Beyond lipid-lowering: effects of statins on endothelial nitric oxide

The metabolic syndrome: prevalence, CHD risk, and treatment

An increased risk of coronary heart disease (CHD) morbidity and mortality is associated with the metabolic syndrome, a condition characterized by the concomitant presence of several abnormalities, including abdominal obesity, dyslipidemia, hypertension, insulin resistance (with or without glucose intolerance or diabetes), microalbuminuria, prothrombotic, and proinflammatory states. Estimates of the prevalence of the metabolic syndrome indicate that this condition is now common and likely to increase dramatically over the coming decades, in parallel with greater rates of obesity and Type 2 diabetes. Risk factors for the metabolic syndrome are already present in obese children and adolescents. Thus, identifying and treating all affected individuals promptly and optimally are critical to ensure that this potentially challenging healthcare burden is minimized. Here, we review the prevalence of the metabolic syndrome, dyslipidemias, and CHD risk. Although changes in lifestyle are fundamental to reducing many of the CHD risk factors associated with the metabolic syndrome, pharmacologic interventions also play an important role. Retrospective subanalyses of the effects of statins on coronary event rates and lipid levels in patients with the metabolic syndrome included in clinical trials indicate that these agents are beneficial in correcting the extensive lipid abnormalities that are frequently present in these individuals. However, the optimal management of metabolic syndrome dyslipidemia will depend on the outcomes of future prospective clinical trials. This review examines the underlying causes and prevalence of the metabolic syndrome and its impact on CHD morbidity and mortality and discusses the role of statins in optimizing its management.

Effects of Acid and Lactone Forms of Eight HMG-CoA Reductase Inhibitors on CYP-Mediated Metabolism and MDR1-Mediated Transport

PURPOSE

With the growing clinical usage of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins), the number of reports concerning serious drug-drug interaction has been increasing. Because recent studies have shown that conversion between acid and lactone forms occurs in the body, drug-drug interaction should be considered on both acid and lactone forms. Thus, we investigated the inhibitory effects of acid and lactone forms of eight statins, including one recently withdrawn, cerivastatin, and two recently developed, pitavastatin and rosuvastatin, on cytochrome P450 (CYP) 2C8, CYP2C9, and CYP3A4/5 metabolic activities and multidrug resistance protein 1 (MDR1) transporting activity.

METHODS

The inhibitory effects of statins on CYP metabolic activities and MDR1 transporting activity were investigated using human liver microsomes and MDR1-overexpressing LLC-GA5-COL150 cells, respectively.

RESULTS

The acid forms had minimal inhibitory effects on all CYP activities tested, except for fluvastatin on CYP2C9-mediated tolbutamide 4-hydroxylation (IC50 = 1.7 microM) and simvastatin on CYP3A4/5-mediated paclitaxel 3-hydroxylation (12.0 microM). Lactone forms showed no or minimal inhibitory effects on CYP2C8, CYP2C9, and CYP2C19 activities, except for rosuvastatin on the CYP2C9 activity (20.5 microM), whereas they showed stronger inhibitory effects on the CYP3A4/5 activity with the rank order of atorvastatin (5.6 microM), cerivastatin (8.1 microM), fluvastatin (14.9 microM), simvastatin (15.2 microM), rosuvastatin (20.7 microM), and lovastatin (24.1 microM). Pitavastatin and pravastatin had little inhibitory effect, and a similar order was found also for testosterone 6beta-hydroxylation. MDR1-mediated transport of [3H]digoxin was inhibited only by lactone forms, and the rank order correlated with that of inhibitory effects on both CYP3A4/5 activities. Inhibitory effects on MDR1 activity, and on both CYP3A4/5 activities, could be explained by the lipophilicity; however, a significant correlation was found between the lipophilicity and inhibitory effects on CYP2C8-mediated paclitaxel 6alpha-hydroxylation.

CONCLUSIONS

We showed the difference between the acid and lactone forms in terms of drug interaction. The lipophilicity could be one of the important factors for inhibitory effects. In the case of statins, it is important to examine the effects of both forms to understand the events found in clinical settings, including the pleiotropic effects.

