Cholesterol efflux capacity does not associate with coronary calcium, plaque vulnerability, and telomere length in healthy octogenarians

Cholesterol Metabolism in Aging and Age-Related Disorders

All mammalian cell membranes contain cholesterol to maintain membrane integrity. The transport of this hydrophobic lipid is mediated by lipoproteins. Cholesterol is especially enriched in the brain, particularly in synaptic and myelin membranes. Aging involves changes in sterol metabolism in peripheral organs and also in the brain. Some of those alterations have the potential to promote or to counteract the development of neurodegenerative diseases during aging. Here, we summarize the current knowledge of general principles of sterol metabolism in humans and mice, the most widely used model organism in biomedical research. We discuss changes in sterol metabolism that occur in the aged brain and highlight recent developments in cell type-specific cholesterol metabolism in the fast-growing research field of aging and age-related diseases, focusing on Alzheimer's disease. We propose that cell type-specific cholesterol handling and the interplay between cell types critically influence age-related disease processes.

Cholesterol mass efflux capacity and coronary artery calcium: The Multi-Ethnic Study of Atherosclerosis

We assessed the cross-sectional and longitudinal relationships of high-density lipoprotein (HDL)-mediated cholesterol mass efflux capacity (CMEC) with coronary artery calcium (CAC) score and CAC density. CMEC was measured in 1626 Multi-Ethnic Study of Atherosclerosis (MESA) participants in samples obtained between 2000 and 2002 as part of two nested case-control studies, one with cases of incident cardiovascular disease and the other with cases of carotid plaque progression by ultrasound. Cardiac CT examinations for the presence of CAC were performed at baseline and at two additional examinations. CAC scores (Agatston and volume) and density scores (for those with positive CAC) were calculated. Multivariable linear regression modeling per SD increment of CMEC was used to estimate the associations of CMEC with each of these CAC measures. We found no association between higher CMEC and either lower CAC scores or a higher CAC density. We also found no association between higher CMEC and progression of any of these CAC measures. These findings suggest that HDL-mediated cholesterol efflux may be associated with cardiovascular risk via mechanisms unrelated to burden of calcified plaque.

HDL and reverse cholesterol transport in humans and animals: Lessons from pre-clinical models and clinical studies

The ability to accept cholesterol from cells and to promote reverse cholesterol transport (RCT) represents the best characterized antiatherogenic function of HDL. Studies carried out in animal models have unraveled the multiple mechanisms by which these lipoproteins drive cholesterol efflux from macrophages and cholesterol uptake to the liver. Moreover, the influence of HDL composition and the role of lipid transporters have been clarified by using suitable transgenic models or through experimental design employing pharmacological or nutritional interventions. Cholesterol efflux capacity (CEC), an in vitro assay developed to offer a measure of the first step of RCT, has been shown to associate with cardiovascular risk in several human cohorts, supporting the atheroprotective role of RCT in humans as well. However, negative data in other cohorts have raised concerns on the validity of this biomarker. In this review we will present the most relevant data documenting the role of HDL in RCT, as assessed in classical or innovative methodological approaches.

Cholesterol efflux promoting function of high-density lipoproteins in calcific aortic valve stenosis

Background and aims

Cholesterol efflux capacity is a functional property of high-density lipoproteins (HDL) reflecting the efficiency of the atheroprotective reverse cholesterol transport process in humans. Its relationship with calcific aortic valve stenosis (CAVS) has not been fully assessed yet.

Methods

We evaluated HDL-CEC in a patient population with varying degrees of aortic valvular calcific disease, assessed using echocardiography and cardiac computed tomography. Measurement of biomarkers that reflect osteogenic and tissue remodeling, along with dietary and gut microbiota-derived metabolites were performed.

