title: Streptococcus sanguinis induces foam cell formation and cell death of macrophages in association with production of reactive oxygen species.
abstract: Streptococcus sanguinis, a normal inhabitant of the human oral cavity, is a common streptococcal species implicated in infective endocarditis. Herein, we investigated the effects of infection with S. sanguinis on foam cell formation and cell death of macrophages. Infection with S. sanguinis stimulated foam cell formation of THP-1, a human macrophage cell line. At a multiplicity of infection >100, S. sanguinis-induced cell death of the macrophages. Viable bacterial infection was required to trigger cell death because heat-inactivated S. sanguinis did not induce cell death. The production of cytokines interleukin-1β and tumor necrosis factor-α from macrophages was also stimulated during bacterial infection. Inhibition of the production of reactive oxygen species (ROS) resulted in reduced cell death, suggesting an association of ROS with cell death. Furthermore, S. sanguinis-induced cell death appeared to be independent of activation of inflammasomes, because cleavage of procaspase-1 was not evident in infected macrophages.
authors.affiliation: Department of Oral Frontier Biology, Osaka University Graduate School of Dentistry, Suita-Osaka, Japan.
authors.forename: Nobuo
authors.initials: N
authors.lastname: Okahashi
authors.forename: Toshinori
authors.initials: T
authors.lastname: Okinaga
authors.forename: Atsuo
authors.initials: A
authors.lastname: Sakurai
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Terao
authors.forename: Masanobu
authors.initials: M
authors.lastname: Nakata
authors.forename: Keisuke
authors.initials: K
authors.lastname: Nakashima
authors.forename: Seikou
authors.initials: S
authors.lastname: Shintani
authors.forename: Shigetada
authors.initials: S
authors.lastname: Kawabata
authors.forename: Takashi
authors.initials: T
authors.lastname: Ooshima
authors.forename: Tatsuji
authors.initials: T
authors.lastname: Nishihara
mesh_terms: D016923:Cell Death; D002460:Cell Line; D005487:Foam Cells; D006801:Humans; D053583:Interleukin-1beta / Q000378:metabolism; D008264:Macrophages / Q000276:immunology* / Q000382:microbiology*; D017382:Reactive Oxygen Species / Q000378:metabolism / Q000633:toxicity*; D013291:Streptococcus / Q000276:immunology / Q000472:pathogenicity*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D053583:Interleukin-1beta; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha