Pleiotropic effects of statins and related pharmacological experimental approaches

Statins, the most widely prescribed cholesterol-lowering drugs, are considered to be first-line therapeutics for the prevention of coronary heart disease and atherosclerosis. Statins act by inhibiting the enzyme 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase, the rate-limiting enzyme in endogenous cholesterol biosynthesis, which catalyzes the reduction of HMG-CoA to mevalonic acid. Inhibition of this enzyme has proven to be effective for lowering plasma total cholesterol, low-density lipoprotein-cholesterol, and triglyceride levels in humans and can therefore be useful to treat atherosclerotic and dyslipidemic disorders. However, the clinical benefits of statins appear to extend beyond their lipid-lowering effects. Besides reducing cholesterol biosynthesis, inhibition of mevalonate by statins also leads to a reduction in the synthesis of important intermediates, such as the isoprenoids farnesyl pyrophosphate and geranylgeranyl pyrophosphate. These intermediates are involved in the posttranslational prenylation of several proteins (e.g., Ras, Rho, Rac) that modulate a variety of cellular processes including cellular signaling, differentiation, and proliferation. Given the central role of these isoprenylated proteins in endothelial function, atherosclerotic plaque stability, platelet activity, coagulation, oxidation, and inflammatory and immunologic responses, it could be anticipated that these compounds may exert multiple beneficial effects in a broad spectrum of disorders including cardiovascular disease, osteoporosis, Alzheimer's disease and related vascular dementia, viral and bacterial infection, etc. This article summarizes these cholesterol-lowering-independent effects of statins, termed "pleiotropic effects", and the underlying mechanisms, as well as the preclinical experimental approaches that would be useful to evaluate the effects of statins.     

Endothelial dysfunction, oxidative stress and inflammation in atherosclerosis: beneficial effects of statins

Atherosclerosis and its complications represent the major cause of death in developed countries. Statins are inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A [HMGCoA] reductase and consequently inhibitors of cholesterol biosynthesis. Statins have been described as the most potent class of drugs to reduce serum cholesterol levels. In clinical trials, statins are beneficial in primary and secondary prevention of coronary heart disease. Statins, were initially designed as cholesterol-lowering drugs. However, these drugs, besides their lipid-lowering properties, exert a number of protective effects on the cardiovascular system that emerged over the past years. The benefits observed with statin treatment appear to be greater than that might be expected from reduction in lipid levels alone, suggesting effects beyond cholesterol lowering. These cholesterol-independent effects have been called "pleiotropic". The cholesterol-independent or "pleiotropic" effects of statins involve improvement of endothelial function, stability of atherosclerotic plaques, decrease of oxidative stress and inflammation, and inhibition of thrombogenic response. These pleiotropic effects of statins have been proposed as key properties of these drugs to reduce cardiovascular morbidity and mortality. The present review will emphasize the molecular mechanisms underlying the effects of statins on endothelial function and oxidative stress. In particular, inhibition of small GTP-binding proteins, Rho, Ras and Rac, which are regulated by isoprenoids [farnesyl pyrophosphate and geranylgeranyl pyrophosphate], seems to play an important role in mediating the pleiotropic effects of statins.     

Antioxidant effects of statins

Statins, a group of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, are widely used in clinical practice for their efficacy in producing significant reductions in plasma cholesterol and LDL cholesterol and in reducing morbidity and mortality from cardiovascular disease. However, several large clinical trials have suggested that the cholesterol-lowering effects of statins may not completely account for the reduced incidence of cardiovascular disease seen in patients receiving statin therapy. A number of recent reports have shown that statins may also have important antiinflammatory effects, in addition to their effects on plasma lipids. Since inflammation is closely linked to the production of reactive oxygen species (ROS), the molecular basis of the observed antiinflammatory effects of statins may relate to their ability block the production and/or activity of ROS. In this review, we will discuss both the inhibition of ROS generation by statins, through interference with NAD(P)H oxidase expression and activity, and the actions of statins that serve to blunt the damaging effects of these radicals, including effects on antioxidant enzymes, lipid peroxidation, LDL cholesterol oxidation and nitric oxide synthase. These antioxidant effects of statins likely contribute to their clinical efficacy in treating cardiovascular disease as well as other chronic conditions associated with increased oxidative stress in humans.     

