Extracellular vesicles derived from Cryptococcus neoformans promoted neutrophil extracellular traps

Area of Science:

• Mycology
• Immunology
• Cell Biology

Background:

• Cryptococcus neoformans causes fatal meningitis.
• Fungal extracellular vesicles (EVs) mediate pathogen-host interactions.
• Encapsulated C. neoformans strains pose a significant threat.

Purpose of the Study:

• Investigate the role of C. neoformans EVs in host immune response.
• Determine the mechanism by which EVs facilitate fungal invasion.
• Elucidate the impact of EVs and NETs on the blood-brain barrier.

Main Methods:

• Treatment of brain endothelial cells with C. neoformans EVs.
• Analysis of CD44 and occludin expression.
• Induction and characterization of neutrophil extracellular traps (NETs).
• Assessment of tight junction integrity and signaling pathways (STAT3, NF-κB, MAPK).
• In vitro blood-brain barrier model.

Main Results:

• Encapsulated C. neoformans EVs increased CD44 and decreased occludin expression.
• H99 EVs induced NET formation via PAD4, p65, and NADPH.
• NETs disrupted brain endothelial tight junctions, reducing claudin-5 and occludin.
• EVs and NETs promoted C. neoformans adhesion and penetration of brain endothelial cells.
• Activation of STAT3, NF-κB, and MyD88-MAPK pathways was observed.

Conclusions:

• C. neoformans EVs, particularly from encapsulated strains, induce NET formation.
• Induced NETs disrupt brain endothelial tight junctions, compromising the blood-brain barrier.
• This process facilitates C. neoformans invasion and meningitis pathogenesis.