Publications by authors named "Matthias Brock"

99 Publications

Aspergillus terreus Species Complex.

Clin Microbiol Rev 2021 Jun 30:e0031120. Epub 2021 Jun 30.

Fungal Biology Group, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom.

Infections due to species are an acute threat to human health; members of the section are the most frequently occurring agents, but depending on the local epidemiology, representatives of section or section are the second or third most important. species complex is of great interest, as it is usually amphotericin B resistant and displays notable differences in immune interactions in comparison to . The latest epidemiological surveys show an increased incidence of as well as an expanding clinical spectrum (chronic infections) and new groups of at-risk patients being affected. Hallmarks of these non- invasive mold infections are high potential for tissue invasion, dissemination, and possible morbidity due to mycotoxin production. We seek to review the microbiology, epidemiology, and pathogenesis of species complex, address clinical characteristics, and highlight the underlying mechanisms of amphotericin B resistance. Selected topics will contrast key elements of with . We provide a comprehensive resource for clinicians dealing with fungal infections and researchers working on pathogenesis, aiming to bridge the emerging translational knowledge and future therapeutic challenges on this opportunistic pathogen.
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http://dx.doi.org/10.1128/CMR.00311-20DOI Listing
June 2021

A structure-based approach for the discovery of inhibitors against methylcitrate synthase of .

J Biomol Struct Dyn 2021 Jun 1:1-13. Epub 2021 Jun 1.

Molecular Biology Laboratory, Institute of Biological Sciences, Federal University of Goiás, Brazil.

Paracoccidioidomycosis (PCM) is a systemic mycosis, endemic in Latin America, caused by fungi of the genus . The treatment of PCM is complex, requiring a long treatment period, which often results in serious side effects. The aim of this study was to screen for inhibitors of a specific target of the fungus that is absent in humans. Methylcitrate synthase (MCS) is a unique enzyme of microorganisms and is responsible for the synthesis of methylcitrate at the beginning of the propionate degradation pathway. This pathway is essential for several microorganisms, since the accumulation of propionyl-CoA can impair virulence and prevent the development of the pathogen. We performed the modeling and molecular dynamics of the structure of (MCS) and performed a virtual screening on 89,415 compounds against the active site of the enzyme. The compounds were selected according to the affinity and efficiency criteria of in vitro tests. Six compounds were able to inhibit the enzymatic activity of recombinant MCS but only the compound ZINC08964784 showed fungistatic and fungicidal activity against spp. cells. The analysis of the interaction profile of this compound with MCS showed its effectiveness in terms of specificity and stability when compared to the substrate (propionyl-CoA) of the enzyme. In addition, this compound did not show cytotoxicity in mammalian cells, with an excellent selectivity index. Our results suggest that the compound ZINC08964784 may become a promising alternative antifungal against spp. Communicated by Ramaswamy H. Sarma.
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http://dx.doi.org/10.1080/07391102.2021.1930584DOI Listing
June 2021

Novel Biological Functions of the NsdC Transcription Factor in Aspergillus fumigatus.

mBio 2021 01 5;12(1). Epub 2021 Jan 5.

Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil

The fungal zinc finger transcription factor NsdC is named after, and is best known for, its essential role in sexual reproduction (ever in exual evelopment). In previous studies with , it was also shown to have roles in promotion of vegetative growth and suppression of asexual conidiation. In this study, the function of the homologue in the opportunistic human pathogen was investigated. NsdC was again found to be essential for sexual development, with deletion of the gene in both and mating partners of a cross leading to complete loss of fertility. However, a functional copy of in one mating partner was sufficient to allow sexual reproduction. Deletion of also led to decreased vegetative growth and allowed conidiation in liquid cultures, again consistent with previous findings. However, NsdC in was shown to have additional biological functions including response to calcium stress, correct organization of cell wall structure, and response to the cell wall stressors. Furthermore, virulence and host immune recognition were affected. Gene expression studies involving chromatin immunoprecipitation (ChIP) of RNA polymerase II (PolII) coupled to next-generation sequencing (Seq) revealed that deletion of resulted in changes in expression of over 620 genes under basal growth conditions. This demonstrated that this transcription factor mediates the activity of a wide variety of signaling and metabolic pathways and indicates that despite the naming of the gene, the promotion of sexual reproduction is just one among multiple roles of NsdC. is an opportunistic human fungal pathogen and the main causal agent of invasive aspergillosis, a life-threatening infection especially in immunocompromised patients. can undergo both asexual and sexual reproductive cycles, and the regulation of both cycles involves several genes and pathways. Here, we have characterized one of these genetic determinants, the NsdC transcription factor, which was initially identified in a screen of transcription factor null mutants showing sensitivity when exposed to high concentrations of calcium. In addition to its known essential roles in sexual reproduction and control of growth rate and asexual reproduction, we have shown in the present study that NsdC transcription factor has additional previously unrecognized biological functions including calcium tolerance, cell wall stress response, and correct cell wall organization and functions in virulence and host immune recognition. Our results indicate that NsdC can play novel additional biological functions not directly related to its role played during sexual and asexual processes.
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http://dx.doi.org/10.1128/mBio.03102-20DOI Listing
January 2021

Global Sexual Fertility in the Opportunistic Pathogen and Identification of New Supermater Strains.

J Fungi (Basel) 2020 Oct 30;6(4). Epub 2020 Oct 30.

School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK.

A sexual cycle in was first described in 2009 with isolates from Dublin, Ireland. However, the extent to which worldwide isolates can undergo sexual reproduction has remained unclear. In this study a global collection of 131 isolates was established with a near 1:1 ratio of mating types. All isolates were crossed to or Irish strains, and a subset of isolates from different continents were crossed together. Ninety seven percent of isolates were found to produce cleistothecia with at least one mating partner, showing that sexual fertility is not limited to the Irish population but is a characteristic of global . However, large variation was seen in numbers of cleistothecia produced per cross, suggesting differences in the possibility for genetic exchange between strains in nature. The majority of crosses produced ascospores with >50% germination rates, but with wide variation evident. A high temperature heat shock was required to induce ascospore germination. Finally, a new set of highly fertile and supermater strains were identified and pyrimidine auxotrophs generated for community use. Results provide insights into the potential for the sexual cycle to generate genetic variation and allow gene flow of medically important traits.
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http://dx.doi.org/10.3390/jof6040258DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7712211PMC
October 2020

Propionate metabolism in a human pathogenic fungus: proteomic and biochemical analyses.

