Effect of a Multifactorial Weight Loss Intervention on HDL Cholesterol Efflux Capacity and Immunosenescence: A Randomized Controlled Trial

OBJECTIVE

Life expectancy and obesity prevalence are increasing worldwide, leading to an increase in the prevalence of cardiovascular disease. High-density lipoprotein (HDL) functionality and immunosenescence play key roles in cardiovascular disease, longevity, and quality of aging. Both molecular hallmarks of aging are impacted by obesity and metabolic syndrome and can be modulated by lifestyle. We aimed to evaluate the effect of a lifestyle intervention focused on an energy-reduced Mediterranean diet (erMedDiet), physical activity (PA), and behavioral support on HDL cholesterol efflux capacity (CEC) and immunosenescence.

METHOD

CEC and immunosenescent T cells were determined in 60 participants from the control group (CG) and 56 from the intervention group (IG) of the PREDIMED-Plus trial at baseline and after 1 and 3 years of follow-up. PREDIMED-Plus is a randomized, controlled, parallel-group trial with an IG of erMedDiet, PA promotion, and behavioral support for weight loss and a CG of usual primary care advice. The sample included 116 volunteers from the PREDIMED-Plus-IMDEA subsample of the PREDIMED-Plus trial. Men aged 55 to 75 years and women aged 60 to 75 years with a body mass index between 27 and 40 kg/m2 and metabolic syndrome were included.

RESULTS

Participants within the IG had significantly improved CEC (2.42% and 10.69% after 1 and 3 years of follow-up) and a decreased in senescent T cell profile (-3.32% ± 12.54% and -6.74% ± 11.2%, p < 0.001, after 1 and 3 years of follow-up). Baseline obesity status impacted the response to the intervention.

CONCLUSIONS

A weight loss intervention program with erMedDiet and PA ameliorated senescence markers.

Effect of Thrombolysis on Circulating Microparticles in Patients with ST-Segment Elevation Myocardial Infarction

Objective

We demonstrated that circulating microparticles (MPs) are increased in patients with coronary heart disease (both chronic coronary syndrome (CCS) and acute coronary syndrome). Whether thrombolysis affects MPs in patients with ST-segment elevation myocardial infarction (STEMI) with or without percutaneous coronary intervention (PCI) is unknown.

Methods

This study was divided into three groups: STEMI patients with thrombolysis (n = 18) were group T, patients with chronic coronary syndrome (n = 20) were group CCS, and healthy volunteers (n = 20) were the control group. Fasting venous blood was extracted from patients in the CCS and control groups, and venous blood was extracted from patients in the T group before (pre-T) and 2 hours after (post-T) thrombolysis. MPs from each group were obtained by centrifugation. After determining the concentration, the effects of MPs on endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) in rat myocardial tissue in vitro were detected by immunohistochemistry and western blotting. Changes in nitric oxide (NO) and oxygen free radicals (O2•-) were also detected. The effect of MPs on vasodilation in isolated rat thoracic aortae was detected.

Results

Compared with that in the control group (2.60 ± 0.38 mg/ml), the concentration of MPs was increased in patients with CCS (3.49 ± 0.72 mg/ml) and in STEMI patients before thrombolysis (4.17 ± 0.58 mg/ml). However, thrombolysis did not further increase MP levels (post-T, 4.23 ± 1.01 mg/ml) compared with those in STEMI patients before thrombolysis. Compared with those in the control group, MPs in both CCS and STEMI patients before thrombolysis inhibited the expression of eNOS (both immunohistochemistry and western blot analysis of phosphorylation at Ser1177), NO production in the isolated myocardium and vasodilation in vitro and stimulated the expression of iNOS (immunohistochemistry and western blot analysis of phosphorylation at Thr495), and the generation of O2•- in the isolated myocardium. The effects of MPs were further enhanced by MPs from STEMI patients 2 hours after thrombolysis.

Conclusion

Changes in MP function after thrombolysis may be one of the mechanisms leading to ischemia-reperfusion after thrombolysis.

Expanding the Molecular Disturbances of Lipoproteins in Cardiometabolic Diseases: Lessons from Lipidomics

The increasing global burden of cardiometabolic diseases highlights the urgent clinical need for better personalized prediction and intervention strategies. Early diagnosis and prevention could greatly reduce the enormous socio-economic burden posed by these states. Plasma lipids including total cholesterol, triglycerides, HDL-C, and LDL-C have been at the center stage of the prediction and prevention strategies for cardiovascular disease; however, the bulk of cardiovascular disease events cannot be explained sufficiently by these lipid parameters. The shift from traditional serum lipid measurements that are poorly descriptive of the total serum lipidomic profile to comprehensive lipid profiling is an urgent need, since a wealth of metabolic information is currently underutilized in the clinical setting. The tremendous advances in the field of lipidomics in the last two decades has facilitated the research efforts to unravel the lipid dysregulation in cardiometabolic diseases, enabling the understanding of the underlying pathophysiological mechanisms and identification of predictive biomarkers beyond traditional lipids. This review presents an overview of the application of lipidomics in the study of serum lipoproteins in cardiometabolic diseases. Integrating the emerging multiomics with lipidomics holds great potential in moving toward this goal.

Risk Factors for Asymptomatic and Symptomatic Intracranial Atherosclerosis Determined by Magnetic Resonance Vessel Wall Imaging in Chinese Population: A Case–Control Study

Background and Purpose

The association between risk factors and intracranial atherosclerosis disease (ICAD) determined by magnetic resonance (MR) vessel wall imaging in Chinese population has not been investigated. The aim of this study was to investigate the associations of conventional vascular risk factors with asymptomatic and symptomatic ICAD using MR vessel wall imaging in Chinese population.

Methods

The study population was recruited from two cohort studies of ICASMAP and CAMERA comprised 104 symptomatic ICAD subjects (57.1 ± 11.1 years; 35.6% females), 51 asymptomatic ICAD subjects (70.1 ± 8.4 years; 50.0% females) and 418 controls (58.0 ± 13.3 years; 61.0% females) defined as asymptomatic subjects without ICAD on MR vessel wall imaging. We compared the vascular risk factors between the three groups using a multivariate logistic regression analysis.

Results

Compared with controls, there was a significant positive association between age (OR: 1.07, 95% CI: 1.03–1.10, p < 0.001) and hypertension (OR: 3.03, 95% CI: 1.45–6.36, p = 0.003) and asymptomatic ICAD. There was a positive association of smoking (OR: 3.41, 95% CI: 1.57–7.42, p = 0.001), hypertension (OR: 7.43, 95% CI: 3.81–14.49, p < 0.001) and diabetes (OR: 3.54, 95% CI: 1.93–6.49, p < 0.001) and an inverse association of high-density lipoprotein (HDL) (p < 0.017) with symptomatic ICAD. Compared to asymptomatic ICAD, there was a significant inverse association of age (OR: 0.86, 95% CI: 0.81–0.92, p < 0.001) and HDL (p < 0.001) with symptomatic ICAD.

Conclusion

Old age and hypertension are associated with asymptomatic ICAD and smoking, hypertension, diabetes and lower HDL are associated with an increased risk of symptomatic ICAD in Chinese population.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT03417063.

