Tài liệu Báo cáo khoa học: Transcriptional upregulation of inflammatory cytokines in human intestinal

Transcriptional upregulation of inflammatory cytokines in

human intestinal epithelial cells following Vibrio cholerae

infection

Arunava Bandyopadhaya*, Madhubanti Sarkar* and Keya Chaudhuri

Molecular & Human Genetics Division, Indian Institute of Chemical Biology, Kolkata, India

The acute diarrheal disease cholera remains a signifi￾cant public health problem, due to its ability to spread

rapidly and kill a high proportion of those affected.

The etiologic agent of the disease is a highly motile

noninvasive Gram-negative organism Vibrio cholerae,

which colonizes the small intestine and produces a

potent enterotoxin called cholera toxin (CT) ) a major

virulence determinant that is primarily responsible for

the diarrheal syndrome [1]. Although much work has

been done on V. cholerae, very little is known about

the bacterium–host interactions. Epithelial cells are the

first site of entry for intestinal pathogens, and provide

early signals for the acute mucosal inflammatory

response via release of proinflammatory cytokines and

Keywords

cholera toxin; cytokines; intestinal epithelial

cells; nuclear factor-jB; Vibrio cholerae

Correspondence

K. Chaudhuri, Molecular & Human Genetics

Division, Indian Institute of Chemical

Biology, Kolkata-700 032, India

Fax: +91 33 2473 5197

Tel: +91 33 2473 3491

E-mail: [email protected] or

[email protected]

*These authors contributed equally to this

work

(Received 21 February 2007, revised

31 May 2007, accepted 13 July 2007)

doi:10.1111/j.1742-4658.2007.05991.x

Coordinated expression and upregulation of interleukin-1a, interleukin-1b,

tumor necrosis factor-a, interleukin-6, granulocyte–macrophage colony￾stimulating factor, interleukin-8, monocyte chemotactic protein-1 (MCP-1)

and epithelial cell derived neutrophil activator-78, with chemoattractant

and proinflammatory properties of various cytokine families, were obtained

in the intestinal epithelial cell line Int407 upon Vibrio cholerae infection.

These proinflammatory cytokines also showed increased expression in T84

cells, except for interleukin-6, whereas a striking dissimilarity in cytokine

expression was observed in Caco-2 cells. Gene expression studies of MCP￾1, granulocyte–macrophage colony-stimulating factor, interleukin-1a, inter￾leukin-6 and the anti-inflammatory cytokine transforming growth factor-b

in Int407 cells with V. cholerae culture supernatant, cholera toxin, lipopoly￾saccharide and ctxA mutant demonstrated that, apart from cholera toxin

and lipopolysaccharide, V. cholerae culture supernatant harbors strong

inducer(s) of interleukin-6 and MCP-1 and moderate inducer(s) of inter￾leukin-1a and granulocyte–macrophage colony-stimulating factor. Cholera

toxin- or lipopolysaccharide-induced cytokine expression is facilitated by

activation of nuclear factor-jB (p65 and p50) and cAMP response element￾binding protein in Int407 cells. Studies with ctxA mutants of V. cholerae

revealed that the mutant activates the p65 subunit of nuclear factor-jB and

cAMP response element-binding protein, and as such the activation is med￾iated by cholera toxin-independent factors as well. We conclude that

V. cholerae elicits a proinflammatory response in Int407 cells that is medi￾ated by activation of nuclear factor-jB and cAMP response element-bind￾ing protein by cholera toxin, lipopolysaccharide and ⁄ or other secreted

products of V. cholerae.

Abbreviations

CREB, cAMP response element-binding protein; CT, cholera toxin; ENA-78, epithelial cell derived neutrophil activator-78; GM-CSF,

granulocyte–macrophage colony-stimulating factor; IFN, interferon; IL, interleukin; LPS, lipopolysacccharide; MCP-1, monocyte chemotactic

protein-1; MOI, multiplicity of infection; NF-jB, nuclear factor-jB; PMN, polymorphonuclear neutrophil; TGF-b, transforming growth factor-b;

TNF-a, tumor necrosis factor-a.

FEBS Journal 274 (2007) 4631–4642 ª 2007 The Authors Journal compilation ª 2007 FEBS 4631