Elevated High-density Lipoprotein Cholesterol Levels Research Articles

Impact of lipid disorders on mortality among Saudi patients with heart failure

BackgroundDyslipidemia, a known cardiovascular risk factor, is extremely common among Saudis, both adults and children. The impact, however, of dyslipidemia and several other lipid disorders in patients with congestive heart failure in this particular population has not been documented. This study aims to fill the gap. MethodsThis retrospective, single center study was conducted at King Abdulaziz Medical City, Riyadh, Saudi Arabia. Of the 500 cases seen during the period between 2002 and 2008, 392 were included in the study. Charts were reviewed and information on medical history, medications, and lipid status were documented. ResultsLow HDL-cholesterol level was the most common lipid disorder with 82.9%, followed by hypertriglyceridemia (35.2%), atherogenic dyslipidemia (27.8%), and hypercholesterolemia (9.2%). Diabetes mellitus was the single most significant predictor of mortality (p=0.001). Among the lipid disorders, only low levels of HDL-cholesterol contributed to significant mortality risk [OR 1.29 (Confidence Interval 1.04–1.59) (p-value<0.01)] adjusted for age, gender and statin use. ConclusionThe results of this study suggest that emphasis should be on the elevation of HDL-cholesterol levels among subjects with congestive heart failure, without compromising any ongoing management of LDL-lowering drugs. Management should not be limited to conventional statin use and should promote other treatments to elevate HDL-cholesterol levels.

Epidemiology: disease associations and modulators of HDL-related biomarkers.

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

Relationships of serum lipid profiles and bone mineral density in postmenopausal Chinese women.

Recent studies suggest that serum lipid profiles are related to bone mineral density (BMD). But data about this relationship on Chinese population are scarce. We investigated the relationships between serum lipid and BMD in postmenopausal Chinese women. A cross-sectional study was conducted in 790 Chinese postmenopausal women. BMDs were measured by dual X-ray absorptiometry. Serum lipid profiles were obtained after a 12-h fasting. Women with serum high-density lipoprotein cholesterol (HDL-C) levels of at least 1·55 mmol/l had a greater prevalence of osteoporosis compared with women with lower HDL-C (≤1·54 mmol/l). After controlling for age, menopausal duration, body mass index, serum creatinine levels, outdoor activity, smoking and alcohol intake, high HDL-C levels were associated with osteoporosis (OR = 1·64, 95%CI 1·16-2·33, P < 0·01). BMD at femoral neck and total hip was significantly lower in the higher HDL-C class than the lower class (0·722 ± 0·118 vs 0·744 ± 0·120 g/cm(2) , P < 0·01; 0·800 ± 0·126 vs 0·824 ± 0·125 g/cm(2) , P < 0·01, respectively). No association was found between total cholesterol (TC), triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C) with BMD. In Chinese postmenopausal women, elevated levels of serum HDL-C had a greater probability of being osteoporosis than the lower HDL-C levels. Our analysis showed higher HDL-C level that is favourable for cardiovascular diseases should be regarded as a risk factor for osteoporosis.

Identification of four novel genes contributing to familial elevated plasma HDL cholesterol in humans

While genetic determinants strongly influence HDL cholesterol (HDLc) levels, most genetic causes underlying variation in HDLc remain unknown. We aimed to identify novel rare mutations with large effects in candidate genes contributing to extreme HDLc in humans, utilizing family-based Mendelian genetics. We performed next-generation sequencing of 456 candidate HDLc-regulating genes in 200 unrelated probands with extremely low (≤10th percentile) or high (≥90th percentile) HDLc. Probands were excluded if known mutations existed in the established HDLc-regulating genes ABCA1, APOA1, LCAT, cholesteryl ester transfer protein (CETP), endothelial lipase (LIPG), and UDP-N-acetyl-α-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase 2 (GALNT2). We identified 93 novel coding or splice-site variants in 72 candidate genes. Each variant was genotyped in the proband's family. Family-based association analyses were performed for variants with sufficient power to detect significance at P < 0.05 with a total of 627 family members being assessed. Mutations in the genes glucokinase regulatory protein (GCKR), RNase L (RNASEL), leukocyte immunoglobulin-like receptor 3 (LILRA3), and dynein axonemal heavy chain 10 (DNAH10) segregated with elevated HDLc levels in families, while no mutations associated with low HDLc. Taken together, we have identified mutations in four novel genes that may play a role in regulating HDLc levels in humans.

