HDL lipid composition is profoundly altered in patients with type 2 diabetes and atherosclerotic vascular disease

Functional Lipids and Cardiovascular Disease Reduction: A Concise Review

Functional lipids are dietary substances that may have an impact on human health by lowering the risk of chronic illnesses and enhancing the quality of life. Numerous functional lipids have been reported to have potential health benefits in the prevention, management, and treatment of cardiovascular disease, the leading cause of death in the United States. However, there is still insufficient and contradictory information in the literature about their effectiveness and associated mechanisms of action. The objective of this review, therefore, is to evaluate available literature regarding these functional lipids and their health benefits. Various studies have been conducted to understand the links between functional lipids and the prevention and treatment of chronic diseases. Recent studies on phytosterols have reported that CLA, medium-chain triglycerides, and omega-3 and 6 fatty acids have positive effects on human health. Also, eicosanoids, which are the metabolites of these fatty acids, are produced in relation to the ratio of omega-3 to omega-6 polyunsaturated fatty acids and may modulate disease conditions. These functional lipids are available either in dietary or supplement forms and have been proven to be efficient, accessible, and inexpensive to be included in the diet. However, further research is required to properly elucidate the dosages, dietary intake, effectiveness, and their mechanisms of action in addition to the development of valid disease biomarkers and long-term effects in humans.

Thrombosis origin identification of cardioembolism and large artery atherosclerosis by distinct metabolites

BACKGROUND

The diagnosis of cerebral thrombosis origin is challenging and remains unclear. This study aims to identify thrombosis due to cardioembolism (CE) and large artery atherosclerosis (LAA) from a new perspective of distinct metabolites.

METHODS

Distinct metabolites between 26 CE and 22 LAA origin thrombi, which were extracted after successful mechanical thrombectomy in patients with acute ischemic stroke in the anterior circulation, were analyzed with a ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) system. Enriched metabolic pathways related to the metabolites were identified. Least absolute shrinkage selection operator regression analyses and a filtering method were used to select potential predictors. Furthermore, four machine learning classifiers, including decision tree, logistic regression, random forest (RF), and k means unsupervised classification model, were used to evaluate the predictive ability of the selected metabolites.

RESULTS

UPLC-QTOF-MS analysis revealed that levels of 88 and 55 metabolites were elevated in LAA and CE thrombi, respectively. Kyoto Encyclopedia of Genes and Genomes analysis revealed a significant difference between the pathways enriched in the two types of thrombi. Six metabolites (diglyceride (DG, 18:3/24:0), DG (22:0/24:0), phytosphingosine, galabiosylceramide (18:1/24:1), triglyceride (15:0/16:1/o-18:0), and glucosylceramide (18:1/24:0)) were finally selected to build a predictive model. The predictive RF model was confirmed to be the best, with a satisfactory stability and prediction capacity (area under the curve=0.889).

CONCLUSIONS

Six metabolites as potential predictors for distinguishing between cerebral thrombi of CE and LAA origin were identified. The results are useful for understanding the pathogenesis and for secondary stroke prevention.

High levels of oxidized fatty acids in HDL impair the antioxidant function of HDL in patients with diabetes

AIMS

Previous studies demonstrate that the antioxidant functions of high-density lipoprotein (HDL) are impaired in diabetic patients. The composition of HDL plays an important role in maintaining the normal functionality of HDL. In this study, we compared the levels of oxidized fatty acids in HDL from diabetic subjects and non-diabetic healthy controls, aiming to investigate the role of oxidized fatty acids in the antioxidant property of HDL.

METHODS

HDL was isolated from healthy subjects (n=6) and patients with diabetes (n=6, hemoglobin A1c ≥ 9%, fasting glucose ≥ 7 mmol/L) using a dextran sulfate precipitation method. Cholesterol efflux capacity mediated by HDL was measured on THP-1 derived macrophages. The antioxidant capacity of HDL was evaluated with dichlorofluorescein-based cellular assay in human aortic endothelial cells. Oxidized fatty acids in HDL were determined by liquid chromatography-tandem mass spectrometry. The correlations between the levels of oxidized fatty acids in HDL and the endothelial oxidant index in cells treated with HDLs were analyzed through Pearson's correlation analyses, and the effects of oxidized fatty acids on the antioxidant function of HDL were verified in vitro.

RESULTS

The cholesterol efflux capacity of HDL and the circulating HDL-cholesterol were similar in diabetic patients and healthy controls, whereas the antioxidant capacity of HDL was significantly decreased in diabetic patients. There were higher levels of oxidized fatty acids in HDL isolated from diabetic patients, which were strongly positively correlated with the oxidant index of cells treated with HDLs. The addition of a mixture of oxidized fatty acids significantly disturbed the antioxidant activity of HDL from healthy controls, while the apolipoprotein A-I mimetic peptide D-4F could restore the antioxidant function of HDL from diabetic patients.

CONCLUSION

HDL from diabetic patients displayed substantially impaired antioxidant activity compared to HDL from healthy subjects, which is highly correlated with the increased oxidized fatty acids levels in HDL.

HDL and type 2 diabetes: the chicken or the egg?

