HDL metabolism and CETP inhibition

Unlocking Cholesterol Metabolism in Metabolic-Associated Steatotic Liver Disease: Molecular Targets and Natural Product Interventions

Metabolic-associated steatotic liver disease (MASLD), the hepatic manifestation of metabolic syndrome, represents a growing global health concern. The intricate pathogenesis of MASLD, driven by genetic, metabolic, epigenetic, and environmental factors, leads to considerable clinical variability. Dysregulation of hepatic lipid metabolism, particularly cholesterol homeostasis, is a critical factor in the progression of MASLD and its more severe form, metabolic dysfunction-associated steatohepatitis (MASH). This review elucidates the multifaceted roles of cholesterol metabolism in MASLD, focusing on its absorption, transportation, biosynthesis, efflux, and conversion. We highlight recent advancements in understanding these processes and explore the therapeutic potential of natural products such as curcumin, berberine, and resveratrol in modulating cholesterol metabolism. By targeting key molecular pathways, these natural products offer promising strategies for MASLD management. Finally, this review also covers the clinical studies of natural products in MASLD, providing new insights for future research and clinical applications.

Precision Nutrition and Cardiovascular Disease Risk Reduction: the Promise of High-Density Lipoproteins

PURPOSE OF REVIEW

Emerging evidence supports the promise of precision nutritional approaches for cardiovascular disease (CVD) prevention. Here, we discuss current findings from precision nutrition trials and studies reporting substantial inter-individual variability in responses to diets and dietary components relevant to CVD outcomes. We highlight examples where early precision nutrition research already points to actionable intervention targets tailored to an individual's biology and lifestyle. Finally, we make the case for high-density lipoproteins (HDL) as a compelling next generation target for precision nutrition aimed at CVD prevention. HDL possesses complex structural features including diverse protein components, lipids, size distribution, extensive glycosylation, and interacts with the gut microbiome, all of which influence HDL's anti-inflammatory, antioxidant, and cholesterol efflux properties. Elucidating the nuances of HDL structure and function at an individual level may unlock personalized dietary and lifestyle strategies to optimize HDL-mediated atheroprotection and reduce CVD risk.

RECENT FINDINGS

Recent human studies have demonstrated that HDL particles are key players in the reduction of CVD risk. Our review highlights the role of HDL and the importance of personalized therapeutic approaches to improve their potential for reducing CVD risk. Factors such as diet, genetics, glycosylation, and gut microbiome interactions can modulate HDL structure and function at the individual level. We emphasize that fractionating HDL into size-based subclasses and measuring particle concentration are necessary to understand HDL biology and for developing the next generation of diagnostics and biomarkers. These discoveries underscore the need to move beyond a one-size-fits-all approach to HDL management. Precision nutrition strategies that account for personalized metabolic, genetic, and lifestyle data hold promise for optimizing HDL therapies and function to mitigate CVD risk more potently. While human studies show HDL play a key role in reducing CVD risk, recent findings indicate that factors such as diet, genetics, glycosylation, and gut microbes modulate HDL function at the individual level, underscoring the need for precision nutrition strategies that account for personalized variability to optimize HDL's potential for mitigating CVD risk.

HDL-Based Therapy: Vascular Protection at All Stages

It is known that lipid metabolism disorders are involved in a wide range of pathologies. These pathologies include cardiovascular, metabolic, neurodegenerative diseases, and even cancer. All these diseases lead to serious health consequences, which makes it impossible to ignore them. Unfortunately, these diseases most often have a complex pathogenesis, which makes it difficult to study them and, in particular, diagnose and treat them. HDL is an important part of lipid metabolism, performing many functions under normal conditions. One of such functions is the maintaining of the reverse cholesterol transport. These functions are also implicated in pathology development. Thus, HDL contributes to vascular protection, which has been demonstrated in various conditions: Alzheimer’s disease, atherosclerosis, etc. Many studies have shown that serum levels of HDL cholesterol correlate negatively with CV risk. With these data, HDL-C is a promising therapeutic target. In this manuscript, we reviewed HDL-based therapeutic strategies that are currently being used or may be developed soon.

Harnessing the cyclization strategy for new drug discovery

The design of new ligands with high affinity and specificity against the targets of interest has been a central focus in drug discovery. As one of the most commonly used methods in drug discovery, the cyclization represents a feasible strategy to identify new lead compounds by increasing structural novelty, scaffold diversity and complexity. Such strategy could also be potentially used for the follow-on drug discovery without patent infringement. In recent years, the cyclization strategy has witnessed great success in the discovery of new lead compounds against different targets for treating various diseases. Herein, we first briefly summarize the use of the cyclization strategy in the discovery of new small-molecule lead compounds, including the proteolysis targeting chimeras (PROTAC) molecules. Particularly, we focus on four main strategies including fused ring cyclization, chain cyclization, spirocyclization and macrocyclization and highlight the use of the cyclization strategy in lead generation. Finally, the challenges including the synthetic intractability, relatively poor pharmacokinetics (PK) profiles and the absence of the structural information for rational structure-based cyclization are also briefly discussed. We hope this review, not exhaustive, could provide a timely overview on the cyclization strategy for the discovery of new lead compounds.

