High-density Lipoprotein Subclasses Research Articles

High-Density Lipoproteins from Coronary Artery Disease and Aortic Valve Stenosis Patients Differentially Regulate Gene Expression in a Model of Cardiac Adipocytes

Previous reports have described a statistical association between high-density lipoproteins (HDL) subclasses and the expression of genes coding for pro-calcifying proteins in the epicardial adipose tissue of patients with coronary artery disease (CAD) and aortic valvular stenosis (AVS). These results suggest a causal relationship between HDL and the regulation of gene expression in epicardial adipose tissue. However, there is no experimental evidence that supports this causal relationship. Therefore, we explored the effect of HDL isolated from CAD or AVS patients on the expression of OPN, BMP2, and BMP4, genes coding for proteins related to calcification, osteopontin, and bone morphogenetic proteins -2 and -4, respectively, and LEP, UCP, and PER, coding for leptin, uncoupling protein-1, and perilipin-2, respectively, proteins that confer phenotypic characteristics to adipocytes. The experiments were performed using a novel model of cardiac adipocytes differentiated in vitro from stromal cells of rabbit cardiac adipose tissue. AVS or CAD patients’ HDL differentially modulated the expression of BMP4 and LEP, whereas HDL from both kinds of patients upregulated the OPN gene expression. A high concentration of triglycerides associated to small HDL and a higher concentration of phospholipids of large HDL from CAD patients than those from AVS individuals were the most remarkable structural differences. Finally, we demonstrated that cholesterol from reconstituted HDL was internalized to the adipocytes. The regulation of genes related to the secretory activity of cardiac adipocytes mediated by HDL has clinical implications as a potential therapeutic target for the prevention and treatment of CAD and AVS. In summary, the HDL isolated from the CAD and AVS patients differentially regulated gene expression in adipocytes by a mechanism that seems to be dependent on HDL lipid internalization to the cells and structural characteristics of the lipoproteins.

Analysis of TEM micrographs with deep learning reveals APOE genotype-specific associations between HDL particle diameter and Alzheimer's dementia.

High-density lipoprotein (HDL) particle diameter distribution is informative in the diagnosis of many conditions, including Alzheimer's disease (AD). However, obtaining an accurate HDL size measurement is challenging. We demonstrated the utility of measuring the diameter of more than 1,800,000 HDL particles with the deep learning model YOLOv7 (you only look once) from micrographs of 183 HDL samples, including patients with dementia or normal cognition (controls). This method was shown to be more efficient and accurate than conventional image analysis software. Using this method, we found a higher abundance of small HDLs in participants with dementia compared to controls in patients with the apolipoprotein E (APOE) ε3ε4 genotype, whereas patients with the APOE ε3ε3 genotype had higher variability in the abundance of different HDL subclasses. Our results show an example of accurate individual HDL particle diameter measurement for large-scale clinical samples, which can be expanded to characterize the relationship between disease risk and other nanoparticles in the sub-20-nm diameter size range.

Association of Small HDL Subclasses with Mortality Risk in Chronic Kidney Disease.

High-density lipoproteins (HDL) exist in various subclasses, with smaller HDL particles possessing the highest anti-oxidative and anti-inflammatory properties. Understanding the role of these specific subclasses in chronic kidney disease (CKD) could provide valuable insights into disease progression and potential therapeutic targets. In the present study, we assessed HDL subclass composition in 463 patients with CKD stage 2-4 using nuclear magnetic resonance spectroscopy. Over a mean follow-up period of 5.0 years, 18.6% of patients died. Compared to survivors, deceased patients exhibited significantly lower levels of cholesterol, ApoA-I, and ApoA-II within the small and extra-small (XS) HDL subclasses. Multivariable Cox regression analysis, adjusted for traditional cardiovascular and renal risk factors, demonstrated that reduced levels of XS-HDL-cholesterol, XS-HDL-ApoA-I, and XS-HDL-ApoA-II were independently associated with an increased risk of mortality. Furthermore, receiver operating characteristic analysis identified XS-HDL-ApoA-II as the most potent prognostic marker for mortality. In conclusion, reduced small and XS-HDL subclasses, especially XS-HDL-ApoA-II, are strongly associated with increased all-cause mortality risk in CKD patients. Assessment of HDL subclass distribution could provide valuable clinical information and help identify patients at high risk.