IMA Fungus 2020 5;11. Epub 2020 May 5.

Laboratório de Biologia Molecular, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, Brazil.

Fungi of the complex spp. are thermodimorphic organisms that cause Paracoccidioidomycosis, one of the most prevalent mycoses in Latin America. These fungi present metabolic mechanisms that contribute to the fungal survival in host tissues. activates glycolysis and fermentation while inactivates aerobic metabolism in iron deprivation, a condition found during infection. In lungs face a glucose poor environment and relies on the beta-oxidation to support energy requirement. During mycelium to yeast transition cells up-regulate transcripts related to lipid metabolism and cell wall remodeling in order to cope with the host body temperature. spp. cells also induce transcripts/enzymes of the methylcitrate cycle (MCC), a pathway responsible for propionyl-CoA metabolism. Propionyl-CoA is a toxic compound formed during the degradation of odd-chain fatty acids, branched chain amino acids and cholesterol. Therefore, fungi require a functional MCC for full virulence and the ability to metabolize propionyl-CoA is related to the virulence traits in spp. On this way we sought to characterize the propionate metabolism in spp. The data collected showed that grows in propionate and activates the MCC by accumulating transcripts and proteins of methylcitrate synthase (MCS), methylcitrate dehydratase (MCD) and methylisocitrate lyase (MCL). Biochemical characterization of MCS showed that the enzyme is regulated by phosphorylation, an event not yet described. Proteomic analyses further indicate that yeast cells degrades lipids and amino acids to support the carbon requirement for propionate metabolism. The induction of a putative propionate kinase suggests that fungal cells use propionyl-phosphate as an intermediate in the production of toxic propionyl-CoA. Concluding, the metabolism of propionate in is under regulation at transcriptional and phosphorylation levels and that survival on this carbon source requires additional mechanisms other than activation of MCC.
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http://dx.doi.org/10.1186/s43008-020-00029-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7324963PMC
May 2020

The Added Value of Longitudinal Imaging for Preclinical Efficacy Testing of Therapeutic Compounds against Cerebral Cryptococcosis.

Antimicrob Agents Chemother 2020 06 23;64(7). Epub 2020 Jun 23.

Biomedical MRI, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium.

Brain infections with are associated with significant morbidity and mortality. Cryptococcosis typically presents as meningoencephalitis or fungal mass lesions called cryptococcomas. Despite frequent discoveries of promising novel antifungals, the clinical need for drugs that can more efficiently treat these brain infections remains. A crucial step in drug development is the evaluation of drug efficacy in animal models. This mainly relies on survival studies or postmortem analyses in large groups of animals, but these techniques only provide information on specific organs of interest at predefined time points. In this proof-of-concept study, we validated the use of noninvasive preclinical imaging to obtain longitudinal information on the therapeutic efficacy of amphotericin B or fluconazole monotherapy in meningoencephalitis and cryptococcoma mouse models. Bioluminescence imaging enabled the rapid and evaluation of drug efficacy, while complementary high-resolution anatomical information obtained by magnetic resonance imaging of the brain allowed a precise assessment of the extent of infection and lesion growth rates. We demonstrated a good correlation between both imaging readouts and the fungal burden in various organs. Moreover, we identified potential pitfalls associated with the interpretation of therapeutic efficacy based solely on postmortem studies, demonstrating the added value of this noninvasive dual imaging approach compared to standard mortality curves or fungal load endpoints. This novel preclinical imaging platform provides insights in the dynamic aspects of the therapeutic response and facilitates a more efficient and accurate translation of promising antifungal compounds from bench to bedside.
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http://dx.doi.org/10.1128/AAC.00070-20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7318040PMC
June 2020

Sensitive bioluminescence imaging of fungal dissemination to the brain in mouse models of cryptococcosis.

Dis Model Mech 2019 06 17;12(6). Epub 2019 Jun 17.

Biomedical MRI, Department of Imaging and Pathology, KU Leuven, 3000 Leuven, Belgium

is a leading cause of fungal brain infection, but the mechanism of dissemination and dynamics of cerebral infection following pulmonary disease are poorly understood. To address these questions, non-invasive techniques that can study the dynamic processes of disease development and progression in living animal models or patients are required. As such, bioluminescence imaging (BLI) has emerged as a powerful tool to evaluate the spatial and temporal distribution of infection in living animals. We aimed to study the time profile of the dissemination of cryptococcosis from the lung to the brain in murine models by engineering the first bioluminescent KN99α strain, expressing a sequence-optimized red-shifted luciferase. The high pathogen specificity and sensitivity of BLI was complemented by the three-dimensional anatomical information from micro-computed tomography (μCT) of the lung and magnetic resonance imaging (MRI) of the brain. These non-invasive imaging techniques provided longitudinal readouts on the spatial and temporal distribution of infection following intravenous, intranasal or endotracheal routes of inoculation. Furthermore, the imaging results correlated strongly with the fungal load in the respective organs. By obtaining dynamic and quantitative information about the extent and timing of brain infections for individual animals, we found that dissemination to the brain after primary infection of the lung is likely a late-stage event with a timeframe that is variable between animals. This novel tool in research can aid the identification of host and pathogen factors involved in this process, and supports development of novel preventive or therapeutic approaches.
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http://dx.doi.org/10.1242/dmm.039123DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6602310PMC
June 2019

Metabolic Peculiarities of Dimorphism as Demonstrated by iTRAQ Labeling Proteomics.

Front Microbiol 2019 20;10:555. Epub 2019 Mar 20.

Laboratório de Biologia Molecular, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, Brazil.

