group leader: Prof. Bruder

Recent Submissions

  • Gamma secretase dependent release of the CD44 cytoplasmic tail upregulates IFI16 in cd44 <sup>-/-</sup> tumor cells, MEFs and macrophages

    Schultz, Kristin; Grieger, Christina; Li, Yong; Urbánek, Pavel; Ruschel, Anne; Minnich, Kerstin; Bruder, Dunja; Gereke, Marcus; Sechi, Antonio; Herrlich, Peter; et al. (PLOS, 2018-12-01)
  • In vivo Neutralization of Pro-inflammatory Cytokines During Secondary Streptococcus pneumoniae Infection Post Influenza A Virus Infection

    Sharma-Chawla, Niharika; Stegemann-Koniszewski, Sabine; Christen, Henrike; Boehme, Julia D.; Kershaw, Olivia; Schreiber, Jens; Guzmán, Carlos A.; Bruder, Dunja; Hernandez-Vargas, Esteban A.; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Frontiers Media SA, 2019-08-14)
    An overt pro-inflammatory immune response is a key factor contributing to lethal pneumococcal infection in an influenza pre-infected host and represents a potential target for therapeutic intervention. However, there is a paucity of knowledge about the level of contribution of individual cytokines. Based on the predictions of our previous mathematical modeling approach, the potential benefit of IFN-γ- and/or IL-6-specific antibody-mediated cytokine neutralization was explored in C57BL/6 mice infected with the influenza A/PR/8/34 strain, which were subsequently infected with the Streptococcus pneumoniae strain TIGR4 on day 7 post influenza. While single IL-6 neutralization had no effect on respiratory bacterial clearance, single IFN-γ neutralization enhanced local bacterial clearance in the lungs. Concomitant neutralization of IFN-γ and IL-6 significantly reduced the degree of pneumonia as well as bacteremia compared to the control group, indicating a positive effect for the host during secondary bacterial infection. The results of our model-driven experimental study reveal that the predicted therapeutic value of IFN-γ and IL-6 neutralization in secondary pneumococcal infection following influenza infection is tightly dependent on the experimental protocol while at the same time paving the way toward the development of effective immune therapies.
  • The STING activator c-di-AMP exerts superior adjuvant properties than the formulation poly(I:C)/CpG after subcutaneous vaccination with soluble protein antigen or DEC-205-mediated antigen targeting to dendritic cells.

    Volckmar, Julia; Knop, Laura; Stegemann-Koniszewski, Sabine; Schulze, Kai; Ebensen, Thomas; Guzmán, Carlos A; Bruder, Dunja; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Elsevier, 2019-08-14)
    Vaccination is the most efficient strategy to protect from infectious diseases and the induction of a protective immune response not only depends on the nature of the antigen, but is also influenced by the vaccination strategy and the co-administration of adjuvants. Therefore, the precise monitoring of adjuvant candidates and their immune modulatory properties is a crucial step in vaccine development. Here, one central aspect is the induction of appropriate humoral and cellular effector mechanisms. In our study we performed a direct comparison of two promising candidates in adjuvant development, the STING activator bis-(3,5)-cyclic dimeric adenosine monophosphate (c-di-AMP) and the Toll-like receptor ligand formulation poly(I:C)/CpG. These were evaluated in C57BL/6 mice using the model antigen ovalbumin (OVA) in subcutaneous vaccination with soluble protein as well as in a dendritic cell (DC) targeting approach (αDEC-OVA). Strikingly, c-di-AMP as compared to poly(I:C)/CpG resulted in significantly higher antigen-specific IgG antibody levels when used in immunization with soluble OVA as well as in antigen targeting to DC. In vaccination with soluble OVA, c-di-AMP induced a significantly stronger CTL, Th1 and IFNγ-producing CD8+ memory T cell response than poly(I:C)/CpG. The response was CTL and Th1 cell dominated, a profile shared by both adjuvants. In the context of targeting OVA to DC, c-di-AMP induced significantly increased Th1 and Th2 cell responses as compared to poly(I:C)/CpG. Interestingly, the Th1 response dominated the overall T cell response only when c-di-AMP was used, indicating a distinct modulatory property of c-di-AMP when the DC targeting immunization approach was exploited. Taken together, we describe superior properties of c-di-AMP as compared to poly(I:C)/CpG in subcutaneous vaccination with soluble antigen as well as antigen targeting to DC. This indicates exceptionally effective adjuvant properties for c-di-AMP and provides compelling evidence of its potential for further adjuvant development, especially also when using DC targeting approaches.
  • Essential role of IκB for in vivo CD4 T cell activation, proliferation and Th1 cell differentiation during Listeria monocytogenes infection in mice.

