Small dense low density lipoprotein has increased affinity for LDL receptor-independent cell surface binding sites: a potential mechanism for increased atherogenicity

Substitution of dietary monounsaturated fatty acids from olive oil for saturated fatty acids from lard increases low-density lipoprotein apolipoprotein B-100 fractional catabolic rate in subjects with dyslipidemia associated with insulin resistance: a randomized controlled trial

BACKGROUND

The substitution of monounsaturated acids (MUFAs) for saturated fatty acids (SFAs) is recommended for cardiovascular disease prevention but its impact on lipoprotein metabolism in subjects with dyslipidemia associated with insulin resistance (IR) remains largely unknown.

OBJECTIVES

This study aimed to evaluate the impact of substituting MUFAs for SFAs on the in vivo kinetics of apolipoprotein (apo)B-containing lipoproteins and on the plasma lipidomic profile in adults with IR-induced dyslipidemia.

METHODS

Males and females with dyslipidemia associated with IR (n = 18) were recruited for this crossover double-blind randomized controlled trial. Subjects consumed, in random order, a diet rich in SFAs (SFAs: 13.4%E; MUFAs: 14.4%E) and a diet rich in MUFAs (SFAs: 7.1%E; MUFAs: 20.7%E) in fully controlled feeding conditions for periods of 4 wk each, separated by a 4-wk washout. At the end of each diet, fasting plasma samples were taken together with measurements of the in vivo kinetics of apoB-containing lipoproteins.

RESULTS

Substituting MUFAs for SFAs had no impact on triglyceride-rich lipoprotein apoB-48 fractional catabolic rate (FCR) (Δ = -8.9%, P = 0.4) and production rate (Δ = 0.0%, P = 0.9), although it decreased very low-density lipoprotein apoB-100 pool size (PS) (Δ = -22.5%; P = 0.01). This substitution also reduced low-density lipoprotein cholesterol (LDL-C) (Δ = -7.0%; P = 0.01), non-high-density lipoprotein cholesterol (Δ = -2.5%; P = 0.04), and LDL apoB-100 PS (Δ = -6.0%; P = 0.05). These differences were partially attributed to an increase in LDL apoB-100 FCR (Δ = +1.6%; P = 0.05). The MUFA diet showed reduced sphingolipid concentrations and elevated glycerophospholipid levels compared with the SFA diet.

CONCLUSIONS

This study demonstrated that substituting dietary MUFAs for SFAs decreases LDL-C levels and LDL PS by increasing LDL apoB-100 FCR and results in an overall improved plasma lipidomic profile in individuals with IR-induced lipidemia.

TRIAL REGISTRATION

This trial was registered as clinicaltrials.gov as NCT03872349.

A novel assay to measure low-density lipoproteins binding to proteoglycans

BACKGROUND

The binding of low-density lipoprotein (LDL) to proteoglycans (PGs) in the extracellular matrix (ECM) of the arterial intima is a key initial step in the development of atherosclerosis. Although many techniques have been developed to assess this binding, most of the methods are labor-intensive and technically challenging to standardize across research laboratories. Thus, sensitive, and reproducible assay to detect LDL binding to PGs is needed to screen clinical populations for atherosclerosis risk.

OBJECTIVES

The aim of this study was to develop a quantitative, and reproducible assay to evaluate the affinity of LDL towards PGs and to replicate previously published results on LDL-PG binding.

METHODS

Immunofluorescence microscopy was performed to visualize the binding of LDL to PGs using mouse vascular smooth muscle (MOVAS) cells. An in-cell ELISA (ICE) was also developed and optimized to quantitatively measure LDL-PG binding using fixed MOVAS cells cultured in a 96-well format.

RESULTS

We used the ICE assay to show that, despite equal APOB concentrations, LDL isolated from adults with cardiovascular disease bound to PG to a greater extent than LDL isolated from adults without cardiovascular disease (p<0.05).

CONCLUSION

We have developed an LDL-PG binding assay that is capable of detecting differences in PG binding affinities despite equal APOB concentrations. Future work will focus on candidate apolipoproteins that enhance or diminish this interaction.

LDL binding to cell receptors and extracellular matrix is proatherogenic in obesity but improves after bariatric surgery

Obesity is a major global public health issue involving dyslipidemia, oxidative stress, inflammation, and increased risk of CVD. Weight loss reduces this risk, but the biochemical underpinnings are unclear. We explored how obesity and weight loss after bariatric surgery influence LDL interactions that trigger proatherogenic versus antiatherogenic processes. LDL was isolated from plasma of six patients with severe obesity before (basal) and 6-12 months after bariatric surgery (basal BMI = 42.7 kg/m2; 6-months and 12-months postoperative BMI = 34.1 and 30 kg/m2). Control LDL were from six healthy subjects (BMI = 22.6 kg/m2). LDL binding was quantified by ELISA; LDL size and charge were assessed by chromatography; LDL biochemical composition was determined. Compared to controls, basal LDL showed decreased nonatherogenic binding to LDL receptor, which improved postoperatively. Conversely, basal LDL showed increased binding to scavenger receptors LOX1 and CD36 and to glycosaminoglycans, fibronectin and collagen, which is proatherogenic. One year postoperatively, this binding decreased but remained elevated, consistent with elevated lipid peroxidation. Serum amyloid A and nonesterified fatty acids were elevated in basal and postoperative LDL, indicating obesity-associated inflammation. Aggregated and electronegative LDL remained elevated, suggesting proatherogenic processes. These results suggest that obesity-induced inflammation contributes to harmful LDL alterations that probably increase the risk of CVD. We conclude that in obesity, LDL interactions with cell receptors and extracellular matrix shift in a proatherogenic manner but are partially reversed upon postoperative weight loss. These results help explain why the risk of CVD increases in obesity but decreases upon weight loss.

Dietary saturated fat and cholesterol: cracking the myths around eggs and cardiovascular disease

Whilst dietary cholesterol guidelines have waivered through the years with historic restrictions lifted for the majority of the general population, recommendations to reduce saturated fat intake have been the mainstay of dietary guidelines since the 1980s and were recently reinforced by the Scientific Advisory Committee on Nutrition (SACN). Cholesterol metabolism is complex, with saturated fat known to have a more significant contribution at raising levels of low-density lipoprotein (LDL) cholesterol, a well-established risk factor for cardiovascular disease (CVD). However, it is clear from metabolic research that hyper-responsiveness to both dietary cholesterol and saturated fat exists; hence, for specific subsets of the population, reductions in both nutrients may be indicated. With this in mind, the current article aims to provide an overview of the mechanisms underlying biological variation in responsiveness and introduces research currently underway which will hopefully identify simple biomarkers that can be used to predict responsiveness and permit tailored, personalised, dietary advice. Eggs are a well-known source of dietary cholesterol whilst being low in saturated fat. A common question encountered in clinical practice is must individuals limit intake to manage blood cholesterol levels. This article summarises key recent papers which confirm that eggs can be enjoyed as part of a healthy balanced diet, whilst highlighting the need for further research in certain population groups, e.g. in individuals with diabetes.

Use of Apolipoprotein B in the Era of Precision Medicine: Time for a Paradigm Change?

Atherosclerotic cardiovascular disease (ASCVD) remains the leading cause of death worldwide and the risk of a major cardiovascular event is highest among those with established disease. Ongoing management of these patients relies on the accurate assessment of their response to any prescribed therapy, and their residual risk, in order to optimize treatment. Recent international guidelines and position statements concur that the plasma concentration of apolipoprotein B (apoB) is the most accurate measure of lipoprotein associated ASCVD risk. This is especially true for the growing number of individuals with diabetes, obesity, or the metabolic syndrome, and those on statin therapy. Most guidelines, however, continue to promote LDL-C as the primary risk marker due to uncertainty as to whether the greater accuracy of apoB is sufficient to warrant a paradigm shift. Recommendations regarding apoB measurement vary, and the information provided on how to interpret apoB results is sometimes insufficient, particularly for non-lipid specialists. Misinformation regarding the reliability of the assays is also frequently repeated despite its equivalent or better standardization than many other diagnostic assays. Thus, demand for apoB testing is relatively low, which means there is little incentive to increase its availability or reduce its cost. In this review, we examine the results of recent clinical outcomes studies and meta-analyses on the relative values of apoB, LDL-C, and non-HDL-C as markers of ASCVD risk. Although there is seemingly minimal difference among these markers when only population-based metrics are considered, it is evident from our analysis that, from a personalized or precision medicine standpoint, many individuals would benefit, at a negligible total cost, if apoB measurement were better integrated into the diagnosis and treatment of ASCVD.

