N-3 polyunsaturated fatty acids attenuates triglyceride and inflammatory factors level in hfat-1 transgenic pigs.

BACKGROUND: The consumption of n-3 polyunsaturated fatty acids (PUFAs) is important to human health, especially in cases of cardiovascular disease. Although beneficial effects of n-3 PUFAs have been observed in a number of studies, the mechanisms involved in these effects have yet to be discovered. METHODS: We generated hfat-1 transgenic pigs with traditional somatic cell nuclear transfer (SCNT) technology. The fatty acid composition in ear tissue of pigs were detected with gas chromatography. The cholesterol, triglycerides (TAG) and inflammation mediators in circulation were investigated. RESULTS: The hfat-1 transgenic pigs were developed which accumulate high levels of n-3 PUFAs than wild-types pigs. Gas chromatography results demonstrated that the total n-3 PUFAs in the ear tissues of the transgenic founders were 2-fold higher than the wild-type pigs. A lipid analysis demonstrated that the levels of TAG in the transgenic pigs were decreased significantly. The basal levels of the inflammation mediators tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein-1 (MCP-1) and interleukin-6 (IL-6) in transgenic pigs were inhibited markedly compared with the wild-type pigs. CONCLUSIONS: These results suggest that n-3 PUFAs accumulation in vivo may have beneficial effects on vascular and hfat-1 transgenic pigs may be a useful tool for investigating the involved mechanisms.

Effects of vitamin E supplementation on cellular α-tocopherol concentrations of neutrophils in Holstein calves.

The effects of vitamin E supplementation on cellular α-tocopherol concentrations of neutrophils from Holstein calves and the mechanism of scavenger receptor class B type I (SR-BI)-mediated uptake of α-tocopherol were examined. Cellular α-tocopherol concentrations in vitamin E-treated calves increased from 3.5 ± 0.38 to 7.2 ± 0.84 µg/10(7) cells, respectively, within 14 d after vitamin E supplementation; these concentrations were significantly higher than those of control calves (P < 0.01). The expression indices of SR-BI [a major receptor that recognizes high-density lipoprotein (HDL)] mRNA in neutrophils were two to five times higher (P < 0.01) in neutrophils obtained from vitamin E-supplemented calves compared with those from control calves, and anti-SR-B1 antibody, ranging from 0.1 to 1.0 µg/mL, significantly (P < 0.01) decreased cellular α-tocopherol concentrations of neutrophils. Cytochalasin D and latrunculin B, major inhibitors of actin polymerization of neutrophils, significantly decreased cellular α-tocopherol concentrations of neutrophils (P < 0.01). Our results demonstrated that in vitamin E-supplemented calves: 1) α-tocopherol is mainly distributed with HDL, 2) α-tocopherol within HDL is recognized by SR-BI on the surface of neutrophils, and 3) rearrangement of the actin cytoskeleton is a crucial step for the uptake of α-tocopherol by neutrophils.

On a examiné les effets d'un supplément de vitamine E sur les concentrations cellulaires d'α-tocophérol des neutrophiles provenant de veaux Holstein et le mécanisme de prise d'α-tocophérol médié par les récepteurs ramasseurs de classe B type I (SR-BI). Les concentrations cellulaires d'α-tocophérol chez les veaux traités avec de la vitamine E ont augmenté de 3,5 ± 0,38 à 7,2 ± 0,84 µg/107 cellules, respectivement, à l'intérieur d'un délai de 14 j après une supplémentation en vitamine E; ces concentrations étaient significativement plus élevées que celles des veaux témoins (P < 0,01). Les taux d'expression d'ARNm de SR-BI [un récepteur majeur qui reconnaît les lipoprotéines de haute-densité (HDL)] dans les neutrophiles étaient 2 à 5 fois plus élevés (P < 0,01) dans les neutrophiles obtenus de veaux ayant reçu un supplément de vitamine E comparativement à ceux des veaux témoins, et des anticorps anti-SR-B1, allant de 0,1 à 1,0 µg/mL, ont réduit significativement (P < 0,01) les concentrations cellulaires d'α-tocophérol des neutrophiles. La cytochalasine D et la latrunculine B, des inhibiteurs majeurs de la polymérisation de l'actine des neutrophiles, ont diminué de manière significative les concentrations cellulaires d'α-tocophérol des neutrophiles (P < 0,01). Nos résultats ont démontré que chez les veaux recevant un supplément de vitamine E : 1) l'α-tocophérol est principalement distribué avec les HDL, 2) l'α-tocophérol dans les HDL est reconnu par les SR-BI sur la surface des neutrophiles, et 3) le réarrangement du cytosquelette d'actine est une étape cruciale pour la prise d'α-tocophérol par les neutrophiles.(Traduit par Docteur Serge Messier).

