ABCA1-Labeled Exosomes in Serum Contain Higher MicroRNA-193b Levels in Alzheimer's Disease.

OBJECTIVE: We aimed to establish a method to determine whether microRNA-193b (miR-193b) levels in ABCA1-labeled serum exosomes might serve as a marker for the diagnosis of Alzheimer's disease. METHODS: We used immunocapture methods to determine the levels of ABCA1-labeled exosomal miR-193b in cultures of white blood cells (WBCs), red blood cells (RBCs), mouse hippocampal neuron HT-22 cells, and primary mouse neuronal cells. ABCA1-labeled exosomal miR-193b levels were also evaluated in the cerebrospinal fluid (CSF) and serum of APP/PS1 double-transgenic mice, as well as control subjects (n = 60) and study participants with subjective cognitive decline (SCD, n = 89), stage and mild cognitive impairment (MCI, n = 92), and dementia of the Alzheimer type (DAT, n = 92). RESULTS: ABCA1 levels of exosomes harvested from the medium of HT-22 cells and neurons were significantly higher than those of RBCs and WBCs (P < 0.05). Exosomal ABCA1 from the CSF of APP/PS1 mice were transmitted to the serum of wild-type mice after injection, and high miR-193b levels were observed in both the serum and CSF after injection. The ABCA1-labeled exosomal miR-193b levels were higher in the CSF of MCI and DAT patients compared with the CSF of the control group (P < 0.05). The ABCA1-labeled exosomal miR-193b were also slightly higher (P > 0.05) in the serum of SCD patients and significantly higher in the serum of MCI and DAT patients compared with the serum of the control group (P < 0.05). CONCLUSION: This study provides a method to capture specific exosomes. Detection of serum exosomes labeled with ABCA1 may facilitate the early diagnosis of AD.

The association between impairment of HDL cholesterol efflux capacity and atrial remodeling in atrial fibrillation.

This cross-sectional study enrolled 202 patients with atrial fibrillation (AF) who had undergone catheter ablation and evaluated the association between high-density lipoprotein (HDL) functionality, cholesterol efflux capacity (CEC) of HDL, and the pathophysiology of left atrial structural remodeling. Participants were divided into two groups, based on their left atrial volume index (LAVI) (< 34 mL/m2, n = 60 vs. LAVI ≥ 34 mL/m2, n = 142). We quantified three types of HDL CECs by the presence or absence of cyclic-AMP, as entire, and CEC dependent or not dependent on ATP binding cassette transporter A1 (ABCA1) and termed them Global CEC, ABCA1 CEC, and Non-ABCA1 CEC, respectively. Consequently, Global and Non-ABCA1 CECs were significantly impaired in patients with an enlarged LA (Global CEC: p = 0.039, Non-ABCA1 CEC: p = 0.022). Logistic regression analyses demonstrated that Non-ABCA1 CEC was significantly associated with an enlarged LA after adjusting for the conventional risk factors of AF. Furthermore, the association of higher Non-ABCA1 CEC with an enlarged LA was independent of serum levels of HDL cholesterol and serum myeloperoxidase (Odds ratio of 1 standard deviation higher: 0.64, 95% confidence interval: 0.43-0.95, p = 0.027). The findings of this study indicate the potential contribution of reduced Non-ABCA1 CEC in HDL to the pathophysiology in left atrial structural remodeling of patients with AF.

Reactive Dicarbonyl Scavenging Effectively Reduces MPO-Mediated Oxidation of HDL and Restores PON1 Activity.