2D QSAR studies on a series of (4S,5R)-5-[3,5-bis(trifluoromethyl)phenyl]-4-methyl-1,3-oxazolidin-2-one as CETP inhibitors

Cardiovascular disease (CVD) is one of the major causes of human death. Preliminary evidence indicates that the inhibition treatment of Cholesteryl Ester Transfer Protein (CETP) causes the most pronounced increase in HDL cholesterol reported so far. Merck has disclosed certain (4S,5R)-5-[3,5-bis(trifluoromethyl)phenyl]-4-methyl-1,3-oxazolidin-2-one derivatives, which show potent CETP inhibitory activity. Therefore, it would be desirable to develop computational models to facilitate the screening of these inhibitors. In the present work, quantitative structure-activity relationship (QSAR) models have been developed to predict the therapeutic potency of 108 derivatives of (4S,5R)-5-[3,5-bis(trifluoromethyl)phenyl]-4-methyl-1,3-oxazolidin-2-one: Multiple Linear Regression (MLR), Support Vector Regression (SVR) and Feedforward Neural Network using Particle Swarm Optimization (FNN-PSO). Six descriptors were selected using genetic algorithms, whereas, internal and external validation of the models was performed according to all available validation strategies. It was shown that CETP inhibitory activity is mainly governed by electronegativity, the structure of the molecule, and the electronic properties. The best results were obtained with the SVR model. The results obtained may assist in the design of new CETP inhibitors.

Cuban Sugar Cane Wax Acid and Policosanol Showed Similar Atheroprotective Effects with Inhibition of LDL Oxidation and Cholesteryl Ester Transfer via Enhancement of High-Density Lipoproteins Functionality

Background

Cuban sugarcane wax acids (SCWA) and policosanol (PCO) are mixtures of higher aliphatic acids and alcohols, respectively, purified from sugarcane wax with different chief components. Although it has been known that they have antioxidant and anti-inflammatory activities, physiological properties on molecular mechanism of SCWA have been less studied than PCO.

Methods

In this study, we compared antiatherogenic activities of SCWA and PCO via encapsulation with reconstituted high-density lipoproteins (rHDL).

Results

After reconstitution, SCWA-rHDL showed smaller particle size than PCO-rHDL with increase of content. PCO-rHDL or SCWA-rHDL showed distinct inhibition of glycation with similar extent in the presence of fructose. PCO-rHDL or SCWA-rHDL showed strong antioxidant activity against cupric ion-mediated oxidation of low-density lipoproteins (LDL), and inhibition of oxLDL uptake into macrophages. Although PCO-rHDL showed 1.2-fold stronger inhibition against cholesteryl ester transfer protein (CETP) activity than SCWA-rHDL, SCWA-rHDL enhanced 15% more brain cell (BV-2) growth and 23% more regeneration of tail fin in zebrafish.

Conclusion

PCO and SCWA both enhance the beneficial functions of HDL to maximize its antioxidant, antiglycation, and antiatherosclerotic activities and the inhibition of CETP. These enhancements of HDL functionality by PCO and SCWA could exert antiaging and rejuvenation activity.

Genetic Identification for Non-Communicable Disease: Findings from 20 Years of the Tehran Lipid and Glucose Study

CONTEXT

Tehran Lipid and Glucose Study (TLGS), a longitudinal family based cohort study, is the oldest and largest longitudinal family based study in Iran, aimed at investigating effects of environmental, social and biological factors on the health of Tehranians over time. Considering the importance of genetic studies in this aspect, here we present a summary of the important genetic findings, and the potentiality of their contributions to future related projects.

EVIDENCE ACQUISITION

For all related studies during the past 20 years the search sources were all prominent search engines such as PubMed, Scopus, and Google Scholar with the most proper Medical Subject Headings (MeSH).

RESULTS

This review summarizes associations of 6 binary phenotypes and 17 quantitative traits with genetic markers in 26 genes. Of the 47 genetic markers, studied most were related to cardio metabolic risk factors. Results of heritability and linkage analysis were also collected and the highest heritability was found to be related to HDL-C (0.5).

CONCLUSION

Considering the opportunity provided by large-scale cohort studies to investigate molecular effects of genetic variants on causality and different omics' data, genetic studies conducted on TLGS population have had a remarkable success in identifying genetic variants that facilitating a unique genetic database on Iranian populations. The results of genome wide association studies in this population are currently facilitating investigations to define the Iranian genetic differences with other population.