Results

Patients with moderate-severe CAVS had significantly lower HDL-CEC compared to both control and aortic sclerosis subjects (mean: 6.09%, 7.32% and 7.26%, respectively). HDL-CEC displayed negative correlations with peak aortic jet velocity and aortic valve calcium score, indexes of CAVS severity (ρ = -0.298, p = 0.002 and ρ = -0.358, p = 0.005, respectively). In multivariable regression model, HDL-CEC had independent association with aortic valve calcium score (B: -0.053, SE: 0.014, p < 0.001), GFR (B: -0.034, SE: 0.012, p = 0.007), as well as with levels of total cholesterol (B: 0.018, SE: 0.005, p = 0.002).

Conclusion

These results indicate an impairment of HDL-CEC in moderate-severe CAVS and may contribute to identify potential novel targets for CAVS management.

HDL in Atherosclerotic Cardiovascular Disease: In Search of a Role

For a long time, high-density lipoprotein cholesterol (HDL-C) has been regarded as a cardiovascular disease (CVD) protective factor. Recently, several epidemiological studies, while confirming low plasma levels of HDL-C as an established predictive biomarker for atherosclerotic CVD, indicated that not only people at the lowest levels but also those with high HDL-C levels are at increased risk of cardiovascular (CV) mortality. This “U-shaped” association has further fueled the discussion on the pathophysiological role of HDL in CVD. In fact, genetic studies, Mendelian randomization approaches, and clinical trials have challenged the notion of HDL-C levels being causally linked to CVD protection, independent of the cholesterol content in low-density lipoproteins (LDL-C). These findings have prompted a reconsideration of the biological functions of HDL that can be summarized with the word “HDL functionality”, a term that embraces the many reported biological activities beyond the so-called reverse cholesterol transport, to explain this lack of correlation between HDL levels and CVD. All these aspects are summarized and critically discussed in this review, in an attempt to provide a background scenario for the “HDL story”, a lipoprotein still in search of a role.

HDL in the 21st Century: A Multifunctional Roadmap for Future HDL Research

Low high-density lipoprotein cholesterol (HDL-C) characterizes an atherogenic dyslipidemia that reflects adverse lifestyle choices, impaired metabolism, and increased cardiovascular risk. Low HDL-C is also associated with increased risk of inflammatory disorders, malignancy, diabetes, and other diseases. This epidemiologic evidence has not translated to raising HDL-C as a viable therapeutic target, partly because HDL-C does not reflect high-density lipoprotein (HDL) function. Mendelian randomization analyses that have found no evidence of a causal relationship between HDL-C levels and cardiovascular risk have decreased interest in increasing HDL-C levels as a therapeutic target. HDLs comprise distinct subpopulations of particles of varying size, charge, and composition that have several dynamic and context-dependent functions, especially with respect to acute and chronic inflammatory states. These functions include reverse cholesterol transport, inhibition of inflammation and oxidation, and antidiabetic properties. HDLs can be anti-inflammatory (which may protect against atherosclerosis and diabetes) and proinflammatory (which may help clear pathogens in sepsis). The molecular regulation of HDLs is complex, as evidenced by their association with multiple proteins, as well as bioactive lipids and noncoding RNAs. Clinical investigations of HDL biomarkers (HDL-C, HDL particle number, and apolipoprotein A through I) have revealed nonlinear relationships with cardiovascular outcomes, differential relationships by sex and ethnicity, and differential patterns with coronary versus noncoronary events. Novel HDL markers may also have relevance for heart failure, cancer, and diabetes. HDL function markers (namely, cholesterol efflux capacity) are associated with coronary disease, but they remain research tools. Therapeutics that manipulate aspects of HDL metabolism remain the holy grail. None has proven to be successful, but most have targeted HDL-C, not metrics of HDL function. Future therapeutic strategies should focus on optimizing HDL function in the right patients at the optimal time in their disease course. We provide a framework to help the research and clinical communities, as well as funding agencies and stakeholders, obtain insights into current thinking on these topics, and what we predict will be an exciting future for research and development on HDLs.