The LDL-C/ApoB ratio predicts cardiovascular and all-cause mortality in the general population

BACKGROUND

Generally, low-density lipoprotein (LDL) particle size can be inferred from the LDL cholesterol concentration to total apolipoprotein B concentration ratio (LDL-C/ApoB ratio, hereinafter called LAR), which is a good predictor of cardiovascular disease. However, the predictive ability of LAR for mortality risk in the general population is still unclear. This study aimed to explore the association between LAR and cardiovascular as well as all-cause mortality among American adults.

METHODS

The present study was a secondary analysis of existing data from the National Health and Nutrition Examination Survey (NHANES). The final analysis included 12,440 participants from 2005 to 2014. Survival differences between groups were visualized using Kaplan‒Meier curves and the log-rank test. The association of LAR with cardiovascular and all-cause mortality was evaluated using multivariate Cox regression and restricted cubic spline analysis. Age, sex, coronary artery disease, diabetes, lipid-lowering medication use and hypertriglyceridemia were analyzed in subgroup analyses.

RESULTS

The median age in the study cohort was 46.0 years [interquartile range (IQR): 31.0-62.0], and 6,034 (48.5%) participants were male. During the follow-up period, there were 872 (7.0%) all-cause deaths and 150 (1.2%) cardiovascular deaths. Compared with individuals without cardiovascular events, those who experienced cardiovascular deaths had a lower LAR (1.13 vs. 1.25) (P < 0.001). The adjusted Cox regression model indicated that lower LAR was an independent risk factor for both cardiovascular [hazard ratio (HR) = 0.304, 95% confidence interval (CI): 0.114-0.812] and all-cause mortality (HR = 0.408, 95% CI: 0.270-0.617). Moreover, a significant age interaction was observed (P for interaction < 0.05), and there was a strong association between LAR and mortality among participants over 65 years of age. Further analysis showed an inverse association between LAR and both cardiovascular and all-cause mortality.

CONCLUSIONS

LAR can independently predict cardiovascular and all-cause mortality in the general population.

Sugar-Sweetened Beverage Consumption and Plasma Lipoprotein Cholesterol, Apolipoprotein, and Lipoprotein Particle Size Concentrations in US Adults

BACKGROUND

Prospective cohort studies have found a relation between sugar-sweetened beverage (SSB) consumption (sodas and fruit drinks) and dyslipidemia. There is limited evidence linking SSB consumption to emerging features of dyslipidemia, which can be characterized by variation in lipoprotein particle size, remnant-like particle (RLP), and apolipoprotein concentrations.

OBJECTIVES

To examine the association between SSB consumption and plasma lipoprotein cholesterol, apolipoprotein, and lipoprotein particle size concentrations among US adults.

METHODS

We examined participants from the Framingham Offspring Study (FOS; 1987-1995, n = 3047) and the Women's Health Study (1992, n = 26,218). Concentrations of plasma LDL cholesterol, apolipoprotein B (apoB), HDL cholesterol, apolipoprotein A1 (apoA1), triglyceride (TG), and non-HDL cholesterol, as well as total cholesterol:HDL cholesterol ratio and apoB:apoA1 ratio, were quantified in both cohorts; concentrations of apolipoprotein E, apolipoprotein C3, RLP-TG, and RLP cholesterol (RLP-C) were measured in the FOS only. Lipoprotein particle sizes were calculated from nuclear magnetic resonance signals for lipoprotein particle subclass concentrations (TG-rich lipoprotein particles [TRL-Ps]: very large, large, medium, small, and very small; LDL particles [LDL-Ps]: large, medium, and small; HDL particles [HDL-Ps]: large, medium, and small). SSB consumption was estimated from food frequency questionnaire data. We examined the associations between SSB consumption and all lipoprotein and apoprotein measures in linear regression models, adjusting for confounding factors such as lifestyle, diet, and traditional lipoprotein risk factors.

RESULTS

SSB consumption was positively associated with LDL cholesterol, apoB, TG, RLP-TG, RLP-C, and non-HDL cholesterol concentrations and total cholesterol:HDL cholesterol and apoB:apoA1 ratios; and negatively associated with HDL cholesterol and apoA1 concentrations (P-trend range: <0.0001 to 0.008). After adjustment for traditional lipoprotein risk factors, SSB consumers had smaller LDL-P and HDL-P sizes; lower concentrations of large LDL-Ps and medium HDL-Ps; and higher concentrations of small LDL-Ps, small HDL-Ps, and large TRL-Ps (P-trend range: <0.0001 to 0.001).

CONCLUSIONS

Higher SSB consumption was associated with multiple emerging features of dyslipidemia that have been linked to higher cardiometabolic risk in US adults.

Discordance of Apolipoprotein B, Non-HDL-Cholesterol, and LDL-Cholesterol Predicts Risk of Increased Arterial Stiffness and Elevated Carotid Intima-Media Thickness in Middle-Aged and Elderly Chinese Adults

Background

Apolipoprotein B (apoB) and non-high-density lipoprotein cholesterol (non-HDL-C) have been shown to predict cardiovascular disease (CVD) even in the case of low levels of low-density lipoprotein cholesterol (LDL-C). We aimed to investigate whether the discordance between LDL-C and apoB or non-HDL-C was associated with arterial stiffness and elevated carotid intima-media thickness (CIMT) in middle-aged and elderly adults.

Methods

A total of 5,279 Chinese adults free of CVD at baseline were included and followed with a mean follow-up of 4.3 years. Arterial stiffness was measured by brachial-ankle pulse wave velocity (baPWV) and pulse pressure (PP). The associations of apoB, non-HDL-C, and LDL-C with arterial stiffness or elevated CIMT were examined with logistic regression models using either continuous scales by restricted cubic splines or categories of concordant and discordant values defined by medians.

Results

High apoB but not LDL-C was associated with elevated baPWV or PP. High apoB, non-HDL-C, and LDL-C were all associated with elevated CIMT (p < 0.05). Individuals with low levels of LDL-C and discordantly high apoB or non-HDL-C compared to those with concordantly low apoB or non-HDL-C demonstrated higher risks of elevated baPWV [ORs (95% CI) of 1.40 (1.03–1.91) and 1.56 (1.12–2.18), respectively] and elevated PP [ORs (95% CI) of 1.61 (1.19–2.18) and 1.55 (1.12–2.15), respectively]. While, discordant high LDL-C with low apoB was associated with an increased risk of elevated CIMT (OR, 1.74; 95% CI, 1.13–2.69).

Conclusion

Discordance analysis revealed that elevated apoB or non-HDL-C was a better predictor of risk of arterial stiffness, whereas LDL-C for elevated CIMT.

The effects of high-intensity functional training on cardiometabolic risk factors and exercise enjoyment in men and women with metabolic syndrome: study protocol for a randomized, 12-week, dose-response trial

Background

Individuals with metabolic syndrome (MetS) are at a greater risk for developing atherosclerotic cardiovascular disease (ASCVD) than those without MetS, due to underlying endothelial dysfunction, dyslipidemia, and insulin resistance. Exercise is an effective primary and secondary prevention strategy for MetS; however, less than 25% of adults meet the minimum stated public recommendations. Barriers often identified are lack of enjoyment and lack of time. High-intensity functional training (HIFT), a time-efficient modality of exercise, has shown some potential to elicit positive affectivity and elicit increased fitness and improved glucose metabolism. However, the effects of HIFT on dyslipidemia and endothelial dysfunction have not been explored nor have the effects been explored in a population with MetS. Additionally, no studies have investigated the minimal dose of HIFT per week to see clinically meaningful changes in cardiometabolic health. The purpose of this study is to (1) determine the dose-response effect of HIFT on blood lipids, insulin resistance, and endothelial function and (2) determine the dose-response effect of HIFT on body composition, fitness, and perceived enjoyment and intention to continue the exercise.

Methods/design

In this randomized, dose-response trial, participants will undergo a 12-week HIFT intervention of either 1 day/week, 2 days/week, or 3 days/week of supervised, progressive exercise. Outcomes assessed at baseline and post-intervention will be multiple cardiometabolic markers, and fitness. Additionally, the participant’s affective response will be measured after the intervention.

Discussion

The findings of this research will provide evidence on the minimal dose of HIFT per week to see clinically meaningful improvements in the risk factors of MetS, as well as whether this modality is likely to mitigate the barriers to exercise. If an effective dose of HIFT per week is determined and if this modality is perceived positively, it may provide exercise specialists and health care providers a tool to prevent and treat MetS.

Trial registration

ClinicalTrials.gov NCT05001126. August 11, 2021.

