HDL Cholesterol Efflux Capacity Research Articles

Lutein and Zeaxanthin Enhance, Whereas Oxidation, Fructosylation, and Low pH Damage High-Density Lipoprotein Biological Functionality.

High-density lipoproteins (HDLs) are key regulators of cellular cholesterol homeostasis but are functionally altered in many chronic diseases. The factors that cause HDL functional loss in chronic disease are not fully understood. It is also unknown what roles antioxidant carotenoids play in protecting HDL against functional loss. The aim of this study was to measure how various disease-associated chemical factors including exposure to (1) Cu2+ ions, (2) hypochlorous acid (HOCL), (3) hydrogen peroxide (H2O2), (4) sialidase, (5) glycosidase, (6) high glucose, (7) high fructose, and (8) acidic pH, and the carotenoid antioxidants (9) lutein and (10) zeaxanthin affect HDL functionality. We hypothesized that some of the modifications would have stronger impacts on HDL particle structure and function than others and that lutein and zeaxanthin would improve HDL function. HDL samples were isolated from generally healthy human plasma and incubated with the corresponding treatments listed above. Cholesterol efflux capacity (CEC), lecithin-cholesterol acyl transferase (LCAT) activity, and paraoxonase-1 (PON1) activity were measured in order to determine changes in HDL functionality. Median HDL particle diameter was increased by acidic pH treatment and reduced by HOCl, high glucose, high fructose, N-glycosidase, and lutein treatments. Acidic pH, oxidation, and fructosylation all reduced HDL CEC, whereas lutein, zeaxanthin, and sialidase treatment improved HDL CEC. LCAT activity was reduced by acidic pH, oxidation, high fructose treatments, and lutein. PON1 activity was reduced by sialidase, glycosidase, H2O2, and fructose and improved by zeaxanthin and lutein treatment. These results show that exposure to oxidizing agents, high fructose, and low pH directly impairs HDL functionality related to cholesterol efflux and particle maturation, whereas deglycosylation impairs HDL antioxidant capacity. On the other hand, the antioxidants lutein and zeaxanthin improve or preserve both HDL cholesterol efflux and antioxidant activity but have no effect on particle maturation.

High-density lipoprotein metrics during midlife and future subclinical atherosclerosis in women: the SWAN HDL study.

The clinical utility of high-density lipoprotein cholesterol (HDL-C) in risk classification is limited, especially in midlife women. Novel metrics of HDL may better reflect this risk. We clustered a comprehensive profile of HDL metrics into favorable and unfavorable clusters and assessed how these two clusters are related to future subclinical atherosclerosis (carotid intima media thickness [cIMT], interadventitial diameter [IAD], and carotid plaque presence) in midlife women. Four hundred sixty-one women (baseline age: 50.4 [2.7] years; 272 White, 137 Black, 52 Chinese) from the Study of Women's Health Across the Nation HDL ancillary study who had baseline measures of HDL cholesterol efflux capacity (HDL-CEC), lipid contents (HDL-phospholipids [HDL-PL] and HDL triglycerides [HDL-Tg]), and HDL particle (HDL-P) distribution and size, followed by carotid ultrasound (average 12.9 [SD: 2.6] years later), were included. Using latent cluster analysis, women were clustered into a favorable (high HDL-CEC, HDL-PL, large and medium HDL-P, less HDL-Tg and small HDL-P, larger size) or an unfavorable HDL cluster (low HDL-CEC, HDL-PL, large and medium HDL-P, more HDL-Tg, and small HDL-P, smaller size) and then linked to future subclinical atherosclerosis using linear or logistic regression. The favorable HDL cluster was associated with lower cIMT, IAD, and odds of carotid plaque presence. These associations were attenuated by body mass index, except in Chinese women where the association with cIMT persisted (0.72 [0.63, 0.83]). The association between favorable HDL clusters and a better postmenopausal subclinical atherosclerosis profile is largely explained by body mass index; however, racial/ethnic differences may exist.