Extra Virgin Olive Oil Prevents the Age-Related Shifts of the Distribution of HDL Subclasses and Improves Their Functionality

High-density lipoproteins (HDL) maintain cholesterol homeostasis through the role they play in regulating reverse cholesterol transport (RCT), a process by which excess cholesterol is transported back to the liver for elimination. However, RCT can be altered in the presence of cardiovascular risk factors, such as aging, which contributes to the increase in the incidence of cardiovascular diseases (CVD). The present study was aimed at investigating the effect of extra virgin olive oil (EVOO) intake on the cholesterol efflux capacity (CEC) of HDL, and to elucidate on the mechanisms by which EVOO intake improves the anti-atherogenic activity of HDL. A total of 84 healthy women and men were enrolled and were distributed, according to age, into two groups: 27 young (31.81 ± 6.79 years) and 57 elderly (70.72 ± 5.6 years) subjects. The subjects in both groups were given 25 mL/d of extra virgin olive oil (EVOO) for 12 weeks. CEC was measured using J774 macrophages radiolabeled with tritiated cholesterol ((3H) cholesterol). HDL subclass distributions were analyzed using the Quantimetrix Lipoprint® system. The HDL from the elderly subjects exhibited a lower level of CEC, at 11.12% (p < 0.0001), than the HDL from the young subjects. The CEC of the elderly subjects returned to normal levels following 12 weeks of EVOO intake. An analysis of the distribution of HDL subclasses showed that HDL from the elderly subjects were composed of lower levels of large HDL (L-HDL) (p < 0.03) and higher levels of small HDL (S-HDL) (p < 0.002) compared to HDL from the young subjects. A multiple linear regression analysis revealed a positive correlation between CEC and L-HDL levels (r = 0.35 and p < 0.001) as well as an inverse correlation between CEC and S-HDL levels (r = -0.27 and p < 0.01). This correlation remained significant even when several variables, including age, sex, and BMI as well as low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and glucose levels (β = 0.28, p < 0.002, and β = 0.24, p = 0.01) were accounted for. Consuming EVOO for 12 weeks modulated the age-related difference in the distribution of HDL subclasses by reducing the level of S-HDL and increasing the level of intermediate-HDL/large-HDL (I-HDL/L-HDL) in the elderly subjects. The age-related alteration of the CEC of HDL was due, in part, to an alteration in the distribution of HDL subclasses. A diet enriched in EVOO improved the functionality of HDL through an increase in I-HDL/L-HDL and a decrease in S-HDL.

The Susceptibility to Diet-Induced Atherosclerosis Is Exacerbated with Aging in C57B1/6 Mice

The anti-atherogenic activity of HDL is mainly due to their capacity to mediate reverse cholesterol transport (RCT). However, it is not clear to what extent this activity is affected by aging or pro-atherogenic conditions. Three and 24-month-old C57Bl/6 mice were fed an atherogenic diet (high fat, high cholesterol) for 12 weeks. The aged mice displayed a significant reduction in the capacity of HDL to mediate RCT (29.03%, p < 0.0006). Interestingly, the atherogenic diet significantly stimulated the RCT process in both young and aged mice (241% and 201%, respectively, p < 0.01). However, despite this, significant amounts of cholesterol accumulated in the aortas of mice fed an atherogenic diet as compared to regular chow. The accumulation of cholesterol was more marked in the aortas of aged mice (110% increase, p < 0.002). ABCA1 and ABCG1 protein expression on macrophages decreased significantly (52 to 37% reduction, p < 0.002), whereas their expression on hepatic cells increased significantly (up to 590% for ABCA1 and 116% for ABCG1, p < 0.002). On the other hand, SR-BI protein expression on hepatic cells decreased significantly (42.85%, p < 0.0001). ABCG5, ABCG8, and CYP7a protein expression on hepatic cells was also higher in mice fed an atherogenic diet. The increase was age-dependent for both ABCG5 and ABCG8. Our results suggest that the susceptibility to diet-induced atherosclerosis is exacerbated with aging and is a consequence of the dysregulation of the expression levels of membrane cholesterol transporters.

Association between high-density lipoprotein cholesterol levels and major adverse cardiovascular events in patients who underwent coronary computed tomography angiography: FU-CCTA registry

It is unclear whether higher levels of serum high-density lipoprotein cholesterol (HDL-C) prevent major adverse cardiovascular events (MACE). We prospectively evaluated 501 patients who had undergone coronary computed tomography angiography at Fukuoka University Hospital and either were clinically suspected of having coronary artery disease (CAD) or had at least one cardiovascular risk factor with a follow-up of up to 5 years. The primary endpoint was MACE (cardiovascular death, ischemic stroke, acute myocardial infarction and coronary revascularization). The patients were divided into tertiles according to the HDL-C level: 47 mg/dl ≥ HDL-C level [n = 167, lower HDL-C level (L-HDL)], 58 mg/dl ≥ HDL-C level ≥ 48 mg/dl [n = 167, middle HDL-C level (M-HDL)] and HDL-C level ≥ 59 mg/dl [n = 167, higher HDL-C level (H-HDL)] groups. There were significant differences in %CAD among the L-HDL, M-HDL and H-HDL groups. Unexpectedly, there was no difference in %MACE between M-HDL and H-HDL, although %MACE in M-HDL was significantly lower than that in L-HDL (p < 0.05). By a multivariate logistic regression analysis, MACE in H-HDL-C was independently associated with diabetes mellitus (DM) (p = 0.03). A Kaplan-Meier curve according to the HDL subgroup indicated that M-HDL, not H-HDL, enjoyed the greatest freedom from MACE among the 3 groups (log-rank test p = 0.047). Finally, the results of a Cox regression model indicated that L-HDL and H-HDL had significantly higher risk of MACE than M-HDL. In conclusions, patients with middle HDL-C levels, not higher HDL-C levels, showed the greatest freedom from MACE. Patients with higher HDL-C levels need to be strictly managed for DM to prevent MACE.

Associations Between High Levels of High-Density Lipoprotein Cholesterol and the Presence and Severity of Coronary Artery Disease in Patients Who Have Undergone Coronary Computed Tomography Angiography

Background

Although a recent study in a Japanese cohort indicated that extremely high-density lipoprotein cholesterol (HDL-C, ≥ 90 mg/dL) had an adverse effect on atherosclerotic cardiovascular disease mortality, we could not conclude that high levels of HDL-C were associated with the presence or severity of coronary artery disease (CAD).

Methods

We enrolled 1,016 patients who were clinically suspected to have CAD and who underwent coronary computed tomography angiography (CCTA). The number of significantly stenosed coronary vessels (vessel disease (VD), ≥ 50% coronary stenosis is diagnosed as CAD) and the Gensini score were quantified using CCTA, and the lipid profile was measured. The patients were divided into four groups according to the HDL-C level: < 40 mg/dL (n = 115, low), 40 - 59 mg/dL (n = 530, normal), 60 - 89 mg/dL (n = 335, high) and ≥ 90 mg/dL (n = 36, very-high).

Results

The percentage (%) of CAD in the low, normal, high and very-high groups was 69%, 55%, 42% and 25%, respectively (P for trend < 0.01). The Gensini score in the low, normal, high and very-high groups was 20 ± 25, 12 ± 16, 8 ± 12 and 4 ± 6, respectively (P for trend < 0.01). The very-high group showed the lowest triglyceride (TG) levels among the four groups. There were no significant differences in the level of low-density lipoprotein cholesterol or % use of statin among the four groups. Finally, the presence of CAD was independently associated with a low level of HDL-C, in addition to age, male, high systolic blood pressure and hemoglobin A1c, but not TG, by a multivariate logistic regression analysis.