    Frentzel, Sarah; Katsoulis-Dimitriou, Konstantinos; Jeron, Andreas; Schmitz, Ingo; Bruder, Dunja; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (Wiley, 2019-05-03)
    Acquisition of effector functions in T cells is guided by transcription factors including NF-κB that itself is tightly controlled by inhibitory proteins. The atypical NF-κB inhibitor IκBNS is involved in the development of Th1, Th17 and Treg cells. However, it remained unclear to which extend IκBNS contributes to the acquisition of effector function in T cells specifically responding to a pathogen during in vivo infection. Tracking of adoptively transferred T cells in Listeria monocytogenes infected mice uncovered antigen-specific activation of CD4+ T cells following in vivo pathogen encounter to strongly rely on IκBNS . While IκBNS was largely dispensable for the acquisition of cytotoxic effector function in CD8+ T cells, IκBNS -deficient Th1 effector cells exhibited significantly reduced proliferation, marked changes in the pattern of activation marker expression and reduced production of the Th1-cell cytokines IFNγ, IL2 and TNFα. Complementary in vitro analyses using cells from novel reporter and inducible knockout mice revealed that IκBNS predominantly affects the early phase of Th1-cell differentiation while its function in terminally differentiated cells appears to be negligible. Our data suggest IκBNS as a potential target to modulate specifically CD4+ T-cell responses. This article is protected by copyright. All rights reserved.
  • Respiratory bordetella bronchiseptica Carriage is Associated with Broad Phenotypic Alterations of Peripheral CD4⁺CD25⁺ T Cells and Differentially Affects Immune Responses to Secondary Non-Infectious and Infectious Stimuli in Mice.

    Jeron, Andreas; Boehme, Julia D; Volckmar, Julia; Gereke, Marcus; Yevsa, Tetyana; Geffers, Robert; Guzmán, Carlos A; Schreiber, Jens; Stegemann-Koniszewski, Sabine; Bruder, Dunja; et al. (MDPI, 2018-09-01)
    The respiratory tract is constantly exposed to the environment and displays a favorable niche for colonizing microorganisms. However, the effects of respiratory bacterial carriage on the immune system and its implications for secondary responses remain largely unclear. We have employed respiratory carriage with Bordetella bronchiseptica as the underlying model to comprehensively address effects on subsequent immune responses. Carriage was associated with the stimulation of Bordetella-specific CD4+, CD8+, and CD4+CD25+Foxp3+ T cell responses, and broad transcriptional activation was observed in CD4+CD25+ T cells. Importantly, transfer of leukocytes from carriers to acutely B. bronchiseptica infected mice, resulted in a significantly increased bacterial burden in the recipient’s upper respiratory tract. In contrast, we found that respiratory B. bronchiseptica carriage resulted in a significant benefit for the host in systemic infection with Listeria monocytogenes. Adaptive responses to vaccination and influenza A virus infection, were unaffected by B. bronchiseptica carriage. These data showed that there were significant immune modulatory processes triggered by B. bronchiseptica carriage, that differentially affect subsequent immune responses. Therefore, our results demonstrated the complexity of immune regulation induced by respiratory bacterial carriage, which can be beneficial or detrimental to the host, depending on the pathogen and the considered compartment.
  • Presence of Infected Gr-1CD11bCD11c Monocytic Myeloid Derived Suppressor Cells Subverts T Cell Response and Is Associated With Impaired Dendritic Cell Function in Mycobacterium avium-Infected Mice.

