title: Acinetobacter baumannii outer membrane vesicles elicit a potent innate immune response via membrane proteins.
abstract: Acinetobacter baumannii is increasingly becoming a major nosocomial pathogen. This opportunistic pathogen secretes outer membrane vesicles (OMVs) that interact with host cells. The aim of this study was to investigate the ability of A. baumannii OMVs to elicit a pro-inflammatory response in vitro and the immunopathology in response to A. baumannii OMVs in vivo. OMVs derived from A. baumannii ATCC 19606(T) induced expression of pro-inflammatory cytokine genes, interleukin (IL)-1β and IL-6, and chemokine genes, IL-8, macrophage inflammatory protein-1α, and monocyte chemoattractant protein-1, in epithelial cells in a dose-dependent manner. Disintegration of OMV membrane with ethylenediaminetetraacetic acid resulted in low expression of pro-inflammatory cytokine genes, as compared with the response to intact OMVs. In addition, proteinase K-treated A. baumannii OMVs did not induce significant increase in expression of pro-inflammatory cytokine genes above the basal level, suggesting that the surface-exposed membrane proteins in intact OMVs are responsible for pro-inflammatory response. Early inflammatory processes, such as vacuolization and detachment of epithelial cells and neutrophilic infiltration, were clearly observed in lungs of mice injected with A. baumannii OMVs. Our data demonstrate that OMVs produced by A. baumannii elicit a potent innate immune response, which may contribute to immunopathology of the infected host.
authors: Department of Microbiology, Kyungpook National University School of Medicine, Daegu, Korea.
authors: So Hyun
authors: SH
authors: Jun
authors: Jung Hwa
authors: JH
authors: Lee
authors: Bo Ra
authors: BR
authors: Kim
authors: Seung Il
authors: SI
authors: Kim
authors: Tae In
authors: TI
authors: Park
authors: Je Chul
authors: JC
authors: Lee
authors: Yoo Chul
authors: YC
authors: Lee
mesh_terms: D040981:Acinetobacter baumannii / Q000187:drug effects / Q000276:immunology*; D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology*; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D004492:Edetic Acid / Q000494:pharmacology; D019286:Endopeptidase K / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D005260:Female; D006801:Humans; D007113:Immunity, Innate / Q000187:drug effects / Q000276:immunology*; D007249:Inflammation / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation / Q000235:genetics; D022142:Secretory Vesicles / Q000187:drug effects / Q000276:immunology*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D016207:Cytokines; D004492:Edetic Acid; D019286:Endopeptidase K
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