Interactions between Entamoeba histolytica, bacteria and intestinal cells

Area of Science:

• Microbiology
• Parasitology
• Infectious Diseases

Background:

• Entamoeba histolytica (E. histolytica) is an enteric protozoan parasite that causes amoebiasis.
• Pathogenic and non-pathogenic E. histolytica isolates possess surface carbohydrate-binding proteins (lectins) mediating adherence to host cells and bacteria.
• The role of bacterial interactions in modulating E. histolytica virulence remains incompletely understood.

Purpose of the Study:

• To investigate how interactions with specific bacteria influence the virulence of E. histolytica trophozoites.
• To elucidate the mechanisms underlying bacterial-induced enhancement of E. histolytica pathogenicity.

Main Methods:

• Axenically grown E. histolytica isolates were co-cultured with various Gram-negative bacteria, primarily Escherichia coli.
• Assays included assessment of epithelial cell destruction and ingestion, cytopathic substance secretion, and hepatic abscess formation in hamsters.
• Inhibition studies involved using specific carbohydrates, heat-inactivated or fixed bacteria, and bacterial treatments with protein or cell-wall synthesis inhibitors.

Main Results:

• Co-incubation with viable Gram-negative bacteria significantly increased E. histolytica trophozoite virulence.
• Enhanced virulence manifested as increased epithelial cell damage, cytopathic effects on cultured cells, and hepatic abscess induction.
• The enhancement was dependent on lectin-mediated bacterial attachment and required viable bacteria with active protein synthesis.

Conclusions:

• Interactions with certain bacteria can substantially increase the virulence of Entamoeba histolytica.
• This phenomenon is mediated by bacterial surface components and requires active bacterial processes.
• Understanding these interactions may offer novel strategies for controlling amoebiasis.