Animal safety and toxicology of simvastatin and related hydroxy-methylglutaryl-coenzyme A reductase inhibitors

Association of Common and Rare Genetic Variation in the 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase Gene and Cataract Risk

Background Results from animal models and observational studies have raised concerns regarding the potential cataractogenic effects of statin treatment. We investigated whether common and rare genetic variants in HMGCR are associated with cataract risk, to gauge the likely long-term effects of statin treatment on lenticular opacities. Methods and Results We used genotyping data and exome sequencing data of unrelated European individuals in the UK Biobank to test the association between genetically proxied inhibition of HMGCR and cataract risk. First, we constructed an HMGCR genetic score consisting of 5 common variants weighted by their association with low-density lipoprotein cholesterol. Second, we analyzed exome sequencing data to identify carriers of predicted loss-of-function mutations in HMGCR. Common and rare variants in aggregate were then tested for association with cataract and cataract surgery. In an analysis of >402 000 individuals, a 38.7 mg/dL (1 mmol/L) reduction in low-density lipoprotein C by the HMGCR genetic score was associated with higher risk for cataract (odds ratio, 1.14 [95% CI, 1.00-1.39], P=0.045) and cataract surgery (odds ratio, 1.25 [95% CI, 1.06-1.48], P=0.009). Among 169 172 individuals with HMGCR sequencing data, we identified 32 participants (0.02%), who carried a rare HMGCR predicted loss-of-function variant. Compared with noncarriers, heterozygous carriers of HMGCR predicted loss-of-function had a higher risk of developing cataract (odds ratio, 4.54 [95% CI, 1.96-10.53], P=0.001) and cataract surgery (odds ratio, 5.27 [95% CI, 2.27-12.25], P=5.37×10-4). In exploratory analyses, we found no significant association between genetically proxied inhibition of PCSK9, NPC1L1, or circulating low-density lipoprotein cholesterol levels (P>0.05 for all) and cataract risk. Conclusions We found that genetically proxied inhibition of the HMGCR gene mimicking long-term statin treatment associated with higher risk of cataract. Clinical trials with longer follow-up are needed to confirm these findings.

HMG-CoA Reductase Inhibitor, Simvastatin Is Effective in Decreasing Degree of Myocarditis by Inhibiting Metalloproteinases Activation

Background: Acute myocarditis often progresses to heart failure because there is no effective, etiology-targeted therapy of this disease. Simvastatin has been shown to be cardioprotective by decreasing matrix metalloproteinases’ (MMPs) activity. The study was designed to determine whether simvastatin inhibits MMPs activity, decreases the severity of inflammation and contractile dysfunction of the heart in experimental autoimmune myocarditis (EAM). Methods: Simvastatin (3 or 30 mg/kg/day) was given to experimental rats with EAM by gastric gavage for 21 days. Then transthoracic echocardiography was performed, MMPs activity and troponin I level were determined and tissue samples were assessed under a light and transmission electron microscope. Results: Hearts treated with simvastatin did not show left ventricular enlargement. As a result of EAM, there was an enhanced activation of MMP-9, which was significantly reduced in the high-dose simvastatin group compared to the low-dose group. It was accompanied by prevention of myofilaments degradation and reduction of severity of inflammation. Conclusions: The cardioprotective effects of simvastatin in the acute phase of EAM are, at least in part, due to its ability to decrease MMP-9 activity and subsequent decline in myofilaments degradation and suppression of inflammation. These effects were achieved in doses equivalent to therapeutic doses in humans.

Cholesterol synthesis inhibition promotes axonal regeneration in the injured central nervous system

Neuronal regeneration in the injured central nervous system is hampered by multiple extracellular proteins. These proteins exert their inhibitory action through interactions with receptors that are located in cholesterol rich compartments of the membrane termed lipid rafts. Here we show that cholesterol-synthesis inhibition prevents the association of the Neogenin receptor with lipid rafts. Furthermore, we show that cholesterol-synthesis inhibition enhances axonal growth both on inhibitory -myelin and -RGMa substrates. Following optic nerve injury, lowering cholesterol synthesis with both drugs and siRNA-strategies allows for robust axonal regeneration and promotes neuronal survival. Cholesterol inhibition also enhanced photoreceptor survival in a model of Retinitis Pigmentosa. Our data reveal that Lovastatin leads to several opposing effects on regenerating axons: cholesterol synthesis inhibition promotes regeneration whereas altered prenylation impairs regeneration. We also show that the lactone prodrug form of lovastatin has differing effects on regeneration when compared to the ring-open hydroxy-acid form. Thus the association of cell surface receptors with lipid rafts contributes to axonal regeneration inhibition, and blocking cholesterol synthesis provides a potential therapeutic approach to promote neuronal regeneration and survival in the diseased Central Nervous System. SIGNIFICANCE STATEMENT: Statins have been intensively used to treat high levels of cholesterol in humans. However, the effect of cholesterol inhibition in both the healthy and the diseased brain remains controversial. In particular, it is unclear whether cholesterol inhibition with statins can promote regeneration and survival following injuries. Here we show that late stage cholesterol inhibition promotes robust axonal regeneration following optic nerve injury. We identified distinct mechanisms of action for activated vs non-activated Lovastatin that may account for discrepancies found in the literature. We show that late stage cholesterol synthesis inhibition alters Neogenin association with lipid rafts, thereby i) neutralizing the inhibitory function of its ligand and ii) offering a novel opportunity to promote CNS regeneration and survival following injuries.

Mevalonate pathway as a novel target for the treatment of metastatic gastric cancer

Gastric mucosa tumors may present as two distinct major entities: Diffuse and intestinal subtypes. There is no standard treatment for advanced or metastatic gastric cancer. The mevalonate pathway and cholesterol homeostasis are important processes in cancer cells that may be highly relevant in terms of cell growth, survival and metastatic potential. Two model cell lines representing intestinal (NCI-N87) and diffuse (Hs746T) metastatic gastric tumor histological subtypes were treated with different drugs that alter membrane lipid metabolism to determine whether cell proliferation, viability and migration were affected. The results indicated that the cells exhibited significant differences in proliferation when treated with the cholesterol-lowering drug simvastatin, but not with terbinafine, another compound that affects cholesterol synthesis. Only simvastatin affected migration in both cell lines. Reposition studies with mevalonolactone, farnesyl pyrophosphate and geranylgeranyl pyrophosphate in the presence of high and low FBS concentrations indicated that both isoprenoids and cholesterol reversed the antiproliferative effects of simvastatin in gastric cancer cells. The cell lines used in the present study had different sensitivities to several potential anti-neoplastic agents that affect the synthesis of membrane lipids. The diffuse gastric cancer cells were particularly sensitive to simvastatin, suggesting it as an option for combination treatment.

Simvastatin attenuates lung functional and vascular effects of hyperoxia in preterm rabbits

BACKGROUND

Bronchopulmonary dysplasia (BPD) remains a frequent complication following preterm birth, affecting respiratory health throughout life. Transcriptome analysis in a preterm rabbit model for BPD revealed dysregulation of key genes for inflammation, vascular growth and lung development in animals exposed to hyperoxia, which could be prevented by simvastatin.

METHODS

Preterm rabbits were randomized to either normoxia (21% O₂) or hyperoxia (95% O₂) and within each condition to treatment with 5 mg/kg simvastatin daily or control. Lung function, structure and mRNA-expression was assessed on day 7.

RESULTS

Simvastatin partially prevented the effect of hyperoxia on lung function, without altering alveolar structure or inflammation. A trend towards a less fibrotic phenotype was noted in simvastatin-treated pups, and airways were less muscularized. Most importantly, simvastatin completely prevented hyperoxia-induced arterial remodeling, in association with partial restoration of VEGFA and VEGF receptor 2 (VEGFR2) expression. Simvastatin however decreased survival in pups exposed to normoxia, but not to hyperoxia.