How cholesteryl ester transfer protein can also be a potential triglyceride transporter

CETP transfers cholesteryl esters (CEs) and triglycerides (TGs) between different lipoproteins and came in limelight as a drug-target against CVD. In the search for detailed mechanism of lipid transfer through CETP, enormous effort is devoted employing crystallographic, cryo-EM, and Molecular Dynamics (MD) studies. However, these studies primarily focused on CE-bound CETP structure and CE transfer mechanism. With the reported correlation that CETP looses significant CE transfer activity upon inhibiting TG transfer, it is of tremendous importance to understand the structure and dynamics of TG-bound CETP. Our results from large-scale all-atom and coarse-grained MD simulations show that CETP can accommodate two TG molecules in parallel N-N orientation with TG oleate chains majorly attaining the tuning-fork conformation. In TG-bound form, CETP not only maintained its secondary structures but also exhibited similar bending-twisting motions as reported for CE-CETP crystal structure. Obtained structural information are further validated by correlating to available functional data of 2-8 fold slower transfer rate of TG through CETP, where we show that TGs make 20% additional contacts with CETP compared to CEs. Identified CETP residues facilitating TG binding also match very well with reported mutagenesis data. The study could accelerate the drug-designing processes to combat CETP functionality and CVD.

c.*84G>A Mutation in CETP Is Associated with Coronary Artery Disease in South Indians

BACKGROUND

Coronary artery disease (CAD) is one of the leading causes of mortality worldwide. It is a multi-factorial disease and several studies have demonstrated that the genetic factors play a major role in CAD. Although variations in cholesteryl ester transfer protein (CETP) gene are reported to be associated with CAD, this gene has not been studied in South Indian populations. Hence we evaluated the CETP gene variations in CAD patients of South Indian origin.

METHODS

We sequenced all the exons, exon-intron boundaries and UTRs of CETP in 323 CAD patients along with 300 ethnically and age matched controls. Variations observed in CETP were subjected to various statistical analyses.

RESULTS AND DISCUSSION

Our analysis revealed a total of 13 variations. Of these, one3'UTRvariant rs1801706 (c.*84G>A) was significantly associated with CAD (genotype association test: OR = 2.16, 95% CI: 1.50-3.10, p = 1.88x10-5 and allelic association test: OR = 1.92, 95% CI: 1.40-2.63, p = 2.57x10-5). Mutant allele "A" was observed to influence the higher concentration of mRNA (p = 7.09×10-3, R2 = 0.029 and β = 0.2163). Since expression of CETP has been shown to be positively correlated with the risk of CAD, higher frequency of "A" allele (patients: 22.69% vs.controls: 13%) reveals that c.*84G>A is a risk factor for CAD in South Indians.

CONCLUSIONS

This is the first report of the CETP gene among South Indians CAD patients. Our results suggest that rs1801706 (c.*84G>A) is a risk factor for CAD in South Indian population.

Novel Therapies for Low-Density Lipoprotein Cholesterol Reduction

Although many clinical trials and meta-analyses have demonstrated that lower serum low-density lipoprotein cholesterol (LDL-C) levels are associated with proportionately greater reductions in the risk of cardiovascular disease events, not all patients with hypercholesterolemia are able to attain risk-stratified LDL-C goals with statin monotherapy. Elucidation of the pathophysiology of genetic disorders of lipid metabolism (e.g., familial hypercholesterolemia) has led to the development of several novel lipid-lowering strategies, including blocking the degradation of hepatic LDL-C receptors that are important in LDL-C clearance, or the inhibition of apoprotein synthesis and lipidation. Mipomersen and lomitapide are highly efficacious new agents available for the treatment of patients with homozygous familial hypercholesterolemia. The recent introduction of PCSK9 inhibitors (alirocumab and evolocumab) have made it possible for many patients to achieve very low LDL-C concentrations (e.g., <40 mg/dl) that are usually not attainable with statin monotherapy. Ongoing clinical trials are examining the impact of very low LDL-C levels on cardiovascular disease event rates and the long-term safety of this approach.

Cholesteryl Ester Transfer Protein Inhibitors

The cholesteryl ester transfer protein (CETP) is a plasma protein that plays an important role in the transfer of lipids between plasma lipoproteins. The CETP inhibitors have been widely studied as a pharmacologic therapy to target plasma cholesterol in order to reduce the risk of atherosclerotic cardiovascular disease . Using CETP inhibitors as cholesterol modifiers was based on the genetic research that found correlations between CETP activity and cholesterol levels. Although CETP inhibitors are successful at altering targeted cholesterol markers, recent phase 3 outcome trials have shown limited benefit on cardiovascular outcomes when combined with the current standard of care. We discuss the science of CETP inhibition, compare the CETP inhibitors developed (torcetrapib, evacetrapib, dalcetrapib, and anacetrapib), the findings from the CETP inhibitor trials, and the future outlook for CETP inhibitors in cholesterol modification.

