Project description:Pathogens have to cope with oxidative, iron- and carbon-limitation stresses in the human body. To understand how combined iron-carbon limitation alters oxidative stress response, Aspergillus fumigatus was cultured in glucose-peptone or peptone containing media supplemented or not with deferiprone as iron chelator. Changes in the transcriptome in these cultures were recorded after H2O2 treatment. Responses to oxidative stress were highly dependent on the availability of glucose and iron. Out of the 16 stress responsive antioxidative enzyme genes only the cat2 catalase-peroxidase gene was upregulated in more than two culturing conditions. The transcriptional responses observed in iron metabolism also varied substantially in these cultures. Only extracellular siderophore production appeared important regardless to culturing conditions in oxidative stress protection, while enhanced synthesis of Fe-S cluster proteins seemed to be crucial for oxidative stress treated iron-limited and fast growing (glucose rich) cultures. Although pathogens and host cells live together in the same place, their culturing conditions (e.g. iron availability, or occurrence of oxidative stress) can be different. Therefore, inhibition of a universally important biochemical process, like Fe-S cluster assembly, may selectively inhibit the pathogen growth in vivo and represent a potential target for antifungal therapy.
Project description:Glucose is a widely used carbon source in laboratory practice to culture Aspergillus fumigatus, however, glucose availability is often low in its “natural habitats” including the human body. We used a physiological–transcriptomical approach to reveal differences between A. fumigatus Af293 cultures incubated on glucose, glucose and peptone, peptone (carbon limitation), or without any carbon source (carbon starvation). Autolytic cell wall degradation was upregulated by both carbon starvation and limitation. The importance of autolytic cell wall degradation in adaptation to carbon stress was also highlighted by approximately 12.4% of the A. fumigatus genomes harbor duplication of genes involved in N-acetyl glucosamine utilization. Glucose withdrawal increased redox imbalance, altered both the transcription of antioxidative enzyme genes and oxidative stress tolerance, downregulated iron acquisition, but upregulated heme protein genes. Transcriptional activity of the Gliotoxin cluster was low in all experiments, while the Fumagillin cluster showed substantial activity both on glucose and under carbon starvation, and the Hexadehydro-astechrome cluster only on glucose. We concluded that glucose withdrawal substantially modified the physiology of A. fumigatus including processes that contribute to virulence. This may explain the challenge of predicting the in vivo behavior of A. fumigatus based on data from glucose rich cultures.
Project description:Aspergillus fumigatus has to cope with a combination of several stress types in the human body, and the interplay between the different stress responses can significantly influence the survival of this human pathogen during the invasion of the host organism. In this study, we examined how the H2O2 induced oxidative stress response depends on iron availability. Surprisingly, the applied H2O2 treatment, which induced only a negligible stress response in iron fed cultures, deleteriously affected the fungus under iron starvation and the majority of observed transcriptome-level stress responses were characteristic only for the combined H2O2-iron starvation stress treatments. Our data suggest that the survival of the fungus highly depended on fragile balances, e.g. between siderophore and ergosterol productions or between economization on iron and production of essential iron containing proteins. The applied stress conditions also affected several processes related to virulence or drug susceptibility including secondary metabolism, zinc acquisition or antifungal drug transport. Our data clearly demonstrate that studying stress responses under single stress treatments is not sufficient at all to understand how fungal pathogens survive in a complex habitat and support the view that the evolutionary success of A. fumigatus as an opportunistic human pathogen is not the mere consequence of the productions of certain virulence factors. Importantly, this fungal pathogen is able to mount and coordinate high-complexity and outstandingly efficient responses to multiple and superpositioning stresses in various harsh habitats like the human body.
Project description:To investigate the influence of Aspergillus fumigatus on iron regulation in macrophages, we obtained macrophages in culture from human derived monocytes and co-cultured the monocyte-derived macrophages with Aspergillus conidia at a 1:1 ratio. We collected samples at 0, 2, 4, 6 and 8 hours and extracted RNA. We then performed gene expression profiling analysis using data obtained from RNA-seq of control macrophages and macrophage co-cultured with Aspergillus fumigatus at five time points.