Atheroprotective functions of high-density lipoproteins (HDL) are related to the activity of HDL-associated enzymes such as paraoxonase 1 (PON1). We examined the impact of inhibition of myeloperoxidase (MPO)-mediated HDL oxidation by PON1 on HDL malondialdehyde (MDA) content and HDL function. In the presence of PON1, crosslinking of apoAI in response to MPO-mediated oxidation of HDL was abolished, and MDA-HDL adduct levels were decreased. PON1 prevented the impaired cholesterol efflux capacity of MPO-oxidized HDL from Apoe-/- macrophages. Direct modification of HDL with MDA increased apoAI crosslinking and reduced the cholesterol efflux capacity. MDA modification of HDL reduced its anti-inflammatory function compared to native HDL. MDA-HDL also had impaired ability to increase PON1 activity. Importantly, HDL from subjects with familial hypercholesterolemia (FH-HDL) versus controls had increased MDA-apoAI adducts, and PON1 activity was also impaired in FH. Consistently, FH-HDL induced a pro-inflammatory response in Apoe-/- macrophages and had an impaired ability to promote cholesterol efflux. Interestingly, reactive dicarbonyl scavengers, including 2-hydroxybenzylamine (2-HOBA) and pentyl-pyridoxamine (PPM), effectively abolished MPO-mediated apoAI crosslinking, MDA adduct formation, and improved cholesterol efflux capacity. Treatment of hypercholesterolemic mice with reactive dicarbonyl scavengers reduced MDA-HDL adduct formation and increased HDL cholesterol efflux capacity, supporting the therapeutic potential of reactive carbonyl scavenging for improving HDL function.

Shexiang Baoxin Pill Alleviates the Atherosclerotic Lesions in Mice via Improving Inflammation Response and Inhibiting Lipid Accumulation in the Arterial Wall.

Epidemiological studies have demonstrated that cardiovascular diseases (CVDs) are the leading cause of death in the world. Atherosclerosis, a kind of chronic vascular disorder related to multiple pathogenic processes, has been reported to be an underlying cause of CVDs. Shexiang Baoxin Pill (SBP) is a traditional Chinese medicine formulation and has been broadly used for the treatment of CVDs in East Asia. However, whether SBP affects the development of atherosclerosis is poorly understood. The aim of this study was to investigate the antiatherosclerotic roles and relevant mechanisms of SBP in apolipoprotein E knockout mice. Our results showed that SBP treatment markedly decreased the size of atherosclerotic plaques of the entire aorta and the aortic sinus. Biochemical analyses indicated that SBP gavage improved oxidative stress in vivo, as seen by the level elevation of SOD, CAT, and GSH and the level reduction of MDA, H2O2, and MPO. Moreover, the concentration of MCP-1, IFN-γ, and IL-17A was reduced, and the content of IL-10 and TGF-ß1 was increased in the serum from SBP-treated mice. We discovered that the expression levels of inflammatory factors including VCAM-1, ICAM-1, IL-6, and IL-2 in the vascular wall of the SBP group were also decreased in comparison with those of the normal saline group. Moreover, we found that SBP alleviated the activation of inflammation-related pathways in the aorta tissue, as seen by the level elevation of Mfn2 and reduced phosphorylation of p38, JNK, and NF-κB. Furthermore, western blot showed that SBP administration reduced the level of SR-A and LOX-1 and elevated the content of LXRα, ABCA1, and ABCG1 in the arterial wall, indicating that SBP was capable of alleviating lipid influx and facilitating lipid efflux. In conclusion, our data suggested that SBP exerted antiatherosclerotic effects via improving inflammation response and inhibiting lipid accumulation.

MiR­30e and miR­92a are related to atherosclerosis by targeting ABCA1.

Atherosclerosis is a chronic disease characterized by the accumulation of lipids and fibrous elements in the large arteries, which is the principal cause of coronary artery disease. Dysregulated exosomal microRNA (miRNA) levels in serum have been identified in patients with various diseases, including CAD. In the present study, nine candidate miRNAs were detected in the plasma exosome from 42 patients with coronary atherosclerosis, and a higher expression of miR­30e and miR­92a was identified in patients. Following bioinformatics analysis and confirmation through immunoblotting, it was demonstrated that ATP binding cassette (ABC)A1 is a direct target of miR­30e, and miR­92a. Furthermore, a negative correlation was identified between plasma miR­30e and ABCA1, or miR­30e and cholesterol. Thus, the results of the present study suggest that the miR­30e level in exosomes from serum may have the potential to be a novel diagnostic biomarker for coronary atherosclerosis.

High-Density Lipoprotein Particles, Cell-Cholesterol Efflux, and Coronary Heart Disease Risk.

