Reversible flow of cholesteryl ester between high-density lipoproteins and triacylglycerol-rich particles is modulated by the fatty acid composition and concentration of triacylglycerols

We determined the influence of fasting (FAST) and feeding (FED) on cholesteryl ester (CE) flow between high-density lipoproteins (HDL) and plasma apoB-lipoprotein and triacylglycerol (TG)-rich emulsions (EM) prepared with TG-fatty acids (FAs). TG-FAs of varying chain lengths and degrees of unsaturation were tested in the presence of a plasma fraction at d > 1.21 g/mL as the source of CE transfer protein. The transfer of CE from HDL to FED was greater than to FAST TG-rich acceptor lipoproteins, 18% and 14%, respectively. However, percent CE transfer from HDL to apoB-containing lipoproteins was similar for FED and FAST HDL. The CE transfer from HDL to EM depended on the EM TG-FA chain length. Furthermore, the chain length of the monounsaturated TG-containing EM showed a significant positive correlation of the CE transfer from HDL to EM (r = 0.81, P < 0.0001) and a negative correlation from EM to HDL (r = -041, P = 0.0088). Regarding the degree of EM TG-FAs unsaturation, among EMs containing C18, the CE transfer was lower from HDL to C18:2 compared to C18:1 and C18:3, 17.7%, 20.7%, and 20%, respectively. However, the CE transfer from EMs to HDL was higher to C18:2 than to C18:1 and C18:3, 83.7%, 51.2%, and 46.3%, respectively. Thus, the EM FA composition was found to be the rate-limiting factor regulating the transfer of CE from HDL. Consequently, the net transfer of CE between HDL and TG-rich particles depends on the specific arrangement of the TG acyl chains in the lipoprotein particle core431211351142FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP95/7662-

An Investigation of the Role of Cholesteryl Ester Transfer Protein in Lipid Metabolism

The investigation of the role of cholesteryl ester transfer protein (CETP) in lipid metabolism was divided into five main areas. These included the development of a reliable and reproducible assay for CETP activity, the development of polyclonal and monoclonal antibodies to CETP, studying the effect of various drugs on plasma CETP activity in several animal species, looking at the control of CETP secretion by different cell lines and analysing the relationship between restriction fragment length polymorphisms (RFLPs) of the CETP gene and various plasma lipid parameters in a population of 56 individuals

Lipid Exchange Mechanism of the Cholesteryl Ester Transfer Protein Clarified by Atomistic and Coarse-grained Simulations

Cholesteryl ester transfer protein (CETP) transports cholesteryl esters, triglycerides, and phospholipids between different lipoprotein fractions in blood plasma. The inhibition of CETP has been shown to be a sound strategy to prevent and treat the development of coronary heart disease. We employed molecular dynamics simulations to unravel the mechanisms associated with the CETP-mediated lipid exchange. To this end we used both atomistic and coarse-grained models whose results were consistent with each other. We found CETP to bind to the surface of high density lipoprotein (HDL) -like lipid droplets through its charged and tryptophan residues. Upon binding, CETP rapidly (in about 10 ns) induced the formation of a small hydrophobic patch to the phospholipid surface of the droplet, opening a route from the core of the lipid droplet to the binding pocket of CETP. This was followed by a conformational change of helix X of CETP to an open state, in which we found the accessibility of cholesteryl esters to the C-terminal tunnel opening of CETP to increase. Furthermore, in the absence of helix X, cholesteryl esters rapidly diffused into CETP through the C-terminal opening. The results provide compelling evidence that helix X acts as a lid which conducts lipid exchange by alternating the open and closed states. The findings have potential for the design of novel molecular agents to inhibit the activity of CETP

Association of Cholesteryl Ester Transfer Protein Gene Taqib Polymorphism and the Associated Phenotype Variation with Coronary Artery Disease.