Quality Assessment of Domesticated Animal Genome Assemblies

The era of high-throughput sequencing has made it relatively simple to sequence genomes and transcriptomes of individuals from many species. In order to analyze the resulting sequencing data, high-quality reference genome assemblies are required. However, this is still a major challenge, and many domesticated animal genomes still need to be sequenced deeper in order to produce high-quality assemblies. In the meanwhile, ironically, the extent to which RNAseq and other next-generation data is produced frequently far exceeds that of the genomic sequence. Furthermore, basic comparative analysis is often affected by the lack of genomic sequence. Herein, we quantify the quality of the genome assemblies of 20 domesticated animals and related species by assessing a range of measurable parameters, and we show that there is a positive correlation between the fraction of mappable reads from RNAseq data and genome assembly quality. We rank the genomes by their assembly quality and discuss the implications for genotype analyses.

Discovery of novel N,N-3-phenyl-3-benzylaminopropionanilides as potent inhibitors of cholesteryl ester transfer protein in vivo

Epidemiological studies have identified that the risk of cardiovascular events increases due to the decreased levels of high density lipoprotein-cholesterol and the elevated levels of low density lipoprotein-cholesterol. Herein, we report a novel series of N,N-3-phenyl-3-benzylaminopropionanilide derivatives, which were identified as potent cholesteryl ester transfer protein (CETP) inhibitor. The initial lead compound L10 (IC50 8.06 μM) was found by pharmacophore-based virtual screening (Dong-Mei Zhao et al., Chin. Chem. Lett.2014, 25, 299). After systematic structure variation and biological testing against CETP, two different series were identified as scaffolds for potent CETP inhibitors. One is N,N-3-phenyl-3-benzylaminopropanamide derivatives, which were investigated in our previous paper (Bioorg. Med. Chem.2015, doi: http://dx.doi.org/10.1016/j.bmc.2015.12.010). The most potent compound HL16 in that series has the IC50 of 0.69 μM. The other series is N,N-3-phenyl-3-benzylaminopropionanilide derivatives, which was investigated in current study. Further optimization of the structure-activity relationship (SAR) resulted in H16 (IC50 0.15 μM), which was discovered as a potent CETP inhibitor in vitro by BODIPY-CE fluorescence assay. In addition, the results of pharmacodynamics studies showed that H16 exhibited both favorable HDL-C enhancement and LDL-C reduction in vivo by hamster. It also has an excellent stability in rat liver microsomal.

The Relationship between Very High Levels of Serum High-Density Lipoprotein Cholesterol and Cause-Specific Mortality in a 20-Year Follow-Up Study of Japanese General Population

AIMS

There is no community-based cohort study to examine the effect of very high level of high-density lipoprotein cholesterol (HDL-C) on coronary heart disease (CHD) and other cause-specific mortality. Therefore, we investigated the relationship between HDL-C including very high level and cause-specific mortality in a 20-year cohort study of the representative sample of Japanese.

METHODS

We followed 7,019 individuals from the Japanese general population (2,946 men and 4,073 women). We defined HDL-C levels as follow: low (HDL-C ＜1.04 mmol/L), reference (1.04-1.55 mmol/L), high (1.56-2.06 mmol/L), very high (≥2.07 mmol/L). The multivariate adjusted hazard ratio (HR) for all-cause or cause-specific mortality was calculated using a Cox proportional hazards model adjusted for other traditional risk factors.

RESULTS

During follow-up, we observed 1,598 deaths. No significant association was observed between HDL-C and all-cause mortality. Serum HDL-C also showed no association with stroke. In contrast, the risk for CHD among high HDL-C was lower than reference, HRs were 0.51 [95% confidence interval (CI): 0.21-1.23] in men, 0.33 (95% CI: 0.11-0.95) in women, and 0.41 (95% CI: 0.21-0.81) when men and women were combined. However, very high HDL-C did not show significant association with CHD and other cause-specific mortality.

CONCLUSIONS

HDL-C was not associated with all-cause and stroke mortality. In contrast, high serum HDL-C levels, at least up to 2.06 mmol/L, were protective against CHD, although further high levels were not. However, sample size of cause-specific death in very high HDL-C group was not enough even in this 20-year follow-up of 7,019 Japanese; larger cohort studies should be warranted.

Irbesartan attenuates atherosclerosis in Watanabe heritable hyperlipidemic rabbits: noninvasive imaging of inflammation by 18F-fluorodeoxyglucose positron emission tomography

The purpose of this study was to assess the usefulness of 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) in evaluating the antiatherogenic effects of irbesartan, an angiotensin II type 1 receptor blocker. Watanabe heritable hyperlipidemic rabbits were divided into the irbesartan-treated group (75 mg/kg/d; n  =  14) and the control group (n  =  14). After a 9-month treatment, rabbits underwent 18F-FDG PET. Using the aortic lesions, autoradiography and histologic examinations were performed. PET imaging clearly visualized the thoracic lesions of control rabbits and showed a significant decrease in the 18F-FDG uptake level of irbesartan-treated rabbits (78.8% of controls; p < .05). Irbesartan treatment significantly reduced the plaque size (43.1% of controls) and intraplaque macrophage infiltration level (48.1% of controls). The 18F-FDG uptake level in plaques positively correlated with the plaque size (r  =  .65, p < .05) and macrophage infiltration level (r  =  .57, p < .05). Noninvasive imaging by 18F-FDG PET is useful for evaluating the therapeutic effects of irbesartan and reflects inflammation, a key factor involved in the therapeutic effects.

