HDL Particles Research Articles

“Head-to-Toe” Lipid Properties Govern the Binding and Cargo Transfer of High-Density Lipoprotein

The viscoelastic properties of biological membranes are crucial in controlling cellular functions and are determined primarily by the lipids’ composition and structure. This work studies these properties by varying the structure of the constituting lipids in order to influence their interaction with high-density lipoprotein (HDL) particles. Various fluorescence-based techniques were applied to study lipid domains, membrane order, and the overall lateral as well as the molecule–internal glycerol region mobility in HDL–membrane interactions (i.e., binding and/or cargo transfer). The analysis of interactions with HDL particles and various lipid phases revealed that both fully fluid and some gel-phase lipids preferentially interact with HDL particles, although differences were observed in protein binding and cargo exchange. Both interactions were reduced with ordered lipid mixtures containing cholesterol. To investigate the mechanism, membranes were prepared from single-lipid components, enabling step-by-step modification of the lipid building blocks. On a biophysical level, the different mixtures displayed varying stiffness, fluidity, and hydrogen bond network changes. Increased glycerol mobility and a strengthened hydrogen bond network enhanced anchoring interactions, while fluid membranes with a reduced water network facilitated cargo transfer. In summary, the data indicate that different lipid classes are involved depending on the type of interaction, whether anchoring or cargo transfer.

Per- and polyfluoroalkyl substances, apolipoproteins and the risk of coronary heart disease in US men and women

BackgroundExisting evidence for associations of per- and polyfluoroalkyl substances (PFASs) with blood lipids, lipoproteins and apolipoproteins (apo), and coronary heart disease (CHD) risk is limited and inconsistent. This study aims to explore associations between plasma PFASs, blood lipoprotein subspecies defined by apolipoproteins, and CHD risk.MethodsA case–control study of CHD was conducted in the Health Professionals Follow-Up Study (HPFS) and Nurses' Health Study (NHS). Among participants initially free of cardiovascular disease at blood collection in 1994 (HPFS) or 1990 (NHS), 101 participants who developed non-fatal myocardial infarction or fatal CHD were identified and confirmed. A healthy control was matched to each case for age, smoking status, and date of blood draw. Plasma levels of perfluorohexane sulfonic acid (PFHxS), perfluorooctanoic acid (PFOA), total perfluorooctane sulfonic acid (PFOS), branched PFOS (brPFOS), linear PFOS (nPFOS), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA) were measured. Conditional logistic regression and cubic spline regression models were used to examine associations between baseline PFASs and CHD risk. Linear regression models were applied to study PFAS associations with lipids and their subfractions.ResultsAfter multivariate adjustments, total PFOS, brPFOS and nPFOS were significantly associated with increased risk of developing CHD, and HRs (95% CIs) per log(ng/mL) increment of PFASs were 3.66 (1.36–9.89), 3.68 (1.55–8.76), and 3.01 (1.16–7.86), respectively. Significant positive dose–response relationships were identified for these PFASs (Plinearity = 0.01, 0.002, 0.02, respectively). Other PFASs were not associated with CHD risk. PFNA and PFDA were positively associated with total apoE levels among HDL particles with or without apoC-III. No associations were observed for other PFASs with blood lipid subspecies. Blood lipid subfractions did not explain the association between PFOS and CHD risk.ConclusionsPlasma PFOS and its isomers were positively associated with CHD risk. These findings suggest that PFOS exposure causes public health risks that are greater than hitherto believed.

Unifying Theory and Experiments: Multi-Target Pharmacology of Dajihan Pill Against Hyperlipidemia

Background: The increasing incidence of hyperlipidemia (HLP) is attributed to the imbalance in redox homeostasis, aberrant lipid metabolism, and the excessive intake of empty calories. Dajihan Pill (DJHP) is a Traditional Chinese Medicine (TCM) formula composed of Zingiberis Rhizoma (ZR), Piperis Longi Fructus (PLF), Alpiniae Officinarum Rhizome (AOR), and Cinnamomi Cortex (CC) in a ratio of 3:2:3:2. It exhibits a significant preventive effect on HLP. Certainly, the active components and the precise mechanism of action are not fully understood. Therefore, this study aims to elucidate the preventive and ameliorative mechanisms of DJHP against HLP by integrating network pharmacology, molecular docking, and experimental validation. Methods: Based on the pharmacological method, active ingredients in DJHP and targets were extracted from Traditional Chinese Medicine System Pharmacology (TCMSP) and UniProt. Then core compounds and targets were obtained by constructing “compounds-targets-disease” and proteinprotein interaction (PPI) network. Gene Ontology (GO) function analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) were employed to elucidate further the associated action mechanism. The molecular binding mechanisms between the core ingredients and targets were elucidated through molecular docking. Additionally, the antioxidant capacities of DJHP extracts were investigated by assessing their DPPH, hydroxyl, and ABTS radical scavenging activities. Results: A total of 45 active compounds and 258 targets were identified in DJHP. Network analysis indicated that quercetin, beta-sitosterol, kaempferol, and oleic acid might serve as core bioactive compounds. Seven core targets, including AKT1, INS, and TNF, were identified as potential preventive targets. GO analysis suggested the improvement of HLP by DJHP may be related to the lipid metabolic process, high-density lipoprotein particle, triglyceride binding, and inflammatory response. The KEGG analysis indicated TNF, HIF-1, and AMPK signaling pathways were involved. The observations of active compounds binding with core targets indicated an excellent combination. Additionally, antioxidant results showed that DJHP exhibited significant DPPH, hydroxyl, and ABTS radical scavenging activities. Conclusion: Theoretical and experimental investigations indicate that DJHP can effectively modulate various signaling pathways and enhance the redox system, thus mitigating HLP. Our work provided a basis for the pharmacological study of DJHP in preventing HLP and further research.