CONCLUSION

Repurposing of simvastatin could be an advantageous therapeutic strategy for bronchopulmonary dysplasia and other developmental lung diseases with pulmonary vascular disease. The increased mortality in the treated normoxia group however limits the translational value at this dose and administration route.

Statin Safety and Associated Adverse Events: A Scientific Statement From the American Heart Association

One in 4 Americans >40 years of age takes a statin to reduce the risk of myocardial infarction, ischemic stroke, and other complications of atherosclerotic disease. The most effective statins produce a mean reduction in low-density lipoprotein cholesterol of 55% to 60% at the maximum dosage, and 6 of the 7 marketed statins are available in generic form, which makes them affordable for most patients. Primarily using data from randomized controlled trials, supplemented with observational data where necessary, this scientific statement provides a comprehensive review of statin safety and tolerability. The review covers the general patient population, as well as demographic subgroups, including the elderly, children, pregnant women, East Asians, and patients with specific conditions such as chronic disease of the kidney and liver, human immunodeficiency viral infection, and organ transplants. The risk of statin-induced serious muscle injury, including rhabdomyolysis, is <0.1%, and the risk of serious hepatotoxicity is ≈0.001%. The risk of statin-induced newly diagnosed diabetes mellitus is ≈0.2% per year of treatment, depending on the underlying risk of diabetes mellitus in the population studied. In patients with cerebrovascular disease, statins possibly increase the risk of hemorrhagic stroke; however, they clearly produce a greater reduction in the risk of atherothrombotic stroke and thus total stroke, as well as other cardiovascular events. There is no convincing evidence for a causal relationship between statins and cancer, cataracts, cognitive dysfunction, peripheral neuropathy, erectile dysfunction, or tendonitis. In US clinical practices, roughly 10% of patients stop taking a statin because of subjective complaints, most commonly muscle symptoms without raised creatine kinase. In contrast, in randomized clinical trials, the difference in the incidence of muscle symptoms without significantly raised creatinine kinase in statin-treated compared with placebo-treated participants is <1%, and it is even smaller (0.1%) for patients who discontinued treatment because of such muscle symptoms. This suggests that muscle symptoms are usually not caused by pharmacological effects of the statin. Restarting statin therapy in these patients can be challenging, but it is important, especially in patients at high risk of cardiovascular events, for whom prevention of these events is a priority. Overall, in patients for whom statin treatment is recommended by current guidelines, the benefits greatly outweigh the risks.

Antioxidant and antihyperlipidemic activity of Costus speciosus against atherogenic diet-induced hyperlipidemia in rabbits

OBJECTIVE

An extract of Costus speciosus (CSE), a herb widely used in folk medicine, was evaluated for its antioxidant, antihyperlipidemic and ameliorating effects on histopathological changes in atherogenic rabbits.

METHODS

Twenty-four male rabbits (Oryctolagus cuniculus) were divided into 4 groups. Three groups were fed a diet containing 3% saturated fat and 1.3% cholesterol for 40 d. One of these was sacrificed on the 40th day and was called the pathogenic (P) group; the other two groups received treatment for another 30 d as follows: one received 0.8 g/(kg·d) of CSE and the other was given 0.01 g/(kg·d) of simvastatin. The normal group was sacrificed on the 70th day and used as a control.

RESULTS

CSE showed radical-scavenging ability. Administration of CSE for a 30-day period resulted in a significant decrease in total cholesterol, triacylglycerol, low-density lipoprotein and aspartate aminotransferase compared to the P group, while levels of hemoglobin, packed corpuscular volume and red blood cells were elevated. With respect to studies performed on the heart, a decrease in malondialdehyde and an increase in reduced glutathione were noted. Total protein increased in the liver, heart and aorta after treatment with CSE and also a marked improvement in histopathological parameters was demonstrated.

CONCLUSION

The present findings indicate that the C. speciosus rhizome possesses antiatherogenic and antioxidant properties which may provide protective effects against oxidative stress in atherosclerotic rabbits.

Use of Lipid-Lowering Drugs and the Risk of Cataract: A Population-Based Nested Case-Control Study

Eye lens membrane cells require high cholesterol concentrations that might be counteracted by lipid-lowering drugs. Using a nationwide database, we conducted a nested case-control study to evaluate the risk of cataract development associated with the use of lipid-lowering drugs. Patients aged 45 years and over with first cataract surgery in 2014 (cases) and up to four controls matched on age, gender, diabetes, hypothyroidism, glucocorticoid use, cardiovascular risk, and area of residence were included in the study. Among the 2,811 cases and 11,106 matched controls included, analyses showed a significantly increased risk of cataract surgery for a cumulative exposure to fibrates exceeding 5 years (adjusted odds ratio (aOR) 1.58; 95% confidence interval (CI): 1.17-2.15), unlike cumulative exposure to statins, whatever the dose or duration of treatment (aORs from 1.00-1.08, none being significant). This study highlighted an increased risk of cataract surgery with prolonged use of fibrates but not of statins.

Implications of cerebrovascular ATP-binding cassette transporter G1 (ABCG1) and apolipoprotein M in cholesterol transport at the blood-brain barrier

Impaired cholesterol/lipoprotein metabolism is linked to neurodegenerative diseases such as Alzheimer's disease (AD). Cerebral cholesterol homeostasis is maintained by the highly efficient blood-brain barrier (BBB) and flux of the oxysterols 24(S)-hydroxycholesterol and 27-hydroxycholesterol, potent liver-X-receptor (LXR) activators. HDL and their apolipoproteins are crucial for cerebral lipid transfer, and loss of ATP binding cassette transporters (ABC)G1 and G4 results in toxic accumulation of oxysterols in the brain. The HDL-associated apolipoprotein (apo)M is positively correlated with pre-β HDL formation in plasma; its presence and function in the brain was thus far unknown. Using an in vitro model of the BBB, we examined expression, regulation, and functions of ABCG1, ABCG4, and apoM in primary porcine brain capillary endothelial cells (pBCEC). RT Q-PCR analyses and immunoblotting revealed that in addition to ABCA1 and scavenger receptor, class B, type I (SR-BI), pBCEC express high levels of ABCG1, which was up-regulated by LXR activation. Immunofluorescent staining, site-specific biotinylation and immunoprecipitation revealed that ABCG1 is localized both to early and late endosomes and on apical and basolateral plasma membranes. Using siRNA interference to silence ABCG1 (by 50%) reduced HDL-mediated [³H]-cholesterol efflux (by 50%) but did not reduce [³H]-24(S)-hydroxycholesterol efflux. In addition to apoA-I, pBCEC express and secrete apoM mainly to the basolateral (brain) compartment. HDL enhanced expression and secretion of apoM by pBCEC, apoM-enriched HDL promoted cellular cholesterol efflux more efficiently than apoM-free HDL, while apoM-silencing diminished cellular cholesterol release. We suggest that ABCG1 and apoM are centrally involved in regulation of cholesterol metabolism/turnover at the BBB.

Simvastatin Exposure and Rotator Cuff Repair in a Rat Model

Simvastatin is a common medication prescribed for hypercholesterolemia that accelerates local bone formation. It is unclear whether simvastatin can accelerate healing at the tendon-bone interface after rotator cuff repair. This study was conducted to investigate whether local and systemic administration of simvastatin increased tendon-bone healing of the rotator cuff as detected by maximum load to failure in a controlled animal-based model. Supraspinatus tendon repair was performed on 120 Sprague-Dawley rats. Sixty rats had a polylactic acid membrane overlying the repair site. Of these, 30 contained simvastatin and 30 did not contain medication. Sixty rats underwent repair without a polylactic acid membrane. Of these, 30 received oral simvastatin (25 mg/kg/d) and 30 received a regular diet. At 4 weeks, 5 rats from each group were killed for histologic analysis. At 8 weeks, 5 rats from each group were killed for histologic analysis and the remaining 20 rats were killed for biomechanical analysis. One rat that received oral simvastatin died of muscle necrosis. Average maximum load to failure was 35.2±6.2 N for those receiving oral simvastatin, 36.8±9.0 N for oral control subjects, 39.5±12.8 N for those receiving local simvastatin, and 39.1±9.3 N for control subjects with a polylactic acid membrane. No statistically significant differences were found between any of the 4 groups (P>.05). Qualitative histologic findings showed that all groups showed increased collagen formation and organization at 8 weeks compared with 4 weeks, with no differences between the 4 groups at each time point. The use of systemic and local simvastatin offered no benefit over control groups. [Orthopedics. 2017; 40(2):e288-e292.].

