Identification of Disease-Associated Cryptococcal Proteins Reactive With Serum IgG From Cryptococcal Meningitis Patients
Cryptococcus neoformans, an opportunistic fungal pathogen ubiquitously present in the environment, causes cryptococcal meningitis (CM) mainly in immunocompromised patients, such as AIDS patients. We aimed to identify disease-associated cryptococcal protein antigens targeted by the human humoral immu...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2021-07-01
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| Series: | Frontiers in Immunology |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fimmu.2021.709695/full |
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| author | A. Elisabeth Gressler Daniela Volke Carolina Firacative Christiane L. Schnabel Uwe Müller Andor Krizsan Bianca Schulze-Richter Matthias Brock Frank Brombacher Patricia Escandón Ralf Hoffmann Gottfried Alber |
| author_facet | A. Elisabeth Gressler Daniela Volke Carolina Firacative Christiane L. Schnabel Uwe Müller Andor Krizsan Bianca Schulze-Richter Matthias Brock Frank Brombacher Patricia Escandón Ralf Hoffmann Gottfried Alber |
| author_sort | A. Elisabeth Gressler |
| collection | DOAJ |
| description | Cryptococcus neoformans, an opportunistic fungal pathogen ubiquitously present in the environment, causes cryptococcal meningitis (CM) mainly in immunocompromised patients, such as AIDS patients. We aimed to identify disease-associated cryptococcal protein antigens targeted by the human humoral immune response. Therefore, we used sera from Colombian CM patients, with or without HIV infection, and from healthy individuals living in the same region. Serological analysis revealed increased titers of anti-cryptococcal IgG in HIV-negative CM patients, but not HIV-positive CM patients, compared to healthy controls. In contrast, titers of anti-cryptococcal IgM were not affected by CM. Furthermore, we detected pre-existing IgG and IgM antibodies even in sera from healthy individuals. The observed induction of anti-cryptococcal IgG but not IgM during CM was supported by analysis of sera from C. neoformans-infected mice. Stronger increase in IgG was found in wild type mice with high lung fungal burden compared to IL-4Rα-deficient mice showing low lung fungal burden. To identify the proteins targeted by human anti-cryptococcal IgG antibodies, we applied a quantitative 2D immunoproteome approach identifying cryptococcal protein spots preferentially recognized by sera from CM patients or healthy individuals followed by mass spectrometry analysis. Twenty-three cryptococcal proteins were recombinantly expressed and confirmed to be immunoreactive with human sera. Fourteen of them were newly described as immunoreactive proteins. Twelve proteins were classified as disease-associated antigens, based on significantly stronger immunoreactivity with sera from CM patients compared to healthy individuals. The proteins identified in our screen significantly expand the pool of cryptococcal proteins with potential for (i) development of novel anti-cryptococcal agents based on implications in cryptococcal virulence or survival, or (ii) development of an anti-cryptococcal vaccine, as several candidates lack homology to human proteins and are localized extracellularly. Furthermore, this study defines pre-existing anti-cryptococcal immunoreactivity in healthy individuals at a molecular level, identifying target antigens recognized by sera from healthy control persons. |
| first_indexed | 2024-12-20T00:39:12Z |
| format | Article |
| id | doaj.art-b9174513a04340ebb1991c7a70e743d5 |
| institution | Directory Open Access Journal |
| issn | 1664-3224 |
| language | English |
| last_indexed | 2024-12-20T00:39:12Z |
| publishDate | 2021-07-01 |
| publisher | Frontiers Media S.A. |
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| series | Frontiers in Immunology |
| spelling | doaj.art-b9174513a04340ebb1991c7a70e743d52022-12-21T19:59:40ZengFrontiers Media S.A.Frontiers in Immunology1664-32242021-07-011210.3389/fimmu.2021.709695709695Identification of Disease-Associated Cryptococcal Proteins Reactive With Serum IgG From Cryptococcal Meningitis PatientsA. Elisabeth Gressler0Daniela Volke1Carolina Firacative2Christiane L. Schnabel3Uwe Müller4Andor Krizsan5Bianca Schulze-Richter6Matthias Brock7Frank Brombacher8Patricia Escandón9Ralf Hoffmann10Gottfried Alber11Institute of Immunology, Faculty of Veterinary Medicine, Leipzig University, Leipzig, GermanyInstitute of Bioanalytical Chemistry, Leipzig University, Leipzig, GermanyStudies in Translational Microbiology and Emerging Diseases (MICROS) Research Group, School of Medicine and Health Sciences, Universidad del Rosario, Bogota, ColombiaInstitute of Immunology, Faculty of Veterinary