Association between lipid accumulation product and chronic obstructive pulmonary disease: a cross-sectional study based on U.S. adults

Background

Lipid Accumulation Product (LAP), which is derived from measurements of waist circumference and triglyceride (TG) levels, serves as a comprehensive indicator of lipid accumulation. Emerging research indicates that lipid accumulation dysfunction might significantly contribute to the pathogenesis of Chronic Obstructive Pulmonary Disease (COPD). Nevertheless, the investigation into the association between LAP and COPD risk is still insufficient, particularly in population-based research. This research intends to examine the possible correlation between LAP and the likelihood of developing COPD.

Methods

This study, designed as a cross-sectional analysis, made use of data gathered from the National Health and Nutrition Examination Survey (NHANES) spanning the years 2017 to 2020, encompassing a total of 7,113 eligible participants. LAP, the exposure variable, was calculated using waist circumference and triglyceride concentration. COPD diagnosis was determined using participants' self-reported information. To explore the association between LAP and COPD, multivariate logistic regression models were applied, and smoothing curve fitting was employed to examine any potential nonlinear patterns. Further analysis included stratified subgroup evaluations to assess how variables such as sex, smoking habits, and alcohol intake might impact the relationship between LAP and COPD.

Results

The findings indicated a significant increase in COPD risk with each one-unit rise in ln LAP, as evidenced by an Odds Ratio (OR) of 1.16 [95% Confidence Interval (CI): 1.04-1.30, p < 0.01]. Furthermore, a quartile-based analysis revealed that individuals in the highest ln LAP category had a considerably higher likelihood of developing COPD compared to those in the lowest category, with an OR of 1.35 (95% CI: 1.04-1.75, P for trend <0.01). Furthermore, the smoothing curve fitting identified a nonlinear and positive association between ln LAP and COPD, suggesting a steeper increase in risk as ln LAP values rise. Subgroup analysis suggested that this association remained fairly consistent across various demographic groups.

Conclusion

This study found a significant link between higher LAP levels and an elevated risk of COPD, with the association displaying a nonlinear pattern. As a marker of lipid accumulation abnormalities, LAP may serve as a valuable tool for assessing COPD risk and could inform strategies for early identification and targeted clinical management.

HDL Function and Atherosclerosis: Reactive Dicarbonyls as Promising Targets of Therapy

Epidemiologic studies detected an inverse relationship between HDL (high-density lipoprotein) cholesterol (HDL-C) levels and atherosclerotic cardiovascular disease (ASCVD), identifying HDL-C as a major risk factor for ASCVD and suggesting atheroprotective functions of HDL. However, the role of HDL-C as a mediator of risk for ASCVD has been called into question by the failure of HDL-C-raising drugs to reduce cardiovascular events in clinical trials. Progress in understanding the heterogeneous nature of HDL particles in terms of their protein, lipid, and small RNA composition has contributed to the realization that HDL-C levels do not necessarily reflect HDL function. The most examined atheroprotective function of HDL is reverse cholesterol transport, whereby HDL removes cholesterol from plaque macrophage foam cells and delivers it to the liver for processing and excretion into bile. Indeed, in several studies, HDL has shown inverse associations between HDL cholesterol efflux capacity and ASCVD in humans. Inflammation plays a key role in the pathogenesis of atherosclerosis and vulnerable plaque formation, and a fundamental function of HDL is suppression of inflammatory signaling in macrophages and other cells. Oxidation is also a critical process to ASCVD in promoting atherogenic oxidative modifications of LDL (low-density lipoprotein) and cellular inflammation. HDL and its proteins including apoAI (apolipoprotein AI) and PON1 (paraoxonase 1) prevent cellular oxidative stress and LDL modifications. Importantly, HDL in humans with ASCVD is oxidatively modified rendering HDL dysfunctional and proinflammatory. Modification of HDL with reactive carbonyl species, such as malondialdehyde and isolevuglandins, dramatically impairs the antiatherogenic functions of HDL. Importantly, treatment of murine models of atherosclerosis with scavengers of reactive dicarbonyls improves HDL function and reduces systemic inflammation, atherosclerosis development, and features of plaque instability. Here, we discuss the HDL antiatherogenic functions in relation to oxidative modifications and the potential of reactive dicarbonyl scavengers as a therapeutic approach for ASCVD.

The Impact of Aerobic Exercise on HDL Quantity and Quality: A Narrative Review

High-density lipoproteins comprise roughly 25-30% of the circulating proteins involved in the transport of lipids in circulation. These particles differ in size and lipid composition. Recent evidence suggests that the quality of HDL particles (which depends on shape, size and the composition of proteins and lipids determining HDL functionality) may be more important than their quantity. The functionality of HDL is mirrored by its cholesterol efflux activity, as well as its antioxidant (including the protection of LDL against oxidation), anti-inflammatory and antithrombotic properties. The results of many studies and meta-analyses imply the beneficial impact of aerobic exercise on HDL-C levels. Physical activity was found to be usually associated with an increase in HDL cholesterol and a decrease in LDL cholesterol and triglycerides. Exercise, apart from inducing quantitative alterations in serum lipids, exerts a beneficial impact on HDL particle maturation, composition and functionality. The Physical Activity Guidelines Advisory Committee Report underlined the importance of establishing a program recommending exercises that enable attainment of maximal advantage at the lowest level of risk. The aim of this manuscript is to review the impact of different types of aerobic exercise (various intensities and durations) on the level and quality of HDL.

Lipotoxicity, glucotoxicity and some strategies to protect vascular smooth muscle cell against proliferative phenotype in metabolic syndrome

Metabolic syndrome (MetS) is a risk factor for the development of cardiovascular disease (CVD) and atherosclerosis through a mechanism that involves vascular smooth muscle cell (VSMC) proliferation, lipotoxicity and glucotoxicity. Several molecules found to be increased in MetS, including free fatty acids, fatty acid binding protein 4, leptin, resistin, oxidized lipoprotein particles, and advanced glycation end products, influence VSMC proliferation. Most of these molecules act through their receptors on VSMCs by activating several signaling pathways associated with ROS generation in various cellular compartments. ROS from NADPH-oxidase and mitochondria have been found to promote VSMC proliferation and cell cycle progression. In addition, most of the natural or synthetic substances described in this review, including pharmaceuticals with hypoglycemic and hypolipidemic properties, attenuate VSMC proliferation by their simultaneous modulation of cell signaling and their scavenging property due to the presence of a phenolic ring in their structure. This review discusses recent data in the literature on the role that several MetS-related molecules and ROS play in the change from contractile to proliferative phenotype of VSMCs. Hence the importance of proposing an appropriate strategy to prevent uncontrolled VSMC proliferation using antioxidants, hypoglycemic and hypolipidemic agents.