A lipoprotein lipase gene polymorphism interacts with consumption of alcohol and unsaturated fat to modulate serum HDL-cholesterol concentrations.

There are limited data from prospective studies regarding interactions between lipoprotein lipase gene (LPL) and lifestyle factors in association with HDL-cholesterol (HDL-C) concentrations, a biomarker of coronary heart disease risk. Our prospective cohort study investigated the interactive effects of a common LPL polymorphism and lifestyle factors, including obesity, smoking, alcohol consumption, physical activity, and dietary intake, on follow-up measurements of HDL-C and triglyceride (TG) concentrations. A total of 5314 Korean men and women aged 40-69 y participated in the study. Serum HDL-C and TG concentrations were measured in all participants at baseline and 6-y follow-up examinations. On the basis of genome-wide association data for HDL-C and TG concentrations, we selected the most significant polymorphism (rs10503669), which was in high linkage disequilibrium with the serine 447 stop (S447×) mutation (D' = 0.99) of LPL. We found that carrying the T allele reflecting the LPL ×447 allele was positively associated with follow-up measurement of HDL-C concentrations (P < 0.001). In the linear regression model adjusted for baseline HDL-C concentration and potential risk factors, we observed interactive effects of the polymorphism and consumption of alcohol (P-interaction < 0.01) and unsaturated fat (P-interaction < 0.05) on follow-up measurement of HDL-C concentrations. We also observed interactive effects of the polymorphism and body mass index (P-interaction < 0.01) on follow-up measurement of TG concentrations after adjusting for the baseline level and potential risk factors. Our findings suggest that carriers of the LPL ×447 allele benefit from moderate alcohol consumption and a diet high in unsaturated fat to minimize reduction of blood HDL-C concentrations and that obese persons who do not carry the LPL ×447 allele need to control body weight to prevent hypertriglyceridemia.

Regulation of the expression of key genes involved in HDL metabolism by unsaturated fatty acids.

The cardioprotective effects of HDL have been largely attributed to their role in the reverse cholesterol transport pathway, whose efficiency is affected by many proteins involved in the formation and remodelling of HDL. The aim of the present study was to determine the effects, and possible mechanisms of action, of unsaturated fatty acids on the expression of genes involved in HDL metabolism in HepG2 cells. The mRNA concentration of target genes was assessed by real-time PCR. Protein concentrations were determined by Western blot or immunoassays. PPAR and liver X receptor (LXR) activities were assessed in transfection experiments. Compared with the SFA palmitic acid (PA), the PUFA arachidonic acid (AA), EPA and DHA significantly decreased apoA-I, ATP-binding cassette A1 (ABCA1), lecithin-cholesterol acyltransferase (LCAT) and phospholipid transfer protein mRNA levels. EPA and DHA significantly lowered the protein concentration of apoA-I and LCAT in the media, as well as the cellular ABCA1 protein content. In addition, DHA repressed the apoA-I promoter activity. AA lowered only the protein concentration of LCAT in the media. The activity of PPAR was increased by DHA, while the activity of LXR was lowered by both DHA and AA, relative to PA. The regulation of these transcription factors by PUFA may explain some of the PUFA effects on gene expression. The observed n-3 PUFA-mediated changes in gene expression are predicted to reduce the rate of HDL particle formation and maturation.

Supplementation of Korean fermented soy paste doenjang reduces visceral fat in overweight subjects with mutant uncoupling protein-1 allele.

