2 cells. Visceral, subcutaneous, and cardiac adipose tissue levels were assessed before and after the intervention using magnetic resonance imaging. Lipoprotein particle size and concentrations were measured by proton nuclear magnetic resonance spectroscopy and a complete lipoprotein‐lipid profile was obtained. At baseline, the best correlate of HDL‐CECs were apolipoprotein AI (R 2=0.35, P<0.0001) and high‐density lipoprotein cholesterol (R 2=0.21, P<0.0001) for J774‐HDL‐CECs and HepG2‐HDL‐CECs, respectively. Baseline and longitudinal changes in HDL‐CECs were associated with several lipoprotein size and concentration indices, although high‐density lipoprotein cholesterol was the best predictor of longitudinal changes in J774‐HDL‐CECs (R 2=0.18, P=0.002) and apolipoprotein AI was found to be the best predictor of longitudinal changes in HepG2 cholesterol efflux capacities (R 2=0.21, P=0.002).ConclusionsResults of this study suggest that increases in high‐density lipoprotein cholesterol and apolipoprotein AI levels typically observed in patients with coronary artery disease undergoing healthy lifestyle modification therapy may be indicative of higher plasma concentrations of functional high‐density lipoprotein particles.

Vitamin D replacement ameliorates serum lipoprotein functions, adipokine profile and subclinical atherosclerosis in pre-menopausal women

Background and aimsLow vitamin D (vitD) has been linked to increased cardiovascular (CV) risk, but the effects of vitD supplementation are not clarified. We evaluated the impact of vitD normalization on HDL cholesterol efflux capacity (CEC), which inversely correlates with CV risk, the proatherogenic serum cholesterol loading capacity (CLC), adipokine profile and subclinical atherosclerosis. Methods and resultsHealthy premenopausal women with vitD deficiency (n = 31) underwent supplementation. Subclinical atherosclerosis was evaluated by flow-mediated dilation (FMD), pulse wave velocity (PWV) and augmentation index (AIx), measured with standard techniques. HDL CEC and serum CLC were measured by a radioisotopic and fluorimetric assay, respectively. Malondialdehyde (MDA) in HDL was quantified by the TBARS assay. Pre-β HDL was assessed by 2D-electrophoresis. Serum adipokines were measured by ELISA.VitD replacement restored normal levels of serum 25-hydroxyvitamin D (25OHD) and significantly improved FMD (+4%; p < 0.001), PWV (−4.1%: p < 0.001) and AIx (−16.1%; p < 0.001). Total CEC was significantly improved (+19.5%; p = 0.003), with a specific increase in the ABCA1-mediated CEC (+70.8%; p < 0.001). HDL-MDA slightly but significantly decreased (−9.6%; p = 0.027), while no difference was detected in pre-β HDL. No change was observed in aqueous diffusion nor in the ABCG1-mediated CEC. Serum CLC was significantly reduced (−13.3%; p = 0.026). Levels of adiponectin were increased (+50.6%; p < 0.0001) and resistin levels were decreased (−24.3%; p < 0.0001). After vitD replacement, an inverse relationship was found linking the ABCA1-mediated CEC with pre-β HDL (r2 = 0.346; p < 0.001) and resistin (r2 = 0.220; p = 0.009). ConclusionOur data support vitD supplementation for CV risk prevention.

Abstract 388: High-density Lipoprotein Cholesterol Efflux Capacity is not associated with Atherosclerosis and Cardiovascular Events: the CODAM Study