Abstract MP55: The Cardioprotective Feature of High-Density Lipoprotein Function Diminishes as Women Transition Through Menopause: The Swan HDL Study

Objective: HDL cholesterol efflux capacity (CEC) is a key metric of the cardioprotective HDL functionality. CEC generally rises as women traverse the menopause but it is unclear whether this rise reduces future CVD risk. We tested whether the association between CEC and subclinical CVD burden, measured using a composite subclinical CVD score based on carotid-intima media thickness (c-IMT), carotid-femoral pulse wave velocity (cf-PWV) and presence of coronary artery calcium (CAC score ≥10), varies by time relative to the final menstrual period (FMP). Design: We included 279 women (at baseline: age 51±2.8 years; 68.5% White; 31.5% Black; 60.6% Pre-/perimenopausal) who had HDL metrics and subclinical CVD outcome measures measured once (N=115 [41.2%]) or twice (N=164 [58.8%]). The composite subclinical CVD score was computed using a factor analysis for mixed data approach (FactoMineR R package), which combines principal component analysis for continuous (c-IMT, cf-PWV) and multiple correspondence analysis for categorical data (CAC≥10). A linear mixed effects model was used to model the composite score of subclinical CVD and estimates were back transformed to the individual observed components. We tested the interaction between CEC and time relative to FMP in this model. Results: Higher CEC was associated with a lower composite subclinical CVD score at FMP in unadjusted analyses (Illustration). This association was negligible after adjustment for confounders. In all models, association of CEC varied by time relative to FMP such that the pre-FMP protective association of CEC diminishes after the FMP. This pattern was consistent across all components of the composite score (Illustration). Conclusions: In women, higher CEC is associated with a lower risk of subclinical CVD burden before but not after menopause. High CEC is not a consistent indicator of CVD protection in women traversing menopause.

ANGPTL3 is a novel HDL component that regulates HDL function

BackgroundAngiopoietin-like protein 3 (ANGPTL3) is secreted by hepatocytes and inhibits lipoprotein lipase and endothelial lipase activity. Previous studies reported the correlation between plasma ANGPTL3 levels and high-density lipoprotein (HDL). Recently ANGPTL3 was found to preferentially bind to HDL in healthy human circulation. Here, we examined whether ANGPTL3, as a component of HDL, modulates HDL function and affects HDL other components in human and mice with non-diabetes or type 2 diabetes mellitus.MethodsHDL was isolated from the plasma of female non-diabetic subjects and type-2 diabetic mellitus (T2DM) patients. Immunoprecipitation, western blot, and ELISA assays were used to examine ANGPTL3 levels in HDL. Db/m and db/db mice, AAV virus mediated ANGPTL3 overexpression and knockdown models and ANGPTL3 knockout mice were used. The cholesterol efflux capacity induced by HDL was analyzed in macrophages preloaded with fluorescent cholesterol. The anti-inflammation capacity of HDL was assessed using flow cytometry to measure VCAM-1 and ICAM-1 expression levels in TNF-α-stimulated endothelial cells pretreated with HDL.ResultsANGPTL3 was found to bind to HDL and be a component of HDL in both non-diabetic subjects and T2DM patients. Flag-ANGPTL3 was found in the HDL of transgenic mice overexpressing Flag-ANGPTL3. ANGPLT3 of HDL was positively associated with cholesterol efflux in female non-diabetic controls (r = 0.4102, p = 0.0117) but not in female T2DM patients (r = − 0.1725, p = 0.3224). Lower ANGPTL3 levels of HDL were found in diabetic (db/db) mice compared to control (db/m) mice and were associated with reduced cholesterol efflux and inhibition of VCAM-1 and ICAM-1 expression in endothelial cells (p < 0.05 for all). Following AAV-mediated ANGPTL3 cDNA transfer in db/db mice, ANGPTL3 levels were found to be increased in HDL, and corresponded to increased cholesterol efflux and decreased ICAM-1 expression. In contrast, knockdown of ANGPTL3 levels in HDL by AAV-mediated shRNA transfer led to a reduction in HDL function (p < 0.05 for both). Plasma total cholesterol, total triglycerides, HDL-c, protein components of HDL and the cholesterol efflux function of HDL were lower in ANGPTL3−/− mice than ANGPTL3+/+ mice, suggesting that ANGPTL3 in HDL may regulate HDL function by disrupting the balance of protein components in HDL.ConclusionANGPTL3 was identified as a component of HDL in humans and mice. ANGPTL3 of HDL regulated cholesterol efflux and the anti-inflammatory functions of HDL in T2DM mice. Both the protein components of HDL and cholesterol efflux capacity of HDL were decreased in ANGPTL3−/− mice. Our findings suggest that ANGPTL3 in HDL may regulate HDL function by disrupting the balance of protein components in HDL. Our study contributes to a more comprehensive understanding of the role of ANGPTL3 in lipid metabolism.

HDL-C and apolipoprotein A-I are independently associated with skeletal muscle mitochondrial function in healthy humans.