Impaired HDL antioxidant and anti-inflammatory functions are linked to increased mortality in acute heart failure patients

AimsAcute heart failure (AHF) is typified by inflammatory and oxidative stress responses, which are associated with unfavorable patient outcomes. Given the anti-inflammatory and antioxidant properties of high-density lipoprotein (HDL), this study sought to examine the relationship between impaired HDL function and mortality in AHF patients. The complex interplay between various HDL-related biomarkers and clinical outcomes remains poorly understood. MethodsHDL subclass distribution was quantified by nuclear magnetic resonance spectroscopy. Lecithin–cholesterol acyltransferase (LCAT) activity, cholesterol ester transfer protein (CETP) activity, and paraoxonase (PON-1) activity were assessed using fluorometric assays. HDL-cholesterol efflux capacity (CEC) was assessed in a validated assay using [3H]-cholesterol-labeled J774 macrophages. ResultsAmong the study participants, 74 (23.5 %) out of 315 died within three months after hospitalization due to AHF. These patients exhibited lower activities of the anti-oxidant enzymes PON1 and LCAT, impaired CEC, and lower concentration of small HDL subclasses, which remained significant after accounting for potential confounding factors. Smaller HDL particles, particularly HDL3 and HDL4, exhibited a strong association with CEC, PON1 activity, and LCAT activity. ConclusionsIn patients with AHF, impaired HDL CEC, HDL antioxidant and anti-inflammatory function, and impaired HDL metabolism are associated with increased mortality. Assessment of HDL function and subclass distribution could provide valuable clinical information and help identify patients at high risk.

Quantification of high-density lipoprotein particle number by proton nuclear magnetic resonance: don't believe the numbers.

Proton nuclear magnetic resonance (NMR) can rapidly assess lipoprotein concentrations and sizes in biological samples. It may be especially useful for quantifying high-density lipoprotein (HDL), which exhibits diverse particle sizes and concentrations. We provide a critical review of the strengths and limitations of NMR for quantifying HDL subclasses. Recent studies using NMR have shed light on HDL's role in various disorders, ranging from residual cardiovascular risk to host susceptibility to infection. However, accurately quantifying HDL particle number, size, and concentration (HDL-P) remains a challenge. Discrepancies exist between NMR and other methods such as gel electrophoresis, ion mobility analysis and size-exclusion chromatography in estimating the abundance of HDL species and the ratio of apolipoprotein A-I (APOA1) to HDL particles. NMR is a low-cost method for quantifying HDL-P that is readily applicable to clinical and translational studies. However, inconsistencies between the results of NMR quantification of HDL-P and other independent methods hinder the interpretation of NMR results. Because proton NMR apparently fails to accurately quantify the sizes and concentrations of HDL, the relevance of such studies to HDL biology poses challenges. This limits our understanding of pathophysiological implications of HDL-P as determined by NMR, particularly in determining cardiovascular disease (CVD) risk.

High-Density Lipoprotein Subclasses and Their Role in the Prevention and Treatment of Cardiovascular Disease: A Narrative Review.

The association between high-density lipoprotein cholesterol (HDL-C) and cardiovascular disease (CVD) is controversial. HDL-C is one content type of high-density lipoprotein (HDL). HDL consists of diverse proteins and lipids and can be classified into different subclasses based on size, shape, charge, and density, and can change dynamically in disease states. Therefore, HDL-C levels alone cannot represent HDLs' cardioprotective role. In this review, we summarized the methods for separating HDL subclasses, the studies on the association between HDL subclasses and cardiovascular risk (CVR), and the impact of lipid-modifying medications and nonpharmacological approaches (exercise training, dietary omega fatty acids, and low-density lipoprotein apheresis) on HDL subclasses. As HDL is a natural nanoplatform, recombinant HDLs (rHDLs) have been used as a delivery system in vivo by loading small interfering RNA, drugs, contrast agents, etc. Therefore, we further reviewed the HDL subclasses used in rHDLs and their advantages and disadvantages. This review would provide recommendations and guidance for future studies on HDL subclasses' cardioprotective roles.