Rho GTPases as therapeutic targets for the treatment of inflammatory diseases

Diseases related to inflammation are a major cause of morbidity and mortality throughout the world and affect the functions of several tissues. The pathophysiology of these diseases involves release of many pro-inflammatory cytokines, such as TNF and IL-1, in addition to anti-inflammatory molecules. Recent studies have demonstrated that neuroimmune interactions are important in the initiation and progress of inflammatory processes. TNF, IL-1 and neuropeptides such as substance P and neurotensin stimulate the release of chemokines, in particular IL-8, a potent neutrophil chemoattractant. Expression of IL-8 is regulated mainly by the transcription factors NF-kappaB, activating protein-1 and CCAAT/enhancer-binding proteins. Recent exciting results indicate that the Rho family of small GTP-binding proteins plays an important role in the expression of NF-kappaB-dependent genes and migration of leukocytes. These results suggest that these proteins may represent a potential therapeutic target to treat several inflammatory states.

Native crystal structure of a nitric oxide-releasing lectin from the seeds of Canavalia maritima

Here, we report the crystallographic study of a lectin from Canavalia maritima seeds (ConM) and its relaxant activity on vascular smooth muscle, to provide new insights into the understanding of structure/function relationships of this class of proteins. ConM was crystallized and its structure determined by standard molecular replacement techniques. The amino acid residues, previously suggested incorrectly by manual sequencing, have now been determined as I17, I53, S129, S134, G144, S164, P165, S187, V190, S169, T196, and S202. Analysis of the structure indicated a dimer in the asymmetric unit, two metal binding sites per monomer, and loops involved in the molecular oligomerization. These confer 98% similarity between ConM and other previously described lectins, derived from Canavalia ensiformis and Canavalia brasiliensis. Our functional data indicate that ConM exerts a concentration-dependent relaxant action on isolated aortic rings that probably occurs via an interaction with a specific lectin-binding site on the endothelium, resulting in a release of nitric oxide.

A novel nitric oxide-releasing statin derivative exerts an antiplatelet/antithrombotic activity and inhibits tissue factor expression

BACKGROUND

NO-releasing statins are new chemical entities, combining HMG-CoA reductase inhibition and slow NO release, that possess stronger anti-inflammatory and antiproliferative activities than the native statins.

OBJECTIVE

We evaluated the antithrombotic effects of nitropravastatin (NCX-6550) by assessing its activity on platelet activation and tissue factor (TF) expression by mononuclear cells in vitro and in vivo.

METHODS AND RESULTS

In vitro, NCX-6550 inhibited (1) U46619- and collagen-induced platelet aggregation in buffer and plasma; (2) collagen-induced P-selectin expression in whole blood and (3) platelet adhesion to collagen-coated coverslips under high shear stress. These effects were displayed at concentrations of NCX-6550 ranging from 25 to 100 mum, and were totally reverted by the guanylylcyclase inhibitor ODQ (10 microm). Equimolar concentrations of pravastatin had no influence on these parameters of platelet function. LPS- and PMA-induced TF expression by blood mononuclear cells was also inhibited by NCX-6550 (IC50 13 microm), but not by pravastatin, as assessed by functional and immunological assays and by real-time PCR. In a mouse model of platelet pulmonary thromboembolism, induced by the i.v. injection of collagen plus epinephrine, pretreatment with NCX-6550 (24-48 mg kg(-1)) significantly reduced platelet consumption, lung vessel occlusion and mortality. Moreover, nitropravastatin markedly inhibited the generation of procoagulant activity by spleen mononuclear cells and peritoneal macrophages in mice treated with LPS. In these in vivo models too, pravastatin failed to affect platelet activation and monocyte/macrophage procoagulant activity.

CONCLUSIONS

Our results show that nitropravastatin exerts strong antithrombotic effects in vitro and in vivo, and may represent an interesting antiatherothrombotic agent for testing in acute coronary syndromes.

High doses of simvastatin upregulate dopamine D1 and D2 receptor expression in the rat prefrontal cortex: possible involvement of endothelial nitric oxide synthase

