Abstract
Clostridium difficile toxin A induces acute colitis with neutrophil infiltration and up-regulation of numerous pro-inflammatory mediators, but the contribution of cyclooxygenase-2 (COX-2) induction in this infection is unknown. We report here that toxin A induces expression of COX-2 and secretion of prostaglandin E2 (PGE2) in a dose- and time-dependent manner in cultured NCM460 human colonocytes and in human intestinal xenografts. This induction was blocked by SB203580, a p38 MAPK inhibitor, which also decreased the phosphorylation of MSK-1, CREB/ATF-1, and COX-2 promoter activity following toxin A stimulation. Gel shift assays indicated that CREB/ATF-1 was the major proteins binding to the COX-2-CRE. Moreover, colonocytes exposed to toxin A produced reactive oxygen species (ROS), which activated p38 MAPK, MSK-1, and CREB/ATF-1, leading to subsequent COX-2 induction and PGE2 secretion. In intact mice, blockage of p38 MAPK inhibited toxin A-mediated induction of COX-2 in enterocytes as well as lamina propria cells, and significantly blocked the toxin A-induced ileal secretion of fluid and PGE2. Furthermore, a selective COX-2 inhibitor also diminished toxin A-associated ileal fluid and PGE2 secretion. The main signaling pathway for toxin A induction of human COX-2 involves ROS-mediated activation of p38 MAPK, MSK-1, CREB, and ATF-1. Toxin A triggers ileal inflammation and secretion of fluid via COX-2 induction and release of PGE2.
Publication types
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Research Support, N.I.H., Extramural
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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 / pharmacology*
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Cell Line
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Colon / cytology*
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Colon / metabolism
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Cyclic AMP / metabolism
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Cyclooxygenase 2
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Dinoprostone / metabolism*
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Dose-Response Relationship, Drug
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Electrophoresis, Polyacrylamide Gel
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Enterotoxins / pharmacology*
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Enzyme Activation
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Enzyme Inhibitors / pharmacology
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Humans
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Ileum / metabolism
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Imidazoles / pharmacology
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Immunohistochemistry
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Inflammation
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Intramolecular Oxidoreductases / metabolism
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Luciferases / metabolism
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Membrane Proteins
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Mice
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Mice, SCID
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Models, Biological
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Nitrobenzenes / pharmacology
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Phosphorylation
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Prostaglandin-E Synthases
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Prostaglandin-Endoperoxide Synthases / metabolism*
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Protein Binding
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Pyridines / pharmacology
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RNA / metabolism
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RNA, Messenger / metabolism
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Reactive Oxygen Species
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Reverse Transcriptase Polymerase Chain Reaction
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Signal Transduction
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Sulfonamides / pharmacology
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Time Factors
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Tissue Transplantation
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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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Enzyme Inhibitors
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Imidazoles
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Membrane Proteins
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Nitrobenzenes
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Pyridines
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RNA, Messenger
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Reactive Oxygen Species
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Sulfonamides
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tcdA protein, Clostridium difficile
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N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide
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RNA
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Cyclic AMP
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Luciferases
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Cyclooxygenase 2
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PTGS2 protein, human
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Prostaglandin-Endoperoxide Synthases
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p38 Mitogen-Activated Protein Kinases
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Intramolecular Oxidoreductases
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Prostaglandin-E Synthases
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Dinoprostone
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SB 203580