Cholesteryl ester transfer protein inhibition: a pathway to reducing risk of morbidity and promoting longevity.

To review the evidence and describe the biological plausibility for the benefits of inhibiting cholesteryl ester transfer protein (CETP) on multiple organ systems through modification of lipoprotein metabolism. Results from observational studies, Mendelian randomization analyses, and randomized clinical trials support the potential of CETP inhibition to reduce atherosclerotic cardiovascular disease (ASCVD) risk through a reduction of apolipoprotein B-containing lipoproteins. In contrast, raising high-density lipoprotein (HDL) particles, as previously hypothesized, did not contribute to ASCVD risk reduction. There is also an expanding body of evidence supporting the benefits of CETP inhibition for safeguarding against other conditions associated with aging, particularly new-onset type 2 diabetes mellitus and dementia, as well as age-related macular degeneration, septicemia, and possibly chronic kidney disease. The latter are likely mediated through improved functionality of the HDL particle, including its role on cholesterol efflux and antioxidative, anti-inflammatory, and antimicrobial activities. At present, there is robust clinical evidence to support the benefits of reducing CETP activity for ASCVD risk reduction, and plausibility exists for the promotion of longevity by reducing risks of several other conditions. An ongoing large clinical trial program of the latest potent CETP inhibitor, obicetrapib, is expected to provide further insight into CETP inhibition as a therapeutic target for these various conditions.

Obicetrapib Treatment Increases Pre-Beta1 HDL and Lipophilic Antioxidants in the Ocean and Rose2 Studies

Background and Aims: Non-lipidated ApoA1 (pre-beta1 HDL) captures cholesterol and lipophilic antioxidants via ABCA1. HDL particles transport antioxidants to tissues such as retina and brain. The effect of HDL raising interventions on pre-beta1 HDL levels and the distribution of lipophilic antioxidants amongst lipoproteins is unknown. CETP-inhibition was hypothesized to reduce the antioxidant capacity of HDL, although direct evidence was never presented. This is now addressed in phase II studies of the novel CETP-inhibitor obicetrapibMethods: Plasma samples from two phase II studies with obicetrapib were used to measure changes in pre-beta1 HDL by ELISA with a selective antibody to ApoA1 aa 137-144 (LQEKLSPL).. Lipophilic antioxidants were quantified in plasma, non-HDL, and HDL-fractions by ULPC ms-ms.Results: In both studies, no significant changes occurred in placebo groups but, in the obicetrapib treated groups, plasma pre-beta1 HDL increased by 12% (p<0.04) and 24% (p<0.03). In OCEAN, plasma ApoA1 and HDL-C levels correlated with increasing levels of antioxidants in the HDL fraction.In ROSE2, α-tocopherol was raised in plasma by 16% (p<0.003) and in HDL by 58% (p<0.00003). In both studies pre-beta1 HDL in obicetrapib treated patients was correlated with α-tocopherol in plasma.Conclusions: CETP inhibition with obicetrapib increases pre-beta1 HDL, impacts excess cholesterol efflux, and also raises important HDL antioxidants. Thus, these results support the potential therapeutic use of obicetrapib in diseases with high unmet medical need that are associated with low HDL and low levels of lipophilic antioxidants in plasma and tissues, such as AMD, neurodegenerative disorders, and sickle cell anemia.

The Emerging Potential of Apolipoprotein C-III Inhibition for ASCVD Prevention: A State-of-the-Art Review.

Multiple agents are being developed that inhibit apolipoprotein (apo) C-III. This state-of-the-art review examines their potential for atherosclerotic cardiovascular disease (ASCVD) risk reduction. Apo C-III, an apolipoprotein on the surface of triglyceride-rich lipoproteins (TRLs), impairs clearance of TRLs through both lipoprotein lipase dependent and independent pathways, thereby resulting in increased concentrations of triglycerides. Apo C-III has also been shown to have pro-atherogenic effects when bound to high-density lipoprotein (HDL) particles. Classical and genetic epidemiology studies provide support for the concept that apo C-III is associated with an increased risk of ASCVD events. Drug efficacy of agents that silence APOC3 mRNA has been studied in populations with varying hypertriglyceridemia severity, including those with familial chylomicronemia syndrome, multifactorial chylomicronemia syndrome/severe hypertriglyceridemia, and mixed hyperlipidemia. Randomized controlled trials have reported significant reductions in TG and non-HDL cholesterol levels among these patients treated with APOC3 inhibitors. Upcoming clinical outcomes trials seek to establish a role for APOC3 inhibitors to reduce risk of ASCVD.

Abstract 4120854: Case Report: Elevated HDL in Familial Hyper-Alpha-Lipoproteinemia: Atheroprotective or Atherogenic?

Introduction: Familial hyper-alpha-lipoproteinemia (HALP) is a heterogenous genetic lipid disorder that is found in only 8% of the population and manifests as elevated HDL levels above the 90 th percentile. HALP is due to mutations in various genes including cholesteryl ester transfer protein (CETP), hepatic lipase, or apolipoprotein C-III (APOC3). While epidemiological studies have noted an inverse relationship between high HDL and the development of coronary artery disease, recent data have shown a lack of causal atheroprotective effects. We present a case of a patient with significantly elevated HDL and peripheral vascular disease. Case Description: Patient is a 64-year-old female with past medical history of peripheral artery disease with occlusion of the left femoral artery and popliteal arteries status post angioplasty, hypertension, type 2 diabetes, alcohol use, and CKD Stage 4 who presented to the advanced lipid clinic for management of elevated lipoproteins. Patient’s laboratory data was significant for total cholesterol (TC) of 375 mg/dL, a high-density lipoprotein (HDL) of &gt;200 mg/dL, triglycerides (TG) of 66 mg/dL, and a low-density lipoprotein (LDL) of 175 mg/dL. Further testing revealed elevated apolipoprotein A-I of 231 mg/dL. Patient was subsequently initiated on a high intensity statin with improvement in her lipid panel with a TC of 247 mg/dL, HDL of 133 mg/dL, TG of 50 mg/dL, and LDL of 106 mg/dL, with plan for further uptitration of lipid therapy to target LDL &lt;70 mg/dL. Discussion: CETP exchanges cholesteryl esters from HDL for TG, making HDL smaller and more TG-rich. Studies have shown that in vitro addition of CETP and hepatic lipase, which hydrolyzes phospholipids and TG, into CETP-deficient patients led to the development of very small HDL particles that were able to remove cholesterol from lipid laden macrophages. Conversely, larger HDL molecules seen in CETP-deficient patients did not have such anti-atherogenic properties. In addition to recognizing HALP in the setting of elevated HDL, it is also important to exclude secondary causes of elevated HDL, such as primary biliary cirrhosis and high-dose niacin. Genetic testing should also be considered.

Differential proteomic profiles of exosomes in pediatric and adult adamantinomatous craniopharyngioma cyst fluid.

Adamantinomatous craniopharyngiomas (ACPs), commonly seen in pediatrics and adults often present with large cystic cavities that can compress surrounding tissues, causing severe visual and endocrine symptoms. Complete resection of cystic ACP is challenging, frequently leading to postoperative recurrence. The composition of the cystic fluid is complex, and to date, there has been limited research focusing on exosomes within ACP cyst fluid. We collected cyst fluid from 12 ACP patients and confirmed the presence of exosomes. Subsequently, we conducted exosomal proteomic analysis using LC-MS/MS. The patients were divided into pediatric and adult groups for the analysis of differential protein enrichment, followed by comprehensive bioinformatics analysis, including GO analysis, KEGG analysis, and PPI network analysis, among other functional pathway and protein interaction analyses. Immunohistochemistry was used to determine the tissue expression distribution of the differential protein APOA1. In our data analysis, 64 significantly differentially expressed proteins were identified, with 37 being overexpressed in the pediatric group and 27 in the adult group. Our results revealed that exosomal proteins in the pediatric group were predominantly enriched in modules and pathways related to high-density lipoprotein particle, apolipoprotein receptor binding, and the PPAR signaling pathway. Additionally, APOA1, as the hub protein with the highest connectivity in the differential protein interaction network, may play a critical role in β-amyloid metabolism pathways in pediatric ACP. This study is the first to construct a proteomic map of ACP cyst fluid exosomes, suggesting significant differences in the tumor microenvironment's lipid metabolism between pediatrics and adults.

Serum Metabolome Signature Response to Different Types of Resistance Training.

Pneumatic resistance training (PRT) facilitates a longer time under tension that might lead to greater changes in body composition when compared to traditional resistance training (TRT), possibly enhancing serum metabolite concentrations indicative of healthy metabolic function. To assess the impact of PRT and TRT on muscular strength, body composition, and serum metabolome, 69 men (age: 31.8±7.2 years, height: 179.7±5.4 cm, weight: 81.1±9.9 kg) were randomized into two 10-week intervention groups (PRT:n=24 and TRT:n=24) and one control group (CON:n=21). Serum metabolite concentrations were assessed before and after the training intervention by high-throughput nuclear magnetic resonance. Fat mass and lean mass were obtained by bioimpedance analysis. The training intervention resulted in an increase in lean mass for both PRT (1.85±2.69%; p=0.003) and TRT (2.72±4.53%; p=0.004), while only PRT reduced statistically significantly in body fat percentage (PRT: -5.08±10.76%; p=0.019). Only in PRT and TRT significant increases in small high-density lipoproteins (S-HDL-L) and small HDL particles (S-HDL-P) were observed. When controlling for fat and lean mass, the effects on S-HDL-L/S-HDL-P diminished. Network analysis may suggest that PRT and TRT result in an increase in network connectivity and robustness. It appears that the observed improvements are associated with changes in body composition.

