group leader: Prof. Müller

Recent Submissions

  • Beware the intruder: Real time observation of infiltrated neutrophils and neutrophil-Microglia interaction during stroke in vivo.

    Neumann, Jens; Henneberg, Sophie; von Kenne, Susanne; Nolte, Niklas; Müller, Andreas J; Schraven, Burkhart; Görtler, Michael W; Reymann, Klaus G; Gunzer, Matthias; Riek-Burchardt, Monika; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2018)
    Inflammation plays an important role in the pathogenesis of ischemic stroke including an acute and prolonged inflammatory process. The role of neutrophil granulocytes as first driver of the immune reaction from the blood site is under debate due to controversial findings. In bone marrow chimeric mice we were able to study the dynamics of tdTomato-expressing neutrophils and GFP-expressing microglia after photothrombosis using intravital two-photon microscopy. We demonstrate the infiltration of neutrophils into the brain parenchyma and confirm a long-lasting contact between neutrophils and microglia as well as an uptake of neutrophils by microglia clearing the brain from peripheral immune cells.
  • 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; Gruber, Achim D; Knolle, Percy; Guzman, Carlos A; Bruder, Dunja; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr.7, 38124 Braunschweig, Germany. (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.
  • TCR signalling network organization at the immunological synapses of murine regulatory T cells.

    van Ham, Marco; Teich, René; Philipsen, Lars; Niemz, Jana; Amsberg, Nicole; Wissing, Josef; Nimtz, Manfred; Gröbe, Lothar; Kliche, Stefanie; Thiel, Nadine; Klawonn, Frank; Hubo, Mario; Jonuleit, Helmut; Reichardt, Peter; Müller, Andreas J; Huehn, Jochen; Jänsch, Lothar; Helmholtz-Zetrum für Infektionsforschung GmbH, Inhoffenstr.7, 38124 Braunschweig, Germany. (2017-08-17)
    Regulatory T (Treg) cells require T-cell receptor (TCR) signalling to exert their immunosuppressive activity, but the precise organization of the TCR signalling network compared to conventional T (Tconv) cells remains elusive. By using accurate mass spectrometry and multi-epitope ligand cartography (MELC) we characterized TCR signalling and recruitment of TCR signalling components to the immunological synapse (IS) in Treg cells and Tconv cells. With the exception of Themis which we detected in lower amounts in Treg cells, other major TCR signalling components were found equally abundant, however, their phosphorylation-status notably discriminates Treg cells from Tconv cells. Overall, this study identified 121 Treg cell-specific phosphorylations. Short-term triggering of T cell subsets via CD3 and CD28 widely harmonized these variations with the exception of eleven TCR signalling components that mainly regulate cytoskeleton dynamics and molecular transport. Accordingly, conjugation with B cells indeed caused variant cellular morphology and revealed a Treg cell-specific recruitment of TCR signalling components such as PKCθ, PLCγ1 and ZAP70 as well as B cell-derived CD86 into the IS. Together, results from this study support the existence of a Treg cell-specific IS and suggest Treg cell-specific cytoskeleton dynamics as a novel determinant for the unique functional properties of Treg cells.
  • D120 and K152 within the PH domain of T cell adapter SKAP55 regulate plasma membrane targeting of SKAP55 and LFA-1 affinity modulation in human T lymphocytes.

    Witte, Amelie; Meineke, Bernhard; Sticht, Jana; Philipsen, Lars; Kuropka, Benno; Müller, Andreas J; Freund, Christian; Schraven, Burkhart; Kliche, Stefanie; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2017-01-04)
    The β2-integrin lymphocyte function-associated antigen-1 (LFA-1) is needed for T cell receptor (TCR) induced activation of LFA-1 to promote T cell adhesion and interaction with antigen presenting cells (APCs). LFA-1-mediated cell-cell interactions are critical for proper T cell differentiation and proliferation. The Src Kinase-Associated Phosphoprotein of 55 kDa (SKAP55) is a key regulator of TCR-mediated LFA-1 signaling (inside-out/outside-in signaling). To gain understanding of how SKAP55 controls TCR-mediated LFA-1 activation, we assessed the functional role of its Pleckstrin Homology (PH) domain. We identified two critical amino acid residues within the PH domain of SKAP55, aspartic acid 120 (D120) and lysine 152 (K152). D120 facilitates retention of SKAP55 in the cytoplasm of non-stimulated T cells while K152 promotes SKAP55 membrane recruitment via Actin binding upon TCR-triggering. Importantly, the K152-dependent interaction of the PH domain with Actin promotes the binding of Talin to LFA-1 thus facilitating LFA-1 activation. These data suggest that K152 and D120 within the PH domain of SKAP55 regulate plasma membrane targeting and TCR-mediated activation of LFA-1.
  • Fast type I interferon response protects astrocytes from flavivirus infection and virus-induced cytopathic effects.

