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Xue P, Sánchez-León E, Hu G, Lee CWJ, Black B, Brisland A, Li H, Jung WH, Kronstad JW. The interplay between electron transport chain function and iron regulatory factors influences melanin formation in Cryptococcus neoformans. mSphere 2024:e0025024. [PMID: 38687055 DOI: 10.1128/msphere.00250-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Accepted: 03/28/2024] [Indexed: 05/02/2024] Open
Abstract
Mitochondrial functions are critical for the ability of the fungal pathogen Cryptococcus neoformans to cause disease. However, mechanistic connections between key functions such as the mitochondrial electron transport chain (ETC) and virulence factor elaboration have yet to be thoroughly characterized. Here, we observed that inhibition of ETC complex III suppressed melanin formation, a major virulence factor. This inhibition was partially overcome by defects in Cir1 or HapX, two transcription factors that regulate iron acquisition and use. In this regard, loss of Cir1 derepresses the expression of laccase genes as a potential mechanism to restore melanin, while HapX may condition melanin formation by controlling oxidative stress. We hypothesize that ETC dysfunction alters redox homeostasis to influence melanin formation. Consistent with this idea, inhibition of growth by hydrogen peroxide was exacerbated in the presence of the melanin substrate L-DOPA. In addition, loss of the mitochondrial chaperone Mrj1, which influences the activity of ETC complex III and reduces ROS accumulation, also partially overcame antimycin A inhibition of melanin. The phenotypic impact of mitochondrial dysfunction was consistent with RNA-Seq analyses of WT cells treated with antimycin A or L-DOPA, or cells lacking Cir1 that revealed influences on transcripts encoding mitochondrial functions (e.g., ETC components and proteins for Fe-S cluster assembly). Overall, these findings reveal mitochondria-nuclear communication via ROS and iron regulators to control virulence factor production in C. neoformans.IMPORTANCEThere is a growing appreciation of the importance of mitochondrial functions and iron homeostasis in the ability of fungal pathogens to sense the vertebrate host environment and cause disease. Many mitochondrial functions such as heme and iron-sulfur cluster biosynthesis, and the electron transport chain (ETC), are dependent on iron. Connections between factors that regulate iron homeostasis and mitochondrial activities are known in model yeasts and are emerging for fungal pathogens. In this study, we identified connections between iron regulatory transcription factors (e.g., Cir1 and HapX) and the activity of complex III of the ETC that influence the formation of melanin, a key virulence factor in the pathogenic fungus Cryptococcus neoformans. This fungus causes meningoencephalitis in immunocompromised people and is a major threat to the HIV/AIDS population. Thus, understanding how mitochondrial functions influence virulence may support new therapeutic approaches to combat diseases caused by C. neoformans and other fungi.
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Affiliation(s)
- Peng Xue
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Eddy Sánchez-León
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Guanggan Hu
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Christopher W J Lee
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Braydon Black
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Anna Brisland
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Haohua Li
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Won Hee Jung
- Department of Systems Biotechnology, Chung-Ang University, Anseong, South Korea
| | - James W Kronstad
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
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2
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Rudhra O, Gnanam H, Sivaperumal S, Namperumalsamy V, Prajna L, Kuppamuthu D. Melanin depletion affects Aspergillus flavus conidial surface proteins, architecture, and virulence. Appl Microbiol Biotechnol 2024; 108:291. [PMID: 38592509 PMCID: PMC11004046 DOI: 10.1007/s00253-024-13107-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 03/06/2024] [Accepted: 03/10/2024] [Indexed: 04/10/2024]
Abstract
Melanin is an Aspergillus flavus cell wall component that provides chemical and physical protection to the organism. However, the molecular and biological mechanisms modulating melanin-mediated host-pathogen interaction in A. flavus keratitis are not well understood. This work aimed to compare the morphology, surface proteome profile, and virulence of melanized conidia (MC) and non-melanized conidia (NMC) of A. flavus. Kojic acid treatment inhibited melanin synthesis in A. flavus, and the conidial surface protein profile was significantly different in kojic acid-treated non-melanized conidia. Several cell wall-associated proteins and proteins responsible for oxidative stress, carbohydrate, and chitin metabolic pathways were found only in the formic acid extracts of NMC. Scanning electron microscopy (SEM) analysis showed the conidial surface morphology difference between the NMC and MC, indicating the role of melanin in the structural integrity of the conidial cell wall. The levels of calcofluor white staining efficiency were different, but there was no microscopic morphology difference in lactophenol cotton blue staining between MC and NMC. Evaluation of the virulence of MC and NMC in the Galleria mellonella model showed NMC was less virulent compared to MC. Our findings showed that the integrity of the conidial surface is controlled by the melanin layer. The alteration in the surface protein profile indicated that many surface proteins are masked by the melanin layer, and hence, melanin can modulate the host response by preventing the exposure of fungal proteins to the host immune defense system. The G. mellonella virulence assay also confirmed that the NMC were susceptible to host defense as in other Aspergillus pathogens. KEY POINTS: • l-DOPA melanin production was inhibited in A. flavus isolates by kojic acid, and for the first time, scanning electron microscopy (SEM) analysis revealed morphological differences between MC and NMC of A. flavus strains • Proteome profile of non-melanized conidia showed more conidial surface proteins and these proteins were mainly involved in the virulence, oxidative stress, and metabolism pathways • Non-melanized conidia of A. flavus strains were shown to be less virulent than melanised conidia in an in vivo virulence experiment with the G. melonella model.
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Affiliation(s)
- Ondippili Rudhra
- Department of Proteomics, Aravind Medical Research Foundation, Madurai, Tamil Nadu, India
| | - Hariharan Gnanam
- Department of Proteomics, Aravind Medical Research Foundation, Madurai, Tamil Nadu, India
| | - Sivaramakrishnan Sivaperumal
- Department of Biotechnology and Genetic Engineering, Bharathidasan University, Tiruchirappalli, Tamil Nadu, India
| | | | - Lalitha Prajna
- Department of Ocular Microbiology, Aravind Eye Hospital, Aravind Eye Care System, Madurai, Tamil Nadu, India
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3
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Xue P, Sánchez-León E, Hu G, Lee CWJ, Black B, Brisland A, Li H, Jung WH, Kronstad JW. The interplay between electron transport chain function and iron regulatory factors influences melanin formation in Cryptococcus neoformans. bioRxiv 2024:2024.02.15.580540. [PMID: 38405941 PMCID: PMC10888943 DOI: 10.1101/2024.02.15.580540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Mitochondrial functions are critical for the ability of the fungal pathogen Cryptococcus neoformans to cause disease. However, mechanistic connections between key functions such as the mitochondrial electron transport chain (ETC) and virulence factor elaboration have yet to be thoroughly characterized. Here, we observed that inhibition of ETC complex III suppressed melanin formation, a major virulence factor. This inhibition was partially blocked upon loss of Cir1 or HapX, two transcription factors that regulate iron acquisition and use. In this regard, loss of Cir1 derepresses the expression of laccase genes as a potential mechanism to restore melanin, while HapX may condition melanin formation by controlling oxidative stress. We hypothesize that ETC dysfunction alters redox homeostasis to influence melanin formation. Consistent with this idea, inhibition of growth by hydrogen peroxide was exacerbated in the presence of the melanin substrate L-DOPA. Additionally, loss of the mitochondrial chaperone Mrj1, which influences the activity of ETC complex III and reduces ROS accumulation, also partially blocked antimycin A inhibition of melanin. The phenotypic impact of mitochondrial dysfunction was consistent with RNA-Seq analyses of WT cells treated with antimycin A or L-DOPA, or cells lacking Cir1 that revealed influences on transcripts encoding mitochondrial functions (e.g., ETC components and proteins for Fe-S cluster assembly). Overall, these findings reveal mitochondria-nuclear communication via ROS and iron regulators to control virulence factor production in C. neoformans.
