Cholesterol Ester Transfer Protein Activity Research Articles

Effects of dietary interventions and intermittent fasting on HDL function in obese individuals with T2DM: a randomized controlled trial

BackgroundCardiovascular disease represents a significant risk factor for mortality in individuals with type 2 diabetes mellitus (T2DM). High-density lipoprotein (HDL) is believed to play a crucial role in maintaining cardiovascular health through its multifaceted atheroprotective effects and its capacity to enhance glycemic control. The impact of dietary interventions and intermittent fasting (IF) on HDL functionality remains uncertain. The objective of this study was to assess the effects of dietary interventions and IF as a strategy to safely improve glycemic control and reduce body weight on functional parameters of HDL in individuals with T2DM.MethodsBefore the 12-week intervention, all participants (n = 41) of the INTERFAST-2 study were standardized to a uniform basal insulin regimen and randomized to an IF or non-IF group. Additionally, all participants were advised to adhere to dietary recommendations that promoted healthy eating patterns. The IF group (n = 19) followed an alternate-day fasting routine, reducing their calorie intake by 75% on fasting days. The participants’ glucose levels were continuously monitored. Other parameters were measured following the intervention: Lipoprotein composition and subclass distribution were measured by nuclear magnetic resonance spectroscopy. HDL cholesterol efflux capacity, paraoxonase 1 (PON1) activity, lecithin cholesterol acyltransferase (LCAT) activity, and cholesterol ester transfer protein (CETP) activity were assessed using cell-based assays and commercially available kits. Apolipoprotein M (apoM) levels were determined by ELISA.ResultsFollowing the 12-week intervention, the IF regimen significantly elevated serum apoM levels (p = 0.0144), whereas no increase was observed in the non-IF group (p = 0.9801). ApoM levels correlated with weight loss and fasting glucose levels in the IF group. Both groups exhibited a robust enhancement in HDL cholesterol efflux capacity (p < 0.0001, p = 0.0006) after 12 weeks. Notably, only the non-IF group exhibited significantly elevated activity of PON1 (p = 0.0455) and LCAT (p = 0.0117) following the 12-week intervention. In contrast, the changes observed in the IF group did not reach statistical significance.ConclusionsA balanced diet combined with meticulous insulin management improves multiple metrics of HDL function. While additional IF increases apoM levels, it does not further enhance other aspects of HDL functionality.Trial registrationThe study was registered at the German Clinical Trial Register (DRKS) on 3 September 2019 under the number DRKS00018070.Graphical

The Endogenous Inhibitor of CETP, apoC1, Remains Ineffective In Vivo after Correction of Hyperglycemia in People with Type 1 Diabetes.

ApolipoproteinC1 (apoC1) is the main physiological inhibitor of the cholesterol ester transfer protein (CETP). Increased CETP activity is associated with macrovascular complications in patients with type 1 diabetes (T1D). ApoC1 has lost its ability to inhibit CETP in patients with T1D, and in vitro glycation of apoC1 increases CETP activity, suggesting that hyperglycemia could be a factor implicated in the loss of the inhibitory effect of apoC1 on CETP. Thus, we aimed to see whether improvement of glycemic control might restore apoC1 inhibitory effect on CETP. We studied 98 patients with T1D and HbA1c > 9% at baseline and 3 months after improvement of glycemic control by a medical intervention (insulin introduction or changes in multi-injection therapy or pump therapy introduction/therapeutic education for all patients). CETP activity was assessed by a radioactive method and plasma apoC1 levels were measured by ELISA. The different isoforms of apoC1 were determined by mass spectrometry. CETP activity was not significantly modified after improvement of glycemic control, despite a significant reduction in mean HbA1c (8.7 ± 1.7 vs. 10.8 ± 2, p < 0.0001). No association between plasma apoC1 and CETP activity was observed in patients with T1D at baseline, nor at 3 months, even in the subgroup of patients with optimal control (3-month HbA1c < 7%). We did not find any glycated form of apoC1 using mass spectrometry in people with T1D. Hyperglycemia in vivo does not seem to be a major factor implicated in the loss of apoC1 ability to inhibit CETP activity observed in T1D. Other factors, such as qualitative abnormalities of lipoproteins, could be involved. Our data emphasize the fact that hyperglycemia is not the only factor involved in lipid abnormalities and macrovascular complications in T1D. Clinical trial reg. no. NCT02816099 ClinicalTrials.gov.