Assessment of the diagnostic value of serum cathepsin S and its correlation with HDL subclasses in patients with non-Hodgkin's lymphoma.

Recent findings point to the key role of cathepsin S (CTSS) in the survival of malignant cells, as well as the significance of the anti-apoptotic properties of high-density lipoprotein (HDL) that contribute to enhanced cell survival. The purpose of this study is to analyse CTSS as a potential biomarker in lymphoma. Also, in order to better understand the role of CTSS in the origin and development of lymphoma, its association with cystatin C (Cys C), lipids, and inflammatory markers was analysed. The study included 90 subjects: 11 Hodgkin (HL) and 44 B-cell non-Hodgkin lymphoma (NHL) patients, as well as 35 healthy subjects. CTSS was determined using the Invitrogen ELISA kit (Thermo Fisher Scientific, Inc., Waltham, MA, USA). The non-denaturing 3%-31% polyacrylamide gradient gel electrophoresis method was used to separate plasma HDL particles. The level of CTSS was significantly higher in NHL patients than in control subjects: 12.20 (9.75-14.57) vs 9.97 (8.44-10.99), P<0.001. In NHL patients, there was a positive correlation between CTSS and the proportions of HDL3a, HDL3b, and the sum of the HDL3 subclasses (r=0.506, P<0.001; r=0.411, P=0.006, r=0.335, P=0.026, respectively). In addition, the area under the receiver operating characteristic curve (AUC curve) of CTSS was 0.766 (CI: 0.655-0.856) for NHL patients. There was no significant difference in CTSS values between the control group and patients with HL, nor significant correlations between CTSS and HDL subclasses in the HL group. CTSS is significantly elevated in patients with NHL and has the potential to be a new diagnostic bio - marker for the detection of NHL. Also, this study was the first to unveil the association between serum CTSS levels and the proportions of anti-apoptotic HDL3a and HDL3b subclasses in NHL patients.

Association between the proportion of HDL-cholesterol subclasses and the severity of coronary artery stenosis in patients with acute myocardial infarction

Past research has shown an inverse correlation between high-density lipoprotein (HDL) and coronary heart disease (CHD), while recent studies have shown that extremely high or low HDL levels increase the risk of cardiovascular death. To explore the relationships between HDL subtypes and the degree of coronary artery stenosis in patients with acute myocardial infarction (AMI). This was a single-center cross-sectional study. Ultimately, we included 1,200 adult participants with AMI hospitalized from 2017 to 2023. Patients were classified into mild and moderate-severe groups according to their Gensini score. Restricted cubic spline and multivariate logistic regression models were used to explore the associations between HDL subclasses and the severity of coronary stenosis. The adjusted odds ratios (ORs), 95% confidence intervals (CIs), and p values for HDL subclasses in the multivariate logistic model (adjusted for age, gender, hypertension status, diabetes status, stroke status, and kidney disease status) were as follows: HDL-2b: 0.97 (0.95-1.00, p= 0.018) and HDL-3: 0.98 (0.97-0.99, p= 0.008). Subgroup analysis revealed that HDL-3 exhibited a statistically significant impact on the severity of coronary stenosis among individuals <75 years of age and among men, and the influence of HDL-2b on the severity of coronary stenosis was statistically significant only in individuals aged ≥75 years. The relationship between reduced levels of HDL-2b and HDL-3 and the risk of coronary stenosis exhibited a linear pattern and was significantly modified by age. Subgroup analysis identified specific populations that warrant attention regarding HDL-2b and HDL-3.

