Abstract
Clostridium difficile toxin A causes acute neutrophil infiltration and intestinal mucosal injury. In cultured cells, toxin A inactivates Rho proteins by monoglucosylation. In monocytes, toxin A induces IL-8 production and necrosis by unknown mechanisms. We investigated the role of mitogen-activated protein (MAP) kinases in these events. In THP-1 monocytic cells, toxin A activated the 3 main MAP kinase cascades within 1 to 2 minutes. Activation of p38 was sustained, whereas stimulation of extracellular signal-regulated kinases and c-Jun NH(2)-terminal kinase was transient. Rho glucosylation became evident after 15 minutes. IL-8 gene expression was reduced by 70% by the MEK inhibitor PD98059 and abrogated by the p38 inhibitor SB203580 or by overexpression of dominant-negative mutants of the p38-activating kinases MKK3 and MKK6. SB203580 also blocked monocyte necrosis and IL-1beta release caused by toxin A but not by other toxins. Finally, in mouse ileum, SB203580 prevented toxin A-induced neutrophil recruitment by 92% and villous destruction by 90%. Thus, in monocytes exposed to toxin A, MAP kinase activation appears to precede Rho glucosylation and is required for IL-8 transcription and cell necrosis. p38 MAP kinase also mediates intestinal inflammation and mucosal damage induced by toxin A.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Bacterial Toxins / metabolism
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Bacterial Toxins / pharmacology*
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Cell Line
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Clostridioides difficile / immunology*
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Clostridioides difficile / metabolism
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Enteritis / enzymology
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Enteritis / immunology*
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Enteritis / microbiology
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Enterocolitis, Pseudomembranous / enzymology
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Enterocolitis, Pseudomembranous / immunology
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Enterocolitis, Pseudomembranous / microbiology
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Enterotoxins / metabolism
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Enterotoxins / pharmacology*
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Enzyme Activation
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Gene Expression Regulation / drug effects
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Glycosylation
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Interleukin-8 / biosynthesis*
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Interleukin-8 / genetics
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MAP Kinase Signaling System*
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Mice
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Mitogen-Activated Protein Kinase 1 / metabolism
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Mitogen-Activated Protein Kinase 3
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Mitogen-Activated Protein Kinase 8
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Mitogen-Activated Protein Kinases / antagonists & inhibitors
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Mitogen-Activated Protein Kinases / immunology
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Mitogen-Activated Protein Kinases / metabolism*
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Monocytes / immunology*
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Monocytes / metabolism
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Monocytes / pathology
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Neutrophil Infiltration / immunology
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Neutrophils / immunology
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p38 Mitogen-Activated Protein Kinases
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rho GTP-Binding Proteins / immunology
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rho GTP-Binding Proteins / metabolism
Substances
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Bacterial Toxins
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Enterotoxins
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Interleukin-8
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tcdA protein, Clostridium difficile
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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 Kinase 8
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Mitogen-Activated Protein Kinases
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p38 Mitogen-Activated Protein Kinases
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rho GTP-Binding Proteins