title: α-Enolase of Streptococcus pneumoniae induces formation of neutrophil extracellular traps.
abstract: Streptococcus pneumoniae is the most common causative agent of community-acquired pneumonia throughout the world, with high morbidity and mortality rates. A major feature of pneumococcal pneumonia is abundant neutrophil infiltration. In this study, we identified S. pneumoniae α-enolase as a neutrophil binding protein in ligand blot assay and mass spectrometry findings. Scanning electron microscopic and fluorescence microscopic analyses also revealed that S. pneumoniae α-enolase induces formation of neutrophil extracellular traps, which have been reported to bind and kill microbes. In addition, cytotoxic assay results showed that α-enolase dose-dependently increased the release of extracellular lactate dehydrogenase from human neutrophils as compared with untreated neutrophils. Furthermore, an in vitro cell migration assay using Chemotaxicell culture chambers demonstrated that α-enolase possesses neutrophil migrating activity. Interestingly, bactericidal assay findings showed that α-enolase increased neutrophil extracellular trap-dependent killing of S. pneumoniae in human blood. Moreover, pulldown assay and mass spectrometry results identified myoblast antigen 24.1D5 as an α-enolase-binding protein on human neutrophils, whereas flow cytometric analysis revealed that 24.1D5 was expressed on human neutrophils, but not on human monocytes or T cells. Together, our results indicate that α-enolase from S. pneumoniae increases neutrophil migrating activity and induces cell death of human neutrophils by releasing neutrophil extracellular traps. Furthermore, we found that myoblast antigen 24.1D5, which expressed on the surface of neutrophils, bound to α-enolase of S. pneumoniae.
authors.affiliation: Departments of Oral and Molecular Microbiology, Osaka University Graduate School of Dentistry, Suita, Osaka, 565-0871, Japan; Departments of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Suita, Osaka, 565-0871, Japan.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Mori
authors.affiliation: Department of Cell Membrane Biology, Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka, 567-0047, Japan, and.
authors.forename: Masaya
authors.initials: M
authors.lastname: Yamaguchi
authors.affiliation: Departments of Oral and Molecular Microbiology, Osaka University Graduate School of Dentistry, Suita, Osaka, 565-0871, Japan. Electronic address: terao@dent.osaka-u.ac.jp.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Terao
authors.affiliation: Research Collaboration Center on Emerging and Reemerging Infections 6F, Department of Medical Sciences, Ministry of Public Health, Muang Nonthaburi 11000, Thailand.
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Hamada
authors.affiliation: Departments of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Suita, Osaka, 565-0871, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Ooshima
authors.affiliation: Departments of Oral and Molecular Microbiology, Osaka University Graduate School of Dentistry, Suita, Osaka, 565-0871, Japan.
authors.forename: Shigetada
authors.initials: S
authors.lastname: Kawabata
mesh_terms: D045744:Cell Line, Tumor; D002465:Cell Movement / Q000276:immunology; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000276:immunology / Q000378:metabolism; D020556:Neutrophil Infiltration / Q000276:immunology; D009504:Neutrophils / Q000276:immunology / Q000378:metabolism*; D010751:Phosphopyruvate Hydratase / Q000276:immunology / Q000378:metabolism*; D011008:Pneumococcal Infections / Q000201:enzymology* / Q000276:immunology; D013296:Streptococcus pneumoniae / Q000201:enzymology* / Q000276:immunology
chemical_list: D007770:L-Lactate Dehydrogenase; D010751:Phosphopyruvate Hydratase