A new risk factor for coronary artery disease can be detected by an ApoA1 mAb-based assay

BackgroundThis study aimed to find coronary artery disease (CAD) related apolipoprotein A1 (ApoA1) monoclonal antibody (mAb) and to evaluate the diagnostic value of the assay based on it. MethodsPatients with CAD diagnosed by coronary angiography (disease group, n = 180) and healthy subjects (control group, n = 199) were recruited. The correlation between methods and CAD were evaluated by Spearman’s rank correlation coefficients. Receiver operating characteristic (ROC) curve analysis was used to evaluate the auxiliary diagnostic value of methods for CAD. Odds ratios (ORs) of the test results in CAD were estimated using logistic regression analysis. ResultsMeasurements from an ApoA1 mAb were found significantly positively correlated with CAD (r = 0.243, P < 0.01), unlike the measurements from the ApoA1 pAb were negatively correlated with CAD (r = -0.341, P < 0.001). The areas under the ROC curve of the ApoA1 mAb and pAb measurements were 0.704 and 0.563, respectively, in patients with normal HDL-C levels. ApoA1 values from the mAb assay had a significant positive impact on CAD risk. ConclusionAn ApoA1 mAb-based assay can distinguish a high-density lipoprotein (HDL) subclass positively related to CAD, which can be used to improve and reappraise CAD risk assessment.

Total Outflow of High-Density Lipoprotein–Cholesteryl Esters from Plasma Is Decreased in a Model of 3/4 Renal Mass Reduction

(1) Background: Previous studies have enriched high-density lipoproteins (HDL) using cholesteryl esters in rabbits with a three-quarter reduction in functional renal mass, suggesting that the kidneys participate in the cholesterol homeostasis of these lipoproteins. However, the possible role of the kidneys in lipoprotein metabolism is still controversial. To understand the role of the kidneys in regulating the HDL lipid content, we determined the turnover of HDL-cholesteryl esters in rabbits with a three-quarter renal mass reduction. (2) Methods: HDL subclass characterization was conducted, and the kinetics of plasma HDL-cholesteryl esters, labeled with tritium, were studied in rabbits with a 75% reduction in functional renal mass (Ntx). (3) Results: The reduced renal mass triggered the enrichment of cholesterol, specifically cholesteryl esters, in HDL subclasses. The exchange of cholesteryl esters between HDL and apo B-containing lipoproteins (VLDL/LDL) was not significantly modified in Ntx rabbits. Moreover, the cholesteryl esters of HDL and VLDL/LDL fluxes from the plasmatic compartment tended to decrease, but they only reached statistical significance when both fluxes were added to the Nxt group. Accordingly, the fractional catabolic rate (FCR) of the HDL-cholesteryl esters was lower in Ntx rabbits, concomitantly with its accumulation in HDL subclasses, probably because of the reduced mass of renal cells requiring this lipid from lipoproteins.

Abstract 14972: Association Between CEC Measured by Immobilized Liposome-Bound Gel Beads Method and the Size of Lipid-Rich Coronary Artery Plaque

Introduction/Background: High-density lipoprotein (HDL) exerts cholesterol efflux capacity (CEC), and it ameliorates cardiovascular disease (CVD). CEC had been expected as a surrogate biomarker in addition to HDL cholesterol (HDL-C), which has been found not always to reflect the CVD risk. However, the procedures of the conventional CEC assays were too complex to be introduced into clinical practice because of cell-based assay. Given this situation, we invented novel cell-free CEC assay named immobilized liposome-bound gel beads (ILG) method. ILG method utilizes liposomes which contain fluorescence labeled cholesterol instead of lipid loaded foam cells, and has advantage of simplicity of procedure and accuracy. Reserch Question/Hypothesis: Does ILG method show some associations between CEC and HDL subclass, and also reflect the condition of coronary artery plaque? Goals/Aim: We aim to demonstrate CEC by ILG method has clinical significance for assessment of the CVD risk. Methods/Approach: Patients who underwent diagnostic catheterization or percutaneous coronary intervention were enrolled, and 61 patients were examined through CEC analysis by ILG method and assessment of coronary artery plaque by optical coherence tomography (OCT) imaging. Large lipid-rich plaque was defined as a lipid plaque with a lipid arc ≥180°and lipid length ≥5 mm. Serum HDL subclass was analyzed by enzymatic assay (Denka). We defined the ratio apolipoprotein E(apoE)-containing HDL-C to HDL-C as %apoE, and we also calculated the value of HDL 3 -C/HDL 2 -C, and classified HDL 3 - or HDL 2 -rich group. Results/Data: HDL-C was positively associated with %apoE, and CEC of apoE-rich patients was higher than that of apoE-poor patients. This correlation was maintained after classified based on size of HDL. CEC and %apoE in patients with large lipid-rich plaque were significantly lower than in those in without. In contrast, there was no significant difference in HDL-C and LDL-C. Conclusion: In present study, ILG method showed that apoE has some influence on CEC, and CEC was inversely correlated with size of lipid-rich plaque. These results implied that ILG method, suitable CEC assay for clinical site, might be useful to assess the CVD risk.

