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Macrophage Cholesterol Depletion and Its Effect on the Phagocytosis of Cryptococcus neoformans
Published on: December 19, 2014
Phospholipids trigger Cryptococcus neoformans capsular enlargement during interactions with amoebae and macrophages
Cara J Chrisman1, Patricia Albuquerque, Allan J Guimaraes
1Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, United States of America.
Plos Pathogens
|June 4, 2011
Summary
Phospholipids, found in amoebae and mammals, trigger Cryptococcus neoformans capsule enlargement. This defense mechanism, involving fungal phospholipase B, leads to giant cell formation and sheds light on cryptococcal virulence.
Area of Science:
- Mycology
- Microbiology
- Host-Pathogen Interactions
Background:
- Cryptococcus neoformans exhibits capsule enlargement when interacting with mammalian hosts.
- Similarities exist between C. neoformans interactions with macrophages and amoebae.
- The role of environmental factors in cryptococcal virulence is under investigation.
Purpose of the Study:
- To investigate if protozoa, specifically Acanthamoeba castellanii, can induce capsule enlargement in C. neoformans.
- To identify the specific molecules responsible for triggering this phenomenon.
- To explore the implications for understanding cryptococcal virulence and host-pathogen interactions.
Main Methods:
- Incubation of C. neoformans with Acanthamoeba castellanii and its extracts.
- Testing extracts from macrophages and mammalian serum for their effect on C. neoformans capsule size.
- Assessing the role of fungal phospholipases (B and C) in the capsule enlargement response.
- Using purified phospholipids, including phosphatidylcholine, to induce capsule enlargement and giant cell formation.
Main Results:
- Incubation with Acanthamoeba castellanii caused C. neoformans capsule enlargement, requiring cell contact but not amoeba viability.
- Protozoan polar lipids were identified as key stimuli for capsule enlargement.
- Mammalian extracts and phospholipids, particularly phosphatidylcholine, also triggered significant capsule enlargement and giant cell formation.
- Fungal phospholipase B activity was essential for the observed capsule enlargement.
Conclusions:
- Phospholipids are identified as the primary host-derived molecules that trigger C. neoformans capsule enlargement.
- Capsule enlargement, induced by phospholipids, serves as a defense mechanism against predatory cells.
- The findings suggest that interactions with environmental microorganisms like protists contribute to cryptococcal virulence.
- This study provides a method for in vitro generation of giant C. neoformans cells.
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