Abstract
Clostridium difficile toxin A causes acute colitis associated with intense infiltration of neutrophils. Although C. difficile toxin A is known to induce nuclear factor-kappaB-mediated chemokine expression in intestinal epithelial cells, little is known about its effect on the regulation of activator protein-1 (AP-1) by mitogen-activated protein kinase (MAPK). In the present study, we investigated whether the MAPK and AP-1 signaling pathway is involved in interleukin (IL)-8 expression and enteric inflammation in response to stimulation with toxin A. Toxin A activated MAPK and AP-1 composed of c-Jun/c-Fos heterodimers in primary intestinal epithelial cells and HT-29 cell lines. Transfection with mutant genes for Ras, c-Jun, p38, or c-Jun N-terminal kinase (JNK) significantly inhibited C. difficile toxin A-induced activation of AP-1 and expression of IL-8 in HT-29 cell lines. Furthermore, the p38 inhibitor SB203580 attenuated toxin A-induced inflammation in vivo in the mouse ileum, evidenced by a significant decrease in neutrophil infiltration, villous destruction, and mucosal congestion. Our results suggest that the Ras/MAPK cascade acts as the upstream signaling for AP-1 activation and IL-8 expression in toxin A-stimulated intestinal epithelial cells and may be involved in the development of enteritis after infection with toxin A-producing C. difficile.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Bacterial Toxins / toxicity*
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Colon / drug effects*
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Colon / enzymology
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Colon / metabolism
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Colon / pathology
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Dimerization
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Disease Models, Animal
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Enterotoxins / toxicity*
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Enzyme Activation
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Epithelial Cells / drug effects*
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Epithelial Cells / enzymology
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Epithelial Cells / metabolism
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Epithelial Cells / pathology
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Genes, ras
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HT29 Cells
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Humans
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Ileitis / chemically induced
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Ileitis / enzymology
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Ileitis / metabolism*
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Ileitis / pathology
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Ileitis / prevention & control
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Imidazoles / pharmacology
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Imidazoles / therapeutic use
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Interleukin-8 / metabolism*
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JNK Mitogen-Activated Protein Kinases / metabolism
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MAP Kinase Signaling System / drug effects*
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Mice
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Mice, Inbred C57BL
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Mitogen-Activated Protein Kinase 1 / metabolism
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Mitogen-Activated Protein Kinase 3 / metabolism
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Mitogen-Activated Protein Kinases / antagonists & inhibitors
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Mitogen-Activated Protein Kinases / genetics
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Mitogen-Activated Protein Kinases / metabolism*
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Mutation
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Protein Kinase Inhibitors / pharmacology
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Protein Kinase Inhibitors / therapeutic use
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Proto-Oncogene Proteins c-fos / metabolism
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Proto-Oncogene Proteins c-jun / metabolism
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Pyridines / pharmacology
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Pyridines / therapeutic use
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Time Factors
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Transcription Factor AP-1 / metabolism*
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Transfection
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p38 Mitogen-Activated Protein Kinases / metabolism
Substances
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Bacterial Toxins
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Enterotoxins
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Imidazoles
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Interleukin-8
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Protein Kinase Inhibitors
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Proto-Oncogene Proteins c-fos
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Proto-Oncogene Proteins c-jun
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Pyridines
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Transcription Factor AP-1
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tcdA protein, Clostridium difficile
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JNK Mitogen-Activated Protein Kinases
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Mitogen-Activated Protein Kinase 1
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Mitogen-Activated Protein Kinase 3
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Mitogen-Activated Protein Kinases
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p38 Mitogen-Activated Protein Kinases
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SB 203580