Endothelial SIRT6 deficiency promotes arterial thrombosis in mice.

OBJECTIVE: Arterial thrombosis may be initiated by endothelial inflammation or denudation, activation of blood-borne elements or the coagulation system. Tissue factor (TF), a central trigger of the coagulation cascade, is regulated by the pro-inflammatory NF-κB-dependent pathways. Sirtuin 6 (SIRT6) is a nuclear member of the sirtuin family of NAD+-dependent deacetylases and is known to inhibit NF-κB signaling. Its constitutive deletion in mice shows early lethality with hypoglycemia and accelerated aging. Of note, the role of SIRT6 in arterial thrombosis remains unknown. Thus, we hypothesized that endothelial SIRT6 protects from arterial thrombosis by modulating inhibition of NF-κB-associated pathways. APPROACH AND RESULTS: Using a laser-induced carotid thrombosis model, in vivo arterial occlusion occurred 45% faster in 12-week-old male endothelial-specific Sirt6-/- mice as compared to Sirt6fl/fl controls (n ≥ 9 per group; p = 0.0012). Levels of procoagulant TF were increased in animals lacking endothelial SIRT6 as compared to control littermates. Similarly, in cultured human aortic endothelial cells, SIRT6 knockdown increased TF mRNA, protein and activity. Moreover, SIRT6 knockdown increased mRNA levels of NF-κB-associated genes tumor necrosis factor alpha (TNF-α), poly [ADP-ribose] polymerase 1 (PARP-1), vascular cell adhesion molecule 1 (VCAM-1), and cyclooxygenase-2 (COX-2); at the protein level, COX-2, VCAM-1, TNF-α, and cleaved PARP-1 remained increased after Sirt6 knockdown. CONCLUSIONS: Endothelium-specific Sirt6 deletion promotes arterial thrombosis in mice. In cultured human aortic endothelial cells, SIRT6 silencing enhances TF expression and activates pro-inflammatory pathways including TNF-α, cleaved PARP-1, VCAM-1 and COX-2. Hence, endogenous endothelial SIRT6 exerts a protective role in experimental arterial thrombosis.

Sirt6 deletion in bone marrow-derived cells increases atherosclerosis - Central role of macrophage scavenger receptor 1.

AIMS: Sirtuin 6 (Sirt6) is a NAD+-dependent deacetylase that plays a key role in DNA repair, inflammation and lipid regulation. Sirt6-null mice show severe metabolic defects and accelerated aging. Macrophage-foam cell formation via scavenger receptors is a key step in atherogenesis. We determined the effects of bone marrow-restricted Sirt6 deletion on foam cell formation and atherogenesis using a mouse model. METHODS AND RESULTS: Sirt6 deletion in bone marrow-derived cells increased aortic plaques, lipid content and macrophage numbers in recipient Apoe-/- mice fed a high-cholesterol diet for 12 weeks (n = 12-14, p < .001). In RAW macrophages, Sirt6 overexpression reduced oxidized low-density lipoprotein (oxLDL) uptake, Sirt6 knockdown enhanced it and increased mRNA and protein levels of macrophage scavenger receptor 1 (Msr1), whereas levels of other oxLDL uptake and efflux transporters remained unchanged. Similarly, in human primary macrophages, Sirt6 knockdown increased MSR1 protein levels and oxLDL uptake. Double knockdown of Sirt6 and Msr1 abolished the increase in oxLDL uptake observed upon Sirt6 single knockdown. FACS analyses of macrophages from aortic plaques of Sirt6-deficient bone marrow-transplanted mice showed increased MSR1 protein expression. Double knockdown of Sirt6 and the transcription factor c-Myc in RAW cells abolished the increase in Msr1 mRNA and protein levels; c-Myc overexpression increased Msr1 mRNA and protein levels. CONCLUSIONS: Loss of Sirt6 in bone marrow-derived cells is proatherogenic; hereby macrophages play an important role given a c-Myc-dependent increase in MSR1 protein expression and an enhanced oxLDL uptake in human and murine macrophages. These findings assign endogenous SIRT6 in macrophages an important atheroprotective role.

Mild endothelial dysfunction in Sirt3 knockout mice fed a high-cholesterol diet: protective role of a novel C/EBP-ß-dependent feedback regulation of SOD2.