Low levels of small HDL particles predict but do not influence risk of sepsis

BackgroundLow levels of high-density lipoprotein (HDL) cholesterol have been associated with higher rates and severity of infection. Alterations in inflammatory mediators and infection are associated with alterations in HDL cholesterol. It is unknown whether the association between HDL and infection is present for all particle sizes, and whether the observed associations are confounded by IL-6 signalling.MethodsIn the UK Biobank, ~ 270,000 individuals have data on HDL subclasses derived from nuclear magnetic resonance analysis. We estimated the association of particle count of total HDL and HDL subclasses (small, medium, large, and extra-large HDL) with sepsis, sepsis-related death, and critical care admission in a Cox regression model. We subsequently utilised genetic data from UK Biobank and FinnGen to perform Mendelian randomisation (MR) of each HDL subclass and sepsis to test for a causal relationship. Finally, we explored the role of IL-6 signalling as a potential causal driver of changes in HDL subclasses.ResultsIn observational analyses, higher particle count of small HDL was associated with protection from sepsis (Hazard ratio, HR 0.80; 95% CI 0.74–0.86, p = 4 × 10–9 comparing Quartile 4, highest quartile of HDL to Quartile 1, lowest quartile of HDL), sepsis-related death (HR 0.80; 95% CI 0.74–0.86, p = 2 × 10–4), and critical care admission with sepsis (HR 0.72 95% CI 0.60–0.85, p = 2 × 10–4). Parallel associations with other HDL subclasses were likely driven by changes in the small HDL compartment. MR analyses did not strongly support causality of small HDL particle count on sepsis incidence (Odds ratio, OR 0.98; 95% CI 0.89–1.07, p = 0.6) or death (OR 0.94, 95% CI 0.75–1.17, p = 0.56), although the estimate on critical care admission with sepsis supported protection (OR 0.73, 95% CI 0.57–0.95, p = 0.02). Bidirectional MR analyses suggested that increased IL-6 signalling was associated with reductions in both small (beta on small HDL particle count − 0.16, 95% CI − 0.10 to − 0.21 per natural log change in SD-scaled CRP, p = 9 × 10–8).and total HDL particle count (beta − 0.13, 95% CI − 0.09 to − 0.17, p = 7 × 10–10), but that the reverse effect of HDL on IL-6 signalling was largely null.ConclusionsLow number of small HDL particles are associated with increased hazard of sepsis, sepsis-related death, and sepsis-related critical care admission. However, genetic analyses did not strongly support this as causal. Instead, we demonstrate that increased IL-6 signalling, which is known to alter infection risk, could confound associations with reduced HDL particle count, and suggest this may explain part of the observed association between (small) HDL particle count and sepsis.

FRI181 Increased LDL Particle And Apolipoprotein B Concentrations In Patients With Nonfunctioning And Cortisol Secreting Adrenal Adenomas

