HMG CoA reductase inhibitors affect the fibrinolytic system of human vascular cells in vitro: a comparative study using different statins

Mild hyperhomocysteinemia is associated with a decreased fibrinolytic activity in patients after ST-elevation myocardial infarction

BACKGROUND

Elevated homocysteine (Hcy) levels have been associated with increased risk for cardiovascular disease and it has been shown that hyperhomocysteinemia is associated with increased levels of t-PA antigen in individuals without evidence for coronary artery disease (CAD). The aim of this study was to examine if Hcy plasma levels are associated with plasma levels of fibrinolytic factors in patients with CAD and a history of acute myocardial infarction.

METHODS

We measured in 56 patients with CAD, 1 month after their first ST-elevation myocardial infarction, plasma levels of Hcy, the fibrinolytic parameters tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor-type-1 (PAI-1), and t-PA-PAI-1 complexes.

RESULTS

Hcy plasma levels inversely correlated with t-PA activity (r=-0.303, p<0.05). Patients with mild hyperhomocysteinemia (Hcy>15 micromol/L, n=8) showed significantly lower plasma levels of t-PA activity (p<0.05). Regression analysis revealed that out of cardiovascular risk factors and medical treatment only Hcy was significantly associated with t-PA activity.

CONCLUSIONS

Patients with CAD after a first myocardial infarction and hyperhomocysteinemia show a reduced t-PA activity independently from cardiovascular risk factors and medical treatment. Homocysteine lowering therapies may increase fibrinolytic activity and thereby may help to avoid atherothrombotic events in patients with CAD after a first myocardial infarction.

Statins in nephrotic syndrome: a new weapon against tissue injury

The nephrotic syndrome is characterized by metabolic disorders leading to an increase in circulating lipoproteins levels. Hypertriglyceridemia and hypercholesterolemia in this case may depend on a reduction in triglyceride-rich lipoproteins catabolism and on an increase in hepatic synthesis of Apo B-containing lipoproteins. These alterations are the starting point of a self-maintaining mechanism, which can accelerate the progression of chronic renal failure. Indeed, hyperlipidemia can affect renal function, increase proteinuria and speed glomerulosclerosis, thus determining a higher risk of progression to dialysis. 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase is the rate-limiting enzyme in cholesterol synthesis from mevalonate and its inhibitors, or statins, can therefore interfere with the above-mentioned consequences of hyperlipidemia. Statins are already well known for their effectiveness on primary cardiovascular prevention, which cannot be explained only through their hypolipemic effect. As far as kidney diseases are concerned, statin therapy has been shown to prevent creatinine clearance decline and to slow renal function loss, particularly in case of proteinuria, and its favorable effect may depend only partially on the attenuation of hyperlipidemia. Statins may therefore confer tissue protection through lipid-independent mechanisms, which can be triggered by other mediators, such as angiotensin receptor blockers. Possible pathways for the protective action of statins, other than any hypocholesterolemic effect, are: cellular apoptosis/proliferation balance, inflammatory cytokines production, and signal transduction regulation. Statins also play a role in the regulation of the inflammatory and immune response, coagulation process, bone turnover, neovascularization, vascular tone, and arterial pressure. In this study, we would like to provide scientific evidences for the pleiotropic effects of statins, which could be the starting point for the development of new therapeutical strategies in different clinical areas.

Hydroxymethylglutaryl-coenzyme A reductase inhibitors induce apoptosis in human cardiac myocytes in vitro

Recent findings have implicated hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors or statins, an established class of drugs for the treatment of hypercholesterolemia, in tissue remodeling in the heart. Statins induce apoptosis in different cell culture systems including rat neonatal cardiomyocytes. We investigated possible effects of different statins in vitro in human adult cardiac myocytes on the expression of proteins thought to be involved in the regulation of apoptosis such as Mcl-1, an inhibitor of apoptosis, Bax, an inducer of apoptosis, as well as on cytoplasmic histone-associated-DNA-fragments. Human adult cardiac myocytes (HACM) were treated with different statins at concentrations from 0.01 to 5 microM for up to 96 h. Whereas the lipophilic statin simvastatin at a concentration of 5 microM downregulated Mcl-1 mRNA by 49%, the hydrophilic pravastatin had no effect. Bax mRNA levels were not affected by neither of the statins. Simvastatin but not pravastatin reduced Mcl-1 protein expression whereas Bax protein was not detectable in HACM as determined by Western blotting. Simvastatin, atorvastatin and fluvastatin induced an up to seven-fold increase in histone-associated-DNA-fragments whereas pravastatin did not. Simvastatin up regulated histone-associated-DNA-fragments dose-dependently, and mevalonate and geranylgeranyl pyrophosphate reversed this effect to control levels. Our results show that lipophilic statins can induce a pro-apoptotic state in human adult cardiac myocytes in vitro. We speculate that, similar to findings in animal models, statins might be involved in the attenuation of cardiac hypertrophy and remodeling in humans by modulating the balance between cell survival and apoptosis.

Atorvastatin reduces plasminogen activator inhibitor-1 expression in adipose tissue of atherosclerotic rabbits

BACKGROUND

Plasminogen activator inhibitor-1 (PAI-1) expression are increased in adipose tissues/adipocytes of obese mice, which is associated with a hypofibrinolytic state that contributes to thrombosis. We recently demonstrated that PAI-1 expression increases in adipose tissues/adipocytes of cholesterol-fed rabbits. In this study, we evaluated the ability of atorvastatin to modulate PAI-1 expression in cholesterol-fed rabbits and the regulatory mechanism.

METHODS

Male rabbits were randomly fed with normal diet and high-cholesterol diet for 8 weeks, following 4 weeks, those fed high-cholesterol diet were randomly assigned to 2.5 mg/kg/day atorvastatin or starch. At the end of 12 weeks, subcutaneous adipose was collected, and culture adipocyte. PAI-1 mRNA was detected by RT-PCR. PAI-1 concentrations were determined with ELISA. The effect of atorvastatin and mevalonate (MVA) on PAI-1 production in adipocytes in vitro was observed.

RESULTS

Atorvastatin significantly reduced serum TC and LDL-C concentrations (p<0.05), and decreased plasma PAI-1 concentration and PAI-1 expression in adipose tissues/adipocytes from cholesterol-fed rabbits. In vitro, atorvastatin dose-dependently suppressed PAI-1 expression and protein secretion in adipocytes. MVA reversed the inhibitory effect of atorvastatin on PAI-1 expression in concentration-dependent manner.

CONCLUSIONS

Atorvastatin reduces plasma PAI-1 concentration and PAI-1 expression in adipose tissue and adipocyte of atherosclerotic rabbit, and inhibits PAI-1 expression and protein secretion in adipocytes in vitro, suggesting that it may have an antithrombtic effect. We also suggest that the mevalonate pathway may play an important role in PAI-1 expression in adipocyte.

Potential vascular benefits of statins

Atherosclerosis is associated with a number of functional abnormalities that affect endothelium-dependent vasomotor function, inflammation, and thrombosis. The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) have effects on many of these functions, likely explaining their benefit in reducing the incidence of clinical events in patients at high risk of cardiovascular disease. Statins may improve this vascular biology by lowering levels of low-density lipoprotein (LDL) or potentially by a number of non-LDL-related mechanisms. Cell culture and some animal studies have demonstrated LDL-independent effects of statins. The non-LDL mechanisms include effects on isoprenoid production and function, interactions between caveolin and nitric oxide synthase, and direct immunomodulatory effects. Although these mechanisms are clearly demonstrated in the experimental setting, their relevance to the clinical use of statins is unknown. From a purely pragmatic viewpoint, the debate of lipid versus nonlipid effects of statins matters little to clinical practice. Their proven effect on vascular biology and risk reduction justifies their important therapeutic role.

Influence of statins on postoperative wound complications after inguinal or ventral herniorrhaphy

The lipid-lowering agents, statins, are the most commonly prescribed class of drugs in the western world. Because of their widespread use, many patients undergo surgical procedures while on statins. Statins, in addition to cholesterol-lowering effects, also have anticoagulant, immunosuppressive, and antiproliferative properties that may affect the risk of local wound complications. This study investigated the relationship between statins and postoperative wound complications in a large cohort of patients undergoing inguinal or ventral hernia repair. Data mining was performed in the Veterans Integrated Service Network (VISN)16 Data Warehouse. This database contains clinical and demographic information about all veterans cared for at the ten VA Medical Centers that comprise the South Central VA Healthcare Network in the mid-south region of the US. Aggregate data (age, body mass index, smoking history, gender, race, history of diabetes, statin use, and postoperative wound complications) were obtained for all patients who underwent inguinal or ventral hernia repair during the period October 1, 1996-November 30, 2004. During the period of the query, 10,782 patients (10,676 male, 106 female), 1,242 (11.5%) of whom received statins, underwent herniorrhaphy. Statin use did not affect the risk of wound infection or delayed wound healing. Statin use was, however, associated with an increased rate of local postoperative bleeding complications (P=0.01). When the type of hernia, age, smoking, diabetes, and body mass index were included in a multivariate analysis, statins remained borderline significant as an independent predictor of wound hematoma/postoperative bleeding (P=0.04), odds ratio 1.6 (95% CI 1.03-2.44). Patients who undergo inguinal herniorrhaphy while on statins have an increased risk of postoperative wound hematoma/hemorrhage. Focus on additional factors that may affect the propensity to postoperative bleeding and on meticulous intraoperative hemostasis are particularly important in such patients.