High Density Lipoprotein Cholesterol Efflux Capacity and Atherosclerosis in Cardiovascular Disease: Pathophysiological Aspects and Pharmacological Perspectives

Over the years, the relationship between high-density lipoprotein (HDL) and atherosclerosis, initially highlighted by the Framingham study, has been revealed to be extremely complex, due to the multiple HDL functions involved in atheroprotection. Among them, HDL cholesterol efflux capacity (CEC), the ability of HDL to promote cell cholesterol efflux from cells, has emerged as a better predictor of cardiovascular (CV) risk compared to merely plasma HDL-cholesterol (HDL-C) levels. HDL CEC is impaired in many genetic and pathological conditions associated to high CV risk such as dyslipidemia, chronic kidney disease, diabetes, inflammatory and autoimmune diseases, endocrine disorders, etc. The present review describes the current knowledge on HDL CEC modifications in these conditions, focusing on the most recent human studies and on genetic and pathophysiologic aspects. In addition, the most relevant strategies possibly modulating HDL CEC, including lifestyle modifications, as well as nutraceutical and pharmacological interventions, will be discussed. The objective of this review is to help understanding whether, from the current evidence, HDL CEC may be considered as a valid biomarker of CV risk and a potential pharmacological target for novel therapeutic approaches.

High-density lipoprotein cholesterol and arterial calcification in midlife women: the contribution of estradiol and C-reactive protein

OBJECTIVE

Studies suggest a reversal in the protective association of high-density lipoprotein cholesterol (HDL-C) and cardiovascular disease in women traversing menopause. Decreasing estrogen levels during the transition, as well as inflammation, may explain this reversal. We tested whether either estradiol or C-reactive protein (CRP) concentrations modified the association of HDL-C with aortic (AC) or coronary artery calcification (CAC).

METHODS

A total of 478 participants between ages 46 to 59 from the Study of Women's Health Across the Nation Heart baseline visit were included. AC and CAC presence were defined as Agatston score of 100 or higher and 10 or higher, respectively. Logistic regression was used for analysis.

RESULTS

A total of 112 (23.53%) participants had AC 100 or higher and 104 (21.76%) had CAC 10 or higher. In unadjusted models, a 1-mg/dL higher in HDL-C was associated with 3% lower odds of AC (95% CI: 0.95-0.99) and 4% lower odds of CAC (95% CI: 0.95-0.98). In adjusted models, a significant interaction between HDL-C and estradiol with respect to AC but not CAC was detected, such that higher HDL-C level was protective at the highest estradiol quartile (odds ratio: 0.91, 95% CI: 0.84-0.99 per 1 mg/dL higher HDL-C, P = 0.03) but tended to associate with greater risk at the lowest quartile (odds ratio: 1.04, 95% CI: 0.98-1.10 per 1 mg/dL higher HDL-C, P = 0.16). CRP did not modify any association.

CONCLUSIONS

The protective cardiovascular association of higher HDL-C levels on AC was modified by estradiol but not CRP concentrations. The pathways through which estradiol might influence this association should be further investigated.

[Predictors of Coronary Plaque Vulnerability in Patients with Stable Coronary Artery Disease]

Aim      To identify new predictors for vulnerability of atherosclerotic coronary plaques in patients with stable ischemic heart disease (sIHD).Material and methods  This prospective, single-center study included 58 patients with sIHD. Unstable plaques were detected with virtual histology intravascular ultrasound of proximal and medium segments of a coronary artery without significant lesions according to coronarography data. Indexes of inflammation, dyslipidemia and carbohydrate metabolism were considered as candidate predictors for coronary plaque vulnerability.Results In 56 coronary arteries, 58 plaques were detected, 12 of which (20.7 %) were unstable. Vulnerable plaques differed morphologically from stable ones by a greater size of the necrotic core (35.1±8.5 % vs. 24.0±13.2 %; р=0.008), calcified nodules (2.0 [1.0; 5.0] % vs. 1.0 [0; 2.0] %; р=0.006), and a lower content of fibrous components (54.9±10.2 % vs. 66.4±15.8 %; р=0.02). In addition, vulnerable plaques more frequently narrowed the arterial lumen by &gt;70 % of the lumen area (33.3 % vs. 2.2 %; р=0.0006). Correlation analysis showed a negative correlation between the level of high-density lipoproteins (HDL) and calcium volume (r= -0.4104; р=0.023); a positive correlation between the blood glucose level as determined by the oral glucose tolerance test and the lipid component (r=0.48198; р=0.033); and a negative correlation between the apolipoprotein A level and the calcium volume (r= -0.4297; р=0.008).Conclusion      The study demonstrated a high prevalence of vulnerable plaques in nontarget coronary arteries in patients with sIHD. In this process, dyslipidemia indexes (LDL, apolipoproteins A) correlate with the calcium volume whereas blood glucose, as measured in the oral glucose tolerance test, correlates with the lipid component of coronary plaque.

