EphA2 knockdown attenuates atherosclerotic lesion development in ApoE-/- mice

Background: The inflammatory response of vascular endothelial cells plays important roles in the initiation and progression of atherosclerotic lesions. EphA2 receptor activation promotes the endothelial cell inflammatory response, and its expression is increased in the endothelial cell layer of atherosclerotic plaques. However, the association between EphA2 and atherosclerosis has not been determined. Methods: Eight-week-old male ApoE(-/-) mice were systemically infected with adenoassociated virus serotype 9 carrying a small hairpin RNA specifically targeting the EphA2 gene to knock down EphA2 expression in aortic endothelial cells. These mice were then fed a high-cholesterol diet for 12 weeks. Blood was collected for the measurement of plasma lipids. The aortas were harvested to evaluate the atherosclerotic lesion size, macrophage components, and expression of proinflammatory genes using Oil Red O staining, immunofluorescence staining, and molecular biology analysis. Results: The lesions formed in the entire aorta and aortic sinus of the ApoE-/- mice with EphA2 knockdown were significantly smaller than those in the control mice (10.7% +/- 3.1% versus 25.1% +/- 4.2%; 0.51 +/- 0.02 mm(2) versus 0.85 +/- 0.03 mm2; n = 10; P <.05). Furthermore, the lesions in the ApoE-/- mice with EphA2 knockdown displayed reduced inflammation compared with the control mice, as reflected by the decreased macrophage infiltration (8.2% +/- 2.9% versus 22.7% +/- 4%; n = 10; P <.05); decreased nuclear factor-kappa beta activation; and diminished expression of vascular cell adhesion molecule-1, E-selectin, and monocyte chemotactic protein-1 (all P <.05). Conclusions: Our data demonstrate that the EphA2 receptor silencing attenuates the extent and inflammation of atherosclerotic lesions in ApoE-/- mice. Thus, EphA2 knockdown in endothelial cells represents a novel therapeutic strategy for patients with atherosclerosis. (c) 2014 Elsevier Inc. All rights reserved.