    Abdissa, Ketema; Nerlich, Andreas; Beineke, Andreas; Ruangkiattikul, Nanthapon; Pawar, Vinay; Heise, Ulrike; Janze, Nina; Falk, Christine; Bruder, Dunja; Schleicher, Ulrike; et al. (2018-01-01)
    Myeloid-derived suppressor cells (MDSC) are immature myeloid cells with immunomodulatory function. To study the mechanism by which MDSC affect antimicrobial immunity, we infected mice with two M. avium strains of differential virulence, highly virulent Mycobacterium avium subsp. avium strain 25291 (MAA) and low virulent Mycobacterium avium subsp. hominissuis strain 104 (MAH). Intraperitoneal infection with MAA, but not MAH, caused severe disease and massive splenic infiltration of monocytic MDSC (M-MDSC; Gr-1intCD11bhiCD11cint) expressing inducible NO synthase (Nos2) and bearing high numbers of mycobacteria. Depletion experiments demonstrated that M-MDSC were essential for disease progression. NO production by M-MDSC influenced antigen-uptake and processing by dendritic cells and proliferation of CD4+ T cells. M-MDSC were also induced in MAA-infected mice lacking Nos2. In these mice CD4+ T cell expansion and control of infection were restored. However, T cell inhibition was only partially relieved and arginase (Arg) 1-expressing M-MDSC were accumulated. Likewise, inhibition of Arg1 also partially rescued T cell proliferation. Thus, mycobacterial virulence results in the induction of M-MDSC that block the T cell response in a Nos2- and Arg1-dependent manner.
  • Hemodialysis-related changes in phenotypical features of monocytes.

    Liakopoulos, Vassilios; Jeron, Andreas; Shah, Aneri; Bruder, Dunja; Mertens, Peter R; Gorny, Xenia; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany. (2018-09-18)
    Hemodialysis (HD) patients exhibit chronic inflammation and leukocyte activation. We investigated the surface-marker profile of monocytes by flow cytometry to assess the chronic effect of uremia and the acute effect of dialysis on their phenotypical and functional features in 16 healthy controls (CON) and 15 HD patients before and after a polysulfone-based dialysis session. Median fluorescence intensities were analyzed indicating expression of CD14, CD16, integrins (CD11b, CD18), chemokine receptors (CCR2, CX3CR1), scavenger receptors (CD36, CD163) and Toll-like receptor-2 (TLR2). Before and after dialysis, HD patients harbour 0.9-fold less CD14
  • Chronic lung inflammation primes humoral immunity and augments antipneumococcal resistance.

    Boehme, Julia D; Stegemann-Koniszewski, Sabine; Autengruber, Andrea; Peters, Nicole; Wissing, Josef; Jänsch, Lothar; Jeron, Andreas; Bruder, Dunja; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2017-07-10)
    Airway epithelial cells (AECs) display remarkable plasticity in response to infectious stimuli and their functional adaptations are critical for antimicrobial immunity. However, the roles of AECs and humoral mediators to host defense in non-communicable lung inflammation remain elusive. We dissected pulmonary defense against Streptococcus pneumoniae in hosts with pre-existing inflammatory conditions (SPC-HAxTCR-HA mice). Lung tissue transcriptomics and bronchoalveolar lavage fluid (BALF) proteomics revealed an induction of humoral defense mechanisms in inflamed lungs. Accordingly, besides antibacterial proteins and complement components being overrepresented in inflamed lungs, elevated polymeric immunoglobulin receptor (pIgR)-expression in AECs correlated with increased secretory immunoglobulin (SIg) transport. Consequently, opsonization assays revealed augmented pneumococcal coverage by SIgs present in the BALF of SPC-HAxTCR-HA mice, which was associated with enhanced antipneumococcal resistance. These findings emphasize the immunologic potential of AECs as well as their central role in providing antibacterial protection and put forward pIgR as potential target for therapeutic manipulation in infection-prone individuals.
  • Targeted antigen delivery to dendritic cells elicits robust antiviral T cell-mediated immunity in the liver.