Medicine, Leipzig University, Leipzig, GermanyInstitute of Immunology, Faculty of Veterinary Medicine, Leipzig University, Leipzig, GermanyInstitute of Bioanalytical Chemistry, Leipzig University, Leipzig, GermanyInstitute of Immunology, Faculty of Veterinary Medicine, Leipzig University, Leipzig, GermanyFungal Genetics and Biology Group, School of Life Sciences, University of Nottingham, Nottingham, United KingdomInternational Centre for Genetic Engineering and Biotechnology (ICGEB), Cape Town Component, Cape Town, South AfricaMicrobiology Group, Instituto Nacional de Salud, Bogota, ColombiaInstitute of Bioanalytical Chemistry, Leipzig University, Leipzig, GermanyInstitute of Immunology, Faculty of Veterinary Medicine, Leipzig University, Leipzig, GermanyCryptococcus neoformans, an opportunistic fungal pathogen ubiquitously present in the environment, causes cryptococcal meningitis (CM) mainly in immunocompromised patients, such as AIDS patients. We aimed to identify disease-associated cryptococcal protein antigens targeted by the human humoral immune response. Therefore, we used sera from Colombian CM patients, with or without HIV infection, and from healthy individuals living in the same region. Serological analysis revealed increased titers of anti-cryptococcal IgG in HIV-negative CM patients, but not HIV-positive CM patients, compared to healthy controls. In contrast, titers of anti-cryptococcal IgM were not affected by CM. Furthermore, we detected pre-existing IgG and IgM antibodies even in sera from healthy individuals. The observed induction of anti-cryptococcal IgG but not IgM during CM was supported by analysis of sera from C. neoformans-infected mice. Stronger increase in IgG was found in wild type mice with high lung fungal burden compared to IL-4Rα-deficient mice showing low lung fungal burden. To identify the proteins targeted by human anti-cryptococcal IgG antibodies, we applied a quantitative 2D immunoproteome approach identifying cryptococcal protein spots preferentially recognized by sera from CM patients or healthy individuals followed by mass spectrometry analysis. Twenty-three cryptococcal proteins were recombinantly expressed and confirmed to be immunoreactive with human sera. Fourteen of them were newly described as immunoreactive proteins. Twelve proteins were classified as disease-associated antigens, based on significantly stronger immunoreactivity with sera from CM patients compared to healthy individuals. The proteins identified in our screen significantly expand the pool of cryptococcal proteins with potential for (i) development of novel anti-cryptococcal agents based on implications in cryptococcal virulence or survival, or (ii) development of an anti-cryptococcal vaccine, as several candidates lack homology to human proteins and are localized extracellularly. Furthermore, this study defines pre-existing anti-cryptococcal immunoreactivity in healthy individuals at a molecular level, identifying target antigens recognized by sera from healthy control persons.https://www.frontiersin.org/articles/10.3389/fimmu.2021.709695/fullCryptococcus neoformansimmunoproteomicscryptococcal meningitishumoral immunityhuman samplesfungal infection |
| spellingShingle | A. Elisabeth Gressler Daniela Volke Carolina Firacative Christiane L. Schnabel Uwe Müller Andor Krizsan Bianca Schulze-Richter Matthias Brock Frank Brombacher Patricia Escandón Ralf Hoffmann Gottfried Alber Identification of Disease-Associated Cryptococcal Proteins Reactive With Serum IgG From Cryptococcal Meningitis Patients Frontiers in Immunology Cryptococcus neoformans immunoproteomics cryptococcal meningitis humoral immunity human samples fungal infection |
| title | Identification of Disease-Associated Cryptococcal Proteins Reactive With Serum IgG From Cryptococcal Meningitis Patients |
| title_full | Identification of Disease-Associated Cryptococcal Proteins Reactive With Serum IgG From Cryptococcal Meningitis Patients |
| title_fullStr | Identification of Disease-Associated Cryptococcal Proteins Reactive With Serum IgG From Cryptococcal Meningitis Patients |
| title_full_unstemmed | Identification of Disease-Associated Cryptococcal Proteins Reactive With Serum IgG From Cryptococcal Meningitis Patients |
| title_short | Identification of Disease-Associated Cryptococcal Proteins Reactive With Serum IgG From Cryptococcal Meningitis Patients |
| title_sort | identification of disease associated cryptococcal proteins reactive with serum igg from cryptococcal meningitis patients |
| topic | Cryptococcus neoformans immunoproteomics cryptococcal meningitis humoral immunity human samples fungal infection |
| url | https://www.frontiersin.org/articles/10.3389/fimmu.2021.709695/full |
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