@article{VendelovaAshourBlanketal.2018, author = {Vendelova, Emilia and Ashour, Diyaaeldin and Blank, Patrick and Erhard, Florian and Saliba, Antoine-Emmanuel and Kalinke, Ulrich and Lutz, Manfred B.}, title = {Tolerogenic transcriptional signatures of steady-state and pathogen-induced dendritic cells}, series = {Frontiers in Immunology}, volume = {9}, journal = {Frontiers in Immunology}, number = {333}, doi = {10.3389/fimmu.2018.00333}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-175636}, year = {2018}, abstract = {Dendritic cells (DCs) are key directors of tolerogenic and immunogenic immune responses. During the steady state, DCs maintain T cell tolerance to self-antigens by multiple mechanisms including inducing anergy, deletion, and Treg activity. All of these mechanisms help to prevent autoimmune diseases or other hyperreactivities. Different DC subsets contribute to pathogen recognition by expression of different subsets of pattern recognition receptors, including Toll-like receptors or C-type lectins. In addition to the triggering of immune responses in infected hosts, most pathogens have evolved mechanisms for evasion of targeted responses. One such strategy is characterized by adopting the host's T cell tolerance mechanisms. Understanding these tolerogenic mechanisms is of utmost importance for therapeutic approaches to treat immune pathologies, tumors and infections. Transcriptional profiling has developed into a potent tool for DC subset identification. Here, we review and compile pathogen-induced tolerogenic transcriptional signatures from mRNA profiling data of currently available bacterial- or helminth-induced transcriptional signatures. We compare them with signatures of tolerogenic steady-state DC subtypes to identify common and divergent strategies of pathogen induced immune evasion. Candidate molecules are discussed in detail. Our analysis provides further insights into tolerogenic DC signatures and their exploitation by different pathogens.}, language = {en} } @article{SilvaVilchesPletinckxLohnertetal.2017, author = {Silva-Vilches, Cinthia and Pletinckx, Katrien and Lohnert, Miriam and Pavlovic, Vladimir and Ashour, Diyaaeldin and John, Vini and Vendelova, Emilia and Kneitz, Susanne and Zhou, Jie and Chen, Rena and Reinheckel, Thomas and Mueller, Thomas D. and Bodem, Jochen and Lutz, Manfred B.}, title = {Low doses of cholera toxin and its mediator cAMP induce CTLA-2 secretion by dendritic cells to enhance regulatory T cell conversion}, series = {PLoS ONE}, volume = {12}, journal = {PLoS ONE}, number = {7}, doi = {10.1371/journal.pone.0178114}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-158244}, pages = {e0178114}, year = {2017}, abstract = {Immature or semi-mature dendritic cells (DCs) represent tolerogenic maturation stages that can convert naive T cells into Foxp3\(^{+}\) induced regulatory T cells (iTreg). Here we found that murine bone marrow-derived DCs (BM-DCs) treated with cholera toxin (CT) matured by up-regulating MHC-II and costimulatory molecules using either high or low doses of CT (CT\(^{hi}\), CT\(^{lo}\)) or with cAMP, a known mediator CT signals. However, all three conditions also induced mRNA of both isoforms of the tolerogenic molecule cytotoxic T lymphocyte antigen 2 (CTLA-2α and CTLA-2β). Only DCs matured under CT\(^{hi}\) conditions secreted IL-1β, IL-6 and IL-23 leading to the instruction of Th17 cell polarization. In contrast, CT\(^{lo}\)- or cAMP-DCs resembled semi-mature DCs and enhanced TGF-β-dependent Foxp3\(^{+}\) iTreg conversion. iTreg conversion could be reduced using siRNA blocking of CTLA-2 and reversely, addition of recombinant CTLA-2α increased iTreg conversion in vitro. Injection of CT\(^{lo}\)- or cAMP-DCs exerted MOG peptide-specific protective effects in experimental autoimmune encephalomyelitis (EAE) by inducing Foxp3\(^{+}\) Tregs and reducing Th17 responses. Together, we identified CTLA-2 production by DCs as a novel tolerogenic mediator of TGF-β-mediated iTreg induction in vitro and in vivo. The CT-induced and cAMP-mediated up-regulation of CTLA-2 also may point to a novel immune evasion mechanism of Vibrio cholerae.}, language = {en} } @article{DasariKoleciShopovaetal.2019, author = {Dasari, Prasad and Koleci, Naile and Shopova, Iordana A. and Wartenberg, Dirk and Beyersdorf, Niklas and Dietrich, Stefanie and Sahag{\´u}n-Ruiz, Alfredo and Figge, Marc Thilo and Skerka, Christine and Brakhage, Axel A. and Zipfel, Peter F.}, title = {Enolase from Aspergillus fumigatus is a moonlighting protein that binds the human plasma complement proteins factor H, FHL-1, C4BP, and plasminogen}, series = {Frontiers in Immunology}, volume = {10}, journal = {Frontiers in Immunology}, issn = {1664-3224}, doi = {10.3389/fimmu.2019.02573}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-195612}, year = {2019}, abstract = {The opportunistic fungal pathogen Aspergillus fumigatus can cause severe infections, particularly in immunocompromised individuals. Upon infection, A. fumigatus faces the powerful and directly acting immune defense of the human host. The mechanisms on how A. fumigatus evades innate immune attack and complement are still poorly understood. Here, we identify A. fumigatus enolase, AfEno1, which was also characterized as fungal allergen, as a surface ligand for human plasma complement regulators. AfEno1 binds factor H, factor-H-like protein 1 (FHL-1), C4b binding protein (C4BP), and plasminogen. Factor H attaches to AfEno1 via