Plaque Calcification: Do Lipoproteins Have a Role?

Vascular calcification (VC) is strongly associated with all-cause mortality and is an independent predictor of cardiovascular events. Resulting from its complex, multifaceted nature, targeted treatments for VC have not yet been developed. Lipoproteins are well characterized in the pathogenesis of atherosclerotic plaques, leading to the development of plaque regressing therapeutics. Although their roles in plaque progression are well documented, their roles in VC, and calcification of a plaque, are not well understood. In this review, early in vitro data and clinical correlations suggest an inhibitory role for HDL (high-density lipoproteins) in VC, a stimulatory role for LDL (low-density lipoprotein) and VLDL (very low-density lipoprotein) and a potentially causal role for Lp(a) (lipoprotein [a]). Additionally, after treatment with a statin or PCSK9 (proprotein convertase subtilisin/kexin type 9) inhibitor, plaque calcification is observed to increase. With the notion that differing morphologies of plaque calcification associate with either a more stable or unstable plaque phenotype, uncovering the mechanisms of lipoprotein-artery wall interactions could produce targeted therapeutic options for VC.

Maternal exposure to 3,3'-iminodipropionitrile targets late-stage differentiation of hippocampal granule cell lineages to affect brain-derived neurotrophic factor signaling and interneuron subpopulations in rat offspring.

3,3'-Iminodipropionitrile (IDPN) causes neurofilament (NF)-filled swellings in the proximal segments of many large-caliber myelinated axons. This study investigated the effect of maternal exposure to IDPN on hippocampal neurogenesis in rat offspring using pregnant rats supplemented with 0 (controls), 67 or 200 ppm IDPN in drinking water from gestational day 6 to day 21 after delivery. On postnatal day (PND) 21, female offspring subjected to analysis had decreased parvalbumin(+), reelin(+) and phospho-TrkB(+) interneurons in the dentate hilus at 200 ppm and increased granule cell populations expressing immediate-early gene products, Arc or c-Fos, at ≥ 67 ppm. mRNA expression in the dentate gyrus examined at 200 ppm decreased with brain-derived neurotrophic factor (Bdnf) and very low density lipoprotein receptor. Immunoreactivity for phosphorylated NF heavy polypeptide decreased in the molecular layer of the dentate gyrus and the stratum radiatum of the cornu ammonis (CA) 3, portions showing axonal projections from mossy cells and pyramidal neurons, at 200 ppm on PND 21, whereas immunoreactivity for synaptophysin was unchanged in the dentate gyrus. Observed changes all disappeared on PND 77. There were no fluctuations in the numbers of apoptotic cells, proliferating cells and subpopulations of granule cell lineage in the subgranular zone on PND 21 and PND 77. Thus, maternal IDPN exposure may reversibly affect late-stage differentiation of granule cell lineages involving neuronal plasticity as evident by immediate-early gene responses to cause BDNF downregulation resulting in a reduction in parvalbumin(+) or reelin(+) interneurons and suppression of axonal plasticity in the mossy cells and CA3 pyramidal neurons.

Does a diet high or low in fat influence the oxidation potential of VLDL, LDL and HDL subfractions?

BACKGROUND AND AIMS: High-fat diets have become increasingly popular for weight-loss, but their effect on the oxidation potential of lipoprotein subfractions has not been studied. Therefore, this study compared the effects of high-fat vs. low-fat weight reduction diets on this parameter. METHODS AND RESULTS: Very-low, low- and high-density lipoprotein (VLDL, LDL & HDL) subfractions were isolated by rapid ultracentrifugation from 24-overweight/obese subjects randomised to a high- or low-fat diet. The lipoprotein subfractions were assessed for oxidation potential by measuring conjugated diene (CD) production and time at half maximum. We found a significant between-group difference in oxidation potential. Specifically, a high-fat diet led to increased CD production in VLDL(A-D) and HDL(2&3), and a prolongation of time at half maximum. Within-group differences found that CDs increased in VLDL(A&D), LDL(I-III) and HDL(2&3) in the high-fat group and fell in VLDL(A-C) and HDL(2&3) and increased in LDL(I&II), in the low-fat group. Furthermore, following both diets all lipoprotein subfractions, except LDL(II) in the low-fat group, were protected against oxidation. CONCLUSION: These results demonstrate that at first glance, a high-fat diet may be indicative of having heart-protective properties. However, this may be erroneous, as although the time for oxidation to occur was prolonged, once this occurred these lipoproteins had the potential to produce significantly more oxidised substrate. Conversely, a low-fat diet may be considered anti-atherogenic, as these subfractions were protected against oxidation and mainly contained fewer oxidised substrate. Thus, increased fat intake may, by increasing the oxidation product within lipoprotein subfractions, increase cardiovascular disease.