    Lindqvist, Richard; Mundt, Filip; Gilthorpe, Jonathan D; Wölfel, Silke; Gekara, Nelson O; Kröger, Andrea; Överby, Anna K; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2016-10-24)
    Neurotropic flaviviruses such as tick-borne encephalitis virus (TBEV), Japanese encephalitis virus (JEV), West Nile virus (WNV), and Zika virus (ZIKV) are causative agents of severe brain-related diseases including meningitis, encephalitis, and microcephaly. We have previously shown that local type I interferon response within the central nervous system (CNS) is involved in the protection of mice against tick-borne flavivirus infection. However, the cells responsible for mounting this protective response are not defined.
  • Chronic Toxoplasma gondii infection enhances β-amyloid phagocytosis and clearance by recruited monocytes.

    Möhle, Luisa; Israel, Nicole; Paarmann, Kristin; Krohn, Markus; Pietkiewicz, Sabine; Müller, Andreas; Lavrik, Inna N; Buguliskis, Jeffrey S; Schott, Björn H; Schlüter, Dirk; Gundelfinger, Eckart D; Montag, Dirk; Seifert, Ulrike; Pahnke, Jens; Dunay, Ildiko Rita; Institute for Medical Microbiology and Hospital Hygiene, University of Magdeburg, Leipziger Str. 44, 39120 Magdeburg, Germany. (2016)
    Alzheimer's disease (AD) is associated with the accumulation of β-amyloid (Aβ) as senile plaques in the brain, thus leading to neurodegeneration and cognitive impairment. Plaque formation depends not merely on the amount of generated Aβ peptides, but more importantly on their effective removal. Chronic infections with neurotropic pathogens, most prominently the parasite Toxoplasma (T.) gondii, are frequent in the elderly, and it has been suggested that the resulting neuroinflammation may influence the course of AD. In the present study, we investigated how chronic T. gondii infection and resulting neuroinflammation affect plaque deposition and removal in a mouse model of AD.
  • Type I Interferon response in olfactory bulb, the site of tick-borne flavivirus accumulation, is primarily regulated by IPS-1.

    Kurhade, Chaitanya; Zegenhagen, Loreen; Weber, Elvira; Nair, Sharmila; Michaelsen-Preusse, Kristin; Spanier, Julia; Gekara, Nelson O; Kröger, Andrea; Överby, Anna K; Helmholtz Centre for infection research (HZI), Inhoffenstraße 7, 38124 Braunschweig, Germany. (2016)
    Although type I interferons (IFNs)-key effectors of antiviral innate immunity are known to be induced via different pattern recognition receptors (PRRs), the cellular source and the relative contribution of different PRRs in host protection against viral infection is often unclear. IPS-1 is a downstream adaptor for retinoid-inducible gene I (RIG-I)-like receptor signaling. In this study, we investigate the relative contribution of IPS-1 in the innate immune response in the different brain regions during infection with tick-borne encephalitis virus (TBEV), a flavivirus that causes a variety of severe symptoms like hemorrhagic fevers, encephalitis, and meningitis in the human host.
  • Rapid Sequestration of Leishmania mexicana by Neutrophils Contributes to the Development of Chronic Lesion.

    Hurrell, Benjamin P; Schuster, Steffen; Grün, Eva; Coutaz, Manuel; Williams, Roderick A; Held, Werner; Malissen, Bernard; Malissen, Marie; Yousefi, Shida; Simon, Hans-Uwe; Müller, Andreas J; Tacchini-Cottier, Fabienne; Department of Biochemistry, WHO-Immunology Research and Training Center, University of Lausanne, Epalinges, Switzerland. (2015-05)
    The protozoan Leishmania mexicana parasite causes chronic non-healing cutaneous lesions in humans and mice with poor parasite control. The mechanisms preventing the development of a protective immune response against this parasite are unclear. Here we provide data demonstrating that parasite sequestration by neutrophils is responsible for disease progression in mice. Within hours of infection L. mexicana induced the local recruitment of neutrophils, which ingested parasites and formed extracellular traps without markedly impairing parasite survival. We further showed that the L. mexicana-induced recruitment of neutrophils impaired the early recruitment of dendritic cells at the site of infection as observed by intravital 2-photon microscopy and flow cytometry analysis. Indeed, infection of neutropenic Genista mice and of mice depleted of neutrophils at the onset of infection demonstrated a prominent role for neutrophils in this process. Furthermore, an increase in monocyte-derived dendritic cells was also observed in draining lymph nodes of neutropenic mice, correlating with subsequent increased frequency of IFNγ-secreting T helper cells, and better parasite control leading ultimately to complete healing of the lesion. Altogether, these findings show that L. mexicana exploits neutrophils to block the induction of a protective immune response and impairs the control of lesion development. Our data thus demonstrate an unanticipated negative role for these innate immune cells in host defense, suggesting that in certain forms of cutaneous leishmaniasis, regulating neutrophil recruitment could be a strategy to promote lesion healing.
  • PI3Kγ deficiency delays the onset of experimental autoimmune encephalomyelitis and ameliorates its clinical outcome.

