Regulation of proinflammatory mediator production in RAW264.7 macrophage by Vibrio vulnificus luxS and smcR.
Vibrio vulnificus causes fatal septicemia in human hosts, which is the consequence of raw shellfish consumption. The mortality following septicemia is dependent on the in vivo production of inflammatory mediators, including tumor necrosis factor-alpha (TNFalpha). The present study was set up to investigate the association of quorum sensing in V. vulnificus with the host immune response. The effect of quorum sensing on cytotoxicity and the production of proinflammatory mediators was examined using the murine macrophage cell-line RAW264.7. Cytotoxicity was determined by measuring lactate dehydrogenase release in the culture medium. Extracellular products from luxS- and smcR-deficient mutants exhibited weak cytotoxic effects on RAW264.7 cells. The production of the proinflammatory cytokines TNFalpha, IL-1beta and IL-6 was measured with real-time PCR and ELISA, and production was measured with Griess reagents. Mutation of both luxS and smcR delayed the transcription of TNFalpha, IL-1beta and IL-6 genes. Also, levels of both TNFalpha and nitric oxide induced by luxS- and smcR-deficient mutants were significantly lower than those induced by parent strains. These results suggest that quorum sensing could be involved in the modulation of TNFalpha and nitric oxide produced from host cells by regulating virulence factors, and that V. vulnificus facilitates its host's mortality and bacterial survival by enhancing virulence on host cells.
Shin
Na-Ri
NR
Department of Infectious Diseases, College of Veterinary Medicine and School of Agricultural Biotechnology, Seoul National University, Seoul 151-742, South Korea.
Lee
Deog-Yong
DY
Shin
Sung Jae
SJ
Kim
Kun-Soo
KS
Yoo
Han-Sang
HS
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology*; D013437:Carbon-Sulfur Lyases; D003601:Cytotoxicity Tests, Immunologic; D004797:Enzyme-Linked Immunosorbent Assay; D007375:Interleukin-1 / Q000737:chemistry / Q000235:genetics; D015850:Interleukin-6 / Q000737:chemistry / Q000235:genetics; D016676:Macrophages, Alveolar / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D009154:Mutation; D009569:Nitric Oxide / Q000276:immunology; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000276:immunology*; D014735:Vibrio Infections / Q000276:immunology*; D041261:Vibrio vulnificus / Q000235:genetics / Q000276:immunology*
D001426:Bacterial Proteins; D007375:Interleukin-1; D015850:Interleukin-6; D012329:RNA, Bacterial; C094220:SmeR protein, Serratia marcescens; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide; D013437:Carbon-Sulfur Lyases; C117753:LuxS protein, Bacteria