HDL Cholesterol Efflux Capacity Research Articles

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.

Gestational Hypertension and High-Density Lipoprotein Function: An Explorative Study in Overweight/Obese Women of the DALI Cohort.

Gestational hypertension (GHTN) is associated with an increased cardiovascular risk for mothers and their offspring later in life. High-density lipoproteins (HDL) are anti-atherogenic by promoting efflux of cholesterol from macrophages and suppression of endothelial cell activation. Functional impairment of HDL in GHTN-complicated pregnancies may affect long-term health of both mothers and offspring. We studied functional parameters of maternal and neonatal HDL in 192 obese women (pre-pregnancy BMI ≥ 29), who were at high risk for GHTN. Maternal blood samples were collected longitudinally at &lt;20 weeks, at 24-28 and 35-37 weeks of gestation. Venous cord blood was collected immediately after birth. Maternal and cord blood were used to determine functional parameters of HDL, such as HDL cholesterol efflux capacity, activity of the vaso-protective HDL-associated enzyme paraoxonase-1, and levels of the HDL-associated anti-inflammatory apolipoprotein (apo)M. In addition, we determined serum anti-oxidative capacity. Thirteen percent of the women were diagnosed with GHTN. While we found no changes in measures of HDL function in mothers with GHTN, we observed impaired HDL cholesterol efflux capacity and paraoxonase-1 activity in cord blood, while serum antioxidant capacity was increased. Of particular interest, increased maternal paraoxonase-1 activity and apoM levels in early pregnancy were associated with the risk of developing GHTN. GHTN significantly impairs HDL cholesterol efflux capacity as well as HDL PON1 activity in cord blood and could affect vascular health in offspring. Maternal paraoxonase-1 activity and apoM levels in early pregnancy associate with the risk of developing GHTN.

Scavenging dicarbonyls with 5′-O-pentyl-pyridoxamine increases HDL net cholesterol efflux capacity and attenuates atherosclerosis and insulin resistance

ObjectiveOxidative stress contributes to the development of insulin resistance (IR) and atherosclerosis. Peroxidation of lipids produces reactive dicarbonyls such as Isolevuglandins (IsoLG) and malondialdehyde (MDA) that covalently bind plasma/cellular proteins, phospholipids, and DNA leading to altered function and toxicity. We examined whether scavenging reactive dicarbonyls with 5′-O-pentyl-pyridoxamine (PPM) protects against the development of IR and atherosclerosis in Ldlr−/− mice. MethodsMale or female Ldlr−/− mice were fed a western diet (WD) for 16 weeks and treated with PPM versus vehicle alone. Plaque extent, dicarbonyl-lysyl adducts, efferocytosis, apoptosis, macrophage inflammation, and necrotic area were measured. Plasma MDA-LDL adducts and the in vivo and in vitro effects of PPM on the ability of HDL to reduce macrophage cholesterol were measured. Blood Ly6Chi monocytes and ex vivo 5-ethynyl-2′-deoxyuridine (EdU) incorporation into bone marrow CD11b+ monocytes and CD34+ hematopoietic stem and progenitor cells (HSPC) were also examined. IR was examined by measuring fasting glucose/insulin levels and tolerance to insulin/glucose challenge. ResultsPPM reduced the proximal aortic atherosclerosis by 48% and by 46% in female and male Ldlr−/− mice, respectively. PPM also decreased IR and hepatic fat and inflammation in male Ldlr−/− mice. Importantly, PPM decreased plasma MDA-LDL adducts and prevented the accumulation of plaque MDA- and IsoLG-lysyl adducts in Ldlr−/− mice. In addition, PPM increased the net cholesterol efflux capacity of HDL from Ldlr−/− mice and prevented both the in vitro impairment of HDL net cholesterol efflux capacity and apoAI crosslinking by MPO generated hypochlorous acid. Moreover, PPM decreased features of plaque instability including decreased proinflammatory M1-like macrophages, IL-1β expression, myeloperoxidase, apoptosis, and necrotic core. In contrast, PPM increased M2-like macrophages, Tregs, fibrous cap thickness, and efferocytosis. Furthermore, PPM reduced inflammatory monocytosis as evidenced by decreased blood Ly6Chi monocytes and proliferation of bone marrow monocytes and HSPC from Ldlr−/− mice. ConclusionsPPM has pleotropic atheroprotective effects in a murine model of familial hypercholesterolemia, supporting the therapeutic potential of reactive dicarbonyl scavenging in the treatment of IR and atherosclerotic cardiovascular disease.