    Volckmar, Julia; Gereke, Marcus; Ebensen, Thomas; Riese, Peggy; Philipsen, Lars; Lienenklaus, Stefan; Wohlleber, Dirk; Klopfleisch, Robert; Stegemann-Koniszewski, Sabine; Müller, Andreas J; et al. (2017-03-07)
    Hepatotropic viruses such as hepatitis C virus cause life-threatening chronic liver infections in millions of people worldwide. Targeted in vivo antigen-delivery to cross-presenting dendritic cells (DCs) has proven to be extraordinarily efficient in stimulating antigen-specific T cell responses. To determine whether this approach would as well be suitable to induce local antiviral effector T cells in the liver we compared different vaccine formulations based on either the targeting of DEC-205 or TLR2/6 on cross-presenting DCs or formulations not involving in vivo DC targeting. As read-outs we used in vivo hepatotropic adenovirus challenge, histology and automated multidimensional fluorescence microscopy (MELC). We show that targeted in vivo antigen delivery to cross-presenting DCs is highly effective in inducing antiviral CTLs capable of eliminating virus-infected hepatocytes, while control vaccine formulation not involving DC targeting failed to induce immunity against hepatotropic virus. Moreover, we observed distinct patterns of CD8+ T cell interaction with virus-infected and apoptotic hepatocytes in the two DC-targeting groups suggesting that the different vaccine formulations may stimulate distinct types of effector functions. Our findings represent an important step toward the future development of vaccines against hepatotropic viruses and the treatment of patients with hepatic virus infection after liver transplantation to avoid reinfection.
  • ChIP-on-chip analysis identifies IL-22 as direct target gene of ectopically expressed FOXP3 transcription factor in human T cells

    Jeron, Andreas; Hansen, Wiebke; Ewert, Franziska; Buer, Jan; Geffers, Robert; Bruder, Dunja (2012-12-17)
    Abstract Background The transcription factor (TF) forkhead box P3 (FOXP3) is constitutively expressed at high levels in naturally occurring CD4+CD25+ regulatory T cells (nTregs). It is not only the most accepted marker for that cell population but is also considered lineage determinative. Chromatin immunoprecipitation (ChIP) of TFs in combination with genomic tiling microarray analysis (ChIP-on-chip) has been shown to be an appropriate tool for identifying FOXP3 transcription factor binding sites (TFBSs) on a genome-wide scale. In combination with microarray expression analysis, the ChIP-on-chip technique allows identification of direct FOXP3 target genes. Results ChIP-on-chip analysis of the human FOXP3 expressed in resting and PMA/ionomycin–stimulated Jurkat T cells revealed several thousand putative FOXP3 binding sites and demonstrated the importance of intronic regions for FOXP3 binding. The analysis of expression data showed that the stimulation-dependent down-regulation of IL-22 was correlated with direct FOXP3 binding in the IL-22 promoter region. This association was confirmed by real-time PCR analysis of ChIP-DNA. The corresponding ChIP-region also contained a matching FOXP3 consensus sequence. Conclusions Knowledge of the general distribution patterns of FOXP3 TFBSs in the human genome under resting and activated conditions will contribute to a better understanding of this TF and its influence on direct target genes, as well as its importance for the phenotype and function of Tregs. Moreover, FOXP3-dependent repression of Th17-related IL-22 may be relevant to an understanding of the phenomenon of Treg/Th17 cell plasticity.
  • ImmunoPET/MR imaging allows specific detection of Aspergillus fumigatus lung infection in vivo.