Sirtuin 3 (Sirt3) is an NAD(+)-dependent mitochondrial deacetylase associated with superoxide dismutase 2 (SOD2)-mediated protection from oxidative stress. We have reported accelerated weight gain and impaired metabolic flexibility in atherosclerotic Sirt3 (-/-) mice. Oxidative stress is a hallmark of endothelial dysfunction. Yet, the role of Sirt3 in this context remains unknown. Thus, we aimed to unravel the effects of endogenous Sirt3 on endothelial function and oxidative stress. Knockdown of Sirt3 in human aortic endothelial cells (HAEC) increased intracellular mitochondrial superoxide accumulation, as assessed by electron spin resonance spectroscopy and fluorescence imaging. Endothelium-dependent relaxation of aortic rings from Sirt3 (-/-) mice exposed to a normal diet did not differ from wild-type controls. However, following 12 weeks of high-cholesterol diet and increasing oxidative stress, endothelial function of Sirt3 (-/-) mice was mildly impaired compared with wild-type controls. Relaxation was restored upon enhanced superoxide scavenging using pegylated superoxide dismutase. Knockdown of Sirt3 in cultured HAEC diminished SOD2 specific activity, which was compensated for by a CCAAT/enhancer binding protein beta (C/EBP-ß)-dependent transcriptional induction of SOD2. Abrogation of this feedback regulation by simultaneous knockdown of C/EBP-ß and Sirt3 exacerbated mitochondrial superoxide accumulation and culminated into endothelial cell death upon prolonged culture. Taken together, Sirt3 deficiency induces a mild, superoxide-dependent endothelial dysfunction in mice fed a high-cholesterol diet. In cultured endothelial cells, a novel C/EBP-ß-dependent rescue mechanism maintains net SOD2 activity upon transient knockdown of Sirt3.

The Sirt1 activator SRT3025 provides atheroprotection in Apoe-/- mice by reducing hepatic Pcsk9 secretion and enhancing Ldlr expression.

AIMS: The deacetylase sirtuin 1 (Sirt1) exerts beneficial effects on lipid metabolism, but its roles in plasma LDL-cholesterol regulation and atherosclerosis are controversial. Thus, we applied the pharmacological Sirt1 activator SRT3025 in a mouse model of atherosclerosis and in hepatocyte culture. METHODS AND RESULTS: Apolipoprotein E-deficient (Apoe(-/-)) mice were fed a high-cholesterol diet (1.25% w/w) supplemented with SRT3025 (3.18 g kg(-1) diet) for 12 weeks. In vitro, the drug activated wild-type Sirt1 protein, but not the activation-resistant Sirt1 mutant; in vivo, it increased deacetylation of hepatic p65 and skeletal muscle Foxo1. SRT3025 treatment decreased plasma levels of LDL-cholesterol and total cholesterol and reduced atherosclerosis. Drug treatment did not change mRNA expression of hepatic LDL receptor (Ldlr) and proprotein convertase subtilisin/kexin type 9 (Pcsk9), but increased their protein expression indicating post-translational effects. Consistent with hepatocyte Ldlr and Pcsk9 accumulation, we found reduced plasma levels of Pcsk9 after pharmacological Sirt1 activation. In vitro administration of SRT3025 to cultured AML12 hepatocytes attenuated Pcsk9 secretion and its binding to Ldlr, thereby reducing Pcsk9-mediated Ldlr degradation and increasing Ldlr expression and LDL uptake. Co-administration of exogenous Pcsk9 with SRT3025 blunted these effects. Sirt1 activation with SRT3025 in Ldlr(-/-) mice reduced neither plasma Pcsk9, nor LDL-cholesterol levels, nor atherosclerosis. CONCLUSION: We identify reduction in Pcsk9 secretion as a novel effect of Sirt1 activity and uncover Ldlr as a prerequisite for Sirt1-mediated atheroprotection in mice. Pharmacological activation of Sirt1 appears promising to be tested in patients for its effects on plasma Pcsk9, LDL-cholesterol, and atherosclerosis.

Deletion of Sirt3 does not affect atherosclerosis but accelerates weight gain and impairs rapid metabolic adaptation in LDL receptor knockout mice: implications for cardiovascular risk factor development.

