High-density lipoproteins: a new potential therapeutic target for the prevention of cardiovascular disease

Insulin Downregulates the Expression of ATP-binding Cassette Transporter A-I in Human Hepatoma Cell Line HepG2 in a FOXO1 and LXR Dependent Manner

ATP-binding cassette transporter A-I (ABCA1) is an ubiquitously expressed protein whose main function is the transmembrane transport of cholesterol and phospholipids. Synthesis of ABCA1 protein in liver is necessary for high-density lipoprotein (HDL) formation in mammals. Thus, the mechanism of ABCA1 gene expression regulation in hepatocytes are of critical importance. Recently, we have found the insulin-dependent downregulation of other key player in the HDL formation-apolipoprotein A-I gene (J. Cell. Biochem., 2017, 118:382-396). Nothing is known about the role of insulin in the regulation of ABCA1 gene. Here we show for the first time that insulin decreases the mRNA and protein levels of ABCA1 in human hepatoma cell line HepG2. PI3K, p38, MEK1/2, JNK and mTORC1 signaling pathways are involved in the insulin-mediated downregulation of human ABCA1 gene. Transcription factors LXRα, LXRβ, FOXO1 and NF-κB are important contributors to this process, while FOXA2 does not regulate ABCA1 gene expression. Insulin causes the decrease in FOXO1, LXRα and LXRβ binding to ABCA1 promoter, which is likely the cause of the decrease in the gene expression. Interestingly, the murine ABCA1 gene seems to be not regulated by insulin in hepatocytes (in vitro and in vivo). We suggest that the reason for this discrepancy is the difference in the 5'-regulatory regions of human and murine ABCA1 genes.

A Study on Multiple Facets of Apolipoprotein A1 Milano

For several strategies formulated to prevent atherosclerosis, Apolipoprotein A1 Milano (ApoA1M) remains a prime target. ApoA1M has been reported to have greater efficiency in reducing the incidence of coronary artery diseases. Furthermore, recombinant ApoA1M based mimetic peptide exhibits comparatively greater atheroprotective potential, offers a hope in reducing the burden of atherosclerosis in in vivo model system. The aim of this review is to emphasize on some of the observed ApoA1M structural and functional effects that are clinically and therapeutically meaningful that might converge on the basic role of ApoA1M in reducing the chances of glycation assisted ailments in diabetes. We also hypothesize that the nonenzymatic glycation prone arginine amino acid of ApoA1 gets replaced with cysteine residue and the rate of ApoA1 glycation may decrease due to change substitution of amino acid. Therefore, to circumvent the effect of ApoA1M glycation, the related mechanism should be explored at the cellular and functional levels, especially in respective experimental disease model in vivo.

HDL and Cholesterol Ester Transfer Protein (CETP)

Cholesterol ester transfer protein (CETP) is important clinically and is one of the major targets in cardiovascular disease studies. With high conformational flexibility, its tunnel structure allows unforced movement of high-density lipoproteins (HDLs), VLDLs, and LDLs. Research in reverse cholesterol transports (RCT) reveals that the regulation of CETP activity can change the concentration of cholesteryl esters (CE) in HDLs, VLDLs, and LDLs. These molecular insights demonstrate the mechanisms of CETP activities and manifest the correlation between CETP and HDL. However, animal and cell experiments focused on CETP give controversial results. Inhibiting CETP is found to be beneficial to anti-atherosclerosis in terms of increasing plasma HDL-C, while it is also claimed that CETP weakens atherosclerosis formation by promoting RCT. Currently, the CETP-related drugs are still immature. Research on CETP inhibitors is targeted at improving efficacy and minimizing adverse reactions. As for CETP agonists, research has proved that they also can be used to resist atherosclerosis.

Genes in human obesity loci are causal obesity genes in C. elegans

Obesity and its associated metabolic syndrome are a leading cause of morbidity and mortality. Given the disease's heavy burden on patients and the healthcare system, there has been increased interest in identifying pharmacological targets for the treatment and prevention of obesity. Towards this end, genome-wide association studies (GWAS) have identified hundreds of human genetic variants associated with obesity. The next challenge is to experimentally define which of these variants are causally linked to obesity, and could therefore become targets for the treatment or prevention of obesity. Here we employ high-throughput in vivo RNAi screening to test for causality 293 C. elegans orthologs of human obesity-candidate genes reported in GWAS. We RNAi screened these 293 genes in C. elegans subject to two different feeding regimens: (1) regular diet, and (2) high-fructose diet, which we developed and present here as an invertebrate model of diet-induced obesity (DIO). We report 14 genes that promote obesity and 3 genes that prevent DIO when silenced in C. elegans. Further, we show that knock-down of the 3 DIO genes not only prevents excessive fat accumulation in primary and ectopic fat depots but also improves the health and extends the lifespan of C. elegans overconsuming fructose. Importantly, the direction of the association between expression variants in these loci and obesity in mice and humans matches the phenotypic outcome of the loss-of-function of the C. elegans ortholog genes, supporting the notion that some of these genes would be causally linked to obesity across phylogeny. Therefore, in addition to defining causality for several genes so far merely correlated with obesity, this study demonstrates the value of model systems compatible with in vivo high-throughput genetic screening to causally link GWAS gene candidates to human diseases.

Forty-eight weeks of statin therapy for type 2 diabetes mellitus patients with lower extremity atherosclerotic disease: Comparison of the effects of pitavastatin and atorvastatin on lower femoral total plaque areas

AIMS/INTRODUCTION

Type 2 diabetes mellitus is correlated with systemic atherosclerosis. Statin therapies have been proved to reduce low-density lipoprotein cholesterol (LDL-C) level, protecting type 2 diabetes mellitus patients from cardiovascular events. Recently, more interest has been focused on the regression of lower extremity atherosclerotic disease (LEAD) for the potential prevention of amputation. However, the effects of pitavastatin and atorvastatin on LEAD in type 2 diabetes mellitus patients have not been directly compared.

MATERIALS AND METHODS

This study compared the effects of pitavastatin and atorvastatin on femoral total plaque areas (FTPA), and lipids and glucose metabolism in type 2 diabetes mellitus patients with elevated LDL-C level and LEAD. Type 2 diabetes mellitus patients with LDL-C level >2.6 mmol/L and LEAD were randomly assigned to receive either pitavastatin 2 mg/day or atorvastatin 10 mg/day for 48 weeks. FTPA were measured at baseline and the end of the study. Levels of glucose and lipids profile were measured periodically. The efficacy was evaluated in 63 patients.

RESULTS

The percentage change in FTPA measurements was similar between the pitavastatin group and atorvastatin group (-17.79 ± 21.27% vs -14.34 ± 16.33%), as were the changes in LDL-C (-44.0 ± 18.0% vs -40.3 ± 18.2%) and triglyceride (17.6 ± 20.0% vs 16.2 ± 17.0%). However, the level of high-density lipoprotein cholesterol was significantly higher in the pitavastatin group compared with the atorvastatin group after 48 weeks of treatment (12.9 ± 10.3% vs 7.2 ± 11.7%, P < 0.05). There were no significant differences between groups for the measurements of glucose metabolism.

CONCLUSION

In type 2 diabetes mellitus patients with elevated LDL-C level and LEAD, 48 weeks of treatment with either pitavastatin or atorvastatin was associated with significant regression of FTPA. Pitavastatin treatment resulted in a significantly higher high-density lipoprotein cholesterol level compared with atorvastatin treatment.

OX-HDL: A Starring Role in Cardiorenal Syndrome and the Effects of Heme Oxygenase-1 Intervention

In this review, we will evaluate how high-density lipoprotein (HDL) and the reverse cholesterol transport (RCT) pathway are critical for proper cardiovascular-renal physiology. We will begin by reviewing the basic concepts of HDL cholesterol synthesis and pathway regulation, followed by cardiorenal syndrome (CRS) pathophysiology. After explaining how the HDL and RCT pathways become dysfunctional through oxidative processes, we will elaborate on the potential role of HDL dysfunction in CRS. We will then present findings on how HDL function and the inducible antioxidant gene heme oxygenase-1 (HO-1) are interconnected and how induction of HO-1 is protective against HDL dysfunction and important for the proper functioning of the cardiovascular-renal system. This will substantiate the proposal of HO-1 as a novel therapeutic target to prevent HDL dysfunction and, consequently, cardiovascular disease, renal dysfunction, and the onset of CRS.

Macrophage polarisation associated with atherosclerosis differentially affects their capacity to handle lipids

BACKGROUND AND AIMS

Lipid-rich foam cell macrophages drive atherosclerosis via several mechanisms, including inflammation, lipid uptake, lipid deposition and plaque vulnerability. The atheroma environment shapes macrophage function and phenotype; anti-inflammatory macrophages improve plaque stability while pro-inflammatory macrophages promote rupture. Current evidence suggests a variety of macrophage phenotypes occur in atherosclerotic plaques with local lipids, cytokines, oxidised phospholipids and pathogenic stimuli altering their phenotype. In this study, we addressed differential functioning of macrophage phenotypes via a systematic analysis of in vitro polarised, human monocyte-derived macrophage phenotypes, focussing on molecular events that regulate foam-cell formation.

METHODS

We examined transcriptomes, protein levels and functionally determined lipid handling and foam cell formation capacity in macrophages polarised with IFNγ+LPS, IL-4, IL-10, oxPAPC and CXCL4.

RESULTS

RNA sequencing of differentially polarised macrophages revealed distinct gene expression changes, with enrichment in atherosclerosis and lipid-associated pathways. Analysis of lipid processing activity showed IL-4 and IL-10 macrophages have higher lipid uptake and foam cell formation activities, while inflammatory and oxPAPC macrophages displayed lower foam cell formation. Inflammatory macrophages showed low lipid uptake, while higher lipid uptake in oxPAPC macrophages was matched by increased lipid efflux capacity.

CONCLUSIONS

Atherosclerosis-associated macrophage polarisation dramatically affects lipid handling capacity underpinned by major transcriptomic changes and altered protein levels in lipid-handling gene expression. This leads to phenotype-specific differences in LDL uptake, cellular cholesterol levels and cholesterol efflux, informing how the plaque environment influences atherosclerosis progression by influencing macrophage phenotypes.

Targeting Foam Cell Formation in Atherosclerosis: Therapeutic Potential of Natural Products

Foam cell formation and further accumulation in the subendothelial space of the vascular wall is a hallmark of atherosclerotic lesions. Targeting foam cell formation in the atherosclerotic lesions can be a promising approach to treat and prevent atherosclerosis. The formation of foam cells is determined by the balanced effects of three major interrelated biologic processes, including lipid uptake, cholesterol esterification, and cholesterol efflux. Natural products are a promising source for new lead structures. Multiple natural products and pharmaceutical agents can inhibit foam cell formation and thus exhibit antiatherosclerotic capacity by suppressing lipid uptake, cholesterol esterification, and/or promoting cholesterol ester hydrolysis and cholesterol efflux. This review summarizes recent findings on these three biologic processes and natural products with demonstrated potential to target such processes. Discussed also are potential future directions for studying the mechanisms of foam cell formation and the development of foam cell-targeted therapeutic strategies.

Anti-obesity effects of pectinase and cellulase enzyme‑treated Ecklonia cava extract in high‑fat diet‑fed C57BL/6N mice

