Macrophages inhibit Aspergillus fumigatus germination and neutrophil-mediated fungal killing
Fig 10
Model of neutrophil and macrophage responses to Aspergillus fumigatus.
Upon infection, A. fumigatus spores are taken up by macrophages, which form dense clusters around the fungus and inhibit spore germination. Macrophages provide a protective niche for spore survival, as neutrophil-mediated killing of A. fumigatus requires germination. As a result, in infections with slow-germinating A. fumigatus strains, the fungus persists for days, while in infections with fast-germinating A. fumigatus strains, germination drives neutrophil recruitment, neutrophil-mediated killing, and faster fungal clearance. Macrophages have some anti-fungal activity, dependent on Myd88-NF-κB signaling, however NF-κB activation is not sufficient to kill slow-germinating strains.