    Rolle, Anna-Maria; Hasenberg, Mike; Thornton, Christopher R; Solouk-Saran, Djamschid; Männ, Linda; Weski, Juliane; Maurer, Andreas; Fischer, Eliane; Spycher, Philipp R; Schibli, Roger; et al. (2016-02-23)
    Invasive pulmonary aspergillosis (IPA) is a life-threatening lung disease caused by the fungus Aspergillus fumigatus, and is a leading cause of invasive fungal infection-related mortality and morbidity in patients with hematological malignancies and bone marrow transplants. We developed and tested a novel probe for noninvasive detection of A. fumigatus lung infection based on antibody-guided positron emission tomography and magnetic resonance (immunoPET/MR) imaging. Administration of a [(64)Cu]DOTA-labeled A. fumigatus-specific monoclonal antibody (mAb), JF5, to neutrophil-depleted A. fumigatus-infected mice allowed specific localization of lung infection when combined with PET. Optical imaging with a fluorochrome-labeled version of the mAb showed colocalization with invasive hyphae. The mAb-based newly developed PET tracer [(64)Cu]DOTA-JF5 distinguished IPA from bacterial lung infections and, in contrast to [(18)F]FDG-PET, discriminated IPA from a general increase in metabolic activity associated with lung inflammation. To our knowledge, this is the first time that antibody-guided in vivo imaging has been used for noninvasive diagnosis of a fungal lung disease (IPA) of humans, an approach with enormous potential for diagnosis of infectious diseases and with potential for clinical translation.
  • A cell culture-derived whole virus influenza A vaccine based on magnetic sulfated cellulose particles confers protection in mice against lethal influenza A virus infection.

    Pieler, Michael M; Frentzel, Sarah; Bruder, Dunja; Wolff, Michael W; Reichl, Udo; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2016-12-07)
    Downstream processing and formulation of viral vaccines employs a large number of different unit operations to achieve the desired product qualities. The complexity of individual process steps involved, the need for time consuming studies towards the optimization of virus yields, and very high requirements regarding potency and safety of vaccines results typically in long lead times for the establishment of new processes. To overcome such obstacles, to enable fast screening of potential vaccine candidates, and to explore options for production of low cost veterinary vaccines a new platform for whole virus particle purification and formulation based on magnetic particles has been established. Proof of concept was carried out with influenza A virus particles produced in suspension Madin Darby canine kidney (MDCK) cells. The clarified, inactivated, concentrated, and diafiltered virus particles were bound to magnetic sulfated cellulose particles (MSCP), and directly injected into mice for immunization including positive and negative controls. We show here, that in contrast to the mock-immunized group, vaccination of mice with antigen-loaded MSCP (aMSCP) resulted in high anti-influenza A antibody responses and full protection against a lethal challenge with replication competent influenza A virus. Antiviral protection correlated with a 400-fold reduced number of influenza nucleoprotein gene copies in the lungs of aMSCP immunized mice compared to mock-treated animals, indicating the efficient induction of antiviral immunity by this novel approach. Thus, our data proved the use of MSCP for purification and formulation of the influenza vaccine to be fast and efficient, and to confer protection of mice against influenza A virus infection. Furthermore, the method proposed has the potential for fast purification of virus particles directly from bioreactor harvests with a minimum number of process steps towards formulation of low-cost veterinary vaccines, and for screening studies requiring fast purification protocols.
  • A Precise Temperature-Responsive Bistable Switch Controlling Yersinia Virulence.

    Nuss, Aaron Mischa; Schuster, Franziska; Roselius, Louisa; Klein, Johannes; Bücker, René; Herbst, Katharina; Heroven, Ann Kathrin; Pisano, Fabio; Wittmann, Christoph; Münch, Richard; et al. (2016-12)
    Different biomolecules have been identified in bacterial pathogens that sense changes in temperature and trigger expression of virulence programs upon host entry. However, the dynamics and quantitative outcome of this response in individual cells of a population, and how this influences pathogenicity are unknown. Here, we address these questions using a thermosensing virulence regulator of an intestinal pathogen (RovA of Yersinia pseudotuberculosis) as a model. We reveal that this regulator is part of a novel thermoresponsive bistable switch, which leads to high- and low-invasive subpopulations within a narrow temperature range. The temperature range in which bistability is observed is defined by the degradation and synthesis rate of the regulator, and is further adjustable via a nutrient-responsive regulator. The thermoresponsive switch is also characterized by a hysteretic behavior in which activation and deactivation occurred on vastly different time scales. Mathematical modeling accurately mirrored the experimental behavior and predicted that the thermoresponsiveness of this sophisticated bistable switch is mainly determined by the thermo-triggered increase of RovA proteolysis. We further observed RovA ON and OFF subpopulations of Y. pseudotuberculosis in the Peyer's patches and caecum of infected mice, and that changes in the RovA ON/OFF cell ratio reduce tissue colonization and overall virulence. This points to a bet-hedging strategy in which the thermoresponsive bistable switch plays a key role in adapting the bacteria to the fluctuating conditions encountered as they pass through the host's intestinal epithelium and suggests novel strategies for the development of antimicrobial therapies.
  • Influenza A virus infection predisposes hosts to secondary infection with different Streptococcus pneumoniae serotypes with similar outcome but serotype-specific manifestation.

