Tiziana Sampietro

Plasma Cholesterol Regulates Soluble Cell Adhesion Molecule Expression in Familial Hypercholesterolemia

BACKGROUND Hypercholesterolemia is associated with endothelial dysfunction. On the basis of the hypothesis that high plasma cholesterol per se may be a sufficient stimulus to upregulate endothelial adhesiveness and that this phenomenon might be reversible, soluble endothelial leukocyte adhesion molecules (sELAMs) were studied in patients with familial hypercholesterolemia undergoing LDL apheresis. METHODS AND RESULTS Selective LDL absorption by dextran sulfate columns was used to treat plasma volumes of 6.5 to 9.2 L; after LDL apheresis, total cholesterol, LDL cholesterol, apolipoprotein B, triglycerides, and lipoprotein(a) levels were reduced by 74%, 82%, 79%, 56%, and 86%, respectively. Soluble intercellular adhesion molecule-1 (sICAM-1) and sELAM- were measured before, immediately after, and 2 and 6 days after LDL apheresis. Basal sICAM-1 and sELAM-1 values were higher than in healthy control subjects. After LDL apheresis, they decreased (P<.0001 and P<.0004, respectively); their removal by extracorporeal circulation components was excluded. Individual pretreatment and posttreatment values of sICAM-1 and sELAM-1 were positively correlated (P<.0001 and P<.001, respectively) with total cholesterol; their rebound curves showed patterns similar to the total cholesterol rebound curve but not to the triglyceride and lipoprotein(a) curves. CONCLUSIONS In the absence of changes in clinical chemical parameters, tumor necrosis factor-alpha, interleukin-6, and acute-phase reactant proteins, these results confirm in a clinical setting the upregulation of endothelial adhesiveness observed in experimental hypercholesterolemia and suggest a direct role for cholesterol in regulating this phenomenon, at least in familial hypercholesterolemia.

Adiponectin is associated with abnormal lipid profile and coronary microvascular dysfunction in patients with dilated cardiomyopathy without overt heart failure.

Reduced plasma adiponectin has been associated with abnormal lipid profile, reduced left ventricle (LV) function, and the extent of coronary atherosclerosis in coronary artery disease. The aim of this study was to assess these relationships in patients with dilated cardiomyopathy (DCM) without overt heart failure. Plasma adiponectin was measured in 55 DCM patients (age, 59 ± 12 years; male, 36; body mass index [BMI], 26.9 ± 0.49 kg/m²; LV ejection fraction, 39.8% ± 1.3%; New York Heart Association class I-II) and in 40 age- and BMI-matched healthy controls. In a subset of 25 patients, myocardial blood flow (MBF) was measured at rest and during intravenous dipyridamole (0.56 mg/kg in 4 minutes) by positron emission tomography and ¹³N-ammonia as a flow tracer. Adiponectin was 6.6 ± 0.34 μg/mL in controls and 10.9 ± 0.85 μg/mL in DCM patients (P < .001), where it was related inversely with BMI (P = .009) and directly with brain natriuretic peptide (P = .017), high-density lipoprotein (HDL) cholesterol (P = .002), and MBF dipyridamole (P = .020). Adiponectin lesser than median value in patients was associated with higher total to HDL cholesterol ratio (4.8 ± 0.24 vs 3.9 ± 0.18, P = .009) and lower MBF reserve (1.76 ± 0.16 vs 2.43 ± 0.19, P = .01). These results could suggest that down-regulation of the adiponectin levels and reduced HDL cholesterol have a key role in causing impaired coronary function and myocardial perfusion in DCM.

Cellular cholesterol efflux and cholesterol loading capacity of serum: effects of LDL-apheresis