HDL cholesterol efflux capacity is inversely associated with subclinical cardiovascular risk markers in young adults: The cardiovascular risk in Young Finns study

The atherogenic process begins already in childhood and progresses to symptomatic condition with age. We investigated the association of cholesterol efflux capacity (CEC) and vascular markers of subclinical atherosclerosis in healthy, young adults. CEC was determined in 2282 participants of the Young Finns study using cAMP treated 3H-cholesterol-labeled J774 cells. The CEC was correlated to baseline and 6-year follow-up data of cardiovascular risk factors and ultrasound measurements of arterial structure and function. CEC was higher in women, correlated with total cholesterol, HDL-C, and apolipoprotein A-I, but not with LDL-C or apolipoprotein B. Compared to the lowest CEC quartile, the highest CEC quartile was significantly associated with high CRP levels and inversely associated with adiponectin. At baseline, high CEC was associated with decreased flow-mediated dilation (FMD) and carotid artery distensibility, as well as an increased Young's modulus of elasticity, indicating adverse changes in arterial structure, and function. The association reversed with follow-up FMD data, indicating the interaction of preclinical parameters over time. A higher CEC was directly associated with a lower risk of subclinical atherosclerosis at follow-up. In young and healthy subjects, CEC was associated with important lipid risk parameters at baseline, as in older patients and CAD patients, but inversely with early risk markers for subclinical atherosclerosis.

Interaction between high-density lipoproteins and inflammation: Function matters more than concentration!

High-density lipoprotein (HDL) plays an important role in lipid metabolism and especially contributes to the reverse cholesterol transport pathway. Over recent years it has become clear that the effect of HDL on immune-modulation is not only dependent on HDL concentration but also and perhaps even more so on HDL function. This review will provide a concise general introduction to HDL followed by an overview of post-translational modifications of HDL and a detailed overview of the role of HDL in inflammatory diseases. The clinical potential of HDL and its main apolipoprotein constituent, apoA-I, is also addressed in this context. Finally, some conclusions and remarks that are important for future HDL-based research and further development of HDL-focused therapies are discussed.

Rationale and design of the expanded combination of evolocumab plus empagliflozin in diabetes: EXCEED-BHS3 trial

BACKGROUND

Patients with type 2 diabetes mellitus (T2DM) remain at increased cardiovascular residual risk and endothelial dysfunction, even after optimizing metabolic control and treatment by sodium-glucose-2 transporter inhibitors (SGLT2-is). The present study was based on the hypothesis that proprotein convertase subtilisin/kexin 9 inhibitor (PCSK9i) therapy may mitigate endothelial dysfunction in T2DM patients who are on regular treatment by SGLT2-i.

METHODS

The EXCEED-BHS3 is a prospective, single-center, investigator-blinded, open-label, randomized clinical trial. Participants (n = 110) will be randomized (1:1) to either empagliflozin 25 mg/day alone or empagliflozin 25 mg/day plus evolocumab 140 mg every 2 weeks in addition to optimal medical care. The primary endpoint was defined as the change in the 1-min flow-mediated dilation (FMD) after 16 weeks of treatment. The secondary endpoint is the FMD change after ischemia/reperfusion injury protocol (reserve FMD) after 16 weeks of treatment. Exploratory outcomes comprise the change in FMD and reserve FMD after 8 weeks of treatment and the change after 16 weeks of treatment in the following parameters: plasma levels of nitric oxide, vascular cell adhesion molecule-1 and isoprostane, high-density lipoprotein (HDL) and low-density lipoprotein subfractions profile, HDL function, blood pressure, body mass index, waist circumference and adipokines.

