Effect of treatment with pravastatin or ezetimibe on endothelial function in patients with moderate hypercholesterolemia.

BACKGROUND/AIM: Statin treatment improves endothelial function. It is matter of debate, however, if this effect of statins is due to their action on low-density lipoprotein cholesterol (LDL-C) or to other non-lipidic (pleiotropic) effects. The aim of this study was to evaluate whether the effect of pravastatin on endothelial function is mediated by pleiotropic effects. We therefore compared the effect of pravastatin and ezetimibe, a cholesterol absorption inhibitor, at doses yielding similar reductions in LDL-C and examined the effect of the two treatments on flow-mediated dilation (FMD) in hypercholesterolemic subjects. METHODS: A total of 33 moderately hypercholesterolemic patients were randomized into three treatment groups to receive ezetimibe 10 mg/day (n = 10), pravastatin 10 mg/day (n = 13) or no treatment (control, n = 10) for 6 weeks. To assess endothelial function, we determined FMD of the brachial artery non-invasively by high-resolution ultrasound before and after treatment. RESULTS: Ezetimibe and pravastatin treatment reduced LDL-C (mean ± standard error) to a similar extent (-20.6 ± 4.1 vs. -24.1 ± 4.0 %, respectively; P = 0.4771), while no decrease was observed in the control group. FMD increased significantly after treatment with ezetimibe (from 11.4 ± 5.7 to 16.8 ± 3.6 %; P = 0.022) and with pravastatin (from 13.7 ± 4.9 to 17.5 ± 4.4 %; P = 0.0466), but not in the control group. There were no differences in the endothelial function changes between the two treatment groups. CONCLUSIONS: In this study, two treatments that lower cholesterol via different mechanisms improved endothelial function to a similar extent, suggesting that the observed effect can be explained by the reduction of cholesterol levels.

Circulating soluble receptor for advanced glycation end products is inversely associated with body mass index and waist/hip ratio in the general population.

Advanced glycation end products, AGEs, and its specific receptor, RAGE, are involved in vascular complications. A role for the soluble form of RAGE (sRAGE), which acts as a decoy for AGE, has been documented in patients with diabetes but no information is available in non-diabetic subjects. The aim of this study was to investigate the association of plasma levels of sRAGE with cardiometabolic risk factors in the general population. In addition we evaluated the relation of the common -374A/T polymorphism of RAGE with plasma levels of sRAGE. One hundred and seventy-six healthy subjects free of diabetes or coronary artery disease untreated for hypertension, dyslipidemia or cardiometabolic related diseases were randomly selected for this study from the general population. Plasma sRAGE were negatively and significantly correlated with BMI, waist/hip circumference ratio and fasting glycemia, while a positive correlation was observed with apolipoprotein A-I. These correlations were observed mainly in women who showed significantly higher sRAGE levels (1744+/-660 pg/mL vs 1414+/-649 pg/mL; P<0.05). In a stepwise regression analysis waist circumference was independently associated with sRAGE and, when waist circumference was excluded, BMI was independently associated with sRAGE. Finally in overweight subjects (BMI>25 kg/m(2)) plasma sRAGE was significantly lower compared to lean subjects (1460+/-640 pg/mL vs 1710+/-693 pg/mL; P<0.05). In healthy subjects plasma levels of sRAGE were negatively correlated with BMI and waist/hip ratio supporting a possible protective role for these proteins before any evidence of diabetic or vascular complications.

Leptin:adiponectin ratio is an independent predictor of intima media thickness of the common carotid artery.