Cholesterol-independent effects of statins in inflammation, immunomodulation and atherosclerosis

Atherosclerosis and its complications still represent the major cause of death in developed countries. Statins have revolutionized the treatment of dyslipidemia and demonstrated their ability to reduce and prevent coronary morbidity and mortality. Statins inhibit 3-hydroxyl-3-methylglutaryl coenzyme A (HMG-CoA) reductase, an enzyme crucial to cholesterol synthesis. The effectiveness and rapidity of statin-induced decreases in coronary events led to the speculation that statins possess cholesterol-independent effects. Since mevalonate produced by the HMG-CoA reductase is not only the precursor of cholesterol, but also of non steroidal isoprenoid compounds, such as the farnesyl pyrophosphate and the geranylgeranyl pyrophosphate, statins also regulate the small signaling proteins, Ras and Rho. Thus, inhibition of these prenylated proteins might account for the non-lipid lowering effects of statins. In this review, we describe the numerous beneficial pleiotropic effects of statins that could modulate atherogenesis.     

Statins and angiogenesis in non-cardiovascular diseases

Statins inhibit HMG-CoA reductase by competitively inhibiting the active site of the enzyme, thus preventing cholesterol synthesis and reducing the risk of developing cardiovascular disease. Many pleiotropic effects of statins have been demonstrated that can be either related or unrelated to their cholesterol-lowering ability. Among these effects are their proangiogenic and antiangiogenic properties that could offer new therapeutic applications. In this regard, pro- and anti-angiogenic properties of statins have been shown to be dose dependent. Statins also appear to have a variety of non-cardiovascular angiogenic effects in many diseases, some examples being ocular disease, brain disease, cancer, preeclampsia, diabetes and bone disease, which are discussed in this review using reports from in vitro and in vivo investigations.     

Modulation of the inflammatory process by statins

Statins reduce cholesterol levels through competitive inhibition of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, the key enzyme that regulates cholesterol synthesis. The cholesterol-lowering effect of statins is also due to an increase in the uptake of cholesterol by cells as a result of intracellular cholesterol depletion and enhanced expression of low-density lipoprotein (LDL) receptors. The use of statins as lipid-lowering agents has lead to remarkable changes in the treatment and prevention of ischemic heart disease. Results of large clinical trials of patients with ischemic heart disease have demonstrated that statins reduce inflammatory markers such as C-reactive protein, an independent risk factor in the disease. Statins exhibit properties that are beyond their lipid-lowering effects. These non-lipid-lowering properties involve the inhibition of the isoprenoid pathway through decreased synthesis of many nonsteroidal isoprenoid compounds. The focus on the immunomodulatory effect of statins is the result of the positive outcome of pravastatin treatment in cardiac transplantation patients, as well as angiographic regression studies showing insignificant changes in the degree of coronary stenosis despite a large reduction in cardiac events. Statin treatment reduces the risk of ischemic stroke despite the fact that LDL cholesterol is not directly associated with the risk of stroke. This observation lead to the investigation of the role of statins in inflammation and the immune system. Recent research data demonstrated that statins inhibit the induction of the major histocompatibility (MHC) class II expression by interferon-gamma (IFN-gamma), leading to repression of MHC II-mediated T-cell activation. Furthermore, statins inhibit the expression of specific cell surface receptors on monocytes, adhesion molecules and also integrin-dependent leucocyte adhesion. While statins may stimulate the secretion of caspase-1, IL-1beta and IL-18 in peripheral mononuclear cells in response to Mycobacterium tuberculosis, they exhibit additional effects on inflammation by decreasing IL-6 synthesis in human vascular smooth muscle cells (VSMC) in vitro. The focus of this monograph is to highlight the role of statins in the modulation of the immune system and inflammatory processes.     