Enhancement of High-Density Lipoprotein (HDL) Quantity and Quality by Regular and Habitual Exercise in Middle-Aged Women with Improvements in Lipid and Apolipoprotein Profiles: Larger Particle Size and Higher Antioxidant Ability of HDL

Regular exercise, especially aerobic exercise, is beneficial for increasing serum high-density lipoprotein-cholesterol (HDL-C) levels in the general population. In addition to the HDL-C quantity, exercise enhances HDL functionality, antioxidants, and cholesterol efflux. On the other hand, the optimal intensity and frequency of exercise to increase HDL quantity and enhance HDL quality in middle-aged women need to be determined. The current study was designed to compare the changes in HDL quantity and quality among middle-aged women depending on exercise intensity, frequency, and duration; participants were divided into a sedentary group (group 1), a middle-intensity group (group 2), and a high-intensity group (group 3). There were no differences in anthropometric parameters among the groups, including blood pressure, muscle mass, and handgrip strength. Although there was no difference in serum total cholesterol (TC) among the groups, the serum HDL-C and apolipoprotein (apo)A-I levels remarkably increased to 17% and 12%, respectively, in group 3. Serum low-density lipoprotein-cholesterol (LDL-C), glucose, triglyceride, and the apo-B/apoA-I ratio were remarkably decreased in the exercise groups depending on the exercise intensity; group 3 showed 13%, 10%, and 45% lower LDL-C, glucose, and triglyceride (TG), respectively, than group 1. The hepatic and muscle damage parameter, aspartate aminotransferase (AST), was significantly decreased in the exercise groups, but high-sensitivity C-reactive protein (CRP), alanine aminotransferase (ALT), and γ-glutamyl transferase (γ-GTP) were similar in the three groups. In LDL, the particle size was increased 1.5-fold (p < 0.001), and the oxidation extent was decreased by 40% with a 23% lower TG content in group 3 than in group 1. In the exercise groups (groups 2 and 3), LDL showed the slowest electromobility with a distinct band intensity compared to the sedentary group (group 1). In HDL2, the particle size was 2.1-fold increased (p < 0.001) in the exercise group (group 3) with a 1.5-fold increase in TC content compared to that in group 1, as well as significantly enhanced antioxidant abilities, paraoxonase (PON) activity, and ferric ion reduction ability (FRA). In HDL3, the particle size was increased 1.2-fold with a 45% reduction in TG in group 3 compared to group 1. With increasing exercise intensity, apoA-I expression was increased in HDL2 and HDL3, and PON activity and FRA were enhanced (p < 0.001). In conclusion, regular exercise in middle-aged women is associated with the elevation of serum HDL-C and apoA-I with the enhancement of HDL quality and functionality and an increase in the TC content, particle size, and antioxidant abilities. With the reduction in TG and oxidized products in LDL and HDL, lipoproteins could have more anti-atherogenic properties through regular exercise in an intensity-dependent manner.

A peptide derived from HSP60 reduces proinflammatory cytokines and soluble mediators: a therapeutic approach to inflammation

Cytokines are secretion proteins that mediate and regulate immunity and inflammation. They are crucial in the progress of acute inflammatory diseases and autoimmunity. In fact, the inhibition of proinflammatory cytokines has been widely tested in the treatment of rheumatoid arthritis (RA). Some of these inhibitors have been used in the treatment of COVID-19 patients to improve survival rates. However, controlling the extent of inflammation with cytokine inhibitors is still a challenge because these molecules are redundant and pleiotropic. Here we review a novel therapeutic approach based on the use of the HSP60-derived Altered Peptide Ligand (APL) designed for RA and repositioned for the treatment of COVID-19 patients with hyperinflammation. HSP60 is a molecular chaperone found in all cells. It is involved in a wide diversity of cellular events including protein folding and trafficking. HSP60 concentration increases during cellular stress, for example inflammation. This protein has a dual role in immunity. Some HSP60-derived soluble epitopes induce inflammation, while others are immunoregulatory. Our HSP60-derived APL decreases the concentration of cytokines and induces the increase of FOXP3+ regulatory T cells (Treg) in various experimental systems. Furthermore, it decreases several cytokines and soluble mediators that are raised in RA, as well as decreases the excessive inflammatory response induced by SARS-CoV-2. This approach can be extended to other inflammatory diseases.

Meta-analysis of the effects of smoking and smoking cessation on triglyceride levels

Smoking increases lipid levels, including triglycerides, leading to increased cardiovascular disease risk. We performed a meta-analysis to quantify the effects of smoking and smoking cessation on triglyceride levels. The PubMed and Scopus databases were searched to identify studies reporting either triglyceride levels in smokers and non-smokers or the effects of smoking cessation on triglyceride levels. Fixed- and random-effects models were used to perform the analyses when three or more studies/comparisons were available. We identified 169 and 21 studies evaluating the effects of smoking and smoking cessation, respectively, on triglyceride levels. Triglyceride levels were 0.50 mmol/L (95% confidence interval: 0.49-0.50 mmol/L) higher in smokers than non-smokers, but the effect differed widely across studies. No statistically significant effect was observed on triglyceride levels between baseline and 6 weeks (mean difference [MD] = 0.02 [-0.09, 0.12] mmol/L), 2 months (MD = 0.03 [-0.21, 0.27] mmol/L), 3 months (MD = 0.08 [-0.03, 0.21] mmol/L), or 1 year (MD = 0.04 [-0.06, 0.14] mmol/L) after quitting. However, a slightly significant decrease in triglyceride levels was observed at 1 month after cessation (MD = -0.15 [-0.15, -0.01] mmol/L). The results of this meta-analysis provide a basis for understanding the effects of smoking and smoking cessation on triglyceride levels, which could have important implications for public health.

Effects of smoking cessation using varenicline on the serum concentrations of oxidized high-density lipoprotein: Comparison with high-density lipoprotein cholesterol

BACKGROUND

The oxidized high-density lipoprotein (oxHDL) is a possible marker for cardiovascular diseases. This study investigated the effects of smoking cessation with varenicline (a partial agonist of nicotinic acetylcholine receptors) on the levels of oxHDL in the serum of subjects compared with those of high-density lipoprotein cholesterol (HDL-C).

METHODS

Data of 99 nicotine-dependent adult subjects who visited the smoking cessation outpatient services at International University of Health and Welfare Shioya Hospital were reviewed. Each subject was treated with varenicline titrated up to 1.0 mg twice daily for 12 weeks. Serum levels of oxHDL and HDL-C were repeatedly measured by enzyme-linked immunosorbent assay and enzymatic method, respectively.

