Phospholipase B Is Critical for Cryptococcus neoformans Survival in the Central Nervous System
ABSTRACT Cryptococcus neoformans (Cn) is an opportunistic, encapsulated, yeast-like fungus that causes severe meningoencephalitis, especially in countries with high HIV prevalence. In addition to its well-known polysaccharide capsule, Cn has other virulence factors such as phospholipases, a heteroge...
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| Format: | Article |
| Language: | English |
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American Society for Microbiology
2023-04-01
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| Series: | mBio |
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| Online Access: | https://journals.asm.org/doi/10.1128/mbio.02640-22 |
| _version_ | 1797839621298585600 |
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| author | Mohamed F. Hamed Glauber Ribeiro de Sousa Araújo Melissa E. Munzen Marta Reguera-Gomez Carly Epstein Hiu Ham Lee Susana Frases Luis R. Martinez |
| author_facet | Mohamed F. Hamed Glauber Ribeiro de Sousa Araújo Melissa E. Munzen Marta Reguera-Gomez Carly Epstein Hiu Ham Lee Susana Frases Luis R. Martinez |
| author_sort | Mohamed F. Hamed |
| collection | DOAJ |
| description | ABSTRACT Cryptococcus neoformans (Cn) is an opportunistic, encapsulated, yeast-like fungus that causes severe meningoencephalitis, especially in countries with high HIV prevalence. In addition to its well-known polysaccharide capsule, Cn has other virulence factors such as phospholipases, a heterogeneous group of enzymes that hydrolyze ester linkages in glycerophospholipids. Phospholipase B (PLB1) has been demonstrated to play a key role in Cn pathogenicity. In this study, we used a PLB1 mutant (plb1) and its reconstituted strain (Rec1) to assess the importance of this enzyme on Cn brain infection in vivo and in vitro. Mice infected with the plb1 strain survive significantly longer, have lower peripheral and central nervous system (CNS) fungal loads, and have fewer and smaller cryptococcomas or biofilm-like brain lesions compared to H99- and Rec1-infected animals. PLB1 causes extensive brain tissue damage and changes microglia morphology during cryptococcal disease, observations which can have important implications in patients with altered mental status or dementia as these manifestations are related to poorer survival outcomes. plb1 cryptococci are significantly more phagocytosed and killed by NR-9460 microglia-like cells. plb1 cells have altered capsular polysaccharide biophysical properties which impair their ability to stimulate glial cell responses or morphological changes. Here, we provide significant evidence demonstrating that Cn PLB1 is an important virulence factor for fungal colonization of and survival in the CNS as well as in the progression of cryptococcal meningoencephalitis. These findings may potentially help fill in a gap of knowledge in our understanding of cerebral cryptococcosis and provide novel research avenues in Cn pathogenesis. IMPORTANCE Cryptococcal meningoencephalitis (CME) is a serious disease caused by infection by the neurotropic fungal pathogen Cryptococcus neoformans. Due to the increasing number of cases in HIV-infected individuals, as well as the limited therapies available, investigation into potential targets for new therapeutics has become critical. Phospholipase B is an enzyme synthesized by Cn that confers virulence to the fungus through capsular enlargement, immunomodulation, and intracellular replication. In this study, we examined the properties of PLB1 by comparing infection of a Cn PLB1 mutant strain with both the wild-type and a PLB1-reconstituted strain. We show that PLB1 augments the survival and proliferation of the fungus in the CNS and strengthens virulence by modulating the immune response and enhancing specific biophysical properties of the fungus. PLB1 expression causes brain tissue damage and impacts glial cell functions, which may be responsible for the dementia observed in patients which may persist even after resolving from CME. The implications of PLB1 inhibition reveal its involvement in Cn infection and suggest that it may be a possible molecular target in the development of antifungal therapies. The results of this study support additional investigation into the mechanism of PLB1 to further understand the intricacies of cerebral Cn infection. |
| first_indexed | 2024-04-09T15:59:47Z |
| format | Article |
| id | doaj.art-9f54be21a89846a0ab268e0252bceb7a |
| institution | Directory Open Access Journal |
| issn | 2150-7511 |
| language | English |
| last_indexed | 2024-04-09T15:59:47Z |
| publishDate | 2023-04-01 |
| publisher | American Society for Microbiology |
| record_format | Article |
| series | mBio |
