Statins Inhibit Leukocyte Recruitment

The outcomes of statin therapy in patients with acute ischemic stroke in Taiwan: a nationwide epidemiologic study

BACKGROUND

Acute stroke is the third leading cause of death in Taiwan. Although statin therapy is widely recommended for stroke prevention, little is known about the epidemiology of statin therapy after acute ischemic stroke (AIS) in Taiwan. To investigate the effects of statin therapy on recurrent stroke, intracranial hemorrhage (ICH), coronary artery disease (CAD), cost of hospitalization and mortality, we conducted a nationwide population-based epidemiologic study.

METHODS

Cases of AIS were identified from the annual hospitalization discharge diagnoses of the National Health Insurance Research Database with the corresponding International Classification of Diseases, ninth revision codes from January 2001 to December 2010. We divided the AIS patients into three groups: non-statin, pre-stroke statin and post-stroke statin.

RESULTS

A total of 422 671 patients with AIS (including 365 419 cases in the non-statin group, 22 716 cases in the pre-stroke statin group and 34 536 cases in the post-stroke statin group) were identified. When compared to the non-statin group, both statin groups had a lower recurrent stroke risk [pre-stroke statin: odds ratio (OR) = 0.84; 95% confidence interval (CI) = 0.82-0.87; P < 0.0001; post-stroke statin: OR = 0.89; 95% CI = 0.86-0.91; P < 0.0001], lower ICH risk (pre-statin: OR = 0.75; 95% CI = 0.69-0.82; P < 0.0001; post-stroke statin: OR = 0.75; 95% CI = 0.71-0.81; P < 0.0001), and a lower mortality rate (pre-stroke statin: OR = 0.56; 95% CI = 0.53-0.59; P < 0.0001; post-stroke statin: OR = 0.51; 95% CI = 0.48-0.53; P < 0.0001). In terms of CAD, only the post-statin group had a lower risk (OR = 0.81; 95% CI = 0.79-0.84; P < 0.0001) than the non-statin group. The post-statin group had the lowest 1-year medical costs after index discharge among the three groups.

CONCLUSIONS

Statin therapy reduced the risks of recurrent stroke, CAD, ICH and the first year mortality in patients after AIS. Treatment with statin therapy after AIS is a cost-effective strategy in Taiwan.

Prestroke statins use reduces oxidized low density lipoprotein levels and improves clinical outcomes in patients with atrial fibrillation related acute ischemic stroke

Background

Atrial fibrillation (AF) is a common cause of cerebral infarction, which could lead to endothelial dysfunction, increased reactive oxygen species (ROS) and oxidized low density lipoprotein (Ox-LDL).AF is associated with higher mortality and more severe neurologic disability. Statins may exert neuroprotective effects that are independent of LDL-C lowering. The purpose of our study was to investigate whether prestroke statins use could reduce plasma Ox-LDL levels and improve clinical outcomes in patients with AF-related acute ischemic stroke (AIS).

Methods

This was a multicenter prospective study that involved four medical centers, 242 AIS patients with AF were identified, who underwent a comprehensive clinical investigation and a 72 h-Holter electrocardiogram monitoring. All patients were divided into two groups: prestroke statins use and no prestroke statins use groups, who were followed up for 3 months. Plasma Ox-LDL levels were measured using enzyme-linked immunosorbent assay (ELISA) on admission and at 3 months. The outcome was death, major disability (modified Rankin Scale score ≥ 3), and composite outcome (death/major disability) at 3 months after AIS.

Results

One hundred thirty-six patients were in no prestroke statins use group, and 106 in prestroke statins use group. Plasma Ox-LDL levels were significantly lower in prestroke statins use than in no prestroke statins use on admission and at 3 months (P < 0.001). Plasma Ox-LDL levels on admission were associated with 3-month mortality [adjusted odds ratio (OR), 1.05; 95% confidence interval (CI), 0.99–1.12; P = 0.047]. In fully adjusted models, prestroke statins use was associated with reduced 3-month mortality [adjusted OR, 0.38; 95% CI, 0.16–0.91; P = 0.031)], major disability (adjusted OR, 0.38; 95% CI, 0.15–0.99; P = 0.047), and composite outcome (adjusted OR, 0.31; 95% CI, 0.17–0.74; P = 0.009).

