Exploiting the vascular protective effects of high-density lipoprotein and its apolipoproteins: an idea whose time for testing is coming, part II

Polysaccharides from Lactarius volemus Fr. ameliorate high-fat and high-fructose diet induced metabolic disorders and intestinal barrier dysfunction

Our research was conducted to investigate the effects of Lactarius volemus Fr. polysaccharides (LVP) on metabolic disorders and intestinal barrier dysfunction in HFFD-induced obese mice. Our findings demonstrated that LVP supplementation significantly ameliorated hyperlipoidemia and hyperglycemia, insulin resistance and hepatic inflammation. Additionally, LVP alleviated hepatic steatosis and histological lesions, as well as hepatic function dysbiosis. The underlying mechanism may involve the regulation of hepatic insulin signaling transduction pathway such as IRS1/AKT pathway and the suppression of MAPKs signaling pathway. Furthermore, LVP intervention improved intestinal barrier function and reduced intestinal permeability by enhancing the expression of tight junction proteins and restoring intestinal microbiota composition. In summary, our results provided evidence that LVP exerted beneficial effects on HFFD-induced metabolic disorders along with restoration of intestinal barrier function and reduction in endotoxin levels. These outcomes are associated with maintenance of gut microbiota homeostasis and up-regulation of Short-Chain Fatty Acids (SCFAs). Furthermore, butyric acid was found to restrict lipid accumulation in OA-induced HepG2 hepatocytes while strengthening intestinal barrier integrity in LPS-induced Caco-2 cells. Thus, polysaccharides LVP may serve as a potential prebiotic or health supplement in the prevention and treatment of obesity-related metabolic disorders.

High-Density Lipoprotein Subclasses and Their Role in the Prevention and Treatment of Cardiovascular Disease: A Narrative Review

The association between high-density lipoprotein cholesterol (HDL-C) and cardiovascular disease (CVD) is controversial. HDL-C is one content type of high-density lipoprotein (HDL). HDL consists of diverse proteins and lipids and can be classified into different subclasses based on size, shape, charge, and density, and can change dynamically in disease states. Therefore, HDL-C levels alone cannot represent HDLs' cardioprotective role. In this review, we summarized the methods for separating HDL subclasses, the studies on the association between HDL subclasses and cardiovascular risk (CVR), and the impact of lipid-modifying medications and nonpharmacological approaches (exercise training, dietary omega fatty acids, and low-density lipoprotein apheresis) on HDL subclasses. As HDL is a natural nanoplatform, recombinant HDLs (rHDLs) have been used as a delivery system in vivo by loading small interfering RNA, drugs, contrast agents, etc. Therefore, we further reviewed the HDL subclasses used in rHDLs and their advantages and disadvantages. This review would provide recommendations and guidance for future studies on HDL subclasses' cardioprotective roles.

Interaction between adipocytes and high-density lipoprotein:new insights into the mechanism of obesity-induced dyslipidemia and atherosclerosis

Obesity is the most common nutritional disorder worldwide and is associated with dyslipidemia and atherosclerotic cardiovascular disease. The hallmark of dyslipidemia in obesity is low high density lipoprotein (HDL) cholesterol (HDL-C) levels. Moreover, the quality of HDL is also changed in the obese setting. However, there are still some disputes on the explanations for this phenomenon. There is increasing evidence that adipose tissue, as an energy storage tissue, participates in several metabolism activities, such as hormone secretion and cholesterol efflux. It can influence overall reverse cholesterol transport and plasma HDL-C level. In obesity individuals, the changes in morphology and function of adipose tissue affect plasma HDL-C levels and HDL function, thus, adipose tissue should be the main target for the treatment of HDL metabolism in obesity. In this review, we will summarize the cross-talk between adipocytes and HDL related to cardiovascular disease and focus on the new insights of the potential mechanism underlying obesity and HDL dysfunction.

High-density lipoprotein cholesterol levels are associated with coronary severity but not with outcomes in new-onset patients with stable coronary artery disease

BACKGROUND AND AIMS

The atheroprotective role of high-density lipoprotein cholesterol (HDL-C) levels in coronary artery disease (CAD) remains controversial. This study sought to reappraise the value of HDL-C in predicting the severity and outcomes of new-onset patients with stable CAD in Chinese populations.

METHODS

A total of 4205 new-onset patients with stable CAD who received coronary angiography were enrolled to analyze the relation of HDL-C to coronary severity and major adverse cardiovascular events (MACEs). Coronary severity was evaluated by Gensini scoring system. The MACEs included all-cause death, non-fatal myocardial infarction, stroke, unplanned revascularization and hospitalized unstable angina.

RESULTS

Significantly, HDL-C levels were negatively associated with coronary severity (p < 0.001). During an average of 27.32-month follow-up, 341 (8.12%) MACEs occurred. There was no significant difference of HDL-C levels between events group and non-events group. Furthermore, both Kaplan-Meier and Cox regression analyses found no relationship between HDL-C and cardiovascular outcomes (p > 0.05).

CONCLUSIONS

Plasma HDL-C levels appeared to be a predicator for coronary severity, but it is not associated with clinical outcomes in new-onset, Chinese patients with stable CAD.

Nontraditional Lipid Variables Predict Recurrent Brain Ischemia in Embolic Stroke of Undetermined Source

OBJECTIVE

The aims of this study are, first, to calculate the risk of brain ischemia recurrence and embolic source diagnosis in the follow-up of patients with ESUS (embolic stroke of undetermined source) and, second, to identify the predictors of these events including cardiologic, laboratory, and clinical factors.

METHODS

A retrospective observational cohort study of stroke patients admitted to the stroke unit in a single tertiary hospital from 2012 to 2014 was performed. Patients fulfilling ESUS criteria were identified and followed by medical history review until March 2016. Statistical analysis comprised Kaplan-Meier analysis and Cox proportional hazards multivariate analysis including clinical characteristics, cardiologic data, and blood test results.

RESULTS

One hundred and thirteen patients, 8.3% of the overall stroke patients, filled ESUS criteria and they were younger, had less vascular risk factors, and suffered milder strokes than the remainder of stroke patients. Median follow-up of ESUS was 25.6 months. Risk of brain ischemia recurrence was 8.4, 10.8, and 15% at 12, 24, and 36 months, respectively, and was associated to age (HR 1.07, P = .027) and to a higher total cholesterol (TC)/high-density lipoprotein (HDL)-cholesterol (HR = 1.38, P = .002) and low-density lipoprotein (LDL)-cholesterol/HDL-cholesterol ratios (HR = 1.48, P = .001). The risk of major embolic source diagnosis was 6.7, 7.8, 13.6% at 12, 24, and 36 months, and was associated to female sex (HR = 6.05, P = .021).