High LDL-cholesterol (LDL-C) characterizes familial hypercholesterolemia (FH) and familial combined hyperlipidemia (FCH). LDL-apheresis, used in these patients to reduce LDL-C levels, has been shown to also affect HDL levels and composition. We studied LDL-apheresis effects on six FH and nine FCH subjects’ serum capacity to modulate cellular cholesterol efflux, an index of HDL functionality, and to load macrophages with cholesterol. Serum cholesterol efflux capacity (CEC) and macrophage cholesterol loading capacity (CLC) were measured before, immediately after, and two days after LDL-apheresis. The procedure reduced total cholesterol (TC), LDL-C, and apoB plasma levels (−69%, −80% and −74%, respectively), parameters only partially restored two days later. HDL-C and apoA-I plasma levels, reduced after LDL-apheresis (−27% and −16%, respectively), were restored to almost normal levels two days later. LDL-apheresis reduced serum aqueous diffusion (AD) CEC, SR-BI-CEC, and ABCA1-CEC. AD and SR-BI were fully restored whereas ABCA1-CEC remained low two days later. Sera immediately and two days after LDL-apheresis had a lower CLC than pre-LDL-apheresis sera. In conclusion, LDL-apheresis transiently reduces HDL-C levels and serum CEC, but it also reduces also serum capacity to deliver cholesterol to macrophages. Despite a potentially negative effect on HDL levels and composition, LDL-apheresis may counteract foam cells formation.

Insulin sensitivity in familial hypercholesterolemia

Insulin resistance is found in association with obesity, non-insulin-dependent diabetes mellitus, and essential hypertension, which are all risk factors for atherosclerotic cardiovascular disease. Furthermore, hyperinsulinemia has been reported in familial combined hyperlipoproteinemia and endogenous hypertriglyceridemia. Finally, relatively high serum triglyceride and low high-density lipoprotein (HDL) cholesterol concentrations invariably accompany hyperinsulinemia. Whether insulin sensitivity is affected by the isolated presence of high levels of serum low-density lipoprotein (LDL) cholesterol has not been clearly established. We studied 13 subjects with heterozygous familial hypercholesterolemia (FHC) and 15 normocholesterolemic subjects selected to be free of any other known cause of insulin resistance. Thus FHC patients and controls had normal body weight and fat distribution, glucose tolerance, blood pressure, and serum triglyceride and HDL cholesterol concentrations, but were completely separated on plasma LDL cholesterol concentrations (6.05 +/- 0.38 v 3.27 +/- 0.15 mmol/L, P < .0001). Fasting plasma levels of glucose, insulin, free fatty acids (FFA), and potassium and fasting rates of net carbohydrate and lipid oxidation were superimposable in the two study groups. During a 2-hour euglycemic (approximately 5 mmol/L) hyperinsulinemic (approximately 340 pmol/L) clamp, whole-body glucose disposal rates averaged 30.4 +/- 2.3 and 31.1 +/- 3.0 mumol.kg-1 x min-1 in FHC and control subjects, respectively (P = 0.88). The ability of exogenous hyperinsulinemia to stimulate carbohydrate oxidation and energy expenditure and suppress lipid oxidation and plasma FFA and potassium levels was equivalent in FHC and control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Oxidative stress, F2-isoprostanes and endothelial dysfunction in hypercholesterolemia.

See article by Wilson et al. [9] (pages 601–607) in this issue. Hypercholesterolemia is reported to be associated both with enhanced oxidative stress, related to increased lipid peroxidation [1], and with augmented susceptibility to coronary vasoconstriction [2]. The abnormal coronary vasoreactivity is mainly attributed to endothelial dysfunction, which in hypercholesterolemic man has been demonstrated by several approaches, including coronary and forearm blood flow response to acetylcholine (ACh) [3,4], and flow-mediated dilation [5]. An increased generation of oxidized LDL is a major factor responsible for the vascular damage related to high cholesterol levels, and oxidative stress leads to increased breakdown and/or reduced bioavailability of NO in a number of experimental and clinical models [6]. F2-Isoprostanes, namely 8-epi-prostaglandin F2α (8-epi-PGF2α), have been recently proposed as reliable markers of oxidative stress in vivo [7,8]. Wilson et al. [9] in their study demonstrate that 8-epi-PGF2α causes a dose-dependent vasoconstriction in vitro, in pig coronary strips obtained from normal and hypercholesterolemic animals. Coronary vasoconstriction induced by 8-epi-PGF2α is shown to be modulated by endothelial NO, being increased after both endothelial denudation and L-NMMA administration in control animals. Hypercholesterolemic vessels (HV), in turn, show an increased coronary vasoconstriction to 8-epi-PGF2α which is comparable to that observed in normal animals following endothelium denudation, specific for 8-epi-PGF2α, not being found with other vasoconstrictor prostanoids, and is attenuated by pretreatment with l-arginine or the NO donor NOR-3. These observations suggest a tonic vasoconstrictor activity dynamically opposed by NO, with the net vasomotor effect resulting from the balance of the two systems. Furthermore, 8-epi-PGF2α in hypercholesterolemic animals … * Corresponding author. Tel.: +39-50-583-288; fax: +39-50-553-461 palombo{at}po.ifc.pi.cnr.it