Protective effects of statins involving both eNOS and tPA in focal cerebral ischemia

Previous studies have shown that 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) protect the brain against ischemic injury by upregulating endothelial nitric oxide synthase (eNOS). Here, we tested the hypothesis that statins provide additional beneficial effects by also upregulating endogenous tissue plasminogen activator (tPA) and enhancing clot lysis in a mouse model of embolic focal ischemia. Heterologous blood clots (0.2 mm) were injected into the distal internal carotid artery to occlude blood flow in the middle cerebral artery territory after long-term (14 days) simvastatin, atorvastatin or vehicle treatment. Ischemic lesion volume, neurologic deficits, as well as residual blood clots were measured at 22 h. Reverse transcription-polymerase chain reaction assessed mRNA levels of eNOS, tPA, and the endogenous plasminogen activator inhibitor PAI-1. Ischemic lesion volumes and neurologic deficits were significantly reduced in wild-type mice by both simvastatin and atorvastatin. Statins increased eNOS and tPA mRNA levels but did not change mRNA levels of PAI-1. In eNOS knockout mice, atorvastatin reduced the volume of ischemic tissue and improved neurologic outcomes after arterial occlusion by blood clot emboli. In contrast, statins did not have protective effects in tPA knockout mice after embolic focal ischemia, but only in a filament model where focal ischemia was achieved via mechanical occlusion. These results suggest that statins protect against stroke by multiple mechanisms involving both eNOS and tPA. The involvement of each pathway may be revealed depending on the choice of experimental stroke model.

Inflammatory Cytokines Interleukin-6 and Oncostatin M Induce Plasminogen Activator Inhibitor-1 in Human Adipose Tissue

Background— Adipose tissue is a prominent source of plasminogen activator inhibitor-1 (PAI-1), the primary physiological inhibitor of plasminogen activation. Increased PAI-1 expression acts as a cardiovascular risk factor, and plasma levels of PAI-1 strongly correlate with body mass index (BMI). Elevated serum levels of interleukin-6 (IL-6), an inflammatory cytokine and a member of the glycoprotein 130 (gp130) ligand family, are found in obese patients and might indicate low-grade systemic inflammation. Another gp130 ligand, oncostatin M (OSM), upregulates PAI-1 in cardiac myocytes, astrocytes, and endothelial cells. We used tissue explants and primary cultures of preadipocytes and adipocytes from human subcutaneous and visceral adipose tissue to investigate whether IL-6 and OSM affect PAI-1 expression in fat.

Methods and Results— Human subcutaneous and visceral adipose tissue responded to treatment with IL-6 and OSM with a significant increase in PAI-1 production. Human preadipocytes were isolated from subcutaneous and visceral adipose tissue. Adipocyte differentiation was induced by hormone supplementation. All cell types expressed receptors for IL-6 and OSM and produced up to 12-fold increased levels of PAI-1 protein and up to 9-fold increased levels of PAI-1 mRNA on stimulation with IL-6 and OSM. AG-490, a janus kinase/signal transducer and activator of transcription inhibitor, abolished the OSM-dependent PAI-1 induction almost completely.

Conclusions— We have for the first time established a link between the gp130 ligands, the proinflammatory mediators IL-6 and OSM, and the expression of PAI-1 in human adipose tissue. Thus, we speculate that IL-6 and OSM, by upregulating PAI-1 in adipose tissue, can contribute to the increased cardiovascular risk of obese patients.