CONCLUSIONS

Brain ischemia recurrence increases with age and increased values of nontraditional lipid variables, TCHDLr and LDLHDLr, in ESUS patients, and women are more frequently diagnosed with a major embolic source in the follow-up.

Hovenia Dulcis Extract Reduces Lipid Accumulation in Oleic Acid-Induced Steatosis of Hep G2 Cells via Activation of AMPK and PPARα/CPT-1 Pathway and in Acute Hyperlipidemia Mouse Model

Hovenia dulcis Thunb. (HDT) was known to have anti-fatigue, anti-diabetes, neuroprotective, and hepatoprotective effects. In the present study, the anti-fatty liver mechanism of HDT was elucidated in oleic acid (OA)-treated Hep G2 cells and acute hyperlipidemia mouse model using Triton WR-1339. Here, HDT activated p-AMP-activated protein kinase (p-AMPK), proliferator activated receptor-α, carnitine palmitoyltransferase and also inhibited the expression of lipogenesis and cholesterol synthesis proteins, such as 3-hydroxy-3-methylglutaryl-CoA reductase, sterol regulatory element binding protein-1c, SREBP-2, and fatty acid synthase in OA-treated Hep G2 cells. Conversely, AMPK inhibitor compound C blocked the anti-fatty liver effect of HDT to induce AMPK phosphorylation and decrease 3-hydroxy-3-methylglutaryl-CoA reductase and lipid accumulation by oil red O staining in OA-treated Hep G2 cells. Additionally, HDT pretreatment protected against the increase of serum total cholesterol, triglyceride, low-density lipoprotein cholesterol and phospholipid in an acute hyperlipidemia mouse model with enhancement of glutathione reductase, glutathione peroxidase, superoxide dismutase, and catalase activities. Taken together, HDT inhibits OA-induced hepatic lipid accumulation via activation of AMPK and proliferator activated receptor-α/carnitine palmitoyltransferase signaling and enhancement of antioxidant activity as a potent candidate for nonalcoholic fatty liver disease and hyperlipidemia. Copyright © 2016 John Wiley & Sons, Ltd.

Lack of Association between High-Density Lipoprotein Cholesterol and Angiographic Coronary Lesion Severity in Chinese Patients with Low Background Low-Density Lipoprotein Cholesterol

BACKGROUND

The atheroprotective role of high-density lipoprotein (HDL-C) particles as measured by HDL-C level in coronary arterial disease (CAD) remains unsettled. The aim of our study was to ascertain whether HDL-C was associated with the development and severity of coronary artery disease in Chinese patients who underwent coronary angiogram with low background Low-density lipoprotein (LDL-C) levels, which has not been previously investigated.

METHODS

Between March 1995 and May 2000, 566 consecutive patients (408 males, 66.7 ± 11.3 years of age) with background LDL-C less than 100 mg/dl who underwent coronary artery angiography at our cath lab for suspected CAD were retrospectively recruited into the study. The severity of coronary lesions was measured by conventional coronary angiography and modified Gensini scores.

RESULTS

In those subjects with significant coronary lesions, there were more males and conventional CAD risk factors of diabetes mellitus, smoking, and chronic renal disease. They were also older compared to those in the control group. However, total cholesterol, LDL-C, HDL-C, triglyceride levels and use of statins were similar in both groups. In those subjects with significant coronary lesions, there was no difference in conventional coronary lesion severity or modified Gensini score between the quartered HDL-C subgroups. Furthermore, there was no significant correlation between serum HDL-C level and modified Gensini scores. In linear regression analysis, HDL-C was not an independent predictor for modified Gensini scores. Furthermore, HDL-C was also not an independent risk factor for the presence of significant coronary lesions in low LDL-C patients in logistic regression analysis.

CONCLUSIONS

In Chinese patients with low background LDL-C, serum HDL-C was not associated with development of CAD or lesion severity in patients with suspected CAD. Therefore, HDL-C did not appear to be atheroprotective in these patients.

KEY WORDS

Coronary artery disease; Gensini score; High-density lipoprotein cholesterol.

Effects of n-3 polyunsaturated fatty acids high fat diet intervention on the synthesis of hepatic high-density lipoprotein cholesterol in obesity-insulin resistance rats

Background

n-3 polyunsaturated fatty acids (PUFA) have previously been demonstrated in association with a reduced risk of chronic diseases, including insulin resistance, cancer and cardiovascular disease. In the present study, we analyzed the effects of n-3 PUFA-rich perilla oil (PO) and fish oil (FO) high fat diet intervention against the synthesis of hepatic high-density lipoprotein cholesterol (HDL-c) in obesity-insulin resistance model rats.

Methods

In the modeling period, the male SD rats were randomly divided into 2 groups. The rats in the high fat (HF) group were given a high fat pure diet containing 20.62 % lard. In the intervention period, the model rats were intervened with purified high-fat diets rich in PO or FO, containing same energy content with high fat pure diet in HF. After the intervention, the protein and mRNA expressions status of the key genes involved in synthesis of hepatic HDL-c were measured for further analytic comparison.

Results

The obesity-insulin resistance model rats were characterized by surprisingly high levels of serum triglyceride (TG) and increased body weight (P < 0.05, each). After the intervention, there were no apparent changes in the serum HDL-c and total cholesterol (TCH). In addition, the FO could up-regulate the hepatic adenosine triphosphate (ATP) binding cassette transporter A1 (ABCA1) mRNA (P < 0.01) and protein expressions, as well as increase the level of serum apolipoprotein A-1 (apoA-1) (P < 0.0001), and elevate the hepatic apoA-1mRNA expression (P < 0.01). Different from FO, the PO specifically elevated the hepatic ABCA1mRNA expression (P < 0.01).

Conclusions

The FO high fat diets promoted the synthesis of HDL-c in the obesity-insulin resistance rats.

HDL/ApoA-1 infusion and ApoA-1 gene therapy in atherosclerosis

The HDL hypothesis stating that simply raising HDL cholesterol (HDL-C) may produce cardiovascular benefits has been questioned recently based on several randomized clinical trials using CETP inhibitors or niacin to raise HDL-C levels. However, extensive pre-clinical data support the vascular protective effects of administration of exogenous ApoA-1 containing preβ-HDL like particles. Several small proof-of-concept clinical trials using such HDL/ApoA-1 infusion therapy have shown encouraging results but definitive proof of efficacy must await large scale clinical trials. In addition to HDL infusion therapy an alternative way to exploit beneficial cardiovascular effects of HDL/ApoA-1 is to use gene transfer. Preclinical studies have shown evidence of benefit using this approach; however clinical validation is yet lacking. This review summarizes our current knowledge of the aforementioned strategies.