Effects of hypolipidemic agent nordihydroguaiaretic acid on lipid droplets and hepatitis C virus.

UNLABELLED: Hepatitis C virus (HCV) relies on host lipid metabolic pathways for its replication, assembly, secretion, and entry. HCV induces de novo lipogenesis, inhibits ß-oxidation, and lipoprotein export resulting in a lipid-enriched cellular environment critical for its proliferation. We investigated the effects of a hypolipidemic agent, nordihydroguaiaretic acid (NDGA), on host lipid/fatty acid synthesis and HCV life cycle. NDGA negated the HCV-induced alteration of host lipid homeostasis. NDGA decreased sterol regulatory element binding protein (SREBP) activation and enhanced expression of genes involved in ß-oxidation. NDGA inhibited very low-density lipoprotein (VLDL) secretion by affecting mediators of VLDL biosynthesis. Lipid droplets (LDs), the neutral lipid storage organelles, play a key role in HCV morphogenesis. HCV induces accumulation and perinuclear distribution of LDs, whereas NDGA most notably reduced the overall number and increased the average size of LDs. The antiviral effects of NDGA resulted in reduced HCV replication and secretion. CONCLUSION: NDGA-mediated alterations of host lipid metabolism, LD morphology, and VLDL transport appear to negatively influence HCV proliferation.

Decrease in hepatic very-low-density lipoprotein-triglyceride secretion after weight loss is inversely associated with changes in circulating leptin.

AIM: Although weight loss usually decreases very-low-density lipoprotein-triglyceride (VLDL-TG) secretion rate, the change in VLDL-TG kinetics is not directly related to the change in body weight. Circulating leptin also declines with weight loss and can affect hepatic lipid metabolism. The aim of this study was to determine whether circulating leptin is associated with weight loss-induced changes in VLDL-TG secretion. METHODS: Ten extremely obese subjects were studied. VLDL-TG secretion rate and the contribution of systemic (derived from lipolysis of subcutaneous adipose tissue TG) and non-systemic fatty acids (derived primarily from lipolysis of intrahepatic and intraperitoneal TG, and de novo lipogenesis) to VLDL-TG production were determined by using stable isotopically labelled tracer methods before and 1 year after gastric bypass surgery. RESULTS: Subjects lost 33 +/- 12% of body weight, and VLDL-TG secretion rate decreased by 46 +/- 23% (p = 0.001), primarily because of a decrease in the secretion of VLDL-TG from non-systemic fatty acids (p = 0.002). Changes in VLDL-TG secretion rates were not significantly related to reductions in body weight, body mass index, plasma palmitate flux, free fatty acid or insulin concentrations. The change in VLDL-TG secretion was inversely correlated with the change in plasma leptin concentration (r = -0.72, p = 0.013), because of a negative association between changes in leptin and VLDL-TG secretion from non-systemic fatty acids (r = -0.95, p < 0.001). CONCLUSIONS: Weight loss-induced changes in plasma leptin concentration are inversely associated with changes in VLDL-TG secretion rate. Additional studies are needed to determine whether the correlation between circulating leptin and VLDL-TG secretion represents a cause-and-effect relationship.

CNTO736, a novel glucagon-like peptide-1 receptor agonist, ameliorates insulin resistance and inhibits very low-density lipoprotein production in high-fat-fed mice.

CNTO736 is a glucagon-like peptide (GLP) 1 receptor agonist that incorporates a GLP-1 peptide analog linked to the Mimetibody platform. We evaluate the potential of acute and chronic CNTO736 treatment on insulin sensitivity and very low-density lipoprotein (VLDL) metabolism. For acute studies, diet-induced insulin-resistant C57BL/6 mice received a single intraperitoneal injection of CNTO736 or vehicle. Chronic effects were studied after 4 weeks of daily intraperitoneal administration. A hyperinsulinemic-euglycemic clamp monitored insulin sensitivity. A single dose of CNTO736 reduced fasting plasma glucose levels (CNTO736, 4.4 +/- 1.0; control, 6.3 +/- 2.4 mM) and endogenous glucose production (EGP) (CNTO736, 39 +/- 11; control, 53 +/- 13 micromol/min/kg) and increased insulin-mediated glucose uptake (CNTO736, 76 +/- 25; control, 54 +/- 13 micromol/min/kg). Chronic administration of CNTO736 reduced fasting glucose levels (CNTO736, 4.1 +/- 0.8; control 6.0 +/- 1.0 mM), improved insulin-dependent glucose uptake (CNTO736, 84 +/- 19; control, 61 +/- 15 micromol/min/kg), and enhanced inhibition of EGP (CNTO736, 91 +/- 18; control, 80 +/- 10% inhibition). In addition, chronic dosing with CNTO736 reduced fasting EGP (CNTO736, 39 +/- 9; control, 50 +/- 8 micromol/min/kg) and VLDL production (CNTO736, 157 +/- 23; control, 216 +/- 36 micromol/h/kg). These results indicate that CNTO736 reinforces insulin's action on glucose disposal and production in diet-induced insulin-resistant mice. In addition, CNTO736 reduces basal hepatic glucose and VLDL output in these animals. The data suggest that CNTO736 may be a useful tool in the treatment of type 2 diabetes.