Impaired HDL antioxidant and anti-inflammatory functions are linked to increased mortality in acute heart failure patients

AimsAcute heart failure (AHF) is typified by inflammatory and oxidative stress responses, which are associated with unfavorable patient outcomes. Given the anti-inflammatory and antioxidant properties of high-density lipoprotein (HDL), this study sought to examine the relationship between impaired HDL function and mortality in AHF patients. The complex interplay between various HDL-related biomarkers and clinical outcomes remains poorly understood. MethodsHDL subclass distribution was quantified by nuclear magnetic resonance spectroscopy. Lecithin–cholesterol acyltransferase (LCAT) activity, cholesterol ester transfer protein (CETP) activity, and paraoxonase (PON-1) activity were assessed using fluorometric assays. HDL-cholesterol efflux capacity (CEC) was assessed in a validated assay using [3H]-cholesterol-labeled J774 macrophages. ResultsAmong the study participants, 74 (23.5 %) out of 315 died within three months after hospitalization due to AHF. These patients exhibited lower activities of the anti-oxidant enzymes PON1 and LCAT, impaired CEC, and lower concentration of small HDL subclasses, which remained significant after accounting for potential confounding factors. Smaller HDL particles, particularly HDL3 and HDL4, exhibited a strong association with CEC, PON1 activity, and LCAT activity. ConclusionsIn patients with AHF, impaired HDL CEC, HDL antioxidant and anti-inflammatory function, and impaired HDL metabolism are associated with increased mortality. Assessment of HDL function and subclass distribution could provide valuable clinical information and help identify patients at high risk.

Cholesterol Metabolic Profiling of HDL in Women with Late-Onset Preeclampsia.

A specific feature of dyslipidemia in pregnancy is increased high-density lipoprotein (HDL) cholesterol concentration, which is probably associated with maternal endothelium protection. However, preeclampsia is most often associated with low HDL cholesterol, and the mechanisms behind this change are scarcely explored. We aimed to investigate changes in HDL metabolism in risky pregnancies and those complicated by late-onset preeclampsia. We analyze cholesterol synthesis (cholesterol precursors: desmosterol, 7-dehydrocholesterol, and lathosterol) and absorption markers (phytosterols: campesterol and β-sitosterol) within HDL particles (NCSHDL), the activities of principal modulators of HDL cholesterol's content, and major HDL functional proteins levels in mid and late pregnancy. On the basis of the pregnancy outcome, participants were classified into the risk group (RG) (70 women) and the preeclampsia group (PG) (20 women). HDL cholesterol was lower in PG in the second trimester compared to RG (p < 0.05) and followed by lower levels of cholesterol absorption markers (p < 0.001 for campesterolHDL and p < 0.05 for β-sitosterolHDL). Lowering of HDL cholesterol between trimesters in RG (p < 0.05) was accompanied by a decrease in HDL phytosterol content (p < 0.001), apolipoprotein A-I (apoA-I) concentration (p < 0.05), and paraoxonase 1 (PON1) (p < 0.001), lecithin-cholesterol acyltransferase (LCAT) (p < 0.05), and cholesterol ester transfer protein (CETP) activities (p < 0.05). These longitudinal changes were absent in PG. Development of late-onset preeclampsia is preceded by the appearance of lower HDL cholesterol and NCSHDL in the second trimester. We propose that reduced capacity for intestinal HDL synthesis, decreased LCAT activity, and impaired capacity for HDL-mediated cholesterol efflux could be the contributing mechanisms resulting in lower HDL cholesterol.

HDL and Cholesterol Ester Transfer Protein (CETP).

