Fenofibrate inhibits thrombogenic and fibrinolytic factors expression in adipose tissue of atherosclerotic rabbits

Use of Lipid-Lowering Drugs After Intracerebral Hemorrhage

Hyperlipidemia is common in patients with intracerebral hemorrhage (ICH). Accumulating evidence indicates that patients with ICH are at risk for future hemorrhage recurrence, cardiovascular disease, and ischemic stroke and highlights the importance of secondary prevention of vascular events after ICH. Although the benefits of intensive treatment of hyperlipidemia for reducing ischemic cardiac and vascular events in patients with ischemic stroke are well established, the benefit versus harm in patients with ICH are less clear. Epidemiological studies suggest that hyperlipidemia is protective against ICH and that intensive lowering of lipids is associated with increased risk for ICH. Similarly, although currently available lipid-lowering treatments have been thoroughly studied in patients with ischemic cardiac and vascular disease, only few randomized trials of these therapies included a very small number of patients with history of ICH. Thus, limiting any definitive conclusions regarding the safety and net benefit of these treatments in ICH populations. Currently, there is no consensus regarding the optimal strategy for management of hyperlipidemia after ICH. In this article, we review relevant literature to outline the competing risks and benefits of lipid-lowering treatments in this vulnerable patient population. We suggest a treatment paradigm based on available data but note that data from dedicated randomized trials are needed to build the necessary evidence to guide optimal lipid-lowering strategy in patients with a history of ICH.

Safety considerations with fibrate therapy

Fibrates are an important class of drugs for the management of dyslipidemia. This class of drugs is generally well tolerated but is infrequently associated with several safety issues. Fibrates, most likely by an effect mediated by peroxisome proliferator-activated receptor-alpha, may reversibly increase creatinine and homocysteine but are not associated with an increased risk for renal failure in clinical trials. Fibrates are associated with a slightly increased risk (<1.0%) for myopathy, cholelithiasis, and venous thrombosis. In clinical trials, patients without elevated triglycerides and/or low high-density lipoprotein cholesterol (HDL) levels, fibrates are associated with an increase in noncardiovascular mortality. In combination with statins, gemfibrozil generally should be avoided. The preferred option is fenofibrate, which is not associated with an inhibition of statin metabolism. Clinicians are advised to measure serum creatinine before fibrate use and adjust the dose accordingly for renal impairment. Routine monitoring of creatinine is not required, but if a patient has a clinically important increase in creatinine, and other potential causes of creatinine increase have been excluded, consideration should be given to discontinuing fibrate therapy or reducing the dose.

Atorvastatin reduces tissue factor expression in adipose tissue of atherosclerotic rabbits

BACKGROUND

We have recently demonstrated that tissue factor (TF) expression increases in adipose tissues/adipocytes of cholesterol-fed rabbit, which is associated with a hypercoagulable state that contributes to thrombosis. In this study, we evaluated the ability of atorvastatin to modulate TF expression in cholesterol-fed rabbit and the regulatory mechanism.

METHODS

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

RESULTS

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

CONCLUSIONS

Results provide further support for the antithrombotic effect of atorvastatin. It also indicated that mevalonate pathway may play an important role in TF expression in adipocyte.

Paradoxical effects of fenofibrate and nicotinic acid in apo E-deficient mice

Atherosclerosis is a complex vascular disease initiated by abnormal accumulation of plasma lipoproteins in the subendothelial space. Elevated levels of plasma triglycerides (TG) and low-density lipoprotein (LDL)-cholesterol as well as low concentrations of high-density lipoprotein (HDL) play a causal role in the development and progression of atherosclerotic lesions. We have shown that apolipoprotein E-deficient (apo E-KO) mice have elevated triglyceride levels plus diminished HDL concentrations. Drugs such as fenofibrate and nicotinic acid are well known to reduce TG and increase HDL levels in humans. In this study, we investigated the beneficial effects of fenofibrate and niacin on lipid profile and atherogenesis in apo E-KO mice and their wild-type counterparts. Animals were fed with a cholesterol-enriched diet supplemented with fenofibrate (0.1% wt/wt, n = 8) or nicotinic acid (0.5% wt/wt, n = 8) for 14 weeks. Body weights were recorded weekly, and plasma lipid profiles were determined at 4-week intervals. The hearts and aortas were collected and fixed for histologic and morphometric evaluations of atherosclerotic lesions. Fenofibrate treatment in apo E-KO mice paradoxically increased total cholesterol and TG by 65% and 44%, respectively, and decreased HDL-cholesterol levels by 35% as compared with controls. Similar effects of fenofibrate on cholesterol levels, but not on TG concentrations, were observed in C57BL/6 mice. Fenofibrate-treated mice had lower body weight as compared with controls. Niacin had no effect on body weight gain but failed to decrease TG or to increase HDL levels in either apo E-KO mice or their wild-type counterparts. Neither fenofibrate nor niacin significantly influenced atherogenesis in apo E-KO mice as compared with controls. In conclusion, this study shows that neither niacin nor fenofibrate has beneficial lipid-modifying and antiatherosclerosis activities in mice. Identification of mechanisms underlying paradoxical effects of fenofibrate on lipoprotein metabolisms in apo E-KO mice merits further investigation.

Renoprotective effects of fenofibrate in diabetic rats are achieved by suppressing kidney plasminogen activator inhibitor-1

To investigate mechanisms of protective effects of fenofibrate on the diabetic kidney, male Wistar rats were divided into control, untreated diabetes, and fenofibrate-treated (32 mg kg(-1) d(-1), 8 weeks) diabetes groups. Diabetes induced by streptozotocin (25 mg/kg) and a high-fat diet was characterized by the disorders of plasma glucose and lipids. In untreated diabetic rats, there were increases in glomerular volume, matrix content, expressions of laminin and urinary albumin excretion. These nephropathies were associated with the upregulations of plasminogen activator inhibitor 1 (PAI-1) mRNA expression and its protein activity in the renal cortex, and a significant increase in transforming growth factor beta1 (TGF-beta1) expression. Treatment with fenofibrate suppressed the expression of PAI-I mRNA and its protein activity, and inhibited TGF-beta1 overexpression. It also partially reversed metabolic disorders and pathophysiologic changes associated with diabetic nephropathy. Our results indicate that fenofibrate delays the progression of diabetic nephropathy in rats to some extent. These renoprotective effects are likely to be achieved through suppression of PAI-1 and TGF-beta1 in the renal cortex, and consequently less extracellular matrix deposition.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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