Efficacy, Safety, Tolerability, and Pharmacokinetic Profile of Evacetrapib Administered as Monotherapy or in Combination With Atorvastatin in Japanese Patients With Dyslipidemia

The cholesteryl ester transfer protein (CETP) inhibitor evacetrapib has been previously shown to increase high-density lipoprotein cholesterol (HDL-C) and decrease low-density lipoprotein cholesterol (LDL-C) levels, as monotherapy or in combination with statins. In this study, 165 Japanese patients with elevated LDL-C or low HDL-C levels were randomly assigned to receive placebo, evacetrapib monotherapy 30 mg, 100 mg, or 500 mg, atorvastatin 10 mg, or evacetrapib 100 mg in combination with atorvastatin 10 mg. After 12 weeks, evacetrapib monotherapy increased HDL-C levels by 74%, 115%, and 136% and decreased LDL-C levels by 15%, 23%, and 22% and CETP activity by 50%, 83%, and 95% (for the 30-mg, 100-mg, and 500-mg dose groups, respectively) versus placebo. In combination with atorvastatin 10 mg, evacetrapib 100 mg increased HDL-C levels by 103% and decreased LDL-C levels by 15% and CETP activity by 68% versus atorvastatin alone. After a 4- to 6-week washout, HDL-C, LDL-C, and CETP mass and activity returned to baseline levels in the evacetrapib-treated groups, and most patients had evacetrapib concentrations below the quantitation limit. Evacetrapib monotherapy or in combination with atorvastatin was not likely to be associated with any significant change in blood pressure and did not have any adverse effects on mineralocorticoid or glucocorticoid measures. Notably, plasma evacetrapib concentrations were mostly undetectable, and all pharmacodynamic biomarkers (HDL-C and LDL-C levels and CETP mass and activity) returned to baseline after a 4- to 6-week washout. In conclusion, evacetrapib as monotherapy or in combination with atorvastatin effectively decreased CETP activity and LDL-C levels and increased HDL-C levels after 12 weeks in Japanese patients with dyslipidemia.

Associations of lipoprotein lipase gene rs326 with changes of lipid profiles after a high-carbohydrate and low-fat diet in healthy Chinese Han youth.

To investigate the effects of a high-carbohydrate and low-fat (HC/LF) diet on plasma lipids and apolipoproteins (Apos) of healthy Chinese Han youth with different genotypes of lipoprotein lipase gene (LPL) rs326, 56 subjects were given a washout diet of 30.1% fat and 54.1% carbohydrate for seven days, followed by the HC/LF diet of 13.8% fat and 70.1% carbohydrate for six days, with no total energy restriction. Plasma glucose, triglyceride (TG), total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), Apo B-100 and Apo A-I were analyzed at baseline and before and after the HC/LF diet. The results show that, when compared with before the HC/LF diet, only the male G carriers experienced increased HDL-C (p = 0.008) and Apo A-I (p = 0.005) after the HC/LF diet. Decreased TC in both males and females and increased TG in females were found regardless of the genotype after the HC/LF diet. LDL-C decreased in all the subjects although the decrease was not significant in the female G carriers. These results demonstrate that the G allele of LPL rs326 associates with the elevated levels of HDL-C and Apo A-I after the HC/LF diet in males of the healthy Chinese Han Youth.

How Do Elevated Triglycerides and Low HDL-Cholesterol Affect Inflammation and Atherothrombosis?

This review article summarizes recent research into the mechanisms as to how elevated levels of triglyceride (TG) and low levels of high- density- lipoprotein cholesterol (HDL-C) contribute to inflammation and atherosclerosis. Evidence supports the role of TG-rich lipoproteins in signaling mechanisms via apolipoproteins C-III and free fatty acids leading to activation of NFKβ, VCAM-1 and other inflammatory mediators which lead to fatty streak formation and advanced atherosclerosis. Moreover, the cholesterol content in TG-rich lipoproteins has been shown to predict CAD risk better than LDL-C. In addition to reverse cholesterol transport, HDL has many other cardioprotective effects which include regulating immune function. The "functionality" of HDL appears more important than the level of HDL-C. Insulin resistance and central obesity underlie the pathophysiology of elevated TG and low HDL-C in metabolic syndrome and type 2 diabetes. Lifestyle recommendations including exercise and weight loss remain first line therapy in ameliorating insulin resistance and the adverse signaling processes from elevated levels of TG-rich lipoproteins and low HDL-C.