The present study investigated the anti‑obesity effects of enzyme‑treated Ecklonia cava extract (EEc) in C57BL/6N mice with high‑fat diet (HFD)‑induced obesity. The EEc was separated and purified with the digestive enzymes pectinase (Rapidase X‑Press L) and cellulase (Rohament CL) and its effects on the progression of HFD‑induced obesity were examined over 10 weeks. The mice were divided into 6 groups (n=10/group) as follows: Normal diet group, HFD group, mice fed a HFD with 25 mg/kg/day Garcinia cambogia extract and mice fed a HFD with 5, 25 or 150 mg/kg/day EEc (EHD groups). Changes in body weight, fat, serum lipid levels and lipogenic enzyme levels were determined. The body weight and liver weight were increased in the HFD group compared with those in the ND group, which was significantly reduced by EEc supplementation. In addition, significant reductions in epididymal, perirenal and mesenteric white adipose tissues were present in the EHD groups and all three EHD groups exhibited decreases in insulin, leptin and glutamate pyruvate transaminase levels compared with those in the HFD group. In addition, EEc treatment significantly decreased the serum and hepatic triglyceride levels compared with those in the HFD group. However, the levels of high‑density lipoprotein cholesterol/total cholesterol ration increased significantly in EHD‑25 and ‑150 groups compared with those in the HFD group. Changes in adipogenic and lipogenic protein expression in the liver was assessed by western blot analysis. The EHD‑25 and -150 groups exhibited reduced levels of CCAAT/enhancer‑binding protein α and peroxisome proliferator activated receptor γ. However, the phosphorylation ratios of AMP‑activated protein kinase and acetyl‑CoA carboxylase were significantly increased in the liver tissue obtained from the EHD (5, ‑25 and ‑150 mg/kg/day) groups compared with those in the HFD group. EEc supplementation reduced levels of sterol regulatory element‑binding protein‑1c, adipose fatty acid‑binding protein, fatty acid synthase and leptin, while it significantly increased glucose transporter type 4 and adiponectin protein levels in the liver tissues of all three EHD groups compared with those in the HFD group. Taken together, these results suggest that EEc exerts anti‑obesity effects by reducing body weight and the serum and hepatic levels of obesity‑associated factors. Thus, EEc supplementation reduces HFD‑induced obesity in C57BL/6N mice and has the potential to prevent obesity and subsequent metabolic disorders.

Cheonggukjang, a soybean paste fermented with B. licheniformis-67 prevents weight gain and improves glycemic control in high fat diet induced obese mice

In this study, we investigated the anti-obesity effects of soybean paste—Cheonggukjang, fermented with poly gamma glutamic acid producing Bacillus licheniformis-67 in diet induced obese C57BL/6J mice. Forty male C57BL/6J mice aged 4 weeks were divided into four dietary groups; normal diet control, high fat diet control, high fat diet containing 30% of unfermented soybean and high fat diet containing 30% Cheonggukjang fermented with Bacillus licheniformis-67. After 13 weeks of dietary intervention the mice were sacrificed; serum and tissue samples were examined. Serum and hepatic lipid profile, blood glucose, insulin, leptin level were lower (<0.05) along with the body weight and epididymal fat pad weight in the 30% Cheonggukjang supplemented group compared with the high fat diet control group. The expression level of lipid anabolic gene was significantly decreased; whereas the expression level of lipid catabolic genes were significantly increased in the 30% Cheonggukjang supplemented group compared to the high fat diet control group. Collectively, these results suggested that intake of Cheonggukjang fermented with Bacillus licheniformis-67 significantly prevents obesity related parameters.

Evidence that periodontal treatment improves biomarkers and CVD outcomes

AIM

The aim of this review was to critically appraise the evidence on the impact of periodontal treatment of cardiovascular diseases (CVDs) biomarkers and outcomes.

METHODS

A systematic search was performed in Cinhal, Cochrane, Embase and Medline for relevant articles up to July 2012. Duplicate screening and reference hand searching were performed. Data were then summarized and evidence graded in tables.

RESULTS

The search resulted in: (a) no evidence on the effects of periodontal therapy on subclinical atherosclerosis, serum levels of CD40 ligand, serum amyloid A and monocyte chemoattractant protein-1, (b) limited evidence on the effects of periodontal therapy on arterial blood pressure, leucocyte counts, fibrinogen, tissue necrosis factor-α, sE-selectin, von Willebrand factors, d-dimers, matrix metalloproteinases, oxidative stress and CVD events, and (c) moderate evidence suggesting a negligible effect of periodontal therapy in reducing interleukin-6 and lipids levels, whilst a positive effect in reducing serum C-reactive protein levels and improving endothelial function.

CONCLUSIONS

Periodontal therapy triggers a short-term inflammatory response followed by (a) a progressive and consistent reduction of systemic inflammation and (b) an improvement in endothelial function. There is however limited evidence that these acute and chronic changes will either increase or reduce CVD burden of individuals suffering from periodontitis in the long term.

Evidence that periodontal treatment improves biomarkers and CVD outcomes

AIM

The aim of this review was to critically appraise the evidence on the impact of periodontal treatment of cardiovascular diseases (CVDs) biomarkers and outcomes.

METHODS

A systematic search was performed in Cinhal, Cochrane, Embase and Medline for relevant articles up to July 2012. Duplicate screening and reference hand searching were performed. Data were then summarized and evidence graded in tables.

RESULTS

The search resulted in: (a) no evidence on the effects of periodontal therapy on subclinical atherosclerosis, serum levels of CD40 ligand, serum amyloid A and monocyte chemoattractant protein-1, (b) limited evidence on the effects of periodontal therapy on arterial blood pressure, leucocyte counts, fibrinogen, tissue necrosis factor-a, sE-selectin, von Willebrand factors, d-dimers, matrix metalloproteinases, oxidative stress and CVD events, and (c) moderate evidence suggesting a negligible effect of periodontal therapy in reducing interleukin-6 and lipids levels, whilst a positive effect in reducing serum C-reactive protein levels and improving endothelial function.

CONCLUSIONS

Periodontal therapy triggers a short-term inflammatory response followed by (a) a progressive and consistent reduction of systemic inflammation and (b) an improvement in endothelial function. There is however limited evidence that these acute and chronic changes will either increase or reduce CVD burden of individuals suffering from periodontitis in the long term.

Glucotoxicity Induced Oxidative Stress and Inflammation In Vivo and In Vitro in Psammomys obesus: Involvement of Aqueous Extract of Brassica rapa rapifera

Context. Brassica rapa is considered as natural source of antioxidants and is used to treat diabetes. Objective. Our study carried the impact of glucotoxicity induced in vivo and in vitro in vascular smooth muscle cells (VSMCs) in Psammomys and the therapeutic effect of Brassica rapa (AEBr). Materials and Methods. We administered a hyperglucidic diet (30% sucrose) for 9 months and a treatment for 20 days with AEBr at 100 mg/kg. VSMCs were submitted to D-Glucose (0.6%) for 48 hours and treated with AEBr (2100 μg/mL) for 24 hours. We measured, in blood metabolic parameters, the redox statues and inflammatory markers in adipose tissue. Histological study was effectuated in liver. In VSMCs, we measured markers of glucotoxicity (IRS1p Serine, AKT) inflammation (NO, MCP1, TNFα, and NF-κB) and oxidative stress (oxidants and antioxydants markers). Cell viability and apoptosis were estimated by the morphological study. Results. AEBr corrects the metabolic parameters and inflammatory and oxidative markers in blood and homogenate tissue and reduces lipid droplets in liver. It induces, in VSMCs, a significant decrease of IRS1p serine, cyt c, NO, MCP1, TNFα, NF-κB, protein, and lipid oxidation and increases cell viability, AKT, ERK1/2, catalase, and SOD activity. Conclusion. Brassica enhanced the antidiabetic, anti-inflammatory, and antioxidant defense leading to the protection of cardiovascular diseases.