HDL is a complex macromolecular cluster of various components, such as apolipoproteins, enzymes and lipids. Quality evidence from clinical and epidemiological studies led to the principle that HDL-cholesterol (HDL-C) levels are inversely correlated with the risk of CHD. Nevertheless, the failure of many cholesteryl ester transfer protein inhibitors to protect against CVD casts doubts on this principle and highlights the fact that HDL functionality, as dictated by its proteome and lipidome, also plays an important role in protecting against metabolic disorders. Recent data indicate that HDL-C levels and HDL particle functionality are correlated with the pathogenesis and prognosis of type 2 diabetes mellitus, a major risk factor for CVD. Hyperglycaemia leads to reduced HDL-C levels and deteriorated HDL functionality, via various alterations in HDL particles' proteome and lipidome. In turn, reduced HDL-C levels and impaired HDL functionality impact the performance of key organs related to glucose homeostasis, such as pancreas and skeletal muscles. Interestingly, different structural alterations in HDL correlate with distinct metabolic abnormalities, as indicated by recent data evaluating the role of apolipoprotein A1 and lecithin-cholesterol acyltransferase deficiency in glucose homeostasis. While it is becoming evident that not all HDL disturbances are causatively associated with the development and progression of type 2 diabetes, a bidirectional correlation between these two conditions exists, leading to a perpetual self-feeding cycle.

Adiponectin predicts the antioxidant capacity and size of high-density lipoprotein (HDL) in individuals with diabetes mellitus

AIMS

The relationship between adiponectin and type 2 diabetes mellitus (T2DM) is established; however the evidence on its role in high-density lipoprotein (HDL) functionality is still scant. The aim of this study was to assess the association of adiponectin with HDL functionality especially on the antioxidant capacity and HDL subfractions in individuals with T2DM.

METHODS

This case-control study enrolled 356 individuals who were divided into two groups: diabetics [T2DM (n = 188)] and non-diabetic [nT2DM (n = 168)]. The association of adiponectin level on HDL functionality parameters was done in function of the cut-off point for adiponectin [percentile p < 75 = 12.9 μg/mL versus p ≥ 75 = 12.9 μg/mL] and multiple adjustments applied in the logistic regression models.

RESULTS

Body mass index (BMI), waist circumference (WC) and body fat mass (FM) were higher in T2DM. The larger HDL particles (HDL_LARGE) were lower in T2DM group in comparison with nT2DM (28.20% versus 30.40%; p = 0.016). Individuals with T2DM and simultaneous highest adiponectin (p ≥ 75) had 2.25 OR (95% CI = 1.03-4.91) and 5.14 OR (95% CI = 2.37-11.15) to present higher HDL-C and HDL_LARGE concentrations. After adjustment for multiple confounders, high level of adiponectin was independently related with improvement of the HDL antioxidant capacity (OR = 2.78; 95% CI = 1.16-6.67).

CONCLUSIONS

High adiponectin level associates with a lesser negative impact of T2DM on HDL functionality by increase in APO AI, particles size, and cholesterol content. On the same token, higher adiponectin was associated with greater odds to have high antioxidant capacity.

Anti-Inflammatory HDL Function, Incident Cardiovascular Events, and Mortality: A Secondary Analysis of the JUPITER Randomized Clinical Trial

Background

High‐density lipoprotein (HDL) cholesterol has inverse association with cardiovascular disease. HDL possesses anti‐inflammatory properties in vitro, but it is unknown whether this may be protective in individuals with inflammation.

Methods and Results

The functional capacity of HDL to inhibit oxidation of oxidized low‐density lipoprotein (ie, the HDL inflammatory index; HII) was measured at baseline and 12 months after random allocation to rosuvastatin or placebo in a nested case‐control study of the JUPITER (Justification for the Use of Statins in Prevention: An Intervention Evaluating Rosuvastatin) trial. There were 517 incident cases of cardiovascular disease and all‐cause mortality compared to 517 age‐ and sex‐matched controls. Multivariable conditional logistic regression was used to examine associations of HII with events. Median baseline HII was 0.54 (interquartile range, 0.50–0.59). Twelve months of rosuvastatin decreased HII by a mean of 5.3% (95% CI, −8.9% to −1.7%; P=0.005) versus 1.3% (95% CI, −6.5% to 4.0%; P=0.63) with placebo (P=0.22 for between‐group difference). HII had a nonlinear relationship with incident events. Compared with the reference group (HII 0.5–1.0) with the lowest event rates, participants with baseline HII ≤0.5 had significantly increased risk of cardiovascular disease/mortality (adjusted hazard ratio, 1.53; 95% CI, 1.06–2.21; P=0.02). Furthermore, there was significant (P=0.002) interaction for HDL particle number with HII, such that having more HDL particles was associated with decreased risk only when HDL was anti‐inflammatory.

Conclusions

In JUPITER participants recruited on the basis of chronic inflammation, HII was associated with incident cardiovascular disease/mortality, with an optimal anti‐inflammatory HII range between 0.5 and 1.0. This nonlinear relationship of anti‐inflammatory HDL function with risk may account in part for the HDL paradox.

Registration

URL: https://www.clini​caltr​ials.gov; Unique identifier: NCT00239681.

The Effects of Linoleic Acid Consumption on Lipid Risk Markers for Cardiovascular Disease in Healthy Individuals: A Review of Human Intervention Trials

Cardiovascular disease (CVD) is the leading cause of death worldwide. Risk factors for developing this disease include high serum concentrations of total cholesterol, triglycerides, low-density lipoproteins, very-low density lipoproteins, and low concentrations of high-density lipoproteins. One proposed dietary strategy for decreasing risk factors involves replacing a portion of dietary saturated fatty acids with mono- and polyunsaturated fatty acids (PUFAs). The essential omega-6 PUFA, linoleic acid (LA), is suggested to decrease the risk for CVD by affecting these lipid risk markers. Reviewing human intervention trials will provide further evidence of the effects of LA consumption on risk factors for CVD. PubMed was used to search for peer-reviewed articles. The purpose of this review was: (1) To summarize human intervention trials that studied the effects of LA consumption on lipid risk markers for CVD in healthy individuals, (2) to provide mechanistic details, and (3) to provide recommendations regarding the consumption of LA to decrease the lipid risk markers for CVD. The results from this review provided evidence that LA consumption decreases CVD lipid risk markers in healthy individuals.