Objective- The cell-cholesterol efflux capacity of HDL (high-density lipoprotein) is inversely associated with coronary heart disease risk. ABCA1 (ATP-binding cassette transporter A1) plays a crucial role in cholesterol efflux from macrophages to preß-1-HDL. We tested the hypothesis that coronary heart disease patients have functionally abnormal preß-1-HDL. Approach and Results- HDL cell-cholesterol efflux capacity via the ABCA1 and the SR-BI (scavenger receptor class B type I) pathways, HDL antioxidative capacity, apo (apolipoprotein) A-I-containing HDL particles, and inflammatory- and oxidative-stress markers were measured in a case-control study of 100 coronary heart disease cases and 100 sex-matched controls. There were significant positive correlations between ABCA1-dependent cholesterol efflux and the levels of small lipid-poor preß-1 particles ( R2=0.535) and between SR-BI-dependent cholesterol efflux and the levels of large lipid-rich (α-1+α-2) HDL particles ( R2=0.712). Cases had significantly higher (87%) preß-1 concentrations than controls, but the functionality of their preß-1 particles (preß-1 concentration normalized ABCA1-dependent efflux capacity) was significantly lower (-31%). Cases had significantly lower (-12%) mean concentration of large HDL particles, but the functionality of their particles (α-1+α-2 concentration normalized SR-BI-dependent efflux capacity) was significantly higher (22%) compared with that of controls. HDL antioxidative capacity was significantly lower (-16%) in cases than in controls. There were no significant correlations between either preß-1 functionality or large HDL particle functionality with HDL antioxidative capacity or the concentrations of inflammatory- and oxidative-stress markers. Conclusions- HDL cell-cholesterol efflux capacity is significantly influenced by both the concentration and the functionality of specific HDL particles participating in cell-cholesterol efflux. Coronary heart disease patients have higher than normal preß-1 concentrations with decreased functionality and lower than normal large HDL particle concentrations with enhanced functionality.

Ground Beef High in Total Fat and Saturated Fatty Acids Decreases X Receptor Signaling Targets in Peripheral Blood Mononuclear Cells of Men and Women.

We hypothesized that consumption of saturated fatty acids in the form of high-fat ground beef for 5 weeks would depress liver X receptor signaling targets in peripheral blood mononuclear cells (PBMC) and that changes in gene expression would be associated with the corresponding changes in lipoprotein cholesterol (C) concentrations. Older men (n = 5, age 68.0 ± 4.6 years) and postmenopausal women (n = 7, age 60.9 ± 3.1 years) were assigned randomly to consume ground-beef containing 18% total fat (18F) or 25% total fat (25F), five patties per week for 5 weeks with an intervening 4-week washout period. The 25F and 18F ground-beef increased (p < 0.05) the intake of saturated fat, monounsaturated fat, palmitic acid, and stearic acid, but the 25F ground-beef increased only the intake of oleic acid (p < 0.05). The ground-beefs 18F and 25F increased the plasma concentration of palmitic acid (p < 0.05) and decreased the plasma concentrations of arachidonic, eicosapentaenoic, and docosahexaenic acids (p < 0.05). The interventions of 18F and 25F ground-beef decreased very low-density lipoprotein C concentrations and increased particle diameters and low-density lipoprotein (LDL)-I-C and LDL-II-C concentrations (p < 0.05). The ground-beef 25F decreased PBMC mRNA levels for the adenosine triphosphate (ATP) binding cassette A, ATP binding cassette G1, sterol regulatory element binding protein-1, and LDL receptor (LDLR) (p < 0.05). The ground-beef 18F increased mRNA levels for stearoyl-CoA desaturase-1 (p < 0.05). We conclude that the increased LDL particle size and LDL-I-C and LDL-II-C concentrations following the 25F ground-beef intervention may have been caused by decreased hepatic LDLR gene expression.

Differences in ABCA1 R219K Polymorphisms and Serum Indexes in Alzheimer and Parkinson Diseases in Northern China.