Coronary artery disease (cad) has become a major public health problem in many Developing countries1,2. Cad is a multifactorial disease caused by genetic and environmental Factors 3. Lipoproteins play a central role in the development of atherosclerotic cardiovascular Disease in humans. The protective role of high density lipoprotein cholesterol (hdl-c) Against atherosclerosis is well established6,7. Numerous genetic, hormonal and environmental Factors determine hdl-c levels within distinct populations. Hdl exerts its cardioprotective Function through a process called reverse cholesterol transport, in addition to antiinflammatory And antioxidative effects. Reverse cholesterol transport describes a metabolic Pathway initiated by hdl-mediated efflux from peripheral tissues and subsequent delivery to The liver21,22. The cholesteryl ester transfer protein (cetp) plays a pivotal role in hdl Metabolism and in reverse cholesterol transport 23,24. Cholesteryl ester transfer protein (cetp), a hydrophobic glycoprotein composed of 476 amino acids. It is a member of the lipid transfer lipopolysaccharide binding protein Family which facilitates redistribution of cholesteryl ester and triglyceride among Lipoproteins25. It transfers cholesteryl esters from hdl to apolipoprotein-b containing Particles in exchange for triglycerides, thereby reducing the concentration of hdl-cholesterl And increasing non-hdl cholesterol, a lipoprotein distribution predisposing to atheroma Formation26. The essential role of cetp on human lipoprotein metabolism is evident based on A markedly altered lipoprotein profile in patients with genetic cetp deficiency27,28. High Plasma levels of cetp are associated with reduced hdl cholesterol levels261,29-31 and Increased ldl cholesterol levels 32. Several studies have also shown high cetp levels to be Atherogenic33,34. In humans, cetp mrna encodes a polypeptide of mr 53000, which is nglycosylated At 4 sites, giving rise to the mature form of cetp of mr 7400035. Cetp is Expressed primarily in liver, spleen, and adipose tissue, and lower levels have been detected In the small intestine, adrenal gland, heart, kidney, and skeletal muscle 35,36. There is a wide Variation in plasma cetp activity within and between population groups. The gene for human cetp contains 25 kb genomic dna and is composed of 16 Exons. It has been localized on chromosome 16q21 adjacent to the lecithin-cholesterol acyl Transferase gene. Several common restriction fragment length polymorphisms (rflps) have Been reported in the cetp gene locus 37,38. Taqib polymorphism is most widely studied, which is created by a silent base change Affecting the 277th nucleotide in the first intron of the cetp gene 37, resulting in two alleles B1 and b2. The cetp taqib polymorphism is associated with changes in plasma cetp Concentrations, hdl cholesterol, and risk of cad39-43. Individuals with b1 allele have higher Cetp mass, cetp activity and low hdl cholesterol than individuals with b2 allele 40. Most Of the reports in asians have shown a positive association between the b1 allele and cad 44,45 due to its intronic location this polymorphism cannot be considered as a part of a Functional regulatory site, but can be a marker for another functional site. Its effect on plasma Cetp mass and hdl-c can be accounted by its linkage with many 5′ promoter region base Changes like −629c/a, −971g/a and −1337c/t polymorphisms 46-48. In view of this we have evaluated the distribution of cholesteryl ester transfer protein Gene taq1b polymorphism and the concerned phonotype (cholesteryl ester transfer protein Activity) was analysed by using a fluorometric assay kit

Regulation of reverse cholesterol transport - a comprehensive appraisal of available animal studies

Plasma levels of high density lipoprotein (HDL) cholesterol are strongly inversely correlated to the risk of atherosclerotic cardiovascular disease. A major recognized functional property of HDL particles is to elicit cholesterol efflux and consequently mediate reverse cholesterol transport (RCT). The recent introduction of a surrogate method aiming at determining specifically RCT from the macrophage compartment has facilitated research on the different components and pathways relevant for RCT. The current review provides a comprehensive overview of studies carried out on macrophage-specific RCT including a quick reference guide of available data. Knowledge and insights gained on the regulation of the RCT pathway are summarized. A discussion of methodological issues as well as of the respective relevance of specific pathways for RCT is also included

HDL and reverse cholesterol transport in humans and animals: Lessons from pre-clinical models and clinical studies

The ability to accept cholesterol from cells and to promote reverse cholesterol transport (RCT) represents the best characterized antiatherogenic function of HDL. Studies carried out in animal models have unraveled the multiple mechanisms by which these lipoproteins drive cholesterol efflux from macrophages and cholesterol uptake to the liver. Moreover, the influence of HDL composition and the role of lipid transporters have been clarified by using suitable transgenic models or through experimental design employing pharmacological or nutritional interventions. Cholesterol efflux capacity (CEC), an in vitro assay developed to offer a measure of the first step of RCT, has been shown to associate with cardiovascular risk in several human cohorts, supporting the atheroprotective role of RCT in humans as well. However, negative data in other cohorts have raised concerns on the validity of this biomarker. In this review we will present the most relevant data documenting the role of HDL in RCT, as assessed in classical or innovative methodological approaches

Evaluating inhibitory potential targeting cholesteryl ester transfer protein (CETP) by hydroxycitric acid (HCA) found in garcinia species through kinetic and in-silico technique

Cardiovascular disease has emerged in developing countries and becoming the leading cause of death recorded. Many scientific studies have been conducted in order to understand the specific mechanism on how atherosclerosis develop, searching for the real culprit that responsible in the progression of the disease and suggesting the possible prevention to overcome this problem. This piece of work examined and revealed the mechanism of action on how secondary metabolites that has been isolated from Malaysian local plants which have the properties to impede the action of cholesteryl ester transfer protein (CETP) in order to prevent the atherosclerosis. Preliminary results of the crude plant extracts from the initial screening showed positive results. A similar trend of inhibition can be obtained for twigs and leaves extracts of Garcinia atroviridis and Garcinia parvifolia. Ethanol extracts of fruit parts of Garcinia atroviridis give IC50 of 19.28 ± 0.021 mg/ml which shows the highest inhibitory compared to the other extracts of other plant parts. The remarkable results that are obtain from fruit rinds of Garcinia atroviridis do give some hints that the secondary metabolites that are present might have the ability to inhibit CETP. Based on literature review, it is postulated hydroxycitric acid (HCA) might be responsible for inhibiting CETP activity and HCA has been selected for further studies. Kinetic studies have been employed in this piece of work in order to see the types of inhibition that HCA possess against CETP. The kinetic study has revealed that HCA is a noncompetitive inhibitor because of the Km (-0.12) that is unchanged for every substrate and the Vmax is increased when the concentration of the inhibitor increase. Further in-silico works such as molecular docking and molecular dynamic has been implemented as well in order to see the interaction and mechanism of action between HCA and CETP. The molecular docking work has revealed that HCA binds to the same side as torcetrapib does and the RMSD obtained was 2.703Å. Molecular dynamics has been employed as well in order to see the extensive structural and functional analysis and also to evaluate the strengthness of the complex between HCA and CETP. The complex were found to be stable due to the existence of the hydrogen bonding to SER230 and the overall RMSD reading are between the range of 0.8Å, 2.4Å and 3.2Å. Overall, this work are pioneering and pave the way for further studies in establishing a new chemical template form of natural products for CETP research with an objective to extend the scope of work into in-vivo studies and x-ray crystallography in order to enable us to understand the mechanism of action in protein level. The in-silico studies in this work provides a preliminary understanding on the structural basis of CETP structure and its active sites which could accommodate the exact template of chemical molecule. With this new understanding, an inhibitor drug which are effective with lesser side effect, targeting atherosclerosis could be developed

Kolesteroliesterien siirtäjäproteiinin ja anacetrapib-lääkeaineen välisten vuorovaikutusten tutkiminen molekyylisimulaatioilla

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in Western societies. The most important cause behind these diseases is a complex condition affecting arterial blood vessels denoted as atherosclerosis. Atherosclerosis is inflicted and restrained by lipoproteins circulating in blood. More specifically, high levels of low density lipoprotein (LDL) have been found to correlate positively and high levels of high density lipoprotein (HDL) inversely with the risk of atherosclerosis. High LDL levels can be reduced by the use of statins, a strategy that has successively reduced the rate of CVD. However, a significant residual risk still remains since atherosclerosis is a multifactorial disease. Because low HDL levels are an independent risk factor, elevating HDL has become one the most promising strategies in the fight against CVD. Clinical trials have shown that this can be achieved through the inhibition of cholesteryl ester transfer protein (CETP), which transports neutral lipids between different lipoprotein fractions. A novel molecular agent, anacetrapib, has been found to meet these requirements but the precise inhibitory mechanism remains to be elucidated. In this study the interactions between CETP and anacetrapib were examined using atomistic molecular dynamics simulations. Extensive structural and functional analysis were performed for both particles. The obtained results point towards the important regulatory roles of helix X and phospholipids during the lipid exchange process. These structures were found to experience considerable conformational fluctuations induced by the drug, indicating the possible capability of anacetrapib to inhibit the functions of CETP. The performed simulations are pioneering and pave the way for further studies, with an objective to extend the scope of computational studies to gain a much deeper understanding concerning the inhibition of CETP. The novel insight could be used in the development of new molecular agents capable of preventing the progression of CVD