Prior animal and cell studies have demonstrated a direct role of high-density lipoprotein (HDL) and apolipoprotein A-I (ApoA-I) in enhancing skeletal muscle mitochondrial function and exercise capacity. However, the relevance of these animal and cell investigations in humans remains unknown. Therefore, a cross-sectional study was conducted in 48 adults (67% female, 8% Black participants, age 39 ± 15.4 yr old) to characterize the associations between HDL measures, ApoA-I, and muscle mitochondrial function. Forearm muscle oxygen recovery time (tau) from postexercise recovery kinetics was used to assess skeletal muscle mitochondrial function. Lipoprotein measures were assessed by nuclear magnetic resonance. HDL efflux capacity was assessed using J774 macrophages, radiolabeled cholesterol, and apolipoprotein B-depleted plasma both with and without added cyclic adenosine monophosphate. In univariate analyses, faster skeletal muscle oxygen recovery time (lower tau) was significantly associated with higher levels of HDL cholesterol (HDL-C), ApoA-I, and larger mean HDL size, but not HDL cholesterol efflux capacity. Slower recovery time (higher tau) was positively associated with body mass index (BMI) and fasting plasma glucose (FPG). In multivariable linear regression analyses, higher levels of HDL-C and ApoA-I, as well as larger HDL size, were independently associated with faster skeletal muscle oxygen recovery times that persisted after adjusting for BMI and FPG (all P < 0.05). In conclusion, higher levels of HDL-C, ApoA-I, and larger mean HDL size were independently associated with enhanced skeletal muscle mitochondrial function in healthy humans.NEW & NOTEWORTHY Our study provides the first direct evidence supporting the beneficial role of HDL-C and ApoA-I on enhanced skeletal muscle mitochondrial function in healthy young to middle-aged humans without cardiometabolic disease.

Sex differences in the associations of HDL particle concentration and cholesterol efflux capacity with incident coronary artery disease in type 1 diabetes: The RETRO HDLc cohort study

In type 1 diabetes, women lose their relative protection (compared to men) against coronary artery disease (CAD), while high-density lipoprotein cholesterol (HDL-C) is less strongly associated with lower CAD risk in women. We aimed to assess whether sex differences in the HDL particle concentration (HDL-P) and cholesterol efflux capacity (CEC) association with CAD may explain these findings. HDL-P (calibrated differential ion mobility analysis) and total and ATP binding cassette transporter A1 (ABCA1)-specific CEC were quantified among 279 men and 271 women with type 1 diabetes (baseline mean age 27·8 years; diabetes duration, 19·6 years). Clinical CAD was defined as CAD death, myocardial infarction and/or coronary revascularization. Women had higher large HDL-P levels and marginally lower concentrations of small HDL-P and ABCA1-specific CEC than men. No sex differences were observed in extra-small HDL-P, medium HDL-P and total CEC. During a median follow-up of 26 years, 37·6 % of men and 35·8 % of women developed CAD (p = 0·72). In multivariable Cox models stratified by sex (pTotal HDL-P x sex interaction=0·01), HDL-P was negatively associated with CAD incidence in both sexes. However, associations were stronger in men, particularly for extra-small HDL-P (hazard ratio (HR)men=0·11, 95 % confidence interval (CI): 0·04-0·30; HRwomen=0·68, 95 % CI: 0·28-1·66; pinteraction=0·001). CEC did not independently predict CAD in either sex. Despite few absolute differences in HDL-P concentrations by sex, the HDL-P - CAD association was weaker in women, particularly for extra-small HDL-P, suggesting that HDL-P may be less efficient in providing atheroprotection in women and perhaps explaining the lack of a sex difference in CAD in type 1 diabetes.

Cuban policosanol improves high-density lipoprotein cholesterol efflux capacity in healthy Japanese subjects.

Policosanol supplementation has been reported to increase high-density lipoprotein (HDL)-cholesterol (HDL-C). However, the association between Cuban policosanol supplementation and HDL cholesterol efflux capacity (CEC), an important function of HDL, remains unclear. We performed a lipoprotein analysis investigating 32 Japanese healthy participants (placebo, n = 17 or policosanol supplementation for 12 weeks, n = 15) from a randomized Cuban policosanol clinical trial. First, HDL CEC and HDL-related factors were measured before and after policosanol supplementation. Then, through electron microscopy after ultracentrifugation and high-performance liquid chromatography, HDL morphology and subclass were analyzed, respectively. Finally, the effects of policosanol supplementation regarding HDL function, HDL-related factors, and HDL morphology/component were examined. Cuban policosanol considerably increased the HDL CEC and HDL-C and apolipoprotein A-I (ApoA-I) levels. Furthermore, policosanol supplementation led to larger HDL particles, increased cholesterol content in larger HDL particles, and reduced triglyceride content in smaller HDL particles. In participants with high baseline HDL-C levels, the policosanol effects for HDL CEC are observed. HDL CEC fluctuation induced by policosanol was highly associated with HDL-C and ApoA-I changes. In conclusion, for the first time, we demonstrated that policosanol supplementation increased the HDL CEC in healthy participants.

Flipped C-Terminal Ends of APOA1 Promote ABCA1-Dependent Cholesterol Efflux by Small HDLs.

Cholesterol efflux capacity (CEC) predicts cardiovascular disease independently of high-density lipoprotein (HDL) cholesterol levels. Isolated small HDL particles are potent promoters of macrophage CEC by the ABCA1 (ATP-binding cassette transporter A1) pathway, but the underlying mechanisms are unclear. We used model system studies of reconstituted HDL and plasma from control and lecithin-cholesterol acyltransferase (LCAT)-deficient subjects to investigate the relationships among the sizes of HDL particles, the structure of APOA1 (apolipoprotein A1) in the different particles, and the CECs of plasma and isolated HDLs. We quantified macrophage and ABCA1 CEC of 4 distinct sizes of reconstituted HDL. CEC increased as particle size decreased. Tandem mass spectrometric analysis of chemically cross-linked peptides and molecular dynamics simulations of APOA1, the major protein of HDL, indicated that the mobility of C-terminus of that protein was markedly higher and flipped off the surface in the smallest particles. To explore the physiological relevance of the model system studies, we isolated HDL from LCAT-deficient subjects, whose small HDLs (like reconstituted HDLs) are discoidal and composed of APOA1, cholesterol, and phospholipid. Despite their very low plasma levels of HDL particles, these subjects had normal CEC. In both the LCAT-deficient subjects and control subjects, the CEC of isolated extra-small HDL (a mixture of extra-small and small HDL by calibrated ion mobility analysis) was 3- to 5-fold greater than that of the larger sizes of isolated HDL. Incubating LCAT-deficient plasma and control plasma with human LCAT converted extra-small and small HDL particles into larger particles, and it markedly inhibited CEC. We present a mechanism for the enhanced CEC of small HDLs. In smaller particles, the C-termini of the 2 antiparallel molecules of APOA1 are "flipped" off the lipid surface of HDL. This extended conformation allows them to engage with ABCA1. In contrast, the C-termini of larger HDLs are unable to interact productively with ABCA1 because they form a helical bundle that strongly adheres to the lipid on the particle. Enhanced CEC, as seen with the smaller particles, predicts decreased cardiovascular disease risk. Thus, extra-small and small HDLs may be key mediators and indicators of the cardioprotective effects of HDL.

Seasonal Factors Are Associated with Activities of Enzymes Involved in High-Density Lipoprotein Metabolism among Pregnant Females in Ghana

BackgroundSmall-quantity lipid-based nutrient supplements (SQ-LNS) during pregnancy and postnatally were previously shown to improve high-density lipoprotein (HDL) cholesterol efflux capacity (CEC) and length in the children of supplemented mothers at 18 mo of age in the International Lipid-Based Nutrient Supplements (iLiNS) DYAD trial in Ghana. However, the effects of SQ-LNS on maternal HDL functionality during pregnancy are unknown. ObjectiveThe goal of this cross-sectional, secondary outcome analysis was to compare HDL function in mothers supplemented with SQ-LNS vs. iron and folic acid (IFA) during gestation. MethodsHDL CEC and the activities of 3 HDL-associated enzymes were analyzed in archived plasma samples (N = 197) from a subsample of females at 36 weeks of gestation enrolled in the iLiNS-DYAD trial in Ghana. Correlations between HDL function and birth outcomes, inflammatory markers C-reactive protein (CRP) and alpha-1-acid glycoprotein (AGP), and the effects of season were explored to determine the influence of these factors on HDL function in this cohort of pregnant females. ResultsThere were no statistically significant differences in HDL CEC, plasma lecithin-cholesterol acyltransferase (LCAT) activity, cholesteryl ester transfer protein (CETP) activity, or phospholipid transfer protein (PLTP) activity between mothers supplemented with SQ-LNS compared with IFA control, and no statistically significant relationships between maternal HDL function and childbirth outcomes. LCAT activity was negatively correlated with plasma AGP (R = -0.19, P = 0.007) and CRP (R = -0.28, P < 0.001), CETP and LCAT activity were higher during the dry season compared to the wet season, and PLTP activity was higher in the wet season compared to the dry season. ConclusionsMothers in Ghana supplemented with SQ-LNS compared with IFA during gestation did not have measurable differences in HDL functionality, and maternal HDL function was not associated with childbirth outcomes. However, seasonal factors and markers of inflammation were associated with HDL function, indicating that these factors had a stronger influence on HDL functionality than SQ-LNS supplementation during pregnancy. Clinical Trial Registry numberThe study was registered as NCT00970866. https://clinicaltrials.gov/study/NCT00970866

Long-term fasting effect on HDL cholesterol efflux and serum cholesterol loading capacity: Preliminary results from a single-arm interventional trial

Long-term fasting effect on HDL cholesterol efflux and serum cholesterol loading capacity: Preliminary results from a single-arm interventional trial

Integrated omics approach for the identification of HDL structure-function relationships in PCSK9-related familial hypercholesterolemia

The role of proprotein convertase subtilisin/kexin type 9 (PCSK9) in dyslipidemia may go beyond its immediate effects on low-density lipoprotein receptor (LDL-R) activity. This study aimed to assess PCSK9-derived alterations of high-density lipoprotein (HDL) physiology, which bear a potential to contribute to cardiovascular risk profile. HDL was isolated from 33 patients with familial autosomal dominant hypercholesterolemia (FH), including those carrying PCSK9 gain-of-function (GOF) genetic variants (FH-PCSK9, n=11), together with two groups of dyslipidemic patients employed as controls and carrying genetic variants in the LDL-R not treated (ntFH-LDLR, n=11) and treated (tFH-LDLR, n=11) with statins, and 11 normolipidemic controls. Biological evaluations paralleled by proteomic, lipidomic and glycomic analyses were applied to characterize functional and compositional properties of HDL. Multiple deficiencies in the HDL function were identified in the FH-PCSK9 group relative to dyslipidemic FH-LDLR patients and normolipidemic controls, which involved reduced antioxidative, antiapoptotic, anti-thrombotic and anti-inflammatory activities. By contrast, cellular cholesterol efflux capacity of HDL was unchanged. In addition, multiple alterations of the proteomic, lipidomic and glycomic composition of HDL were found in the FH-PCSK9 group. Remarkably, HDLs from FH-PCSK9 patients were systematically enriched in several lysophospholipids as well as in A2G2S2 (GP13) glycan and apolipoprotein A-IV. Based on network analysis of functional and compositional data, a novel mosaic structure-function model of HDL biology involving FH was developed. Several metrics of anti-atherogenic HDL functionality are altered in FH-PCSK9 patients paralleled by distinct compositional alterations. These data provide a first-ever overview of the impact of GOF PCSK9 genetic variants on structure-function relationships in HDL.

327-OR: Smaller HDL Particles and ABCA1 Cholesterol Efflux Capacity Predict Incident Proliferative Retinopathy Only among Men with Type 1 Diabetes

Clinical studies have provided evidence for a potential role of dyslipidemia in the development of retinopathy in type 1 diabetes. Existing evidence, however, is generally based on conventional lipid analysis and/or cross-sectional study designs. We therefore assessed the prospective association of HDL particle concentration (HDL-P) and cholesterol efflux capacity (CEC) with incident proliferative diabetic retinopathy (PDR) in a cohort of childhood-onset type 1 diabetes. HDL-P (calibrated differential ion mobility analysis) and total and ABCA1-specific CEC (validated cell-based assays) were quantified in 186 men and 185 women with type 1 diabetes free of PDR (stereo fundus photography) at baseline (mean age 25.6 years; diabetes duration, 17.1 years). Women had higher large HDL-P than men; the concentrations of extra-small, small and medium HDL-P as well as both total and ABCA1 CEC were similar by sex. During a median follow-up of 28 years, 108 men and 100 women developed PDR. In multivariable Cox models stratified by sex, HDL-C did not predict PDR incidence in either sex. However, in addition to increased HbA1c, non-HDL-C, white blood cell count and albumin excretion rate, increased extra-small (HR=0.25, 95% CI=0.09-0.67) and small (HR=0.72, 95% CI=0.55-0.94) HDL-P concentrations and ABCA1 CEC (HR=0.80, 95% CI=0.64-0.998) negatively predicted PDR in men but not women, among whom HbA1c, hypertension and white blood cell count were the only consistent significant predictors of PDR. In conclusion, while extra-small and small HDL-P concentrations and ABCA1 CEC did not differ by sex in type 1 diabetes, they only predicted incident PDR in men, a finding similar to our previously reported results for coronary artery disease. Further research is warranted to better understand the role of HDL in the pathophysiology of PDR and why this appears to differ by sex in type 1 diabetes. Disclosure T.Costacou: None. R.G.Miller: None. T.J.Orchard: None. Funding National Institutes of Health (R01HL130153, R01DK034818)

Regulating the Size of Simvastatin-loaded Discoidal Reconstituted Highdensity Lipoprotein: Preparation, Characterization, and Investigation of Cellular Cholesterol Efflux.

