p38γMAPK delays myelination and remyelination and is abundant in multiple sclerosis lesions

Abstract

Multiple Sclerosis is a chronic inflammatory disease in which disability results from the disruption of myelin and axons. During the initial stages of the disease, injured myelin is replaced by mature myelinating oligodendrocytes that differentiate from oligodendrocyte precursor cells. However, myelin repair fails in secondary and chronic progressive stages of the disease and with aging, as the environment becomes progressively more hostile. This may be attributable to inhibitory molecules in the multiple sclerosis environment including activation of the p38MAPK family of kinases. We explored oligodendrocyte precursor cell differentiation and myelin repair using animals with conditional ablation of p38MAPK{gamma} from oligodendrocyte precursors. We found that p38{gamma}MAPK ablation accelerated oligodendrocyte precursor cell differentiation and myelination. This resulted in an increase in both the total number of oligodendrocytes and the migration of progenitors ex vivo and faster remyelination in the cuprizone model of demyelination/remyelination. Consistent with its role as an inhibitor of myelination, p38{gamma}MAPK was significantly downregulated as oligodendrocyte precursor cells matured into oligodendrocytes. Notably, p38{gamma}MAPK was enriched in samples of leukocortical multiple sclerosis lesions from patients, which represent areas of failed remyelination. Our data suggest that p38{gamma} could be targeted to improve myelin repair in multiple sclerosis.