Cryptococcus is a fatal fungal pathogen that causes cryptococcosis and is a leading cause of death in immunocompromised individuals, particularly AIDS patients. Cryptococcus is an opportunistic and facultative intracellular human pathogen, which is not only resistant to phagocytosis, but is able to survive and proliferate within the mature phagolysosome following uptake. From there, Cryptococcus can either lyse the host cell or move between macrophages via a non-lytic process called vomocytosis. Interestingly, although much is known about the opsonisation and uptake of Cryptococcus via opsonic receptors (e.g. complement or Fc receptors), little is known about the involvement of non-opsonic receptors in cryptococcosis. Here we use a combination of inhibitors, bone marrow macrophages from knockout mice and ectopically overexpressed non-opsonic receptors to dissect the role of non-opsonic receptors in driving phagocytosis of this important pathogen. We show that, despite the presence of a thick mannan-based capsule, non-opsonic uptake of Cryptococcus is dependent on the dectin family of receptors but not the mannose receptor. Together, this suggests that phagocytosis of cryptococci in vivo is likely to depend on a complex interplay between different signalling pathways, which likely has significant implications for the intracellular behaviour of this pathogen.
Full conference title:
Society for General Microbiology Autumn Conference 2013
- SGM 2013