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Arastehfar A, Daneshnia F, Floyd DJ, Jeffries NE, Salehi M, Perlin DS, Ilkit M, Lass-Flöerl C, Mansour MK. Echinocandin persistence directly impacts the evolution of resistance and survival of the pathogenic fungus Candida glabrata. mBio 2024; 15:e0007224. [PMID: 38501869 PMCID: PMC11005346 DOI: 10.1128/mbio.00072-24] [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: 01/17/2024] [Accepted: 02/23/2024] [Indexed: 03/20/2024] Open
Abstract
Recent epidemiological studies documented an alarming increase in the prevalence of echinocandin-resistant (ECR) Candida glabrata blood isolates. ECR isolates are known to arise from a minor subpopulation of a clonal population, termed echinocandin persisters. Although it is believed that isolates with a higher echinocandin persistence (ECP) are more likely to develop ECR, the implication of ECP needs to be better understood. Moreover, replacing laborious and time-consuming traditional approaches to determine ECP levels with rapid, convenient, and reliable tools is imperative to advance our understanding of this emerging concept in clinical practice. Herein, using extensive ex vivo and in vivo systemic infection models, we showed that high ECP isolates are less effectively cleared by micafungin treatment and exclusively give rise to ECR colonies. Additionally, we developed a flow cytometry-based tool that takes advantage of a SYTOX-based assay for the stratification of ECP levels. Once challenged with various collections of echinocandin-susceptible blood isolates, our assay reliably differentiated ECP levels in vitro and predicted ECP levels in real time under ex vivo and in vivo conditions when compared to traditional methods relying on colony-forming unit counting. Given the high and low ECP predictive values of 92.3% and 82.3%, respectively, our assay showed a high agreement with traditional approach. Collectively, our study supports the concept of ECP level determination in clinical settings and provides a robust tool scalable for high-throughput settings. Application of this tool facilitates the interrogation of mutant and drug libraries to further our understanding of persister biology and designing anti-persister therapeutics. IMPORTANCE Candida glabrata is a prevalent fungal pathogen able to replicate inside macrophages and rapidly develop resistance against frontline antifungal echinocandins. Multiple studies have shown that echinocandin resistance is fueled by the survival of a small subpopulation of susceptible cells surviving lethal concentrations of echinocandins. Importantly, bacterial pathogens that exhibit high antibiotic persistence also impose a high burden and generate more antibiotic-resistant colonies. Nonetheless, the implications of echinocandin persistence (ECP) among the clinical isolates of C. glabrata have not been defined. Additionally, ECP level determination relies on a laborious and time-consuming method, which is prone to high variation. By exploiting in vivo systemic infection and ex vivo models, we showed that C. glabrata isolates with a higher ECP are associated with a higher burden and more likely develop echinocandin resistance upon micafungin treatment. Additionally, we developed an assay that reliably determines ECP levels in real time. Therefore, our study identified C. glabrata isolates displaying high ECP levels as important entities and provided a reliable and convenient tool for measuring echinocandin persistence, which is extendable to other fungal and bacterial pathogens.
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Affiliation(s)
- Amir Arastehfar
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Farnaz Daneshnia
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
- Institute of Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, Amsterdam, The Netherlands
| | - Daniel J. Floyd
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
| | | | - Mostafa Salehi
- Department Industrial Engineering Faculty of K.N., Toosi University of Technology, Tehran, Iran
| | - David S. Perlin
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey, USA
- Hackensack Meridian School of Medicine, Nutley, New Jersey, USA
- Georgetown University Lombardi Comprehensive Cancer Center, Washington, District of Columbia, USA
| | - Macit Ilkit
- Division of Mycology, Faculty of Medicine, University of Çukurova, Adana, Türkiye
| | - Cornelia Lass-Flöerl
- Medical University Innsbruck, Institute of Hygiene and Medical Microbiology, Innsbruck, Austria
| | - Michael K. Mansour
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
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Naicker SD, Shuping L, Zulu TG, Mpembe RS, Mhlanga M, Tsotetsi EM, Maphanga TG, Govender NP. Epidemiology and susceptibility of Nakaseomyces (formerly Candida) glabrata bloodstream isolates from hospitalised adults in South Africa. Med Mycol 2023; 61:myad057. [PMID: 37336590 DOI: 10.1093/mmy/myad057] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 06/07/2023] [Accepted: 06/14/2023] [Indexed: 06/21/2023] Open
Abstract
