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Liu S, Le Mauff F, Sheppard DC, Zhang S. Filamentous fungal biofilms: Conserved and unique aspects of extracellular matrix composition, mechanisms of drug resistance and regulatory networks in Aspergillus fumigatus. NPJ Biofilms Microbiomes 2022; 8:83. [PMID: 36261442 PMCID: PMC9581972 DOI: 10.1038/s41522-022-00347-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 10/04/2022] [Indexed: 11/09/2022] Open
Abstract
The filamentous fungus Aspergillus fumigatus is an ubiquitous mold that can cause invasive pulmonary infections in immunocompromised patients. Within the lung, A. fumigatus forms biofilms that can enhance resistance to antifungals and immune defenses, highlighting the importance of defining the mechanisms underlying biofilm development and associated emergent properties. A. fumigatus biofilms display a morphology and architecture that is distinct from bacterial and yeast biofilms. Moreover, A. fumigatus biofilms display unique characteristics in the composition of their extracellular matrix (ECM) and the regulatory networks governing biofilm formation. This review will discuss our current understanding of the form and function of A. fumigatus biofilms, including the unique components of ECM matrix, potential drug resistance mechanisms, the regulatory networks governing A. fumigatus biofilm formation, and potential therapeutics targeting these structures.
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Affiliation(s)
- Shuai Liu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Microbiology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Francois Le Mauff
- Department of Microbiology and Immunology, Faculty of Medicine, McGill University, Montreal, QC, Canada.,Infectious Disease and Immunity in Global Health, Research Institute of McGill University Health Center, Montreal, QC, Canada.,McGill Interdisciplinary Initiative in Infection and Immunity, Montreal, QC, Canada
| | - Donald C Sheppard
- Department of Microbiology and Immunology, Faculty of Medicine, McGill University, Montreal, QC, Canada. .,Infectious Disease and Immunity in Global Health, Research Institute of McGill University Health Center, Montreal, QC, Canada. .,McGill Interdisciplinary Initiative in Infection and Immunity, Montreal, QC, Canada.
| | - Shizhu Zhang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Microbiology, College of Life Sciences, Nanjing Normal University, Nanjing, China.
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Two Monoclonal Antibodies That Specifically Recognize Aspergillus Cell Wall Antigens and Can Detect Circulating Antigens in Infected Mice. Int J Mol Sci 2021; 23:ijms23010252. [PMID: 35008678 PMCID: PMC8745570 DOI: 10.3390/ijms23010252] [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] [Received: 12/01/2021] [Revised: 12/16/2021] [Accepted: 12/19/2021] [Indexed: 01/25/2023] Open
Abstract
Invasive aspergillosis (IA) is a life-threatening disease mainly caused by Aspergillus fumigatus and Aspergillus flavus. Early diagnosis of this condition is crucial for patient treatment and survival. As current diagnostic techniques for IA lack sufficient accuracy, we have raised two monoclonal antibodies (1D2 and 4E4) against A. fumigatus cell wall fragments that may provide a platform for a new diagnostic approach. The immunoreactivity of these antibodies was tested by immunofluorescence and ELISA against various Aspergillus and Candida species in vitro and by immunohistochemistry in A. fumigatus infected mouse tissues. Both monoclonal antibodies (mAbs) showed intensive fluorescence with the hyphae wall of A. fumigatus and A. flavus, but there was no staining with other Aspergillus species or Candida species. Both mAbs also showed strong immunoreactivity to the cell wall of A. fumigatus hyphae in the infected liver, spleen and kidney of mice with IA. The antigens identified by 1D2 and 4E4 might be glycoproteins and the epitopes are most likely a protein or peptide rather than a carbohydrate. An antibody-based antigen capture ELISA detected the extracellular antigens released by A. fumigatus, A. flavus, A. niger and A. terreus, but not in Candida species. The antigen could be detected in the plasma of mice after 48 h of infection by double-sandwich ELISA. In conclusion, both 1D2 and 4E4 mAbs are potentially promising diagnostic tools to investigate invasive aspergillosis.
