Search

Current structural and functional investigations of cholesteryl ester transfer protein (CETP) inhibitor design are nearly entirely based on a fully active mutation (CETPMutant) constructed for protein crystallization, limiting the study of the dynamic structural features of authentic CETP involved in lipid transport under physiological conditions. In this study, we conducted comprehensive molecular dynamics (MD) simulations of both authentic CETP (CETPAuthentic) and CETPMutant. Considering the structural differences between the N- and C-terminal domains of CETPAuthentic and CETPMutant, and their crucial roles in lipid transfer, we identified the two domains as binding pockets of the ligands for virtual screening to discover potential lead compounds targeting CETP. Our results revealed that CETPAuthentic displays greater flexibility and pronounced curvature compared to CETPMutant. Employing virtual screening and MD simulation strategies, we found that ZINC000006242926 has a higher binding affinity for the N- and C-termini, leading to reduced N- and C-opening sizes, disruption of the continuous tunnel, and increased curvature of CETP. In conclusion, CETPAuthentic facilitates the formation of a continuous tunnel in the neck region, while CETPMutant does not exhibit such characteristics. The ligand ZINC000006242926 screened for binding to the N- and C-termini induces structural changes in the CETP unfavorable to lipid transport. This study sheds new light on the relationship between the structural and functional mechanisms of CETP. Furthermore, it provides novel ideas for the precise regulation of CETP functions.

High levels of plasma cholesterol, especially high levels of low-density lipoprotein cholesterol (LDL-C), have been associated with an increased risk of Alzheimer's disease. The cholesteryl ester transfer protein (CETP) in plasma distributes cholesteryl esters between lipoproteins and increases LDL-C in plasma. Epidemiologically, decreased CETP activity has been associated with sustained cognitive performance during aging, longevity, and a lower risk of Alzheimer's disease. Thus, pharmacological CETP inhibitors could be repurposed for the treatment of Alzheimer's disease as they are safe and effective at lowering CETP activity and LDL-C. Although CETP is mostly expressed by the liver and secreted into the bloodstream, it is also expressed by astrocytes in the brain. Therefore, it is important to determine whether CETP inhibitors can enter the brain. Here, we describe the pharmacokinetic parameters of the CETP inhibitor evacetrapib in the plasma, liver, and brain tissues of CETP transgenic mice. We show that evacetrapib crosses the blood-brain barrier and is detectable in brain tissue 0.5 h after a 40 mg/kg i.v. injection in a non-linear function. We conclude that evacetrapib may prove to be a good candidate to treat CETP-mediated cholesterol dysregulation in Alzheimer's disease. [ABSTRACT FROM AUTHOR]

Purpose of Review: Cholesteryl ester transfer proteins (CETP) regulate plasma cholesterol levels by transferring cholesteryl esters (CEs) among lipoproteins. Lipoprotein cholesterol levels correlate with the risk factors for atherosclerotic cardiovascular disease (ASCVD). This article reviews recent research on CETP structure, lipid transfer mechanism, and its inhibition. Recent Findings: Genetic deficiency in CETP is associated with a low plasma level of low-density lipoprotein cholesterol (LDL-C) and a profoundly elevated plasma level of high-density lipoprotein cholesterol (HDL-C), which correlates with a lower risk of atherosclerotic cardiovascular disease (ASCVD). However, a very high concentration of HDL-C also correlates with increased ASCVD mortality. Considering that the elevated CETP activity is a major determinant of the atherogenic dyslipidemia, i.e., pro-atherogenic reductions in HDL and LDL particle size, inhibition of CETP emerged as a promising pharmacological target during the past two decades. CETP inhibitors, including torcetrapib, dalcetrapib, evacetrapib, anacetrapib and obicetrapib, were designed and evaluated in phase III clinical trials for the treatment of ASCVD or dyslipidemia. Although these inhibitors increase in plasma HDL-C levels and/or reduce LDL-C levels, the poor efficacy against ASCVD ended interest in CETP as an anti-ASCVD target. Nevertheless, interest in CETP and the molecular mechanism by which it inhibits CE transfer among lipoproteins persisted. Insights into the structural-based CETP-lipoprotein interactions can unravel CETP inhibition machinery, which can hopefully guide the design of more effective CETP inhibitors that combat ASCVD. Summary: Individual-molecule 3D structures of CETP bound to lipoproteins provide a model for understanding the mechanism by which CETP mediates lipid transfer and which in turn, guide the rational design of new anti-ASCVD therapeutics. [ABSTRACT FROM AUTHOR]

High levels of plasma cholesterol, especially high levels of low-density lipoprotein cholesterol (LDL-C), have been associated with an increased risk of Alzheimer’s disease. The cholesteryl ester transfer protein (CETP) in plasma distributes cholesteryl esters between lipoproteins and increases LDL-C in plasma. Epidemiologically, decreased CETP activity has been associated with sustained cognitive performance during aging, longevity, and a lower risk of Alzheimer’s disease. Thus, pharmacological CETP inhibitors could be repurposed for the treatment of Alzheimer’s disease as they are safe and effective at lowering CETP activity and LDL-C. Although CETP is mostly expressed by the liver and secreted into the bloodstream, it is also expressed by astrocytes in the brain. Therefore, it is important to determine whether CETP inhibitors can enter the brain. Here, we describe the pharmacokinetic parameters of the CETP inhibitor evacetrapib in the plasma, liver, and brain tissues of CETP transgenic mice. We show that evacetrapib crosses the blood–brain barrier and is detectable in brain tissue 0.5 h after a 40 mg/kg i.v. injection in a non-linear function. We conclude that evacetrapib may prove to be a good candidate to treat CETP-mediated cholesterol dysregulation in Alzheimer’s disease.

Current structural and functional investigations of cholesteryl ester transfer protein (CETP) inhibitor design are nearly entirely based on a fully active mutation (CETPMutant) constructed for protein crystallization, limiting the study of the dynamic structural features of authentic CETP involved in lipid transport under physiological conditions. In this study, we conducted comprehensive molecular dynamics (MD) simulations of both authentic CETP (CETPAuthentic) and CETPMutant. Considering the structural differences between the N- and C-terminal domains of CETPAuthentic and CETPMutant, and their crucial roles in lipid transfer, we identified the two domains as binding pockets of the ligands for virtual screening to discover potential lead compounds targeting CETP. Our results revealed that CETPAuthentic displays greater flexibility and pronounced curvature compared to CETPMutant. Employing virtual screening and MD simulation strategies, we found that ZINC000006242926 has a higher binding affinity for the N- and C-termini, leading to reduced N- and C-opening sizes, disruption of the continuous tunnel, and increased curvature of CETP. In conclusion, CETPAuthentic facilitates the formation of a continuous tunnel in the “neck” region, while CETPMutant does not exhibit such characteristics. The ligand ZINC000006242926 screened for binding to the N- and C-termini induces structural changes in the CETP unfavorable to lipid transport. This study sheds new light on the relationship between the structural and functional mechanisms of CETP. Furthermore, it provides novel ideas for the precise regulation of CETP functions.

