Publications

Abstract (Expand)

Candida albicans is a leading cause of life-threatening hospital-acquired infections and can lead to Candidemia with sepsis-like symptoms and high mortality rates. We reconstructed a genome-scale C. albicans metabolic model to investigate bacterial-fungal metabolic interactions in the gut as determinants of fungal abundance. We optimized the predictive capacity of our model using wild type and mutant C. albicans growth data and used it for in silico metabolic interaction predictions. Our analysis of more than 900 paired fungal-bacterial metabolic models predicted key gut bacterial species modulating C. albicans colonization levels. Among the studied microbes, Alistipes putredinis was predicted to negatively affect C. albicans levels. We confirmed these findings by metagenomic sequencing of stool samples from 24 human subjects and by fungal growth experiments in bacterial spent media. Furthermore, our pairwise simulations guided us to specific metabolites with promoting or inhibitory effect to the fungus when exposed in defined media under carbon and nitrogen limitation. Our study demonstrates that in silico metabolic prediction can lead to the identification of gut microbiome features that can significantly affect potentially harmful levels of C. albicans.

Authors: Mohammad Mirhakkak, Sascha Schäuble, Tilman Klassert, S. Brunke, Philipp Brandt, D. Loos, R. V. Uribe, F. Senne de Oliveira Lino, Y. Ni, Slavena Vylkova, Hortense Slevogt, Bernhard Hube, Esther Weiß, M. O. A. Sommer, Gianni Panagiotou

Date Published: 15th Dec 2020

Journal: ISME J

Abstract (Expand)

Invasive pulmonary aspergillosis (IPA) is a severe infection that is difficult to diagnose due to the ubiquitous presence of fungal spores, the underlying diseases of risk patients, and limitations of currently available markers. In this study, we performed a comprehensive liquid chromatography tandem mass spectrometry (LC-MS/MS)-based identification of host and fungal proteins expressed during IPA in mice and humans. The proteomic analysis of bronchoalveolar lavage samples of individual IPA and control cases allowed the description of common host factors that had significantly increased abundance in both infected animals and IPA patients compared to their controls. Although increased levels of these individual host proteins might not be sufficient to distinguish bacterial from fungal infection, a combination of these markers might be beneficial to improve diagnosis. We also identified 16 fungal proteins that were specifically detected during infection and may be valuable candidates for biomarker evaluation.

Authors: S. Machata, Wolfgang Müller, R. Lehmann, Patricia Sieber, Gianni Panagiotou, A. Carvalho, C. Cunha, K. Lagrou, J. Maertens, Hortense Slevogt, Ilse Jacobsen

Date Published: 12th Oct 2020

Journal: Virulence

Abstract (Expand)

Mucormycosis is an emergent, fatal fungal infection of humans and warm-blooded animals caused by species of the order Mucorales. Immune cells of the innate immune system serve as the first line of defence against inhaled spores. Alveolar macrophages were challenged with the mucoralean fungus Lichtheimia corymbifera and subjected to biotinylation and streptavidin enrichment procedures followed by LC-MS/MS analyses. A total of 28 host proteins enriched for binding to macrophage-L. corymbifera interaction. Among those, the HSP70-family protein Hspa8 was found to be predominantly responsive to living and heat-killed spores of a virulent and an attenuated strain of L. corymbifera. Confocal scanning laser microscopy of infected macrophages revealed colocalization of Hspa8 with phagocytosed spores of L. corymbifera. The amount of detectable Hspa8 was dependent on the multiplicity of infection. Incubation of alveolar macrophages with an anti-Hspa8 antibody prior to infection reduced their capability to phagocytose spores of L. corymbifera. In contrast, anti-Hspa8 antibodies did not abrogate the phagocytosis of Aspergillus fumigatus conidia by macrophages. These results suggest an important contribution of the heat-shock family protein Hspa8 in the recognition of spores of the mucoralean fungus L. corymbifera by host alveolar macrophages and define a potential immunomodulatory therapeutic target.

Authors: M. I. A. Hassan, J. M. Kruse, Thomas Krüger, H. M. Dahse, Z. Cseresnyes, M. G. Blango, Hortense Slevogt, F. Horhold, V. Ast, R. Konig, Marc Thilo Figge, Olaf Kniemeyer, Axel Brakhage, Kerstin Voigt

Date Published: 26th Jun 2020

Journal: Environ Microbiol

Abstract (Expand)

Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1, CD66a) is a receptor for Candida albicans. It is crucial for the immune response of intestinal epithelial cells to this opportunistic pathogen. Moreover, CEACAM1 is of importance for the mucosal colonization by different bacterial pathogens. We therefore studied the influence of the human CEACAM1 receptor in human CEACAM1-transgenic mice on the C. albicans colonization and infection utilizing a colonization/dissemination and a systemic infection mouse model. Our results showed no alterations in the host response between the transgenic mice and the wild-type littermates to the C. albicans infections. Both mouse strains showed comparable C. albicans colonization and mycobiota, similar fungal burdens in various organs, and a similar survival in the systemic infection model. Interestingly, some of the mice treated with anti-bacterial antibiotics (to prepare them for C. albicans colonization via oral infection) also showed a strong reduction in endogenous fungi instead of the normally observed increase in fungal numbers. This was independent of the expression of human CEACAM1. In the systemic infection model, the human CEACAM1 expression was differentially regulated in the kidneys and livers of Candida-infected transgenic mice. Notably, in the kidneys, a total loss of the largest human CEACAM1 isoform was observed. However, the overwhelming immune response induced in the systemic infection model likely covered any CEACAM1-specific effects in the transgenic animals. In vitro studies using bone marrow-derived neutrophils from both mouse strains also revealed no differences in their reaction to C. albicans. In conclusion, in contrast to bacterial pathogens interacting with CEACAM1 on different mucosal surfaces, the human CEACAM1-transgenic mice did not reveal a role of human CEACAM1 in the in vivo candidiasis models used here. Further studies and different approaches will be needed to reveal a putative role of CEACAM1 in the host response to C. albicans.

Authors: Esther Klaile, M. M. Muller, C. Zubiria-Barrera, S. Brehme, Tilman Klassert, M. Stock, A. Durotin, T. D. Nguyen, S. Feer, B. B. Singer, Peter Zipfel, Sven Rudolphi, Ilse Jacobsen, Hortense Slevogt

Date Published: 19th Dec 2019

Journal: Front Microbiol

Abstract (Expand)

Fungi, usually present as commensals, are a major cause of opportunistic infections in immunocompromised patients. Such infections, if not diagnosed or treated properly, can prove fatal. However, in most cases healthy individuals are able to avert the fungal attacks by mounting proper antifungal immune responses. Among the pattern recognition receptors (PRRs), C-type lectin receptors (CLRs) are the major players in antifungal immunity. CLRs can recognize carbohydrate ligands, such as beta-glucans and mannans, which are mainly found on fungal cell surfaces. They induce proinflammatory immune reactions, including phagocytosis, oxidative burst, cytokine, and chemokine production from innate effector cells, as well as activation of adaptive immunity via Th17 responses. CLRs such as Dectin-1, Dectin-2, Mincle, mannose receptor (MR), and DC-SIGN can recognize many disease-causing fungi and also collaborate with each other as well as other PRRs in mounting a fungi-specific immune response. Mutations in these receptors affect the host response and have been linked to a higher risk in contracting fungal infections. This review focuses on how CLRs on various immune cells orchestrate the antifungal response and on the contribution of single nucleotide polymorphisms in these receptors toward the risk of developing such infections.

Authors: S. Goyal, J. C. Castrillon-Betancur, Esther Klaile, Hortense Slevogt

Date Published: 20th Jun 2018

Journal: Front Immunol

Abstract (Expand)

The human plasma contact system is an immune surveillance system activated by the negatively charged surfaces of bacteria and fungi and includes the kallikrein-kinin, the coagulation, and the fibrinolytic systems. Previous work shows that the contact system also activates complement, and that plasma enzymes like kallikrein, plasmin, thrombin, and FXII are involved in the activation process. Here, we show for the first time that kallikrein cleaves the central complement component C3 directly to yield active components C3b and C3a. The cleavage site within C3 is identical to that recognized by the C3 convertase. Also, kallikrein-generated C3b forms C3 convertases, which trigger the C3 amplification loop. Since kallikrein also cleaves factor B to yield Bb and Ba, kallikrein alone can trigger complement activation. Kallikrein-generated C3 convertases are inhibited by factor H; thus, the kallikrein activation pathway merges with the amplification loop of the alternative pathway. Taken together, these data suggest that activation of the contact system locally enhances complement activation on cell surfaces. The human pathogenic microbe Candida albicans activates the contact system in normal human serum. However, C. albicans immediately recruits factor H to the surface, thereby evading the alternative and likely kallikrein-mediated complement pathways.