Cholesterol Efflux Capacity (CEC) is considered to be a key atheroprotective property of high-density lipoproteins (HDL). However, its role in atherosclerosis risk is still controversial. In this study, we have analyzed the relationship between HDL CEC and atherosclerosis surrogates (carotid intima media thickness (cIMT), endothelial dysfunction (EnD); Z-Scores) in a well-characterized clinical population in the Cohort of Diabetes and Atherosclerosis Maastricht (CODAM) study, which consists of 574 individuals (age 59.6±0.3yrs, 61.3% men, 24.4% T2DM). Multiple linear regression analyses were performed to identify the associations in baseline data between HDL CEC (%), plasma HDL cholesterol (HDL-C, mmol/L), HDL size (nm), apoprotein A1 (ApoA1, g/L), and HDL Particle Concentration (HDL-P, nmol/L (LN), by NMR) with cIMT and EnD. Logistic regression analyses were done to identify the association of the above-mentioned HDL characteristics and CV events (CVE; N=499, 80 CVE cases). Analyses were adjusted for lifestyle, medication and metabolic confounders. The results show that HDL-C (ß=-0.65, 95%CI -0.91; -0.42), HDL size (ß=-0.57, 95%CI -0.98; -0.15), apoA1 (ß=-0.65, 96%CI -1.01; -0.29), and HDL-P (ß=-0.77, 95%CI -1.47; -0.11) were inversely associated with EnD (N=532), whereas HDL CEC was not (ß=-0.03, 95%CI=-0.24;0.24). Interestingly, preliminary analyses show that these associations are lost in diabetic subjects (N=131), but not in non-diabetics (N=401). An inverse association also exists between HDL-C, HDL size, apoA1, and HDL-P with cIMT (N=494), which was not statistically significant likely due to variability and relative insensitivity of cIMT measurements. Further, a 1 unit increase of HDL-C was associated with ~4fold lower prevalence of CVE (OR=0.25, 95%CI 0.08;0.83), and for HDL-P, with ~20fold less CVE (OR=0.05, 95%CI 0.00;0.70), but no association was found between HDL CEC and CVE (OR=1.26, 95%CI 0.41;3.84). Our results show that certain HDL-related parameters have atheroprotective associations, but HDL-CEC is not one of them. This result agrees with, but differs from, some other studies, and might reflect population differences in the relationships between measurements of HDL lipids/particle number, and HDL CEC.

Abstract 135: Sterol Efflux Function and HDL Associated APOF Levels Associate with Recovery from Stroke

Background: Prospective cohort studies and meta-analyses examining the relationship between HDL-cholesterol (C) and stroke risk are discordant and question the value of HDL-C as a marker for stroke risk prediction. Changes in HDL-C protein composition and function after acute ischemic stroke, and their relationship to stroke recovery have not been studied. We investigated changes in HDL cholesterol efflux capacity (CEC) and proteome in response to acute ischemic stroke, and their correlation with long-term functional recovery after stroke. Methods: Plasma samples were collected from stroke patients either at 24 (early, N = 35) or 96 hours (late, N = 20) after stroke onset, in addition to age matched healthy controls (N = 35). Samples were analyzed for HDL proteome using mass spectrometry, and CEC using three independent assays for macrophage-, ABCA1- and ABCG1-dependent efflux. Stroke recovery was assessed at 3 months after stroke using the Modified Rankin Scores (MRS) and the NIH Stroke Scale (NIHSS). Results: Both macrophage- and ABCG1-mediated CEC were reduced by 50% ( P &lt;0.0001) and 20% ( P &lt;0.038) in early and late post stroke samples, respectively, compared to the control group. Patients who had comparable or increased CEC between the two-time points had lower NIHSS and MRS indicating better recovery. Proteomic analysis of HDL indicated a distinct time-dependent remodeling post stroke. Coagulation complement cascade proteins (FGB, FGA, A2M, C3) significantly increased (FDR&gt;0.01) early and returned to control levels later, inflammation proteins (SAA1, SAA2, PON1, C4B) increased early and continued to increase. Interestingly, platelet adhesion proteins (DSG1, JUP, ITGB1, ITGA2, TUBB, DNAH3, PF4) were abundantly present in only later samples. Finally, apolipoprotein F (APOF) levels were 2 fold increased at 96 hour when compared to 24hour time points. APOF positively and significantly correlated with NIHSS (r=0.72, P=0.031) Conclusion: 1) Patients with acute ischemic stroke who maintain or improve HDL CEC post stroke exhibit better recovery scores, 2) Post stroke HDL proteome remodeling is dynamic with distinct time-dependent protein signatures among which APOF correlates positively and strongly with stroke recovery.

