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Yoo K, Oliveira NK, Bhattacharya S, Fries BC. Achieving Resilience in Aging: How Mitochondrial Modulation Drives Age-associated Fluconazole Tolerance in Cryptococcus neoformans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.26.586817. [PMID: 38585804 PMCID: PMC10996610 DOI: 10.1101/2024.03.26.586817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Cryptococcus neoformans ( Cn ) is an opportunistic fungal microorganism that causes life-threatening meningoencephalitis. During the infection, the microbial population is heterogeneously composed of cells with varying generational ages, with older cells accumulating during chronic infections. This is attributed to their enhanced resistance to phagocytic killing and tolerance of antifungals like fluconazole (FLC). In this study, we investigated the role of ergosterol synthesis, ATP-binding cassette (ABC) transporters, and mitochondrial metabolism in the regulation of age-dependent FLC tolerance. We find that old Cn cells increase the production of ergosterol and exhibit upregulation of ABC transporters. Old cells also show transcriptional and phenotypic characteristics consistent with increased metabolic activity, leading to increased ATP production. This is accompanied by increased production of reactive oxygen species (ROS), which results in mitochondrial fragmentation. This study demonstrates that the metabolic changes occurring in the mitochondria of old cells drive the increase in ergosterol synthesis and the upregulation of ABC transporters, leading to FLC tolerance. IMPORTANCE Infections caused by Cryptococcus neoformans cause more than 180,000 deaths annually. Estimated one-year mortality for patients receiving care ranges from 20% in developed countries to 70% in developing countries, suggesting that current treatments are inadequate. Some fungal cells can persist and replicate despite the usage of current antifungal regimens, leading to death or treatment failure. In replicative aging, older cells display a resilient phenotype, characterized by their enhanced tolerance against antifungals and resistance to killing by host cells. This study shows that age-dependent increase in mitochondrial reactive oxygen species drive changes in ABC transporters and ergosterol synthesis, ultimately leading to the heightened tolerance against fluconazole in old C. neoformans cells. Understanding the underlying molecular mechanisms of this age-associated antifungal tolerance will enable more targeted antifungal therapies for cryptococcal infections.
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Shen J, Ma M, Duan W, Huang Y, Shi B, Wu Q, Wei X. Autophagy Alters the Susceptibility of Candida albicans Biofilms to Antifungal Agents. Microorganisms 2023; 11:2015. [PMID: 37630575 PMCID: PMC10458732 DOI: 10.3390/microorganisms11082015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 08/01/2023] [Accepted: 08/03/2023] [Indexed: 08/27/2023] Open
Abstract
Candida albicans (C. albicans) reigns as a major cause of clinical candidiasis. C. albicans biofilms are known to increase resistance to antifungal agents, making biofilm-related infections particularly challenging to treat. Drug resistance is of particular concern due to the spread of multidrug-resistant fungal pathogens, while autophagy is crucial for the maintenance of cellular homeostasis. Therefore, this study aimed to investigate the effects of an activator and an inhibitor of autophagy on the susceptibility of C. albicans biofilms to antifungal agents and the related mechanisms. The susceptibility of C. albicans biofilms to different antifungal agents after treatment with or without the autophagy activator or inhibitor was evaluated using XTT assay. Alkaline phosphatase (ALP) activity and reactive oxygen species (ROS) level, as well as the expression of ROS-related and autophagy-related genes, were examined to evaluate the autophagic activity of C. albicans biofilms when treated with antifungal agents. The autophagosomes were observed by transmission electron microscopy (TEM). The susceptibility of C. albicans biofilms to antifungal agents changed when autophagy changed. The ALP activity and ROS level of C. albicans biofilms increased with the treatment of antifungal agents, and autophagosomes could be observed in C. albicans biofilms. Autophagy was involved in the susceptibility of C. albicans biofilms to antifungal agents.
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Affiliation(s)
- Jiadi Shen
- Department of Endodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing 210000, China; (J.S.)
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing 210000, China
| | - Ming Ma
- Department of Endodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing 210000, China; (J.S.)
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing 210000, China
| | - Wei Duan
- Department of Endodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing 210000, China; (J.S.)
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing 210000, China
| | - Yun Huang
- Department of Endodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing 210000, China; (J.S.)