Cholesterol ester transfer protein (CETP) is important clinically and is one of the major targets in cardiovascular disease studies. With high conformational flexibility, its tunnel structure allows unforced movement of high-density lipoproteins (HDLs), VLDLs, and LDLs. Research in reverse cholesterol transports (RCT) reveals that the regulation of CETP activity can change the concentration of cholesteryl esters (CE) in HDLs, VLDLs, and LDLs. These molecular insights demonstrate the mechanisms of CETP activities and manifest the correlation between CETP and HDL. However, animal and cell experiments focused on CETP give controversial results. Inhibiting CETP is found to be beneficial to anti-atherosclerosis in terms of increasing plasma HDL-C, while it is also claimed that CETP weakens atherosclerosis formation by promoting RCT. Currently, the CETP-related drugs are still immature. Research on CETP inhibitors is targeted at improving efficacy and minimizing adverse reactions. As for CETP agonists, research has proved that they also can be used to resist atherosclerosis.

EPA and DHA Have Differential Effects on Cholesterol Ester Transfer Protein and Lipoprotein Lipase Activities Following Plasma Triglycerides Lowering

Abstract Objectives Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are effective in reducing plasma triglyceride (TG) concentrations but have divergent effects on LDL cholesterol (LDL-C) concentrations. Differential regulations of cholesterol ester transfer protein (CETP) and lipoprotein lipase (LPL) activities are possible mechanisms of their differential effects. We assessed the effects of EPA and DHA supplementation on plasma lipid profiles and two enzyme activities involved in lipoprotein metabolism. Methods Nine men and twelve postmenopausal women (N = 21, 50–75y) with chronic inflammation (CRP &amp;gt; 2 mg/L) were enrolled in a randomized, double-blind, crossover trial consisting of a 4-wk lead-in phase with high oleic acid sunflower oil (3 g/d) followed by two 10-wk EPA and DHA supplementation phases (3 g/d each) separated by a 10-wk washout phase. Plasma was collected after the lead-in (baseline) and each n-3 fatty acid supplementation phase for analysis of TG, total cholesterol and HDL-C, and CETP and post-heparin LPL activities. LDL-C was estimated using the Friedewald formula. Results Subjects were recruited to have moderately elevated TG and LDL-C concentrations (mean ± SEM: 141 ± 11 and 130 ± 6 mg/dL, respectively). Compared to baseline, EPA supplementation lowered TG concentration (−28 ± 6 mg/dL, P &amp;lt; 0.001) and CETP activity (−1.6 ± 1.1 µg/mL/h, P &amp;lt; 0.05), whereas LDL-C concentration and LPL activity were unchanged. The changes in TG concentration and CETP activity were negatively correlated with baseline TG (r = −0.77 and −0.45, respectively, both P &amp;lt; 0.05). DHA supplementation lowered TG concentration (−31 ± 8 mg/dL, P &amp;lt; 0.001), and increased LDL-C concentration (+10 ± 4 mg/dL, P &amp;lt; 0.01) and LPL activity (+6.1 ± 4.0 mU/mL, P &amp;lt; 0.03), CETP activity was unchanged. The DHA-mediated increase in LPL activity was correlated with the baseline TG concentration and change in TG concentration (r = 0.64 and ρ = −0.45, respectively, both P &amp;lt; 0.05). Conclusions In the context of the established TG-lowering effects of EPA and DHA, these n-3 fatty acids affected CETP and LPL activities differently. DHA-induced change in LDL-C concentration may be related to increased LPL activity, and the conversion of very low-density lipoprotein to LDL. Funding Sources AFRI/NIFA; USDA.

ApoE and apoC-III-defined HDL subtypes: a descriptive study of their lecithin cholesterol acyl transferase and cholesteryl ester transfer protein content and activity

