The long-term goal of this proposal is to study mechanism(s) of pathogenicity of Cryptococcus neoformans (Cn) focusing on how Cn sphingolipids regulate fungal virulence and counteract the host immune response. Cn is a fungal pathogen that, upon entering the lung and disseminating through the bloodstream, causes a life- threatening meningo-encephalitis in susceptible patients. One key feature of Cn is its ability to grow both extracellularly and intracellularly. Being the lung the port of entry of Cn, alveolar macrophages (AMs) are the first line of defense of the host. Thus, the outcome of the interaction between the fungus and AMs greatly determines the progression of the disease. If the immune system of the host is compromised and AMs fail to kill the engulfed Cn cells, these fungal cells survive and proliferate within the phagolysosome of AMs. This implies that the physiopathology of cryptococcosis is determined by fungal growth that can occur in an intracellular compartment (e.g. acidic environment of AM's phagolysosome) and in an extracellular compartment (e.g. neutral/alkaline environment of alveolar spaces and bloodstream). In the past funding cycle, we identified novel fungal factors in the sphingolipid pathway that specifically regulate growth of Cn in each compartment. Particularly, the inositol phosphosphingolipid phospholipase C (Isc1) enzyme was found to be required for intracellular growth of Cn within AMs, whereas the glucosylceramide synthase (Gcs1) was found to be required for extracellular growth of Cn within the alveolar spaces. Importantly, we identified very long chain C26 phytoceramide and glucosylceramide (GlcCer) as the biochemical products of the reactions catalized by Isc1 and Gcs1, respectively. Thus, we hypothesize that Isc1 and Gcs1 regulate pathogenicity by favoring growth in different compartment(s) through the action of the specific sphingolipids that they produce. This hypothesis will be addressed by the following Aims: 1) To study the mechanism by which fungal sphingolipids regulate growth of Cn in the intracellular compartment;2) To study the mechanism by which fungal sphingolipids regulate growth of Cn in the lung-like extracellular compartment;3) To determine the therapeutic effect of targeting intracellular and/or extracellular populations of Cn on the outcome of the infection.

Public Health Relevance

Cryptococcus neoformans is an environmental microorganism that causes the most common fungal meningo-encephalitis worldwide. The pathogenesis of this fungal pathogen is not well understood. This proposal focuses on a better understanding of the pathogenic process focusing on how fungal sphingolipids regulates virulence, providing new insights into the development of better therapeutic strategies against this life-threatening fungal brain infection

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
7R01AI056168-09
Application #
8514913
Study Section
Special Emphasis Panel (ZRG1-IDM-B (02))
Program Officer
Duncan, Rory A
Project Start
2003-07-01
Project End
2014-08-31
Budget Start
2012-09-01
Budget End
2013-08-31
Support Year
9
Fiscal Year
2012
Total Cost
$307,915
Indirect Cost
$111,895
Name
State University New York Stony Brook
Department
Genetics
Type
Schools of Medicine
DUNS #
804878247
City
Stony Brook
State
NY
Country
United States
Zip Code
11794
Rollin-Pinheiro, Rodrigo; Singh, Ashutosh; Barreto-Bergter, Eliana et al. (2016) Sphingolipids as targets for treatment of fungal infections. Future Med Chem 8:1469-84
Rella, Antonella; Farnoud, Amir M; Del Poeta, Maurizio (2016) Plasma membrane lipids and their role in fungal virulence. Prog Lipid Res 61:63-72
Joffe, Luna S; Nimrichter, Leonardo; Rodrigues, Marcio L et al. (2016) Potential Roles of Fungal Extracellular Vesicles during Infection. mSphere 1:
Nimrichter, Leonardo; de Souza, Marcio M; Del Poeta, Maurizio et al. (2016) Extracellular Vesicle-Associated Transitory Cell Wall Components and Their Impact on the Interaction of Fungi with Host Cells. Front Microbiol 7:1034
Singh, Ashutosh; Del Poeta, Maurizio (2016) Sphingolipidomics: An Important Mechanistic Tool for Studying Fungal Pathogens. Front Microbiol 7:501
Fernandes, C M; de Castro, P A; Singh, A et al. (2016) Functional characterization of the Aspergillus nidulans glucosylceramide pathway reveals that LCB Δ8-desaturation and C9-methylation are relevant to filamentous growth, lipid raft localization and Psd1 defensin activity. Mol Microbiol 102:488-505
Mor, Visesato; Farnoud, Amir M; Singh, Ashutosh et al. (2016) Glucosylceramide Administration as a Vaccination Strategy in Mouse Models of Cryptococcosis. PLoS One 11:e0153853
Medici, Natasha P; Del Poeta, Maurizio (2015) New insights on the development of fungal vaccines: from immunity to recent challenges. Mem Inst Oswaldo Cruz 110:966-73
Farnoud, Amir M; Toledo, Alvaro M; Konopka, James B et al. (2015) Raft-like membrane domains in pathogenic microorganisms. Curr Top Membr 75:233-68
Singh, Arpita; Rella, Antonella; Schwacke, John et al. (2015) Transmembrane transporter expression regulated by the glucosylceramide pathway in Cryptococcus neoformans. BMC Res Notes 8:681

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