During 2016-2017, Nakaseomyces glabrata (formerly Candida glabrata) caused 14% of cases of candidaemia in South Africa. We aimed to describe the clinical characteristics of adults with N. glabrata candidaemia at 20 sentinel hospitals (accounting for 20% (172/917) of cases) and the antifungal susceptibility of the corresponding isolates. A higher proportion of patients with N. glabrata candidaemia were older (median age: 55 years [interquartile range (IQR): 41-65 years] vs. 49 years [IQR: 35-63 years]; p = 0.04), female (87/164, 53% vs. 283/671, 42%; p = 0.01), admitted to a public-sector hospital (152/172, 88% vs. 470/745, 63%; p < 0.001), treated with fluconazole only (most with suboptimal doses) (51/95, 54% vs. 139/361, 39%; p < 0.001), and had surgery (47/172, 27% vs. 123/745, 17%; p = 0.001) and a shorter hospital stay (median 7 days [IQR: 2-20 days] vs. 13 days [IQR: 4-27 days]; p < 0.001) compared to patients with other causes of candidaemia. Eight N. glabrata isolates (6%, 8/131) had minimum inhibitory concentrations in the intermediate or resistant range for ≥ 1 echinocandin and a R1377K amino acid substitution encoded by the hotspot 2 region of the FKS2 gene. Only 11 isolates (8%, 11/131) were resistant to fluconazole. Patients with confirmed N. glabrata candidaemia are recommended to be treated with an echinocandin (or polyene), thus further guideline training is required.
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Affiliation(s)
- Serisha D Naicker
- Centre for Healthcare-Associated Infections, Antimicrobial Resistance and Mycoses, National Institute for Communicable Diseases, a Division of the National Health Laboratory Service, Johannesburg, South Africa
| | - Liliwe Shuping
- Centre for Healthcare-Associated Infections, Antimicrobial Resistance and Mycoses, National Institute for Communicable Diseases, a Division of the National Health Laboratory Service, Johannesburg, South Africa
| | - Thokozile G Zulu
- Centre for Healthcare-Associated Infections, Antimicrobial Resistance and Mycoses, National Institute for Communicable Diseases, a Division of the National Health Laboratory Service, Johannesburg, South Africa
| | - Ruth S Mpembe
- Centre for Healthcare-Associated Infections, Antimicrobial Resistance and Mycoses, National Institute for Communicable Diseases, a Division of the National Health Laboratory Service, Johannesburg, South Africa
| | - Mabatho Mhlanga
- Centre for Healthcare-Associated Infections, Antimicrobial Resistance and Mycoses, National Institute for Communicable Diseases, a Division of the National Health Laboratory Service, Johannesburg, South Africa
| | - Ernest M Tsotetsi
- Centre for Healthcare-Associated Infections, Antimicrobial Resistance and Mycoses, National Institute for Communicable Diseases, a Division of the National Health Laboratory Service, Johannesburg, South Africa
| | - Tsidiso G Maphanga
- Centre for Healthcare-Associated Infections, Antimicrobial Resistance and Mycoses, National Institute for Communicable Diseases, a Division of the National Health Laboratory Service, Johannesburg, South Africa
| | - Nelesh P Govender
- Centre for Healthcare-Associated Infections, Antimicrobial Resistance and Mycoses, National Institute for Communicable Diseases, a Division of the National Health Laboratory Service, Johannesburg, South Africa
- School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Division of Medical Microbiology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
- Institute of Infection and Immunity, St George's University of London, London and Medical Research Council Centre for Medical Mycology, University of Exeter, Exeter, United Kingdom
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3
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Arastehfar A, Daneshnia F, Cabrera N, Penalva-Lopez S, Sarathy J, Zimmerman M, Shor E, Perlin DS. Macrophage internalization creates a multidrug-tolerant fungal persister reservoir and facilitates the emergence of drug resistance. Nat Commun 2023; 14:1183. [PMID: 36864040 PMCID: PMC9981703 DOI: 10.1038/s41467-023-36882-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 02/22/2023] [Indexed: 03/04/2023] Open
Abstract
Candida glabrata is a major fungal pathogen notable for causing recalcitrant infections, rapid emergence of drug-resistant strains, and its ability to survive and proliferate within macrophages. Resembling bacterial persisters, a subset of genetically drug-susceptible C. glabrata cells can survive lethal exposure to the fungicidal echinocandin drugs. Herein, we show that macrophage internalization induces cidal drug tolerance in C. glabrata, expanding the persister reservoir from which echinocandin-resistant mutants emerge. We show that this drug tolerance is associated with non-proliferation and is triggered by macrophage-induced oxidative stress, and that deletion of genes involved in reactive oxygen species detoxification significantly increases the emergence of echinocandin-resistant mutants. Finally, we show that the fungicidal drug amphotericin B can kill intracellular C. glabrata echinocandin persisters, reducing emergence of resistance. Our study supports the hypothesis that intra-macrophage C. glabrata is a reservoir of recalcitrant/drug-resistant infections, and that drug alternating strategies can be developed to eliminate this reservoir.
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Affiliation(s)
- Amir Arastehfar
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, 07110, USA
| | - Farnaz Daneshnia
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, 07110, USA
- Institute of Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, Amsterdam, 1012 WX, The Netherlands
| | - Nathaly Cabrera
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, 07110, USA
| | - Suyapa Penalva-Lopez
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, 07110, USA
| | - Jansy Sarathy
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, 07110, USA
- Department of Medical Sciences, Hackensack Meridian School of Medicine, Nutley, NJ, USA
| | - Matthew Zimmerman
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, 07110, USA
- Department of Medical Sciences, Hackensack Meridian School of Medicine, Nutley, NJ, USA
| | - Erika Shor
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, 07110, USA.
- Department of Medical Sciences, Hackensack Meridian School of Medicine, Nutley, NJ, USA.
| | - David S Perlin
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, 07110, USA.
- Department of Medical Sciences, Hackensack Meridian School of Medicine, Nutley, NJ, USA.
- Georgetown University Lombardi Comprehensive Cancer Center, Washington, DC, 20057, USA.
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Multiple Genes of Candida albicans Influencing Echinocandin Susceptibility in Caspofungin-Adapted Mutants. Antimicrob Agents Chemother 2022; 66:e0097722. [PMID: 36354349 PMCID: PMC9765025 DOI: 10.1128/aac.00977-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Candida albicans is an opportunistic human fungal pathogen that causes invasive infections in immunocompromised individuals. Despite the high anticandidal activity among the echinocandins (ECNs), a first-line therapy, resistance remains an issue. Furthermore, many clinical isolates display decreased ECN susceptibility, a physiological state which is thought to lead to resistance. Determining the factors that can decrease susceptibility is of high importance. We searched for such factors genome-wide by comparing the transcriptional profiles of five mutants that acquired decreased caspofungin susceptibility in vitro in the absence of canonical FKS1 resistance mutations. The mutants were derived from two genetic backgrounds and arose due to independent mutational events, some with monosomic chromosome 5 (Ch5). We found that the mutants exhibit common transcriptional changes. In particular, all mutants upregulate five genes from Ch2 in concert. Knockout experiments show that all five genes positively influence caspofungin and anidulafungin susceptibility and play a role in regulating the cell wall mannan and glucan contents. The functions of three of these genes, orf19.1766, orf19.6867, and orf19.5833, were previously unknown, and our work expands the known functions of LEU42 and PR26. Importantly, orf19.1766 and LEU42 have no human orthologues. Our results provide important clues as to basic mechanisms of survival in the presence of ECNs while identifying new genes controlling ECN susceptibility and revealing new targets for the development of novel antifungal drugs.
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Bhakt P, Raney M, Kaur R. The SET-domain protein CgSet4 negatively regulates antifungal drug resistance via the ergosterol biosynthesis transcriptional regulator CgUpc2a. J Biol Chem 2022; 298:102485. [PMID: 36108742 PMCID: PMC9576903 DOI: 10.1016/j.jbc.2022.102485] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 08/30/2022] [Accepted: 09/02/2022] [Indexed: 11/27/2022] Open
Abstract
Invasive fungal infections, which pose a serious threat to human health, are increasingly associated with a high mortality rate and elevated health care costs, owing to rising resistance to current antifungals and emergence of multidrug-resistant fungal species. Candida glabrata is the second to fourth common cause of Candida bloodstream infections. Its high propensity to acquire resistance toward two mainstream drugs, azoles (inhibit ergosterol biosynthesis) and echinocandins (target cell wall), in clinical settings, and its inherent low azole susceptibility render antifungal therapy unsuccessful in many cases. Here, we demonstrate a pivotal role for the SET {suppressor of variegation 3 to 9 [Su(var)3-9], enhancer of zeste [E(z)], and trithorax (Trx)} domain-containing protein, CgSet4, in azole and echinocandin resistance via negative regulation of multidrug transporter-encoding and ergosterol biosynthesis (ERG) genes through the master transcriptional factors CgPdr1 and CgUpc2A, respectively. RNA-Seq analysis revealed that C. glabrata responds to caspofungin (CSP; echinocandin antifungal) stress by downregulation and upregulation of ERG and cell wall organization genes, respectively. Although CgSet4 acts as a repressor of the ergosterol biosynthesis pathway via CgUPC2A transcriptional downregulation, the CSP-induced ERG gene repression is not dependent on CgSet4, as CgSet4 showed diminished abundance on the CgUPC2A promoter in CSP-treated cells. Furthermore, we show a role for the last three enzymes of the ergosterol biosynthesis pathway, CgErg3, CgErg5, and CgErg4, in antifungal susceptibility and virulence in C. glabrata. Altogether, our results unveil the link between ergosterol biosynthesis and echinocandin resistance and have implications for combination antifungal therapy.
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Affiliation(s)
- Priyanka Bhakt
- Laboratory of Fungal Pathogenesis, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India
| | - Mayur Raney
- Laboratory of Fungal Pathogenesis, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India; Graduate Studies, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Rupinder Kaur
- Laboratory of Fungal Pathogenesis, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India.
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6
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Transcriptomics and Phenotyping Define Genetic Signatures Associated with Echinocandin Resistance in Candida auris. mBio 2022; 13:e0079922. [PMID: 35968956 PMCID: PMC9426441 DOI: 10.1128/mbio.00799-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Candida auris emerged as a human fungal pathogen only during the past decade. Remarkably, C. auris displays high degrees of genomic diversity and phenotypic plasticity, with four major clades causing hospital outbreaks with high mortality and morbidity rates. C. auris can show clinical resistance to all classes of antifungal drugs, including echinocandins that are usually recommended as first-line therapies for invasive candidiasis. Here, we exploit transcriptomics coupled with phenotypic profiling to characterize a set of clinical C. auris isolates displaying pronounced echinocandin resistance (ECN-R). A hot spot mutation in the echinocandin FKS1 target gene is present in all resistant isolates. Moreover, ECN-R strains share a core signature set of 362 genes differentially expressed in ECN-R isolates. Among others, mitochondrial gene expression and genes affecting cell wall function appear to be the most prominent, with the latter correlating well with enhanced adhesive traits, increased cell wall mannan content, and altered sensitivity to cell wall stress of ECN-R isolates. Moreover, ECN-R phenotypic signatures were also linked to pathogen recognition and interaction with immune cells. Hence, transcriptomics paired with phenotyping is a suitable tool to predict resistance and fitness traits as well as treatment outcomes in pathogen populations with complex phenotypic diversity. IMPORTANCE The surge in antimicrobial drug resistance in some bacterial and fungal pathogens constitutes a significant challenge to health care facilities. The emerging human fungal pathogen Candida auris has been particularly concerning, as isolates can display pan-antifungal resistance traits against all drugs, including echinocandins. However, the mechanisms underlying this phenotypic diversity remain poorly understood. We identify transcriptomic signatures in C. auris isolates resistant to otherwise fungicidal echinocandins. We identify a set of differentially expressed genes shared by resistant strains compared to unrelated susceptible isolates. Moreover, phenotyping demonstrates that resistant strains show distinct behaviors, with implications for host-pathogen interactions. Hence, this work provides a solid basis to identify the mechanistic links between antifungal multidrug resistance and fitness costs that affect the interaction of C. auris with host immune defenses.
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7
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Murphy SE, Bicanic T. Drug Resistance and Novel Therapeutic Approaches in Invasive Candidiasis. Front Cell Infect Microbiol 2022; 11:759408. [PMID: 34970504 PMCID: PMC8713075 DOI: 10.3389/fcimb.2021.759408] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 11/08/2021] [Indexed: 12/12/2022] Open
Abstract
Candida species are the leading cause of invasive fungal infections worldwide and are associated with acute mortality rates of ~50%. Mortality rates are further augmented in the context of host immunosuppression and infection with drug-resistant Candida species. In this review, we outline antifungal drugs already in clinical use for invasive candidiasis and candidaemia, their targets and mechanisms of resistance in clinically relevant Candida species, encompassing not only classical resistance, but also heteroresistance and tolerance. We describe novel antifungal agents and targets in pre-clinical and clinical development, including their spectrum of activity, antifungal target, clinical trial data and potential in treatment of drug-resistant Candida. Lastly, we discuss the use of combination therapy between conventional and repurposed agents as a potential strategy to combat the threat of emerging resistance in Candida.