2D and 3D QSAR models for identifying diphenylpyridylethanamine based inhibitors against cholesteryl ester transfer protein

Cholesteryl ester transfer protein (CETP) inhibitors hold promise as new agents against coronary heart disease. Molecular modeling techniques such as 2D-QSAR and 3D-QSAR analysis were applied to establish models to distinguish potent and weak CETP inhibitors. 2D and 3D QSAR models-based a series of diphenylpyridylethanamine (DPPE) derivatives (newly identified as CETP inhibitors) were then performed to elucidate structural and physicochemical requirements for higher CETP inhibitory activity. The linear and spline 2D-QSAR models were developed through multiple linear regression (MLR) and support vector machine (SVM) methods. The best 2D-QSAR model obtained by SVM gave a high predictive ability (R(2)train=0.929, R(2)test=0.826, Q(2)LOO=0.780). Also, the 2D-QSAR models uncovered that SlogP_VSA0, E_sol and Vsurf_DW23 were important features in defining activity. In addition, the best 3D-QSAR model presented higher predictive ability (R(2)train=0.958, R(2)test=0.852, Q(2)LOO=0.734) based on comparative molecular field analysis (CoMFA). Meanwhile, the derived contour maps from 3D-QSAR model revealed the significant structural features (steric and electronic effects) required for improving CETP inhibitory activity. Consequently, twelve newly designed DPPE derivatives were proposed to be robust and potent CETP inhibitors. Overall, these derived models may help to design novel DPPE derivatives with better CETP inhibitory activity.

Potent cholesteryl ester transfer protein inhibitors of reduced lipophilicity: 1,1'-spiro-substituted hexahydrofuroquinoline derivatives

A series of 1,1'-spiro-substituted hexahydrofuroquinoline derivatives exhibiting potent cholesteryl ester transfer protein (CETP) inhibition at reduced lipophilicity was identified. A focused structure-activity relationship (SAR) exploration led to the potent and comparatively polar CETP inhibitor 26 showing robust high density lipoprotein-cholesterol (HDL-C) elevation and low density lipoprotein-cholesterol (LDL-C) reduction in transgenic hCETP/hApoB-100 mice. Compound 26 was also shown to positively differentiate from highly lipophilic CETP inhibitors in its complete elimination from fat tissue in hCETP transgenic mice as evident within 21 days after cessation of treatment. In addition, compound 26 showed no significant effects on aldosterone secretion from H295R cells, as well as no significant effects on blood pressure and electrocardiogram parameters in telemetrized cynomolgus monkeys.

Effects of cigarette smoking on HDL quantity and function: implications for atherosclerosis

Cigarette smoking has been identified as an independent and preventable risk factor for atherosclerosis and cardiovascular disease. Population studies have shown that plasma high density lipoprotein (HDL) cholesterol levels are inversely related to the risk of developing cardiovascular disease. Cigarette smoking is associated with reduced HDL cholesterol levels. Cigarette smoking can alter the critical enzymes of lipid transport, lowering lecithin: cholesterol acyltransferase (LCAT) activity and altering cholesterol ester transfer protein (CETP) and hepatic lipase activity, which attributes to its impact on HDL metabolism and HDL subfractions distribution. In addition, HDL is susceptible to oxidative modifications by cigarette smoking, which makes HDL become dysfunctional and lose its atheroprotective properties in smokers. Therefore, cigarette smoking has a negative impact on both HDL quantity and function, which can explain, in part, the increased risk of cardiovascular disease in smokers.

Cholesterol ester transfer protein (CETP) gene polymorphism and selected parameters of lipid metabolism in children from families with history of cardiovascular system diseases

BACKGROUND

Children from families with a history of cardiovascular system diseases are especially predisposed to early development of atherosclerosis. Therefore, the aim of this study was to examine the selected lipid parameters and polymorphisms of G279A located in the cholesterol ester transfer protein (CETP) gene.

MATERIAL/METHODS

This longitudinal study was performed in 3 stages. During stage I the tests were carried out on 137 newborns after birth. Of these, we selected 30 children with a family history of cardiovascular system diseases. During stage II of the study the same children were evaluated at the age of 18-30 months, and during stage III at the age 5-6 years. Gestational age and the birth weight were evaluated in newborns. The older children were examined physically, and nutritional status was assessed. In all of the children examined, we determined the blood concentrations of triglycerides, total cholesterol, high-density lipoprotein (HDL) cholesterol, apolipoproteins (AI and B), lipoprotein(a) and polymorphisms, and the G279A locus of the CETP gene.

