title: Staphylococcal cysteine protease staphopain B (SspB) induces rapid engulfment of human neutrophils and monocytes by macrophages.
abstract: Abstract Circulating neutrophils and monocytes constitute the first line of antibacterial defence, which is responsible for the phagocytosis and killing of microorganisms. Previously, we have described that the staphylococcal cysteine proteinase staphopain B (SspB) cleaves CD11b on peripheral blood phagocytes, inducing the rapid development of features of atypical cell death in protease-treated cells. Here, we report that exposure of phagocytes to SspB critically impairs their antibacterial functions. Specifically, SspB blocks phagocytosis of Staphylococcus aureus by both neutrophils and monocytes, represses their chemotactic activity and induces extensive, nonphlogistic clearance of SspB-treated cells by macrophages. The proteinase also cleaves CD31, a major repulsion ('do not-eat-me') signal, on the surface of neutrophils. We suggest that both proteolytic degradation of repulsion signals and induction of 'eat-me' signals on the surface of leukocytes are responsible for the observed intensive phagocytosis of SspB-treated neutrophils by human monocyte-derived macrophages. Collectively, this may lead to the depletion of functional neutrophils at the site of infection, thus facilitating staphylococcal colonisation and spreading.
authors.affiliation: Department of Microbiology, Faculty of Biochemistry, Biophysics, and Biotechnology, Jagiellonian University, 30-386 Krakow, Poland.
authors.forename: Jan
authors.initials: J
authors.lastname: Smagur
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Guzik
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Bzowska
authors.forename: Mateusz
authors.initials: M
authors.lastname: Kuzak
authors.forename: Miroslaw
authors.initials: M
authors.lastname: Zarebski
authors.forename: Tomasz
authors.initials: T
authors.lastname: Kantyka
authors.forename: Michal
authors.initials: M
authors.lastname: Walski
authors.forename: Barbara
authors.initials: B
authors.lastname: Gajkowska
authors.forename: Jan
authors.initials: J
authors.lastname: Potempa
mesh_terms: D002478:Cells, Cultured; D003546:Cysteine Endopeptidases / Q000276:immunology / Q000494:pharmacology*; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000187:drug effects* / Q000276:immunology; D008264:Macrophages / Q000187:drug effects / Q000276:immunology; D046529:Microscopy, Electron, Transmission; D009504:Neutrophils / Q000187:drug effects* / Q000276:immunology; D010587:Phagocytosis / Q000187:drug effects* / Q000276:immunology; D013210:Staphylococcus / Q000276:immunology*
chemical_list: D003546:Cysteine Endopeptidases; C479137:staphopain B protein, Staphylococcus aureus