The Bromodomain and Extraterminal Protein Inhibitor Apabetalone Ameliorates Kidney Injury in Diabetes by Regulating Cholesterol Accumulation and Modulating the Gut Microbiota

IntroductionAn FDA-approved new bromodomain (BRD) and extra-terminal (BET) bromine domain antagonist called apabetalone, which targets BRD4, has been shown to raise preβ1-HDL(Prebeta-1 High-Density Lipoprotein) particles, enhance apolipoprotein A-I in both humans and animals, and restore angiogenesis in experimental diabetes. Its action is not, however, fully known mechanistically. The objective of our research was to investigate the impact of apabetalone on renal damage linked to diabetic kidney disease (DKD). MethodsThis research employed both pharmacological and genetic methods to examine the impact of apabetalone on db/db (BKS. Cg-leprdb/leprdb) mice and human tubular epithelial cells (HK-2). ResultsHere, significant reductions in blood creatinine, urea nitrogen and UACR(urinary albumin/creatinine ratio) levels, serum triglycerides (TG) and serum total cholesterol (TC), as well as ectopic lipid droplet formation in renal tissue, were seen in the db/db mice following apabetalone therapy. Analysis of the gut microbiota revealed changes in its composition. Significantly, the proportion of Firmicutes to Bacteroidetes decreased as well as Deferribacterota, indicating a positive influence on lipid metabolism. Untargeted metabolomic analysis also indicated that the ABC transporter signaling pathway, implicated in cholesterol metabolism, was enriched. Moreover, peroxisome proliferator-activated receptor-gamma (PPARγ)/liver X receptor (LXR)/ABCA1(ATP-binding cassette transporters A1) protein and mRNA level as well as fibrosis-related marker proteins FN(Fibronectin) and Collagen I were all improved by apabetalone. ConclusionTherefore, we suggest that apabetalone showed significant anti-hyperlipidemic and anti-fibrotic effects, closely associated with alterations in the gut microbiota and cholesterol metabolism. The results of this investigation provide fresh perspectives on the processes that underlie apabetalone's effects in db/db mice.

HDL-Free Cholesterol Influx into Macrophages and Transfer to LDL Correlate with HDL-Free Cholesterol Content

High-density lipoprotein (HDL)-free cholesterol (FC) transfers to other lipoproteins and cells, the former by a spontaneous mechanism and the latter by both spontaneous and receptor-mediated mechanisms. Macrophages are an important cell type in all stages of atherosclerotic cardiovascular disease (ASCVD), and the magnitude of FC efflux from macrophages to HDL, a metric of HDL function, inversely associates with several metrics of ASCVD. Very high plasma HDL concentrations are associated with increased all cause and ASCVD mortality, suggesting that the reverse process, FC influx from HDL into macrophages, is atherogenic. We hypothesize that HDL-FC is a metric of dysfunctional HDL, and when combined with HDL particle number (HDL-P), is an ASCVD risk factor. The magnitude of FC influx from HDL to macrophages is expected to be a function of HDL-P and HDL-FC content. Here we show that plasma HDL-FC content varies 2-fold among normolipidemic human subjects and linearly correlates with low-density lipoprotein (LDL)-FC content. The influx of HDL-FC into macrophages and transfer to LDL increase linearly with HDL-FC. As expected, influx of HDL-FC into macrophages and transfer to LDL are positively correlated. These data support the hypothesis that high HDL FC content is a marker for dysfunctional HDL, resulting in greater influx into macrophages and greater HDL-FC transfer to LDL. HDL-FC transfer to LDL is a valid surrogate for influx into macrophages. This study of HDL composition and function of normolipidemic subjects provides the basis for further investigation and establishment of HDL-FC content as an ASCVD risk factor.

Plasma proteomic signature of chronic psychosocial stress in mice

Chronic stress significantly impacts both physical and mental wellbeing, increasing risk of cardiovascular disease, immune dysregulation, and psychiatric conditions such as depression and anxiety disorders. The plasma proteome is a valuable source of biomarkers of health and disease, but the limited number of studies exploring the potential of the plasma proteome as a biomarker for stress-related disorders underscores the importance of further investigation of the effects of chronic stress on the plasma proteome. The aim of this study was to examine the effect of a 5-week chronic psychosocial stress paradigm on the plasma proteome in mice and to determine if any affected proteins correlated with stress-induced changes in behaviour and physiology, and thus might represent biomarkers of negative impacts of chronic stress. Using LC-MS/MS proteomic analysis, 38 proteins in the mouse plasma proteome were identified to be affected by chronic psychosocial stress. Functional analysis revealed that these proteins clustered into biological functions including inflammatory response, regulation of the immune response, complement and coagulation cascades, lipid metabolic process, and high-density lipoprotein particles Correlation analyses of the identified proteins with stress-induced behavioural or physiological changes stress revealed significant correlations between stress-induced anxiety-like behaviour and Phosphatidylinositol-glycan-specific phospholipase D, Complement C2, Epidermal growth factor receptor, Prosaposin, Actin-related protein 2/3 complex subunit 1B, Maltase-glucoamylase, Mannosyl-oligosaccharide 1,2-alpha-mannosidase IA and Fibrinogen-like protein 1. Chronic psychosocial stress blunted acute stress-induced corticosterone release, and this correlated with abundance of Pyrethroid hydrolase Ces2a; N-fatty-acyl-amino acid synthase/hydrolase Pm20d1, Mannosyl-oligosaccharide 1,2-alpha-mannosidase IA, Alpha-2-macroglobulin-P and L-selectin. Finally, stress-induced reductions in both brown and epididymal fat correlated with Phosphatidylinositol-glycan-specific phospholipase D, Complement C2, Epidermal growth factor receptor, Kininogen-1, Apolipoprotein M, Angiopoietin-related protein 3, Proprotein convertase subtilisin/kexin type 9, and Lipopolysaccharide-binding protein. These findings demonstrate that chronic psychosocial stress induces alterations in plasma proteins implicated in key biological processes and pathways related to stress response, immune function, and lipid metabolic regulation. Further investigation into these proteins may provide new avenues for identification of biomarkers or mediators of stress-induced pathology.

Relation of apolipoprotein C3 to risk of major adverse cardiovascular events and death after acute coronary syndrome on a background of optimized statin treatment

Abstract Background Apolipoprotein C3 (ApoC3), a component of triglyceride-rich lipoproteins and some low-density lipoprotein and high-density lipoprotein particles, has been shown to predict incident coronary heart disease (CHD) and major adverse cardiovascular events (MACE). However, it is unknown whether ApoC3 predicts risk in patients with acute coronary syndrome (ACS) receiving contemporary therapies including optimized statin treatment, and if any such association is independent of apolipoprotein B (ApoB) levels. Purpose We assessed the association of ApoC3 with first MACE (CHD death, nonfatal myocardial infarction, fatal or nonfatal ischaemic stroke, or hospitalization for unstable angina) and all-cause death in patients with recent ACS treated with high-intensity or maximum-tolerated statin and blinded PCSK9 inhibitor (alirocumab, ALI) or placebo (PBO). Methods ApoC3 was measured by mass spectrometry at baseline (n=11,956) and after 4 months (M4; n=11,176) of treatment with ALI or PBO in the ODYSSEY OUTCOMES trial (which had 18,924 total participants). In continuous and spline analyses adjusted for treatment group and ApoB, we assessed the association of baseline ApoC3 with risk of MACE and death. In the ALI group we determined association of change in ApoC3 from baseline to M4 with risk of MACE and death after M4 in a model adjusted for baseline ApoC3 and ApoB, and the change in ApoB from baseline to M4. Results Median (Q1, Q3) baseline ApoC3 concentration was in a normal range [85 (65, 113) mg/L]. Continuous ApoC3 was not related to MACE (p=0.50) or death (p=0.51); spline analysis showed a slight curvilinear association of baseline ApoC3 with risk of MACE and death, but no clinically meaningful relationship (Figure). Findings were similar in the PBO group alone, and without adjustment for ApoB (data not shown). At M4, the median (Q1, Q3) change from baseline in ApoC3 was -10 (-27, -5; p&amp;lt;0.0001) mg/L with ALI and 2 (-14, 18; P = NS) mg/L with PBO. Overall, ALI significantly reduced the incidence of MACE (10.1% vs 12.1%; p=0.0006) and death (3.5% vs 4.2%; p=0.045) compared with PBO among those with available baseline ApoC3. However, the change in ApoC3 on treatment with ALI did not predict the risk of MACE or death after M4. Findings were qualitatively similar without adjustment for ApoB or its change. Conclusion In a cohort with recent ACS receiving optimized statin therapy and with median baseline ApoC3 in a normal range, ApoC3 did not provide clinically meaningful prediction of cardiovascular events or death. A modest reduction of ApoC3 by ALI did not associate with subsequent risk of MACE or death. It remains uncertain whether targeted therapies producing larger reductions in ApoC3 from higher baseline levels will affect cardiovascular risk.

Electronegative ApoCIII-Rich HDL promotes cellular damage and vascular aging

Abstract Background Experimental studies attributing HDL a cardioprotective effect are challenged by well-designed randomized controlled trials showing largely neutral results, which might be related to more recent observations that certain HDL particles exert detrimental effects. This study explores the effects of electronegative HDL on cellular damage and vascular aging. Using anion-exchange chromatography, HDL was divided into five subclasses (H1 to H5) based on increasing electronegativity. Compared to the health-promoting H1, the most electronegative subclass, H5 contains significantly higher levels of ApoCIII and triglycerides (TG). Purpose Herein, we aim to explore the cellular and molecular mechanisms underpinning H5-induced pathology in human umbilical vein vascular endothelial cells (HUVECs), which may accelerate vascular aging preceding the development of atherosclerotic cardiovascular disease (ASCVD). Methods H1 and H5 were isolated from patients with metabolic syndrome (MetS). To gauge the impact of H5 on vascular integrity, HUVECs were treated with solvent, H1, or H5 at concentrations of 25, 50, or 100 µg/mL. Cell viability and apoptosis were evaluated using the MTT assay and PI/Calcein fluorescent staining, respectively. Immunofluorescence staining and immunoblotting, focusing on 8-oxodG, P53, and β-gal, proxies of DNA damage and cellular senescence, were performed. Senescence-associated secretory phenotype (SASP) analysis was done to elucidate the senescent mechanism. By harnessing Mitosox imaging reactive oxygen species (ROS) synthesis was monitored. Finally, unbiased lipid- and transcriptomics were used to identify lipid components potentially involved in H5 signaling. Results As compared to controls, MetS patients exhibited more electronegative HDL particles, as indicated by increased H5 (1.604±0.410% vs 4.598±4.712%, P=0.0016). Remarkable elevations were noted in individuals with severe clinical complications, as shown in the representative patient with left ventricular hypertrophy, chronic coronary syndrome, and heart failure (Fig. 1). In HUVECs, H5 but not H1 reduced cell viability and increased apoptosis in a concentration-dependent manner. In parallel, H5 but not H1 induced cell aging, ROS production, and DNA damage, with SASP cytokines including IL-1β, IL-6, CCL2, TNF-α, and γH2AX (Fig. 1). Notably, compared to H1, H5 exhibited high contents of various TG species, impairing H5’s anti-inflammatory and antioxidant capacities, along with reductions in several phosphatidylcholines that may constitute essential cell membrane structural components, as evidenced by lipidomic studies (Fig. 2). Conclusion H5, the most electronegative and dysfunctional HDL subfraction, is capable of inducing DNA damage, oxidative stress, and senescence in vascular ECs. Its notable elevation in patients with MetS highlights a previously unrecognized etiology, shedding light on how electronegative HDL may contribute to and expedite ASCVD.Fig 1Fig 2

Triple-hormone receptor agonist retatrutide significantly improves lipoprotein and apolipoprotein profiles in participants with obesity or overweight

Abstract Background In a phase 2 study in participants who have obesity or overweight but not type 2 diabetes (T2D) (n=338), retatrutide (RETA), an agonist of GIP, GLP-1 and glucagon receptors, reduced body weight, glycated hemoglobin, triglycerides (TG), LDL-C and VLDL-C. Purpose To better understand the effects of RETA on the serum lipid profile we analyzed changes in apolipoprotein levels and distribution and size of lipoprotein particles. Methods Adult participants with obesity (BMI ≥30 kg/m2), or overweight (BMI ≥ 27 kg/m2 and &amp;lt; 30 kg/m2) with a weight-related comorbidity, and without T2D were randomized to receive RETA 1, 4, 8, 12 mg or placebo for 48 weeks. Lipids panel (including calculated non-HDL-C), apolipoproteins (apo) and NMR lipoprotein profiles were measured at baseline, 24 and 48 weeks in fasting plasma samples. Data were analyzed using a mixed model for repeated measures after log transformation. Results RETA dose-dependently reduced non-HDL-C up to 22.2% and 26.9% and apoB up to 19.6% and 24.2% at 24 and 48 weeks, respectively (Figure). At 48 weeks, RETA reduced TG and apoC-III levels up to 40.6% and 38.0%, respectively. RETA greatly reduced the total number of TG-rich lipoprotein particles (TRLP) and all subfractions of TRLP (large, medium and small) at 48 weeks (Table). Since the reduction in large and medium TRLP was greater than the reduction in small TRLP, the average size of TRLP was smaller following treatment with RETA. RETA reduced the number of total and highly atherogenic small LDL particles (LDLP), while total and small HDL particles (HDLP) were only slightly reduced. The average size of HDLP increased following treatment with RETA. At 48 weeks, the NMR-derived lipoprotein insulin resistance score was dose-dependently decreased by 27.4%, 31.7% and 32.5% with 4 mg, 8 mg and 12 mg, respectively, following RETA treatment. Conclusions RETA treatment for 48 weeks dose-dependently reduced levels of non-HDL-C and apoB and the number of total and small LDL particles, suggesting an improvement in atherogenic lipoprotein profile and cardiovascular risk in subjects who have obesity or overweight but not T2D.

Association between lipoprotein particle concentration and size and progression of coronary plaque: the MACS Longitudinal Coronary CT angiography study