不同基因多态性对他汀类药物影响的研究进展

他汀类药物是目前临床应用最广泛的降脂药物,为心血管疾病的一级、二级预防的基石。他汀类药物为羟基-甲基戊二酰辅酶A还原酶抑制剂,可以显著降低血清总胆固醇、低密度脂蛋白胆固醇、三酰甘油水平,同时可轻度升高高密度脂蛋白胆固醇水平。目前研究的参与他汀类药物代谢的酶、转运蛋白、受体等基因多态性对他汀类药物安全性、不良反应有重要影响。阐述遗传因素载脂蛋白E、SLCO1B1、ATP结合盒转运蛋白B1、ABCG2、CYP、3-羟基-3-甲基戊二酰辅酶A还原酶基因等相关基因多态性对他汀类药物疗效和安全性的影响,为他汀类药物的个体化用药提供参考依据。     

Telomere/Telomerase system: a new target of statins pleiotropic effect?

Statins are well established drugs for primary and secondary prevention of coronary artery disease (CAD). Despite the well-known ability of statins to lower cholesterol, it is now clear that clinical benefits are also substantially higher than expected and several clinical trials, like JUPITER (Justification for the Use of Statins in Primary Prevention: An Intervention Trial Evaluating Rosuvastatin trial) have indicated that such clinical effects are independent of cholesterol reduction. These cholesterol-independent actions have been named "pleiotropic effects" and include: anti-oxidation and anti-inflammatory effects, modulation of immune activation, stabilization of atherosclerotic plaque, decreased platelet activation, inhibition of cardiac hypertrophy, reduction of cytokine-mediated vascular smooth muscle cell (VSMC) proliferation and improvement of endothelial function. Recently, additional pleiotropic effects of statins on "cellular senescence" have been seen in different cell types, including endothelial progenitor cells (EPC), endothelial cells (EC), VSMC and chondrocytes. At the molecular level, the effect of statins on cellular senescence could be mediated by their interaction with the telomere/telomerase system. Recent evidence suggests that the anti-aging effects of statins are linked to their ability to inhibit telomere shortening by reducing either directly and indirectly oxidative telomeric DNA damage, as well as by a telomere capping proteins dependent mechanism. In this review, we discuss the pleiotropic effects of statins, focusing on the telomere/telomerase system. We will also present our current findings regarding leukocyte telomere length in very old people with myocardial infarction on statin therapy.     

Statins for diabetic cardiovascular complications

The prevalence of diabetes mellitus (DM), particularly Type 2 DM, has rapidly increased in industrialized and many developing countries. The predominant cause of death in diabetic patients is vascular complications. Dyslipidemia and hypercholesterolemia are common in diabetic patients. 3-Hydroxy-3-methylglutaryl-CoA reductase inhibitors (statins) were designed for lowering cholesterol synthesis. Landmark clinical trials indicated that statins effectively reduced cardiac death and events in patients with coronary artery disease or DM. The benefits of statins on the prevention of vascular events were independent from age, sex or baseline lipid levels in diabetic patients. Statins not only prevent atherosclerotic macrovascular complications, but also postpone the development of microvascular complications of DM, such as nephropathy and retinopathy. The non-cholesterol lowering or pleiotropic effects of statins have attracted vast attention. Results from experimental and clinical studies suggest that statins may attenuate inflammation, oxidative stress, coagulation, platelet aggregation, and improve insulin resistance, fibrinolysis and endothelial functions and help to prevent thrombosis, restenosis or organ transplantation rejection. Statins may affect the intracellular prenylation of proteins, which modulate the activity of small-GTP binding proteins. This may be an underlying mechanism for some pleiotropic effects of statins. Statins have an excellent safety profile and seldom cause adverse effects. Increasing evidence suggests that statins are the current treatment of choice to prevent vascular complications in diabetic patients with hypercholesterolemia.     