Affected by abundant PLTP : the atherogenic role of a lipid transfer protein in transgenic mice

__Abstract__ Atherosclerosis is a progressive disease of the large and medium-sized arteries. The disease is characterised by endothelial dysfunction, inflammation and the accumulation of fatty and fibrous substances in the vessel wall, resulting in thickening and loss of elasticity of the arteries. The word atherosclerosis has been derived from the Greek words "athera", porridge or gruel, and "skleros", hard or stiff. These words describe the external features of the lipid-loaded lesions that characterize the disease. Although atherosclerosis has been discovered in blood vessels of people living more than 3000 years ago, until the end of the 18th century its prevalence was very rare. During the 20th century, mortality caused by atherosclerosis strongly increased. Nowadays, complications of atherosclerosis are the main cause of death in the developed world, and are predicted to be the leading cause of death worldwide by the year 2020 (Fonarow, 2007). It is difficult to accurately determine the true frequency of atherosclerosis because it is a predominantly asymptomatic condition (Kavey et al., 2006). Early atherosclerotic lesions can already be found in the aorta shortly after birth, increasing in number during childhood. More advanced lesions begin to develop at an age of approximately 25 years. Generally, the clinical manifestations of the disease become apparent in the sixth decade of life

Evaluating inhibitory potential targeting cholesteryl ester transfer protein (CETP) by hydroxycitric acid (HCA) found in garcinia species through kinetic and in-silico technique

Cardiovascular disease has emerged in developing countries and becoming the leading cause of death recorded. Many scientific studies have been conducted in order to understand the specific mechanism on how atherosclerosis develop, searching for the real culprit that responsible in the progression of the disease and suggesting the possible prevention to overcome this problem. This piece of work examined and revealed the mechanism of action on how secondary metabolites that has been isolated from Malaysian local plants which have the properties to impede the action of cholesteryl ester transfer protein (CETP) in order to prevent the atherosclerosis. Preliminary results of the crude plant extracts from the initial screening showed positive results. A similar trend of inhibition can be obtained for twigs and leaves extracts of Garcinia atroviridis and Garcinia parvifolia. Ethanol extracts of fruit parts of Garcinia atroviridis give IC50 of 19.28 ± 0.021 mg/ml which shows the highest inhibitory compared to the other extracts of other plant parts. The remarkable results that are obtain from fruit rinds of Garcinia atroviridis do give some hints that the secondary metabolites that are present might have the ability to inhibit CETP. Based on literature review, it is postulated hydroxycitric acid (HCA) might be responsible for inhibiting CETP activity and HCA has been selected for further studies. Kinetic studies have been employed in this piece of work in order to see the types of inhibition that HCA possess against CETP. The kinetic study has revealed that HCA is a noncompetitive inhibitor because of the Km (-0.12) that is unchanged for every substrate and the Vmax is increased when the concentration of the inhibitor increase. Further in-silico works such as molecular docking and molecular dynamic has been implemented as well in order to see the interaction and mechanism of action between HCA and CETP. The molecular docking work has revealed that HCA binds to the same side as torcetrapib does and the RMSD obtained was 2.703Å. Molecular dynamics has been employed as well in order to see the extensive structural and functional analysis and also to evaluate the strengthness of the complex between HCA and CETP. The complex were found to be stable due to the existence of the hydrogen bonding to SER230 and the overall RMSD reading are between the range of 0.8Å, 2.4Å and 3.2Å. Overall, this work are pioneering and pave the way for further studies in establishing a new chemical template form of natural products for CETP research with an objective to extend the scope of work into in-vivo studies and x-ray crystallography in order to enable us to understand the mechanism of action in protein level. The in-silico studies in this work provides a preliminary understanding on the structural basis of CETP structure and its active sites which could accommodate the exact template of chemical molecule. With this new understanding, an inhibitor drug which are effective with lesser side effect, targeting atherosclerosis could be developed