Conclusions

High levels of HDL-C at the time of CCTA for screening were associated with a reduced presence and severity of CAD.

Anti-atherosclerotic effects of an improved apolipoprotein A-I mimetic peptide

BACKGROUND

Apolipoprotein (Apo)A-I is a major protein component of high-density lipoprotein (HDL) that causes cholesterol efflux from peripheral cells through ATP-binding cassette transporter A1 (ABCA1) and the generation of HDL. Furthermore, it has a possible protective function against atherosclerotic cardiovascular disease (ASCVD). We previously developed a novel ApoA-I mimetic peptide without phospholipids (Fukuoka University ApoA-I Mimetic Peptide, FAMP). According to our previous studies, FAMP had an anti-arteriosclerotic effect. Since the required dose and reaction time of conventional FAMP were relatively large and short, respectively, we newly developed an improved FAMP (i-FAMP).

METHODS AND RESULTS

We synthesized four candidate i-FAMPs, i-FAMP-D1, -D2, -D3 and -D4, and examined which i-FAMP has greater cholesterol efflux capacity than FAMP in A172 human glioblastoma cells transiently transfected with human ABCA1 cDNA. Only i-FAMP-D1 showed significantly greater cholesterol efflux capacity than conventional FAMP. i-FAMP-D1 formed stronger α-helical conformations than FAMP as assessed by circular dichroism spectra. Thus, we selected i-FAMP-D1 for further experiments. i-FAMP-D1 had a greater atheroprotective effect than FAMP in ApoE knockout mice. In addition, i-FAMP-D1 activated cholesterol efflux from macrophage to HDL more strongly than FAMP and increased cholesterol excretion from liver to feces.

CONCLUSION

These results suggest that i-FAMP-D1 has a stronger anti-atherosclerotic effect than conventional FAMP.

Long-term effect of pioglitazone vs glimepiride on lipoprotein oxidation in patients with type 2 diabetes: a prospective randomized study

AIMS

Type 2 diabetes (DM2) is associated to oxidative modifications of high-density lipoproteins (HDL), which can interfere with their function. Pioglitazone has proved effective in raising HDL cholesterol (HDL-C) and lowering small dense low-density lipoprotein (LDL), but no clinical studies have examined its effect on lipoprotein oxidation in patients with DM2.

METHODS

We assessed the effect of pioglitazone vs glimepiride after 1 year on HDL oxidation, expressed as relative abundance of peptides containing Met¹¹²O in ApoA-I (oxApoA-I) estimated by mass spectrometry (MALDI/TOF/TOF), in 95 patients with DM2. The oxLDL and AGE were quantified by ELISA.

RESULTS

Patients receiving pioglitazone showed a significant increase in the concentration of ApoA-I (Δ = 7.2 ± 14.8 mg/dL, p < 0.02) and a reduction in oxApoA-I (Δ = - 1.0 ± 2.6%, p < 0.02); this reduction was not significantly different from glimepiride. oxLDL showed a slight, but not significant increase in both treatment groups. Regression analysis showed a correlation between ΔoxApoA-I and ΔAGE (r = 0.30; p = 0.007) in all patients, while both of these parameters were unrelated to changes in HbA1c, HDL-C, duration of illness, or use of statins.

CONCLUSIONS

Long-term treatment with pioglitazone was effective in reducing the oxidation of HDL, but not LDL in patients with DM2, while glimepiride didn't. This finding seems to be associated to the change of glyco-oxidation status, not to any improvement in glycemic control or lipid profile.

TRIAL REGISTRATION

NCT00700856, ClinicalTrials.gov Registered June 18, 2008.

The expression of hSR-B1 on platelets of patients with coronary artery disease (CAD)

INTRODUCTION

The human scavenger receptor class B type 1 (hSR-B1), which serves as a high affinity receptor for HDL, is expressed on platelet surface and mediates various anti-atherogenic functions. Based on the anti-thrombotic effect of HDL and the importance of HDL-SR-B1 in the formation of atherosclerotic plaque, the present study was aimed to investigate and compare the expression level of hSR-B1on platelets of CAD patients with that of normal controls.

METHODS

The expression of the hSR-B1 on platelets of 31 CAD patients with atherosclerotic plaque and 20 healthy controls were detected using flowcytometry and western blotting. Moreover, platelet function in response to the agonists was examined by aggregometry, and the lipid panel tests were assayed using chemistry autoanalyzer.

RESULTS

Our findings showed that the expression of hSR-B1 was significantly reduced on the surface of platelets from CAD patients with atherosclerotic disease, as compared with healthy controls (6/8% vs. 13/6%) (P < 0,001). Of particular of interest, we also found that the formation of aggregates after stimulation of the platelets with ADP was higher in patients with atherosclerotic disease than the controls; indicating an inverse relationship between hSR-B1 expression and the function of human platelets.

CONCLUSION

Taken together, the results of the present study raise the possibility that the measurement of hSR-B1 expression on human platelets may provide a valuable insight that reflects the status of RCT in patients with atherosclerosis.

The role of paraoxonase 1 in regulating high-density lipoprotein functionality during aging

Pharmacological interventions to increase the concentration of high-density lipoprotein (HDL) have led to disappointing results and have contributed to the emergence of the concept of HDL functionality. The anti-atherogenic activity of HDLs can be explained by their functionality or quality. The capacity of HDLs to maintain cellular cholesterol homeostasis and to transport cholesterol from peripheral cells to the liver for elimination is one of their principal anti-atherogenic activities. However, HDLs possess several other attributes that contribute to their protective effect against cardiovascular diseases. HDL functionality is regulated by various proteins and lipids making up HDL particles. However, several studies investigated the role of paraoxonase 1 (PON1) and suggest a significant role of this protein in the regulation of the functionality of HDLs. Moreover, research on PON1 attracted much interest following several studies indicating that it is involved in cardiovascular protection. However, the mechanisms by which PON1 exerts these effects remain to be elucidated.

High-density lipoproteins attenuate high glucose-impaired endothelial cell signaling and functions: potential implications for improved vascular repair in diabetes

Background

Abnormalities of endothelial cell function are proposed to be a critical factor underlying adverse cardiovascular outcomes in the setting of hyperglycaemia. While high-density lipoproteins (HDL) have been demonstrated to be cardioprotective, the impact on the endothelium in hyperglycaemia has not been fully elucidated.

Methods

Human umbilical vein endothelial cells (HUVECs) were exposed to high-glucose conditions using dextrose, the main isoform of glucose, and native HDL. HUVEC proliferation and migration were determined. The key signalling pathways that regulate endothelial cell function were also characterized.

Results

Increasing concentrations of dextrose resulted in significant reductions in HUVEC proliferation, this was attenuated by coincubation with HDL. In support of this, HDL was also found to rescue dextrose impaired expression of PCNA and the activation (phosphorylation) of the key transcription factor for proliferation ERK. Dextrose also dose-dependently inhibited HUVEC migration, which was mitigated by co-incubation with HDL. Consistent with this, HDL prevented dextrose-induced inhibition of p38 phosphorylation, responsible for cell migration. Finally, phosphorylation of the pro-survival transcription factor Akt was dose-dependently inhibited by dextrose, however, this was completely rescued by co-administration with HDL.

