Entamoeba histolytica cysteine proteinases with interleukin-1 beta converting enzyme (ICE) activity cause intestinal inflammation and tissue damage in amoebiasis.

Abstract	The protozoan parasite Entamoeba histolytica causes intestinal inflammation and ulceration. Amoebic trophozoites activate the transcription factor NF-kappa B in human intestinal epithelial cells, initiating an inflammatory response programme with resultant damage to the intestinal tissue. Amoebic cysteine proteinases have been proposed as important virulence factors for amoebiasis. To test the role of amoebic cysteine proteinases in the pathogenesis of amoebic colitis, human intestinal xenografts in SCID mice were infected with E. histolytica trophozoites expressing an antisense message to ehcp5. The cysteine proteinase-deficient amoeba failed to induce intestinal epithelial cell production of the inflammatory cytokines interleukin (IL)-1B and IL-8, and caused significantly less gut inflammation and damage to the intestinal permeability barrier. The critical role of amoebic cysteine proteinases in human gut inflammation and tissue damage may be explained by our discovery that amoebic cysteine proteinases possess IL-1B converting enzyme (ICE) activity. This ICE activity could contribute to intestinal inflammation by activating human pIL-1B released by damaged intestinal cells. These results demonstrate for the first time that amoebic cysteine proteinases are a key virulence factor in amoebic colitis, and provide a novel mechanism for their activity.
Authors	Z Zhang, L Wang, K B Seydel, E Li, S Ankri, D Mirelman, S L Stanley Jr
Journal	Molecular microbiology (Mol Microbiol) Vol. 37 Issue 3 Pg. 542-8 (Aug 2000) ISSN: 0950-382X [Print] England
PMID	10931347 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)
Chemical References	Bacterial Proteins Oligonucleotides, Antisense Cysteine Endopeptidases Caspase 1
Topics	Amebiasis (etiology, genetics, parasitology, pathology) Animals Bacterial Proteins (genetics, metabolism) Caspase 1 (genetics, metabolism) Cysteine Endopeptidases (genetics, metabolism) Entamoeba histolytica (genetics, metabolism) Humans Inflammation (parasitology) Intestines (parasitology, pathology) Mice Mice, SCID Oligonucleotides, Antisense Transplantation, Heterologous

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