title: Fusobacterium nucleatum infection of gingival epithelial cells leads to NLRP3 inflammasome-dependent secretion of IL-1β and the danger signals ASC and HMGB1.
abstract: Fusobacterium nucleatum is an invasive anaerobic bacterium that is associated with periodontal disease. Previous studies have focused on virulence factors produced by F. nucleatum, but early recognition of the pathogen by the immune system remains poorly understood. Although an inflammasome in gingival epithelial cells (GECs) can be stimulated by danger-associated molecular patterns (DAMPs) (also known as danger signals) such as ATP, inflammasome activation by this periodontal pathogen has yet to be described in these cells. This study therefore examines the effects of F. nucleatum infection on pro-inflammatory cytokine expression and inflammasome activation in GECs. Our results indicate that infection induces translocation of NF-κB into the nucleus, resulting in cytokine gene expression. In addition, infection activates the NLRP3 inflammasome, which in turn activates caspase-1 and stimulates secretion of mature IL-1β. Unlike other pathogens studied until now, F. nucleatum activates the inflammasome in GECs in the absence of exogenous DAMPs such as ATP. Finally, infection promotes release of other DAMPs that mediate inflammation, such as high-mobility group box 1 protein and apoptosis-associated speck-like protein, with a similar time-course as caspase-1 activation. Thus, F. nucleatum expresses the pathogen-associated molecular patterns necessary to activate NF-κB and also provides an endogenous DAMP to stimulate the inflammasome and further amplify inflammation through secretion of secondary DAMPs.
authors.affiliation: Department of Biomedical Sciences, University of the Pacific, Arthur Dugoni School of Dentistry, San Francisco, CA, 95343, USA.
authors.forename: Fiona Q
authors.initials: FQ
authors.lastname: Bui
authors.affiliation: Department of Biomedical Sciences, University of the Pacific, Arthur Dugoni School of Dentistry, San Francisco, CA, 95343, USA.|Immunobiology Program, Instituto de Biofísica Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, 21941, Brazil.
authors.forename: Larry
authors.initials: L
authors.lastname: Johnson
authors.affiliation: Department of Periodontology and Emerging Pathogens Institute, University of Florida, Gainesville, FL, 32610, USA.
authors.forename: JoAnn
authors.initials: J
authors.lastname: Roberts
authors.affiliation: Department of Biomedical Sciences, University of the Pacific, Arthur Dugoni School of Dentistry, San Francisco, CA, 95343, USA.
authors.forename: Shu-Chen
authors.initials: SC
authors.lastname: Hung
authors.affiliation: Department of Periodontology and Emerging Pathogens Institute, University of Florida, Gainesville, FL, 32610, USA.
authors.forename: Jungnam
authors.initials: J
authors.lastname: Lee
authors.affiliation: Department of Periodontology and Emerging Pathogens Institute, University of Florida, Gainesville, FL, 32610, USA.
authors.forename: Kalina Rosenova
authors.initials: KR
authors.lastname: Atanasova
authors.affiliation: Center for Molecular and Clinical Immunology, Chang Gung University, Gueishan, Taoyuan 333, Taiwan.
authors.forename: Pei-Rong
authors.initials: PR
authors.lastname: Huang
authors.affiliation: Department of Periodontology and Emerging Pathogens Institute, University of Florida, Gainesville, FL, 32610, USA.
authors.forename: Özlem
authors.initials: Ö
authors.lastname: Yilmaz
authors.affiliation: Department of Biomedical Sciences, University of the Pacific, Arthur Dugoni School of Dentistry, San Francisco, CA, 95343, USA.
authors.forename: David M
authors.initials: DM
authors.lastname: Ojcius
mesh_terms: D053468:CARD Signaling Adaptor Proteins; D020170:Caspase 1 / Q000378:metabolism; D002460:Cell Line; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism / Q000382:microbiology; D005674:Fusobacterium Infections / Q000378:metabolism* / Q000382:microbiology; D016967:Fusobacterium nucleatum / Q000472:pathogenicity; D005881:Gingiva / Q000166:cytology / Q000378:metabolism / Q000382:microbiology*; D024243:HMGB1 Protein / Q000378:metabolism*; D054884:Host-Pathogen Interactions / Q000502:physiology; D006801:Humans; D058847:Inflammasomes / Q000378:metabolism; D053583:Interleukin-1beta / Q000235:genetics / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D053468:CARD Signaling Adaptor Proteins; D003598:Cytoskeletal Proteins; D024243:HMGB1 Protein; C585491:HMGB1 protein, human; D058847:Inflammasomes; D053583:Interleukin-1beta; D016328:NF-kappa B; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C453881:NLRP3 protein, human; C402202:PYCARD protein, human; D020170:Caspase 1