Conclusions

Prestroke statins use can reduce plasma Ox-LDL levels and improve clinical outcomes in patients with AF-related AIS.

Impact of prior statin use on mortality in patients with type 2 diabetes mellitus and bloodstream infection

Objective

This study assessed the effect of prior statin use on the 28-day mortality of patients with type 2 diabetes mellitus (DM) who develop bloodstream infections.

Methods

This retrospective cohort study included all adult type 2 DM patients with bacteremia and verified prior medication history who visited the emergency department of a single tertiary hospital between January 2007 and December 2013. All major adverse consequences including septic shock events, use of mechanical ventilation, intensive care unit admission, and 28-day mortality were assessed.

Results

A total of 1,979 patients were enrolled in the study, of whom 507 were taking statins. Statin users had less severe disease presentation and lower levels of sepsis biomarkers such as bandemia (1.3 ± 3.1 vs 1.8 ± 4.2). After adjustment for confounding variables using a Cox regression model, only older age (adjusted hazard ratio [HR]: 1.04, 95% confidence interval [CI], 1.01–1.04), urinary tract infection (adjusted HR: 0.56, 95% CI, 0.43–0.75), and prior statin use (adjusted HR: 0.58, 95% CI: 0.42–0.85) were significantly associated with 28-day in-hospital mortality.

Conclusion

Prior statin treatment in patients with type 2 DM and bacteremia was associated with a lower 28-day in-hospital mortality rate.

Thiazolidinedione-independent activation of peroxisome proliferator-activated receptor γ is a potential target for diabetic macrovascular complications

Macrovascular complications are responsible for the high morbidity and mortality in patients with diabetes. Peroxisome proliferator‐activated receptor γ (PPARγ) plays a central role in the process of adipocyte differentiation and insulin sensitization, and also possesses anti‐atherogenic effects. Recently, some statins, angiotensin II type 1 receptor blockers and calcium channel blockers have been reported to activate PPARγ. However, the impact of PPARγ activation on diabetic macrovascular complications is not fully understood. It has been reported that the activation of PPARγ by thiazolidinediones induces anti‐atherogenic effects in vascular cells, including monocytes/macrophages, endothelial cells and smooth muscle cells, in atherosclerotic animal models and in clinical studies. We have reported that hydroxymethylglutaryl coenzyme A reductase inhibitors (statins), which are used for treatment of hypercholesterolemia, activate PPARγ and mediate anti‐atherogenic effects through PPARγ activation in macrophages. Also, telmisartan, an angiotensin type I receptor blocker, has been reported to have anti‐atherogenic effects through PPARγ activation. Furthermore, we have reported that nifedipine, a dihydropyridine calcium channel blocker, can activate PPARγ, thereby mediating anti‐atherogenic effects in macrophages. Therefore, statin therapy and part of anti‐hypertensive therapy might produce beneficial effects through PPARγ activation in hypercholesterolemic and/or hypertensive patients with diabetes, and PPARγ might be a therapeutic target for diabetic macrovascular complications. In the present review, we focus on the anti‐atherogenic effects of PPARγ and suggest potential therapeutic approaches to prevent diabetic macrovascular complications. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00182.x, 2012)

[Rheumatoid arthritis. Systemic inflammation and cardiovascular morbidity]

In recent years it could be shown that systemic inflammation, which typically occurs in chronic inflammatory rheumatic diseases, significantly contributes to cardiovascular morbidity and mortality. All rheumatic diseases inherit this enhanced risk for cardiovascular complications with rheumatoid arthritis being one of the most prominent. As the underlying pathophysiological mechanisms are very similar with respect to endothelial damage all rheumatic diseases and specifically rheumatoid arthritis should be monitored and treated with disease-modifying drugs and biological agents as consistently as possible to be able to improve the long-term outcome of affected patients as much as possible.

