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Entry of pyelonephritogenic Escherichia coli into HEp-2 cells due to actin polymerization
Abstract:
This study provides evidence that pyelonephritogenic strains of Escherichia coli, which do not produce soluble hemolysin and possess mannose-resistant hemagglutinating activity, are able to adhere and penetrate to HEp-2 cells. Invasion and intracellular survival were analyzed by transmission electron microscopy and by viable counts after killing of extracellular bacteria by gentamicin. Cytochalasin D, which blocks polymerization of G-actin, markedly reduced the entry of E. coli into the cells and inhibited intracellular mobility of the bacteria. By using indirect fluorescent staining with anti-actin rabbit serum, direct evidence was obtained that interaction with the cytoskeleton of HEp-2 cells is necessary for invasion.
Insights
Pyelonephritogenic Escherichia coli strains adhere to and invade HEp-2 cells. Bacterial entry and intracellular survival depend on the host cell
Area of Science:
- Microbiology
- Cell Biology
- Infectious Diseases
Background:
- Pyelonephritogenic strains of Escherichia coli (E. coli) are a significant cause of urinary tract infections.
- Understanding the mechanisms of bacterial invasion into host cells is crucial for developing effective treatments.
Purpose of the Study:
- To investigate the adherence and invasion capabilities of specific E. coli strains into HEp-2 cells.
- To elucidate the role of the host cell cytoskeleton in E. coli invasion.
Main Methods:
- Transmission electron microscopy to visualize bacterial entry and intracellular survival.
- Gentamicin protection assays to quantify intracellular bacteria.
- Cytochalasin D treatment to assess the role of actin polymerization.
- Indirect fluorescent staining with anti-actin antibodies to study cytoskeleton interaction.
Main Results:
- Pyelonephritogenic E. coli strains lacking soluble hemolysin but possessing mannose-resistant hemagglutinating activity adhered to and penetrated HEp-2 cells.
- Cytochalasin D significantly reduced E. coli entry and intracellular mobility, indicating actin's role.
- Direct evidence showed that interaction with the HEp-2 cell cytoskeleton is essential for bacterial invasion.
Conclusions:
- Specific pyelonephritogenic E. coli strains can invade host cells.
- Bacterial invasion is dependent on the host cell's actin cytoskeleton.
- These findings contribute to understanding the pathogenesis of E. coli-associated kidney infections.