Simvastatin Ameliorates Matrix Stiffness-Mediated Endothelial Monolayer Disruption

Arterial stiffening accompanies both aging and atherosclerosis, and age-related stiffening of the arterial intima increases RhoA activity and cell contractility contributing to increased endothelium permeability. Notably, statins are 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors whose pleiotropic effects include disrupting small GTPase activity; therefore, we hypothesized the statin simvastatin could be used to attenuate RhoA activity and inhibit the deleterious effects of increased age-related matrix stiffness on endothelial barrier function. Using polyacrylamide gels with stiffnesses of 2.5, 5, and 10 kPa to mimic the physiological stiffness of young and aged arteries, endothelial cells were grown to confluence and treated with simvastatin. Our data indicate that RhoA and phosphorylated myosin light chain activity increase with matrix stiffness but are attenuated when treated with the statin. Increases in cell contractility, cell-cell junction size, and indirect measurements of intercellular tension that increase with matrix stiffness, and are correlated with matrix stiffness-dependent increases in monolayer permeability, also decrease with statin treatment. Furthermore, we report that simvastatin increases activated Rac1 levels that contribute to endothelial barrier enhancing cytoskeletal reorganization. Simvastatin, which is prescribed clinically due to its ability to lower cholesterol, alters the endothelial cell response to increased matrix stiffness to restore endothelial monolayer barrier function, and therefore, presents a possible therapeutic intervention to prevent atherogenesis initiated by age-related arterial stiffening.

Oxidative Stress and Protein Quality Control Systems in the Aged Canine Brain as a Model for Human Neurodegenerative Disorders

Aged dogs are considered the most suitable spontaneous animal model for studying normal aging and neurodegenerative diseases. Elderly canines naturally develop cognitive dysfunction and neuropathological hallmarks similar to those seen in humans, especially Alzheimer's disease-like pathology. Pet dogs also share similar living conditions and diets to humans. Oxidative damage accumulates in the canine brain during aging, making dogs a valid model for translational antioxidant treatment/prevention studies. Evidence suggests the presence of detective protein quality control systems, involving ubiquitin-proteasome system (UPS) and Heat Shock Proteins (HSPs), in the aged canine brain. Further studies on the canine model are needed to clarify the role of age-related changes in UPS activity and HSP expression in neurodegeneration in order to design novel treatment strategies, such as HSP-based therapies, aimed at improving chaperone defences against proteotoxic stress affecting brain during aging.

Hypocholesterolaemic pharmaceutical simvastatin disrupts reproduction and population growth of the amphipod Gammarus locusta at the ng/L range

Simvastatin (SIM), a hypocholesterolaemic drug, is among the most widely used pharmaceuticals worldwide and is therefore of emerging environmental concern. Despite the ubiquitous nature of SIM in the aquatic ecosystems, significant uncertainties exist about sublethal effects of the drug in aquatic organisms. Therefore, here we aimed at investigating a multi-level biological response in the model amphipod Gammarus locusta, following chronic exposures to low levels of SIM (64 ng/L to 8 μg/L). The work integrated a battery of key endpoints at individual-level (survival, growth and reproduction) with histopathological biomarkers in hepatopancreas and gonads. Additionally, an individual-based population modelling was used to project the ecological costs associated with long-term exposure to SIM at the population level. SIM severely impacted growth, reproduction and gonad maturation of G. locusta, concomitantly to changes at the histological level. Among all analysed endpoints, reproduction was particularly sensitive to SIM with significant impact at 320 ng/L. These findings have important implications for environmental risk assessment and disclose new concerns about the effects of SIM in aquatic ecosystems.

Prevention approaches in a preclinical canine model of Alzheimer's disease: benefits and challenges

Aged dogs spontaneously develop many features of human aging and Alzheimer's disease (AD) including cognitive decline and neuropathology. In this review, we discuss age-dependent learning tasks, memory tasks, and functional measures that can be used in aged dogs for sensitive treatment outcome measures. Neuropathology that is linked to cognitive decline is described along with examples of treatment studies that show reduced neuropathology in aging dogs (dietary manipulations, behavioral enrichment, immunotherapy, and statins). Studies in canine show that multi-targeted approaches may be more beneficial than single pathway manipulations (e.g., antioxidants combined with behavioral enrichment). Aging canine studies show good predictive validity for human clinical trials outcomes (e.g., immunotherapy) and several interventions tested in dogs strongly support a prevention approach (e.g., immunotherapy and statins). Further, dogs are ideally suited for prevention studies as they the age because onset of cognitive decline and neuropathology strongly support longitudinal interventions that can be completed within a 3-5 year period. Disadvantages to using the canine model are that they lengthy, use labor-intensive comprehensive cognitive testing, and involve costly housing (almost as high as that of non-human primates). However, overall, using the dog as a preclinical model for testing preventive approaches for AD may complement work in rodents and non-human primates.

Enhancement of autophagy by simvastatin through inhibition of Rac1-mTOR signaling pathway in coronary arterial myocytes

BACKGROUND/AIMS

In addition to their action of lowering blood cholesterol levels, statins modulate biological characteristics and functions of arterial myocytes such as viability, proliferation, apoptosis, survival and contraction. The present study tested whether simvastatin, as a prototype statin, enhances autophagy in coronary arterial myocytes (CAMs) to thereby exert their beneficial effects in atherosclerosis.

METHODS AND RESULTS

Using flow cytometry, we demonstrated that simvastatin significantly increased the autophagsome formation in CAMs. Western blot analysis confirmed that simvastatin significantly increased protein expression of typical autophagy markers LC3B and Beclin1 in these CAMs. Confocal microscopy further demonstrated that simvastatin increased fusion of autophagosomes with lysosomes, which was blocked by autophagy inhibitor 3-methyladenine or silencing of Atg7 genes. Simvastatin reduced mammalian target of rapamycin (mTOR) activity, which was reversed by Rac1-GTPase overexpression and the mTOR agonist phosphatidic acid. Moreover, both Rac1-GTPase overexpression and activation of mTOR by phosphatidic acid drastically blocked simvastatin-induced autophagosome formation in CAMs. Interestingly, simvastatin increased protein expression of a contractile phenotype marker calponin in CAMs, which was blocked by autophagy inhibitor 3-methyladenine. Simvastatin markedly reduced proliferation of CAMs under both control and proatherogenic stimulation. However, this inhibitory effect of simvastatin on CAM proliferation was blocked by by autophagy inhibitor 3-methyladenine or silencing of Atg7 genes. Lastly, animal experiments demonstrated that simvastatin increased protein expression of LC3B and calponin in mouse coronary arteries.

CONCLUSION

Our results indicate that simvastatin inhibits the Rac1-mTOR pathway and thereby increases autophagy in CAMs which may stabilize CAMs in the contractile phenotype to prevent proliferation and growth of these cells.

