Blockade of class IA phosphoinositide 3-kinase in neutrophils prevents NADPH oxidase activation- and adhesion-dependent inflammation.
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-alpha. TNF-alpha stimulation of PMNs resulted in superoxide production that was dependent on CD11b/CD18-mediated PMN adhesion. Additionally, TNF-alpha induced the association of CD11b/CD18 with the NADPH oxidase subunit Nox2 (gp91(phox)) and phosphorylation of p47(phox), indicating the CD11b/CD18 dependence of NADPH oxidase activation. Transduction of wild-type PMNs with Deltap85 protein, a dominant-negative form of the class IA PI3K regulatory subunit, p85alpha, fused to HIV-TAT (TAT-Deltap85) prevented (i) CD11b/CD18-dependent PMN adhesion, (ii) interaction of CD11b/CD18 with Nox2 and phosphorylation of p47(phox), and (iii) PMN oxidant production. Furthermore, studies in mice showed that i.v. infusion of TAT-Deltap85 significantly reduced the recruitment of PMNs in lungs and increase in lung microvascular permeability induced by TNF-alpha. 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.
Gao
Xiao-Pei
XP
Department of Pharmacology and Center of Lung and Vascular Biology, University of Illinois College of Medicine, Chicago, Illinois 60612, USA.
Zhu
Xiangdong
X
Fu
Jian
J
Liu
Qinghui
Q
Frey
Randall S
RS
Malik
Asrar B
AB
D000818:Animals; D002448:Cell Adhesion; D004789:Enzyme Activation; D007249:Inflammation; D008168:Lung / Q000098:blood supply; D008171:Lung Diseases; D016177:Macrophage-1 Antigen / Q000502:physiology; D051379:Mice; D009097:Multienzyme Complexes / Q000378:metabolism*; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D009504:Neutrophils / Q000201:enzymology*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D013481:Superoxides / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D016177:Macrophage-1 Antigen; D009097:Multienzyme Complexes; D009247:NADH, NADPH Oxidoreductases; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D013481:Superoxides; D014409:Tumor Necrosis Factor-alpha; C023107:NADH oxidase