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 associated 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.

Comparative Analysis of Atherogenic Lipoproteins L5 and Lp(a) in Atherosclerotic Cardiovascular Disease.

Purpose Of Review: Low-density lipoprotein (LDL) poses a risk for atherosclerotic cardiovascular disease (ASCVD). As LDL comprises various subtypes differing in charge, density, and size, understanding their specific impact on ASCVD is crucial. Two highly atherogenic LDL subtypes-electronegative LDL (L5) and Lp(a)-induce vascular cell apoptosis and atherosclerotic changes independent of plasma cholesterol levels, and their mechanisms warrant further investigation.

The pathophysiology of excess plasma-free cholesterol.

Purpose Of Review: Several large studies have shown increased mortality due to all-causes and to atherosclerotic cardiovascular disease. In most clinical settings, plasma HDL-cholesterol is determined as a sum of free cholesterol and cholesteryl ester, two molecules with vastly different metabolic itineraries. We examine the evidence supporting the concept that the pathological effects of elevations of plasma HDL-cholesterol are due to high levels of the free cholesterol component of HDL-C.

Bempedoic acid lowers high-sensitivity C-reactive protein and low-density lipoprotein cholesterol: Analysis of pooled data from four phase 3 clinical trials.

Background And Aims: High-sensitivity C-reactive protein (hsCRP), a marker for atherosclerotic cardiovascular disease risk, is reduced by bempedoic acid. We assessed the relationship between changes in low-density lipoprotein cholesterol (LDL-C) and hsCRP in relation to baseline statin use.

Methods: Pooled data from four phase 3 trials (patients on maximally tolerated statins [Pool 1] and patients receiving no or low-dose statins [Pool 2]) were used to determine the proportion of patients with baseline hsCRP ≥2 mg/L who achieved hsCRP <2 mg/L at week 12.

Efficacy and safety of bempedoic acid in patients not receiving statins in phase 3 clinical trials.

Background: Despite the high incidence of patients with statin tolerance problems, randomized evaluations of nonstatin oral treatment options for lowering of low-density lipoprotein cholesterol (LDL-C) in this population are sparse.

Objective: To assess the LDL-C lowering effect of bempedoic acid in patients not taking statins.

Methods: This was a pooled analysis of data from patients enrolled in four phase 3 bempedoic acid studies (12 to 52 weeks in duration) who were not taking concomitant statins (Phase 3 No Statin Cohort) and a phase 3 bempedoic acid plus ezetimibe fixed-dose combination study (BA+EZE FDC No Statin Cohort).

Bempedoic acid in patients with type 2 diabetes mellitus, prediabetes, and normoglycaemia: A post hoc analysis of efficacy and glycaemic control using pooled data from phase 3 clinical trials.

Aim: To evaluate the effect of bempedoic acid on glycaemic and lipid variables in patients with hypercholesterolaemia.

Methods: A patient-level pooled analysis of four phase 3, randomized, double-blind, placebo-controlled trials evaluated changes in glycaemia, change from baseline in LDL-C, and adverse events. Patients (N = 3621) on maximally tolerated statins were randomized 2:1 to oral bempedoic acid 180 mg or placebo once daily for 12 to 52 weeks with the results analysed by baseline glycaemic status (diabetes, prediabetes, or normoglycaemia).

High Free Cholesterol Bioavailability Drives the Tissue Pathologies in Scarb1 Mice.

Objective: Overall and atherosclerosis-associated mortality is elevated in humans with very high HDL (high-density lipoprotein) cholesterol concentrations. Mice with a deficiency of the HDL receptor, Scarb1 (scavenger receptor class B type 1), are a robust model of this phenotype and exhibit several additional pathologies. We hypothesized that the previously reported high plasma concentration of free cholesterol (FC)-rich HDL in Scarb1-/- mice produces a state of high HDL-FC bioavailability that increases whole-body FC and dysfunction in multiple tissue sites.

High-density lipoproteins, reverse cholesterol transport and atherogenesis.

Plasma HDL-cholesterol concentrations correlate negatively with the risk of atherosclerotic cardiovascular disease (ASCVD). According to a widely cited model, HDL elicits its atheroprotective effect through its role in reverse cholesterol transport, which comprises the efflux of cholesterol from macrophages to early forms of HDL, followed by the conversion of free cholesterol (FCh) contained in HDL into cholesteryl esters, which are hepatically extracted from the plasma by HDL receptors and transferred to the bile for intestinal excretion. Given that increasing plasma HDL-cholesterol levels by genetic approaches does not reduce the risk of ASCVD, the focus of research has shifted to HDL function, especially in the context of macrophage cholesterol efflux.

Comparing a novel machine learning method to the Friedewald formula and Martin-Hopkins equation for low-density lipoprotein estimation.

Background: Low-density lipoprotein cholesterol (LDL-C) is a target for cardiovascular prevention. Contemporary equations for LDL-C estimation have limited accuracy in certain scenarios (high triglycerides [TG], very low LDL-C).

