Involvement of reactive oxygen species in Toll-like receptor 4-dependent activation of NF-kappa B.
Although oxidative stress has been thought to play a general role in the activation of NF-kappaB, the involvement of reactive oxygen species (ROS) in facilitating nuclear translocation of NF-kappaB in neutrophils has not been described. In addition, the mechanisms by which ROS modulate the transcriptional activity of NF-kappaB in response to Toll-like receptor 4 (TLR4)-dependent signaling are not well characterized. To examine these issues, oxidant-dependent signaling events downstream of TLR4 were investigated in neutrophils stimulated with LPS. Pretreatment of neutrophils with the antioxidants N-acetylcysteine or alpha-tocopherol prevented LPS-induced nuclear translocation of NF-kappaB. Antioxidant treatment of LPS-stimulated neutrophils also inhibited the production of proinflammatory cytokines (TNF-alpha, macrophage inflammatory protein-2, and IL-1beta), as well as activation of the kinases IkappaB kinase alpha, IkappaB kinase beta, p38, Akt, and extracellular receptor-activated kinases 1 and 2. The decrease in cytoplasmic levels of IkappaBalpha produced by exposure of neutrophils to LPS was prevented by N-acetylcysteine or alpha-tocopherol. Activation of IL-1R-associated kinase-1 (IRAK-1) and IRAK-4 in response to LPS stimulation was inhibited by antioxidants. These results demonstrate that proximal events in TLR4 signaling, at or antecedent to IRAK-1 and IRAK-4 activation, are oxidant dependent and indicate that ROS can modulate NF-kappaB-dependent transcription through their involvement in early TLR4-mediated cellular responses.
Asehnoune
Karim
K
Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Health Sciences Center, Denver, CO 80262, USA.
Strassheim
Derek
D
Mitra
Sanchayita
S
Kim
Jae Yeol
JY
Abraham
Edward
E
D000111:Acetylcysteine / Q000494:pharmacology; D021581:Active Transport, Cell Nucleus / Q000276:immunology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D002467:Cell Nucleus / Q000276:immunology / Q000378:metabolism; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects / Q000276:immunology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004795:Enzyme Stability / Q000187:drug effects / Q000276:immunology; D051550:I-kappa B Kinase; D020672:I-kappa B Proteins / Q000378:metabolism; D018836:Inflammation Mediators / Q000378:metabolism; D053592:Interleukin-1 Receptor-Associated Kinases; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D008562:Membrane Glycoproteins / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism*; D009504:Neutrophils / Q000201:enzymology / Q000276:immunology / Q000378:metabolism; D016877:Oxidants / Q000502:physiology; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D017382:Reactive Oxygen Species / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000502:physiology*; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D015854:Up-Regulation / Q000276:immunology; D024502:alpha-Tocopherol / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases
D000975:Antioxidants; D016207:Cytokines; D004791:Enzyme Inhibitors; D020672:I-kappa B Proteins; D018836:Inflammation Mediators; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D016328:NF-kappa B; C000606205:Nfkbia protein, mouse; D016877:Oxidants; D011518:Proto-Oncogene Proteins; D017382:Reactive Oxygen Species; D011956:Receptors, Cell Surface; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D000072000:NF-KappaB Inhibitor alpha; D011494:Protein Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D053592:Interleukin-1 Receptor-Associated Kinases; C507774:Irak4 protein, mouse; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; C496564:Chuk protein, mouse; D051550:I-kappa B Kinase; C496562:Ikbkb protein, mouse; C496566:Ikbke protein, mouse; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D024502:alpha-Tocopherol; D000111:Acetylcysteine