BACKGROUND AND PURPOSE: The evaluation of the leptin:adiponectin ratio (L:A) has been suggested as an atherosclerotic index in patients with type 2 diabetes and a useful parameter to assess insulin resistance in patients with and without diabetes. METHODS: We investigated, therefore, the relationship between L:A ratio and intima media thickness (IMT), an independent predictor of cardiovascular disease, in 110 healthy males. RESULTS: L:A ratio was significantly correlated to body mass index, waist, hip, waist-to-hip ratio, systolic blood pressure, IMT, high-density lipoprotein, apolipoprotein A-I, glucose, and the homeostasis model of insulin resistance-revised. No significant correlation was observed with age, diastolic blood pressure, low-density lipoprotein, triglycerides, apolipoprotein B, ApoB/ApoA-I ratio, insulin, alanine transaminase, gamma-glutamyl-transferase, and resistin. In addition, when the relationship between IMT and adiponectin or leptin alone was analyzed, only leptin plasma levels significantly associated with IMT (r=0.301, P<0.01). In a multiple regression analysis including in the statistical model the risk factors known to affect IMT (age, systolic blood pressure, diastolic blood pressure, high-density lipoprotein cholesterol, triglycerides, total cholesterol, body mass index, glucose, and L:A ratio), we observed that only age, L:A, and glucose were independent predictors of IMT. As expected, obese subjects (body mass index >30 kg/m(2)) showed a significantly higher L:A ratio compared with nonobese subjects (1.20 versus 0.42, respectively, P<0.001); in addition, subjects with the metabolic syndrome showed a significantly higher L:A ratio level (0.79) compared with subjects without (0.52) (P<0.01). CONCLUSIONS: We show here that the L:A ratio is a powerful independent predictor of IMT in healthy subjects and correlates with several anthropometric, metabolic, and clinical parameters better than each single adipokine.

Post-prandial endothelial dysfunction in hypertriglyceridemic subjects: molecular mechanisms and gene expression studies.

OBJECTIVE: Triglyceride-rich lipoproteins (TGRLs) are a cardiovascular risk factor and induce endothelial dysfunction. In the present study, we investigated the effects of post-prandial TGRLs from type IV hyperlipidemic subjects on endothelial activation addressing the effects of the lipoproteins on intracellular pathways and gene expression. METHODS: Thirty fasted hypertriglyceridemic patients were given an oral fat load (OFL) and blood samples were collected before the OFL (T0) and 2, 4, 6 and 8h thereafter. Endothelial function, determined as flow-mediated dilatation of the brachial artery, was assessed at the same time points. TGRLs were isolated at T0 and T4 (PP-TGRL) for in vitro studies. RESULTS: Compared with TGRLs, PP-TGRLs induced to a larger extent phosphorylation of p38 MAPK, CREB and IKB-alpha in human endothelial cells and increased the DNA binding activity of CREB, NFAT and NF-kappaB. Furthermore, PP-TRGLs upregulated the expression of several pro-inflammatory genes including vascular cell adhesion molecule-1 (VCAM-1), PECAM-1, ELAM-1, intercellular adhesion molecule-1 (ICAM-1), P-selectin, MCP-1, interleukin-6 (IL-6), TLR-4, CD40, ADAMTS1 and PAI-1. CONCLUSION: These effects may relate to the severe impairment of endothelial function seen during the post-prandial phase in hypertriglyceridemic patients.

Effects of fractalkine receptor variants on common carotid artery intima-media thickness.

BACKGROUND AND PURPOSE: Fractalkine receptor (CX3CR1) plays a key role during atherogenesis. CX3CR1 has 2 common coding polymorphisms, namely V249I and T280M, that have been associated with interindividual differences in susceptibility to atherosclerosis. In the present study, we investigated the possible association between CX3CR1variants and intima-media thickness (IMT). METHODS: We genotyped 1256 samples from the Progression of Lesions in the Intima of the Carotid (PLIC) study (a prospective population-based study) for the presence of the V249 and the M280 variants of CX3CR1. RESULTS: Significantly reduced IMT was observed in subjects with the MM280 genotype (0.57+/-0.12 mm) compared with subjects with the TT (0.65+/-0.14 mm) or the TM (0.65+/-0.13 mm) genotype. No difference in IMT was observed within carrier of the II249, VI249, or VV249 genotype. Subjects with combined genotype VI249/MM280 and II249/MM280 showed a reduced IMT. CONCLUSIONS: The presence of the M280 polymorphism of the fractalkine receptor is associated with a decreased common carotid artery IMT, whereas the presence of the I249 polymorphism does not play a major role on the progression of carotid atherosclerosis.

