Sequential activation of class IB and class IA PI3K is important for the primed respiratory burst of human but not murine neutrophils.
It is well established that preexposure of human neutrophils to proinflammatory cytokines markedly augments the production of reactive oxygen species (ROS) to subsequent stimuli. This priming event is thought to be critical for localizing ROS to the vicinity of the inflammation, maximizing their role in the resolution of the inflammation, and minimizing the damage to surrounding tissue. We have used a new generation of isoform-selective phosphoinositide 3-kinase (PI3K) inhibitors to show that ROS production under these circumstances is regulated by temporal control of class I PI3K activity. Stimulation of tumor necrosis factor-alpha (TNF-alpha)-primed human neutrophils with N-formyl-methionyl-leucyl-phenylalanine (fMLP) results in biphasic activation of PI3K; the first phase is largely dependent on PI3Kgamma, and the second phase is largely dependent on PI3Kdelta. The second phase of PI3K activation requires the first phase; it is this second phase that is augmented by TNF-alpha priming and that regulates parallel activation of ROS production. Surprisingly, although TNF-alpha-primed mouse bone marrow-derived neutrophils exhibit superficially similar patterns of PI3K activation and ROS production in response to fMLP, these responses are substantially lower and largely dependent on PI3Kgamma alone. These results start to define which PI3K isoforms are responsible for modulating neutrophil responsiveness to infection and inflammation.
Condliffe
Alison M
AM
The Inositide Laboratory, Babraham Institute, Babraham Research Campus, Cambridge CB2 4AT, UK.
Davidson
Keith
K
Anderson
Karen E
KE
Ellson
Chris D
CD
Crabbe
Tom
T
Okkenhaug
Klaus
K
Vanhaesebroeck
Bart
B
Turner
Martin
M
Webb
Louise
L
Wymann
Matthias P
MP
Hirsch
Emilio
E
Ruckle
Thomas
T
Camps
Montserrat
M
Rommel
Christian
C
Jackson
Shaun P
SP
Chilvers
Edwin R
ER
Stephens
Len R
LR
Hawkins
Phillip T
PT
D000818:Animals; D002478:Cells, Cultured; D058534:Class I Phosphatidylinositol 3-Kinases; D058544:Class Ib Phosphatidylinositol 3-Kinase; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007527:Isoenzymes; D051379:Mice; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D016897:Respiratory Burst; D013045:Species Specificity; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D004791:Enzyme Inhibitors; D007527:Isoenzymes; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; D009240:N-Formylmethionine Leucyl-Phenylalanine; D019869:Phosphatidylinositol 3-Kinases; D058534:Class I Phosphatidylinositol 3-Kinases; D058544:Class Ib Phosphatidylinositol 3-Kinase; C497132:PIK3CB protein, human; C486018:PIK3CD protein, human; C546760:PIK3CG protein, human; C546764:Pik3cg protein, mouse