Abstract 553: Scavenging Reactive Aldehydes With 5'-o-pentyl-pyridoxamine (PPM) Improves HDL Function and Reduces Atherosclerosis in Ldlr Deficient Mice

Background: Lipid peroxidation products impair the cholesterol efflux capacity of high-density lipoprotein (HDL) and contribute to the development of atherosclerosis. The effect of inhibition of HDL dysfunction by scavengers on HDL function and whether scavenging reactive aldehydes with PPM protects against the development of atherosclerosis was examined. Methods and Results: HDL of familial hypercholesterolemia (FH) subjects have impaired ability to promote cholesterol efflux and FH-HDL contain 5-fold more malondialdehyde adducts (MDA) than control HDL. In vitro studies revealed that reactive aldehyde MDA crosslinks apolipoprotein AI (apoAI) and impairs the ability of HDL to promote cholesterol efflux from Apoe -/- macrophages. 5'-O-pentyl-pyridoxamine (PPM), a potent scavenger of reactive aldehydes, abolished MDA-mediated crosslinking of apoA-I in HDL by 80 % (P&lt;0.05). PPM prevents the reduction in cholesterol efflux capacity of MDA treated HDL in Apoe-/- macrophages. Furthermore, PPM significantly improved the cholesterol efflux capacity of HDL from Ldlr -/- mice fed a Western diet (WD) for 16 weeks (P&lt;0.05), indicating that PPM protects HDL from modifications by reactive aldehydes and maintains HDL function in vivo. Importantly, administration of 1 mg/mL of the reactive aldehyde scavenger PPM, versus 1 mg/mL of the nonreactive analogue PPO, to Ldlr -/- mice consuming a WD for 16 weeks reduced the extent of proximal aortic atherosclerosis by 45% (P&lt;0.05). Immunohistochemistry studies revealed that PPM reduced the macrophage content and the number of TUNEL positive cells by 55% (P&lt;0.05) and by 60% (P&lt;0.01) in advanced atherosclerotic lesions of Ldlr -/- mice, respectively. In addition, the necrotic core area was reduced by 52% (P&lt;0.05) in advanced atherosclerotic lesions in Ldlr -/- mice treated with PPM compared to the control group. Conclusions: Treatment with PPM, a reactive aldehyde scavenger: 1) inhibits MDA-ApoA1 adduct formation thereby preserving HDL cholesterol efflux capacity in Ldlr -/- mice; 2) reduces the number of apoptotic cells in atherosclerotic lesions and the necrotic core area in lesions of Ldlr -/- mice. These results support the therapeutic potential of PPM in the treatment of atherosclerotic cardiovascular disease.

Sex steroids mediate discrete effects on HDL cholesterol efflux capacity and particle concentration in healthy men

Exogenous testosterone decreases serum concentrations of high-density lipoprotein cholesterol (HDL-C) in men, but whether this alters cardiovascular risk is uncertain. To investigate the effects of testosterone and estradiol on HDL particle concentration (HDL-Pima) and metrics of HDL function. We enrolled 53 healthy men, 19 to 55years of age, in a double-blinded, placebo-controlled, randomized trial. Subjects were rendered medically castrate using the GnRH receptor antagonist acyline and administered either (1) placebo gel, (2) low-dose transdermal testosterone gel (1.62%, 1.25g), (3) full replacement dose testosterone gel (1.62%, 5g) or (4) full replacement dose testosterone gel together with an aromatase inhibitor for 4weeks. At baseline and end of treatment, serum HDL total macrophage and ABCA1-specific cholesterol efflux capacity (CEC), HDL-Pima and size, and HDL protein composition were determined. Significant differences in serum HDL-C were observed with treatment across groups (P=.01 in overall repeated measures ANOVA), with increases in HDL-C seen after both complete and partial testosterone deprivation. Medical castration increased total HDL-Pima (median [interquartile range] 19.1 [1.8] nmol/L at baseline vs 21.3 [3.1] nmol/L at week 4, P=.006). However, corresponding changes in total macrophage CEC and ABCA1-specific CEC were not observed. Change in serum 17β-estradiol concentration correlated with change in total macrophage CEC (β=0.33 per 10 pg/mL change in serum 17β-estradiol, P=.03). Testosterone deprivation in healthy men leads to a dissociation between changes in serum HDL-C and HDL CEC. Changes in serum HDL-C specifically due to testosterone exposure may not reflect changes in HDL function.

