Endothelial Microparticle Formation by Angiotensin II Is Mediated via Ang II Receptor Type I/NADPH Oxidase/ Rho Kinase Pathways Targeted to Lipid Rafts

Burger, D., Montezano, A. C., Nishigaki, N., He, Y., Carter, A. and Touyz, R. M. (2011) Endothelial Microparticle Formation by Angiotensin II Is Mediated via Ang II Receptor Type I/NADPH Oxidase/ Rho Kinase Pathways Targeted to Lipid Rafts. Arteriosclerosis, Thrombosis, and Vascular Biology, 31(8), pp. 1898-1907. (doi: 10.1161/ATVBAHA.110.222703)

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Abstract

Objective—Circulating microparticles are increased in cardiovascular disease and may themselves promote oxidative stress and inflammation. Molecular mechanisms underlying their formation and signaling are unclear. We investigated the role of reactive oxygen species (ROS), Rho kinase, and lipid rafts in microparticle formation and examined their functional significance in endothelial cells (ECs). Methods and Results—Microparticle formation from angiotensin II (Ang II)–stimulated ECs and apolipoprotein E−/− mice was assessed by annexin V or by CD144 staining and electron microscopy. Ang II promoted microparticle formation and increased EC Graphic generation and Rho kinase activity. Ang II–stimulated effects were inhibited by irbesartan (Ang II receptor type I blocker) and fasudil (Rho kinase inhibitor). Methyl-β-cyclodextrin and nystatin, which disrupt lipid rafts/caveolae, blocked microparticle release. Functional responses, assessed in microparticle-stimulated ECs, revealed increased Graphic production, enhanced vascular cell adhesion molecule/platelet-EC adhesion molecule expression, and augmented macrophage adhesion. Inhibition of epidermal growth factor receptor blocked the prooxidative and proinflammatory effects of microparticles. In vitro observations were confirmed in apolipoprotein E−/− mice, which displayed vascular inflammation and high levels of circulating endothelial microparticles, effects that were reduced by apocynin. Conclusion—We demonstrated direct actions of Ang II on endothelial microparticle release, mediated through NADPH oxidase, ROS, and Rho kinase targeted to lipid rafts. Microparticles themselves stimulated endothelial ROS formation and inflammatory responses. Our findings suggest a feedforward system whereby Ang II promotes EC injury through its own endothelial-derived microparticles.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Touyz, Professor Rhian
Authors: Burger, D., Montezano, A. C., Nishigaki, N., He, Y., Carter, A., and Touyz, R. M.
College/School:College of Medical Veterinary and Life Sciences > School of Cardiovascular & Metabolic Health
Journal Name:Arteriosclerosis, Thrombosis, and Vascular Biology
Publisher:American Heart Association
ISSN:1079-5642
ISSN (Online):1524-4636
Published Online:19 May 2011

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