Reverse cholesterol transportation is essential for high-density lipoprotein (HDL) particles to reduce the cholesterol burden of peripheral cells. Studies have shown that particle size plays a crucial role in the cholesterol efflux capacity of HDLs, and the reconstituted HDLs (rHDLs) possess a similar function to natural ones. The study aimed to investigate the effect of particle size on the cholesterol efflux capacity of discoidal rHDLs and whether drug loadings may have an influence on this effect. Different-sized simvastatin-loaded discoidal rHDLs (ST-d-rHDLs) resembling nascent HDL were prepared by optimizing key factors related to the sodium cholate of film dispersion-sodium cholate dialysis method with a single controlling factor. Their physicochemical properties, such as particle size, zeta potential, and morphology in vitro, were characterized, and their capacity of cellular cholesterol efflux in foam cells was evaluated. We successfully constructed discoidal ST-d-rHDLs with different sizes (13.4 ± 1.4 nm, 36.6 ± 2.6 nm, and 68.6 ± 3.8 nm) with over 80% of encapsulation efficiency and sustained drug release. Among them, the small-sized ST-d-rHDL showed the strongest cholesterol efflux capacity and inhibitory effect on intracellular lipid deposition in foam cells. In addition, the results showed that the loaded drug did not compromise the cellular cholesterol efflux capacity of different-sized ST-d-rHDL. Compared to the larger-sized ST-d-rHDLs, the small-sized ST-d-rHDL possessed enhanced cellular cholesterol efflux capacity similar to drug-free one, and the effect of particle size on cholesterol efflux was not influenced by the drug loading.

HDL Function and Atherosclerosis: Reactive Dicarbonyls as Promising Targets of Therapy.

Epidemiologic studies detected an inverse relationship between HDL (high-density lipoprotein) cholesterol (HDL-C) levels and atherosclerotic cardiovascular disease (ASCVD), identifying HDL-C as a major risk factor for ASCVD and suggesting atheroprotective functions of HDL. However, the role of HDL-C as a mediator of risk for ASCVD has been called into question by the failure of HDL-C-raising drugs to reduce cardiovascular events in clinical trials. Progress in understanding the heterogeneous nature of HDL particles in terms of their protein, lipid, and small RNA composition has contributed to the realization that HDL-C levels do not necessarily reflect HDL function. The most examined atheroprotective function of HDL is reverse cholesterol transport, whereby HDL removes cholesterol from plaque macrophage foam cells and delivers it to the liver for processing and excretion into bile. Indeed, in several studies, HDL has shown inverse associations between HDL cholesterol efflux capacity and ASCVD in humans. Inflammation plays a key role in the pathogenesis of atherosclerosis and vulnerable plaque formation, and a fundamental function of HDL is suppression of inflammatory signaling in macrophages and other cells. Oxidation is also a critical process to ASCVD in promoting atherogenic oxidative modifications of LDL (low-density lipoprotein) and cellular inflammation. HDL and its proteins including apoAI (apolipoprotein AI) and PON1 (paraoxonase 1) prevent cellular oxidative stress and LDL modifications. Importantly, HDL in humans with ASCVD is oxidatively modified rendering HDL dysfunctional and proinflammatory. Modification of HDL with reactive carbonyl species, such as malondialdehyde and isolevuglandins, dramatically impairs the antiatherogenic functions of HDL. Importantly, treatment of murine models of atherosclerosis with scavengers of reactive dicarbonyls improves HDL function and reduces systemic inflammation, atherosclerosis development, and features of plaque instability. Here, we discuss the HDL antiatherogenic functions in relation to oxidative modifications and the potential of reactive dicarbonyl scavengers as a therapeutic approach for ASCVD.