Ginseng Berry Extract Prevents Atherogenesis via Anti-Inflammatory Action by Upregulating Phase II Gene Expression

Ginseng berry possesses higher ginsenoside content than its root, which has been traditionally used in herbal medicine for many human diseases, including atherosclerosis. We here examined the antiatherogenic effects of the Korean ginseng berry extract (KGBE) and investigated its underlying mechanism of action in vitro and in vivo. Administration of KGBE decreased atherosclerotic lesions, which was inversely correlated with the expression levels of phase II genes to include heme oxygenase-1 (HO-1) and glutamine-cysteine ligase (GCL). Furthermore, KGBE administration suppressed NF-κB-mediated expression of atherogenic inflammatory genes (TNF-α, IL-1β, iNOS, COX-2, ICAM-1, and VCAM-1), without altering serum cholesterol levels, in ApoE^−/− mice fed a high fat-diet. Treatment with KGBE increased phase II gene expression and suppressed lipopolysaccharide-induced reactive oxygen species production, NF-κB activation, and inflammatory gene expression in primary macrophages. Importantly, these cellular events were blocked by selective inhibitors of HO-1 and GCL. In addition, these inhibitors reversed the suppressive effect of KGBE on TNF-α-mediated induction of ICAM-1 and VCAM-1, resulting in decreased interaction between endothelial cells and monocytes. These results suggest that KGBE ameliorates atherosclerosis by inhibiting NF-κB-mediated expression of atherogenic genes via upregulation of phase II enzymes and thus has therapeutic or preventive potential for atherosclerosis.

The association of statin therapy and high-sensitivity C-reactive protein level for predicting clinical outcome in acute non-cardioembolic ischemic stroke

BACKGROUND

Statins reportedly have anti-inflammatory effects aside from their cholesterol-lowering effect. We investigated the effects of statins on serum hs-CRP level and clinical outcome of acute ischemic stroke (IS) patients.

METHODS

This prospective cohort study consequently evaluated patients with acute IS in a single medical center. Serum hs-CRP levels were measured at different time points (within 48 h and 30 days post-stroke). The patients' clinical and laboratory data on admission were analyzed.

RESULTS

Total 100 patients with acute IS were divided in the statin group (n=50) and the non-statin group (n=50). Serum hs-CRP level was similar in the 2 groups within 48 h after acute IS, but was significantly lower in the statin group on Day 30 compared to the non-statin group (p<0.05). The statin group also had favorable 3-month outcome compared to the non-statin group (p<0.05). After adjustments for covariance using stepwise logistic regression, only NIHSS on admission (OR=1.38, 95% CI=1.06-1.80; p=0.02) and hs-CRP in the acute phase (OR=1.74, 95% CI=1.30-2.33; p=0.001) were significantly and independently predictive of 3-month outcome.

CONCLUSION

Statin therapy reduces serum hs-CRP level and may be associated with favorable 3-month outcome in patients after acute IS.

The value of serial plasma nuclear and mitochondrial DNA levels in acute spontaneous intra-cerebral haemorrhage

BACKGROUND

Increased plasma nuclear and mitochondrial DNA levels may be connected to disease severity following spontaneous intra-cerebral haemorrhage (ICH). This study tested the hypothesis that plasma nuclear and mitochondrial DNA levels are substantially increased in acute ICH and can predict treatment outcomes.

METHODS

Serial plasma nuclear and mitochondrial DNA levels were examined in 60 consecutive patients admitted within 24 h after onset of spontaneous ICH and in 60 volunteer control subjects. Additional samples were obtained on days 4, 7, 10, and 14 after onset of ICH regardless of clinical deterioration.

RESULTS

Only plasma nuclear DNA, not plasma mitochondrial DNA, levels in patients with spontaneous ICH significantly correlated with Glasgow Coma Scale (GCS) (r = -0.467, P = 0.001) and ICH volume (r = 0.515, P ≤ 0.001) on presentation. Plasma nuclear DNA levels increased significantly from day 1 to day 7 in patients with poor outcome. Higher plasma nuclear DNA levels (cut-off value >18.7 ng/ml) on presentation were associated with poor outcomes in spontaneous ICH patients.

CONCLUSION

Plasma nuclear DNA levels reflect the severity of cerebral damage such that higher levels are associated with poorer outcome. Plasma nuclear DNA level can be considered a neuropathologic marker of acute spontaneous ICH.

Evaluation of the lipid lowering ability, anti-inflammatory effects and clinical safety of intensive therapy with Zhibitai, a Chinese traditional medicine

OBJECTIVES

To evaluate the lipid lowering ability, anti-inflammatory effects and clinical safety of intensive therapy of the Chinese traditional medicine Zhibitai in subjects with moderate to high cardiovascular risk.