Statins as coronary vasodilators in isolated bovine coronary arteries--involvement of PGI2 and NO

Here we studied direct vasodilation induced by statins in isolated bovine coronary arteries. In rings of coronary bovine arteries preconstricted with prostaglandin F(2 alpha) (3 x 10(-8) - 10(-5)), lovastatin, simvastatin, atorvastatin and cerivastatin (3-30 microM) but not pravastatin induced concentration-dependent vasodilation. Removal of endothelium diminished response to simvastatin, cerivastatin and atorvastatin (30 microM) (67.4+/-4.56 vs. 22.7+/-8.14%, 96.9+/-2.27% vs. 54.5+/-6.86%, 67.4+/-4.01% vs. 34.6+/-5.66%, respectively). In presence of L-NAME (300 microM) or indomethacin (5 microM) responses to simvastatin, atorvastatin and cerivastatin, were also partially diminished. In contrast, lovastatin-induced vasorelaxation was not significantly affected by removal of endothelium (35.6+/-4.19% vs. 28.8+/-5.24%) or by pretreatment with L-NAME or indomethacin. In summary, with the exception of pravastatin, statins act as coronary vasodilators. Simvastatin, cerivastatin and atorvastatin but not lovastatin induced vasodilation displayed endothelium dependent- and endothelium-independent components. The endothelium-dependent effect of statins was mediated by NO and PGI(2), while the mechanism of smooth muscle cells-dependent component remains to be determined.

A review of the lipid-related effects of fluvastatin

BACKGROUND

Statin therapy has been shown to significantly decrease vascular events and overall mortality in primary and secondary prevention trials. This review considers the pharmacology, nonlipid-lowering effects and clinical trial evidence of fluvastatin based on a survey of PubMed entries.

FINDINGS

Recent clinical data show that treatment with fluvastatin is associated with a variety of benefits in different high-risk populations along with a good safety profile. Fluvastatin exerts non-lipid lowering-associated pleiotropic effects in both clinical and experimental studies. Furthermore, an extended-release formulation of fluvastatin with a favourable pharmacokinetic profile is available.

CONCLUSION

Treatment with fluvastatin offers a convenient, safe and evidence-based approach to managing dyslipidaemias and preventing vascular events.

Do the pleiotropic effects of statins in the vasculature predict a role in inflammatory diseases?

Pleiotropic effects are now described for the 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (or statins) that might have utility in the context of chronic inflammatory autoimmune disease. Here we discuss the pharmacology and established uses of statins and in this context describe potential anti-inflammatory and immune-modulatory effects. An extensive in vitro data set defines roles for statins in modifying endothelial function, particularly with respect to adhesion molecule expression and apoptosis. Broader effects on leukocyte function have now emerged including altered adhesion molecule expression, cytokine and chemokine release and modulation of development of adaptive immune responses via altered MHC class II upregulation. In vivo data in several inflammatory models, including collagen-induced inflammatory arthritis and experimental autoimmune encephalomyelitis, suggest that such effects might have immune-modulatory potential. Finally, a recent clinical trial has demonstrated immunomodulatory effects for statins in patients with rheumatoid arthritis. Together with their known vasculoprotective effects, this growing body of evidence provides compelling support for longer-term trials of statin therapy in human disease such as rheumatoid arthritis.

Statins in the first-line therapy of acute coronary syndrome - similar to aspirin?

Statins are cholesterol-lowering drugs, highly effective in the primary and secondary prevention of coronary artery disease. It has been found, however, that statins also have nonlipid effects; they can influence different pathways, which have been described to participate in the pathogenesis of acute coronary syndrome (ACS). Inflammation or decreased production of nitric oxide are obvious targets for statin therapy. Recently, several large clinical trials have been published, showing safety and, in some areas, efficacy of administration of statins early after ACS. Furthermore, there is growing evidence from both experimental and small clinical studies that statin therapy may have favourable effects when started as soon as possible after the development of ACS. Confirmation of this approach by large randomized trials is needed; however, based on currently available data, statins have high chance of achieving a similar place in the first-line therapy of ACS as the pillar of contemporary therapeutic strategy, aspirin.

Does aggressive statin therapy offer improved cholesterol-independent benefits compared to conventional statin treatment?

There is currently intense research interest in the properties of HMG-CoA reductase inhibitors (statins) beyond their well-documented lipid-lowering action. Studies have consistently demonstrated that administration of statin therapy decreases levels of the inflammatory marker C-reactive protein (CRP), a marker associated with an increased risk of cardiovascular events. This effect appears to be independent of the extent of reduction in total or LDL-cholesterol. Statins also appear to improve endothelial dysfunction by increasing endothelium-dependent vasodilatation. There is also evidence that statins inhibit fibrin formation and thrombus development, an effect that which would be clinically beneficial following plaque fissure or rupture. Early preclinical and clinical evidence suggests that there are quantitative differences between statin regimens in terms of their cholesterol-independent properties. Trials comparing equipotent doses of different statins, based on lipid-lowering efficacy, have not reported any differences in cholesterol-independent properties. However, the current evidence base indicates that more aggressive statin regimens are associated with an enhanced anti-inflammatory effect. Intensive lipid-lowering using statin therapy generates a greater reduction in mortality than standard lipid management, and it is possible that enhanced cholesterol-independent effects may account for some of this excess benefit.