BackgroundThe functionality of high-density lipoproteins (HDL) is a better cardiovascular risk predictor than HDL concentrations. One of the key elements of HDL functionality is its apolipoprotein composition. Lecithin-cholesterol acyl transferase (LCAT) and cholesterol-ester transfer protein (CETP) are enzymes involved in HDL-mediated reverse cholesterol transport. This study assessed the concentration and activity of LCAT and CETP in HDL subspecies defined by their content of apolipoproteins E (apoE) and C-III (apoC-III) in humans.MethodsEighteen adults (ten women and eight men, mean age 55.6, BMI 26.9 Kg/m2, HbA1c 5.4%) were studied. HDL from each participant were isolated and divided into four subspecies containing respectively: No apoE and no apoC-III (E-C-), apoE but not apoC-III (E + C-), apoC-III but no apoE (E-C+) and both apoE and apoC-III (E + C+). The concentration and enzymatic activity of LCAT and CETP were measured within each HDL subspecies using immunoenzymatic and fluorometric methods. Additionally, the size distribution of HDL in each apolipoprotein-defined fraction was determined using non-denaturing electrophoresis and anti-apoA-I western blotting.ResultsHDL without apoE or apoC-III was the predominant HDL subtype. The size distribution of HDL was very similar in all the four apolipoprotein-defined subtypes. LCAT was most abundant in E-C- HDL (3.58 mg/mL, 59.6% of plasma LCAT mass), while HDL with apoE or apoC-III had much less LCAT (19.8, 12.2 and 8.37% of plasma LCAT respectively for E + C-, E-C+ and E + C+). LCAT mass was lower in E + C- HDL relative to E-C- HDL, but LCAT activity was similar in both fractions, signaling a greater activity-to-mass ratio associated with the presence of apoE. Both CETP mass and CETP activity showed only slight variations across HDL subspecies. There was an inverse correlation between plasma LCAT activity and concentrations of both E-C+ pre-beta HDL (r = − 0.55, P = 0.017) and E-C- alpha 1 HDL (r = − 0.49, P = 0.041). Conversely, there was a direct correlation between plasma CETP activity and concentrations of E-C+ alpha 1 HDL (r = 0.52, P = 0.025).ConclusionsThe presence of apoE in small HDL is correlated with increased LCAT activity and esterification of plasma cholesterol. These results favor an interpretation that LCAT and apoE interact to enhance anti-atherogenic pathways of HDL.

Temporal Dynamics of High-Density Lipoprotein Proteome in Diet-Controlled Subjects with Type 2 Diabetes.

We examined the effect of mild hyperglycemia on high-density lipoprotein (HDL) metabolism and kinetics in diet-controlled subjects with type 2 diabetes (T2D). 2H2O-labeling coupled with mass spectrometry was applied to quantify HDL cholesterol turnover and HDL proteome dynamics in subjects with T2D (n = 9) and age- and BMI-matched healthy controls (n = 8). The activities of lecithin–cholesterol acyltransferase (LCAT), cholesterol ester transfer protein (CETP), and the proinflammatory index of HDL were quantified. Plasma adiponectin levels were reduced in subjects with T2D, which was directly associated with suppressed ABCA1-dependent cholesterol efflux capacity of HDL. The fractional catabolic rates of HDL cholesterol, apolipoprotein A-II (ApoA-II), ApoJ, ApoA-IV, transthyretin, complement C3, and vitamin D-binding protein (all p < 0.05) were increased in subjects with T2D. Despite increased HDL flux of acute-phase HDL proteins, there was no change in the proinflammatory index of HDL. Although LCAT and CETP activities were not affected in subjects with T2D, LCAT was inversely associated with blood glucose and CETP was inversely associated with plasma adiponectin. The degradation rates of ApoA-II and ApoA-IV were correlated with hemoglobin A1c. In conclusion, there were in vivo impairments in HDL proteome dynamics and HDL metabolism in diet-controlled patients with T2D.

APOE-knockout in rabbits causes loss of cells in nucleus pulposus and enhances the levels of inflammatory catabolic cytokines damaging the intervertebral disc matrix.