The purpose of this study was to examine the hypothesis that the antiobesity effect of doenjang, a Korean fermented soy paste is different between the mutant and the wild-type alleles of a polymorphism upstream of the uncoupling protein-1 (UCP-1) gene in overweight subjects. In our randomized, double-blind, placebo-controlled trial, a total of 51 subjects with a body mass index of 23 kg/m(2) or greater and a waist-to-hip ratio of 0.90 or greater for men or 0.85 or greater for women were randomly assigned to take 9.9 g/d of either a placebo or doenjang for 12 weeks. The relative frequency of the mutant G allele of the UCP-1 polymorphism was 0.60 in the placebo group and 0.62 in the doenjang group. Supplementation of doenjang had no significant effect on the visceral fat area compared with that of the placebo group, but there was a significantly reduced amount of visceral fat in subjects with the G allele of UCP-1 polymorphism. Doenjang supplementation was found to significantly increase the free fatty acid concentration in subjects with both the A allele and the G allele. There was a significant association between visceral fat and age in study subjects with both the wild-type and mutant alleles of the UCP-1 gene. Doenjang supplementation significantly reduced visceral fat and increased the free fatty acid concentrations in subjects with the G allele of the UCP-1 polymorphism, which suggests that doenjang may be related to increased free fatty acid levels caused by elevated lipolysis in these subjects.

HDL-C: role as a risk modifier.

Evidence that low-density lipoprotein-cholesterol (LDL-C) causes cardiovascular disease (CVD) is overwhelming. It has also been proven beyond all doubt that lowering the level of LDL-C using statins reduces CV risk. However, many people remain at high risk even when their level of LDL-C has been reduced by aggressive treatment with statins. One reason for this residual risk can be a low level of high-density lipoprotein-cholesterol (HDL-C). The concentration of HDL-C is an independent, inverse predictor for CVD. This relationship is apparent even when treatment with statins has reduced the level of LDL-C to below 1.8 mmol/L (70 mg/dL). It has therefore been suggested that raising the level of HDL-C should be considered as a therapeutic strategy for reducing the residual CV risk that persists in some people, despite aggressive LDL-C lowering with statins. HDL particles have several functions with the potential to protect against arterial disease, the best known of which relates to their ability to promote cholesterol efflux from macrophages in the artery wall. However, HDLs have several additional protective properties that are independent of their involvement in cholesterol metabolism. For example, they have properties that reduce oxidation, vascular inflammation and thrombosis, improve endothelial function, promote endothelial repair, enhance insulin sensitivity and promote insulin secretion by pancreatic beta islet cells. There is also a large and compelling body of evidence in animal models showing that interventions that increase HDL levels are profoundly anti-atherogenic. Major causes of low HDL are abdominal obesity and type 2 diabetes, the worldwide incidences of which are increasing at alarming rates. Strategies to increase the concentration of HDL should begin with lifestyle changes such as weight reduction, increased physical activity and smoking cessation. However, compliance with such measures is frequently poor and pharmacological intervention may be required. Currently available HDL-raising medications include fibrates, niacin and statins. There is indisputable evidence that lowering LDL-C levels using statins translates into a large reduction in CV risk. There is also mounting evidence that increasing the level of HDL-C using statins contributes to an additional reduction in CV risk. For example, the increase in HDL-C levels that was associated with simvastatin treatment in the 4S study was a significant predictor for the reduction in CV events. Moreover, a meta-analysis of 1,455 patients in 4 coronary intravascular ultrasound imaging trials showed that both the achieved level of LDL-C and the increase in HDL-C concentration during statin treatment were significant independent predictors for coronary atheroma progression as assessed by coronary intravascular ultrasound. In conclusion, evidence suggests that low levels of HDL-C are associated with an increased CV risk even when LDL-C is reduced to below 1.7 mmol/L (70 mg/dL) with a statin. Moreover, there is mounting evidence that increasing the level of HDL-C has the capacity to reduce CV risk. Thus, there is a compelling case for targeting both the LDL and HDL fractions to reduce CV risk in people with dyslipidemia, high CV risk and low levels of HDL-C.

Lecithin cholesterol acyltransferase: an anti- or pro-atherogenic factor?