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Affiliation(s)
- Sarah E Murphy
- Institute of Infection & Immunity, St George's University of London, London, United Kingdom
| | - Tihana Bicanic
- Institute of Infection & Immunity, St George's University of London, London, United Kingdom.,Clinical Academic Group in Infection and Immunity, St. George's University Hospital National Health Service (NHS) Foundation Trust, London, United Kingdom
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8
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Ribeiro GF, Denes E, Heaney H, Childers DS. What 'Omics Can Tell Us About Antifungal Adaptation. FEMS Yeast Res 2021; 21:6484793. [PMID: 34958354 PMCID: PMC8755904 DOI: 10.1093/femsyr/foab070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 12/22/2021] [Indexed: 12/01/2022] Open
Abstract
Invasive candidiasis, the most frequent healthcare-associated invasive fungal infection, is commonly caused by Candida albicans. However, in recent years other antifungal-resistant Candida species—namely Candida glabrata and Candidaauris—have emerged as a serious matter of concern. Much of our understanding of the mechanisms regulating antifungal resistance and tolerance relies on studies utilizing C. albicans, C. glabrataand the model yeast Saccharomyces cerevisiae. ‘Omics studies have been used to describe alterations in metabolic, genomic and transcriptomic expression profiles upon antifungal treatment of fungal cells. The physiological changes identified by these approaches could significantly affect fungal fitness in the host and survival during antifungal challenge, as well as provide further understanding of clinical resistance. Thus, this review aims to comparatively address ‘omics data for C. albicans, C. glabrata andS. cerevisiae published from 2000 to 2021 to identify what these technologies can tell us regarding cellular responses to antifungal therapy. We will also highlight possible effects on pathogen survival and identify future avenues for antifungal research.
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Affiliation(s)
- Gabriela Fior Ribeiro
- University of Aberdeen, Institute of Medical Sciences, Aberdeen Fungal Group, Aberdeen, UK, AB25 2ZD
| | - Eszter Denes
- University of Aberdeen, Institute of Medical Sciences, Aberdeen Fungal Group, Aberdeen, UK, AB25 2ZD
| | - Helen Heaney
- University of Aberdeen, Institute of Medical Sciences, Aberdeen Fungal Group, Aberdeen, UK, AB25 2ZD
| | - Delma S Childers
- University of Aberdeen, Institute of Medical Sciences, Aberdeen Fungal Group, Aberdeen, UK, AB25 2ZD
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9
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Ceballos-Garzon A, Monteoliva L, Gil C, Alvarez-Moreno C, Vega-Vela NE, Engelthaler DM, Bowers J, Le Pape P, Parra-Giraldo CM. Genotypic, proteomic, and phenotypic approaches to decipher the response to caspofungin and calcineurin inhibitors in clinical isolates of echinocandin-resistant Candida glabrata. J Antimicrob Chemother 2021; 77:585-597. [PMID: 34893830 PMCID: PMC8865013 DOI: 10.1093/jac/dkab454] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 11/09/2021] [Indexed: 01/20/2023] Open
Abstract
Background Echinocandin resistance represents a great concern, as these drugs are recommended as first-line therapy for invasive candidiasis. Echinocandin resistance is conferred by mutations in FKS genes. Nevertheless, pathways are crucial for enabling tolerance, evolution, and maintenance of resistance. Therefore, understanding the biological processes and proteins involved in the response to caspofungin may provide clues indicating new therapeutic targets. Objectives We determined the resistance mechanism and assessed the proteome response to caspofungin exposure. We then evaluated the phenotypic impact of calcineurin inhibition by FK506 and cephalosporine A (CsA) on caspofungin-resistant Candida glabrata isolates. Methods Twenty-five genes associated with caspofungin resistance were analysed by NGS, followed by studies of the quantitative proteomic response to caspofungin exposure. Then, susceptibility testing of caspofungin in presence of FK506 and CsA was performed. The effects of calcineurin inhibitor/caspofungin combinations on heat stress (40°C), oxidative stress (0.2 and 0.4 mM menadione) and on biofilm formation (polyurethane catheter) were analysed. Finally, a Galleria mellonella model using blastospores (1 × 109 cfu/mL) was developed to evaluate the impact of the combinations on larval survival. Results F659-del was found in the FKS2 gene of resistant strains. Proteomics data showed some up-regulated proteins are involved in cell-wall biosynthesis, response to stress and pathogenesis, some of them being members of calmodulin–calcineurin pathway. Therefore, the impact of calmodulin inhibition was explored. Calmodulin inhibition restored caspofungin susceptibility, decreased capacity to respond to stress conditions, and reduced biofilm formation and in vivo pathogenicity. Conclusions Our findings confirm that calmodulin-calcineurin-Crz1 could provide a relevant target in life-threatening invasive candidiasis.