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Mei L, Wang X, Yin Y, Tang G, Wang C. Conservative production of galactosaminogalactan in Metarhizium is responsible for appressorium mucilage production and topical infection of insect hosts. PLoS Pathog 2021; 17:e1009656. [PMID: 34125872 PMCID: PMC8224951 DOI: 10.1371/journal.ppat.1009656] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 06/24/2021] [Accepted: 05/20/2021] [Indexed: 02/07/2023] Open
Abstract
The exopolysaccharide galactosaminogalactan (GAG) has been well characterized in Aspergilli, especially the human pathogen Aspergillus fumigatus. It has been found that a five-gene cluster is responsible for GAG biosynthesis in Aspergilli to mediate fungal adherence, biofilm formation, immunosuppression or induction of host immune defences. Herein, we report the presence of the conserved GAG biosynthetic gene cluster in the insect pathogenic fungus Metarhizium robertsii to mediate either similar or unique biological functions. Deletion of the gene cluster disabled fungal ability to produce GAG on germ tubes, mycelia and appressoria. Relative to the wild type strain, null mutant was impaired in topical infection but not injection of insect hosts. We found that GAG production by Metarhizium is partially acetylated and could mediate fungal adherence to hydrophobic insect cuticles, biofilm formation, and penetration of insect cuticles. In particular, it was first confirmed that this exopolymer is responsible for the formation of appressorium mucilage, the essential extracellular matrix formed along with the infection structure differentiation to mediate cell attachment and expression of cuticle degrading enzymes. In contrast to its production during A. fumigatus invasive growth, GAG is not produced on the Metarhizium cells harvested from insect hemocoels; however, the polymer can glue germ tubes into aggregates to form mycelium pellets in liquid culture. The results of this study unravel the biosynthesis and unique function of GAG in a fungal system apart from the aspergilli species.
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Affiliation(s)
- Lijuan Mei
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Xuewen Wang
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Ying Yin
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Guirong Tang
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Chengshu Wang
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- * E-mail:
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Dysregulation of Key Proteinases in Aspergillus fumigatus Induced by Blood Platelets. Rep Biochem Mol Biol 2021; 10:95-104. [PMID: 34277873 DOI: 10.52547/rbmb.10.1.95] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 12/13/2020] [Indexed: 11/18/2022]
Abstract
Background Aspergillus fumigatus is the most common species causing invasive aspergillosis (IA), a life-threatening infection with more than 80% mortality. Interactions between A. fumigatus and human blood platelets lead to intravascular thrombosis and localized infarcts. To better understand A. fumigatus pathogenesis, we aimed to analyze the genetic basis of interactions between the pathogen and blood platelets. Methods A bioinformatic pipeline on microarray gene expression dataset, including analysis of differentially expressed genes (DEGs) using Limma R package and their molecular function, as well as biological pathways identification, was conducted to find the effective genes involved in IA. In the wet phase, the gene expression patterns following fungal exposure to blood platelets at 15, 30, 60, and 180 min were evaluated by quantitative reverse transcriptase-PCR analysis. Results Three genes encoding aspartic endopeptidases including (Pep1), (Asp f 13), and (β-glucanase) were the standing candidates. The invasion-promoting fungal proteinase-encoding genes were down-regulated after 30 min of hyphal incubation with blood platelets, and then up-regulated at 60 and 180 min, although only Pep1 was greater than the control at the 60and 180 min time points. Also, the same genes were downregulated in more the clinical isolates relative to the standard strain CBS 144.89. Conclusion Our findings delineate the possible induction of fungal-encoded proteinases by blood platelets. This provides a new research line into A. fumigatus' molecular pathogenesis. Such insight into IA pathogenesis might also guide researchers toward novel platelet-based therapies that involve molecular interventions, especially in IA patients.
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Ogwugwa VH, Oyetibo GO, Amund OO. Taxonomic profiling of bacteria and fungi in freshwater sewer receiving hospital wastewater. ENVIRONMENTAL RESEARCH 2021; 192:110319. [PMID: 33069702 DOI: 10.1016/j.envres.2020.110319] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 10/04/2020] [Accepted: 10/06/2020] [Indexed: 06/11/2023]
Abstract
Consistent discharges of hospital wastewaters (HWWs) pose ecological risk to the biome of the receiving environment with cumulative effect on its healthiness. Understanding the taxonomic profile of microorganisms in the impacted systems is required to establish taxa that are bio-indicators of toxicants, and provide possible taxa for mitigating ecotoxicity of the HWWs. Geochemistry, pollution status and ecotoxicity of heavy metals (HMs) in HWW-impacted sewer (LU) were assessed. The microbiome profiling was based on 16S rDNA and ITS of 18S rDNA metagenomes. The degree of HMs contamination exceeded 50 and HMs pollution load index of LU was severe (1,084), which consequently exerted severe risk (1,411,575 toxic response factors) with very high toxic responses of Co, Cu, Pb, and Cd. Eco-toxicological impact of the HMs on LU skewed microbiome towards Proteobacteria (43%), Actinobacteria (18%), and about 5% apiece for Chloroflexi, Acidobacteria, Plantomycetes, and Bacteroidetes. Likewise, the relative abundance of in LU inclined towards Ascomycota (59%), Basidiomycota (17%) and unclassified Eukarya_uc_p (16%). Exclusively found in LU sediments were 44,862 bacterial species and 42,881 fungi taxa, while 72,877 and 53,971 species of bacteria and fungi, respectively, were found missing. Extinction and emergence of bacteria and fungi taxa in LU were in response to HMs ecotoxicity and the need for natural attenuation processes respectively. The profiled taxa in LU may be plausible in bioremediation strategies of the impacted system, and in designing knowledge-based bioreactor system for the treatment of HWWs before discharge into the environment.