Conclusion

Dextrose-induced hyperglycaemia causes the impairment of endothelial cell proliferation and migration and inhibits the activation of ERK, p38 and Akt pathways. The protective effects of HDL in this milieu highlights the potential for HDL to improve vascular repair in patients with impaired glucose homeostasis.

Decreased high density lipoprotein cholesterol is an independent predictor for persistent organ failure, pancreatic necrosis and mortality in acute pancreatitis

High density lipoprotein cholesterol (HDL-C) has been reported as a significant indicator of systemic inflammation. The association underlying HDL-C and persistent organ failure (POF), pancreatic necrosis (PNec) and mortality in acute pancreatitis (AP) has not been evaluated. From 2007 to 2016, consecutive AP patients with admission lipid profiles assessment were included in this study. The association of HDL-C value and other lipids with outcomes was explored with Cox proportional regression models, which were adjusted for confounding factors. 1131 consecutive AP patients were clinically eligible. Overall, 17.9% of the patients developed with POF, 27.1% experienced PNec, and 6.7% died during hospitalization. Lower HDL-C median (<1.06 mmol/L) was identified as an independent prognostic factor of the outcomes. Moreover, there was a positive trend for the association across increasing HDL-C quartiles and POF, PNec and mortality after multivariable analysis (p values were <0.001, <0.001 and 0.043, respectively). The AUC of HDL-C for the outcomes were comparable to that of Ranson score for diagnosing POF (0.778 vs. 0.678; P < 0.001), PNec (0.734 vs. 0.701; P = 0.143) and mortality (0.768 vs. 0.745; P = 0.516). Decreased HDL-C value is an independent risk factor for the incidence of POF, PNec and in-hospital mortality in AP.

Apolipoprotein A-I Mimetic Peptides: Discordance Between In Vitro and In Vivo Properties-Brief Report

OBJECTIVE

Apolipoprotein A-I (apoA-I) mimetic peptides have antiatherogenic properties of high-density lipoprotein in vitro and have been shown to inhibit atherosclerosis in vivo. It is unclear, however, if each in vitro antiatherogenic property of these peptides translates to a corresponding activity in vivo, and if so, which of these contributes most to reduce atherosclerosis.

APPROACH AND RESULTS

The effect of 7 apoA-I mimetic peptides, which were developed to selectively reproduce a specific component of the antiatherogenic properties of apoA-I, on the development of atherosclerosis was investigated in apolipoprotein E-deficient mice fed a high-fat diet for 4 or 12 weeks. The peptides include those that selectively upregulate cholesterol efflux, or are anti-inflammatory, or have antioxidation properties. All the peptides studied effectively inhibited the in vivo development of atherosclerosis in this model to the same extent. However, none of the peptides had the same selective effect in vivo as they had exhibited in vitro. None of the tested peptides affected plasma lipoprotein profile; capacity of plasma to support cholesterol efflux was increased modestly and similarly for all peptides.

CONCLUSIONS

There is a discordance between the selective in vitro and in vivo functional properties of apoA-I mimetic peptides, and the in vivo antiatherosclerotic effect of apoA-I-mimetic peptides is independent of their in vitro functional profile. Comparing the properties of apoA-I mimetic peptides in plasma rather than in the lipid-free state is better for predicting their in vivo effects on atherosclerosis.

High density lipoprotein (HDL) particles from end-stage renal disease patients are defective in promoting reverse cholesterol transport

Atherosclerotic cardiovascular disease (CVD) represents the largest cause of mortality in end-stage renal disease (ESRD). CVD in ESRD is not explained by classical CVD risk factors such as HDL cholesterol mass levels making functional alterations of lipoproteins conceivable. HDL functions in atheroprotection by promoting reverse cholesterol transport (RCT), comprising cholesterol efflux from macrophage foam cells, uptake into hepatocytes and final excretion into the feces. ESRD-HDL (n = 15) were compared to healthy control HDL (n = 15) for their capacity to promote in vitro (i) cholesterol efflux from THP-1 macrophage foam cells and (ii) SR-BI-mediated selective uptake into ldla[SR-BI] cells as well as (iii) in vivo RCT. Compared with HDL from controls, ESRD-HDL displayed a significant reduction in mediating cholesterol efflux (p < 0.001) and SR-BI-mediated selective uptake (p < 0.01), two key steps in RCT. Consistently, also the in vivo capacity of ESRD-HDL to promote RCT when infused into wild-type mice was significantly impaired (p < 0.01). In vitro oxidation of HDL from healthy controls with hypochloric acid was able to fully mimic the impaired biological activities of ESRD-HDL. In conclusion, we demonstrate that HDL from ESRD patients is dysfunctional in key steps as well as overall RCT, likely due to oxidative modification.

Effects of obeticholic acid on lipoprotein metabolism in healthy volunteers

The bile acid analogue obeticholic acid (OCA) is a selective farnesoid X receptor (FXR) agonist in development for treatment of several chronic liver diseases. FXR activation regulates lipoprotein homeostasis. The effects of OCA on cholesterol and lipoprotein metabolism in healthy individuals were assessed. Two phase I studies were conducted to evaluate the effects of repeated oral doses of 5, 10 or 25 mg OCA on lipid variables after 14 or 20 days of consecutive administration in 68 healthy adults. Changes in HDL and LDL cholesterol levels were examined, in addition to nuclear magnetic resonance analysis of particle sizes and sub-fraction concentrations. OCA elicited changes in circulating cholesterol and particle size of LDL and HDL. OCA decreased HDL cholesterol and increased LDL cholesterol, independently of dose. HDL particle concentrations declined as a result of a reduction in medium and small HDL. Total LDL particle concentrations increased because of an increase in large LDL particles. Changes in lipoprotein metabolism attributable to OCA in healthy individuals were found to be consistent with previously reported changes in patients receiving OCA with non-alcoholic fatty liver disease or non-alcoholic steatohepatitis.

HDL function is impaired in acute myocardial infarction independent of plasma HDL cholesterol levels

BACKGROUND

High-density lipoproteins (HDLs) protect against the development of atherosclerotic cardiovascular disease. HDL function represents an emerging concept in cardiovascular research.

OBJECTIVE

This study investigated the association between HDL functionality and acute myocardial infarction (MI) independent of HDL-cholesterol plasma levels.

METHODS

Participants (non-ST-segment elevation MI, non-STEMI, n = 41; STEMI, n = 37; non-MI patients, n = 33) from a prospective follow-up study enrolling patients with acute chest pain were matched for age and plasma HDL cholesterol. The in vitro capacity of HDL to (1) mediate cholesterol efflux from macrophage foam cells, (2) prevent low-density lipoprotein oxidation, and (3) inhibit TNF-α-induced vascular adhesion molecule-1 expression in endothelial cells was determined.

RESULTS

STEMI-HDL displayed reduced cholesterol efflux (P < .001) and anti-inflammatory functionality (P = .001), whereas the antioxidative properties were unaltered. Cholesterol efflux correlated with the anti-inflammatory HDL activity (P < .001). Not C-reactive protein levels, a marker of systemic inflammation, but specifically plasma myeloperoxidase levels were independently associated with impaired HDL function (efflux: P = .022; anti-inflammation: P < .001). Subjects in the higher risk quartile of efflux (odds ratio [OR], 5.66; 95% confidence interval [CI], 1.26-25.00; P = .024) as well as anti-inflammatory functionality of HDL (OR, 5.53; 95% CI, 1.83-16.73; P = .002) had a higher OR for MI vs those in the three lower risk quartiles combined.