RESULTS

The serum levels of oxHDL were significantly decreased from 163.2 ± 96.6 to 148.3 ± 80.7 U/mL (p = 0.034, n = 99). This effect was more prominent when the data of subjects in whom the treatment was objectively unsuccessful (exhaled carbon monoxide at 3 months ≥ 10 ppm) were omitted (from 166.6 ± 98.4 to 147.4 ± 80.6 U/mL; p = 0.0063, n = 93). In contrast, the serum levels of HDL-C were significantly increased (p = 0.0044, n = 99). There was a close relationship between the baseline levels of oxHDL and HDL-C (R = 0.45, p < 0.0001, n = 99). Changes in the levels of oxHDL were closely associated with changes in the levels of exhaled carbon monoxide in subjects in whom smoking cessation with varenicline was very effective (decrease in exhaled carbon monoxide by ≥ 15 ppm after treatment with varenicline; R = 0.42, p = 0.0052, n = 43).

CONCLUSIONS

Although there was a close relationship between the baseline serum concentrations of oxHDL and HDL-C, smoking cessation decreased oxHDL and increased HDL-C. This effect on oxHDL may be associated with the effectiveness of smoking cessation.

Anti-Inflammatory Activity of CIGB-258 against Acute Toxicity of Carboxymethyllysine in Paralyzed Zebrafish via Enhancement of High-Density Lipoproteins Stability and Functionality

Background: Hyperinflammation is frequently associated with the chronic pain of autoimmune disease and the acute death of coronavirus disease (COVID-19) via a severe cytokine cascade. CIGB-258 (Jusvinza®), an altered peptide ligand with 3 kDa from heat shock protein 60 (HSP60), inhibits the systemic inflammation and cytokine storm, but the precise mechanism is still unknown. Objective: The protective effect of CIGB-258 against inflammatory stress of N-ε-carboxymethyllysine (CML) was tested to provide mechanistic insight. Methods: CIGB-258 was treated to high-density lipoproteins (HDL) and injected into zebrafish and its embryo to test a putative anti-inflammatory activity under presence of CML. Results: Treatment of CML (final 200 μM) caused remarkable glycation of HDL with severe aggregation of HDL particles to produce dysfunctional HDL, which is associated with a decrease in apolipoprotein A-I stability and lowered paraoxonase activity. Degradation of HDL3 by ferrous ions was attenuated by a co-treatment with CIGB-258 with a red-shift of the Trp fluorescence in HDL. A microinjection of CML (500 ng) into zebrafish embryos resulted in the highest embryo death rate, only 18% of survivability with developmental defects. However, co-injection of CIGB-258 (final 1 ng) caused the remarkable elevation of survivability around 58%, as well as normal developmental speed. An intraperitoneal injection of CML (final 250 μg) into adult zebrafish resulted acute paralysis, sudden death, and laying down on the bottom of the cage with no swimming ability via neurotoxicity and inflammation. However, a co-injection of CIGB-258 (1 μg) resulted in faster recovery of the swimming ability and higher survivability than CML alone injection. The CML alone group showed 49% survivability, while the CIGB-258 group showed 97% survivability (p < 0.001) with a remarkable decrease in hepatic inflammation up to 50%. A comparison of efficacy with CIGB-258, Infliximab (Remsima®), and Tocilizumab (Actemra®) showed that the CIGB-258 group exhibited faster recovery and swimming ability with higher survivability than those of the Infliximab group. The CIGB-258 group and Tocilizumab group showed the highest survivability, the lowest plasma total cholesterol and triglyceride level, and the infiltration of inflammatory cells, such as neutrophils in hepatic tissue. Conclusion: CIGB-258 ameliorated the acute neurotoxicity, paralysis, hyperinflammation, and death induced by CML, resulting in higher survivability in zebrafish and its embryos by enhancing the HDL structure and functionality.

An updated analysis on the association of GSTM1 polymorphism and smoking exposure with the increased risk of coronary heart disease

Objective

To undertake a meta-analysis to investigate if there is an association between the glutathione S-transferase mu 1 (GSTM1) gene polymorphism, coronary artery disease (CAD) susceptibility and smoking.

Methods

Electronic databases, including PubMed®, Web of Science and Embase®, were searched for relevant case–control studies. Data were extracted and the odds ratio (OR) was calculated and appropriate statistical methods were used for the meta-analysis.

Results

The analysis included eight studies with a total of 1880 cases with CAD and 1758 control subjects. The results of this meta-analysis demonstrated that there is no association between the GSTM1 null and CAD (OR 1.24, 95% confidence interval [CI] 1.00, 1.55). An increased risk of CAD was observed in the smoking population with the GSTM1 null genotype (OR 1.48, 95% CI 1.02, 2.15). Subgroup analyses of geographical region, genotyping method and publication language category demonstrated potential relationships among gene polymorphism, smoking and CAD.

Conclusions

Based on the current literature, the GSTM1 null genotype was associated to CAD in the smoking population. The interaction between smoking and GSTM1 polymorphism may contribute to the susceptibility of CAD.

HDL and Oxidation

In this chapter, we will focus on HDLs' activity of inhibiting LDL oxidation and neutralizing some other oxidants. ApoA-I was known as the main antioxidant component in HDLs. The regulation of antioxidant capacity of HDL is mainly exhibited in regulation of apoA-I and alterations at the level of the HDL lipidome and the modifications of the proteome, especially MPO and PON1. HDL oxidation will influence the processes of inflammation and cholesterol transport, which are important processes in atherosclerosis, metabolic diseases, and many other diseases. In a word, HDL oxidation might be an effective antioxidant target in treatment of many diseases.