Abstract Disclosure: R. Sandooja: None. A. Kittithaworn: None. P. Dogra: None. D. Gruppen: None. E. Atkinson: None. S. Achenbach: None. K. Yu: None. M. Connelly: None. V. Simha: None. R.P. Dullaart: None. I. Bancos: None. INTRODUCTION: Based on the spectrum of cortisol excess, adrenal adenomas are classified as adenomas with Cushing syndrome (CS), adenomas with mild autonomous cortisol secretion (MACS), and non-functioning adenomas (NFA). Patients with adrenal adenomas demonstrate a high prevalence of cardiovascular morbidity and mortality proportional to the degree of hypercortisolism. Evidence on whether dyslipidemia is a contributing cardiovascular risk factor in patients with NFA and MACS is discrepant. We aimed to characterize (apo) lipoprotein abnormalities across the spectrum of cortisol excess in patients with adenomas as compared to referent subjects. METHODS: Study Design: Single center cross sectional study between 01/2015 - 05/2021.Patients: Adults with NFA, MACS, or CS were consecutively enrolled. MACS was diagnosed based on post-dexamethasone cortisol &amp;gt;1.8 mcg/dL. Referent subjects were recruited from local population of patients with available abdominal imaging and no adrenal disorders. All subjects provided fasting ethylenediaminetetraacetic acid (EDTA) venous samples. Measurements: Nuclear magnetic resonance (NMR) spectroscopy measurements included total cholesterol (TC), low-density lipoprotein (LDL) and LDL particle concentrations, high-density lipoprotein (HDL) subclasses, apolipoprotein B (apo B), triglycerides (TG) and TG-rich lipoprotein concentrations. RESULTS: Participants included 101 patients with CS (median age 44 years, IQR 31-58, 85% women), 158 patients with MACS (median age 62 years, IQR 51-70, 62% women), 166 patients with NFA (median age 60 years, IQR 53--66, 63% women) and 136 referent subjects (median age 68 years, IQR 57-77, 52% women). Patients had higher BMI (32 vs 27 kg/m2), higher prevalence of hypertension (72% vs 46%) and diabetes mellitus (27% vs 9%) as compared to reference subjects. Statin therapy was used in 32% of patients and referent subjects. After adjusting for age, sex, BMI, smoking, diabetes, hypertension, and statin therapy, as compared to referent subjects, we found inconsistent increase in TC, LDL cholesterol and TG across CS, MACS and NFA and no consistent differences in LDL size, HDL variables, TG and TG-rich lipoproteins. However, when compared to referent subjects, LDL particle concentrations- CS(OR 1.78, 95% CI 1.33-2.39), MACS (OR 1.31, 95% CI 1.03-1.67), and NFA (OR 1.43, 95% CI 1.12-1.82) and Apo B levels were higher in all patient categories: CS (OR 2.26, 95% CI 1.57-3.24), MACS (OR 1.36 95% CI 1.00-1.85 ), and NFA (OR 1.54 95% CI 1.13-2.09). These differences were particularly evident in patients not on statin therapy. CONCLUSIONS: We found that LDL particle and Apo B concentrations were elevated in all patient groups, including those with MACS and NFA. In comparison to conventional lipid measurements, LDL particle and Apo B may serve as a better biomarker of the future cardiovascular risk in patients with adrenal adenomas. Presentation: Friday, June 16, 2023

Metabolomic Profiling of Cholesterol Efflux Capacity in a Multiethnic Population: Insights From MESA.

Impaired cholesterol efflux capacity (CEC) is a novel lipid metabolism trait associated with atherosclerotic cardiovascular disease. Mechanisms underlying CEC variation are unknown. We evaluated associations of circulating metabolites with CEC to advance understanding of metabolic pathways involved in cholesterol efflux regulation. Participants enrolled in the MESA (Multi-Ethnic Study of Atherosclerosis) who underwent nuclear magnetic resonance metabolome profiling and CEC measurement (N=3543) at baseline were included. Metabolite associations with CEC were evaluated using standard linear regression analyses. Repeated ElasticNet and multilayer perceptron regression were used to assess metabolite profile predictive performance for CEC. Features important for CEC prediction were identified using Shapley Additive Explanations values. Greater CEC was significantly associated with metabolite clusters composed of the largest-sized particle subclasses of VLDL (very-low-density lipoprotein) and HDL (high-density lipoprotein), as well as their constituent apo A1, apo A2, phospholipid, and cholesterol components (β=0.072-0.081; P<0.001). Metabolite profiles had poor accuracy for predicting in vitro CEC in linear and nonlinear analyses (R2<0.02; Spearman ρ<0.18). The most important feature for CEC prediction was race, with Black participants having significantly lower CEC compared with other races. We identified independent associations among CEC, the largest-sized particle subclasses of VLDL and HDL, and their constituent apolipoproteins and lipids. A large proportion of variation in CEC remained unexplained by metabolites and traditional clinical risk factors, supporting further investigation into genomic, proteomic, and phospholipidomic determinants of CEC.

Proteomic and functional analysis of HDL subclasses in humans and rats: a proof-of-concept study

BackgroundThe previous study investigated whether the functions of small, medium, and large high density lipoprotein (S/M/L-HDL) are correlated with protein changes in mice. Herein, the proteomic and functional analyses of high density lipoprotein (HDL) subclasses were performed in humans and rats.MethodsAfter purifying S/M/L-HDL subclasses from healthy humans (n = 6) and rats (n = 3) using fast protein liquid chromatography (FPLC) with calcium silica hydrate (CSH) resin, the proteomic analysis by mass spectrometry was conducted, as well as the capacities of cholesterol efflux and antioxidation was measured.ResultsOf the 120 and 106 HDL proteins identified, 85 and 68 proteins were significantly changed in concentration among the S/M/L-HDL subclasses in humans and rats, respectively. Interestingly, it was found that the relatively abundant proteins in the small HDL (S-HDL) and large HDL (L-HDL) subclasses did not overlap, both in humans and in rats. Next, by searching for the biological functions of the relatively abundant proteins in the HDL subclasses via Gene Ontology, it was displayed that the relatively abundant proteins involved in lipid metabolism and antioxidation were enriched more in the medium HDL (M-HDL) subclass than in the S/L-HDL subclasses in humans, whereas in rats, the relatively abundant proteins associated with lipid metabolism and anti-oxidation were enriched in M/L-HDL and S/M-HDL, respectively. Finally, it was confirmed that M-HDL and L-HDL had the highest cholesterol efflux capacity among the three HDL subclasses in humans and rats, respectively; moreover, M-HDL exhibited higher antioxidative capacity than S-HDL in both humans and rats.ConclusionsThe S-HDL and L-HDL subclasses are likely to have different proteomic components during HDL maturation, and results from the proteomics-based comparison of the HDL subclasses may explain the associated differences in function.

Measurement of cholesterol levels of lipoprotein subclasses in human serum using anion-exchange high-performance liquid chromatography with a linear concentration gradient of sodium perchlorate.

Relationships between the subclasses of high-density lipoprotein (HDL) or low-density lipoprotein (LDL) and the risk of atherosclerotic cardiovascular disease have been studied, and using various methods, such as ultracentrifugation, electrophoresis, and nuclear magnetic resonance, for analysing lipoprotein subclasses. We established a method for HDL and LDL subclasses using anion-exchange high-performance liquid chromatography (AEX-HPLC) with a linear concentration gradient of sodium perchlorate (NaClO4). In the AEX-HPLC, the subclasses of HDL and LDL were separated, and detected using a post-column reactor with an enzymatic cholesterol reagent, that contained cholesterol esterase, cholesterol oxidase, and peroxidase as major ingredients. LDL subclasses were divided based on the absolute value of first-derivative chromatogram. Three HDL subclasses, HDL-P1, HDL-P2, and HDL-P3, and three LDL subclasses, LDL-P1, LDL-P2, and LDL-P3, were separated by AEX-HPLC, and detected in order. The major components of HDL-P2 and HDL-P3 were HDL3 and HDL2, respectively. The linearity was determined for each lipoprotein subclass. The coefficients of variation of cholesterol concentration of the subclasses for within-day assay (n = 10) and between-day assay (n = 10) ranged between 3.08-8.94% and 4.52-9.97%, respectively. Cholesterol levels in HDL-P1 of diabetic patients were positively correlated with oxidized LDL levels (r = 0.409, p = 0.002). Moreover, cholesterol levels in LDL-P2 and LDL-P3 were positively correlated with oxidized LDL levels (r = 0.393, p = 0.004 and r = 0.561, p < 0.001, respectively). AEX-HPLC may be highly suitable as an assay to clinically assess lipoprotein subclasses.