Time course differences for statin-induced pleiotropic effects in hypercholesterolemic patients

BACKGROUND

It is unclear whether there are temporal differences for the pleiotropic effects for different members of the statin class. The present study investigated differences in the short- and intermediate-term pleiotropic effects of statins in hypercholesterolemic patients.

METHODS

Thirty-five hypercholesterolemic patients were randomly treated with either atorvastatin or cerivastatin for 3 months. We measured fasting lipid concentrations, thiobarbituric acid reactive substances (TBARS), fibrinolytic parameters, and flow-mediated dilation of the brachial artery (FMD) at baseline and after 2 weeks and 3 months of therapy.

RESULTS

After 2 weeks of therapy, atorvastatin decreased the low density lipoprotein (LDL) cholesterol, small, dense LDL cholesterol (34+/-22 vs. 18+/-20%, P<0.01), remnant-like particles (RLP) cholesterol (8.8+/-6.0 vs. 5.1+/-2.6 mg/ml, P<0.01), and TBARS (3.3+/-1.0 vs. 3.1+/-0.9 nmol/ml, P<0.05), and cerivastatin decreased LDL cholesterol. After 3 months of therapy, atorvastatin decreased small dense LDL cholesterol (8+/-13%, P<0.0001) additionally, and cerivastatin decreased small, dense LDL cholesterol (51+/-11 vs. 12+/-22%, P<0.0001) and plasminogen activator inhibitor type 1 (68+/-32 vs. 51+/-21 ng/ml, P<0.05). FMD increased significantly in both groups after 2 weeks, although the relative change in FMD was greater with cerivastatin therapy after 2 weeks than atorvastatin therapy (60+/-78 vs. 23+/-26%, P<0.05). However, FMD was the same for both groups after 3 months (58+/-65 vs. 66+/-61%, NS), because atorvastatin additionally increased FMD. There was no correlation between these pleiotropic effects and the improvement in the lipid profile for either group.

CONCLUSIONS

These findings suggest that the degree of pleiotropic effect as well as the time course for the effect are different among members of the statin class of drugs.

Effects of HMG-CoA reductase inhibitors on coagulation and fibrinolysis processes

Recent large clinical trials have demonstrated that HMG-CoA reductase inhibitors, or statins, markedly reduce morbidity and mortality when used in the primary and secondary prevention of cardiovascular disease. It has been established that the benefits of statin therapy in cardiovascular disease can be explained not only by the lipid-lowering potential of statins but also by nonlipid-related mechanisms (so-called "pleiotropic effects") that contribute to the positive effect of statins on the incidence of cardiovascular events. The coagulation and fibrinolytic systems are two separate but reciprocally linked enzyme cascades that regulate the formation and breakdown of fibrin. Numerous studies have demonstrated that disturbances of coagulation and fibrinolysis contribute to the development and progression of atherosclerosis, and that they affect the incidence of atherosclerosis-related clinical events. High plasma levels or activities of fibrinogen, factor VII, factor VIII, von Willebrand factor (vWF), soluble thrombomodulin, tissue plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) are thought to be associated with increased morbidity and mortality related to cardiovascular disease. Experimental studies and many clinical studies have recently shown that statins produce favourable effects on haemostatic parameters, including those that are risk factors for cardiovascular disease. Statins diminish procoagulant activity, which is observed at different stages of the coagulation cascade, including tissue factor (TF) activity, conversion of prothrombin to thrombin and thrombin activity. In some studies, statins also reduced fibrinogen levels. By altering the levels and activities of tPA and PAI-1, statins seem to stimulate fibrinolysis. The data on the effects of combined treatment with statins and other drugs on haemostasis are rather limited. They suggest that statins combined with fibric acid derivatives, omega-3 fatty acids and 17beta-estradiol are superior to statins alone. The only two clinical studies performed in patients with acute coronary syndromes showed a relatively weak effect of statins on haemostasis in those patients. Although various statins may produce different effects on individual variables, there are no convincing data showing that differences in their physicochemical and pharmacokinetic properties significantly alter their net effect on excessive procoagulant activity. Apart from the lipid-lowering effect, statins suppress the synthesis of several important nonsterol isoprenoids derived from the mevalonate pathway, especially farnesyl and geranylgeranyl pyrophosphates, which via enhanced protein prenylation, are involved in the regulation of many cellular processes. It is presumed that the inhibitory effect of statins on the mevalonate pathway is involved in the regulation of some key steps of coagulation and fibrinolysis processes. In this way they probably regulate the synthesis of TF, tPA and PAI-1, and perhaps they also control the generation and activity of thrombin. The beneficial effects of statins on coagulation and fibrinolysis may be responsible for their ability to decrease the number of cardiovascular events. The lipid-independent effects of statins on haemostasis may contribute to the marked decrease in the incidence rates of mortality, hospitalisation and revascularisation in patients treated with these drugs.

