Altered gene expression in Staphylococcus aureus upon interaction with human endothelial cells.

Area of Science:

• Microbiology
• Cell Biology
• Infectious Diseases

Background:

• Staphylococcus aureus is a common cause of infective endocarditis, even in patients without prior heart conditions.
• The mechanism of infection initiation may involve direct binding of S. aureus to human vascular endothelium.

Purpose of the Study:

• To investigate the interaction between Staphylococcus aureus and human vascular endothelium.
• To understand the mutual responses of endothelial cells and bacteria during infection.

Main Methods:

• Scanning electron microscopy was used to visualize the binding and internalization of S. aureus by human umbilical vein endothelial cells (HUVEC).
• Bacterial growth phases were analyzed for their impact on endothelial cell interaction.
• An S. aureus expression library was employed to identify genes induced by HUVEC exposure.

Main Results:

• S. aureus binding to HUVEC occurred via cell surface protrusions, with bacteria being internalized through invaginations.
• Logarithmically growing S. aureus exhibited significantly higher binding and internalization rates compared to stationary-phase bacteria.
• Exposure to HUVEC induced the expression of various S. aureus genes involved in transport, catabolism, biosynthesis, and DNA repair.
• Both HUVEC and human serum were identified as triggers for S. aureus gene expression.

Conclusions:

• The interaction between S. aureus and human endothelium is dynamic, involving bacterial binding and internalization.
• Bacterial growth phase critically influences the interaction with endothelial cells.
• Staphylococcus aureus actively responds to the host environment, including endothelial cells and serum, by modulating gene expression.