Urotensin II receptor antagonism confers vasoprotective effects in diabetes associated atherosclerosis: studies in humans and in a mouse model of diabetes.

AIMS/HYPOTHESIS: The small, highly conserved vasoactive peptide urotensin II (UII) is upregulated in atherosclerosis. However, its effects in diabetes-associated atherosclerosis have not been assessed. METHODS: Endothelial cells were grown in normal- and high-glucose (5 and 25 mmol/l) media with and without UII (10⁻8 mol/l) and/or the UII receptor antagonist, SB-657510 (10⁻8 mol/l). Apoe knockout (KO) mice with or without streptozotocin-induced diabetes were treated with or without SB-657510 (30 mg kg⁻¹ day⁻¹; n = 20 per group) and followed for 20 weeks. Carotid endarterectomy specimens from diabetic and non-diabetic humans were also evaluated. RESULTS: In high (but not normal) glucose medium, UII significantly increased CCL2 (encodes macrophage chemoattractant protein 1 [MCP-1]) gene expression (human aortic endothelial cells) and increased monocyte adhesion (HUVECs). UII receptor antagonism in diabetic Apoe KO mice significantly attenuated diabetes-associated atherosclerosis and aortic staining for MCP-1, F4/80 (macrophage marker), cyclooxygenase-2, nitrotyrosine and UII. UII staining was significantly increased in carotid endarterectomies from diabetic compared with non-diabetic individuals, as was staining for MCP-1. CONCLUSIONS/INTERPRETATION: This is the first report to demonstrate that UII is increased in diabetes-associated atherosclerosis in humans and rodents. Diabetes-associated plaque development was attenuated by UII receptor antagonism in the experimental setting. Thus UII may represent a novel therapeutic target in the treatment of diabetes-associated atherosclerosis.

Vascular endothelial dysfunction in cyclosporine-treated rat aortas is not associated with serum total homocysteine levels.

OBJECTIVES: Elevation of serum total homocysteine (tHcy) is considered to contribute to endothelial cell dysfunction, which is considered to be the initial event in posttransplant vascular disease. We sought to investigate whether an association existed between serum tHcy levels and vascular endothelial function during cyclosporine (CsA) treatment. MATERIALS AND METHODS: Endothelium-dependent and -independent relaxation responses (to acetylcholine [ACh] and sodium nitroprusside [SNP]) were determined on thoracic aortae from CsA-treated rats (5 mg kg/d, subcutaneously, for 14 days). A correlation analysis was performed between ACh responses and tHcy levels. RESULTS: CsA decreased the responses to ACh and the pD(2) values of the concentration-response curves compared with controls (P < .05). Responses to SNP and serum tHcy levels were unchanged among the groups. tHcy negatively correlated with the ACh pD(2) values among control (r = -0.69; P < .05) and vehicle (r = -0.73; P < .05) groups, indicating that the increase in tHcy was associated with decreased sensitivity to ACh. In CsA-treated rats, no association was observed between these parameters. Also, no correlation was noted between CsA concentrations and tHcy levels. CONCLUSION: These data suggested a possible link between serum tHcy and decreased vascular sensitivity to endothelium-dependent vasorelaxation in control aortae, but CsA-induced vascular endothelial dysfunction was not associated with an effect of the drug on homocysteine metabolism.