Genetic score based on high-risk genetic polymorphisms and early onset of ischemic heart disease in an Italian cohort of ischemic patients

Several single-nucleotide polymorphisms (SNPs) have been recognized as associated with ischemic heart disease (IHD) although the optimal set of risk genotypes has not be identified. This study aimed to examine whether identified high-risk SNPs are associated with early onset of IHD. In the GENOCOR study, 44 high-risk SNPs were genotyped in 114 patients with early onset of IHD (46.2 ± 5.1 years) and 384 patients with late onset of IHD (60.7 ± 5.9 years). The associations between individual SNPs and early onset IHD were assessed. A multilocus genetic risk score (GRS) for each associated risk genetic markers was constructed by summing the number of risk alleles. The SNPs significantly associated with IHD were: -482C>T of Apolipoprotein C III gene (ApoC3, p=0.02); 1171 5A>6A of Matrix metalloproteinase 3 stromelisine I gene (p=0.01); G98T of Selectin E gene (p=0.05); C/G of 9p21.3 locus (p=0.01). Likelihood ratio test showed a strong interaction for increasing risk of early IHD between the presence of ApoC3 and 9p21.3 locus with hypertriglyceridemia (p=0.0008, 0.0011) as well as between 9p21.3 locus and smoking (p=0.0010) after correction for multiple testing. The OR for premature IHD for GRS unit was 1.3 (95% CI 1.1-1.6, p=0.001). Patients in the top tertile of GRS were estimated to have a 3.2-fold (95% CI 1.5-6.8; p=0.001) increased risk of early IHD compared with those in the bottom tertile. The results show that currently identified high-risk SNPs confer an additive biomarker for cardiovascular events. GRS may provide important incremental information on the genetic component of IHD.

Routine laboratory tests to risk-stratify patients with chronic coronary artery disease

BACKGROUND Several biohumoral variables, taken individually, are predictors of prognosis in patients with chronic coronary artery disease (CAD). We hypothesized that taken together, laboratory tests provide prognostic information that is additive to a complete diagnostic work-up. METHODS We prospectively examined 2370 consecutive patients with chronic CAD, as shown by a >50% coronary stenosis (in 95% of patients), previous coronary revascularization (in 31% of patients), and/or previous myocardial infarction (MI, in 54% of patients). We tested the ability of laboratory and clinical variables to predict future cardiac events (cardiac death and non-fatal MI). RESULTS During follow-up (median, 46 months), 147 patients (6.2%) died from cardiac causes and 81 (3.4%) experienced a non-fatal MI. Using multivariate analysis, after adjustment for clinical variables (including left ventricular ejection fraction and angiographic extent of coronary stenoses), a high-density lipoprotein cholesterol (HDLc) concentration<35 mg/dL (p<0.0001), a neutrophil-to-lymphocyte ratio >2.4 (p=0.0014), and an fT3 serum level<2.1 pg/mL with normal thyrotropin (low-T3 syndrome) (p=0.0260) showed an independent and incremental prognostic value, and were associated with an increase in the rate of cardiac events of 86%, 57% and 41%, respectively. When these variables were added to clinical and instrumental variables, the prognostic power of the model increased significantly (global chi-square improvement: from 157.01 to 185.07, p<0.0001). CONCLUSION Low HDLc, high neutrophil-to-lymphocyte ratio and low-T3 syndrome, both individually and taken together, provide prognostic information that is independent of and incremental to the main clinical and instrumental findings.