HDL cholesterol efflux capacity and cholesteryl ester transfer are associated with body mass, but are not changed by diet-induced weight loss: A randomized trial in abdominally obese men

Background and aimsObesity is associated with a lower HDL-mediated cholesterol efflux from macrophages and a higher CETP (cholesteryl ester transfer protein) activity, but effects of weight loss are not clear. In addition, associations with visceral and subcutaneous adipose tissue are not known. We therefore investigated effects of diet-induced weight loss on HDL-mediated cholesterol efflux and cholesterol ester (CE) transfer in abdominally obese men. Differences between normal-weight and abdominally obese men were also examined. MethodsTwenty-five apparently healthy, normal-weight men (waist circumference: <94 cm) and 52 abdominally obese men (waist circumference: 102–110 cm) were included. Abdominally obese subjects were randomly allocated to a dietary weight-loss intervention group or a no–weight loss control group. Individuals from the intervention group followed a very-low-calorie diet for 6 weeks to obtain a waist circumference below 102 cm, followed by a 2-week weight-stable period. Cholesterol efflux was measured in BODIPY-labeled murine J774 macrophages. CE transfer was measured by quantifying the transfer of CE from radiolabeled exogenous HDL to apoB-containing lipoproteins. ResultsCholesterol efflux capacity was 9 percentage point (pp) lower in abdominally obese than in normal-weight men (p≤0.001), while CE transfer was 5 pp higher (p≤0.01). Diet-induced weight-loss of 10.3 kg did not change cholesterol efflux and CE transfer. In addition, stepwise regression analysis did not suggest that the different fat depots are differently related to efflux capacity and CE transfer. ConclusionsAfter a 2-week weight-stable period, dietary weight loss of 10 kg did not improve ABCA1-mediated cholesterol efflux and CE transfer in abdominally obese men.

Cholesterol efflux in the transplant patient.

Cholesterol metabolism is increasingly recognized in inflammatory diseases including transplantation. This review discusses the mechanistic underpinnings that tie macrophage cholesterol efflux capacity (CEC) of high-density lipoprotein (HDL) to chronic rejection in transplanted patients. Animal studies suggest that administration of apolipoprotein A-I, the main protein constituent of HDL, can prevent transplant arteriosclerosis. apoA-I administration increases CEC of HDL. In patients with cardiac allograft vasculopathy (CAV), decreased CEC has been associated with poorer survival. In addition, reduced CEC in recipients, pretransplant, has been associated with the development of CAV and renal allograft survival. These recent findings raise the hypothesis that increasing cholesterol efflux may prevent chronic rejection and improve allograft survival after transplant. Reconstituted HDL significantly increases CEC and is currently in clinical development for traditional atherosclerosis. Clinical trials of reconstituted HDL administration in transplantation should be performed.

High-density lipoprotein (HDL) functionality and its relevance to atherosclerotic cardiovascular disease.

Several prospective epidemiological studies have shown that there is a clear inverse relationship between serum high-density lipoprotein-cholesterol (HDL-C) concentrations and risk for coronary heart disease (CHD), even at low-density lipoprotein-cholesterol (LDL-C) levels below 70 mg/dL. However, more recent evidence from genetic studies and clinical research has come to challenge the long-standing notion that higher HDL-C levels are always beneficial, while lower HDL-C levels are always detrimental. Thus, it becomes apparent that HDL functionality plays a much more important role in atheroprotection than circulating HDL-C levels. HDL cholesterol efflux capacity (CEC) from macrophages is a key metric of HDL functionality and exhibits a strong inverse association with both carotid intima-media thickness and the likelihood of angiographic coronary artery disease (CAD), independent of the HDL-C level. Thus, extensive research is being conducted to identify new agents with a favorable side effect profile, which would be able to enhance CEC, improve HDL functionality and potentially decrease cardiovascular risk. This review aims to present and discuss the current clinical and scientific evidence pertaining to the significance of HDL functionality over the actual HDL-C concentration in mediating the favorable effects on the cardiovascular system. Thus, we conducted a PubMed search until December 2017 through the English literature using the search terms ‘HDL function/functionality’, ‘HDL properties’, ‘cardiovascular risk’ and ‘cholesterol efflux capacity’. We also included references from the articles identified and publications available in the authors’ libraries.