Authors: Sarah Irmscher, N. Doring, Luke Donald Halder, E. A. H. Jo, I. Kopka, C. Dunker, Ilse Jacobsen, S. Luo, Hortense Slevogt, S. Lorkowski, Niklas Beyersdorf, Peter Zipfel, Christine Skerka

Date Published: 14th Dec 2017

Journal: J Innate Immun

Abstract (Expand)

Helicobacter pylori specifically colonizes the human gastric epithelium and is the major causative agent for ulcer disease and gastric cancer development. Here, we identify members of the carcinoembryonic antigen-related cell adhesion molecule (CEACAM) family as receptors of H. pylori and show that HopQ is the surface-exposed adhesin that specifically binds human CEACAM1, CEACAM3, CEACAM5 and CEACAM6. HopQ-CEACAM binding is glycan-independent and targeted to the N-domain. H. pylori binding induces CEACAM1-mediated signalling, and the HopQ-CEACAM1 interaction enables translocation of the virulence factor CagA into host cells and enhances the release of pro-inflammatory mediators such as interleukin-8. Based on the crystal structure of HopQ, we found that a beta-hairpin insertion (HopQ-ID) in HopQ's extracellular 3+4 helix bundle domain is important for CEACAM binding. A peptide derived from this domain competitively inhibits HopQ-mediated activation of the Cag virulence pathway, as genetic or antibody-mediated abrogation of the HopQ function shows. Together, our data suggest the HopQ-CEACAM1 interaction to be a potentially promising novel therapeutic target to combat H. pylori-associated diseases.

Authors: A. Javaheri, T. Kruse, K. Moonens, R. Mejias-Luque, A. Debraekeleer, C. I. Asche, N. Tegtmeyer, B. Kalali, N. C. Bach, S. A. Sieber, D. J. Hill, V. Koniger, C. R. Hauck, R. Moskalenko, R. Haas, D. H. Busch, Esther Klaile, Hortense Slevogt, A. Schmidt, S. Backert, H. Remaut, B. B. Singer, M. Gerhard

Date Published: 18th Oct 2016

Journal: Nat Microbiol

Abstract (Expand)

The human restricted pathogen Moraxella catarrhalis is an important causal agent for exacerbations in chronic obstructive lung disease (COPD) in adults. In such patients, increased numbers of granulocytes are present in the airways, which correlate with bacteria-induced exacerbations and severity of the disease. Our study investigated whether the interaction of M. catarrhalis with the human granulocyte-specific carcinoembryonic antigen-related cell adhesion molecule (CEACAM)-3 is linked to NF-kappaB activation, resulting in chemokine production. Granulocytes from healthy donors and NB4 cells were infected with M. catarrhalis in the presence of different inhibitors, blocking antibodies and siRNA. The supernatants were analysed by ELISA for chemokines. NF-kappaB activation was determined using a luciferase reporter gene assay and chromatin-immunoprecipitation. We found evidence that the specific engagement of CEACAM3 by Moraxella catarrhalis ubiquitous surface protein A1 (UspA1) results in the activation of pro-inflammatory events, such as degranulation of neutrophils, ROS production and chemokine secretion. The interaction of UspA1 with CEACAM3 induced the activation of the NF-kappaB pathway via Syk and the Card9 pathway and was dependent on the phosphorylation of the CEACAM3 ITAM -like motif. These findings suggest that the CEACAM3 signalling in neutrophils is able to specifically modulate airway inflammation caused by infection with M. catarrhalis.

Authors: A. Heinrich, K. A. Heyl, E. Klaile, Tobias Müller, Tilman Klassert, A. Wiessner, K. Fischer, R. R. Schumann, U. Seifert, K. Riesbeck, A. Moter, B. B. Singer, S. Bachmann, Hortense Slevogt

Date Published: 3rd Apr 2016

Journal: Cell Microbiol

Abstract (Expand)

Beyond its well-documented role in reproduction, embryogenesis and maintenance of body tissues, vitamin A has attracted considerable attention due to its immunomodulatory effects on both the innate and the adaptive immune responses. In infectious diseases, vitamin A has been shown to have a host-protective effect in infections of bacterial, viral or protozoan origin. Nevertheless, its impact in fungal infections remains unknown. Meanwhile, the frequency of invasive mycoses keeps on growing, with Candida albicans being the major opportunistic fungal pathogen and associated with high mortality. In the present work, we explored the impact of all-trans retinoic acid (atRA), the most active metabolite of vitamin A, on the innate immune response against C. albicans in human monocytes. Our results show a strong immunomodulatory role for atRA, leading to a significant down-regulation of the fungi-induced expression and secretion of the pro-inflammatory cytokines TNFalpha, IL6 and IL12. Moreover, atRA significantly suppressed the expression of Dectin-1, a major fungal pattern recognition receptor, as well as the Dectin-1-dependent cytokine production. Both RAR-dependent and RAR-independent mechanisms seem to play a role in the atRA-mediated immunomodulation. Our findings open a new direction to elucidate the role of vitamin A on the immune function during fungal infections.

Authors: Tilman Klassert, A. Hanisch, J. Brauer, E. Klaile, K. A. Heyl, M. K. Mansour, J. M. Tam, J. M. Vyas, Hortense Slevogt

Date Published: 17th Aug 2014

Journal: Med Microbiol Immunol

Abstract

Not specified

Authors: A. Schmoldt, H. F. Benthe, G. Haberland

Date Published: 1st Sep 1975

Journal: Biochem Pharmacol

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