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Affiliation(s)
- Peng Xue
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
- Present address: Nantong Key Laboratory of Environmental Toxicology, Department of Occupational Medicine and Environmental Toxicology, School of Public Health, Nantong University, Nantong, Jiangsu, China
| | - Eddy Sánchez-León
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Guanggan Hu
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Christopher WJ Lee
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Braydon Black
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Anna Brisland
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Haohua Li
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Won Hee Jung
- Department of Systems Biotechnology, Chung-Ang University, Anseong, Republic of Korea
| | - James W. Kronstad
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
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4
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Trung HT, Purnomo KA, Yu SY, Yang ZJ, Hu HC, Hwang TL, Tuan NN, Tu LN, Duc DX, Quang LD, Backlund A, Thang TD, Chang FR. Anti-inflammatory and Antiphytopathogenic Fungal Activity of 2,3- seco-Tirucallane Triterpenoids Meliadubins A and B from Melia dubia Cav. Barks with ChemGPS-NP and In Silico Prediction. ACS Omega 2023; 8:37116-37127. [PMID: 37841162 PMCID: PMC10568771 DOI: 10.1021/acsomega.3c04657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 08/28/2023] [Indexed: 10/17/2023]
Abstract
Two new rearranged 2,3-seco-tirucallane triterpenoids, meliadubins A (1) and B (2), along with four known compounds, 3-6, were isolated from the barks of Melia dubia Cav. Compound 2 exhibited a significant inflammatory inhibition effect toward superoxide anion generation in human neutrophils (EC50 at 5.54 ± 0.36 μM). It bound to active sites of a human inducible nitric oxide synthase (3E7G) through interactions with the residues of GLU377 and PRO350, which may benefit in reducing the neutrophilic inflammation effect. The ChemGPS-NP interpretation combined with bioactivity assay and in silico prediction results suggested 2 to be an agent for targeting iNOS with different mechanisms as compared to a selected set of current approved drugs. Moreover, compounds 1 and 2 showed remarkable inhibition against the rice pathogenic fungus Magnaporthe oryzae in a dose-dependent manner with IC50 values of 137.20 ± 9.55 and 182.50 ± 18.27 μM, respectively. Both 1 and 2 displayed interactions with the residue of TYR223, a key active site of trihydroxynaphthalene reductase (1YBV). The interpretation of 1 and 2 in the ChemGPS-NP physical-chemical property space indicated that both compounds are quite different compared to all members of a selected set of reference compounds. In light of demonstrated biological activity and in silico prediction experiments, both compounds possibly exhibited activity against phytopathogenic fungi via a novel mode of action.
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Affiliation(s)
- Hieu Tran Trung
- Department
of Chemistry, Vinh University, Vinh City 462030, Viet Nam
| | - Kartiko Arif Purnomo
- Graduate
Institute of Natural Products, College of Pharmacy, Kaohsiung Medical University, Kaohsiung 807378, Taiwan
| | - Szu-Yin Yu
- Graduate
Institute of Natural Products, College of Pharmacy, Kaohsiung Medical University, Kaohsiung 807378, Taiwan
- Institute
of Pharmacognosy, University of Szeged, Szeged 6720, Hungary
| | - Zih-Jie Yang
- Graduate
Institute of Natural Products, College of Pharmacy, Kaohsiung Medical University, Kaohsiung 807378, Taiwan
| | - Hao-Chun Hu
- Graduate
Institute of Natural Products, College of Pharmacy, Kaohsiung Medical University, Kaohsiung 807378, Taiwan
- Institute of Pharmaceutical
Chemistry, University of Szeged, Szeged 6720, Hungary
- Graduate
Institute of Natural Products, School of Traditional Medicine, College
of Medicine, Chang Gung University, Taoyuan 333323, Taiwan
| | - Tsong-Long Hwang
- Graduate
Institute of Natural Products, School of Traditional Medicine, College
of Medicine, Chang Gung University, Taoyuan 333323, Taiwan
- Research
Center for Chinese Herbal Medicine, Research Center for Food and Cosmetic
Safety, and Graduate Institute of Health Industry Technology, College
of Human Ecology, Chang Gung University
of Science and Technology, Taoyuan 333324, Taiwan
- Department
of Anesthesiology, Chang Gung Memorial Hospital, Taoyuan 333423, Taiwan
| | - Nguyen Ngoc Tuan
- Institute
of Biotechnology and Food Technology, Industrial
University of Ho Chi Minh City, Ho Chi Minh City 727000, Viet Nam
| | - Le Ngoc Tu
- Faculty
of Chemistry, Ho Chi Minh City University
of Education, Ho Chi
Minh City 749000, Viet Nam
| | - Dau Xuan Duc
- Department
of Chemistry, Vinh University, Vinh City 462030, Viet Nam
| | - Le Dang Quang
- Institute
for Tropical Technology, Vietnam Academy
of Science and Technology (VAST), Hanoi 122000, Viet Nam
| | - Anders Backlund
- Research Group Pharmacognosy, Department
of Pharmaceutical Biosciences, Uppsala University, Uppsala S-75124, Sweden
| | - Tran Dinh Thang
- Institute
of Biotechnology and Food Technology, Industrial
University of Ho Chi Minh City, Ho Chi Minh City 727000, Viet Nam
| | - Fang-Rong Chang
- Graduate
Institute of Natural Products, College of Pharmacy, Kaohsiung Medical University, Kaohsiung 807378, Taiwan
- Drug Development
and Value Creation Research Center, Kaohsiung
Medical University, Kaohsiung 807378, Taiwan
- Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 807378, Taiwan
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5
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Romero V, Kalinhoff C, Saa LR, Sánchez A. Fungi's Swiss Army Knife: Pleiotropic Effect of Melanin in Fungal Pathogenesis during Cattle Mycosis. J Fungi (Basel) 2023; 9:929. [PMID: 37755037 PMCID: PMC10532448 DOI: 10.3390/jof9090929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 09/05/2023] [Accepted: 09/08/2023] [Indexed: 09/28/2023] Open
Abstract
Fungal threats to public health, food security, and biodiversity have escalated, with a significant rise in mycosis cases globally. Around 300 million people suffer from severe fungal diseases annually, while one-third of food crops are decimated by fungi. Vertebrate, including livestock, are also affected. Our limited understanding of fungal virulence mechanisms hampers our ability to prevent and treat cattle mycoses. Here we aim to bridge knowledge gaps in fungal virulence factors and the role of melanin in evading bovine immune responses. We investigate mycosis in bovines employing a PRISMA-based methodology, bioinformatics, and data mining techniques. Our analysis identified 107 fungal species causing mycoses, primarily within the Ascomycota division. Candida, Aspergillus, Malassezia, and Trichophyton were the most prevalent genera. Of these pathogens, 25% produce melanin. Further research is required to explore the involvement of melanin and develop intervention strategies. While the literature on melanin-mediated fungal evasion mechanisms in cattle is lacking, we successfully evaluated the transferability of immunological mechanisms from other model mammals through homology. Bioinformatics enables knowledge transfer and enhances our understanding of mycosis in cattle. This synthesis fills critical information gaps and paves the way for proposing biotechnological strategies to mitigate the impact of mycoses in cattle.
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Affiliation(s)
- Víctor Romero
- Maestría en Biotecnología Agropecuaria, Universidad Técnica Particular de Loja, San Cayetano Alto, Calle París s/n, Loja 1101608, Ecuador
- Museo de Zoología, Universidad Técnica Particular de Loja, San Cayetano Alto, Calle París s/n, Loja 1101608, Ecuador
| | - Carolina Kalinhoff
- Departamento de Ciencias Biológicas y Agropecuarias, Facultad de Ciencias Exactas y Naturales, Universidad Técnica Particular de Loja, San Cayetano Alto, Calle París s/n, Loja 1101608, Ecuador; (C.K.)
| | - Luis Rodrigo Saa
- Departamento de Ciencias Biológicas y Agropecuarias, Facultad de Ciencias Exactas y Naturales, Universidad Técnica Particular de Loja, San Cayetano Alto, Calle París s/n, Loja 1101608, Ecuador; (C.K.)
| | - Aminael Sánchez
- Departamento de Ciencias Biológicas y Agropecuarias, Facultad de Ciencias Exactas y Naturales, Universidad Técnica Particular de Loja, San Cayetano Alto, Calle París s/n, Loja 1101608, Ecuador; (C.K.)