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing 210000, China
| | - Banruo Shi
- Department of Endodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing 210000, China; (J.S.)
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing 210000, China
| | - Qiaochu Wu
- Department of Endodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing 210000, China; (J.S.)
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing 210000, China
| | - Xin Wei
- Department of Endodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing 210000, China; (J.S.)
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing 210000, China
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Guha S, Cheng A, Carroll T, King D, Koren SA, Swords S, Nehrke K, Johnson GVW. Selective disruption of Drp1-independent mitophagy and mitolysosome trafficking by an Alzheimer's disease relevant tau modification in a novel Caenorhabditis elegans model. Genetics 2022; 222:iyac104. [PMID: 35916724 PMCID: PMC9434186 DOI: 10.1093/genetics/iyac104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 07/06/2022] [Indexed: 11/14/2022] Open
Abstract
Accumulation of inappropriately phosphorylated tau into neurofibrillary tangles is a defining feature of Alzheimer's disease, with Tau pT231 being an early harbinger of tau pathology. Previously, we demonstrated that expressing a single genomic copy of human phosphomimetic mutant tau (T231E) in Caenorhabditis elegans drove age-dependent neurodegeneration. A critical finding was that T231E, unlike wild-type tau, completely and selectively suppressed oxidative stress-induced mitophagy. Here, we used dynamic imaging approaches to analyze T231E-associated changes in mitochondria and mitolysosome morphology, abundance, trafficking, and stress-induced mitophagy as a function of mitochondrial fission mediator dynamin-related protein 1, which has been demonstrated to interact with hyper phosphorylated tau and contribute to Alzheimer's disease pathogenesis, as well as Pink1, a well-recognized mediator of mitochondrial quality control that works together with Parkin to support stress-induced mitophagy. T231E impacted both mitophagy and mitolysosome neurite trafficking with exquisite selectivity, sparing macroautophagy as well as lysosome and autolysosome trafficking. Both oxidative-stress-induced mitophagy and the ability of T231E to suppress it were independent of drp-1, but at least partially dependent on pink-1. Organelle trafficking was more complicated, with drp-1 and pink-1 mutants exerting independent effects, but generally supported the idea that the mitophagy phenotype is of greater physiologic impact in T231E. Collectively, our results refine the mechanistic pathway through which T231E causes neurodegeneration, demonstrating pathologic selectivity for mutations that mimic tauopathy-associated post-translational modifications, physiologic selectivity for organelles that contain damaged mitochondria, and molecular selectivity for dynamin-related protein 1-independent, Pink1-dependent, perhaps adaptive, and mitophagy.
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Affiliation(s)
- Sanjib Guha
- Department of Anesthesiology & Perioperative Medicine, University of Rochester, Rochester, NY 14642, USA
| | - Anson Cheng
- Department of Anesthesiology & Perioperative Medicine, University of Rochester, Rochester, NY 14642, USA
| | - Trae Carroll
- Department of Pathology and Laboratory Medicine, University of Rochester, Rochester, NY 14642, USA
| | - Dennisha King
- Department of Neuroscience, University of Rochester, Rochester, NY 14642, USA
| | - Shon A Koren
- Department of Anesthesiology & Perioperative Medicine, University of Rochester, Rochester, NY 14642, USA
| | - Sierra Swords
- Department of Molecular Biology and Biochemistry, Rutgers University, New Brunswick, NJ 08901, USA
| | - Keith Nehrke
- Department of Medicine, Nephrology Division, University of Rochester, Rochester, NY 14642, USA
| | - Gail V W Johnson
- Department of Anesthesiology & Perioperative Medicine, University of Rochester, Rochester, NY 14642, USA
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Oliveira NK, Bhattacharya S, Gambhir R, Joshi M, Fries BC. Novel ABC Transporter Associated with Fluconazole Resistance in Aging of Cryptococcus neoformans. J Fungi (Basel) 2022; 8:677. [PMID: 35887434 PMCID: PMC9320417 DOI: 10.3390/jof8070677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 06/24/2022] [Accepted: 06/26/2022] [Indexed: 11/27/2022] Open
Abstract