Altered HDL Cholesterol Efflux Capacity and LCAT Activity is APOE‐Specific in Alzheimer Disease and Mild Cognitive Impairment Patients

AbstractBackgroundHigh‐density lipoproteins (HDL) in circulation perform a crucial role in maintaining cholesterol homeostasis by removing cholesterol from peripheral tissues for excretion. High HDL has been linked with a lower risk of developing Alzheimer’s Disease (AD). However, the concentration of HDL only partially accounts for the variation in the ability of HDL to perform their primary function to efflux cholesterol. Apolipoprotein E (APOE) is the strongest genetic risk factor for AD, and its role in regulating cholesterol is implicated in AD. However, the complex relationship between APOE genotype and the function of peripheral HDL in AD patients remains largely unknown.MethodWe isolated HDL from plasma of 194 age‐ and sex‐matched, ApoE genotyped participants (non‐demented controls, n = 83; mild cognitive impairment, n = 40; AD dementia, n = 71) using two‐step flotation ultracentrifugation, followed by size exclusion chromatography. HDL cholesterol efflux capacity (CEC) and lecithin‐cholesterol acyltransferase (LCAT) activity were measured. We further explored the relationships between HDL functional capacity and cognitive, functional, and imaging scores.ResultRegardless of diagnosis, ApoE3/E4 carriers had significantly lower CEC index (p = 0.003) and LCAT activity (p &lt; 0.001) vs. ApoE3/E3 carriers. When participants were stratified by APOE genotype and diagnosis, ApoE3/E3 MCI patients had significantly lower CEC index than controls (p = 0.042). In contrast, the CEC index of ApoE3/E4 AD patients was paradoxically increased compared to controls (p = 0.016). ApoE3/E3 MCI and AD patients had lower LCAT activity than controls (p = 0.012 and p = 0.004, respectively), but there were no differences in LCAT activity in ApoE3/E4 participants by diagnosis group. LCAT activity was positively correlated with verbal memory score (p = 0.033) and negatively correlated with clinical dementia rating (p = 0.025).ConclusionTo our knowledge, our study revealed for the first time an APOE genotype‐dependent alteration in peripheral HDL functional capacity among AD and MCI patients compared with non‐demented controls and an association between HDL LCAT activity and cognitive and functional scores.

High-density lipoprotein cholesterol efflux capacity in patients with obstructive sleep apnea and its relation with disease severity

BackgroundObstructive sleep apnea (OSA) is linked to an accelerated risk of cardiovascular disease (CVD). Some key CVD risk factors are present in patients suffering from OSA such as hypertension, inflammation, oxidative stress, and dyslipidemia. High-density lipoprotein (HDL) cholesterol efflux capacity (CEC) is proposed as a reliable biomarker of HDL function and the present study aimed to quantify this biomarker in patients with OSA.MethodsATP binding cassette subfamily A member 1 (ABCA1), non-ABCA1, and total CEC were determined in 69 polysomnographic-confirmed OSA patients and 23 controls. Moreover, paraoxonase (PON) activities, high-sensitivity C-reactive protein (hsCRP), apolipoprotein B (apo B), and apolipoprotein A-I (apo A-I) circulating levels were quantified in the studied population.Results: All CEC measures were reduced in the OSA group compared to the control group. Strikingly, ABCA1 CEC was diminished in severe OSA in comparison with mild OSA. Furthermore, PON activities and apo A-I showed lower levels, while hsCRP and apo B were elevated in OSA patients compared to controls. Moreover, ABCA1 CEC showed an inverse association with hsCRP and a positive association with apo A-I, while non-ABCA1 CEC presented an association with HDL-C.ConclusionThese results suggest the presence of an impaired HDL function in OSA. In particular, ABCA1 CEC was associated with disease severity and inflammation which could be a factor increasing the risk of CVD.