| spelling | doaj.art-9f54be21a89846a0ab268e0252bceb7a2023-04-25T13:04:57ZengAmerican Society for MicrobiologymBio2150-75112023-04-0114210.1128/mbio.02640-22Phospholipase B Is Critical for Cryptococcus neoformans Survival in the Central Nervous SystemMohamed F. Hamed0Glauber Ribeiro de Sousa Araújo1Melissa E. Munzen2Marta Reguera-Gomez3Carly Epstein4Hiu Ham Lee5Susana Frases6Luis R. Martinez7Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, USALaboratório de Biofísica de Fungos, Instituto de Biofísica Carlos Chagas Filhos, Universidade Federal do Rio de Janeiro, Rio de Janeiro, BrazilDepartment of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, USADepartment of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, USADepartment of Biomedical Sciences, NYIT College of Osteopathic Medicine, Old Westbury, New York, USADepartment of Biomedical Sciences, NYIT College of Osteopathic Medicine, Old Westbury, New York, USALaboratório de Biofísica de Fungos, Instituto de Biofísica Carlos Chagas Filhos, Universidade Federal do Rio de Janeiro, Rio de Janeiro, BrazilDepartment of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, USAABSTRACT Cryptococcus neoformans (Cn) is an opportunistic, encapsulated, yeast-like fungus that causes severe meningoencephalitis, especially in countries with high HIV prevalence. In addition to its well-known polysaccharide capsule, Cn has other virulence factors such as phospholipases, a heterogeneous group of enzymes that hydrolyze ester linkages in glycerophospholipids. Phospholipase B (PLB1) has been demonstrated to play a key role in Cn pathogenicity. In this study, we used a PLB1 mutant (plb1) and its reconstituted strain (Rec1) to assess the importance of this enzyme on Cn brain infection in vivo and in vitro. Mice infected with the plb1 strain survive significantly longer, have lower peripheral and central nervous system (CNS) fungal loads, and have fewer and smaller cryptococcomas or biofilm-like brain lesions compared to H99- and Rec1-infected animals. PLB1 causes extensive brain tissue damage and changes microglia morphology during cryptococcal disease, observations which can have important implications in patients with altered mental status or dementia as these manifestations are related to poorer survival outcomes. plb1 cryptococci are significantly more phagocytosed and killed by NR-9460 microglia-like cells. plb1 cells have altered capsular polysaccharide biophysical properties which impair their ability to stimulate glial cell responses or morphological changes. Here, we provide significant evidence demonstrating that Cn PLB1 is an important virulence factor for fungal colonization of and survival in the CNS as well as in the progression of cryptococcal meningoencephalitis. These findings may potentially help fill in a gap of knowledge in our understanding of cerebral cryptococcosis and provide novel research avenues in Cn pathogenesis. IMPORTANCE Cryptococcal meningoencephalitis (CME) is a serious disease caused by infection by the neurotropic fungal pathogen Cryptococcus neoformans. Due to the increasing number of cases in HIV-infected individuals, as well as the limited therapies available, investigation into potential targets for new therapeutics has become critical. Phospholipase B is an enzyme synthesized by Cn that confers virulence to the fungus through capsular enlargement, immunomodulation, and intracellular replication. In this study, we examined the properties of PLB1 by comparing infection of a Cn PLB1 mutant strain with both the wild-type and a PLB1-reconstituted strain. We show that PLB1 augments the survival and proliferation of the fungus in the CNS and strengthens virulence by modulating the immune response and enhancing specific biophysical properties of the fungus. PLB1 expression causes brain tissue damage and impacts glial cell functions, which may be responsible for the dementia observed in patients which may persist even after resolving from CME. The implications of PLB1 inhibition reveal its involvement in Cn infection and suggest that it may be a possible molecular target in the development of antifungal therapies. The results of this study support additional investigation into the mechanism of PLB1 to further understand the intricacies of cerebral Cn infection.https://journals.asm.org/doi/10.1128/mbio.02640-22cerebral cryptococcosisCryptococcus neoformansgliaGXMnitric oxidephospholipase |
| spellingShingle | Mohamed F. Hamed Glauber Ribeiro de Sousa Araújo Melissa E. Munzen Marta Reguera-Gomez Carly Epstein Hiu Ham Lee Susana Frases Luis R. Martinez Phospholipase B Is Critical for Cryptococcus neoformans Survival in the Central Nervous System mBio cerebral cryptococcosis Cryptococcus neoformans glia GXM nitric oxide phospholipase |
| title | Phospholipase B Is Critical for Cryptococcus neoformans Survival in the Central Nervous System |
| title_full | Phospholipase B Is Critical for Cryptococcus neoformans Survival in the Central Nervous System |
| title_fullStr | Phospholipase B Is Critical for Cryptococcus neoformans Survival in the Central Nervous System |
| title_full_unstemmed | Phospholipase B Is Critical for Cryptococcus neoformans Survival in the Central Nervous System |
| title_short | Phospholipase B Is Critical for Cryptococcus neoformans Survival in the Central Nervous System |
| title_sort | phospholipase b is critical for cryptococcus neoformans survival in the central nervous system |
| topic | cerebral cryptococcosis Cryptococcus neoformans glia GXM nitric oxide phospholipase |
| url | https://journals.asm.org/doi/10.1128/mbio.02640-22 |
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