A canine model of human aging and Alzheimer's disease

The aged dog naturally develops cognitive decline in many different domains (including learning and memory) but also exhibits human-like individual variability in the aging process. The neurobiological basis for cognitive dysfunction may be related to structural changes that reflect neurodegeneration. Molecular cascades that contribute to degeneration in the aging dog brain include the progressive accumulation of beta-amyloid (Aβ) in diffuse plaques and in the cerebral vasculature. In addition, neuronal dysfunction occurs as a consequence of mitochondrial dysfunction and cumulative oxidative damage. In combination, the aged dog captures key features of human aging, making them particularly useful for the development of preventive or therapeutic interventions to improve aged brain function. These interventions can then be translated into human clinical trials. This article is part of a Special Issue entitled: Animal Models of Disease.

Attenuation by statins of membrane raft-redox signaling in coronary arterial endothelium

Membrane raft (MR)-redox signaling platforms associated with NADPH oxidase are involved in coronary endothelial dysfunction. Here, we studied whether statins interfere with the formation of MR-redox signaling platforms to protect the coronary arterial endothelium from oxidized low-density lipoprotein (OxLDL)-induced injury and from acute hypercholesterolemia. In cultured human coronary arterial endothelial cells, confocal microscopy detected the formation of an MRs clustering when they were exposed to OxLDL, and such MR platform formation was inhibited markedly by statins, including pravastatin and simvastatin. In these MR clusters, NADPH oxidase subunits gp91(phox) and p47(phox) were aggregated and were markedly blocked by both statins. In addition, colocalization of acid sphingomyelinase (ASM) and ceramide was induced by OxLDL, which was blocked by statins. Electron spin resonance spectrometry showed that OxLDL-induced superoxide (O2(.-)) production in the MR fractions was substantially reduced by statins. In coronary artery intima of mice with acute hypercholesterolemia, confocal microscopy revealed a colocalization of gp91(phox), p47(phox), ASM, or ceramide in MR clusters. Such colocalization was rarely observed in the arteries of normal mice or significantly reduced by pretreatment of hypercholesterolemic mice with statins. Furthermore, O2(.-) production in situ was 3-fold higher in the coronary arteries from hypercholesterolemic mice than in those from normal mice, and such increase was inhibited by statins. Our results indicate that blockade of MR-redox signaling platform formation in endothelial cell membrane may be another important therapeutic mechanism of statins in preventing endothelial injury and atherosclerosis and may be associated with their direct action on membrane cholesterol structure and function.

Therapeutic interventions targeting Beta amyloid pathogenesis in an aging dog model

Aged dogs and humans share complex cognitive and pathological responses to aging. Specifically, dogs develop Alzheimer's Disease (AD) like beta-amyloid (Aβ) that are associated with cognitive deficits. Currently, therapeutic approaches to prevent AD are targeted towards reduced production, aggregation and increased clearance of Aβ. The current review discusses cognition and neuropathology of the aging canine model and how it has and continues to be useful in further understanding the safety and efficacy of potential AD prevention therapies targeting Aβ.

Hypercholesterolemia promotes an osteoporotic phenotype

A role for hypercholesterolemia in the development of osteoporosis has been suggested in published reports. However, few studies contain direct evidence of a role for maintenance of cholesterol homeostasis in bone health. Using isocaloric high-fat/high-cholesterol and low-fat/no-cholesterol diets in a 4-month feeding study combined with micro computed tomography analysis, we demonstrated in two different mouse strains that mice with hypercholesterolemia lose cortical and trabecular bone in the femurs and vertebrae (bone mineral density was decreased on average by ≈90 mg/mL in the cortical vertebrae in one strain) and cortical bone in the calvariae (bone mineral density was decreased on average by ≈60 mg/mL in one strain). Mechanical testing of the femurs demonstrated that loss of bone in the mice with hypercholesterolemia caused changes in the mechanical properties of the bone including loss of failure load (failure load was decreased by ≈10 N in one strain) and energy to failure. Serologic and histomorphologic analyses suggested that hypercholesterolemia promotes osteoclastogenesis. These studies support a role for hypercholesterolemia in the development of osteoporosis and provide a model with which to test intervention strategies to reduce the effects of hypercholesterolemia on bone health.

Effect of pretreatment with simvastatin on spinal cord ischemia-reperfusion injury in rats

OBJECTIVE

The aim of this study was to evaluate the pretreatment effect of simvastatin on spinal cord ischemia-reperfusion injury.

DESIGN

Prospective, interventional study.

SETTING

University research laboratory.

PARTICIPANTS

Forty-five male Sprague-Dawley rats.

INTERVENTIONS

Rats were treated with oral simvastatin, 10 mg/kg (simvastatin group; n = 15) or saline (control group; n = 15) for 5 days before ischemia. Spinal cord ischemia was induced using a balloon-tipped catheter placed in the proximal descending aorta in the control and simvastatin groups, but not in the sham group (n = 15).

MEASUREMENTS AND MAIN RESULTS

Neurologic function was assessed daily using the motor deficit index until 7 days after reperfusion. After the last neurologic evaluation, a histologic examination of the spinal cord was performed. At day 1 after reperfusion, the simvastatin group showed a significantly lower motor deficit index compared with the control group (2.0, 2.0-2.0, v 4.0, 3.5-5.0; p < 0.001). This trend was sustained at day 7 (2.0, 1.5-2.0, v 4.0, 3.0-4.0; p < 0.001). The simvastatin group displayed a significantly larger number of normal motor neurons compared with the control group (mean ± SD, 31.7 ± 6.1 v 20.4 ± 4.4; p < 0.001). However, compared with the sham group, the simvastatin group displayed fewer intact motor neurons (sham group, 38.5 ± 5.1; p = 0.005).

CONCLUSIONS

Pretreatment with simvastatin, 10 mg/kg, given orally for 5 days before the ischemia-reperfusion insult, improved the neurologic outcome and preserved more normal motor neurons compared with the control group in a rat model of spinal cord ischemia-reperfusion.

Juvenile toxicity assessment of open-acid lovastatin in rats

BACKGROUND

Lovastatin, an inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, reduces de novo cholesterol biosynthesis primarily in the liver. Since cholesterol is a major component of brain myelin and peak periods of brain myelination occurs after birth, this study was designed to encompass this period in rats and evaluate the potential neurotoxic effects.

METHODS

The pharmacologically active, open-acid form of lovastatin was administered to groups of 50 Sprague-Dawley rats per sex subcutaneously once daily at dose levels of 0 (vehicle), 2.5, 5, or 10 mg/kg/day beginning on postnatal day 4 and continuing until termination on postnatal day 41 to 51. Physical signs and body weights were monitored during the study. Animals were assessed in a battery of behavioral tests, and at termination a set of animals were examined for gross and histological changes.

RESULTS

There were no test article-related deaths, physical signs, or effects on preweaning and postweaning body weights during the study. In the behavior tests there were no test article-related effects in the passive avoidance, auditory startle habituation, open-field motor activity, or FOB. No test article-related postmortem findings were observed, including brain weights and histomorphology of brain, spinal cord, eye, optic nerve, or peripheral nerve.

CONCLUSION

Based on these results, the no-effect level for general and neurobehavioral toxicity in neonatal rats was ≥10 mg/kg/day for open-acid lovastatin.

Coenzyme Q10 and cognition in atorvastatin treated dogs

Statins have been suggested to protect against Alzheimer's disease (AD). Recently, however, we reported that aged dogs that underwent chronic statin treatment exhibited cognitive deficits compared with age matched controls. In human studies, blood levels of Coenzyme Q10 (CoQ10) decrease with statin use. CoQ10 is important for proper mitochondrial function and is a powerful antioxidant, two important factors for cognitive health in aging. Thus, the current study tested the hypothesis that CoQ10 levels in the serum and/or parietal cortex are decreased in statin treated dogs and are associated with poorer cognition. Six aged beagles (>8 years) were administered 80 mg/day of atorvastatin for 14.5 months and compared with placebo-treated animals. As predicted, serum CoQ10 was significantly lower in statin-treated dogs. Parietal cortex CoQ10 was not different between the two groups. However, poorer cognition was correlated with lower parietal cortex CoQ10. This study in dogs suggests that serum CoQ10 is reduced with atorvastatin treatment. CoQ10 levels in brain may be linked to impaired cognition in response to atorvastatin, in agreement with previous reports that statins may have a negative impact on cognition in the elderly.

