title: Upregulation of interferon-induced indoleamine 2,3-dioxygenase in human macrophage cultures by lipopolysaccharide, muramyl tripeptide, and interleukin-1.
abstract: The tryptophan decyclizing enzyme indoleamine 2,3-dioxygenase (IDO) was induced in human monocyte-derived macrophages (MDM) treated with human recombinant interferon-beta (IFN-beta) or interferon-gamma (IFN-gamma). Treated cells exhibited dose-dependent increases in IDO when assayed 48 hr after treatment. Cells exposed to IFN-gamma were observed to exhibit consistently higher peak levels of IDO when compared with cells incubated in the presence of IFN-beta. When IFN-beta-treated cells were incubated in the presence of specified amounts of bacterial lipopolysaccharide (LPS) or liposome-encapsulated muramyl tripeptide (MTP), peak IDO activity increased such that enzyme activity was comparable to maximal activity observed with IFN-gamma-treated cells. LPS and MTP also upregulated IFN-gamma-mediated IDO activity when suboptimal amounts of IFN-gamma were used. When macrophages were costimulated with various concentrations of human recombinant interleukin 1 alpha (IL-1 alpha), along with either maximum-stimulating amounts of IFN-beta or suboptimal amounts of IFN-gamma, IDO activity was upregulated in a manner similar to results obtained using the microbial products as stimuli. While neither IL-1 alpha or IL-1 beta was detected in culture supernatants from macrophages treated with either LPS or MTP (alone or in combination with IFN), IL-1 alpha was detected in cell lysates of macrophages treated with these upregulators. Although neutralizing antibody to IL-1 alpha abolished the upregulatory effect of exogenous IL-1 alpha, it had no effect on upregulation by LPS or MTP. This suggests that although LPS and MTP may induce production of cell-associated IL-1 alpha, upregulation of IDO activity by these agents is independent of IL-1 alpha production and may be mediated through distinct pathways.
authors.affiliation: Department of Microbiology, Miami University, Oxford, Ohio 45056, USA.
authors.forename: B D
authors.initials: BD
authors.lastname: Hissong
authors.forename: G I
authors.initials: GI
authors.lastname: Byrne
authors.forename: M L
authors.initials: ML
authors.lastname: Padilla
authors.forename: J M
authors.initials: JM
authors.lastname: Carlin
mesh_terms: D000119:Acetylmuramyl-Alanyl-Isoglutamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D002478:Cells, Cultured; D004357:Drug Synergism; D004790:Enzyme Induction / Q000187:drug effects; D006801:Humans; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D016899:Interferon-beta / Q000494:pharmacology; D007371:Interferon-gamma / Q000494:pharmacology; D007375:Interleukin-1 / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects* / Q000201:enzymology; D011994:Recombinant Proteins / Q000494:pharmacology; D014366:Tryptophan Oxygenase / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D007375:Interleukin-1; D008070:Lipopolysaccharides; D011994:Recombinant Proteins; D000119:Acetylmuramyl-Alanyl-Isoglutamine; C035104:muramylNAc-Ala-isoGln-Lys-tripeptide; D016899:Interferon-beta; D007371:Interferon-gamma; D014366:Tryptophan Oxygenase