The Current Status of Research on High-Density Lipoproteins (HDL): A Paradigm Shift from HDL Quantity to HDL Quality and HDL Functionality

The quantity of high-density lipoproteins (HDL) is represented as the serum HDL-C concentration (mg/dL), while the HDL quality manifests as the diverse features of protein and lipid content, extent of oxidation, and extent of glycation. The HDL functionality represents several performance metrics of HDL, such as antioxidant, anti-inflammatory, and cholesterol efflux activities. The quantity and quality of HDL can change during one's lifetime, depending on infection, disease, and lifestyle, such as dietary habits, exercise, and smoking. The quantity of HDL can change according to age and gender, such as puberty, middle-aged symptoms, climacteric, and the menopause. HDL-C can decrease during disease states, such as acute infection, chronic inflammation, and autoimmune disease, while it can be increased by regular aerobic exercise and healthy food consumption. Generally, high HDL-C at the normal level is associated with good HDL quality and functionality. Nevertheless, high HDL quantity is not always accompanied by good HDL quality or functionality. The HDL quality concerns the morphology of the HDL, such as particle size, shape, and number. The HDL quality also depends on the composition of the HDL, such as apolipoproteins (apoA-I, apoA-II, apoC-III, serum amyloid A, and α-synuclein), cholesterol, and triglyceride. The HDL quality is also associated with the extent of HDL modification, such as glycation and oxidation, resulting in the multimerization of apoA-I, and the aggregation leads to amyloidogenesis. The HDL quality frequently determines the HDL functionality, which depends on the attached antioxidant enzyme activity, such as the paraoxonase and cholesterol efflux activity. Conventional HDL functionality is regression, the removal of cholesterol from atherosclerotic lesions, and the removal of oxidized species in low-density lipoproteins (LDL). Recently, HDL functionality was reported to expand the removal of β-amyloid plaque and inhibit α-synuclein aggregation in the brain to attenuate Alzheimer's disease and Parkinson's disease, respectively. More recently, HDL functionality has been associated with the susceptibility and recovery ability of coronavirus disease 2019 (COVID-19) by inhibiting the activity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The appearance of dysfunctional HDL is frequently associated with many acute infectious diseases and chronic aging-related diseases. An HDL can be a suitable biomarker to diagnose many diseases and their progression by monitoring the changes in its quantity and quality in terms of the antioxidant and anti-inflammatory abilities. An HDL can be a protein drug used for the removal of plaque and as a delivery vehicle for non-soluble drugs and genes. A dysfunctional HDL has poor HDL quality, such as a lower apoA-I content, lower antioxidant ability, smaller size, and ambiguous shape. The current review analyzes the recent advances in HDL quantity, quality, and functionality, depending on the health and disease state during one's lifetime.

ApoA-I mimetics reduce systemic and gut inflammation in chronic treated HIV

Novel therapeutic strategies are needed to attenuate increased systemic and gut inflammation that contribute to morbidity and mortality in chronic HIV infection despite potent antiretroviral therapy (ART). The goal of this study is to use preclinical models of chronic treated HIV to determine whether the antioxidant and anti-inflammatory apoA-I mimetic peptides 6F and 4F attenuate systemic and gut inflammation in chronic HIV. We used two humanized murine models of HIV infection and gut explants from 10 uninfected and 10 HIV infected persons on potent ART, to determine the in vivo and ex vivo impact of apoA-I mimetics on systemic and intestinal inflammation in HIV. When compared to HIV infected humanized mice treated with ART alone, mice on oral apoA-I mimetic peptide 6F with ART had consistently reduced plasma and gut tissue cytokines (TNF-α, IL-6) and chemokines (CX3CL1) that are products of ADAM17 sheddase activity. Oral 6F attenuated gut protein levels of ADAM17 that were increased in HIV-1 infected mice on potent ART compared to uninfected mice. Adding oxidized lipoproteins and endotoxin (LPS) ex vivo to gut explants from HIV infected persons increased levels of ADAM17 in myeloid and intestinal cells, which increased TNF-α and CX3CL1. Both 4F and 6F attenuated these changes. Our preclinical data suggest that apoA-I mimetic peptides provide a novel therapeutic strategy that can target increased protein levels of ADAM17 and its sheddase activity that contribute to intestinal and systemic inflammation in treated HIV. The large repertoire of inflammatory mediators involved in ADAM17 sheddase activity places it as a pivotal orchestrator of several inflammatory pathways associated with morbidity in chronic treated HIV that make it an attractive therapeutic target.

Good Cholesterol Gone Bad? HDL and COVID-19

The transmissible respiratory disease COVID-19, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has affected millions of people worldwide since its first reported outbreak in December of 2019 in Wuhan, China. Since then, multiple studies have shown an inverse correlation between the levels of high-density lipoprotein (HDL) particles and the severity of COVID-19, with low HDL levels being associated with an increased risk of severe outcomes. Some studies revealed that HDL binds to SARS-CoV-2 particles via the virus's spike protein and, under certain conditions, such as low HDL particle concentrations, it facilitates SARS-CoV-2 binding to angiotensin-converting enzyme 2 (ACE2) and infection of host cells. Other studies, however, reported that HDL suppressed SARS-CoV-2 infection. In both cases, the ability of HDL to enhance or suppress virus infection appears to be dependent on the expression of the HDL receptor, namely, the Scavenger Receptor Class B type 1 (SR-B1), in the target cells. SR-B1 and HDL represent crucial mediators of cholesterol metabolism. Herein, we review the complex role of HDL and SR-B1 in SARS-CoV-2-induced disease. We also review recent advances in our understanding of HDL structure, properties, and function during SARS-CoV-2 infection and the resulting COVID-19 disease.

Anti-inflammatory HDL effects are impaired in atrial fibrillation

High-density lipoprotein (HDL), best known for cholesterol transport, also has anti-inflammatory effects. Previous studies suggest involvement of myeloperoxidase (MPO) in modification of HDL. HDL bound Sphingosine-1-phosphate (S1P) has been implied to be an essential protein regarding beneficial HDL effects. In this study, we analyzed anti-inflammatory HDL properties in patients with atrial fibrillation (AF), a disease involving atrial inflammation, compared to non-AF controls and whether anti-inflammatory properties improve upon catheter ablation. Additionally, association with serum concentrations of MPO and S1P were assessed. We isolated HDL from 25 AF patients, 13 non-AF individuals and 14 AF patients at follow-up (FU) after catheter ablation. S1P was measured in a cohort of 141 AF and 21 FU patients. Following preincubation with HDL from either group, bovine aortic endothelial cells were stimulated using tumor necrosis factor α and expression of pro-inflammatory genes intercellular adhesion molecule 1 (ICAM1), vascular cell adhesion molecule 1 (VCAM1), E-selectin (SELE) and P-selectin (SELP) was assessed using qPCR. Concentrations of circulating protein of these genes as well as MPO and S1P were measured in serum samples. Compared to non-AF individuals HDL from AF patients suppressed gene expression of the pro-inflammatory adhesion molecules ICAM1, VCAM1, SELE and SELP 27%, 18%, 21% and 57% less, respectively (p < 0.05 for all except SELE p = 0.06). In FU patients, the anti-inflammatory HDL activity was improved (suppression of ICAM1 + 22%, VCAM1 + 10%, SELE + 38% and SELP + 75%, p < 0.05 for all except VCAM1 p = 0.08). AF patients using angiotensin converting enzyme inhibitors or angiotensin receptor blockers had better anti-inflammatory HDL properties than non-users (gene expression suppression at least 28% more, p < 0.05 for all except ICAM1 p = 0.051). Circulating protein concentrations were not correlated with in vitro gene-expression, but circulating P-selectin was generally elevated in AF and FU patients compared to non-AF patients. MPO plasma concentration was positively associated with gene-expression of ICAM1, VCAM1 and SELP (r² > 0.4, p < 0.05). Serum concentrations of S1P were increased in FU patients {1.201 µM [1.077–1.543]} compared to AF patients {0.953 µM [0.807–1.135], p < 0.01} but not correlated with ICAM1, VCAM1 and SELP gene expression. We conclude that the anti-inflammatory activity of HDL is impaired in AF patients, which might promote AF progression and AF-associated complications.