Mild total hypercholesterolemia, elevated serum high-density and non-high-density lipoproteins, across age and disease severity staging, in people with Alzheimer's disease: An observational study

Presently, existing information about the lipids and lipoproteins profile characteristics in Alzheimer's disease (AD) is conflicting. We previously reported, mild hypercholesterolemia (total), and normal serum triglycerides level, present in subjects with AD, across age and disease severity staging. The aim of this study was to investigate serum total cholesterol (TC), high-density lipoprotein cholesterol (HDLc), low-density lipoprotein cholesterol (LDLc), non-HDL cholesterol (non-HDLc) and triglycerides levels, in subjects with probable AD, and in healthy elderly controls, as well as, a possible correlation with AD. In a retrospective study, measures of fasting plasma TC, HDLc, LDLc, non-HDLc and TG levels, were studied in 87 patients (52 women) with probable AD (DSM-IV; NINCDS-ADRDA criteria); (Mean age: 72.7±8.5 years; range:55–89 years; disease duration:2±1.1y); from a private ambulatory of neurology, recruited in a community elderly in Skikda-Algeria (2009–2012); and in 100 age matched elderly controls (50 women), (Mean age: 72.1±10.1 years). Correlation with dementia severity was assessed by the clinical dementia rating scale (CDR) global score. M ean TC, HDLc, non-HDLc levels were higher for AD compared to control group, (Mean±SD): 201.5±24.8 vs 178.1±12.2; 52.1±6.6 vs 47.8±5.3; 149.4 ± 24.5 vs 130.3±11.7 mg/dl respectively (all p<.0001). There were no differences in mean LDLc: 116.0±18.4 vs 112.8±16.2 mg/dl (p=0.216) or triglycerides: 110.7±19.0 vs 109.2±22.4 mg/dl (p=0.617), levels. When compared by decennial age strata subgroups, TC, HDLc and non-HDLc levels were higher for AD compared to controls among decennial subgroups. Respective, AD and controls, plotted trajectories of change across age, were fairly parallel for TC, for HDLc and for non-HDLc plasma levels. Patients were classified according to the CDR score into four subgroups (CDR=0.5;1;2;3); we did not find significant differences among subgroups in mean TC (p=0.37), HDLc (p=0.514), and non-HDLc (p=0.27) levels. Dementia severity did not correlate significantly with any lipid parameters. These results suggest that patients with Alzheimer disease have mild total hypercholesterolemia, elevated plasma HDL and non-HDL cholesterol levels; and normal plasma triglycerides levels. This biochemical parameters profile is observed across age and dementia severity staging, until the late stage of the disease, and may be present long before a decade at least- the disease symptomatic onset.

Future of Cholesteryl Ester Transfer Protein (CETP) Inhibitors: A Pharmacological Perspective