The lipid paradox in neuroprogressive disorders: Causes and consequences

Chronic systemic inflammation is associated with an increased risk of cardiovascular disease in an environment of low low-density lipoprotein (LDL) and low total cholesterol and with the pathophysiology of neuroprogressive disorders. The causes and consequences of this lipid paradox are explored. Circulating activated neutrophils can release inflammatory molecules such as myeloperoxidase and the pro-inflammatory cytokines interleukin-1 beta, interleukin-6 and tumour necrosis factor-alpha. Since activated neutrophils are associated with atherosclerosis and cardiovascular disease and with major depressive disorder, bipolar disorder and schizophrenia, it seems reasonable to hypothesise that the inflammatory molecules released by them may act as mediators of the link between systemic inflammation and the development of atherosclerosis in neuroprogressive disorders. This hypothesis is tested by considering the association at a molecular level of systemic inflammation with increased LDL oxidation; increased small dense LDL levels; increased lipoprotein (a) concentration; secretory phospholipase A₂ activation; cytosolic phospholipase A₂ activation; increased platelet activation; decreased apolipoprotein A1 levels and function; decreased paroxonase-1 activity; hyperhomocysteinaemia; and metabolic endotoxaemia. These molecular mechanisms suggest potential therapeutic targets.

Low-density lipoproteins cause atherosclerotic cardiovascular disease: pathophysiological, genetic, and therapeutic insights: a consensus statement from the European Atherosclerosis Society Consensus Panel

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Effects of lipoproteins on endothelial cells and macrophages function and its possible implications on fetal adverse outcomes associated to maternal hypercholesterolemia during pregnancy

Hypercholesterolemia is one of the main risk factors associated with atherosclerosis and cardiovascular disease, the leading cause of death worldwide. During pregnancy, maternal hypercholesterolemia develops, and it can occur in a physiological (MPH) or supraphysiological (MSPH) manner, where MSPH is associated with endothelial dysfunction and early atherosclerotic lesions in the fetoplacental vasculature. In the pathogenesis of atherosclerosis, endothelial activation and endothelial dysfunction, characterized by an imbalance in the bioavailability of nitric oxide, contribute to the early stages of this disease. Macrophages conversion to foam cells, cholesterol efflux from these cells and its differentiation into a pro- or anti-inflammatory phenotype are also important processes that contribute to atherosclerosis. In adults it has been reported that native and modified HDL and LDL play an important role in endothelial and macrophage function. In this review it is proposed that fetal lipoproteins could be also relevant factors involved in the detrimental vascular effects described in MSPH. Changes in the composition and function of neonatal lipoproteins compared to adults has been reported and, although in MSPH pregnancies the fetal lipid profile does not differ from MPH, differences in the lipidomic profiles of umbilical venous blood have been reported, which could have implications in the vascular function. In this review we summarize the available information regarding the effects of lipoproteins on endothelial and macrophage function, emphasizing its possible implications on fetal adverse outcomes associated to maternal hypercholesterolemia during pregnancy.

Effect of PCSK9 inhibitor on lipoprotein particles in patients with acute coronary syndromes

Background

To assess the effects of proprotein convertase subtilisin/kexin type 9 inhibitor (evolocumab) on lipoprotein particles subfractions with Nuclear Magnetic Resonance spectroscopy in patients with acute coronary syndromes.

Methods

A total of 99 consecutive patients with ACS were enrolled and assigned to either the experimental group (n = 54) or the control group (n = 45). The combination therapy of PCSK9 inhibitor (Repatha®, 140 mg, q2w) and moderate statin (Rosuvastatin, 10 mg, qn) was administered in the experimental group, with statin monotherapy (Rosuvastatin, 10 mg, qn) in the control group. The therapeutic effects on lipoprotein particle subfractions were assessed with NMR spectroscopy after 8 weeks treatment, and the achievement of LDL-C therapeutic target in both groups were analyzed.

Results

In the experimental group, after 8 weeks of evolocumab combination treatment, the concentrations of blood lipids (TC, LDL-C and its subfractions [LDL-1 to 6], VLDL-C and its subfractions [VLDL-1 to 5], IDL-C, and HDL-C), lipoprotein particles, and their subfractions [VLDL-P, IDL-P, LDL-P, and its subfractions [LDL-P1 to 6], apoB, and LP(a)] demonstrated therapeutic benefits with statistical significance (P < 0.05). The decrease in total LDL-P concentrations was mainly due to a decreased concentration of small-sized LDL particles (LDL-P 5 + 6), which was significantly more prominent than the decrease in medium-sized LDL-P (LDL-P3 + 4) and large-sized LDL-P (LDL-P1 + 2) (P < 0.001). According to lipid control target recommended by the latest China Cholesterol Education Program Expert Consensus in 2019, after 8 weeks treatment, 96.3% patients in the experimental group and 13.3% in the control group had achieved the LDL-C therapeutic target (P < 0.01).

Conclusions

Evolocumab combination treatment for 8 weeks significantly improves the plasma lipid profiles in ACS patients, and significantly decrease the concentration of lipoprotein particles which might contribute to the pathonesis of atherosclerosis.

The Association of Small Dense Low-Density Lipoprotein Cholesterol and Coronary Heart Disease in Subjects at High Cardiovascular Risk

AIM

The present study aims to investigate the association between serum small dense low-density lipoprotein (sdLDL) cholesterol level and the development of coronary heart disease (CHD) in subjects at high cardiovascular risk.

METHODS

A total of 3,080 participants without prior cardiovascular disease (CVD), aged ≥ 40 years, were followed up for a median of 8.3 years, which were divided into two groups, those with serum sdLDL cholesterol levels of ＜35 mg/dL or ≥ 35 mg/dL. Then, subjects were stratified by the status of diabetes, CVD-related comorbidities (defined as the presence of diabetes, chronic kidney disease, or peripheral artery disease), and the CVD risk assessment according to the Japan Atherosclerosis Society Guidelines. The hazard ratios (HRs) and 95% confidence intervals (CIs) were computed using a Cox proportional hazards model.

RESULTS

During the follow-up, 79 subjects developed CHD. The risk for incident CHD was higher in subjects with serum sdLDL cholesterol of ≥ 35 mg/dL than those with sdLDL cholesterol of ＜35 mg/dL (HR 2.09, 95%CI 1.26-3.45) after adjusting for traditional risk factors. In the subgroup analyses, the multivariable-adjusted HR for incident CHD increased significantly in those with serum sdLDL cholesterol of ≥ 35 mg/dL among subjects with diabetes (HR 2.76, 95%CI 1.09-7.01), subjects with CVD-related comorbidities (HR 2.60, 95%CI 1.21-5.58), and high-risk category defined as the presence of CVD-related comorbidities or a Suita score of ≥ 56 points (HR 1.93, 95%CI 1.02-3.65).

CONCLUSIONS

Elevated serum sdLDL cholesterol was associated with the development of CHD even in subjects at high cardiovascular risk.

Metabolomic signatures for visceral adiposity and dysglycaemia in Asian Chinese and Caucasian European adults: the cross-sectional TOFI_Asia study

BACKGROUND

Asian Chinese are more susceptible to deposition of visceral adipose tissue (VAT) and type 2 diabetes (T2D) development than European Caucasians when matched for gender, age and body mass index (BMI). Our aims were: (i) characterise the ethnicity-specific metabolomic signature of visceral adiposity measured by dual energy X-ray absorptiometry (DXA) and fasting plasma glucose (FPG), and (ii) identify individuals susceptible to worse metabolic health outcomes.

METHODS

Fasting plasma samples from normoglycaemic (n = 274) and prediabetic (n = 83) participants were analysed with liquid chromatography-mass spectrometry using untargeted metabolomics. Multiple linear regression adjusting for age, gender and BMI was performed to identify metabolites associated with FPG and VAT calculated as percentage of total body fat (%VAT_TBF) in each ethnic group. Metabolic risk groups in each ethnicity were stratified based on the joint metabolomic signature for FPG and %VAT_TBF and clinically characterised using partial least squares-discriminant analysis (PLS-DA) and t-tests.

RESULTS

FPG was correlated with 40 and 110 metabolites in Caucasians and Chinese respectively, with diglyceride DG(38:5) (adjusted β = 0.29, p = 3.00E-05) in Caucasians and triglyceride TG(54:4) (adjusted β = 0.28, p = 2.02E-07) in Chinese being the most significantly correlated metabolite based on the p-value. %VAT_TBF was correlated with 85 and 119 metabolites in Caucasians and Chinese respectively, with TG(56:2) (adjusted β = 0.3, p = 8.25E-09) in Caucasians and TG(58:3) (adjusted β = 0.25, p = 2.34E-08) in Chinese being the most significantly correlated. 24 metabolites associated with FPG were common to both ethnicities including glycerolipid species. 67 metabolites associated with %VAT_TBF were common to both ethnicities including positive correlations with dihydroceramide, sphingomyelin, glycerolipid, phosphatidylcholine, phosphatidylethnolamine, and inverse correlations with ether-linked phosphatidylcholine. Participant re-stratification found greater total and central adiposity, worse clinical lipid profiles, higher serum glucoregulatory peptides and liver enzymes in normal fasting glucose (NFG) individuals with a prediabetic metabolomic profile than NFG individuals with a normoglycaemic metabolomic profile in both ethnicities.