CONCLUSION

Independent of plasma HDL cholesterol levels, 2 of 3 antiatherogenic HDL functionalities tested were significantly impaired in STEMI patients, namely cholesterol efflux and anti-inflammatory properties. Increased myeloperoxidase levels might represent a major contributing mechanism for decreased HDL functionality in MI patients.

Influences on plasminogen activator inhibitor-2 polymorphism-associated recurrent cardiovascular disease risk in patients with high HDL cholesterol and inflammation

BACKGROUND AND AIMS

Evidence continues to accumulate that athero-protective effects of high-density lipoprotein (HDL) depend to some degree on effective HDL functionality and that such functionality can become degraded in the setting of chronic inflammation. To investigate this issue, we have studied a group of post-myocardial infarction patients with high levels of C-reactive protein as an indicator of chronic inflammation and with concurrently high levels of HDL cholesterol. For these patients we have demonstrated high-risk for recurrent cardiac events as well as a strong association of risk with a polymorphism of the gene (SERPINB2) for plasminogen activator inhibitor-2 (PAI-2) presumptively reflective of an important role for fibrinolysis in risk. However, additional processes might be involved. The current work sought to characterize processes underlying how PAI-2 might be involved in the generation of risk.

METHODS

Multivariate population data were leveraged using Bayesian network modeling, a graphical probabilistic approach for knowledge discovery, to generate networks reflective of influences on PAI-2 polymorphism-associated risk.

RESULTS

Modeling results revealed three individual networks centering on the PAI-2 polymorphism with specific features providing information relating to how the polymorphism might associate with risk. These included racial dependency, platelet clot initiation and propagation, oxidative stress, inflammation effects on HDL metabolism and coagulation, and induction and termination of fibrinolysis.

CONCLUSIONS

Beyond direct association of a PAI-2 polymorphism with recurrent risk in post-myocardial infarction patients, results suggest that PAI-2 likely plays a key role leading to risk through multiple pathophysiologic processes. Such knowledge could potentially be valuable with individualization of patient care.

High-density lipoprotein mimetics: promises and challenges

The concept of lipoprotein mimetics was developed and extensively tested in the last three decades. Most lipoprotein mimetics were designed to recreate one or several functions of high-density lipoprotein (HDL) in the context of cardiovascular disease; however, the application of this approach is much broader. Lipoprotein mimetics should not just be seen as a set of compounds aimed at replenishing a deficiency or dysfunctionality of individual elements of lipoprotein metabolism but rather as a designer concept with remarkable flexibility and numerous applications in medicine and biology. In the present review, we discuss the fundamental design principles used to create lipoprotein mimetics, mechanisms of their action, medical indications and efficacy in animal models and human studies.

HDL Cholesterol Efflux Predicts Graft Failure in Renal Transplant Recipients

High-density lipoprotein (HDL) particles are involved in the protection against cardiovascular disease by promoting cholesterol efflux, in which accumulated cholesterol is removed from macrophage foam cells. We investigated whether HDL cholesterol efflux capacity is associated with cardiovascular mortality, all-cause mortality, and graft failure in a cohort of renal transplant recipients (n=495, median follow-up 7.0 years). Cholesterol efflux capacity at baseline was quantified using incubation of human macrophage foam cells with apolipoprotein B-depleted plasma. Baseline efflux capacity was not different in deceased patients and survivors (P=0.60 or P=0.50 for cardiovascular or all-cause mortality, respectively), whereas recipients developing graft failure had lower efflux capacity than those with functioning grafts (P<0.001). Kaplan-Meier analysis demonstrated a lower risk for graft failure (P=0.004) but not cardiovascular (P=0.30) or all-cause mortality (P=0.31) with increasing gender-stratified tertiles of efflux capacity. Cox regression analyses adjusted for age and gender showed that efflux capacity was not associated with cardiovascular mortality (hazard ratio [HR], 0.89; 95% confidence interval [95% CI], 0.67 to 1.19; P=0.43). Furthermore, the association between efflux capacity and all-cause mortality (HR, .79; 95% CI, 0.63 to 0.98; P=0.031) disappeared after further adjustment for potential confounders. However, efflux capacity at baseline significantly predicted graft failure (HR, 0.43; 95% CI, 0.29 to 0.64; P<0.001) independent of apolipoprotein A-I, HDL cholesterol, or creatinine clearance. In conclusion, this prospective study shows that cholesterol efflux capacity from macrophage foam cells is not associated with cardiovascular or all-cause mortality but is a strong predictor of graft failure independent of plasma HDL cholesterol levels in renal transplant recipients.

Increased plasma monocyte chemoattractant protein-1 levels in patients with isolated low high-density lipoprotein cholesterol

BACKGROUND

High-density lipoprotein cholesterol (HDL-C) inhibits inflammation associated with the development of atherosclerotic plaques. Monocyte chemoattractant protein-1 (MCP-1) contributes to the pathogenesis of atherosclerosis. The aim of this study was to evaluate the relationship between plasma MCP-1 levels and low HDL-C levels in patients without cardiovascular disease (CVD).

METHODS

This study included 55 patients with low HDL-C (≤ 35 mg/dL) and 33 age- and sex-matched control subjects with normal HDL-C (˃ 35 mg/dL). In addition to MCP-1 levels, laboratory parameters associated with inflammation such as neutrophil-lymphocyte ratio (NLR), uric acid and high sensitivity C-reactive protein (hs-CRP) were also evaluated.

RESULTS

HDL-C levels was significantly lower in study group compared to that of the control group (p < 0.001). MCP-1 were prominently higher in the low HDL-C group compared with those of the control group (p < 0.01). NLR, uric acid and hs-CRP levels were also higher in patients with low HDL-C than controls.

CONCLUSION

These findings suggest that elevated plasma MCP-1 levels and inflammation status might be associated with the increased cardiovascular risk in patients with low HDL-C.

Rosiglitazone attenuates atherosclerosis and increases high-density lipoprotein function in atherosclerotic rabbits

Rosiglitazone has been found to have anti-atherogenic effects and to increase serum high-density lipoprotein (HDL) cholesterol (HDL-C) levels. However, in vivo studies investigating the regulation of adenosine triphosphate-binding cassette transporter A1 (ABCA1) and scavenger receptor class B type I (SR-BI) by rosiglitazone are limited. Moreover, the effects of rosiglitazone on the function and levels of HDL are unclear. In the present study, we investigated the effects of rosiglitazone on HDL function and its mechanisms of action in atherosclerotic rabbits. Our results revealed that rosiglitazone induced a significant increase in serum HDL-C levels, paraoxonase 1 (PON1) activity, [³H]cholesterol efflux rates, and the expression of ABCA1 and SR-BI in hepatocytes and peritoneal macrophages. The expression of ABCA1 was also increased in aortic lesions. Rosiglitazone markedly reduced serum myeloperoxidase (MPO) activity, aortic intima-media thickness (IMT) and the percentage of plaque area in the aorta. It can thus be concluded that in atherosclerotic rabbits, rosigitazone increases the levels of HDL-C and hinders atherosclerosis. Thus, it improves HDL quality and function, as well as the HDL-induced cholesterol efflux, exerting anti-inflammatory and antioxidant effects.