Rabbits with naturally high levels of cholesterol ester transfer protein (CETP), unlike rodents, have become an interesting animal model for the study of lipid metabolism and atherosclerosis, as they have similarities to humans in lipid metabolism, cardiovascular physiology and susceptibility to develop atherosclerosis. Rodents, such as mice, are not prone to atherosclerosis as they lack the mass and activity of CETP, as a key player in lipoprotein metabolism. Recently, APOE-knockout in rabbits has been shown to promote atherosclerosis and associated premature IVD degeneration that mimic the symptoms of atherosclerosis and structural changes of IVDs in humans. Here we examined whether APOE-knockout promoted IVD degeneration in rabbits is associated with imbalanced inflammatory catabolic activities, as the underlying problem of biological deterioration that mimic the symptoms of advanced IVD degeneration in humans. We analysed in lumbar nucleus pulposus (NP) of APOE-knockout rabbits the cell viabilities and the intracellular levels of inflammatory, catabolic, anti-catabolic and anabolic proteins derogating IVD matrix. Grades of IVD degeneration were evaluated by magnetic resonance imaging. NP cells were isolated from homozygous APOE-knockout and wild-type New Zealand White rabbits of similar age. Three-dimensional cell culture with low-glucose was completed in alginate hydrogel. Cell proliferation and intracellular levels of target proteins were examined by MTT and ELISA assays. Alike human NP cells of different disc degeneration grades, NP cells of APOE-knockout and wild-type rabbits showed significantly different in vivo cell population densities (p<0.0001) and similar in vitro proliferation rates. Furthermore, they showed differences in overexpression of selective inflammatory and catabolic proteins (p<0.0001) similar to those found in human NP cells of different disc degeneration grades, such as IL-1β, TNF-α, ADAMTS-4, ADAMTS-5 and MMP-3. This study showed that premature IVD degeneration in APOE-knockout rabbits was promoted by the accumulation of selective inflammatory catabolic factors that enhanced imbalances between catabolic and anabolic factors mimicking the symptoms of advanced IVD degeneration in humans. Thus, APOE-knockout rabbits could be used as a promising model for therapeutic approaches of degenerative disc disorders.

HDL flux is higher in patients with nonalcoholic fatty liver disease.

Altered lipid metabolism and inflammation are involved in the pathogenesis of both nonalcoholic fatty liver disease (NAFLD) and cardiovascular disease (CVD). Even though high-density lipoprotein (HDL), a CVD protective marker, is decreased, whether HDL metabolism and function are perturbed in NAFLD are currently unknown. We examined the effect of NAFLD and disease severity on HDL metabolism and function in patients with biopsy-proven simple steatosis (SS), nonalcoholic steatohepatitis (NASH), and healthy controls. HDL turnover and HDL protein dynamics in SS (n = 7), NASH (n = 8), and healthy controls (n = 9) were studied in vivo. HDL maturation and remodeling, antioxidant, cholesterol efflux properties, and activities of lecithin-cholesterol ester acyltransferase and cholesterol ester transfer protein (CETP) were quantified using in vitro assays. All patients with NAFLD had increased turnover of both HDL cholesterol (HDLc; 0.16 ± 0.09 vs. 0.34 ± 0.18 days, P < 0.05) and apolipoprotein A1 (ApoAI) (0.26 ± 0.04 vs. 0.34 ± 0.06 days, P < 0.005) compared with healthy controls. The fractional catabolic rates of other HDL proteins, including ApoAII (and ApoAIV) were higher (P < 0.05) in patients with NAFLD who also had higher CETP activity, ApoAI/HDLc ratio (P < 0.05). NAFLD-induced alterations were associated with lower antioxidant (114.2 ± 46.6 vs. 220.5 ± 48.2 nmol·mL-1·min-1) but higher total efflux properties of HDL (23.4 ± 1.3% vs. 25.5 ± 2.3%) (both P < 0.05), which was more pronounced in individuals with NASH. However, no differences were observed in either HDL turnover, antioxidant, and cholesterol efflux functions of HDL or HDL proteins' turnover between subjects with SS and subjects with NASH. Thus, HDL metabolism and function are altered in NAFLD without any significant differences between SS and NASH.

Clinical Pharmacokinetics and Pharmacodynamics of Dalcetrapib.