Learning from biology: synthetic lipoproteins for drug delivery

Synthetic lipoproteins represent a relevant tool for targeted delivery of biological/chemical agents (chemotherapeutics, siRNAs, photosensitizers, and imaging contrast agents) into various cell types. These nanoparticles offer a number of advantages for drugs delivery over their native counterparts while retaining their natural characteristics and biological functions. Their ultra-small size (<30 nm), high biocompatibility, favorable circulation half-life, and natural ability to bind specific lipoprotein receptors, i.e., low-density lipoprotein receptor (LDLR) and Scavenger receptor class B member 1 (SRB1) that are found in a number of pathological conditions (e.g., cancer, atherosclerosis), make them superior delivery strategies when compared with other nanoparticle systems. We review the various approaches that have been developed for the generation of synthetic lipoproteins and their respective applications in vitro and in vivo. More specifically, we summarize the approaches employed to address the limitation on use of reconstituted lipoproteins by means of natural or recombinant apolipoproteins, as well as apolipoprotein mimetic molecules. Finally, we provide an overview of the advantages and disadvantages of these approaches and discuss future perspectives for clinical translation of these nanoparticles.

Dyslipidemia and diabetic retinopathy

Diabetic retinopathy (DR) is one of the major microvascular complications of diabetes. In developed countries, it is the most common cause of preventable blindness in diabetic adults. Dyslipidemia, a major systemic disorder, is one of the most important risk factors for cardiovascular disease. Patients with diabetes have an increased risk of suffering from dyslipidemia concurrently. The aim of this article is to review the association between diabetic retinopathy (DR) and traditional/nontraditional lipid markers, possible mechanisms involving lipid metabolism and diabetic retinopathy, and the effect of lipid-lowering therapies on diabetic retinopathy. For traditional lipid markers, evidence is available that total cholesterol and low-density lipoprotein cholesterol are associated with the presence of hard exudates in patients with DR. The study of nontraditional lipid markers is advancing only in recently years. The severity of DR is inversely associated with apolipoprotein A1 (ApoA1), whereas ApoB and the ApoB-to-ApoA1 ratio are positively associated with DR. The role of lipid-lowering medication is to work as adjunctive therapy for better control of diabetes-related complications including DR.

High density lipoproteins and endothelial functions: mechanistic insights and alterations in cardiovascular disease

Prospective population studies in the primary prevention setting have shown that reduced plasma levels of HDL cholesterol are associated with an increased risk of coronary disease and myocardial infarction. Experimental and translational studies have further revealed several potential anti-atherogenic effects of HDL, including protective effects on endothelial cell functions. HDL has been suggested to protect endothelial cell functions by prevention of oxidation of LDL and its adverse endothelial effects. Moreover, HDL from healthy subjects can directly stimulate endothelial cell production of nitric oxide and anti-inflammatory, anti-apoptotic, and anti-thrombotic effects as well as endothelial repair processes. However, several recent clinical trials using HDL cholesterol-raising agents, such as torcetrapib, dalcetrapib, and niacin, did not demonstrate a significant reduction of cardiovascular events in patients with coronary disease. Of note, growing evidence suggests that the vascular effects of HDL can be highly heterogeneous and vasoprotective properties of HDL are altered in patients with coronary disease. Characterization of underlying mechanisms and understanding of the clinical relevance of this "HDL dysfunction" is currently an active field of cardiovascular research. Notably, in some recent studies no clear association of higher HDL cholesterol levels with a reduced risk of cardiovascular events was observed in patients with already established coronary disease. A greater understanding of mechanisms of action of HDL and its altered vascular effects is therefore critical within the context of HDL-targeted therapies. In this review, we will address different effects of HDL on endothelial cell functions potentially relevant to atherosclerotic vascular disease and explore molecular mechanisms leading to "dysfunctional HDL".

Progress in HDL-based therapies for atherosclerosis

Atherosclerosis is a chronic inflammatory disease affecting medium and large arteries resulting from a complex interaction between genetic and environmental risk factors that include dyslipidemia, hypertension, diabetes mellitus, and smoking. The most serious manifestations of atherosclerotic vascular disease, such as unstable angina, myocardial infarction, ischemic stroke, and sudden death, largely result from thrombosis superimposed on a disrupted (ruptured or eroded) atherosclerotic plaque. Adoption and maintenance of a healthy lifestyle coupled with management of modifiable risk factors significantly reduce the adverse clinical consequences of athero-thrombosis. Reducing low-density lipoprotein cholesterol levels using statins and other agents serves as the primary pharmacologic approach to stabilize atherosclerotic vascular disease. However, a large residual risk remains, prompting the search for additional therapies for atherosclerosis management, such as raising atheroprotective high-density lipoprotein (HDL) and/or improving HDL function. This review focuses on new and emerging HDL-based therapeutic strategies targeting atherosclerosis.

Serum apolipoproteins are associated with systemic and retinal microvascular function in people with diabetes

Serum apolipoprotein (apo)AI and -B have been shown to be associated with diabetic retinopathy, but the underlying mechanisms are unclear. We investigated whether apoAI and apoB levels are associated with measures of systemic and retinal microvascular function in patients with diabetes. We recruited 224 diabetic patients (85 type 1 and 139 type 2) and assessed serum lipids and lipoproteins from fasting blood, skin responses to sodium nitroprusside (endothelium independent) and acetylcholine (ACh) (endothelium dependent) iontophoresis, flicker-light-induced retinal vasodilatation, and retinal vascular tortuosity. After adjustment for age and sex, every SD increase in apoAI level was associated with ACh-induced skin perfusion (mean change 1.27%; P < 0.001 for apoAI) and flicker-light retinal arteriolar vasodilatation (0.33%; P = 0.003) and was associated inversely with arteriolar tortuosity (-2.83 × 10(-5); P = 0.044). Each SD increase in apoB was associated with arteriolar tortuosity only (1.75 × 10(-5); P = 0.050). These associations, except for apoB, remained in multivariate models. Serum apoAI was associated with increased vasomotor responsiveness to ACh and flickering light and inversely related to retinal vessel tortuosity--a characteristic that has both structural and functional dimensions. These findings provide additional insights into the potential mechanisms of apos in the pathogenesis of diabetic retinopathy and other diabetic microvascular complications.

Microvesicles: potential markers and mediators of endothelial dysfunction

PURPOSE OF REVIEW

Microvesicles (also known as microparticles) are small membranous structures that are released from platelets and cells upon activation or during apoptosis. Microvesicles have been found in blood, urine, synovial fluid, extracellular spaces of solid organs, atherosclerotic plaques, tumors, and elsewhere. Here, we focus on new clinical and basic work that implicates microvesicles as markers and mediators of endothelial dysfunction and hence novel contributors to cardiovascular and other diseases.