This study aims to investigate whether or not long-term statin treatment causes upregulation of D1 and D2 receptor gene expression with concomitant increase in endothelial nitric oxide synthase (eNOS) expression in Sprague-Dawley rats. Serum triglyceride levels were dose dependently reduced in the simvastatin-treated rats reaching statistical significance at the highest dose (49% reduction), while pravastatin caused similar effects (52%) at the same dose. Cholesterol levels remained unchanged in both groups at all doses. Simvastatin, 10 or 30 mg kg(-1) day(-1), increased D1 and D2 receptor expressions in the prefrontal cortex. Similar upregulation was observed neither with simvastatin in the striatum nor with pravastatin in both brain regions. Simvastatin (10 mg kg(-1) day(-1)) also increased eNOS expression in the prefrontal cortex but not neuronal NOS or inducible NOS. D1 receptor activation by chloro-APB (5 microM) increased cAMP levels in synaptosomes prepared from the prefrontal cortex of control and simvastatin-treated rats by 88 and 285%, respectively. This effect was markedly attenuated by the selective D1 antagonist SCH-23390 (25 microM). D2 receptor activation by quinpirole (5 microM) had no effect on the basal cAMP levels in synaptosomes prepared from the prefrontal cortex of control and simvastatin-treated rats, while the same concentration of quinpirole completely abolished the D1 receptor-mediated increase. These results suggest that lipophilic statins can alter dopaminergic functions in the prefrontal cortex possibly via a central mechanism. The possibility of a nitric oxide mechanism involving eNOS requires further investigation.

Clinical impact of vasomotor function assessment and the role of ACE-inhibitors and statins

Impaired endothelial function is recognised as one of the earliest events of atherogenesis. Endothelium-dependent vasomotion has been the principal method to assess endothelial function. In this article, we will discuss the clinical value of the different techniques to evaluate endothelium-dependent vasomotion. To date, there seems not to be a simple and reliably endothelial function test to identify asymptomatic subjects at increased risk for cardiovascular disease in clinical practice. Recent studies indicate that pharmacological interventions, in particular with ACE-inhibitors and statins, might improve endothelial function. However, there is no solid evidence that improvement of endothelial function is a necessity for the observed reduction in cardiovascular events by these compounds. Overall, at this moment, there is no place in clinical practice for the use of endothelial function as a method for risk assessment or target of pharmacological interventions.

The prevention of diabetic microvascular complications of diabetes: is there a role for lipid lowering?

The role of hyperglycemia in the development of microvascular complications of diabetes, such as nephropathy, retinopathy and neuropathy, has been well documented. Evidence is accumulating to support the concept that dyslipidemia can also contribute to the development of these complications. Lipid-lowering agents, such as statins, have been shown to prevent cardiovascular events in patients with diabetes. However, in addition to preventing macrovascular diseases, statins may also be able to retard the progression of microvascular complications of diabetes. Indeed, in addition to reducing lipid levels, these agents can improve endothelial function and reduce oxidative stress, which can improve microvascular function. These findings would provide further support for the use of lipid-lowering agents in patients with diabetes.

Effect of rosuvastatin on outcomes in chronic haemodialysis patients - design and rationale of the AURORA study

BACKGROUND

Patients with end-stage renal disease (ESRD) are at high risk of cardiovascular events. Multiple risk factors for atherosclerosis are present in ESRD and may contribute to the increased risk of cardiovascular mortality in this population. In contrast to patients with normal renal function, the benefits of modifying lipid levels on cardiovascular outcomes in patients with ESRD on haemodialysis have yet to be confirmed in large prospective randomised trials. A study to evaluate the Use of Rosuvastatin in subjects On Regular haemodialysis: an Assessment of survival and cardiovascular events (AURORA) will be the first large-scale international trial to assess the effects of statin therapy on cardiovascular morbidity and mortality in ESRD patients on chronic haemodialysis.

METHODS

More than 2,750 ESRD patients who have been receiving chronic haemodialysis treatment for at least 3 months have been randomised (1:1), irrespective of baseline lipid levels, to treatment with rosuvastatin 10 mg or placebo. The primary study endpoint is the time to a major cardiovascular event (first occurrence of cardiovascular death, non-fatal myocardial infarction or non-fatal stroke). Secondary endpoints include all-cause mortality, major cardiovascular event-free survival time, time to cardiovascular death, time to non-cardiovascular death, cardiovascular interventions, tolerability of treatment and health economic costs per life-year saved. Study medication will be given until 620 subjects have experienced a major cardiovascular event.

CONCLUSION

Our hypothesis is that results from AURORA will establish the clinical efficacy and tolerability of rosuvastatin in patients with ESRD receiving chronic haemodialysis and guide the optimal management of this expanding population.

The statins--therapeutic diversity in renal disease?