In almost 30years since the introduction of HMG-CoA reductase inhibitors (statins), no other class of lipid modulators has entered the market. Elevation of high-density lipoprotein-cholesterol (HDL-C) via inhibiting cholesteryl ester transfer protein (CETP) is an attractive strategy for reducing the risk of cardiovascular events in high-risk patients. Transfer of triglyceride and cholesteryl ester (CE) between lipoproteins is mediated by CETP; thus inhibition of this pathway can increase the concentration of HDL-C. Torcetrapib was the first CETP inhibitor evaluated in phase III clinical trials. Because of off-target effects, torcetrapib raised blood pressure and increased the concentration of serum aldosterone, leading to higher cardiovascular events and mortality. Torcetrapib showed positive effects on cardiovascular risk especially in patients with a greater increase in HDL-C and apolipoprotein A-1 (apoA-1) levels. The phase III clinical trial of dalcetrapib, the second CETP inhibitor that has entered clinical development, was terminated because of ineffectiveness. Dalcetrapib is a CETP modulator that elevated HDL-C levels but did not reduce the concentration of low-density lipoprotein cholesterol (LDL-C). Both heterotypic and homotypic CE transfer between lipoproteins are mediated by some CETP inhibitors, including torcetrapib, anacetrapib, and evacetrapib, while dalcetrapib only affects the heterotypic CE transfer. Dalcetrapib has a chemical structure that is distinct from other CETP inhibitors, with a smaller molecular weight and a lack of trifluoride moieties. Moreover, dalcetrapib is a pro-drug that must be hydrolyzed to a pharmacologically active thiol form. Two other CETP inhibitors, anacetrapib and evacetrapib, are currently undergoing evaluation in phase III clinical trials. Both molecules have shown beneficial effects by increasing HDL-C and decreasing LDL-C concentration. The success of anacetrapib and evacetrapib remains to be confirmed upon the completion of phase III clinical trials in 2017 and 2015, respectively. Generally, the concentration of HDL-C has been considered a biomarker for the activity of CETP inhibitors. However, it is not clear whether a fundamental relationship exists between HDL-C levels and the risk of coronary artery diseases. The most crucial role for HDL is cholesterol efflux capacity in which HDL can reverse transport cholesterol from foam cells in atherosclerotic plaques. In view of the heterogeneity in HDL particle size, charge, and composition, the mere concentration of HDL-C may not be a good surrogate marker for HDL functionality. Recent clinical studies have reported that increased HDL functionality inversely correlates with the development of atherosclerotic plaque. Future development of CETP inhibitors may therefore benefit from the use of biomarkers of HDL functionality.

HDL’s Protein Cargo

Low levels of high-density lipoprotein (HDL) particles were first linked to increased risk of cardiovascular disease (CVD) >40 years ago.1 Because analytic ultracentrifugation, the method used for those pioneering studies, is complex and time consuming, clinical investigators began to use HDL cholesterol (HDL-C) as a surrogate measure for HDL concentration. Clinical, epidemiological, and genetic studies provide robust evidence that low HDL-C levels associate with clinically significant CVD.2 Moreover, atherosclerosis increases markedly in hypercholesterolemic mice deficient in apolipoprotein (apoA)-I,3 the major HDL protein, whereas overexpression of human apoA-I dramatically retards atherosclerosis in hypercholesterolemic mice.4 Many lines of evidence indicate that apoA-I and HDL promote cholesterol efflux from macrophages, a key step in atherogenesis.5 Taken together, these findings provide strong evidence that apoA-I plays a key role in HDL’s cardioprotective activities. Article see p 891 These observations have triggered intense interest in targeting HDL-C for therapeutic intervention, because lowering low-density lipoprotein (LDL) levels with statins leaves a large residual risk in CVD subjects. However, several lines of evidence suggest that the association between HDL-C levels and CVD status is not a causal relationship and that elevating HDL-C is not necessarily therapeutic.6,7 For example, genetic variations that only affect HDL-C levels do not markedly alter CVD risk. Also, trials of several drugs that elevate …

Lower levels of total HDL and HDL3 cholesterol are associated with albuminuria in normoalbuminuric Type 1 diabetic patients.

Previous studies have suggested a positive association between dyslipidemia and chronic kidney disease, but sparse data are available on the relation of lipids and urinary albumin excretion rate (UAE) in normoalbuminuric patients with normal renal function. The aim of this study was to evaluate the associations of serum lipids, including total, LDL, HDL, HDL2, HDL3 cholesterol, and triglyceride levels with UAE in normoalbuminuric Type 1 diabetic (T1D) patients. Study included 313 normoalbuminuric T1D patients with normal renal function and before any interventions with statins, ACE inhibitors or angiotensin II receptor blockers. Subjects were classified as low-normoalbuminuric (UAE<11.0 mg/24h) or high-normoalbuminuric (UAE≥11.0 mg/24h) based on median UAE of at least two 24- h urine collections. Correlations and multiple linear regressions analysis were performed to identify relationships between serum lipids and UAE in normoalbuminuric subjects. Total HDL (p=0.02) and HDL3 cholesterol (p=0.01) levels were higher in low-normoalbuminuric subjects compared to high-normoalbuminuric subjects. In logistic regression analysis, after adjustment for age, sex, BMI, duration of diabetes and HbA1c, lower total HDL and HDL3 cholesterol levels were significantly associated with risk of higher UAE in our normoalbuminuric subjects (p≤0.01), with odds ratios of 0.34 to 0.43. Elevated total HDL and HDL3 cholesterol levels are associated with lower UAE in normoalbuminuric T1D patients. However, whether the detection of elevated total HDL and HDL3 cholesterol levels in T1D patients has protective value for development of microalbuminuria needs to be assessed in further follow-up studies.

