Regulation of alveolar macrophage p40phox: hierarchy of activating kinases and their inhibition by PGE2

J Leukoc Biol. 2012 Jul;92(1):219-31. doi: 10.1189/jlb.1211590. Epub 2012 Apr 27.


PGE(2), produced in the lung during infection with microbes such as Klebsiella pneumoniae, inhibits alveolar macrophage (AM) antimicrobial functions by preventing H(2)O(2) production by NADPH oxidase (NADPHox). Activation of the NADPHox complex is poorly understood in AMs, although in neutrophils it is known to be mediated by kinases including PI3K/Akt, protein kinase C (PKC) δ, p21-activated protein kinase (PAK), casein kinase 2 (CK2), and MAPKs. The p40phox cytosolic subunit of NADPHox has been recently recognized to function as a carrier protein for other subunits and a positive regulator of oxidase activation, a role previously considered unique to another subunit, p47phox. The regulation of p40phox remains poorly understood, and the effect of PGE(2) on its activation is completely undefined. We addressed these issues in rat AMs activated with IgG-opsonized K. pneumoniae. The kinetics of kinase activation and the consequences of kinase inhibition and silencing revealed a critical role for a PKCδ-PAK-class I PI3K/Akt1 cascade in the regulation of p40phox activation upon bacterial challenge in AMs; PKCα, ERK, and CK2 were not involved. PGE(2) inhibited the activation of p40phox, and its effects were mediated by protein kinase A type II, were independent of interactions with anchoring proteins, and were directed at the distal class I PI3K/Akt1 activation step. Defining the kinases that control AM p40phox activation and that are the targets for inhibition by PGE(2) provides new insights into immunoregulation in the infected lung.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blotting, Western
  • Cyclic AMP-Dependent Protein Kinases / metabolism*
  • Dinoprostone / pharmacology*
  • Female
  • Gene Expression Regulation*
  • Hydrogen Peroxide / metabolism
  • Immunoglobulin G / pharmacology
  • Immunoprecipitation
  • Klebsiella Infections / drug therapy
  • Klebsiella Infections / metabolism*
  • Klebsiella Infections / microbiology
  • Klebsiella pneumoniae
  • Macrophages, Alveolar / drug effects
  • Macrophages, Alveolar / metabolism*
  • Macrophages, Alveolar / microbiology
  • NADPH Oxidases / metabolism
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphoproteins / metabolism*
  • Phosphorylation
  • Protein Kinase C-delta / metabolism
  • Proto-Oncogene Proteins c-akt / antagonists & inhibitors
  • Proto-Oncogene Proteins c-akt / genetics
  • Proto-Oncogene Proteins c-akt / metabolism
  • RNA, Small Interfering / genetics
  • Rats
  • Rats, Wistar
  • Signal Transduction


  • Immunoglobulin G
  • Phosphoproteins
  • RNA, Small Interfering
  • neutrophil cytosol factor 40K
  • Hydrogen Peroxide
  • NADPH Oxidases
  • Proto-Oncogene Proteins c-akt
  • Cyclic AMP-Dependent Protein Kinases
  • Protein Kinase C-delta
  • Dinoprostone