Grape seed proanthocyanidins correct dyslipidemia associated with a high-fat diet in rats and repress genes controlling lipogenesis and VLDL assembling in liver.

OBJECTIVE: To determine whether proanthocyanidins can protect against dyslipidemia induced by a high-fat diet (HFD) and to address the mechanisms that underlie this hypolipidemic effect. DESIGN AND MEASUREMENTS: Female Wistar rats were fed on a HFD for 13 weeks. They were divided into two groups, one of which was treated with a grape seed proanthocyanidin extract (25 mg kg(-1) of body weight) for 10 days. Plasma and liver lipids were measured by colorimetric and gravimetric analysis. Liver, muscle and adipose tissue were used to study the expression of genes involved in the synthesis and oxidation of fatty acids and lipoprotein homeostasis by real-time RT-PCR. RESULTS: The administration of proanthocyanidins normalized plasma triglyceride and LDL-cholesterol (both parameters significantly increased with the HFD) but tended to decrease hypercholesterolemia and fatty liver. Gene expression analyses revealed that proanthocyanidins repressed both the expression of hepatic key regulators of lipogenesis and very low density lipoprotein (VLDL) assembling such as SREBP1, MTP and DGAT2, all of which were overexpressed by the HFD. CONCLUSION: These findings indicate that natural proanthocyanidins improve dyslipidemia associated with HFDs, mainly by repressing lipogenesis and VLDL assembly in the liver, and support the idea that they are powerful agents for preventing and treating lipid altered metabolic states.

Inhibition of CETP by torcetrapib attenuates the atherogenicity of postprandial TG-rich lipoproteins in type IIB hyperlipidemia.

OBJECTIVE: The purpose of this study was to evaluate the impact of torcetrapib on atherogenic TG-rich lipoprotein subfractions in the postprandial phase in Type IIB hyperlipidemia. METHODS AND RESULTS: The quantitative and qualitative features of the postprandial profile of TG-rich lipoproteins were determined at baseline, after treatment for 6 weeks with 10 mg/d atorvastatin, and subsequently with an atorvastatin/torcetrapib combination (10/60 mg/d) in Type IIB patients (n=18). After ingestion of a standardized mixed meal, TG-rich lipoprotein subfractions were evaluated over 8 hours after each experimental period. On a background of atorvastatin, torcetrapib significantly attenuated the incremental postprandial area under the curve (iAUC 0 to 8 hours) for VLDL-1 (-40%), and the AUC 0 to 8 hours for VLDL-2 (-53%), with minor effect on chylomicron iAUC (-24%); concomitantly, the CE/TG ratio in both VLDL-1 and VLDL-2 was significantly reduced (-27% to -42%). Such reduction was attributable to torcetrapib-mediated attenuation of postprandial CE transfer to Chylomicrons (-17%) and VLDL-1 (-33%). Marked reduction in postprandial VLDL-1 levels was associated with apoE enrichment. CONCLUSIONS: On a background of atorvastatin, torcetrapib attenuated the quantitative and qualitative features of the atherogenic postprandial profile of chylomicrons, VLDL-1 and VLDL-2. Such changes reflect the sum of torcetrapib-mediated effects on TG-rich lipoprotein production, intravascular remodeling, and catabolism.

Secretion of atherogenic risk factor apolipoprotein B-100 is increased by a potential mechanism of JNK/PKC-mediated insulin resistance in liver cells.