METHODS

A total of 169 subjects (96 males and 73 females, aged 55-72) having moderate to high cardiovascular risk were recruited and randomly divided into Zhibitai group (n=85), which received 480 mg of Zhibitai orally twice daily, and atorvastatin group (n=84), which received 10 mg of atorvastatin orally once a day. Blood lipoproteins, myocardial enzymes, liver and renal functions were measured before treatment started, and after 4 and 8 weeks of the treatment. High sensitivity C-reactive protein (hs-CRP), P-selectin, matrix metalloproteinase-9 (MMP-9) and soluble intercellular adhesion molecule-1 (sICAM-1) were measured before and after the treatment.

RESULTS

Plasma total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) were significantly decreased, and high-density lipoprotein cholesterol (HDL-C) was increased in both groups, after 4 and 8 weeks of treatment (p<0.05 for all pairs). Interestingly, plasma triglycerides (TG) decreased in the Zhibitai group after 4 weeks of treatment but only decreased in the atorvastatin group after 8 weeks. Inflammatory factors such as hs-CRP, P-selectin, MMP-9 and sICAM-1 were significantly decreased in both groups after 8 weeks (p<0.01 for all pairs). Furthermore, there was no difference in myocardial enzymes, hepatic and renal function test parameters, incidence of myopathy or gastrointestinal tract symptoms in either group.

CONCLUSION

Zhibitai therapy is a good alternative to statin therapy to reduce plasma cholesterol levels in subjects with moderate to high cardiovascular risk. Most importantly, Zhibitai is safe to use.

Therapeutic potential of statins in multiple sclerosis: immune modulation, neuroprotection and neurorepair

Statins as inhibitors of 3-hydroxy-3-methyl glutaryl coenzyme A reductase are widely used as cholesterol-lowering drugs. Recent studies provide evidence that the anti-inflammatory activity of statins, which is independent of their cholesterol-lowering effects, may have potential therapeutic implications for neuroinflammatory diseases such as multiple sclerosis (MS), Alzheimer's disease and brain tumors, as well as traumatic spinal cord and brain injuries. Studies with animal models of MS suggest that, in addition to immunomodulatory activities similar to the ones observed with approved MS medications, statin treatment also protects the BBB, protects against neurodegeneration and may also promote neurorepair. Although the initial human studies on statin treatment for MS are encouraging, prospective randomized clinical studies will be required to evaluate their efficacy in the larger patient population.

Statin Therapy for Vascular Failure

There is increasing evidence that statins reduce cardiovascular events such as coronary artery disease or stroke in hypercholesterolemic patients in both primary and secondary prevention. The striking benefit achieved with statin treatments in patients with a wide range of cholesterol levels cannot be attributed to their cholesterol lowering effect alone. Substantial data has recently accumulated showing that statins exert various effects on multiple targets, namely pleiotropic effects, especially targeting the concept of 'vascular failure', including the improvement of vascular endothelial function, inhibition of vascular smooth muscle cell proliferation and migration, anti-inflammatory actions, anti-oxidative effects or stabilization of vulnerable plaques. These effects have potential in the treatments of coronary artery disease in various settings, such as prevention of its onset as well as its progression, or plaque rupture. Statin therapy should be more extensively applied even in normolipidemic patients if there are additional risk factors such as hypertension, diabetes mellitus, or others. Furthermore, statins may be used to intervene in earlier stage risk conditions such as postprandial hyperlipidemia or hyperglycemia, insulin resistant state, masked hypertension, or metabolic syndrome to further reduce mortality or morbidity of coronary artery disease and heart failure.

The effect of aggressive versus conventional lipid-lowering therapy on markers of inflammatory and oxidative stress

Purpose

Recent trial results are in favor of aggressive lipid lowering using high dose statins in patients needing secondary prevention. It is unclear whether these effects are solely due to more extensive lipid lowering or the result of the potentially anti-inflammatory properties of statins. We aimed to determine whether aggressive compared with conventional statin therapy is more effective in reducing systemic markers of inflammation and oxidative stress.

