Central Nervous System-Endogenous TLR7 and TLR9 Induce Different Immune Responses and Effects on Experimental Autoimmune Encephalomyelitis

Innate receptors, including Toll like receptors (TLRs), are implicated in pathogenesis of CNS inflammatory diseases such as multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE). TLR response to pathogens or endogenous signals includes production of immunoregul...

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Main Authors: Ruthe Storgaard Dieu, Vian Wais, Michael Zaucha Sørensen, Joanna Marczynska, Magdalena Dubik, Stephanie Kavan, Mads Thomassen, Mark Burton, Torben Kruse, Reza Khorooshi, Trevor Owens
Format: Article
Language:English
Published: Frontiers Media S.A. 2021-06-01
Series:Frontiers in Neuroscience
Subjects:
Online Access:https://www.frontiersin.org/articles/10.3389/fnins.2021.685645/full
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author Ruthe Storgaard Dieu
Vian Wais
Michael Zaucha Sørensen
Joanna Marczynska
Magdalena Dubik
Stephanie Kavan
Mads Thomassen
Mark Burton
Torben Kruse
Reza Khorooshi
Trevor Owens
author_facet Ruthe Storgaard Dieu
Vian Wais
Michael Zaucha Sørensen
Joanna Marczynska
Magdalena Dubik
Stephanie Kavan
Mads Thomassen
Mark Burton
Torben Kruse
Reza Khorooshi
Trevor Owens
author_sort Ruthe Storgaard Dieu
collection DOAJ
description Innate receptors, including Toll like receptors (TLRs), are implicated in pathogenesis of CNS inflammatory diseases such as multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE). TLR response to pathogens or endogenous signals includes production of immunoregulatory mediators. One of these, interferon (IFN)β, a Type I IFN, plays a protective role in MS and EAE. We have previously shown that intrathecal administration of selected TLR ligands induced IFNβ and infiltration of blood-derived myeloid cells into the central nervous system (CNS), and suppressed EAE in mice. We have now extended these studies to evaluate a potential therapeutic role for CNS-endogenous TLR7 and TLR9. Intrathecal application of Imiquimod (TLR7 ligand) or CpG oligonucleotide (TLR9 ligand) into CNS of otherwise unmanipulated mice induced IFNβ expression, with greater magnitude in response to CpG. CD45+ cells in the meninges were identified as source of IFNβ. Intrathecal CpG induced infiltration of monocytes, neutrophils, CD4+ T cells and NK cells whereas Imiquimod did not recruit blood-derived CD45+ cells. CpG, but not Imiquimod, had a beneficial effect on EAE, when given at time of disease onset. This therapeutic effect of CpG on EAE was not seen in mice lacking the Type I IFN receptor. In mice with EAE treated with CpG, the proportion of monocytes was significantly increased in the CNS. Infiltrating cells were predominantly localized to spinal cord meninges and demyelination was significantly reduced compared to non-treated mice with EAE. Our findings show that TLR7 and TLR9 signaling induce distinct inflammatory responses in the CNS with different outcome in EAE and point to recruitment of blood-derived cells and IFNβ induction as possible mechanistic links between TLR9 stimulation and amelioration of EAE. The protective role of TLR9 signaling in the CNS may have application in treatment of diseases such as MS.
