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203 Publications visible to you, out of a total of 203

Abstract (Expand)

The problem with cancer tissue is that its intratumoral heterogeneity and its complexity is extremely high as cells possess, depending on their location and function, different mutations, different mRNA expression and the highest intricacy in the protein pattern. Prior to genomic and proteomic analyses, it is therefore indispensable to identify the exact part of the tissue or even the exact cell. Laser-based microdissection is a tried and tested technique able to produce pure and well-defined cell material for further analysis with proteomic and genomic techniques. It sheds light on the heterogeneity of cancer or other complex diseases and enables the identification of biomarkers. This review aims to raise awareness for the reconsideration of laser-based microdissection and seeks to present current state-of-the-art combinations with omic techniques.

Authors: F. von Eggeling, F. Hoffmann

Date Published: 25th Jun 2020

Publication Type: Not specified

Abstract (Expand)

BACKGROUND: Candida albicans and Candida glabrata are the 2 most prevalent Candida species causing bloodstream infections. Patterns of innate immune activation triggered by the 2 fungi differ considerably. METHODS: To analyze human natural killer (NK) cell activation by both species, we performed ex vivo whole-blood infection assays and confrontation assays with primary human NK cells. RESULTS: C. albicans was a stronger activator for isolated human NK cells than C. glabrata. In contrast, activation of blood NK cells, characterized by an upregulated surface exposure of early activation antigen CD69 and death receptor ligand TRAIL, as well as interferon-gamma (IFN-gamma) secretion, was more pronounced during C. glabrata infection. NK cell activation in blood is mediated by humoral mediators released by other immune cells and does not depend on direct activation by fungal cells. Cross-talk between Candida-confronted monocyte-derived dendritic cells (moDC) and NK cells resulted in the same NK activation phenotype as NK cells in human blood. Blocking experiments and cytokine substitution identified interleukin-12 as a critical mediator in regulation of primary NK cells by moDC. CONCLUSIONS: Activation of human NK cells in response to Candida in human blood mainly occurs indirectly by mediators released from monocytic cells.

Authors: A. Marolda, K. Hunniger, S. Bottcher, W. Vivas, J. Loffler, M. T. Figge, O. Kurzai

Date Published: 11th Jun 2020

Publication Type: Not specified

Abstract (Expand)

The fungal pathogen Candida albicans forms polymorphic biofilms where hyphal morphogenesis and metabolic adaptation are tightly coordinated by a complex intertwined network of transcription factors. The sensing and metabolism of amino acids play important roles during various phases of biofilm development - from adhesion to maturation. Stp2 is a transcription factor that activates the expression of amino acid permease genes and is required for environmental alkalinization and hyphal growth in vitro and during macrophage phagocytosis. While it is well established that Stp2 is activated in response to external amino acids, its role in biofilm formation remains unknown. In addition to widely used techniques, we applied newly developed approaches for automated image analysis to quantify Stp2-regulated filamentation and biofilm growth. Our results show that in the stp2Delta deletion mutant adherence to abiotic surfaces and initial germ tube formation were strongly impaired, but formed mature biofilms with cell density and morphological structures comparable to the control strains. Stp2-dependent nutrient adaptation appeared to play an important role in biofilm development: stp2Delta biofilms formed under continuous nutrient flow displayed an overall reduction in biofilm formation, whereas under steady conditions the mutant strain formed biofilms with lower metabolic activity, resulting in increased cell survival and biofilm longevity. A deletion of STP2 led to increased rapamycin susceptibility and transcriptional activation of GCN4, the transcriptional regulator of the general amino acid control pathway, demonstrating a connection of Stp2 to other nutrient-responsive pathways. In summary, the transcription factor Stp2 is important for C. albicans biofilm formation, where it contributes to adherence and induction of morphogenesis, and mediates nutrient adaption and cell longevity in mature biofilms.

