title: Interleukin 10 (IL-10)-mediated inhibition of inflammatory cytokine production by human alveolar macrophages.
abstract: Alveolar macrophages are an important source of inflammatory cytokines in the lung. IL-10 has been shown to inhibit inflammatory cytokine production by human alveolar macrophages, but mechanisms are unclear. The purpose of the present study was to investigate whether IL-10 modified cytokine production by interference with transcriptional pathways. Alveolar macrophages were obtained from healthy controls by fiberoptic bronchoscopy and incubated with LPS+/-IL-10. Results indicated that steady state mRNA levels of tumour necrosis factor-alpha (TNF) and interleukin 1-beta (IL-1) decreased in the presence of IL-10. Consequently, electrophoretic mobility shift assays were performed using end-labelled nuclear factor-kappa B (NF-kappa B) or activator protein-1 (AP-1) probe. NF-kappa B binding was decreased in extracts from macrophages incubated for 4 h with LPS+IL-10 in comparison to those incubated with LPS alone. IL-10 also inhibited TNF secretion and NF-kappa B activation induced by another stimulus, staphylococcal toxin. Supershift assays revealed the presence of both p50 and p65 subunits of NF-kappa B. AP-1 was not affected by IL-10. Further examination of mechanisms indicated that IL-10 delayed the LPS-mediated degradation of the inhibitor protein I kappa B, thus delaying the nuclear translocation of the p65 subunit. These observations provide the first evidence that IL-10 antagonizes cytokine transcription in human alveolar macrophages by impeding the nuclear translocation of NF-kappa B by delaying the degradation of I kappa B.
authors.affiliation: Department of Pulmonary and Critical Care Medicine, The Cleveland Clinic Foundation, 9500 Euclid Avenue Cleveland, Ohio 44195-5038, USA.
authors.forename: B
authors.initials: B
authors.lastname: Raychaudhuri
authors.forename: C J
authors.initials: CJ
authors.lastname: Fisher
authors.forename: C F
authors.initials: CF
authors.lastname: Farver
authors.forename: A
authors.initials: A
authors.lastname: Malur
authors.forename: J
authors.initials: J
authors.lastname: Drazba
authors.forename: M S
authors.initials: MS
authors.lastname: Kavuru
authors.forename: M J
authors.initials: MJ
authors.lastname: Thomassen
mesh_terms: D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism; D016207:Cytokines / Q000096:biosynthesis*; D004768:Enterotoxins / Q000378:metabolism; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D007375:Interleukin-1 / Q000378:metabolism; D016753:Interleukin-10 / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008168:Lung / Q000276:immunology*; D016676:Macrophages, Alveolar / Q000276:immunology* / Q000378:metabolism; D008856:Microscopy, Fluorescence; D016328:NF-kappa B / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051996:Transcription Factor RelA; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D016207:Cytokines; D004768:Enterotoxins; D020672:I-kappa B Proteins; D007375:Interleukin-1; D008070:Lipopolysaccharides; D016328:NF-kappa B; D012333:RNA, Messenger; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; C031818:enterotoxin B, staphylococcal