High-density cholesterol and apolipoprotein AI as modifiers of plasma fibrin clot properties in apparently healthy individuals

Low high-density lipoprotein cholesterol (HDL-C) increases cardiovascular risk, whereas its high levels protect against atherosclerosis via multiple beneficial effects. Dense and poorly lysable fibrin clot formation is observed in cardiovascular disease. We sought to investigate whether HDL-C and its major component apolipoprotein A (Apo A)-I affect fibrin clot properties. In 136 apparently healthy individuals (99 men, 37 women, aged 49-69 years) we determined plasma fibrin clot permeability (Ks coefficient) and lysis time (t50%) together with Apo A-I and lipoprotein (a) [Lp(a)] levels. The median HDL-C level was 1.33 mmol/l (range from 0.77 to 2.19 mmol/l). HDL-C was positively associated with Apo A-I (r = 0.62, P < 0.00001). HDL-C and Apo A-I were positively correlated with Ks (r = 0.52, P < 0.00001 and r = 0.44, P < 0.00001, respectively) and inversely with t50% (r = -0.44, P < 0.00001 and r = -0.35, P = 0.00003, respectively). No such associations were seen for other lipid variables. Ks and t50% were associated with Lp(a) (r = -0.42, P < 0.00001 and r = 0.42, P < 0.00001, respectively) and fibrinogen (r = -0.31, P = 0.00024 and r = 0.39, P < 0.00001, respectively). Individuals with HDL-C at least 1.4 mmol/l (n = 54) had 19% higher Ks (P = 0.00016) and 17% shorter t50% (P = 0.0012) than the remainder. After adjustment for age, fibrinogen, and Lp(a), HDL-C was the independent predictor of Ks (β = 0.7, P < 0.00001) and t50% (β = -0.62, P < 0.00001). This study shows that elevated HDL-C levels are associated with improved fibrin clot permeability and lysis, indicating a novel antithrombotic mechanism underlying the postulated beneficial effects of therapy targeted at HDL-C.

High Density Lipoprotein – Should we Raise it?

Low high-density lipoprotein (HDL) cholesterol levels are associated with an increased risk of coronary artery disease and myocardial infarction. Experimental studies have identified several potential anti-atherogenic properties of HDL, including promotion of macrophage cholesterol efflux, endothelial nitric oxide stimulation, anti-inflammatory and anti-thrombotic effects. These observations have lead to the important question of whether raising of HDL can reduce cardiovacular risk. Notably, recent studies have suggested that vascular effects of HDL can be highly heterogenous and are altered in patients with coronary disease or diabetes, that has been referred to as "HDL dysfunction". Moreover, studies using gene-targeted mice have indicated that genetic modifications leading to a similar increase of HDL cholesterol levels can either reduce (i.e. apoA1 transgene overexpression) or accelerate (i.e. SR-B1 deficiency) atherosclerosis, depending on the molecular target. These findings therefore suggest that HDL cholesterol levels alone are likely not sufficient as a readout for the vascular effects of HDL-targeted therapeutic interventions, since both, the vascular effects of on-treatment HDL as well as the underlying molecular mechanism used to elevate HDL cholesterol levels may represent critical determinants of the overall vascular effects of therapeutic interventions raising HDL-cholesterol levels. In summary, low HDL cholesterol plasma levels remain associated with an increased cardiovascular risk. However, the above findings suggest that careful clinical trial programms are needed to determine, which HDL raising therapeutic interventions may indeed exert vasoprotective effects.