Native High-Density Lipoproteins (HDL) with Higher Paraoxonase Exerts a Potent Antiviral Effect against SARS-CoV-2 (COVID-19), While Glycated HDL Lost the Antiviral Activity

Human high-density lipoproteins (HDL) show a broad spectrum of antiviral activity in terms of anti-infection. Although many reports have pointed out a correlation between a lower serum HDL-C and a higher risk of COVID-19 infection and progression, the in vitro antiviral activity of HDL against SARS-CoV-2 has not been reported. HDL functionality, such as antioxidant and anti-infection, can be impaired by oxidation and glycation and a change to pro-inflammatory properties. This study compared the antiviral activity of native HDL with glycated HDL via fructosylation and native low-density lipoproteins (LDL). After 72 h of fructosylation, glycated HDL showed a typical multimerized protein pattern with an elevation of yellowish fluorescence. Glycated HDL showed a smaller particle size with an ambiguous shape and a loss of paraoxonase activity up to 51% compared to native HDL. The phagocytosis of acetylated LDL was accelerated 1.3-fold by glycated HDL than native HDL. Native HDL showed 1.7 times higher cell viability and 3.6 times higher cytopathic effect (CPE) inhibition activity against SARS-CoV-2 than that of glycated HDL under 60 μg/mL (approximately final 2.2 μM) in a Vero E6 cell. Native HDL showed EC50 = 52.1 ± 1.1 μg/mL (approximately final 1.8 μM) for the CPE and CC50 = 79.4 ± 1.5 μg/mL (around 2.8 μM). The selective index (SI) of native HDL was calculated to be 1.52. In conclusion, native HDL shows potent antiviral activity against SARS-CoV-2 without cytotoxicity, while the glycation of HDL impairs its antiviral activity. These results may explain why patients with diabetes mellitus or hypertension are more sensitive to a COVID-19 infection and have a higher risk of mortality.

Association of common gene-smoking interactions with elevated plasma apolipoprotein B concentration

Background

Increased apolipoprotein (apo) B level (hyperapoB) is a strong predictor of cardiovascular disease (CVD), even in patients who achieve recommended LDL-Cholesterol (LDL-C) goals. ApoB level, an important correlate of metabolic syndrome (MetS), is influenced by several gene-environment interactions. Some of them are rare and can explain a large proportion of apoB variance, whereas others more common have variable effects. The aim of this study was to evaluate the association of interaction between smoking and common hyperapoB gene variants (PPARα-L162V, lipoprotein lipase loss-of function mutation, apo e4 allele or apo E2/2 genotype) with plasma apoB concentrations, according to the expression of MetS.

Methods

This study was performed among 1798 subjects. Smoking was defined as non/mild smokers vs. moderate-to-heavy smokers. ApoB levels were determined using nephelometry. Logistic regression models were used to document interactions between smoking habits and the presence of hyperapoB gene variants on the relative odds to exhibit increased plasma apoB concentrations.

Results

Around 29% of individuals with a low-risk lipid profile without MetS component had hyperapoB. Smoking and the presence of hyperapoB gene variants tended to be associated with higher plasma apoB levels even in presence of low-LDL-C. There was a significant interaction (P = 0.04) between the presence of ≥1 gene variants and smoking on the risk to exhibit hyperapoB among subjects with low risk profile in primary prevention.

Conclusions

Combination of life habits assessment and some common genes variants may detect a significant proportion of patients with increased apoB levels, and therefore a higher risk of CVD, who could have been initially perceived as low-risk.

Detection and inhibition of lipid-derived radicals in low-density lipoprotein

Oxidized low density lipoprotein (Ox-LDL) is implicated in a variety of oxidative diseases. To clarify the mechanisms involved and facilitate the investigation of therapeutics, we previously developed a detection method for lipid-derived radicals using the fluorescent probe 2,2,6-trimethyl-6-pentyl-4-(4-nitrobenzo[1,2,5]oxadiazol-7-ylamino)piperidine-1-oxyl (NBD-Pen). In this study, NBD-Pen was used to detect lipid-derived radicals in Ox-LDL from in vitro and in vivo samples using an iron overloaded mouse model. By following the timeline of lipid radical generation using this method, the iron overloaded mice could be successfully treated with the antioxidant Trolox, resulting in successful lowering of the plasma lipid peroxidation, aspartate transaminase and alanine transaminase levels. Furthermore, using a combination therapy of the chelating agent deferoxamine (DFX) and Trolox, liver injury and oxidative stress markers were also reduced in iron overloaded mice. The NBD-Pen method is highly sensitive as well as selective and is suitable for targeting minimally modified LDL compared with other existing methods.

Cadmium exposure exacerbates severe hyperlipidemia and fatty liver changes in zebrafish via impairment of high-density lipoproteins functionality

Cadmium (Cd) is a heavy metal with several toxicities that have destructive effect on most organ systems. However, its toxic effects on human lipoproteins are largely remained unknown especially in hyperlipidemic zebrafish model. Treatment of human high-density lipoprotein (HDL) with cadmium chloride (CdCl₂, final 12 and 24μM) caused spontaneous formation of multimeric apoA-I as well as increased production of glycated extent products. Cd-HDL₃ accelerated uptake of oxidized LDL (oxLDL) into macrophages and induced severe senescence in human dermal fibroblast (HDF) cells. Microinjection of Cd-HDL₃ into zebrafish embryos resulted in acute embryonic toxicity with high mortality. Exposure of zebrafish embryos to water containing CdCl₂ (final 12 and 24μM) caused early embryonic death along with increased production of oxidized products and impairment of skeletal development. Consumption of CdCl₂ (12 and 24μM) by zebrafish for 4weeks resulted in severe elevation of plasma total cholesterol (TC) and triglyceride (TG) levels as well as cholesteryl ester (CE) transfer activity. Furthermore, consumption of CdCl₂ resulted in acceleration of fatty liver changes and increased production of reactive oxygen species (ROS). In conclusion, CdCl₂ caused structural modification of HDL₃ and impaired the beneficial functions of HDL₃, including anti-oxidation, anti-atherosclerosis, and anti-senescence effects. Consumption of CdCl₂ also resulted in exacerbated hyperlipidemia and fatty liver changes in zebrafish via enhancement of cholesteryl ester transfer protein (CETP) activity.