Rosiglitazone attenuates atherosclerosis and increases high-density lipoprotein function in atherosclerotic rabbits

Rosiglitazone has been found to have anti-atherogenic effects and to increase serum high-density lipoprotein (HDL) cholesterol (HDL-C) levels. However, in vivo studies investigating the regulation of adenosine triphosphate-binding cassette transporter A1 (ABCA1) and scavenger receptor class B type I (SR-BI) by rosiglitazone are limited. Moreover, the effects of rosiglitazone on the function and levels of HDL are unclear. In the present study, we investigated the effects of rosiglitazone on HDL function and its mechanisms of action in atherosclerotic rabbits. Our results revealed that rosiglitazone induced a significant increase in serum HDL-C levels, paraoxonase 1 (PON1) activity, [³H]cholesterol efflux rates, and the expression of ABCA1 and SR-BI in hepatocytes and peritoneal macrophages. The expression of ABCA1 was also increased in aortic lesions. Rosiglitazone markedly reduced serum myeloperoxidase (MPO) activity, aortic intima-media thickness (IMT) and the percentage of plaque area in the aorta. It can thus be concluded that in atherosclerotic rabbits, rosigitazone increases the levels of HDL-C and hinders atherosclerosis. Thus, it improves HDL quality and function, as well as the HDL-induced cholesterol efflux, exerting anti-inflammatory and antioxidant effects.

Celastrol suppresses obesity process via increasing antioxidant capacity and improving lipid metabolism

High fat diet, as an important risk factor, plays a pivotal role in atherosclerotic process. Celastrol is one of the active triterpenoid compounds with antioxidative and anti-inflammatory characters. The aims of this study were to evaluate the effect of celastrol on weight, blood lipid and oxidative injury induced by high fat emulsion, and investigate its potential pharmacological mechanisms. Male Sprague-Dawley rats were fed with high fat emulsion for 6 wk to mimic high fat mediated oxidative injury. The effects of celastrol on weight and blood lipid were evaluated, and its mechanisms were disclosed by applying western blot, ELISA and assay kits. Long-term consumption of high fat emulsion could significantly increase weight by enhancing total cholesterol (TC), triacylglycerol (TG), apolipoprotein B (Apo B), low-density lipoprotein cholesterol (LDL-c) levels, attenuating ATP-binding cassette transporter A1 (ABCA1) expression, and decreasing the levels of high-density lipoprotein cholesterol (HDL-c) and apolipoprotein A-I (Apo A-I), and inhibit antioxidant enzymes activities, improve nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity. Comparing with model group, celastrol was able to effectively suppress weight and attenuate high fat mediated oxidative injury by improving ABCA1 expression, reducing the levels of TC, TG, LDL-c and Apo B in plasma, and increasing antioxidant enzymes activities and inhibiting NADPH oxidase activity, and decreasing the serum levels of Malondialdehyde (MDA) and reactive oxygen species in dose-dependent way. These data demonstrated that celastrol was able to effectively suppress weight and alleviate high-fat mediated cardiovascular injury via mitigating oxidative stress and improving lipid metabolism.

Exercise improves immune function, antidepressive response, and sleep quality in patients with chronic primary insomnia

The aim of this study was to evaluate the effects of moderate aerobic exercise training on sleep, depression, cortisol, and markers of immune function in patients with chronic primary insomnia. Twenty-one sedentary participants (16 women aged 44.7 ± 9 years) with chronic primary insomnia completed a 4-month intervention of moderate aerobic exercise. Compared with baseline, polysomnographic data showed improvements following exercise training. Also observed were reductions in depression symptoms and plasma cortisol. Immunologic assays revealed a significant increase in plasma apolipoprotein A (140.9 ± 22 to 151.2 ± 22 mg/dL) and decreases in CD4 (915.6 ± 361 to 789.6 ± 310 mm(3)) and CD8 (532.4 ± 259 to 435.7 ± 204 mm(3)). Decreases in cortisol were significantly correlated with increases in total sleep time (r = -0.51) and REM sleep (r = -0.52). In summary, long-term moderate aerobic exercise training improved sleep, reduced depression and cortisol, and promoted significant changes in immunologic variables.

Remodeling pattern is related to the degree of coronary plaque regression induced by pitavastatin: a sub-analysis of the TOGETHAR trial with intravascular ultrasound and coronary angioscopy

This study aimed to clarify the relationships between arterial remodeling patterns and plaque volume regression or stabilization. The TOGETHAR trial is a prospective open-label trial designed to assess coronary plaque regression and stabilization with multiple plaque imaging modalities following 52 weeks of pitavastatin treatment (2 mg/day). Coronary plaques were observed in 46 patients with both angioscopy and intravascular ultrasound at baseline and after 52 weeks of drug treatment. We divided these patients into three groups according to their remodeling indices (RI). Group P consisted of patients with a baseline RI >1.05, Group M of patients with a baseline RI of 0.95-1.05, and Group N of patients with a baseline RI <0.95 and then evaluated differences in coronary plaque volume changes and yellow grade among the three groups. In the positive remodeling group, whose remodeling index (RI) exceeded 1.05 at baseline, RI and percent atheroma volume (PAV) were significantly reduced (RI 1.14 ± 0.07 to 1.05 ± 0.10, p = 0.010, PAV 47.3 ± 8.3 to 45.3 ± 7.3 mm(3), p = 0.048). There was no relationship between baseline RI and the change in yellow grade of plaque. RI increased without significant change of PAV or a decrease in lumen volume in group N, with RI below 0.95 at baseline. Plaques with positive remodeling were more likely to have plaque volume regression by pitavastatin than those without in patients with coronary artery disease. Moreover, plaques with positive and negative remodeling were changed into those with intermediate remodeling by pitavastatin. Pitavastatin might induce not only plaque regression or stabilization, but also conformational normalization of vessel structure.

Oxidized high-density lipoprotein induces the proliferation and migration of vascular smooth muscle cells by promoting the production of ROS

AIM

As the major atheroprotective particle in plasma, high-density lipoprotein(HDL) is oxidized during atherosclerotic processes. Oxidized HDL(ox-HDL) may lose its cardioprotective properties and develop a proinflammatory and proatherogenic phenotype. The proliferation and migration of vascular smooth muscle cells(VSMCs) play a crucial role in atherogenesis. However, the influence of ox-HDL on VSMC proliferation and migration remains poorly understood.

METHODS

VSMCs were treated with native HDL(N-HDL) or ox-HDL at varying concentrations for different time intervals and used in several analyses. The degree of cell proliferation was assayed using CCK-8 kits. The level of cell migration was determined using a Transwell chamber and scratch-wound assay. The presence of intracellular reactive oxygen species(ROS) was detected based on ROS-mediated 2',7'-dichlorofluorescein fluorescence. The activation of NADPH oxidase was measured in terms of the Rac1 activity and NADP(＋)/NADPH ratio.

RESULTS

Compared to N-HDL, ox-HDL significantly promoted VSMC proliferation and migration in a dose-dependent manner. In addition, ox-HDL remarkably activated NADPH oxidase and enhanced ROS generation in the VSMCs. Diphenyleneiodonium chloride, an inhibitor of NADPH oxidase, and N-acetylcysteine, a ROS scavenger, efficiently inhibited the ROS production triggered by ox-HDL and subsequently blocked the proliferating and migrating effects of ox-HDL in the VSMCs.

CONCLUSIONS

Ox-HDL significantly induces VSMC proliferation and migration by promoting NADPH oxidase activation and ROS production. Furthermore, the inhibition of NADPH oxidase and ROS generation blocks the proliferation and migration of VSMCs induced by ox-HDL. These proliferating and migrating effects of ox-HDL are closely related to its proinflammatory and proatherogenic roles.

Vulnerable plaque: from bench to bedside; local pacification versus systemic therapy

Critical coronary stenoses accounts for a small proportion of acute coronary syndromes and sudden death. The majority are caused by coronary thromboses that arise from a nonangiographically obstructive atheroma. Recent developments in noninvasive imaging of so-called vulnerable plaques created opportunities to direct treatment to prevent morbidity and mortality associated with these high-risk lesions. This review covers therapy employed in the past, present, and potentially in the future as the natural history of plaque assessment unfolds.

Recalculation of 23 mouse HDL QTL datasets improves accuracy and allows for better candidate gene analysis

In the past 15 years, the quantitative trait locus (QTL) mapping approach has been applied to crosses between different inbred mouse strains to identify genetic loci associated with plasma HDL cholesterol levels. Although successful, a disadvantage of this method is low mapping resolution, as often several hundred candidate genes fall within the confidence interval for each locus. Methods have been developed to narrow these loci by combining the data from the different crosses, but they rely on the accurate mapping of the QTL and the treatment of the data in a consistent manner. We collected 23 raw datasets used for the mapping of previously published HDL QTL and reanalyzed the data from each cross using a consistent method and the latest mouse genetic map. By utilizing this approach, we identified novel QTL and QTL that were mapped to the wrong part of chromosomes. Our new HDL QTL map allows for reliable combining of QTL data and candidate gene analysis, which we demonstrate by identifying Grin3a and Etv6, as candidate genes for QTL on chromosomes 4 and 6, respectively. In addition, we were able to narrow a QTL on Chr 19 to five candidates.

PPAR Medicines and Human Disease: The ABCs of It All

ATP-dependent binding cassette (ABC) transporters are a family of transmembrane proteins that pump a variety of hydrophobic compounds across cellular and subcellular barriers and are implicated in human diseases such as cancer and atherosclerosis. Inhibition of ABC transporter activity showed promise in early preclinical studies; however, the outcomes in clinical trials with these agents have not been as encouraging. Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that regulate genes involved in fat and glucose metabolism, and inflammation. Activation of PPAR signaling is also reported to regulate ABC gene expression. This suggests the potential of PPAR medicines as a novel means of controlling ABC transporter activity at the transcriptional level. This paper summarizes the advances made in understanding how PPAR medicines affect ABC transporters, and the potential implications for impacting on human diseases, in particular with respect to cancer and atherosclerosis.

Substituted benzamides containing azaspiro rings as upregulators of apolipoprotein A-I transcription

Apolipoprotein A-I (Apo A-I) is the principal protein component of high density lipoprotein (HDL), which is generally considered as a potential therapeutic target against atherosclerosis. The understanding of the Apo A-I regulation mechanism has fuelled the development of novel HDL targeted therapeutic approaches. To identify novel agents that can upregulate Apo A-I expression, we performed a cell-based reporter assay to screen 25,600 small molecules. Based on the dataset obtained from screening, a series of novel analogs of substituted benzamides containing azaspiro rings were assessed for their ability to induce the transcription of the Apo A-I gene, and the structure-activity relationship (SAR) around these analogs was also proposed. The results indicated that the trifluoromethyl substituted benzamide containing an azaspiro ring is a promising backbone for designing Apo A-I transcriptional upregulator and could be viable leads for development of new drugs to prevent and treat atherosclerosis in the future.

Structural and biophysical insight into cholesteryl ester-transfer protein

CETP (cholesteryl ester-transfer protein) is essential for neutral lipid transfer between HDL (high-density lipoprotein) and LDL (low-density lipoprotein) and plays a critical role in the reverse cholesterol transfer pathway. In clinical trials, CETP inhibitors increase HDL levels and reduce LDL levels, and therefore may be used as a potential treatment for atherosclerosis. In this review, we cover the analysis of CETP structure and provide insights into CETP-mediated lipid transfer based on a collection of structural and biophysical data.