Benefits of statins in cerebrovascular disease

Although elevated cholesterol levels have been associated with coronary heart disease, the evidence for a role of cholesterol in stroke is less well defined. Epidemiological studies indicate that high lipid levels are linked with an increase in ischemic stroke, while low lipid levels may increase the risk of hemorrhagic stroke. Lipid lowering with statins reduces the incidence of ischemic stroke without increasing the frequency of hemorrhagic stroke. The benefits of statins on stroke may be due to a combination of mechanisms. Statins lower cholesterol levels and reduce the progression of atherosclerotic plaque formation in carotid arteries, and the incidence of emboli from cardiac, aortic and carotid sites. Furthermore, statins may produce cholesterol-independent effects such as improving cerebral blood flow and reducing inflammation and oxidative stress, which could limit the size of an ischemic lesion. Statins offer potential benefits for reducing the incidence and improving the prognosis of stroke.     

Perspectives on the cardioprotective effects of statins

Statins are inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase), the rate-limiting enzyme of cholesterol synthesis. In recent years, statins have become the major choice of treatment for hypercholesterolemia. Emerging evidence from both animal and human studies indicates that mechanisms independent of cholesterol lowering effects contribute to the observed clinical benefits of statins. The anti-hypertrophy effect of statins on the cardiac tissue represents one of such mechanisms. The beneficial effects of statins on cardiac hypertrophy and cardioprotection may be attributed to their functional influences on small G proteins such as Ras and Rho, resulting in an increase of endogenous nitric oxide (NO), reduction of oxidative stress, inhibition of inflammatory reaction, and decrease of the renin-angiotensin system activity as well as C-reactive protein (CRP) levels in cardiac tissues. Recent findings from in vitro and in vivo studies of statins on cardioprotective effects are summarized in this review. The unveiled novel mechanisms support the use of statins as the new mainstay therapeutic agents for various cardiovascular diseases and complications.     

To cardiovascular disease and beyond: new therapeutic perspectives of statins in autoimmune diseases and cancer

Statins have been successfully used in patients with hypercholesterolemia and cardiovascular diseases, but there is increasing evidence that they exert effects by much exceeding the lowering of cholesterol levels. Statins have antiatherosclerotic, antiinflammatory, antioxidant, immunomodulatory and antithrombotic effects. These "pleiotropic" effects stem from their inhibition of prenylation of the small GTP-binding proteins Ras and Rho, and to the disruption, or depletion, of cholesterol rich membrane micro-domains (membrane rafts). Through these pathways statins modulate immune responses by altering cytokine levels and by affecting the function of cells involved in both innate and adaptive responses. Anti-inflammatory and immunosuppressory properties of statins provide the rationale for their potential application in conditions in which the inflammation and immune response represent key pathogenic mechanisms, such as antiphospholipid syndrome, rheumatoid arthritis and systemic lupus erythematosus. Reduction of atherosclerosis progression in autoimmunity is also a very important effect. Statins pathways of action in systemic autoimmune diseases, and their potential therapeutic use are discussed in this review. The inhibition of mevalonate pathway by statins impairs modification of Ras and Rho GTPases, which play key roles in signaling pathways related to tumor formation, metastasis and cell death. There is experimental and clinical evidence that statins may improve the therapeutic outcome of anticancer drugs. Thus, this review will also discuss recent insights into the molecular mechanisms underlying the anticancer effects of statins and their assessment as promising candidates for inclusion into current therapeutic regimens for the treatment of malignant diseases.     