Apolipoprotein B-100 (ApoB) is the main protein of the atherogenic lipoproteins and plasma ApoB levels reflect the total numbers of atherogenic lipoproteins. Induction of insulin resistance was accompanied by a considerable rise in the production of hepatic very low density lipoprotein (VLDL) containing ApoB and triglyceride. Increased plasma levels of ApoB and triglyceride in VLDL are common characteristics of the dyslipidemia associated with insulin resistance and type 2 diabetes mellitus. Thus, we investigate whether phorbol 12-myristate-13-acetate (PMA)-induced insulin resistance affects the increase of ApoB secretion. PMA increased ApoB secretion and transcriptional level of microsomal triglyceride transfer protein (MTP). PMA treatment also resulted in increase of insulin receptor substrate 1 (IRS1) serine312 (Ser312) and serine1101 (Ser1101) phosphorylation and induction of IRS1 degradation. Additionally, PMA induced activation of c-jun N-terminal kinase (JNK) and protein kinase C (PKC) isoforms (alpha, betaI, delta, zeta, theta), and reduced AKT8 virus oncogene cellular homolog (AKT) activation in a time dependent manner. PMA-induced ApoB secretion, MTP promoter activities, and IRS1 degradation was significantly decreased by treatment of JNK and PKCs inhibitors. Orthovanadate, a potent tyrosine phosphatase inhibitor, increased tyrosine phosphorylation of IRS1 and decreased ApoB secretion of Chang liver cells although PMA was co-treated. From the results, it was concluded that PMA-induced insulin resistance, through induction of serine phosphorylation of IRS1 mediated by activated JNK and PKCs, increases ApoB secretion in Chang liver cells.

Carbohydrate restriction and dietary cholesterol distinctly affect plasma lipids and lipoprotein subfractions in adult guinea pigs.

To evaluate the effects of carbohydrate restriction (CR) and dietary cholesterol on lipoprotein metabolism, adult male guinea pigs (10 guinea pigs/diet) were fed either low (0.04 g/100 g) or high (0.25 g/100 g) amounts of dietary cholesterol, in combination with either low (10% total energy) or high (54.2% total energy) dietary carbohydrate (control groups) for a total of four groups: high carbohydrate-low cholesterol (control-L), high carbohydrate-high cholesterol (control-H), low carbohydrate-low cholesterol (CR-L) and low carbohydrate-high cholesterol (CR-H). Plasma triglyceride concentrations were lower (P<.01%), while high-density lipoprotein cholesterol concentrations were higher (P<.05) in the CR groups compared to the control groups. In contrast, high dietary cholesterol (CR-H and control-H) resulted in higher concentrations of total and low-density lipoprotein (LDL) cholesterol compared to those guinea pigs fed the low-cholesterol diets (P<.01). Dietary cholesterol significantly increased the total number of LDL particles (P<.001) and the number of small LDL (P<.001), as determined by nuclear magnetic resonance. In contrast, carbohydrate restriction (CR-L and CR-H) resulted in lower concentrations of medium very-low-density lipoprotein and small LDL particles compared to the high-carbohydrate groups. Plasma lecithin:cholesterol acyltransferase (LCAT) activity was decreased and cholesterol ester transfer protein activity was increased by dietary cholesterol, whereas carbohydrate restriction increased LCAT activity (P<.05). These findings are similar to those observed in humans, thus validating the use of adult guinea pigs to study lipid responses to carbohydrate restriction. The results also indicate that the atherogenicity of lipoproteins induced by high dietary cholesterol is attenuated by carbohydrate restriction in guinea pigs.

[Omega-3 polyunsaturated fatty acids in the prevention of atherosclerosis]. / Az omega-3 többszörösen telítetlen zsírsavak az atherosclerosis megelôzésében.

Cardioprotective action of omega-3 polyunsaturated fatty acids such as eicosapentaenoic and docosahexaenoic acid in fish and alpha-linolenic acid in plants was demonstrated in primary and secondary clinical trials. Fish oil therapy causes a marked decrease in serum triacylglycerol and very low density lipoprotein levels and increases moderately high density lipoprotein levels without any adverse effects. Omega-3 fatty acids decrease slightly, but significantly blood pressure, enhance endothelial function, they have anti-aggregator, anti-thrombotic and anti-inflammatory effects as well. These beneficial effects are in connection with modification of gene transcription levels of some key molecules such as nuclear factor-kappaB and sterol element binding receptor protein-1c, which regulate for example expression of adhesion molecules or several receptors involved in triglyceride synthesis (hepatocyte X receptor, hepatocyte nuclear factor 4alpha, farnesol X receptor, and peroxisome proliferator-activated receptors). On the basis of these observations, the supplementation of the diet with omega-3 fatty acids (fish, fish oil, linseed, and linseed oil or canola oil) is advisable in primary and secondary prevention.

GLP-2 Dysregulates Hepatic Lipoprotein Metabolism, Inducing Fatty Liver and VLDL Overproduction in Male Hamsters and Mice.