Sirt3 is a mitochondrial NAD(+)-dependent deacetylase that governs mitochondrial metabolism and reactive oxygen species homeostasis. Sirt3 deficiency has been reported to accelerate the development of the metabolic syndrome. However, the role of Sirt3 in atherosclerosis remains enigmatic. We aimed to investigate whether Sirt3 deficiency affects atherosclerosis, plaque vulnerability, and metabolic homeostasis. Low-density lipoprotein receptor knockout (LDLR(-/-)) and LDLR/Sirt3 double-knockout (Sirt3(-/-)LDLR(-/-)) mice were fed a high-cholesterol diet (1.25 % w/w) for 12 weeks. Atherosclerosis was assessed en face in thoraco-abdominal aortae and in cross sections of aortic roots. Sirt3 deletion led to hepatic mitochondrial protein hyperacetylation. Unexpectedly, though plasma malondialdehyde levels were elevated in Sirt3-deficient mice, Sirt3 deletion affected neither plaque burden nor features of plaque vulnerability (i.e., fibrous cap thickness and necrotic core diameter). Likewise, plaque macrophage and T cell infiltration as well as endothelial activation remained unaltered. Electron microscopy of aortic walls revealed no difference in mitochondrial microarchitecture between both groups. Interestingly, loss of Sirt3 was associated with accelerated weight gain and an impaired capacity to cope with rapid changes in nutrient supply as assessed by indirect calorimetry. Serum lipid levels and glucose tolerance were unaffected by Sirt3 deletion in LDLR(-/-) mice. Sirt3 deficiency does not affect atherosclerosis in LDLR(-/-) mice. However, Sirt3 controls systemic levels of oxidative stress, limits expedited weight gain, and allows rapid metabolic adaptation. Thus, Sirt3 may contribute to postponing cardiovascular risk factor development.

Endothelial mineralocorticoid receptor activation mediates endothelial dysfunction in diet-induced obesity.

AIMS: Aldosterone plays a crucial role in cardiovascular disease. 'Systemic' inhibition of its mineralocorticoid receptor (MR) decreases atherosclerosis by reducing inflammation and oxidative stress. Obesity, an important cardiovascular risk factor, is an inflammatory disease associated with increased plasma aldosterone levels. We have investigated the role of the 'endothelial' MR in obesity-induced endothelial dysfunction, the earliest stage in atherogenesis. METHODS AND RESULTS: C57BL/6 mice were exposed to a normal chow diet (ND) or a high-fat diet (HFD) alone or in combination with the MR antagonist eplerenone (200 mg/kg/day) for 14 weeks. Diet-induced obesity impaired endothelium-dependent relaxation in response to acetylcholine, whereas eplerenone treatment of obese mice prevented this. Expression analyses in aortic endothelial cells isolated from these mice revealed that eplerenone attenuated expression of pro-oxidative NADPH oxidase (subunits p22phox, p40phox) and increased expression of antioxidative genes (glutathione peroxidase-1, superoxide dismutase-1 and -3) in obesity. Eplerenone did not affect obesity-induced upregulation of cyclooxygenase (COX)-1 or prostacyclin synthase. Endothelial-specific MR deletion prevented endothelial dysfunction in obese (exhibiting high 'endogenous' aldosterone) and in 'exogenous' aldosterone-infused lean mice. Pre-incubation of aortic rings from aldosterone-treated animals with the COX-inhibitor indomethacin restored endothelial function. Exogenous aldosterone administration induced endothelial expression of p22phox in the presence, but not in the absence of the endothelial MR. CONCLUSION: Obesity-induced endothelial dysfunction depends on the 'endothelial' MR and is mediated by an imbalance of oxidative stress-modulating mechanisms. Therefore, MR antagonists may represent an attractive therapeutic strategy in the increasing population of obese patients to decrease vascular dysfunction and subsequent atherosclerotic complications.

Familial combined hyperlipidemia is associated with alterations in the cholesterol synthesis pathway.

