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Activation of macrophages by Entamoeba histolytica extracts in mice
1Montreal General Hospital Research Institute, Quebec, Canada.
Abstract:
The effect of Entamoeba histolytica extracts on the production of inflammatory macrophages and the release of hydrogen peroxide (H2O2) and superoxide (O2-) from these cells was examined in C57BL/6 mice. Two different strains of E. histolytica, either virulent (IP:0682:1) or nonvirulent (DKB), were used in this study. The number of macrophages recovered from the peritoneal cavity of mice treated 5 days previously with 150 micrograms of either strain of amoebic extracts was significantly higher than in the saline-treated groups. Macrophages from mice treated with 150 micrograms of the IP:0682:1 strain of amoebic extracts exhibited a powerful burst of oxidative metabolis when triggered with phorbol myristate acetate (PMA). Extract from the non-virulent strain was much less effective in activating macrophages for the production of oxidative metabolites. Thus, a crude extract preparation from E. histolytica, particularly the virulent strain, induces a strong macrophage inflammatory response in which the cells also produce high levels of H2O2 and O2-.
Insights
Entamoeba histolytica extracts, especially from virulent strains, significantly increase inflammatory macrophages. These activated macrophages release high levels of hydrogen peroxide (H2O2) and superoxide (O2-).
Area of Science:
- Immunology
- Parasitology
Background:
- Entamoeba histolytica is a protozoan parasite that causes amoebiasis.
- Macrophage activation is crucial in the host immune response to parasitic infections.
Purpose of the Study:
- To investigate the impact of Entamoeba histolytica extracts on macrophage activation and oxidative burst.
- To compare the effects of virulent and non-virulent E. histolytica strains.
Main Methods:
- C57BL/6 mice were treated with extracts from virulent (IP:0682:1) or non-virulent (DKB) E. histolytica strains.
- Macrophage counts in the peritoneal cavity were determined.
- Oxidative burst (H2O2 and O2- production) was measured in macrophages stimulated with phorbol myristate acetate (PMA).
Main Results:
- Treatment with E. histolytica extracts significantly increased macrophage numbers compared to saline controls.
- Macrophages from mice treated with the virulent strain extract showed a potent oxidative burst upon PMA stimulation.
- Extracts from the non-virulent strain were less effective in stimulating oxidative metabolite production.
Conclusions:
- Crude extracts of Entamoeba histolytica, particularly from virulent strains, induce a robust macrophage inflammatory response.
- This response is characterized by elevated production of reactive oxygen species like hydrogen peroxide and superoxide.