Trogocytosis-associated cell to cell spread of intracellular bacterial pathogens

Area of Science:

• Immunology
• Microbiology
• Cell Biology

Background:

• Macrophages are crucial immune cells that phagocytose pathogens but can be exploited by intracellular bacteria.
• Some bacteria resist macrophage antimicrobial activity and replicate intracellularly.
• Macrophages have surveillance roles involving the acquisition of cytosolic components from other cells.

Purpose of the Study:

• To investigate if intracellular bacteria utilize host cell cytosolic transfer mechanisms for dissemination.
• To determine if pathogens replicating within macrophages can spread to uninfected cells via cell-to-cell transfer.

Main Methods:

• Co-culture experiments with macrophages infected by Francisella tularensis and Salmonella enterica.
• Microscopy and cell viability assays to observe and confirm intercellular transfer.
• Analysis of trogocytosis-related processes involving plasma membrane and cytosol exchange.

Main Results:

• Viable Francisella tularensis and Salmonella enterica were transferred from infected to uninfected macrophages.
• Bacterial transfer occurred via a transient, contact-dependent mechanism involving plasma membrane and cytosol exchange (trogocytosis).
• Both donor and recipient cells remained intact and viable post-transfer.
• Trogocytosis was observed in infected mice, indicating in vivo relevance.

Conclusions:

• Intracellular bacteria can exploit host cell trogocytosis to spread between macrophages.
• This cell-to-cell transfer mechanism facilitates bacterial dissemination, even within a living organism.
• Trogocytosis represents a novel pathway for intracellular pathogen spread.