Cryptococcus neoformans causes meningoencephalitis in immunocompromised individuals, which is treated with fluconazole (FLC) monotherapy when resources are limited. This can lead to azole resistance, which can be mediated by overexpression of ABC transporters, a class of efflux pumps. ABC pump-mediated efflux of FLC is also augmented in 10-generation old C. neoformans cells. Here, we describe a new ABC transporter Afr3 (CNAG_06909), which is overexpressed in C. neoformans cells of advanced generational age that accumulate during chronic infection. The Δafr3 mutant strain showed higher FLC susceptibility by FLC E-Test strip testing and also by a killing test that measured survival after 3 h FLC exposure. Furthermore, Δafr3 cells exhibited lower Rhodamine 6G efflux compared to the H99 wild-type cells. Afr3 was expressed in the Saccharomyces cerevisiae ADΔ strain, which lacks several drug transporters, thus reducing background transport. The ADΔ + Afr3 strain demonstrated a higher efflux with both Rhodamine 6G and Nile red, and a higher FLC resistance. Afr3-GFP localized in the plasma membrane of the ADΔ + Afr3 strain, further highlighting its importance as an efflux pump. Characterization of the Δafr3 mutant revealed unattenuated growth but a prolongation (29%) of the replicative life span. In addition, Δafr3 exhibited decreased resistance to macrophage killing and attenuated virulence in the Galleria mellonella infection model. In summary, our data indicate that a novel ABC pump Afr3, which is upregulated in C. neoformans cells of advanced age, may contribute to their enhanced FLC tolerance, by promoting drug efflux. Lastly, its role in macrophage resistance may also contribute to the selection of older C. neoformans cells during chronic infection.
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Affiliation(s)
- Natalia Kronbauer Oliveira
- Department of Microbiology and Immunology, Renaissance School of Medicine, Stony Brook University, Stony Brook, NY 11794, USA;
| | - Somanon Bhattacharya
- Division of Infectious Diseases, Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA;
| | - Rina Gambhir
- Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA; (R.G.); (M.J.)
| | - Manav Joshi
- Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA; (R.G.); (M.J.)
| | - Bettina C. Fries
- Department of Microbiology and Immunology, Renaissance School of Medicine, Stony Brook University, Stony Brook, NY 11794, USA;
- Division of Infectious Diseases, Department of Medicine, Stony Brook University, Stony Brook, NY 11794, USA;
- Veterans Administration Medical Center, Northport, NY 11768, USA
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Atim PB, Meya DB, Gerlach ES, Muhanguzi D, Male A, Kanamwanji B, Nielsen K. Lack of Association between Fluconazole Susceptibility and ERG11 Nucleotide Polymorphisms in Cryptococcus neoformans Clinical Isolates from Uganda. J Fungi (Basel) 2022; 8:508. [PMID: 35628763 PMCID: PMC9145384 DOI: 10.3390/jof8050508] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 05/04/2022] [Accepted: 05/10/2022] [Indexed: 11/22/2022] Open
Abstract
Fluconazole is the drug of choice for cryptococcal meningitis (CM) monoprophylaxis in resource-limited settings such as Uganda. Emerging fluconazole resistance linked to mutations in the Cryptococcus neoformansERG11 gene (CYP51) has been observed in clinical isolates. Currently, the single nucleotide polymorphisms [SNPs] in the Cryptococcus spp. ERG11 gene that could be responsible for fluconazole resistance are poorly characterized within Ugandan C. neoformans clinical isolates. If available, this information would be useful in the management of cryptococcosis among HIV patients. This cross-sectional study investigates the SNPs present in the coding region of the C. neoformansERG11 gene to determine the relationship between the SNPs identified and fluconazole susceptibility of the clinical isolates. 310 C. neoformans isolates recovered from the Cerebrospinal Fluid (CSF) of patients with HIV and cryptococcal meningitis were examined. The fluconazole half-maximal inhibitory concentrations (IC50 range: 0.25−32 μg/mL) was determined using the microbroth dilution method. A total of 56.1% of the isolates had low IC50 values of <8 μg/mL while 43.9% had high IC50 values ≥ 8 μg/mL. We amplified and sequenced 600 bp of the ERG11 coding sequence from 40 of the clinical isolates. Novel synonymous and 2 missense mutations, S460T and A457V, were identified in the ERG11 gene. The identified SNPs were not associated with differences in fluconazole IC50 values in vitro (p = 0.179).