RECENT FINDINGS

Advances in the detection of microvesicles and the use of cell type-specific markers to determine their origin have allowed studies that associated plasma concentrations of specific microvesicles with major types of endothelial dysfunction - namely, inappropriate or maladaptive vascular tone, leukocyte recruitment, and thrombosis. Recent investigations have highlighted microvesicular transport of key biologically active molecules besides tissue factor, such as ligands for pattern-recognition receptors, elements of the inflammasome, and morphogens. Microvesicles generated from human cells under different pathologic circumstances, for example, during cholesterol loading or exposure to endotoxin, carry different subsets of these molecules and thereby alter endothelial function through several distinct, well characterized molecular pathways.

SUMMARY

Clinical and basic studies indicate that microvesicles may be novel markers and mediators of endothelial dysfunction. This work has advanced our understanding of the development of cardiovascular and other diseases. Opportunities and obstacles to clinical applications are discussed.

ApoA-1 mimetic restores adiponectin expression and insulin sensitivity independent of changes in body weight in female obese mice

BACKGROUND

We examined the ability of the apolipoprotein AI mimetic peptide L-4F to improve the metabolic state of female and male ob mice and the mechanisms involved.

METHODS

Female and male lean and obese (ob) mice were administered L-4F or vehicle for 6 weeks. Body weight was measured weekly. Fat distribution, serum cytokines and markers of cardiovascular dysfunction were determined at the end of treatment.

RESULTS

L-4F significantly decreased serum interleukin (IL)-6, tumor necrosis factor-α and IL-1β. L-4F improved vascular function, and increased serum adiponectin levels and insulin sensitivity compared with untreated mice. In addition, L-4F treatment increased heme oxygenase (HO)-1, pAKT and pAMPK levels in kidneys of ob animals. pAKT and pAMPK levels were significantly reduced in the presence of an HO inhibitor. Interestingly, L4F did not alter body weight in female mice, but caused a significant reduction in males.

CONCLUSIONS

L-4F treatments reduced cardiovascular risk factors and improved insulin sensitivity in female ob mice independent of body fat changes. Reduced inflammatory cytokine levels accompanied by increased HO activity, serum adiponectin and improved insulin sensitivity suggest that L-4F may promote the conversion of visceral fat to a healthier phenotype. Therefore, L-4F appears to be a promising therapeutic strategy for treating both cardiovascular risk factors and insulin resistance in obese patients of either gender.

Regulation of the expression of key genes involved in HDL metabolism by unsaturated fatty acids

The cardioprotective effects of HDL have been largely attributed to their role in the reverse cholesterol transport pathway, whose efficiency is affected by many proteins involved in the formation and remodelling of HDL. The aim of the present study was to determine the effects, and possible mechanisms of action, of unsaturated fatty acids on the expression of genes involved in HDL metabolism in HepG2 cells. The mRNA concentration of target genes was assessed by real-time PCR. Protein concentrations were determined by Western blot or immunoassays. PPAR and liver X receptor (LXR) activities were assessed in transfection experiments. Compared with the SFA palmitic acid (PA), the PUFA arachidonic acid (AA), EPA and DHA significantly decreased apoA-I, ATP-binding cassette A1 (ABCA1), lecithin-cholesterol acyltransferase (LCAT) and phospholipid transfer protein mRNA levels. EPA and DHA significantly lowered the protein concentration of apoA-I and LCAT in the media, as well as the cellular ABCA1 protein content. In addition, DHA repressed the apoA-I promoter activity. AA lowered only the protein concentration of LCAT in the media. The activity of PPAR was increased by DHA, while the activity of LXR was lowered by both DHA and AA, relative to PA. The regulation of these transcription factors by PUFA may explain some of the PUFA effects on gene expression. The observed n-3 PUFA-mediated changes in gene expression are predicted to reduce the rate of HDL particle formation and maturation.

HDL Mimetic Peptide Administration Improves Left Ventricular Filling and Cardiac output in Lipopolysaccharide-Treated Rats

AIMS: Cardiac dysfunction is a complication of sepsis and contributes to morbidity and mortality. Since raising plasma apolipoprotein (apo) A-I and high density lipoprotein (HDL) concentration reduces sepsis complications, we tested the hypothesis that the apoA-I mimetic peptide 4F confers similar protective effects in rats treated with lipopolysaccharide (LPS). METHODS AND RESULTS: Male Sprague-Dawley (SD) rats were randomized to receive saline vehicle (n=13), LPS (10 mg/kg: n=16) or LPS plus 4F (10 mg/kg each: n=13) by intraperitoneal injection. Plasma cytokine and chemokine levels were significantly elevated 24 hrs after LPS administration. Echocardiographic studies revealed changes in cardiac dimensions that resulted in a reduction in left ventricular end-diastolic volume (LVEDV), stroke volume (SV) and cardiac output (CO) 24 hrs after LPS administration. 4F treatment reduced plasma levels of inflammatory mediators and increased LV filling, resulting in improved cardiac performance. Chromatographic separation of lipoproteins from plasma of vehicle, LPS and LPS+4F rats revealed similar profiles. Further analyses showed that LPS treatment reduced the agarose electrophoretic mobility of isolated HDL fractions. HDL-associated proteins were characterized by SDSPAGE and mass spectrometry. ApoA-I and apoA-IV were reduced while apoE content was increased in LPStreated rats. 4F treatment in vivo attenuated changes in HDL-associated apolipoproteins and increased the electrophoretic mobility of the particle. CONCLUSIONS: The ability of 4F to reduce inflammation and improve cardiac performance in LPS-treated rats may be due to its capacity to neutralize endotoxin and prevent adverse changes in HDL composition and function.

Docosahexaenoic acid suppresses apolipoprotein A-I gene expression through hepatocyte nuclear factor-3β

BACKGROUND

Dietary fish-oil supplementation has been shown in human kinetic studies to lower the production rate of apolipoprotein (apo) A-I, the major protein component of HDL. The underlying mechanism responsible for this effect is not fully understood.

OBJECTIVE

We investigated the effect and the mechanism of action of the very-long-chain n-3 (omega-3) polyunsaturated fatty acid docosahexaenoic acid (DHA), relative to the saturated fatty acid palmitic acid (PA), on the hepatic expression of apo A-I in HepG2 cells.

DESIGN

HepG2 cells were treated with different doses of DHA and PA (0-200 μmol/L). mRNA expression levels of apo A-I were assessed by real-time polymerase chain reaction, and apo A-I protein concentrations were measured by immunoassay. DHA dose-dependently suppressed apo A-I mRNA levels and also lowered apo A-I protein concentrations in the media, with maximum effects at 200 μmol/L. This concentration of fatty acids was used in all subsequent experiments.

