Hemophagocytic macrophages harbor Salmonella enterica during persistent infection

Area of Science:

• Immunology
• Microbiology
• Pathogen Survival

Background:

• Salmonella enterica subspecies cause persistent systemic infections in mammals, including human typhoid fever.
• These bacteria typically reside within macrophages during both acute and chronic infection stages.
• The mechanism by which Salmonella survives within macrophages remains largely unknown.

Purpose of the Study:

• To investigate the role of hemophagocytic macrophages in Salmonella Typhimurium persistence.
• To evaluate bacterial survival within macrophages that have ingested viable host cells.

Main Methods:

• Development of cell culture assays to assess bacterial survival.
• Co-culture of Salmonella Typhimurium with macrophages pre-phagocytosing viable cells, dead cells, or beads.

Main Results:

• Salmonella Typhimurium preferentially replicated in macrophages that had ingested viable cells.
• Bacterial survival was significantly reduced in macrophages that ingested beads or dead cells.
• Hemophagocytic macrophages were observed during the establishment of persistent murine infection.

Conclusions:

• Hemophagocytic macrophages may provide a survival niche for Salmonella Typhimurium during persistent infections.
• The interaction between Salmonella and hemophagocytic macrophages is crucial for establishing chronic disease.
• Understanding this interaction could lead to new therapeutic strategies against persistent Salmonella infections.