BACKGROUND ABCA1 R219K single-nucleotide polymorphisms (SNPs) was related to Alzheimer disease (AD) but not Parkinson disease (PD). Here, we analyzed the associations among ABCA1 R219K distribution, serum biomarkers, AD, and PD in a population in northern China. MATERIAL AND METHODS We used the Mini-Mental State Examination (MMSE) and the Hoehn and Yahr scale (H-Y) to evaluate AD and PD progression, separately. ABCA1 R219K was analyzed by matrix-assisted laser desorption ionization time of flight time mass spectrometry (MALDI-TOF-MS). Serum indexes were determined by enzyme-linked immunosorbent assay (ELISA). RESULTS ABCA1 R219K RR+RK genotype frequency in AD and PD patients was lower than that in normal controls (NC), while ABCA1 R219K KK genotype frequency was significantly higher. ABCA1 R219K RR genotype frequency in AD patients and NC was lower than that in PD patients, while ABCA1 R219K RK+KK genotype frequency was significantly higher. ABCA1 R219K RR genotype was positively correlated to MMSE value in AD patients, while ABCA1 R219K KK genotype was negatively correlated to H-Y value in PD patients. Serum factors were significantly different among AD and PD patients and NC. Serum ABCA1, ApoA1, ApoA2, ApoB, HDL, TC, IL-1ß, IL-6, and TNF-α were significantly different between AD and PD patients. CONCLUSIONS ABCA1 R219K R allele was the risk factor inducing abnormal serum levels of ApoA2, LDL, and TG in AD patients, and abnormal levels of serum ABCA1, HDL, IL-1b, IL-6, and TNF-α in PD patients, while ABCA1 R219K K allele was the risk factor inducing lower ABCA1 in AD patients. IL-1ß, IL-6, and TNF-α were negatively correlated to MMSE in AD patients but positively correlated to H-Y in PD patients, while HDL was positively related to H-Y in PD patients.

Pre-ß1 HDL in type 2 diabetes mellitus.

BACKGROUND AND AIMS: Pre-ß1 HDL, being a major acceptor of free cholesterol from cells, plays an important role in reverse cholesterol transport. This study was performed to determine whether abnormalities in pre-ß1 HDL concentration were present in type 2 diabetes irrespective of their HDL-cholesterol levels, and the impact on cholesterol efflux. METHODS: 640 type 2 diabetic patients with or without cardiovascular disease (CVD) and 360 non-diabetic controls matched for serum HDL-cholesterol levels were recruited. Plasma pre-ß1 HDL was measured by ELISA, and cholesterol efflux to serum, mediated by ATP-binding cassette transporter A1 (ABCA1), was determined by measuring the transfer of [3H]cholesterol from cultured cells expressing ABCA1 to the medium containing the tested serum. RESULTS: Despite the diabetic subjects having matched HDL-cholesterol and total apoA1 as controls, plasma pre-ß1 HDL was significantly reduced in both male (p < 0.01) and female diabetic patients (p < 0.05), and patients with CVD had the lowest pre-ß1 HDL level. Serum capacity to induce ABCA1-mediated cholesterol efflux was impaired in the diabetic group (p < 0.01) and cholesterol efflux correlated with pre-ß1 HDL (Pearson's r = 0.38, p < 0.01), and this association remained significantly even after controlling for age, gender, body mass index, diabetes status, smoking, apoA1, triglyceride and LDL. CONCLUSIONS: Plasma pre-ß1 HDL level was significantly decreased in type 2 diabetes and was associated with a reduction in cholesterol efflux mediated by ABCA1. Our data would suggest that low pre-ß1 HDL might cause impairment in reverse cholesterol transport in type 2 diabetes.

Analysis of Serum Cholesterol Efflux Capacity in a Minipig Model of Nonischemic Heart Failure.

AIM: Circulating levels of high-density lipoprotein cholesterol (HDL-C) are decreased in patients with heart failure (HF). We tested whether HDL-C serum levels are associated with cardiac contractile dysfunction in a minipig HF model. METHODS: Blood samples were collected from 13 adult male minipigs: 1) before pacemaker implantation, 2) 10 days after surgery, and 3) 3 weeks after high-rate LV pacing. Serum cholesterol efflux capacity (CEC), an index of HDL functionality, was assessed through four mechanisms: ATP Binding Cassette transporter A1 (ABCA1), ATP Binding Cassette transporter G1 (ABCG1), Scavenger Receptor-Class B Type I (SR-BI) and Passive Diffusion (PD). RESULTS: HDL-C serum levels significantly decrease in minipigs with HF compared with baseline (p＜0.0001). Serum CEC mediated by PD and SR-BI, but not ABCA1 or ABCG1, significantly decrease in animals with HF (p＜0.05 and p＜0.005, respectively). DISCUSSION: HDL-C serum levels and partial serum CEC reduction may play a pathophysiological role in the cardiac function decay sustained by high-rate LV pacing, opening new avenues to understand of the pathogenesis of nonischemic myocardial remodeling.

Cholesterol Efflux Capacity and Subclasses of HDL Particles in Healthy Women Transitioning Through Menopause.

