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Diverse injury responses of human oligodendrocyte to mediators implicated in multiple sclerosis

ABSTRACT: Early multiple sclerosis lesions feature relative preservation of oligodendrocyte cell bodies with dying back retraction of their myelinating processes. Cell loss occurs with disease progression. Putative injury mediators include metabolic stress (low glucose/nutrient), pro-inflammatory mediators (interferon γ and tumor necrosis factor a), and excitotoxins (glutamate). Our objective was to compare the impact of these disease relevant mediators on the injury responses of human mature oligodendrocytes. In the current study, we determined the effects of these mediators on process extension and survival of human brain derived mature oligodendrocytes in vitro and used bulk RNA sequencing to identify distinct effector mechanisms that underlie the responses. All mediators induced significant process retraction of the oligodendrocytes in dissociated cell culture. Only metabolic stress (low glucose/nutrient) conditions resulted in delayed (4-6 days) non-apoptotic cell death. Metabolic effects were associated with induction of the integrated stress response, which can be protective or contribute to cell injury dependent on its level and duration of activation. Addition of Sephin1, an agonist of the integrated stress response induced process retraction under control conditions and further enhanced retraction under metabolic stress conditions. The antagonist ISRIB restored process outgrowth under stress conditions, and if added to already stressed cells, reduced delayed cell death and prolonged the period in which recovery could occur. Inflammatory cytokine functional effects were associated with activation of multiple signaling pathways (including Jak/Stat-1) that regulate process outgrowth, without integrated stress response induction. Glutamate application produced limited transcriptional changes suggesting a contribution of effects directly on cell processes.

ORGANISM(S): Homo sapiens

PROVIDER: GSE249381 | GEO | 2023/12/08

REPOSITORIES: GEO

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Project description:Increasing evidence indicates heterogeneity in functional and molecular properties of oligodendrocyte lineage cells both during development and under pathologic conditions. In multiple sclerosis, remyelination of grey matter lesions exceeds that in white matter. Here we used cells derived from grey matter versus white matter regions of surgically resected human brain tissue samples, to compare the capacities of human A2B5-positive progenitor cells and mature oligodendrocytes to ensheath synthetic nanofibers, and relate differences to the molecular profiles of these cells. For both cell types, the percentage of ensheathing cells was greater for grey matter versus white matter cells. For both grey matter and white matter samples, the percentage of cells ensheathing nanofibers was greater for A2B5-positive cells versus mature oligodendrocytes. Grey matter A2B5-positive cells were more susceptible than white matter A2B5-positive cells to injury induced by metabolic insults. Bulk RNA sequencing indicated that separation by cell type (A2B5-positive vs mature oligodendrocytes) is more significant than by region but segregation for each cell type by region is apparent. Molecular features of grey matter versus white matter derived A2B5-positive and mature oligodendrocytes were lower expression of mature oligodendrocyte genes and increased expression of early oligodendrocyte lineage genes. Genes and pathways with increased expression in grey matter derived cells with relevance for myelination included those related to responses to external environment, cell-cell communication, cell migration, and cell adhesion. Immune and cell death related genes were up-regulated in grey matter derived cells. We observed a significant number of up-regulated genes shared between the stress/injury and myelination processes, providing a basis for these features. In contrast to oligodendrocyte lineage cells, no functional or molecular heterogeneity was detected in microglia maintained in vitro, likely reflecting the plasticity of these cells ex vivo. The combined functional and molecular data indicate that grey matter human oligodendrocytes have increased intrinsic capacity to myelinate but also increased injury susceptibility, in part reflecting their being at a stage earlier in the oligodendrocyte lineage.