CONCLUSIONS

Untargeted metabolomics identified common and disparate metabolites associated with FPG and %VAT_TBF, with an ethnic-dimorphic signature for these metabolic traits. These signatures could improve risk stratification and identify NFG individuals with an adverse cardiometabolic and T2D risk profile.

Neutrophils as a Novel Target of Modified Low-Density Lipoproteins and an Accelerator of Cardiovascular Diseases

Neutrophil extracellular traps (NETs) significantly contribute to various pathophysiological conditions, including cardiovascular diseases. NET formation in the vasculature exhibits inflammatory and thrombogenic activities on the endothelium. NETs are induced by various stimulants such as exogenous damage-associated molecular patterns (DAMPs). Oxidatively modified low-density lipoprotein (oxLDL) has been physiologically defined as a subpopulation of LDL that comprises various oxidative modifications in the protein components and oxidized lipids, which could act as DAMPs. oxLDL has been recognized as a crucial initiator and accelerator of atherosclerosis through foam cell formation by macrophages; however, recent studies have demonstrated that oxLDL stimulates neutrophils to induce NET formation and enhance NET-mediated inflammatory responses in vascular endothelial cells, thereby suggesting that oxLDL may be involved in cardiovascular diseases through neutrophil activation. As NETs comprise myeloperoxidase and proteases, they have the potential to mediate oxidative modification of LDL. This review summarizes recent updates on the analysis of NETs, their implications for cardiovascular diseases, and prospects for a possible link between NET formation and oxidative modification of lipoproteins.

Toward reliable low-density lipoprotein ultrastructure prediction in clinical conditions: A small-angle X-ray scattering study on individuals with normal and high triglyceride serum levels

Atherosclerosis is the main killer in the west and therefore a major health challenge today. Total serum cholesterol and lipoprotein concentrations, used as clinical markers, fail to predict the majority of cases, especially between the risk scale extremes, due to the high complexity in lipoprotein structure and composition. In particular, low-density lipoprotein (LDL) plays a key role in atherosclerosis development, with LDL size being a parameter considered for determining the risk for cardiovascular diseases. Determining LDL size and structural parameters is challenging to address experimentally under physiological-like conditions. This article describes the biochemistry and ultrastructure of normolipidemic and hypertriglyceridemic LDL fractions and subfractions using small-angle X-ray scattering. Our results conclude that LDL particles of hypertriglyceridemic compared to healthy individuals 1) have lower LDL core melting temperature, 2) have lower cholesteryl ester ordering in their core, 3) are smaller, rounder and more spherical below melting temperature, and 4) their protein-containing shell is thinner above melting temperature.

Endothelial function improvement in patients with familial hypercholesterolemia receiving PCSK-9 inhibitors on top of maximally tolerated lipid lowering therapy

BACKGROUND

Treatment with protein convertase subtilisin kexin type 9 inhibitors (PCSK-9i) reduced cholesterol levels and cardiovascular events in patients with hypercholesterolemia. We assessed changes in lipid profile, oxidation markers and endothelial function in patients with familial hypercholesterolemia (FH) after a 12-week treatment with a PCSK-9i.

METHODS

Patients with FH starting a treatment with PCSK-9i were included. Total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), lipoprotein(a) (Lp(a)), small dense LDL (assessed by LDL score), 11-dehydro-thromboxane (11-TXB2), 8-isoprostaglandin-2alpha (8-iso-PGF2α), flow-mediated dilation (FMD) and reactive hyperaemia index (RHI) were evaluated before starting PCSK-9i treatment and after a 12-week treatment.

RESULTS

Twenty-five subjects were enrolled (52% males, mean age 51.5 years). At the 12-week assessment, we observed a 38% median reduction in TC, 52% in LDL-C, 7% in Lp(a) and 46% in LDL score. In parallel, 11-TXB2 and 8-iso-PGF2α showed a reduction of 18% and 17%, respectively. FMD changed from 4.78% ± 2.27 at baseline to 10.6% ± 5.89 at 12 weeks (p < 0.001), with RHI changing from 2.37 ± 1.23 to 3.76 ± 1.36 (p < 0.001). A multivariate analysis showed that, after adjusting for potential confounders, change in LDL score was an independent predictor of changes in FMD (β = -0.846, p = 0.015) and in 8-iso-PGF2α (β = 0.778, p = 0.012).

CONCLUSIONS

Small dense LDL reduction (assessed by LDL score) is related to changes in oxidation markers and endothelial function in patients with FH treated with PCSK-9i.

Changes in carotid stiffness in patients with familial hypercholesterolemia treated with Evolocumab®: A prospective cohort study

BACKGROUND AND AIM

Protein convertase subtilisin kexin type 9 (PCSK-9) inhibitors demonstrated efficacy in cholesterol reduction and in the prevention of cardiovascular events. We evaluated changes in lipid profile and carotid stiffness in patients with familial hypercholesterolemia during 12 weeks of treatment with a PCSK-9 inhibitor, Evolocumab®.

METHODS AND RESULTS

Patients with familial hypercholesterolemia starting a treatment with Evolocumab® were included. Total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), small dense LDL (assessed by LDL score) and carotid stiffness were evaluated before starting treatment with Evolocumab® and during 12 weeks of treatment. Twenty-five subjects were enrolled (52% males, mean age 51.5 years). TC and LDL-C were reduced of 38% and 52%, respectively during treatment, with LDL score reduced of 46.1%. In parallel, carotid stiffness changed from 8.8 (IQR: 7.0-10.4) m/sec to 6.6 (IQR: 5.4-7.5) m/sec, corresponding to a median change of 21.4% (p < 0.001), with a significant increase in carotid distensibility (from 12.1, IQR: 8.73-19.3 kPA^-1 × 10^-3 at T₀ to 21.8, IQR: 16.6-31.8 kPA^-1 × 10^-3 at T12_w) corresponding to a median change of 62.8% (p < 0.001). A multivariate analysis showed that changes in LDL score were independently associated with changes in carotid stiffness (β = 0.429, p = 0.041).

CONCLUSION

Small dense LDL reduction, as assessed by LDL score, is associated with changes in carotid stiffness in patients with familial hypercholesterolemia treated with Evolocumab®.

Metabolic Inflammation-A Role for Hepatic Inflammatory Pathways as Drivers of Comorbidities in Nonalcoholic Fatty Liver Disease?

Nonalcoholic fatty liver disease (NAFLD) is a global and growing health concern. Emerging evidence points toward metabolic inflammation as a key process in the fatty liver that contributes to multiorgan morbidity. Key extrahepatic comorbidities that are influenced by NAFLD are type 2 diabetes, cardiovascular disease, and impaired neurocognitive function. Importantly, the presence of nonalcoholic steatohepatitis and advanced hepatic fibrosis increase the risk for systemic comorbidity in NAFLD. Although the precise nature of the crosstalk between the liver and other organs has not yet been fully elucidated, there is emerging evidence that metabolic inflammation-in part, emanating from the fatty liver-is the engine that drives cellular dysfunction, cell death, and deleterious remodeling within various body tissues. This review describes several inflammatory pathways and mediators that have been implicated as links between NAFLD and type 2 diabetes, cardiovascular disease, and neurocognitive decline.

Mediterranean Diet Nutrients to Turn the Tide against Insulin Resistance and Related Diseases

Insulin resistance (IR), defined as an attenuated biological response to circulating insulin, is a fundamental defect in obesity and type 2 diabetes (T2D), and is also linked to a wide spectrum of pathological conditions, such as non-alcoholic fatty liver disease (NAFLD), cognitive impairment, endothelial dysfunction, chronic kidney disease (CKD), polycystic ovary syndrome (PCOS), and some endocrine tumors, including breast cancer. In obesity, the unbalanced production of pro- and anti-inflammatory adipocytokines can lead to the development of IR and its related metabolic complications, which are potentially reversible through weight-loss programs. The Mediterranean diet (MedDiet), characterized by high consumption of extra-virgin olive oil (EVOO), nuts, red wine, vegetables and other polyphenol-rich elements, has proved to be associated with greater improvement of IR in obese individuals, when compared to other nutritional interventions. Also, recent studies in either experimental animal models or in humans, have shown encouraging results for insulin-sensitizing nutritional supplements derived from MedDiet food sources in the modulation of pathognomonic traits of certain IR-related conditions, including polyunsaturated fatty acids from olive oil and seeds, anthocyanins from purple vegetables and fruits, resveratrol from grapes, and the EVOO-derived, oleacein. Although the pharmacological properties and clinical uses of these functional nutrients are still under investigation, the molecular mechanism(s) underlying the metabolic benefits appear to be compound-specific and, in some cases, point to a role in gene expression through an involvement of the nuclear high-mobility group A1 (HMGA1) protein.