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6
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Hatinguais R, Leaves I, Brown GD, Brown AJP, Brock M, Peres da Silva R. CRISPR-based tools for targeted genetic manipulation in pathogenic Sporothrix species. Microbiol Spectr 2023; 11:e0507822. [PMID: 37707447 PMCID: PMC10581184 DOI: 10.1128/spectrum.05078-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 07/11/2023] [Indexed: 09/15/2023] Open
Abstract
Sporothrix brasiliensis is an emerging fungal pathogen frequently associated with zoonotic transmission of sporotrichosis by contaminated cats. Within 25 years, the disease has spread not only throughout Brazil but now to neighboring countries in Latin America. Thermo-dimorphism, melanin, glycans, adhesins, and secreted vesicles have been associated with the ability of Sporothrix species to cause disease in the mammalian host. Although certain virulence factors have been proposed as potential determinants for sporotrichosis, the scarcity of molecular tools for performing reverse genetics in Sporothrix has significantly impeded the dissection of mechanisms underlying the disease. Here, we demonstrate that PEG-mediated protoplast transformation is a powerful method for heterologous gene expression in S. brasiliensis, S. schenckii, and S. chilensis. Combined with CRISPR/Cas9 gene editing, this transformation protocol enabled the deletion of the putative DHN-melanin synthase gene pks1, which is a proposed virulence factor of Sporothrix species. To improve in locus integration of deletion constructs, we deleted the KU80 homolog that is critical for non-homologous end-joining DNA repair. The use of Δku80 strains from S. brasiliensis enhanced homologous-directed repair during transformation resulting in increased targeted gene deletion in combination with CRISPR/Cas9. In conclusion, our CRISPR/Cas9-based transformation protocol provides an efficient tool for targeted gene manipulation in Sporothrix species. IMPORTANCE Sporotrichosis caused by Sporothrix brasiliensis is a disease that requires long periods of treatment and is rapidly spreading across Latin America. The virulence of this fungus and the surge of atypical and more severe presentations of the disease raise the need for an understanding of the molecular mechanisms underlying sporotrichosis, as well as the development of better diagnostics and antifungal therapies. By developing molecular tools for accurate genetic manipulation in Sporothrix, this study addresses the paucity of reliable and reproducible tools for stable genetic engineering of Sporothrix species, which has represented a major obstacle for studying the virulence determinants and their roles in the establishment of sporotrichosis.
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Affiliation(s)
- Remi Hatinguais
- Medical Research Council Centre for Medical Mycology, University of Exeter, Exeter, United Kingdom
| | - Ian Leaves
- Medical Research Council Centre for Medical Mycology, University of Exeter, Exeter, United Kingdom
| | - Gordon D. Brown
- Medical Research Council Centre for Medical Mycology, University of Exeter, Exeter, United Kingdom
| | - Alistair J. P. Brown
- Medical Research Council Centre for Medical Mycology, University of Exeter, Exeter, United Kingdom
| | - Matthias Brock
- Fungal Biology Group, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Roberta Peres da Silva
- Medical Research Council Centre for Medical Mycology, University of Exeter, Exeter, United Kingdom
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7
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Ortiz-Ramírez JA, Cuéllar-Cruz M, Villagómez-Castro JC, López-Romero E. Fungal Glycosidases in Sporothrix Species and Candida albicans. J Fungi (Basel) 2023; 9:919. [PMID: 37755027 PMCID: PMC10532485 DOI: 10.3390/jof9090919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 08/30/2023] [Accepted: 09/06/2023] [Indexed: 09/28/2023] Open
Abstract
Glycoside hydrolases (GHs) are enzymes that participate in many biological processes of fungi and other organisms by hydrolyzing glycosidic linkages in glycosides. They play fundamental roles in the degradation of carbohydrates and the assembly of glycoproteins and are important subjects of studies in molecular biology and biochemistry. Based on amino acid sequence similarities and 3-dimensional structures in the carbohydrate-active enzyme (CAZy), they have been classified in 171 families. Members of some of these families also exhibit the activity of trans-glycosydase or glycosyl transferase (GT), i.e., they create a new glycosidic bond in a substrate instead of breaking it. Fungal glycosidases are important for virulence by aiding tissue adhesion and colonization, nutrition, immune evasion, biofilm formation, toxin release, and antibiotic resistance. Here, we review fungal glycosidases with a particular emphasis on Sporothrix species and C. albicans, two well-recognized human pathogens. Covered issues include a brief account of Sporothrix, sporotrichosis, the different types of glycosidases, their substrates, and mechanism of action, recent advances in their identification and characterization, their potential biotechnological applications, and the limitations and challenges of their study given the rather poor available information.
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Affiliation(s)
| | | | | | - Everardo López-Romero
- Departamento de Biología, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Guanajuato 36050, Mexico
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8
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Almutawif YA, Al‐kuraishy HM, Al‐Gareeb AI, Alexiou A, Papadakis M, Eid HMA, Saad HM, Batiha GE. Insights on Covid-19 with superimposed pulmonary histoplasmosis: The possible nexus. Immun Inflamm Dis 2023; 11:e989. [PMID: 37773721 PMCID: PMC10540147 DOI: 10.1002/iid3.989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 08/06/2023] [Accepted: 08/09/2023] [Indexed: 10/01/2023] Open
Abstract
A novel coronavirus (CoV) known as severe acute respiratory syndrome CoV type 2 is the causative agent for the development of CoV disease 2019 (Covid-19). Covid-19 may increase the risk of developing pulmonary histoplasmosis due to immune dysregulation. In addition, Covid-19 may enhance the propagation of acute pulmonary histoplasmosis due to lung injury and inflammation, and using corticosteroids in severely affected Covid-19 patients may reactivate latent pulmonary histoplasmosis. Likewise, activation of inflammatory signaling pathways during H. capsulatum infection may increase the severity of Covid-19 and vice versa. Furthermore, lymphopenia in Covid-19 may increase the risk for the progress of pulmonary histoplasmosis besides activation of inflammatory signaling pathways during H. capsulatum infection may increase the severity of Covid-19 and vice versa. Therefore, this critical review aimed to find the potential link between Covid-19 pneumonia and pulmonary histoplasmosis concerning the immunological response.
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Affiliation(s)
- Yahya A. Almutawif
- Department of Medical Laboratories Technology, College of Applied Medical SciencesTaibah UniversityMadinahSaudi Arabia
| | - Hayder M. Al‐kuraishy
- Department of Clinical Pharmacology and Medicine, College of MedicineAl‐Mustansiriyia UniversityBaghdadIraq
| | - Ali I. Al‐Gareeb
- Department of Clinical Pharmacology and Medicine, College of MedicineAl‐Mustansiriyia UniversityBaghdadIraq
| | - Athanasios Alexiou
- Department of Science and EngineeringNovel Global Community Educational FoundationHebershamNew South WalesAustralia
- AFNP MedWienAustria
| | - Marios Papadakis
- Department of Surgery II, University Hospital Witten‐Herdecke, Heusnerstrasse 40University of Witten‐HerdeckeWuppertalGermany
| | - Hamza M. A. Eid
- Department of Medical Laboratories Technology, College of Applied Medical SciencesTaibah UniversityMadinahSaudi Arabia
| | - Hebatallah M. Saad
- Department of Pathology, Faculty of Veterinary MedicineMatrouh UniversityMarsaMatruhEgypt
| | - Gaber El‐Saber Batiha
- Department of Pharmacology and Therapeutics, Faculty of Veterinary MedicineDamanhour UniversityDamanhourAlBeheiraEgypt
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9
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Kim JS, Bahn YS. Protein Kinase A Controls the Melanization of Candida auris through the Alteration of Cell Wall Components. Antioxidants (Basel) 2023; 12:1702. [PMID: 37760005 PMCID: PMC10525270 DOI: 10.3390/antiox12091702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 08/23/2023] [Accepted: 08/28/2023] [Indexed: 09/29/2023] Open
Abstract
Candida auris, a multidrug-resistant fungal pathogen, significantly threatens global public health. Recent studies have identified melanin production, a key virulence factor in many pathogenic fungi that protects against external threats like reactive oxygen species, in C. auris. However, the melanin regulation mechanism remains elusive. This study explores the role of the Ras/cAMP/PKA signaling pathway in C. auris melanization. It reveals that the catalytic subunits Tpk1 and Tpk2 of protein kinase A (PKA) are essential, whereas Ras1, Gpr1, Gpa2, and Cyr1 are not. Under melanin-promoting conditions, the tpk1Δ tpk2Δ strain formed melanin granules in the supernatant akin to the wild-type strain but failed to adhere them properly to the cell wall. This discrepancy is likely due to a decreased expression of chitin-synthesis-related genes. Our findings also show that Tpk1 primarily drives melanization, with Tpk2 having a lesser impact. To corroborate this, we found that C. auris must deploy Tpk1-dependent melanin deposition as a defensive mechanism against antioxidant exposure. Moreover, we confirmed that deletion mutants of multicopper oxidase and ferroxidase genes, previously assumed to influence C. auris melanization, do not directly contribute to the process. Overall, this study sheds light on the role of PKA in C. auris melanization and enhances our understanding of the pathogenicity mechanisms of this emerging fungal pathogen.
