Invasive Shigella flexneri activates NF-kappa B through a lipopolysaccharide-dependent innate intracellular response and leads to IL-8 expression in epithelial cells.
The pathogenesis of Shigella flexneri infection centers on the ability of this organism to invade epithelial cells and initiate an intense inflammatory reaction. Because NF-kappa B is an important transcriptional regulator of genes involved in inflammation, we investigated the role of this transcription factor during S. flexneri infection of epithelial cells. Infection of HeLa cells with invasive S. flexneri induced NF-kappa B DNA-binding activity; noninvasive S. flexneri strains did not lead to this activation. The pathway leading to NF-kappa B activation by invasive S. flexneri involved the kinases, NF-kappa B-inducing kinase, I kappa B kinase-1, and I kappa B kinase-2. NF-kappa B activation was linked to inflammation, because invasive S. flexneri activated an IL-8 promoter-driven reporter gene, and the kappa B site within this promoter was indispensable for its induction. Microinjection of bacterial culture supernatants into HeLa cells suggested that LPS is responsible for NF-kappa B activation by S. flexneri infection. In conclusion, the eukaryotic transcription factor NF-kappa B was activated during S. flexneri infection of epithelial cells, which suggests a role for this transcriptional regulator in modulating the immune response during infection in vivo.
Philpott
D J
DJ
Unité de Pathogénie Microbienne Moléculaire, Institut National de la Santé et de la Recherche Médicale, Unité 389, Pasteur, France.
Yamaoka
S
S
Israël
A
A
Sansonetti
P J
PJ
D000942:Antigens, Bacterial / Q000502:physiology; D001426:Bacterial Proteins / Q000502:physiology; D001665:Binding Sites / Q000235:genetics / Q000276:immunology; D018938:Caco-2 Cells; D004268:DNA-Binding Proteins / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000276:immunology; D004847:Epithelial Cells / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism* / Q000382:microbiology; D006367:HeLa Cells; D006801:Humans; D051550:I-kappa B Kinase; D007113:Immunity, Innate; D016209:Interleukin-8 / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D007424:Intracellular Fluid / Q000276:immunology* / Q000378:metabolism* / Q000382:microbiology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008156:Luciferases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D016328:NF-kappa B / Q000096:biosynthesis / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000276:immunology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012763:Shigella flexneri / Q000276:immunology* / Q000472:pathogenicity; D015398:Signal Transduction / Q000276:immunology; D014774:Virulence / Q000276:immunology
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D016209:Interleukin-8; C063664:IpaA protein, Shigella flexneri; D008070:Lipopolysaccharides; D016328:NF-kappa B; C087447:ipaB protein, Shigella; D008156:Luciferases; D017346:Protein Serine-Threonine Kinases; C496559:CHUK protein, human; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C496565:IKBKE protein, human