Abstract Background People living with HIV have greater risk of cardiovascular diseases (CVD) than people without HIV and tend to have different risk profiles, including higher serum triglycerides and lower LDL cholesterol levels. Nuclear magnetic resonance (NMR) provides a detailed phenotype of lipoproteins. Purpose To examine the associations between lipoprotein particle concentrations and size and progression of coronary artery plaque among people living with and without HIV, and whether these associations differ by HIV serostatus. Methods Men with no clinical CVD in the Multicenter AIDS Cohort Study (MACS) who underwent a coronary CT angiography at baseline (2010-13) and follow-up (2015-17) were included. NMR spectroscopy was completed on fasting serum samples at baseline. Logistic regression models for the change in total coronary plaque volume (in tertiles) were estimated with NMR-derived lipoproteins as predictors. Levels were log-transformed and standardized to make results comparable. Models were adjusted for demographics, statin use and HIV serostatus (model 1) with addition of CVD risk factors (model 2). Interactions by HIV serostatus were also tested. Results A total of 549 men (314 with HIV; 235 without HIV) were included. Mean age was 53 ±7 years; 58% were White, 30% Black, and 12% Hispanic. Coronary plaque was present in 70% and plaque volume progressed in 79% of the cohort. Among men with HIV, 81% had undetectable HIV RNA and 12% had a diagnosis of AIDS at baseline. Men with HIV had significantly higher levels of small LDL-P, and total, medium and large VLDL-P levels compared to men without HIV, and lower levels of total, small and large HDL-P (Table 1). Men with HIV had significantly greater progression of plaque volume (37 mm3) compared to men without HIV (31 mm3, p&amp;lt;0.05). Levels of total and small LDL-P concentrations were directly associated with plaque progression, whereas large HDL-P was inversely associated with plaque progression in the combined sample (Model 2). Associations between total and small LDL-P with plaque progression were stronger in men with HIV than in men without HIV in models 1 and 2 (interaction p&amp;lt;0.01). While associations in fully adjusted models for total VLDL-P and small VLDL-P were significant in men without HIV, there were no significant associations between these particle concentrations with coronary plaque progression among men without HIV (interaction p&amp;lt; 0.01) (Model 2, Table 2). Conclusion Associations between lipid particle concentrations and coronary plaque progression differed between men with and without HIV, with stronger associations seen in men without HIV for total and small LDL-P. Despite having higher VLDL and lower HDL particle concentrations at baseline, these particle concentrations were only associated with plaque progression in men without HIV. Further research is needed to elucidate HIV specific factors for plaque progression to tailor risk reduction strategies.

Associations Between High-Density Lipoprotein Cholesterol Efflux and Brain Grey Matter Volume.

Objective: High-density lipoprotein cholesterol efflux function may prevent brain amyloid beta deposition and neurodegeneration. However, the relevance of this finding has not been established in the diverse middle-aged population. Methods: We examined 1826 adults (47% Black adults) who participated in the Dallas Heart Study to determine associations between high-density lipoprotein (HDL) measures and brain structure and function. White matter hyperintensities (WMH) and whole-brain grey matter volume (GMV) were measured using brain MRI, and the Montreal Cognitive Assessment (MoCA) was used to measure neurocognitive function. HDL cholesterol efflux capacity (HDL-CEC) was assessed using fluorescence-labeled cholesterol efflux from J774 macrophages, and HDL particle size measures were assessed using nuclear magnetic resonance (NMR) spectroscopy (LipoScience). Multivariable linear regressions were performed to elucidate associations between HDL-CEC and brain and cognitive phenotypes after adjustment for traditional risk factors such as age, smoking status, time spent in daily physical activity, and education level. Results: Higher HDL-CEC and small HDL particle (HDL-P) concentration were positively associated with higher GMV normalized to total cranial volume (TCV) (GMV/TCV) after adjustment for relevant risk factors (β = 0.078 [95% CI: 0.029, 0.126], p = 0.002, and β = 0.063 [95% CI: 0.014, 0.111], p = 0.012, respectively). Conversely, there were no associations between HDL measures and WMH or MoCA (all p > 0.05). Associations of HDL-CEC and small HDL-P with GMV/TCV were not modified by ApoE-ε4 status or race/ethnicity. Interpretation: Higher HDL cholesterol efflux and higher plasma concentration of small HDL-P were associated with higher GMV/TCV. Additional studies are needed to explore the potential neuroprotective functions of HDL.

Distinct roles of size-defined HDL subpopulations in cardiovascular disease.

Doubts about whether high-density lipoprotein-cholesterol (HDL-C) levels are causally related to atherosclerotic cardiovascular disease (CVD) risk have stimulated research on identifying HDL-related metrics that might better reflect its cardioprotective functions. HDL is made up of different types of particles that vary in size, protein and lipid composition, and function. This review focuses on recent findings on the specific roles of HDL subpopulations defined by size in CVD. Small HDL particles are more effective than larger particles at promoting cellular cholesterol efflux because apolipoprotein A-I on their surface better engages ABCA1 (ATP binding cassette subfamily A member 1). In contrast, large HDL particles bind more effectively to scavenger receptor class B type 1 on endothelial cells, which helps prevent LDL from moving into the artery wall. The specific role of medium-sized HDL particles, the most abundant subpopulation, is still unclear. HDL is made up of subpopulations of different sizes of particles, with selective functional roles for small and large HDLs. The function of HDL may depend more on the size and composition of its subpopulations than on HDL-C levels. Further research is required to understand how these different HDL subpopulations influence the development of CVD.