The Relationship of Alcohol Consumption and HDL Metabolism in the Multiethnic Dallas Heart Study

Small studies have suggested that moderate alcohol consumption increases HDL cholesterol (HDL-C) levels and cholesterol efflux capacity (CEC), a main anti-atherosclerotic HDL function. This study aimed to understand the degree to which alcohol intake is associated with various HDL markers in a large, multiethnic population cohort, the Dallas Heart Study (DHS), and whether alcohol modifies the link between HDL markers and atherosclerotic cardiovascular disease (ASCVD). Participants of the DHS were included if they had self-reported alcohol intake and CEC measurements (N=2,919). Alcohol intake was analyzed continuously (grams/week) and as an ordered categorical variable (never, past, light, moderate, heavy, and binge drinkers). HDL-C, CEC, HDL particle number (HDL-P), HDL particle size (HDL-size), and ApoA-I were the primary HDL measures. After adjustment for confounding variables, increasing continuous measure of alcohol intake was associated with increased levels of all HDL markers. Moreover, as compared to moderate drinkers, light drinkers had decreased levels of the HDL markers. In a large, multiethnic cohort, increased alcohol intake was associated with increased levels of multiple markers of HDL metabolism. However, the association of HDL markers with ASCVD risk as modified by alcohol consumption is unable to be determined in this low-risk cohort.

Early Midlife Cardiovascular Health Influences Future HDL Metrics in Women: The SWAN HDL Study.

Background Utility of high-density lipoprotein cholesterol (HDL-C) in assessing the antiatherogenic properties of HDL may be limited in midlife women. Novel metrics of HDL function, lipid contents, and subclasses may better reflect the atheroprotective capacities of HDL, supporting the need to evaluate how cardiovascular health affects these metrics in women. We assessed the relationship of early midlife Life's Simple 7 (LS7) score and its health behavior components with future HDL function (HDL-cholesterol efflux capacity), HDL-phospholipid, HDL-triglyceride, HDL particles (HDL-P) and size, and the relationship between LS7 score and changes in HDL metrics over time. Methods and Results We analyzed 529 women (baseline age: 46.4 [2.6] years, 57% White) from the SWAN HDL (Study of Women's Health Across the Nation HDL) study who had baseline LS7 followed by future repeated HDL metrics. Multivariable linear mixed models were used. Higher LS7 score was associated with favorable future HDL profile (higher HDL-phospholipid, total HDL-P and large HDL-P, lower HDL-triglyceride, and larger overall HDL size). Ideal body mass index was associated with higher HDL-cholesterol efflux capacity, HDL-phospholipid, and large HDL-P, lower HDL-triglyceride and small HDL-P, and larger overall HDL size. Ideal physical activity was associated with higher HDL-phospholipid, and total, large, and medium HDL-P. Ideal smoking was associated with less HDL-triglycerides. Diet was not related to HDL metrics. Higher LS7 score and ideal body mass index were associated with slower progression of HDL size over time. Conclusions Novel HDL metrics may better reflect the clinical utility of HDL. Improving lifestyle at midlife, particularly maintaining ideal body mass index, is associated with better future HDL phenotype.

High levels of oxidized fatty acids in HDL impair the antioxidant function of HDL in patients with diabetes.

Previous studies demonstrate that the antioxidant functions of high-density lipoprotein (HDL) are impaired in diabetic patients. The composition of HDL plays an important role in maintaining the normal functionality of HDL. In this study, we compared the levels of oxidized fatty acids in HDL from diabetic subjects and non-diabetic healthy controls, aiming to investigate the role of oxidized fatty acids in the antioxidant property of HDL. HDL was isolated from healthy subjects (n=6) and patients with diabetes (n=6, hemoglobin A1c ≥ 9%, fasting glucose ≥ 7 mmol/L) using a dextran sulfate precipitation method. Cholesterol efflux capacity mediated by HDL was measured on THP-1 derived macrophages. The antioxidant capacity of HDL was evaluated with dichlorofluorescein-based cellular assay in human aortic endothelial cells. Oxidized fatty acids in HDL were determined by liquid chromatography-tandem mass spectrometry. The correlations between the levels of oxidized fatty acids in HDL and the endothelial oxidant index in cells treated with HDLs were analyzed through Pearson's correlation analyses, and the effects of oxidized fatty acids on the antioxidant function of HDL were verified in vitro. The cholesterol efflux capacity of HDL and the circulating HDL-cholesterol were similar in diabetic patients and healthy controls, whereas the antioxidant capacity of HDL was significantly decreased in diabetic patients. There were higher levels of oxidized fatty acids in HDL isolated from diabetic patients, which were strongly positively correlated with the oxidant index of cells treated with HDLs. The addition of a mixture of oxidized fatty acids significantly disturbed the antioxidant activity of HDL from healthy controls, while the apolipoprotein A-I mimetic peptide D-4F could restore the antioxidant function of HDL from diabetic patients. HDL from diabetic patients displayed substantially impaired antioxidant activity compared to HDL from healthy subjects, which is highly correlated with the increased oxidized fatty acids levels in HDL.