The cholesterol ester transfer protein (CETP) inhibitor dalcetrapib has been under evaluation for its potential to prevent cardiovascular (CV) events for almost two decades. The current clinical development program, representing new advances in precision medicine and focused on a genetically defined population with acute coronary syndrome (ACS), is supported by a large body of pharmacokinetic and pharmacodynamic data as well as substantial clinical experience in over 13,000 patients and volunteers. Dalcetrapib treatment of 600 mg/day produces significant inhibition of CETP activity, and has been utilized in phase II and III studies, including CV endpoint trials. Numerous studies have investigated the interactions between dalcetrapib and most drugs commonly prescribed to CV patients and have not demonstrated any clinically significant effects. Evaluations in patients with renal and hepatic impairment demonstrate a greater exposure to dalcetrapib than in the non-impaired population, but long-term clinical studies including patients with mild to moderate hepatic and renal dysfunction demonstrate no increase in adverse events. Safety pharmacology and toxicology studies as well as the clinical safety experience support the continuing development of dalcetrapib as an adjunct to ‘standard of care’ for the ACS population. This article provides a full review of the pharmacokinetics, as well as pharmacodynamics and pharmacology, of dalcetrapib in the context of a large clinical program.

Oxidized and electronegative low-density lipoprotein as potential biomarkers of cardiovascular risk in obese adolescents

OBJECTIVES:To evaluate biomarkers associated with early cardiometabolic risk in obese adolescents.METHODS:This cross-sectional study included 137 adolescents of both sexes aged 10 to 19 years divided into a normal weight group (NW) (n=69) and an obese group (OB) (n=68).RESULTS:As expected, obesity showed positive associations with homeostatic model assessment for insulin resistance (HOMA-IR), triacylglycerol, insulin, plasma levels of non-esterified fatty acids, and cholesterol ester transfer protein activity and negative associations with plasma antioxidant levels. Plasma oxidized low-density lipoprotein (oxLDL) and electronegative low-density lipoprotein [LDL(-)] levels were significantly higher in the OB group. Higher tertiles of oxLDL were associated with increased values of body mass index; waist circumference; fatty mass percentage (%FM); and the atherogenic lipids non-high-density-lipoprotein cholesterol (non-HDL-C), low-density lipoprotein cholesterol (LDL-C), apolipoprotein B and triacylglycerol. Higher tertiles of LDL(-) were robustly associated with body mass index and waist circumference. Logistic regression models (odds ratios) confirmed that increased values of lipids and apolipoprotein B were associated with increased risk of oxLDL. For LDL(-), these associations were not significant, suggesting that another mechanism is involved in generating this particle in obese adolescents.CONCLUSIONS:Obese adolescents showed increased plasma LDL(-) and oxLDL, and obese girls had more LDL(-) than obese boys. Therefore, oxLDL is strongly and independently associated with classical cardiovascular risk factors, while increased levels of LDL(-) were influenced by body mass index, waist circumference and demographic parameters in obese adolescents.

Functionality of High-Density Lipoprotein as Antiatherosclerotic Therapeutic Target.

A great majority of the morbidity and mortality worldwide can still be attributed to cardiovascular diseases, such as ischemic (coronary) heart disease, angina pectoris, and myocardial and cerebral infarction. Atherosclerosis, narrowing of the arteries because of arterial cholesterol deposition in macrophage foam cells, is the driving force behind the cardiovascular disease pathology. Water-soluble protein/lipid complexes called lipoproteins mediate the transport of cholesterol and other lipoid substances through the blood compartment. Relatively high levels of cholesterol associated with apolipoprotein B–containing low-density lipoprotein (LDL) particles predispose human subjects to the development of atherosclerosis and, thereby, increase the risk for cardiovascular disease.1,2 Apolipoprotein B–containing lipoproteins are, therefore, generally regarded as being proatherogenic factors. Cholesterol ester–rich high-density lipoprotein (HDL) particles use apolipoprotein A1 (apoA1) as their primary protein component. In sharp contrast to LDL, HDL is considered a potent anti-atherogenic agent. This notion is based on the fact that, in the general population, a strong inverse correlation exists between plasma levels of HDL cholesterol and the risk of cardiovascular disease.1 Of note, this inverse association seems to be independent of the level of cholesterol associated with proatherogenic LDL particles. As such, increasing plasma levels of HDL cholesterol has long been regarded a promising alternative therapy to supplement classical statin–based LDL cholesterol–lowering strategies that are able to reduce cardiovascular disease by only ≈30%.3 However, over the last decade, the enthusiasm for HDL as an interesting therapeutic target has been challenged by the HDL hypothesis critics because genetic association studies have excluded HDL cholesterol levels as determinants for cardiovascular disease risk.2,4 Furthermore, several therapeutic HDL-targeting approaches have proven insufficient to secure benefit for cardiovascular disease patients. Niacin is the most effective drug available in the clinic to raise plasma HDL cholesterol levels. Despite the fact that niacin is …

