title: p38 MAP kinase activation by Clostridium difficile toxin A mediates monocyte necrosis, IL-8 production, and enteritis.
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.
authors.affiliation: Gastroenterology Division, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA. mwarny@caregroup.havard.edu
authors.forename: M
authors.initials: M
authors.lastname: Warny
authors.forename: A C
authors.initials: AC
authors.lastname: Keates
authors.forename: S
authors.initials: S
authors.lastname: Keates
authors.forename: I
authors.initials: I
authors.lastname: Castagliuolo
authors.forename: J K
authors.initials: JK
authors.lastname: Zacks
authors.forename: S
authors.initials: S
authors.lastname: Aboudola
authors.forename: A
authors.initials: A
authors.lastname: Qamar
authors.forename: C
authors.initials: C
authors.lastname: Pothoulakis
authors.forename: J T
authors.initials: JT
authors.lastname: LaMont
authors.forename: C P
authors.initials: CP
authors.lastname: Kelly
mesh_terms: D000818:Animals; D001427:Bacterial Toxins / Q000378:metabolism / Q000494:pharmacology*; D002460:Cell Line; D016360:Clostridioides difficile / Q000276:immunology* / Q000378:metabolism; D004751:Enteritis / Q000201:enzymology / Q000276:immunology* / Q000382:microbiology; D004761:Enterocolitis, Pseudomembranous / Q000201:enzymology / Q000276:immunology / Q000382:microbiology; D004768:Enterotoxins / Q000378:metabolism / Q000494:pharmacology*; D004789:Enzyme Activation; D005786:Gene Expression Regulation / Q000187:drug effects; D006031:Glycosylation; D016209:Interleukin-8 / Q000096:biosynthesis* / Q000235:genetics; D020935:MAP Kinase Signaling System; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D048055:Mitogen-Activated Protein Kinase 8; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism*; D009000:Monocytes / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D020556:Neutrophil Infiltration / Q000276:immunology; D009504:Neutrophils / Q000276:immunology; D048051:p38 Mitogen-Activated Protein Kinases; D020741:rho GTP-Binding Proteins / Q000276:immunology / Q000378:metabolism
chemical_list: D001427:Bacterial Toxins; D004768:Enterotoxins; D016209:Interleukin-8; C041348:tcdA protein, Clostridium difficile; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048055:Mitogen-Activated Protein Kinase 8; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D020741:rho GTP-Binding Proteins