In vitro isolation of circulating endothelial progenitor cells is related to the high density lipoprotein plasma levels.

Circulating endothelial progenitor cells (EPCs) play an important role in post natal neovascularization. High density lipoproteins (HDL) protect the vascular wall from atherosclerosis. The role exerted by HDL on EPCs physiology is unknown. In this study we investigated whether the levels of plasma HDL can modulate the number of EPCs. The number of EPCs was evaluated in 24 subjects as the number of endothelial colony-forming unit (e-CFU) growth in culture. The number of AC133 positive progenitor cells present in the gate of the CD34 bright positive lymphocytes was also evaluated. Plasma levels of HDL, triglycerides and total cholesterol/HDL cholesterol ratio correlated with the number of e-CFU (r=0.62, P=0.006; r=-0.54, P=0.019, and r=-0.61, P=0.007 respectively), but not with the number of CD34/AC133 positive progenitor cells. In vitro, the incubation of the mononuclear cellular fraction with HDL did not increase the number of e-CFU in culture, whereas LDL and VLDL reduced the number of e-CFU. Our results indicate that human HDL plasma levels directly relate to the number of circulating endothelial progenitor cells that can be isolated in vitro, as determined by the number of e-CFU.

Lipoprotein remnants and endothelial dysfunction in the postprandial phase.

The objective of this work was to study whether changes in remnant lipoprotein (RLP) plasma levels during the postprandial phase relate to alterations of the endothelial function. Fasted patients (15 moderately dyslipidemic men) were given an oral fat load (OFL), and blood samples were collected before the OFL ingestion (T0) and 2, 4, 6, and 8 h (T2, T4, T6, T8) thereafter. Endothelial function, determined as flow-mediated dilatation (FMD) of the brachial artery, was assessed at the same time points. Triglyceridemia peaked between T4 (5.48 +/- 0.64 mmol/liter) and T6 (5.34 +/- 0.89 mmol/liter) and decreased at 8 h (4.36 +/- 0.87 mmol/liter) after the OFL. FMD decreased significantly 6 h after the OFL consumption (from 16.03 +/- 1.32% to 11.53 +/- 1.42%, P < 0.01). Cholesterol in RLPs increased steadily up to 6 h and decreased at 8 h (T0 0.53 +/- 0.10, T6 0.81 +/- 0.11, T8 0.73 +/- 0.13 mmol/liter). Fasting levels of triglycerides and cholesterol-RLPs (C-RLPs) correlated significantly with FMD at baseline. The decrease in endothelial function at 6 h also significantly correlated with the area under the curve of triglycerides (R = 0.53, P = 0.04). Postprandial C-RLPs (area under the curve), however, showed the best correlation with the decrease of FMD (R = 0.63, P = 0.012). The correlation persisted in a multivariate analysis. We concluded that C-RLPs contribute significantly to the endothelial dysfunction occurring during the postprandial lipemia.

Effects of PCSK9 variants on common carotid artery intima media thickness and relation to ApoE alleles.

BACKGROUND: PCSK9 plays a key role in plasma cholesterol metabolism by modulating the expression of LDL receptors. OBJECTIVE AND METHODS: In this study we investigated the effects of two common polymorphism of the PCSK9 gene (E670G and I474V) on the intima media thickness of the common carotid artery and the possible relation with polymorphisms of apolipoprotein E in 1541 middle aged subjects selected from the general population enrolled in the PLIC study and confirmed the major findings in a second free-living population enrolled in the Ventimiglia study. RESULTS: 670G carriers showed significantly increased plasma total cholesterol, LDL-cholesterol, and Apo levels B while no significant differences were observed between carriers of the I474V SNP. IMT was significantly increased in 670G carriers compared to individuals homozygous for the E allele (0.640+/-0.102mm vs. 0.652+/-0.092mm, P<0.05). The presence of the 670G allele was also significantly associated with a greater progression of IMT compared to 670EE subjects. Plasma total cholesterol, LDL-cholesterol, apolipoprotein B, and IMT significantly increased from ApoE2;PCSK9-670EE carriers to ApoE4-PCSK9-670G carriers, while no significant differences were observed when the presence of the ApoE alleles was combined with that of the PCSK9 I474V SNP. In silico analysis on wild type and 670G variant showed several structural differences on the interactions of the loops of the "V" domain. CONCLUSIONS: The E670G polymorphism of the PCSK9 gene is associated with increased IMT progression in the general population. When the presence of 670G allele is stratified according to the ApoE gene alleles, ApoE2;PCSK9-670EE carriers show a more favorable plasma lipid profile and decreased IMT compared to ApoE4-PCSK9-670G carriers.

