Effects of oxidized and glycated low-density lipoproteins on transcription and secretion of plasminogen activator inhibitor-1 in vascular endothelial cells.

Plasminogen activator inhibitor-1 (PAI-1) is the major physiological inhibitor of fibrinolysis. Elevated levels of PAI-1 were frequently detected in patients with coronary artery disease (CAD) or diabetes. Low-density lipoprotein (LDL) is a classical risk factor of CAD. Oxidation and glycation increase the atherogenecity of LDL. Previous studies demonstrated that oxidized LDL (oxLDL) or glycated LDL (gly-LDL) increased the release of PAI-1 from endothelial cells (ECs). The present study examined the effects of oxLDL and gly-LDL on the transcription, expression, secretion, and subcellular distribution of PAI-1 in cultured human ECs. Treatment with LDL significantly increased the promoter activity, mRNA level, and the release of PAI-1 from ECs by two- to threefold compared to controls. Oxidation or glycation significantly enhanced the effects of LDL on PAI-1 production in ECs compared to LDL (four- to fivefold vs. controls). No significant differences were detected between the effects of oxLDL and gly-LDL. Abundant PAI-1 antigens were detected in the perinuclear region of ECs and overlapped with giantin, a marker of Golgi apparatus. Treatment with brefeldin A disturbed the stack structure of Golgi apparatus and almost completely inhibited the release of PAI-1 from ECs induced by the lipoproteins and at basal conditions. The results suggest that oxidation and glycation enhanced the effects of LDL on the production of PAI-1 in ECs through increasing the transcription of PAI-1. Intact Golgi apparatus is required for PAI-1 generation from ECs induced by LDL or its modified forms.

Effects of losartan on urinary secretion of extracellular matrix and their modulators in type 2 diabetes mellitus patients with microalbuminuria.

PURPOSE: Angiotensin II receptor Type 1 antagonists postpone the development of nephropathy in type 2 diabetes mellitus (DM). We hypothesize that Losartan may ameliorate renal function in diabetic patients through the regulation on the generation of transforming growth factor (TGF)-beta and fibrinolytic regulators. METHODS: Twenty-two type 2 DM patients with microalbuminuria were treated with 50-100 mg/day of Losartan for 6 months. Urinary secretion of TGF-, plasminogen activator inhibitor-1 (PAI-1), tissue and urokinase plasminogen activators (tPA and uPA) fibronectin, collagen IV and plasma levels of TGF-beta, PAI-1, tPA and uPA of the patients before and after the treatment were analyzed using enzyme-linked immunoabosorbance assay. RESULTS: Losartan effectively reduced arterial blood pressure and urinary albumin excretion. The levels of TGF-beta in urine, but not in plasma, were reduced after 2, 4 and 6 months of the treatment (-32% to -48%, P < 0.05 or 0.01). Urinary or plasma levels of PAI-1, tPA or uPA, and urinary secretion of fibronectin or collagen IV were not significantly altered by Losartan treatment. Urinary levels of collagen IV positively correlated with uPA, and that of fibronectin negatively correlated with PAI-1 in the patients (P < 0.01). Urinary TGF-beta negatively correlated uPA in urine of the patients (P < 0.01). CONCLUSION: Losartan reduced urinary excretion of TGF-beta and albumin in type 2 DM patients with microalbuminuria. Fibrinolytic regulators and TGF-beta are implicated in the regulation of ECM turnover in kidneys of the patients with diabetic nephropathy.

Impact of simvastatin on hemostatic and fibrinolytic regulators in Type 2 diabetes mellitus.

Simvastatin, a widely used 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitor, effectively reduced cardiac death and ischemic events in patients with coronary heart disease (CHD) and diabetes mellitus (DM). The mechanism of cardiovascular benefits of statins in DM remains unclear. We examined how simvastatin influences the levels of several in vivo markers for coagulation and fibrinolysis in 26 Type 2 DM patients. The diabetic patients received 20 mg/day of simvastatin up to 12 months. The levels of total cholesterol (TC), low density lipoprotein-cholesterol (LDL-c) and triglycerides in peripheral circulation of patients were significantly reduced after > or =6 weeks of simvastatin treatment. Levels of prothrombin fragment 1+2 (F1+2), factor VII, plasminogen activator inhibitor-1 (PAI-1) and tissue factor pathway inhibitor (TFPI) antigens, but not tissue plasminogen activator (tPA) antigen, in the pre-simvastatin plasmas of the diabetic patients were significantly higher than the levels found in plasmas of healthy subjects. Significant reductions in F1+2 and PAI-1 levels were evident > or =6 weeks after the diabetic patients received simvastatin. Levels of total tPA, TFPI, FVII, hemoglobin A1c, fasting blood glucose, and insulin in the diabetic patients' plasma were not significantly altered by simvastatin treatment. Positive correlations were found between PAI-1 versus TC, PAI-1 versus LDL-c, and FVII versus triglycerides in the plasmas of simvastatin-treated patients. The results suggest that simvastatin reduces in vivo prothrombinase activity and PAI-1 levels in type 2 DM patients. These actions may contribute to the protective properties of simvastatin against ischemic events in diabetic patients.