The Effects of Heme Oxygenase Upregulation on Obesity and the Metabolic Syndrome

Significance: Obesity is a chronic condition that is characterized by inflammation and oxidative stress with consequent cardiovascular complications of hypertension, dyslipidemia, and vascular dysfunction. Obesity-induced metabolic syndrome remains an epidemic of global proportions. Recent Advances: Gene targeting of the endothelium with a retrovirus using an endothelium-specific promoter vascular endothelium cadherin (VECAD)-HO-1 offers a potential long-term solution to adiposity by targeting the endothelium. This has resulted in improvements of both vascular function and adiposity attenuation. Critical Issues: Heme oxygenase plays an ever-increasing role in the understanding of human biology in the complex conditions of obesity and the metabolic syndrome. The heme oxygenase 1 (HO-1) system creates biliverdin/bilirubin, which functions as an antioxidant, and carbon monoxide, which has antiapoptotic properties. Future Directions: Upregulation of HO-1 has been shown to improve adiposity as well as vascular function in both animal and human studies.

A Review of Lipidomics of Cardiovascular Disease Highlights the Importance of Isolating Lipoproteins

Cutting-edge lipidomic profiling measures hundreds or even thousands of lipids in plasma and is increasingly used to investigate mechanisms of cardiovascular disease (CVD). In this review, we introduce lipidomic techniques, describe distributions of lipids across lipoproteins, and summarize findings on the association of lipids with CVD based on lipidomics. The main findings of 16 cohort studies were that, independent of total and high-density lipoprotein cholesterol (HDL-c), ceramides (d18:1/16:0, d18:1/18:0, and d18:1/24:1) and phosphatidylcholines (PCs) containing saturated and monounsaturated fatty acyl chains are positively associated with risks of CVD outcomes, while PCs containing polyunsaturated fatty acyl chains (PUFA) are inversely associated with risks of CVD outcomes. Lysophosphatidylcholines (LPCs) may be positively associated with risks of CVD outcomes. Interestingly, the distributions of the identified lipids vary across lipoproteins: LPCs are primarily contained in HDLs, ceramides are mainly contained in low-density lipoproteins (LDLs), and PCs are distributed in both HDLs and LDLs. Thus, the potential mechanism behind previous findings may be related to the effect of the identified lipids on the biological functions of HDLs and LDLs. Only eight studies on the lipidomics of HDL and non-HDL particles and CVD outcomes have been conducted, which showed that higher triglycerides (TAGs), lower PUFA, lower phospholipids, and lower sphingomyelin content in HDLs might be associated with a higher risk of coronary heart disease (CHD). However, the generalizability of these studies is a major concern, given that they used case-control or cross-sectional designs in hospital settings, included a very small number of participants, and did not correct for multiple testing or adjust for blood lipids such as HDL-c, low-density lipoprotein cholesterol (LDL-c), or TAGs. Overall, findings from the literature highlight the importance of research on lipidomics of lipoproteins to enhance our understanding of the mechanism of the association between the identified lipids and the risk of CVD and allow the identification of novel lipid biomarkers in HDLs and LDLs, independent of HDL-c and LDL-c. Lipidomic techniques show the feasibility of this exciting research direction, and the lack of high-quality epidemiological studies warrants well-designed prospective cohort studies.

High-density lipoprotein lipid peroxidation as a molecular signature of the risk for developing cardiovascular disease: Results from MASHAD cohort

High-density lipoprotein (HDL) function rather than level may better predict cardiovascular disease (CVD). However, the contribution of the impaired antioxidant function of HDL that is associated with increased HDL lipid peroxidation (HDLox) to the development of clinical CVD remains unclear. We have investigated the association between serum HDLox with incident CVD outcomes in Mashhad cohort. Three-hundred and thirty individuals who had a median follow-up period of 7 years were recruited as part of the cohort. The primary end point was cardiovascular event, including myocardial infarction, stable angina, unstable angina, or coronary revascularization. In both univariate/multivariate analyses adjusted for traditional CVD risk factors, HDLox was an independent risk factor for CVD (odds ratio, 1.62; 95% confidence interval, 1.41-1.86; p < 0.001). For every increase in HDLox by 0.1 unit, there was an increase in CVD risk by 1.62-fold. In an adjusted analysis, there was a >2.5-fold increase in cardiovascular risk in individuals with HDLox higher than cutoff point of 1.06 compared to those with lower scores, suggesting HDLox > 1.06 is related to the impaired HDL oxidant function and in turn exposed to elevated risk of CVD outcomes (hazard ratio, 2.72; 95% CI, 1.88-3.94). Higher HDLox is a surrogate measure of reduced HDL antioxidant function that positively associated with cardiovascular events in a population-based cohort.

Accelerated Atherosclerosis in Rheumatoid Arthritis: Mechanisms and Treatment

Background:

Rheumatoid arthritis (RA) is a chronic systemic autoimmune inflammatory disorder that increases the risk of developing cardiovascular disease. There is accumulating evidence that the RA disease state accelerates the formation of atherosclerotic plaques. Treatments for RA improve joint symptomatology and may reduce inflammation, but consideration of their effects on the cardiovascular system is generally low priority.

Objective:

Since cardiovascular disease is the leading cause of mortality in RA patients, the impact of RA therapies on atherosclerosis is an area in need of attention and the focus of this review.