Eicosapentaenoic acid (EPA) has optimal chain length and degree of unsaturation to inhibit oxidation of small dense LDL and membrane cholesterol domains as compared to related fatty acids in vitro

BACKGROUND

Oxidation of small dense low-density lipoprotein (sdLDL) and membranes is causally related to atherosclerosis. The omega-3 fatty acid (FA) eicosapentaenoic acid (EPA, 20:5, ω-3) significantly reduced oxidized LDL in patients with hypertriglyceridemia by unknown mechanisms. We compared EPA effects to related FAs of varying chain length and unsaturation on oxidation of sdLDL and model membranes, and on cholesterol crystal domains. We compared EPA to the FAs: stearic (SA, 18:0), oleic (OA, 18:1, ω-9), linoleic (LA, 18:2, ω-6), alpha-linolenic (ALA, 18:3, ω-3), eicosanoic (EA, 20:0), eicosatrienoic (ETE, 20:3, ω-3), arachidonic (AA, 20:4, ω-6), docosapentaenoic (DPA, 22:5, ω-3), and docosahexaenoic (DHA, 22:6, ω-3).

METHODS

Human sdLDL or model membranes of cholesterol and 1,2-Dilinoleoyl-sn-glycero-3-phosphocholine [18:2(cis)PC or DLPC] were preincubated with FAs followed by copper-induced oxidation. Malondialdehyde (MDA) or lipid hydroperoxides (LOOH) levels measured oxidation; small-angle X-ray diffraction assessed cholesterol domain formation.

RESULTS

After 40 min, EPA reduced MDA levels 70% compared to vehicle (p < 0.001). Lesser inhibition was observed with DHA, DPA, ETE, and ALA (33%, 34%, 32%, and 16%, respectively; all p < 0.001 versus vehicle). Similar relative FA effects were observed in model membranes where EPA more substantially inhibited cholesterol crystal domain formation.

CONCLUSION

We observed relationships between hydrocarbon length and unsaturation with antioxidant activity and membrane cholesterol domain formation. EPA had the most favorable molecular structure, likely contributing to membrane stability, improved lipoprotein clearance, and reduced inflammation.

GENERAL SIGNIFICANCE

Insight is provided into FA hydrocarbon length and unsaturation relationships with antioxidant activity in lipoproteins and membranes, and cholesterol crystal domains formation.

Small Dense Low-Density Lipoprotein Cholesterol and the Risk of Coronary Heart Disease in a Japanese Community

Aims: This study aims to investigate the association between serum small dense low-density lipoprotein (sdLDL) cholesterol level and the development of coronary heart disease (CHD) in a Japanese community.

Methods: A total of 3,080 participants without prior cardiovascular disease, aged 40 years or older, were followed up for 8 years. The participants were divided into the quartiles of serum sdLDL cholesterol levels. The risk estimates were computed using a Cox proportional hazards model.

Results: During the follow-up period, 79 subjects developed CHD. Subjects in the highest quartile had a 5.41-fold (95% confidence interval, 2.12–13.82) higher risk of CHD than those in the lowest quartile after controlling for confounders. In the analysis classifying the participants into four groups according to the levels of serum sdLDL cholesterol and serum low-density lipoprotein (LDL) cholesterol levels, the risk of CHD almost doubled in subjects with sdLDL cholesterol of ≥ 32.9 mg/dL (median), regardless of serum LDL cholesterol levels, as compared with subjects with serum sdLDL cholesterol of < 32.9 mg/dL and serum LDL cholesterol of < 120.1 mg/dL (median). When serum sdLDL cholesterol levels were incorporated into a model with known cardiovascular risk factors, c-statistics was significantly increased (from 0.77 to 0.79; p = 0.02), and the net reclassification improvement was also significant (0.40; p < 0.001).

Conclusions: The present findings suggest that the serum sdLDL cholesterol level is a relevant biomarker for the future development of CHD that offers benefit beyond the serum LDL cholesterol level and a possible therapeutic target to reduce the burden of CHD in a Japanese community.

Phospholipid packing defects and oxysterols in atherosclerosis: Dietary prevention and the French paradox

The research literature on atherosclerosis includes findings investigating the atherosclerotic effect of oxysterols, which are the oxidation products of cholesterol; and the literature on oxysterols refers to mechanisms by which oxysterols cause phospholipid packing defects in cell membranes. This review synthesizes these two bodies of research findings to describe how oxysterols cause phospholipid packing defects within the membranes of vascular endothelial cells, potentially increasing cell permeability of low-density lipoprotein cholesterol which may lead to atheroma formation. Exogenous sources of oxysterols are provided by dietary intake of animal-based foods that contain cholesterol oxidation products. This review proposes an explanation for the anti-atherosclerotic effect of plant-based dietary patterns, which is attributed to restriction or avoidance of dietary oxysterol intake from animal-based foods. Furthermore, raw-milk cheeses play an important role in the traditional French diet-low oxysterol content in these unheated foods may contribute to the French paradox, in which reduced coronary heart disease is associated with a diet high in saturated fat and cholesterol.

ApoB, small-dense LDL-C, Lp(a), LpPLA2 activity, and cognitive change

OBJECTIVE

To examine the association of specific lipoproteins/inflammatory enzyme with cognitive change.

METHODS

We examined the association of apolipoprotein B (ApoB), small-dense low-density lipoprotein cholesterol (sdLDL-C), lipoprotein (a) (Lp[a]), and lipoprotein-associated phospholipase A2 (LpPLA2) activity with 15-year change in Delayed Word Recall Test, Digit Symbol Substitution Test (DSST), Word Fluency Test (WFT), and overall summary score in 9,350 participants in the Atherosclerosis Risk in Communities study. We assessed interaction by race, sex, education, APOE ε4 status, and statin use. We also addressed questions of informative missingness, the role of stroke, and the influence of fasting status.

RESULTS

The mean (SD) age was 63.4 (5.7) years; 56.4% were women and 17.4% were black. We observed faster cognitive decline on DSST and global z scores with every 10-mg/dL higher sdLDL-C level (Δ DSST z score, -0.010; 95% confidence interval [CI] -0.017, -0.002 and Δ global z score, -0.011; -0.021, -0.001) and the highest vs the lowest ApoB quintiles (Δ DSST z score, -0.092; -0.0164, -0.019 and Δ global z score, -0.101; -0.200, -0.002). Association for the ApoB quintiles with Δ global z score (-0.10) was comparable with that of having 1 APOE ε4 allele (-0.11). Higher Lp(a) was associated with slower decline in DSST, WFT, and global z scores. LpPLA2 activity was not associated with cognitive change. Results were similar in sensitivity analyses. The associations of sdLDL-C or Lp(a) on cognitive change were more pronounced in statin users.

CONCLUSIONS

Optimal control of atherogenic lipoproteins such as ApoB and sdLDL-C in midlife for cardiovascular health may also benefit late-life cognitive health.

Impact of the triglyceride level on coronary plaque components in female patients with coronary artery disease treated with statins

Several studies have reported that elevated triglyceride (TG) levels may be more strongly associated with an increased risk of coronary artery disease (CAD) in females than in males. We examined gender differences in the relationship between TG levels and coronary atherosclerosis using integrated backscatter intravascular ultrasound (IB IVUS) in CAD patients treated with statins. Three hundred seventy-eight CAD patients (105 females and 273 males) who underwent percutaneous coronary intervention using IB IVUS, and who were already receiving statin treatment, were included. Gray-scale and IB IVUS examinations were performed for the non-culprit segment of a coronary artery and fasting serum TG concentrations were measured. We found that TG levels were significantly correlated with increased lipid (r = 0.40, p < 0.001) and decreased fibrous (r = - 0.37, p < 0.001) plaque components in females, but not in males. Low-density lipoprotein cholesterol and high-density lipoprotein cholesterol levels were not related to either the gray-scale or IB IVUS parameters in both genders. After adjustment for conventional coronary risk factors by a multivariate stepwise regression analysis, higher TG levels in females were independently associated with increased lipid (β = 0.31, p< 0.001) contents in coronary plaques. In conclusion, among CAD patients treated with statins, TG levels were associated with lipid-rich coronary plaques in females, but not in males. TG levels may be more important indicators of residual risk after statin treatment in females than in males.

Eicosapentaenoic Acid Inhibits Oxidation of ApoB-containing Lipoprotein Particles of Different Size In Vitro When Administered Alone or in Combination With Atorvastatin Active Metabolite Compared With Other Triglyceride-lowering Agents

Eicosapentaenoic acid (EPA) is a triglyceride-lowering agent that reduces circulating levels of the apolipoprotein B (apoB)-containing lipoprotein particles small dense low-density lipoprotein (sdLDL), very–low-density lipoprotein (VLDL), and oxidized low-density lipoprotein (LDL). These benefits may result from the direct antioxidant effects of EPA. To investigate this potential mechanism, these particles were isolated from human plasma, preincubated with EPA in the absence or presence of atorvastatin (active) metabolite, and subjected to copper-initiated oxidation. Lipid oxidation was measured as a function of thiobarbituric acid reactive substances formation. EPA inhibited sdLDL (IC₅₀ ∼2.0 μM) and LDL oxidation (IC₅₀ ∼2.5 μM) in a dose-dependent manner. Greater antioxidant potency was observed for EPA in VLDL. EPA inhibition was enhanced when combined with atorvastatin metabolite at low equimolar concentrations. Other triglyceride-lowering agents (fenofibrate, niacin, and gemfibrozil) and vitamin E did not significantly affect sdLDL, LDL, or VLDL oxidation compared with vehicle-treated controls. Docosahexaenoic acid was also found to inhibit oxidation in these particles but over a shorter time period than EPA. These data support recent clinical findings and suggest that EPA has direct antioxidant benefits in various apoB-containing subfractions that are more pronounced than those of other triglyceride-lowering agents and docosahexaenoic acid.

Association of low-density lipoprotein pattern with mortality after myocardial infarction: Insights from the TRIUMPH study

BACKGROUND

Studies of incident coronary heart disease risk within low-density lipoprotein (LDL) subclass (small, dense vs large, buoyant) have shown mixed results. No prospective cohort study has examined the association of small, dense, or large, buoyant LDL with mortality after myocardial infarction (MI).

OBJECTIVE

The objective of the study was to examine association of LDL pattern after MI and death.

METHODS

In 2476 patients hospitalized for MI, LDL pattern (A [large, buoyant], A/B [mixed], and B [small, dense]) was established by ultracentrifugation using Vertical Auto Profile. Using time-to-event analysis, we examined the association with 5-year mortality within LDL patterns, after adjusting for important patient and treatment characteristics. We additionally adjusted for LDL cholesterol (LDL-C) and triglyceride levels and used directly measured LDL-C and non-high-density lipoprotein cholesterol as exposures.

RESULTS

Patterns A, A/B, and B were present in 39%, 28%, and 33% of patients, respectively, with incident rates (per 1000 patient-years) of 50, 34, and 24 for all-cause and 24, 19, and 10 for CV mortality. The hazard ratios (95% confidence interval) with LDL patterns A/B and B compared with pattern A were 0.77 (0.61, 0.99) and 0.67 (0.51, 0.88) for all-cause, 0.94 (0.67, 1.33) and 0.69 (0.46, 1.03) for cardiovascular, and 0.64 (0.45, 0.91) and 0.65 (0.45, 0.93) for noncardiovascular mortalities, respectively. Results were similar when further adjusted for LDL-C and triglycerides, or with LDL-C and non-high-density lipoprotein cholesterol as exposures.

CONCLUSION

Compared with LDL pattern A, pattern B was significantly associated with reduced all-cause and non-CV mortalities with a trend for lower CV mortality after MI, independent of LDL-C and triglycerides.

Apolipoprotein B is associated with carotid atherosclerosis progression independent of individual cholesterol measures in a 9-year prospective study of Multi-Ethnic Study of Atherosclerosis participants

BACKGROUND

High blood cholesterol contributes to atherosclerosis, yet reliance on the lipid panel alone may mischaracterize individuals with elevated lipoprotein particle numbers.

OBJECTIVE

The aim of the article was to determine whether elevated lipoprotein or apolipoprotein measures are associated with carotid atherosclerosis and plaque progression independent of cardiovascular (CV) risk factors including standard lipids in a subcohort of 2228 Multi-Ethnic Study of Atherosclerosis participants.

METHODS

Ultrasonography assessed carotid artery plaque and common carotid intima-media thickness (cIMT) at baseline and after a median period of 9.4 years. Nuclear magnetic resonance spectroscopy estimated lipoprotein particle concentrations. Apolipoprotein B (ApoB) and apolipoprotein A-I were measured using an automated immunoassay. Regression analysis determined associations of apolipoprotein and lipoprotein measurements with cIMT and relative risk regression determined associations with carotid plaque progression.

RESULTS

After adjustment for typical CV risk factors, individuals in top quartiles of ApoB, ApoB/apolipoprotein A-I, low-density lipoprotein particles (LDL-P), small LDL-P, and total LDL-P/high-density lipoprotein (HDL) particles showed similar risks of carotid plaque and cIMT progression as LDL-C, non-HDL cholesterol (HDL-C), total cholesterol (TC), and TC/HDL-C. A significant association with plaque progression remained in the top ApoB quartile after further adjustment for LDL-C (P = .02) or TC + HDL-C (P = .04), but was nonsignificant when adjusted for all lipid covariates (P = .086). Those in the top quartile of small LDL-P concentrations showed greater cIMT progression than those in the referent after adjustment for LDL-C, but this was nonsignificant after adjustment for TC + HDL-C.

CONCLUSION

When coupled with evidence that apolipoprotein testing identifies lipid-lipoprotein discordance, these findings suggest that ApoB and small LDL-P provide atherosclerosis risk information that is not revealed by typical CV risk factors.

Impact of Egg Consumption on Cardiovascular Risk Factors in Individuals with Type 2 Diabetes and at Risk for Developing Diabetes: A Systematic Review of Randomized Nutritional Intervention Studies

Observational studies have reported inconclusive results regarding the relationship between egg consumption (and dietary cholesterol) and the risk for cardiovascular diseases (CVDs) in individuals with type 2 diabetes, which has led to inconsistent recommendations to patients. We reviewed the evidence of egg consumption on major CVD risk factors in individuals with or at risk for type 2 diabetes (prediabetes, insulin resistance or metabolic syndrome). We performed a systematic search in the databases PubMed, MEDLINE, EMBASE and Web of Science in January 2016. Inclusion criteria included randomized controlled trials in which the amount of egg consumed was manipulated and compared to a control group that received no-egg or low-egg diets (<2 eggs/week). We found 10 articles (6 original trials) that met our inclusion criteria. The majority of studies found that egg consumption did not affect major CVD risk factors. Consumption of 6 to 12 eggs per week had no impact on plasma concentrations of total cholesterol, low-density lipoprotein-cholesterol, triglycerides, fasting glucose, insulin or C-reactive protein in all studies that reported these outcomes in comparison with control groups. An increase in high-density lipoprotein-cholesterol with egg consumption was observed in 4 of 6 studies. Results from randomized controlled trials suggest that consumption of 6 to 12 eggs per week, in the context of a diet that is consistent with guidelines on cardiovascular health promotion, has no adverse effect on major CVD risk factors in individuals at risk for developing diabetes or with type 2 diabetes. However, heterogeneities in study design, population included and interventions prevent firm conclusions from being drawn.

Dyslipidemia Part 1--Review of Lipid Metabolism and Vascular Cell Physiology

Dyslipidemia, more specifically, high-serum low-density lipoproteins and low-serum high-density lipoproteins, are known risk factors for cardiovascular disease. The current clinical treatment of dyslipidemia represents the outcome of a large body of fundamental basic science research on lipids, lipid metabolism, and the effects of different lipids on cellular components of the artery, inflammatory cells, and platelets. In general, lower density lipids activate intracellular pathways to increase local and systemic inflammation, monocyte adhesion, endothelial cell dysfunction and apoptosis, and smooth muscle cell proliferation, resulting in foam cell formation and genesis of atherosclerotic plaque. In contrast, higher density lipids prevent or attenuate atherosclerosis. This article is part 1 of a 2-part review, with part 1 focusing on lipid metabolism and the downstream effects of lipids on the development of atherosclerosis, and part 2 on the clinical treatment of dyslipidemia and the role of these drugs for patients with arterial disease exclusive of the coronary arteries.

Do HDL and LDL subfractions play a role in atherosclerosis in end-stage renal disease (ESRD) patients?

BACKGROUND

Significantly increased cardiovascular mortality in patients with chronic kidney (CKD) disease cannot be explained by traditional risk factors. Recent studies revealed that the quality of HDL and LDL cholesterol may be more important than their serum levels. The aim of this study was to assess which LDL and HDL subfractions were more abundant in end-stage renal disease (ESRD) patients and to analyse whether subfraction distribution could be associated with accelerated atherosclerotic processes.

METHODS

This study included 50 ESRD patients undergoing dialysis and 20 healthy volunteers. LDL and HDL subfractions were analysed in serum with the use of Lipoprint system. All patients had intima-media thickness (IMT) measured.

RESULTS

Statistically significant differences in subfractions between control and study group were observed in case of: HDL1 (p < 0.0001), HDL2 (p = 0.009), HDL3 (p < 0.0001), HDL4 (p = 0.003), HDL5 (p = 0.01), HDL7 (p < 0.0001), HDL8 (p < 0.0001), HDL9 (p < 0.0001), HDL10 (p < 0.0001), large HDL (p < 0.0001), HDL Small (p < 0.0001) as well as IDL-B (p = 0.014), IDLA (p = 0.011), LDL2 (p = 0.007). Significant differences were also observed in HDL and LDL subfraction distribution between haemodialysis patients with normal and increased IMT: HDL6 (p = 0.020), HDL Large (HDL1-3) (p = 0.017), HDL Intermediate (HDL4-7) (p = 0.017).