Small dense LDL and VLDL predict common carotid artery IMT and elicit an inflammatory response in peripheral blood mononuclear and endothelial cells.

OBJECTIVE: The presence of small dense LDL has been associated with increased cardiovascular risk and with the progression of coronary and carotid atherosclerosis in case-control and prospective studies. The aim of this study was to investigate the relation between different lipoprotein subfractions with intima-media thickness of the common carotid artery in a free-living, healthy population, and to evaluate whether in patients with comparable LDL-C, the different lipoprotein subclasses differently affected the expression of chemokines, cytokines and adhesion molecules in peripheral blood mononuclear and endothelial cells. METHODS AND RESULTS: The lipoprotein cholesterol profile and the LDL buoyancy (LDL-RF) were evaluated in a cohort of 156 healthy subjects randomly selected from the PLIC (Progressione Lesione Intimale Carotidea) study. The LDL-RF was directly and significantly correlated to weight, body mass index, waist, hip, waist/hip ratio, triglycerides, fasting glycemia and intima media thickness (IMT) of the common carotid artery and inversely related to HDL-C. After multivariate statistical analysis, IMT was independently associated with age, LDL-RF and HDL-C and among the lipoprotein subclasses, only those corresponding to triglyceride-rich lipoproteins (TGRL) and small dense LDL (sdLDL) independently predicted IMT variance. Peripheral blood mononuclear cells (PBMC) isolated from patients with the predominance of sdLDL (pattern B) had an increased mRNA expression of pro-inflammatory molecules compared to PBMC from patients with the predominance of large LDL (pattern A); in endothelial cells TGRL from pattern B subjects and much less those from pattern A induced the expression of pro-inflammatory genes while sdLDL from either pattern A or B subjects were less effective and showed comparable effects. CONCLUSION: LDL-relative flotation rate significantly correlates with several cardiometabolic parameters. Furthermore cholesterol levels lipoprotein subfractions within the TGRL and sdLDL density range are independent predictors of IMT variance and are associated with a pro-inflammatory activation of PBMC and endothelial cells.

Carotid artery intima-media thickness in nonalcoholic fatty liver disease.

PURPOSE: To evaluate, in patients with nonalcoholic fatty liver disease with no or mild alterations of liver function tests, carotid artery intima-media thickness and the presence of plaques and to define determinants of vascular damage. METHODS: A paired-sample case-control study: 125 patients with nonalcoholic fatty liver disease and 250 controls, without a prior diagnosis of diabetes, hypertension, and cardiovascular disease, matched for sex, age, and body mass index. B-mode ultrasound was used for evaluation of carotid intima-media thickness and presence of small plaques. RESULTS: A significant difference in mean values of intima-media thickness (0.89+/-0.26 and 0.64+/-0.14 mm, P = .0001) and prevalence of plaques (26 [21%] and 15 [6%], P < .001) was observed in nonalcoholic fatty liver disease patients and controls. Variables significantly associated with intima-media thickness higher than 0.64 mm (median value in controls), in both patients and controls were: age (P = .0001), systolic blood pressure (P = .004), total and low-density lipoprotein cholesterol (P < or = .02 and P = .01, respectively), fasting glucose (P = .0001), and cardiovascular risk (P = .0001) and, only in controls, metabolic syndrome (P = .0001), HOMA-insulin resistance (P = .01), and body mass index (P = .0003). At multivariate logistic regression performed in the overall series of subjects, independent risk predictors of intima-media thickness higher than 0.64 mm were presence of steatosis (odds ratio [OR] = 6.9), age (OR 6.0), and systolic blood pressure (OR 2.3). CONCLUSION: Patients with nonalcoholic fatty liver disease, even with no or mild alterations of liver tests, should be considered at high risk for cardiovascular complications.