Synergistic anticancer effects of combined γ-tocotrienol with statin or receptor tyrosine kinase inhibitor treatment

Systemic chemotherapy is the only current method of treatment that provides some chance for long-term survival in patients with advanced or metastatic cancer. γ-Tocotrienol is a natural form of vitamin E found in high concentrations in palm oil and displays potent anticancer effects, but limited absorption and transport of by the body has made it difficult to obtain and sustain therapeutic levels in the blood and target tissues. Statins are inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A (HMGCoA) reductase and are an example of a promising cancer chemotherapeutic agent whose clinical usefulness has been limited due to high-dose toxicity. Similarly, erlotinib and gefitinib are anticancer agents that inhibit the activation of individual HER/ErbB receptor subtypes, but have shown limited clinical success because of heterodimerization between different EGF receptor family members that can rescue cancer cells from agents directed against a single receptor subtype. Recent studies have investigated the anticancer effectiveness of low-dose treatment of various statins or EGF receptor inhibitors alone and in combination with γ-tocotrienol on highly malignant +SA mouse mammary epithelial cells in vitro. Combined treatment with subeffective doses of γ-tocotrienol with these other chemotherapeutic agents resulted in a synergistic inhibition of +SA cell growth and viability. These findings strongly suggest that combined treatment of γ-tocotrienol with other anticancer agents may not only provide an enhanced therapeutic response but also provide a means to avoid the toxicity, low bioavailability, or limited therapeutic action associated with high-dose monotherapy.

Simvastatin combined with nifedipine enhances endothelial cell protection by inhibiting ROS generation and activating Akt phosphorylation

AIM

To investigate the protective effects of simvastatin (Sim) combined with nifedipine (Nif) on endothelial cells and elucidate the action mechanism.

METHODS

Human umbilical vein endothelial cells (HUVEC) were used. mRNA and protein levels were measured by using reverse-transcription polymerase chain reaction (RT-PCR) and Western blotting, respectively. Intracellular calcium and reactive oxygen species (ROS) were detected using confocal microscopy. The Griess assay was used to evaluate nitric oxide (NO) release.

RESULTS

Treatment of HUVEC with H(2)O(2) 100 micromol/L for 30 min inhibited the mRNA and protein expression of endothelial nitric oxide synthase (eNOS). With increased concentrations of Nif, eNOS mRNA and protein levels increased (P<0.05). Combined treatment with Sim 1.0 micromol/L and Nif 1.0 micromol/L significantly increased the mRNA and protein expression of eNOS and NO release compared with Sim or Nif alone (P<0.05). The combination significantly lowered the intracellular ROS level (P<0.05), which was correlated with the increase in eNOS and NO, but there was no visible change in intracellular calcium (P>0.05). Compared with individual drug treatment, Akt phosphorylation and the ratio of p-eNOS/eNOS were up-regulated in the combination group, and this effect was inhibited by the phosphatidylinositol 3-kinase (PI3K) inhibitors wortmannin and LY294002.

CONCLUSION

The Sim-Nif combination effectively protects HUVEC against H(2)O(2) injury by inhibiting intracellular ROS generation, increasing the ratio of p-eNOS/eNOS and up-regulating Akt phosphorylation.

Can low doses of simvastatin enhance fracture healing? An experimental study in rabbits

Several observational and experimental studies have investigated the potential anabolic effects of statins on undisturbed bone but only a few recent studies have examined the effect of statins on skeletal repair. The goal of the study is to investigate any potential early anabolic effect of the systemic administration of simvastatin in low doses (based on earlier safety and efficacy studies on undisturbed bone) on fracture healing. Fifty-four skeletally mature male New Zealand White rabbits were used for the study. The rabbits were assigned to one of three experimental groups: a control group, and two groups that were orally administrated a diet with 10 and 30 mg/kg/day of simvastatin, respectively. A complete biochemical blood count was performed to exclude drug-induced complications. Half of the animals of each group were sacrificed at 15 days and the other half at 30 days after surgery at which time intervals healing quality was assessed. The bones were subjected to biomechanical testing, histomorphometric analysis and peripheral quantitative computed tomography. In animals received simvastatin of 30 mg/kg/day a significant reduction of BMD, stiffness, and energy absorbed to failure were observed. At 15 days, the amount of cartilaginous callus formation was reduced, and the void space was significantly increased, in the animals of both groups that received simvastatin when compared to the control group (p<.05). Our results suggest that simvastatin doses of 30 mg/kg/day may have a negative anabolic effect on callus formation in rabbits, whereas doses of 10 mg/kg/day seem not to produce a significant positive or a negative effect, especially at the early stages of fracture remodeling.

A current practice for predicting ocular toxicity of systemically delivered drugs

The ability to predict ocular side effects of systemically delivered drugs is an important issue for pharmaceutical companies. Although animal models involving standard clinical ophthalmic examinations and postmortem microscopic examinations of eyes are still used to identify ocular issues, these methods are being supplemented with additional in silico, in vitro, and in vivo techniques to identify potential safety issues and assess risk. The addition of these tests to a development plan for a potential new drug provides the opportunity to save time and money by detecting ocular issues earlier in the program. This review summarizes a current practice for minimizing the potential for systemically administered, new medicines to cause adverse effects in the eye.

Statin-induced myopathy in the rat: relationship between systemic exposure, muscle exposure and myopathy

Rare instances of myopathy are associated with all statins, but cerivastatin was withdrawn from clinical use due to a greater incidence of myopathy. The mechanism of statin-induced myopathy with respect to tissue disposition was investigated by measuring the systemic, hepatic, and skeletal muscle exposure of cerivastatin, rosuvastatin, and simvastatin in rats before and after muscle damage. The development of myopathy was not associated with the accumulation of statins in skeletal muscle. For each statin exposure was equivalent in muscles irrespective of their fibre-type sensitivity to myopathy. The low amount of each statin in skeletal muscle relative to the liver does not support a significant role for transporters in the disposition of statins in skeletal muscle. Finally, the concentration of cerivastatin necessary to cause necrosis in skeletal muscle was considerably lower than rosuvastatin or simvastatin, supporting the concept cerivastatin is intrinsically more myotoxic than other statins.

Simvastatin increases osteoblasts and osteogenic proteins in ovariectomized rats

BACKGROUND

Previous reports have indicated that statins could prevent bone loss in ovariectomized (OVX) rats and increase the expressions of osteogenic genes in cultured osteoblasts. In this study, we hypothesized that simvastatin might increase osteoblast number and protein expressions of osteogenic markers localized in bones in concomitance with the prevention of bone loss in OVX rats.

MATERIALS AND METHODS

Fifty-four 3-month-old OVX and sham-operated (SHAM) female Sprague-Dawley rats were used. Simvastatin (10-20 mg kg(-1) day(-1)) was administrated orally for 6 weeks. Trabecular volume, osteoblast number and osteogenic proteins including BMP2, collagen type I and osteocalcin on bone sections obtained from lumbar vertebral body, distal femur and proximal tibia were measured.

RESULTS

The results showed that SHAM rats had significantly less trabecular bone volume and osteoblast number than that of OVX rats 6 weeks after operation. Oral simvastatin treatment (10-20 mg kg(-1) day(-1)) increased bone volume and osteoblast number in the distal femurs, proximal tibiae and vertebrae of OVX rats. Furthermore, the osteoblastic cells with immuno-stained BMP2, collagen type I and osteocalcin in vertebral bones were significantly increased by simvastatin treatment (20 mg kg(-1) day(-1)) in OVX rats.