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Affiliation(s)
| | - Yong-Sun Bahn
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Republic of Korea;
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10
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Pruksaphon K, Amsri A, Thammasit P, Nosanchuk JD, Youngchim S. Extracellular vesicles derived from Talaromyces marneffei contain immunogenic compounds and modulate THP-1 macrophage responses. Front Immunol 2023; 14:1192326. [PMID: 37457708 PMCID: PMC10339390 DOI: 10.3389/fimmu.2023.1192326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 06/08/2023] [Indexed: 07/18/2023] Open
Abstract
Pathogenic eukaryotes including fungi release extracellular vesicles (EVs) which are composed of a variety of bioactive components, including peptides, nucleic acids, polysaccharides, and membrane lipids. EVs contain virulence-associated molecules suggesting a crucial role of these structures in disease pathogenesis. EVs derived from the pathogenic yeast phase of Talaromyces (Penicillium) marneffei, a causative agent of systemic opportunistic mycoses "talaromycosis," were studied for their immunogenic components and immunomodulatory properties. Some important virulence factors in EVs including fungal melanin and yeast phase specific mannoprotein were determined by immunoblotting. Furthermore, fluorescence microscopy revealed that T. marneffei EVs were internalized by THP-1 human macrophages. Co-incubation of T. marneffei EVs with THP-1 human macrophages resulted in increased levels of supernatant interleukin (IL)-1β, IL-6 and IL-10. The expression of THP-1 macrophage surface CD86 was significantly increased after exposed to T. marneffei EVs. These findings support the hypothesis that fungal EVs play an important role in macrophage "classical" M1 polarization. T. marneffei EVs preparations also increased phagocytosis, suggesting that EV components stimulate THP-1 macrophages to produce effective antimicrobial compounds. In addition, T. marneffei EVs stimulated THP-1 macrophages were more effective at killing T. marneffei conidia. These results indicate that T. marneffei EVs can potently modulate macrophage functions, resulting in the activation of these innate immune cells to enhance their antimicrobial activity.
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Affiliation(s)
- Kritsada Pruksaphon
- Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Artid Amsri
- Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Patcharin Thammasit
- Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Joshua D. Nosanchuk
- Department of Medicine (Division of Infectious Diseases) and Department of Microbiology and Immunology, Albert Einstein College of Medicine, New York, NY, United States
| | - Sirida Youngchim
- Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
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11
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Urbaniak MM, Gazińska M, Rudnicka K, Płociński P, Nowak M, Chmiela M. In Vitro and In Vivo Biocompatibility of Natural and Synthetic Pseudomonas aeruginosa Pyomelanin for Potential Biomedical Applications. Int J Mol Sci 2023; 24:ijms24097846. [PMID: 37175552 PMCID: PMC10178424 DOI: 10.3390/ijms24097846] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 04/17/2023] [Accepted: 04/24/2023] [Indexed: 05/15/2023] Open
Abstract
Bacteria are the source of many bioactive compounds, including polymers with various physiological functions and the potential for medical applications. Pyomelanin from Pseudomonas aeruginosa, a nonfermenting Gram-negative bacterium, is a black-brown negatively charged extracellular polymer of homogentisic acid produced during L-tyrosine catabolism. Due to its chemical properties and the presence of active functional groups, pyomelanin is a candidate for the development of new antioxidant, antimicrobial and immunomodulatory formulations. This work aimed to obtain bacterial water-soluble (Pyosol), water-insoluble (Pyoinsol) and synthetic (sPyo) pyomelanin variants and characterize their chemical structure, thermosensitivity and biosafety in vitro and in vivo (Galleria mallonella). FTIR analysis showed that aromatic ring connections in the polymer chains were dominant in Pyosol and sPyo, whereas Pyoinsol had fewer Car-Car links between rings. The differences in chemical structure influence the solubility of various forms of pyomelanins, their thermal stability and biological activity. Pyosol and Pyoinsol showed higher biological safety than sPyo. The obtained results qualify Pyosol and Pyoinsol for evaluation of their antimicrobial, immunomodulatory and proregenerative activities.
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Affiliation(s)
- Mateusz M Urbaniak
- Department of Immunology and Infectious Biology, Faculty of Biology and Environmental Protection, University of Łódź, 90-237 Łódź, Poland
- The Bio-Med-Chem Doctoral School, University of Lodz and Lodz Institutes of the Polish Academy of Sciences, 90-237 Łódź, Poland
| | - Małgorzata Gazińska
- Department of Engineering and Technology of Polymers, Faculty of Chemistry, Wrocław University of Science and Technology (WUST), 50-370 Wrocław, Poland
| | - Karolina Rudnicka
- Department of Immunology and Infectious Biology, Faculty of Biology and Environmental Protection, University of Łódź, 90-237 Łódź, Poland
| | - Przemysław Płociński
- Department of Immunology and Infectious Biology, Faculty of Biology and Environmental Protection, University of Łódź, 90-237 Łódź, Poland
| | - Monika Nowak
- Department of Immunology and Infectious Biology, Faculty of Biology and Environmental Protection, University of Łódź, 90-237 Łódź, Poland
| | - Magdalena Chmiela
- Department of Immunology and Infectious Biology, Faculty of Biology and Environmental Protection, University of Łódź, 90-237 Łódź, Poland
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12
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Maximo MF, Fill TP, Rodrigues ML. A Close Look into the Composition and Functions of Fungal Extracellular Vesicles Produced by Phytopathogens. Mol Plant Microbe Interact 2023; 36:228-234. [PMID: 36847651 DOI: 10.1094/mpmi-09-22-0184-fi] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Fungal extracellular vesicles (EVs) were first described in human pathogens. In a few years, the field of fungal EVs evolved to include several studies with plant pathogens, in which extracellularly released vesicles play fundamental biological roles. In recent years, solid progress has been made in the determination of the composition of EVs produced by phytopathogens. In addition, EV biomarkers are now known in fungal plant pathogens, and the production of EVs during plant infection has been demonstrated. In this manuscript, we review the recent progress in the field of fungal EVs, with a focus on plant pathogens. [Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 "No Rights Reserved" license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2023.