Lecithin cholesterol acyl transferase (LCAT) is a plasma enzyme that esterifies cholesterol and raises high-density lipoprotein cholesterol, but its role in atherosclerosis is not clearly established. Studies of various animal models have yielded conflicting results, but studies done in rabbits and non-human primates, which more closely simulate human lipoprotein metabolism, indicate that LCAT is likely atheroprotective. Although suggestive, there are also no biomarker studies that mechanistically link LCAT with cardiovascular disease. Imaging studies of patients with LCAT deficiency have also not yielded a clear answer to the role of LCAT in atherosclerosis. Recombinant LCAT, however, is currently being developed as a therapeutic product for enzyme replacement therapy of patients with genetic disorders of LCAT for the prevention and/or treatment of renal disease, but it may also have value for the treatment of acute coronary syndrome.

Serum lipid and blood pressure responses to quercetin vary in overweight patients by apolipoprotein E genotype.

Our objective was to examine the effect of a quercetin supplementation on blood pressure, lipid metabolism, markers of oxidative stress, inflammation, and body composition in an at-risk population of 93 overweight-obese volunteers aged 25-65 y with metabolic syndrome traits in relation to apolipoprotein (apo) E genotype. Participants were randomized to receive 150 mg/d quercetin in a double-blinded, placebo-controlled, crossover trial with 6-wk treatment periods separated by a 5-wk washout period. Retrospectively, 5 apoE genotype variants were found (epsilon2/epsilon3, n = 3; epsilon3/epsilon3, n = 60; epsilon3/epsilon4, n = 23; epsilon2/epsilon4, n = 4; and epsilon4/epsilon4, n = 3). Participants were classified into the following 3 apoE phenotypes: apoE2 (n = 3), apoE3 (n = 60), and apoE4 (n = 26). Data were analyzed for apoE3 and apoE4 subgroups. Quercetin decreased systolic blood pressure by 3.4 mm Hg (P < 0.01) in the apoE3 group, whereas no significant effect was observed in the apoE4 group. Quercetin decreased serum HDL cholesterol (P < 0.01) and apoA1 (P < 0.01) and increased the LDL:HDL cholesterol ratio (P < 0.05) in the apoE4 subgroup, whereas the apoE3 subgroup had no significant changes in these variables. Quercetin significantly decreased plasma oxidized LDL and tumor necrosis factor-alpha in the apoE3 and apoE4 groups, whereas no significant inter-group differences were found. Serum C-reactive protein and nutritional status (body weight, waist circumference, fat mass, fat-free mass) were unaffected compared with placebo. In conclusion, quercetin exhibited blood pressure-lowering effects in overweight-obese carriers of the apo epsilon3/epsilon3 genotype but not in carriers of the epsilon4 allele. Furthermore, quercetin supplementation resulted in a reduction in HDL cholesterol and apoA1 in apo epsilon4 carriers.

Dietary capsanthin, the main carotenoid in paprika (Capsicum annuum), alters plasma high-density lipoprotein-cholesterol levels and hepatic gene expression in rats.

The effects of dietary capsanthin, the main carotenoid in paprika (Capsicum annuum), on lipid metabolism were examined. Young male Wistar rats were fed diets containing paprika powder, paprika organic solvent extract, residue of paprika extract, and purified capsanthin. Administration of purified capsanthin for 2 weeks resulted in a significant increase in plasma HDL-cholesterol (P < 0.05) without detectable differences in plasma total cholesterol and TAG concentrations. A statistically significant correlation (r 0.567; P < 0.001) was found between dietary capsanthin concentrations and plasma HDL-cholesterol concentrations. Animals receiving diets containing two different capsanthin concentrations exhibited dose-dependent increases in plasma HDL-cholesterol (r 0.597; P < 0.005). While capsanthin was absent in the liver of animals fed the basal diet, it increased markedly in capsanthin-fed animals (P < 0.001). Quantitative analyses of hepatic mRNA levels revealed that capsanthin administration resulted in up-regulation of mRNA for apoA5 and lecithin cholesterol acyltransferase (LCAT), without significant differences in other mRNA levels related to HDL-cholesterol metabolism. These results suggest that capsanthin had an HDL-cholesterol-raising effect on plasma, and the potential to increase cholesterol efflux to HDL particles by increasing apoA5 levels and/or enhancement of LCAT activity.