Materials and methods

This was a multi-centre, double-blind, placebo-controlled trial. Patients with previous cardiovascular disease, who did not achieve low density lipoprotein (LDL) cholesterol levels <2.6 mmol/l on conventional statin therapy (simvastatin 40 mg) were randomized to continue with simvastatin 40 mg or to receive atorvastatin 40 mg for 8 weeks and thereafter atorvastatin 80 mg for the final 8 weeks (aggressive treatment). Lipids, C-reactive protein, soluble cellular adhesion molecules, neopterin, von Willebrand Factor, and antibodies against oxidized LDL were measured at baseline and after 16 weeks.

Results

Lipid levels decreased significantly in the aggressive treatment group (LDL-C reduction 20.8%; P < 0.001), whereas a slight increase was observed in the conventional group (LDL-C increase 3.7%; P = 0.037). A significant reduction in antibodies against oxidized LDL was seen in the aggressive (13.4%; P < 0.001) and the conventional (26.8%; P < 0.001) group, but there was no difference between groups (P = 0.25). Furthermore, no significant differences in change in other biomarkers was observed between both groups.

Conclusions

This study does not support the hypothesis that a more profound reduction in inflammatory and oxidative stress contributes to the benefits of aggressive statin therapy.

Simvastatin modulates chemokine and chemokine receptor expression by geranylgeranyl isoprenoid pathway in human endothelial cells and macrophages

OBJECTIVE

Atherosclerosis is a chronic immuno-inflammatory disease involving the recruitment of monocytes and T lymphocytes to the vascular wall of arteries. Chemokines and their receptors, known to induce leukocyte migration, have recently been implicated in atherogenesis. Recent in vitro and in vivo studies have suggested that statins (3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors) have anti-inflammatory properties beyond their lipid-lowering effects. Thus, the aim of the present study was to investigate whether simvastatin reduces the expression of chemokines and chemokine receptors in two major cell types implicated in atherogenesis and to test isoprenoid intermediates involved in their regulation.

METHODS AND RESULTS

We performed in vitro experiments on human vascular endothelial cells and human primary macrophages. First, we have shown by ELISA that 1 microM simvastatin significantly reduced MCP-1 in endothelial cells (ECs) and macrophages stimulated with TNF-alpha or IFN-gamma, respectively. Messenger RNA analysis revealed that expression of the chemokines MCP-1, MIP-1alpha and MIP-1beta, as well as the chemokine receptors CCR1, CCR2, CCR4 and CCR5, was decreased by simvastatin, both in ECs and macrophages. Furthermore, the statin effects were reversed by mevalonate and mimicked by the geranylgeranyl transferase inhibitor (GGTI), whereas the farnesyl transeferase inhibitor (FTI) had no effect. These results suggests that statins act via inhibition of the geranylgeranylation of proteins.

CONCLUSIONS

Our results demonstrate that statins reduce chemokine and chemokine receptor expressions in human ECs and macrophages via inhibition of the geranylgeranylpyrophosphate pathway. Thus, our data provide further evidence that statins have anti-inflammatory properties beyond their lipid-lowering effects. These findings highlight specific novel therapeutic targets for cardiovascular diseases to reduce inflammation mediated by chemokines and their receptors.

Statin therapy is associated with fewer deaths in patients with bacteraemia

OBJECTIVE

Beneficial effects with statin use are increasingly reported in a variety of patient groups. There is in vitro and clinical evidence for its antiinflammatory and immunomodulatory therapeutic roles. We aimed to assess the association between statin administration and mortality in bacteraemic patients.

DESIGN

A retrospective cohort analysis.

SETTING

A 300-bed acute general hospital.

PATIENTS AND PARTICIPANTS

All patients (n=438) requiring hospital care for an episode of bacteraemia during the years 2000-2003 were included. Statin use, patient outcome, and clinical and laboratory variables were collected.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

There was a significant reduction in all-cause hospital mortality (10.6% vs. 23.1%, p=0.022) and death attributable to bacteraemia (6.1% vs. 18.3%, p=0.014) in patients who were receiving statin therapy at the time of bacteraemia (n=66). The reduction in all-cause hospital mortality (1.8% vs. 23.1%, p=0.0002) and death attributable to bacteraemia (1.8% vs. 18.3%, p=0.0018) was more pronounced in the patients who continued to receive statin therapy after the diagnosis of bacteraemia (n=56). The apparent mortality benefit persisted after controlling for differences between the groups. Statin use prior to admission was associated with a reduced adjusted hospital mortality rate (odds ratio 0.39; CI 95% 0.17, 0.91; p=0.029), and continuing statin use after bacteraemia increased this effect (odds ratio 0.06; CI 95% 0.01, 0.44; p=0.0056).

CONCLUSION

This retrospective study demonstrates a significant survival benefit associated with continuing statin therapy in bacteraemic patients. The potential for statins as an adjuvant therapy in sepsis warrants further investigation.

Statins as Immunomodulatory Agents

Statins have long been thought to exert their benefits by reducing cholesterol synthesis. However, the fact that mevalonate is the precursor of isoprenoids that regulate diverse cellular functions has led investigators to examine pleiotropic effects for these agents. Major histocompatibility complex class II (MHC-II) molecules, which affect the immune response and organ rejection after transplantation, may be induced by the proinflammatory cytokine interferon gamma (IFN-γ). An experiment was conducted to determine whether statins affect the regulation of MHC-II expression by IFN-γ in cultured human endothelial cells and monocyte/macrophages. Statins were found to repress the induction of MHC-II by IFN-γ. This may explain the immunosuppressive effects of statins seen in two clinical trials of organ transplantation and suggest a potential role for statins as immunosuppressive agents.

Hydroxymethylglutaryl coenzyme a reductase inhibitors down-regulate chemokines and chemokine receptors in patients with coronary artery disease

OBJECTIVES

We sought to investigate whether the activation of the chemokine network observed in patients with coronary artery disease (CAD) could be modified by treatment with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins).

BACKGROUND

Chemokines and chemokine receptors are important mediators in atherogenesis, and we hypothesized that the statins could affect the chemokine network in CAD.

METHODS

Thirty CAD patients without previous statin therapy were randomized to receive atorvastatin (80 mg/day, n = 15) or simvastatin (20 mg/day, n = 15). Peripheral blood mononuclear cells (PBMCs) and plasma were obtained at baseline and after six months of statin therapy. Messenger ribonucleic acid (mRNA) expression of chemokines and chemokine receptors in PBMCs was analyzed by ribonuclease protection assay and real-time reverse-transcription polymerase chain reaction. Chemokines were also examined in the supernatants from unstimulated and lipopolysaccharide-stimulated PBMCs (and in plasma).

RESULTS

Our main findings were: 1) gene expression of several chemokines (i.e., macrophage inflammatory protein [MIP]-1alpha, MIP-1beta, and interleukin [IL]-8) and chemokine receptors (i.e., CC chemokine receptor [CCR]1, CCR2, CCR4, and CCR5) was markedly increased among CAD patients compared with healthy control subjects; 2) treatment with atorvastatin and simvastatin markedly reduced the mRNA levels of some of these chemokines (i.e., MIP-1alpha, MIP-1beta, IL-8) and receptors (i.e., CCR1 and CCR2), with the most pronounced effect in the atorvastatin group; and 3) statin therapy reduced the spontaneous release of IL-8 and MIP-1alpha from PBMCs in CAD patients.

CONCLUSIONS

This study demonstrates a down-regulatory effect of statins on the chemokine network in CAD patients, possibly contributing to the beneficial effects of statins in this disorder.

Comparing HMG-CoA reductase inhibitors

The statins have proved to be some of the most potent therapies for reducing elevated low-density lipoprotein (LDL) cholesterol and lessening the risk of coronary heart disease (CHD) and related events. Nonetheless, there are still questions about the clinical relevance of individual drug characteristics, such as chemical derivation, solubility properties, and metabolic route, in terms of tolerability or therapeutic benefit. At the same time, no clear explanation has emerged for the significantly steeper reductions in LDL cholesterol levels achieved with atorvastatin versus lovastatin, simvastatin, pravastatin, or fluvastatin, or, more recently, with rosuvastatin versus atorvastatin, although possible mechanisms have been suggested. More studies are needed to characterize the effects of statins on high-density lipoprotein (HDL) in different patient groups. Clearly, though, several statins have yielded significant reductions in CHD risk and have shown to be well tolerated in both primary and secondary prevention trials. The possibility that statins exert pronounced effects beyond lowering blood lipids is opening other avenues of research into the benefits of these drugs.