    Sharma-Chawla, Niharika; Sender, Vicky; Kershaw, Olivia; Gruber, Achim D; Volckmar, Julia; Henriques-Normark, Birgitta; Stegemann-Koniszewski, Sabine; Bruder, Dunja; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2016-09-19)
    Influenza A virus (IAV) and Streptococcus pneumoniae (S. pn.) are major causes of respiratory tract infections, particularly during co-infection. The synergism between these two pathogens is characterized by a complex network of dysregulated immune responses, some of which last until recovery post IAV infection. Despite the high serotype-diversity of S. pn. and the serotype-replacement observed since the introduction of conjugate vaccines, little is known about pneumococcal strain-dependency in the enhanced susceptibility to severe secondary S. pn. infection following IAV infection. Thus we studied how pre-infection with IAV alters host susceptibility to different S. pn. strains with varying degrees of invasiveness using a highly invasive serotype 4, an invasive serotype 7F and a carrier serotype 19F strain. A murine model of pneumococcal co-infection during the acute phase of IAV infection showed a significantly increased degree of pneumonia and mortality for all tested pneumococcal strains at otherwise sublethal doses. The incidence and kinetics of systemic dissemination however remained bacterial strain-dependent. Furthermore we observed strain-specific alterations in the pulmonary levels of alveolar macrophages, neutrophils and inflammatory mediators ultimately affecting immunopathology. During the recovery phase following IAV infection, bacterial growth in the lungs and systemic dissemination were enhanced in a strain-dependent manner. Altogether, this study shows that acute IAV infection predisposes the host to lethal S. pn. infection irrespective of the pneumococcal serotype, while the long lasting synergism between IAV and S. pn. is bacterial strain-dependent. These results hold implications for developing tailored therapeutic treatment regimens for dual infections during future IAV outbreaks.
  • Biodegradable chitosan nanoparticle coatings on titanium for the delivery of BMP-2.

    Poth, Nils; Seiffart, Virginia; Gross, Gerhard; Menzel, Henning; Dempwolf, Wibke; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2015)
    A simple method for the functionalization of a common implant material (Ti6Al4V) with biodegradable, drug loaded chitosan-tripolyphosphate (CS-TPP) nanoparticles is developed in order to enhance the osseointegration of endoprostheses after revision operations. The chitosan used has a tailored degree of acetylation which allows for a fast biodegradation by lysozyme. The degradability of chitosan is proven via viscometry. Characteristics and degradation of nanoparticles formed with TPP are analyzed using dynamic light scattering. The particle degradation via lysozyme displays a decrease in particle diameter of 40% after 4 days. Drug loading and release is investigated for the nanoparticles with bone morphogenetic protein 2 (BMP-2), using ELISA and the BRE luciferase test for quantification and bioactivity evaluation. Furthermore, nanoparticle coatings on titanium substrates are created via spray-coating and analyzed by ellipsometry, scanning electron microscopy and X-ray photoelectron spectroscopy. Drug loaded nanoparticle coatings with biologically active BMP-2 are obtained in vitro within this work. Additionally, an in vivo study in mice indicates the dose dependent induction of ectopic bone growth through CS-TPP-BMP-2 nanoparticles. These results show that biodegradable CS-TPP coatings can be utilized to present biologically active BMP-2 on common implant materials like Ti6Al4V.
  • Alveolar Type II Epithelial Cells Contribute to the Anti-Influenza A Virus Response in the Lung by Integrating Pathogen- and Microenvironment-Derived Signals