Paracoccidioidomycosis (PCM), a systemic mycosis with a high incidence in Latin America, is caused by thermodimorphic fungi of the genus. The contact with host occurs by the inhalation of conidia or mycelial propagules which once reaching the pulmonary alveoli differentiate into yeast cells. This transition process is vital in the pathogenesis of PCM allowing the fungus survival in the host. Thus, the present work performed a comparative proteome analysis of mycelia, mycelia-to-yeast transition, and yeast cells of . For that, tryptic peptides were labeled with iTRAQ and identified by LC-MS/MS and computational data analysis, which allowed the identification of 312 proteins differentially expressed in different morphological stages. Data showed that yeast cells preferentially employ aerobic beta-oxidation and the tricarboxylic acid cycle accompanied by oxidative phosphorylation for ATP production, in comparison to mycelia and the transition from mycelia-to-yeast cells. Furthermore, yeast cells show a metabolic reprogramming in amino acid metabolism and in the induction of virulence determinants and heat shock proteins allowing adaptation to environmental conditions during the increase of the temperature. In opposite of that, the alcoholic fermentation found to , at least under laboratory conditions, is strongly favored in mycelium compared to yeast cells. Thereby, the data strongly support substantial metabolic differences among members of the complex, when comparing the saprobiotic mycelia and the yeast parasitic phases.
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http://dx.doi.org/10.3389/fmicb.2019.00555DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6436475PMC
March 2019

Protein Kinase A and High-Osmolarity Glycerol Response Pathways Cooperatively Control Cell Wall Carbohydrate Mobilization in .

mBio 2018 12 11;9(6). Epub 2018 Dec 11.

Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brazil

mitogen-activated protein kinases (MAPKs) are involved in maintaining the normal morphology of the cell wall and providing resistance against cell wall-damaging agents. Upon cell wall stress, cell wall-related sugars need to be synthesized from carbohydrate storage compounds. Here we show that this process is dependent on cAMP-dependent protein kinase A (PKA) activity and regulated by the high-osmolarity glycerol response (HOG) MAPKs SakA and MpkC. These protein kinases are necessary for normal accumulation/degradation of trehalose and glycogen, and the lack of these genes reduces glucose uptake and glycogen synthesis. Alterations in glycogen synthesis were observed for the and deletion mutants, which also displayed alterations in carbohydrate exposure on the cell wall. Carbohydrate mobilization is controlled by SakA interaction with PkaC1 and PkaR, suggesting a putative mechanism where the PkaR regulatory subunit leaves the complex and releases the SakA-PkaC1 complex for activation of enzymes involved in carbohydrate mobilization. This work reveals the communication between the HOG and PKA pathways for carbohydrate mobilization for cell wall construction. is an opportunistic human pathogen causing allergic reactions or systemic infections such as invasive pulmonary aspergillosis, especially in immunocompromised patients. The fungal cell wall is the main component responsible for recognition by the immune system, due to the specific composition of polysaccharide carbohydrates exposed on the surface of the fungal cell wall called pathogen-associated molecular patterns (PAMPs). Key enzymes in the fungal cell wall biosynthesis are a good target for fungal drug development. This report elucidates the cooperation between the HOG and PKA pathways in the mobilization of carbohydrates for fungal cell wall biosynthesis. We suggest that the reduced mobilization of simple sugars causes defects in the structure of the fungal cell wall. In summary, we propose that SakA is important for PKA activity, therefore regulating the availability and mobilization of monosaccharides for fungal cell wall biosynthesis during cell wall damage and the osmotic stress response.
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http://dx.doi.org/10.1128/mBio.01952-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6299480PMC
December 2018

Cross-Chemistry Leads to Product Diversity from Atromentin Synthetases in Aspergilli from Section Nigri.

Cell Chem Biol 2019 02 6;26(2):223-234.e6. Epub 2018 Dec 6.

Fungal Genetics and Biology, School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK. Electronic address:

Non-ribosomal peptide synthetase (NRPS)-like enzymes catalyze the non-oxidative homodimerization of aromatic α-keto acids, but the exact reaction mechanism is unknown. The furanone-forming thioesterase domain of the Aspergillus terreus aspulvinone E synthetase MelA displays a predicted quinone-forming motif, whereby its catalytic triad contains an essential cysteine indicating an unusual thioester intermediate. To convert MelA into a quinone-forming atromentin synthetase its thioesterase domain was replaced with that from a Paxillus involutus or A. terreus atromentin synthetase. Phylogenetic proximity of donor and acceptor seems important, as only replacement with the A. terreus thioesterase was functional. Heterologous expression of atromentin synthetases in Aspergillus niger and Aspergillus oryzae revealed host-dependent product formation whereby cross-chemistry directed atromentin biosynthesis in A. niger toward atrofuranic acid. Screening of aspergilli from section Nigri identified an atromentin synthetase in Aspergillus brasiliensis that produced atrofuranic acid in the homologous host. Therefore, cross-chemistry on quinone cores appears common to section Nigri.
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http://dx.doi.org/10.1016/j.chembiol.2018.10.021DOI Listing
February 2019

Prolonged Waking and Recovery Sleep Affect the Serum MicroRNA Expression Profile in Humans.

Clocks Sleep 2019 Mar 22;1(1):75-86. Epub 2018 Nov 22.

Institute of Pharmacology and Toxicology, University of Zürich, 8057 Zürich, Switzerland.

MicroRNAs (miRNAs) are small, abundant, non-coding RNA fragments that regulate gene expression and silencing at the post-transcriptional level. The miRNAs each control various downstream targets and play established roles in different biological processes. Given that miRNAs were recently proposed to contribute to the molecular control of sleep-wake regulation in animal models and narcoleptic patients, we investigated the impact of acute sleep deprivation on blood miRNA expression in healthy adult men of two different age groups. Twenty-two young (mean age: 24 ± 3 years) and nine older (65 ± 1 years) volunteers completed a controlled in-lab study, consisting of 8 h baseline sleep, followed by 40 h of extended wakefulness, and a 10-h recovery sleep opportunity. At the same circadian time in all three conditions (at 4:23 p.m. ± 23 min), qPCR expression profiling of 86 miRNAs was performed in blood serum. Thirteen different miRNAs could be reliably quantified and were analyzed using mixed-model ANOVAs. It was found that miR-30c and miR-127 were reliably affected by previous sleep and wakefulness, such that expression of these miRNAs was upregulated after extended wakefulness and normalized after recovery sleep. Together with previous findings in narcolepsy patients, our preliminary data indicate that miR-30c and its target proteins may provide a biomarker of elevated sleep debt in humans.
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http://dx.doi.org/10.3390/clockssleep1010008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7509676PMC
March 2019

Long non-coding RNAs influence the transcriptome in pulmonary arterial hypertension: the role of PAXIP1-AS1.

J Pathol 2019 03 16;247(3):357-370. Epub 2019 Jan 16.