Fundamental complications of insulin resistance and type 2 diabetes include the development of nonalcoholic fatty liver disease and an atherogenic fasting dyslipidemic profile, primarily due to increases in hepatic very-low-density lipoprotein (VLDL) production. Recently, central glucagon-like peptide-2 receptor (GLP2R) signaling has been implicated in regulating hepatic insulin sensitivity; however, its role in hepatic lipid and lipoprotein metabolism is unknown. We investigated the role of glucagon-like peptide-2 (GLP-2) in regulating hepatic lipid and lipoprotein metabolism in Syrian golden hamsters, C57BL/6J mice, and Glp2r-/- mice consuming either a normal chow or high-fat diet (HFD). In the chow-fed hamsters, IP GLP-2 administration significantly increased fasting dyslipidemia, hepatic VLDL production, and the expression of key genes involved in hepatic de novo lipogenesis. In HFD-fed hamsters and chow-fed mice, GLP-2 administration exacerbated or induced hepatic lipid accumulation. HFD-fed Glp2r-/- mice displayed reduced glucose tolerance, VLDL secretion, and microsomal transfer protein lipid transfer activity, as well as exacerbated fatty liver. Thus, we conclude that GLP-2 plays a lipogenic role in the liver by increasing lipogenic gene expression and inducing hepatic steatosis, fasting dyslipidemia, and VLDL overproduction. In contrast, the lack of Glp2r appears to interfere with VLDL secretion, resulting in enhanced hepatic lipid accumulation. These studies have uncovered a role for GLP-2 in maintaining hepatic lipid and lipoprotein homeostasis.

Effect of ezetimibe on low- and high-density lipoprotein subclasses in sitosterolemia.

BACKGROUND AND AIMS: Sitosterolemia displays high plasma total sterols [high plant sterols (PS) + normal to high total cholesterol (TC)] with normal to moderately elevated low-density lipoprotein (LDL) levels. High LDL, intermediate-density lipoprotein (IDL) and very low-density lipoprotein (VLDL) particles, low high-density lipoprotein (HDL), and increased non-HDL and the ratios of TC and triglycerides (TG) to HDL can increase the risk for atherosclerosis. Ezetimibe (EZE) can reduce plasma PS and TC levels in sitosterolemia, but its effect on lipoprotein subclasses has not been previously reported. METHODS: Sitosterolemia patients (n = 8) were taken off EZE for 14 weeks (OFF EZE) and placed on EZE (10 mg/d) for 14 weeks (ON EZE). Serum lipids were measured enzymatically and lipoprotein subclasses were assessed by polyacrylamide gel electrophoresis. RESULTS: EZE reduced (p < 0.05) total sterols (-12.5 ± 4.1%) and LDL-sterol (-22.7 ± 5.7%) and its sterol mass of large VLDL (-24.4 ± 4.5%), VLDL remnants (-21.1 ± 7.9%) and large IDL (-22.4 ± 7.2%) compared to OFF EZE. EZE did not affect large LDL subclasses or mean LDL particle size (273.8 ± 0.6 vs. 274.6 ± 0.3 Å). EZE increased HDL-sterol (25.5 ± 8.0%, p = 0.008) including intermediate (34 ± 14%, p = 0.02) and large (33 ± 16%, p = 0.06) HDL. EZE reduced non-HDL-sterol (-21.8± 5.0%), total sterols/HDL (-28.2 ± 5.5%) and TG/HDL (-27.4 ± 6.5%, all p < 0.01). CONCLUSIONS: EZE improves VLDL and HDL subfraction distribution, thereby reducing the atherogenic lipid profile, thus providing potential clinical benefit in sitosterolemia beyond TC and PS reduction.

Octanoate reduces very low-density lipoprotein secretion by decreasing the synthesis of apolipoprotein B in primary cultures of chicken hepatocytes.

Fatty acids of varying lengths and saturation differentially affect plasma apolipoprotein B (apoB) levels. To identify the mechanisms underlying the effect of octanoate on very low-density lipoprotein (VLDL) secretion, chicken primary hepatocytes were incubated with either fatty acid-bovine serum albumin (BSA) complexes or BSA alone. Addition of octanoate to culture medium significantly reduced VLDL-triacylglycerol (TG), VLDL-cholesterol and apoB secretion from hepatocytes compared to both control cultures with BSA only and palmitate treatments, but did not modulate intracellular TG accumulation. However, no differences in cellular microsomal triglyceride transfer protein levels were observed in the cultures with saturated fatty acid. In pulse-chase studies, octanoate treatment resulted in reduced apoB-100 synthesis, in agreement with its promotion of secretion. This characteristic effect of octanoate was confirmed by addition of a protease inhibitor, N-acetyl-leucyl-leucyl-norleucinal (ALLN), to hepatocyte cultures. Analysis showed that the level of apoB mRNA was lower in cultures supplemented with octanoate than in the control cultures, but no significant changes were observed in the levels of apolipoprotein A-I, fatty acid synthase and 3-hydroxy-3-methylglutaryl-CoA reductase mRNA as a result of octanoate treatment. Time-course studies indicate that a 50% reduction in apoB mRNA levels requires 12 h of incubation with octanoate. We conclude that octanoate reduced VLDL secretion by the specific down-regulation of apoB gene expression and impairment of subsequent synthesis of apoB, not by the modulation of intracellular apoB degradation, which is known to be a major regulatory target of VLDL secretion of other fatty acids.