Psoriasis is a common inflammatory skin disease, which is tightly associated with metabolic disorders. Cholesteryl ester transfer protein (CETP) and sortilin (SORT) are molecules engaged in lipid metabolism of proatherogenic properties. They have been hardly ever studied in psoriasis before. Serum CETP and SORT concentrations were measured in 33 patients with plaque-type psoriasis before and after 12 weeks of treatment with methotrexate or acitretin. There was no significant difference in CEPT and SORT serum concentrations between patients and controls. Positive correlations between CETP after the treatment with acitretin and activity of transaminases (R = 0.65, R = 0.56, respectively) were noted. CETP was positively related with triglycerides (R = 0.49), glucose (R = 0.54) and CRP (R = 0.64) before the treatment with methotrexate, which all disappeared afterwards. Systemic therapy with methotrexate caused normalization of SORT concentration. There was significant correlation between SORT and WBC (p < 0.01) and CRP (p < 0.05). CETP and SORT cannot be used as individual biomarkers. Nevertheless, they show some interesting relations with other parameters. Increased concentration of CETP perhaps could investigated as a marker of liver side effects of acitretin treatment in psoriatics. SORT could be considered as a new indicator of metabolically induced inflammation in psoriasis. Methotrexate may be preferred in patients with high SORT concentrations. Further studies are needed to establish their exact role in psoriatic patients. [ABSTRACT FROM AUTHOR]

Introduction: Low high-density lipoprotein (HDL)-cholesterol is frequent in patients with peripheral artery disease (PAD) and also in type 2 diabetes mellitus (T2DM), the major risk factor for PAD. The transfer of cholesterol from the other lipoproteins to HDL is an important aspect of HDL metabolism and function, and may contribute to atherogenic mechanisms that lead to PAD development. Objective: The aim of this study was to investigate the status of cholesterol transfers in patients with PAD without or with T2DM. Methods: Patients with PAD (n = 19), with PAD and T2DM (PAD + DM, n = 19), and healthy controls (n = 20), all paired for age, sex, and BMI were studied. Transfer of both forms of cholesterol, unesterified (UC) and esterified (EC), was performed by incubating plasma with a donor nanoemulsion containing radioactive UC and EC, followed by chemical precipitation and HDL radioactive counting. Results: Low-density lipoprotein (LDL)-cholesterol and triglycerides were similar in the three groups. Compared to controls, HDL-C was lower in PAD + DM (p < 0.05), but not in PAD. Transfer of UC was lower in PAD + DM than in PAD and controls (4.18 ± 1.17%, 5.13 ± 1.44%, 6.59 ± 1.25%, respectively, p < 0.001). EC transfer tended to be lower in PAD + DM than in controls (2.96 ± 0.60 vs 4.12 ± 0.89%, p = 0.05). Concentrations of cholesteryl ester transfer protein (CETP) and lecithin-cholesterol acyltransferase (LCAT), both involved in HDL metabolism, were not different among the three groups. Conclusion: Deficient cholesterol transfer to HDL may play a role in PAD pathogenesis. Since UC transfer to HDL was lower in PAD + DM compared to PAD alone, it is possible that defective HDL metabolism may contribute to the higher PAD incidence in patients with T2DM.Keywords [ABSTRACT FROM AUTHOR]

Abstract Elevated triglycerides (TGs) and impaired TG clearance increase the risk of cardiovascular disease in both men and women, but molecular mechanisms remain poorly understood. Cholesteryl ester transfer protein (CETP) is a lipid shuttling protein known for its effects on high‐density lipoprotein cholesterol. Although mice lack CETP, transgenic expression of CETP in mice alters TG metabolism in males and females by sex‐specific mechanisms. A unifying mechanism explaining how CETP alters TG metabolism in both males and females remains unknown. Since low‐density lipoprotein receptor (LDLR) regulates both TG clearance and very low density lipoprotein (VLDL) production, LDLR may be involved in CETP‐mediated alterations in TG metabolism in both males and females. We hypothesize that LDLR is required for CETP to alter TG metabolism in both males and females. We used LDLR null mice with and without CETP to demonstrate that LDLR is required for CETP to raise plasma TGs and to impair TG clearance in males. We also demonstrate that LDLR is required for CETP to increase TG production and to increase the expression and activity of VLDL synthesis targets in response to estrogen. Additionally, we show that LDLR is required for CETP to enhance β‐oxidation. These studies support that LDLR is required for CETP to regulate TG metabolism in both males and females.

Psoriasis is a common inflammatory skin disease, which is tightly associated with metabolic disorders. Cholesteryl ester transfer protein (CETP) and sortilin (SORT) are molecules engaged in lipid metabolism of proatherogenic properties. They have been hardly ever studied in psoriasis before. Serum CETP and SORT concentrations were measured in 33 patients with plaque-type psoriasis before and after 12 weeks of treatment with methotrexate or acitretin. There was no significant difference in CEPT and SORT serum concentrations between patients and controls. Positive correlations between CETP after the treatment with acitretin and activity of transaminases (R = 0.65, R = 0.56, respectively) were noted. CETP was positively related with triglycerides (R = 0.49), glucose (R = 0.54) and CRP (R = 0.64) before the treatment with methotrexate, which all disappeared afterwards. Systemic therapy with methotrexate caused normalization of SORT concentration. There was significant correlation between SORT and WBC (p < 0.01) and CRP (p < 0.05). CETP and SORT cannot be used as individual biomarkers. Nevertheless, they show some interesting relations with other parameters. Increased concentration of CETP perhaps could investigated as a marker of liver side effects of acitretin treatment in psoriatics. SORT could be considered as a new indicator of metabolically induced inflammation in psoriasis. Methotrexate may be preferred in patients with high SORT concentrations. Further studies are needed to establish their exact role in psoriatic patients.

Elevated triglycerides (TGs) and impaired TG clearance increase the risk of cardiovascular disease in both men and women, but molecular mechanisms remain poorly understood. Cholesteryl ester transfer protein (CETP) is a lipid shuttling protein known for its effects on high‐density lipoprotein cholesterol. Although mice lack CETP, transgenic expression of CETP in mice alters TG metabolism in males and females by sex‐specific mechanisms. A unifying mechanism explaining how CETP alters TG metabolism in both males and females remains unknown. Since low‐density lipoprotein receptor (LDLR) regulates both TG clearance and very low density lipoprotein (VLDL) production, LDLR may be involved in CETP‐mediated alterations in TG metabolism in both males and females. We hypothesize that LDLR is required for CETP to alter TG metabolism in both males and females. We used LDLR null mice with and without CETP to demonstrate that LDLR is required for CETP to raise plasma TGs and to impair TG clearance in males. We also demonstrate that LDLR is required for CETP to increase TG production and to increase the expression and activity of VLDL synthesis targets in response to estrogen. Additionally, we show that LDLR is required for CETP to enhance β‐oxidation. These studies support that LDLR is required for CETP to regulate TG metabolism in both males and females. [ABSTRACT FROM AUTHOR]

Elevated postprandial triacylglycerols (TAG) are an important risk factor for cardiovascular disease. Men have higher plasma TAG and impaired TAG clearance compared to women, which may contribute to sex differences in risk of cardiovascular disease. Understanding mechanisms of sex differences in TAG metabolism may yield novel therapeutic targets to prevent cardiovascular disease. Cholesteryl ester transfer protein (CETP) is a lipid shuttling protein known for its effects on high‐density lipoprotein (HDL) cholesterol levels. Although mice lack CETP, we previously demonstrated that transgenic CETP expression in female mice alters TAG metabolism. The impact of CETP on TAG metabolism in males, however, is not well understood. Here, we demonstrate that CETP expression increases plasma TAG in males, especially in very‐low density lipoprotein (VLDL), by impairing postprandial plasma TAG clearance compared to wild‐type (WT) males. Gonadal hormones were required for CETP to impair TAG clearance, suggesting a role for sex hormones for this effect. Testosterone replacement in the setting of gonadectomy was sufficient to restore the effect of CETP on TAG. Lastly, liver androgen receptor (AR) was required for CETP to increase plasma TAG. Thus, expression of CETP in males raises plasma TAG by impairing TAG clearance via testosterone signaling to AR. Further understanding of how CETP and androgen signaling impair TAG clearance may lead to novel approaches to reduce TAG and mitigate risk of cardiovascular disease. [ABSTRACT FROM AUTHOR]

Abstract Background Heart failure (HF) courses with chronic inflammatory process and alterations in lipid metabolism may aggravate the disease. The aim was to test whether the severity of HF, using brain natriuretic peptide (BNP) as a marker, is associated with alterations in functional aspects of HDL, such as lipid transfer, cholesterol ester transfer protein (CETP) and lecithin-cholesterol acyltransferase (LCAT) concentration. Methods Twenty-five HF patients in NYHA class I/II and 23 in class III/IV were enrolled. Plasma lipids, apolipoproteins, CETP, LCAT, oxidized-LDL (oxLDL) and paraoxonase-1 (PON-1) activity were determined. Lipid transfer from a donor artificial nanoparticle to HDL was measured by in vitro assay. Results Total cholesterol (p = 0.049), LDL-C (p = 0.023), non-HDL-C (p = 0.029) and CETP, that promotes lipid transfer among lipoproteins (p = 0.013), were lower in III/IV than in I/II group. Triglycerides, HDL-C, apo A-I, apo B, oxLDL, LCAT, enzyme that catalyzes serum cholesterol esterification, PON-1 activity, and in vitro transfers of cholesterol, triglycerides and phospholipids to HDL, important steps in HDL metabolism, were equal. IL-8 was higher in III/IV (p = 0.025), but TNFα, IL-1β, IL-6 and MCP-1 were equal. BNP was negatively correlated with CETP (r = − 0.294; p = 0.042) and positively correlated with IL-8 (r = 0.299; p = 0.039). Conclusions Our results disclosed the relationship between CETP levels and HF severity, by comparing two HF groups and by correlation analysis. Lower CETP levels may be a marker of HF aggravation and possibly of worse prognosis. Practical applications of this initial finding, as the issue whether CETP could be protective against HF aggravation, should be explored in larger experimental and clinical studies.

