title: Nonencapsulated Streptococcus pneumoniae resists extracellular human neutrophil elastase- and cathepsin G-mediated killing.
abstract: Although the Streptococcus pneumoniae polysaccharide capsule is an important virulence factor, ~ 15% of carriage isolates are nonencapsulated. Nonencapsulated S. pneumoniae are a cause of mucosal infections. Recent studies have shown that neutrophils kill S. pneumoniae predominately through neutrophil proteases, such as elastase and cathepsin G. Another recent finding is that nonencapsulated pneumococci have greater resistance to resist cationic antimicrobial peptides that are important in mucosal immunity. We here show that nonencapsulated pneumococci have greater resistance to extracellular human neutrophil elastase- and cathepsin G-mediated killing than isogenic encapsulated pneumococci. Resistance to extracellular neutrophil protease-mediated killing is likely to be of greater relative importance on mucosal surfaces compared to other body sites.
authors.affiliation: Laboratory of Pediatric Infectious Diseases, Radboud University Medical Centre, Nijmegen, The Netherlands.
authors.forename: Dieke
authors.initials: D
authors.lastname: van der Windt
authors.forename: Hester J
authors.initials: HJ
authors.lastname: Bootsma
authors.forename: Peter
authors.initials: P
authors.lastname: Burghout
authors.forename: Christa E
authors.initials: CE
authors.lastname: van der Gaast-de Jongh
authors.forename: Peter W M
authors.initials: PW
authors.lastname: Hermans
authors.forename: Michiel
authors.initials: M
authors.lastname: van der Flier
mesh_terms: D016667:Bacterial Capsules / Q000276:immunology*; D056649:Cathepsin G / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D057131:Immune Evasion; D019272:Leukocyte Elastase / Q000276:immunology* / Q000378:metabolism; D050296:Microbial Viability / Q000187:drug effects; D009504:Neutrophils / Q000201:enzymology / Q000276:immunology / Q000382:microbiology; D013296:Streptococcus pneumoniae / Q000276:immunology* / Q000502:physiology
chemical_list: C534094:CTSG protein, human; D056649:Cathepsin G; D019272:Leukocyte Elastase