CONCLUSIONS

This study revealed that ESRD influenced HDL subfractions. In HD patients, large HDL subfractions are more abundant while small HDL fraction is more frequent in healthy persons. It failed to show the influence of end-stage disease on LDL subfraction levels. Shift in HDL subfractions might be responsible for the increased risk of atherosclerosis in CKD patients.

Additive Antiatherogenic Effects of CETP rs708272 on Serum LDL Subfraction Levels in Patients with CHD Under Statin Therapy

Recently, subfraction analysis of serum low density lipoprotein (LDL) is considered to be a better predictor of the risk of coronary heart disease (CHD) compared to the other lipid parameters. The aim of this study was to examine the effects of the HDL-associated Taq1B (rs708272) SNP of cholesterol ester transfer protein (CETP) gene on serum LDL subfractions in patients with CHD. Serum lipid levels were measured enzymatically and LDL subfraction analysis was carried out by the Lipoprint System (Quantimetrix, CA, USA). The CETP rs708272 SNP was studied in 66 healthy controls and 79 patients with CHD receiving statin therapy by the PCR-RFLP technique. The CHD patients had elevated antiatherogenic LDL-1 subfraction (p = 0.042), decreased atherogenic IDL-C subfraction (p = 0.023), and total IDL (p = 0.030) levels compared to the healthy controls. The CETP rs708272 Taq1B minor B2 allele was associated with increased levels of antiatherogenic LDL-1 (B2: 0.40 ± 0.20 vs. B1B1: 0.25 ± 0.08, p = 0.004) and large-LDL (LDL 1-2) subfractions in the CHD group (B2 allele: 0.68 ± 0.41 vs. B1B1: 0.42 ± 0.20; p < 0.05), while it was associated with reduced levels of the large-LDL subfraction in healthy subjects (B2 allele: 0.29 ± 0.14 vs. B1B1: 0.54 ± 0.24; p = 0.017). However, there was no statistically significant association between the CETP rs708272 SNP and small dense LDL subfraction (LDL 3-7) and lipoprotein levels (p > 0.05). Our findings have indicated that the CETP rs708272 SNP together with statin therapy may show a favorable effect on antiatherogenic LDL-1 and large-LDL subfractions in CHD patients with an atherogenic effect on large-LDL subfraction in healthy subjects. Based on these results, it can be concluded that the effects of the CETP variation on LDL subfraction could change in cardiometabolic events such as CHD and statin therapy.

Krill oil reduces plasma triacylglycerol level and improves related lipoprotein particle concentration, fatty acid composition and redox status in healthy young adults - a pilot study

Background

Lipid abnormalities, enhanced inflammation and oxidative stress seem to represent a vicious circle in atherogenesis, and therapeutic options directed against these processes seems like a reasonable approach in the management of atherosclerotic disorders. Krill oil (RIMFROST Sublime®) is a phospholipid-rich oil with eicosapentaenoic acid (EPA): docosahexaenoic acid (DHA) ratio of 1.8:1. In this pilot study we determined if krill oil could favourable affect plasma lipid parameters and parameters involved in the initiation and progression of atherosclerosis.

Methods

The study was conducted as a 28 days intervention study examining effect-parameters of dietary supplementation with krill oil (832.5 mg EPA and DHA per day). 17 healthy volunteers in the age group 18–36 (mean age 23 ± 4 years) participated. Plasma lipids, lipoprotein particle sizes, fatty acid composition in plasma and red blood cells (RBCs), plasma cytokines, antioxidant capacity, acylcarntines, carnitine, choline, betaine, and trimethylamine-N-oxide (TMAO) were measured before and after supplementation.

Results

Plasma triacylglycerol (TAG) and large very-low density lipoprotein (VLDL) & chylomicron particle concentrations decreased after 28 days of krill oil intake. A significant reduction in the TAG/HDL cholesterol resulted. Krill oil supplementation decreased n-6/n-3 polyunsaturated fatty acids (PUFA) ratio both in plasma and RBCs. This was due to increased EPA, DHA and docosapentaenoic acid (DPA) and reduced amount of arachidonic acid (AA). The increase of n-3 fatty acids and wt % of EPA and DHA in RBC was of smaller magnitude than found in plasma. Krill oil intake increased the antioxidant capacity, double bond index (DBI) and the fatty acid anti-inflammatory index. The plasma atherogenicity index remained constant whereas the thrombogenicity index decreased. Plasma choline, betaine and the carnitine precursor, γ-butyrobetaine were increased after krill oil supplementation whereas the TMAO and carnitine concentrations remained unchanged.

Conclusion

Krill oil consumption is considered health beneficial as it decreases cardiovascular disease risk parameters through effects on plasma TAGs, lipoprotein particles, fatty acid profile, redox status and possible inflammation. Noteworthy, no adverse effects on plasma levels of TMAO and carnitine were found.

Cholesterol Metabolism in CKD

Patients with chronic kidney disease (CKD) have a substantial risk of developing coronary artery disease. Traditional cardiovascular disease (CVD) risk factors such as hypertension and hyperlipidemia do not adequately explain the high prevalence of CVD in CKD. Both CVD and CKD are inflammatory states and inflammation adversely affects lipid balance. Dyslipidemia in CKD is characterized by elevated triglyceride levels and high-density lipoprotein levels that are both decreased and dysfunctional. This dysfunctional high-density lipoprotein becomes proinflammatory and loses its atheroprotective ability to promote cholesterol efflux from cells, including lipid-overloaded macrophages in the arterial wall. Elevated triglyceride levels result primarily from defective clearance. The weak association between low-density lipoprotein cholesterol level and coronary risk in CKD has led to controversy over the usefulness of statin therapy. This review examines disrupted cholesterol transport in CKD, presenting both clinical and preclinical evidence of the effect of the uremic environment on vascular lipid accumulation. Preventative and treatment strategies are explored.

The apolipoprotein B/apolipoprotein A-I ratio as a potential marker of plasma atherogenicity

Background. The apolipoprotein (apo) B/apoA-I ratio represents the balance between apoB-rich atherogenic particles and apoA-I-rich antiatherogenic particles, and this ratio is considered to be a marker of cardiovascular risk. Although many studies have demonstrated the importance of the apoB/apoA-I ratio in predicting the presence or absence of cardiovascular disease, less is known about apoB/apoA-I ratio as a marker of plasma atherogenicity. Methods. A total of 157 normolipidemic men aged 20–59 years were included in the study. The plasma levels of total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), apoA-I, apoB, and apoE were determined after a 12 h fasting period. Results. The median of the apoB/apoA-I ratio in the studied normolipidemic subjects was 0.52, with values ranging from 0.19 to 2.60. The percentage of subjects with the apoB/apoA-I ratio exceeding 0.9 (the accepted risk value of cardiovascular disease) was 19.1%. The subjects with apoB/apoA-I>0.9 were characterized by higher TG levels and atherogenic index of plasma (AIP) and lower values of ratio of low-density lipoprotein cholesterol (LDL-C) to apoB (LDL-C/apoB) and apoE levels compared with men with apoB/apoA-I<0.9. Conclusion. Despite normolipidemia, the subjects with the unfavorable apoB/apoA-I ratio had more atherogenic lipid profile.

Relation of plasma PCSK9 levels to lipoprotein subfractions in patients with stable coronary artery disease

Background

Plasma PCSK9 levels was positively associated with low-density lipoprotein (LDL) cholesterol (LDL-C) and atherosclerosis, while PCSK9 may also be implicated in the metabolism of lipoprotein subfractions. The study was to examine the association of plasma PCSK9 with lipoprotein subfractions in patients with stable coronary artery disease (CAD).

Methods

A total of 281 consecutive, stable CAD patients who were not treated with lipid-lowering drugs were enrolled. The baseline clinical characteristics were collected, the plasma PCSK9 levels were determined using ELISA, and the LDL and high-density lipoprotein (HDL) subfractions were analyzed by Lipoprint System. The association of plasma PCSK9 levels with the lipoprotein subfractions was investigated.

Results

In the overall population, plasma PCSK9 levels were positively associated with the concentration of LDL-C, intermediate LDL-C, small LDL-C, and LDL score, while negatively correlated with mean LDL particle size. PCSK9 levels were positively associated with the concentration of HDL-C, intermediate HDL-C and small HDL-C. Multivariable regression analysis revealed that the plasma PCSK9 levels were significantly and independently associated with the concentration of intermediate LDL-C (β = 0.152, p = 0.013), small LDL-C (β = 0.179, p = 0.004), LDL score (β = 0.121, p = 0.043), and mean LDL particle size (β = -0.130, p = 0.035), while not HDL subfractions. Interestingly, when investigated in male and female patients separately, these relationships were only found in male but not in female, and the small HDL-C exhibited an association with PCSK9 levels in male patients (β = 0.149, p = 0.045).