Background: Hyperlipidemia is characterized by an abnormally elevated serum cholesterol, triglycerides, or both. The relationship between an elevated level of LDL and cardiovascular diseases is well-established. Cholesteryl ester transfer protein (CETP) is an enzyme that moves cholesterol esters and triglycerides between LDL, VLDL, and HDL. CETP inhibition leads to a reduction in cardiovascular disease by raising HDL and minimizing LDL., Objective: This study synthesized ten meta-chlorinated benzene sulfonamides 6a-6j and explored their structure-activity relationship., Methods: The synthesized molecules were characterized using 1H-NMR, 13C-NMR, IR, and HR-MS. Moreover, cheminformatics analyses included pharmacophore mapping, LibDock studies, and cheminformatics characterization using 2-dimensional (2D) molecular descriptors and principal component analysis., Results: Based on in vitro functional CETP assays, compounds 6e, 6i, and 6j demonstrated the strongest inhibitory activities against CETP, reaching 100% inhibition. The inhibitory activity of compounds 6a-6d and 6f-6h ranged from 47.5% to 96.5% at 10 μM concentration. Pharmacophore mapping results suggested CETP inhibitory action, while the docking scores and calculated binding energies predicted favoring binding at the CETP active site. Best-scoring docking poses predicted critical hydrophobic features corresponding to key interactions with His232 and Cys13. Cheminformatics analysis using 2D molecular descriptors indicated that the synthesized compounds span various physicochemical properties and drug-likeness., Conclusion: It was found that a chloro moiety at the ortho-position, or a nitro group at the meta and para-positions, improves the CETP inhibitory activity of synthesized analogs. Computational studies suggest the formation of stable ligand-protein complexes between compounds 6a- 6j and CETP., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Background: Heart failure (HF) courses with chronic inflammatory process and alterations in lipid metabolism may aggravate the disease. The aim was to test whether the severity of HF, using brain natriuretic peptide (BNP) as a marker, is associated with alterations in functional aspects of HDL, such as lipid transfer, cholesterol ester transfer protein (CETP) and lecithin-cholesterol acyltransferase (LCAT) concentration. Methods: Twenty-five HF patients in NYHA class I/II and 23 in class III/IV were enrolled. Plasma lipids, apolipoproteins, CETP, LCAT, oxidized-LDL (oxLDL) and paraoxonase-1 (PON-1) activity were determined. Lipid transfer from a donor artificial nanoparticle to HDL was measured by in vitro assay. Results: Total cholesterol (p = 0.049), LDL-C (p = 0.023), non-HDL-C (p = 0.029) and CETP, that promotes lipid transfer among lipoproteins (p = 0.013), were lower in III/IV than in I/II group. Triglycerides, HDL-C, apo A-I, apo B, oxLDL, LCAT, enzyme that catalyzes serum cholesterol esterification, PON-1 activity, and in vitro transfers of cholesterol, triglycerides and phospholipids to HDL, important steps in HDL metabolism, were equal. IL-8 was higher in III/IV (p = 0.025), but TNFα, IL-1β, IL-6 and MCP-1 were equal. BNP was negatively correlated with CETP (r = - 0.294; p = 0.042) and positively correlated with IL-8 (r = 0.299; p = 0.039). Conclusions: Our results disclosed the relationship between CETP levels and HF severity, by comparing two HF groups and by correlation analysis. Lower CETP levels may be a marker of HF aggravation and possibly of worse prognosis. Practical applications of this initial finding, as the issue whether CETP could be protective against HF aggravation, should be explored in larger experimental and clinical studies. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To verify whether the capacity of high-density lipoprotein (HDL) to simultaneously receive nonesterified cholesterol, triglycerides, cholesteryl esters, and phospholipids changes with aging and the presence of coronary artery disease. DESIGN: Cross-sectional study with biochemical analyses. SUBJECTS: Eleven elderly patients with coronary artery disease (74±5 years) were compared with the following groups of non-coronary artery disease subjects (referred to as "healthy"): 25 young (25±5 years), 25 middle-aged (42± years), and 25 elderly subjects (75±8 years). METHODS: Plasma samples were incubated with a nanoemulsion labeled with radioactive lipids; the transfer of the lipids from the nanoemulsion to the HDL was measured in chemically precipitated HDL. HDL size and paraoxonase-1 activity were also determined. RESULTS: The transfer of cholesteryl esters and phospholipids to high-density lipoprotein was significantly greater (p

We examined the cholesteryl ester transfer protein (CETP) gene TaqI intron 1 B1/B2 polymorphism and the -629A/C CETP promoter polymorphism in respect to high-density lipoprotein cholesterol (HDL-C) in a healthy Iranian population taken from the Tehran Lipid and Glucose Study (TLGS). The relationship between CETP activity and HDL-C level was also determined along with body mass index, blood pressure and tobacco smoking status. PCR-RFLP used to amplify a segment of the CETP intron 1 TaqI (B2/B1) polymorphism from 1021 individuals and we selected 345 individuals from the lowest, middle and highest HDL-C deciles and investigated the -629A/C polymorphism. We also evaluated the CETP activity of 103 of these individuals, each with at least one homozygous allele. The presence of the TaqI B2 and -629A/C A alleles were significantly associated with increased HDL-C levels (B2B2 = 1.19 ± 0.31 mmolL-1 vs. B1B1 = 1.01 ± 0.2 mmol L-1 for p < 0.001; AA = 1.15 ± 0.41 mmol L-1 vs. CC = 0.95 ± 0.28 mmol L-1 for p < 0.001) and decreased the CETP activity (B1B1 = 67.8 ± 8.9 pmol L-1 vs. B2B2 = 62.6 ± 9.6 pmol L-1 for p < 0.01; CC = 68.6 ± 8.4 pmol L-1 vs. AA = 62.7 ± 9.7 pmol L-1 for p < 0.002). The frequencies were 0.382 for the TaqI B2 allele and 0.462 for the -629A/C A allele, with linkage disequilibrium analysis giving D = 0.0965 and D' = 0.4695. We demonstrated that the TaqI B1 and B2 alleles and the -629A/C A and C alleles were in linkage disequilibrium in our population and that there was a significant association between the B2 and A alleles and high HDL-C levels and low CETP activity. Linkage disequilibrium between the TaqI A and B2 alleles also detected.