Mathematically modelling the dynamics of cholesterol metabolism and ageing

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in the UK. This condition becomes increasingly prevalent during ageing; 34.1% and 29.8% of males and females respectively, over 75 years of age have an underlying cardiovascular problem. The dysregulation of cholesterol metabolism is inextricably correlated with cardiovascular health and for this reason low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) are routinely used as biomarkers of CVD risk. The aim of this work was to use mathematical modelling to explore how cholesterol metabolism is affected by the ageing process. To do this we updated a previously published whole-body mathematical model of cholesterol metabolism to include an additional 96 mechanisms that are fundamental to this biological system. Additional mechanisms were added to cholesterol absorption, cholesterol synthesis, reverse cholesterol transport (RCT), bile acid synthesis, and their enterohepatic circulation. The sensitivity of the model was explored by the use of both local and global parameter scans. In addition, acute cholesterol feeding was used to explore the effectiveness of the regulatory mechanisms which are responsible for maintaining whole-body cholesterol balance. It was found that our model behaves as a hypo-responder to cholesterol feeding, while both the hepatic and intestinal pools of cholesterol increased significantly. The model was also used to explore the effects of ageing in tandem with three different cholesterol ester transfer protein (CETP) genotypes. Ageing in the presence of an atheroprotective CETP genotype, conferring low CETP activity, resulted in a 0.6% increase in LDL-C. In comparison, ageing with a genotype reflective of high CETP activity, resulted in a 1.6% increase in LDL-C. Thus, the model has illustrated the importance of CETP genotypes such as I405V, and their potential role in healthy ageing.

Marked lowering of high-density lipoprotein cholesterol levels due to high dose bexarotene therapy

Bexarotene is a retinoid X receptor agonist, which is currently used for the treatment of cutaneous T-cell lymphoma (CTCL). It is known to induce central hypothyroidism as well as dyslipidemia including elevation of triglycerides (TG) and low-density lipoprotein cholesterol along with slight lowering of high-density lipoprotein cholesterol (HDL-C). Marked lowering of HDL-C has never been previously reported in bexarotene-treated patients and whether it is related to hypothyroidism remains unclear. A 49-year-old African female with a history of CTCL on treatment with bexarotene of 300 mg/d, presented with serum total cholesterol level of 249 mg/dL (6.4 mmol/L), TG level of 92 mg/dL (1.03 mmol/L), HDL-C level of 78 mg/dL (2.02 mmol/L), thyroid stimulating hormone (TSH) of 0.68 μIU/mL, and free thyroxine level of 0.5 ng/dL. Six months later, on increasing the bexarotene dose to 600 mg daily, serum TG increased to 310 mg/dL (3.5 mmol/L) and HDL-C dropped to 3 to 5 mg/dL (0.077-0.13 mmol/L), whereas the TSH was undetectable (0.01 μIU/mL). Despite adequate levothyroxine replacement to 225 μg daily resulting in free thyroxine levels up to 1.5 ng/dL, HDL-C remained extremely low of 4 to 9 mg/dL (0.103-0.233 mmol/L). Bexarotene was discontinued due to poor response of CTCL, 3 months after which her HDL-C levels returned to baseline of 80 to 90 mg/dL (2.07-2.33 mmol/L). High dose bexarotene can markedly lower HDL-C levels, which normalize on discontinuation of the drug. Lowering of HDL-C with bexarotene may be due to an increase in cholesterol ester transfer protein activity and appears to be independent of central hypothyroidism.