Association of cholesterol efflux capacity with plasmalogen levels of high-density lipoprotein: A cross-sectional study in chronic kidney disease patients

Background and aimCurrent research suggests that dysfunctional high-density lipoprotein (HDL) with low cholesterol efflux capacity may accelerate atherosclerosis, particularly in chronic kidney disease (CKD). We previously reported that serum levels of plasmalogens closely correlated with HDL concentration, and could serve as a novel biomarker for atherosclerosis. In the present study, we analyzed the association of cholesterol efflux capacity of HDL with clinical and biochemical parameters, including plasmalogens, in CKD patients. MethodsWe enrolled 24 mild-to-moderate CKD patients (CKD-3-4) and 33 end-stage renal disease (ESRD) patients nearing hemodialysis (CKD-5), and assessed physiological atherosclerotic scores, cholesterol efflux capacity, and plasmalogens levels in HDL. Furthermore, the effect of plasmalogen on cholesterol efflux capacity of HDL was examined by in vitro studies with re-constituted HDL (rHDL) and HDL prepared from CKD-5 patient (ESRD-HDL) with additional phospholipids. ResultsThere were significant differences in many parameters between the two groups. In particular, plasmalogens levels and cholesterol efflux capacity of HDL were significantly reduced in the CKD-5 group compared to those in the CKD-3-4 group (-35.1%, p < 0.001, -36.8%, p < 0.001, respectively). Multivariate linear regression analyses revealed that ethanolamine plasmalogen levels of HDL were independently associated with cholesterol efflux capacity (p = 0.045) and plaque scores (p = 0.035). In vitro studies also indicated that additional plasmalogens augmented cholesterol efflux ability of HDL. ConclusionsHigh plasmalogens concentrations in HDL may correlate with acceleration of cholesterol efflux and their decreased levels may promote atherosclerosis in advanced CKD patients.

High-Density Lipoprotein Function in Cardiovascular Disease and Diabetes Mellitus.

Cardiovascular disease (CVD) is the most common cause of death worldwide.1 Major CVD risk factors are hypertension, smoking, physical inactivity, abnormal glucose levels/diabetes mellitus, and dyslipidemia. Among these, dyslipidemia characterized by a low level of HDL-C (high-density lipoprotein cholesterol) is strongly and inversely correlated with CVD risk,2–4 and low HDL-C levels is part of the atherogenic dyslipidemia complex associated with diabetes mellitus.5 These observations triggered intense interest in increasing HDL-C levels for therapeutic intervention of CVD.6,7 However, several recent lines of evidence now suggest that the association between HDL-C levels and CVD status may be indirect or more complicated than previously recognized.7 Thus, human genetic studies demonstrate that genetically altered HDL-C levels do not necessarily translate to an altered risk of CVD.8–12 Phase III clinical trials of drugs that elevate HDL-C, such as niacin and CETP (cholesteryl ester transfer protein) inhibitors, also have largely failed to reduce CVD events in statin-treated subjects with established CVD.13–15 For several CETP inhibitors, improvement in CVD prevention was unsuccessful because of off-target effects (torcetrapib) or lack of efficacy (dalcetrapib and evacetrapib).14,16–18 The exception is the recent REVEAL trial (Randomized Evaluation of the Effects of Anacetrapib Through Lipid-Modification), which included more subjects and was performed for longer than previous CETP inhibitor trials. The REVEAL demonstrated that the CETP inhibitor anacetrapib exhibited beneficial effects on cardiovascular outcomes on top of those of statin therapy, although the risk reduction was moderate19,20 and might have been due, at least in part, to a reduction in non-HDL-C rather than elevated HDL-C.21 Considering these cumulative observations, it remains uncertain whether increased HDL-C directly impacts atherosclerosis and the …

Genetic Insights of Cholesterol and Atherosclerosis: Complex Biology

Atherosclerosis is multifaceted arterial disease involving collaboration of chromosomal and conservational factors, around seven million Americans are experiencing a heart attack during their lifetime. Many biomolecules play different roles in atherosclerosis such as 5-LO enzyme which play vital role in synthesis of leukotrienes inflammatory intermediates and proteins. Previous studies show that individuals suffering from coronary artery disease more commonly have C. pneumonia antibody than inhabitant’s controls. In recent years the genes and genetic polymorphism which are associated with atherosclerosis had been identified. Phospholipid transfer protein will subsequently decrease the HDL mass and cholesterol efflux capacity due to its overexpression and deletation. Our aim of this review is to demonstrate complex biology of atherosclerosis and effect of cholesterol in cardiovascular diseases.

