Lactobacilli and Streptococci activate NF-kappa B and STAT signaling pathways in human macrophages.
Gram-positive bacteria induce the production of several cytokines in human leukocytes. The molecular mechanisms involved in Gram-positive bacteria-induced cytokine production have been poorly characterized. In this work we demonstrate that both nonpathogenic Lactobacillus rhamnosus GG and pathogenic Streptococcus pyogenes (group A streptococci) induce NF-kappa B and STAT DNA-binding activity in human primary macrophages as analyzed by EMSA. NF-kappa B activation was rapid and was not inhibited by a protein synthesis inhibitor cycloheximide, suggesting that these bacteria could directly activate NF-kappa B. STAT1, STAT3, and IFN regulatory factor-1 DNA binding was induced by both bacteria with delayed kinetics compared with NF-kappa B. In addition, streptococci induced the formation of IFN-alpha-specific transcription factor complex and IFN-stimulated gene factor-3 (ISGF3). STAT1 and STAT3 activation and ISGF3 complex formation were inhibited by cycloheximide or by neutralization with IFN-alpha/beta-specific Abs. Streptococci were more potent than lactobacilli in inducing STAT1, ISGF3, and IFN regulatory factor-1 DNA binding. Accordingly, only streptococci induced IFN-alpha production. The activation of the IFN-alpha signaling pathway by streptococci could play a role in the pathogenesis of these bacteria. These results indicate that extracellular Gram-positive bacteria activate transcription factors involved in cytokine signaling by two mechanisms: directly, leading to NF-kappa B activation, and indirectly via cytokines, leading to STAT activation.
Miettinen
M
M
Department of Virology, National Public Health Institute, Helsinki, Finland. minjia.miettinen@ktl.fi
Lehtonen
A
A
Julkunen
I
I
Matikainen
S
S
D001665:Binding Sites / Q000276:immunology; D002648:Child; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D007106:Immune Sera / Q000494:pharmacology; D050856:Interferon Regulatory Factor-1; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D016898:Interferon-alpha / Q000096:biosynthesis / Q000276:immunology; D015850:Interleukin-6 / Q000096:biosynthesis; D007778:Lactobacillus / Q000187:drug effects / Q000276:immunology*; D008264:Macrophages / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology*; D016328:NF-kappa B / Q000378:metabolism* / Q000502:physiology; D010750:Phosphoproteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D050794:STAT1 Transcription Factor; D050796:STAT3 Transcription Factor; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology*; D013297:Streptococcus pyogenes / Q000187:drug effects / Q000276:immunology*; D015534:Trans-Activators / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D014157:Transcription Factors / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
D004268:DNA-Binding Proteins; C494257:IRF1 protein, human; C494227:IRF9 protein, human; D007106:Immune Sera; D050856:Interferon Regulatory Factor-1; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D016898:Interferon-alpha; D015850:Interleukin-6; D016328:NF-kappa B; D010750:Phosphoproteins; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D004247:DNA