Conclusions

PCSK9 levels were independently associated with the changes of lipoprotein subfractions, suggesting a potential interaction between PCSK9 and lipoprotein subfractions in CAD.

Small dense low density lipoprotein particles are associated with poor outcome after angioplasty in peripheral artery disease

Purpose

In patients suffering from symptomatic peripheral artery disease (PAD), percutaneous revascularization is the treatment of choice. However, restenosis may occur in 10 to 60% in the first year depending on a variety of factors. Small dense low density lipoprotein (sdLDL) particles are associated with an increased risk for cardiovascular events, but their role in the process of restenosis is not known. We conducted a prospective study to analyze the association of sdLDL particles with the outcome of balloon angioplasty in PAD. The composite primary endpoint was defined as improved walking distance and absence of restenosis.

Methods

Patients with angiographically documented PAD of the lower extremities who were scheduled for lower limb revascularization were consecutively recruited for the study. At baseline and at three month follow-up triglyceride, total cholesterol, LDL size and subclasses and HDL cholesterol and ankle-brachial index (ABI) were measured. Three months after the intervention duplex sonography was performed to detect restenosis.

Results

Sixty-four patients (53% male) with a mean age of 68.6±9.9 years were included. The proportion of small- dense LDL particles (class III and IV) was significantly lower (33.1±11.0% vs. 39.4±12.1%, p = 0.038) in patients who reached the primary end-point compared with those who did not. Patients with improved walking distance and without restenosis had a significantly higher LDL size at baseline (26.6±1.1 nm vs. 26.1±1.1 nm, p = 0.046) and at follow-up (26.7±1.1 nm vs. 26.2±0.9 nm, p = 0.044) than patients without improvement.

Conclusions

Small-dense LDL particles are associated with worse early outcome in patients undergoing percutaneous revascularization for symptomatic PAD.

A moderate-fat diet containing pistachios improves emerging markers of cardiometabolic syndrome in healthy adults with elevated LDL levels

A randomised, cross-over, controlled-feeding study was conducted to evaluate the cholesterol-lowering effects of diets containing pistachios as a strategy for increasing total fat (TF) levels v. a control (step I) lower-fat diet. Ex vivo techniques were used to evaluate the effects of pistachio consumption on lipoprotein subclasses and functionality in individuals (n 28) with elevated LDL levels ( ≥ 2·86 mmol/l). The following test diets (SFA approximately 8 % and cholesterol < 300 mg/d) were used: a control diet (25 % TF); a diet comprising one serving of pistachios per d (1PD; 30 % TF); a diet comprising two servings of pistachios per d (2PD; 34 % TF). A significant decrease in small and dense LDL (sdLDL) levels was observed following the 2PD dietary treatment v. the 1PD dietary treatment (P= 0·03) and following the 2PD dietary treatment v. the control treatment (P= 0·001). Furthermore, reductions in sdLDL levels were correlated with reductions in TAG levels (r 0·424, P= 0·025) following the 2PD dietary treatment v. the control treatment. In addition, inclusion of pistachios increased the levels of functional α-1 (P= 0·073) and α-2 (P= 0·056) HDL particles. However, ATP-binding cassette transporter A1-mediated serum cholesterol efflux capacity (P= 0·016) and global serum cholesterol efflux capacity (P= 0·076) were only improved following the 2PD dietary treatment v. the 1PD dietary treatment when baseline C-reactive protein status was low ( < 103μg/l). Moreover, a significant decrease in the TAG:HDL ratio was observed following the 2PD dietary treatment v. the control treatment (P= 0·036). There was a significant increase in β-sitosterol levels (P< 0·0001) with the inclusion of pistachios, confirming adherence to the study protocol. In conclusion, the inclusion of pistachios in a moderate-fat diet favourably affects the cardiometabolic profile in individuals with an increased risk of CVD.

Atorvastatin active metabolite inhibits oxidative modification of small dense low-density lipoprotein

We tested the hypothesis that atorvastatin active metabolite (ATM), on the basis of its distinct structural features and potent antioxidant activity, preferentially inhibits lipid oxidation in human small dense low-density lipoprotein (sdLDL) and other small lipid vesicles. LDL, sdLDL, and various subfractions were isolated from human plasma by sequential ultracentrifugation, treated with ATM, atorvastatin, pravastatin, rosuvastatin, or simvastatin and were subjected to copper-induced oxidation. Lipid oxidation was measured spectrophotometrically as a function of thiobarbituric acid reactive substances formation. Similar analyses were performed in reconstituted lipid vesicles enriched in polyunsaturated fatty acids and prepared at various sizes. ATM was found to inhibit sdLDL oxidation in a dose-dependent manner. The antioxidant effects of ATM in sdLDL were 1.5 and 4.7 times greater (P < 0.001) than those observed in large buoyant LDL and very low-density lipoprotein subfractions, respectively. ATM had similar dose- and size-dependent effects in reconstituted lipid vesicles. None of these effects were reproduced by atorvastatin (parent) or any of the other statins examined in this study. These data suggest that ATM interacts with sdLDL in a specific manner that also confers preferential resistance to oxidative stress. Such interactions may reduce sdLDL atherogenicity and improve clinical outcomes in patients with cardiovascular disease.

Effect of Mediterranean Diet With and Without Weight Loss on Apolipoprotein B 100 Metabolism in Men With Metabolic Syndrome

Objective—

To assess the effect of a Mediterranean diet (MedDiet) with and without weight loss (WL) on apolipoprotein B 100 (apoB 100 ) metabolism in men with metabolic syndrome.

Approach and Results—

The diet of 19 men with metabolic syndrome (age, 24–62 years) was first standardized to a North American isoenergetic control diet for 5 weeks, followed by an isoenergetic MedDiet for an additional 5 weeks under full-feeding conditions (MedDiet−WL). Participants next underwent a 20-week supervised WL program under free-living conditions (−10.2±2.9% body weight; P <0.01) and finally consumed the MedDiet (5 weeks) under weight-stabilizing feeding conditions (MedDiet+WL). In vivo kinetic of apoB 100 was assessed in the fasted state at the end of the 3 controlled diets using a bolus of D 3 -leucine. Compared with the control diet, MedDiet−WL reduced low-density lipoprotein (LDL)-apoB 100 pool size (−14.2%, P <0.01) primarily through an increase in LDL-apoB 100 fractional catabolic rate (+30.4%, P =0.02) and increased LDL particle size ( P <0.01) but had no effect on very-LDL (VLDL)-apoB 100 pool size or triglyceride concentrations, despite a significant increase in VLDL-apoB 100 fractional catabolic rate (+25.6%; P =0.03). MedDiet+WL had no further effect on LDL-apoB 100 pool size and fractional catabolic rate but further increased LDL particle size and reduced VLDL-apoB 100 pool size versus the control diet primarily through an increase in VLDL-apoB 100 fractional catabolic rate (+30.7%; P <0.01).

Conclusions—

Consumption of MedDiet increases LDL size and reduces LDL-apoB 100 concentrations primarily by increasing the catabolism of LDL even in the absence of WL in men with metabolic syndrome. MedDiet seems to have a trivial effect on VLDL concentrations and kinetics unless accompanied by significant WL.

Clinical Trial Registration

—URL: http://www.clinicaltrials.gov . Unique identifier: NCT00988650.

Inhibition of oxidative stress and lipid peroxidation by anthocyanins from defatted Canarium odontophyllum pericarp and peel using in vitro bioassays

Canarium odontophyllum, also known as CO, is a highly nutritious fruit. Defatted parts of CO fruit are potent sources of nutraceutical. This study aimed to determine oxidative stress and lipid peroxidation effects of defatted CO pericarp and peel extracts using in vitro bioassays. Cell cytotoxic effect of the CO pericarp and peel extracts were also evaluated using HUVEC and Chang liver cell lines. The crude extracts of defatted CO peel and pericarp showed cytoprotective effects in t-BHP and 40% methanol-induced cell death. The crude extracts also showed no toxic effect to Chang liver cell line. Using CD36 ELISA, NAD⁺ and LDL inhibition assays, inhibition of oxidative stress were found higher in the crude extract of defatted CO peel compared to the pericarp extract. Hemoglobin and LDL oxidation assays revealed both crude extracts had significantly reduced lipid peroxidation as compared to control. TBARS values among defatted CO pericarp, peel, and cyanidin-3-glucoside showed no significant differences for hemoglobin and LDL oxidation assays. The protective effects of defatted CO parts, especially its peel is related to the presence of high anthocyanin that potentially offers as a pharmaceutical ingredient for cardioprotection.