Ludwig Boltzmann Institute for Lung Vascular Research, Graz, Austria.

In idiopathic pulmonary arterial hypertension (IPAH), global transcriptional changes induce a smooth muscle cell phenotype characterised by excessive proliferation, migration, and apoptosis resistance. Long non-coding RNAs (lncRNAs) are key regulators of cellular function. Using a compartment-specific transcriptional profiling approach, we sought to investigate the link between transcriptional reprogramming by lncRNAs and the maladaptive smooth muscle cell phenotype in IPAH. Transcriptional profiling of small remodelled arteries from 18 IPAH patients and 17 controls revealed global perturbations in metabolic, neuronal, proliferative, and immunological processes. We demonstrated an IPAH-specific lncRNA expression profile and identified the lncRNA PAXIP1-AS1 as highly abundant. Comparative transcriptomic analysis and functional assays revealed an intrinsic role for PAXIP1-AS1 in orchestrating the hyperproliferative and migratory actions of IPAH smooth muscle cells. Further, we showed that PAXIP1-AS1 mechanistically interferes with the focal adhesion axis via regulation of expression and phosphorylation of its downstream target paxillin. Overall, we show that changes in the lncRNA transcriptome contribute to the disease-specific transcriptional landscape in IPAH. Our results suggest that lncRNAs, such as PAXIP1-AS1, can modulate smooth muscle cell function by affecting multiple IPAH-specific transcriptional programmes. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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http://dx.doi.org/10.1002/path.5195DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6900182PMC
March 2019

Monitoring of Fluconazole and Caspofungin Activity against Candida glabrata Biofilms by Bioluminescence Imaging.

Antimicrob Agents Chemother 2019 02 29;63(2). Epub 2019 Jan 29.

VIB-KU Leuven Center for Microbiology, Leuven, Belgium.

can attach to various medical implants and forms thick biofilms despite its inability to switch from yeast to hyphae. The current biofilm models only provide limited information about colonization and infection and usually require animal sacrifice. To gain real-time information from individual BALB/c mice, we developed a noninvasive imaging technique to visualize biofilms in catheter fragments that were subcutaneously implanted on the back of mice. Bioluminescent reporter strains ( 7/2/4 and 8/1/4), free of auxotrophic markers, expressing a codon-optimized firefly luciferase were generated. A murine subcutaneous model was used to follow real-time biofilm formation in the presence and absence of fluconazole and caspofungin. The fungal load in biofilms was quantified by CFU counts and by bioluminescence imaging (BLI). biofilms formed within the first 24 h, as documented by the increased number of device-associated cells and elevated bioluminescent signal compared with adhesion at the time of implant. The model allowed monitoring of the antibiofilm activity of caspofungin against biofilms through bioluminescent imaging from day four after the initiation of treatment. Contrarily, signals emitted from biofilms implanted in fluconazole-treated mice were similar to the light emitted from control-treated mice. This study gives insights into the real-time development of biofilms under conditions. BLI proved to be a dynamic, noninvasive, and sensitive tool to monitor continuous biofilm formation and activity of antifungal agents against biofilms formed on abiotic surfaces .
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http://dx.doi.org/10.1128/AAC.01555-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6355587PMC
February 2019

Hybrid in silico/in vitro target fishing to assign function to "orphan" compounds of food origin - The case of the fungal metabolite atromentin.

Food Chem 2019 Jan 4;270:61-69. Epub 2018 Jul 4.

Department of Food Chemistry and Toxicology, Faculty of Chemistry, University of Vienna, Waehringer Str. 38, 1090 Vienna, Austria. Electronic address:

Many small molecules of food origin may effect human health but lack an adequate description of their biological activity. To fill this knowledge gap, a first-line workflow is needed to assign putative functions, rank the endpoints for testing and guide wet-lab experiments. In this framework, the identification of potential biological targets can be used to probe the activity of orphan compounds using a so-called "target fishing" approach. Here, we present a proof of concept study using an in silico/in vitro target fishing approach on the fungal secondary metabolite atromentin. The procedure relies on a computational screening for activity identification coupled with experimental trials for dose-response characterization. Computational results identified estrogen receptors and 17-β-hydroxysteroid dehydrogenase as potential targets. Experiments confirmed a weak estrogenic activity, supporting the reliability of the procedure. Despite limited estrogenicity of atromentin, the proposed inhibition of 17-β-hydroxysteroid dehydrogenase should be considered as a source for endocrine disruptive effects.
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http://dx.doi.org/10.1016/j.foodchem.2018.07.027DOI Listing
January 2019

A Multimodal Imaging Approach Enables Assessment of Antifungal Treatment in a Mouse Model of Invasive Pulmonary Aspergillosis.

Antimicrob Agents Chemother 2018 07 26;62(7). Epub 2018 Jun 26.

Laboratory of Clinical Bacteriology and Mycology, Department of Microbiology and Immunology, KU Leuven, Leuven, Belgium.

causes life-threatening lung infections in immunocompromised patients. Mouse models are extensively used in research to assess the efficacies of antifungals. In recent years, there has been an increasing interest in the use of noninvasive imaging techniques to evaluate experimental infections. However, single imaging modalities have limitations concerning the type of information they can provide. In this study, magnetic resonance imaging and bioluminescence imaging were combined to obtain longitudinal information on the extent of developing lesions and fungal load in a leukopenic mouse model of invasive pulmonary aspergillosis (IPA). This multimodal imaging approach was used to assess changes occurring within lungs of infected mice receiving voriconazole treatment starting at different time points after infection. The results showed that IPA development depends on the inoculum size used to infect animals and that disease can be successfully prevented or treated by initiating intervention during early stages of infection. Furthermore, we demonstrated that a reduction in fungal load is not necessarily associated with the disappearance of lesions on anatomical lung images, especially when antifungal treatment coincides with immune recovery. In conclusion, multimodal imaging allows an investigation of different aspects of disease progression or recovery by providing complementary information on dynamic processes, which are highly useful for assessing the efficacy of (novel) therapeutic compounds in a time- and labor-efficient manner.
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http://dx.doi.org/10.1128/AAC.00240-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6021662PMC
July 2018

ATNT: an enhanced system for expression of polycistronic secondary metabolite gene clusters in .

Fungal Biol Biotechnol 2017 19;4:13. Epub 2017 Dec 19.

Fungal Genetics and Biology, School of Life Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD UK.