Authors: B. Bottcher, B. Hoffmann, E. Garbe, T. Weise, Z. Cseresnyes, P. Brandt, S. Dietrich, D. Driesch, M. T. Figge, S. Vylkova

Date Published: 20th May 2020

Publication Type: Not specified

Abstract (Expand)

Extracellular vesicles have an important function in cellular communication. Here, we show that human and mouse monocytes release TGF-beta1-transporting vesicles in response to the pathogenic fungus Candida albicans. Soluble beta-glucan from C. albicans binds to complement receptor 3 (CR3, also known as CD11b/CD18) on monocytes and induces the release of TGF-beta1-transporting vesicles. CR3-dependence is demonstrated using CR3-deficient (CD11b knockout) monocytes generated by CRISPR-CAS9 genome editing and isolated from CR3-deficient (CD11b knockout) mice. These vesicles reduce the pro-inflammatory response in human M1-macrophages as well as in whole blood. Binding of the vesicle-transported TGF-beta1 to the TGF-beta receptor inhibits IL1B transcription via the SMAD7 pathway in whole blood and induces TGFB1 transcription in endothelial cells, which is resolved upon TGF-beta1 inhibition. Notably, human complement-opsonized apoptotic bodies induce production of similar TGF-beta1-transporting vesicles in monocytes, suggesting that the early immune response might be suppressed through this CR3-dependent anti-inflammatory vesicle pathway.

Authors: L. D. Halder, E. A. H. Jo, M. Z. Hasan, M. Ferreira-Gomes, T. Kruger, M. Westermann, D. I. Palme, G. Rambach, N. Beyersdorf, C. Speth, I. D. Jacobsen, O. Kniemeyer, B. Jungnickel, P. F. Zipfel, C. Skerka

Date Published: 11th May 2020

Publication Type: Not specified

Abstract (Expand)

Fungal spores and hyphal fragments play an important role as allergens in respiratory diseases. In this study, we performed trypsin shaving and secretome analyses to identify the surface-exposed proteins and secreted/shed proteins of Aspergillus fumigatus conidia, respectively. We investigated the surface proteome under different conditions, including temperature variation and germination. We found that the surface proteome of resting A. fumigatus conidia is not static but instead unexpectedly dynamic, as evidenced by drastically different surface proteomes under different growth conditions. Knockouts of two abundant A. fumigatus surface proteins, ScwA and CweA, were found to function only in fine-tuning the cell wall stress response, implying that the conidial surface is very robust against perturbations. We then compared the surface proteome of A. fumigatus to other allergy-inducing molds, including Alternaria alternata, Penicillium rubens, and Cladosporium herbarum, and performed comparative proteomics on resting and swollen conidia, as well as secreted proteins from germinating conidia. We detected 125 protein ortholog groups, including 80 with putative catalytic activity, in the extracellular region of all four molds, and 42 nonorthologous proteins produced solely by A. fumigatus. Ultimately, this study highlights the dynamic nature of the A. fumigatus conidial surface and provides targets for future diagnostics and immunotherapy.

Authors: M. G. Blango, A. Pschibul, F. Rivieccio, T. Kruger, M. Rafiq, L. J. Jia, T. Zheng, M. Goldmann, V. Voltersen, J. Li, G. Panagiotou, O. Kniemeyer, A. A. Brakhage

Date Published: 1st May 2020

Publication Type: Not specified

Abstract (Expand)