CONCLUSIONS

This study demonstrates that simvastatin enhances the production of osteogenic proteins in bone and this effect may contribute to the prevention of bone loss in OVX rats.

Locally applied simvastatin promotes fracture healing in ovariectomized rat

Simvastatin solution was injected subcutaneously to the site of fractured tibiae of ovariectomized rats. Afterwards healing quality was evaluated by morphologic, radiographic, biomechanical, histological and histomorphometric methods at 1, 2 and 4 weeks after fracture. Results showed that locally applied simvastatin improved fracture healing.

INTRODUCTION

Many studies have documented an anabolic effect of hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, statins, on undisturbed bone. Reports of their effects, however, on fractured skeletal systems have been limited. A study was, therefore, conducted to check the effects of statins on fracture healing.

METHODS

Simvastatin (10 mg/kg/day) was injected subcutaneously to tissue overlying the site of fractured tibiae of ovariectomized rats for a treatment period of 5 days. Vehicle reagent was used as a control. Healing quality was evaluated at 1, 2 and 4 weeks after fracture.

RESULTS

Compared with that in the vehicle group, the callus cross-section area in simvastatin-treated rats was significantly enlarged by 21.3% (p < 0.05) at 1 week and by 21.5% (p < 0.05) at 2 weeks; new woven bone was relatively substantive and arranged more tightly and regularly at 2 and 4 weeks; and maximal load was increased by 57.5% (p < 0.05) at 2 weeks and by 31.4% (p < 0.05) at 4 weeks. Histomorphometrically, simvastatin was associated with a significant (p < 0.05) increase of mineralization width (MLW), mineralization volume (MLV) and mineral apposition rate (MAR).

CONCLUSION

The current study suggests that local application of simvastatin could promote fracture healing in ovariectomized rats.

The application of microbore UPLC/oa-TOF-MS and 1H NMR spectroscopy to the metabonomic analysis of rat urine following the intravenous administration of pravastatin

The metabonomic effects of hepatotoxic doses of pravastatin on the urinary metabolic profiles of female rats have been investigated using ultra performance liquid chromatography (UPLC)-oa-TOF-MS and, independently, by (1)H NMR spectroscopy. UPLC was performed using a 1 mm microbore column packed with 1.7 microm particles. Examination of the data obtained from the individual animals, aided by statistical interpretation of the data, made it possible to identify potential markers for toxicological effects, with both NMR and UPLC-MS analysis highlighting distinct changes in the urinary metabolite profiles. These markers, which included elevated taurine and creatine, as well as bile acids, were consistent with hepatotoxicity in some animals, and this hypothesis was supported by histopathological and clinical chemistry findings. The analytical data from both techniques could be used to define a metabolic "trajectory" as toxicity developed and to provide an explanation for the lack of hepatotoxicity for one of the animals. The two analytical approaches (UPLC-MS and NMR) were found to be complementary whilst the use of a 1mm i.d. x 100 mm column reduced the amount of sample required for analysis to 2 microL, compared with 10 microL for a 2.1mm i.d. x 100 mm column. The 1mm i.d. column also provided increased signal-to-noise without loss of chromatographic efficiency.

Systemic administration of simvastatin after the onset of experimental subarachnoid hemorrhage attenuates cerebral vasospasm

OBJECTIVE

Experimental evidence suggests that intercellular adhesion molecule-1 mediated leukocyte extravasation contributes to the pathogenesis of cerebral vasospasm. Simvastatin, an HMG-CoA reductase inhibitor, decreases intercellular adhesion molecule-1 expression and competitively inhibits leukocyte intercellular adhesion molecule-1 binding. We hypothesized that administration of simvastatin after the onset of subarachnoid hemorrhage (SAH) would attenuate perivascular granulocyte migration and ameliorate cerebral vasospasm in a rabbit model of SAH.

METHODS

New Zealand white rabbits (n = 15) underwent injection of autologous blood into the cisterna magna or sham surgery followed by subcutaneous injection of simvastatin (40 mg/kg) or vehicle 30 minutes, 24 hours, and 48 hours after SAH or sham surgery. Seventy-two hours later, basilar artery lumen diameter was measured by in situ perfusion/fixation and image analysis. CD-18 monoclonal antibody stained perivascular granulocytes and macrophages were counted under light microscopy.

RESULTS

In vehicle treated rabbits, mean +/- standard deviation basilar artery diameter was reduced 3 days after SAH (n = 5) versus sham (n = 5) rabbits (0.49 +/- 0.08 mm versus 0.75 +/- 0.03 mm, P < 0.01). After SAH, mean +/- standard deviation basilar artery diameter was greater in simvastatin (n = 5) treated rabbits versus vehicle (n = 5) (0.63 +/- 0.04 mm versus 0.49 +/- 0.08 mm, P < 0.01). In vehicle treated rabbits, SAH resulted in an increase in the mean +/- standard deviation perivascular CD18 cell count (sham-vehicle, 2.8 +/- 2; SAH-vehicle 90 +/- 27; P < 0.01). Subcutaneous administration of simvastatin attenuated this increase in perivascular CD18-positive cells after SAH (SAH statin, 41.6 +/- 13; SAH vehicle, 90 +/- 27; P < 0.001).

CONCLUSION

Subcutaneous administration of simvastatin after the onset of SAH attenuates perivascular granulocyte migration and ameliorates basilar artery vasospasm after experimental SAH in rabbits. 5-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors, such as simvastatin, may potentially serve as agents in the prevention of cerebral vasospasm after SAH.

The use of simvastatin in rabbit posterolateral lumbar intertransverse process spine fusion

BACKGROUND CONTEXT

There has been recent enthusiasm regarding the potential positive effects of statins on bone. Statins vary in their ability to influence bone activity. Simvastatin has been shown in experimental models to stimulate bone acting growth factors and enhance bone formation.

PURPOSE

The potential efficacy of Simvastatin in enhancing spinal fusion was evaluated in a rabbit posterolateral intertransverse process fusion model.

STUDY DESIGN/SETTING

Posterior lumbar intertransverse process spinal fusion performed on New Zealand White rabbits. PATIENT/STUDY SAMPLE: 44 New Zealand White rabbits.

OUTCOME MEASURES

Spinal fusion as determined by manual palpation testing and fine detail radiography. Bone fusion mass volume and density as determined by CT scan imaging.

METHODS

Forty-four New Zealand White rabbits underwent posterolateral intertransverse process spine fusion using autogenous iliac crest bone graft. Simvastatin was administered orally in 20 animals and the serum lipid profile quantified in test and control animals. The animals were euthanized 9 weeks following index surgery and the lumbar spine was harvested. Spinal fusion was determined by manual palpation testing and fine detail radiography. The volume and density of the bone fusion mass was quantified by computed tomography.

RESULTS

Drug treatment for 9 weeks caused a reduction in serum lipid biochemical markers when compared with controls. The spinal fusion rate, as judged by manual palpation testing (13.0% control group, 16.6% Simvastatin group) and fine detail radiography, was not significantly different comparing treatment with control animals. Accordant with the assessment of spinal fusion, there was no statistically significant effect on the volume of the fusion mass (1,224.7+/-98.7 mm(3) in the control group and 1,075.9+/-66.3 mm(3) in the Simvastatin group), the density of bone in the lumbar spine or that in the formed fusion mass.

CONCLUSIONS

Systemic use of Simvastatin caused a reduction in lipid biochemical parameters in treated animals. Successful spinal fusion as judged by manual palpation testing and fine detail radiography was not significantly different in treated versus untreated animals. The bone volume density of the formed fusion mass was not significantly different in treated versus untreated animals. There did not appear to be a significant advantage or disadvantage to the use of Simvastatin rabbit posterolateral spinal fusion. The potential positive effects of statins on bone require further study.