PURPOSE OF REVIEW

Statins significantly reduce cholesterol synthesis and reduce cardiovascular morbidity and mortality. In addition, they appear to have beneficial effects independent of their ability to lower cholesterol. Recent publications suggesting a potential role for statin therapy in chronic renal insufficiency, hypertension and following organ transplantation are reviewed.

RECENT FINDINGS

Pharmacokinetic studies have shown statins to be well-tolerated and effective in patients on long-term haemodialysis, providing equivalent control of lipid levels to that seen in matched controls. Preliminary clinical trials suggest that statins may have beneficial disease-modifying effects in chronic inflammatory disease. Furthermore, immunosuppressive and immunomodulatory actions may confer benefit following cardiac transplantation, but this remains to be demonstrated definitively in renal transplant patients. Data to date suggest that, in addition to reduction of cardiovascular risk, statins may help slow the progress of chronic renal insufficiency, particularly in patients with proteinuria. Addition of statin therapy may also contribute to the control of systemic and pulmonary hypertension.

SUMMARY

Encouraging data in support of a wider spectrum of use for statins are emerging. In addition to reduction of cardiovascular risk through lipid lowering, they may represent an important adjunctive therapy in patients with chronic kidney diseases and post-transplantation. However, further large, well-designed clinical trials are required before their widespread use can be recommended in this setting.

Simvastatin reverses the downregulation of dopamine D1 and D2 receptor expression in the prefrontal cortex of 6-hydroxydopamine-induced Parkinsonian rats

Sprague-Dawley rats with unilateral lesion of the medial forebrain bundle by 6-hydroxydopamine showed marked decrease in the expression of dopamine D1 and D2 receptors in the prefrontal cortex. Simvastatin (10 mg/kg/day for 4 weeks) restored receptor expression to control levels. Given the association of dopaminergic dysfunction in the prefrontal cortex and cognitive deficits in Parkinson's disease, these findings may have implication in the treatment of cognitive decline in advanced Parkinson's disease.

Cholesterol-independent effects of statins and new therapeutic targets: ischemic stroke and dementia

The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, or "statins", are used as cholesterol-lowering agents worldwide. Statins inhibit cholesterol biosynthesis, leading to enhanced uptake of low-density lipoprotein (LDL) from the circulation via LDL receptors. This strong cholesterol-lowering action contributes to the beneficial effects of statins. For example, large clinical trials have demonstrated that statins significantly reduce cardiovascular risk. Recent research has shown that statins have other multiple actions involved in endothelial function, cell proliferation, inflammatory response, immunological reactions, platelet function, and lipid oxidation. These "pleiotropic actions" of statins probably provide a significant contribution to the reduction of cardiovascular events. This review summarizes the pleiotropic actions of statins in both basic and clinical studies. It also considers the potential for statin therapy in the treatment of stroke and dementia.

Statins and the response to myocardial injury

The benefits of long-term statin (HMG-CoA reductase inhibitor) treatment for preventing coronary events have been well documented in several large-scale prospective clinical trials. By influencing the determinants of myocardial injury, statins may produce direct cardioprotective effects in the ischemic myocardium and prevent further damaging recurrent events. Although not proven fully in a clinical setting, cholesterol-independent or 'pleiotropic' effects of statins are thought to protect against myocardial injury and may occur via a number of mechanisms. Endothelial dysfunction occurs early in the development of atherosclerosis and is associated with a reduction in endothelial nitric oxide (NO) production. Statins have been shown to increase the expression of endothelial NO synthase, with subsequent augmentation of NO in the vasculature. Statins have also been reported to have anti-inflammatory effects, reducing the release of cytokines and chemokines, decreasing the expression of pro-inflammatory cell adhesion molecules, and reducing the accumulation of neutrophils in myocardial tissue following ischemia and reperfusion. Indeed, the role of statins in reducing infarct size is supported by data from a number of preclinical studies. Statin treatment, administered at the onset of reperfusion, has been shown to reduce infarct size by approximately 50% following ischemia in various animal models, and this may be an NO-dependent effect. Randomized clinical trials have indicated that early initiation of statin treatment is associated with a reduction in both the rate of recurrence of cardiovascular events and death in patients with acute coronary syndrome. In addition, decreased rates of myocardial infarction and mortality were demonstrated in several retrospective studies where statin treatment was administered before an interventional procedure. There is a need for further clinical trials to fully elucidate the importance of pre-procedural statin therapy and to determine the extent and mechanisms by which statins exert their cardioprotective effects.