    Berod, Luciana; Heinemann, Christina; Heink, Sylvia; Escher, Angelika; Stadelmann, Christine; Drube, Sebastian; Wetzker, Reinhard; Norgauer, Johannes; Kamradt, Thomas (2011-03)
    PI3Ks control signal transduction triggered by growth factors and G-protein-coupled receptors and regulate an array of biological processes, including cellular proliferation, differentiation, survival and migration. Herein, we investigated the role of PI3Kγ in the pathogenesis of EAE. We show that, in the absence of PI3Kγ expression, clinical signs of EAE were delayed and mitigated. PI3Kγ-deficient myelin oligodendrocyte glycoprotein (MOG)(35-55) -specific CD4(+) T cells appeared later in the secondary lymphoid organs and in the CNS than their WT counterparts. Transfer of WT CD4(+) cells into PI3Kγ(-/-) mice prior to MOG(35-55) immunisation restored EAE severity to WT levels, supporting the relevance of PI3Kγ expression in Th cells for the pathogenesis of EAE; however, PI3Kγ was dispensable for Th1 and Th17 differentiation, thus excluding an altered expression of these pathogenetically relevant cytokines as the cause for ameliorated EAE in PI3Kγ(-/-) mice. These findings demonstrate that PI3Kγ contributes to the development of autoimmune CNS inflammation.
  • Interferon regulatory factor-1 protects from fatal neurotropic infection with vesicular stomatitis virus by specific inhibition of viral replication in neurons.

    Nair, Sharmila; Michaelsen-Preusse, Kristin; Finsterbusch, Katja; Stegemann-Koniszewski, Sabine; Bruder, Dunja; Grashoff, Martina; Korte, Martin; Köster, Mario; Kalinke, Ulrich; Hauser, Hansjörg; Kröger, Andrea; Research Group Innate Immunity and Infection, Helmholtz Centre for Infection Research, Braunschweig, Germany (2014-03)
    The innate immune system protects cells against invading viral pathogens by the auto- and paracrine action of type I interferon (IFN). In addition, the interferon regulatory factor (IRF)-1 can induce alternative intrinsic antiviral responses. Although both, type I IFN and IRF-1 mediate their antiviral action by inducing overlapping subsets of IFN stimulated genes, the functional role of this alternative antiviral action of IRF-1 in context of viral infections in vivo remains unknown. Here, we report that IRF-1 is essential to counteract the neuropathology of vesicular stomatitis virus (VSV). IFN- and IRF-1-dependent antiviral responses act sequentially to create a layered antiviral protection program against VSV infections. Upon intranasal infection, VSV is cleared in the presence or absence of IRF-1 in peripheral organs, but IRF-1-/- mice continue to propagate the virus in the brain and succumb. Although rapid IFN induction leads to a decline in VSV titers early on, viral replication is re-enforced in the brains of IRF-1-/- mice. While IFN provides short-term protection, IRF-1 is induced with delayed kinetics and controls viral replication at later stages of infection. IRF-1 has no influence on viral entry but inhibits viral replication in neurons and viral spread through the CNS, which leads to fatal inflammatory responses in the CNS. These data support a temporal, non-redundant antiviral function of type I IFN and IRF-1, the latter playing a crucial role in late time points of VSV infection in the brain.
  • Hepatitis C virus replication in mouse cells is restricted by IFN-dependent and -independent mechanisms.

    Nandakumar, Ramya; Finsterbusch, Katja; Lipps, Christoph; Neumann, Berit; Grashoff, Martina; Nair, Sharmila; Hochnadel, Inga; Lienenklaus, Stefan; Wappler, Ilka; Steinmann, Eike; Hauser, Hansjörg; Pietschmann, Thomas; Kröger, Andrea; Helmholtz Centre for infection research, D38124 Braunschweig, Germany (2013-12)
    Current treatment strategies for hepatitis C virus (HCV) infection include pegylated interferon (IFN)-alfa and ribavirin. Approximately 50% of patients control HCV infection after treatment, but the broad range of patients' outcomes and responses to treatment, among all genotypes, indicates a role for host factors. Although the IFN system is important in limiting HCV replication, the virus has evolved mechanisms to circumvent the IFN response. However, direct, IFN-independent antiviral processes also might help control HCV replication. We examined the role of IFN-independent responses against HCV replication.