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Affiliation(s)
| | - David B. Meya
- Infectious Diseases Institute, Kampala P.O. Box 22418, Uganda;
- Department of Microbiology and Immunology, University of Minnesota, Minneapolis, MN 55455, USA; (E.S.G.); (K.N.)
| | - Elliot S. Gerlach
- Department of Microbiology and Immunology, University of Minnesota, Minneapolis, MN 55455, USA; (E.S.G.); (K.N.)
| | - Dennis Muhanguzi
- College of Veterinary Medicine Animal Resources and Biosecurity, Makerere University, Kampala P.O. Box 7062, Uganda;
| | - Allan Male
- International Centre for Tropical Agriculture (CIAT)—Uganda, Kampala P.O. Box 6247, Uganda;
| | - Benedict Kanamwanji
- National Microbiology Reference Laboratory (NMRL), Kampala P.O. Box 7272, Uganda;
| | - Kirsten Nielsen
- Department of Microbiology and Immunology, University of Minnesota, Minneapolis, MN 55455, USA; (E.S.G.); (K.N.)
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Chen YC, Kuo SF, Lin SY, Lin YS, Lee CH. Epidemiological and Clinical Characteristics, Antifungal Susceptibility, and MLST-Based Genetic Analysis of Cryptococcus Isolates in Southern Taiwan in 2013-2020. J Fungi (Basel) 2022; 8:jof8030287. [PMID: 35330289 PMCID: PMC8951076 DOI: 10.3390/jof8030287] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 03/09/2022] [Accepted: 03/10/2022] [Indexed: 02/04/2023] Open
Abstract
Cryptococcal meningoencephalitis (CM) is a treatable condition, but it leads to excessive morbidity and mortality. We collected 115 non-duplicated Cryptococcus clinical isolates during 2013−2020 in southern Taiwan to perform antifungal susceptibility testing. Multi-locus sequence typing was performed on 96 strains from patients with CM (n = 47) or cryptococcemia (n = 49). In addition, the epidemiological and clinical characteristics of patients with CM during 2013−2020 (n = 47) were compared with those during 2000−2010 (n = 46). During 2013−2020, only one C. neoformans isolate (0.9%) had a fluconazole minimum inhibitory concentration of >8 μg/mL. Amphotericin B (AMB), flucytosine (5FC), and voriconazole were highly active against all C. neoformans/C. gattii isolates. The most common sequence type was ST5. Among these 47 patients with CM, cerebrospinal fluid cryptococcal antigen (CSF CrAg) titer >1024 was a significant predictor of death (odds ratio, 48.33; 95% CI, 5.17−452.06). A standard induction therapy regimen with AMB and 5FC was used for all patients during 2013−2020, but only for 2.2% of patients in 2000−2010. The in-hospital CM mortality rate declined from 39.1% during 2000−2010 to 25.5% during 2013−2020, despite there being significantly younger patients with less CSF CrAg >1024 during 2000−2010. The study provides insight into the genetic epidemiology and antifungal susceptibility of Cryptococcus strains in southern Taiwan. The recommended antifungal drugs, AMB, 5FC, and FCZ, remained active against most of the Cryptococcus strains. Early diagnosis of patients with CM and adherence to the clinical practice guidelines cannot be overemphasized to improve the outcomes of patients with CM.
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Affiliation(s)
- Yi-Chun Chen
- Division of Infectious Diseases, Department of Internal Medicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan; (Y.-C.C.); (Y.-S.L.)
| | - Shu-Fang Kuo
- Department of Laboratory Medicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan;
- Department of Medical Biotechnology and Laboratory Sciences, College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan
| | - Shang-Yi Lin
- Division of Infectious Diseases, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung 80756, Taiwan;
- Department of Laboratory Medicine, Kaohsiung Medical University Hospital, Kaohsiung 80756, Taiwan
- College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
| | - Yin-Shiou Lin
- Division of Infectious Diseases, Department of Internal Medicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan; (Y.-C.C.); (Y.-S.L.)
| | - Chen-Hsiang Lee
- Division of Infectious Diseases, Department of Internal Medicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan; (Y.-C.C.); (Y.-S.L.)
- School of Medicine, College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan
- Correspondence: ; Tel.: +886-7-7317123 (ext. 8304); Fax: +886-7-7-7322402
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