Background: Fungi are treasure chests for yet unexplored natural products. However, exploitation of their real potential remains difficult as a significant proportion of biosynthetic gene clusters appears silent under standard laboratory conditions. Therefore, elucidation of novel products requires gene activation or heterologous expression. For heterologous gene expression, we previously developed an expression platform in that is based on the transcriptional regulator TerR and its target promoter P.

Results: In this study, we extended this system by regulating expression of  by the doxycycline inducible Tet-on system. Reporter genes cloned under the control of the target promoter P remained silent in the absence of doxycycline, but were strongly expressed when doxycycline was added. Reporter quantification revealed that the coupled system results in about five times higher expression rates compared to gene expression under direct control of the Tet-on system. As production of secondary metabolites generally requires the expression of several biosynthetic genes, the suitability of the self-cleaving viral peptide sequence P2A was tested in this optimised expression system. P2A allowed polycistronic expression of genes required for Asp-melanin formation in combination with the gene coding for the red fluorescent protein tdTomato. Gene expression and Asp-melanin formation was prevented in the absence of doxycycline and strongly induced by addition of doxycycline. Fluorescence studies confirmed the correct subcellular localisation of the respective enzymes.

Conclusion: This tightly regulated but strongly inducible expression system enables high level production of secondary metabolites most likely even those with toxic potential. Furthermore, this system is compatible with polycistronic gene expression and, thus, suitable for the discovery of novel natural products.
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http://dx.doi.org/10.1186/s40694-017-0042-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5735947PMC
December 2017

Hap43 Domains Are Required under Iron Starvation but Not Excess.

Front Microbiol 2017 1;8:2388. Epub 2017 Dec 1.

Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knoell Institute, Jena, Germany.

Iron availability is a central factor in infections, since iron is a critical micronutrient for all living organisms. The host employs both iron limitation and toxicity strategies to control microbial growth, and successful pathogens are able to tightly coordinate iron homeostasis in response to changing iron levels. As a commensal and opportunistic pathogen, copes with both iron deficiency and excess the precise regulation of iron acquisition, consumption and storage. The transcription factor Hap43 is known to be required for the iron starvation response, while specific domains of its ortholog, HapX, in , were recently shown to regulate iron uptake and consumptions genes under both low and high iron levels. Therefore, we investigated the contribution of Hap43 domains in response to changing iron levels. We found the C-terminus of Hap43 to be essential for the activation of iron uptake genes during iron starvation, whereas, in contrast to , Hap43 was not required in mediating adaptation to iron resistance. These data indicate that the generally conserved metal acquisition systems in fungal pathogens can show individual adaptations to the host environment.
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http://dx.doi.org/10.3389/fmicb.2017.02388DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5717023PMC
December 2017

Lipid components of bile increase the protective effect of conjugated bile salts against antifungal drugs.

Fungal Biol 2017 11 21;121(11):929-938. Epub 2017 Aug 21.

Fungal Genetics and Biology Group, School of Life Sciences, University of Nottingham, University Park, NG7 2RD Nottingham, UK. Electronic address:

Fungi and bacteria can persist in the human gall bladder. Previous studies have shown that bile protects Candida albicans in this cryptic host niche from antifungals, providing a reservoir for intestinal re-colonization after discontinuation of antifungal therapy. Bile and conjugated bile salts trap antifungals in micelles, thereby reducing their bioavailability and possibly promoting the development of drug resistance. Here we show that the protective effect of bile and conjugated bile salts is not limited to C. albicans, but also observed with other fungi. Interestingly, bile, but not conjugated bile salts conferred resistance of C. albicans against fluconazole and only bile mediated resistance of Aspergillus terreus against voriconazole. To investigate this higher potency of bile we aimed in a step-wise reconstitution of bile from conjugated bile salts. Neither addition of phospholipids nor saturated fatty acids protected from azoles. In contrast, supplementation with polyunsaturated fatty acids increased azole resistance and decreased the critical micelle concentration of conjugated bile salts to the level of bile. Therefore, polyunsaturated fatty acids are vital for mixed micelle formation with high potential to trap antifungals. As biliary infections are difficult to treat, drug efficacy in the biliary system should be tested by using reconstituted synthetic bile.
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http://dx.doi.org/10.1016/j.funbio.2017.08.002DOI Listing
November 2017

Persistence within dendritic cells marks an antifungal evasion and dissemination strategy of Aspergillus terreus.

Sci Rep 2017 09 6;7(1):10590. Epub 2017 Sep 6.

Fungal Genetics and Biology Group, School of Life Sciences, University of Nottingham, University Park, NG7 2RD, Nottingham, UK.

Aspergillus terreus is an airborne human fungal pathogen causing life-threatening invasive aspergillosis in immunocompromised patients. In contrast to Aspergillus fumigatus, A. terreus infections are associated with high dissemination rates and poor response to antifungal treatment. Here, we compared the interaction of conidia from both fungal species with MUTZ-3-derived dendritic cells (DCs). After phagocytosis, A. fumigatus conidia rapidly escaped from DCs, whereas A. terreus conidia remained persisting with long-term survival. Escape from DCs was independent from DHN-melanin, as A. terreus conidia expressing wA showed no increased intracellular germination. Within DCs A. terreus conidia were protected from antifungals, whereas A. fumigatus conidia were efficiently cleared. Furthermore, while A. fumigatus conidia triggered expression of DC activation markers such as CD80, CD83, CD54, MHCII and CCR7, persistent A. terreus conidia were significantly less immunogenic. Moreover, DCs confronted with A. terreus conidia neither produced pro-inflammatory nor T-cell stimulating cytokines. However, TNF-α addition resulted in activation of DCs and provoked the expression of migration markers without inactivating intracellular A. terreus conidia. Therefore, persistence within DCs and possibly within other immune cells might contribute to the low response of A. terreus infections to antifungal treatment and could be responsible for its high dissemination rates.
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http://dx.doi.org/10.1038/s41598-017-10914-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5587622PMC
September 2017

A Highly Conserved Basidiomycete Peptide Synthetase Produces a Trimeric Hydroxamate Siderophore.

Appl Environ Microbiol 2017 Nov 17;83(21). Epub 2017 Oct 17.