RESULTS

To elucidate the mechanism mediating the reduction in apo A-I expression by DHA, transfection experiments were conducted with plasmid constructs containing serial deletions of the apo A-I promoter. The DHA-responsive region was mapped to the -185 to -148 nucleotide region of the apo A-I promoter, which binds the hepatocyte nuclear factor (HNF)-3β. Nuclear extracts from cells treated with DHA or PA had a similar nuclear abundance of HNF-3β. However, electrophoresis mobility shift assays showed less binding of HNF-3β to the -180 to -140 sequence of the apo A-I promoter than did PA-treated cells. As shown by chromatin immunoprecipitation analysis, less HNF-3β was recruited to the apo A-I promoter in DHA-treated cells than in PA-treated cells, which supports the concept of an interference of DHA with the binding of HNF-3β to the apo A-I promoter.

CONCLUSION

These findings suggest that, in human hepatoma HepG2 cells, DHA inhibits the binding of HNF-3β to the apo A-I promoter, resulting in the repression of apo A-I promoter transactivity and thus a reduction in apo A-I expression.

Emerging therapies for atherosclerosis prevention and management

Atherosclerosis is a chronic immunoinflammatory disease involving medium and large arteries, resulting from a complex interaction between genetic and environmental risk factors. Acute atherosclerotic vascular disease largely results from thrombosis that supervenes on a disrupted atherosclerotic plaque. A healthy lifestyle coupled with management of modifiable risk factors reduces the adverse clinical consequences of atherothrombosis. Reducing low-density lipoprotein cholesterol levels using statins and other agents is the primary pharmacologic approach to stabilize atherosclerosis, but a large residual risk burden remains, stimulating the search for additional therapies for atherosclerosis management. This review focuses on new and emerging therapeutic strategies targeting atherosclerosis.

Conformation of dimeric apolipoprotein A-I milano on recombinant lipoprotein particles

Apolipoprotein A-I Milano (apoA-I(Milano)) is a naturally occurring human mutation of wild-type apolipoprotein A-I (apoA-I(WT)) having cystine substituted for arginine(173). Two molecules of apo-I(WT) form disks with phospholipid having a defined relationship between the apoA-I(WT) molecules. ApoA-I(Milano) forms cystine homodimers that would not allow the protein to adopt the conformation reported for apoA-I(WT). The conformational constraints for dimeric apoA-I(Milano) recombinant high-density lipoprotein (rHDL) disks made with phospholipid were deduced from a combination of chemical cross-linking and mass spectrometry. Lysine-selective homobifunctional cross-linkers were reacted with homogeneous rHDL having diameters of 78 and 125 A. After reduction, cross-linked apoA-I(Milano) was separated from monomeric apoprotein by gel electrophoresis and then subjected to in-gel trypsin digest. Cross-linked peptides were confirmed by MS/MS sequencing. The cross-links provided distance constraints that were used to refine models of lipid-bound dimeric apoA-I(Milano). These studies suggest that a single dimeric apoA-I(Milano) on 78 A diameter rHDL girdles the edge of a phospholipid disk assuming a "belt" conformation similar to the "belt" region of apoA-I(WT) on rHDL. However, the C-terminal end of dimeric apoA-I(Milano) wraps around the periphery of the particle to shield the fatty acid chains from water rather than folding back onto the "belt" as does apoA-I(WT). The two apoA-I(Milano) dimers on a 125 A diameter rHDL do not encircle the periphery of a phospholipid disk but appear to reside on the surface of a laminar micelle.

Novel potent apoA-I peptide mimetics that stimulate cholesterol efflux and pre-beta particle formation in vitro

Reverse cholesterol transport (RCT) is believed to be the primary mechanism by which HDL and its major protein apoA-I protect against atherosclerosis. Starting from the inactive 22-amino acid peptide representing the consensus sequence of the class A amphipathic helical repeats of apoA-I, we designed novel peptides able to mobilize cholesterol from macrophages in vitro, and to stimulate the formation of 'nascent HDL' particles, with potency comparable to the entire apoA-I protein.

Splenomegaly with sea-blue histiocytosis, dyslipidemia, and nephropathy in a patient with lecithin-cholesterol acyltransferase deficiency: a clinicopathologic correlation

A 31-year-old man with no significant medical history presented with a 5-day history of progressive left upper quadrant abdominal pain. Physical examination revealed a tender guarded abdomen, no icterus, and bilateral corneal "arcus senilis"-like changes. Laboratory workup showed a mild normocytic, normochromic anemia; and target cells were seen in the peripheral blood smear. Serum was turbid; and the lipid profile showed elevated total cholesterol, low high-density lipoprotein cholesterol, and elevated triglycerides. Urinalysis revealed nephrotic range proteinuria with microhematuria. An abdominal computed tomographic scan demonstrated a homogeneously enlarged spleen. The patient was discharged after symptomatic treatment to be followed as an ambulatory patient. Several days later, he returned with severe left upper quadrant pain and was admitted to the surgical service for further evaluation. A splenectomy was performed for a suspected splenic lymphoma. Upon gross examination, spleen was moderately enlarged, weighing 780 g. Sectioning revealed a beefy red cut surface without gross lesions. Wright-Giemsa-stained touch imprints showed many sea-blue histiocytes. A renal biopsy was also performed, demonstrating focal segmental glomerular sclerosis and mesangial expansion with extramembranous and intramembranous deposition of lipids. In the absence of hematologic malignancy and in light of the abnormal lipid profile, a disorder of lipid metabolism was suspected. Histologic and ultrastructural findings in the kidney and spleen raised the likelihood of lecithin-cholesterol acyltransferase (LCAT) deficiency, which was confirmed by the markedly decreased serum LCAT activity and serum LCAT mass. We describe a case with the triad of splenomegaly with sea-blue histiocytes, nephropathy, and dyslipidemia in a patient with LCAT deficiency.

Atherogenesis and atherothrombosis--focus on diabetes mellitus

Diabetes mellitus represents a major cause of cardiovascular morbidity and mortality in developed countries, and atherothrombosis accounts for most deaths among patients with diabetes mellitus. Atherothrombosis is defined as atherosclerotic lesion disruption with superimposed thrombus formation. As a long-term, progressive disease process, atherosclerosis often results in an acute atherothrombotic event through plaque rupture and formation of a platelet-rich thrombus. The principal clinical manifestations of atherothrombosis are sudden cardiac death, myocardial infarction, ischaemic stroke, and peripheral arterial ischaemia comprising both intermittent claudication and critical limb ischaemia. Atherosclerosis is the leading cause of morbidity and mortality in the industrialized world, and diabetes mellitus magnifies the risk of cardiovascular events. In addition to the well-known microvascular complications of diabetes mellitus - such as nephropathy, retinopathy and neuropathy - the risk of macrovascular complications affecting the large conduit arteries markedly increases in patients with diabetes mellitus.