OBJECTIVE: Familial combined hyperlipidemia (FCH) is a common familial lipid disorder characterized by increases in plasma total cholesterol, triglyceride, and apolipoprotein B-100 levels. In light of prior metabolic and genetic research, our purpose was to ascertain whether FCH cases had significant abnormalities of plasma markers of cholesterol synthesis and absorption as compared to unaffected kindred members. METHODS AND RESULTS: Plasma levels of squalene, desmosterol, and lathosterol (cholesterol synthesis markers) and campesterol, sitosterol, and cholestanol (cholesterol absorption markers) were measured by gas-liquid chromatography in 103 FCH patients and 240 normolipidemic relatives (NLR). Squalene, desmosterol, and lathosterol levels were 6% (0.078), 31%, (P<0.001) and 51% (P<0.001) higher in FCH as compared to NLR, and these differences were especially pronounced in women. An interaction with obesity was also noted for a subset of these markers. We did not observe any apparent differences for the cholesterol absorption markers among FCH patients and NLR. CONCLUSIONS: Our data indicate that both men and women with FCH have alterations in the cholesterol synthesis pathway, resulting in 51% higher levels of lathosterol (and additionally desmosterol in women). Plasma levels of the cholesterol precursor sterol squalene were only slightly increased (6%), suggesting enhanced conversion of squalene to lathosterol in this disorder.

Serum hepcidin levels are innately low in HFE-related haemochromatosis but differ between C282Y-homozygotes with elevated and normal ferritin levels.

HFE C282Y-homozygosity has been associated with low hepcidin expression, leading to increased ferritin levels. However, serum hepcidin protein levels have not been documented in humans. In the current study, we compared serum hepcidin levels of newly diagnosed HFE C282Y-homozygotes with (N = 15) and without (N = 7) elevated serum ferritin levels to levels of 40 controls (20 heterozygotes and 20 wild types). In addition, hepcidin levels of four C282Y homozygotes were investigated during the course of all phlebotomy treatment phases. Serum hepcidin levels were lower in HFE C282Y-homozygotes (median; 25th-75th percentile: 1.88; 0.78-2.77 nmol/l) compared to controls (2.74; 1.45-5.39). Hepcidin/ferritin ratios were also lower in homozygotes. Homozygotes with an elevated serum ferritin had a higher serum hepcidin but a lower hepcidin/ferritin ratio than those with normal ferritin (2.28; 1.62-3.23 nmol/l hepcidin vs. 0.80; 0.60-1.29 and 3.63; 2.72-7.59 pmol hepcidin/microg ferritin vs. 13.2; 5.15-14.2). Serum hepcidin decreased during the depletion phase of phlebotomy and remained low during maintenance. This study showed that serum hepcidin is innately low in HFE-related haemochromatosis. Elevated ferritin levels were associated with increased hepcidin levels while erythropoiesis lead to lower hepcidin levels. During depletion, therefore, hepcidin levels are decreased, which may exacerbate intestinal iron absorption.

Adiponectin multimer distribution in patients with familial combined hyperlipidemia.

Adiponectin is secreted from adipocytes in different multimers, of which the high molecular weight (HMW) form is supposed to mediate favorable metabolic and anti-atherogenic effects. We determined adiponectin multimers in 29 female and 22 male patients with familial combined hyperlipidemia (FCH) and 51 age-, gender-, and BMI-matched controls in relation to cardiovascular disease (CVD). We observed a clear sexual dimorphism of total adiponectin and its multimers. Female, but not male, FCH patients had significant lower total adiponectin and both HMW and low molecular weight (LMW) adiponectin than controls. The adiponectin sensitivity index (ASI), reflected by HMW/total adiponectin, and the LMW/HMW adiponectin ratio did not differ significantly between FCH females and control females. However, FCH females with CVD exhibited significantly lower ASI (34.2+/-10.1% vs 46.0+/-7.1%) and higher LMW/HMW ratio (1.5+/-0.8 vs 0.7+/-0.3) compared to FCH females without CVD, reflecting a more atherogenic adiponectin multimer distribution.

Regulation of hepcidin: insights from biochemical analyses on human serum samples.

Knowledge of hepcidin regulation is foremost gained by in vitro studies. We aimed to translate this knowledge into the human in vivo situation. Therefore, we measured serum markers as transferrin saturation (TS), soluble transferrin receptor (sTfR), and C-reactive protein (CRP) in parallel with hepcidin and prohepcidin in patients with iron metabolism disorders and controls. To assess sTfR as erythropoietic activity-associated factor in hepcidin regulation, we studied its influence on hepcidin expression in HepG2 cells. Results showed that sTfR highly associates with erythropoietic activity that strongly interfered with the iron store regulation of hepcidin. HepG2 expression results display an inverse association between hepcidin and sTfR. Inflammation was strongly related to increased hepcidin levels regardless of the iron store and erythropoietic activity status. In contrast, prohepcidin failed to correlate to any other parameter. In conclusion, these studies verify that previous conclusions based on in vitro studies on hepcidin regulation are also likely to apply to human patients. This is underscored by a simple algorithm, based on parameters reflecting the main regulating pathways, that accurately predict the actual measured hepcidin levels. Future studies are needed to validate the combined utility of this predictive algorithm together with actual measured hepcidin levels in clinical diagnosis.

Loss of Sirt3 accelerates arterial thrombosis by increasing formation of neutrophil extracellular traps and plasma tissue factor activity.

Aims: Sirtuin 3 (Sirt3) is a mitochondrial, nicotinamide adenine dinucleotide (NAD+)-dependent deacetylase that reduces oxidative stress by activation of superoxide dismutase 2 (SOD2). Oxidative stress enhances arterial thrombosis. This study investigated the effects of genetic Sirt3 deletion on arterial thrombosis in mice in an inflammatory setting and assessed the clinical relevance of these findings in patients with ST-elevation myocardial infarction (STEMI). Methods and results: Using a laser-induced carotid thrombosis model with lipopolysaccharide (LPS) challenge, in vivo time to thrombotic occlusion in Sirt3-/- mice (n = 6) was reduced by half compared to Sirt3+/+ wild-type (n = 8, P < 0.01) controls. Ex vivo analyses of whole blood using rotational thromboelastometry revealed accelerated clot formation and increased clot stability in Sirt3-/- compared to wild-type blood. rotational thromboelastometry of cell-depleted plasma showed accelerated clotting initiation in Sirt3-/- mice, whereas overall clot formation and firmness remained unaffected. Ex vivo LPS-induced neutrophil extracellular trap formation was increased in Sirt3-/- bone marrow-derived neutrophils. Plasma tissue factor (TF) levels and activity were elevated in Sirt3-/- mice, whereas plasma levels of other coagulation factors and TF expression in arterial walls remained unchanged. SOD2 expression in bone marrow -derived Sirt3-/- neutrophils was reduced. In STEMI patients, transcriptional levels of Sirt3 and its target SOD2 were lower in CD14+ leukocytes compared with healthy donors (n = 10 each, P < 0.01). Conclusions: Sirt3 loss-of-function enhances experimental thrombosis in vivo via an increase of neutrophil extracellular traps and elevation of TF suggesting thrombo-protective effects of endogenous Sirt3. Acute coronary thrombosis in STEMI patients is associated with lower expression levels of SIRT3 and SOD2 in CD14+ leukocytes. Therefore, enhancing SIRT3 activity by pan-sirtuin activating NAD+-boosters may provide a novel therapeutic target to prevent or treat thrombotic arterial occlusion in myocardial infarction or stroke.

Pulse wave velocity in familial combined hyperlipidemia.

BACKGROUND: In the present cross-sectional study we investigated whether familial combined hyperlipidemia (FCH) is associated with an increased arterial wall stiffness, and whether measures of arterial wall stiffness in FCH family members could contribute to cardiovascular risk stratification. METHODS: Ninety-eight subjects with FCH and 230 unaffected relatives filled out a questionnaire about their smoking habits, medical history, and medication use. Fasting venous blood was drawn after discontinuation of any lipid-lowering medication. Pulse wave velocity (PWV) and augmentation index (AIx) were determined by applanation tonometry as surrogate markers of arterial stiffness. RESULTS: Patients with FCH had a significantly increased PWV compared to their unaffected relatives (9.07 +/- 2.75 v 8.28 +/- 2.62 m/sec, P = .005), whereas AIx was not increased (21.6 +/- 12.7 v 15.6 +/- 14.1, P = .96). Age- and gender-adjusted PWV was an equally good predictor of the presence of cardiovascular disease (CVD) in FCH family members as the most predictive combination of age- and gender-adjusted clinical and biochemical risk factors, including total cholesterol, HDL-cholesterol, and systolic blood pressure (area under the receiver operating curve (ROC) [AUC] 0.83 [0.76-0.90] v AUC 0.84 [0.78-0.91], P = .83). Addition of PWV to the multivariable prognostic model, including these age- and gender-adjusted traditional risk factors, did not increase the predictive ability for CVD (AUC 0.84 [0.79-0.89]). CONCLUSIONS: Patients with FCH are characterized by an increased arterial stiffness. The PWV predicts the presence of CVD equally well as any combination of clinical and traditional biochemical risk factors, but PWV has no additional value in addition to traditional risk factor screening in FCH families.

