title: Macrophage Apoptosis Triggered by IpaD from Shigella flexneri.
abstract: Shigellosis, a potentially severe bacillary dysentery, is an infectious gastrointestinal disease caused by Shigella spp. Shigella invades the human colonic epithelium and avoids clearance by promoting apoptosis of resident immune cells in the gut. This process is dependent on the Shigella type III secretion system (T3SS), which injects effector proteins into target cells to alter their normal cellular functions. Invasion plasmid antigen D (IpaD) is a structural component that forms a complex at the tip of the T3SS apparatus needle. Recently, IpaD has also been shown to indirectly induce apoptosis in B lymphocytes. In this study, we explored the cytotoxicity profile during macrophage infection by Shigella and discovered that the pathogen induces macrophage cell death independent of caspase-1. Our results demonstrate that IpaD triggers apoptosis in macrophages through activation of host caspases accompanied by mitochondrial disruption. Additionally, we found that the IpaD N-terminal domain is necessary for macrophage killing and SipD, a structural homologue from Salmonella, was found to promote similar cytotoxicity. Together, these findings indicate that IpaD is a contributing factor to macrophage cell death during Shigella infection.
authors.affiliation: Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, Kansas, USA.
authors.forename: Olivia
authors.initials: O
authors.lastname: Arizmendi
authors.affiliation: Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, Kansas, USA.
authors.forename: William D
authors.initials: WD
authors.lastname: Picking
authors.affiliation: Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, Kansas, USA wendy.picking@ku.edu.
authors.forename: Wendy L
authors.initials: WL
authors.lastname: Picking
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D020169:Caspases / Q000235:genetics* / Q000378:metabolism; D016923:Cell Death; D002460:Cell Line; D005786:Gene Expression Regulation; D054884:Host-Pathogen Interactions; D006801:Humans; D008264:Macrophages / Q000382:microbiology* / Q000473:pathology; D051379:Mice; D008928:Mitochondria / Q000382:microbiology* / Q000473:pathology; D000072417:Protein Domains; D012763:Shigella flexneri / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D015398:Signal Transduction; D000069296:Type III Secretion Systems / Q000235:genetics / Q000378:metabolism
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C095770:IpaD protein, Shigella flexneri; D000069296:Type III Secretion Systems; D020169:Caspases