CONTEXT: Growing evidence challenges the concept that high-density lipoprotein-cholesterol (HDL-C) is cardioprotective after menopause. HDL particle concentration (HDL-P) and cholesterol efflux capacity (CEC) might be better predictors of cardiovascular risk. OBJECTIVE: Quantify alterations in HDL-P and CEC during menopause, correlating those changes with alterations in estradiol (E2) and FSH. DESIGN: Longitudinal study of HDL metrics before and after menopause as indexed by the final menstrual period (FMP). PARTICIPANTS: Forty-six women, mean baseline age 47.1 years, 33% black, 67% white. MAIN OUTCOMES AND MEASURES: HDL-P concentration (HDL-PIMA) by calibrated ion mobility analysis (IMA); macrophage CEC with cAMP-stimulated macrophages; ATP-binding cassette transporter A1 (ABCA1)-specific CEC with BHK cells expressing human ABCA1. RESULTS: After a median of 2.1 years since FMP, both HDL-C (P = .03) and HDL-PIMA (P = .01) increased, with a selective increase in large HDL-PIMA (P = .01), whereas sizes of medium and small HDL-PIMA were decreased (P < .05). These changes were independent of race, body mass index, and time difference. Macrophage CEC and ABCA1-specific CEC increased after FMP (both P < .001). Greater declines in E2 correlated with larger increases in small HDL-PIMA (P = .01), whereas greater increases in FSH associated with greater reductions in the size of medium HDL-PIMA (P = .04). Macrophage CEC and ABCA1-specific CEC correlated positively with E2 levels only before menopause (P = .04 and .009, respectively). CONCLUSIONS: Large HDL-PIMA and CEC increased significantly in the early phase of the menopausal transition. Whether patterns of these alterations differ in late postmenopause is unknown. Further exploration is needed to assess that and to determine whether the reported changes in HDL metrics associate with increased cardiovascular risk after menopause.

ATP-binding cassette transporter 1 (ABCA1) deficiency decreases platelet reactivity and reduces thromboxane A2 production independently of hematopoietic ABCA1.

UNLABELLED: ESSENTIALS: The role of ATP-binding cassette transporter 1 (ABCA1) in platelet functions is poorly characterized. We studied the impact of ABCA1 deficiency on platelet responses in a mouse model and two Tangier patients. ABCA1-deficient platelets exhibit reduced positive feedback loop mechanisms. This reduced reactivity is dependent on external environment and independent of hematopoietic ABCA1. BACKGROUND: The ATP-binding cassette transporter ABCA1 is required for the conversion of apolipoprotein A-1 to high-density lipoprotein (HDL), and its defect causes Tangier disease, a rare disorder characterized by an absence of HDL and accumulation of cholesterol in peripheral tissues. The role of ABCA1 in platelet functions remains poorly characterized. OBJECTIVE: To determine the role of ABCA1 in platelet functions and to clarify controversies concerning its implication in processes as fundamental as platelet phosphatidylserine exposure and control of platelet membrane lipid composition. METHODS AND RESULTS: We studied the impact of ABCA1 deficiency on platelet responses in a mouse model and in two Tangier patients. We show that platelets in ABCA1-deficient mice are slightly larger in size and exhibit aggregation and secretion defects in response to low concentrations of thrombin and collagen. These platelets have normal cholesterol and major phospholipid composition, granule morphology, or calcium-induced phosphatidylserine exposure. Interestingly, ABCA1-deficient platelets display a reduction in positive feedback loop mechanisms, particularly in thromboxane A2 (TXA2) production. Hematopoietic chimera mice demonstrated that defective eicosanoids production, particularly TXA2, was primarily dependent on external environment and not on the hematopoietic ABCA1. Decreased aggregation and production of TXA2 and eicosanoids were also observed in platelets from Tangier patients. CONCLUSIONS: Absence of ABCA1 and low HDL level induce reduction of platelet reactivity by decreasing positive feedback loops, particularly TXA2 production through a hematopoietic ABCA1-independent mechanism.

Hematopoietic ABCA1 deletion promotes monocytosis and worsens diet-induced insulin resistance in mice.

