Mechanisms of dendritic cell lysosomal killing of Cryptococcus.
Cryptococcus neoformans is an opportunistic pulmonary fungal pathogen that disseminates to the CNS causing fatal meningitis in immunocompromised patients. Dendritic cells (DCs) phagocytose C. neoformans following inhalation. Following uptake, cryptococci translocate to the DC lysosomal compartment and are killed by oxidative and non-oxidative mechanisms. DC lysosomal extracts kill cryptococci in vitro; however, the means of antifungal activity remain unknown. Our studies determined non-oxidative antifungal activity by DC lysosomal extract. We examined DC lysosomal killing of cryptococcal strains, anti-fungal activity of purified lysosomal enzymes, and mechanisms of killing against C. neoformans. Results confirmed DC lysosome fungicidal activity against all cryptococcal serotypes. Purified lysosomal enzymes, specifically cathepsin B, inhibited cryptococcal growth. Interestingly, cathepsin B combined with its enzymatic inhibitors led to enhanced cryptococcal killing. Electron microscopy revealed structural changes and ruptured cryptococcal cell walls following treatment. Finally, additional studies demonstrated that osmotic lysis was responsible for cryptococcal death.
Department of Biology and The South Texas Center for Emerging Infectious Diseases, The University of Texas at San Antonio, San Antonio, TX, USA.
Camaron R
CR
Hole
Hoang
H
Bui
Floyd L
FL
Wormley
Karen L
KL
Wozniak
D000818:Animals; D000935:Antifungal Agents / Q000494:pharmacology; D001854:Bone Marrow Cells / Q000166:cytology / Q000187:drug effects; D002401:Cathepsin B / Q000037:antagonists & inhibitors / Q000378:metabolism; D002457:Cell Extracts; D002473:Cell Wall / Q000187:drug effects / Q000648:ultrastructure; D003455:Cryptococcus neoformans / Q000187:drug effects / Q000254:growth & development / Q000276:immunology* / Q000648:ultrastructure; D003713:Dendritic Cells / Q000187:drug effects / Q000201:enzymology / Q000276:immunology*; D005260:Female; D006801:Humans; D008247:Lysosomes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D009995:Osmosis / Q000187:drug effects; D011480:Protease Inhibitors / Q000494:pharmacology; D015203:Reproducibility of Results
D000935:Antifungal Agents; D002457:Cell Extracts; D011480:Protease Inhibitors; D002401:Cathepsin B