Background: Cholesteryl ester transfer protein (CETP) is a plasma protein that mediates the exchange of triglycerides for esterified cholesterol between HDL and apoB-lipoproteins. Previous studies suggest that CETP may modify glucose metabolism in patients or cultured cells. In this study, we tested if stable CETP expression would impair glucose metabolism. Methods: We used human CETP transgenic mice and non-transgenic littermate controls (NTg), fed with control or high fat diet, as well as in dyslipidemic background and aging conditions. Assays included glucose and insulin tolerance tests, isolated islets insulin secretion, tissue glucose uptake and adipose tissue GLUT mRNA expression. Results: CETP expression did not modify glucose or insulin tolerance in all tested conditions such as chow and high fat diet, adult and aged mice, normo and dyslipidemic backgrounds. Fasting and fed state plasma levels of insulin were not differ in CETP and NTg mice. Direct measurements of isolated pancreatic islet insulin secretion rates induced by glucose (11, 16.7 or 22 mM), KCl (40 mM), and leucine (10 mM) were similar in NTg and CETP mice, indicating that CETP expression did not affect β-cell function in vivo and ex vivo. Glucose uptake by insulin target tissues, measured in vivo using 3H-2-deoxyglucose, showed that CETP expression had no effect on the glucose uptake in liver, muscle, perigonadal, perirenal, subcutaneous and brown adipose tissues. Accordingly, GLUT1 and GLUT4 mRNA in adipose tissue were not affected by CETP. Conclusions: In summary, by comparing the in vivo all-or-nothing CETP expressing mouse models, we demonstrated that CETP per se has no impact on the glucose tolerance and tissue uptake, global insulin sensitivity and beta cell insulin secretion rates. [ABSTRACT FROM AUTHOR]

Objectives: We determine the significant relation of HDL cholesterol and total cholesterol/HDL cholesterol between CETP I405V genotypes and activity of CETP. CETP is an essential for transfer of cholesterol ester to the liver from peripheral tissues which facilitating its transfer to TG rich VLDL. Reduction activity of CETP I405V may associate with genotypes of CETP I405V. This study is undertaken to assess the presence and impact of CETP I405V genotype in our population. Materials and Methods: In this study 100 acute myocardial infarction patients and 100 normal age & sex matched healthy individuals were included. Serum Lipid profile was estimated by using universal standard methods whereas CETP I405V genotype was studied by ARMS PCR. Result: There is presence of CETP 405Val genotype both in patient as well as in control group. Results show that HDL cholesterol (p

Introduction Genetic inhibition of Cholesteryl Ester Transfer Protein (CETP) might be associated with insulin resistance and incident type 2 diabetes mellitus (T2DM). This study investigated the relation between a genetic variant in the CETP gene and measures of insulin resistance and incident T2DM in patients with manifest cardiovascular disease (CVD). Furthermore the effect on risk of recurrent cardiovascular events was investigated. Methods SMART is a prospective cohort study performed in 5601 patients with clinically manifest CVD. We selected a variant (rs3764261) associated with reduced CETP activity and increased levels of HDL cholesterol (HDL-C). Patients were divided in three groups: 2640 wild type patients (GG), 2420 heterozygotes for rs3764261 (GT) and 541 homozygotes for rs3764261 (TT). Regression analyses were performed using an additive model. Results The study population consisted of 4656 patients without T2DM and 945 patients with T2DM at baseline. Presence of rs3764261 was associated with increased HDL-C in patients without T2DM (β 0.106, 95%CI 0.083–0.128) and with T2DM (β 0.043, 95%CI 0.007–0.078). During a median follow up of 7.2 years (IQR 4.7–10.2) 427 incident T2DM occurred. Presence of rs3764261 was not related to incident T2DM (HR 0.96, 95%CI 0.83–1.11) in patients without T2DM at baseline. Furthermore, presence of rs3764261 was not related to insulin resistance (glucose, insulin, HOMA-IR, HbA1c) or recurrent CVD (HR 0.92, 95%CI 0.84–1.02). Conclusion Presence of CETP SNP rs3764261 is not associated with insulin resistance and incident T2DM in patients with clinically manifest vascular disease. Furthermore, no effect of rs3764261 on the risk of recurrent CVD was observed. [ABSTRACT FROM AUTHOR]

Macrophage markers in skeletal muscle of obese subjects are elevated and inversely relate to insulin sensitivity. The present study aimed to investigate whether short-term high-fat high-calorie (HFHC) diet already increases macrophage markers and affects glucose metabolism in skeletal muscle of healthy lean subjects. Muscle biopsies were obtained from 24 healthy lean young men before and after a 5-day HFHC-diet. mRNA expression levels of relevant genes in muscle and glucose, insulin, C-peptide and cholesteryl ester transfer protein (CETP) levels in plasma were measured. In addition, we assessed hepatic triacylglycerol ('triglyceride') (HTG) content by magnetic resonance spectroscopy and subcutaneous white adipose tissue (sWAT) biopsies were analysed histologically from a subset of subjects (n=8). A 5-day HFHC-diet markedly increased skeletal muscle mRNA expression of the general macrophage markers CD68 (3.7-fold, P<0.01) and CD14 (3.2-fold, P<0.01), as well as the M1 macrophage markers MARCO (11.2-fold, P<0.05), CD11c (1.8-fold, P<0.05) and MRC1 (1.7-fold, P<0.05). This was accompanied by down-regulation of SLC2A4 and GYS1 mRNA expression, and elevated plasma glucose (+4%, P<0.001) and insulin (+55%, P<0.001) levels together with homoeostasis model assessment of insulin resistance (HOMA-IR) (+48%, P<0.001), suggesting development of insulin resistance (IR). Furthermore, the HFHC-diet markedly increased HTG (+118%, P<0.001) and plasma CETP levels (+21%, P<0.001), a marker of liver macrophage content, whereas sWAT macrophage content remained unchanged. In conclusion, short-term HFHC-diet increases expression of macrophage markers in skeletal muscle of healthy men accompanied by reduced markers of insulin signalling and development of IR. Therefore, recruitment of macrophages into muscle may be an early event in development of IR in response to short-term HFHC-feeding. [ABSTRACT FROM AUTHOR]

Epidemiologic studies have shown that low-density lipoprotein cholesterol (LDL-C) is a strong risk factor, whilst high-density lipoprotein cholesterol (HDL-C) reduces the risk of coronary heart disease (CHD). Therefore, strategies to manage dyslipidemia in an effort to prevent or treat CHD have primarily attempted at decreasing LDL-C and raising HDL-C levels. Cholesteryl ester transfer protein (CETP) mediates the exchange of cholesteryl ester for triglycerides between HDL and VLDL and LDL. We have published the first report indicating that a group of Japanese patients who were lacking CETP had extremely high HDL-C levels, low LDL-C levels and a low incidence of CHD. Animal studies, as well as clinical and epidemiologic evidences, have suggested that inhibition of CETP provides an effective strategy to raise HDL-C and reduce LDL-C levels. Four CETP inhibitors have substantially increased HDL-C levels in dyslipidemic patients. This review will discuss the current status and future prospects of CETP inhibitors in the treatment of CHD. At present anacetrapib by Merck and evacetrapib by Eli Lilly are under development. By 100mg of anacetrapib HDL-C increased by 138%, and LDL-C decreased by 40%. Evacetrapib 500 mg also showed dramatic 132% increase of HDL-C, while LDL-C decreased by 40%. If larger, long-term, randomized, clinical end point trials could corroborate other findings in reducing atherosclerosis, CETP inhibitors could have a significant impact in the management of dyslipidemic CHD patients. Inhibition of CETP synthesis by antisense oligonucleotide or small molecules will produce more similar conditions to human CETP deficiency and may be effective in reducing atherosclerosis and cardiovascular events. We are expecting the final data of prospective clinical trials by CETP inhibitors in 2015. [ABSTRACT FROM AUTHOR]

Novel ester derivatives of 2, 10-dichloro-12 H-dibenzo [d,g] 1,3 dioxocin-6-carboxylic acid were synthesized and evaluated for their in vitro human cholesteryl ester transfer protein (CETP) inhibition. Three out of twelve synthesized compounds showed good inhibition of CETP (more than 50 %). Compound 10 showed 81.32 % inhibition of CETP at the dose of 0.5 nM whereas compound 11 showed 75.78 % inhibition when tested at the same concentration. Compound 8 and 13 also showed modest activity with 57.44 and 38.02 % inhibition. All other synthesized compounds were devoid of significant inhibitory activity against CETP. We also performed molecular docking to predict the mode of binding of all compounds at the active site of CETP. Compound 10 showed the dock score of −9.16 whereas the dock score of compound 11 was found to be −9.09. [ABSTRACT FROM AUTHOR]