Atorvastatin reduction of intravascular thrombosis, increase in cerebral microvascular patency and integrity, and enhancement of spatial learning in rats subjected to traumatic brain injury

OBJECT

Atorvastatin, a beta-hydroxy-beta-methylglutaryl coenzyme A reductase inhibitor, has pleiotropic effects, such as promoting angiogenesis, increasing fibrinolysis, and reducing inflammatory responses, and has shown promise in enhancing recovery in animals with traumatic brain injury (TBI) and stroke. The authors tested the effect of atorvastatin on vascular changes after TBI.

METHODS

Male Wistar rats subjected to controlled cortical impact injury were perfused at different time points with fluorescein isothiocyanate (FITC)--conjugated dextran 1 minute before being killed. Spatial memory function had been measured using a Morris Water Maze test at various points before and after TBI. The temporal profile of intravascular thrombosis and vascular changes was measured on brain tissue sections by using a microcomputer imaging device and a laser confocal microscopy. The study revealed the following results. 1) Vessels in the lesion boundary zone and hippocampal CA3 region showed a variety of damage, morphological alterations, reduced perfusion, and intraluminal microthrombin formation. 2) Atorvastatin enhanced FITC-dextran perfusion of vessels and reduced intravascular coagulation. 3) Atorvastatin promoted the restoration of spatial memory function.

CONCLUSIONS

These results indicated that atorvastatin warrants investigation as a potential therapeutic drug for TBI.

Delayed Thrombosis after Traumatic Brain Injury in Rats

Secondary thrombosis may contribute to cerebral ischemia caused by traumatic brain injury (TBI). In this study, we sought to investigate the temporal and spatial profiles of intravascular thrombosis and to evaluate the effect of atorvastatin, a beta-hydroxy-beta-methylglutaryl coenzyme-A (HMG-CoA) reductase inhibitor, on thrombosis after TBI. Young male Wistar rats weighing 350-400 g were subjected to controlled cortical impact injury, and were sacrificed at 1 and 4 h, and 1, 3, 8, and 15 days after TBI (5 rats/time point), respectively. For the evaluation of the effects of atorvastatin on intravascular thrombosis, rats were subjected to TBI, and subsequently atorvastatin (1 mg/kg) was orally administered starting 1 day after TBI and then daily until sacrifice at 3, 8, and 15 days after TBI (5 rats/time point). Before sacrifice of animals, blood was withdrawn and employed for the measurement of von Willibrand factor and platelet activity using enzyme-linked immunoabsorbant assay (ELISA). Brain tissues were prepared for histological analysis. The data show that (1) delayed thrombosis is present in the lesion boundary zone and in the hippocampal CA3 region, starting at 1-4 h, peaking at 1-3 days, and then declining at 8 and 15 days after TBI; (2) intravascular thrombosis also occurs in the other areas of cortex, striatum, and corpus callosum, but with a scattered distribution; (3) delayed thrombi are composed of platelets, fibrin, and vWF; and (4) reduction of the plasma vWF level and platelet activity by atorvastatin decreases delayed thrombosis after TBI. These data suggest that atorvastatin reduces intravascular thrombosis attributed to hemostatic disturbances caused by TBI.

Atorvastatin reduction of intracranial hematoma volume in rats subjected to controlled cortical impact

Object. Atorvastatin, a β-hydroxy-β-methylglutaryl coenzyme A reductase inhibitor, has pleiotropic effects such as improving thrombogenic profile, promoting angiogenesis, and reducing inflammatory responses and has shown promise in enhancing neurological functional improvement and promoting neuroplasticity in animal models of traumatic brain injury (TBI), stroke, and intracranial hemorrhage. The authors tested the effect of atorvastatin on intracranial hematoma after TBI.

Methods. Male Wistar rats were subjected to controlled cortical impact, and atorvastatin (1 mg/kg) was orally administered 1 day after TBI and daily for 7 days thereafter. Rats were killed at 1, 8, and 15 days post-TBI. The temporal profile of intraparenchymal hematoma was measured on brain tissue sections by using a MicroComputer Imaging Device and light microscopy.

Conclusions. Data in this study showed that intraparenchymal and intraventricular hemorrhages are present 1 day after TBI and are absorbed at 15 days after TBI. Furthermore, atorvastatin reduces the volume of intracranial hematoma 8 days after TBI.