Lipid and non-lipid effects of statins

Long- and short-term trials with the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) have demonstrated significant reductions in cardiovascular events in patients with and without history of coronary heart disease. Statins are well-established low-density lipoprotein (LDL)-lowering agents, but their clinical benefit is believed to result from a number of lipid and non-lipid effects beyond LDL lowering, including a rise in plasma high-density lipoprotein levels. Beyond improving the lipid profile, statins have additional non-lipid effects including benefit on endothelial function, inflammatory mediators, intima-media thickening, prothombotic factors that ultimately result in plaque stabilization. These effects arise through the inhibition of several mevalonate-derived metabolites other than cholesterol itself, which are involved in the control of different cellular functions. Although statins represent the gold standard in the prevention and treatment of coronary heart disease, combination therapy with other lipid-lowering drugs, as well as novel therapeutic indications, may increase their therapeutic potential.     

他汀类药物的安全性风险评价

他汀类药物是最广泛的可用药物治疗降低胆固醇水平,并控制其发展的处方药。所有的他汀类药物,如阿托伐他汀、氟伐他汀、洛伐他汀、匹伐他汀、普伐他汀、瑞舒伐他汀和辛伐他汀可用于心血管疾病事件的预防。众所周知,在治疗过程中一些服用他汀类药物的患者出现不良反应,如肝损害、癌症的风险和骨骼肌损害。因此,认识他汀类药物的安全性风险是很重要的。根据发表的他汀类药物的临床研究文献数据,分析和认识这类药物的安全性、不良反应及毒性的风险,并简要介绍了由美国心脏协会和美国心脏病学院基于4年评述而制定的2013年他汀类降胆固醇药物新使用指南。     

Non-lipid effects of statins: emerging new indications

Statins are beneficial both in the primary and secondary prevention of atherosclerotic vascular disease and acute events in a broad spectrum of patient subgroups. However, the observed clinical benefit with statin therapy is much greater than expected through the reduction of cholesterol levels alone. Clinical and experimental studies suggested that several antiatherosclerotic effects other than lipid lowering also contribute to the observed benefit of statin therapy. These 'pleiotropic effects' include improvement of endothelial function, antitrombotic actions, plaque stabilization, reduction of the vascular inflammatory process and anti-oxidation. Statins may also exhibit a wide variety of actions other than antiatherosclerotic effects. Recent observational data documented a potential association between statin use and improvement of fracture risk in osteoporosis. Despite the lack of randomized trials, epidemiological and limited clinical data suggested that statins might retard the pathogenesis of Alzheimer's disease. Observational data indicated that the progression of aortic stenosis and valvular calcification might be delayed in statin users. In addition, the deterioration of congestive heart failure may be delayed with statins via anti-inflammatory, vascular endothelial and antiatherosclerotic actions. Furthermore, preliminary clinical studies suggested that, by their immunosuppressive actions statins might reduce the incidence of rejection following organ transplantation. Currently, there is not enough evidence to prescribe therapy for such patients. However, ongoing studies are exploring the role of statin therapy for these new indications. This review will discuss several non-lipid effects of statin therapy currently under investigation.     

Molecular mechanisms of toxicity of simvastatin,widely used cholesterol-lowering drug. A review

Statins are widely used and well tolerated cholesterol-lowering drugs, and when used for therapy purposes reduce morbidity and mortality from coronary heart disease. Simvastatin is one of nine known statins, specific inhibitors of hepatic enzyme 3-hydroxy-3-methylglutaryl-coenzyme A reductase, the rate-limiting step of cholesterol biosynthesis, and is believed to reduce plasma cholesterol levels by decreasing the activity of this enzyme. Statin drugs represent the major improvement in the treatment of hypercholesterolemia that constitutes the main origin of atherosclerosis, leading to coronary heart disease. Although statins are generally safe, minor and severe adverse reactions are well known complications of statin use. Adverse events associated with simvastatin therapy are uncommon, but potentially serious. In this review some details about statins including their adverse effects in humans and animals, the effects of simvastatin on various intracellular and mitochondrial processes, and molecular mechanisms underlying simvastatin cytotoxicity are discussed.     

Defining the Role of High-Dose Statins in PCI

Several studies have reported a significant reduction in morbidity and mortality in patients with acute coronary syndrome (ACS) or in patients with stable ischemic heart disease with the use of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins). Based on these findings, current guidelines recommend the use of statin therapy before hospital discharge for all patients with ACS regardless of the baseline low-density lipoprotein level. Statins are also recommended to patients at high risk for cardiovascular disease. Statins have been introduced in the clinical arena to reduce the low-density lipoprotein (LDL) cholesterol level that is associated with coronary atherosclerosis; however, a growing body of evidence suggests that other mechanisms of action beyond the modification of the lipid profile may come into action. In particular, statins exert antiinflammatory effects, modulate endothelial function, and inhibit the thrombotic signaling cascade. All together the non-LDL cholesterol-lowering effects of statins are called pleiotropic effects. In this article we will review the evidence supporting the use of high-dose statins in patients undergoing percutaneous coronary intervention, and we will also attempt to highlight the possible mechanisms of action.     

Ezetimibe and vascular endothelial function

Hypercholesterolemia is a major risk factor for cardiovascular diseases that has been managed mostly with 3-hydroxy-3-methyl glutaryl coenzyme A reductase inhibitors (statins) that suppress de novo cholesterol synthesis in the liver. Statins also have beneficial pleiotropic effects on the atherosclerotic process that are independent of their ability to lower lipid values. However, the levels of low-density lipoprotein cholesterol (LDL-C) in most hypercholesterolemic patients at high risk for cardiovascular disease do not reach the goals proposed by guidelines even when prescribed with statins. Ezetimibe is a new lipid-lowering agent that blocks the intestinal absorption of dietary and biliary cholesterol and reduces LDL-C levels, especially when combined with statins. However, its effect on cardiovascular events remains unknown. We reviewed the effects of ezetimibe on cardiovascular diseases, in particular, vascular endothelial function, which is initially impaired during the atherogenetic process and is an important predictor of cardiovascular events. The simultaneous inhibition of cholesterol synthesis by statin and of cholesterol absorption by ezetimibe might retard the atherogenetic process. These effects are considered to be mainly mediated by lipid lowering. However, further studies should elucidate the mechanism of the anti-atherosclerotic effects induced by ezetimibe; for instance, whether or not it directly affects atherogenesis independently from its lipid-lowering effects.     

Plant sterols and their role in combined use with statins for lipid lowering

Cardiovascular disease (CVD) is currently one of the major contributors to the global burden of disease. Combination treatments to promote a maximal reduction of the ratio between total cholesterol and high-density lipoprotein are currently the most effective way of preventing CVD. In this review, we assess the role of plant sterols and statins in CVD prevention. Statins have been used by millions of patients at high to moderate risk of CVD, while plant sterols are potentially available to whole populations in food products. The benefits and risks of each compound, as well as the combination, are discussed.     

Emerging indications for statins: a pluripotent family of agents with several potential applications

Statins are pluripotent agents exhibiting multiple non-lipid-lowering actions. Besides their established role in the management of hypercholesterolemia, statins may also have beneficial actions in other pathological conditions, namely: a) osteoporosis and osteoporosis-related bone fractures, b) cancer, c) solid organ transplantation, d) cerebrovascular events (transient ischemic attack and stroke episodes), e) various neurological disorders, such as Alzheimer's disease, Parkinson's disease and multiple sclerosis, f) cardiac arrhythmias and heart failure, g) renal diseases, h) rheumatoid arthritis, i) autoimmune diseases, j) sepsis, and k) allergic asthma. We reviewed the literature searching for studies that support or oppose the use of statins in each proposed indication. In some of these emerging indications, a role for statin treatment is more firmly set; for others, current evidence is more controversial. Future trials may reveal more convincing evidence that will make statin use necessary in the therapeutic management of several diseases.