Zurich Open Repository and Archive University of Zurich Main Library Strickhofstrasse 39 CH-8057 Zurich www.zora.uzh.ch Year: 2007 Priming and target recognition of autoimmune pathogenic T cells Greter, Melanie Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-163734 Dissertation Published Version Originally published at: Greter, Melanie. Priming and target recognition of autoimmune pathogenic T cells. 2007, University of Zurich, Faculty of Science. PRIMING AND TARGET RECOGNITION OF AUTOIMMUNE PATHOGENIC T CELLS DISSERTATION zur Erlangung der naturwissenschaftlichen Doktorwürde (Dr. Sc. nat.) vorgelegt der Mathematisch-naturwissenschaftlichen Fakultät der Universität Zürich von MELANIE GRETER von Greppen LU Promotionskomitee Prof. Dr. Esther Stöckli (Vorsitz) Prof. Dr. Burkhard Becher (Leitung der Dissertation) Prof. Dr. Adriano Fontana Zürich 2007 DISCLAIMER The thesis is based on the following publications: • Induction of primary T cell immunity in the absence of secondary lymphoid tissues Melanie Greter, Burkhard Becher (submitted) • Antigen presentation in autoimmunity and CNS-inflammation: How T lymphocytes recognize the brain Burkhard Becher, Ingo Bechmann, Melanie Greter Journal of Molecular Medicine 2006 (1). • Dendritic cells permit immune invasion of the CNS in an animal model of multiple sclerosis Melanie Greter, Frank L Heppner, Maria P Lemos, Berhard M Odermatt, Norbert Goebels, Terri Laufer, Randolph J Noelle, Burkhard Becher Nature Medicine 2005 (2) • Experimental autoimmune encephalomyelitis repressed by microglial paralysis Frank L Heppner, Melanie Greter, Denis Marino, Jeppe Falsig, Gennadij Raivich, Nadine Hövelmeyer, Ari Waisman, Thomas Rülicke, Marco Prinz, Josef Priller, Burkhard Becher, Adriano Aguzzi Nature Medicine 2005 (3) 2 TABLE OF CONTENTS DISCLAIMER 2 ABBREVIATIONS 4 SUMMARY 5 ZUSAMMENFASSUNG 6 INTRODUCTION 7 ADAPTIVE IMMUNITY AND AUTOIMMUNITY 7 EVOLUTION OF ADAPTIVE IMMUNITY AND THE ROLE OF PERIPHERAL LYMPHOID TISSUES 8 EVOLUTION OF ADAPTIVE IMMUNITY 8 SECONDARY LYMPHOID TISSUES 9 TERTIARY LYMPHOID TISSUES 11 ALYMPHOPLASTIC MICE 11 The role of NFkB-inducing kinase 11 Alymphoplasia mice DENDRITIC CELLS: PROFESSIONAL APCS AND REGULATORS OF IMMUNE RESPONSES 14 TOLERANCE VERSUS AUTOIMMUNITY 15 DENDRITIC CELL SUBTYPES AND FUNCTIONS 16 THE PATHOGENESIS OF CNS-AUTOIMMUNE DISEASES 17 MULTIPLE SCLEROSIS 17 EXPERIMENTAL AUTOIMMUNE ENCEPHALOMYELITIS 18 Encephalitogenicity 19 THE BLOOD BRAIN BARRIER AND THE IMMUNE PRIVILEGE OF THE CNS 20 ANTIGEN PRESENTATION AND TARGET RECOGNITION IN EAE 21 MICROGLIA – SENTINELS OF THE CNS PARENCHYMA 22 CNS-ASSOCIATED DENDRITIC CELLS - SENTINELS AT THE GATEWAY TO THE CNS 24 PUBLICATIONS 27 1. INDUCTION OF PRIMARY T CELL IMMUNITY IN THE ABSENCE OF SECONDARY LYMPHOID TISSUES 2. EXPERIMENTAL AUTOIMMUNE ENCEPHALOMYELITIS REPRESSED BY MICROGLIAL PARALYSIS 3. DENDRITIC CELLS PERMIT IMMUNE INVASION OF THE CNS IN AN ANIMAL MODEL OF MULTIPLE SCLEROSIS DISCUSSION 64 T CELL PRIMING PHASE 64 T CELL PRIMING IN THE ABSENCE OF SLTS 64 ALTERNATIVE SITES FOR T CELL PRIMING 66 LYMPHOID NEOGENESIS 68 RECRUITMENT AND EFFECTOR PHASE 69 IDENTIFICATION OF CELL TYPES NECESSARY TO PERMIT IMMUNE INVASION OF THE CNS AND DISEASE DEVELOPMENT 69 APCS RESIDING IN SLTS 69 MICROGLIA – RESIDENT GUARDS OF THE CNS 70 CNS-ASSOCIATED DCS – SENTINELS AT THE GATEWAY TO THE CNS 71 CONCLUDING REMARKS 74 REFERENCES 75 ACKNOWLEDGEMENTS 80 3 ABBREVIATIONS Ab: Antibody Ag: Antigen APC: Antigen-presenting cell BM Bone marrow CNS: Central nervous system CTL: Cytotoxic T lymphocyte DC: Dendritic cell EAE: Experimental autoimmune encephalomyelitis FDC: Follicular dendritic cell GC: Germinal center Ig: Immunoglobulin IFNγ: Interferon gamma IL: Interleukin LPS: Lipopolysaccharide LTα: Lymphotoxin alpha LTβR: Lymphotoxin beta receptor MBP: Myelin basic protein MHCI: Major histocompatibility complex class I MHCII: Major histocompatibility complex class II MOG: Myelin oligodendrocyte glycoprotein MS: Multiple sclerosis NFκB: Nuclear factor kappa B NIK: NFκB-inducing kinase NK: Natural killer cell NKT: Natural killer T cell PLP: Proteolipid protein RAG: Recombination-activation gene s.c.: Subcutaneous SLT: Secondary lymphoid tissue TCR: T-cell receptor TGF-β: Transforming growth factor-beta TH: T-helper cells Tc: Cytotoxic T cell TMEV-IDD: Theiler’s murine encephalomyelitis virus-induced demyelinating disease TNF-α: Tumor necrosis factor alpha TLR: Toll-like receptor Treg: Regulatory T cell Wt: Wild-type 4 Melanie Greter Dissertation 2007 SUMMARY Subcutaneuos immunization with protein antigen (Ag) leads to the licensing of local dendritic cells (DCs) and the initiation of T cell priming. At the site of immunization, DCs take up the antigen (Ag) and subsequently migrate into the regional