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Streptococcal M protein: a multipotent and powerful inducer of inflammation

Lisa I Påhlman1, Matthias Mörgelin, Jana Eckert

  • 1Department of Clinical Sciences, Section for Clinical and Experimental Infection Medicine, Biomedicinskt Centrum B14, Lund University, Tornavägen 10, SE-221 84 Lund, Sweden.

Journal of Immunology (Baltimore, Md. : 1950)
|July 5, 2006
PubMed

Insights

Streptococcus pyogenes M protein triggers an inflammatory response by interacting with monocytes. Neutrophil heparin-binding protein (HBP) amplifies this, contributing to severe infections like necrotizing fasciitis.

Area of Science:

  • Immunology
  • Microbiology
  • Pathophysiology

Background:

  • Streptococcus pyogenes causes severe infections with significant inflammation.
  • The mechanisms underlying this inflammatory response require further elucidation.

Purpose of the Study:

  • To investigate the interaction between Streptococcus pyogenes M protein and human immune cells.
  • To determine the role of neutrophil-derived heparin-binding protein (HBP) in modulating this interaction and subsequent inflammation.

Main Methods:

  • Monocyte activation assays using M protein and HBP.
  • Cytokine expression analysis (IL-6, IL-1beta, TNF-alpha).
  • Analysis of patient tissue biopsies from necrotizing fasciitis cases.

Main Results:

  • Streptococcal M protein directly interacts with Toll-like receptor 2 (TLR2) on human monocytes.
  • This interaction leads to the expression of pro-inflammatory cytokines IL-6, IL-1beta, and TNF-alpha.
  • Neutrophil-derived HBP significantly enhances monocyte co-stimulation via CD11/CD18, amplifying the inflammatory response. HBP and M protein synergy observed.

Conclusions:

  • Streptococcus pyogenes M protein and HBP act synergistically to induce a potent inflammatory response.
  • This synergistic action likely contributes to the severe pathology observed in infections like necrotizing fasciitis.
  • Targeting these interactions may offer therapeutic strategies for severe streptococcal infections.

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