The role of statins in vascular disease

BACKGROUND

Recent publications have highlighted the benefits of statins in non-cardiac occlusive disease but also the failure of vascular surgeons to recognise and treat the risk factors for atherosclerosis, in particular hypercholesterolaemia. The aim of this review is to clarify the current experimental and clinical evidence for the use of statins in vascular disease.

METHODS

Literature compiled from an extensive search of Medline and the Cochrane database has been used for the basis of this review.

RESULTS

Experimental and clinical evidence consistently reports that statins improve endothelial dysfunction, are anti-inflammatory, anti-proliferative, anti-thrombogenic and anti-proteolytic. These effects are known to inhibit atherogenesis and improve plaque stability. Independent groups support the use of statins in the prevention of both primary and secondary cardiac events. The National Stroke association recommends their use to reduce strokes following myocardial infarction and the Heart Protection Study reports benefits in patients with non-cardiac occlusive disease.

CONCLUSIONS

There is substantial evidence advocating the use of statins in patients with clinically significant vascular disease. In the future this may evolve to include those patients at risk from neointimal hyperplasia, aneurysmal disease and ischaemia reperfusion injury.

[Non-lipid effects of statins: myth or fact?]

Hydroxy-methylglutaryl coenzyme A reductase-inhibitors (HMG-CoA [statins]) are currently the most effective method to pharmacologically decrease total plasma cholesterol levels. A number of multicenter studies have demonstrated, that statins administered for several years lead to a significant reduction of cardiovascular events and mortality compared with placebo. Apart from the well known LDL- and cholesterol lowering effect, statins have been postulated to exert beneficial effects on mortality due to so called 'non-lipid effects'. There is circumstantial evidence from a number of experimental studies that statins can improve endothelial function, exert anti-inflammatory and anti-oxidative effects, stabilize arteriosclerotic plaque and inhibit proliferation and activation of smooth muscle cells. However, the clinical implications of these beneficial 'non-lipid effects' are unclear, but appear to exert only a minor role in comparison to the lowering effect of statins on total plasma cholesterol levels.

Statins in coronary bypass surgery: rationale and clinical use

Statin therapy prevents the first occurrence and recurrence of coronary events and reduces cardiovascular and general mortality in patients with coronary artery disease. These compounds modulate a variety of processes involved in the pathophysiology of arteriosclerosis and vascular graft disease by lipid-dependent and lipid-independent (pleiotropic) mechanisms. As a result, statins produce angiographic and clinical benefits in patients undergoing coronary bypass surgery. We review the present knowledge about the effects of statins on this pathologic condition and the evidence supporting an early treatment initiation.

Statins increase thrombomodulin expression and function in human endothelial cells by a nitric oxide-dependent mechanism and counteract tumor necrosis factor alpha-induced thrombomodulin downregulation

Expression of functionally active thrombomodulin (TM) on the luminal surface of endothelial cells is critical for vascular thromboresistance. TM maintains thrombohemorrhagic homeostasis by forming a complex with thrombin, which subsequently loses its procoagulant properties and instead activates protein C. Acquired deficiency of endothelial TM is of particular pathophysiological significance in sepsis and related disorders. We show here that two different 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins), atorvastatin and simvastatin, strongly increase the expression and functional activity of TM in human umbilical vein endothelial cells, human coronary artery endothelial cells, and EA.hy926 endothelial cells. The increase in endothelial TM conferred by statin was prevented by the addition of mevalonic acid, geranylgeranyl-pyrophosphate, and nitric oxide scavenger, and was mimicked by the addition of a specific inhibitor of geranylgeranyl transferase, as well as by nitric oxide donors. Moreover, statin counteracted tumor necrosis factor alpha-induced downregulation of endothelial cell TM. The increase in endothelial cell TM activity in response to statin constitutes a novel pleiotropic (non-lipid-related) effect of these commonly used compounds, and may be of clinical significance in disorders where deficient endothelial TM and protein C activation play a pathophysiological role.

