FEMS Immunology and Medical Microbiology 2012-12-01

Nonencapsulated Streptococcus pneumoniae resists extracellular human neutrophil elastase- and cathepsin G-mediated killing.

Dieke van der Windt, Hester J Bootsma, Peter Burghout, Christa E van der Gaast-de Jongh, Peter W M Hermans, Michiel van der Flier

Index: FEMS Immunol. Med. Microbiol. 66(3) , 445-8, (2012)

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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.© 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.