title: A defective TLR4 signaling for IFN-β expression is responsible for the innately lower ability of BALB/c macrophages to produce NO in response to LPS as compared to C57BL/6.
abstract: C57BL/6 mice macrophages innately produce higher levels of NO than BALB/c cells when stimulated with LPS. Here, we investigated the molecular events that account for this intrinsic differential production of NO. We found that the lower production of NO in BALB/c is not due to a subtraction of L-arginine by arginase, and correlates with a lower iNOS accumulation, which is independent of its degradation rate. Instead, the lower accumulation of iNOS is due to the lower levels of iNOS mRNA, previously shown to be also independent of its stability, suggesting that iNOS transcription is less efficient in BALB/c than in C57BL/6 macrophages. Activation of NFκB is more efficient in BALB/c, thus not correlating with iNOS expression. Conversely, activation of STAT-1 does correlate with iNOS expression, being more prominent in C57BL/6 than in BALB/c macrophages. IFN-β and IL-10 are more highly expressed in C57BL/6 than in BALB/c macrophages, and the opposite is true for TNF-α. Whereas IL-10 and TNF-α do not seem to participate in their differential production of NO, IFN-β has a determinant role since 1) anti-IFN-β neutralizing antibodies abolish STAT-1 activation reducing NO production in C57BL/6 macrophages to levels as low as in BALB/c cells and 2) exogenous rIFN-β confers to LPS-stimulated BALB/c macrophages the ability to phosphorylate STAT-1 and to produce NO as efficiently as C57BL/6 cells. We demonstrate, for the first time, that BALB/c macrophages are innately lower NO producers than C57BL/6 cells because they are defective in the TLR-4-induced IFN-β-mediated STAT-1 activation pathway.
authors.affiliation: Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, MG, Brazil.
authors.forename: Luciana S
authors.initials: LS
authors.lastname: Oliveira
authors.affiliation: Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, MG, Brazil.
authors.forename: Nina M G P
authors.initials: NM
authors.lastname: de Queiroz
authors.affiliation: Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, MG, Brazil.
authors.forename: Laura V S
authors.initials: LV
authors.lastname: Veloso
authors.affiliation: Departamento de Alimentos, Faculdade de Farmácia, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, MG, Brazil.
authors.forename: Thaís G
authors.initials: TG
authors.lastname: Moreira
authors.affiliation: Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, MG, Brazil.
authors.forename: Fernanda S
authors.initials: FS
authors.lastname: Oliveira
authors.affiliation: Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, MG, Brazil.
authors.forename: Matheus B H
authors.initials: MB
authors.lastname: Carneiro
authors.affiliation: Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, MG, Brazil.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Faria
authors.affiliation: Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, MG, Brazil.
authors.forename: Leda Q
authors.initials: LQ
authors.lastname: Vieira
authors.affiliation: Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, MG, Brazil.
authors.forename: Sérgio C
authors.initials: SC
authors.lastname: Oliveira
authors.affiliation: Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, MG, Brazil.
authors.forename: Maria F
authors.initials: MF
authors.lastname: Horta
mesh_terms: D000818:Animals; D001119:Arginase / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D016899:Interferon-beta / Q000235:genetics*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009569:Nitric Oxide / Q000096:biosynthesis*; D052247:Nitric Oxide Synthase Type II / Q000235:genetics; D010641:Phenotype; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D050794:STAT1 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D013045:Species Specificity; D051197:Toll-Like Receptor 4 / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D008070:Lipopolysaccharides; D012333:RNA, Messenger; D050794:STAT1 Transcription Factor; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D009569:Nitric Oxide; D016899:Interferon-beta; D052247:Nitric Oxide Synthase Type II; D001119:Arginase