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Entamoeba histolytica proteins modulate the respiratory burst potential by murine macrophages
1Institute of Parasitology, McGill University, Ste Anne-de-Bellevue, Canada.
Abstract:
Reactive oxygen intermediates are important components of macrophage microbicidal mechanisms and pathogenesis of parasitic disease. The purpose of the present study was to investigate the effect of virulent Entamoeba histolytica (strain HM1-IMSS) on respiratory burst potential of macrophages. Pretreatment of elicited peritoneal macrophages (EPM) with crude soluble amoebic proteins from 1 to 6 hr was found to prime EPM for enhanced O2 and H2O2 release in response to phorbol myristate acetate (PMA) in a dose-dependent manner, whereas pretreatment with the same concentrations of the non-pathogenic E. histolytica-like Laredo strain was without priming effect. Low molecular weight (MW) amoebic proteins (27,000-67,000) purified by Sephacryl-200 column chromatography and subfractionated by diethylaminoethyl cellulose chromatography were 10-fold more potent than crude amoebic proteins in priming EPM for an enhanced respiratory burst potential. Both crude and purified amoebic proteins inhibited the priming effect of lipopolysaccharide (LPS) or interferon-gamma (IFN-gamma) and antagonized the stimulating effect of PMA. Amoebic proteins by themselves were incapable of stimulating EPM respiratory burst. These findings demonstrate that amoebic proteins are capable of modulating the respiratory burst response of macrophages, suggesting an important role for them in the immunoregulation and pathogenesis of amoebiasis.
Insights
Virulent Entamoeba histolytica proteins prime macrophages for enhanced respiratory burst. These amoebic proteins modulate immune responses and play a role in parasitic disease pathogenesis.
Area of Science:
- Immunology
- Parasitology
- Cell Biology
Background:
- Reactive oxygen intermediates are crucial for macrophage microbicidal activity and parasitic disease development.
- Understanding how pathogens interact with host immune cells is key to controlling infectious diseases.
Purpose of the Study:
- To investigate the impact of virulent Entamoeba histolytica on macrophage respiratory burst potential.
- To identify specific amoebic components responsible for modulating macrophage responses.
Main Methods:
- Elicited peritoneal macrophages (EPM) were pretreated with Entamoeba histolytica proteins.
- Respiratory burst activity (O2 and H2O2 release) was measured in response to phorbol myristate acetate (PMA).
- Protein purification using Sephacryl-200 and diethylaminoethyl cellulose chromatography was performed.
Main Results:
- Pretreatment with virulent E. histolytica proteins primed EPM for enhanced respiratory burst.
- Low molecular weight amoebic proteins (27,000-67,000) were potent inducers of this priming effect.
- Amoebic proteins inhibited priming by lipopolysaccharide (LPS) or interferon-gamma (IFN-gamma) and antagonized PMA stimulation.
Conclusions:
- Entamoeba histolytica proteins modulate macrophage respiratory burst responses.
- These proteins likely play a significant role in the immunoregulation and pathogenesis of amoebiasis.
- Further research into these proteins could reveal novel therapeutic targets.