Fulvio Bruni

Time‐dependent effect of statins on platelet function in hypercholesterolaemia

Background Reduction of platelet activity induced by statins has been described as a positive effect exerted by such molecules on vascular thrombotic events. However, the relations among cholesterol (LDL‐C) reduction, the timing of the antiplatelet effect, the involved mechanisms and the doses of each statin able to reduce platelet function are not actually well known. The aim of our study was to evaluate the impact of simvastatin (20 mg day−1), atorvastatin (10 mg day−1), fluvastatin (40 mg day−1) and pravastatin (40 mg day−1) on platelet function in hypercholesterolaemic subjects with relation to (LDL‐C), oxidized‐LDL (ox‐LDL) and antiport mechanism modifications.

Platelet hyperactivity after statin treatment discontinuation

Hydroxymethyl-glutaryl-CoA-reductase inhibitors (statins) reduce cardiovascular events by cholesterol lowering as well as by non-lipid related actions. Among them, the modulation of platelet activity could play a relevant role in vascular protection. Furthermore withdrawal of statins has been associated with increased cardiovascular event rate. The aim of our study was to evaluate platelet activity after cerivastatin discontinuation in eighteen subjects that did not accept other drugs and in sixteen subjects continuing treatment with simvastatin. Fourteen subjects at the end of the discontinuation period decided to receive other drugs (simvastatin) and they were evaluted six weeks later. We measured complete lipid profile by the chromogenic method (LDL-C was calculated); oxidized-LDL (ox-LDL; ELISA), platelet P-selectin (P-sel) expression (flow cytometry detection), platelet aggregation (% change of transmitted light), intracellular citrullin production (iCit; HPLC) as an indicator of intracellular NO synthase activity at baseline and 7, 14, 28, 60 days after statin discontinuation. P-sel expression and platelet aggregation were increased at 14 days (p < 0.001 and p < 0.05) in association with raised ox-LDL (r = 0.30, p < 0.05) and decreased iCit (r = 0.53, p < 0.01). Increased LDL-C was related to P-sel and platelet aggregation at 28 days (r = 0.30, p < 0.05). Subjects continuing statin treatment had no significant changes of P-sel at 28 (p = 0.221) and 60 days (p = 0.238). Subjects treated with simvastatin after 60 days of diet showed a significant reduction of P-sel and platelet aggregation after six weeks of treatment (p < 0.01). Our data suggest a platelet hyperactivation state in the second week after statin discontinuation which is partially related to raised LDL-C. Such a finding could participate in the increased cardiovascular event rate after statin discontinuation.

Atorvastatin reduces platelet-oxidized-LDL receptor expression in hypercholesterolaemic patients

Background  Oxidized‐LDL (ox‐LDL) are proatherogenic and platelet‐activating molecules. Atorvastatin reduces platelet activity before cholesterol‐lowering action. CD36 and lectin‐like oxidized‐LDL receptor‐1 (LOX‐1) are specific ox‐LDL receptors expressed also in platelets. This study was planned to address whether the possible rapid effect of atorvastatin on platelets could be related to modulation of ox‐LDL receptors.

Effects of carvedilol on left ventricular remodeling and systolic function in elderly patients with heart failure

Recent studies have shown that carvedilol therapy in patients with heart failure improves clinical outcome and survival, however, the effects of such treatment on left cardiac morphology and function in elderly patients with severe heart failure has not been widely studied.

Different effect of statins on platelet oxidized-LDL receptor (CD36 and LOX-1) expression in hypercholesterolemic subjects.

Hydroxymethyl-glutaryl-CoA-reductase inhibitors (statins) reduce cardiovascular mortality by decreasing cholesterol as well as by non-lipid-related actions. Oxidized low-density lipoproteins (ox-LDL) are pro-atherogenic molecules and potent platelet agonists. CD36 and lectin-like ox-LDL receptor-1 (LOX-1) are specific ox-LDL receptors also expressed in platelets. This study was planned to address whether treatment with atorvastatin 10 mg/day, pravastatin 40 mg/day or simvastatin 20 mg/day could affect platelet CD36 and LOX-1 expression. Twenty-four patients for each treatment were evaluated after 3, 6, and 9 days and at 6 weeks for complete lipid profile (chromogenic), ox-LDL (ELISA), platelet P-selectin (P-sel), CD36, LOX-1 (FACS), and intracellular citrullin recovery (iCit) (HPLC). Data show hyperactivated platelets (P-sel absolute values, percent variation in activated cells, all p < 0.001), and CD36 and LOX-1 overexpression (all p < 0.001) in patients at baseline. P-sel, CD36, and LOX-1 were significantly decreased by atorvastatin and simvastatin (all p < 0.01) and related with iCit increase (r = 0.58,p < 0.001) and platelet-associated ox-LDL (r = 0.51, p < 0.01) at 9 days. Pravastatin reduced LOX-1 and P-sel (p < 0.05) at 6 weeks in relation with decreased LDL and ox-LDL (r = 0.39, p < 0.01 and r = 0.37, p < 0.01, respectively). These data suggest that atorvastatin and simvastatin reduce platelet activity by exposure of CD36 and LOX-1 before significant LDL reduction, whereas pravastatin action is detected later and in relation with LDL and ox-LDL lowering. Rapid and consistent reduction of CD36 and LOX-1 could be considered a direct anti-atherothrombotic mechanism related to the role of ox-LDL in platelet activation, platelet-endothelium interactions, and NO synthase activity.