High-Density Lipoprotein - A Hero, a Mirage, or a Witness?

Negative relationship between plasma high-density lipoprotein (HDL) levels and risk of cardiovascular disease (CVD) is a firmly established medical fact, but attempts to reproduce protective properties of HDL by pharmacologically elevating HDL levels were mostly unsuccessful. This conundrum presents a fundamental question: were the approaches used to raise HDL flawed or the protective effects of HDL are an epiphenomenon? Recent attempts to elevate plasma HDL were universally based on reducing HDL catabolism by blocking reverse cholesterol transport (RCT). Here, we argue that this mode of HDL elevation may be mechanistically different to natural mechanisms and thus be counterproductive. We further argue that independently of whether HDL is a driving force or a surrogate measure of the rate of RCT, approaches aimed at increasing HDL supply, rather than reducing its catabolism, would be most beneficial for speeding up RCT and improving protection against CVD.

Alteration of HDL functionality and PON1 activities in acute coronary syndrome patients

OBJECTIVE

The functionality of HDL has been suggested as an important factor in the prevention of cardiovascular and coronary artery diseases. The objective of the present study was to investigate the functionality of HDL and the factors that may affect the anti-atherogenic properties of HDL in ACS patients.

METHODS AND RESULTS

One hundred healthy subjects and 205 ACS patients were recruited. HDL functionality was evaluated by measuring their capacity to mediate cholesterol efflux from J774 macrophages. Oxidative stress status was determined by measuring plasma malondialdehyde (MDA), protein carbonyl, and vitamin E levels by HPLC. The PON1 Q192R polymorphism status and PON1 paraoxonase and arylesterase activities of the healthy subjects and ACS patients were also determined. The HDL of ACS patients displayed a limited capacity to mediate cholesterol efflux, especially via the ABCA1-pathway. MDA (7.06±0.29 μM) and protein carbonyl (9.29±0.26 μM) levels were significantly higher in ACS patients than in healthy subjects (2.29±0.21 μM and 3.07±0.17 μM, respectively, p<0.0001), while α- and γ-tocopherol (vitamin E) levels in ACS patients were 8-fold (p<0.001) and 2-fold (p<0.05) lower than in healthy subjects. Paraoxonase, arylesterase and HDL-corrected PON1 activities (PON1 activity/HDL ratio) were significantly lower in ACS patients. Logistic regression analyses showed that high PON1 paraoxonase and arylesterase activities had a significant protective effect (OR=0.413, CI 0.289-0.590, p<0.001; OR=0.232 CI 0.107-0.499, p<0.001, respectively) even when adjusted for HDL level, age, BMI, and PON1 polymorphism.

CONCLUSION

The results of the present study showed that the functionality of HDL is impaired in ACS patients and that the impairment may be due to oxidative stress and an alteration of PON1 activities.

HDL-mediated mechanisms of protection in cardiovascular disease

Low plasma levels of HDL-cholesterol (HDL-C) represent a strong and independent risk factor for cardiovascular disease. HDL particles display a wide spectrum of atheroprotective activities, which include effluxing cellular cholesterol, diminishing cellular death, decreasing vascular constriction, reducing inflammatory response, protecting from pathological oxidation, combating bacterial infection, lessening platelet activation, regulating gene expression by virtue of microRNAs, and improving glucose metabolism. It remains presently indeterminate as to whether some biological activities of HDL are more relevant for the protection of the endothelium from atherogenesis when compared with others. The multitude of such activities raises the question of a proper assay to assess HDL functionality ex vivo. Together with clear understanding of molecular mechanisms underlying atheroprotective properties of HDL, such assay will provide a basis to resolve the ultimate question of the HDL field to allow the development of efficient HDL-targeting therapies.

Low High-Density Lipoprotein Cholesterol Is Characterized by Elevated Oxidative Stress

High-density lipoprotein cholesterol (HDL-C) is an independent risk factor for premature atherosclerosis and cardiovascular disease. Plasma HDL exerts potent antioxidant activity. We evaluated parameters associated with oxidative stress in participants with low HDL-C. This study included 32 patients with low HDL-C (≤35 mg/dL) and 33 age- and sex-matched control patients with normal HDL-C (>35 mg/dL). We evaluated clinical and laboratory parameters that are associated with oxidative stress. The oxidative stress index (OSI) levels were significantly higher in the low HDL-C group (3.32 [0.01-13.3] vs 0.74 [0.17-3.55] AU; P < .01) and negatively correlated with HDL-C levels. We suggest that change in OSI and uric acid levels in the study group might indicate increased oxidative status in patients with low HDL-C. This may be associated with increased cardiovascular risk.

Conservation of apolipoprotein A-I's central domain structural elements upon lipid association on different high-density lipoprotein subclasses

The antiatherogenic properties of apolipoprotein A-I (apoA-I) are derived, in part, from lipidation-state-dependent structural elements that manifest at different stages of apoA-I's progression from lipid-free protein to spherical high-density lipoprotein (HDL). Previously, we reported the structure of apoA-I's N-terminus on reconstituted HDLs (rHDLs) of different sizes. We have now investigated at the single-residue level the conformational adaptations of three regions in the central domain of apoA-I (residues 119-124, 139-144, and 164-170) upon apoA-I lipid binding and HDL formation. An important function associated with these residues of apoA-I is the activation of lecithin:cholesterol acyltransferase (LCAT), the enzyme responsible for catalyzing HDL maturation. Structural examination was performed by site-directed tryptophan fluorescence and spin-label electron paramagnetic resonance spectroscopies for both the lipid-free protein and rHDL particles 7.8, 8.4, and 9.6 nm in diameter. The two methods provide complementary information about residue side chain mobility and molecular accessibility, as well as the polarity of the local environment at the targeted positions. The modulation of these biophysical parameters yielded new insight into the importance of structural elements in the central domain of apoA-I. In particular, we determined that the loosely lipid-associated structure of residues 134-145 is conserved in all rHDL particles. Truncation of this region completely abolished LCAT activation but did not significantly affect rHDL size, reaffirming the important role of this structural element in HDL function.

Newer therapeutic strategies to alter high-density lipoprotein level and function

Measurements of low levels of high-density lipoprotein (HDL) cholesterol have been identified as a risk factor for premature coronary artery disease, however, to date, current pharmacologic approaches for raising HDL have provided little benefit, if at all, in reducing cardiovascular outcomes. It has been shown that HDL can modify many aspects of plaque pathogenesis. Its most established role is in reverse cholesterol transportation, but HDL can also affect oxidation, inflammation, cellular adhesion, and vasodilatation. Considering these potential benefits of HDL, newer treatments have been developed to modify HDL activity, which include the use of oral cholesteryl ester transfer protein inhibitors, apolipoprotein (apo)A-I infusions, apoA-I mimetics, drugs to increase apoA-I synthesis, and agonists of the liver X receptor. These new therapies are reviewed in this article.