Low concentrations of medium-sized HDL particles predict incident CVD in chronic kidney disease patients

Patients with chronic kidney disease (CKD) are at high risk for CVD. However, traditional CVD risk factors cannot completely explain the increased risk. Altered HDL proteome is linked with incident CVD in CKD patients, but it is unclear whether other HDL metrics are associated with incident CVD in this population. In the current study, we analyzed samples from two independent prospective case-control cohorts of CKD patients, the Clinical Phenotyping and Resource Biobank Core (CPROBE) and the Chronic Renal Insufficiency Cohort (CRIC). We measured HDL particle sizes and concentrations (HDL-P) by calibrated ion mobility analysis and HDL cholesterol efflux capacity (CEC) by cAMP-stimulated J774 macrophages in 92 subjects from the CPROBE cohort (46 CVD and 46 controls) and in 91 subjects from the CRIC cohort (34 CVD and 57 controls). We tested associations of HDL metrics with incident CVD using logistic regression analysis. No significant associations were found for HDL-C or HDL-CEC in either cohort. Total HDL-P was only negatively associated with incident CVD in the CRIC cohort in unadjusted analysis. Among the six sized HDL subspecies, only medium-sized HDL-P was significantly and negatively associated with incident CVD in both cohorts after adjusting for clinical confounders and lipid risk factors with odds ratios (per 1-SD) of 0.45 (0.22–0.93, P = 0.032) and 0.42 (0.20–0.87, P = 0.019) for CPROBE and CRIC cohorts, respectively. Our observations indicate that medium-sized HDL-P—but not other-sized HDL-P or total HDL-P, HDL-C, or HDL-CEC—may be a prognostic cardiovascular risk marker in CKD.

Preparative Electrophoresis for HDL Particle Size Separation and Intact-Mass Apolipoprotein Proteoform Analysis.

The most abundant proteins on high-density lipoproteins (HDLs), apolipoproteins A-I (APOA1) and A-II (APOA2), are determinants of HDL function with 15 and 9 proteoforms (chemical-structure variants), respectively. The relative abundance of these proteoforms in human serum is associated with HDL cholesterol efflux capacity, and cholesterol content. However, the association between proteoform concentrations and HDL size is unknown. We employed a novel native-gel electrophoresis technique, clear native gel-eluted liquid fraction entrapment electrophoresis (CN-GELFrEE) paired with mass spectrometry of intact proteins to investigate this association. Pooled serum was fractionated using acrylamide gels of lengths 8 and 25 cm. Western blotting determined molecular diameter and intact-mass spectrometry determined proteoform profiles of each fraction. The 8- and 25 cm experiments generated 19 and 36 differently sized HDL fractions, respectively. The proteoform distribution varied across size. Fatty-acylated APOA1 proteoforms were associated with larger HDL sizes (Pearson's R = 0.94, p = 4 × 10-7) and were approximately four times more abundant in particles larger than 9.6 nm than in total serum; HDL-unbound APOA1 was acylation-free and contained the pro-peptide proAPOA1. APOA2 proteoform abundance was similar across HDL sizes. Our results establish CN-GELFrEE as an effective lipid-particle separation technique and suggest that acylated proteoforms of APOA1 are associated with larger HDL particles.

Preeclampsia Affects Lipid Metabolism and HDL Function in Mothers and Their Offspring.

Preeclampsia (PE) is linked to an overall increased cardiovascular risk for both the mother and child. Functional impairment of high-density lipoproteins (HDL) may contribute to the excess cardiovascular risk associated with PE. In this study, we investigated the effects of PE on maternal and neonatal lipid metabolism, and the parameters of HDL composition and function. The study cohort included 32 normotensive pregnant women, 18 women diagnosed with early-onset PE, and 14 women with late-onset PE. In mothers, early- and late-onset PE was associated with atherogenic dyslipidemia, characterized by high plasma triglycerides and low HDL-cholesterol levels. We observed a shift from large HDL to smaller HDL subclasses in early-onset PE, which was associated with an increased plasma antioxidant capacity in mothers. PE was further associated with markedly increased levels of HDL-associated apolipoprotein (apo) C-II in mothers, and linked to the triglyceride content of HDL. In neonates of early-onset PE, total cholesterol levels were increased, whereas HDL cholesterol efflux capacity was markedly reduced in neonates from late-onset PE. In conclusion, early- and late-onset PE profoundly affect maternal lipid metabolism, potentially contributing to disease manifestation and increased cardiovascular risk later in life. PE is also associated with changes in neonatal HDL composition and function, demonstrating that complications of pregnancy affect neonatal lipoprotein metabolism.

Associations between Endothelial Lipase, High-Density Lipoprotein, and Endothelial Function Differ in Healthy Volunteers and Metabolic Syndrome Patients.