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Affiliation(s)
- Andres Ceballos-Garzon
- Unidad de Proteómica y Micosis Humanas, Grupo de Enfermedades Infecciosas Departamento de Microbiología, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, D.C., Colombia
- Department of Parasitology and Medical Mycology, Faculty of Pharmacy, University of Nantes, Nantes Atlantique Universities, Nantes, France
| | - Lucia Monteoliva
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain
| | - Concha Gil
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain
- Unidad de Proteómica, Universidad Complutense de Madrid, Madrid, Spain
| | - Carlos Alvarez-Moreno
- Department of Internal Medicine, Faculty of Medicine, Universidad Nacional de Colombia, Bogotá, Colombia
- Clínica Universitaria Colombia, Clinica Colsanitas, Bogotá, Colombia
| | - Nelson E Vega-Vela
- Unidad de Proteómica y Micosis Humanas, Grupo de Enfermedades Infecciosas Departamento de Microbiología, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, D.C., Colombia
| | | | - Jolene Bowers
- Translational Genomics Research Institute, Flagstaff, AZ, USA
| | - Patrice Le Pape
- Department of Parasitology and Medical Mycology, Faculty of Pharmacy, University of Nantes, Nantes Atlantique Universities, Nantes, France
| | - Claudia M Parra-Giraldo
- Unidad de Proteómica y Micosis Humanas, Grupo de Enfermedades Infecciosas Departamento de Microbiología, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, D.C., Colombia
- Corresponding author. E-mail:
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10
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Burchacka E, Pięta P, Łupicka-Słowik A. Recent advances in fungal serine protease inhibitors. Biomed Pharmacother 2021; 146:112523. [PMID: 34902742 DOI: 10.1016/j.biopha.2021.112523] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 11/30/2021] [Accepted: 12/06/2021] [Indexed: 12/20/2022] Open
Abstract
Four types of antifungal drugs are available that include inhibitors of ergosterol synthesis, of fungal RNA biosynthesis, and of cell wall biosynthesis as well as physiochemical regulators of fungal membrane sterols. Increasing resistance to antifungal drugs can severely limit treatment options of fungal nail infections, vaginal candidiasis, ringworm, blastomycosis, histoplasmosis, and Candida infections of the mouth, throat, and esophagus, among other infections. Development of strategies focused on new fungicides can effectively help tackle troublesome fungal diseases. The virulence and optimal growth of fungi depend on various extracellular secreted factors, among which proteases, such as serine proteases, are of particular interest. A specific extracellular proteolytic system enables fungi to survive and penetrate the tissues. Given the role of fungal proteases in infection, any molecule capable of selectively and specifically inhibiting their activity can lead to the development of potential drugs. Owing to their specific mode of action, fungal protease inhibitors can avoid fungal resistance observed with currently available treatments. Although fungal secreted proteases have been extensively studied as potential virulence factors, our understanding of the substrate specificity of such proteases remains poor. In this review, we summarize the recent advances in the design and development of specific serine protease inhibitors and provide a brief history of the compounds that inhibit fungal serine protease activity.