Modulatory effects of HMG-CoA reductase inhibitors in diabetic microangiopathy

3-hydroxy-3-methyl-glutaryl CoA (HMG-CoA) reductase inhibitors or statins are competitive inhibitors of the rate-limiting enzyme in cholesterol biosynthesis. Several large landmark clinical studies have shown a marked reduction of cardiovascular mortality and morbidity in patients treated with statins. Because of the strong association between serum cholesterol levels and coronary artery disease, investigators initially assumed that the predominant beneficial effects of statins result from their lipid-lowering properties. However, more recent observations have suggested that the clinical benefits of statins may be in part independent of their cholesterol-lowering effects. The pleiotropic or cholesterol-independent effects of statins might result from preventing the production of isoprenoids. Isoprenoids serve as important lipid attachments for the post-translational modification of a variety of proteins such as small GTP binding proteins implicated in intracellular signaling. The list of different pleiotropic effects of statins is still growing and, among others, includes the modulatory effects of statins on endothelial function, oxidative stress, coagulation, plaque stability, and inflammation. The pleiotropic effects of statins represent an area of great interest in prevention and therapy of cardiovascular and other chronic diseases. An area of particular interest is the potential beneficial effects of statins in diabetes and its micro/macrovascular complications. This review summarizes our current understanding of the pleiotropic effects of statins in diabetes and the modulatory effects of statins in various pathobiological pathways involved in diabetes and its complications.

The antioxidant effects of statins

Oxidative stress contributes to the initiation and the development of atherosclerotic plaques and adversely influences myocardial integrity. Statins interfere with oxidation in several ways that may contribute to reducing the atherogenic process. In addition to direct antioxidant effects, statins reduce circulating oxidized low-density lipoproteins (oxLDL) and inhibit their uptake by macrophages. They also reduce circulating markers of oxidation such as F2-isoprostane and nitrotyrosine. Statins inhibit oxidant enzymes activity such as that of reduced nicotinamide adenine dinucleotide phosphate (NAD[P]H) oxidase and myeloperoxidase and up-regulate the activity of antioxidant enzymes such as catalase and paraoxonase. They reduce endothelial dysfunction mainly by their ability to enhance endothelial nitric oxide bioavailability, which is achieved by several mechanisms. The antioxidant properties of statins extend to organ protection especially the myocardium and the lungs.

Effect of administration of lovastatin on the development of late pulmonary effects after whole-lung irradiation in a murine model

Our group's work on late radiation effects has been governed by the hypothesis that the effects observed in normal tissues are a consequence of multicellular interactions through a network of mediators. Further, we believe that inflammation is a necessary component of this process. We therefore investigated whether the recruitment of mononuclear cells, observed during the pneumonitic period in the irradiated normal lung, is dependent on the expression of chemokines, notably Mcp1. Since statins have been shown to reduce chemokine expression and inflammatory cell recruitment, we specifically examined whether statins could be used to reduce monocyte recruitment. Mice received 15 Gy whole-lung irradiation; treated groups were administered lovastatin three times weekly starting either immediately or 8 weeks postirradiation. At subsequent intervals, animals were killed humanely, and cellular, mRNA and protein analyses were undertaken. Statin-treated animals demonstrated a statistically significant reduction in both macrophage and lymphocyte populations in the lung compared to radiation alone as well as improved rates of survival and decreased collagen content. In addition, ELISA measurements showed that radiation-induced increases in Mcp1 protein were reduced by statin treatment. Additional experiments are needed to assess whether statins offer a potential treatment for the amelioration of late effects in breast and lung cancer patients undergoing radiation therapy.

Atorvastatin restores endothelial function in normocholesterolemic smokers independent of changes in low-density lipoprotein

