title: A critical role for hemolysin in Vibrio fluvialis-induced IL-1β secretion mediated by the NLRP3 inflammasome in macrophages.
abstract: Vibrio fluvialis causes human diarrhea, but the pathogenesis is not well-studied. We hypothesized that V. fluvialis-secreted hemolysin (VFH) may induce IL-1β secretion through the activation of the NLRP3 inflammasome and contribute to the pathogenicity of V. fluvialis. To examine this possibility, we constructed VFH mutant and complement strains and demonstrated that V. fluvialis-induced IL-1β production and cytotoxicity in human monocytic THP-1 cells and mouse macrophages is attributed to VFH. To evaluate the role of VFH in vivo, we infected adult C57BL/6 mice intraperitoneally and suckling C57/B6 mice orally with various strains. The mice treated with 10(8) CFU wild-type V. fluvialis or cell-free supernatant containing VFH induced significantly higher IL-1β production in peritoneal lavage fluid or in colon compared with those infected with the mutant strain, while no effect on TNF and IL-6 production was observed at day 5 or 24 h post-infection. VFH contributed to pathological changes and IL-1β release independent of colonization of V. fluvialis in the colon. VFH has no effect on the synthesis of pro-IL-1β, but rather it triggers the processing of pro-IL-1β into IL-1β. Furthermore, using deficient mouse strains, we verified that V. fluvialis-induced IL-1β is mediated through activation of Caspase-1 and the NLRP3 inflammasome ex vivo. Confocal microscopy suggests that VFH contributes to cathepsin B release. Furthermore, V. fluvialis-induced IL-1β secretion requires potassium (K(+)) eﬄux and reactive oxygen species production. Our results provide new evidence for the role of VFH in the activation of the NLRP3 inflammasome and pathogenesis in response to V. fluvialis infection. Summary Sentence: Vibrio fluvialis-secreted hemolysin induces IL-1β secretion through the activation of the NLRP3 inflammasome and contributes to the pathogenicity of V. fluvialis.
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention - Chinese Center for Disease Control and Prevention Beijing, China.
authors.forename: Liqiong
authors.initials: L
authors.lastname: Song
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention - Chinese Center for Disease Control and Prevention Beijing, China.
authors.forename: Yuanming
authors.initials: Y
authors.lastname: Huang
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention - Chinese Center for Disease Control and Prevention Beijing, China.
authors.forename: Meng
authors.initials: M
authors.lastname: Zhao
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention - Chinese Center for Disease Control and Prevention Beijing, China.
authors.forename: Zhihao
authors.initials: Z
authors.lastname: Wang
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention - Chinese Center for Disease Control and Prevention Beijing, China.
authors.forename: Shujing
authors.initials: S
authors.lastname: Wang
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention - Chinese Center for Disease Control and Prevention Beijing, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Sun
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention - Chinese Center for Disease Control and Prevention Beijing, China.
authors.forename: Biao
authors.initials: B
authors.lastname: Kan
authors.affiliation: Unit of Innate Immunity, Key Laboratory of Molecular Virology and Immunology, Institute Pasteur of Shanghai - Chinese Academy of Sciences Shanghai, China.
authors.forename: Guangxun
authors.initials: G
authors.lastname: Meng
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention - Chinese Center for Disease Control and Prevention Beijing, China ; Unit of Innate Immunity, Key Laboratory of Molecular Virology and Immunology, Institute Pasteur of Shanghai - Chinese Academy of Sciences Shanghai, China.
authors.forename: Weili
authors.initials: W
authors.lastname: Liang
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention - Chinese Center for Disease Control and Prevention Beijing, China ; Unit of Innate Immunity, Key Laboratory of Molecular Virology and Immunology, Institute Pasteur of Shanghai - Chinese Academy of Sciences Shanghai, China.
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Ren
keywords: IL-1β; NLRP3 inflammasomes; Vibrio fluvialis; hemolysin; macrophages