Statins as immunomodulators

HMG-CoA reductase inhibitors, or statins, are effective lipid lowering agents, extensively used in medical practice. Statins have never been shown to be involved in the immune response, although few clinical reports have suggested a better outcome of cardiac transplantation in patients under pravastatin therapy. Major histocompatibility complex class II (MHC-II) molecules are directly involved in the activation of T lymphocytes and in the control of the immune response. Whereas only a limited number of specialized cell types express MHC-II constitutively, numerous other cells become MHC-II positive upon induction by interferon gamma (IFN-gamma). We and others recently demonstrated that statins act as direct inhibitors of induction of MHC-II expression by IFN-gamma and thus as repressors of MHC-II-mediated T cell activation. This effect was observed in several cell types, including primary human endothelial cells and macrophages. Interestingly, this inhibition is specific for inducible MHC-II expression and does not concern either constitutive expression of MHC-II or expression of MHC-I. In repressing induction of MHC-II, and subsequent T lymphocyte activation, statins therefore behave as a novel type of immunomodulator. This unexpected effect provides a scientific rationale for suggesting the use of statins as novel immunosuppressors, not only in organ transplantation but in numerous other pathologies as well.

Fluvastatin reduces tissue factor expression and macrophage accumulation in carotid lesions of cholesterol-fed rabbits in the absence of lipid lowering

The expression of tissue factor (TF), mainly by infiltrated inflammatory cells, has been shown to be responsible for the thrombogenicity associated with atheroma. The contribution of the nonlipid-related effects of statins to the clinical benefits of statin therapy is currently under intense investigation. In this study, we evaluated the ability of fluvastatin to modulate TF expression and macrophage accumulation in rabbit carotid intimal lesions independently of cholesterol lowering. Male rabbits were fed for 30 days a 1% cholesterol-rich diet with or without fluvastatin at 5 mg/kg per day. Two weeks from the start of treatment, a silastic collar was placed around the carotid artery. Fifteen days later, the animals were killed, and carotid segments were excised and processed. The atherogenic diet caused a consistent increase in plasma cholesterol levels (610+/-231 mg/dL versus 50+/-9 mg/dL at baseline), which were not affected by fluvastatin (603+/-248 mg/dL). In the rabbits fed a high cholesterol diet without fluvastatin, an intimal lesion with macrophage accumulation and TF expression was detected. Fluvastatin significantly reduced TF and macrophage content of the lesion (-50% for both). Results indicate that fluvastatin may attenuate the inflammatory and thrombogenic potential of atherosclerotic lesions through a mechanism(s) other than cholesterol reduction, providing new insight regarding the complex mode of action of statins.

HMG-CoA reductase inhibitors and the malignant cell: the statin family of drugs as triggers of tumor-specific apoptosis

The statin family of drugs target HMG-CoA reductase, the rate-limiting enzyme of the mevalonate pathway, and have been used successfully in the treatment of hypercholesterolemia for the past 15 years. Experimental evidence suggests this key biochemical pathway holds an important role in the carcinogenic process. Moreover, statin administration in vivo can provide an oncoprotective effect. Indeed, in vitro studies have shown the statins can trigger cells of certain tumor types, such as acute myelogenous leukemia, to undergo apoptosis in a sensitive and specific manner. Mechanistic studies show bcl-2 expression is down-regulated in transformed cells undergoing apoptosis in response to statin exposure. In addition, the apoptotic response is in part due to the depletion of the downstream product geranylgeranyl pyrophosphate, but not farnesyl pyrophosphate or other products of the mevalonate pathway including cholesterol. Clinically, preliminary phase I clinical trials have shown the achievable plasma concentration corresponds to the dose range that can trigger apoptosis of tumor types in vitro. Moreover, little toxicity was evident in vivo even at high concentrations. Clearly, additional clinical trials are warranted to further assess the safety and efficacy of statins as novel and immediately available anti-cancer agents. In this article, the experimental evidence supporting a role for the statin family of drugs to this new application will be reviewed.