Redox signaling-mediated regulation of lipopolysaccharide-induced proinflammatory cytokine biosynthesis in alveolar epithelial cells.
The regulation of cytokine gene transcription and biosynthesis involves the reduction-oxidation (redox)-sensitive nuclear factor-kappaB (NF-kappaB), whose activation is mediated by an upstream kinase that regulates the phosphorylation of inhibitory-kappaB (IkappaB). It was hypothesized that lipopolysaccharide (LPS)-induced biosynthesis of interleukin-1beta, interleukin-6, and tumor necrosis factor-alpha in vitro is regulated by redox equilibrium. In alveolar epithelial cells, we investigated the role of L-buthionine-(S,R)-sulfoximine (BSO), an irreversible inhibitor of gamma-glutamylcysteine synthetase, the rate-limiting enzyme in GSH biosynthesis, 1,3-bis-(2-chloroethyl)-1-nitrosourea (BCNU), which inhibits glutathione oxidized disulfide reductase, pyrrolidine dithiocarbamate (PDTC), an antioxidant/prooxidant thiuram, and N-acetyl-L-cysteine (NAC), an antioxidant and GSH precursor, in regulating LPS-induced cytokine biosynthesis and IkappaB-alpha/NF-kappaB signaling. BSO blockaded the phosphorylation of IkappaB-alpha, reduced its degradation, and inhibited NF-kappaB activation, besides augmenting LPS-mediated biosynthesis of cytokines. BCNU up-regulated LPS-induced release of cytokines, an effect associated with partial phosphorylation/degradation of IkappaB-alpha and inhibition of the DNA binding activity. PDTC, which partially affected LPS-induced IkappaB-alpha phosphorylation/degradation, otherwise blockading NF-kappaB activation, reduced LPS-dependent up-regulation of cytokine release. Pretreatment with BSO did not abolish the NAC-dependent reduction of LPS-induced cytokine release, despite the fact that NAC marginally amplified IkappaB-alpha phosphorylation/degradation and suppressed NF-kappaB activation. These results indicate that cytokines are redox-sensitive mediators and that the IkappaB-alpha/NF-kappaB pathway is redox-sensitive and differentially implicated in mediating redox-dependent regulation of LPS-induced release of proinflammatory cytokines.
Haddad
John J
JJ
Oxygen Signaling Group, Center for Research into Human Development, Tayside Institute of Child Health, Faculty of Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, Scotland, UK. haddadj@anesthesia.ucsf.edu
Land
Stephen C
SC
D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology; D002330:Carmustine / Q000494:pharmacology; D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D005978:Glutathione / Q000378:metabolism; D020672:I-kappa B Proteins; D008070:Lipopolysaccharides / Q000378:metabolism*; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism; D010084:Oxidation-Reduction; D010766:Phosphorylation; D011650:Pulmonary Alveoli / Q000166:cytology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction
D018906:Antineoplastic Agents, Alkylating; D016207:Cytokines; D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D008070:Lipopolysaccharides; D016328:NF-kappa B; C000606204:NFKBIA protein, human; C000606206:Nfkbia protein, rat; D000072000:NF-KappaB Inhibitor alpha; D005978:Glutathione; D002330:Carmustine