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4 Publications visible to you, out of a total of 4
The impact of episporic modification of Lichtheimia corymbifera on virulence and interaction with phagocytes.

Abstract (Expand)

Fungal infections caused by the ancient lineage Mucorales are emerging and increasingly reported in humans. Comprehensive surveys on promising attributes from a multitude of possible virulence factors … are limited and so far, focused on Mucor and Rhizopus. This study addresses a systematic approach to monitor phagocytosis after physical and enzymatic modification of the outer spore wall of Lichtheimia corymbifera, one of the major causative agents of mucormycosis. Episporic modifications were performed and their consequences on phagocytosis, intracellular survival and virulence by murine alveolar macrophages and in an invertebrate infection model were elucidated. While depletion of lipids did not affect the phagocytosis of both strains, delipidation led to attenuation of LCA strain but appears to be dispensable for infection with LCV strain in the settings used in this study. Combined glucano-proteolytic treatment was necessary to achieve a significant decrease of virulence of the LCV strain in Galleria mellonella during maintenance of the full potential for spore germination as shown by a novel automated germination assay. Proteolytic and glucanolytic treatments largely increased phagocytosis compared to alive resting and swollen spores. Whilst resting spores barely (1-2%) fuse to lysosomes after invagination in to phagosomes, spore trypsinization led to a 10-fold increase of phagolysosomal fusion as measured by intracellular acidification. This is the first report of a polyphasic measurement of the consequences of episporic modification of a mucormycotic pathogen in spore germination, spore surface ultrastructure, phagocytosis, stimulation of Toll-like receptors (TLRs), phagolysosomal fusion and intracellular acidification, apoptosis, generation of reactive oxygen species (ROS) and virulence.

Authors: M. I. A. Hassan, M. Keller, M. Hillger, U. Binder, S. Reuter, K. Herold, A. Telagathoti, H. M. Dahse, S. Wicht, N. Trinks, S. Nietzsche, T. Deckert-Gaudig, V. Deckert, R. Mrowka, U. Terpitz, H. Peter Saluz, K. Voigt

Date Published: 18th Feb 2021

Publication Type: Not specified

Reconstituting NK Cells After Allogeneic Stem Cell Transplantation Show Impaired Response to the Fungal Pathogen Aspergillus fumigatus.

Abstract (Expand)

Delayed natural killer (NK) cell reconstitution after allogeneic stem cell transplantation (alloSCT) is associated with a higher risk of developing invasive aspergillosis. The interaction of NK cells … with the human pathogen Aspergillus (A.) fumigatus is mediated by the fungal recognition receptor CD56, which is relocated to the fungal interface after contact. Blocking of CD56 signaling inhibits the fungal mediated chemokine secretion of MIP-1alpha, MIP-1beta, and RANTES and reduces cell activation, indicating a functional role of CD56 in fungal recognition. We collected peripheral blood from recipients of an allograft at defined time points after alloSCT (day 60, 90, 120, 180). NK cells were isolated, directly challenged with live A. fumigatus germ tubes, and cell function was analyzed and compared to healthy age and gender-matched individuals. After alloSCT, NK cells displayed a higher percentage of CD56(bright)CD16(dim) cells throughout the time of blood collection. However, CD56 binding and relocalization to the fungal contact side were decreased. We were able to correlate this deficiency to the administration of corticosteroid therapy that further negatively influenced the secretion of MIP-1alpha, MIP-1beta, and RANTES. As a consequence, the treatment of healthy NK cells ex vivo with corticosteroids abrogated chemokine secretion measured by multiplex immunoassay. Furthermore, we analyzed NK cells regarding their actin cytoskeleton by Structured Illumination Microscopy (SIM) and flow cytometry and demonstrate an actin dysfunction of NK cells shown by reduced F-actin content after fungal co-cultivation early after alloSCT. This dysfunction remains until 180 days post-alloSCT, concluding that further actin-dependent cellular processes may be negatively influenced after alloSCT. To investigate the molecular pathomechansism, we compared CD56 receptor mobility on the plasma membrane of healthy and alloSCT primary NK cells by single-molecule tracking. The results were very robust and reproducible between tested conditions which point to a different molecular mechanism and emphasize the importance of proper CD56 mobility.

Authors: E. Weiss, J. Schlegel, U. Terpitz, M. Weber, J. Linde, A. L. Schmitt, K. Hunniger, L. Marischen, F. Gamon, J. Bauer, C. Loffler, O. Kurzai, C. O. Morton, M. Sauer, H. Einsele, J. Loeffler

Date Published: 5th Oct 2020

Publication Type: Not specified

Expansion Microscopy for Cell Biology Analysis in Fungi.

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

Three-Dimensional Light Sheet Fluorescence Microscopy of Lungs To Dissect Local Host Immune-Aspergillus fumigatus Interactions.

Abstract (Expand)

Aspergillus fumigatus is an opportunistic fungal pathogen that can cause life-threatening invasive lung infections in immunodeficient patients. The cellular and molecular processes of infection during … onset, establishment, and progression of A. fumigatus infections are highly complex and depend on both fungal attributes and the immune status of the host. Therefore, preclinical animal models are of paramount importance to investigate and gain better insight into the infection process. Yet, despite their extensive use, commonly employed murine models of invasive pulmonary aspergillosis are not well understood due to analytical limitations. Here, we present quantitative light sheet fluorescence microscopy (LSFM) to describe fungal growth and the local immune response in whole lungs at cellular resolution within its anatomical context. We analyzed three very common murine models of pulmonary aspergillosis based on immunosuppression with corticosteroids, chemotherapy-induced leukopenia, or myeloablative irradiation. LSFM uncovered distinct architectures of fungal growth and degrees of tissue invasion in each model. Furthermore, LSFM revealed the spatial distribution, interaction, and activation of two key immune cell populations in antifungal defense: alveolar macrophages and polymorphonuclear neutrophils. Interestingly, the patterns of fungal growth correlated with the detected effects of the immunosuppressive regimens on the local immune cell populations. Moreover, LSFM demonstrates that the commonly used intranasal route of spore administration did not result in complete intra-alveolar deposition, as about 80% of fungal growth occurred outside the alveolar space. Hence, characterization by LSFM is more rigorous than by previously used methods employing murine models of invasive pulmonary aspergillosis and pinpoints their strengths and limitations.IMPORTANCE The use of animal models of infection is essential to advance our understanding of the complex host-pathogen interactions that take place during Aspergillus fumigatus lung infections. As in the case of humans, mice need to suffer an immune imbalance in order to become susceptible to invasive pulmonary aspergillosis (IPA), the most serious infection caused by A. fumigatus There are several immunosuppressive regimens that are routinely used to investigate fungal growth and/or immune responses in murine models of invasive pulmonary aspergillosis. However, the precise consequences of the use of each immunosuppressive model for the local immune populations and for fungal growth are not completely understood. Here, to pin down the scenarios involving commonly used IPA models, we employed light sheet fluorescence microscopy (LSFM) to analyze whole lungs at cellular resolution. Our results will be valuable to optimize and refine animal models to maximize their use in future research.

Authors: J. Amich, Z. Mokhtari, M. Strobel, E. Vialetto, D. Sheta, Y. Yu, J. Hartweg, N. Kalleda, K. J. Jarick, C. Brede, A. L. Jordan-Garrote, S. Thusek, K. Schmiedgen, B. Arslan, J. Pinnecker, C. R. Thornton, M. Gunzer, S. Krappmann, H. Einsele, K. G. Heinze, A. Beilhack

Date Published: 4th Feb 2020

Publication Type: Not specified

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