Improving of HDL capacity for macrophages cholesterol efflux after plasma incubation with phospholipid nanoparticles

In connection with recent data about antiatherogenic importance of not only plasma HDL concentration, but of their cell cholesterol efflux capacity as well, the possibility of its correction by phospholipid (PL) nanoparticles was studied. Blood plasma was incubated with earlier elaborated PL nanoparticles emulsion with the particle diameter up to 30 nm, and HDL cholesterol efflux capacity of apo B-depleted plasma was studied. Using macrophages THP-1 preloaded 3H-cholesterol were used. The addition of incubated plasma supernatants with the elevated PL/apo A-1 ratio to cell media resulted in almost increase in two fold 3H-cholesterol efflux as compared with native HDL. The maximal efflux was observed at the PL/apo A-1 ratio of 1.06 as compared with native apo B-depleted plasma (the PL/apo A-1 ratio of 0.85). Results suggest possible usage of ultrasmall PL nanoparticles for regeneration of impaired antiatherogenic HDL functionality. This approach seems to be predominant compared with the usage of PL emulsions with detergent or apoprotein A1.

Weight Loss and Exercise Alter the High-Density Lipoprotein Lipidome and Improve High-Density Lipoprotein Functionality in Metabolic Syndrome.

High-density lipoprotein (HDL) lipid composition and function may better reflect cardiovascular risk than HDL cholesterol concentration. This study characterized the relationships between HDL composition, metabolism, and function in metabolic syndrome (MetS) patients and how changes in composition after weight loss (WL) and exercise treatments are related to function. Plasma samples from MetS patients (n=95) and healthy individuals (n=40) were used in this study. Subsets of the MetS group underwent 12 weeks of no treatment (n=17), WL (n=19), or WL plus exercise (WLEX; n=17). HDL was isolated using density-gradient ultracentrifugation. The HDL lipidome was analyzed by mass spectrometry, and particle size determined by nuclear magnetic resonance. Cholesteryl ester transfer protein activity and ex vivo HDL cholesterol efflux capacity (CEC) were assessed. The HDL lipidome in the MetS patients was substantially different from that in healthy individuals, mean particle size was smaller, and CEC was lower. Several HDL phospholipid and sphingolipid species were associated with HDL diameter and CEC. The HDL lipidome and particle size were modified toward the healthy individuals after WL and WLEX treatments, with greater effects observed in the latter group. Cholesteryl ester transfer protein activity was reduced after WL and WLEX, and CEC was improved after WLEX. WLEX treatment in MetS patients normalizes the HDL lipidome and particle size profile and enhances CEC. HDL lipids associated with diminished CEC may represent novel biomarkers for early prediction of HDL dysfunction and disease risk and may represent potential therapeutic targets for future HDL therapies. URL: http://www.clinicaltrials.gov. Unique identifier: NCT00163943.

High-density lipoprotein cholesterol efflux capacity is inversely associated with cardiovascular risk: a systematic review and meta-analysis

BackgroundA low plasma level of high-density lipoprotein (HDL) cholesterol (HDL-C) is associated with cardiovascular risk. A key cardioprotective property of HDL is cholesterol efflux capacity (CEC), the ability of HDL to accept cholesterol from macrophages. In this study, we aimed to identify the predictive value of CEC for cardiovascular risk.MethodsThe relative risks (RRs) and 95% confidence intervals (CIs) were pooled to analyze the association between CEC and the incidence of cardiovascular events and all-cause mortality. The odds ratios (ORs) and 95% CIs were pooled to estimate the association of CEC and the prevalence of cardiovascular events.ResultsA total of 15 studies were included. Results showed that the highest CEC was significantly associated with a reduced risk of cardiovascular events incidents compared to the lowest CEC (RR, 0.56; 95% CI, 0.37 to 0.85; I2, 89%); the pooled RR of cardiovascular risk for per unit SD increase was 0.87 (95% CI, 0.73 to 1.04; I2, 67%). Dose-response curve indicated that cardiovascular risk decreased by 39% (RR, 0.61; 95% CI, 0.51 to 0.74) for per unit CEC increase. Similarly, an inverse association was observed between CEC and the prevalence of cardiovascular events (highest vs. lowest, OR, 0.30; 95% CI, 0.17 to 0.5; I2 = 63%; per unit SD increase, OR, 0.94; 95% CI, 0.90 to 0.98; I2 = 71%). However, based on the current data, CEC was not significantly associated with all-cause mortality.ConclusionsFindings from this meta-analysis suggest that HDL-mediated CEC is inversely associated with cardiovascular risk, which appears to be independent of HDL concentration. The growing understanding of CEC and its role in cardiovascular risk decrease may improve the accuracy of cardiovascular risk prediction and also open important avenues to develop novel therapeutic targeting HDL metabolism.