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Affiliation(s)
- Marina F Maximo
- Instituto de Química, Universidade de Campinas, São Paulo, Brazil
| | - Taícia P Fill
- Instituto de Química, Universidade de Campinas, São Paulo, Brazil
| | - Marcio L Rodrigues
- Instituto Carlos Chagas, Fundação Oswaldo Cruz (Fiocruz), Curitiba, Brazil
- Instituto de Microbiologia Paulo de Góes (IMPG), Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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13
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Aranda C, Méndez I, Barra PJ, Hernández-Montiel L, Fallard A, Tortella G, Briones E, Durán P. Melanin Induction Restores the Pathogenicity of Gaeumannomyces graminis var. tritici in Wheat Plants. J Fungi (Basel) 2023; 9:jof9030350. [PMID: 36983518 PMCID: PMC10058861 DOI: 10.3390/jof9030350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 03/02/2023] [Accepted: 03/03/2023] [Indexed: 03/18/2023] Open
Abstract
One of the most challenging aspects of long-term research based on microorganisms is the maintenance of isolates under ex situ conditions, particularly the conservation of phytopathological characteristics. Our research group has worked for more than 10 years with Gaumannomyces graminis var. tritici (Ggt), the main biotic factor affecting wheat. In this sense we preserved the microorganisms in oil overlaid. However, several strains preserved for a long time lost their pathogenicity. These strains show white and non-infective mycelia. In this sense, we hypothesized that this is attributable to low melanin content. Melanin is a natural pigment mainly involved in UV protection, desiccation, salinity, oxidation, and fungal pathogenicity. Therefore, understanding the melanin role on Ggt pathogenicity is fundamental to developing melanin activation strategies under laboratory studies. In this study, we induce melanin activation by UV-A light chamber, 320 to 400 nm (T1) and temperature changes of 30 °C, 15 °C, and 20 °C (T2). Fungal pathogenicity was evaluated by determination of blackening roots and Ggt was quantified by real-time PCR in inoculated wheat plants. Results revealed that Ggt grown under UV-A (T1) conditions showed around 40% higher melanin level with a concomitant effect on root infection (98% of blackened roots) and 4-fold more Ggt genome copy number compared with the control (non-infective mycelia) being T1, a more inductor factor compared with T2. These findings would support the role of melanin in pathogenicity in darkly pigmented fungi such as Ggt and could serve as a basis for activating pathogenicity under laboratory conditions.
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Affiliation(s)
- Camila Aranda
- Programa de Doctorado en Ciencias de Recursos Naturales, Universidad de La Frontera, Temuco 4811230, Chile
- Biocontrol Research Laboratory, Universidad de La Frontera, Temuco 4811230, Chile
| | - Isabel Méndez
- Programa de Doctorado en Ciencias de Recursos Naturales, Universidad de La Frontera, Temuco 4811230, Chile
- Biocontrol Research Laboratory, Universidad de La Frontera, Temuco 4811230, Chile
| | - Patricio Javier Barra
- Biocontrol Research Laboratory, Universidad de La Frontera, Temuco 4811230, Chile
- Scientific and Technological Bioresource Nucleus, Universidad de La Frontera, Temuco 4811230, Chile
| | - Luis Hernández-Montiel
- Nanotechnology and Microbial Biocontrol Group, Centro de Investigaciones Biológicas del Noroeste, Av. Politécnico Nacional 195, Col. Playa Palo de Santa Rita Sur, La Paz 23090, Mexico
| | - Ana Fallard
- Biocontrol Research Laboratory, Universidad de La Frontera, Temuco 4811230, Chile
| | - Gonzalo Tortella
- Scientific and Technological Bioresource Nucleus, Universidad de La Frontera, Temuco 4811230, Chile
| | - Evelyn Briones
- Biocontrol Research Laboratory, Universidad de La Frontera, Temuco 4811230, Chile
| | - Paola Durán
- Biocontrol Research Laboratory, Universidad de La Frontera, Temuco 4811230, Chile
- Scientific and Technological Bioresource Nucleus, Universidad de La Frontera, Temuco 4811230, Chile
- Facultad de Ciencias Agropecuarias y Medioambiente, Departamento de Producción Agropecuaria, Universidad de La Frontera, Temuco 4811230, Chile
- Correspondence:
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14
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Faccin M, Rodrigues Hoffmann A. Paraconiothyrium cyclothyrioides, a novel cutaneous fungal pathogen in a dog and a cat. Vet Dermatol 2023. [PMID: 36919229 DOI: 10.1111/vde.13155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 01/31/2023] [Accepted: 02/03/2023] [Indexed: 03/16/2023]
Abstract
A dog and a cat presented with pyogranulomatous mycotic pododermatitis. Panfungal PCR and next-generation sequencing identified Paraconiothyrium cyclothyrioides with 100% identity. Paraconiothyrium cyclothyrioides can rarely cause cutaneous infection and systemic disease in immunocompromised humans. This is the first report of infections in domestic animal species.
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Affiliation(s)
- Mayane Faccin
- Department of Veterinary Pathobiology, School of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, USA
| | - Aline Rodrigues Hoffmann
- Department of Comparative, Diagnostic, and Population Medicine, College of Veterinary Medicine, University of Florida, Gainesville, Florida, USA
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15
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Chen Q, Liu F, Wu Y, He Y, Kong Q, Sang H. Fungal melanin-induced metabolic reprogramming in macrophages is crucial for inflammation. J Mycol Med 2023; 33:101359. [PMID: 36701872 DOI: 10.1016/j.mycmed.2023.101359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Revised: 11/18/2022] [Accepted: 01/11/2023] [Indexed: 01/18/2023]
Abstract
The overuse of antifungal and immunosuppressant drugs and the higher frequency of organ transplantation has resulted in mycosis being increasingly intractable, and there is a great need for the development of new therapies. Melanin is an important virulence factor that can inhibit the inflammatory response in the host and facilitate fungal survival by several methods. However, a recent study showed that the Akt/mTOR/HIF1α axis in macrophages was activated after melanin-binding proteins recognised the DHN melanin of Aspergillus fumigatus, with a resulting metabolic shift towards glycolysis (i.e., metabolic reprogramming). As a result, antimicrobial compounds (e.g., inflammatory mediators and reactive oxygen species) were increased to fight the fungal invasion. Actually, DHN melanin from other fungi and DOPA melanin can induce inflammation and stimulate the production of melanin-binding antibodies. In addition, DOPA melanin contains conserved repeating units that are similar to those of DHN melanin. Therefore, we evaluated the associated evidence to propose an interesting and reasonable hypothesis that melanin promotes inflammation by metabolic reprogramming, which could provide a research direction for antifungal therapy. It suggests that regulating the metabolism of immune cells can guide the inflammatory response against fungi, despite the presence of immunosuppressant melanin. Since the biochemical molecules of glycolysis are clearly described, regulating glycolysis in macrophages may be easier than inventing new antifungal drugs. Further clarification of our hypothesis may strengthen the candidacy of melanin for future antifungal vaccines.
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Affiliation(s)
- Qiying Chen
- Department of Dermatology, Nanjing Jinling Hospital, The First School of Clinical Medicine, Southern Medical University, Guangzhou, Guangdong Province 510080, China
| | - Fang Liu
- Department of Dermatology, Nanjing Jinling Hospital, Nanjing, Jiangsu Province 210002, China
| | - Yifan Wu
- Department of Dermatology, Nanjing Medical University, Nanjing, Jiangsu Province 210002, China
| | - Yifan He
- Department of Dermatology, Nanjing Medical University, Nanjing, Jiangsu Province 210002, China
| | - Qingtao Kong
- Department of Dermatology, Nanjing Jinling Hospital, Nanjing, Jiangsu Province 210002, China.
| | - Hong Sang
- Department of Dermatology, Nanjing Jinling Hospital, The First School of Clinical Medicine, Southern Medical University, Guangzhou, Guangdong Province 510080, China; Department of Dermatology, Nanjing Jinling Hospital, Nanjing, Jiangsu Province 210002, China.