Advanced glycation end-products (AGEs) and functionality of reverse cholesterol transport in patients with type 2 diabetes and in mouse models

We investigated the contribution of AGEs to the impairment of reverse cholesterol transport (RCT) variables in diabetic individuals and in two animal models of diabetic obesity and of renal impairment. The capacity of plasma and HDL from 26 individuals with moderately controlled type 2 diabetes to support cholesterol efflux was compared with 26 age- and sex-matched individuals without diabetes. We also compared the rates of RCT in vivo in two animal models: db/db mice and mice with chronic renal failure. Diabetic individuals had characteristic dyslipidaemia and higher levels of plasma AGEs. The capacity of whole plasma, ApoB-depleted plasma and isolated HDL to support cholesterol efflux was greater for diabetic patients compared with controls despite their lower HDL-cholesterol levels. The capacity of plasma to support cholesterol efflux correlated with plasma levels of cholesteryl ester transfer protein and levels of ApoB, but not with levels of AGE. RCT was severely impaired in db/db mice despite elevated HDL-cholesterol levels and no change in AGE concentration, whereas RCT in uraemic mice was unaffected despite elevated AGE levels. AGEs are unlikely to contribute significantly to the impairment of RCT in type 2 diabetes.

Abstract 46: Cholesteryl Ester Transfer Protein Interactions with Lipoproteins: Insights into Mechanisms by Electron Microscopy and Molecular Dynamics Simulation

Cholesteryl ester transfer protein (CETP) mediates the transfer of neutral lipids, including cholesteryl esters (CEs) and triglycerides (TGs), between HDL, LDL and VLDL. Lipoprotein particles contain a neutral lipid core composed of CE and TG surrounded by a surface monolayer of phospholipids (PL), free cholesterol (FC), and apolipoproteins, most notably, apo B-100 in LDL and VLDL and apo A-I in HDL. An elevated level of LDL-cholesterol (LDL-C) and/or a low level of HDL-cholesterol (HDL-C) in human plasma are major risk factors for cardiovascular disease (CVD). Since increased CETP can reduce HDL-C concentration and CETP deficiency is associated with elevated HDL-C levels, CETP inhibitors, including torcetrapib, anacetrapib and dalcetrapib have been investigated in clinical trials for treating CVD. Despite the intense clinical interest in CETP inhibition, little is known concerning the molecular mechanisms of CETP-mediated lipid transfer among lipoproteins, or even how CETP interacts with lipoproteins. CETP is a hydrophobic glycoprotein of 476 amino acids (∼53 kDa, before posttranslational modification). Its crystal structure reveals a banana-shaped molecule with N- and C-terminal β-barrel domains, a central β-sheet, and a ∼60 Å-long hydrophobic central cavity. Three CETP neutral lipid transfer hypotheses were proposed more than two decades ago: 1) a shuttle mechanism that involves CETP collecting CEs from one lipoprotein and delivering them through the aqueous phase to another lipoprotein; 2) a tunnel mechanism in which CETP bridges two lipoproteins forming a ternary complex, with lipids flowing from the donor to acceptor lipoprotein through the CETP molecule; and 3) a modified tunnel mechanism implicating a CETP dimer. One difficulty in investigating CETP mechanisms using structural methods is that interaction with CETP can alter the size, shape, and composition of lipoproteins, especially HDL. We validated an optimized negative-staining electron microscopy (NS-EM) protocol in which flash-fixation of lipoprotein particles preserves a near native-state conformation for direct visualization of individual molecular or macromolecular particles. We applied this protocol to study the mechanisms by which CETP interacts with spherical HDL, LDL and VLDL. Three-dimensional (3D) reconstructions of CETP, free and HDL-bound, were obtained by single-particle techniques. In addition, we used inhibitory CETP antibodies to identify the regions of CETP that interact with HDL and LDL. Finally molecular dynamics (MD) simulation was used to assess the molecular mobility of CETP and predict the likely conformational changes that are associated with lipid transfer. We discovered that CETP bridges a ternary complex with its N-terminal β-barrel domain penetrating into HDL and its C-terminal domain interacting with LDL or VLDL. In our mechanistic model, the CETP lipoprotein-interacting regions, which are highly mobile, form pores that connect to a hydrophobic central cavity, thereby forming a tunnel for transfer of neutral lipids from donor to acceptor lipoproteins. These new insights into CETP transfer provide a molecular basis for analyzing mechanisms for CETP inhibition.

