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Identification of trafficking molecules involved in the migration of CD8 T cells across the blood-brain barrier during immunosurveillance and neuroinflammation

Applicant Engelhardt Britta
Number 149420
Funding scheme Project funding (Div. I-III)
Research institution Theodor Kocher Institut Medizinische Fakultät Universität Bern
Institution of higher education University of Berne - BE
Main discipline Immunology, Immunopathology
Start/End 01.10.2013 - 30.09.2016
Approved amount 518'661.00
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All Disciplines (2)

Discipline
Immunology, Immunopathology
Neurophysiology and Brain Research

Keywords (6)

lymphocyte trafficking; CD8 T cells; blood-cerebrospinal fluid barrier; serial block face scanning electron microscopy; blood-brain barrier; live cell imaging

Lay Summary (German)

Lead
Dieses Forschungsprojekt untersucht die zellulären und molekularen Mechanismen der Einwanderung von CD8 Killer T Zellen in das zentrale Nervensystem während entzündlicher Prozesse im ZNS.
Lay summary
±Bei der Multiplen Sklerose (MS) greifen Immunzellen, die normalerweise unseren Körper vor Krankheitserregern schützen, das zentrale Nervensystem (ZNS) an. Vom Blutkreislauf aus gelangen sie über die Blut-Hirn-Schranke (BHS) in das ZNS und zerstören dort die Isolationsschicht von Nervenzellen, das Myelin. Dies führt zu vielfältigen Störungen der Infor-mationsübermittlung der Nervenzellen und daher zum variablen klinischen Erscheinungsbild der MS.  
Zur Navigation durch den Körper verwenden Immunzellen bestimmte Adhäsions und Signalmoleküle auf ihrer Oberfläche. Das Adhäsionsmolekül VLA-4 vermittelt z.B. das Andocken von autoagressiven Helfer T Zellen an die BHS. Das Medikament Natalizumab blockiert VLA-4 und verhindert deshalb das Auswandern der autoagressiven Helfer T Zellen in das ZNS. Abklingen der Entzündung im ZNS lindert das klinische Erscheinungsbild der MS. Leider führt die Behandlung mit Natalizumab nach längerer Behandlungsdauer in ca. 1 von 1000 MS Patienten zur Reaktivierung eines Virus, welcher Zellen im ZNS schädigt.  Dies spricht dafür, dass Natalizumab auch das Einwandern von Killer T Zellen, welche das Virus im ZNS in Schach halten, blockiert und somit die Immunüberwachung im ZNS zusammenbricht.
Weitere Befunde zeigen mittlerweile, dass Killer T Zellen auch eine Rolle bei der Pathogenese der Multiplen Sklerose spielen können.
In unsererm Forschungsprojekt wollen wir die molekularen Signale, welche Killer T Zellen zur Einwanderung in das ZNS verwenden identifizieren. Dazu verwenden wir neue Killerzell vermittelte in vivo Entzüngsmodelle des ZNS und verschiedene bildgebende Verfahren. Wir werden die Auswanderung von Killer T Zellen aus dem Blutkreislauf in vivo und in vitro mit Zeitraffervideoaufnahmen und modernster Mikroskopie analysieren. Wir hoffen in unserem Forschungsprojekt, Killerzell-spezifische Mechanismen bei der Einwanderung dieser T Zellen in das ZNS zu entdecken. Dies wäre der Ansatzpunkt im sichere Therapien für die MS zu entwickeln.

Direct link to Lay Summary Last update: 29.10.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Migration of encephalitogenic CD8 T cells into the central nervous system is dependent on the α4β1-integrin.
Martin-Blondel Guillaume (2016), Migration of encephalitogenic CD8 T cells into the central nervous system is dependent on the α4β1-integrin., in European Journal of immunology, 45, 3302.
Post-arrest stalling rather than crawling favors CD8+ over CD4+ T-cell migration across the blood-brain barrier under flow in vitro
Rudolph Henriette (2016), Post-arrest stalling rather than crawling favors CD8+ over CD4+ T-cell migration across the blood-brain barrier under flow in vitro, in European Journal of Immunology, 9/16(46), 2187-2203.

Collaboration

Group / person Country
Types of collaboration
Prof. Thorsten Mempel, Harvard Medical School United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Prof. Roland Liblau, INSERM Tolouse France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Exchange of personnel
Dr. Federica Sallusto, IRB, Bellinzona Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Exchange of personnel
Prof. Roméo Cecchelli, University of Lens France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Exchange of personnel
Prof. Thomas Hünig, University of Würzburg Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Exchange of personnel
Prof. JAmes McGrath United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
Prof. Horst Schroten, University Clinic Mannheim Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Exchange of personnel
Prof. Benoit Zuber, Institute for Anatomy, University of Bern Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
50th Anniversary of ARSEP Talk given at a conference Focus on T cells: endothelial interaction during neuroinflammation 24.05.2019 Paris, France Engelhardt Britta;