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16
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Ban Y, Tan J, Xiong Y, Mo X, Li W, Jia C, Ding Y, Xu Z. The responses and detoxification mechanisms of dark septate endophytes (DSE), Exophiala salmonis, to CuO nanoparticles. Environ Sci Pollut Res Int 2023; 30:13773-13787. [PMID: 36149553 DOI: 10.1007/s11356-022-23099-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 09/14/2022] [Indexed: 06/16/2023]
Abstract
To understand the tolerance mechanisms of dark septate endophytes (DSE), Exophiala salmonis, to CuO nanoparticles (CuO-NPs) with different sizes (40 and 150 nm), we investigated the morphology, antioxidant response, Cu subcellular distribution, and the melanin gene expression in the mycelia of E. salmonis. E. salmonis was cultured in liquid and solid media under the stress of increasing CuO-NP concentrations (0, 50, 100, 150, and 250 mg/L). Results showed that (1) E. salmonis showed good CuO-NP tolerance, and the tolerance to CuO-NPs at 150 nm was stronger than that at 40 nm. A large number of agglomeration structures were observed on the mycelia surface with the exception of 50 mg/L CuO-NPs with a diameter of 150 nm. (2) CuO-NP stress significantly stimulated the production of antioxidant enzymes, particularly the CuO-NPs with small particle size (40 nm). (3) Cu uptaken by E. salmonis increased proportionally with the increase of CuO-NP concentration in the medium. More than 80% Cu was absorbed in cell wall of mycelia treated with a small particle size (40 nm). (4) FTIR analysis revealed that hydroxyl, amine, carboxyl, and phosphate groups were associated with CuO-NP binding regardless of particle size. (5) Fungal melanin content increased with the addition of CuO-NPs; the increase of melanin induced by CuO-NPs with small particle size (40 nm) was more significant. (6) The expression of 1,3,6,8-tetrahydroxynaphthalene reductase (Arp2) in the melanin synthesis pathway increased under the stress of CuO-NPs, and CuO-NPs with a small particle size (40 nm) caused a significant change in the expression level of Arp2 gene than those with a large particle size (150 nm). In conclusion, E. salmonis had a strong tolerance to CuO-NPs and mitigated the toxic effects of CuO-NPs through the antioxidant system, the expression of genes related to melanin synthesis, and the synthesis of melanin.
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Affiliation(s)
- Yihui Ban
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan, 430070, Hubei, China
| | - Jiayuan Tan
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan, 430070, Hubei, China
| | - Yang Xiong
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan, 430070, Hubei, China
| | - Xiantong Mo
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan, 430070, Hubei, China
| | - Wenxuan Li
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan, 430070, Hubei, China
| | - Chenyue Jia
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan, 430070, Hubei, China
| | - Yiwen Ding
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan, 430070, Hubei, China
| | - Zhouying Xu
- School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan, 430070, Hubei, China.
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17
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Alonso MF, Bain JM, Rudkin FM, Erwig LP, Brown AJ, Gow NA. The nature of the fungal cargo induces significantly different temporal programmes of macrophage phagocytosis. Cell Surf 2022; 8:100082. [PMID: 36299405 PMCID: PMC9589029 DOI: 10.1016/j.tcsw.2022.100082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Revised: 10/12/2022] [Accepted: 10/12/2022] [Indexed: 11/05/2022] Open
Abstract
Phagocytosis is an essential component of our immune defence against fungal pathogens. Differences in the dynamics of phagocyte migration, recognition, uptake and phagolysosome maturation are dependent on the characteristics of the fungal cargo, and in particular to differences in cell wall composition and cellular morphology. However, studies that have focused on phagocyte interactions with individual fungal species have not enabled comparisons in the kinetics of these interactions to be made between these different species. We therefore used live cell video microscopy to examine the temporal dynamics of phagocytosis for a range of fungal cargoes by thioglycollate-elicited peritoneal macrophages from C57BL/6 mice. Uniform populations of macrophages were challenged at the same time with yeast cells of Candida albicans, Candida glabrata, Saccharomyces cerevisiae and Cryptococcus neoformans (wild-type and an acapsular mutant, cap59Δ), and spores of Aspergillus fumigatus and Mucor circinelloides to enable standardized comparative interactions to be quantified from different stages of phagocytosis. Differences in the rate of uptake of fungal cells varied by up to 26-fold, whilst differences in time to induce phagosome acidification varied by as much as 29-fold. Heat-killing or opsonizing the fungal targets markedly affected the kinetics of the interaction in a species-specific manner. Fungal and macrophage killing assays further revealed cargo-specific differences in phagocytosis and diversity in fungal evasion mechanisms. Therefore, simultaneous assessment of the interaction of macrophages with different fungal pathogens highlighted major differences in the kinetics and growth responses during fungus-phagocyte interactions that are likely to impact on pathogenesis and virulence.
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Affiliation(s)
- María Fernanda Alonso
- The Aberdeen Fungal Group, School of Medicine, Medical Sciences & Nutrition, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Judith M. Bain
- The Aberdeen Fungal Group, School of Medicine, Medical Sciences & Nutrition, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Fiona M. Rudkin
- The Aberdeen Fungal Group, School of Medicine, Medical Sciences & Nutrition, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Lars P. Erwig
- The Aberdeen Fungal Group, School of Medicine, Medical Sciences & Nutrition, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Alistair J.P. Brown
- The Aberdeen Fungal Group, School of Medicine, Medical Sciences & Nutrition, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
- Medical Research Council Centre for Medical Mycology, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter EX4 4QD, UK
| | - Neil A.R. Gow
- The Aberdeen Fungal Group, School of Medicine, Medical Sciences & Nutrition, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
- Medical Research Council Centre for Medical Mycology, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter EX4 4QD, UK
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18
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Smith DFQ, Mudrak NJ, Zamith-Miranda D, Honorato L, Nimrichter L, Chrissian C, Smith B, Gerfen G, Stark RE, Nosanchuk JD, Casadevall A. Melanization of Candida auris Is Associated with Alteration of Extracellular pH. J Fungi (Basel) 2022; 8:jof8101068. [PMID: 36294632 PMCID: PMC9604884 DOI: 10.3390/jof8101068] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 10/05/2022] [Accepted: 10/07/2022] [Indexed: 11/29/2022] Open
Abstract
Candida auris is a recently emerged global fungal pathogen, which causes life-threatening infections, often in healthcare settings. C. auris infections are worrisome because the fungus is often resistant to multiple antifungal drug classes. Furthermore, C. auris forms durable and difficult to remove biofilms. Due to the relatively recent, resilient, and resistant nature of C. auris, we investigated whether it produces the common fungal virulence factor melanin. Melanin is a black-brown pigment typically produced following enzymatic oxidation of aromatic precursors, which promotes fungal virulence through oxidative stress resistance, mammalian immune response evasion, and antifungal peptide and pharmaceutical inactivation. We found that certain strains of C. auris oxidized L-DOPA and catecholamines into melanin. Melanization occurred extracellularly in a process mediated by alkalinization of the extracellular environment, resulting in granule-like structures that adhere to the fungus’ external surface. C. auris had relatively high cell surface hydrophobicity, but there was no correlation between hydrophobicity and melanization. Melanin protected the fungus from oxidative damage, but we did not observe a protective role during infection of macrophages or Galleria mellonella larvae. In summary, C. auris alkalinizes the extracellular medium, which promotes the non-enzymatic oxidation of L-DOPA to melanin that attaches to its surface, thus illustrating a novel mechanism for fungal melanization.
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Affiliation(s)
- Daniel F. Q. Smith
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Nathan J. Mudrak
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
- Krieger School of Arts & Science, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Daniel Zamith-Miranda
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA
- Division of Infectious Diseases, Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA
| | - Leandro Honorato
- Laboratório de Glicobiologia de Eucariotos, Departamento de Microbiologia Geral, Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-901, Brazil
| | - Leonardo Nimrichter
- Laboratório de Glicobiologia de Eucariotos, Departamento de Microbiologia Geral, Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-901, Brazil
| | - Christine Chrissian
- Department of Chemistry and Biochemistry, City College of New York and CUNY Institute for Macromolecular Assemblies, The City University of New York, New York, NY 10031, USA
| | - Barbara Smith
- Institute for Basic Biomedical Sciences Microscope Facility, The Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
| | - Gary Gerfen
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA
| | - Ruth E. Stark
- Department of Chemistry and Biochemistry, City College of New York and CUNY Institute for Macromolecular Assemblies, The City University of New York, New York, NY 10031, USA
| | - Joshua D. Nosanchuk
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA
- Division of Infectious Diseases, Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA
- Correspondence: (J.D.N.); (A.C.)
| | - Arturo Casadevall
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
- Correspondence: (J.D.N.); (A.C.)