Objectives: We derived a novel method for LDL-C estimation from the standard lipid profile using a machine learning (ML) approach utilizing random forests (the Weill Cornell model).

Highly conserved amino acid residues in apolipoprotein A1 discordantly induce high density lipoprotein assembly in vitro and in vivo.

Objective: Apolipoprotein A1 (APOA1) is essential to reverse cholesterol transport, a physiologically important process that protects against atherosclerotic cardiovascular disease. APOA1 is a 28 kDa protein comprising multiple lipid-binding amphiphatic helices initialized by proline residues, which are conserved across multiple species. We tested the hypothesis that the evolutionarily conserved residues are essential to high density lipoprotein (HDL) function.

The Alcohol-High-Density Lipoprotein Athero-Protective Axis.

Ingestion of alcohol is associated with numerous changes in human energy metabolism, especially that of plasma lipids and lipoproteins. Regular moderate alcohol consumption is associated with reduced atherosclerotic cardiovascular disease (ASCVD), an effect that has been attributed to the concurrent elevations of plasma high-density lipoprotein-cholesterol (HDL-C) concentrations. More recent evidence has accrued against the hypothesis that raising plasma HDL concentrations prevents ASCVD so that other metabolic processes associated with alcohol consumption have been considered.

Association of Bempedoic Acid Administration With Atherogenic Lipid Levels in Phase 3 Randomized Clinical Trials of Patients With Hypercholesterolemia.

Importance: Additional lipid-lowering therapy options are needed for patients who cannot achieve sufficient decreases in low-density lipoprotein cholesterol (LDL-C) levels using statins alone or for those who are statin intolerant.

Objective: To conduct a pooled analysis of phase 3 randomized clinical trials of bempedoic acid vs placebo.

Design, Setting, And Participants: This analysis pooled data from 4 double-blind, placebo-controlled randomized clinical trials conducted from 2016 to 2018.

PCSK9 and inflammation: a review of experimental and clinical evidence.

Proprotein convertase subtilisin/kexin Type 9 (PCSK9) is now identified as an important and major player in hypercholesterolaemia and atherosclerosis pathophysiology. PCSK9, through promoting lysosomal degradation of hepatic low-density lipoprotein (LDL) receptor, can decrease the clearance of plasma LDLs, leading to hypercholesterolaemia and consequent atherosclerotic plaque formation. Hypercholesterolaemia has been found to promote systemic and vascular inflammation, which can cause atherosclerotic lesion formation and progression and subsequent incidence of cardiovascular disease.

Revisiting Reverse Cholesterol Transport in the Context of High-Density Lipoprotein Free Cholesterol Bioavailability.

Dysregulated free cholesterol (FC) metabolism has been implicated in nearly all stages of atherosclerosis, the underlying cause of most cardiovascular disease. According to a widely cited model, the burden of macrophage FC in the arterial wall is relieved by transhepatic reverse cholesterol transport (RCT), which comprises three successive steps: (1) macrophage FC efflux to high-density lipoprotein (HDL) and/or its major protein, apolipoprotein AI; (2) FC esterification by lecithin:cholesterol acyltransferase (LCAT); and (3) HDL-cholesteryl ester (CE) uptake via the hepatic HDL-receptor, scavenger receptor class B type 1 (SR-B1). Recent studies have challenged the validity of this model, most notably the role of LCAT, which appears to be of minor importance.

Cholesterol: Can't Live With It, Can't Live Without It.

Given its role in many biochemical processes essential to life, cholesterol remains a topic of intense research. Of all the plasma lipids, cholesterol is distinctive because it is a precursor to steroidogenic molecules, some of which regulate metabolism, and its blood concentration in the form of low- and high-density lipoprotein cholesterol (HDL-C) are positive and negative risk factors for atherosclerotic cardiovascular disease (ASCVD). New research, however, has challenged the widely held belief that high HDL-C levels are atheroprotective and is showing that both low and high plasma HDL-C levels confer an increased risk of ASCVD.

Mammalian Target of Rapamycin: A Metabolic Rheostat for Regulating Adipose Tissue Function and Cardiovascular Health.

The complex relationship between diet and metabolism is an important contributor to cellular metabolism and health. Over the past few decades, a central role for mammalian target of rapamycin (mTOR) in the regulation of multiple cellular processes, including the response to food intake, maintaining homeostasis, and the pathogenesis of disease, has been shown. Herein, we first review our current understanding of the biochemical functions of mTOR and its response to fluctuations in hormone levels, like insulin.

Monocyte-to-HDL-cholesterol ratio as a prognostic marker in cardiovascular diseases.

Inflammation and lipid accumulation are two basic hallmarks of atherosclerosis as a chronic disease. Inflammation not only is a local response but can also be considered as a systemic process followed by an elevation of inflammatory mediators. Monocytes are a major source of proinflammatory species during atherogenesis.