Colesevelam hydrochloride does not cause maternal or fetal toxicity in rats and rabbits

WelChol (colesevelam hydrochloride), a bile acid sequestrant for the treatment of hypercholesterolemia, was evaluated for adverse effects on reproduction and fetal development using standard preclinical tests. During gestation, Sprague-Dawley rats used in the developmental toxicity study received feed, feed/control article or feed plus 300, 1,000 or 3,000 mg/kg/day colesevelam whereas rats in the pre- and postnatal toxicity study received vehicle or 100, 300 or 1,000 mg/kg/day colesevelam via gavage. New Zealand white rabbits received control or 100, 500 or 1,000 mg/kg/day colesevelam via gavage. No deaths, premature deliveries or gross pathologic lesions were observed up to gestation day (GD) 20 for rats and GD 28 for rabbits. No significant differences in the number of pregnant animals, average litter size, percentage of viable fetuses, fetal body weights, number of corpora lutea, fetal viability, or gross malformations were observed versus controls. Pre- and postnatal effects were assessed in pregnant rats receiving 100, 300 or 1,000 mg/kg/day colesevelam from GD 6 to postpartum day 22. Gestation, parturition and lactation in F(0) generation dams were similar between treatment and control groups. Colesevelam did not affect physical or neurological development or induce gross pathological changes in F(1) generation rats. Colesevelam does not produce developmental toxicity in rats or rabbits, nor does it exhibit pre- or postnatal toxicity in rats at the tested doses.

Histopathologic findings after treatment with different oxidosqualene cyclase (OSC) inhibitors in hamsters and dogs

In order to investigate the toxicity of oxidosqualene cyclase (OSC) inhibitors, hamsters and dogs were treated up to 13 weeks with three different agents of this compound class. Subacute treatment (< or = 4 weeks) of hamsters and dogs with OSC inhibitors produced a similar spectrum of histopathologic lesions, which have previously been described for compounds of this pharmacological class. In the hamster, other lesions were produced only after subchronic treatment (13 weeks). After subacute treatment, histopathologic findings were observed in the eye, skin and forestomach. Lesions in the eye were characterized as proliferation, swelling and degeneration of lens fiber cells. This finding was considered to be an early stage in cataract development. In the skin and forestomach, squamous cell hyperplasia and hyperkeratosis accompanied by a mixed inflammation was observed. After subchronic treatment of hamsters, histopathologic findings were observed in the eye, skin, forestomach, testes, epididymides, prostate gland, seminal vesicles and long bones. Lesions in the eye were characterized as cataracts. Squamous cell hyperplasia accompanied by a diffuse hyperkeratosis and a mixed inflammation was seen in the skin and forestomach epithelium. In addition, testes lesions were characterized as testicular atrophy, generalized germ cell depletion, germ cell degeneration and tubular collapse. Atrophy, oligospermia and lumenal germ cells/cell debris were found in the epididymides. The prostate gland and seminal vesicles were decreased in size (atrophy). The bone lesions were characterized as a failure of enchondral ossification causing variable widening of the growth plate and a failure to form primary bone trabecula (lesions resemble those found in rickets). To our knowledge, this is the first study describing the toxicity of OSC inhibitors after subchronic treatment in hamsters and dogs. As all adverse effects described in this report are considered to be due to an exaggeration of the desired biochemical mechanism of action at high dose levels, a decrease of the systemic exposure by the use of more hepatoselective OSC inhibitors is expected to reduce the probability of these adverse effects in humans.

Statins downregulate myeloperoxidase gene expression in macrophages

Statins, inhibitors of HMG-CoA reductase, have pleiotropic benefits independent of cholesterol levels, including anti-oxidant and anti-inflammatory effects. Here, we investigate the effect of statins on myeloperoxidase (MPO) expression. MPO, expressed in foam cell macrophages, was recently shown to oxidize the ApoA-1 component of HDL, impairing ABCA-1 mediated cholesterol efflux. High levels of serum MPO correlate with increased risk of CAD events. Findings here show that statins strongly inhibit MPO mRNA expression in human and murine monocyte-macrophages. Suppression was reversed by downstream intermediates of HMG-CoA reductase, mevalonate, and geranylgeranylpyrophosphate, but not farnesylpyrophosphate. An inhibitor of geranylgeranyltransferase, GGTI-286, mimics the effects of statins, indicating geranylgeranylation is key to MPO expression. Reduction of MPO mRNA levels was observed in vivo in leukocytes from statin-fed mice, correlating with reductions in MPO protein and enzyme activity. These findings suggest that the pleiotropic protections afforded by statins may be due in part to suppression of MPO expression.

Statins potentiate the IFN-γ-induced upregulation of group IIA phospholipase A2 in human aortic smooth muscle cells and HepG2 hepatoma cells

The present study shows that the incubation of human aortic smooth muscle cells (HASMC) and HepG2 cells with atorvastatin and mevastatin as HMG-CoA reductase inhibitors potentiated the interferon-gamma (INF-gamma)-induced group IIA phospholipase A(2) (sPLA(2)-IIA) expression in a dose- and time-dependent manner. The effect of statins on sPLA(2)-IIA expression was reduced by mevalonate, farnesyl pyrophosphate and geranylgeranyl pyrophosphate. Inversely, inhibitors of the farnesyl transferase and geranylgeranyl transferase-I mimicked the effects of statins. Clostridium difficile toxin B (TcdB), Y-27632 and H-1152, functioning as inhibitors of Rho proteins and Rho-associated kinase, also augmented the sPLA(2)-IIA expression in combination with IFN-gamma. The same effects were observed when inhibitors of mitogen-activated/extracellular response protein kinase kinase (MEK), PD98059 or U0126 were used. Further, the Janus kinase-2 (Jak2)-specific inhibitor, AG-490 and inhibitors of nuclear factor-kappaB (NFkappaB) abrogated the sPLA(2)-IIA elevating effects of statins, TcdB and PD98059 in the presence of IFN-gamma. This cytokine alone increased the NFkappaB p65 and CAAT-enhancer-binding protein-beta (C/EBP-beta) activity in HASMC nuclear extract, but only C/EBP-beta was further augmented when the cells were incubated in addition to IFN-gamma with atorvastatin, H-1152, PD98059 or U0126. Moreover, after the incubation of cells with atorvastatin and IFN-gamma the stability of sPLA-(2)IIA mRNA significantly increased in comparison to those after incubation with IFN-gamma alone. In conclusion, the obtained data suggest that (i) the expression of sPLA(2)-IIA is negatively regulated by RhoA/Rho-associated kinase and MEK/ERK signaling pathways and (ii) statins, because of their ability to down-regulate these pathways, can potentiate the IFN-gamma-induced sPLA(2)-II expression at transcriptional and post-transcriptional levels.

Lovastatin and beyond: the history of the HMG-CoA reductase inhibitors

In the 1950s and 1960s, it became apparent that elevated concentrations of plasma cholesterol were a major risk factor for the development of coronary heart disease, which led to the search for drugs that could reduce plasma cholesterol. One possibility was to reduce cholesterol biosynthesis, and the rate-limiting enzyme in the cholesterol biosynthetic pathway, 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase, was a natural target. Here, I describe the discovery and development of lovastatin--the first approved inhibitor of HMG-CoA reductase--and the clinical trials that have provided the evidence for the ability of drugs in this class to reduce the morbidity and mortality associated with cardiovascular disease.