Extra-virgin olive oil consumption reduces the age-related decrease in HDL and paraoxonase 1 anti-inflammatory activities

Paraoxonase 1 (PON1) is associated with HDL and modulates the antioxidant and anti-inflammatory role of HDL. The goals of the present study were to investigate the effect of ageing and the role of PON1 on the anti-inflammatory activity of HDL, and to determine whether extra-virgin olive oil (EVOO) consumption could improve the atheroprotective activity of HDL. HDL and PON1 were isolated from the plasma of ten young (Y-HDL and Y-PON1) and ten elderly (E-HDL and E-PON1) healthy volunteers before and after 12 weeks of EVOO consumption. Inflammation was assessed by measuring intracellular adhesion molecule 1 (ICAM-1) expression. THP-1 (human acute monocytic leukaemia cell line) monocyte chemotaxis was measured using a Boyden chamber. Oxidative damage to HDL was assessed by measuring conjugated diene formation and changes in electrophoretic migration. Y-HDL had more anti-inflammatory activity than E-HDL. The conjugated diene content and the electrophoretic mobility of E-HDL were higher than those of Y-HDL. Y-PON1 had significant anti-inflammatory activity, reducing ICAM-1 expression by 32·64 (SD 2·63)%, while E-PON1 had no significant effect. THP-1 chemotaxis measurements confirmed the ICAM-1 expression results. The 12 weeks of EVOO consumption significantly increased the anti-inflammatory activities of both HDL and PON1. The anti-inflammatory activity of HDL was modulated by PON1 and was lower in the elderly volunteers. EVOO consumption increased the anti-inflammatory effect of HDL and reduced the age-related decrease in anti-atherogenic activity.

The impact of partial and complete loss-of-function mutations in endothelial lipase on high-density lipoprotein levels and functionality in humans

BACKGROUND

Endothelial lipase is a phospholipase with activity against high-density lipoprotein. Although a small number of mutations in LIPG have been described, the role of LIPG in protection against atherosclerosis is unclear.

METHODS AND RESULTS

We identified 8 loss-of-function (LOF) mutations in LIPG in individuals with high-density lipoprotein cholesterol. Functional analysis confirmed that most rare mutations abolish lipase activity in vitro, indicating complete LOF, whereas 2 more common mutations N396S and R476W reduce activity by ≈50%, indicating partial LOF and implying ≈50% and ≈75% remaining endothelial lipase function in heterozygous complete LOF and partial LOF mutation carriers, respectively. complete LOF mutation carriers had significantly higher plasma high-density lipoprotein cholesterol levels compared with partial LOF mutation carriers. Apolipoprotein B-depleted serum from complete LOF carriers showed significantly enhanced cholesterol efflux acceptor capacity, whereas only trends were observed in partial LOF carriers. Carriers of LIPG mutations exhibited trends toward reduced coronary artery disease in 4 independent cohorts (meta-analysis odds ratio, 0.7; P=0.04).

CONCLUSIONS

Our data suggest that the impact of LIPG mutations is directly related to their effect on endothelial lipase function and support that antagonism of endothelial lipase function improves cardioprotection.

Expression of endothelial lipase correlates with the size of neointima in a murine model of vascular remodeling

AIM

Endothelial lipase (EL) regulates plasma high-density lipoprotein-cholesterol (HDL-C) levels by promoting HDL catabolism. However, it remains unknown whether the inhibition of EL has beneficial effects on the genesis of vascular diseases. Here, we investigated the role of EL on vascular remodeling in mice.

METHODS

Vascular remodeling was developed by ligation of the left common carotid artery and neointimal lesions were histologically compared between EL-knockout (ELKO), EL-transgenic (ELTg), and wild-type (WT) mice. HDL was isolated from these mice, and effects of the HDL on cell growth and Erk activation were evaluated in vitro using cultured vascular smooth muscle cells.

RESULTS

Plasma HDL-C levels were 62% higher in ELKO and 13% lower in ELTg than in WT mice, after the carotid ligation. The size of neointimal lesion was significantly larger in ELTg and smaller in ELKO than in WT mice. Vascular expression of adhesion molecules was lower in ELKO and higher in ELTg compared with WT mice. Moreover, oxidative stress was attenuated in ELKO mice. HDL isolated from ELKO, ELTg, and WT mice inhibited expression of intercellular adhesion molecule-1, angiotensin II-induced activation of Erk, and growth of cultured vascular smooth muscle cells, whereas EL expression itself did not affect cell migration or growth.

CONCLUSION

EL expression modulates vascular remodeling as well as plasma HDL-C levels. EL inactivation may increase HDL particles that can inhibit smooth muscle cell growth and migration.

Reactive Oxygen Species, SUMOylation, and Endothelial Inflammation

Although the exact mechanism through which NADPH oxidases (Nox's) generate reactive oxygen species (ROS) is still not completely understood, it is widely considered that ROS accumulation is the cause of oxidative stress in endothelial cells. Increasing pieces of evidence strongly indicate the role for ROS in endothelial inflammation and dysfunction and subsequent development of atherosclerotic plaques, which are causes of various pathological cardiac events. An overview for a causative relationship between ROS and endothelial inflammation will be provided in this review. Particularly, a crucial role for specific protein SUMOylation in endothelial inflammation will be presented. Given that SUMOylation of specific proteins leads to increased endothelial inflammation, targeting specific SUMOylated proteins may be an elegant, effective strategy to control inflammation. In addition, the involvement of ROS production in increasing the risk of recurrent coronary events in a sub-group of non-diabetic, post-infarction patients with elevated levels of HDL-cholesterol will be presented with the emphasis that elevated HDL-cholesterol under certain inflammatory conditions can lead to increased incidence of cardiovascular events.

Apolipoprotein B-100 and apoA-II kinetics as determinants of cellular cholesterol efflux

CONTEXT

Cellular cholesterol efflux is a key step in reverse cholesterol transport and may depend on the metabolism of apolipoprotein (apo) B-100, apoA-I, and apoA-II.

OBJECTIVE

We examined the associations between cholesterol efflux and plasma concentrations and kinetics of very low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), and low-density lipoprotein (LDL)-apoB-100, high-density lipoprotein (HDL)-apoA-I, and HDL-apoA-II in men. DESIGN, SUBJECTS, AND METHODS: Thirty men were recruited from the community with a wide range of body mass index. The capacity of plasma and HDL to efflux cholesterol was measured ex vivo. Apolipoprotein kinetics were measured using stable isotope techniques and multicompartmental modeling.

RESULTS

Cholesterol efflux to whole plasma was correlated with plasma levels of cholesterol, triglyceride, apoB-100, insulin, cholesteryl ester transfer protein, and lecithin-cholesterol acyltransferase, body mass index and waist circumference (P < 0.05 in all). Cholesterol efflux was inversely correlated with the fractional catabolic rate (FCR) of VLDL (r = -0.728), IDL (r = -0.662), and LDL-apoB-100 (r = -0.479) but positively correlated with the FCR (r = 0.438) and production rate (r = 0.468) of HDL-apoA-II. In multiple regression analysis, the concentration and FCR of VLDL-apoB-100 (β-coefficient = 0.708 and -0.518, respectively) and IDL-apoB-100 (β-coefficient = 0.354 and -0.447, respectively) were independent predictors of cholesterol efflux. The association of cholesterol efflux with apoB-100 metabolism was diminished after removal of apoB-100-containing lipoproteins from plasma prior to efflux. All associations, except for cholesteryl ester transfer protein, were lost when cholesterol efflux to isolated HDL was tested.