CONCLUSION

This will be the first study to evaluate the add-on effect of PCSK9i on endothelial function of T2DM patients under regular use of empagliflozin.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03932721.

High-density lipoprotein cholesterol efflux capacity and cardiovascular risk in autoimmune and non-autoimmune diseases

Functional assessment of cholesterol efflux capacity (CEC) to high-density lipoprotein (HDL) is an emerging tool for evaluating morbidity and mortality associated with cardiovascular disease (CVD). By promoting macrophage reverse cholesterol transport (RCT), HDL-mediated CEC is believed to play an important role in atherosclerotic lesion progression in the vessel wall. Furthermore, recent evidence indicates that the typical inverse associations between various forms of CEC and CV events may be strongly modulated by environmental systemic factors and traditional CV risk factors, in addition to autoimmune diseases. These factors influence the complex and dynamic composition of HDL particles, which in turn positively or negatively affect HDL-CEC. Herein, we review recent findings connecting HDL-CEC to traditional CV risk factors and cardiometabolic conditions (non-autoimmune diseases) as well as autoimmune diseases, with a specific focus on how these factors may influence the associations between HDL-CEC and CVD risk.

Cholesterol mass efflux capacity and risk of peripheral artery disease: The Multi-Ethnic Study of Atherosclerosis

BACKGROUND AND AIMS

We aimed to assess the relationship of HDL (high-density lipoprotein)-mediated cholesterol mass efflux capacity (CMEC) with risk of incident peripheral artery disease (PAD).

METHODS

CMEC was measured in 1458 Multi-Ethnic Study of Atherosclerosis participants between 2000 and 2002 as part of a case-control study matched for incident cardiovascular disease and progression of carotid plaque by ultrasound. Incident clinical PAD, adjudicated on the basis of a positive history for the presence of disease-related symptoms or treatment, was ascertained through 2015 in 1419 individuals without clinical PAD at baseline. Subclinical PAD, defined as an ankle-brachial index (ABI) ≤1.0, was assessed among 1255 individuals with a baseline ABI >1.0 and at least one follow-up ABI measurement 3-10 years later. Cox proportional hazards and relative risk regression modeling per SD increment of CMEC were used to determine the association of CMEC with clinical and subclinical PAD, respectively.

RESULTS

There were 38 clinical PAD and 213 subclinical PAD events that occurred over a mean follow-up of 6.0 and 6.5 years respectively. After adjustment for age, gender, and race, higher CMEC levels were not associated with clinical PAD (hazard ratio 1.25; 95% CI 0.89, 1.75) or subclinical PAD (risk ratio 1.02; 95% CI, 0.94, 1.11).

CONCLUSIONS

These findings suggest that HDL-mediated cholesterol efflux is not significantly associated with incident clinical and subclinical PAD.

[Predictors of acute coronary syndrome in patients with ischaemic heart disease]

Acute coronary syndrome has for a long time been giving no way of decreasing mortality related to ischaemic heart disease. The primary cause of acute coronary syndrome in the majority of cases is rupture of an unstable atherosclerotic plaque in the coronary artery followed by thrombosis thereof. The main missions of modern cardiology include: assessment of the risk of acute coronary syndrome, identification of predictors of adverse events, and working-out of measures aimed at prevention and optimal management of patients with ischaemic heart disease. This article deals with clinical and morphological factors associated with destabilization of coronary plaques, their rupture, and the development of an acute coronary event.

Coagulatory Defects in Type-1 and Type-2 Diabetes

Diabetes (both type-1 and type-2) affects millions of individuals worldwide. A major cause of death for individuals with diabetes is cardiovascular diseases, in part since both types of diabetes lead to physiological changes that affect haemostasis. Those changes include altered concentrations of coagulatory proteins, hyper-activation of platelets, changes in metal ion homeostasis, alterations in lipid metabolism (leading to lipotoxicity in the heart and atherosclerosis), the presence of pro-coagulatory microparticles and endothelial dysfunction. In this review, we explore the different mechanisms by which diabetes leads to an increased risk of developing coagulatory disorders and how this differs between type-1 and type-2 diabetes.

