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Chemokine production by rat macrophages stimulated with streptolysin O from Streptococcus pyogenes
Ken-Ichiro Mitsui1, Katsuhiko Takano, Sumie Nakatani
1Department of Physiological Chemistry, Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, Toyama, Japan.
Abstract:
The contribution of streptolysin O (SLO) from Streptococcus pyogenes to neutrophil infiltration in inflammatory lesions was determined by production of cytokine-induced neutrophil chemoattractant (CINC)-1, -2 and -3, and macrophage inflammatory protein (MIP)-1alpha by rat macrophages stimulated with SLO in culture. Active SLO induced the production of CINCs and MIP-1alpha in dose- and time-dependent manners. These inductions were ascertained by chemokine mRNA expression in macrophages. Streptolysin S was without effect. The SLO-cholesterol complex induced the chemokine production in proportion to the residual hemolytic activity of the complex. In addition, the effects of SLO on the chemokine production were confirmed by the injection of active SLO into the preformed air pouch on the back of rats. The infiltration of neutrophils into the pouch fluid (exudate) increased steadily with a lag phase of about 2 hr. The major chemokine found in exudates was MIP-1alpha but not CINCs. In this study, it became clear that active SLO, but not the inactive one, contributed to the production of MIP-1alpha and CINCs in the conditioned medium and in exudates.
Insights
Streptolysin O (SLO) from Streptococcus pyogenes triggers the release of chemokines, attracting neutrophils to inflammatory sites. This study confirms SLO
Area of Science:
- Immunology
- Microbiology
- Molecular Biology
Background:
- Streptococcus pyogenes produces streptolysin O (SLO), a toxin implicated in inflammatory processes.
- Neutrophil infiltration is a key feature of inflammatory lesions.
Purpose of the Study:
- To investigate the role of SLO in inducing neutrophil chemoattractants.
- To elucidate the mechanism by which SLO contributes to neutrophil recruitment.
Main Methods:
- Rat macrophages were stimulated with SLO in vitro to measure chemokine production (CINCs, MIP-1alpha).
- Chemokine mRNA expression was analyzed to confirm induction.
- Active SLO was injected into rat air pouches to assess in vivo neutrophil infiltration and chemokine levels.
Main Results:
- Active SLO dose- and time-dependently induced the production of CINCs and MIP-1alpha by macrophages.
- SLO-cholesterol complex induced chemokines proportionally to its hemolytic activity.
- In vivo, SLO injection led to increased neutrophil infiltration in air pouch exudates, with MIP-1alpha being the major chemokine detected.
Conclusions:
- Active SLO, but not streptolysin S, significantly contributes to the production of MIP-1alpha and CINCs.
- SLO plays a direct role in neutrophil recruitment to inflammatory sites through chemokine induction.