The cholesteryl ester transfer protein (CETP), inhibition of which assists in maintaining a high level of high-density lipoprotein cholesterol in the blood, is a target for anti-atherosclerosis treatments. Orange monascus pigment was produced by a Monascus species in a 5 L jar fermenter and various derivative compounds were synthesised by incorporating 19 different l-amino acids into the orange pigment. Among them, the l-Thr and l-Tyr derivatives exhibited high inhibitory activities against the CETP reaction. The inhibitory activities of the l-Thr and l-Tyr derivatives increased in a dose-dependent manner, resulting in IC50 values of 1.0 and 2.3 μM, respectively. When CETP reactions in the presence of the derivatives were performed, the inhibition modes of the l-Thr and l-Tyr derivatives were non-competitive with inhibition constant (Ki) values of 2.7 and 4.3 μM, respectively. [ABSTRACT FROM AUTHOR]

Abstract: The mammalian target of rapamycin (mTOR) inhibiting drug rapamycin (Sirolimus) has severe side effects in patients including hyperlipidemia, an established risk factor for atherosclerosis. Recently, it was shown that rapamycin decreases hepatic LDL receptor (LDL-R) expression, which likely contributes to hypercholesterolemia. Scavenger receptor, class B, type I (SR-BI) is the major HDL receptor and consequently regulating HDL-cholesterol levels and the athero-protective effects of HDL. By using the mTOR inhibitor rapamycin, we show that SR-BI is down-regulated in human umbilical vein endothelial cells (HUVECs). This reduction of SR-BI protein as well as mRNA levels by about 50% did not alter HDL particle uptake or HDL-derived lipid transfer. However, rapamycin reduced HDL-induced activation of eNOS and stimulation of endothelial cell migration. The effects on cell migration could be counteracted by SR-BI overexpression, indicating that decreased SR-BI expression is in part responsible for the rapamycin-induced effects. We demonstrate that inhibition of mTOR leads to endothelial cell dysfunction and decreased SR-BI expression, which may contribute to atherogenesis during rapamycin treatment. [Copyright &y& Elsevier]

Abstract: Lipidomics has developed rapidly over the past decade to the point where clinical application may soon be possible. Developments including high throughput technologies enable the simultaneous quantification of several hundred lipid species, thereby providing a global assessment of lipid metabolism. Given the key role of lipids in the pathophysiology of diabetes and cardiovascular disease, lipidomics has the potential to: [i)] Significantly improve prediction of future disease risk, [ii)] Inform on mechanisms of disease pathogenesis, [iii)] Identify patient groups responsive to particular therapies and [iv)] More closely monitor response to therapy. Lipidomic analyses of both whole plasma and lipoprotein subfractions are integral to the current initiative to understand the relationships between lipoprotein composition and function and how these are affected by disease and treatment. This approach will not only aid in appropriate targeting of existing lipid lowering therapies such as statins and fibrates, but will be important in unravelling the controversies surrounding HDL-based therapies which have failed in clinical trials to date. The ultimate utility of lipidomics to clinical practice will depend firstly on the ability of risk prediction models incorporating lipidomic parameters to significantly improve upon conventional clinical risk markers in predicting future disease risk. Secondly, for widespread application, lipidomic-based measurements must be practical and accessible through standard pathology laboratories. This review will cover developments in lipidomics including methodology, bioinformatics/statistics, insights into disease pathophysiology, the effect of therapeutic interventions, the role of large clinical outcome trials in validating lipidomic approaches to patient management and potential applications in clinical practice. [Copyright &y& Elsevier]

Objectives: We determine the significant relation of HDL cholesterol and total cholesterol/HDL cholesterol between CETP I405V genotypes and activity of CETP. CETP is an essential for transfer of cholesterol ester to the liver from peripheral tissues which facilitating its transfer to TG rich VLDL. Reduction activity of CETP I405V may associate with genotypes of CETP I405V. This study is undertaken to assess the presence and impact of CETP I405V genotype in our population. Materials and Methods: In this study 100 acute myocardial infarction patients and 100 normal age & sex matched healthy individuals were included. Serum Lipid profile was estimated by using universal standard methods whereas CETP I405V genotype was studied by ARMS PCR. Result: There is presence of CETP 405Val genotype both in patient as well as in control group. Results show that HDL cholesterol (p<0.0001) and ratio of total cholesterol/HDL cholesterol are significantly (p<0.0043) associated with Val/Val genotype. In addition to that the CETP I405V genotype is associated with inhibition of CETP activity with higher HDL-C level and decreased total cholesterol/HDL cholesterol ratio. Conclusion: Our results show that the CETP I405V genotypes are very much significantly determinant of HDL cholesterol in patients with CHD. [ABSTRACT FROM AUTHOR]

Abstract: Cholesteryl ester transfer protein (CETP) is a plasma protein that reduces high density lipoprotein (HDL)-cholesterol (chol) levels and may increase atherosclerosis risk. n-3 and n-6 polyunsaturated fatty acids (PUFAs) are natural ligands, and fibrates are synthetic ligands for peroxisome proliferator activated receptor-alpha (PPARα), a transcription factor that modulates lipid metabolism. In this study, we investigated the effects of PUFA oils and fibrates on CETP expression. Hypertriglyceridemic CETP transgenic mice were treated with gemfibrozil, fenofibrate, bezafibrate or vehicle (control), and normolipidemic CETP transgenic mice were treated with fenofibrate or with fish oil (FO; n-3 PUFA rich), corn oil (CO, n-6 PUFA rich) or saline. Compared with the control treatment, only fenofibrate significantly diminished triglyceridemia (50%), whereas all fibrates decreased the HDL-chol level. Elevation of the CETP liver mRNA levels and plasma activity was observed in the fenofibrate (53%) and gemfibrozil (75%) groups. Compared with saline, FO reduced the plasma levels of nonesterified fatty acid (26%), total chol (15%) and HDL-chol (20%). Neither of the oil treatments affected the plasma triglyceride levels. Compared with saline, FO increased the plasma adiponectin level and reduced plasma leptin levels, whereas CO increased the leptin levels. FO, but not CO, significantly increased the plasma CETP mass (90%) and activity (23%) as well as increased the liver level of CETP mRNA (28%). In conclusion, fibrates and FO, but not CO, up-regulated CETP expression at both the mRNA and protein levels. We propose that these effects are mediated by the activation of PPARα, which acts on a putative PPAR response element in the CETP gene. [Copyright &y& Elsevier]

Objective: Our objective was to examine the role of hypertriglyceridemia on the capacity of HDL to facilitate ABCA-1 mediated cholesterol efflux in type 2 diabetes (T2DM). Methods: HDL mediated cholesterol efflux through the ABCA-1 transporter was measured using BHK cell lines in samples of 71 participants with T2DM in the presence or absence of high triglyceride levels (TG). Additionally, HDL mediated efflux was measured in 13 diabetic and non-diabetic participants fasting and four hours after a high-fat test challenge. Results: HDL mediated cholesterol efflux function was increased in participants with T2DM with hypertriglyceridemia when compared to participants with T2DM without hypertriglyceridemia (efflux ratio mean±standard deviation (SD), T2DM+TG: 1.17±0.25 vs. T2DM − TG: 1.03±0.19, p =0.0098). In the fat challenge study, we observed a significant increase in ABCA-1 mediated cholesterol efflux capacity following an ingestion of high-fat test meal by participants in both groups of T2DM (n=6, efflux ratio, mean±SD, pre: 0.86±0.4 vs. post: 1.34±0.6, p =0.01) and non-diabetic participants (n=7, efflux ratio mean±SD pre: 1.24±0.31 vs. post: 1.39±0.42, p =0.04) that was partly explained by the difference in CETP activity (r=0.6, p =0.03). Conclusion: Our study suggests that high triglyceride levels facilitate ABCA-1 mediated efflux function of HDL in part by activating CETP. [ABSTRACT FROM AUTHOR]