High-throughput genotyping with infrared fluorescence allele specific hybridization (iFLASH): a simple, reliable and low-cost alternative.

OBJECTIVES: To develop and validate a novel genotyping approach, named infrared Fluorescence Allele Specific Hybridization (iFLASH), which combines the principles of allele specific oligonucleotide (ASO) hybridization with the advanced possibilities of infrared imaging. DESIGN AND METHODS: As an example, we genotyped the 55L > M and the 192Q > R common genetic variants of the paraoxonase-1 gene in 92 DNA samples using the iFLASH technique, and validated the outcomes with the restriction fragment length polymorphism (RFLP) and TAQman genotyping assays. RESULTS: There was a 100 percent agreement in genotype outcome among the three methods. CONCLUSIONS: Although we found complete unity in genotype outcome, the iFLASH assay has essential advantages over the RFLP and TAQman genotyping assays. First, the iFLASH technique is capable of handling up to 1536 samples per assay, which makes it a suitable technique for high-throughput genotyping. Secondly, because the costs per assay are lower, high-throughput genotyping with iFLASH is affordable.

Changes of coronary plaque composition correlate with C-reactive protein levels in patients with ST-elevation myocardial infarction following high-intensity statin therapy.

OBJECTIVES: Levels of inflammatory biomarkers associate with changes of coronary atheroma burden in statin-treated patients with stable coronary artery disease. This study sought to determine changes of plaque composition in vivo in relation to high-sensitivity C-reactive protein (hs-CRP) levels in patients with ST-elevation myocardial infarction (STEMI) receiving high-intensity statin therapy. METHODS: The IBIS-4 study performed serial (baseline and 13-month), 2-vessel intravascular ultrasound (IVUS) and radiofrequency-IVUS of the non-infarct-related arteries in patients with STEMI treated with high-intensity statin therapy. The present analysis included 44 patients (80 arteries) with serial measurements of hs-CRP. RESULTS: At follow-up, median low-density lipoprotein cholesterol (LDL-C) levels decreased from 126 to 77 mg/dl, HDL-C increased from 44 to 47 mg/dl, and hs-CRP decreased from 1.6 to 0.7 mg/L. Regression of percent atheroma volume (-0.99%, 95% CI -1.84 to -0.14, p = 0.024) was accompanied by reduction of percent fibro-fatty (p = 0.04) and fibrous tissue (p < 0.001), and increase in percent necrotic core (p = 0.006) and dense calcium (p < 0.001). Follow-up levels of hs-CRP, but not LDL-C, correlated with changes in percent necrotic core (p = 0.001) and inversely with percent fibrous tissue volume (p = 0.008). Similarly, baseline-to-follow-up change of hs-CRP correlated with the change in percent necrotic core volume (p = 0.02). CONCLUSIONS: In STEMI patients receiving high-intensity statin therapy, stabilization of VH-IVUS-defined necrotic core was confined to patients with lowest on-treatment levels and greatest reduction of hs-CRP. Elevated CRP levels at follow-up may identify progression of high-risk coronary plaque composition despite intensive statin therapy and overall regression of atheroma volume.

Elevated leptin levels in subjects with familial combined hyperlipidemia are associated with the increased risk for CVD.