Association of Lipoproteins, Insulin Resistance, and Rosuvastatin With Incident Type 2 Diabetes Mellitus : Secondary Analysis of a Randomized Clinical Trial.

IMPORTANCE: Statins decrease levels of low-density lipoprotein (LDL) and triglycerides as well as cardiovascular events but increase the risk for a diagnosis of type 2 diabetes mellitus (T2DM). The risk factors associated with incident T2DM are incompletely characterized. OBJECTIVE: To investigate the association of lipoprotein subclasses and size and a novel lipoprotein insulin resistance (LPIR) score (a composite of 6 lipoprotein measures) with incident T2DM among individuals randomized to a high-intensity statin or placebo. DESIGN, SETTING, AND PARTICIPANTS: This secondary analysis of the JUPITER trial (a placebo-controlled randomized clinical trial) was conducted at 1315 sites in 26 countries and enrolled 17 802 men 50 years or older and women 60 years or older with LDL cholesterol levels less than 130 mg/dL, high-sensitivity C-reactive protein levels of at least 2 mg/L, and triglyceride levels less than 500 mg/dL. Those with T2DM were excluded. A prespecified secondary aim was to assess the effect of rosuvastatin calcium on T2DM. Incident T2DM was monitored for a median of 2.0 years. Data were collected from February 4, 2003, to August 20, 2008, and analyzed (intention-to-treat) from December 1, 2013, to January 21, 2016. INTERVENTIONS: Rosuvastatin calcium, 20 mg/d, or placebo. MAIN OUTCOMES AND MEASURES: Size and concentration of lipids, apolipoproteins, and lipoproteins at baseline (11 918 patients with evaluable plasma samples) and 12 months after randomization (9180 patients). The LPIR score, a correlate of insulin resistance, was calculated as a weighted combination of size and concentrations of LDL, very low-density lipoprotein (VLDL), and high-density lipoprotein (HDL) particles. RESULTS: Among the 11 918 patients (4334 women [36.4%]; median [interquartile range] age, 66 [60-71] years), rosuvastatin lowered the levels of LDL particles (-39.6%; 95% CI, -49.4% to -24.6%), VLDL particles (-19.6%; 95% CI, -40.6% to 10.3%), and VLDL triglycerides (-15.2%; 95% CI, -35.9% to 11.3%) and shifted the lipoprotein subclass distribution toward smaller LDL size (-1.5%; 95% CI, -3.7% to 0.5%), larger VLDL size (2.8%; 95% CI, -5.8% to 12.7%), and lower LPIR score (-3.2%; 95% CI, -20.6% to 16.9%). In analyses adjusted for age, sex, race or ethnic origin, exercise, educational level, family history, and smoking, the hazard ratio (HR) for T2DM per SD of LPIR score in the placebo arm was 1.99 (95% CI, 1.64-2.42); in the rosuvastatin arm, 2.06 (95% CI, 1.74-2.43). After additional adjustment for systolic blood pressure, body mass index, high-sensitivity C-reactive protein, hemoglobin A1c, HDL cholesterol, LDL cholesterol, and triglycerides, the LPIR score remained associated with T2DM in the placebo arm (HR, 1.35; 95% CI, 1.03-1.76) and rosuvastatin arm (HR, 1.60; 95% CI, 1.27-2.03). Similar trends were seen at 12 months. The LPIR score improved the model likelihood ratio (χ2 = 18.23; P < .001) and categorical net reclassification index (0.039; 95% CI, 0.003-0.072). CONCLUSIONS AND RELEVANCE: In apparently healthy people, LPIR score was positively associated with incident T2DM, including during rosuvastatin therapy. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00239681.

ω-3 Fatty Acid Ethyl Esters Diminish Postprandial Lipemia in Familial Hypercholesterolemia.

