A plasmid-encoded surface protein on Enterococcus faecalis augments its internalization by cultured intestinal...

Area of Science:

• Microbiology
• Cell Biology
• Infectious Diseases

Background:

• Enterococcus faecalis is a common bacterium with implications in healthcare-associated infections.
• Aggregation substance (AS) is a surface protein of E. faecalis known to mediate bacterial conjugation and biofilm formation.
• The role of AS in host cell interaction, specifically epithelial cell internalization, remains less understood.

Purpose of the Study:

• To investigate the function of aggregation substance in the internalization of Enterococcus faecalis by intestinal epithelial cells.
• To determine if AS influences the adherence and entry mechanisms of E. faecalis into HT-29 cells.

Main Methods:

• Utilized cultured human intestinal epithelial cells (HT-29) to model host-pathogen interactions.
• Quantified the internalization of E. faecalis strains with and without functional aggregation substance.
• Employed electron microscopy to visualize the interaction between E. faecalis and enterocytes at the cellular level.

Main Results:

• Aggregation substance significantly increased the endocytosis of E. faecalis by HT-29 cells compared to control strains.
• Internalization levels were comparable to Salmonella typhimurium and some Listeria monocytogenes strains.
• Electron microscopy confirmed AS presence on the bacterial surface interacting with enterocytes and intracellular bacteria within vacuoles.

Conclusions:

• Aggregation substance facilitates the internalization of Enterococcus faecalis by intestinal epithelial cells.
• This mechanism may contribute to the pathogenesis and persistence of E. faecalis in the host.
• Targeting aggregation substance could be a potential strategy to control E. faecalis infections.