Pitavastatin alters the expression of thrombotic and fibrinolytic proteins in human vascular cells

In addition to lowering blood lipids, clinical benefits of 3-hydroxy-3-methylglutaryl coenzyme A (HMG Co-A; EC 1.1.1.34) reductase inhibitors may derive from altered vascular function favoring fibrinolysis over thrombosis. We examined effects of pitavastatin (NK-104), a relatively novel and long acting statin, on expression of tissue factor (TF) in human monocytes (U-937), plasminogen activator inhibitor-1 (PAI-1), and tissue-type plasminogen activator (t-PA) in human aortic smooth muscle cells (SMC) and human umbilical vein endothelial cells (HUVEC). In monocytes, pitavastatin reduced expression of TF protein induced by lipopolysaccharide (LPS) and oxidized low-density lipoprotein (OxLDL). Similarly, pitavastatin also reduced expression of TF mRNA induced by LPS. Pitavastatin reduced PAI-1 antigen released from HUVEC under basal, OxLDL-, or tumor necrosis factor-alpha (TNF-alpha)-stimulated conditions. Reductions of PAI-1 mRNA expression correlated with decreased PAI-1 antigen secretion and PAI-1 activity as assessed by fibrin-agarose zymography. In addition, pitavastatin decreased PAI-1 antigen released from OxLDL-treated and untreated SMC. Conversely, pitavastatin enhanced t-PA mRNA expression and t-PA antigen secretion in untreated OxLDL-, and TNF-alpha-treated HUVEC and untreated SMC. Finally, pitavastatin increased t-PA activity as assessed by fibrin-agarose zymography. Our findings demonstrate that pitavastatin may alter arterial homeostasis favoring fibrinolysis over thrombosis, thereby reducing risk for thrombi at sites of unstable plaques.

HMG-CoA reductase inhibitors inhibit inducible nitric oxide synthase gene expression in macrophages

The 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors, statins, are potent inhibitors of cholesterol synthesis and have wide therapeutic use in cardiovascular diseases. Recent evidence, however, suggests that the beneficial effects of statins may extend beyond their action on serum cholesterol levels. In this study, we investigated the effects of lovastatin, pravastatin, atorvastatin and fluvastatin on macrophage formation of nitric oxide (NO) in murine RAW 264.7 cells. Stimulation of macrophages with lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma) resulted in inducible NO synthase (iNOS) expression, which was accompanied by a large amount of NO formation. At concentrations of 0.1-30 microM, statins can inhibit stimuli-induced NO formation and iNOS induction to different extents. This inhibition occurs at the transcriptional level, and displays potency in the order of lovastatin > atorvastatin > fluvastatin >> pravastatin. We found that LPS-induced I kappa B kinase and nuclear factor-kappa B (NF-kappa B) activation, as well as IFN-gamma-induced signal transducer and activator of transcription 1 (STAT1) phosphorylation, were reduced by lovastatin. Moreover, inhibition by lovastatin of NO production and kappa B activation was reversed by mevalonate, geranylgeranyl pyrophosphate and farnesyl pyrophosphate. All these results suggest that inhibition of iNOS gene expression by statins can be attributed to interference with protein isoprenylation, which mediates both NF-kappa B and STAT1 activation in the upstream signaling pathways for iNOS gene transcription.

Early vascular benefits of statin therapy

Large-scale trials established that statin administration in hypercholesterolaemic individuals and patients with coronary heart disease (CHD) significantly reduces the risk of vascular events and death. This benefit was primarily attributed to their actions on lipids. This review focuses on the benefits (clinical and experimental) of statins observed soon (approximately 12 weeks) after their administration. Statins rapidly increase nitric oxide production and improve endothelial function (e.g. increased flow-mediated dilatation). Similarly, antioxidant properties decrease the susceptibility of low density lipoprotein cholesterol to oxidation. Statins inhibit the migration of macrophages and smooth muscle cell proliferation leading to an antiproliferative effect and the stabilisation of atherosclerotic plaques. Anti-inflammatory effects include a reduction in serum C-reactive protein levels, inflammatory and proinflammatory cytokines (e.g. IL-6, IL-8), adhesion molecules (e.g. ICAM-1, VCAM-1) and other acute phase proteins. Statins influence the haemostatic system. They reduce tissue factor expression and platelet activity, whereas fibrinolysis can be enhanced. Statins improve microalbuminuria, renal function, hypertension and arterial wall stiffness. A significant reduction of the carotid intima media thickness (IMT) was also reported early after statin treatment. These early effects of statins probably contribute to the significant reduction in vascular events seen in some 'short-term' studies. There is a need to further elucidate the rapid and non-lipid lowering properties of statins.