Gestational diabetes mellitus modulates neonatal high-density lipoprotein composition and its functional heterogeneity

Gestational diabetes mellitus (GDM) is related to neonatal macrosomia and an increased risk of vascular events. We hypothesized that GDM exerts qualitative effects on neonatal high-density lipoprotein (HDL). HDL was isolated from control (n=11) and GDM maternal/neonatal donors (n=9) and subjected to shotgun proteomics. Differences in HDL mobility were assessed by FPLC and native gel-electrophoresis. Paraoxonase (PON1) activity, cholesterol ester-transfer protein (CETP) mass and activity, phospholipid, triglyceride and cholesterol concentrations were quantified with commercial kits. Total anti-oxidative capacity and cholesterol efflux capability of HDLs were measured. Four proteins involved in lipid metabolism, inflammation and innate immunity were differentially expressed between controls and GDM neonates. ApoM (decreased, p<0.05) and SAA1 (increased, p<0.05) showed the same differences on both, maternal and neonatal GDM HDL. Lower PON1 protein expression was corroborated by lower activity (p<0.05) which in turn was associated with attenuated anti-oxidant capacity of GDM HDL. Protein changes were accompanied by increased levels of triglycerides and decreased levels of cholesterol esters, respectively. The observed differences in GDM HDL lipid moiety may be related to CETP mass and activity alterations. The rate of cholesterol efflux from term trophoblasts to maternal and from placental endothelial cells to neonatal GDM HDL was impaired (p<0.05). In conclusion, GDM causes changes in HDL composition and is intimately associated with impaired cholesterol efflux capability as well as diminished anti-oxidative particle properties. Remodeling of neonatal GDM HDL in utero supports the hypothesis that maternal conditions in pregnancy impact neonatal lipoprotein metabolism.

Korean red ginseng combined with nattokinase ameliorates dyslipidemia and the area of aortic plaques in high cholesterol-diet fed rabbits

Male white rabbits were fed a high cholesterol diet supplemented with red ginseng (RG) or red ginseng plus nattokinase (RGNK). RG and RGNK significantly reduced increased serum triglycerides levels and aortic plaque area in a hypercholesterol diet fed rabbits. Moreover, only RGNK reduced hepatic cholesterol and cholesteryl ester transfer protein activity levels. Therefore, the present study suggests RGNK might be a potential therapeutic approach for atherogenesis.

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

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

AB0339 Role of cholesterol ester transfer protein in inflammation mediated dyslipidemia of rheumatoid arthritis patients

ObjectivesRheumatoid Arthritis (RA) patients show alterations in cholesterol and lypoproteins levels. These disturbances seem to be related to the inflammation that takes place in the disease, but the pathological mechanisms...

Angptl3 Deficiency Is Associated With Increased Insulin Sensitivity, Lipoprotein Lipase Activity, and Decreased Serum Free Fatty Acids

Angiopoietin-like 3 (Angptl3) is a regulator of lipoprotein metabolism at least by inhibiting lipoprotein lipase activity. Loss-of-function mutations in ANGPTL3 cause familial combined hypolipidemia through an unknown mechanism. We compared lipolytic activities, lipoprotein composition, and other lipid-related enzyme/lipid transfer proteins in carriers of the S17X loss-of-function mutation in ANGPTL3 and in age- and sex-matched noncarrier controls. Gel filtration analysis revealed a severely disturbed lipoprotein profile and a reduction in size and triglyceride content of very low density lipoprotein in homozygotes as compared with heterozygotes and noncarriers. S17X homozygotes had significantly higher lipoprotein lipase activity and mass in postheparin plasma, whereas heterozygotes showed no difference in these parameters when compared with noncarriers. No changes in hepatic lipase, endothelial lipase, paraoxonase 1, phospholipid transfer protein, and cholesterol ester transfer protein activities were associated with the S17X mutation. Plasma free fatty acid, insulin, glucose, and homeostatic model assessment of insulin resistance were significantly lower in homozygous subjects compared with heterozygotes and noncarriers subjects. These results indicate that, although partial Angptl3 deficiency did not affect the activities of lipolytic enzymes, the complete absence of Angptl3 results in an increased lipoprotein lipase activity and mass and low circulating free fatty acid levels. This latter effect is probably because of decreased mobilization of free fatty acid from fat stores in human adipose tissue and may result in reduced hepatic very low density lipoprotein synthesis and secretion via attenuated hepatic free fatty acid supply. Altogether, Angptl3 may affect insulin sensitivity and play a role in modulating both lipid and glucose metabolism.