High density lipoprotein cholesterol: an evolving target of therapy in the management of cardiovascular disease

Since the pioneering work of John Gofman in the 1950s, our understanding of high density lipoprotein cholesterol (HDL-C) and its relationship to coronary heart disease (CHD) has grown substantially. Numerous clinical trials since the Framingham Study in 1977 have demonstrated an inverse relationship between HDL-C and one’s risk of developing CHD. Over the past two decades, preclinical research has gained further insight into the nature of HDL-C metabolism, specifically regarding the ability of HDL-C to promote reverse cholesterol transport (RCT). Recent attempts to harness HDL’s ability to enhance RCT have revealed the complexity of HDL-C metabolism. This review provides a detailed update on HDL-C as an evolving therapeutic target in the management of cardiovascular disease.

Beyond high-density lipoprotein cholesterol levels evaluating high-density lipoprotein function as influenced by novel therapeutic approaches

A number of therapeutic strategies targeting high-density lipoprotein (HDL) cholesterol and reverse cholesterol transport are being developed to halt the progression of atherosclerosis or even induce regression. However, circulating HDL cholesterol levels alone represent an inadequate measure of therapeutic efficacy. Evaluation of the potential effects of HDL-targeted interventions on atherosclerosis requires reliable assays of HDL function and surrogate markers of efficacy. Promotion of macrophage cholesterol efflux and reverse cholesterol transport is thought to be one of the most important mechanisms by which HDL protects against atherosclerosis, and methods to assess this pathway in vivo are being developed. Indexes of monocyte chemotaxis, endothelial inflammation, oxidation, nitric oxide production, and thrombosis reveal other dimensions of HDL functionality. Robust, reproducible assays that can be performed widely are needed to move this field forward and permit effective assessment of the therapeutic potential of HDL-targeted therapies.

Emerging HDL-based therapies for atherothrombotic vascular disease

Statin therapy has been a significant advance in the management of dyslipidemia and atherothrombotic cardiovascular disease with a resultant 30% to 40% reduction in cardiovascular events; however, a significant number of events continue to occur in statin-treated patients, including in patients treated with high-dose statins targeted to achieve mean low-density lipoprotein cholesterol levels in the range of 60 to 80 mg/dL. Therefore, development and testing of new therapies that exploit the vascular protective effects of high-density lipoprotein (HDL) constitutes a rational and complementary approach. A number of HDL-based therapies are in various stages of development and testing. It is hoped that one or more of these new HDL-based therapies, if proven effective and safe, will become a part of our armamentarium against vaso-occlusive cardiovascular disease. A paradigm could emerge in which patients recovering from acute coronary syndromes and at high risk of recurrent events could be treated with rapid-acting HDL-based therapy, such as infusions of recombinant HDL or even HDL delipidation, followed by more sustained long-term HDL-based therapies, such as oral agents and perhaps even HDL-based gene therapy.

Differences in dyslipidemia between American and Italian women with polycystic ovary syndrome

BACKGROUND

Dyslipidemia is a common metabolic complication in polycystic ovary syndrome (PCOS). The aim of this study was to determine if differences exist in dyslipidemia in women with PCOS from different ethnic and geographical backgrounds.

METHODS

This retrospective study evaluated the serum fasting lipid profiles of 106 women with PCOS from the United States and 108 women with PCOS from Italy evaluated at endocrinology clinics.

RESULTS

American women had higher mean body mass index than Italian women (36.1+/-8.6 vs 28.1+/-5.8 kg/m2, p<0.01). Low HDL-cholesterol was the most prevalent lipid abnormality in both populations. U.S. women had higher mean levels of serum total cholesterol, LDL-cholesterol, and triglycerides, and lower mean serum HDL-cholesterol. Most of these differences were due to differences in weight. After controlling for differences in weight and age, fasting serum triglycerides remained higher in U.S. women compared with Italian women [131.1 mg/dl, SE=7.8, 95% confidence interval =(115.7, 146.5) vs 99.3, SE=8.4, 95% confidence interval =(82.9, 115.8)].

CONCLUSIONS

Variations in body weight alone do not fully explain differences in dyslipidemia in women of diverse ethnic and geographical backgrounds. Genetic and environmental factors, such as diet and activity level, likely contribute to these differences.

High-density lipoprotein mimetics: focus on synthetic high-density lipoprotein

Epidemiologic studies show an inverse relation between high-density lipoprotein (HDL) cholesterol levels and coronary artery disease, and proof-of-concept experimental studies suggest that HDL and its apolipoproteins, specifically apolipoprotein (apo) A-I , have atheroprotective effects. Atheroprotective effects of HDL are attributed to its ability to remove macrophage cholesterol by stimulating reverse cholesterol transport as well as anti-inflammatory and antioxidant effects. Several different strategies are currently being pursued to exploit the vascular-protective effects of HDL. One such approach involves direct administration of synthetic reconstituted HDL made from linking phospholipid carriers with recombinant mutant apoA-I or plasma-derived wild-type apoA-I.

Immunization for atherosclerosis

This review summarizes experimental findings that highlight the complex roles of the immune system in atherogenesis. Immune activation can have either proatherogenic or atheroprotective effects. Immune-modulation therapy via an active or passive immunization strategy aims to exploit the atheroprotective aspects of the immune system to modulate atherosclerosis. Several experimental studies have demonstrated that such an approach is feasible and effective, raising the tantalizing possibility that an atheroprotective vaccine can be developed for clinical testing. Several potential immunogens have been identified and tested for their atheroprotective efficacy with variable results. Although several questions such as choice of optimal antigens, choice of most effective adjuvants, the optimal route of administration, durability of effects, and safety remain to be answered, we believe that a vaccine-based approach to manage atherosclerotic cardiovascular disease is a potentially viable paradigm.

Effect of torcetrapib on the progression of coronary atherosclerosis

BACKGROUND

Levels of high-density lipoprotein (HDL) cholesterol are inversely related to cardiovascular risk. Torcetrapib, a cholesteryl ester transfer protein (CETP) inhibitor, increases HDL cholesterol levels, but the functional effects associated with this mechanism remain uncertain.

METHODS

A total of 1188 patients with coronary disease underwent intravascular ultrasonography. After treatment with atorvastatin to reduce levels of low-density lipoprotein (LDL) cholesterol to less than 100 mg per deciliter (2.59 mmol per liter), patients were randomly assigned to receive either atorvastatin monotherapy or atorvastatin plus 60 mg of torcetrapib daily. After 24 months, disease progression was measured by repeated intravascular ultrasonography in 910 patients (77%).

RESULTS

After 24 months, as compared with atorvastatin monotherapy, the effect of torcetrapib-atorvastatin therapy was an approximate 61% relative increase in HDL cholesterol and a 20% relative decrease in LDL cholesterol, reaching a ratio of LDL cholesterol to HDL cholesterol of less than 1.0. Torcetrapib was also associated with an increase in systolic blood pressure of 4.6 mm Hg. The percent atheroma volume (the primary efficacy measure) increased by 0.19% in the atorvastatin-only group and by 0.12% in the torcetrapib-atorvastatin group (P=0.72). A secondary measure, the change in normalized atheroma volume, showed a small favorable effect for torcetrapib (P=0.02), but there was no significant difference in the change in atheroma volume for the most diseased vessel segment.

CONCLUSIONS

The CETP inhibitor torcetrapib was associated with a substantial increase in HDL cholesterol and decrease in LDL cholesterol. It was also associated with an increase in blood pressure, and there was no significant decrease in the progression of coronary atherosclerosis. The lack of efficacy may be related to the mechanism of action of this drug class or to molecule-specific adverse effects. (ClinicalTrials.gov number, NCT00134173 [ClinicalTrials.gov].).

Emerging strategies for increasing high-density lipoprotein

High-density lipoprotein cholesterol is a potent and independent epidemiologic risk factor and is a proved antiatherosclerotic agent in animal models of atherosclerosis, acting through the principal mechanisms of accelerating cholesterol efflux and inhibiting oxidation and inflammation. Lifestyle modification increases serum levels by 5% to 15%, whereas niacin, the drug most widely used to increase high-density lipoprotein cholesterol, increases it by 25% to 35% at the highest doses. This review examines the potent methods of increasing high-density lipoprotein and/or enhancing reverse cholesterol transport, including cholesterol ester transfer protein inhibitors, apolipoprotein A-I Milano, D4F, the dual peroxisome proliferator-activated receptor agonists, and rimonabant, that are now in clinical trials. In conclusion, these new agents, used alone or in combination with existing therapies, carry the potential to markedly reduce the incidence of new coronary disease and cardiac events in this decade.

Human apoA-I expression in CETP transgenic rats leads to lower levels of apoC-I in HDL and to magnification of CETP-mediated lipoprotein changes

Plasma cholesteryl ester transfer protein (CETP) has a profound effect on neutral lipid transfers between HDLs and apolipoprotein B (apoB)-containing lipoproteins when it is expressed in combination with human apoA-I in HuAI/CETP transgenic (Tg) rodents. In the present study, human apoA-I-mediated lipoprotein changes in HuAI/CETPTg rats are characterized by 3- to 5-fold increments in the apoB-containing lipoprotein-to-HDL cholesterol ratio, and in the cholesteryl ester-to-triglyceride ratio in apoB-containing lipoproteins. These changes occur despite no change in plasma CETP concentration in HuAI/CETPTg rats, as compared with CETPTg rats. A number of HDL apolipoproteins, including rat apoA-I and rat apoC-I are removed from the HDL surface as a result of human apoA-I overexpression. Rat apoC-I, which is known to constitute a potent inhibitor of CETP, accounts for approximately two-thirds of CETP inhibitory activity in HDL from wild-type rats, and the remainder is carried by other HDL-bound apolipoprotein inhibitors. It is concluded that human apoA-I overexpression modifies HDL particles in a way that suppresses their ability to inhibit CETP. An apoC-I decrease in HDL of HuAI/CETPTg rats contributes chiefly to the loss of the CETP-inhibitory potential that is normally associated with wild-type HDL.

High-density lipoprotein cholesterol therapies: the next frontier in lipid management

Current cholesterol treatment guidelines target low-density lipoprotein cholesterol as the primary goal of therapy and recommend statins as first line therapy. However, despite aggressive treatment and success at reaching the recommended goals, coronary heart disease is still a leading cause of morbidity and mortality. Thus, other lipoproteins, such as high-density lipoprotein, are now being looked to as the next promising targets of therapy to help reduce the burden of coronary heart disease and atherosclerosis. This review details currently available strategies to raise high-density lipoprotein cholesterol, and then turns to several new compounds in development that target the varying components of the complex metabolism of high-density lipoprotein.

Atherothrombosis and high-risk plaque: part I: evolving concepts

Atherothrombosis is a complex disease in which cholesterol deposition, inflammation, and thrombus formation play a major role. Rupture of high-risk, vulnerable plaques is responsible for coronary thrombosis, the main cause of unstable angina, acute myocardial infarction, and sudden cardiac death. In addition to rupture, plaque erosion may also lead to occlusive thrombosis and acute coronary events. Atherothrombosis can be evaluated according to histologic criteria, most commonly categorized by the American Heart Association (AHA) classification. However, this classification does not include the thin cap fibroatheroma, the most common form of high-risk, vulnerable plaque. Furthermore, the AHA classification does not include plaque erosion. As a result, new classifications have emerged and are reviewed in this article. The disease is asymptomatic during a long period and dramatically changes its course when complicated by thrombosis. This is summarized in five phases, from early lesions to plaque rupture, followed by plaque healing and fibrocalcification. For the early phases, the role of endothelial dysfunction, cholesterol transport, high-density lipoprotein, and proteoglycans are discussed. Furthermore, the innate and adaptive immune response to autoantigens, the Toll-like receptors, and the mechanisms of calcification are carefully analyzed. For the advanced phases, the role of eccentric remodeling, vasa vasorum neovascularization, and mechanisms of plaque rupture are systematically evaluated. In the final thrombosis section, focal and circulating tissue factor associated with apoptotic macrophages and circulatory monocytes is examined, closing the link between inflammation, plaque rupture, and blood thrombogenicity.