Magnitude of HDL cholesterol variation after high-dose atorvastatin is genetically determined at the LDL receptor locus in patients with homozygous familial hypercholesterolemia.

OBJECTIVE: The combination of LDL apheresis with high doses of a potent hepatic hydroxymethylglutaryl coenzyme A reductase inhibitor, such as atorvastatin, has been the best therapy available for the prevention of cardiovascular disease in patients with homozygous familial hypercholesterolemia (HFH). However, some concerns have been made about the effect of atorvastatin on HDL cholesterol levels in these patients. METHODS AND RESULTS: HDL cholesterol levels were determined bimonthly over the course of 2 years of treatment with high-dose atorvastatin in genotypically defined HFH patients either receptor-defective (n=6) or receptor-negative (n=6) under long-term treatment with LDL apheresis. We additionally stratified the atorvastatin effect on HDL cholesterol according to the genotype as an indicator of residual in vivo LDL receptor activity. Our findings indicate that (1) an early and transitory reduction of plasma HDL cholesterol levels occurs during the first 4 weeks of atorvastatin treatment; (2) the degree of the transient HDL reduction is higher in receptor-negative than in receptor-defective patients (-21+/-11 versus -10+/-4%; P=0.01); and (3) after long-term treatment, HDL cholesterol concentration remains higher in receptor-defective than receptor-negative patients (P=0.026). CONCLUSIONS: The present study reveals that HDL cholesterol reduction after high-dose atorvastatin is an early and transient event in HFH patients which magnitude depends on the presence of a residual LDL-R activity.

Genetic factors associated with response of LDL subfractions to change in the nature of dietary fat.

A preponderance of dense low density lipoprotein (LDL) particles is associated with an increased risk of coronary heart disease. It has been shown that dense LDL levels can be modified by diet. We investigated the contribution of polymorphisms in the genes for apolipoprotein (apo) B, apo AIV, lipoprotein lipase (LPL) and cholesterol ester transfer protein (CETP) to variation in the changes in plasma concentrations of dense LDL between a high saturated and a high polyunsaturated fatty acid diet. A total of 46 freeliving individuals (19 men and 27 women) completed a crossover trial with two dietary interventions of 4 weeks each, a high saturated fat diet (providing 21% energy from saturated fat and 3% energy from polyunsaturated fat) and a high polyunsaturated fat diet (providing 11% energy as saturated fat and 10% energy as polyunsaturated fat). Overall, the change in dense LDL between the saturated and polyunsaturated fat period was 0.17+/-0.33 mmol/L and this change was similar in men and women. Of the polymorphisms studied only variation in the apo AIV gene causing the substitution of histidine for glutamine at position 360 (Q360H) was associated with significant differences in the change in dense LDL concentration. Apo AIV Q/H individuals (n=6) showed a three-fold greater change in dense LDL cholesterol unadjusted for Lp(a) levels than Q/Q individuals (0.46+/-0.27 versus 0.12+/-0.31 mmol/L, p=0.02). The greater decrease in dense LDL cholesterol with an increase in polyunsaturated fat seen in those with the apo AIV H360 variant, who represent roughly 10% of the general population, suggests that they may benefit most from a PUFA rich lipid lowering diet.

Hypobetalipoproteinemia associated with apo B-48.4, a truncated protein only 14 amino acids longer than apo B-48.

Familial hypobetalipoproteinemia is an autosomal codominant trait that can be caused by mutations in the apo B gene. Here we report a novel apo B gene mutation causing hypobetalipoproteinemia, that is associated with the synthesis of a truncated apo B protein in a young healthy male subject and his mother. The mutation is an A deletion at position 6627 of the apo B cDNA leading to a truncated protein of 2166 amino acids (apo B-48.4). This truncated apo B was detected mainly in VLDL, LDL and in trace amounts in HDL, but not in the lipoprotein deficient plasma fraction. Affected family members present with elevated levels of HDL-cholesterol, mainly due to an increase in HDL2 particles. Postprandial triglycerides and retinyl esters in the d < 1.006 g/ml lipoprotein in the proband showed a normal response to an oral fat load compared to a group of eight matched healthy controls. In summary this novel mutation is associated with hypobetalipoproteinemia with a normal fat absorption as expected for a protein with a length similar to that of apo B-48.