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Affiliation(s)
- Vincent Happy Ogwugwa
- Department of Microbiology, Faculty of Science, University of Lagos, Akoka, Yaba, Lagos State, 101017, Nigeria.
| | - Ganiyu Oladunjoye Oyetibo
- Department of Microbiology, Faculty of Science, University of Lagos, Akoka, Yaba, Lagos State, 101017, Nigeria.
| | - Olukayode Oladipupo Amund
- Department of Microbiology, Faculty of Science, University of Lagos, Akoka, Yaba, Lagos State, 101017, Nigeria.
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Deshmukh H, Speth C, Sheppard DC, Neurauter M, Würzner R, Lass-Flörl C, Rambach G. Aspergillus-Derived Galactosaminogalactan Triggers Complement Activation on Human Platelets. Front Immunol 2020; 11:550827. [PMID: 33123129 PMCID: PMC7573070 DOI: 10.3389/fimmu.2020.550827] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 08/21/2020] [Indexed: 12/18/2022] Open
Abstract
Invasive fungal infections caused by Aspergillus (A.) and Mucorales species still represent life-threatening diseases in immunocompromised individuals, and deeper knowledge about fungal interactions with elements of innate immunity, such as complement and platelets, appears essential for optimized therapy. Previous studies showed that galactosaminogalactan secreted by A. fumigatus and A. flavus is deposited on platelets, thereby inducing their activation. Since the altered platelet surface is a putative trigger for complement activation, we aimed to study the interplay of platelets with complement in the presence of fungal GAG. Culture supernatants (SN) of A. fumigatus and A. flavus both induced not only GAG deposition but also subsequent deposition of complement C3 fragments on the platelet surface. The SN of a Δuge3 mutant of A. fumigatus, which is unable to synthesize GAG, did not induce complement deposition on platelets, nor did the SN of other Aspergillus species and all tested Mucorales. Detailed analysis revealed that GAG deposition itself triggered the complement cascade rather than the GAG-induced phosphatidylserine exposure. The lectin pathway of complement could be shown to be crucially involved in this process. GAG-induced complement activation on the platelet surface was revealed to trigger processes that might contribute to the pathogenesis of invasive aspergillosis by A. fumigatus or A. flavus. Both pro-inflammatory anaphylatoxins C3a and C5a arose when platelets were incubated with SN of these fungal species; these processes might favor excessive inflammation after fungal infection. Furthermore, platelets were stimulated to shed microparticles, which are also known to harbor pro-inflammatory and pro-coagulant properties. Not only did early processes of the complement cascade proceed on platelets, but also the formation of the terminal complement C5b-9 complex was detected on platelets after incubation with fungal SN. Subsequently, reduced viability of the platelets could be shown, which might contribute to the lowered platelet numbers found in infected patients. In summary, fungal GAG initiates an interplay between complement and platelets that can be supposed to contribute to excessive inflammation, thrombocytopenia, and thrombosis, which are important hallmarks of fatal invasive mycoses.
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Affiliation(s)
- Hemalata Deshmukh
- Institute of Hygiene and Medical Microbiology, Medical University of Innsbruck, Innsbruck, Austria
| | - Cornelia Speth
- Institute of Hygiene and Medical Microbiology, Medical University of Innsbruck, Innsbruck, Austria.,Christian Doppler Laboratory for Invasive Fungal Infections, Innsbruck, Austria
| | - Donald C Sheppard
- Department of Microbiology and Immunology, McGill University, Montréal, QC, Canada
| | - Magdalena Neurauter
- Institute of Hygiene and Medical Microbiology, Medical University of Innsbruck, Innsbruck, Austria
| | - Reinhard Würzner
- Institute of Hygiene and Medical Microbiology, Medical University of Innsbruck, Innsbruck, Austria
| | - Cornelia Lass-Flörl
- Institute of Hygiene and Medical Microbiology, Medical University of Innsbruck, Innsbruck, Austria.,Christian Doppler Laboratory for Invasive Fungal Infections, Innsbruck, Austria
| | - Günter Rambach
- Institute of Hygiene and Medical Microbiology, Medical University of Innsbruck, Innsbruck, Austria.,Christian Doppler Laboratory for Invasive Fungal Infections, Innsbruck, Austria
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