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Evasion of macrophage scavenger receptor A-mediated recognition by pathogenic streptococci

Författare:
Publiceringsår: 2008
Språk: Engelska
Sidor: 3068-3079
Publikation/Tidskrift/Serie: European Journal of Immunology
Volym: 38
Nummer: 11
Dokumenttyp: Artikel
Förlag: WILEY-VCH Verlag GmbH & Co

Sammanfattning

PRR recognize conserved structures on pathogenic microbes and are important for the defense against invading microorganisms. However, accumulating evidence indicates that many pathogens have evolved mechanisms to avoid recognition by PRR. One type of PRR is the macrophage scavenger receptor A (SR-A), which has been shown to play an important role in recognition and non-opsonic phagocytosis of pathogenic bacteria. The bacterial ligands for SR-A have been suggested to be LPS or lipoteichoic acid. Here, we use murine bone marrow-derived macrophages to analyze the role of SR-A in non-opsonic phagocytosis of two major Gram-positive pathogens, streptococcus agalactiae (group B streptococcus; GBS) and Streptococcus pyogenes. We show that the polysaccharide capsule of GBS and the surface M protein of S. pyogenes, two important virulence factors, prevent SR-A-mediated non-opsonic phagocytosis of streptococci. The sialic acid moiety of the GBS capsule was crucial for its ability to prevent recognition by SR-A. Moreover, we show that a ligand on GBS recognized by SR-A in the absence of capsule is the surface lipoprotein BIr. These findings represent the first example of a microbial strategy to prevent recognition by SR-A and suggest that bacterial surface proteins may be of importance as ligands for SR-A.

Disputation

Nyckelord

  • Medicine and Health Sciences
  • Scavenger receptor A
  • Polysaccharide capsule
  • M protein
  • Macrophage
  • streptococcus

Övrigt

Published
Yes
  • ISSN: 0014-2980

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