Abstract: Objective: Niacin has been used for more than 50years to treat dyslipidemia, yet the mechanisms underlying its lipid-modifying effects remain unknown, a situation stemming at least in part from a lack of validated animal models. The objective of this study was to determine if the dyslipidemic hamster could serve as such a model. Materials/Methods: Dyslipidemia was induced in Golden Syrian hamsters by feeding them a high-fat, high-cholesterol, and high-fructose (HF/HF) diet. The effect of high-dose niacin treatment for 18days and 28days on plasma lipid levels and gene expression was measured. Results: Niacin treatment produced significant decreases in plasma total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), and free fatty acids (FFA), but had no measureable effect on high-density lipoprotein cholesterol (HDL-C) in the dyslipidemic hamster. Niacin treatment also produced significant increases in hepatic adenosine ATP-Binding Cassette A1 (ABCA1) mRNA, ABCA1 protein, apolipoprotein A-I (Apo A-I) mRNA, and adipose adiponectin mRNA in these animals. Conclusions: With the exception of HDL-C, the lipid effects of niacin treatment in the dyslipidemic hamster closely parallel those observed in humans. Moreover, the effects of niacin treatment on gene expression of hepatic proteins related to HDL metabolism are similar to those observed in human cells in culture. The HF/HF-fed hamster could therefore serve as an animal model for niacin’s lowering of proatherogenic lipids and mechanisms of action relative to lipid metabolism. [Copyright &y& Elsevier]

Objectives: This study sought to evaluate the vascular risk of low high-density lipoprotein-cholesterol (HDL-C) in relation to the use and intensity of lipid-lowering medication in patients with clinically manifest vascular diseases. Background: Low levels of HDL-C are associated with an increased risk for vascular diseases and may contribute to residual vascular risk in patients already treated for other risk factors. However, post-hoc analyses from statin trials indicate that the vascular risk associated with low HDL-C may be low or even absent in patients using intensive statin therapy. Methods: We performed a prospective cohort study of 6,111 patients with manifest vascular disease. Cox proportional hazards models were used to evaluate the risk of HDL-C on vascular events in patients using no, usual dose, or intensive lipid-lowering therapy. Results: New vascular events (myocardial infarction, stroke, or vascular death) occurred in 874 subjects during a median follow-up of 5.4 years (interquartile range: 2.9 to 8.6 years). In patients not using lipid-lowering medication at baseline (n = 2,153), a 0.1 mmol/l increase in HDL-C was associated with a 5% reduced risk for all vascular events (hazard ratio [HR]: 0.95; 95% confidence interval [CI]: 0.92 to 0.99). In patients on usual dose lipid-lowering medication (n = 1,910) there was a 6% reduced risk (HR: 0.94; 95% CI: 0.90 to 0.98). However, in patients using intensive lipid-lowering treatment (n = 2,046), HDL-C was not associated with recurrent vascular events (HR: 1.02; 95% CI: 0.98 to 1.07) irrespective of low-density lipoprotein cholesterol level. Conclusions: In patients with clinically manifest vascular disease using no or usual dose lipid-lowering medication, low plasma HDL-C levels are related to increased vascular risk, whereas in patients using intensive lipid-lowering medication, HDL-C levels are not related to vascular risk. [ABSTRACT FROM AUTHOR]

Objectives: This study sought to assess the independent effect of high-density lipoprotein-cholesterol (HDL-C) level on cardiovascular risk in patients with stable ischemic heart disease (SIHD) who were receiving optimal medical therapy (OMT). Background: Although low HDL-C level is a powerful and independent predictor of cardiovascular risk, recent data suggest that this may not apply when low-density lipoprotein-cholesterol (LDL-C) is reduced to optimal levels using intensive statin therapy. Methods: We performed a post-hoc analysis in 2,193 men and women with SIHD from the COURAGE trial. The primary outcome measure was the composite of death from any cause or nonfatal myocardial infarction (MI). The independent association between HDL-C levels measured after 6 months on OMT and the rate of cardiovascular events after 4 years was assessed. Similar analyses were performed separately in subjects with LDL-C levels below 70 mg/dl (1.8 mmol/l). Results: In the overall population, the rate of death/MI was 33% lower in the highest HDL-C quartile as compared with the lowest quartile, with quartile of HDL-C being a significant, independent predictor of death/MI (p = 0.05), but with no interaction for LDL-C category (p = 0.40). Among subjects with LDL-C levels <70 mg/dl, those in the highest quintile of HDL-C had a 65% relative risk reduction in death or MI as compared with the lowest quintile, with HDL-C quintile demonstrating a significant, inverse predictive effect (p = 0.02). Conclusions: In this post-hoc analysis, patients with SIHD continued to experience incremental cardiovascular risk associated with low HDL-C levels despite OMT during long-term follow-up. This relationship persisted and appeared more prominent even when LDL-C was reduced to optimal levels with intensive dyslipidemic therapy. (Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation; NCT00007657) [Copyright &y& Elsevier]

Abstract: In this study we have used mass spectrometry in order to characterize the HDL lipidome in three groups of women from the DIWA cohort; one control group, plus two groups with type 2 diabetes with insulin resistance; one dyslipidemic and one normolipidemic. The aim was to investigate whether dyslipidemia is required in addition to insulin resistance for the occurrence of an altered HDL lipidome, which in turn might impact HDL functionality. The dyslipidemic type 2 diabetic subjects were distinguished by obesity, hypertriglyceridemia with elevated apoC3, low HDL-cholesterol and chronic low grade inflammation. In a stepwise multivariate linear regression analysis, including biomarkers of dyslipidemia and insulin resistance as independent variables, only dyslipidemia showed a significant correlation with HDL lipid classes. Small HDL-particles predominated in dyslipidemic subjects in contrast to the normolipidemic diabetic and control groups, and were enriched in lysophosphatidylcholine (+13%), a product of proinflammatory phospholipases, and equally in two core lipids, palmitate-rich triacylglycerols and diacylglycerols (+77 %), thereby reflecting elevated CETP activity. Dyslipidemic small HDL particles were further distinguished not only as the primary carrier of ceramides, which promote inflammation and insulin resistance, but also by a subnormal plasmalogen/apoAI ratio, consistent with elevated oxidative stress typical of type 2 diabetes. From these data we conclude that in type 2 diabetes, dyslipidemia predominates relative to hyperglycemia for the occurrence of an altered HDL lipidome. Furthermore, dyslipidemia alters the cargo of bioactive lipids, with implications for HDL function. [Copyright &y& Elsevier]

Abstract: Cholesteryl ester transfer protein (CETP), a key regulator of high-density lipoprotein (HDL) metabolism, induces HDL remodeling by transferring lipids between apolipoprotein B-containing lipoproteins and HDL, and/or by promoting lipid transfer between HDL subparticles. In this study, we investigated the mechanism as to how CETP induces the generation of lipid-poor particles (pre-β-HDL) from HDL, which increases ATP-binding cassette transporter 1-mediated cholesterol efflux. This CETP-dependent HDL remodeling is enhanced by the CETP modulator dalcetrapib both in plasma and isolated HDL. The interaction of dalcetrapib with cysteine 13 of CETP is required, since this effect was abolished when using mutant CETP in which cysteine 13 was substituted for a serine residue. Other thiol-containing compounds were identified as CETP modulators interacting with cysteine 13 of CETP. In order to mimic dalcetrapib-bound CETP, mutant CETP proteins were prepared by replacing cysteine 13 with the bulky amino acid tyrosine or tryptophan. The resultant mutants showed virtually no CETP-dependent lipid transfer activity but demonstrated preserved CETP-dependent pre-β-HDL generation. Overall, these data demonstrate that the two functions of CETP i.e., cholesteryl ester transfer and HDL remodeling can be uncoupled by interaction of thiol-containing compounds with cysteine 13 of CETP or by introducing large amino acid residues in place of cysteine 13. [Copyright &y& Elsevier]

Copyright of Archives of Cardiovascular Diseases is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: Bile acids play multiple roles in the physiology of vertebrates; they facilitate lipid absorption, serve as signaling molecules to control carbohydrate and lipid metabolism, and provide a disposal route for cholesterol. Unexpectedly, the α-methylacyl-CoA racemase (Amacr) deficient mice, which are unable to complete the peroxisomal cleavage of C27-precursors to the mature C24-bile acids, are physiologically asymptomatic when maintained on a standard laboratory diet. The aim of this study was to uncover the underlying adaptive mechanism with special reference to cholesterol and bile acid metabolism that allows these mice to have a normal life span. Intestinal cholesterol absorption in Amacr−/− mice is decreased resulting in a 2-fold increase in daily cholesterol excretion. Also fecal excretion of bile acids (mainly C27-sterols) is enhanced 3-fold. However, the body cholesterol pool remains unchanged, although Amacr-deficiency accelerates hepatic sterol synthesis 5-fold. Changes in lipoprotein profiles are mainly due to decreased phospholipid transfer protein activity. Thus Amacr-deficient mice provide a unique example of metabolic regulation, which allows them to have a normal lifespan in spite of the disruption of a major metabolic pathway. This metabolic adjustment can be mainly explained by setting cholesterol and bile acid metabolism to a new balanced level in the Amacr-deficient mouse. [Copyright &y& Elsevier]

Abstract: During an egg-laying cycle, oviparous animals transfer massive amounts of triglycerides, the major lipid component of very low density lipoprotein (VLDL), from the liver to the developing oocytes. A major stimulus for this process is the rise in estrogen associated with the onset of an egg-laying cycle. In mammals, the microsomal triglyceride transfer protein (MTP) is required for VLDL assembly and secretion. To enable studies to determine if MTP plays a role in basal and estrogen-stimulated VLDL assembly and secretion in an oviparous vertebrate, we have cloned and sequenced the chicken MTP cDNA. This cDNA encodes a protein of 893 amino acids with an N-terminal signal sequence. The primary sequence of chicken MTP is, on average, 65% identical to that of mammalian homologs, and 23% identical to the Drosophila melanogaster protein. We have obtained a clone of chicken embryo fibroblast cells that stably express the avian MTP cDNA and show that these cells display MTP activity as measured by the transfer of a fluorescently labeled neutral lipid. As in mammals, chicken MTP is localized to the endoplasmic reticulum as revealed by indirect immunofluorescence and by the fact that its N-linked oligosaccharide moiety remains sensitive to endoglycosidase H. Endogenous, enzymatically active MTP is also expressed in an estrogen receptor-expressing chicken hepatoma cell line that secretes apolipoprotein B-containing lipoproteins. In this cell line and in vivo, the expression and activity of MTP are not influenced by estrogen. Therefore, up-regulation of MTP in the liver is not required for the increased VLDL assembly during egg production in the chicken. This indicates that MTP is not rate-limiting, even for the massive estrogen-induced secretion of VLDL accompanying an egg-laying cycle. [Copyright &y& Elsevier]

Introduction: Plasma triglycerides (TG) and HDL-C are inversely related in Metabolic Syndrome (MetS), due to exchange of VLDL-TG for HDL-cholesteryl esters catalyzed by cholesteryl ester transfer protein (CETP). We investigated the relationship of TG to HDL-C in highly-active antiretroviral drug (HAART)-treated HIV patients. Methods: Fasting plasma TG and HDL-C levels were compared in 179 hypertriglyceridemic HIV/HAART patients and 71 HIV-negative persons (31 normotriglyceridemic (NL) and 40 hypertriglyceridemic due to type IV hyperlipidemia (HTG)). CETP mass and activity were compared in 19 NL and 87 HIV/HAART subjects. Results: Among the three groups, a plot of HDL-C vs. TG gave similar slopes but significantly different y-intercepts (9.24±0.45, 8.16±0.54, 6.70±0.65, sqrt(HDL-C) for NL, HIV and HTG respectively; P<0.001); this difference persisted after adjusting HDL-C for TG, age, BMI, gender, glucose, CD4 count, viral load and HAART strata (7.18±0.20, 6.20±0.05 and 4.55±0.15 sqrt(HDL-C) for NL, HIV and HTG, respectively, P<0.001). CETP activity was not different between NL and HIV, but CETP mass was significantly higher in HIV (1.47±0.53 compared to 0.93±0.27μg/mL, P<0.0001), hence CETP specific activity was lower in HIV (22.67±13.46 compared to 28.46±8.24nmol/μg/h, P=0.001). Conclusions: Dyslipidemic HIV/HAART patients have a distinctive HDL-C plasma concentration adjusted for TG. The weak inverse relationship between HDL-C and TG is not explained by altered total CETP activity; it could result from a non-CETP-dependent mechanism or a decrease in CETP function due to inhibitors of CETP activity in HIV patients’ plasma. [ABSTRACT FROM AUTHOR]

Abstract: Takeout proteins are found across a diverse range of insect species and are thought to be involved in important aspects of insect physiology and behavior. These proteins act as ligand carriers, but the nature of their endogenous ligands remains unknown. The crystal structure of Epiphyas postvittana Takeout 1 (EpTo1), the only structure for any Takeout protein to date, revealed an α/β-wrap fold with a purely hydrophobic internal cavity of tubular shape. When recombinantly expressed in Escherichia coli, we previously showed that a surrogate ubiquinone-8 ligand binds within the internal cavity of EpTo1 with excellent shape complementarity. We have now expressed EpTo1 in an insect cell expression system devoid of ubiquinone-8, and solved its crystal structure at 2.2Å resolution. Using combined information from crystallography and mass spectrometry, we identify a mixture of fatty acid moieties, mostly myristic and palmitic acid, bound inside the EpTo1 cavity, mimicking the structure of the longer ubiquinone-8 compound. No significant alteration of the internal cavity was observed regardless of the bound ligands, ubiquinone-8 or fatty acids, suggesting that the internal cavity of EpTo1 forms a rigid scaffold that imposes strict structural constraints for selectivity and specificity of ligand(s) in vivo. [Copyright &y& Elsevier]

Abstract: Background: Recent findings suggest that DNA methylation, a well-known epigenetic mechanism, is involved in high-density lipoprotein cholesterol (HDL-C) metabolism and increased cardiovascular disease risk. The aim of this study was thus to assess whether DNA methylation within key genes of lipoprotein metabolism is associated with blood lipid profile variability. Methods and results: Ninety-eight untreated familial hypercholesterolaemia patients (61 men and 37 women) were recruited for leucocyte DNA methylation analyses at the LDLR, CETP, LCAT and LPL gene promoter loci using bisulfite pyrosequencing. LPL DNA methylation was correlated with HDL-C (r = 0.22; p = 0.031) and HDL particle size (r = 0.47, p = 0.013). In both sex, CETP DNA methylation was negatively associated with low-density lipoprotein cholesterol levels (r < −0.32; p < 0.05). In men, CETP DNA methylation was associated with HDL-C (r = −0.36; p = 0.006), HDL-triglyceride levels (r = 0.59; p < 0.001) and HDL particle size (r = −0.44, p = 0.019). In visceral adipose tissue from 30 men with severe obesity, the associations between LPL DNA methylation, HDL-C (r = −0.40; p = 0.03) and LPL mRNA levels (r = −0.61, p < 0.001) were confirmed. Conclusion: CETP and LPL DNA methylation levels are associated with blood lipid profile, suggesting that further studies of epipolymorphisms should most certainly contribute to a better understanding of the molecular bases of dyslipidemia. [Copyright &y& Elsevier]

Abstract: Background and aims: Vegan diet excludes all foodstuffs of animal origin and leads to cholesterol lowering and possibly reduction of cardiovascular disease risk. The aim was to investigate whether vegan diet improves the metabolic pathway of triglyceride-rich lipoproteins, consisting in lipoprotein lipolysis and removal from circulation of the resulting remnants and to verify whether the diet alters HDL metabolism by changing lipid transfers to this lipoprotein. Methods and results: 21 vegan and 29 omnivores eutrophic and normolipidemic subjects were intravenously injected triglyceride-rich emulsions labeled with 14C-cholesterol oleate and 3H-triolein: fractional clearance rates (FCR, in min−1) were calculated from samples collected during 60 min for radioactive counting. Lipid transfer to HDL was assayed by incubating plasma samples with a donor nanoemulsion labeled with radioactive lipids; % lipids transferred to HDL were quantified in supernatant after chemical precipitation of non-HDL fractions and nanoemulsion. Serum LDL cholesterol was lower in vegans than in omnivores (2.1 ± 0.8, 2.7 ± 0.7 mmol/L, respectively, p < 0,05), but HDL cholesterol and triglycerides were equal. Cholesteryl ester FCR was greater in vegans than in omnivores (0.016 ± 0.012, 0.003 ± 0.003, p < 0.01), whereas triglyceride FCR was equal (0.024 ± 0.014, 0.030 ± 0.016, N.S.). Cholesteryl ester transfer to HDL was lower in vegans than in omnivores (2.7 ± 0.6, 3.5 ± 1.5%, p < 0,05). Free-cholesterol, triglyceride and phospholipid transfer were equal, as well as HDL size. Conclusion: Remnant removal from circulation, estimated by cholesteryl oleate FCR was faster in vegans, but the lipolysis process, estimated by triglyceride FCR was equal. Increased removal of atherogenic remnants and diminution of cholesteryl ester transfer may favor atherosclerosis prevention by vegan diet. [Copyright &y& Elsevier]