Comparison of the beneficial effects of guar gum on lipid profile in hyperlipidemic and normal rats

In this study, we searched the hypolipidemic effects of a dietary fiber in hyperlipidemic and normal rats. Rats were fed with high-fat diet (HFD) or a normal fed diet (NFD) for 12-weeks and then treated with 5, 10 and 20% guar gum in their regime for 28 days. Total cholesterol (TC), triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C) were significantly increased in HFD rats, while administration of guar gum significantly lowered them. Serum high-density lipoprotein-cholesterol (HDL-C) was reduced in HFD rats. However, feeding the HFD rats with guar gum markedly elevated HDL-C level. Of the different tested percentage of guar gum in their regimes, 20% guar gum showed the strongest hypolipidemic effect, as well as a high anti atherogenic potential with atherogenic index (A.I.)These results suggested that guar gum may be effective hypolipiedemic agent and may prevent hyperlipidemic atherosclerosis in both hyperlipidemic and normal rats. Key word: Dietary fiber, guar gum, hyperlipidemic, lipid profile, rat.

Elevating HDL-cholesterol levels with dalcetrapib is safe

Elevating HDL-cholesterol levels with dalcetrapib is safe

Reactive Oxygen Species, SUMOylation, and Endothelial Inflammation

Although the exact mechanism through which NADPH oxidases (Nox's) generate reactive oxygen species (ROS) is still not completely understood, it is widely considered that ROS accumulation is the cause of oxidative stress in endothelial cells. Increasing pieces of evidence strongly indicate the role for ROS in endothelial inflammation and dysfunction and subsequent development of atherosclerotic plaques, which are causes of various pathological cardiac events. An overview for a causative relationship between ROS and endothelial inflammation will be provided in this review. Particularly, a crucial role for specific protein SUMOylation in endothelial inflammation will be presented. Given that SUMOylation of specific proteins leads to increased endothelial inflammation, targeting specific SUMOylated proteins may be an elegant, effective strategy to control inflammation. In addition, the involvement of ROS production in increasing the risk of recurrent coronary events in a sub-group of non-diabetic, post-infarction patients with elevated levels of HDL-cholesterol will be presented with the emphasis that elevated HDL-cholesterol under certain inflammatory conditions can lead to increased incidence of cardiovascular events.

Background to Discuss Guidelines for Control of Plasma HDL-Cholesterol in Japan*

A decrease in high density lipoprotein-cholesterol (HDL-C) is a strong risk factor for atherosclerotic disorders in Japan, probably more important than an increase in low density lipoprotein-cholesterol (LDL-C). While there are rational grounds for the argument that elevation of HDL-C leads to decreased risk, there has as yet been no direct evidence of such an effect. If elevation of HDL-C decreases the risk, this effect is expected throughout the normal range of HDL-C or perhaps even higher than that. Simulation based on epidemiological data indicated that it may eventually reduce the incidence of ischemic heart disease by 60-70% in Japan. In the risk management guideline, "low" HDL-C is presently defined as 40 mg/dL or below. While there is no evidence that strongly urges a change in this definition, the results of epidemiological studies support "The higher the HDL-C level, the lower the risk,"even in the "normal range". Elevation of the HDL-C level may reduce the risk, probably at least up to 70 mg/dL; however, there are no supportive data for this effect still being obtained over 80 mg/dL. Patients with homozygous CETP deficiency should be followed-up while controlling other risk factors, so as not to dismiss the possibility of a risk increase with an extremely elevated HDL-C level.

The Use of Fibric Acid Derivatives in Cardiovascular Prevention

Clinical trials have demonstrated the benefit of reduction of low-density lipoprotein (LDL) cholesterol levels in the prevention of atherosclerotic cardiovascular disease. Evidence is less robust for the effect of reduction of triglyceride levels and increase of high-density lipoprotein (HDL) cholesterol levels. In spite of the decrease of cardiovascular events in trials of LDL cholesterol-lowering medications, considerable residual risk remains, even with the use of high-dose statins. The fibric acid derivatives or fibrates reduce triglyceride and increase HDL cholesterol levels, effects that would be expected to affect cardiovascular events. However, clinical outcomes trials with fibrates have shown mixed results. Post-hoc analyses of fibrate trials as well as several meta-analyses suggest an overall decrease in primarily non-fatal coronary events without decrease in total mortality. The effects are most apparent in patients with elevated triglycerides and low HDL cholesterol levels. Statin therapy is the treatment of choice for most patients with dyslipidemia. The addition of a fibrate appears to be most beneficial in high-risk patients who continue to have significant dyslipidemia on statin therapy, most notably patients with diabetes mellitus or the metabolic syndrome. Thus, fibrates are not first-line drugs, but they do have a place in the management of the atherogenic lipid profile.