RESULTS

In children with genotype B1B1 (after birth and aged 5-6 years), a significantly lower cholesterol concentration in the HDL fraction was found compared to those with genotype B1B2 and B2B2. Other biochemical parameters of lipid metabolism were not significantly different between these genetic polymorphisms.

CONCLUSIONS

A lower cholesterol concentration in the HDL fraction in children with a family history of cardiovascular system diseases was determined by polymorphism of the CETP gene. Homozygotes (genotype B1B1) show a tendency towards the phenotype favoring the development of atherosclerosis.

Novel pharmacotherapies of familial hyperlipidemia

Familial hyperlipidemia is an inherited metabolic disorder characterized by elevated lipid and/or lipoprotein levels in the blood. Despite improvements in lipid-lowering therapy during the last decades, it still remains a substantial contributor to the incidence of cardiovascular disease since patients on current conventional therapies do not achieve their target LDL-cholesterol levels. With a view to lower LDL-cholesterol levels, a number of new therapeutic strategies have been developed over recent years. In this review, we provide an overview of these treatment options that are currently in clinical development and may offer alternative or adjunctive therapies for this high-risk population.

Dietary cholesterol increases paraoxonase 1 enzyme activity

HDL-associated paraoxonase 1 (PON1) activity has been consistently associated with cardiovascular and other diseases. Vitamins C and E intake have previously been positively associated with PON1 in a subset of the Carotid Lesion Epidemiology and Risk (CLEAR) cohort. The goal of this study was to replicate these findings and determine whether other nutrient intake affected PON1 activity. To predict nutrient and mineral intake values, 1,402 subjects completed a standardized food frequency survey of their dietary habits over the past year. Stepwise regression was used to evaluate dietary and covariate effects on PON1 arylesterase activity. Five dietary components, cholesterol (P < 2.0 × 10(-16)), alcohol (P = 8.51 × 10(-8)), vitamin C (P = 7.97 × 10(-5)), iron (P = 0.0026), and folic acid (0.037) were independently predictive of PON1 activity. Dietary cholesterol was positively associated and predicted 5.5% of PON1 activity, second in variance explained. This study presents a novel finding of dietary cholesterol, iron, and folic acid predicting PON1 activity in humans and confirms prior reported associations, including that with vitamin C. Identifying and understanding environmental factors that affect PON1 activity is necessary to understand its role and that of HDL in human disease.

Mipomersen: evidence-based review of its potential in the treatment of homozygous and severe heterozygous familial hypercholesterolemia

Familial hypercholesterolemia (FH) is an autosomal-dominant inherited disease with a prevalence of one in 500 (heterozygous) to one in 1,000,000 (homozygous). Mutations of the low-density lipoprotein (LDL) receptor gene, the apolipoprotein B100 gene, or the PCSK9 gene may be responsible for the disease. The resulting LDL hypercholesterolemia results in premature atherosclerosis as early as childhood (homozygous FH) or in adulthood (heterozygous FH). Current treatment modalities include lifestyle modification, combination drug therapy (statin-based), and apheresis. Mipomersen is an antisense oligonucleotide which inhibits apolipoprotein B production independent of LDL receptor function and thus works in homozygous FH, heterozygous FH, and other forms of hypercholesterolemia. Mipomersen is given 200 mg/week subcutaneously. Phase III studies indicate that the LDL cholesterol concentration can be reduced by 25%-47%, lipoprotein(a) levels by 20%-40%, and triglyceride concentrations by approximately 10%. In general, mipomersen has no effect on high-density lipoprotein cholesterol concentrations. Although there is considerable interindividual variability, the observed lipid effects are largely independent of age, gender, concomitant statin therapy, and underlying dyslipoproteinemia. The most common side effects are injection site reactions (70%-100%), flu-like symptoms (29%-46%), and elevated transaminases associated with an increased liver fat content (6%-15%). Mipomersen may be an interesting addon drug in patients with heterozygous or homozygous FH not reaching treatment goals, either because baseline values are very high or because high-dose statins are not tolerated.

Genetic determinants of lipid homeostasis

Circulating levels of blood lipids are heritable risk factors for atherosclerosis and heart disease, and are the target of therapeutic intervention. Studies of monogenic disorders and - more recently - genome-wide association studies have identified several important genetic determinants of blood lipid levels. These have the potential to provide new drug targets to alter blood lipid levels and may improve prediction of cardiovascular disease. Better functional validation of lipid loci is required to clarify the biological role of proteins encoded by specific genomic regions and understand how they influence lipid metabolism and confer disease risk.

Nanotechnology for synthetic high-density lipoproteins

Atherosclerosis is the disease mechanism responsible for coronary heart disease (CHD), the leading cause of death worldwide. One strategy to combat atherosclerosis is to increase the amount of circulating high-density lipoproteins (HDL), which transport cholesterol from peripheral tissues to the liver for excretion. The process, known as reverse cholesterol transport, is thought to be one of the main reasons for the significant inverse correlation observed between HDL blood levels and the development of CHD. This article highlights the most common strategies for treating atherosclerosis using HDL. We further detail potential treatment opportunities that utilize nanotechnology to increase the amount of HDL in circulation. The synthesis of biomimetic HDL nanostructures that replicate the chemical and physical properties of natural HDL provides novel materials for investigating the structure-function relationships of HDL and for potential new therapeutics to combat CHD.