Familial combined hyperlipidemia (FCH) is characterized by hypercholesterolemia and/or hypertriglyceridemia and is associated with premature cardiovascular disease (CVD). Other features of FCH are obesity and insulin resistance. Serum leptin levels have been associated with obesity, insulin resistance and CVD. The aim of this study was to determine whether increased leptin levels contribute to the FCH phenotype and its increased risk for CVD. The study population comprised 644 subjects, including 158 FCH patients. Leptin levels were determined, using a commercially available ELISA. For both males and females, the mean leptin level (ng/ml) was higher in FCH patients compared to normolipidemic relatives and spouses. However, after standardization for BMI and insulin resistance, these differences disappeared. The 90th percentile of the leptin level, standardized for BMI, insulin resistance and gender, was associated with an increased risk for CVD in FCH patients (odds ratio=2.9, 95% CI=1.1-8.0) and in non-FCH subjects (odds ratio=3.4, 95% CI=1.3-9.0). The overall increased risk for CVD, associated with a leptin level >90th percentile, was 3.3 (95% CI=1.7-6.4). We conclude that in patients with FCH, leptin levels are increased in proportion to their higher BMI and the presence of insulin resistance. These increased leptin levels are associated with an increased risk for CVD both in FCH patients and non-FCH subjects, independent of BMI, insulin resistance and gender.

Atorvastatin and simvastatin in patients on hemodialysis: effects on lipoproteins, C-reactive protein and in vivo oxidized LDL.

BACKGROUND: Cardiovascular disease as a result of accelerated atherogenesis is common in patients with end-stage renal disease (ESRD). Dyslipidemia may be a major contributor in this process and can be influenced by lipid-lowering drugs (statins). Moreover, statins may exhibit additional inhibitory effects on the atherogenesis, such as a modulation of the immune system as triggered by oxidatively modified LDL and a reduction of the inflammatory marker C-reactive protein (CRP). METHODS: We evaluated in a single-blind randomized trial of 28 ESRD patients on hemodialysis, the dose-depending effects of both atorvastatin and simvastatin on lipids, lipoproteins, LDL particle heterogeneity, high sensitive-CRP, and markers of in vivo LDL oxidation. RESULTS: Both statin therapies significantly lowered total plasma cholesterol and LDL-cholesterol concentrations to the same extent, whereas reduction in the concentrations of triglyceride-rich particles was less pronounced. Furthermore, statin therapy reduced LDL cholesterol in all LDL subfractions, without altering the overall LDL particle density. After both statins plasma hs-CRP concentrations were not significantly reduced; parameters of in vivo LDL oxidation (plasma ox-LDL concentration and the oxidation level of isolated LDL), were significantly decreased. Autoantibodies against ox-LDL, however, did not change during this trial period. CONCLUSIONS: These results show that atorvastatin and simvastatin exhibit comparable favourable effects on lipid profiles in ESRD. Moreover, the reduction of in vivo oxidatively modified LDL as shown in this ESRD population, may indicate that these statins exhibit favourable effects on oxidative stress in vivo.

Effects of atorvastatin and simvastatin on low-density lipoprotein subfraction profile, low-density lipoprotein oxidizability, and antibodies to oxidized low-density lipoprotein in relation to carotid intima media thickness in familial hypercholesterolemia.

BACKGROUND: Little is known about the effects of statins on the quality of circulating low-density lipoprotein (LDL) in relation to atherosclerosis progression. METHODS: In a double-blind, randomized trial of 325 patients with familial hypercholesterolemia (FH), we assessed the effects of high-dose atorvastatin (80 mg) and conventional-dose simvastatin (40 mg) on LDL subfraction profile (n = 289), LDL oxidizability (n = 121), and circulating autoantibodies to oxidized LDL (n = 220). Progression of atherosclerosis was measured by carotid intima media thickness (IMT) (n = 325). RESULTS: At baseline, the patients showed an intermediate LDL subfraction profile composed of three LDL subfractions (LDL1, LDL2, LDL3), with LDL2 as the predominant subfraction. A strong negative correlation was found between plasma triglycerides and the LDL subfraction profile (r = -.64, p = .000). Both plasma levels of triglycerides and small dense LDL3 correlated weakly with baseline IMT (r = .11, p = .04 and r = .15, p = .01, respectively; n = 289). No association was found between baseline IMT and oxidation parameters or circulating antibodies to oxidized LDL. Atorvastatin reduced triglycerides, LDL cholesterol, and all LDL subfractions to a greater extent than did simvastatin and led to regression of carotid IMT. However, LDL subfraction pattern and plasma levels of autoantibodies to oxidized LDL remained unchanged in both treatment groups, and LDL oxidizability increased minimally to a similar extent in both groups. Significant treatment differences were found for the rate of in vitro oxidation of LDL and the amount of dienes formed during in vitro oxidation of LDL, which both decreased more following atorvastatin than after simvastatin. CONCLUSION: Change of IMT after statin treatment was associated with baseline IMT (r = .41), LDL cholesterol (r = -.20), and the amount of dienes formed during in vitro oxidation of LOL (r = .28) but not with plasma levels of antibodies to oxidized LDL, in vitro LDL oxidizability, and LDL subfraction profile.