CONCLUSIONS

The plasma concentration and kinetics of apoB-100-containing lipoproteins are significant predictors of the capacity of whole plasma to effect cellular cholesterol efflux.

Measurement of reverse cholesterol transport pathways in humans: in vivo rates of free cholesterol efflux, esterification, and excretion

BACKGROUND

Reverse cholesterol transport from peripheral tissues is considered the principal atheroprotective mechanism of high-density lipoprotein, but quantifying reverse cholesterol transport in humans in vivo remains a challenge. We describe here a method for measuring flux of cholesterol though 3 primary components of the reverse cholesterol transport pathway in vivo in humans: tissue free cholesterol (FC) efflux, esterification of FC in plasma, and fecal sterol excretion of plasma-derived FC.

METHODS AND RESULTS

A constant infusion of [2,3-(13)C(2)]-cholesterol was administered to healthy volunteers. Three-compartment SAAM II (Simulation, Analysis, and Modeling software; SAAM Institute, University of Washington, WA) fits were applied to plasma FC, red blood cell FC, and plasma cholesterol ester (13)C-enrichment profiles. Fecal sterol excretion of plasma-derived FC was quantified from fractional recovery of intravenous [2,3-(13)C(2)]-cholesterol in feces over 7 days. We examined the key assumptions of the method and evaluated the optimal clinical protocol and approach to data analysis and modeling. A total of 17 subjects from 2 study sites (n=12 from first site, age 21 to 75 years, 2 women; n=5 from second site, age 18 to 70 years, 2 women) were studied. Tissue FC efflux was 3.79±0.88 mg/kg per hour (mean ± standard deviation), or ≍8 g/d. Red blood cell-derived flux into plasma FC was 3.38±1.10 mg/kg per hour. Esterification of plasma FC was ≍28% of tissue FC efflux (1.10±0.38 mg/kg per hour). Recoveries were 7% and 12% of administered [2,3-(13)C(2)]-cholesterol in fecal bile acids and neutral sterols, respectively.

CONCLUSIONS

Three components of systemic reverse cholesterol transport can be quantified, allowing dissection of this important function of high-density lipoprotein in vivo. Effects of lipoproteins, genetic mutations, lifestyle changes, and drugs on these components can be assessed in humans. (J Am Heart Assoc. 2012;1:e001826 doi: 10.1161/JAHA.112.001826.).

Apolipoprotein E predicts incident cardiovascular disease risk in women but not in men with concurrently high levels of high-density lipoprotein cholesterol and C-reactive protein

Although there is great interest in the notion that dysfunctional transformation of high-density lipoprotein (HDL) facilitates development of atherosclerosis and cardiovascular disease (CVD), few studies in human populations directly address this issue. As apolipoprotein E (apoE) is a constituent of HDL thought to be important for HDL antiatherogenic function, we sought to assess the role of apoE in CVD risk in subjects likely to display dysfunctional transformation of HDL. Association of apoE levels with incident CVD risk was investigated using Cox multivariable proportional hazards modeling. Analyses were performed in subgroups of women and men likely to display dysfunctional transformation of HDL deriving from previous subgroup identification based upon defining characteristics of concurrently high levels of HDL cholesterol and systemic inflammation as reflected by high C-reactive protein levels. Results revealed apoE levels (dichotomized as highest quartile vs combined 3 lowest quartiles) as predicting subgroup risk in women (hazard ratio, 4.52; 95% confidence interval, 1.07-19.12; P = .040) but not in men. Further sex differences were manifested in terms of the relationship of apoE levels with age. Analysis revealed positive correlation of apoE levels with age in women (r = 0.47, P < .0001) but not in men (r = 0.04, P = .43). Apolipoprotein E levels predict incident CVD risk in women with high levels of HDL cholesterol and C-reactive protein but not in men. Future studies should be oriented toward investigations of apoE as related to multiplicity of HDL functionality and toward assessment of potential roles for apoE in dysfunctional transformation of HDL.

Apolipoprotein A-II influences apolipoprotein E-linked cardiovascular disease risk in women with high levels of HDL cholesterol and C-reactive protein

Background

In a previous report by our group, high levels of apolipoprotein E (apoE) were demonstrated to be associated with risk of incident cardiovascular disease in women with high levels of C-reactive protein (CRP) in the setting of both low (designated as HR1 subjects) and high (designated as HR2 subjects) levels of high-density lipoprotein cholesterol (HDL-C).

To assess whether apolipoprotein A-II (apoA-II) plays a role in apoE-associated risk in the two female groups.

Methodology/Principal

Outcome event mapping, a graphical data exploratory tool; Cox proportional hazards multivariable regression; and curve-fitting modeling were used to examine apoA-II influence on apoE-associated risk focusing on HDL particles with apolipoprotein A-I (apoA-I) without apoA-II (LpA-I) and HDL particles with both apoA-I and apoA-II (LpA-I:A-II). Results of outcome mappings as a function of apoE levels and the ratio of apoA-II to apoA-I revealed within each of the two populations, a high-risk subgroup characterized in each situation by high levels of apoE and additionally: in HR1, by a low value of the apoA-II/apoA-I ratio; and in HR2, by a moderate value of the apoA-II/apoA-I ratio. Furthermore, derived estimates of LpA-I and LpA-I:A-II levels revealed for high-risk versus remaining subjects: in HR1, higher levels of LpA-I and lower levels of LpA-I:A-II; and in HR2 the reverse, lower levels of LpA-I and higher levels of LpA-I:A-II. Results of multivariable risk modeling as a function of LpA-I and LpA-I:A-II (dichotomized as highest quartile versus combined three lower quartiles) revealed association of risk only for high levels of LpA-I:A-II in the HR2 subgroup (hazard ratio 5.31, 95% CI 1.12–25.17, p = 0.036). Furthermore, high LpA-I:A-II levels interacted with high apoE levels in establishing subgroup risk.

Conclusions/Significance

We conclude that apoA-II plays a significant role in apoE-associated risk of incident CVD in women with high levels of HDL-C and CRP.

HDL-C: does it matter? An update on novel HDL-directed pharmaco-therapeutic strategies

It has long been recognized that elevated levels of low-density lipoprotein cholesterol (LDL-C) increase the risk of cardiovascular disease (CHD) and that pharmacologic therapy to decrease LDL-C significantly reduces cardiovascular events. Despite the effectiveness of statins for CHD risk reduction, even optimal LDL-lowering therapy alone fails to avert 60% to 70% of CHD cases. A low plasma concentration of high-density lipoprotein cholesterol (HDL-C) is also associated with increased risk of CHD. However, the convincing epidemiologic data linking HDL cholesterol (HDL-C) to CHD risk in an inverse correlation has not yet translated into clinical trial evidence supporting linearity between HDL-C increases and CHD risk reduction. It is becoming clear that a functional HDL is a more desirable target than simply increasing HDL-C levels. Discoveries in the past decade have shed light on the complex metabolic and antiatherosclerotic pathways of HDL. These insights, in turn, have fueled the development of new HDL-targeted drugs, which can be classified according to four different therapeutic approaches: directly augmenting the concentration of apolipoprotein A-I (apo A-I), the major protein constituent of HDL; indirectly augmenting the concentration of apo A-I and HDL cholesterol; mimicking the functionality of apo A-I and enhancing reverse cholesterol transport. This review discusses the latest in novel HDL directed therapeutic strategies.