Vulnerable Plaque, Characteristics, Detection, and Potential Therapies

Plaque development and rupture are hallmarks of atherosclerotic vascular disease. Despite current therapeutic developments, there is an unmet necessity in the prevention of atherosclerotic vascular disease. It remains a challenge to determine at an early stage if atherosclerotic plaque will become unstable and vulnerable. The arrival of molecular imaging is receiving more attention, considering it allows for a better understanding of the biology of human plaque and vulnerabilities. Various plaque therapies with common goals have been tested in high-risk patients with cardiovascular disease. In this work, the process of plaque instability, along with current technologies for sensing and predicting high-risk plaques, is debated. Updates on potential novel therapeutic approaches are also summarized.

Markers of Atherosclerosis: Part 1 - Serological Markers

Atherosclerosis is a major contributor to morbidity and mortality worldwide. With therapeutic consequences in mind, several risk scores are being used to differentiate individuals with low, intermediate or high cardiovascular (CV) event risk. The most appropriate management of intermediate risk individuals is still not known, therefore, novel biomarkers are being sought to help re-stratify them as low or high risk. This narrative review is presented in two parts. Here, in Part 1, we summarise current knowledge on serum (serological) biomarkers of atherosclerosis. Among novel biomarkers, high sensitivity C-reactive protein (hsCRP) has emerged as the most promising in chronic situations, others need further clinical studies. However, it seems that a combination of serum biomarkers offers more to risk stratification than either biomarker alone. In Part 2, we address genetic and imaging markers of atherosclerosis, as well as other developments relevant to risk prediction.

A critical appraisal of the measurement of serum 'cholesterol efflux capacity' and its use as surrogate marker of risk of cardiovascular disease

The 'cholesterol efflux capacity (CEC)' assay is a simple in vitro measure of the capacities of individual sera to promote the first step of the reverse cholesterol transport pathway, the delivery of cellular cholesterol to plasma HDL. This review describes the cell biology of this model and critically assesses its application as a marker of cardiovascular risk. We describe the pathways for cell cholesterol export, current cell models used in the CEC assay with their limitations and consider the contribution that measurement of serum CEC provides to our understanding of HDL function in vivo.

Unravelling HDL-Looking beyond the Cholesterol Surface to the Quality Within

High-density lipoprotein (HDL) particles have experienced a turbulent decade of falling from grace with widespread demotion from the most-sought-after therapeutic target to reverse cardiovascular disease (CVD), to mere biomarker status. HDL is slowly emerging from these dark times due to the HDL flux hypothesis wherein measures of HDL cholesterol efflux capacity (CEC) are better predictors of reduced CVD risk than static HDL-cholesterol (HDL-C) levels. HDL particles are emulsions of metabolites, lipids, protein, and microRNA (miR) built on the backbone of Apolipoprotein A1 (ApoA1) that are growing in their complexity due to the higher sensitivity of the respective “omic” technologies. Our understanding of particle composition has increased dramatically within this era and has exposed how our understanding of these particles to date has been oversimplified. Elucidation of the HDL proteome coupled with the identification of specific miRs on HDL have highlighted the “hormonal” characteristics of HDL in that it carries and delivers messages systemically. HDL can dock to most peripheral cells via its receptors, including SR-B1, ABCA1, and ABCG1, which may be a critical step for facilitating HDL-to-cell communication. The composition of HDL particles is, in turn, altered in numerous disease states including diabetes, auto-immune disease, and CVD. The consequence of changes in composition, however, on subsequent biological activities of HDL is currently poorly understood and this is an important avenue for the field to explore in the future. Improving HDL particle quality as opposed to HDL quantity may, in turn, prove a more beneficial investment to reduce CVD risk.