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Molecular imaging of inflammation and platelet adhesion in advanced atherosclerosis effects of antioxidant therapy with NADPH oxidase inhibition.

ABSTRACT: In atherosclerosis, local generation of reactive oxygen species amplifies the inflammatory response and contributes to plaque vulnerability. We used molecular imaging to test whether inhibition of NADPH oxidase with apocynin would reduce endothelial inflammatory activation and endothelial-platelet interactions, thereby interrupting progression to high-risk plaque phenotype.Mice deficient for both the low-density lipoprotein receptor and Apobec-1 were studied at 30 weeks of age and again after 10 weeks with or without apocynin treatment (10 or 50 mg/kg per day orally). In vivo molecular imaging of vascular cell adhesion molecule-1 (VCAM 1) P-selectin, and platelet glycoprotein-1b? (GPIb?) in the thoracic aorta was performed with targeted contrast-enhanced ultrasound molecular imaging. Arterial elastic modulus and pulse wave transit time were assessed using ultrahigh frequency ultrasound and invasive hemodynamic measurements. Plaque size and composition were assessed by histology. Molecular imaging in nontreated mice detected a 2-fold increase in P-selectin expression, VCAM-1 expression, and platelet adhesion between 30 and 40 weeks of age. Apocynin reduced all of these endothelial events in a dose-dependent fashion (25% and 50% reduction in signal at 40 weeks for low- and high-dose apocynin). Apocynin also decreased aortic elastic modulus and increased the pulse transit time. On histology, apocynin reduced total monocyte accumulation in a dose-dependent manner as well as platelet adhesion, although total plaque area was reduced in only the high-dose apocynin treatment group.Inhibition of NADPH oxidase in advanced atherosclerosis reduces endothelial activation and platelet adhesion, which are likely responsible for the arrest of plaque growth and improvement of vascular mechanical properties.

SUBMITTER: Liu Y

PROVIDER: S-EPMC3575135 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature

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Molecular imaging of inflammation and platelet adhesion in advanced atherosclerosis effects of antioxidant therapy with NADPH oxidase inhibition.

Liu Yani Y Davidson Brian P BP Yue Qi Q Belcik Todd T Xie Aris A Inaba Yoichi Y McCarty Owen J T OJ Tormoen Garth W GW Zhao Yan Y Ruggeri Zaverio M ZM Kaufmann Beat A BA Lindner Jonathan R JR

Circulation. Cardiovascular imaging 20121213 1

<h4>Background</h4>In atherosclerosis, local generation of reactive oxygen species amplifies the inflammatory response and contributes to plaque vulnerability. We used molecular imaging to test whether inhibition of NADPH oxidase with apocynin would reduce endothelial inflammatory activation and endothelial-platelet interactions, thereby interrupting progression to high-risk plaque phenotype.<h4>Methods and results</h4>Mice deficient for both the low-density lipoprotein receptor and Apobec-1 wer ...[more]

PMID: 23239832

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Project description:Trypanosoma cruzi, the aetiological agent of Chagas disease, invades nucleated mammalian cells including macrophages. In this study, we investigated the crosstalk between T. cruzi-induced immune activation of reactive oxygen species (ROS) and pro-inflammatory responses, and their role in myocardial pathology. Splenocytes of infected mice (C3H/HeN) responded to Tc-antigenic stimulus by more than a two-fold increase in NADPH oxidase (NOX) activity, ROS generation, cytokine production (IFN-? > IL-4 > TNF? > IL1-?? IL6), and predominant expansion of CD4(+) and CD8(+) T cells. Inhibition of NOX, but not of myeloperoxidase and xanthine oxidase, controlled the ROS (>98%) and cytokine (70-89%) release by Tc-stimulated splenocytes of infected mice. Treatment of infected mice with apocynin (NOX inhibitor) in drinking water resulted in a 50-90% decline in endogenous NOX/ROS and cytokine levels, and splenic phagocytes' proliferation. The splenic percentage of T cells was maintained, though more than a 40% decline in splenic index (spleen weight/body weight) indicated decreased T-cell proliferation in apocynin-treated/infected mice. The blood and tissue parasite burden were significantly increased in apocynin-treated/infected mice, yet acute myocarditis, ie inflammatory infiltrate consisting of macrophages, neutrophils, and CD8(+) T cells, and tissue oxidative adducts (eg 8-isoprostanes, 3-nitrotyrosine, and 4-hydroxynonenal) were diminished in apocynin-treated/infected mice. Consequently, hypertrophy (increased cardiomyocytes' size and ?-MHC, BNP, and ANP mRNA levels) and fibrosis (increased collagen, glycosaminoglycans, and lipid contents) of the heart during the chronic phase were controlled in apocynin-treated mice. We conclude that NOX/ROS is a critical regulator of the splenic response (phagocytes, T cells, and cytokines) to T. cruzi infection, and bystander effects of heart-infiltrating phagocytes and CD8(+) T cells resulting in cardiac remodelling in chagasic mice.

Dataset Information

Molecular imaging of inflammation and platelet adhesion in advanced atherosclerosis effects of antioxidant therapy with NADPH oxidase inhibition.

Publications

Molecular imaging of inflammation and platelet adhesion in advanced atherosclerosis effects of antioxidant therapy with NADPH oxidase inhibition.

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