Results:

The drugs used to treat RA may be analgesics, conventional disease-modifying anti-rheumatic drugs, and/or biologics, including antibodies against the cytokine tumor necrosis factor-α. Pain relievers such as nonselective non-steroidal anti-inflammatory drugs and cyclooxygenase inhibitors may adversely affect lipid metabolism and cyclooxygenase inhibitors have been associated with increased adverse cardiovascular events, such as myocardial infarction and stroke. Methotrexate, the anchor disease-modifying anti-rheumatic drug in RA treatment has multiple atheroprotective advantages and is often combined with other therapies. Biologic inhibitors of tumor necrosis factor-α may be beneficial in preventing cardiovascular disease because tumor necrosis factor-α promotes the initiation and progression of atherosclerosis. However, some studies show a worsening of the lipid profile in RA with blockade of this cytokine, leading to higher total cholesterol and triglycerides.

Conclusion:

Greater understanding of the pharmacologic activity of RA treatments on the atherosclerotic process may lead to improved care, addressing both damages to the joints and heart.

Apolipoprotein A-I mimetics mitigate intestinal inflammation in COX2-dependent inflammatory bowel disease model

Cyclooxygenase 2 (Cox2) total knockout and myeloid knockout (MKO) mice develop Crohn's-like intestinal inflammation when fed cholate-containing high fat diet (CCHF). We demonstrated that CCHF impaired intestinal barrier function and increased translocation of endotoxin, initiating TLR/MyD88-dependent inflammation in Cox2 KO but not WT mice. Cox2 MKO increased pro-inflammatory mediators in LPS-activated macrophages, and in the intestinal tissue and plasma upon CCHF challenge. Cox2 MKO also reduced inflammation resolving lipoxin A4 (LXA4) in intestinal tissue, while administration of an LXA4 analog rescued disease in Cox2 MKO mice fed CCHF. The apolipoprotein A-I (APOA1) mimetic 4F mitigated disease in both the Cox2 MKO/CCHF and piroxicam-accelerated Il10-/- models of inflammatory bowel disease (IBD) and reduced elevated levels of pro-inflammatory mediators in tissue and plasma. APOA1 mimetic Tg6F therapy was also effective in reducing intestinal inflammation in the Cox2 MKO/CCHF model. We further demonstrated that APOA1 mimetic peptides: i) inhibited LPS and oxidized 1-palmitoyl-2-arachidonoyl-sn-phosphatidylcholine (oxPAPC) dependent pro-inflammatory responses in human macrophages and intestinal epithelium; and ii) directly cleared pro-inflammatory lipids from mouse intestinal tissue and plasma. Our results support a causal role for pro-inflammatory and inflammation resolving lipids in IBD pathology and a translational potential for APOA1 mimetic peptides for the treatment of IBD.

Large triglyceride-rich lipoproteins from fasting patients with type 2 diabetes activate platelets

AIMS

Type 2 diabetes (T2D) patients present with risk factors for atherothrombosis such as fasting hypertriglyceridaemia and platelet hyperactivity. Our study objective was to determine the effect of large triglyceride-rich lipoproteins (TGRL) from fasting T2D patients on platelet aggregation and, if any, to identify the signaling pathway involved.

METHODS

Large TGRL were isolated from the plasma of 25 T2D patients by ultracentrifugation (density < 1.000 g/mL). Platelets were isolated from healthy blood donors (HBD) and suspended in buffer, then preincubated in the presence or absence of TGRL and stimulated with either collagen or thrombin. Platelet aggregation and the arachidonic acid (AA) signaling pathway were studied.

RESULTS

Fasting T2D large TGRL were mostly of hepatic origin (apoB100/apoB48 ratio: 42 ± 7) and rich in triglycerides (TG/total apoB ratio: 4.2 ± 0.5), and able to potentiate agonist-stimulated platelet aggregation (collagen: +68%, P < 0.05; thrombin: +771%, P < 0.05). It should also be mentioned that TGRL from the plasma of HBD (n = 7) had no effect on platelet aggregation. In addition, T2D large TGRL increased thromboxane B₂ (TxB₂) concentration in platelets stimulated with either collagen (+34%, P < 0.05) or thrombin (+37%, P < 0.05) compared with platelets stimulated with either of these agonists without TGRL. Phosphorylation of p38 MAPK and cytosolic phospholipase A₂ (cPLA₂) was enhanced after incubation of platelets with T2D TGRL and thrombin (+87% and +32%, respectively, P < 0.05) compared with platelets incubated with thrombin only.

CONCLUSION

Large TGRL from fasting T2D patients may play a role in the development of atherothrombosis by increasing platelet aggregation and activating the platelet AA signaling pathway.

The Relationship between Eicosanoid Levels and Serum Levels of Metabolic and Hormonal Parameters Depending on the Presence of Metabolic Syndrome in Patients with Benign Prostatic Hyperplasia

Background: The purpose of our investigation was to analyze the relationship between the serum levels of inflammatory mediators (HETE, HODE) and the levels of selected metabolic and hormonal parameters in patients with benign prostatic hyperplasia (BPH) with regard to concomitant metabolic syndrome (MetS). Methods: The study involved 151 men with BPH. Blood samples were taken for laboratory analysis of the serum levels of metabolic and hormonal parameters. Gas chromatography was performed using an Agilent Technologies 7890A GC System. Results: We found that waist circumference was the only parameter related to the levels of fatty acids, namely: 13(S)-HODE, 9(S)-HODE, 15(S)-HETE, 12(S)-HETE, and 5-HETE. In the patients with BPH and MetS, triglycerides correlated with 9(S)-HODE, 15(S)-HETE, 12(S)-HETE, and 5-HETE, which was not observed in the patients without MetS. Similarly, total cholesterol correlated with 9(S)-HODE, and 15(S)-HETE in the patients with BPH and MetS, but not in those without MetS. In the group of BPH patients with MetS, total testosterone positively correlated with 13(S)-HODE, and free testosterone with 9(S)-HODE. Conclusions: Based on this study, it can be concluded that lipid mediators of inflammation can influence the levels of biochemical and hormonal parameters, depending on the presence of MetS in BPH patients.