Effects of carvedilol therapy on restrictive diastolic filling pattern in chronic heart failure

BACKGROUND Carvedilol therapy during congestive heart failure demonstrated a good efficacy in mortality rate reduction and in improvement of left ventricular (LV) systolic performance. However, currently there is not any finding about the drugs effect on diastolic filling. The aim of this study was to evaluate the effects of beta-blocker treatment on LV diastolic function with an eco-pulsed Doppler ultrasound scanning examination at transmitral level in a group of patients who were affected by heart failure with a restrictive filling pattern. METHODS We studied 27 patients with idiopathic or ischemic dilated cardiomyopathy with LV severe systolic disfunction (ejection fraction <35%). Fourteen patients were randomized to receive carvedilol treatment (carvedilol group), and 13 patients continued to receive standard therapy with angiotensin-converting enzyme inhibitors, diuretics, and vasodilators (placebo group). All patients underwent an echo-Doppler ultrasound scanning examination at the beginning of the study and after 4 and 12 months of treatment. RESULTS In the carvedilol group, we found a progressive improvement of Doppler ultrasound scanning parameters after 4 months, with a significant increase of A wave (P <.005), deceleration time (DT; P <.02) and isovolumetric relaxation time (IVRT; P <.02). These improvements were confirmed after 1 year of follow-up, whereas patients in the placebo group did not shown any significant modifications. After 1 year, the differences in these groups were more significant for A wave (39 +/- 4 cm/sec carvedilol group vs 30 +/- 4 cm/sec placebo group; P <.0001), for E/A ratio (1.8 +/- 0.2 carvedilol group vs 2.6 +/- 0.5 placebo group; P <.0002), for DT 1(40 +/- 16 msec carvedilol group vs 112 +/- 13 msec placebo group; P <.001), and for IVRT (74 +/- 8 msec carvedilol group vs 57 +/- 7 mesc placebo group; P <.0002). These changes seem to happen before systolic and morphological modifications. CONCLUSION Our results show that carvedilol therapy is a means of modifying parameters of diastolic filling favorably in patients with heart failure. These effects seem to be independent of those of systolic function. The improvement of systolic performance occurs after 1 year of treatment. The restrictive filling pattern, related to an unfavorable prognosis, changes toward pseudonormal or altered relaxation pattern during carvedilol therapy. Further investigations with a greater sample size will be necessary to confirm our findings.

Mechanisms for antiplatelet action of statins.

Hydroxymethyl-glutaryl coenzyme A reductase inhibitors (statins) offer important benefits for the large populations of individuals at high risk for coronary heart and cerebrovascular disease. the overall clinical benefits observed with statin therapy appear to be greater than what might be expected from changes in lipid profile alone, suggesting that the beneficial effects of such drugs may extend beyond their effects on serum cholesterol. Platelet hyperactivity is a key step in atherothrombosis and experimental data suggest that statins could exert an antiplatelet effect which could be involved in their protective action. In the present review we report of the major studies in humans showing the effect of statins on platelets, especially by the more sensitive methods to explore platelet function such as cytofluorymetric detection of specific proteins. Moreover we describe the putative mechanisms involved in platelet deactivation with particular regard to the effects related to cholesterol reduction or beyond lipid-lowering. Indeed, data from several studies suggest some differences among compounds in terms of timing of action by modulation of several activating pathways which could take part either in the early, cholesterol-lowering independent, effects in the acute phase of vascular disease or during chronic treatment.

Different effect induced by treatment with several statins on monocyte tissue factor expression in hypercholesterolemic subjects

Abstract. Platelets and monocytes are involved in atherothrombosis via tissue factor expression. Moreover, they are activated in hypercholesterolemia, a classic risk factor for atherothrombosis. Cholesterol-lowering drugs (statins) reduce cardiovascular risk either by decreasing cholesterol or non-lipidic actions, such as platelet and monocyte activity. The aim of our study was to evaluate the effect of several statins on platelet and monocyte activity in hypercholesterolemic subjects. Platelet activity (P-selectin, cytofluorimetric detection), tissue factor levels (ELISA) and activity (detected in whole blood and cellular preparations by a specific clotting assay) were measured in hypercholesterolemic subjects (41 males, 23 females, aged 34–65 years, total cholesterol 6.86±0.60 mmol/l) treated with atorvastatin 10 mg, simvastatin 20 mg, fluvastatin 40 mg, or pravastatin 40 mg for 6 weeks. P-selectin and tissue factor expression in whole blood and isolated cells were increased in hypercholesterolemic subjects with respect to controls (all P<0.001). Simvastatin, atorvastatin, and fluvastatin reduced monocyte procoagulant activity in whole blood and P-selectin (P<0.01). Tissue factor antigen and activity in isolated cells were further reduced (all P<0.05) independently of cholesterol lowering. Pravastatin decreased tissue factor expression in whole blood in direct relationship to reduction of P-sel and cholesterol (P<0.05). Our data show a different impact of several statins on monocyte tissue factor expression in whole blood, suggesting a possible role of decreased platelet activity and a direct action on monocytes. In contrast, pravastatin decreased monocyte procoagulant activity with relation to cholesteroldependent modifications of platelet function.

T cell activation and enhanced apoptosis in non-ST elevation myocardial infarction

Abstract. Recent studies have shown that inflammation plays a major role in coronary plaque destabilization and in the induction of thrombosis in acute coronary syndromes. The aim of this study was to evaluate circulating lymphocyte activation and apoptosis in patients with non-ST elevation myocardial infarction (NSTEMI) in comparison with subjects with stable angina and with age-matched healthy controls. We considered T cell subpopulations, T cell surface HLA-DR and CD69 expression (evaluated by flow cytometry), lymphomonocyte spontaneous apoptosis (evaluated by ELISA), and IL2 production (evaluated by ELISA) in peripheral blood within 6 hours of onset of NSTEMI. We also investigated Fas expression on T cells (evaluated by flow cytometry) and FasL mRNA (evaluated by RT-PCR), as well as Fas functionality. In NSTEMI patients we found a significant increase of HLADR+ CD3+ and CD69+CD4+ cells. Spontaneous apoptosis was significantly increased in NSTEMI patients in comparison with the two control groups and was associated with an increased expression of Fas, an increased susceptibility to Fas agonist (CH11), and a normal production of IL2 in cell cultures. These data suggest that the enhanced apoptosis is due to a mechanism of “active” antigen-driven death, induced by the expression of death cytokines and not by the failure of cell growth factors. We conclude that peripheral lymphocytes are activated in NSTEMI and undergo an enhanced programmed cell death due to activation mechanisms. It is likely that lymphocyte activation occurs before the onset of acute ischemia and contributes to the plaque rupture and to the myocardial ischemic insult.

Relationship between serum complement and different lipid disorders

Abstract Inflammatory and lipid factors share an important role in atherosclerosis. Recent studies showed the concomitant presence and increase of complement components and lipid both in the atherosclerotic plaque and the circulating blood. The aim of this study was to examine the relationship between the complement system and lipid disorders. We evaluated the circulating complement terminal complex C5b-9, a clear sign of complement activation, in three groups of 30 patients the first with hypercholesterolemia, the second with hypertriglyceridemia (associated with low values of HDL-cholesterol), the third with low levels of HDL-cholesterol compared with an equivalent group of matched normolipemic subjects. We found a significant increase of sC5b-9 in each group of patients compared with controls. The mean sC5b-9 level in the hypercholesterolemic population was 366.2±141.2 ng/ml (P<0.01), 395.4±118.2 ng/ml in the hypertrygliceridemic group (P<0.01), 414.8±126.4 ng/ml in the low HDL-chol subjects (P<0.01), and 182.0±40.8. ng/ml in the control group. Regression analysis showed a significant direct correlation between sC5b-9 and triglycerides (r=0.64), and a significant inverse correlation between sC5b-9, HDL-chol (r=0.74), and apo-A1 (r=0.68); no significant relationship was found between sC5b-9 and cholesterol. We suggest that complement activation is associated with the various lipid disorders and is more important in those dyslipidemic conditions in which other factors may be involved. In particular, hypertriglyceridemia may be associated with endothelial and fibrinolytic disturbances, and the decrease of HDL may induce the failure of the regulatory proteins transported by the same HDL.