Low-grade chronic inflammation plays an important role in the pathogenesis of obesity-induced insulin resistance. ABCA1 is essential for reverse cholesterol transport and HDL synthesis, and protects against macrophage inflammation. In the present study, the effects of ABCA1 deficiency in hematopoietic cells on diet-induced inflammation and insulin resistance were tested in vivo using bone marrow transplanted (BMT)-WT and BMT-ABCA1(-/-) mice. When challenged with a high-fat high-carbohydrate diabetogenic diet with added cholesterol (HFHSC), BMT-ABCA1(-/-) mice displayed enhanced insulin resistance and impaired glucose tolerance as compared with BMT-WT mice. The worsened insulin resistance and impaired glucose tolerance in BMT-ABCA1(-/-) mice were accompanied by increased macrophage accumulation and inflammation in adipose tissue and liver. Moreover, BMT-ABCA1(-/-) mice had significantly higher hematopoietic stem cell proliferation, myeloid cell expansion, and monocytosis when challenged with the HFHSC diet. In vitro studies indicated that macrophages from ABCA1(-/-) mice showed significantly increased inflammatory responses induced by saturated fatty acids. Taken together, these studies point to an important role for hematopoietic ABCA1 in modulating a feed-forward mechanism in obesity such that inflamed tissue macrophages stimulate the production of more monocytes, leading to an exacerbation of inflammation and associated disease processes.

HDL-Mediated Cellular Cholesterol Efflux Assay Method.

Biomarkers of high-density lipoprotein (HDL) function may provide mechanistic insights and better cardiovascular risk discrimination than HDL-cholesterol mass. The purpose of this work is to describe a simplified experimental protocol that can be used in the determination of cholesterol efflux from macrophages cultured cells and be brought to a medium throughput volume. The cellular cholesterol efflux assay is designed to quantify the rate of cholesterol efflux from cultured cells to an acceptor particle or to plasma. This assay is multi step, cell based assay. Various factors, if not carefully controlled may influence the accuracy and reproducibility of the assay. Attempts were made to address factors influencing this assay and to provide a standardized method that is relatively rapid and scalable. We demonstrate that further centrifugation of the HDL fraction is necessary to avoid apolipoprotein B contamination when using polyethylene glycol (PEG) method. We demonstrate also no effect on cholesterol efflux efficiency when using PEG with plasma or serum. This method has been previously applied in our laboratory in context of cardiovascular research, cardiovascular disease and pharmacologic therapies.

HDL-apolipoprotein A-I exchange is independently associated with cholesterol efflux capacity.

HDL is the primary mediator of cholesterol mobilization from the periphery to the liver via reverse cholesterol transport (RCT). A critical first step in this process is the uptake of cholesterol from lipid-loaded macrophages by HDL, a function of HDL inversely associated with prevalent and incident cardiovascular disease. We hypothesized that the dynamic ability of HDL to undergo remodeling and exchange of apoA-I is an important and potentially rate-limiting aspect of RCT. In this study, we investigated the relationship between HDL-apoA-I exchange (HAE) and serum HDL cholesterol (HDL-C) efflux capacity. We compared HAE to the total and ABCA1-specific cholesterol efflux capacity of 77 subjects. We found that HAE was highly correlated with both total (r = 0.69, P < 0.0001) and ABCA1-specific (r = 0.47, P < 0.0001) efflux, and this relationship remained significant after adjustment for HDL-C or apoA-I. Multivariate models of sterol efflux capacity indicated that HAE accounted for approximately 25% of the model variance for both total and ABCA1-specific efflux. We conclude that the ability of HDL to exchange apoA-I and remodel, as measured by HAE, is a significant contributor to serum HDL efflux capacity, independent of HDL-C and apoA-I, indicating that HDL dynamics are an important factor in cholesterol efflux capacity and likely RCT.

Association between the ABCA1-565C/T gene promoter polymorphism and coronary heart disease severity and cholesterol efflux in the Chinese Han population.

