Abstract
The Streptococcus pyogenes cysteine protease SpeB (streptococcal pyrogenic exotoxin B) is important for the invasive potential of the bacteria, but its production is down-regulated following systemic infection. This prompted us to investigate if SpeB potentiated the host immune response after systemic spreading. Addition of SpeB to human plasma increased plasma-mediated bacterial killing and prolonged coagulation time through the intrinsic pathway of coagulation. This effect was independent of the enzymatic activity of SpeB and was mediated by a noncovalent medium-affinity binding and modification of the serpin A1AT (α-1 antitrypsin). Consequently, addition of A1AT to plasma increased bacterial survival. Sequestration of A1AT by SpeB led to enhanced contact system activation, supported by increased bacterial growth in prekallikrein deficient plasma. In a mouse model of systemic infection, administration of SpeB reduced significantly bacterial dissemination. The findings reveal an additional layer of complexity to host-microbe interactions that may be of benefit in the treatment of severe bacterial infections.
| Original language | English |
|---|---|
| Journal | Biochemical Journal |
| Volume | 434 |
| Issue number | 1 |
| Pages (from-to) | 123-32 |
| Number of pages | 10 |
| ISSN | 0264-6021 |
| DOIs | |
| Publication status | Published - 15 Feb 2011 |
Keywords
- Animals
- Bacterial Proteins
- Chemotaxis
- Exotoxins
- Humans
- Leukocytes, Mononuclear
- Male
- Mice
- Mice, Inbred BALB C
- Protein Binding
- Streptococcal Infections
- Streptococcus pyogenes
- alpha 1-Antitrypsin