Role for inducible cAMP early repressor in promoting pancreatic beta cell dysfunction evoked by oxidative stress in human and rat islets

AIMS/HYPOTHESIS

Pro-atherogenic and pro-oxidant, oxidised LDL trigger adverse effects on pancreatic beta cells, possibly contributing to diabetes progression. Because oxidised LDL diminish the expression of genes regulated by the inducible cAMP early repressor (ICER), we investigated the involvement of this transcription factor and of oxidative stress in beta cell failure elicited by oxidised LDL.

METHODS

Isolated human and rat islets, and insulin-secreting cells were cultured with human native or oxidised LDL or with hydrogen peroxide. The expression of genes was determined by quantitative real-time PCR and western blotting. Insulin secretion was monitored by EIA kit. Cell apoptosis was determined by scoring cells displaying pycnotic nuclei.

RESULTS

Exposure of beta cell lines and islets to oxidised LDL, but not to native LDL raised the abundance of ICER. Induction of this repressor by the modified LDL compromised the expression of important beta cell genes, including insulin and anti-apoptotic islet brain 1, as well as of genes coding for key components of the secretory machinery. This led to hampering of insulin production and secretion, and of cell survival. Silencing of this transcription factor by RNA interference restored the expression of its target genes and alleviated beta cell dysfunction and death triggered by oxidised LDL. Induction of ICER was stimulated by oxidative stress, whereas antioxidant treatment with N-acetylcysteine or HDL prevented the rise of ICER elicited by oxidised LDL and restored beta cell functions.

CONCLUSIONS/INTERPRETATION

Induction of ICER links oxidative stress to beta cell failure caused by oxidised LDL and can be effectively abrogated by antioxidant treatment.

Progress and challenges in translating the biology of atherosclerosis

Atherosclerosis is a chronic disease of the arterial wall, and a leading cause of death and loss of productive life years worldwide. Research into the disease has led to many compelling hypotheses about the pathophysiology of atherosclerotic lesion formation and of complications such as myocardial infarction and stroke. Yet, despite these advances, we still lack definitive evidence to show that processes such as lipoprotein oxidation, inflammation and immunity have a crucial involvement in human atherosclerosis. Experimental atherosclerosis in animals furnishes an important research tool, but extrapolation to humans requires care. Understanding how to combine experimental and clinical science will provide further insight into atherosclerosis and could lead to new clinical applications.

PPARγ activates ABCA1 gene transcription but reduces the level of ABCA1 protein in HepG2 cells

Synthesis of ABCA1 protein in liver is necessary for high-density lipoproteins (HDL) formation in mammals. Nuclear receptor PPARγ is known as activator of ABCA1 expression, but details of PPARγ-mediated regulation of ABCA1 at both transcriptional and post-transcriptional levels in hepatocytes have not still been well elucidated. In this study we have shown, that PPARγ activates ABCA1 gene transcription in human hepatoma cells HepG2 through increasing of LXRβ binding with promoter region of ABCA1 gene. Treatment of HepG2 cells with PPARγ agonist GW1929 leads to dissociation of LXRβ from ABCA1/LXRβ complex and to nuclear translocation of this nuclear receptor resulting in reduction of ABCA1 protein level 24h after treatment. Inhibition of protein kinases MEK1/2 abolishes PPARγ-mediated dissociation of LXRβ from ABCA1/LXRβ complex, but does not block PPARγ-dependent down-regulation of ABCA1 protein in HepG2 cells. These data suggest that PPARγ may be important for regulation of the level of hepatic ABCA1 protein and indicate the new interplays between PPARγ, LXRβ and MEK1/2 in regulation of ABCA1 mRNA and protein expression.

Cholesteryl ester transfer protein and its inhibition

Cholesteryl ester transfer protein (CETP) is a plasma glycoprotein that facilitates the transfer of cholesteryl esters from the atheroprotective high density lipoprotein (HDL) to the proatherogenic low density lipoprotein cholesterol (LDL) and very low density lipoprotein cholesterol (VLDL) leading to lower levels of HDL but raising the levels of proatherogenic LDL and VLDL. Inhibition of CETP is considered a potential approach to treat dyslipidemia. However, discussions regarding the role of CETP-mediated lipid transfer in the development of atherosclerosis and CETP inhibition as a potential strategy for prevention of atherosclerosis have been controversial. Although many animal studies support the hypothesis that inhibition of CETP activity may be beneficial, negative phase III studies on clinical endpoints with the CETP inhibitor torcetrapib challenged the future perspectives of CETP inhibitors as potential therapeutic agents. The review provides an update on current understanding of the molecular mechanisms involved in CETP activity and its inhibition.

High-density lipoprotein affects antigen presentation by interfering with lipid raft: a promising anti-atherogenic strategy

Atherosclerosis is a chronic inflammatory disease. Immunomodulation of atherosclerosis emerges as a promising approach to prevention and treatment of this widely prevalent disease. The function of high-density lipoprotein (HDL) to promote reverse cholesterol transport may explain the ability of its protection against atherosclerosis. Findings that HDL and apolipoprotein A-I (apoA-I) inhibited the ability of antigen presenting cells (APCs) to stimulate T cells might be attributed to lipid raft, a cholesterol-rich microdomain exhibiting functional properties depending largely upon its lipid composition. Thus, modulating cholesterol in lipid raft may provide a promising anti-atherogenic strategy.

Cholesteryl ester transfer protein: at the heart of the action of lipid-modulating therapy with statins, fibrates, niacin, and cholesteryl ester transfer protein inhibitors

Subnormal plasma levels of high-density lipoprotein cholesterol (HDL-C) constitute a major cardiovascular risk factor; raising low HDL-C levels may therefore reduce the residual cardiovascular risk that frequently presents in dyslipidaemic subjects despite statin therapy. Cholesteryl ester transfer protein (CETP), a key modulator not only of the intravascular metabolism of HDL and apolipoprotein (apo) A-I but also of triglyceride (TG)-rich particles and low-density lipoprotein (LDL), mediates the transfer of cholesteryl esters from HDL to pro-atherogenic apoB-lipoproteins, with heterotransfer of TG mainly from very low-density lipoprotein to HDL. Cholesteryl ester transfer protein activity is elevated in the dyslipidaemias of metabolic disease involving insulin resistance and moderate to marked hypertriglyceridaemia, and is intimately associated with premature atherosclerosis and high cardiovascular risk. Cholesteryl ester transfer protein inhibition therefore presents a preferential target for elevation of HDL-C and reduction in atherosclerosis. This review appraises recent evidence for a central role of CETP in the action of current lipid-modulating agents with HDL-raising potential, i.e. statins, fibrates, and niacin, and compares their mechanisms of action with those of pharmacological agents under development which directly inhibit CETP. New CETP inhibitors, such as dalcetrapib and anacetrapib, are targeted to normalize HDL/apoA-I levels and anti-atherogenic activities of HDL particles. Further studies of these CETP inhibitors, in particular in long-term, large-scale outcome trials, will provide essential information on their safety and efficacy in reducing residual cardiovascular risk.