The Role of High-Density Lipoproteins in Diabetes and Its Vascular Complications

Almost 600 million people are predicted to have diabetes mellitus (DM) by 2035. Diabetic patients suffer from increased rates of microvascular and macrovascular complications, associated with dyslipidaemia, impaired angiogenic responses to ischaemia, accelerated atherosclerosis, and inflammation. Despite recent treatment advances, many diabetic patients remain refractory to current approaches, highlighting the need for alternative agents. There is emerging evidence that high-density lipoproteins (HDL) are able to rescue diabetes-related vascular complications through diverse mechanisms. Such protective functions of HDL, however, can be rendered dysfunctional within the pathological milieu of DM, triggering the development of vascular complications. HDL-modifying therapies remain controversial as many have had limited benefits on cardiovascular risk, although more recent trials are showing promise. This review will discuss the latest data from epidemiological, clinical, and pre-clinical studies demonstrating various roles for HDL in diabetes and its vascular complications that have the potential to facilitate its successful translation.

A short-term increase in dietary cholesterol and fat intake affects high-density lipoprotein composition in healthy subjects

BACKGROUND AND AIMS

High-cholesterol and high-fat diets alter biochemical composition and anti-oxidant properties of high-density lipoproteins (HDL) in animals. Whether this occurs in humans is unknown. Therefore, we examined the effect of a short-term elevation in dietary cholesterol and fat intake on HDL composition in healthy subjects.

METHODS AND RESULTS

In a randomized, crossover clinical trial, 14 healthy young volunteers followed a 14-day low-cholesterol/low-fat diet (LChF) and a 14-day isocaloric high-cholesterol/high-fat diet (HChF) in a random order. After each diet, we measured HDL concentrations of hydroxyeicosatetraenoic acids (HETE), hydroxyoctadecadienoic acids (HODE), and haptoglobin, as well as serum amyloid A (SAA) and paroxonase-1 activity (PON-1). HDL concentrations of 15-HETE (+254%, p = 0.002), 5-HETE (+116%, p = 0.004), 13-HODE (+102%, p = 0.049), and SAA levels (+75%, p = 0.007) were significantly higher after the HChF than after the LChF. Furthermore, haptoglobin was marginally increased (+32%, p = 0.091) while PON-1 activity was unaffected (-16%, p = 0.366) by the HChF.

CONCLUSION

In healthy subjects, a short-term elevation in dietary cholesterol and fat intake increases HDL lipid hydroperoxide content (15-HETE, 5-HETE, 13-HODE) and SAA levels, which are key features of dysfunctional HDL. This is the first study showing that a physiologic manipulation of dietary cholesterol and fat intake affects HDL lipidome and proteome in healthy subjects independently of weight changes.

CLINICAL TRIAL REGISTRATION

NCT02549144.

Acute coronary syndrome remodels the antiplatelet aggregation properties of HDL particle subclasses

Essentials HDL subclasses were studied in acute coronary syndrome (ACS). HDL2 from ACS patients have better antiplatelet potency than HDL from non ACS subjects. ACS remodels the antiplatelet properties of HDL subclasses. Oxidized polyunsaturated fatty acids content of HDL is modified by ACS.

SUMMARY

Background Although HDLs have antithrombotic effects by reducing platelet activation, the relationship between HDL levels and the risk of acute coronary syndrome (ACS) is unclear, as HDL particles are heterogeneous in composition and biological properties. Objective To characterize the effects of HDL2 and HDL3 subclasses from ACS patients and non-coronary artery disease (CAD) subjects on platelet activation. Methods We measured platelet aggregation and ex vivo thrombus formation, analyzed signaling pathways by flow cytometry, and performed a targeted lipidomics analysis on HDL subclasses. Results Analysis of human platelet aggregation in suspension, adhesion on von Willebrand factor and thrombus formation on collagen under arterial shear demonstrated that HDL2 from ACS patients had higher antiplatelet potency than HDL3 from ACS patients and HDL from non-CAD subjects. HDL binding to scavenger receptor class B type I was essential for this effect. A lipidomics analysis revealed that HDL2 from ACS patients had more oxidized polyunsaturated fatty acids (PUFAs). An inverse correlation between the concentrations of 9-hydroxyoctadecadienoic acid (9-HODE), 13-hydroxyoctadecadienoic acid (13-HODE), the eicosapentaenoic acid metabolite 18-hydroxyeicosapentaenoic acid (18-HEPE) and hydroxyeicosatetraenoic acid isomers in HDL2 and platelet aggregation was observed. This relationship was further demonstrated by the direct inhibitory effects of 18-HEPE, 9-HODE, 13-HODE, 17-hydroxydocosahexaenoic acid and 14-hydroxydocosahexaenoic acid on collagen-related peptide-induced platelet aggregation, indicating that oxidized PUFAs contribute to the antithrombotic effect of ACS HDL2. Conclusions Our data shed new light on the antiplatelet effects of HDL subclasses, and suggest physiological adaptation through the modulation of HDL properties in ACS patients that may limit their platelet-dependent thrombotic risk.

