Related Experiment Videos
Murine macrophage activation by staphylococcal exotoxins
S D Fleming1, J J Iandolo, S K Chapes
1Division of Biology, Kansas State University, Manhattan 66506.
Abstract:
We investigated the ability of staphylococcal enterotoxins A and B, exfoliative toxins A and B, and toxic shock syndrome toxin 1 to activate macrophages. All of the toxins tested had the potential to stimulate tumoricidal activity in peritoneal macrophages from lipopolysaccharide-responsive C3HeB/FeJ mice. In contrast, none of the toxins activated cytotoxicity in lipopolysaccharide-unresponsive macrophages from C3H/HeJ mice. We also studied toxin stimulation of monokine secretion. Staphylococcal enterotoxin A, toxic shock syndrome toxin 1, and both exfoliative toxins triggered C3HeB/FeJ macrophages to secrete tumor necrosis factor alpha, but enterotoxin B induced only marginal amounts of tumor necrosis factor. All of the toxins used stimulated interleukin-6 production by macrophages from both strains of mice. Nitric oxide is produced in response to the exfoliative toxins only by the lipopolysaccharide-responsive macrophages. These results suggest that macrophages respond differently to several staphylococcal exotoxins.
Insights
Staphylococcal toxins activate macrophages from responsive mice, but not unresponsive ones. Macrophages produce various cytokines and nitric oxide depending on toxin type and mouse strain.
Area of Science:
- Immunology
- Microbiology
Background:
- Staphylococcal exotoxins are virulence factors with immunomodulatory potential.
- Macrophages play a critical role in innate and adaptive immunity.
Purpose of the Study:
- To investigate the differential activation of macrophages by staphylococcal enterotoxins (SEs), exfoliative toxins (ETs), and toxic shock syndrome toxin 1 (TSST-1).
- To compare the effects of these toxins on macrophage tumoricidal activity and cytokine secretion in lipopolysaccharide (LPS)-responsive versus LPS-unresponsive mice.
Main Methods:
- Peritoneal macrophages from C3HeB/FeJ (LPS-responsive) and C3H/HeJ (LPS-unresponsive) mice were cultured.
- Cells were treated with SE A, SE B, ET A, ET B, or TSST-1.
- Tumoricidal activity, tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), and nitric oxide (NO) production were assessed.
Main Results:
- All tested staphylococcal toxins stimulated tumoricidal activity in LPS-responsive macrophages.
- None of the toxins induced cytotoxicity in LPS-unresponsive macrophages.
- SE A, ET A, ET B, and TSST-1 induced TNF-α secretion in LPS-responsive macrophages; SE B induced minimal TNF-α.
- All toxins stimulated IL-6 production in macrophages from both mouse strains.
- NO production was observed only in LPS-responsive macrophages treated with ET A or ET B.
Conclusions:
- Macrophage responses to staphylococcal exotoxins are dependent on the LPS-responsiveness of the mouse strain.
- Specific toxins differentially induce macrophage effector functions, including cytotoxicity and cytokine/NO production.