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19
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Pruksaphon K, Nosanchuk JD, Thammasit P, Pongpom M, Youngchim S. Interaction of Talaromyces marneffei with free living soil amoeba as a model of fungal pathogenesis. Front Cell Infect Microbiol 2022; 12:1023067. [PMID: 36262181 PMCID: PMC9574045 DOI: 10.3389/fcimb.2022.1023067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 09/20/2022] [Indexed: 11/13/2022] Open
Abstract
Talaromyces (Penicillium) marneffei is an important dimorphic mycosis endemic in Southeast Asia and Southern China, but the origin and maintenance of virulence traits in this organism remains obscure. Several pathogenic fungi, including Cryptococcus neoformans, Aspergillus fumigatus, Blastomyces dermatitidis, Sporothrix schenckii, Histoplasma capsulatum and Paracoccidioides spp. interact with free living soil amoebae and data suggests that fungal pathogenic strategies may emerge from environmental interactions of these fungi with ubiquitous phagocytic microorganisms. In this study, we examined the interactions of T. marneffei with the soil amoeba Acanthamoeba castellanii. T. marneffei was rapidly ingested by A. castellanii and phagocytosis of fungal cells resulted in amoeba death after 24 h of contact. Co-culture also resulted in a rapid transition for conidia to the fission-yeast form. In addition, well-established virulence factors such as melanin and a yeast specific mannoprotein of T. marneffei were expressed during interaction with A. castellanii at 37°C. Our findings support the assumption that soil amoebae environmental predators play a role in the selection and maintenance of particular features in T. marneffei that impart virulence to this clinically important dimorphic fungus in mammalian hosts.
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Affiliation(s)
- Kritsada Pruksaphon
- Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Joshua D. Nosanchuk
- Departments of Microbiology and Immunology and Medicine, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Patcharin Thammasit
- Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Monsicha Pongpom
- Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Sirida Youngchim
- Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
- *Correspondence: Sirida Youngchim,
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Pereira JAL, de Moraes LS, de Sena CBC, do Nascimento JLM, Rodrigues APD, da Silva SHM, Silva EO. Inhibition of Melanization by Kojic Acid Promotes Cell Wall Disruption of the Human Pathogenic Fungus Fonsecaea sp. Pathogens 2022; 11:pathogens11080925. [PMID: 36015045 PMCID: PMC9414132 DOI: 10.3390/pathogens11080925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 08/05/2022] [Accepted: 08/11/2022] [Indexed: 11/16/2022] Open
Abstract
Chromoblastomycosis (CBM) is a chronic human subcutaneous mycosis caused by various aetiologic agents. CBM does not have an established treatment but may be managed using antifungal agents, surgical removal of the lesions, or cryotherapy. Kojic acid (KA), a known tyrosinase inhibitor with a variety of biological actions, including fungistatic action against the fungus Cryptococcus neoformans, mediated by inhibiting melanin production, seems to be an alternative to improve the treatment of CBM. The aim of the present study was to analyze the action of KA against the pathogenic fungus Fonsecaea sp., an aetiological agent of CBM. The fungal culture was incubated with KA, and the amount of melanin was assessed, followed by cytochemical detection. Subsequently, the samples were analyzed by light microscopy, transmission and scanning electron microscopy. Culture analysis revealed that 100 g/mL KA significantly decreased the melanization of the fungus and the exocytosis of melanin into the culture supernatant. Additionally, KA induced less growth of biofilm formation and intense disruption of the cell wall, and decreased the number of melanin-containing vesicles in the culture supernatant. Finally, KA inhibited fungal filamentation in culture and the subsequent phagocytosis process. Thus, KA may be a promising substance to help in the treatment of CBM.
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Affiliation(s)
- Jorge Augusto Leão Pereira
- Laboratory of Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém 66075-110, PA, Brazil
| | - Lienne Silveira de Moraes
- Laboratory of Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém 66075-110, PA, Brazil
- National Institute of Science and Technology in Structural Biology and Bioimaging, Rio de Janeiro 21040-900, RJ, Brazil
- Pharmaceutical Sciences Post Graduation Program, Health and Biological Sciences Department, Federal University of Amapa (UNIFAP), Macapá 68903-329, AP, Brazil
| | - Chubert Bernardo Castro de Sena
- Laboratory of Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém 66075-110, PA, Brazil
- National Institute of Science and Technology in Neuroimmunomodulation (INCT—NIM), Rio de Janeiro 21040-900, RJ, Brazil
| | - José Luiz Martins do Nascimento
- Pharmaceutical Sciences Post Graduation Program, Health and Biological Sciences Department, Federal University of Amapa (UNIFAP), Macapá 68903-329, AP, Brazil
- National Institute of Science and Technology in Neuroimmunomodulation (INCT—NIM), Rio de Janeiro 21040-900, RJ, Brazil
- Laboratory of Molecular and Cellular Neurochemistry, Institute of Biological Sciences, Federal University of Pará, Belém 66075-110, PA, Brazil
| | - Ana Paula D. Rodrigues
- National Institute of Science and Technology in Structural Biology and Bioimaging, Rio de Janeiro 21040-900, RJ, Brazil
- Laboratory of Electron Microscopy, Evandro Chagas Institute, Ministry of Health, Belém 66093-020, PA, Brazil
| | - Silvia Helena Marques da Silva
- Laboratory of Superficial and Systemic Mycoses, Evandro Chagas Institute, Department of Mycology and Bacteriology, Ministry of Health, Ananindeua 67030-000, PA, Brazil
| | - Edilene O. Silva
- Laboratory of Structural Biology, Institute of Biological Sciences, Federal University of Pará, Belém 66075-110, PA, Brazil
- National Institute of Science and Technology in Structural Biology and Bioimaging, Rio de Janeiro 21040-900, RJ, Brazil
- Correspondence: ; Tel.: +055-9132-0175-46
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Vercellino L, de Jong D, Dercle L, Hosten B, Braumuller B, Das JP, Deng A, Moya-plana A, A’keen C, Yeh R, Merlet P, Baroudjian B, Salvatore MM, Capaccione KM. Translating Molecules into Imaging—The Development of New PET Tracers for Patients with Melanoma. Diagnostics (Basel) 2022; 12:1116. [PMID: 35626272 PMCID: PMC9139963 DOI: 10.3390/diagnostics12051116] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 04/22/2022] [Accepted: 04/27/2022] [Indexed: 01/27/2023] Open
Abstract
Melanoma is a deadly disease that often exhibits relentless progression and can have both early and late metastases. Recent advances in immunotherapy and targeted therapy have dramatically increased patient survival for patients with melanoma. Similar advances in molecular targeted PET imaging can identify molecular pathways that promote disease progression and therefore offer physiological information. Thus, they can be used to assess prognosis, tumor heterogeneity, and identify instances of treatment failure. Numerous agents tested preclinically and clinically demonstrate promising results with high tumor-to-background ratios in both primary and metastatic melanoma tumors. Here, we detail the development and testing of multiple molecular targeted PET-imaging agents, including agents for general oncological imaging and those specifically for PET imaging of melanoma. Of the numerous radiopharmaceuticals evaluated for this purpose, several have made it to clinical trials and showed promising results. Ultimately, these agents may become the standard of care for melanoma imaging if they are able to demonstrate micrometastatic disease and thus provide more accurate information for staging. Furthermore, these agents provide a more accurate way to monitor response to therapy. Patients will be able to receive treatment based on tumor uptake characteristics and may be able to be treated earlier for lesions that with traditional imaging would be subclinical, overall leading to improved outcomes for patients.