Genetic variants influencing circulating lipid levels and risk of coronary artery disease

OBJECTIVE

Genetic studies might provide new insights into the biological mechanisms underlying lipid metabolism and risk of CAD. We therefore conducted a genome-wide association study to identify novel genetic determinants of low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides.

METHODS AND RESULTS

We combined genome-wide association data from 8 studies, comprising up to 17 723 participants with information on circulating lipid concentrations. We did independent replication studies in up to 37 774 participants from 8 populations and also in a population of Indian Asian descent. We also assessed the association between single-nucleotide polymorphisms (SNPs) at lipid loci and risk of CAD in up to 9 633 cases and 38 684 controls. We identified 4 novel genetic loci that showed reproducible associations with lipids (probability values, 1.6×10(-8) to 3.1×10(-10)). These include a potentially functional SNP in the SLC39A8 gene for HDL-C, an SNP near the MYLIP/GMPR and PPP1R3B genes for LDL-C, and at the AFF1 gene for triglycerides. SNPs showing strong statistical association with 1 or more lipid traits at the CELSR2, APOB, APOE-C1-C4-C2 cluster, LPL, ZNF259-APOA5-A4-C3-A1 cluster and TRIB1 loci were also associated with CAD risk (probability values, 1.1×10(-3) to 1.2×10(-9)).

CONCLUSIONS

We have identified 4 novel loci associated with circulating lipids. We also show that in addition to those that are largely associated with LDL-C, genetic loci mainly associated with circulating triglycerides and HDL-C are also associated with risk of CAD. These findings potentially provide new insights into the biological mechanisms underlying lipid metabolism and CAD risk.

Gene-environment interactions of CETP gene variation in a high cardiovascular risk Mediterranean population

Genome-wide association studies show that cholesteryl ester transfer protein (CETP) single nucleotide polymorphisms (SNPs) are more strongly associated with HDL cholesterol (HDL-C) concentrations than any other loci across the genome. However, gene-environment interactions for clinical applications are still largely unknown. We studied gene-environment interactions between CETP SNPs and dietary fat intake, adherence to the Mediterranean diet, alcohol consumption, smoking, obesity, and diabetes on HDL-C in 4,210 high cardiovascular risk subjects from a Mediterranean population. We focused on the -4,502C>T and the TaqIB SNPs in partial linkage disequilibrium (D'= 0.88; P < 0.001). They were independently associated with higher HDL-C (P < 0.001); this clinically relevant association was greater when their diplotype was considered (14% higher in TT/B2B2 vs. CC/B1B1). No gene-gene interaction was observed. We also analyzed the association of these SNPs with blood pressure, and no clinically relevant associations were detected. No statistically significant interactions of these SNPs with obesity, diabetes, and smoking in determining HDL-C concentrations were found. Likewise, alcohol, dietary fat, and adherence to the Mediterranean diet did not statistically interact with the CETP variants (independently or as diplotype) in determining HDL-C. In conclusion, the strong association of the CETP SNPs and HDL-C was not statistically modified by diet or by the other environmental factors.

Cholesteryl ester transfer protein (CETP) genotype and reduced CETP levels associated with decreased prevalence of hypertension

OBJECTIVES

To clarify whether reduced cholesteryl ester transfer protein (CETP) activity carries inherent blood pressure risks and to infer whether the increased blood pressure and elevated mortality associated with torcetrapib are idiosyncratic or characteristic of this class of drugs.

PATIENTS AND METHODS

We examined the associations among CETP genotype, phenotype, and blood pressure in a cohort of 521 older adults (who have complete data for the variables required in our primary analysis) enrolled between November 1, 1998, and June 30, 2003, in our ongoing studies of genes associated with longevity, including a cohort with a high prevalence of a genotype coding for a reduced activity variant of CETP and low levels of CETP.

RESULTS

The prevalence of hypertension was actually lower among homozygotes for the variant CETP (48% vs 60% among those with wild-type and 65% among heterozygotes; P=.03). Low levels of CETP were associated with reduced prevalence of hypertension (65% in highest tertile, 59% in middle tertile, and 55% in lowest tertile; P=.04) and lower systolic blood pressure (140.8, 138.1, 136.2 mm Hg, respectively; P=.03).

CONCLUSION

Reduced levels of CETP are associated with lower, not higher, blood pressure. The adverse results with torcetrapib, if mediated through blood pressure, are likely to represent effects of this specific drug, rather than a result of lower CETP levels.

