title: Clostridium difficile toxin A regulates inducible cyclooxygenase-2 and prostaglandin E2 synthesis in colonocytes via reactive oxygen species and activation of p38 MAPK.
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.
authors.affiliation: Division of Gastroenterology, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, USA.
authors.forename: Ho
authors.initials: H
authors.lastname: Kim
authors.forename: Sang Hoon
authors.initials: SH
authors.lastname: Rhee
authors.forename: Efi
authors.initials: E
authors.lastname: Kokkotou
authors.forename: Xi
authors.initials: X
authors.lastname: Na
authors.forename: Tor
authors.initials: T
authors.lastname: Savidge
authors.forename: Mary P
authors.initials: MP
authors.lastname: Moyer
authors.forename: Charalabos
authors.initials: C
authors.lastname: Pothoulakis
authors.forename: J Thomas
authors.initials: JT
authors.lastname: LaMont
mesh_terms: D000818:Animals; D001427:Bacterial Toxins / Q000494:pharmacology*; D002460:Cell Line; D003106:Colon / Q000166:cytology* / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D004768:Enterotoxins / Q000494:pharmacology*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007082:Ileum / Q000378:metabolism; D007093:Imidazoles / Q000494:pharmacology; D007150:Immunohistochemistry; D007249:Inflammation; D019746:Intramolecular Oxidoreductases / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D008565:Membrane Proteins; D051379:Mice; D016513:Mice, SCID; D008954:Models, Biological; D009578:Nitrobenzenes / Q000494:pharmacology; D010766:Phosphorylation; D000071876:Prostaglandin-E Synthases; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D011485:Protein Binding; D011725:Pyridines / Q000494:pharmacology; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D017382:Reactive Oxygen Species; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013449:Sulfonamides / Q000494:pharmacology; D013997:Time Factors; D016378:Tissue Transplantation; D014162:Transfection; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D001427:Bacterial Toxins; D004768:Enterotoxins; D004791:Enzyme Inhibitors; D007093:Imidazoles; D008565:Membrane Proteins; D009578:Nitrobenzenes; D011725:Pyridines; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D013449:Sulfonamides; C041348:tcdA protein, Clostridium difficile; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; D012313:RNA; D000242:Cyclic AMP; D008156:Luciferases; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D048051:p38 Mitogen-Activated Protein Kinases; D019746:Intramolecular Oxidoreductases; D000071876:Prostaglandin-E Synthases; D015232:Dinoprostone; C093642:SB 203580