Blockade of Class IA Phosphoinositide 3-Kinase in Neutrophils Prevents NADPH Oxidase Activation- and Adhesion-dependent Inflammation*
- ‡Department of Pharmacology and Center of Lung and Vascular Biology, University of Illinois College of Medicine, Chicago, Illinois 60612 and the §Section of Pulmonary and Critical Care Medicine, Department of Medicine, The University of Chicago, Chicago, Illinois 60637
- 2 To whom correspondence should be addressed: Dept. of Pharmacology, College of Medicine, The University of Illinois, 835 South Wolcott Ave., Chicago, IL 60612-7343. Tel.: 312-996-7635; Fax: 312-996-1225; E-mail: abmalik{at}uic.edu.
Abstract
We examined the role of class IA phosphoinositide 3-kinase (PI3K) in the regulation of activation of NADPH oxidase in PMNs and the mechanism of PMN-dependent lung inflammation and microvessel injury induced by the pro-inflammatory cytokine TNF-α. TNF-α stimulation of PMNs resulted in superoxide production that was dependent on CD11b/CD18-mediated PMN adhesion. Additionally, TNF-α induced the association of CD11b/CD18 with the NADPH oxidase subunit Nox2 (gp91phox) and phosphorylation of p47phox, indicating the CD11b/CD18 dependence of NADPH oxidase activation. Transduction of wild-type PMNs with Δp85 protein, a dominant-negative form of the class IA PI3K regulatory subunit, p85α, fused to HIV-TAT (TAT-Δp85) prevented (i) CD11b/CD18-dependent PMN adhesion, (ii) interaction of CD11b/CD18 with Nox2 and phosphorylation of p47phox, and (iii) PMN oxidant production. Furthermore, studies in mice showed that i.v. infusion of TAT-Δp85 significantly reduced the recruitment of PMNs in lungs and increase in lung microvascular permeability induced by TNF-α. We conclude that class IA PI3K serves as a nodal point regulating CD11b/CD18-integrin-dependent PMN adhesion and activation of NADPH oxidase, and leads to oxidant production at sites of PMN adhesion, and the resultant lung microvascular injury in mice.
Footnotes
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↵3 The abbreviations used are: PMN, polymorphonuclear leukocyte; NIF, neutrophil inhibitory factor; BAL, bronchoalveolar lavage; Kf,c, capillary filtration coefficient; PKC, protein kinase C; PI3K, phosphoinositide 3-kinase; TNF, tumor necrosis factor; WT, wild type; mAb, monoclonal antibody; i.v., intravenous; ROS, reactive oxygen species; PBS, phosphate-buffered saline; GFP, green fluorescent protein; MPO, myeloperoxidase.
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↵* This study was supported in part by National Institutes of Health Grants HL46350, HL77806, HL45638, and HL64573 (to A. B. M.), and AI52109 (to X. Z.) and by a research grant from the American Lung Association (to R. S. F.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement”in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵1 Both authors contributed equally to this work.
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- Received November 2, 2006.
- Revision received December 14, 2006.
- The American Society for Biochemistry and Molecular Biology, Inc.