Early time-restricted feeding improves high-density lipoprotein amount and function in nonhuman primates, without effects on body composition.

Time-restricted feeding (TRF), whereby caloric intake is limited to a <12-hour window, is a potential regimen to ameliorate metabolic syndrome and cardiovascular disease (CVD) risk co-occurring with aging and with obesity. Early TRF (eTRF; early morning feeding followed by overnight fasting) times calorie consumption with hepatic circadian gene expression rhythms. Brief TRF trials demonstrate that high-density lipoprotein (HDL) cholesterol increases similar to diet/exercise interventions, which may impart beneficial CVD effects. Using a nonhuman primate (NHP) model, the efficacy of eTRF to raise HDL and increase plasma cholesterol efflux capacity (CEC) (primarily mediated by cholesterol efflux to HDL particles, a process that is inversely associated with CVD risk) was examined. Adult (8-16 years old, n=25) and geriatric (≥17 years old) NHPs were randomized to ad libitum feeding or eTRF for 12 months, and relevant body composition, glycemic control, and plasma HDL cholesterol levels and CEC were measured. Impaired CEC was found in geriatric NHPs. eTRF induced larger-sized HDL particles, increased HDL apolipoprotein A-1 content, lowered triglyceride concentrations, and increased plasma CEC (primarily to HDL particles) in both adult and geriatric NHPs without changes in glycemic control or body composition. A beneficial effect of eTRF on increasing HDL CEC in NHPs was demonstrated.

Changes in HDL cholesterol, particles, and function associate with pediatric COVID-19 severity.

BackgroundMyriad roles for high-density lipoprotein (HDL) beyond atheroprotection include immunologic functions implicated in the severity of coronavirus disease-2019 (COVID-19) in adults. We explored whether there is an association between HDL and COVID-19 severity in youth.MethodsA pediatric cohort (N = 102), who tested positive for COVID-19 across a range of disease manifestations from mild or no symptoms, to acute severe symptoms, to the multisystem inflammatory syndrome of children (MIS-C) was identified. Clinical data were collected from the medical record and reserve plasma aliquots were assessed for lipoproteins by NMR spectroscopy and assayed for HDL functional cholesterol efflux capacity (CEC). Findings were compared by COVID-19 status and symptom severity. Lipoprotein, NMR spectroscopy and CEC data were compared with 30 outpatient COVID negative children.ResultsDecreasing HDL cholesterol (HDL-c), apolipoprotein AI (ApoA-I), total, large and small HDL particles and HDL CEC showed a strong and direct linear dose-response relationship with increasing severity of COVID-19 symptoms. Youth with mild or no symptoms closely resembled the uninfected. An atypical lipoprotein that arises in the presence of severe hepatic inflammation, lipoprotein Z (LP-Z), was absent in COVID-19 negative controls but identified more often in youth with the most severe infections and the lowest HDL parameters. The relationship between HDL CEC and symptom severity and ApoA-I remained significant in a multiply adjusted model that also incorporated age, race/ethnicity, the presence of LP-Z and of GlycA, a composite biomarker reflecting multiple acute phase proteins.ConclusionHDL parameters, especially HDL function, may help identify youth at risk of more severe consequences of COVID-19 and other novel infectious pathogens.

Low HDL Cholesterol Efflux Capacity Indicates a Fatal Course of COVID-19.