HDL structure and function is profoundly affected when stored frozen in the absence of cryoprotectants

Analysis of structural and functional parameters of HDL has gained significant momentum in recent years because they are stronger predictors of cardiovascular risk than HDL-cholesterol levels. Surprisingly, in most HDL studies, very low attention is paid to HDL storage, which might critically affect functional properties. In the present study, we systematically examined the impact of storage and freezing on the structural/functional properties of freshly isolated HDL. Initial damage to HDL starts between week 1 and week 4 of storage. We observed that prolonged freezing at −20°C or −70°C led to a shedding of apoA-I from HDL and to the formation of large protein-poor particles, indicating that HDL is irreversibly disrupted. These structural alterations profoundly affected key metrics of HDL function, including HDL-cholesterol efflux capacity and HDL paraoxonase activity. Flash-freezing of isolated HDL prior to storage at −70°C did not preserve HDL structure. However, addition of the cryoprotectants, sucrose or glycerol, completely preserved structure and function of HDL when stored for at least 2 years. Our data clearly indicate that HDL is a complex particle requiring special attention when stored. Addition of cryoprotectants to isolated HDL samples before storage will make biochemical and clinical HDL research studies more reproducible and comparable.

Determinants of HDL Cholesterol Efflux Capacity after Virgin Olive Oil Ingestion: Interrelationships with Fluidity of HDL Monolayer.

Cholesterol efflux capacity of HDL (CEC) is inversely associated with cardiovascular risk. HDL composition, fluidity, oxidation, and size are related with CEC. We aimed to assess which HDL parameters were CEC determinants after virgin olive oil (VOO) ingestion. Post-hoc analyses from the VOHF study, a crossover intervention with three types of VOO. We assessed the relationship of 3-week changes in HDL-related variables after intervention periods with independence of the type of VOO. After univariate analyses, mixed linear models were fitted with variables related with CEC and fluidity. Fluidity and Apolipoprotein (Apo)A-I content in HDL was directly associated, and HDL oxidative status inversely, with CEC. A reduction in free cholesterol, an increase in triglycerides in HDL, and a decrease in small HDL particle number or an increase in HDL mean size, were associated to HDL fluidity. HDL fluidity, ApoA-I concentration, and oxidative status are major determinants for CEC after VOO. The impact on CEC of changes in free cholesterol and triglycerides in HDL, and those of small HDL or HDL mean size, could be mechanistically linked through HDL fluidity. Our work points out novel therapeutic targets to improve HDL functionality in humans through nutritional or pharmacological interventions.

Impact of Endothelial Lipase on Cholesterol Efflux Capacity of Serum and High-density Lipoprotein

Endothelial lipase (EL) is a potent modulator of the structural and functional properties of HDL. Impact of EL on cholesterol efflux capacity (CEC) of serum and isolated HDL is not well understood and apparently contradictory data were published. Here, we systematically examined the impact of EL on composition and CEC of serum and isolated HDL, in vitro and in vivo, using EL-overexpressing cells and EL-overexpressing mice. CEC was examined in a validated assay using 3H-cholesterol labelled J774 macrophages. In vitro EL-modification of serum resulted in complex alterations, including enrichment of serum with lipid-free/-poor apoA-I, decreased size of human (but not mouse) HDL and altered HDL lipid composition. EL-modification of serum increased CEC, in line with increased lipid-free/-poor apoA-I formation. In contrast, CEC of isolated HDL was decreased likely through altered lipid composition. In contrast to in vitro results, EL-overexpression in mice markedly decreased HDL-cholesterol and apolipoprotein A-I serum levels associated with a decreased CEC of serum. HDL lipid composition was altered, but HDL particle size and CEC were not affected. Our study highlights the multiple and complex effects of EL on HDL composition and function and may help to clarify the seemingly contradictory data found in published articles.