Association between the Serum Metabolic Profile and Lung Function in Chronic Obstructive Pulmonary Disease

OBJECTIVES

Although dietary patterns are known to modulate disease severity in patients with chronic obstructive pulmonary disease (COPD), the relationship between the circulating lipid profile and lung function in COPD has not been studied extensively.

MATERIAL AND METHODS

There were 43 COPD patients with a history of smoking and 39 patients with a history of biomass fuel exposure recruited in this study, along with 43 age-matched healthy controls. All participants underwent complete lung function profiling, and their glucose and lipid profiles were measured. The association between the metabolic profile and lung function was assessed using the Spearman's rank-order correlation coefficient.

RESULTS

52.4% of the COPD patients were smokers compared to the healthy group (46.5%). We found an inverse correlation between triglyceride and functional residual capacity (p=-0.21, p=0.05) and a positive association between serum cholesterol and overall airway resistance (R5) (p=0.24, p=0.04) and central airway resistance (R20) (p=0.32, p=0.004). Low-density lipoprotein (LDL) cholesterol and high-density lipoprotein (HDL) ratio and LDL/HDL ratio were also found to correlate with R5 (p=0.25, 0.23, and 0.22, respectively) and R20 (p=0.31, 0.24, and 0.24, respectively). No significant association was observed between other metabolites and either spirometric or plethysmographic lung function indices.

CONCLUSION

High serum triglyceride and cholesterol may increase the resistance in the airways, which may lead to increased airway obstruction. Therefore, monitoring of lipid profile should be considered in the diagnosis and management of COPD.

Cord and maternal sera from small neonates share dysfunctional lipoproteins with proatherogenic properties: Evidence for Barker's hypothesis

BACKGROUND

Fetal growth restriction (GR) is associated with perinatal mortality and subsequent metabolic disorders in adulthood. Until now, there is little information regarding changes in the properties of lipoproteins from growth-restricted fetuses and their maternal sera.

OBJECTIVE

To identify unique lipoprotein biomarkers for fetal GR in maternal and cord sera from small neonates, we analyzed lipoprotein compositions and functions.

METHODS

Lipoprotein compositions and functions were compared between cord blood and maternal blood among small for gestational age neonates (SGA; n = 15, 2589 ± 50 g) and appropriate for gestational age neonates (AGA; n = 15) in Korea.

RESULTS

Cord blood from the SGA group showed 2-fold higher triglyceride (TG) and TG/high-density lipoprotein cholesterol levels than the AGA group as well as significantly lower (up to 20%) paraoxonase activity and apolipoprotein (apo) A-I content. The SGA group showed the highest cholesteryl ester transfer protein activities in both cord and maternal sera. SGA neonates showed elevated apo-B content in very low-density lipoprotein, 52% reduction of apo A-I content in high-density lipoprotein, and 30% increased glycation (P < .001) compared with AGA neonates. Especially, low-density lipoprotein from the SGA group showed 1.9-fold higher sensitivity to oxidation as well as 3-fold greater uptake into macrophages, suggesting stronger proatherosclerotic properties. Lipoproteins from maternal serum of SGA neonates showed greater oxidation along with TG enrichment and loss of antioxidant ability. On microinjection of cord serum (50 nL) into zebrafish embryos, the SGA group showed the most severe embryonic damage.

CONCLUSIONS

Lipoproteins from cord and maternal sera of SGA neonates resulted in severe impairment of functional and structural correlations accompanied by greater pro-oxidant and proatherosclerotic properties.

Antioxidative activity of high-density lipoprotein (HDL): Mechanistic insights into potential clinical benefit

Uptake of low-density lipoprotein (LDL) particles by macrophages represents a key step in the development of atherosclerotic plaques, leading to the foam cell formation. Chemical modification of LDL is however necessary to induce this process. Proatherogenic LDL modifications include aggregation, enzymatic digestion and oxidation. LDL oxidation by one-electron (free radicals) and two-electron oxidants dramatically increases LDL affinity to macrophage scavenger receptors, leading to rapid LDL uptake and fatty streak formation. Circulating high-density lipoprotein (HDL) particles, primarily small, dense, protein-rich HDL3, provide potent protection of LDL from oxidative damage by free radicals, resulting in the inhibition of the generation of pro-inflammatory oxidized lipids. HDL-mediated inactivation of lipid hydroperoxides involves their initial transfer from LDL to HDL and subsequent reduction to inactive hydroxides by redox-active Met residues of apolipoprotein A-I. Several HDL-associated enzymes are present at elevated concentrations in HDL3 relative to large, light HDL2 and can be involved in the inactivation of short-chain oxidized phospholipids. Therefore, HDL represents a multimolecular complex capable of acquiring and inactivating proatherogenic lipids. Antioxidative function of HDL can be impaired in several metabolic and inflammatory diseases. Structural and compositional anomalies in the HDL proteome and lipidome underlie such functional deficiency. Concomitant normalization of the metabolism, circulating levels, composition and biological activities of HDL particles, primarily those of small, dense HDL3, can constitute future therapeutic target.

Infusional high-density lipoproteins therapies as a novel strategy for treating atherosclerosis

High-density lipoproteins (HDL) have received considerable interest as a target for the development of novel anti-atherosclerotic agents beyond conventional approaches to lipid lowering. While a number of approaches have focused on modifying remodeling and expression pathways implicated in the regulation of HDL levels, an additional approach involves simply infusions of delipidated HDL. Several groups have advanced HDL infusions to clinical development with intriguing signs suggesting potentially favorable impacts at the level of the artery wall. The findings of early studies of infusional HDL therapies will be reviewed.

Breast Milk from Smokers Contains Less Cholesterol and Protein and Smaller Size of Apolipoprotein A-I Resulting in Lower Zebrafish Embryo Survivability

BACKGROUND

To determine the quality of breast milk (BM), we compared the functions of BM from ex-smokers and nonsmokers.

SUBJECTS AND METHODS

We analyzed the contents of lipids, glucose, and protein in BM from ex-smokers (10 cigarettes/day for 13 ± 3 years) as well as infant formula.