Plasma membrane cholesterol is required for proper trafficking and localization of receptors that facilitate severe acute respiratory syndrome coronavirus 2 infection. High-density lipoproteins (HDL) mobilize plasma membrane cholesterol, and HDL-cholesterol levels are associated with the severity of COVID-19 disease and mortality. However, HDL-cholesterol levels poorly reflect the function of this complex family of particles, and a detailed assessment of COVID-19-associated changes in HDL functionality and its prognostic value is lacking. In the present study, we assessed HDL cholesterol efflux capacity, HDL anti-inflammatory and antioxidant properties, and changes in HDL composition and metabolism in COVID-19 (n = 48) and non-COVID pneumonia patients (n = 32). COVID-19 infection markedly reduced the activity of lecithin-cholesteryl-acyltransferase and functional parameters of HDL, such as the cholesterol efflux capacity, arylesterase activity of paraoxonase 1, and anti-oxidative capacity of apoB-depleted serum when compared to non-COVID pneumonia at baseline, paralleled by markedly reduced levels of HDL-cholesterol. Of particular interest, low HDL cholesterol efflux capacity was associated with increased mortality risk in COVID-19 patients, independent of HDL-C levels. Our results highlight profound effects of COVID-19 infection on HDL function, metabolism, and composition. Low HDL cholesterol efflux capacity indicates a fatal course of COVID-19, independent of HDL-cholesterol levels.

Plasma HDL pattern, cholesterol efflux and cholesterol loading capacity of serum in carriers of a novel missense variant (Gly176Trp) of endothelial lipase

Loss of function variants of LIPG gene encoding endothelial lipase (EL) are associated with primary hyperalphalipoproteinemia (HALP), a lipid disorder characterized by elevated plasma levels of high density lipoprotein cholesterol (HDL-C). Aim of the study was the phenotypic and genotypic characterization of a family with primary HALP. HDL subclasses distribution was determined by polyacrylamide gradient gel electrophoresis. Serum content of preβ-HDL was assessed by (2D)-electrophoresis. Cholesterol efflux capacity (CEC) of serum mediated by ABCA1, ABCG1 or SR-BI was assessed using cells expressing these proteins. Cholesterol loading capacity (CLC) of serum was assayed using cultured human macrophages. Next generation sequencing was used for DNA analysis. Plasma EL mass was determined by ELISA. Three family members had elevated plasma HDL-C, apoA-I and total phospholipids, as well as a reduced content of preβ-HDL. These subjects were heterozygous carriers of a novel variant of LIPG gene [c.526 G>T, p.(Gly176Trp)] found to be deleterious in silico. Plasma EL mass in carriers was lower than in controls. CEC of sera mediated by ABCA1 and ABCG1 transporters was substantially reduced in the carriers. This effect was maintained after correction for serum HDL concentration. The sera of carriers were found to have a higher CLC in cultured human macrophages than control sera. The novel p.(Gly176Trp) variant of endothelial lipase is associated with changes in HDL composition and subclass distribution as well as with functional changes affecting cholesterol efflux capacity of serum which suggest a defect in the early steps of revere cholesterol transport.

Hypercholesterolemia-Induced HDL Dysfunction Can Be Reversed: The Impact of Diet and Statin Treatment in a Preclinical Animal Model.

High-density lipoproteins (HDL) undergo adverse remodeling and loss of function in the presence of comorbidities. We assessed the potential of lipid-lowering approaches (diet and rosuvastatin) to rescue hypercholesterolemia-induced HDL dysfunction. Hypercholesterolemia was induced in 32 pigs for 10 days. Then, they randomly received one of the 30-day interventions: (I) hypercholesterolemic (HC) diet; (II) HC diet + rosuvastatin; (III) normocholesterolemic (NC) diet; (IV) NC diet + rosuvastatin. We determined cholesterol efflux capacity (CEC), antioxidant potential, HDL particle number, HDL apolipoprotein content, LDL oxidation, and lipid levels. Hypercholesterolemia time-dependently impaired HDL function (−62% CEC, −11% antioxidant index (AOI); p < 0.01), increased HDL particles numbers 2.8-fold (p < 0.0001), reduced HDL-bound APOM (−23%; p < 0.0001), and increased LDL oxidation 1.7-fold (p < 0.0001). These parameters remained unchanged in animals on HC diet alone up to day 40, while AOI deteriorated up to day 25 (−30%). The switch to NC diet reversed HDL dysfunction, restored apolipoprotein M content and particle numbers, and normalized cholesterol levels at day 40. Rosuvastatin improved HDL, AOI, and apolipoprotein M content. Apolipoprotein A-I and apolipoprotein C-III remained unchanged. Lowering LDL-C levels with a low-fat diet rescues HDL CEC and antioxidant potential, while the addition of rosuvastatin enhances HDL antioxidant capacity in a pig model of hypercholesterolemia. Both strategies restore HDL-bound apolipoprotein M content.