Lysosome Fusion Maintains Phagosome Integrity during Fungal Infection

Area of Science:

• Cell biology
• Immunology
• Mycology

Background:

• Phagosomes are crucial for microbial killing but can rupture if pathogens grow inside.
• Maintaining phagosome integrity is essential for host defense against intracellular pathogens like Candida albicans.

Purpose of the Study:

• To investigate how phagosomes regulate size to maintain integrity during Candida albicans infection.
• To elucidate the mechanism of phagosome expansion and its role in preventing pathogen escape and host cell death.

Main Methods:

• Studied calcium release and lysosome recruitment dynamics in phagosomes infected with C. albicans.
• Utilized whole-genome transcriptomic analysis to assess pathogen stress responses.
• Investigated the role of TFEB (transcription factor EB) in lysosome biogenesis.

Main Results:

• Phagosomes release calcium upon C. albicans hyphal elongation, triggering lysosome insertion and surface area expansion.
• Lysosome biosynthesis is stimulated via TFEB activation to replenish consumed lysosomes.
• Inhibition of lysosomal insertion leads to phagosome rupture, inflammasome activation, and host cell death.

Conclusions:

• Phagosomes actively regulate their size through calcium-mediated lysosome recruitment and insertion to accommodate growing Candida albicans.
• This expansion mechanism is vital for maintaining phagosome integrity, preventing pathogen escape, and averting host cell death.
• The findings reveal a novel host-pathogen interaction centered on phagosome dynamics and immune signaling.