High levels of oxidized fatty acids in HDL are associated with impaired HDL function in patients with active rheumatoid arthritis

The objective of this study was to evaluate oxidation products of arachidonic acid and linoleic acid in lipoproteins and synovial fluid (SF) from patients with active rheumatoid arthritis (RA) compared to non-RA controls. High-density lipoproteins (HDL) and low-density lipoproteins (LDL) were isolated from plasma using fast protein liquid chromatography and HDL was isolated from SF using dextran sulfate precipitation. 5-Hydroxyeicosatetraenoic acid (HETE), 12-HETE, 15-HETE, 9 hydroxyoctadecadienoic (HODE), and 13-HODE levels were measured in HDL, LDL, and SF by liquid chromatography-tandem mass spectrometry. HDL's anti-inflammatory function, cholesterol levels, myeloperoxidase (MPO) and paraoxonase 1 (PON1) activities were determined as previously. 5-HETE, 15-HETE, 9-HODE, and 13-HODE levels were significantly increased in HDL and LDL from patients with active RA (n = 10) compared to healthy controls (n = 8) and correlated significantly with measures of systemic inflammation, particularly in HDL (r = 0.65-0.80, p values < 0.004). Higher HETES and HODES in HDL were also significantly correlated with impaired HDL function as measured by the HDL inflammatory index (HII) (r = 0.54-0.58; p values < 0.03). 15-HETE levels and MPO activity were higher in RA SF (n = 10) compared to osteoarthritis (OA) SF(n = 11), and HDL from RA SF had worse function compared to OA SF HDL (HII = 2.1 ± 1.9 and 0.5 ± 0.1), respectively (p < 0.05). Oxidation products of arachidonic acid and linoleic acid are increased in HDL and LDL from patients with active RA compared to healthy controls, and are associated with worse anti-oxidant function of HDL. These results suggest a potential mechanism by which oxidative stress from active RA increases oxidized fatty acids in HDL, promoting HDL dysfunction, and thereby increasing atherosclerotic risk.

Cell-free Biochemical Fluorometric Enzymatic Assay for High-throughput Measurement of Lipid Peroxidation in High Density Lipoprotein

Low high-density lipoprotein cholesterol (HDL-C) levels are one of the most powerful independent negative predictors of atherosclerotic cardiovascular disease (CVD). The structure and function of HDL rather than HDL-C may more accurately predict atherosclerosis. Several HDL protein and lipid compositional changes that impair HDL function occur in inflammatory states such as atherosclerosis. HDL function is usually determined by cell based assays such as cholesterol efflux assay but these assays have numerous drawbacks lack of standardization. Cell-free assays may give more robust measures of HDL function compared to cell-based assays. HDL oxidation impairs HDL function. HDL has a major role in lipid peroxide transport and high amount of lipid peroxides is related to abnormal HDL function. Lipid-probe interactions should be considered when interpreting the results of non-enzymatic fluorescence assays for measuring the lipid oxidative state. This motivated us to develop a cell-free biochemical enzymatic method to assess HDL lipid peroxide content (HDLox) that contributes to HDL dysfunction. This method is based on the enzyme horseradish peroxidase (HRP) and the fluorochrome Amplex Red that can quantify (without cholesterol oxidase) the lipid peroxide content per mg of HDL-C. Here a protocol is describedfor determination of HDL-lipid peroxidation using the fluorochrome reagent. Assay variability can be reduced by strict standardization of experimental conditions. Higher HDLox values are associated with reduced HDL antioxidant function. The readout of this assay is associated with readouts of validated cell-based assays, surrogate measures of cardiovascular disease, systemic inflammation, immune dysfunction, and associated cardiovascular and metabolic risk phenotypes. This technical approach is a robust method to assess HDL function in human disease where systemic inflammation, oxidative stress and oxidized lipids have a key role (such as atherosclerosis).

Low serum paraoxonase1 activity levels predict coronary artery disease severity

Paraoxonase1 (PON1) activity is closely related to coronary artery disease (CAD). However, whether PON1 activity can predict the degree of coronary stenosis remains unknown. In the present study, the serum PON1 activity and related factors that influence PON1 activity were analyzed in 186 patients with diagnostic coronary angiography. The serum PON1 activity was determined using a spectrophotometry-based assay in 186 patients with diagnostic coronary angiography, in which coronary stenosis severity was graded and clinically defined as single- or multi-vessel stenosis >50%. Target lesion stenosis was quantified via quantitative coronary angiography (QCA). The serum PON1 activity was significantly decreased in the CAD group, the multiple coronary stenosis subgroup, and the diabetes mellitus subgroup compared with each control group. The PON1 activity was positively correlated with the High density lipoprotein cholesterol (HDL-C) and Apolipoprotein A1 (ApoA1). Males, smoking, diabetes, and heart failure were identified as factors that influenced PON1 activity. Furthermore, a Receiver Operating Characteristic Curve (ROC) analysis indicated that a PON1 activity cut-off point of 330 U/L could predict CAD with a sensitivity of 52% and a specificity of 65%. In conclusion, low PON1 activity predicted the degree of coronary lesion, particularly in multiple vessel lesions, smokers, and diabetes, which may represent a biochemical marker for the severity of CAD.

Circulating fibroblast growth factor-23 plasma levels predict adverse cardiovascular outcomes in patients with diabetes mellitus with coronary artery disease

BACKGROUND

Abnormalities of fibroblast growth factor-23 (FGF-23) plasma levels predict adverse outcomes in patients with coronary artery disease. However, FGF-23 has a different behaviour in the presence of type 2 diabetes mellitus (T2D). We explored whether the presence of T2D affects the predictive power of FGF-23.

METHODS

In 704 patients with stable coronary artery disease, FGF-23, calcidiol, parathormone (PTH) and phosphate plasma levels were prospectively assessed. The primary outcome was the development of acute ischemic events (acute coronary syndrome, stroke or transient ischemic attack), heart failure or death.

