title: Klebsiella pneumoniae secretes outer membrane vesicles that induce the innate immune response.
abstract: Outer membrane vesicles (OMVs) derived from pathogenic Gram-negative bacteria are an important vehicle for delivery of effector molecules to host cells, but the production of OMVs from Klebsiella pneumoniae, an opportunistic pathogen of both nosocomial and community-acquired infections, and their role in bacterial pathogenesis have not yet been determined. In the present study, we examined the production of OMVs from K. pneumoniae and determined the induction of the innate immune response against K. pneumoniae OMVs. Klebsiella pneumoniae ATCC 13883 produced and secreted OMVs during in vitro culture. Proteomic analysis revealed that 159 different proteins were associated with K. pneumoniae OMVs. Klebsiella pneumoniae OMVs did not inhibit cell growth or induce cell death. However, these vesicles induced expression of proinflammatory cytokine genes such as interleukin (IL)-1β and IL-8 in epithelial cells. An intratracheal challenge of K. pneumoniae OMVs in neutropenic mice resulted in severe lung pathology similar to K. pneumoniae infection. In conclusion, K. pneumoniae produces OMVs like other pathogenic Gram-negative bacteria and K. pneumoniae OMVs are a molecular complex that induces the innate immune response.
authors.affiliation: Departement of Microbiology, Kyungpook National University School of Medicine, Daegu, South Korea.
authors.forename: Je Chul
authors.initials: JC
authors.lastname: Lee
authors.forename: Eun Jeoung
authors.initials: EJ
authors.lastname: Lee
authors.forename: Jung Hwa
authors.initials: JH
authors.lastname: Lee
authors.forename: So Hyun
authors.initials: SH
authors.lastname: Jun
authors.forename: Chi Won
authors.initials: CW
authors.lastname: Choi
authors.forename: Seung Il
authors.initials: SI
authors.lastname: Kim
authors.forename: Sang Sun
authors.initials: SS
authors.lastname: Kang
authors.forename: Sunghee
authors.initials: S
authors.lastname: Hyun
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000032:analysis; D016207:Cytokines / Q000096:biosynthesis; D004847:Epithelial Cells / Q000276:immunology; D055354:Exosomes / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism*; D005260:Female; D020869:Gene Expression Profiling; D006651:Histocytochemistry; D007113:Immunity, Innate; D007711:Klebsiella pneumoniae / Q000276:immunology* / Q000378:metabolism*; D008168:Lung / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D008853:Microscopy; D011014:Pneumonia / Q000139:chemically induced / Q000473:pathology; D020543:Proteome / Q000032:analysis
chemical_list: D001426:Bacterial Proteins; D016207:Cytokines; D020543:Proteome