Endoglin as a possible marker of atorvastatin treatment benefit in atherosclerosis.

Endoglin (a type III TGF-ß receptor) is able to modulate ligand binding and signaling by association with the TGF-ß type I receptors (ALK-1 and ALK-5). In this study, we hypothesized whether atorvastatin treatment affects endoglin/ALK-1/p-Smad1/VEGF expression in the aorta and endoglin levels in serum in ApoE/LDLR double knockout mice. ApoE/LDLR double knockout mice were fed with a diet containing either 1% of cholesterol (CHOL) or cholesterol with atorvastatin (ATV) at a dose of 50mg/kg/day. Biochemical analysis of cholesterol levels and ELISA analysis of endoglin levels in serum, lesion area size, immunohistochemistry and Western blot analysis in mice aorta were performed. Atorvastatin treatment resulted in a significant decrease of total, VLDL and LDL cholesterol, atherosclerotic lesion size and endoglin serum levels in comparison with CHOL mice. On the other hand, atorvastatin treatment significantly increased the expressions of endoglin by 1431%, ALK-1 by 310%, p-Smad1 by 135% and VEGF by 62% in aorta when compared to CHOL mice. In conclusion, it has been demonstrated that atorvastatin increases endoglin/ALK-1/p-Smad1/VEGF expression in aorta and decreases the size of atherosclerotic lesions, suggesting that activation of this endothelial-protective pathway might support the antiatherogenic effects of atorvastatin. Moreover, atorvastatin concurrently decreased serum levels of endoglin suggesting that monitoring of endoglin levels in blood might represent an important marker of the progression and/or treatment of atherosclerosis.

Cholesterol effects on endoglin and its downstream pathways in ApoE/LDLR double knockout mice.

BACKGROUND: The aim of the study was to evaluate whether cholesterol-rich diet affects transforming growth factor-ß-RIII (endoglin) levels in blood and 2 endoglin-related pathways in the aorta of ApoE/LDLR double knockout mice. METHODS AND RESULTS: Mice were fed either chow diet (CHOW) (n=8) or by 1% cholesterol-rich diet (CHOL) (n=8). Biochemical analysis of cholesterol and endoglin levels in blood, lesion size area, immunohistochemistry and Western blot analysis in mice aortas were performed. Biochemical analysis showed that cholesterol-rich diet resulted in a significant increase of cholesterol and endoglin levels in serum, and increased plaque size in the aorta. In addition, a cholesterol-rich diet significantly decreased the expressions of endoglin by 92%, activin receptor-like kinase (ALK)-1 by 71%, p-Smad2 by 21%, and vascular endothelial growth factor (VEGF) by 37% when compared to CHOW mice, but ALK-5, p-Smad1, and endothelial nitric oxide synthase were not significantly affected. CONCLUSIONS: Hypercholesterolemia increases endoglin levels in blood and simultaneously decreases its expression in aorta, together with atherosclerosis protective markers p-Smad2 and VEGF, followed by increased plaque size. Inhibition of endoglin signaling might be one of the mechanisms responsible for the promoting of endothelial dysfunction and atherogenesis. Moreover, the monitoring of endoglin serum levels might represent an attractive blood marker of progression of disease; however, the precise source and role of endoglin in blood serum remains to be elucidated.

Pravastatin modulates liver bile acid and cholesterol homeostasis in rats with chronic cholestasis.

BACKGROUND AND AIM: The administration of pravastatin to patients with cholestatic liver disease has suggested the potential of the drug with regard to reducing raised plasma cholesterol and bile acid levels. Information about the mechanisms associated with this effect is lacking. Thus, the aim of the present study is to evaluate pravastatin effects on the liver bile acid and cholesterol homeostasis in healthy and cholestatic rats. METHODS: Control sham-operated and reversibly bile duct-obstructed (BDO) rats were treated with pravastatin (1 or 5 mg/kg) or the vehicle alone for 7 days after surgery. RESULTS: Lower doses of pravastatin reduced bile acid plasma concentrations in cholestatic animals. The effect was associated with reduced liver mRNA expression of Cyp7a1, Cyp8b1, Mrp2, Ugt1a1 and the increased expression of Bsep. In addition, BDO-induced increase in the liver content of cholesterol was normalized by pravastatin. The change was accompanied by the reduced liver expression of Hmg-CoA reductase, LDL receptor, and Acat2, and induced the expression of Abca1 and Mdr2. These changes corresponded with the upregulation of nuclear receptors LXRα and PPARα, and the downregulation of FXR, CAR, SREBP-2 and HNF1α. High doses of pravastatin lacked any positive effects on bile acids and cholesterol homeostasis, and blocked bile formation through the reduction of the biliary excretion of bile acids. CONCLUSIONS: Pravastatin rendered a positive reduction in BDO-induced increases in plasma bile acid concentrations and cholesterol liver content, mainly through the transcriptionally-mediated downregulation of genes involved in the synthesis of these compounds in the liver.

Activation of TGF-ß receptors and Smad proteins by atorvastatin is related to reduced atherogenesis in ApoE/LDLR double knockout mice.

AIM: Transforming growth factor-beta (TGF-ß) plays important role in atherogenesis via TGF-ß receptors and Smad proteins, which determine its signaling activity. In this study, we hypothesized, whether non-lipid related effects of atorvastatin, affect both endoglin/ALK-5/Smad2/eNOS and/or endoglin/ALK-1/Smad1/VEGF previously proposed pathways in ApoE/LDLR double knockout mice. METHODS: ApoE/LDLR double knockout mice were divided into two groups. The chow group (CHOW) (n =8) was fed with chow diet, while in the atorvastatin group (ATV) (n =8) atorvastatin was added to the chow diet at dose 50 mg/kg/day. Biochemical analyses of lipid profile, lesion area measurement, immunohistochemistry and Western blot analysis of endoglin, ALK-1, 5, phosphorylated and non-phosphorylated forms Smad-1, 2, VEGF and eNOS proteins in mice aorta were performed. RESULTS: Biochemical analysis of blood serum and morphometric analysis of aortic lesion size showed that atorvastatin treatment resulted in a significant increase of cholesterol levels and simultaneously in reduced lesion size in aortic sinus when compared to CHOW mice. Western blot analysis revealed that atorvastatin treatment significantly increase the expressions of endoglin by 102%, ALK-1 by 113%, ALK-5 by 296%, pSmad-1 by 202%, pSmad-2 by 34%, VEGF by 68% and eNOS by 687% as compared with CHOW mice. Immunofluorescence staining revealed endoglin coexpression with all studied markers that were increased by atorvastatin treatment mainly in endothelial cells covering atherosclerotic plaques. CONCLUSION: This study shows that atorvastatin treatment increases the expression of endoglin, ALK-1, ALK-5, phosphorylated forms of Smad1 and Smad2, VEGF and eNOS and reduces atherosclerotic lesion size beyond its lipid lowering effects. Therefore, we propose that endoglin related receptors and signal transducers might play protective role in atherogenesis.