Cigarette smoking impairs endothelial function. Hydroxymethylglutaryl (HMG) CoA reductase inhibitors (statins) may favorably affect endothelial function via nonlipid mechanisms. We tested the hypothesis that statins would improve endothelial function independent of changes in lipids in cigarette smokers. Twenty normocholesterolemic cigarette smokers and 20 matched healthy control subjects were randomized to atorvastatin 40 mg daily or placebo for 4 weeks, washed out for 4 weeks, and then crossed-over to the other treatment. Baseline low-density lipoprotein (LDL) levels were similar in smokers and healthy subjects, 103+/-22 versus 95+/-27 mg/dL, respectively (P=NS) and were reduced similarly in smokers and control subjects by atorvastatin, to 55+/-30 and 58+/-20 mg/dL, respectively (P=NS). Vascular ultrasonography was used to determine brachial artery, flow-mediated, endothelium-dependent, and nitroglycerin-mediated, endothelium-independent vasodilation. To elucidate potential molecular mechanisms that may account for changes in endothelial function, skin biopsy specimens were assayed for eNOS mRNA, eNOS activity, and nitrotyrosine. Endothelium-dependent vasodilation was less in smokers than nonsmoking control subjects during placebo treatment, 8.0+/-0.6% versus 12.1+/-1.1%, (P=0.003). Atorvastatin increased endothelium-dependent vasodilation in smokers to 10.5+/-1.3% (P=0.017 versus placebo) but did not change endothelium-dependent vasodilation in control subjects (to 11.0+/-0.8%, P=NS). Endothelium-independent vasodilation did not differ between groups during placebo treatment and was not significantly affected by atorvastatin. Multivariate analysis did not demonstrate any association between baseline lipid levels or the change in lipid levels and endothelium-dependent vasodilation. Cutaneous nitrotyrosine levels and skin microvessel eNOS mRNA, but not ENOS activity, were increased in smokers compared with controls but unaffected by atorvastatin treatment. Atorvastatin restores endothelium-dependent vasodilation in normocholesterolemic cigarette smokers independent of changes in lipids. These results are consistent with a lipid-independent vascular benefit of statins but could not be explained by changes in eNOS message and tissue oxidative stress. These findings implicate a potential role for statin therapy to restore endothelial function and thereby investigate vascular disease in cigarette smokers.

Effect of simvastatin and fenofibrate on endothelium in Type 2 diabetes

Statins and fibrates influence endothelial activity and consequently atherogenesis but the mechanisms are not well understood. Twenty Type 2 diabetic patients with dyslipidemia were treated 3 months with simvastatin (20 mg daily) and then 3 months with fenofibrate (200 mg daily) with 2 months of wash-out between the two treatments. Laboratory parameters of oxidative stress, fibrinolysis and endothelial function were evaluated before and at the end of each treatment period. The significant decrease in serum total and LDL-cholesterol concentrations (P<0.0001) caused by simvastatin was associated with an increase in serum N-acetyl-beta-glucosaminidase activity (P<0.001), ascorbic acid (P<0.001), plasminogen activator inhibitor (PAI-1) (P<0.01), vonWillebrand factor (P<0.05), E-selectin (P<0.01) and vascular endothelial growth factor (P<0.05) concentrations and with a decrease in plasma glutathione (P<0.01) levels. Fenofibrate caused a significant decrease in serum triglyceride concentration (P<0.0001) associated with a decrease in plasma malondialdehyde (P<0.001) and an increase in plasma PAI-1 (P<0.05) and P-selectin (P<0.05) concentrations. We conclude that simvastatin and fenofibrate interact, by different mechanisms, with oxidative stress, a key factor in the modification of fibrinolysis and endothelial function in Type 2 diabetes.

Targeting eNOS for stroke protection

Nitric oxide (NO) generated by endothelial NO synthase (eNOS) plays a crucial role in vascular function and homeostasis. NO possesses vasodilatory, anti-inflammatory, antithrombotic and antiproliferative properties. Augmentation of NO production increases cerebral blood flow, which can lead to neuroprotection during brain ischaemia. Several modalities that upregulate eNOS expression and/or activity have recently been identified, including HMG-CoA reductase inhibitors (statins), steroid hormones, nutrients and physical activity. They all increase NO bioavailability, leading to enhanced cerebral blood flow and protection from ischaemic stroke. Thus, therapeutic modalities that target eNOS not only serve as preventive measures to reduce stroke incidence but also could represent novel treatment strategies for reducing brain injury during cerebral ischaemia.

Enhanced cutaneous vascular response in AD subjects under donepezil therapy

OBJECTIVE

Abnormal cutaneous vasodilatory responses to the iontophoresis of vasodilators were previously observed in Alzheimer's disease (AD). We sought to replicate these observations and further identify peripheral vascular components of AD pathology.

METHODS

Methacholine chloride (MCh), acetylcholine chloride (ACh), and sodium nitroprusside (SNP) were applied iontophoretically to forearm skin. Laser Doppler imaging of treated areas yielded total perfusion response values.

RESULTS

Response to MCh was enhanced 78% ( P=0.003 ) in AD subjects under therapy with the acetylcholinesterase inhibitor (AChEI) donepezil ( N=9 ), relative to age- and sex-matched controls ( N=12 ). Significant increases in perfusion were also observed after application of ACh (68%, P=0.03 ) and SNP (46%, P=0.04 ).

CONCLUSIONS

A previous study reported attenuated response to ACh in AD. Paradoxically, we observed a substantially enhanced response that is likely a consequence of donepezil therapy. The increased response to the endothelium-independent vasodilator SNP indicates improved general vasodilatory response, perhaps due to preservation of endogenous ACh by donepezil. Cerebral perfusion in response to functional activation may be improved in this way, suggesting a secondary therapeutic mode of donepezil.

Lipaemia, Inflammation and Atherosclerosis

Atherosclerosis is the major cause of death in the world. Fasting and postprandial hyperlipidaemia are important risk factors for coronary heart disease (CHD). Recent developments have undoubtedly indicated that inflammation is pathophysiologically closely linked to atherogenesis and its clinical consequences. Inflammatory markers such as C-reactive protein (CRP), leucocyte count and complement component 3 (C3) have been linked to CHD and to hyperlipidaemia and several other CHD risk factors. Increases in these markers may result from activation of endothelial cells (CRP, leucocytes, C3), disturbances in adipose tissue fatty acid metabolism (CRP, C3), or from direct effects of CHD risk factors (leucocytes). It has been shown that lipoproteins, triglycerides, fatty acids and glucose can activate endothelial cells, most probably as a result of the production of reactive oxygen species. Similar mechanisms may also lead to leucocyte activation. Increases in triglycerides, fatty acids and glucose are common disturbances in the metabolic syndrome and are most prominent in the postprandial phase. People are in a postprandial state most of the day, and this phase is proatherogenic. Inhibition of the activation of leucocytes, endothelial cells, or both, is an interesting target for intervention, as activation is obligatory for adherence of leucocytes to the endothelium, thereby initiating atherogenesis. Potential interventions include the use of unsaturated long-chain fatty acids, polyphenols, antioxidants, angiotensin converting enzyme inhibitors and high-dose aspirin, which have direct anti-inflammatory and antiatherogenic effects. Furthermore, peroxisome proliferator activating receptor gamma (PPARgamma) agonists and statins have similar properties, which are in part independent of their lipid-lowering effects.

Nitric oxide, an iceberg in cardiovascular physiology:

The endothelium is now recognized not only as a physical barrier between blood and vascular wall, but also as an important and strategically located organ with multiple endocrine and paracrine functions. By releasing vasoactive substances, the endothelium acts as an inhibitory regulator of vascular contraction, leukocyte adhesion, vascular smooth muscle cell growth, and platelet aggregation. This review intends to demonstrate how much the picture of the biological functions of nitric oxide has changed in cardiovascular physiology, extending beyond its vessel-relaxing activity, as well as to highlight new insights into the factors affecting its bioavailability and regulation in relation with many cardiovascular diseases.

The cardioprotective effects of statins

In addition to their lipid-modulating properties, statins have a large number of beneficial cardiovascular effects that have emerged over time and that were not anticipated during drug development. The lipid and nonlipid effects act in a concerted way to reduce the ischemic burden of the myocardium and to protect it against injury. By acting on the vessel wall, statins may prevent lesion initiation and repair injuries, enhance myocardial perfusion, slow lesion progression, and prevent coronary occlusion. They may also directly reduce myocardial damage, favor myocardial repair, and protect against immune injury. This review focuses on properties of statins that contribute to their cardioprotective effect. The first section includes information on modulation of vascular tone, endothelial permeability and function, inhibition of complement injury, curbing of foam cell formation, antioxidant and anti-inflammatory properties, and profibrinolytic and anticoagulant activities. The second section relates to reduction of myocardial necrosis, myocardial hypertrophy, blood pressure, and heart failure, as well as mobilization of endothelial progenitor cells for repair, angiogenic effects, and immunomodulation. In many instances, results of in vitro and animal studies have raised expectations and prompted studies in humans. Several clinical trials have confirmed these expectations and have strengthened the value of statins as valuable antiatherosclerotic and cardioprotective agents.