Improvement of endothelial function in uraemic patients on peritoneal dialysis: a possible role for 5-MTHF administration.

BACKGROUND: Hyperhomocysteinaemia is an independent risk factor for the development of atherosclerosis. Furthermore, homocysteine induces endothelial dysfunction by an increased inactivation of nitric oxide. In patients with chronic renal failure, the administration of folic acid or its metabolites reduces but does not normalize plasma homocysteine concentrations. METHODS: We examined the effect of oral treatment with 15 mg/daily of 5-methyltetrahydrofolate (5-MTHF) for 12 weeks, on homocysteinaemia and endothelial function in 19 patients undergoing peritoneal dialysis and compared them, for the same period of time, to a control group of patients on peritoneal dialysis. Endothelial function was evaluated by B-mode ultrasonography on the brachial artery. Flow-mediated dilation (FMD) was recorded during reactive hyperaemia produced by the inflation of a pneumatic tourniquet. Nitroglycerine-mediated dilation (NMD) was recorded after sublingual administration of glyceryl trinitrate. Finally, oxidative stress was assessed by evaluating the conjugated dienes plasma levels. RESULTS: Plasma homocysteine concentrations fell by 30% after oral treatment with 5-MTHF. Endothelial function improved significantly after oral 5-MTHF treatment (13.8 +/- 1.2% vs 11.4 +/- 1.4%; P < 0.02) while in the control group we observed a worsening of basal values from 12.1 +/- 2.66% to 8.7 +/- 2.90% (P < 0.02). The conjugated dienes plasma levels did not change either. CONCLUSIONS: Our study demonstrated that 5-MTHF administration improves endothelial dysfunction in patients undergoing peritoneal dialysis. This effect appears to be independent of the reduction in homocysteine plasma levels.

5-methyltetrahydrofolate restores endothelial function in uraemic patients on convective haemodialysis.

BACKGROUND: Hyperhomocysteinaemia is an independent risk factor for the development of atherosclerosis. In patients with chronic renal failure, the administration of folic acid or its metabolites reduces but does not normalize plasma homocysteine concentrations. Furthermore, homocysteine induces endothelial dysfunction by an increased inactivation of nitric oxide. METHODS: We examined the effect of the active metabolite of folic acid, 5-methyltetrahydrofolate (5-MTHF), 45 mg/week i.v. for 10 weeks, combined during the last 2 weeks with vitamin B12, 500 microg s.c. twice weekly, on homocysteinaemia and endothelial function in 15 patients undergoing convective haemodialysis. Endothelial function was evaluated by B-mode ultrasonography on the brachial artery. Flow-mediated dilation (FMD) was recorded during reactive hyperaemia produced by inflation of a pneumatic tourniquet. Nitroglycerine-mediated dilation (NMD) was recorded after administration of isosorbide dinitrate. Finally, the presence of the thermolabile variant of methyltetrahydrofolate reductase (t-MTHFR) was assessed by genotype analysis. RESULTS: Plasma homocysteine concentrations fell by 47% after treatment with 5-MTHF alone and by a further 13.6% after the addition of vitamin B12. The reduction was more marked in homo- and heterozygous patients than in normal genotypes for t-MTHFR. Flow-mediated endothelial vasodilation, measured by ultrasonography of the brachial artery, improved after administration of 5-MTHF (12.52+/- 2.47% vs. 7.03+/-1.65%; P<0.05), but there were no further changes following the addition of vitamin B12. CONCLUSIONS: Our study demonstrated that 5-MTHF administration not only reduced plasma homocysteine but also improved endothelial function in uraemic patients undergoing convective haemodialysis.