Inflammatory and autoimmune reactions in atherosclerosis and vaccine design informatics

Atherosclerosis is the leading pathological contributor to cardiovascular morbidity and mortality worldwide. As its complex pathogenesis has been gradually unwoven, the regime of treatments and therapies has increased with still much ground to cover. Active research in the past decade has attempted to develop antiatherosclerosis vaccines with some positive results. Nevertheless, it remains to develop a vaccine against atherosclerosis with high affinity, specificity, efficiency, and minimal undesirable pathology. In this review, we explore vaccine development against atherosclerosis by interpolating a number of novel findings in the fields of vascular biology, immunology, and bioinformatics. With recent technological breakthroughs, vaccine development affords precision in specifying the nature of the desired immune response—useful when addressing a disease as complex as atherosclerosis with a manifold of inflammatory and autoimmune components. Moreover, our exploration of available bioinformatic tools for epitope-based vaccine design provides a method to avoid expenditure of excess time or resources.

Common cholesteryl ester transfer protein gene variation related to high-density lipoprotein cholesterol is not associated with decreased coronary heart disease risk after a 10-year follow-up in a Mediterranean cohort: Modulation by alcohol consumption

OBJECTIVE

Despite the consistent association between cholesteryl ester transfer protein (CETP) gene variation and plasma HDL-C, huge controversy still rages on its association with coronary heart disease (CHD). We investigated the association between the CETP-TaqIB polymorphism, HDL-C and incident CHD in a Mediterranean population.

METHODS

A nested case-control study among participants of the Spanish EPIC cohort was performed. 41,440 healthy individuals (30-69 years) were followed up over a 10-year period, incident CHD cases being identified. We analyzed 557 confirmed CHD cases and 1180 healthy controls.

RESULTS

Despite B2B2 subjects having the highest HDL-C concentrations and B1B1, the lowest (P<0.001), no protective effect of the B2 allele against CHD incidence was observed. Thus, in comparison with B1B1 subjects, the adjusted CHD risk of B1B2 was OR: 1.00, 95% CI: 0.80-1.26; P=0.982, and that of B2B2 was OR: 1.16, 95% CI: 0.84-1.61; P=0.374. These results did not change after adjustment for HDL-C. No significant interaction between alcohol consumption and the CETP-TaqIB polymorphism in determining HDL-C was found. However, a different effect of this polymorphism on CHD risk in drinkers and non-drinkers was observed. In non-drinkers, the B2B2 genotype was associated with a non-significant lower CHD risk, whereas in drinkers it was associated with a greater risk (OR: 1.55, 95% CI: 1.05-2.29; P=0.026). We also observed that in diabetics (11% cases and 7.4% controls), the B2 allele was significantly associated with higher CHD risk.

CONCLUSIONS

In this Mediterranean population, the CETP-TaqIB polymorphism was not associated with a lower CHD incidence, and its effect was modulated by alcohol and possibly by diabetes.

Dysfunctional high-density lipoprotein

PURPOSE OF REVIEW

To address the progress of the investigation on dysfunctional high-density lipoprotein (HDL).

RECENT FINDINGS

HDL is generally considered to be an independent protective factor against cardiovascular disease. However, emerging evidence indicates that HDL can be modified under certain circumstances and lose its protective effect or even become atherogenic. The underlying mechanisms responsible for generating the dysfunctional HDL and the chemical and structural changes of HDL remain largely unknown. Recent studies focus on the role of myeloperoxidase in generating oxidants as participants in rendering HDL dysfunctional in vivo. Myeloperoxidase modifies HDL in humans by oxidation of specific amino acid residues in apolipoprotein A-I, which impairs cholesterol efflux through ATP-binding cassette transporter A1 and contributes to atherogenesis.

SUMMARY

HDL may not always be atheroprotective and can be atherogenic paradoxically under certain conditions. The mechanisms responsible for generating the dysfunctional HDL remain largely unknown. Recent data suggest that myeloperoxidase-associated modification of HDL may be one of the mechanisms. Further studies are needed to investigate the in-vivo mechanisms of HDL modification and identify therapeutic approaches aiming at controlling HDL modification.

Vaccines in development to prevent and treat atherosclerotic disease

Coronary heart disease (CHD) remains the leading cause of death in the United States. Immune mechanisms have been recently proposed to play an important role in the development of atherosclerotic plaques in CHD. Heat shock proteins and oxidized low-density lipoprotein are proinflammatory substances that have been shown to have an important role in the pathogenesis of atherosclerosis, and are now targets for clinical vaccine development. In addition, a vaccine has been developed to inhibit cholesteryl ester transfer protein. It is now recognized that many medications used to combat plaque development and rupture have significant anti-inflammatory effects and these effects are critical for drug efficacy. The influenza vaccine is associated with an atheroprotective effect. In addition, a nicotine vaccine, an antiangiotensin vaccine, and an anti-obesity vaccine may play a therapeutic role in modifying known risk factors for the development of atherosclerosis and its complications. This article reviews these vaccines as possible additions to the armamentarium of atheroprotective treatment modalities.