@article{LeonhardtSpielbergWeberetal.2015, author = {Leonhardt, Ines and Spielberg, Steffi and Weber, Michael and Albrecht-Eckardt, Daniela and Bl{\"a}ss, Markus and Claus, Ralf and Barz, Dagmar and Scherlach, Kirstin and Hertweck, Christian and L{\"o}ffler, J{\"u}rgen and H{\"u}nniger, Kerstin and Kurzai, Oliver}, title = {The fungal quorum-sensing molecule farnesol activates innate immune cells but suppresses cellular adaptive immunity}, series = {mBio}, volume = {6}, journal = {mBio}, number = {2}, doi = {10.1128/mBio.00143-15}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-143756}, pages = {e00143-15}, year = {2015}, abstract = {Farnesol, produced by the polymorphic fungus Candida albicans, is the first quorum-sensing molecule discovered in eukaryotes. Its main function is control of C. albicans filamentation, a process closely linked to pathogenesis. In this study, we analyzed the effects of farnesol on innate immune cells known to be important for fungal clearance and protective immunity. Farnesol enhanced the expression of activation markers on monocytes (CD86 and HLA-DR) and neutrophils (CD66b and CD11b) and promoted oxidative burst and the release of proinflammatory cytokines (tumor necrosis factor alpha [TNF-\(\alpha\)] and macrophage inflammatory protein 1 alpha [MIP-1 \(\alpha\)]). However, this activation did not result in enhanced fungal uptake or killing. Furthermore, the differentiation of monocytes to immature dendritic cells (iDC) was significantly affected by farnesol. Several markers important for maturation and antigen presentation like CD1a, CD83, CD86, and CD80 were significantly reduced in the presence of farnesol. Furthermore, farnesol modulated migrational behavior and cytokine release and impaired the ability of DC to induce T cell proliferation. Of major importance was the absence of interleukin 12 (IL-12) induction in iDC generated in the presence of farnesol. Transcriptome analyses revealed a farnesol-induced shift in effector molecule expression and a down-regulation of the granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor during monocytes to iDC differentiation. Taken together, our data unveil the ability of farnesol to act as a virulence factor of C. albicans by influencing innate immune cells to promote inflammation and mitigating the Th1 response, which is essential for fungal clearance.}, language = {en} } @article{RemmeleLutherBalkenholetal.2015, author = {Remmele, Christian W. and Luther, Christian H. and Balkenhol, Johannes and Dandekar, Thomas and M{\"u}ller, Tobias and Dittrich, Marcus T.}, title = {Integrated inference and evaluation of host-fungi interaction networks}, series = {Frontiers in Microbiology}, volume = {6}, journal = {Frontiers in Microbiology}, number = {764}, doi = {10.3389/fmicb.2015.00764}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-148278}, year = {2015}, abstract = {Fungal microorganisms frequently lead to life-threatening infections. Within this group of pathogens, the commensal Candida albicans and the filamentous fungus Aspergillus fumigatus are by far the most important causes of invasive mycoses in Europe. A key capability for host invasion and immune response evasion are specific molecular interactions between the fungal pathogen and its human host. Experimentally validated knowledge about these crucial interactions is rare in literature and even specialized host pathogen databases mainly focus on bacterial and viral interactions whereas information on fungi is still sparse. To establish large-scale host fungi interaction networks on a systems biology scale, we develop an extended inference approach based on protein orthology and data on gene functions. Using human and yeast intraspecies networks as template, we derive a large network of pathogen host interactions (PHI). Rigorous filtering and refinement steps based on cellular localization and pathogenicity information of predicted interactors yield a primary scaffold of fungi human and fungi mouse interaction networks. Specific enrichment of known pathogenicity-relevant genes indicates the biological relevance of the predicted PHI. A detailed inspection of functionally relevant subnetworks reveals novel host fungal interaction candidates such as the Candida virulence factor PLB1 and the anti-fungal host protein APP. Our results demonstrate the applicability of interolog-based prediction methods for host fungi interactions and underline the importance of filtering and refinement steps to attain biologically more relevant interactions. This integrated network framework can serve as a basis for future analyses of high-throughput host fungi transcriptome and proteome data.}, language = {en} } @article{IrmerTarazonaSasseetal.2015, author = {Irmer, Henriette and Tarazona, Sonia and Sasse, Christoph and Olbermann, Patrick and Loeffler, J{\"u}rgen and Krappmann, Sven and Conesa, Ana and Braus, Gerhard H.}, title = {RNAseq analysis of Aspergillus fumigatus in blood reveals a just wait and see resting stage behavior}, series = {BMC Genomics}, volume = {16}, journal = {BMC Genomics}, number = {640}, doi = {10.1186/s12864-015-1853-1}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-151390}, year = {2015}, abstract = {Background: Invasive aspergillosis is started after germination of Aspergillus fumigatus conidia that are inhaled by susceptible individuals. Fungal hyphae can grow in the lung through the epithelial tissue and disseminate hematogenously to invade into other organs. Low fungaemia indicates that fungal elements do not reside in the bloodstream for long. Results: We analyzed whether blood represents a hostile environment to which the physiology of A. fumigatus has to adapt. An in vitro model of A. fumigatus infection was established by incubating mycelium in blood. Our model allowed to discern the changes of the gene expression profile of A. fumigatus at various stages of the infection. The majority of described virulence factors that are connected to pulmonary infections appeared not to be activated during the blood phase. Three active processes were identified that presumably help the fungus to survive the blood environment in an advanced phase of the infection: iron homeostasis, secondary metabolism, and the formation of detoxifying enzymes. Conclusions: We propose that A. fumigatus is hardly able to propagate in blood. After an early stage of sensing the environment, virtually all uptake mechanisms and energy-consuming metabolic pathways are shut-down. The fungus appears to adapt by trans-differentiation into a resting mycelial stage. This might reflect the harsh conditions in blood where A. fumigatus cannot take up sufficient nutrients to establish self-defense mechanisms combined with significant growth.}, language = {en} } @article{DuehringGermerodtSkerkaetal.2015, author = {D{\"u}hring, Sybille and Germerodt, Sebastian and Skerka, Christine and Zipfel, Peter F. and Dandekar, Thomas and Schuster, Stefan}, title = {Host-pathogen interactions between the human innate immune system and Candida albicans - understanding and modeling defense and evasion strategies}, series = {Frontiers in Microbiology}, volume = {6}, journal = {Frontiers in Microbiology}, number = {625}, doi = {10.3389/fmicb.2015.00625}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-151621}, year = {2015}, abstract = {The diploid, polymorphic yeast Candida albicans is one of the most important human pathogenic fungi. C. albicans can grow, proliferate and coexist as a commensal on or within the human host for a long time. However, alterations in the host environment can render C. albicans virulent. In this review, we describe the immunological cross-talk between C. albicans and the human innate immune system. We give an overview in form of pairs of human defense strategies including immunological mechanisms as well as general stressors such as nutrient limitation, pH, fever etc. and the corresponding fungal response and evasion mechanisms. Furthermore, Computational Systems Biology approaches to model and investigate these complex interactions are highlighted with a special focus on game-theoretical methods and agent-based models. An outlook on interesting questions to be tackled by Systems Biology regarding entangled defense and evasion mechanisms is given.}, language = {en} }