Contributions
Abstract: P1202
Type: Poster
Abstract Category: Therapy - disease modifying - Neuroprotection
Recent studies propose to Myelin-associated glycoprotein (MAG) as a functional receptor in oligodendrocytes (OLs), acting as a docking platform for different signal transduction pathways. However the impact of MAG activation in OLS remains elusive. We studied the effect of antibody-mediated MAG activation in OLS using a well characterized anti-MAG mAb that induces MAG crosslinking/activation of intracellular signaling. Methods: A MOG-induced animal model of chronic inflammatory demyelination characterized by the presence of extensive axonal degeneration and OLs cultures (primary or derived from CG4 cell line) were used to study the role of extracellular glutamate (Glu) uptake induced by antibody-mediated activation of MAG at the cell membrane of OLs. Monitoring of Glu concentrations in OL cultures was studied by using Föster resonance energy transfer (FRET)-based Glu biosensors. Results: We found that in primary OLs cultures mAb-mediated MAG activation induce: i) increase resistance to oxidative stress caused by Glu overload, ii) increase Glu uptake by OLs measured by Glu biosensors with differential cellular expression, iii) activates antioxidant defenses associated with a PKC-dependent activation/translocation of nuclear factor erythroid-related factor 2 to the nucleus analyzed by immunofluorescence and confocal microscopy, iv) increase the levels of reduced glutathione (GSH), the main cellular antioxidant element in a Xc- cysteine/Glu antiporter and Glu transporters-dependent manner and v) dramatically increase neuronal and glial survival exposed to Glu overload in cerebellar organotypic cultures. The impact of mAb-mediated MAG activation was then analyzed in the animal model of EAE induced by MOG. Compared to IgG isotype-matched control groups, intraperitoneal treatment with anti-MAG mAb prior to disease onset significantly delays the onset of clinical symptoms, ameliorates clinical expression of the disease, reduce axonal damaged of myelinated sensory axons from spinal cord (analyzed by electron microscopy) and reduce the amount of IL-17 secreted by peripheral mononuclear cells. Conclusion: these results allow us to propose OLs as critical modulators of high extracellular Glu concentration in white matter. This event results critical toward understanding demyelination-associated axonal damaged induced by Glu toxicity, opening a new opportunity for therapeutic intervention in MS.
Disclosure: This work was supported by grants from Mincyt PICT-PRH 98, PICT-2013-2416 and Secyt -Universidad Nacional de Córdoba to Pablo H. H. Lopez and a grant from MERCK-Serono to Edgardo Cristiano and Pablo H. H. Lopez. E Cristiano has received honoraria speaking and travel grants from MERCK Serono, NOvartis, Genzyme, Biogen and Teva Tuteur
Abstract: P1202
Type: Poster
Abstract Category: Therapy - disease modifying - Neuroprotection
Recent studies propose to Myelin-associated glycoprotein (MAG) as a functional receptor in oligodendrocytes (OLs), acting as a docking platform for different signal transduction pathways. However the impact of MAG activation in OLS remains elusive. We studied the effect of antibody-mediated MAG activation in OLS using a well characterized anti-MAG mAb that induces MAG crosslinking/activation of intracellular signaling. Methods: A MOG-induced animal model of chronic inflammatory demyelination characterized by the presence of extensive axonal degeneration and OLs cultures (primary or derived from CG4 cell line) were used to study the role of extracellular glutamate (Glu) uptake induced by antibody-mediated activation of MAG at the cell membrane of OLs. Monitoring of Glu concentrations in OL cultures was studied by using Föster resonance energy transfer (FRET)-based Glu biosensors. Results: We found that in primary OLs cultures mAb-mediated MAG activation induce: i) increase resistance to oxidative stress caused by Glu overload, ii) increase Glu uptake by OLs measured by Glu biosensors with differential cellular expression, iii) activates antioxidant defenses associated with a PKC-dependent activation/translocation of nuclear factor erythroid-related factor 2 to the nucleus analyzed by immunofluorescence and confocal microscopy, iv) increase the levels of reduced glutathione (GSH), the main cellular antioxidant element in a Xc- cysteine/Glu antiporter and Glu transporters-dependent manner and v) dramatically increase neuronal and glial survival exposed to Glu overload in cerebellar organotypic cultures. The impact of mAb-mediated MAG activation was then analyzed in the animal model of EAE induced by MOG. Compared to IgG isotype-matched control groups, intraperitoneal treatment with anti-MAG mAb prior to disease onset significantly delays the onset of clinical symptoms, ameliorates clinical expression of the disease, reduce axonal damaged of myelinated sensory axons from spinal cord (analyzed by electron microscopy) and reduce the amount of IL-17 secreted by peripheral mononuclear cells. Conclusion: these results allow us to propose OLs as critical modulators of high extracellular Glu concentration in white matter. This event results critical toward understanding demyelination-associated axonal damaged induced by Glu toxicity, opening a new opportunity for therapeutic intervention in MS.
Disclosure: This work was supported by grants from Mincyt PICT-PRH 98, PICT-2013-2416 and Secyt -Universidad Nacional de Córdoba to Pablo H. H. Lopez and a grant from MERCK-Serono to Edgardo Cristiano and Pablo H. H. Lopez. E Cristiano has received honoraria speaking and travel grants from MERCK Serono, NOvartis, Genzyme, Biogen and Teva Tuteur