    Stegemann-Koniszewski, S.; Jeron, Andreas; Gereke, Marcus; Geffers, Robert; Kröger, Andrea; Gunzer, Matthias; Bruder, Dunja; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2016-05-03)
    ABSTRACT Influenza A virus (IAV) periodically causes substantial morbidity and mortality in the human population. In the lower lung, the primary targets for IAV replication are type II alveolar epithelial cells (AECII), which are increasingly recognized for their immunological potential. So far, little is known about their reaction to IAV and their contribution to respiratory antiviral immunity in vivo . Therefore, we characterized the AECII response during early IAV infection by analyzing transcriptional regulation in cells sorted from the lungs of infected mice. We detected rapid and extensive regulation of gene expression in AECII following in vivo IAV infection. The comparison to transcriptional regulation in lung tissue revealed a strong contribution of AECII to the respiratory response. IAV infection triggered the expression of a plethora of antiviral factors and immune mediators in AECII with a high prevalence for interferon-stimulated genes. Functional pathway analyses revealed high activity in pathogen recognition, immune cell recruitment, and antigen presentation. Ultimately, our analyses of transcriptional regulation in AECII and lung tissue as well as interferon I/III levels and cell recruitment indicated AECII to integrate signals provided by direct pathogen recognition and surrounding cells. Ex vivo analysis of AECII proved a powerful tool to increase our understanding of their role in respiratory immune responses, and our results clearly show that AECII need to be considered a part of the surveillance and effector system of the lower respiratory tract. IMPORTANCE In order to confront the health hazard posed by IAV, we need to complete our understanding of its pathogenesis. AECII are primary targets for IAV replication in the lung, and while we are beginning to understand their importance for respiratory immunity, the in vivo AECII response during IAV infection has not been analyzed. In contrast to studies addressing the response of AECII infected with IAV ex vivo , we have performed detailed gene transcriptional profiling of AECII isolated from the lungs of infected mice. Thereby, we have identified an exceptionally rapid and versatile response to IAV infection that is shaped by pathogen-derived as well as microenvironment-derived signals and aims at the induction of antiviral measures and the recruitment and activation of immune cells. In conclusion, our study presents AECII as active players in antiviral defense in vivo that need to be considered part of the sentinel and effector immune system of the lung.
  • Morphological and Functional Alterations of Alveolar Macrophages in a Murine Model of Chronic Inflammatory Lung Disease

    Désirée Boehme, Julia; Pietkiewicz, Sabine; Lavrik, Inna; Jeron, Andreas; Bruder, Dunja (2015-08-30)
  • Evidence for a causal link between adaptor protein PDZK1 downregulation and Na⁺/H⁺ exchanger NHE3 dysfunction in human and murine colitis.