Awards

Title Year
Fellowship of the Swiss MS Society and ECTRIMS Fellowship 2015

Associated projects

Number Title Start Funding scheme
141773 ProDoc Cell Migration Research Module 3: Soluble factors in Cell Migration 01.10.2012 ProDoc
154483 Unraveling the immune etiology of multiple sclerosis - UnmetMS 01.10.2014 Sinergia
133092 Defining the specific role of endothelial-expressed Ig-superfamily cell adhesion molecules (IgCAMs) in mediating the individual steps involved in T cell extravasation across the blood-brain barrier in vitro and in vivo 01.10.2010 Project funding (Div. I-III)
170131 Anatomical routes and molecular mechanisms of T cell migration across the brain barriers 01.10.2016 Project funding (Div. I-III)
137127 ProDoc Cell Migration Research Module I: Immune cell migration in immunosurveillance and inflammation 01.10.2011 ProDoc

Abstract

Multiple sclerosis (MS) is the most common inflammatory disease of the central nervous system (CNS) with unknown etiology to this date. Much of our current knowledge about MS pathogenesis was obtained from its animal model experimental autoimmune encephalomyelitis (EAE). As classical EAE is a CD4+ T cell mediated disease, it is unsuitable for adequately modeling other potential culprits such as CD8 T cells, which are the focus of the present proposal. Accumulating evidence points to a critical role of CD8+ T cells in MS pathogenesis. Indeed, CD8+ T cells outnumber CD4+ T cells in inflammatory lesions in post-mortem MS brains. Their identification as oligoclonal, myelin-reactive effector/memory CD8+ T cells suggests their cytotoxic and inflammatory contribution to MS pathogenesis within the CNS. This is further supported by recent genetic studies, which demonstrated an association between certain major histocompatibility (MHC) class I alleles and MS. Finally, antibody induced depletion of CD4+ T cells did not lead to clinical benefits in MS patients underlining the contribution of lymphocyte subsets other than CD4+ T cells to MS pathogenesis. - Inhibition of immune cell trafficking into the CNS with the humanized anti-a4-integrin antibody natalizumab is a successful therapeutic regimen for the treatment of MS but comes with a risk for progressive multifocal leukoencephalopathy (PML), an often fatal disease caused by JC virus infection of oligodendrocytes, suggesting that natalizumab may also target CD8+ T cell trafficking to the CNS. Therapeutic efficacy of blocking a4-integrins was discovered in EAE focussing our current insight into the molecular mechanisms involved in immune cell trafficking to the CNS largely on encephalitogenic CD4+ T cells. In contrast, our current understanding of the molecular mechanisms used by CD8+ T cells to migrate into the CNS in MS is rudimentary. - Immune cell recruitment into the CNS is controlled by both the highly specialized endothelial cells forming the blood-brain barrier (BBB) and the epithelial cells of the choroid plexus constituting the blood-cerebrospinal fluid barrier (BCSFB). By making use of novel rodent models for CD8+ T cell driven CNS autoimmunity and novel in vitro models for the human BBB and BCSFB combined with sophisticated live cell and novel 3D ultrastructural imaging techniques we aim to identify the anatomical route and the traffic signals involved in the multi-step recruitment of CD8+ T cell subsets into the CNS during immunosurveillance and neuroinflammation. Under Specific Aim 1 we will address the molecular mechanisms mediating the dynamic multi-step migration of TCR transgenic ovalbumin (OVA) specific CD8+ T cell subsets across the inflamed or non-inflamed BBB by live cell imaging under physiological flow in vitro. The requirement of endothelial antigen presentation for CD8+ T cell migration across the BBB will be addressed by visualization of NFAT-nucleocytoplasmic shuttling. Using in vitro BBB models, in which endothelial junctions are visualized by a VE-cadherin-GFP fusion protein, we will determine the mechanisms employed during paracellular or transcellular diapedesis of CD8+ T cell subsets across the BBB. To determine subcellular structures defining endothelial sites permissive for diapedesis, three-dimensional ultrastructural investigation of CD8 T cell migration across the BBB will be performed using serial block face scanning electron microscopy. Employing novel rodent models for CD8+ T cell driven CNS autoimmunity under Specific Aim 2, we will investigate the molecular mechanisms mediating the recruitment of antigen-specific CD8 T cells across the BBB in vivo by means of (2-photon) intravital microscopy (IVM) of the brain and the spinal cord microvasculature. Finally, employing novel human in vitro models for the BBB and the BCSFB under Specific Aim 3 we will determine, if the trafficking signals mediating CD8 T cell migration into the CNS in mice hold true for the migration of human CD8+ effector T cell subsets across these barriers under inflammatory and non-inflammatory conditions. Understanding the molecular mechanisms involved in CD8 T cell trafficking into the CNS will set the ground for improving our understanding of the benefits and risks associated with therapeutic targeting of T cell trafficking into the CNS during MS and will hopefully allow to identify novel molecular targets suited to specifically block CNS recruitment of destructive T cells while leaving the migration of protective T cell subsets into the CNS unaffected.
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