Hepatic Cdkal1 deletion regulates HDL catabolism and promotes reverse cholesterol transport

Background and aimsAssociations between CDKAL1 variants and cholesterol efflux capacity (CEC) have been reported. This study aimed to investigate the effects of Cdkal1 deficiency on high-density lipoprotein (HDL) metabolism, atherosclerosis, and related pathways. MethodsLipid and glucose metabolic profiles, CEC, and in vivo reverse cholesterol transport (RCT) were compared in liver-specific Alb-Cre:Cdkal1fl/fl and Cdkal1fl/fl mice. Aortic atherosclerosis was compared in Apoe−/−Alb-Cre:Cdkal1fl/fl and Apoe−/− mice fed high-fat diets. HDL subclasses and mediators of HDL metabolism from Alb-Cre:Cdkal1fl/fl mice were examined. ResultsHDL-cholesterol level tended to be higher in the Alb-Cre:Cdkal1fl/fl mice (p = 0.050). Glucose and other lipid profiles were similar in the two groups of mice, irrespective of diet. The mean CEC was 27% higher (p = 0.007) in the Alb-Cre:Cdkal1fl/fl mice, as were the radioactivities of bile acids (mean difference 17%; p = 0.035) and cholesterol (mean difference 42%; p = 0.036) from faeces. The radioactivity tendency was largely similar in mice fed a high-fat diet. Atherosclerotic lesion area tended to be smaller in the Apoe−/−Alb-Cre:Cdkal1fl/fl mice than in the Apoe−/− mice (p = 0.067). Cholesterol concentrations in large HDLs were higher in the Alb-Cre:Cdkal1fl/fl mice (p = 0.024), whereas in small HDLs, they were lower (p = 0.024). Endothelial lipase (mean difference 39%; p = 0.002) and hepatic lipase expression levels (mean difference 34%; p < 0.001) were reduced in the Alb-Cre:Cdkal1fl/fl mice, whereas SR-B1 expression was elevated (mean difference 35%; p = 0.007). ConclusionsThe promotion of CEC and RCT in Alb-Cre:Cdkal1fl/fl mice verified the effect of CDKAL1 seen in human genetic data. These phenotypes were related to regulation of HDL catabolism. This study suggests that CDKAL1 and associated molecules could be targets for improving RCT and vascular pathology.

Altered high-density lipoprotein composition is associated with risk for complications in type 2 diabetes mellitus in South Asian descendants: A cross-sectional, case-control study on lipoprotein subclass profiling.

Composition of high-density lipoproteins (HDL) is emerging as an important determinant in the development of microvascular complications in type 2 diabetes mellitus (T2DM). Dutch South Asian (DSA) individuals with T2DM display an increased risk of microvascular complications compared with Dutch white Caucasian (DwC) individuals with T2DM. In this study, we aimed to investigate whether changes in HDL composition associate with increased microvascular risk in this ethnic group and lead to new lipoprotein biomarkers. Using 1 H nuclear magnetic resonance spectroscopy and Bruker IVDr Lipoprotein Subclass Analysis (B.I.LISA) software, plasma lipoprotein changes were determined in 51 healthy individuals (30 DwC, 21 DSA) and 92 individuals with T2DM (45 DwC, 47 DSA) in a cross-sectional, case-control study. Differential HDL subfractions were investigated using multinomial logistic regression analyses, adjusting for possible confounders including BMI and diabetes duration. We identified HDL compositional differences between healthy and diabetic individuals in both ethnic groups. Specifically, levels of apolipoprotein A2 and HDL-4 subfractions were lower in DSA compared with DwC with T2DM. Apolipoprotein A2 and HDL-4 subfractions also negatively correlated with waist circumference, waist-to-hip ratio, haemoglobin A1c, glucose levels and disease duration in DSA with T2DM, and associated with increased incidence of microvascular complications. While HDL composition differed between controls and T2DM in both ethnic groups, the lower levels of lipid content in the smallest HDL subclass (HDL-4) in DSA with T2DM appeared to be more clinically relevant, with higher odds of having diabetes-related pan-microvascular complications such as retinopathy and neuropathy. These typical differences in HDL could be used as ethnicity-specific T2DM biomarkers.

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.