Metabolic syndrome (MS) is characterized by endothelial- and high-density lipoprotein (HDL) dysfunction and increased endothelial lipase (EL) serum levels. We examined the associations between EL serum levels, HDL (serum levels, lipid content, and function), and endothelial function in healthy volunteers (HV) and MS patients. Flow-mediated dilation (FMD), nitroglycerin-mediated dilation (NMD), serum levels of HDL subclasses (measured by nuclear magnetic resonance (NMR) spectroscopy), and EL serum levels differed significantly between HV and MS patients. The serum levels of triglycerides in large HDL particles were significantly positively correlated with FMD and NMD in HV, but not in MS patients. Cholesterol (C) and phospholipid (PL) contents of large HDL particles, calculated as HDL1-C/HDL1-apoA-I and HDL1-PL/HDL1-apoA-I, respectively, were significantly negatively correlated with FMD in HV, but not in MS patients. Cholesterol efflux capacity and arylesterase activity of HDL, as well as EL, were correlated with neither FMD nor NMD. EL was significantly negatively correlated with HDL-PL/HDL-apoA-I in HV, but not in MS patients, and with serum levels of small dense HDL containing apolipoprotein A-II in MS patients, but not in HV. We conclude that MS modulates the association between HDL and endothelial function, as well as between EL and HDL. HDL cholesterol efflux capacity and arylesterase activity, as well as EL serum levels, are not associated with endothelial function in HV or MS patients.

HDL cholesterol efflux capacity and phospholipid content are associated with the severity of acute ischemic stroke and predict its outcome

Background/AimsImpaired high-density lipoprotein (HDL) function and composition are more strongly related to cardiovascular morbidity than HDL concentration. However, it is unclear whether HDL function and composition predict ischemic stroke severity and outcome. We aimed to evaluate these associations. MethodsWe prospectively studied 199 consecutive patients who were admitted with acute ischemic stroke. The severity of stroke was evaluated at admission with the National Institutes of Health Stroke Scale (NIHSS). Severe stroke was defined as NIHSS ≥ 5. The outcome was assessed with dependency at discharge (modified Rankin scale 2–5) and in-hospital mortality. Cholesterol efflux capacity (CEC), phospholipid levels, lecithin:cholesterol acyl transferase (LCAT)-phospholipase activity, paraoxonase-1 (PON1)-arylesterase activity and serum amyloid A1 (SAA1) content of HDL were measured. ResultsCEC, phospholipid levels and LCAT-phospholipase activity of HDL were lower and SAA1 content of HDL was higher in patients with severe stroke. Patients who were dependent at discharge had lower CEC, PON1-arylesterase activity, phospholipid content and LCAT-phospholipase activity of HDL and higher HDL-SAA1 content. Independent predictors of dependency at discharge were the NIHSS at admission (RR 2.60, 95% CI 1.39–4.87), lipid-lowering treatment (RR 0.17, 95% CI 0.01–0.75), HDL-CEC (RR 0.21, 95% CI 0.05–0.87) and HDL-associated PON1-arylesterase activity (RR 0.95, 95% CI 0.91–0.99). In patients who died during hospitalization, phospholipids, LCAT-phospholipase and PON1-arylesterase activities of HDL were lower. ConclusionsChanges in CEC and composition of HDL appear to be associated with the severity and outcome of acute ischemic stroke and could represent biomarkers that may inform risk stratification and management strategies in these patients.

Obesity Affects Maternal and Neonatal HDL Metabolism and Function.

Pregravid obesity is one of the major risk factors for pregnancy complications such as gestational diabetes mellitus (GDM) and an increased risk of cardiovascular events in children of affected mothers. However, the biological mechanisms that underpin these adverse outcomes are not well understood. High-density lipoproteins (HDLs) are antiatherogenic by promoting the efflux of cholesterol from macrophages and by suppression of inflammation. Functional impairment of HDLs in obese and GDM-complicated pregnancies may have long-term effects on maternal and offspring health. In the present study, we assessed metrics of HDL function in sera of pregnant women with overweight/obesity of the DALI lifestyle trial (prepregnancy BMI ≥ 29 kg/m2) and women with normal weight (prepregnancy BMI < 25 kg/m2), as well as HDL functionalities in cord blood at delivery. We observed that pregravid obesity was associated with impaired serum antioxidative capacity and lecithin−cholesterol acyltransferase activity in both mothers and offspring, whereas maternal HDL cholesterol efflux capacity was increased. Interestingly, functionalities of maternal and fetal HDL correlated robustly. GDM did not significantly further alter the parameters of HDL function and metabolism in women with obesity, so obesity itself appears to have a major impact on HDL functionality in mothers and their offspring.