Abstract: Dalcetrapib solubility was determined in aqueous and in non-aqueous vehicles and in biorelevant media. In a pure aqueous environment the solubility was low but could be increased by addition of surfactants or complexing agents. This was also reflected in the solubility seen in simulated gastrointestinal (GI) fluids, with almost no solubility in simulated gastric fluid, but reasonable solubilisation in simulated intestinal fluids containing lecithin and bile salt. Additionally, the stability of dalcetrapib was determined in simulated GI fluids with and without pancreatic lipase. In solutions without lipase, dalcetrapib was slowly hydrolysed, but in the presence of lipase the hydrolysis rate was significantly faster depending on pH and enzyme activity. In biological fluids, dissolved dalcetrapib appeared to behave similarly being rapidly hydrolysed in human intestinal fluids with a half-life below 20s with no degradation observed in human gastric fluids at low pH. The results provide supportive evidence that absorption is higher under fed conditions and indicate lipase inhibitors might interfere with oral absorption of dalcetrapib. [Copyright &y& Elsevier]

Eur J Clin Invest 2012; 42 (7): 709-716 Abstract Objective Accelerated cholesteryl ester transfer (CET) in patients with types 1 (T1D) and 2 diabetes enhances the atherogenicity of the apoB-containing CE acceptor lipoproteins. The study of lipoprotein density fractions cannot identify which of the five immunologically distinct apoB subclasses function as CE acceptors because they are heterogeneous and present in very low-, intermediate- and low density lipoproteins (VLDL, IDL and LDL, respectively). In order to design lipid-modifying therapies that specifically target these CE-enriched lipoprotein particles, it is necessary to first characterize their CE acceptor function. Methods and Results To identify the CE acceptors, we estimated CE net mass transfer to the apoB subclasses LpB:C, LpB:E + LpB:C:E, LpB and LpAII:B:C:D:E from changes in neutral lipids measured by gas chromatography following their separation by sequential immunoaffinity chromatography in the plasma of 12 patients with T1D and six control subjects. In both groups, CE was distributed equally to LpB:E + LpB:C:E and LpB:C. In the T1D CE acceptors, however, both the magnitude of the increase (18% vs. 10%; P < 0·01) and the per particle mass of CE transferred were significantly greater than in controls (T1D: 2·29 μmol ± 2·1 vs. control 0·43 ± 0·43/mg apoB; P < 0·047). Conclusion While LpB:E + LpB:C:E and LpB:C functioned as CE acceptors in both groups, these subclasses increased their CE content to a greater degree and accrued more CE per particle in the patients with T1D. As this disturbance in lipoprotein remodelling may increase the cholesterol burden and potential atherogenicity of these apoB subclasses, it may be a previously unrecognized factor that increases cardiovascular risk in patients with T1D. [ABSTRACT FROM AUTHOR]

Although exercise increases HDL-cholesterol, exercise-induced changes in HDL metabolism have been little explored. Lipid transfer to HDL is essential for HDL's role in reverse cholesterol transport. We investigated the effects of acute exhaustive exercise on lipid transfer to HDL. We compared plasma lipid, apolipoprotein and cytokine levels and in vitro transfer of four lipids from a radioactively labeled lipid donor nanoemulsion to HDL in sedentary individuals ( n = 28) and in marathon runners ( n = 14) at baseline, immediately after and 72 h after a marathon. While HDL-cholesterol concentrations and apo A1 levels were higher in marathon runners, LDL-cholesterol, apo B and triacylglycerol levels were similar in both groups. Transfers of non-esterified cholesterol [6.8 (5.7-7.2) vs. 5.2 (4.5-6), p = 0.001], phospholipids [21.7 (20.4-22.2) vs. 8.2 (7.7-8.9), p = 0.0001] and triacylglycerol [3.7 (3.1-4) vs. 1.3 (0.8-1.7), p = 0.0001] were higher in marathon runners, but esterified-cholesterol transfer was similar. Immediately after the marathon, LDL- and HDL-cholesterol concentrations and apo A1 levels were unchanged, but apo B and triacylglycerol levels increased. Lipid transfer of non-esterified cholesterol [6.8 (5.7-7.2) vs. 5.8 (4.9-6.6), p = 0.0001], phospholipids [21.7 (20.4-22.2) vs. 19.1 (18.6-19.3), p = 0.0001], esterified-cholesterol [3.2 (2.2-3.8) vs. 2.3 (2-2.9), p = 0.02] and triacylglycerol [3.7 (3.1-4) vs. 2.6 (2.1-2.8), p = 0.0001] to HDL were all reduced immediately after the marathon but returned to baseline 72 h later. Running a marathon increased IL-6 and TNF-α levels, but after 72 h these values returned to baseline. Lipid transfer, except esterified-cholesterol transfer, was higher in marathon runners than in sedentary individuals, but the marathon itself acutely inhibited lipid transfer. In light of these novel observations, further study is required to clarify how these metabolic changes can influence HDL composition and anti-atherogenic function. [ABSTRACT FROM AUTHOR]

Elevated low-density lipoprotein (LDL) cholesterol and lowered high-density lipoprotein (HDL) cholesterol are important risk factors for cardiovascular disease. Accordingly, raising HDL cholesterol induced by cholesteryl ester transfer protein (CETP) inhibition is an attractive approach for reducing the residual risk of cardiovascular events that persist in many patients receiving low-density LDL cholesterol-lowering therapy with statins. The development of torcetrapib, a CETP inhibitor, was terminated due to its adverse cardiovascular effects. These adverse effects did not influence the mechanism of CETP inhibition, but affected the molecule itself. Therefore a CETP modulator, dalcetrapib, and a CETP inhibitor, anacetrapib, are in Phase III of clinical trials to evaluate their effects on cardiovascular outcomes. In the dal-VESSEL (dalcetrapib Phase IIb endothelial function study) and the dal-PLAQUE (safety and efficacy of dalcetrapib on atherosclerotic disease using novel non-invasive multimodality imaging) clinical studies, dalcetrapib reduced CETP activity by 50% and increased HDL cholesterol levels by 31% without changing LDL cholesterol levels. Moreover, dalcetrapib was associated with a reduction in carotid vessel-wall inflammation at 6 months, as well as a reduced vessel-wall area at 24 months compared with the placebo. In the DEFINE (determining the efficacy and tolerability of CETP inhibition with anacetrapib) clinical study, anacetrapib increased HDL cholesterol levels by 138% and decreased LDL cholesterol levels by 36%. In contrast with torcetrapib, anacetrapib had no adverse cardiovascular effects. The potential of dalcetrapib and anacetrapib in the treatment of cardiovascular diseases will be revealed by two large-scale clinical trials, the dal-OUTCOMES (efficacy and safety of dalcetrapib in patients with recent acute coronary syndrome) study and the REVEAL (randomized evaluation of the effects of anacetrapib through lipid modification, a large-scale, randomized placebo-controlled trial of the clinical effects of anacetrapib among people with established vascular disease) study. The dal-OUTCOMES study is testing whether dalcetrapib can reduce cardiovascular events and the REVEAL study is testing whether anacetrapib can reduce cardiovascular events. These reports are expected to be released by 2013 and 2017, respectively. [ABSTRACT FROM AUTHOR]