[Visualizing arterial macrophage warfare with nuclear magnetic resonance, positron-emission tomography and computerized tomography]

The macrophage is the principal immune cell found in atherosclerotic plaque. Although its function is to phagocytose foreign bodies present in the vascular endothelium, it can undergo a process of sustained activation that gives rise to a pattern of chronic inflammation, which may even trigger an acute coronary syndrome. The cellular response underlying this disease process is mediated by a complex molecular signaling cascade. Cytokines released by activated macrophages ultimately produce significant tissue damage by perpetuating the ongoing inflammatory response. Recent studies have shown that a defective interaction between the macrophage and its substrate could provide a mechanism for destabilizing atherosclerotic plaque by stimulating digestion of the artery and promoting plaque rupture. A key element in the life cycle of macrophages is that, when they cannot effectively remove the foreign bodies that have resulted in their activation, they initiate cell death (i.e., apoptosis), thereby releasing substances into the extracellular milieu that are even more toxic than inflammatory mediators. The significant advances in noninvasive molecular imaging techniques that have taken place in recent years have helped to unravel fundamental features of macrophage biology and have made it possible to explore the potential benefits of specific therapeutic interventions. Nanomarkers designed to home in on specific molecular targets have enabled imaging techniques to be used not only to study the pathophysiological mechanisms of atherosclerotic disease but also to diagnose such disease, and have made it possible to imagine the development of a form of nanomedicine based on administering treatment that can target a single cell type.

Promoting mechanisms of vascular health: circulating progenitor cells, angiogenesis, and reverse cholesterol transport

To understand and promote vascular health, we must reduce the aggression to the vessel wall and enhance the physiologic mechanisms leading to restoration of vessel wall function. Three main defense mechanisms are responsible for maintaining cardiovascular homeostasis: the regenerative production of endothelial progenitor cells, vessel wall angiogenesis, and macrophage-mediated reverse cholesterol transport. Endothelial progenitor cells can restore vessel wall function and reduce atherosclerosis. In patients with risk factors, high levels of circulating progenitor cells increase event-free survival from cardiovascular events. Mobilization of progenitor cells includes physical and pharmacological approaches, of which exercise and statin therapy have great potential. Angiogenesis is a pivotal defense mechanism to counteract hypoxia and is needed for plaque regression. However, neovessels are susceptible for intraplaque hemorrhage, particularly in diabetes mellitus. In these patients, the haptoglobin 2-2 genotype is the more affected, and may benefit from an antioxidant approach. Finally, the reverse cholesterol transport system is the main mechanism for plaque regression. In addition to high-density lipoprotein cholesterol, apolipoprotein A-I therapies and the promotion of cholesterol efflux from macrophages by the ABCA1 and ABCG1 transporter systems hold great promise and may be available for therapeutic application in the near future.

Safety and tolerability of dalcetrapib

Efficacy and safety data for dalcetrapib (RO4607381/JTT-705) are presented, following a report of increased mortality and cardiac events with another cholesteryl ester transfer protein inhibitor, torcetrapib, associated with off-target adverse effects (hypertension and the activation of the renin-angiotensin-aldosterone system). The efficacy and clinical safety of dalcetrapib 300, 600, and 900 mg or placebo were assessed (n = 838) in 4 pooled 4-week phase IIa trials (1 monotherapy, n = 193; 3 statin combination, n = 353) and 1 12-week phase IIb trial (with pravastatin, n = 292). Nonclinical safety, assessed by the induction of aldosterone production and aldosterone synthase (cytochrome P450 11B2) messenger ribonucleic acid, was measured in human adrenocarcinoma (H295R) cells exposed to dalcetrapib or torcetrapib. Dalcetrapib increased high-density lipoprotein cholesterol by up to 36% and apolipoprotein A-I by up to 16%. The incidence of adverse events (AEs) was similar between placebo (42%) and dalcetrapib 300 mg (50%) and 600 mg (42%), with more events with dalcetrapib 900 mg (58%) (p <0.05, pooled 4-week studies). Six serious AEs (3 with placebo, 1 with dalcetrapib 300 mg, and 2 with dalcetrapib 600 mg) were considered "unrelated" to treatment. Cardiovascular AEs were similar across treatment groups, with no dose-related trends and no clinically relevant changes in blood pressure or electrocardiographic results. Findings were similar in the 12-week study. In vitro, torcetrapib but not dalcetrapib increased aldosterone production and cytochrome P450 11B2 messenger ribonucleic acid levels. In conclusion, dalcetrapib alone or in combination with statins was effective at increasing high-density lipoprotein cholesterol and was well tolerated, without clinically relevant changes in blood pressure or cardiovascular AEs and no effects on aldosterone production as assessed nonclinically.

Effect of rimonabant on the high-triglyceride/ low-HDL-cholesterol dyslipidemia, intraabdominal adiposity, and liver fat: the ADAGIO-Lipids trial

BACKGROUND

Rimonabant, the first selective cannabinoid type 1 (CB1) receptor antagonist, improves cardiometabolic risk factors in overweight/obese patients. ADAGIO-Lipids assessed the effect of rimonabant on cardiometabolic risk factors and intraabdominal and liver fat.