BACKGROUND: ABCA1 -565C/T gene promoter variants have been associated with the severity of coronary artery disease in Western populations. The purpose of our study was to investigate the association between the -565C/T gene polymorphism and coronary artery disease severity and cholesterol efflux in the Chinese Han population. METHODS: A cohort of 298 acute coronary syndrome (ACS) patients and 541 healthy controls was genotyped using the highly sensitive ligase detection reaction. ABCA1 -565C/T genotype was correlated with the clinical features of 164 acute myocardial infarction (AMI) patients. Monocytes from patients with various -565C/T gene polymorphisms were isolated and differentiated into foam cells by coincubation with [(3)H]-labeled acetyl-low-density lipoprotein cholesterol. ABCA1 mRNA and protein expression levels were evaluated, as well as cellular cholesterol efflux. RESULTS: The frequency of the TT genotype in the -565C/T polymorphism of ACS patients was significantly increased when compared with controls (0.211 vs. 0.162, p<0.05). The TT genotype, but not the CT or CC genotypes, in the -565C/T gene polymorphism correlated with the severity of the coronary lesion observed in AMI patients. Patients with the TT homozygote genotype also exhibited significantly lower cellular cholesterol efflux (TT [6.37%±0.554%]) levels than controls and also had the lowest levels of ABCA1 mRNA and protein expression among the group of variants. In contrast, cholesterol efflux levels in AMI patients with CT [11.35%±3.975%] and CC ([15.32%±6.293%]) genotypes were not significantly different from controls. CONCLUSIONS: Impaired ABCA1-mediated cholesterol efflux in macrophages may be associated with the severity of the coronary lesions in AMI patients with the TT genotype at the -565C/T gene polymorphism.

miR-28-5p Involved in LXR-ABCA1 Pathway is Increased in the Plasma of Unstable Angina Patients.

BACKGROUND: Previous studies confirmed that the intronic miRNAs participated in regulating host gene-primed biological processes. The coordinated roles of miR-28 with its host gene, LIM domain lipoma-preferred partner (LPP), remain unknown in atherosclerosis. METHODS: In this study, we determined to assess circulating levels of miR-28-5p in unstable angina patients, compared with age- and sex- matched control subjects by quantitative PCR. Furthermore, we attempted to explore whether miR-28-5p could influence the expression of ATP-binding cassette transporter A1 (ABCA1) and liver X receptor (LXR), major mediators of high density lipoprotein (HDL) synthesis and transportation in hepatic cells and macrophages. RESULTS: It was found that plasma levels of miR-28-5p were significantly increased in unstable angina patients with or without type 2 diabetes mellitus. Notably, miR-28-5p upregulated ABCA1 expression at transcription and translation levels, strongly correlated with translational activation of LXRα in HepG2 and THP-1-derived macrophages. CONCLUSIONS: Our findings suggest that circulating miR-28-5p, involved in LXRα-ABCA1 pathway, may be a potential biomarker for diagnosis and prognosis of unstable angina.

Chlorogenic acid protects against atherosclerosis in ApoE-/- mice and promotes cholesterol efflux from RAW264.7 macrophages.

Chlorogenic acid (CGA) is one of the most abundant polyphenols in the human diet and is suggested to be a potential antiatherosclerotic agent due to its proposed hypolipidemic, anti-inflammatory and antioxidative properties. The aim of this study was to evaluate the effect of CGA on atherosclerosis development in ApoE(-/-) mice and its potential mechanism. ApoE(-/-) mice were fed a cholesterol-rich diet without (control) or with CGA (200 and 400 mg/kg) or atorvastatin (4 mg/kg) for 12 weeks. During the study plasma lipid and inflammatory parameters were determined. Treatment with CGA (400 mg/kg) reduced atherosclerotic lesion area and vascular dilatation in the aortic root, comparable to atorvastatin. CGA (400 mg/kg) also significantly decreased plasma levels of total cholesterol, triglycerides and low-density lipoprotein-cholesterol as well as inflammatory markers. Supplementation with CGA or CGA metabolites-containing serum suppressed oxidized low-density lipoprotein (oxLDL)-induced lipid accumulation and stimulated cholesterol efflux from RAW264.7 cells. CGA significantly increased the mRNA levels of PPARγ, LXRα, ABCA1 and ABCG1 as well as the transcriptional activity of PPARγ. Cholesterol efflux assay showed that three major metabolites, caffeic, ferulic and gallic acids, significantly stimulated cholesterol efflux from RAW264.7 cells. These results suggest that CGA potently reduces atherosclerosis development in ApoE(-/-) mice and promotes cholesterol efflux from RAW264.7 macrophages. Caffeic, ferulic and gallic acids may be the potential active compounds accounting for the in vivo effect of CGA.