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Affiliation(s)
- E Burchacka
- Faculty of Chemistry, Department of Organic and Medicinal Chemistry, Wrocław University of Science and Technology, 27 Wybrzeże Wyspiańskiego St, 50-370 Wrocław, Poland.
| | - P Pięta
- Department of Bionic and Medical Experimental Biology, Poznań University of Medical Sciences, Parkowa 2 St, 60-775 Poznań, Poland
| | - A Łupicka-Słowik
- Faculty of Chemistry, Department of Organic and Medicinal Chemistry, Wrocław University of Science and Technology, 27 Wybrzeże Wyspiańskiego St, 50-370 Wrocław, Poland
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11
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Ibe C, Munro CA. Fungal Cell Wall Proteins and Signaling Pathways Form a Cytoprotective Network to Combat Stresses. J Fungi (Basel) 2021; 7:jof7090739. [PMID: 34575777 PMCID: PMC8466366 DOI: 10.3390/jof7090739] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 09/01/2021] [Accepted: 09/04/2021] [Indexed: 12/13/2022] Open
Abstract
Candida species are part of the normal flora of humans, but once the immune system of the host is impaired and they escape from commensal niches, they shift from commensal to pathogen causing candidiasis. Candida albicans remains the primary cause of candidiasis, accounting for about 60% of the global candidiasis burden. The cell wall of C. albicans and related fungal pathogens forms the interface with the host, gives fungal cells their shape, and also provides protection against stresses. The cell wall is a dynamic organelle with great adaptive flexibility that allows remodeling, morphogenesis, and changes in its components in response to the environment. It is mainly composed of the inner polysaccharide rich layer (chitin, and β-glucan) and the outer protein coat (mannoproteins). The highly glycosylated protein coat mediates interactions between C. albicans cells and their environment, including reprograming of wall architecture in response to several conditions, such as carbon source, pH, high temperature, and morphogenesis. The mannoproteins are also associated with C. albicans adherence, drug resistance, and virulence. Vitally, the mannoproteins contribute to cell wall construction and especially cell wall remodeling when cells encounter physical and chemical stresses. This review describes the interconnected cell wall integrity (CWI) and stress-activated pathways (e.g., Hog1, Cek1, and Mkc1 mediated pathways) that regulates cell wall remodeling and the expression of some of the mannoproteins in C. albicans and other species. The mannoproteins of the surface coat is of great importance to pathogen survival, growth, and virulence, thus understanding their structure and function as well as regulatory mechanisms can pave the way for better management of candidiasis.
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Affiliation(s)
- Chibuike Ibe
- Department of Microbiology, Faculty of Biological Sciences, Abia State University, Uturu 441107, Nigeria
- Correspondence:
| | - Carol A. Munro
- Aberdeen Fungal Group, Institute of Medical Sciences, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen AB24 3FX, UK;
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Replicative Aging Remodels the Cell Wall and Is Associated with Increased Intracellular Trafficking in Human Pathogenic Yeasts. mBio 2021; 13:e0019022. [PMID: 35164553 PMCID: PMC8844920 DOI: 10.1128/mbio.00190-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Replicative aging is an underexplored field of research in medical mycology. Cryptococcus neoformans (Cn) and Candida glabrata (Cg) are dreaded fungal pathogens that cause fatal invasive infections. The fungal cell wall is essential for yeast viability and pathogenesis. In this study, we provide data characterizing age-associated modifications to the cell wall of Cn and Cg. Here, we report that old yeast cells upregulate genes of cell wall biosynthesis, leading to cell wall reorganization and increased levels of all major components, including glucan, chitin, and its derivatives, as well as mannan. This results in a significant thickening of the cell wall in aged cells. Old-generation yeast cells exhibited drastic ultrastructural changes, including the presence of abundant vesicle-like particles in the cytoplasm, and enlarged vacuoles with altered pH homeostasis. Our findings suggest that the cell wall modifications could be enabled by augmented intracellular trafficking. This work furthers our understanding of the cell phenotype that emerges during aging. It highlights differences in these two fungal pathogens and elucidates mechanisms that explain the enhanced resistance of old cells to antifungals and phagocytic attacks. IMPORTANCE Cryptococcus neoformans and Candida glabrata are two opportunistic human fungal pathogens that cause life-threatening diseases. During infection, both microorganisms have the ability to persist for long periods, and treatment failure can occur even if standard testing identifies the yeasts to be sensitive to antifungals. Replicative life span is a trait that is measured by the number of divisions a cell undergoes before death. Aging in fungi is associated with enhanced tolerance to antifungals and resistance to phagocytosis, and characterization of old cells may help identify novel antifungal targets. The cell wall remains an attractive target for new therapies because it is essential for fungi and is not present in humans. This study shows that the organization of the fungal cell wall changes remarkably during aging and becomes thicker and is associated with increased intracellular trafficking as well as the alteration of vacuole morphology and pH homeostasis.
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