Department of Pharmaceutical Microbiology at the Hans Knöll Institute, Friedrich Schiller University, Jena, Germany

The model white-rot basidiomycete, () B, encodes putative natural product biosynthesis genes. Among them is the gene for the seven-domain nonribosomal peptide synthetase CsNPS2. It is a member of the as-yet-uncharacterized fungal type VI siderophore synthetase family, which is highly conserved and widely distributed among the basidiomycetes. These enzymes include only one adenylation (A) domain, i.e., one complete peptide synthetase module, and two thiolation/condensation (T-C) didomain partial modules which together constitute an ATCTCTC domain setup. The full-length CsNPS2 enzyme (274.5 kDa) was heterologously produced as a polyhistidine fusion in as a soluble and active protein. -acetyl- -hydroxy-l-ornithine (l-AHO) and --anhydromevalonyl- -hydroxy-l-ornithine (l-AMHO) were accepted as the substrates, based on results of an substrate-dependent [P]ATP-pyrophosphate radioisotope exchange assay. Full-length -CsNPS2 catalyzed amide bond formation between three l-AHO molecules to release the linear l-AHO trimer, called basidioferrin, as the product , which was verified by liquid chromatography-high-resolution electrospray ionization-mass spectrometry analysis. Phylogenetic analyses suggested that type VI family siderophore synthetases are widespread in mushrooms and evolved in a common ancestor of basidiomycetes. The basidiomycete nonribosomal peptide synthetase CsNPS2 represents a member of a widely distributed but previously uninvestigated class (type VI) of fungal siderophore synthetases. Genes orthologous to are highly conserved across various phylogenetic clades of the basidiomycetes. Hence, our work serves as a broadly applicable model for siderophore biosynthesis and iron metabolism in higher fungi. Also, our results on the amino acid substrate preference of CsNPS2 support a further understanding of the substrate selectivity of fungal adenylation domains. Methodologically, this report highlights the /SM-Xpress-based system as a suitable platform to heterologously express multimodular basidiomycete biosynthesis enzymes in the >250-kDa range in soluble and active form.
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http://dx.doi.org/10.1128/AEM.01478-17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5648918PMC
November 2017

Comment on: "Melanisation of Aspergillus terreus-Is Butyrolactone I Involved in the Regulation of Both DOPA and DHN Types of Pigments in Submerged Culture? Microorganisms 2017, 5, 22".

Microorganisms 2017 Jun 21;5(2). Epub 2017 Jun 21.

Fungal Genetics and Biology, School of Life Sciences, University of Nottingham, University Park, NG72RD Nottingham, UK.

A recent article by Palonen et al. describes the effect of butyrolactone I on the expression of a secondary metabolite biosynthesis gene cluster from that shows similarities to fusarubin biosynthesis gene clusters from species. The authors claim that two different types of pigments are formed in conidia, whereby one pigment is termed a DOPA-type melanin and the second a DHN-type melanin. Unfortunately, the terminology of the classification of melanin-types requires revision as Asp-melanin present in conidia is clearly distinct from DOPA-melanins. In addition, some hypotheses in this manuscript are based on questionable data published previously, resulting in incorrect conclusions. Finally, as biochemical data are lacking and metabolite production is only deduced from bioinformatics and transcriptomic data, the production of a second pigment type in conidia appears highly speculative.
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http://dx.doi.org/10.3390/microorganisms5020034DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5488105PMC
June 2017

Aquaporin 1 controls the functional phenotype of pulmonary smooth muscle cells in hypoxia-induced pulmonary hypertension.

Basic Res Cardiol 2017 05 13;112(3):30. Epub 2017 Apr 13.

Division of Pulmonology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.

Vascular remodelling in hypoxia-induced pulmonary hypertension (PH) is driven by excessive proliferation and migration of endothelial and smooth muscle cells. The expression of aquaporin 1 (AQP1), an integral membrane water channel protein involved in the control of these processes, is tightly regulated by oxygen levels. The role of AQP1 in the pathogenesis of PH, however, has not been directly addressed so far. This study was designed to characterize expression and function of AQP1 in pulmonary vascular cells from human arteries and in the mouse model of hypoxia-induced PH. Exposure of human pulmonary vascular cells to hypoxia significantly induced the expression of AQP1. Similarly, levels of AQP1 were found to be upregulated in lungs of mice with hypoxia-induced PH. The functional role of AQP1 was further tested in human pulmonary artery smooth muscle cells demonstrating that depletion of AQP1 reduced proliferation, the migratory potential, and, conversely, increased apoptosis of these cells. This effect was associated with higher expression of the tumour suppressor gene p53. Using the mouse model of hypoxia-induced PH, application of GapmeR inhibitors targeting AQP1 abated the hypoxia-induced upregulation of AQP1 and, of note, reversed PH by decreasing both right ventricular pressure and hypertrophy back to the levels of control mice. Our data suggest an important functional role of AQP1 in the pathobiology of hypoxia-induced PH. These results offer novel insights in our pathogenetic understanding of the disease and propose AQP1 as potential therapeutic in vivo target.
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http://dx.doi.org/10.1007/s00395-017-0620-7DOI Listing
May 2017

Low tissue levels of miR-125b predict malignancy in solitary fibrous tumors of the pleura.

Respir Res 2017 03 2;18(1):43. Epub 2017 Mar 2.

Department of Pulmonology, University Hospital Zurich, University of Zurich, Rämistr. 100, 8091, Zurich, Switzerland.

Background: Solitary fibrous tumors of the pleura (SFTP) are rare neoplasia of the chest. A subset of SFTP follows a malignant course, sometimes several years after complete resection. Traditional scoring systems based on clinical and histological features are poor predictors of biological behavior. This study aimed to investigate tumor-associated miRNAs expression as novel biomarkers to predict the clinical behavior of SFTP.

Methods: Formalin-fixed and paraffin-embedded SFTP tissues blocks from patients surgically resected between 1992 and 2013 at two tertiary care teaching hospitals were included. SFTP tumors were categorized as either malignant or benign variants according to the WHO classification. Following miRNAs levels were measured: let-7a, miR-16b, miR-17, miR-21, miR-31, miR-34a, miR-92a, miR-125a, miR-125b, miR-195-5b, miR-203a, and miR-223. Differential gene expressions which were calculated with the threshold cycle (C) method were compared among the two variants.