lymph nodes where they initiate the activation and expansion of T cells recognizing their cognate Ag. The structural environment within secondary lymphoid tissues (SLTs) is considered essential for the initiation of adaptive immunity. However, we discovered that immunization-induced T cell priming can occur outside of such dedicated SLTs. While B cell priming is highly dependant on the topography of SLTs, effective T cell immunity can occur completely independent of lymphoreticular structures. In the absence of SLTs, the liver displays the potential to serve as an alternative site for T- cell priming. After successful T cell priming occurred, T cells migrate through the body's tissues in search of their cognate Ag, which needs to be presented by an Ag-presenting cell (APC) in the context of major histocompatibility complex class II. When a self-Ag, such as CNS-myelin is the prime target, T cells re-encouter their cognate Ag presented by central nervous system (CNS)-associated DCs in perivascular spaces, which is an absolute requirement for the development of experimental autoimmune encephalomyelitis. After this second encounter with their cognate Ag, myelin-reactive T cells cross the glia limitans and enter the CNS parenchyma where they interact with CNS-resident microglia. Microglia do not serve as classical APCs, however they will produce a host of vasoactive substances, cytokines and chemokines leading to the invasion of other leukocytes and the development of a tissue lesion. While the precise molecular mechanisms of the disease pathogenesis will need to be elucidated in the future, our findings have provided a great leap of our understanding of the spatial and temporal process occurring during autoimmune diseases. 5 Melanie Greter Dissertation 2007 ZUSAMMENFASSUNG Subkutane Immunisierung mit Protein-Antigen führt zur Aktivierung von dendritischen Zellen (DCs) und T-Zell „priming“. Nachdem DCs das Antigen (Ag) lokal aufgenommen haben, migrieren sie in die regionalen Lymphknoten, wo sie die Aktivierung und Expansion von T Zellen induzieren, welche das Ag erkennen. Sekundäre lymphatische Organe (SLOs) mit ihren klar abgegrenzten T- und B- Zellzonen werden als auschlaggebend für die Entwicklung adaptiver Immunität betrachtet. Wir haben jedoch entdeckt, dass Immunisierungs-induziertes T-Zell „priming“ auch ausserhalb von solch definierten Strukturen stattfinden kann. Während effektive B-Zellaktivierung von der Topographie in SLOs abhängig ist, funktioniert T-Zellaktivierung ohne lymphoretikuläre Strukturen. Wir haben herausgefunden, dass in der Abwesenheit von SLOs möglicherweise die Leber als Organ für T-Zell „priming“ dienen könnte. Nachdem T-Zell „priming“ erfolgreich stattgefunden hat, verlassen die T Zellen die SLOs um den Körper nach ihrem spezifischen Ag zu durchsuchen, das auf dem „major histocompatibility complex class II“ von Ag-präsentierenden Zellen (APZs) präsentiert weren muss. Wenn ein Selbst-Ag das Angriffsziel ist, wie z.B Myelin im Zentralnervensystem (ZNS), treffen die Myelin-reaktiven T Zellen im perivaskulären Raum auf DCs, welche ihnen ihr Ag präsentieren. Dieser Schritt ist absolut entscheidend für die Entstehung der experimentellen Autoimmun-Enzephalomeylitis. Nach der Wiedererkennung des Ags migrieren die Myelin-reaktiven T Zellen durch die Glia Limitans und dringen in das Parenchym des ZNS ein. Dort interagieren sie mit ZNS-angesiedelten Microgliazellen, die daraufhin aktiviert werden. Microglia dienen nicht als klassische APZs, sekretieren jedoch vasoaktive Substanzen, Zytokine und Chemokine, wodurch die Invasion von Leukozyten und die Entwicklung einer Läsion herbeiführt wird. Während die genauen molekularen Mechanismen des Krankheitsverlaufes zukünftig noch genauer untersucht werden müssen, haben unsere Daten einen grossen Erkenntnisgewinn im räumlichen sowie zeitlichen Ablauf autoimmuner Erkrankungen erbracht . 6 Melanie Greter Dissertation 2007 INTRODUCTION INTRODUCTION ADAPTIVE IMMUNITY AND AUTOIMMUNITY The mammalian immune system constitutes antigen (Ag)-non-specific innate immunity and Ag-specific adaptive immunity. Innate immunity comprises the first line of defense against pathogens whereby phagocytic cells (e.g. macrophages, neutrophils) and natural killer (NK) cells are considered key players in eliminating infections. A prime feature of innate immunity is its capacity to recognize a vast array of patterns shared by many pathogens through germline-encoded pattern recognition receptors (Toll-like receptors (TLRs)). While innate immune responses can act rapidly immediately after recognition of molecular patterns, adaptive immunity requires significantly more time to develop. These two arms of immunity are not separate entities but heavily intertwined