    Yeruva, Sunil; Chodisetti, Giriprakash; Luo, Min; Chen, Mingmin; Cinar, Ayhan; Ludolph, Lisa; Lünnemann, Maria; Goldstein, Julia; Singh, Anurag Kumar; Riederer, Brigitte; et al. (2015-08)
    A dysfunction of the Na(+)/H(+) exchanger isoform 3 (NHE3) significantly contributes to the reduced salt absorptive capacity of the inflamed intestine. We previously reported a strong decrease in the NHERF family member PDZK1 (NHERF3), which binds to NHE3 and regulates its function in a mouse model of colitis. The present study investigates whether a causal relationship exists between the decreased PDZK1 expression and the NHE3 dysfunction in human and murine intestinal inflammation. Biopsies from the colon of patients with ulcerative colitis, murine inflamed ileal and colonic mucosa, NHE3-transfected Caco-2BBe colonic cells with short hairpin RNA (shRNA) knockdown of PDZK1, and Pdzk1-gene-deleted mice were studied. PDZK1 mRNA and protein expression was strongly decreased in inflamed human and murine intestinal tissue as compared to inactive disease or control tissue, whereas that of NHE3 or NHERF1 was not. Inflamed human and murine intestinal tissues displayed correct brush border localization of NHE3 but reduced acid-activated NHE3 transport activity. A similar NHE3 transport defect was observed when PDZK1 protein content was decreased by shRNA knockdown in Caco-2BBe cells or when enterocyte PDZK1 protein content was decreased to similar levels as found in inflamed mucosa by heterozygote breeding of Pdzk1-gene-deleted and WT mice. We conclude that a decrease in PDZK1 expression, whether induced by inflammation, shRNA-mediated knockdown, or heterozygous breeding, is associated with a decreased NHE3 transport rate in human and murine enterocytes. We therefore hypothesize that inflammation-induced loss of PDZK1 expression may contribute to the NHE3 dysfunction observed in the inflamed intestine.
  • First genomic analysis of dendritic cells from lung and draining lymph nodes in murine asthma.

    Tschernig, Thomas; Hartwig, Christina; Jeron, Andreas; Dinh, Quoc Thai; Gereke, Marcus; Bruder, Dunja; Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany. (2015)
    Asthma is the consequence of allergic inflammation in the lung compartments and lung-draining lymph nodes. Dendritic cells initiate and promote T cell response and drive it to immunity or allergy. However, their modes of action during asthma are poorly understood. In this study, an allergic inflammation with ovalbumin was induced in 38 mice versus 42 control animals. After ovalbumin aerosol challenge, conventional dendritic cells (CD11c/MHCII/CD8) were isolated from the lungs and the draining lymph nodes by means of magnetic cell sorting followed by fluorescence-activated cell sorting. A comparative transcriptional analysis was performed using gene arrays. In general, many transcripts are up- and downregulated in the CD8(-) dendritic cells of the allergic inflamed lung tissue, whereas few genes are regulated in CD8(+) dendritic cells. The dendritic cells of the lymph nodes also showed minor transcriptional changes. The data support the relevance of the CD8(-) conventional dendritic cells but do not exclude distinct functions of the small population of CD8(+) dendritic cells, such as cross presentation of external antigen. So far, this is the first approach performing gene arrays in dendritic cells obtained from lung tissue and lung-draining lymph nodes of asthmatic-like mice.
  • Attenuation of immune-mediated influenza pneumonia by targeting the inducible co-stimulator (ICOS) molecule on T cells.

    Sakthivel, Priya; Gereke, Marcus; Breithaupt, Angele; Fuchs, Dietmar; Gigliotti, Luca; Gruber, Achim D; Dianzani, Umberto; Bruder, Dunja (2014)
    Inducible Co-stimulator (ICOS) plays a critical role in mediating T cell differentiation and function and is considered a key player in balancing T effector and T regulatory (Treg) cell responses. Here we show that activation of the ICOS signalling pathway during acute influenza A virus (IAV) infection by application of an agonistic ICOS antibody reduced the frequency of CD8+ T cells in the respiratory tract of IAV infected animals and delayed pathogen elimination. In line with this, immune-mediated influenza pneumonia was significantly ameliorated in mice that received ICOS agonist as indicated by significantly reduced alveolar infiltrations and bronchointerstitial pneumonia, while at the same time virus-related pathology remained unaffected. Importantly, ICOS agonist treatment resulted in expansion of CD4+Foxp3+ Tregs in IAV infected mice, which was associated with elevated levels of the immunosuppressive cytokine IL-10 in the alveolar space. Together, our findings suggest a prominent role of ICOS signaling during acute IAV infection by increasing the Treg/CD8+ T cell ratio with beneficial outcome on immune-mediated pneumonia and underline the suitability of ICOS as potential therapeutic target for immune intervention in those infectious conditions characterized by strong immunopathology rather than virus-mediated cytopathic effects.

View more