RESULTS

One hundred seventy-three (24.6%) patients had T2D, without differences in age, sex or estimated glomerular filtration rate as compared with non-diabetic patients. Serum PTH was lower and phosphate higher in T2D than in non-diabetic patients, without differences in FGF-23 or calcidiol levels. During follow-up (2.15 ± 0.99 years), 26 (15.2%) T2D and 51 (9.6%) non-diabetic patients developed the outcome (p = 0.048). T2D patients who developed the outcome had higher FGF-23 [112.0 (59.9, 167.6) vs 68.9 (54.2, 93.0) RU/mL; p = 0.002], PTH [71.3 (47.3, 106.6) vs 51.9 (40.8, 66.2) pg/mL; p = 0.004) and phosphate (3.53 ± 0.71 vs 3.25 ± 0.50 mg/dL; p = 0.017) levels than T2D subjects who remained stable. These differences were not significant in non-diabetic patients. By multivariable Cox proportional hazard model, FGF-23 predicted independently the outcome in T2D patients [hazard ratio = 1.277; 95% CI (1.132, 1.442)] but not in those without T2D.

CONCLUSIONS

FGF-23 plasma levels predict adverse cardiovascular outcomes in coronary artery disease patients who have T2D but not in those without T2D. This finding should be confirmed in larger studies. Copyright © 2016 John Wiley & Sons, Ltd.

Dysfunctional high-density lipoproteins in coronary heart disease: implications for diagnostics and therapy

Low plasma levels of high-density lipoprotein (HDL) cholesterol are associated with increased risks of coronary heart disease. HDL mediates cholesterol efflux from macrophages for reverse transport to the liver and elicits many anti-inflammatory and anti-oxidative activities which are potentially anti-atherogenic. Nevertheless, HDL has not been successfully targeted by drugs for prevention or treatment of cardiovascular diseases. One potential reason is the targeting of HDL cholesterol which does not capture the structural and functional complexity of HDL particles. Hundreds of lipid species and dozens of proteins as well as several microRNAs have been identified in HDL. This physiological heterogeneity is further increased in pathologic conditions due to additional quantitative and qualitative molecular changes of HDL components which have been associated with both loss of physiological function and gain of pathologic dysfunction. This structural and functional complexity of HDL has prevented clear assignments of molecules to the functions of normal HDL and dysfunctions of pathologic HDL. Systematic analyses of structure-function relationships of HDL-associated molecules and their modifications are needed to test the different components and functions of HDL for their relative contribution in the pathogenesis of atherosclerosis. The derived biomarkers and targets may eventually help to exploit HDL for treatment and diagnostics of cardiovascular diseases.

Dysfunctional High-Density Lipoprotein: An Innovative Target for Proteomics and Lipidomics

High-Density Lipoprotein-Cholesterol (HDL-C) is regarded as an important protective factor against cardiovascular disease, with abundant evidence of an inverse relationship between its serum levels and risk of cardiovascular disease, as well as various antiatherogenic, antioxidant, and anti-inflammatory properties. Nevertheless, observations of hereditary syndromes featuring scant HDL-C concentration in absence of premature atherosclerotic disease suggest HDL-C levels may not be the best predictor of cardiovascular disease. Indeed, the beneficial effects of HDL may not depend solely on their concentration, but also on their quality. Distinct subfractions of this lipoprotein appear to be constituted by specific protein-lipid conglomerates necessary for different physiologic and pathophysiologic functions. However, in a chronic inflammatory microenvironment, diverse components of the HDL proteome and lipid core suffer alterations, which propel a shift towards a dysfunctional state, where HDL-C becomes proatherogenic, prooxidant, and proinflammatory. This heterogeneity highlights the need for further specialized molecular studies in this aspect, in order to achieve a better understanding of this dysfunctional state; with an emphasis on the potential role for proteomics and lipidomics as valuable methods in the search of novel therapeutic approaches for cardiovascular disease.

Effects of short-term walnut consumption on human microvascular function and its relationship to plasma epoxide content

Improved vascular function after the incorporation of walnuts into controlled or high-fat diets has been reported; however, the mechanism(s) underlying this effect of walnuts is(are) poorly defined. The objective of the current study was to evaluate the acute and short-term effects of walnut intake on changes in microvascular function and the relationship of these effects to plasma epoxides, the cytochrome-P450-derived metabolites of fatty acids. Thirty-eight hypercholesterolemic postmenopausal women were randomized to 4 weeks of 5 g or 40 g of daily walnut intake. All outcomes were measured after an overnight fast and 4 h after walnut intake. Microvascular function, assessed as the reactive hyperemia index (RHI), was the primary outcome measure, with serum lipids and plasma epoxides as secondary measures. Compared to 5 g of daily walnut intake, consuming 40 g/d of walnuts for 4 weeks increased the RHI and Framingham RHI. Total cholesterol and low- and high-density cholesterol did not significantly change after walnut intake. The change in RHI after 4 weeks of walnut intake was associated with the change in the sum of plasma epoxides (r=0.65, P=.002) but not with the change in the sum of plasma hydroxyeicosatetraenoic acids. Of the individual plasma epoxides, arachidonic-acid-derived 14(15)-epoxyeicosatrienoic acid was most strongly associated with the change in microvascular function (r=0.72, P<.001). These data support the concept that the intake of walnut-derived fatty acids can favorably affect plasma epoxide production, resulting in improved microvascular function.