RESULTS

Nonsmokers' BM showed 2.4- and 1.4-fold higher cholesterol and protein contents, respectively, than BM from smokers. Infant formula contained almost no cholesterol, but did show remarkably higher glucose and triglyceride levels than BM. Microinjection of BM (50 nL) from nonsmokers and smokers into zebrafish embryos resulted in 59% and 44% survival, respectively, whereas formula injection resulted in 31% survival. The higher cholesterol and protein contents of BM were directly correlated with higher embryo survivability, suggesting that cholesterol content is directly and critically associated with growth of neonate infants. Smokers' BM contained smaller-sized apolipoproteinA-I (apoA-I) (24.4 ± 0.2 kDa) than BM from nonsmokers (26.7 ± 0.4 kDa), suggesting that putative modification and cleavage occurred in apoA-I. BM containing higher molecular weight apoA-I resulted in higher embryo survivability.

CONCLUSIONS

Smoking before pregnancy can affect the composition and quality of BM, resulting in almost complete loss of cholesterol and protein, especially lactoferrin, lactalbumin, and apoA-I, accompanied by proteolytic degradation. These impairment effects of BM are associated with elevation of oxidative stress and lower embryo survivability.

Inducing apolipoprotein A-I synthesis to reduce cardiovascular risk: from ASSERT to SUSTAIN and beyond

Increasing attention has focused on efforts to promote the biological activities of high-density lipoproteins (HDL) in order to reduce cardiovascular risk. Targeting apolipoprotein A-I (apoA-I), the major protein carried on HDL particles, represents an attractive approach to promoting HDL by virtue of its ability to increase endogenous synthesis of functional HDL particles. A number of pharmacological strategies that target apoA-I, including upregulation of its production with the bromodomain and extraterminal (BET) protein inhibitor RVX-208, development of short peptide sequences that mimic its action, and administration as a component of reconstituted HDL particles, have undergone clinical development. The impact of these approaches on cardiovascular biomarkers will be reviewed.

Oxidized lipoproteins are associated with markers of inflammation and immune activation in HIV-1 infection

OBJECTIVE

The pathogenesis of immune dysfunction in chronic HIV-1 infection is unclear, and a potential role for oxidized lipids has been suggested. We hypothesize that both oxidized HDL and LDL (HDLox and LDLox) contribute to HIV-1-related immune dysfunction.

STUDY

In the AIDS Clinical Trials Group A5260, 234 HIV-infected antiretroviral therapy (ART)-naive participants were randomized to receive tenofovir-emtricitabine and protease inhibitors or raltegravir and had HIV-1 RNA less than 50 copies/ml by week 24 and thereafter.

METHODS

Associations between biomarkers of inflammation (IL-6, high-sensitivity C-reactive protein and D-dimer), immune activation (sCD163, sCD14, soluble IL-2 receptor, CD38 and HLA-DR), inflammatory monocytes (CD14CD16), T-cell senescence (CD28 and CD57) and exhaustion (PD1), and HDLox, LDLox were assessed at entry and after ART (week 96) with Spearman (partial) correlations.

RESULTS

HDLox declined and LDLox increased over 96 weeks of ART. Positive associations were observed at baseline and over time between HDLox (but not consistently for LDLox) and most markers of inflammation and immune activation (but not senescence/exhaustion), even after adjustment for multiple comparisons, demographics, entry CD4 cell count and HIV-1 RNA. HDLox was positively associated with IL-6 (r = 0.19 - 0.29, P < 0.01) and sCD163 (r = 0.14 - 0.41, P ≤ 0.04) at all time points.

CONCLUSION

These prospective longitudinal data suggest that oxidized lipoproteins may contribute to persistent immune activation on ART.

Breast Milk from Frequent Trans Fatty Acid Consumers Shows High Triglyceride and Glucose Levels, but Low Cholesterol and Apolipoprotein A-I levels, with Resulting Impaired In Vitro Zebrafish Embryo Growth and Survival

BACKGROUND

It is well known that breast milk is the best nutritional source for infant growth. However, there has been no information about the quality of breast milk from individuals who daily consume a trans fatty acid (TFA)-enriched diet.

SUBJECTS AND METHODS

We performed compositional and functional analyses with breast milk from lactating mothers, in terms of lipid content and zebrafish embryo survivability, among individuals who daily consumed TFA-enriched food (n = 5), normal diet as control (n = 5), and powder formula (n = 5).

RESULTS

In lipid content of breast milk, the control group showed 2.5- and 4.5-fold higher cholesterol content than the TFA group and infant formula, respectively. The TFA group and infant formula showed 1.8- and 2.0-fold higher triglyceride (TG) than the control group. Moreover, the TFA group and formula showed 1.4- and 4.8-fold higher glucose levels compared with control. The TFA group also showed 25% lower protein content than control. Microinjection with breast milk (50 nL) from the TFA group showed significantly lower zebrafish embryo survivability (50% ± 4%) compared with the control (66% ± 5%), whereas microinjection with formula showed the lowest survivability (39% ± 5%) with the slowest developmental speed. Immunodetection revealed that breast milk from the TFA group showed smaller-sized apoA-I (25.5 ± 0.6 kDa) than that from the control group (27.5 ± 1.5 kDa), whereas formula did not contain apoA-I. Larger apoA-I size in breast milk was directly associated with higher embryo survivability.

CONCLUSIONS

Breast milk from the TFA group showed increased TG and loss of cholesterol, lactalbumin (14 kDa), and apoA-I proteins, resulting in functional impairment of development and growth.

Effects of the Particulate Matter₂.₅ (PM₂.₅) on Lipoprotein Metabolism, Uptake and Degradation, and Embryo Toxicity

Particulate matter2.5 (PM2.5) is notorious for its strong toxic effects on the cardiovascular, skin, nervous, and reproduction systems. However, the molecular mechanism by which PM2.5 aggravates disease progression is poorly understood, especially in a water-soluble state. In the current study, we investigated the putative physiological effects of aqueous PM2.5 solution on lipoprotein metabolism. Collected PM2.5 from Seoul, Korea was dissolved in water, and the water extract (final 3 and 30 ppm) was treated to human serum lipoproteins, macrophages, and dermal cells. PM2.5 extract resulted in degradation and aggregation of high-density lipoprotein (HDL) as well as low-density lipoprotein (LDL); apoA-I in HDL aggregated and apo-B in LDL disappeared. PM2.5 treatment (final 30 ppm) also induced cellular uptake of oxidized LDL (oxLDL) into macrophages, especially in the presence of fructose (final 50 mM). Uptake of oxLDL along with production of reactive oxygen species was accelerated by PM2.5 solution in a dose-dependent manner. Further, PM2.5 solution caused cellular senescence in human dermal fibroblast cells. Microinjection of PM2.5 solution into zebrafish embryos induced severe mortality accompanied by impairment of skeletal development. In conclusion, water extract of PM2.5 induced oxidative stress as a precursor to cardiovascular toxicity, skin cell senescence, and embryonic toxicity via aggregation and proteolytic degradation of serum lipoproteins.

Consumption of high-dose vitamin C (1250 mg per day) enhances functional and structural properties of serum lipoprotein to improve anti-oxidant, anti-atherosclerotic, and anti-aging effects via regulation of anti-inflammatory microRNA

Background Although the health effects of vitamin C are well known, its physiological effect on serum lipoproteins and microRNA still remain to be investigated, especially daily consumption of a high dosage. Objectives To investigate the physiological effect of vitamin C on serum lipoprotein metabolism in terms of its anti-oxidant and anti-glycation activities, and gene expression via microRNA regulation. Methods We analyzed blood parameters and lipoprotein parameters in young subjects (n = 46, 22 ± 2 years old) including smokers who consumed a high dose of vitamin C (1250 mg) daily for 8 weeks. Results Antioxidant activity of serum was enhanced with the elevation of Vit C content in plasma during 8 weeks consumption. In the LDL fraction, the apo-B48 band disappeared at 8 weeks post-consumption in all subjects. In the HDL fraction, apoA-I expression was enhanced by 20% at 8 weeks, especially in male smokers. In the lipoprotein fraction, all subjects showed significantly reduced contents of advanced glycated end products and reactive oxygen species (ROS). Triglyceride (TG) contents in each LDL and HDL fraction were significantly reduced in all groups following the Vit C consumption, suggesting that the lipoprotein was changed to be more anti-inflammatory and atherogenic properties. Phagocytosis of LDL, which was purified from each individual, into macrophages was significantly reduced at 8-weeks post-consumption of vitamin C. Anti-inflammatory and anti-senescence effects of HDL from all subjects were enhanced after the 8-weeks consumption. The expression level of microRNA 155 in HDL3 was reduced by 49% and 75% in non-smokers and smokers, respectively. Conclusion The daily consumption of a high dose of vitamin C for 8 weeks resulted in enhanced anti-senescence and anti-atherosclerotic effects via an improvement of lipoprotein parameters and microRNA expression through anti-oxidation and anti-glycation, especially in smokers.

Dysfunctional HDL and atherosclerotic cardiovascular disease

High-density lipoproteins (HDLs) protect against atherosclerosis by removing excess cholesterol from macrophages through the ATP-binding cassette transporter A1 (ABCA1) and ATP-binding cassette transporter G1 (ABCG1) pathways involved in reverse cholesterol transport. Factors that impair the availability of functional apolipoproteins or the activities of ABCA1 and ABCG1 could, therefore, strongly influence atherogenesis. HDL also inhibits lipid oxidation, restores endothelial function, exerts anti-inflammatory and antiapoptotic actions, and exerts anti-inflammatory actions in animal models. Such properties could contribute considerably to the capacity of HDL to inhibit atherosclerosis. Systemic and vascular inflammation has been proposed to convert HDL to a dysfunctional form that has impaired antiatherogenic effects. A loss of anti-inflammatory and antioxidative proteins, perhaps in combination with a gain of proinflammatory proteins, might be another important component in rendering HDL dysfunctional. The proinflammatory enzyme myeloperoxidase induces both oxidative modification and nitrosylation of specific residues on plasma and arterial apolipoprotein A-I to render HDL dysfunctional, which results in impaired ABCA1 macrophage transport, the activation of inflammatory pathways, and an increased risk of coronary artery disease. Understanding the features of dysfunctional HDL or apolipoprotein A-I in clinical practice might lead to new diagnostic and therapeutic approaches to atherosclerosis.

Impaired antioxidant HDL function is associated with premature myocardial infarction

BACKGROUND

There is growing evidence that the predictive value of HDL cholesterol levels for cardiovascular risk stratification is limited in patients with coronary artery disease (CAD). HDL function seems to be a more sensitive surrogate of cardiovascular risk estimation than simple serum levels. Therefore, we aimed to assess whether impaired antioxidant HDL function is involved in the development of premature acute myocardial infarction (AMI).

METHODS

In this multicentre case-control study, we compared the antioxidant function of HDL, measured by the HDL inflammatory index (HII), and HDL particle size in 184 patients comprising 92 patients with AMI at a very young age (≤40 years of age) and 92 age- and gender-matched controls.

RESULTS

Antioxidant capacities of HDL were significantly impaired in the acute phase of AMI (HII of 1·50 [IQR 1·10-1·74] vs. 0·56 [IQR 0·41-0·86] in controls, P < 0·001 as well as in the chronic stable phase 1 year after the event (HII of 0·85 [IQR 0·72-1·03] vs. 0·56 [IQR 0·41-0·86], P < 0·001) compared to controls. Moreover, HDL function in the stable phase remained significantly associated with premature MI in adjusted logistic regression analysis with an OR of 2·24 per SD increase of HII (95% CI 1·28-3·91; P = 0·005). Analyses of HDL size revealed a significant correlation between all HDL subfractions and HDL function in controls, whereas this correlation was lost for large and intermediate HDL in AMI patients.

CONCLUSION

Impaired antioxidant function of HDL is independently associated with the development of premature AMI. The maintenance of HDL function might evolve into a significant therapeutic target, especially in patients with premature CAD.

SR-BI mediates high density lipoprotein (HDL)-induced anti-inflammatory effect in macrophages

High density lipoprotein (HDL) receptor, scavenger receptor class B, type I (SR-BI), mediates selective cholesteryl ester uptake from lipoproteins into the liver as well as cholesterol efflux from macrophages to HDL. Recently, strong evidence has demonstrated the anti-inflammatory effect of HDL, although the mechanism of action is not fully understood. In this study, we showed that the anti-inflammatory effects of HDL are dependent on SR-BI expression in THP-1 macrophages. Consistent with earlier findings, pretreatment of macrophages with HDL abolished LPS-induced TNFα production. HDL also inhibited LPS-induced NF-κB activation. In addition, knockdown of SR-BI or inhibition of SR-BI ligand binding abolished the anti-inflammatory effect of HDL. SR-BI is a multi-ligand receptor that binds to modified lipoproteins as well as native HDL. Since modified lipoproteins have pro-inflammatory properties, it is unclear whether SR-BI activated by modified HDL has an anti- or pro-inflammatory effect. Glycated HDL induced NF-κB activation and cytokine production in macrophages in vitro, suggesting a pro-inflammatory effect for modified HDL. Moreover, inhibition of SR-BI function or expression potentiated glycated HDL-induced TNF-α production, suggesting an anti-inflammatory effect for SR-BI. In conclusion, SR-BI plays an important function in regulating HDL-mediated anti-inflammatory response in macrophages.