Advanced lipid testing in children: a call for pediatric reference intervals

Abstract Introduction Abnormal serum lipid levels in childhood are associated with dyslipidemia and increased risk of cardiovascular disease in adulthood. High prevalence of childhood obesity in the US has increased concerns about the adverse effects of abnormal lipids in children, prompting recommendations for universal lipid screening in adolescents. While specialized analysis of lipoproteins by nuclear magnetic resonance (NMR) has been predominately used in adults with risk factors for CVD, our laboratory also receives pediatric samples for NMR testing, most commonly associated with diagnostic codes for hyperlipidemia and/or abnormal weight gain. Currently adult-based reference ranges for the NMR lipoprotein measurements are used in children. The objective of this pilot study was to compare lipoprotein profiles of healthy adults and children and to assess the impact of reference intervals for children on clinical interpretation of pediatric results. Methods Serum samples were collected from 60 healthy children, ages 1 – 17 years, and 148 healthy adults, ages 19 – 64 years old. NMR lipoprotein analysis was performed using the Axinon lipoFIT by NMR assay on a 600 MHz NMR (Bruker). Statistical analysis was conducted in Excel and GraphPad Prism. Reference intervals (RIs) were determined in EP Evaluator as the central 95% interval. Results The levels of atherogenic low-density lipoprotein particle number (LDL-P) and small LDL-P (sLDL-P) were significantly lower in children compared to adults: 783±222 vs 1212±412 nmol/L and 302±142 vs 498±306 nmol/L, respectively (p&amp;lt;0.00001). Additionally, LDL size (LDL-s) was significantly larger in children than adults (21.23±0.29 vs 21.06±0.44 nm, p=0.006), reflecting prevalence of less dense LDL-P in the former group. Pediatric samples also had lower number of anti-atherogenic high-density lipoprotein particles (HDL-P) compared to adults: 29.4±4.6 vs 33.5±4.6 µmol/L, p&amp;lt;0.00001. The significant differences in the number and size of lipoprotein particles between adults and children implies that currently used adult reference intervals might not be appropriate for evaluating pediatric NMR samples. Therefore, we estimated RIs for our heathy pediatric and adult cohorts and applied these RIs to our retrospective data of 618 samples from children 1-17 years old, which were submitted for NMR lipoprotein testing in recent years. The analysis showed that using the adult RIs, 37% and 27% of pediatric samples would not flag for abnormally elevated LDL-P and sLDL-P, respectively; but they would be flagged based on the RI derived from our pediatric cohort. Moreover, 12% pediatric samples flagged for low HDL-P would have normal HDL-P levels if pediatric RIs are used instead of adult RIs. Conclusions Use of adult reference intervals in children may result in misclassification of lipid status and underestimation or overestimation of dyslipidemia and CVD risk in children. This pilot study highlights the need for pediatric reference intervals to guide interpretation of advanced lipid testing in children.

NMR Insights into Lipoprotein Particles: analyzing correlations with traditional lipid measurements

Abstract Introduction Lipid metabolism plays a crucial role in various physiological processes. Lipid molecules are transported by lipoproteins, and the intricate involvement of lipoproteins in cardiovascular disease (CVD) is well-established, given their diverse size, density, and lipid composition. The emergence of Nuclear Magnetic Resonance (NMR) spectroscopy, a high-resolution analytical technique, promotes the assessment of lipoprotein particle numbers and sizes. Studies suggest that the measurement of total low-density lipoprotein particle numbers (LDL-P), small LDL-P (SLDL-P), and total high-density lipoprotein particle numbers (HDL-P) provides better evaluation of risk of CVD than enzymatic-based measurements of LDL cholesterol (LDL-C) and HDL cholesterol (HDL-C). Our study examined the correlation between NMR-derived lipoprotein profiles and traditional cholesterol measurements in control and patient populations. Methods Fasting serum samples were collected from healthy male and female donors (n=148), ages 21-64 years. The analysis also included the results from &amp;gt;20,000 patients’ samples submitted to our laboratory for NMR lipid testing. We assessed LDL-P, SLDL-P, HDL-P, large HDL (LHDL-P), and HDL size (HDL-S) by NMR. In addition, total cholesterol (TC) and HDL-C were measured using traditional automated enzymatic assays (Roche Diagnostics); LDL-C was calculated. Statistical analyses, including Spearman correlation, were performed using GraphPad Prism software. Spearman coefficient (r) ≥0.75 indicated a strong correlation, r &amp;lt;0.5 indicated a weak correlation. Results HDL-C only moderately correlated with total HDL-P in samples collected from controls (rcontrols=0.52) and patients (rpatients=0.68), while showing better correlation with LHDL-P (rcontrols=0.90, rpatients=0.89). Traditional LDL-C strongly correlated with total LDL-P (rcontrols=0.76, rpatients=0.81), but showed only weak correlation with SLDL-P (rcontrols=0.42, rpatients=0.28), which is considered more atherogenic and predictive of CVD risk than LDL-C or total LDL-P. Interestingly, among various lipoprotein parameters, SLDL-P correlated the strongest with HDL-S in both study populations (rcontrols=-0.87, rpatients=-0.84). Samples with higher number of SLDL-P also had smaller size of HDL-P, although the number of total HDL-P did not differ between high vs low SLDL-P samples. In contrast, only moderate negative correlation was observed between SLDL-P and traditional HDL-C (rcontrols=-0.74, rpatients=-0.68), suggesting that the size of HDL particles might add value in evaluating CVD risk. Conclusion The NMR technology has advantage over traditional measurements in stratifying an individual’s lipoprotein milieu. It provides insights into the number of small LDL particles and size of HDL particles, which are not included in standard lipid testing and may allow for more individualized patient care. Incorporation of lipoprotein size and particle number in clinical guidelines may help physicians with assessment CVD risk and treatment monitoring.