The capacity of Candida albicans to reversibly change its morphology between yeast and filamentous stages is crucial for its virulence. Formation of hyphae correlates with the upregulation of genes ALS3 and ECE1, which are involved in pathogenicity processes such as invasion, iron acquisition, and host cell damage. The global repressor Tup1 and its cofactor Nrg1 are considered to be the main antagonists of hyphal development in C. albicans However, our experiments revealed that Tup1, but not Nrg1, was required for full expression of ALS3 and ECE1 In contrast to NRG1, overexpression of TUP1 was found to inhibit neither filamentous growth nor transcription of ALS3 and ECE1 In addition, we identified the transcription factor Ahr1 as being required for full expression of both genes. A hyperactive version of Ahr1 bound directly to the promoters of ALS3 and ECE1 and induced their transcription even in the absence of environmental stimuli. This regulation worked even in the absence of the crucial hyphal growth regulators Cph1 and Efg1 but was dependent on the presence of Tup1. Overall, our results show that Ahr1 and Tup1 are key contributors in the complex regulation of virulence-associated genes in the different C. albicans morphologies.IMPORTANCE Candida albicans is a major human fungal pathogen and the leading cause of systemic Candida infections. In recent years, Als3 and Ece1 were identified as important factors for fungal virulence. Transcription of both corresponding genes is closely associated with hyphal growth. Here, we describe how Tup1, normally a global repressor of gene expression as well as of filamentation, and the transcription factor Ahr1 contribute to full expression of ALS3 and ECE1 in C. albicans hyphae. Both regulators are required for high mRNA amounts of the two genes to ensure functional relevant protein synthesis and localization. These observations identified a new aspect of regulation in the complex transcriptional control of virulence-associated genes in C. albicans.

Authors: S. Ruben, E. Garbe, S. Mogavero, D. Albrecht-Eckardt, D. Hellwig, A. Hader, T. Kruger, K. Gerth, I. D. Jacobsen, O. Elshafee, S. Brunke, K. Hunniger, O. Kniemeyer, A. A. Brakhage, J. Morschhauser, B. Hube, S. Vylkova, O. Kurzai, R. Martin

Date Published: 28th Apr 2020

Publication Type: Not specified

Abstract (Expand)

Super-resolution microscopy has evolved as a powerful method for subdiffraction-resolution fluorescence imaging of cells and cellular organelles, but requires sophisticated and expensive installations. Expansion microscopy (ExM), which is based on the physical expansion of the cellular structure of interest, provides a cheap alternative to bypass the diffraction limit and enable super-resolution imaging on a conventional fluorescence microscope. While ExM has shown impressive results for the magnified visualization of proteins and RNAs in cells and tissues, it has not yet been applied in fungi, mainly due to their complex cell wall. Here we developed a method that enables reliable isotropic expansion of ascomycetes and basidiomycetes upon treatment with cell wall degrading enzymes. Confocal laser scanning microscopy (CLSM) and structured illumination microscopy (SIM) images of 4.5-fold expanded sporidia of Ustilago maydis expressing fluorescent fungal rhodopsins and hyphae of Fusarium oxysporum or Aspergillus fumigatus expressing either histone H1-mCherry together with Lifeact-sGFP or mRFP targeted to mitochondria, revealed details of subcellular structures with an estimated spatial resolution of around 30 nm. ExM is thus well suited for cell biology studies in fungi on conventional fluorescence microscopes.

Authors: R. Gotz, S. Panzer, N. Trinks, J. Eilts, J. Wagener, D. Turra, A. Di Pietro, M. Sauer, U. Terpitz

Date Published: 23rd Apr 2020

Publication Type: Not specified

Abstract (Expand)