Lower Apo A-I and lower HDL-C levels are associated with higher intermediate CD14++CD16+ monocyte counts that predict cardiovascular events in chronic kidney disease.

OBJECTIVE: Patients with chronic kidney disease (CKD) display impaired cholesterol efflux capacity and elevated CD14(++)CD16(+) monocyte counts. In mice, dysfunctional cholesterol efflux causes monocytosis. It is unknown whether cholesterol efflux capacity and monocyte subsets are associated in CKD. APPROACH AND RESULTS: In 438 patients with CKD, mediators of cholesterol efflux capacity (high-density lipoprotein cholesterol/apolipoprotein A-I) and monocyte subsets were analyzed as predictors of cardiovascular events. Monocyte subset-specific intracellular lipid content, CD36, CD68, and ABCA1 were measured in a subgroup. Experimentally, we analyzed subset-specific cholesterol efflux capacity and response to oxidized low-density lipoprotein cholesterol stimulation in CKD. Epidemiologically, both low Apo-I and low high-density lipoprotein cholesterol were associated with high CD14(++)CD16(+) monocyte counts in linear regression analyses (apolipoprotein A-I: ß=-0.171; P<0.001; high-density lipoprotein cholesterol: ß=-0.138; P=0.005), but not with counts of other monocyte subsets. In contrast to apolipoprotein A-I or high-density lipoprotein cholesterol, higher CD14(++)CD16(+) monocyte counts independently predicted cardiovascular events (hazard ratio per increase of 1 cell/µL: 1.011 [1.003-1.020]; P=0.007). Experimentally, CD14(++)CD16(+) monocytes demonstrated preferential lipid accumulation, high CD36, CD68, and low ABCA1 expression and, consequently, displayed low cholesterol efflux capacity, avid oxidized low-density lipoprotein cholesterol uptake, and potent intracellular interleukin-6, interleukin-1ß, and tumor necrosis factor-α production. CONCLUSIONS: Taken together, mediators of cholesterol efflux are associated with CD14(++)CD16(+) monocyte counts, which independently predict adverse outcome in CKD.

Cardiometabolic and immune factors associated with increased common carotid artery intima-media thickness and cardiovascular disease in patients with systemic lupus erythematosus.

BACKGROUND AND AIM: Patients with systemic lupus erythematosus (SLE) have a higher prevalence of subclinical atherosclerosis and higher risk of cardiovascular (CV) events compared to the general population. The relative contribution of CV-, immune- and disease-related risk factors to accelerated atherogenesis in SLE is unclear. METHODS AND RESULTS: Fifty SLE patients with long-lasting disease (mean age 44 ± 10 years, 86% female) and 50 sex- and age-matched control subjects were studied. Common carotid artery intima-media thickness (CCA-IMT) was used as a surrogate marker of atherosclerosis. We evaluated traditional and immune- and disease-related factors, assessed multiple T-cell subsets by 10-parameter-eight-colour polychromatic flow cytometry and addressed the effect of pharmacological therapies on CCA-IMT. In SLE patients, among several cardiometabolic risk factors, only high-density lipoprotein levels (HDL) and their adenosine triphosphate-binding cassette transporter 1 (ABCA-1)-dependent cholesterol efflux capacity were markedly reduced (p < 0.01), whereas the CCA-IMT was significantly increased (p = 0.03) compared to controls. CCA-IMT correlated with systolic blood pressure, low-density lipoprotein (LDL) cholesterol and body mass index (BMI), but not with disease activity and duration. The activated CD4(+)HLA-DR(+) and CCR5(+) T-cell subsets were expanded in SLE patients. Patients under hydroxychloroquine (HCQ) therapy showed lower CCA-IMT (0.62 ± 0.08 vs. 0.68 ± 0.10 mm; p = 0.03) and better risk-factor profile and presented reduced circulating pro-atherogenic effector memory T-cell subsets and a parallel increased percentage of naïve T-cell subsets. CONCLUSION: HDL represents the main metabolic parameter altered in SLE patients. The increased CCA-IMT in SLE patients may represent the net result of a process in which 'classic' CV risk factors give a continuous contribution, together with immunological factors (CD4(+)HLA-DR(+) T cells) which, on the contrary, could contribute through flares of activity of various degrees over time. Patients under HCQ therapy present a modified metabolic profile, a reduced T-cell activation associated with decreased subclinical atherosclerosis.