Glycoxidized HDL, HDL enriched with oxidized phospholipids and HDL from diabetic patients inhibit platelet function

CONTEXT

High-density lipoproteins (HDL) possess atheroprotective properties including anti-thrombotic and antioxidant effects. Very few studies relate to the functional effects of oxidized HDL on platelets in type 2 diabetes (T2D).

OBJECTIVE

The objective of our study was to investigate the effects of in vitro glycoxidized HDL and HDL from patients with T2D on platelet aggregation and arachidonic acid signaling cascade. At the same time, the contents of hydroxylated fatty acids were assessed in HDL.

RESULTS

Compared with control HDL, in vitro glycoxidized HDL had decreased proportions of linoleic (LA) and arachidonic (AA) acids in phospholipids and cholesteryl esters, and increased concentrations of hydroxy-octadecadienoic acids (9-HODE and 13-HODE) and 15-hydroxy-eicosatetraenoic acid (15-HETE), derived from LA and AA respectively, especially hydroxy derivatives esterified in phospholipids. Glycoxidized HDL dose-dependently decreased collagen-induced platelet aggregation by binding to scavenger receptor BI (SR-BI). Glycoxidized HDL prevented collagen-induced increased phosphorylation of platelet p38 MAPK and cytosolic phospholipase A2, as well as intracellular calcium mobilization. HDL enriched with oxidized phosphatidylcholine (PC), namely PC(16:0/13-HODE) dose-dependently inhibited platelet aggregation. Increased concentrations of 9-HODE, 13-HODE, and 15-HETE in phospholipids (2.1-, 2.1-, and 2.4-fold increase, respectively) were found in HDL from patients with T2D, and these HDL also inhibited platelet aggregation via SR-BI.

CONCLUSIONS

Our results suggest that in vitro glycoxidized HDL as well as HDL from patients with T2D inhibit platelet aggregation, and suggest that oxidized LA-containing phospholipids may contribute to the anti-aggregatory effects of glycoxidized HDL and HDL from patients with T2D.

Percutaneous Coronary Intervention Rates and Associated Independent Predictors for Progression of Nontarget Lesions in Patients With Diabetes Mellitus After Drug-Eluting Stent Implantation

Little is known about clinically driven percutaneous coronary intervention (PCI) rates and predictors for progression of nontarget lesions in diabetic patients who have undergone drug-eluting stent (DES) implantation. We retrospectively analyzed the clinical and angiographic data of 2187 diabetic patients undergoing DES implantation. The cumulative rate of nontarget lesion PCI was 6.3% at 1 year, 14.3% at 2 years, and 19.8% at 3 years. The independent predictors of need for clinically driven PCI in patients with diabetes mellitus after DES implantation included obesity (odds ratio [OR] 2.303, 95% confidence interval [CI] 1.657-3.199, P < .001), low levels of high-density lipoprotein cholesterol (OR 1.412, 95% CI 1.114-1.789, P = .004), statin use (OR 0.669, 95% CI 0.454-0.986, P = .042), insulin use (OR 1.310, 95% CI 1.030-1.665, P = .027), and Synergy Between PCI With Taxus and Cardiac Surgery (SYNTAX) score (OR 1.061, 95% CI 1.045-1.077, P < .001) at baseline PCI. These findings may facilitate prediction of the risk of repeat revascularization and improve repeat revascularization rates in diabetic patients after DES implantation.

Epidemiology: disease associations and modulators of HDL-related biomarkers

Epidemiological studies have shown an inverse association between high-density lipoprotein cholesterol (HDL-C) levels and risk of ischemic heart disease. In addition, a low level of HDL-C has been shown to be a risk factor for other diseases not related to atherosclerosis. However, recent studies have not supported a causal effect of HDL-C in the development of atherosclerosis. Furthermore, new drugs markedly elevating HDL-C levels have been disappointing with respect to clinical endpoints. Earlier, most studies have focused almost exclusively on the total HDL-C without regard to the chemical composition or multiple subclasses of HDL particles. Recently, there have been efforts to dissect the HDL fraction into as many well-defined subfractions and individual molecules of HDL particles as possible. On the other hand, the focus is shifting from the structure and composition to the function of HDL particles. Biomarkers and mechanisms that could potentially explain the beneficial characteristics of HDL particles unrelated to their cholesterol content have been sought with sophisticated methods such as proteomics, lipidomics, metabonomics, and function studies including efflux capacity. These new approaches have been used in order to resolve the complex effects of diseases, conditions, environmental factors, and genes in relation to the protective role of HDL but high-throughput methods are still needed for large-scale epidemiological studies.

Elevated CpG island methylation of GCK gene predicts the risk of type 2 diabetes in Chinese males

BACKGROUND

The GCK gene encodes hexokinase 4, which catalyzes the first step in most glucose metabolism pathways. The purpose of our study is to assess the contribution of GCK methylation to type 2 diabetes (T2D).

METHODS AND RESULTS

GCK methylation was evaluated in 48 T2D cases and 48 age- and gender-matched controls using the bisulphite pyrosequencing technology. Among the four CpG sites in the methylation assay, CpG4 and the other three CpGs (CpG1-3) were not in high correlation (r<0.5). Significantly elevated methylation levels of GCK CpG4 methylation were observed in T2D patients than in the healthy controls (P=0.004). A breakdown analysis by gender indicated that the association between CpG4 methylation and T2D was specific to males (P=0.002). It is intriguing that another significant male-specific association was also found between GCK CpG4 methylation and total cholesterol (TC) concentration (r=0.304, P=0.036).

CONCLUSION

Our results showed that elevated GCK CpG4 methylation might suggest a risk of T2D in Chinese males. Gender disparity in GCK CpG4 methylation might provide a clue to elaborate the pathogenesis of T2D.