CONTEXT: Impaired postprandial chylomicron metabolism induces hypertriglyceridemia and may increase the risk of atherosclerotic cardiovascular disease. Omega-3 fatty acid ethyl ester (ω-3 FAEE) supplementation decreases plasma triglycerides. However, its effect on postprandial chylomicron metabolism in familial hypercholesterolemia (FH) has not yet been investigated. OBJECTIVE: We aimed to examine the effect of ω-3 FAEE supplementation on postprandial responses in plasma triglycerides, very-low-density lipoprotein (VLDL) apolipoprotein B (apoB)-100, and apoB-48 in FH patients receiving standard cholesterol-lowering treatment. DESIGN, SETTING, AND PATIENTS: We carried out an 8-week open-label, randomized, crossover intervention trial to test the effect of oral supplementation with 4 g/d ω-3 FAEE (46% eicosapentaenoic acid and 38% docosahexaenoic acid) on postprandial triglyceride, VLDL-apoB-100, and apoB-48 responses in FH patients after ingestion of an oral fat load. OUTCOMES MEASURES: Plasma total and incremental triglyceride, VLDL-apoB-100, and apoB-48 0- to 10-hour area under the curve (AUC). RESULTS: ω-3 FAEE supplementation significantly (P < .05 in all) reduced concentrations of fasting plasma triglyceride (-20%), apoB (-8%), VLDL-apoB-100 (-26%), and apoB-48 (-36%); as well as systolic blood pressure (-6%) and diastolic blood pressure (-6%). Postprandial triglyceride and VLDL-apoB-100 total AUCs (-19% and -26%, respectively; P < .01) and incremental AUCs (-18% and -35%, respectively; P < .05), as well as postprandial apoB-48 total AUC (-30%; P < .02) were significantly reduced by ω-3 FAEE supplementation. CONCLUSION: Supplementation with ω-3 FAEEs improves postprandial lipemia in FH patients receiving standard care; this may have implications for further reducing atherosclerotic cardiovascular disease in this high-risk patient group.

Probucol normalizes cholesteryl ester transfer in type 2 diabetes.

AIMS: Accelerated cholesteryl ester transfer (CET) protein (CETP) activity is believed to promote macrovascular disease in patients with type 2 diabetes (T2D) by increasing the cholesterol burden of the apoB - containing triglyceride-rich lipoprotein (TGRLP) CE acceptors and promoting small dense LDL formation. While previous studies have shown that this same abnormality is present in patients with type 1 diabetes (T1D) and was normalized by the anti-oxidant drug probucol, its effects on CET in T2D are unknown. PATIENTS AND METHODS: The net mass transfer of CE from HDL to the apoB lipoproteins (VLDL+LDL) was studied in intact plasma from seven T2D patients before and two months after treatment with probucol (1g/day). RESULTS: Before treatment, CET was significantly greater than controls at 1 and 2h (p<.005). Recombination studies showed that this disturbance was attributable to dysfunction of VLDL and not due to altered behavior of HDL or CETP. Probucol treatment normalized CET in all subjects and significantly lowered plasma cholesterol (pre-Rx: 197±4.5 vs post-Rx: 162±27.1mg/dL; mean±S.D.; p<.025) and HDL-C (pre-Rx: 46.4±7.5 vs post-Rx: 39.1±4.0; p<.025) without changing glycemic control. CONCLUSIONS: By normalizing CET in T2D, probucol likely reduces the formation of atherogenic lipoproteins. This effect on CET is achieved through qualitative alterations in CETP's lipoprotein substrates and not through changes in CETP or HDL. Since probucol also has potent anti-oxidative and anti-inflammatory properties, it may have a new role to play in lipoprotein remodeling that reduce cardiovascular risk in T2D.

Antiretroviral treatment reduces very-low-density lipoprotein and intermediate-density lipoprotein apolipoprotein B fractional catabolic rate in human immunodeficiency virus-infected patients with mild dyslipidemia.

The relationship between antiretroviral treatment of HIV infection, body fat distribution, insulin resistance, and very-low-density lipoprotein (VLDL) and intermediate-density lipoprotein (IDL) apolipoprotein-B (apoB) kinetics was investigated in 55 HIV-infected patients taking two nucleoside analogs plus either a protease inhibitor (n = 15) or a nonnucleoside reverse transcriptase inhibitor (n = 25), 15 antiretroviral therapy-naive patients, and 12 HIV-negative controls. Compared with the controls, high-density lipoprotein cholesterol was reduced in all groups (P < 0.01). Plasma triglyceride was increased in patients taking protease inhibitors (P < 0.05). VLDL and IDL apoB fractional catabolic rate (FCR) was lower in all treatment groups (P < 0.05) compared with controls. Trunk fat, VLDL apoB absolute secretion rate, and insulin resistance were not different between groups. Peripheral fat was lower in the treated patients (P < 0.05) and correlated with duration of therapy (r = -0.55; P < 0.001). There was a positive correlation between peripheral fat and VLDL apoB FCR (P = 0.002) and IDL apoB FCR (P = 0.002) and a negative correlation with VLDL apoB pool size, VLDL cholesterol, and triglyceride (P < 0.03; P < 0.01; P < 0.002). These results suggest that mild dyslipidemia resulting from antiretroviral therapy is caused by a decrease in VLDL and IDL apoB FCR, which is associated with a loss of peripheral fat.