Results: Thirty-eight patients (40% male, mean age 62.2 (±10.9) years) were included. Expression levels of miR-125b showed a significant difference between benign compared to malignant variants (-3.08 ± 0.93 vs. -2.22 ± 1.36, p = 0.0068). Furthermore, lower levels of miR-125b were found to be associated with increased tumor size (p = 0.0414). Thus, downregulation of miR-125b indicates malignant transformation. All other investigated miRNAs were not associated with grading of SFTP.

Conclusions: Our data suggest a potential role of miR-125b in the pathogenesis of tumor growth and malignant transformation of SFTP, respectively. Further studies have to address the potential use of miRNA-125b as a biomarker or therapeutic target in SFTP.
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http://dx.doi.org/10.1186/s12931-017-0528-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5335791PMC
March 2017

Encapsulation of Antifungals in Micelles Protects during Gall-Bladder Infection.

Front Microbiol 2017 1;8:117. Epub 2017 Feb 1.

Microbial Biochemistry and Physiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knoell InstituteJena, Germany; Fungal Genetics and Biology Group, School of Life Sciences, University of NottinghamNottingham, UK.

is a dimorphic fungus that colonizes human mucosal surfaces with the potential to cause life-threatening invasive candidiasis. Studies on systemic candidiasis in a murine infection model using real-time bioluminescence imaging revealed persistence of in the gall bladder under antifungal therapy. Preliminary analyses showed that bile conferred resistance against a wide variety of antifungals enabling survival in this cryptic host niche. Here, bile and its components were studied for their ability to reduce antifungal efficacy in order to elucidate the underlying mechanism of protection. While unconjugated bile salts were toxic to , taurine, or glycine conjugated bile salts were well tolerated and protective against caspofungin and amphotericin B when exceeding their critical micellar concentration. Microarray experiments indicated that upregulation of genes generally known to mediate antifungal protection is not involved in the protection process. In contrast, rhodamine 6G and crystal violet in- and efflux experiments indicated encapsulation of antifungals in micelles, thereby reducing their bioavailability. Furthermore, farnesol sensing was abolished in the presence of conjugated bile salts trapping cells in the hyphal morphology. This suggests that bioavailability of amphiphilic and hydrophobic compounds is reduced in the presence of bile. In contrast, small and hydrophilic molecules, such as cycloheximide, flucytosine, or sodium azide kept their antifungal properties. We therefore conclude that treatment of gall bladder and bile duct infections is hampered by the ability of bile salts to encapsulate antifungals in micelles. As a consequence, treatment of gall bladder or bile duct infections should favor the use of small hydrophilic drugs that are not solubilised in micelles.
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http://dx.doi.org/10.3389/fmicb.2017.00117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5285334PMC
February 2017

Widespread Inter- and Intra-Domain Horizontal Gene Transfer of d-Amino Acid Metabolism Enzymes in Eukaryotes.

Front Microbiol 2016 20;7:2001. Epub 2016 Dec 20.

Centre for Genomic Regulation, The Barcelona Institute of Science and TechnologyBarcelona, Spain; Universitat Pompeu FabraBarcelona, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA)Barcelona, Spain.

Analysis of the growing number of available fully-sequenced genomes has shown that Horizontal Gene Transfer (HGT) in eukaryotes is more common than previously thought. It has been proposed that genes with certain functions may be more prone to HGT than others, but we still have a very poor understanding of the selective forces driving eukaryotic HGT. Recent work uncovered that d-amino acid racemases have been commonly transferred from bacteria to fungi, but their role in the receiving organisms is currently unknown. Here, we set out to assess whether d-amino acid racemases are commonly transferred to and between eukaryotic groups. For this we performed a global survey that used a novel automated phylogeny-based HGT-detection algorithm (Abaccus). Our results revealed that at least 7.0% of the total eukaryotic racemase repertoire is the result of inter- or intra-domain HGT. These transfers are significantly enriched in plant-associated fungi. For these, we hypothesize a possible role for the acquired racemases allowing to exploit minoritary nitrogen sources in plant biomass, a nitrogen-poor environment. Finally, we performed experiments on a transferred aspartate-glutamate racemase in the fungal human pathogen , which however revealed no obvious biological role.
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http://dx.doi.org/10.3389/fmicb.2016.02001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5169069PMC
December 2016

Analysis of hypoxia-induced noncoding RNAs reveals metastasis-associated lung adenocarcinoma transcript 1 as an important regulator of vascular smooth muscle cell proliferation.

Exp Biol Med (Maywood) 2017 03 5;242(5):487-496. Epub 2017 Jan 5.

1 Division of Pulmonology, University Hospital Zurich, University of Zurich, Zurich CH-8091, Switzerland.

Vascular remodeling, a pathogenic hallmark in pulmonary hypertension, is mainly driven by a dysbalance between proliferation and apoptosis of human pulmonary artery smooth muscle cells. It has previously been shown that microRNAs are involved in the pathogenesis of pulmonary hypertension. However, the role of long noncoding RNAs has not been evaluated. long noncoding RNA expression was quantified in human pulmonary artery smooth muscle cells using PCR arrays and quantitative PCR. Knockdown of genes was performed by transfection of siRNA or GapmeR. Proliferation and migration were measured using BrdU incorporation and wound healing assays. The mouse model of hypoxia-induced PH was used to determine the physiological meaning of identified long noncoding RNAs. The expression of 84 selected long noncoding RNAs was assessed in hypoxic human pulmonary artery smooth muscle cells and the levels of metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) were significantly increased. Depletion of hypoxia-inducible factor 1α abolished the hypoxia-induced upregulation of metastasis-associated lung adenocarcinoma transcript 1 expression. Silencing of MALAT1 significantly decreased proliferation and migration of human pulmonary artery smooth muscle cells. In vivo, MALAT1 expression was significantly increased in lungs of hypoxic mice. Of note, targeting of MALAT1 by GapmeR ameliorated heart hypertrophy in mice with pulmonary hypertension. This is the first report on functional characterization of MALAT1 in the pulmonary vasculature. Our data provide evidence that MALAT1 expression is significantly increased by hypoxia, probably by hypoxia-inducible factor 1α. Intervention experiments confirmed that MALAT1 regulates the proliferative phenotype of smooth muscle cells and silencing of MALAT1 reduced heart hypertrophy in mice with pulmonary hypertension. These data indicate a potential role of MALAT1 in the pathogenesis of pulmonary hypertension. Impact statement Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a long noncoding RNA that mediates several biological processes. In the context of vascular biology, MALAT1 has been shown to be inducible by hypoxia and to control cell proliferation. These processes are of major importance for the pathophysiology of hypoxia-induced pulmonary hypertension (PH). Until now, the physiological role of MALAT1 in PH remains unclear. By using smooth muscle cells and by employing an established PH mouse model, we provide evidence that hypoxia induces MALAT1 expression. Moreover, depletion of MALAT1 inhibited migration and proliferation of smooth muscle cells, probably by the induction of cyclin-dependent kinase inhibitors. Of note, MALAT1 was significantly increased in mice exposed to hypoxia and silencing of MALAT1 ameliorated heart hypertrophy in mice with hypoxia-induced PH. Since vascular remodeling and right heart failure as a consequence of pulmonary pressure overload is a major problem in PH, these data have implications for our pathogenetic understanding.
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http://dx.doi.org/10.1177/1535370216685434DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5367660PMC
March 2017