Hepatotoxicity of hypolipidemic drugs

Dyslipidemic conditions and their cardiovascular related complications are common. Effective primary and secondary prevention strategies include therapies to lower LDL and total cholesterol and to increase HDL. Further, it seems that there is a need for therapeutic reduction in triglycerides as it emerges as an independent risk factor for CVD. Many clinical trials have been designed to evaluate pharmacologic compounds in the treatment of the dyslipidemias and they seem to have shown a safe profile, both in the experiment phases and in post-marketing observation studies. Nevertheless, sporadic reports of hepatotoxicity with statins and niacin still arise (Table 2). Although routine hepatic biochemical test monitoring is recommended, the cost-effectiveness is questionable because often these reactions are idiosyncratic and may not be identified by this routine screening. The risk/benefit ratio is in favor of using these medications in individuals at risk. There is no evidence to suggest intrinsic hepatotoxic activity as such. Drugs that lower triglycerides such as fibrates, have been observed to improve hepatic biochemical tests, although in small series. This leads to speculation whether treatment with fibrates would be beneficial for non-alcoholic fatty liver disease (NAFLD), a condition that is emerging as one of enormous magnitude.

A 6-Month Study on the Toxicity of High Doses of Policosanol Orally Administered to Sprague-Dawley Rats

Policosanol is a cholesterol-lowering drug purified from sugar cane. Previous toxicological studies have not demonstrated any policosanol-related toxicity, even with long-term oral administration at 500 mg/kg, a dose 1,724 times larger than the maximal therapeutic dose (20 mg/day) recommended to date. The present study was undertaken to investigate the oral toxicity of policosanol administered for 6 months in doses up to 5,000 mg/kg to Sprague-Dawley rats. Animals were randomly distributed in five groups (15 animals per dose per sex): a control and four groups given oral policosanol (50, 500, 2,500, or 5,000 mg/kg). Eight treated rats (6 males, 2 females) died during the study, five of them (4 males, 1 female) from among those receiving the highest dose (5,000 mg/kg). According to necropsy, all deaths were related to gavage manipulation of higher doses. Although the differences were not significant, body weight gain and food consumption in the groups receiving 2,500 or 5,000 mg/kg tended to be lower than in the control group. Nevertheless, no drug-related toxicity symptoms were detected. Analysis of blood biochemistry, hematology, organ weight ratios, and histopathological findings did not show significant differences compared with controls, nor any tendency with the dose. Therefore, the present study did not show any new evidence of oral toxicity of policosanol, and the findings observed were a consequence of long-term administration by gastric gavage of the highly concentrated suspensions needed to reach the higher doses. It is concluded that policosanol chronically administered by the oral route is safe and that no drug-related toxicity was demonstrated.

Modulation of COX-2 expression by statins in human aortic smooth muscle cells. Involvement of geranylgeranylated proteins

Cyclooxygenase (COX)-2 and COX-1 play an important role in prostacyclin production in vessels and participate in maintaining vascular homeostasis. Statins are inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase, which is crucial in cholesterol biosynthesis. Recently, cholesterol-independent effects of statins have been described. In this study, we evaluated the effect of two inhibitors of HMG CoA reductase, mevastatin and lovastatin, on the production of prostacyclin and the expression of COX in human aortic smooth muscle cells. Treatment of cells with 25 microm mevastatin or lovastatin resulted in the induction of COX-2 and increase in prostacyclin production. Mevalonate, the direct metabolite of HMG CoA reductase, and geranylgeranyl-pyrophosphate reversed this effect. GGTI-286, a selective inhibitor of geranylgeranyltransferases, increased COX-2 expression and prostacyclin formation, thus indicating the involvement of geranylgeranylated proteins in the down-regulation of COX-2. Furthermore, Clostridium difficile toxin B, an inhibitor of the Rho GTP-binding protein family, the Rho selective inhibitor C3 transferase, and Y-27632, a selective inhibitor of the Rho-associated kinases, targets of Rho A, increased COX-2 expression whereas the activator of the Rho GTPase, the cytotoxic necrotizing factor 1, blocked interlukin-1alpha-dependent COX-2 induction. These results demonstrate that statins up-regulate COX-2 expression and subsequent prostacyclin formation in human aortic smooth muscle cells in part through inhibition of Rho.

Simvastatin induces regression of cardiac hypertrophy and fibrosis and improves cardiac function in a transgenic rabbit model of human hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy is a genetic disease characterized by cardiac hypertrophy, myocyte disarray, interstitial fibrosis, and left ventricular (LV) dysfunction. We have proposed that hypertrophy and fibrosis, the major determinants of mortality and morbidity, are potentially reversible. We tested this hypothesis in beta-myosin heavy chain-Q(403) transgenic rabbits.

METHODS AND RESULTS

We randomized 24 beta-myosin heavy chain-Q(403) rabbits to treatment with either a placebo or simvastatin (5 mg. kg(-1). d(-1)) for 12 weeks and included 12 nontransgenic controls. We performed 2D and Doppler echocardiography and tissue Doppler imaging before and after treatment. Demographic data were similar among the groups. Baseline mean LV mass and interventricular septal thickness in nontransgenic, placebo, and simvastatin groups were 3.9+/-0.7, 6.2+/-2.0, and 7.5+/-2.1 g (P<0.001) and 2.2+/-0.2, 3.1+/-0.5, and 3.3+/-0.5 mm (P=0.002), respectively. Simvastatin reduced LV mass by 37%, interventricular septal thickness by 21%, and posterior wall thickness by 13%. Doppler indices of LV filling pressure were improved. Collagen volume fraction was reduced by 44% (P<0.001). Disarray was unchanged. Levels of activated extracellular signal-regulated kinase (ERK) 1/2 were increased in the placebo group and were less than normal in the simvastatin group. Levels of activated and total p38, Jun N-terminal kinase, p70S6 kinase, Ras, Rac, and RhoA and the membrane association of Ras, RhoA, and Rac1 were unchanged.

CONCLUSIONS

Simvastatin induced the regression of hypertrophy and fibrosis, improved cardiac function, and reduced ERK1/2 activity in the beta-myosin heavy chain-Q(403) rabbits. These findings highlight the need for clinical trials to determine the effects of simvastatin on cardiac hypertrophy, fibrosis, and dysfunction in humans with hypertrophic cardiomyopathy and heart failure.

Inhibition of interferon-gamma-mediated microvascular endothelial cell major histocompatibility complex class II gene activation by HMG-CoA reductase inhibitors

BACKGROUND

Graft vascular disease, a major cause of late graft failure in cardiac transplant patients, is associated with the presence of class II major histocompatibility complex molecules on the endothelium. 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase inhibitors, e.g., simvastatin, have been shown to reduce the incidence of graft vascular disease. We studied the effect of simvastatin on interferon (IFN)-gamma-induced human leukocyte antigen (HLA)-DR expression in human microvascular endothelial cells (MVECs).

METHODS AND RESULTS

Simvastatin pretreatment inhibited MVEC HILA-DR induction by IFN-gamma, as detected by flow cytometry. Simvastatin's inhibitory effect was reversed by the cholesterol synthesis pathway intermediates mevalonate and geranylgeranyl pyrophosphate but not squalene, indicating the involvement of protein prenylation in this process. Reverse transcription-polymerase chain reaction analysis demonstrated that induction of class II transactivator (CIITA), and consequently, HLA-DRalpha mRNA, is abrogated by simvastatin. Although signal transducer and activator of transcription (STAT)-1 is a critical CIITA gene transactivator, immunofluorescence studies, Western blotting, and electrophoretic mobility shift assays demonstrated that IFN-gamma-induced STAT-1 phosphorylation, nuclear translocation, and DNA binding are not affected by simvastatin. However, simvastatin inhibited IFN-gamma-induced transactivation of a CIITA promoter IV reporter construct, indicating the involvement of this promoter in the inhibitory effect of simvastatin.

CONCLUSIONS

Simvastatin pretreatment inhibits CIITA and consequent HLA-DR induction by IFN-gamma in MVECs through interference with protein prenylation. This inhibitory effect occurs at the level of transcription and is directed, at least in part, at the CIITA promoter IV. These results explain some of the beneficial effects of HMG-CoA reductase inhibitors in cardiac transplantation.