VLDL triglyceride kinetics in Wistar fatty rats, an animal model of NIDDM: effects of dietary fructose alone or in combination with pioglitazone.

The effects of dietary fructose alone or in combination with a new oral agent, pioglitazone, on VLDL-triglyceride (TG) turnover were studied in genetically obese Wistar fatty rats characterized by hyperinsulinemia (7,488 +/- 954 pmol/l), hyperglycemia, (22.5 +/- 1.4 mmol/l), and hypertriglyceridemia (4.39 +/- 0.54 mmol/l). They had an increased hepatic TG production (16.2 +/- 0.1 micromol/min; lean rats, 5.4 +/- 0.3 micromol/min) as well as a longer half-life of VLDL-TG from lean donors (8.8 +/- 1.4 min, lean recipients; 2.3 +/- 0.9 min). In addition, in lean recipients, the half-life of VLDL-TG from fatty donors was longer than that from lean donors (4.80 +/- 0.56 vs. 3.14 +/- 0.23 min). Although feeding fructose into fatty rats did not change plasma glucose and insulin levels, it produced a twofold increase in TG levels (8.74 +/- 1.15 mmol/l). This was associated with a 1.7-fold increase in TG production to 27.5 +/- 1.2 micromol/min, while no significant change was found in the half-life of lean VLDL-TG in fructose-fed fatty recipients (10.9 +/- 2.4 min) or in that of VLDL-TG from fructose-fed fatty donors in lean recipients (4.46 +/- 0.76 min). Daily administration of pioglitazone (3 mg/kg body weight) in fructose-fed fatty rats ameliorated glycemia and triglyceridemia to the level of lean rats (8.1 +/- 0.7 and 1.18 +/- 0.05 mmol/l, respectively) and insulinemia to a lesser extent (2,712 +/- 78 pmol/l). A fall in TG levels was associated with improvement of an impairment in the ability of fructose-fed fatty rats to remove lean VLDL-TG (half-fife: 2.6 +/- 0.6 min). Pioglitazone, however, produced no change in TG production (25.9 +/- 2.7 micromol/min), the half-life of VLDL-TG from fructose-fed fatty donors in lean recipients (4.17 +/- 0.38 min), or the activity of lipoprotein lipase and hepatic lipase in postheparin plasma. We conclude that in Wistar fatty rats 1) hypertriglyceridemia is attributed to TG overproduction and impaired TG catabolism, and the latter is due to changes in both VLDL, such that they are less able to be removed, and changes in the nature of Wistar fatty rats, such that they are less able to remove VLDL-TG; 2) fructose further increases hepatic TG production with a resultant deterioration in hypertriglyceridemia; 3) pioglitazone normalizes TG levels by altering the physiology of the Wistar fatty rats in a manner that increases their ability to remove VLDL-TG from the circulation.

Hepatic VLDL production in ob/ob mice is not stimulated by massive de novo lipogenesis but is less sensitive to the suppressive effects of insulin.

Type 2 diabetes in humans is associated with increased de novo lipogenesis (DNL), increased fatty acid (FA) fluxes, decreased FA oxidation, and hepatic steatosis. In this condition, VLDL production is increased and resistant to suppressive effects of insulin. The relationships between hepatic FA metabolism, steatosis, and VLDL production are incompletely understood. We investigated VLDL-triglyceride and -apolipoprotein (apo)-B production in relation to DNL and insulin sensitivity in female ob/ob mice. Hepatic triglyceride (5-fold) and cholesteryl ester (15-fold) contents were increased in ob/ob mice compared with lean controls. Hepatic DNL was increased approximately 10-fold in ob/ob mice, whereas hepatic cholesterol synthesis was not affected. Basal rates of hepatic VLDL-triglyceride and -apoB100 production were similar between the groups. Hyperinsulinemic clamping reduced VLDL-triglyceride and -apoB100 production rates by approximately 60% and approximately 75%, respectively, in lean mice but only by approximately 20% and approximately 20%, respectively, in ob/ob mice. No differences in hepatic expression of genes encoding apoB and microsomal triglyceride transfer protein were found. Hepatic expression and protein phosphorylation of insulin receptor and insulin receptor substrate isoforms were reduced in ob/ob mice. Thus, strongly induced hepatic DNL is not associated with increased VLDL production in ob/ob mice, possibly related to differential hepatic zonation of apoB synthesis (periportal) and lipid accumulation (perivenous) and/or relatively low rates of cholesterogenesis. Insulin is unable to effectively suppress VLDL-triglyceride production in ob/ob mice, presumably because of impaired insulin signaling.