Cerivastatin, a HMG-CoA reductase inhibitor, reduces plasminogen activator inhibitor-1 (PAI-1) expression in endothelial cells by down-regulation of cellular signaling and the inhibition of PAI-1 promoter activity

Statins, which competitively inhibit 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase activity and reduce mevalonate synthesis, are believed to exert a plethora of pleiotropic effects. In this report, molecular mechanisms of the inhibitory effect on plasminogen activator inhibitor type 1 (PAI-1) expression produced by cerivastatin (CRV), the most active compound in this class, were studied using monocultures of human endothelial cell line (EA.hy 926). CRV similar to another statin, lovastatin (LOV), significantly inhibited PAI-1 expression and its release from endothelial cells, nonstimulated and stimulated with TNF-alpha. The inhibitory effect of CRV could be detected at the level of PAI-1 promoter in EA.hy 926 cells transfected with plasmid p800 LUC containing PAI-1 promoter fragment (+71 to -800), as well as at the level of PAI-1 mRNA. The PAI-1 promoter activity was markedly suppressed in the nonstimulated cells and almost completely inhibited in TNF-alpha-stimulated cells. In addition, CRV at low doses (IC(50) of 4 - 6 microM) significantly inhibited mitogen-activated protein kinases (MAPKs) phosphorylation. The majority of inhibitory effects occurred at significantly lower concentrations for CRV compared to LOV. The mechanism by which CRV inhibits PAI-1 expression appears to be directly associated with geranylgeranylation of some cell proteins, since the inhibitory effect on PAI-1 expression can be reversed by geranylgeranyl-pyrophosphate but not by farnesyl-pyrophosphate.

Anti-inflammatory and immunomodulating properties of statins. An additional tool for the therapeutic approach of systemic autoimmune diseases?

Cardiovascular diseases secondary to accelerated atherosclerosis are now accepted as a cause of mortality and morbidity in patients suffering from systemic lupus erythematosus and rheumatoid arthritis. More recently, atherosclerosis is emerging as one of the most serious complications in the anti-phospholipid syndrome, although large epidemiological studies, such as those performed in lupus and rheumatoid arthritis patients, have not been performed up to now. Classical risk factors (dislipidemia, hypertension, diabetes, smoking, etc.) and steroid therapy cannot completely explain the high prevalence of cardiovascular complications in systemic autoimmune diseases. Since the modern view defines atherosclerosis as a chronic inflammatory disorder, it has been suggested that systemic inflammation and soluble immune mediators (circulating autoantibodies, immune-complexes, complement activation products) might play a role in accelerating vessel pathology. The main target appears to be the endothelium because of its ability to switch to a pro-adhesive, pro-inflammatory and pro-coagulant surface in response to these mediators. Recent advances in the knowledge of the pharmacology of statins have indicated that these drugs rather than to be simple cholesterol lowering molecules display a pleiotropic effects on several mechanisms involved in the atherosclerotic plaque formation. Their anti-inflammatory activity and particularly their ability to downregulate endothelial cell activation induced by different stimuli strongly suggest their possible use in conditions in which the systemic inflammation and the endothelial activation/damage are thought to represent key pathogenic mechanisms.

Plasminogen activator inhibitor-1: physiologic role, regulation, and the influence of common pharmacologic agents

Plasminogen activator inhibitor-1 (PAI-1) is the major inhibitor of endogenous thrombolysis, thereby promoting thrombosis. PAI-1 is also a primary contributor to the development and recurrence of acute myocardial infarction. The renin angiotensin system, hypertriglyceridemia, hyperglycemia and hyperinsulinemia, and estrogen all influence the fibrinolytic system and PAI-1 in particular. Available data strongly suggest that angiotensin-converting enzyme (ACE) inhibitors and hormone replacement therapy with estrogen beneficially reduce PAI-1 production. Metformin, an agent commonly used for non-insulin-dependent diabetes mellitus (NIDDM), appears to favorably decrease PAI-1 production in NIDDM patients but not nondiabetic patients. Among the cholesterol-lowering statins, clinical literature evaluating pravastatin provides the most compelling data to support this agent's favorable effect on PAI-1. Other available statins either have not displayed an effect on PAI-1 or do not have clear data to conclusively define their effects on the fibrinolytic system.