Effect of a reduced-fat diet with or without pravastatin on glucose tolerance and insulin sensitivity in patients with primary hypercholesterolemia

Pharmacological treatment of hyperlipidemia may be associated with deterioration of glucose tolerance. We randomized 20 nonobese patients with primary familial hypercholesterolemia (serum total cholesterol 7.8 +/- 0.4 mM, triglycerides 1.4 +/- 0.2 mM) to an isocaloric, reduced fat (< 30%) low-cholesterol (200 mg/day) diet with placebo or pravastatin (40 mg/day). Oral glucose tolerance, endogenous insulin response to glucose, insulin sensitivity (determined by the euglycemic insulin clamp technique), hepatic glucose production (by the tritiated glucose technique), and substrate utilization (by indirect calorimetry) were measured at baseline and after 8 weeks of treatment. Ten normocholesterolemic healthy subjects, matched to the patients by age, sex, and body weight, served as the control group. Diet alone (with no change in body weight) was associated with a significant 15% decrease in both serum low density lipoprotein (LDL)-cholesterol and triglycerides (p < 0.001 for both), and a slight decrease in high density lipoprotein (HDL)-cholesterol concentrations, paralleled by reductions in Apo B, C2, C3, and E levels (p < 0.05 or less). The addition of pravastatin led to a significantly larger reduction in LDL-cholesterol (30%, p < 0.05) and an 8% increase (p < 0.02) in total HDL-cholesterol concentrations. Accordingly, the ratio of LDL:HDL cholesterol (which was 60% higher than in controls at baseline) remained unchanged in the placebo-diet group whereas it was restored to normal in the pravastatin-diet group. Glucose tolerance, insulin response, insulin-induced inhibition of hepatic glucose production and lipolysis, and insulin-mediated glucose uptake and oxidation were all slightly but not significantly improved after treatment, with no significant differences between pravastatin and placebo. In nonobese patients with primary hypercholesterolemia, pravastatin treatment in combination with an isocaloric, reduced-fat diet leads to a marked reduction in LDL-cholesterol and triglycerides levels and a normalization of the LDL:HDL ratio without affecting glucose tolerance or insulin sensitivity.

Depletion in LpA-I:A-II particles enhances HDL-mediated endothelial protection in familial LCAT deficiency

The aim of this study was to evaluate the vasoprotective effects of HDL isolated from carriers of LCAT deficiency, which are characterized by a selective depletion of LpA-I:A-II particles and predominance of preβ migrating HDL. HDLs were isolated from LCAT-deficient carriers and tested in vitro for their capacity to promote NO production and to inhibit vascular cell adhesion molecule-1 (VCAM-1) expression in cultured endothelial cells. HDLs from carriers were more effective than control HDLs in promoting eNOS activation with a gene-dose-dependent effect (PTrend = 0.048). As a consequence, NO production induced by HDL from carriers was significantly higher than that promoted by control HDL (1.63 ± 0.24-fold vs. 1.34 ± 0.07-fold, P = 0.031). HDLs from carriers were also more effective than control HDLs in inhibiting the expression of VCAM-1 (homozygotes, 65.0 ± 8.6%; heterozygotes, 53.1 ± 7.2%; controls, 44.4 ± 4.1%; PTrend = 0.0003). The increased efficiency of carrier HDL was likely due to the depletion in LpA-I:A-II particles. The in vitro findings might explain why carriers of LCAT deficiency showed flow-mediated vasodilation and plasma-soluble cell adhesion molecule concentrations comparable to controls, despite low HDL-cholesterol levels. These results indicate that selective depletion of apoA-II-containing HDL, as observed in carriers of LCAT deficiency, leads to an increased capacity of HDL to stimulate endothelial NO production, suggesting that changes in HDL apolipoprotein composition may be the target of therapeutic interventions designed to improve HDL functionality.

Lipoprotein Glomerulopathy: Molecular Characterization of Three Italian Patients and Literature Survey

Lipoprotein Glomerulopathy: Molecular Characterization of Three Italian Patients and Literature Survey Lipoprotein glomerulopathy (LPG) is a rare kidney disease, mainly reported in Asian subjects, linked with rare APOE gene mutations resulting in a structurally abnormal Apolipoprotein E (ApoE), the plasma accumulation of lipoprotein remnants and the formation of lipid thrombi in glomerular capillaries. This study reports the molecular characterization of three unrelated Italian patients with long standing LPG.