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Azam F, Khan MA, Khan A, Ahmad S, Zofair SFF, Younus H. In silico and in vitro studies on the inhibition of laccase activity by Ellagic acid: Implications in drug designing for the treatment of Cryptococcal infections. Int J Biol Macromol 2022; 209:642-54. [PMID: 35421416 DOI: 10.1016/j.ijbiomac.2022.04.060] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 03/30/2022] [Accepted: 04/08/2022] [Indexed: 01/14/2023]
Abstract
In recent years, the increased frequency of drug-resistant strains of Cryptococcus neoformans has depleted our antifungal armory. In the present study, we investigated the inhibitory potential of ellagic acid (EA) against C. neoformans laccase through in silico and in vitro studies. For the first time, a homology modelling was established to model laccase and modelled protein served as a receptor for docking EA. Thermodynamic stability of the docked complex was ascertained by molecular dynamics simulation (MD). The analysis of root mean square deviation and fluctuation of alpha carbons of protein justifies the stability of the bound EA in the binding pocket of laccase. Frontier molecular orbitals of the EA was studied by density functional theory-based optimization by using the Lee-Yang-Parr correlation functional (B3LYP) approach. Negative values of the highest occupied/unoccupied molecular orbitals (HOMO/LUMO) indicated that laccase with EA forms a stable complex. Interestingly, EA inhibited laccase activity both in vitro and in yeast cells of C. neoformans. Moreover, EA treatment remarkably inhibited the proliferation of C. neoformans inside macrophages. The findings of the present study unveil the molecular basis of the interactions of laccase with EA, which may prove to be beneficial for designing laccase inhibitors as potential anti-cryptococcal agents.
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Ogórek R, Borzęcka J, Kłosińska K, Piecuch A, Przymencki M, Litwiniak K, Suchodolski J. A Culture-Based Study of Micromycetes Isolated from the Urban Nests of Grey Heron (Ardea cinerea) in SW Poland. Animals (Basel) 2022; 12:676. [PMID: 35327074 PMCID: PMC8944552 DOI: 10.3390/ani12060676] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 03/04/2022] [Accepted: 03/06/2022] [Indexed: 12/14/2022] Open
Abstract
Simple Summary Fungi inhabiting bird nests may pose a serious threat to living organisms. Therefore, the main goal of the study was to identify cultivable fungi in the nest of grey heron (Ardea cinerea) located near the city centre of Wrocław (Poland). Overall, 10 different fungal species were obtained which were both cosmopolitan and potentially hazardous to humans, homoiothermous animals and plants. The greatest number of fungal species was obtained from the nest fragments with visible fungal growth, and the least from western conifer seed bugs (Leptoglossus occidentalis) inhabiting the nests. The damp chamber allowed isolation of Aspergillus fumigatus, Penicillium coprophilum, and P. griseofulvum as directly related to the occurrence of visible fungal growth on plant fragments of grey heron nests. Abstract There are many positive relationships between micromycetes and birds: They can spread fungal spores, and fungi facilitate cavity woodpecker excavation by preparing and modifying excavation sites. In turn, bird nests are mainly a source of potentially zoopathogenic fungi. The Wrocław city centre hosts the biggest grey heron breeding colony in Poland with at least 240 breeding birds pairs. To assess the possible public health risks associated with bird nests, the goal of the present study was to identify cultivable fungi present in the nests of grey herons (Ardea cinerea) in Wrocław. Additionally, attempts were made to determine whether the obtained species of fungi may pose a potential threat to animal health. Fungi were cultured at 23 and 37 ± 0.5 °C, and identified based on phenotypic and genotypic traits. Moreover, during routine inspection, visible fungal growth in some of the nests was found. Overall, 10 different fungal species were obtained in the study (Alternaria alternata, Aspergillus fumigatus, Botryotrichum piluliferum, Cladosporium cladosporioides, Epicoccum layuense, Mucor circinelloides, M.hiemalis, Penicillium atramentosum, P.coprophilum, and P.griseofulvum). They are both cosmopolitan species and a source of potential threat to humans, homoiothermous animals and plants. The greatest number of fungal species was obtained from the nest fragments with visible fungal growth incubated at 23 °C, and the least from western conifer seed bugs (Leptoglossus occidentalis) inhabiting the nests. The species such as A. fumigatus, P. coprophilum, and P.griseofulvum can be directly related to the occurrence of visible fungal growth on plant fragments of grey heron’s nests.
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Pruksaphon K, Nosanchuk JD, Ratanabanangkoon K, Youngchim S. Talaromyces marneffei Infection: Virulence, Intracellular Lifestyle and Host Defense Mechanisms. J Fungi (Basel) 2022; 8:200. [PMID: 35205954 PMCID: PMC8880324 DOI: 10.3390/jof8020200] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 02/14/2022] [Accepted: 02/18/2022] [Indexed: 12/02/2022] Open
Abstract
Talaromycosis (Penicilliosis) is an opportunistic mycosis caused by the thermally dimorphic fungus Talaromyces (Penicillium) marneffei. Similar to other major causes of systemic mycoses, the extent of disease and outcomes are the results of complex interactions between this opportunistic human pathogen and a host’s immune response. This review will highlight the current knowledge regarding the dynamic interaction between T. marneffei and mammalian hosts, particularly highlighting important aspects of virulence factors, intracellular lifestyle and the mechanisms of immune defense as well as the strategies of the pathogen for manipulating and evading host immune cells.
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Chongkae S, Youngchim S, Nosanchuk JD, Laliam A, Tangmonkongvoragul C, Pruksaphon K. Fungal Keratitis in Northern Thailand: Spectrum of Agents, Risk Factors and Putative Virulence Factors. J Fungi (Basel) 2021; 7:475. [PMID: 34208353 DOI: 10.3390/jof7060475] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 06/04/2021] [Accepted: 06/09/2021] [Indexed: 01/09/2023] Open
Abstract
Fungal keratitis (FK) is a serious ocular infection that can result in various degrees of vision loss, including blindness. The aim of the study was to identify and retrospectively review all FK cases diagnosed between August 2012 and December 2020 at a tertiary care hospital in northern Thailand with a specific focus on epidemiologic features, including season, patient sex and age, the spectrum of pathogens, and presence of certain putative virulence factors. Of 1237 patients with corneal ulcers, 294 (23.8%) were confirmed by direct microscopic examination and/or fungal culture. For the positive cases, direct examinations of Calcofluor white (CW) stains and KOH mounts were found in 97.3% (286/294) and 76.5% (225/294), respectively (p < 0.05). Of the cases diagnosed by microscopy and culture, fungi were isolated in 152 (51.7%), with Fusarium spp. being the most frequently identified (n = 69, 45.5%) followed by dematiaceous fungi (n = 45, 29.6%) and Aspergillus spp. (n = 18, 11.8%). The incidence of FK was higher in the rainy season of July to October. The mean age was 54.4 ± 14.4 (SD) years, with a range of 9–88 years. Males (75.8%) were affected significantly more than females (24.2%) (p < 0.05). Of 294 patients, 132 (44.9%) were middle-aged adults (41–60 years) and 107 (36.4%) were older than 60 years. Trauma to the eye by soil or vegetative matter were the most common preceding factors (188/294; 64.0%). We assessed two virulence factors. First, 142 of the 152 culture-positive FK cases were due to molds, indicating that hyphal morphogenesis is extremely important in disease. We also demonstrated that fungal melanization occurs in the molds during the course of FK by applying a melanin-specific monoclonal antibody (MAb) that labeled fungal elements in corneal samples of patients, and melanin particles derived from the hyphae were also recovered after treatment of the samples with proteolytic enzymes, denaturant and hot concentrated acid. In summary, we demonstrate that northern Thailand has a high rate of FK that is influenced by season and males engaged in outside activities are at highest risk for disease. Moulds are significantly more commonly responsible for FK, in part due to their capacity to form hyphae and melanins. Future studies will examine models of fungal corneal interactions and assess additional factors of virulence, such as secreted enzymes, to more deeply decipher the pathogenesis of FK.
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