Neutrophil superoxide-anion generating capacity in chronic smoking: effect of long-term alpha-tocopherol therapy.

We investigated whether long-term alpha-tocopherol therapy in chronic smoking affects superoxide generating capacity of neutrophils ex vivo. To this purpose, we randomly assigned 128 male chronic smokers (37 +/- 21 pack years of smoking) to treatment with placebo (n = 64) or alpha-tocopherol (400 IU dL-a-tocopherol daily, n = 64). After two years of therapy, we measured phorbol 12-myristate 13-acetate-induced superoxide production of isolated neutrophils and of diluted whole blood by monitoring reduction of ferricytochrome c and luminol-enhanced peroxidase-catalyzed chemiluminescence. Plasma lipids and lipoproteins were not different between the two treatment groups. As expected, concentrations of alpha-tocopherol in plasma and in low-density lipoproteins were markedly elevated in the supplemented group compared to the placebo group (+ 120%, P < 0.0001 and + 83%, P < 0.0001, respectively). Consequently, resistance to in vitro oxidation of low-density lipoproteins (reflected by lag time of conjugated diene formation) was higher in the supplemented group than in the placebo group (+ 22%, P < 0.0001). Superoxide generating capacity of neutrophils and superoxide production in diluted whole blood did not differ between alpha-tocopherol and placebo group. It is concluded that in chronic smoking long-term supranormal alpha-tocopherol intake does not reduce neutrophil superoxide-anion generating capacity, despite large increases in the concentrations of alpha-tocopherol in plasma and in low-density lipoproteins.

Oxidative stress in patients with end-stage renal disease prior to the start of renal replacement therapy.

BACKGROUND/AIM: In patients with end-stage renal disease (ESRD), cardiovascular complications are the main cause of death. Increased oxidative stress is one of the risk factors for enhanced atherosclerosis in this population. Literature data vary partially dependent on differences in methodology. The present study compares three different methods: plasma lipid peroxides, the newly developed measurement of circulating oxidized LDL (Ox-LDL) particles and the frequently used copper-induced LDL oxidation lag time. METHODS: We assessed plasma lipid peroxides, circulating Ox-LDL and in vitro copper-induced LDL oxidation lag time in 47 non-diabetic patients with ESRD, at the start of renal replacement therapy, and compared these with 41 age- and sex-matched controls. RESULTS: In ESRD, total cholesterol (4.6 +/- 1.1 vs. 5.6 +/- 0.9 mmol/l; p < 0.001), LDL cholesterol (2.8 +/- 0.8 vs. 3.5 +/- 0.7 mmol/l; p < 0.001) and HDL cholesterol (1.0 +/- 0.3 vs. 1.4 +/- 0.4 mmol/l; p < 0.001) were lower compared to controls. Plasma lipid peroxides were higher (1.1 +/- 0.5 vs. 0.8 +/- 0.5 micromol/l; p = 0.003) in ESRD. No differences were observed in plasma Ox-LDL (63.1 +/- 62.0 vs. 55.3 +/- 48.0 mg/l). However, due to the lower plasma LDL cholesterol in ESRD, LDL oxidation level was increased in ESRD (7.1 +/- 0.1 vs. 4.2 +/- 0.3%; p = 0.03). LDL lag time was slightly longer (89 +/- 11 vs. 84 +/- 11 min; p = 0.04) in ESRD. There were no significant differences regarding the amount and rate of dienes produced. CONCLUSIONS: Elevated levels of lipid peroxides and higher LDL oxidation levels support the theory that ESRD is associated with increased oxidative stress, which may explain the accelerated atherosclerosis. The measured amount of oxidative stress is not reflected by in vitro oxidizability of LDL.