METHODS AND RESULTS

803 abdominally obese patients with atherogenic dyslipidemia (increased triglycerides [TG] or reduced high-density lipoprotein-cholesterol [HDL-C]) were randomized to placebo or rimonabant 20 mg/d for 1 year. HDL-C and TG were coprimary end points. Intraabdominal (visceral) and liver fat were measured by computed tomography in a subgroup of 231 patients. In total, 73% of rimonabant- and 70% of placebo-treated patients completed the study treatment. Rimonabant 20 mg produced significantly greater changes from baseline versus placebo in HDL-C (+7.4%) and TG levels (-18%; P<0.0001), as well as low-density lipoprotein (LDL) and HDL particle sizes, apolipoprotein A1 and B, HDL2, HDL3, C-reactive protein, and adiponectin levels (all P<0.05). Rimonabant decreased abdominal subcutaneous adipose tissue (AT) cross-sectional area by 5.1% compared to placebo (P<0.005), with a greater reduction in visceral AT (-10.1% compared to placebo; P<0.0005), thereby reducing the ratio of visceral/subcutaneous AT (P<0.05). Rimonabant significantly reduced liver fat content (liver/spleen attenuation ratio; P<0.005). Systolic (-3.3 mm Hg) and diastolic (-2.4 mm Hg) blood pressure were significantly reduced with rimonabant versus placebo (P<0.0001). The safety profile of rimonabant was consistent with previous studies; gastrointestinal, nervous system, psychiatric, and general adverse events were more common with rimonabant 20 mg.

CONCLUSIONS

In abdominally obese patients with atherogenic dyslipidemia, rimonabant 20 mg significantly improved multiple cardiometabolic risk markers and induced significant reductions in both intraabdominal and liver fat.

High glucose induces transactivation of the human paraoxonase 1 gene in hepatocytes

Human serum paraoxonase 1 (PON1) is associated with high-density lipoprotein and inhibits oxidative modification of low-density lipoprotein in vitro. Therefore, PON1 is expected to protect against atherosclerosis in vivo. We and other investigators have shown that PON1 enzymatic activity is decreased in diabetic patients; however, an alteration in hepatic PON1 synthesis under hyperglycemic conditions remains unclear. We previously demonstrated that Sp1 is a positive regulator of PON1 transcription and that an interaction between Sp1 and protein kinase C (PKC) is a crucial mechanism for the effect of Sp1 on PON1 transcription in cultured HepG2 cells. Because several PKC isoforms are activated under hyperglycemic conditions, we examined the effect of d-glucose, which can activate the diacylglycerol-PKC pathway, on the transcription and expression of PON1. For a reporter gene assay, Huh7 human hepatocyte cell line incorporated with PON1 (-1232/-6)-luciferase expression vector was established using a cationic lipid method. d-Glucose dose dependently enhanced PON1 promoter activity. d-Glucose also enhanced both messenger RNA and protein expression of PON1. Increased PON1 expression was also detected in primary human hepatocytes treated with high d-glucose concentrations. Bisindolylmaleimide, a PKC inhibitor, significantly inhibited d-glucose-induced transactivation of PON1; and mithramycin, an inhibitor of Sp1, completely abrogated the transactivation. Our data suggest that high glucose concentrations transactivate the PON1 gene through Sp1 activation by PKC in cultured hepatocytes. Up-regulated hepatic PON1 expression under high glucose conditions may be a compensatory mechanism in diabetes in which antioxidant capacity, including PON1 enzymatic activity, is attenuated.

Infusion of reconstituted high-density lipoprotein leads to acute changes in human atherosclerotic plaque

Studies have shown a reduction in plaque volume and change in plaque ultrasound characteristics after 4 infusions of reconstituted high-density lipoprotein (rHDL). Whether rHDL infusion leads to acute changes in plaque characteristics in humans is not known. Patients with claudication scheduled for percutaneous superficial femoral artery revascularization were randomized to receive 1 intravenous infusion of either placebo or rHDL (80 mg/kg given over 4 hours). Five to 7 days following the infusion, patients returned and revascularization was performed including atherectomy to excise plaque from the superficial femoral artery. Twenty patients (17 males) average age, 68+/-10 years (mean+/-SD) were recruited. Eleven patients had a history of documented coronary artery disease, all patients were on aspirin, and 18 were on statins. Ten of the patients received rHDL and 10 placebo. There was significantly less vascular cell adhesion molecule-1 expression (28+/-3% versus 50+/-3%; P<0.05) and a reduction in lipid content in the plaque of HDL-treated subjects compared to placebo. The level of HDL cholesterol increased by 20% after infusion of rHDL and the capacity of apolipoprotein B-depleted plasma to support cholesterol efflux increased. Intravenous infusion of a single dose of reconstituted HDL led to acute changes in plaque characteristics with a reduction in lipid content, macrophage size, and measures of inflammation. These changes may contribute to the cardioprotective effects of HDL.

Genetic basis of HDL variation in 129/SvImJ and C57BL/6J mice: importance of testing candidate genes in targeted mutant mice

To evaluate the effect of genetic background on high-density lipoprotein cholesterol (HDL) levels in Soat1(-/-) mice, we backcrossed sterol O-acyltransferase 1 (Soat1)(-/-) mice, originally reported to have elevated HDL levels, to C57BL/6 mice and constructed a congenic strain with only a small region (3.3Mb) of 129 alleles, specifically excluding the nearby apolipoprotein A-II (Apoa2) gene from 129. HDL levels in these Soat1(-/-) mice were no different from C57BL/6, indicating that the passenger gene Apoa2 caused the previously reported elevation of HDL in these Soat1(-/-) mice. Because many knockouts are made in strain 129 and then subsequently backcrossed into C57BL/6, it is important to identify quantitative trait loci (QTL) that differ between 129 and C57BL/6 so that one can guard against effects ascribed to a knockout but really caused by a passenger gene from 129. To provide such data, we generated 528 F(2) progeny from an intercross of 129S1/SvImJ and C57BL/6 and measured HDL concentrations in F(2) animals first fed chow and then atherogenic diet. A genome wide scan using 508 single-nucleotide polymorphisms (SNPs) identified 19 QTL, 2 of which were male specific and 2 were female specific. Using comparative genomics and haplotype analysis, we narrowed QTL on chromosomes 3, 5, 8, 17, and 18 to 0.5, 6.3, 2.6, 1.1, and 0.6 Mb, respectively. These data will serve as a reference for any effort to test the impact of candidate genes on HDL using a knockout strategy.