two regions, via short conserved repeats (SCRs) 6-7 and 19-20, and FHL-1 contacts AfEno1 via SCRs 6-7. Both regulators when bound to AfEno1 retain cofactor activity and assist in C3b inactivation. Similarly, the classical pathway regulator C4BP binds to AfEno1 and bound to AfEno1; C4BP assists in C4b inactivation. Plasminogen which binds to AfEno1 via lysine residues is accessible for the tissue-type plasminogen activator (tPA), and active plasmin cleaves the chromogenic substrate S2251, degrades fibrinogen, and inactivates C3 and C3b. Plasmin attached to swollen A. fumigatus conidia damages human A549 lung epithelial cells, reduces the cellular metabolic activity, and induces cell retraction, which results in exposure of the extracellular matrix. Thus, A. fumigatus AfEno1 is a moonlighting protein and virulence factor which recruits several human regulators. The attached human regulators allow the fungal pathogen to control complement at the level of C3 and to damage endothelial cell layers and tissue components.}, language = {en} } @article{BergfeldDasariWerneretal.2017, author = {Bergfeld, Arne and Dasari, Prasad and Werner, Sandra and Hughes, Timothy R. and Song, Wen-Chao and Hortschansky, Peter and Brakhage, Axel A. and H{\"u}nig, Thomas and Zipfel, Peter F. and Beyersdorf, Niklas}, title = {Direct binding of the pH-regulated Protein 1 (Pra1) from Candida albicans inhibits cytokine secretion by mouse CD4\(^{+}\) T cells}, series = {Frontiers in Microbiology}, volume = {8}, journal = {Frontiers in Microbiology}, number = {844}, doi = {10.3389/fmicb.2017.00844}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-158274}, year = {2017}, abstract = {Opportunistic infections with the saprophytic yeast Candida albicans are a major cause of morbidity in immunocompromised patients. While the interaction of cells and molecules of innate immunity with C. albicans has been studied to great depth, comparatively little is known about the modulation of adaptive immunity by C. albicans. In particular, direct interaction of proteins secreted by C. albicans with CD4\(^{+}\) T cells has not been studied in detail. In a first screening approach, we identified the pH-regulated antigen 1 (Pra1) as a molecule capable of directly binding to mouse CD4\(^{+}\) T cells in vitro. Binding of Pra1 to the T cell surface was enhanced by extracellular Zn\(^{2+}\) ions which Pra1 is known to scavenge from the host in order to supply the fungus with Zn\(^{2+}\). In vitro stimulation assays using highly purified mouse CD4\(^{+}\) T cells showed that Pra1 increased proliferation of CD4\(^{+}\) T cells in the presence of plate-bound anti-CD3 monoclonal antibody. In contrast, secretion of effector cytokines such as IFNγ and TNF by CD4\(^{+}\) T cells upon anti-CD3/ anti-CD28 mAb as well as cognate antigen stimulation was reduced in the presence of Pra1. By secreting Pra1 C. albicans, thus, directly modulates and partially controls CD4\(^{+}\) T cell responses as shown in our in vitro assays.}, language = {en} } @article{DasariShopovaStroeetal.2018, author = {Dasari, Prasad and Shopova, Iordana A. and Stroe, Maria and Wartenberg, Dirk and Martin-Dahse, Hans and Beyersdorf, Niklas and Hortschansky, Peter and Dietrich, Stefanie and Cseresny{\´e}s, Zolt{\´a}n and Figge, Marc Thilo and Westermann, Martin and Skerka, Christine and Brakhage, Axel A. and Zipfel, Peter F.}, title = {Aspf2 From Aspergillus fumigatus Recruits Human Immune Regulators for Immune Evasion and Cell Damage}, series = {Frontiers in Immunology}, volume = {9}, journal = {Frontiers in Immunology}, number = {1635}, issn = {1664-3224}, doi = {10.3389/fimmu.2018.01635}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-197013}, year = {2018}, abstract = {The opportunistic fungal pathogen Aspergillus fumigatus can cause life-threatening infections, particularly in immunocompromised patients. Most pathogenic microbes control host innate immune responses at the earliest time, already before infiltrating host immune cells arrive at the site of infection. Here, we identify Aspf2 as the first A. fumigatus Factor H-binding protein. Aspf2 recruits several human plasma regulators, Factor H, factor-H-like protein 1 (FHL-1), FHR1, and plasminogen. Factor H contacts Aspf2 via two regions located in SCRs6-7 and SCR20. FHL-1 binds via SCRs6-7, and FHR1 via SCRs3-5. Factor H and FHL-1 attached to Aspf2-maintained cofactor activity and assisted in C3b inactivation. A Δaspf2 knockout strain was generated which bound Factor H with 28\% and FHL-1 with 42\% lower intensity. In agreement with less immune regulator acquisition, when challenged with complement-active normal human serum, Δaspf2 conidia had substantially more C3b (>57\%) deposited on their surface. Consequently, Δaspf2 conidia were more efficiently phagocytosed (>20\%) and killed (44\%) by human neutrophils as wild-type conidia. Furthermore, Aspf2 recruited human plasminogen and, when activated by tissue-type plasminogen activator, newly generated plasmin cleaved the chromogenic substrate S2251 and degraded fibrinogen. Furthermore, plasmin attached to conidia damaged human lung epithelial cells, induced cell retraction, and caused matrix exposure. Thus, Aspf2 is a central immune evasion protein and plasminogen ligand of A. fumigatus. By blocking host innate immune attack and by disrupting human lung epithelial cell layers, Aspf2 assists in early steps of fungal infection and likely allows tissue penetration.}, language = {en} }