• A clonotypic Vγ4Jγ1/Vδ5Dδ2Jδ1 innate γδ T-cell population restricted to the CCR6⁺CD27⁻ subset.

      Kashani, Elham; Föhse, Lisa; Raha, Solaiman; Sandrock, Inga; Oberdörfer, Linda; Koenecke, Christian; Suerbaum, Sebastian; Weiss, Siegfried; Prinz, Immo; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2015)
      Here we investigate the TCR repertoire of mouse Vγ4(+) γδ T cells in correlation with their developmental origin and homeostasis. By deep sequencing we identify a high frequency of straight Vδ5Dδ2Jδ1 germline rearrangements without P- and N-nucleotides within the otherwise highly diverse Trd repertoire of Vγ4(+) cells. This sequence is infrequent in CCR6(-)CD27(+) cells, but abundant among CCR6(+)CD27(-) γδ T cells. Using an inducible Rag1 knock-in mouse model, we show that γδ T cells generated in the adult thymus rarely contain this germline-rearranged Vδ5Dδ2Jδ1 sequence, confirming its fetal origin. Single-cell analysis and deep sequencing of the Trg locus reveal a dominant CDR3 junctional motif that completes the TCR repertoire of invariant Vγ4(+)Vδ5(+) cells. In conclusion, this study identifies an innate subset of fetal thymus-derived γδ T cells with an invariant Vγ4(+)Vδ5(+) TCR that is restricted to the CCR6(+)CD27(-) subset of γδ T cells.
    • Hypoxia Enhances Immunosuppression by Inhibiting CD4+ Effector T Cell Function and Promoting Treg Activity.

      Westendorf, Astrid M; Skibbe, Kathrin; Adamczyk, Alexandra; Buer, Jan; Geffers, Robert; Hansen, Wiebke; Pastille, Eva; Jendrossek, Verena; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2017)
      Hypoxia occurs in many pathological conditions, including inflammation and cancer. Within this context, hypoxia was shown to inhibit but also to promote T cell responses. Due to this controversial function, we aimed to explore whether an insufficient anti-tumour response during colitis-associated colon cancer could be ascribed to a hypoxic microenvironment.
    • Induction of endogenous Type I interferon within the central nervous system plays a protective role in experimental autoimmune encephalomyelitis.

      Khorooshi, Reza; Mørch, Marlene Thorsen; Holm, Thomas Hellesøe; Berg, Carsten Tue; Dieu, Ruthe Truong; Dræby, Dina; Issazadeh-Navikas, Shohreh; Weiß, Siegfried; Lienenklaus, Stefan; Owens, Trevor; et al. (2015-07)
      The Type I interferons (IFN), beta (IFN-β) and the alpha family (IFN-α), act through a common receptor and have anti-inflammatory effects. IFN-β is used to treat multiple sclerosis (MS) and is effective against experimental autoimmune encephalomyelitis (EAE), an animal model for MS. Mice with EAE show elevated levels of Type I IFNs in the central nervous system (CNS), suggesting a role for endogenous Type I IFN during inflammation. However, the therapeutic benefit of Type I IFN produced in the CNS remains to be established. The aim of this study was to examine whether experimentally induced CNS-endogenous Type I IFN influences EAE. Using IFN-β reporter mice, we showed that direct administration of polyinosinic-polycytidylic acid (poly I:C), a potent inducer of IFN-β, into the cerebrospinal fluid induced increased leukocyte numbers and transient upregulation of IFN-β in CD45/CD11b-positive cells located in the meninges and choroid plexus, as well as enhanced IFN-β expression by parenchymal microglial cells. Intrathecal injection of poly I:C to mice showing first symptoms of EAE substantially increased the normal disease-associated expression of IFN-α, IFN-β, interferon regulatory factor-7 and IL-10 in CNS, and disease worsening was prevented for as long as IFN-α/β was expressed. In contrast, there was no therapeutic effect on EAE in poly I:C-treated IFN receptor-deficient mice. IFN-dependent microglial and astrocyte response included production of the chemokine CXCL10. These results show that Type I IFN induced within the CNS can play a protective role in EAE and highlight the role of endogenous type I IFN in mediating neuroprotection.
    • Interleukin-2 improves amyloid pathology, synaptic failure and memory in Alzheimer's disease mice.

      Alves, Sandro; Churlaud, Guillaume; Audrain, Mickael; Michaelsen-Preusse, Kristin; Fol, Romain; Souchet, Benoit; Braudeau, Jérôme; Korte, Martin; Klatzmann, David; Cartier, Nathalie; et al. (2017-03-01)
      Interleukin-2 (IL-2)-deficient mice have cytoarchitectural hippocampal modifications and impaired learning and memory ability reminiscent of Alzheimer's disease. IL-2 stimulates regulatory T cells whose role is to control inflammation. As neuroinflammation contributes to neurodegeneration, we investigated IL-2 in Alzheimer's disease. Therefore, we investigated IL-2 levels in hippocampal biopsies of patients with Alzheimer's disease relative to age-matched control individuals. We then treated APP/PS1ΔE9 mice having established Alzheimer's disease with IL-2 for 5 months using single administration of an AAV-IL-2 vector. We first found decreased IL-2 levels in hippocampal biopsies of patients with Alzheimer's disease. In mice, IL-2-induced systemic and brain regulatory T cells expansion and activation. In the hippocampus, IL-2 induced astrocytic activation and recruitment of astrocytes around amyloid plaques, decreased amyloid-β42/40 ratio and amyloid plaque load, improved synaptic plasticity and significantly rescued spine density. Of note, this tissue remodelling was associated with recovery of memory deficits, as assessed in the Morris water maze task. Altogether, our data strongly suggest that IL-2 can alleviate Alzheimer's disease hallmarks in APP/PS1ΔE9 mice with established pathology. Therefore, this should prompt the investigation of low-dose IL-2 in Alzheimer's disease and other neuroinflammatory/neurodegenerative disorders.
    • Visualizing production of beta interferon by astrocytes and microglia in brain of La Crosse virus-infected mice.

      Kallfass, Carsten; Ackerman, Andreas; Lienenklaus, Stefan; Weiss, Siegfried; Heimrich, Bernd; Staeheli, Peter; Department of Virology, University of Freiburg, Freiburg, Germany. (2012-10)
      Beta interferon (IFN-β) is a major component of innate immunity in mammals, but information on the in vivo source of this cytokine after pathogen infection is still scarce. To identify the cell types responsible for IFN-β production during viral encephalitis, we used reporter mice that express firefly luciferase under the control of the IFN-β promoter and stained organ sections with luciferase-specific antibodies. Numerous luciferase-positive cells were detected in regions of La Crosse virus (LACV)-infected mouse brains that contained many infected cells. Double-staining experiments with cell-type-specific markers revealed that similar numbers of astrocytes and microglia of infected brains were luciferase positive, whereas virus-infected neurons rarely contained detectable levels of luciferase. Interestingly, if a mutant LACV unable of synthesizing the IFN-antagonistic factor NSs was used for challenge, the vast majority of the IFN-β-producing cells in infected brains were astrocytes rather than microglia. Similar conclusions were reached in a second series of experiments in which conditional reporter mice expressing the luciferase reporter gene solely in defined cell types were infected with wild-type or mutant LACV. Collectively, our data suggest that glial cells rather than infected neurons represent the major source of IFN-β in LACV-infected mouse brains. They further indicate that IFN-β synthesis in astrocytes and microglia is differentially affected by the viral IFN antagonist, presumably due to differences in LACV susceptibility of these two cell types.