Flagellin, a novel mediator of Salmonella-induced epithelial activation and systemic inflammation: I kappa B alpha degradation, induction of nitric oxide synthase, induction of proinflammatory mediators, and cardiovascular dysfunction.
Gram-negative sepsis is mediated by the actions of proinflammatory genes induced in response to microbes and their products. We report that flagellin, the monomeric subunit of flagella, is a potent proinflammatory species released by Salmonella. Flagellin (1 microgram/ml) induces IkappaBalpha degradation, NF-kappaB nuclear translocation, and inducible NO synthase expression in cultured intestinal epithelial cells (IEC). Aflagellic Salmonella mutants do not induce NF-kappaB activation or NO production by cultured IEC. Antiserum to flagellin blocks NO production in IEC induced by medium conditioned by a variety of motile Gram-negative enteric pathogens (Escherichia coli, Salmonella muenchen, Serratia marcescens, Proteus mirabilis, and Proteus vulgaris). Flagellin, when injected systemically (approximately 10 microgram/mouse), induces systemic inflammation characterized by the systemic expression of a range of proinflammatory cytokines and chemokines and of inducible NO synthase. At higher doses (approximately 300 microgram/mouse), flagellin induces shock, characterized by hypotension, reduced vascular contractility in mice, and death. The effects of flagellin do not diminish in C3H/HeJ LPS-resistant mice, indicating that the Toll-like receptor-4 receptor is not involved in flagellin's actions. In LPS-resistant mice, i.p. injection of S. dublin flagellin or medium conditioned by wild-type S. dublin induces serum IFN-gamma and TNF-alpha, whereas medium conditioned by aflagellic mutants has no effect. Flagellin can be detected in the blood of rats with septic shock induced by live bacteria at approximately 1 microg/ml. We propose that flagellin released by Gram-negative pathogens may contribute to the inflammatory response by an LPS- and Toll-like receptor-4-independent pathway.
Eaves-Pyles
T
T
Inotek Corporation, Beverly, MA 01915, USA.
Murthy
K
K
Liaudet
L
L
Virág
L
L
Ross
G
G
Soriano
F G
FG
Szabó
C
C
Salzman
A L
AL
D000595:Amino Acid Sequence; D000818:Animals; D018938:Caco-2 Cells; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D004790:Enzyme Induction / Q000235:genetics / Q000276:immunology; D005407:Flagella / Q000276:immunology / Q000378:metabolism; D005408:Flagellin / Q000097:blood / Q000276:immunology / Q000302:isolation & purification / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000276:immunology; D006090:Gram-Negative Bacteria / Q000276:immunology; D006439:Hemodynamics / Q000235:genetics / Q000276:immunology; D006801:Humans; D020672:I-kappa B Proteins; D007106:Immune Sera / Q000494:pharmacology; D018836:Inflammation Mediators / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism / Q000473:pathology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D000072000:NF-KappaB Inhibitor alpha; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000096:biosynthesis* / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D012475:Salmonella / Q000276:immunology; D012481:Salmonella Infections, Animal / Q000235:genetics / Q000276:immunology* / Q000473:pathology / Q000503:physiopathology; D012772:Shock, Septic / Q000097:blood / Q000276:immunology / Q000382:microbiology / Q000503:physiopathology*; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D007106:Immune Sera; D018836:Inflammation Mediators; D008070:Lipopolysaccharides; C000606204:NFKBIA protein, human; C000606205:Nfkbia protein, mouse; C000606206:Nfkbia protein, rat; D005408:Flagellin; D000072000:NF-KappaB Inhibitor alpha; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase