IL-1beta expression in Int407 is induced by flagellin of Vibrio cholerae through TLR5 mediated pathway.
Vibrio cholerae, a noninvasive enteric bacterium, causing inflammatory diarrheal disease cholera, is associated with the secretion of proinflamammatory cytokines including IL-1beta in cultured epithelial cells. Incubation of Int407 with live V. cholerae resulted in increased IL-1beta mRNA expression as early as 2h of infection, reached a peak at approximately 3.5h and decreased thereafter. The identity of the effector molecule(s) is largely unknown. The bacterial culture supernatant showed IL-1beta stimulating activity. An engineered aflagellate V. cholerae flaA mutant (O395FLAN) resulted in highly reduced level of IL-1beta expression in Int407. The crude flagellar protein of V. cholerae as well as recombinant FlaA induced IL-1beta expression in Int407. Infection of Toll-like receptor 5 (TLR5) transfected HeLa cells with O395FLAN showed reduced expression of IL-1beta compared to wild-type. Unlike wild-type V. cholerae, O395FLAN did not activate the NF-kappaB while the recombinant flagellin could activate NF-kappaB. Finally, the mitogen activated protein kinases (ERK1 and 2, p38) were phosphorylated in wild-type and recombinant flagellin treated Int407 cells and inhibition of the p38 and ERK pathways significantly decreased the IL-1beta response induced by wild-type V. cholerae as well as recombinant flagellin. Our data clearly indicate that flagellin of V. cholerae could induce IL-1beta expression by recognizing TLR5 that activate NF-kappaB and MAP kinase in Int407.
Bandyopadhaya
Arunava
A
Molecular and Human Genetics Division, Indian Institute of Chemical Biology, 4 Raja S.C. Mullick Road, Kolkata 700 032, India.
Sarkar
Madhubanti
M
Chaudhuri
Keya
K
D002478:Cells, Cultured; D002771:Cholera / Q000276:immunology* / Q000382:microbiology / Q000503:physiopathology; D003470:Culture Media / Q000737:chemistry; D004847:Epithelial Cells / Q000276:immunology / Q000382:microbiology / Q000502:physiology; D005408:Flagellin / Q000235:genetics / Q000276:immunology*; D015870:Gene Expression; D006367:HeLa Cells; D006801:Humans; D053583:Interleukin-1beta / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology; D015398:Signal Transduction; D051198:Toll-Like Receptor 5 / Q000235:genetics / Q000378:metabolism*; D014734:Vibrio cholerae / Q000235:genetics / Q000276:immunology*
D003470:Culture Media; D053583:Interleukin-1beta; D016328:NF-kappa B; D012333:RNA, Messenger; D011994:Recombinant Proteins; C495346:TLR5 protein, human; D051198:Toll-Like Receptor 5; D005408:Flagellin; C067138:flaA protein, bacteria; D020928:Mitogen-Activated Protein Kinases