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spelling doaj.art-b64a2d79216d4c6dbb396a2f748f9b862022-12-21T18:43:01ZengFrontiers Media S.A.Frontiers in Neuroscience1662-453X2021-06-011510.3389/fnins.2021.685645685645Central Nervous System-Endogenous TLR7 and TLR9 Induce Different Immune Responses and Effects on Experimental Autoimmune EncephalomyelitisRuthe Storgaard Dieu0Vian Wais1Michael Zaucha Sørensen2Joanna Marczynska3Magdalena Dubik4Stephanie Kavan5Mads Thomassen6Mark Burton7Torben Kruse8Reza Khorooshi9Trevor Owens10Department of Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, DenmarkDepartment of Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, DenmarkDepartment of Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, DenmarkDepartment of Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, DenmarkDepartment of Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, DenmarkDepartment of Clinical Genetics, Odense University Hospital, Institute of Clinical Research, University of Southern Denmark, Odense, DenmarkDepartment of Clinical Genetics, Odense University Hospital, Institute of Clinical Research, University of Southern Denmark, Odense, DenmarkDepartment of Clinical Genetics, Odense University Hospital, Institute of Clinical Research, University of Southern Denmark, Odense, DenmarkDepartment of Clinical Genetics, Odense University Hospital, Institute of Clinical Research, University of Southern Denmark, Odense, DenmarkDepartment of Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, DenmarkDepartment of Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, DenmarkInnate receptors, including Toll like receptors (TLRs), are implicated in pathogenesis of CNS inflammatory diseases such as multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE). TLR response to pathogens or endogenous signals includes production of immunoregulatory mediators. One of these, interferon (IFN)β, a Type I IFN, plays a protective role in MS and EAE. We have previously shown that intrathecal administration of selected TLR ligands induced IFNβ and infiltration of blood-derived myeloid cells into the central nervous system (CNS), and suppressed EAE in mice. We have now extended these studies to evaluate a potential therapeutic role for CNS-endogenous TLR7 and TLR9. Intrathecal application of Imiquimod (TLR7 ligand) or CpG oligonucleotide (TLR9 ligand) into CNS of otherwise unmanipulated mice induced IFNβ expression, with greater magnitude in response to CpG. CD45+ cells in the meninges were identified as source of IFNβ. Intrathecal CpG induced infiltration of monocytes, neutrophils, CD4+ T cells and NK cells whereas Imiquimod did not recruit blood-derived CD45+ cells. CpG, but not Imiquimod, had a beneficial effect on EAE, when given at time of disease onset. This therapeutic effect of CpG on EAE was not seen in mice lacking the Type I IFN receptor. In mice with EAE treated with CpG, the proportion of monocytes was significantly increased in the CNS. Infiltrating cells were predominantly localized to spinal cord meninges and demyelination was significantly reduced compared to non-treated mice with EAE. Our findings show that TLR7 and TLR9 signaling induce distinct inflammatory responses in the CNS with different outcome in EAE and point to recruitment of blood-derived cells and IFNβ induction as possible mechanistic links between TLR9 stimulation and amelioration of EAE. The protective role of TLR9 signaling in the CNS may have application in treatment of diseases such as MS.https://www.frontiersin.org/articles/10.3389/fnins.2021.685645/fulltoll-like receptorinnate signalingexperimental autoimmune encephalomyelitismonocytesType I interferons
spellingShingle Ruthe Storgaard Dieu
Vian Wais
Michael Zaucha Sørensen
Joanna Marczynska
Magdalena Dubik
Stephanie Kavan
Mads Thomassen
Mark Burton
Torben Kruse
Reza Khorooshi
Trevor Owens
Central Nervous System-Endogenous TLR7 and TLR9 Induce Different Immune Responses and Effects on Experimental Autoimmune Encephalomyelitis
Frontiers in Neuroscience
toll-like receptor
innate signaling
experimental autoimmune encephalomyelitis
monocytes
Type I interferons
title Central Nervous System-Endogenous TLR7 and TLR9 Induce Different Immune Responses and Effects on Experimental Autoimmune Encephalomyelitis
title_full Central Nervous System-Endogenous TLR7 and TLR9 Induce Different Immune Responses and Effects on Experimental Autoimmune Encephalomyelitis
title_fullStr Central Nervous System-Endogenous TLR7 and TLR9 Induce Different Immune Responses and Effects on Experimental Autoimmune Encephalomyelitis
title_full_unstemmed Central Nervous System-Endogenous TLR7 and TLR9 Induce Different Immune Responses and Effects on Experimental Autoimmune Encephalomyelitis
title_short Central Nervous System-Endogenous TLR7 and TLR9 Induce Different Immune Responses and Effects on Experimental Autoimmune Encephalomyelitis
title_sort central nervous system endogenous tlr7 and tlr9 induce different immune responses and effects on experimental autoimmune encephalomyelitis
topic toll-like receptor
innate signaling
experimental autoimmune encephalomyelitis
monocytes
Type I interferons
url https://www.frontiersin.org/articles/10.3389/fnins.2021.685645/full
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