Polymorphonuclear granulocytes (PMNs) are indispensable for controlling life-threatening fungal infections. In addition to various effector mechanisms, PMNs also produce extracellular vesicles (EVs). Their contribution to antifungal defense has remained unexplored. We reveal that the clinically important human-pathogenic fungus Aspergillus fumigatus triggers PMNs to release a distinct set of antifungal EVs (afEVs). Proteome analyses indicated that afEVs are enriched in antimicrobial proteins. The cargo and the release kinetics of EVs are modulated by the fungal strain confronted. Tracking of afEVs indicated that they associated with fungal cells and even entered fungal hyphae, resulting in alterations in the morphology of the fungal cell wall and dose-dependent antifungal effects. To assess as a proof of concept whether the antimicrobial proteins found in afEVs might contribute to growth inhibition of hyphae when present in the fungal cytoplasm, two human proteins enriched in afEVs, cathepsin G and azurocidin, were heterologously expressed in fungal hyphae. This led to reduced fungal growth relative to that of a control strain producing the human retinol binding protein 7. In conclusion, extracellular vesicles produced by neutrophils in response to A. fumigatus infection are able to associate with the fungus, limit growth, and elicit cell damage by delivering antifungal cargo. This finding offers an intriguing, previously overlooked mechanism of antifungal defense against A. fumigatus IMPORTANCE Invasive fungal infections caused by the mold Aspergillus fumigatus are a growing concern in the clinic due to the increasing use of immunosuppressive therapies and increasing antifungal drug resistance. These infections result in high rates of mortality, as treatment and diagnostic options remain limited. In healthy individuals, neutrophilic granulocytes are critical for elimination of A. fumigatus from the host; however, the exact extracellular mechanism of neutrophil-mediated antifungal activity remains unresolved. Here, we present a mode of antifungal defense employed by human neutrophils against A. fumigatus not previously described. We found that extracellular vesicles produced by neutrophils in response to A. fumigatus infection are able to associate with the fungus, limit growth, and elicit cell damage by delivering antifungal cargo. In the end, antifungal extracellular vesicle biology provides a significant step forward in our understanding of A. fumigatus host pathogenesis and opens up novel diagnostic and therapeutic possibilities.

Authors: I. A. Shopova, I. Belyaev, P. Dasari, S. Jahreis, M. C. Stroe, Z. Cseresnyes, A. K. Zimmermann, A. Medyukhina, C. M. Svensson, T. Kruger, V. Szeifert, S. Nietzsche, T. Conrad, M. G. Blango, O. Kniemeyer, M. von Lilienfeld-Toal, P. F. Zipfel, E. Ligeti, M. T. Figge, A. A. Brakhage

Date Published: 14th Apr 2020

Publication Type: Not specified

Abstract (Expand)

The gut microbiota has the potential to influence the efficacy of cancer therapy. Here, we investigated the contribution of the intestinal microbiome on treatment outcomes in a heterogeneous cohort that included multiple cancer types to identify microbes with a global impact on immune response. Human gut metagenomic analysis revealed that responder patients had significantly higher microbial diversity and different microbiota compositions compared to non-responders. A machine-learning model was developed and validated in an independent cohort to predict treatment outcomes based on gut microbiota composition and functional repertoires of responders and non-responders. Specific species, Bacteroides ovatus and Bacteroides xylanisolvens, were positively correlated with treatment outcomes. Oral gavage of these responder bacteria significantly increased the efficacy of erlotinib and induced the expression of CXCL9 and IFN-gamma in a murine lung cancer model. These data suggest a predictable impact of specific constituents of the microbiota on tumor growth and cancer treatment outcomes with implications for both prognosis and therapy.

Authors: Y. Heshiki, R. Vazquez-Uribe, J. Li, Y. Ni, S. Quainoo, L. Imamovic, J. Li, M. Sorensen, B. K. C. Chow, G. J. Weiss, A. Xu, M. O. A. Sommer, G. Panagiotou

Date Published: 5th Mar 2020

Publication Type: Not specified

Abstract (Expand)

Pathogenic microorganisms exploit host metabolism for sustained survival by rewiring its metabolic interactions. Therefore, several metabolic changes are induced in both pathogen and host cells in the course of infection. A systems-based approach to elucidate those changes includes the integrative use of genome-scale metabolic networks and molecular omics data, with the overall goal of better characterizing infection mechanisms for novel treatment strategies. This review focuses on novel aspects of metabolism-oriented systems-based investigation of pathogen-human interactions. The reviewed approaches are the generation of dual-omics data for the characterization of metabolic signatures of pathogen-host interactions, the reconstruction of pathogen-host integrated genome-scale metabolic networks, which has a high potential to be applied to pathogen-gut microbiota interactions, and the structure-based analysis of enzymes playing role in those interactions. The integrative use of those approaches will pave the way for the identification of novel biomarkers and drug targets for the prediction and prevention of infectious diseases.

Authors: T. Cakir, G. Panagiotou, R. Uddin, S. Durmus

Date Published: 3rd Mar 2020

Publication Type: Not specified

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