Abstract 080: Endothelin-1 Exaggerates Type-1 Diabetes-Accelerated Atherosclerosis Through NADPH Oxidase 1

Abstract

Introduction: NADPH oxidase (NOX) 1 but not NOX4-dependent oxidative stress plays a role in diabetic vascular disease, including atherosclerosis. Endothelin (ET)-1 has been implicated in diabetes-induced vascular complications. We showed that crossing mice overexpressing ET-1 selectively in endothelium (eET-1) with apolipoprotein E knockout ( Apoe -/- ) mice exaggerated high-fat diet-induced atherosclerosis in part by increasing oxidative stress. We hypothesized that ET-1 overexpression in the endothelium would exaggerate diabetes-accelerated atherosclerosis through a mechanism involving NOX1 but not NOX4. Methods: Six-week-old male Apoe -/- mice, eET-1/ Apoe -/- and eET-1/ Apoe -/- mice deficient in Nox1 (eET-1/ Apoe -/- / Nox1 y/- ) or Nox4 (eET-1/ Apoe -/- / Nox4 -/- ) were rendered diabetic with 55 mg/kg/day streptozotocin (STZ) IP for 5 days and studied 14 weeks later. Aortic atherosclerotic lesions were quantified using Oil Red O staining. Monocyte/macrophage infiltration and alpha-smooth muscle actin area were determined by immunofluorescence in aortic atherosclerotic lesions. Plasma cholesterol, HDL and triglycerides were measured. Results: ET-1 overexpression exaggerated 2.5-fold the atherosclerotic lesion area of the aortic sinus in diabetic Apoe -/- mice (plaque area [x10 5 μm 2 ]: 5.3±0.2 vs 2.1±0.4, P <0.05), which was reduced ~35% by Nox1 (3.5±0.4 x10 5 μm 2 , P <0.05) but not Nox4 knockout (5.0±0.7 x10 5 μm 2 ). Monocyte/macrophage infiltration was reduced ~30% in diabetic eET-1/ Apoe -/- and eET-1/ Apoe -/- / Nox4 -/- mice (31±1 and 35±2 vs 48±5% of lesion area, P <0.05) but not eET-1/ Apoe -/- / Nox1 y/- mice (35±2%). ET-1 overexpression decreased alpha-smooth muscle actin content by ~35% (9±1 vs 14±2% of lesion area, P <0.05), which was blunted by Nox1 (15±2%, P <0.05) but not Nox4 knockout (9±1%). Plasma triglycerides were unaffected by ET-1 overexpression (3.4±0.3 vs 3.6±0.5 mmol/L) but reduced by Nox1 and Nox4 knockout (2.2±0.4 and 1.8±0.4 mmol/L, P <0.05). Plasma HDL and cholesterol were similar between groups. Conclusions: Endothelium ET-1 overexpression exaggerates diabetes-accelerated atherosclerosis and reduces plaque stability through NOX1.