Inflammatory markers and serum lipids in idiopathic dilated cardiomyopathy

Coronary microcirculation is impaired in idiopathic dilated cardiomyopathy (IDC), possibly because of endothelial dysfunction. High-density lipoproteins (HDLs) have the potential to regulate endothelial function and modulate inflammation and the innate immune response. This study investigated whether reduced HDLs, concomitantly with the activation of inflammation, are associated with IDC. Fifty-five patients with IDC, without evidence of other organ or systemic, chronic, or recurrent diseases, were compared with 55 healthy controls for HDLs and complete lipid profiles, C-reactive protein, C3 and C4 complement fractions, soluble intercellular adhesion molecule-1 and soluble endothelial leukocyte adhesion molecule-1, haptoglobin, and ceruloplasmin. Patients with IDC differed from controls, with lower HDL levels, lower apolipoprotein A-I and A-II levels, and higher triglyceride levels, but not on total and low-density lipoprotein cholesterol, apolipoprotein B, or lipoprotein(a). In addition, all measured inflammation markers were significantly greater in patients with IDC than in controls and were negatively correlated with HDLs. A strong and independent association with IDC was found for age, soluble intercellular adhesion molecule-1, and HDLs that, when categorized as <40 or >40 mg/dl, showed the strongest association (prevalence odds ratio 0.10, p <0.0005) with the disease. In conclusion, the data here reported on reduced HDLs and increased endothelial inflammatory activation and the linear negative correlation between HDLs and inflammation markers, particularly soluble intercellular adhesion molecule-1, could suggest a role for HDLs in the endothelial-microvascular dysfunction seen in IDC.

Apolipoprotein A-I Mimetic Peptides: Potential Role in Atherosclerosis Management

Atherothrombotic vascular disease continues to be a leading cause of morbidity and mortality in much of the world. Although a healthy lifestyle and low-density lipoprotein cholesterol lowering significantly reduce cardiovascular morbidity and mortality, substantial number of adverse vasoocclusive events continue to occur. These realities have brought attention to additional therapies that could further reduce cardiovascular events. High-density lipoprotein (HDL)/apolipoprotein A-I (apo A-I)-based therapies are a potential therapeutic strategy against atherothrombotic vascular disease because of the known inverse relationship between HDL cholesterol and coronary heart disease, favorable and pleotrophic biologic effects of HDL/apo A-I, results of preclinical experimental studies, and emerging proof of concept in clinical studies. A variety of HDL/apo A-I-based therapies are currently under investigation, including synthetic peptides that mimic the function of HDL. Such apo A-I mimetic peptides are the focus of this review.

The role of shear stress in the destabilization of vulnerable plaques and related therapeutic implications

American Heart Association type IV plaques consist of a lipid core covered by a fibrous cap, and develop at locations of eccentric low shear stress. Vascular remodeling initially preserves the lumen diameter while maintaining the low shear stress conditions that encourage plaque growth. When these plaques eventually start to intrude into the lumen, the shear stress in the area surrounding the plaque changes substantially, increasing tensile stress at the plaque shoulders and exacerbating fissuring and thrombosis. Local biologic effects induced by high shear stress can destabilize the cap, particularly on its upstream side, and turn it into a rupture-prone, vulnerable plaque. Tensile stress is the ultimate mechanical factor that precipitates rupture and atherothrombotic complications. The shear-stress-oriented view of plaque rupture has important therapeutic implications. In this review, we discuss the varying mechanobiologic mechanisms in the areas surrounding the plaque that might explain the otherwise paradoxical observations and unexpected outcomes of experimental therapies.

Oxidation, lipoproteins, and atherosclerosis: which is wrong, the antioxidants or the theory?

PURPOSE OF REVIEW

Paradoxically, many well-established components of the heart-healthy lifestyle are pro-oxidant, including polyunsaturated fat and moderate alcohol consumption. Moreover, antioxidant supplements have failed to decrease cardiovascular risk in extensive human clinical trials to date. Recent progress in understanding the roles of oxidants in regulating VLDL secretion and as essential signaling molecules supports the concept that oxidation may be beneficial in certain circumstances but damaging in others. We summarize recent data on the roles played by oxidative metabolism in different tissues and pathways, and address whether it is currently advisable to use antioxidant supplements to reduce cardiovascular risk.

RECENT FINDINGS

Our recent study reported that in liver cells, polyunsaturated fatty acids increased reactive oxygen species, which in turn lowered the secretion of the atherogenic lipoprotein, VLDL, in vitro and in vivo. Antioxidant treatments prevented VLDL-lowering effects of polyunsaturated fatty acids in vitro, suggesting that supplemental antioxidants could either raise apolipoprotein-B-lipoprotein plasma levels in vivo, or impair the response to lipid-lowering therapies. The failure of antioxidants to decrease cardiovascular disease risk in many trials is also discussed in the context of current models for atherosclerosis progression and regression.

SUMMARY

Oxidation includes distinct biochemical reactions, and it is overly simplistic to lump them into a unitary process that affects all cell types and metabolic pathways adversely. Guidelines for diet should adhere closely to what has been clinically proved, and by this standard there is no basis to recommend antioxidant use, beyond what is inherent to the 'heart healthy' diet in order to benefit cardiovascular health.

Inhibition of cholesteryl ester transfer protein activity: a new therapeutic approach to raising high-density lipoprotein

High-density lipoprotein (HDL) cholesterol levels are inversely associated with risk of atherosclerotic cardiovascular disease (ASCVD), leading to the concept that pharmacologic therapy to raise HDL cholesterol levels may reduce ASCVD risk. There is substantial interest in the concept of inhibition of the cholesteryl ester transfer protein (CETP) as a novel strategy for raising HDL cholesterol levels, as well as reducing levels of atherogenic lipoproteins. This article reviews the physiology of CETP in lipoprotein metabolism and the data in animals and humans that are relevant to the question of whether CETP inhibition may some day be part of the clinical armamentarium for treating dyslipidemia and atherosclerotic vascular disease.

Pharmacologic strategies for the prevention of atherosclerotic plaque progression

Despite improved treatment options, coronary artery disease remains the leading cause of death in men and women in industrialized societies. Reduction of atherosclerotic disease will require the development and evaluation of new classes of pharmacologic agents capable of modifying the development and progression of the atherosclerotic disease process. The direct observation of coronary plaque burden and morphology with in vivo imaging modalities has been evaluated as an end point in serial pharmacologic intervention trials. This review will describe the use of intravascular ultrasound for such studies, summarize results from recent trials and outline potential future pharmacologic targets.

Addressing cardiovascular risk beyond low-density lipoprotein cholesterol: the high-density lipoprotein cholesterol story

A large body of evidence from numerous, well-controlled, randomized trials demonstrates that treatment with statins reduce morbidity and mortality from cardiovascular disease (CVD). Although these observations are important and have resulted in the adoption of standard of care approaches to the management of CVD risk, they do not tell the whole story. When reviewing these landmark trials it is clear that on average two thirds of events are not prevented. This leads to the evaluation of risk beyond low-density lipoprotein cholesterol. This review focuses on the association of low high-density lipoprotein (HDL) cholesterol and increased CVD risk, the published trials that study the effect of raising HDL cholesterol on CVD outcomes, and the novel approaches toward HDL cholesterol raising that are on the horizon.