Bacillus anthracis oedema toxin as a cause of tissue necrosis and cell type-specific cytotoxicity.
Oedema factor (OF) and protective antigen (PA) are secreted by Bacillus anthracis, and their binary combination yields oedema toxin (OT). Following PA-mediated delivery to the cytosol, OF functions as an adenylate cyclase generating high levels of cAMP. To assess OT as a possible cause of tissue damage and cell death, a novel approach was developed, which utilized a developing zebrafish embryo model to study toxin activity. Zebrafish embryos incubated with OT exhibited marked necrosis of the liver, cranium and gastrointestinal tract, as well as reduced swim bladder inflation. The OT-treated embryos survived after all stages of development but succumbed to the toxin within 7 days. Additional analysis of specific cell lines, including macrophage and non-macrophage, showed OT-induced cell death is cell type-specific. There was no discernible correlation between levels of OF-generated cAMP and cell death. Depending on the type of cell analysed, cell death could be detected in low levels of cAMP, and, conversely, cell survival was observed in one cell line in which high levels of cAMP were found following treatment with OT. Collectively, these data suggest OT is cytotoxic in a cell-dependent manner and may contribute to disease through direct cell killing leading to tissue necrosis.
Voth
Daniel E
DE
Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
Hamm
Elaine E
EE
Nguyen
Lan G
LG
Tucker
Amy E
AE
Salles
Isabelle I
II
Ortiz-Leduc
William
W
Ballard
Jimmy D
JD
D000262:Adenylyl Cyclases / Q000502:physiology*; D000400:Air Sacs / Q000473:pathology; D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics / Q000502:physiology* / Q000633:toxicity; D017209:Apoptosis; D001408:Bacillus anthracis / Q000378:metabolism; D001427:Bacterial Toxins / Q000235:genetics / Q000633:toxicity; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D000242:Cyclic AMP / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000473:pathology*; D041981:Gastrointestinal Tract / Q000473:pathology; D008099:Liver / Q000473:pathology; D008264:Macrophages / Q000166:cytology* / Q000187:drug effects; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009154:Mutation; D009336:Necrosis; D012886:Skull / Q000473:pathology; D015027:Zebrafish
D000942:Antigens, Bacterial; D001427:Bacterial Toxins; C030325:anthrax toxin; D000242:Cyclic AMP; D000262:Adenylyl Cyclases