Dynamic Immune Cell Recruitment After Murine Pulmonary Aspergillus fumigatus Infection under Different Immunosuppressive Regimens.

Front Microbiol 2016 13;7:1107. Epub 2016 Jul 13.

Department of Medicine II, Würzburg University HospitalWürzburg, Germany; Research Center for Infectious Diseases, Julius-Maximilians-University WürzburgWürzburg, Germany; Interdisciplinary Center for Clinical Science Research LaboratoryWuürzburg, Germany; Graduate School of Life Sciences WürzburgWürzburg, Germany.

Humans are continuously exposed to airborne spores of the saprophytic fungus Aspergillus fumigatus. However, in healthy individuals pulmonary host defense mechanisms efficiently eliminate the fungus. In contrast, A. fumigatus causes devastating infections in immunocompromised patients. Host immune responses against A. fumigatus lung infections in immunocompromised conditions have remained largely elusive. Given the dynamic changes in immune cell subsets within tissues upon immunosuppressive therapy, we dissected the spatiotemporal pulmonary immune response after A. fumigatus infection to reveal basic immunological events that fail to effectively control invasive fungal disease. In different immunocompromised murine models, myeloid, notably neutrophils, and macrophages, but not lymphoid cells were strongly recruited to the lungs upon infection. Other myeloid cells, particularly dendritic cells and monocytes, were only recruited to lungs of corticosteroid treated mice, which developed a strong pulmonary inflammation after infection. Lymphoid cells, particularly CD4(+) or CD8(+) T-cells and NK cells were highly reduced upon immunosuppression and not recruited after A. fumigatus infection. Moreover, adoptive CD11b(+) myeloid cell transfer rescued cyclophosphamide immunosuppressed mice from lethal A. fumigatus infection but not cortisone and cyclophosphamide immunosuppressed mice. Our findings illustrate that CD11b(+) myeloid cells are critical for anti-A. fumigatus defense under cyclophosphamide immunosuppressed conditions.
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http://dx.doi.org/10.3389/fmicb.2016.01107DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4942482PMC
July 2016

Reducing hypoxia and inflammation during invasive pulmonary aspergillosis by targeting the Interleukin-1 receptor.

Sci Rep 2016 05 24;6:26490. Epub 2016 May 24.

Unité de recherche Cytokines &Inflammation, Institut Pasteur, Paris.

Hypoxia as a result of pulmonary tissue damage due to unresolved inflammation during invasive pulmonary aspergillosis (IPA) is associated with a poor outcome. Aspergillus fumigatus can exploit the hypoxic microenvironment in the lung, but the inflammatory response required for fungal clearance can become severely disregulated as a result of hypoxia. Since severe inflammation can be detrimental to the host, we investigated whether targeting the interleukin IL-1 pathway could reduce inflammation and tissue hypoxia, improving the outcome of IPA. The interplay between hypoxia and inflammation was investigated by in vivo imaging of hypoxia and measurement of cytokines in the lungs in a model of corticosteroid immunocompromised and in Cxcr2 deficient mice. Severe hypoxia was observed following Aspergillus infection in both models and correlated with development of pulmonary inflammation and expression of hypoxia specific transcripts. Treatment with IL-1 receptor antagonist reduced hypoxia and slightly, but significantly reduced mortality in immunosuppressed mice, but was unable to reduce hypoxia in Cxcr2(-/-) mice. Our data provides evidence that the inflammatory response during invasive pulmonary aspergillosis, and in particular the IL-1 axis, drives the development of hypoxia. Targeting the inflammatory IL-1 response could be used as a potential immunomodulatory therapy to improve the outcome of aspergillosis.
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http://dx.doi.org/10.1038/srep26490DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4877709PMC
May 2016

A Non-canonical Melanin Biosynthesis Pathway Protects Aspergillus terreus Conidia from Environmental Stress.

Cell Chem Biol 2016 05 28;23(5):587-597. Epub 2016 Apr 28.

Microbial Biochemistry and Physiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knoell Institute, Beutenbergstr. 11a, 07745 Jena, Germany; Fungal Genetics and Biology Group, School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK; Institute for Microbiology, Friedrich Schiller University, 07743 Jena, Germany. Electronic address:

Melanins are ubiquitous pigments found in all kingdoms of life. Most organisms use them for protection from environmental stress, although some fungi employ melanins as virulence determinants. The human pathogenic fungus Aspergillus fumigatus and related Ascomycetes produce dihydroxynaphthalene- (DHN) melanin in their spores, the conidia, and use it to inhibit phagolysosome acidification. However, biosynthetic origin of melanin in a related fungus, Aspergillus terreus, has remained a mystery because A. terreus lacks genes for synthesis of DHN-melanin. Here we identify genes coding for an unusual NRPS-like enzyme (MelA) and a tyrosinase (TyrP) that A. terreus expressed under conidiation conditions. We demonstrate that MelA produces aspulvinone E, which is activated for polymerization by TyrP. Functional studies reveal that this new pigment, Asp-melanin, confers resistance against UV light and hampers phagocytosis by soil amoeba. Unexpectedly, Asp-melanin does not inhibit acidification of phagolysosomes, thus likely contributing specifically to survival of A. terreus conidia in acidic environments.
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http://dx.doi.org/10.1016/j.chembiol.2016.03.014DOI Listing
May 2016