Author Of 1 Presentation
P0776 - Dual threats of CSPGs in multiple sclerosis through inhibiting oligodendrocyte repair and polarizing Th17 cells (ID 1167)
Abstract
Background
In multiple sclerosis (MS), oligodendrocytes and myelin are damaged by immune responses. Remyelination failure contributes to the axonal loss and progression of disability. The failed repair process could be the consequence of ongoing toxic neuroinflammation and to inhibitors in lesions. The extracellular matrix (ECM) molecules, including members of the chondroitin sulfate proteoglycan (CSPG) family, contribute to the altered microenvironment of MS lesions. CSPGs, particularly versican V1, have been described to directly inhibit the differentiation of oligodendrocyte precursor cells (OPCs) and to prevent remyelination.
Objectives
Herein, we examined ECM members for their expression in lesions of MS and experimental autoimmune encephalomyelitis (EAE), a model of MS, and addressed whether these ECM molecules alter immune responses that then affect tissue repair in MS lesions.
Methods
EAE was induced with MOG peptide 35-55 in CFA and spinal cord tissues were evaluated.Immunofluorescence staining and confocal microscopy were employed to determine which members of ECM are altered in EAE lesions.To assess the effect of ECM molecules on T cells, isolated T cells from 2D2 mice were cultured on ECM coated wells and were then activated with MOG-loaded dendritic cells and polarized to Th17 subset. The frequency of Th17 was determined using flow cytometry 5 days later.
Results
we found increased levels in spinal cord EAE lesions of versican V1, fibronectin, thrombospondin-1 and heparan sulfate proteoglycans (HSPGs), but not versican V2 or aggrecan. Versican V1 deposition was confirmed in active MS lesions. In culture, a mixed CSPG preparation and purified versican V1, but not other ECM molecules tested, shifted T cell differentiation toward Th17 cells, which were then inhibitory for OPC differentiation. CSPG-polarized Th17 cells also killed OPCs. To inhibit CSPG synthesis in vivo, EAE mice were injected with difluorosamine (peracetylated,4,4-difluoro-N-acetylglucosamine) starting at the peak of clinical disease severity. Difluorosamine-treated mice has reduced injury-enhanced versican content in spinal cord lesions correspondent with lower frequency of Th17 cells. To study the effect of difluorosamine on remyelination during EAE, NG2-Cre:Tau-mGFP mice were used with GFP expression localized to newly formed oligodendrocytes and myelin. We found that difluorosamine reduced levels of versican V1 in well-formed EAE lesions resulting in higher number of new oligodendrocytes and myelin sheets around and within lesions
Conclusions
These results highlight lesion-elevated CSPGs, especially versican V1, in directly inhibiting OPCs and indirectly in shaping T cell responses which then impact remyelination outcomes. We propose CSPG-lowering drugs as dual pronged repair therapeutics that directly affect OPCs, and that indirectly antagonize Th17 roles in inflammation and oligodendrocyte injury.