Project description:Genomic DNA from five strains, Aspergillus fumigatus Af71, Aspergillus fumigatus Af294, Aspergillus clavatus, Neosartorya fenneliae, and Neosartorya fischeri, were co-hybridized with that of Aspergillus fumigatus Af293 and compared.
Project description:Aspergillus fumigatus has to cope with a combination of several stress types after colonisng the human body, and the interplay between the different stress responses can significantly influence the survival of this human pathogen during the invasion of the host organism. In this study, we examined how the H2O2 induced oxidative stress response depends on iron availability. Surprisingly, the applied H2O2 treatment, which induced only a negligible stress response in iron fed cultures, deleteriously affected the fungus under iron starvation and the majority of stress responses on the transcript level were characteristic only for the combined H2O2-iron starvation stress treatments. Our data suggest that the survival of the fungus highly depends on fragile balances, e.g. between siderophore and ergosterol productions or between economization on iron and production of essential iron containing proteins. The applied stress conditions also affected several processes related to virulence or drug susceptibility including secondary metabolism, zinc acquisition or antifungal drug transport. Our[It would be interesting to mention the antioxidative enzymes which are upregulated/increase in abundance under iron-depleting conditions] data clearly demonstrate that studying stress responses under single stress treatments is not sufficient to understand how fungal pathogens survive in a complex habitat and support the view that the evolutionary success of A. fumigatus as an opportunistic human pathogen is not the mere consequence of the productions of certain virulence factors. Importantly, this fungal pathogen is able to mount and coordinate high-complexity and outstandingly efficient responses to multiple and superpositioning stresses in various harsh habitats like the human body.
Project description:Iron restriction imposed by mammalian hosts during an infection is a common mechanism of defense to reduce or avoid the pathogen infection. Iron is essential for organism survival due to its involvement in several biological processes. Aspergillus fumigatus causes invasive aspergillosis (IA), a disease that typically manifests in immunocompromised patients. A. fumigatus has two high affinity mechanisms of iron acquisition during infection: reductive iron assimilation (RIA) and siderophore-mediated iron uptake. It has been shown that siderophore production is important for A. fumigatus virulence, differently to the reductive iron uptake system. A. fumigatus PpzA, the catalytic subunit of protein phosphatase Z (PPZ), has been recently identified as associated with iron assimilation. Transcriptomic and proteomic comparisons between ∆ppzA and wild-type strains under iron starvation showed that PpzA has a broad influence on genes involved in secondary metabolism. LC-MS under standard and iron starvation conditions confirmed that the ΔppzA mutant had reduced production of pyripyropene A (PPA), fumagillin, fumiquinazoline A, TAFC, and helvolic acid. The ΔppzA was shown to be avirulent in a neutropenic murine model of invasive pulmonary aspergillosis. PpzA plays an important role at the interface between iron starvation, regulation of SM production and pathogenicity in A. fumigatus.
Project description:Microarray analysis was used to compare gene expression of Aspergillus fumigatus under two different sporulation temperatures, 17oC and 32oC, with an emphasis on genes encoding known or putative allergens of the fungus. The objective of the study was to investigate whether allergenic potencies of A. fumigatus spores produced under different sporulation temperatures would be influenced by temperature-dependent transcriptional regulation of allergenicity genes. Non-sporulating liquid culture of Aspergillus fumigatus was harvested and divided equally onto two sets of potato dextrose agar plates, one set for incubation at 17oC, the other for incubation at 32oC. After 48 hours of incubation, RNA was harvested from both sets of sporulating cultures, reverse-transcribed into dye-coupled cDNA and hybridized onto microarrays for analysis of gene expression. For each experiment, extracted RNA from the two cultures were hybridized onto two dye-swap technical replicate arrays. A total of three separate experiments were conducted for biological triplicates, for a total of six hybridizations.
Project description:Human dendritic cells were coinfected with Aspergillus fumigatus and human cytomegalovirus. Single-cultures or single-infections served as controls. RNA was isolated and processed for next generation sequencing.