Activation of the astrocytic Nrf2/ARE system ameliorates the formation of demyelinating lesions in a multiple sclerosis animal model

Oxidative stress critically contributes to the pathogenesis of a variety of neurodegenerative diseases such as multiple sclerosis. Astrocytes are the main regulators of oxidative homeostasis in the brain and dysregulation of these cells likely contributes to the accumulation of oxidative damage. The nuclear factor erythroid 2‐related factor 2 (Nrf2) is the main transcriptional regulator of the anti‐oxidant stress defense. In this study, we elucidate the effects of astrocytic Nrf2‐activation on brain‐intrinsic inflammation and lesion development. Cells deficient for the Nrf2 repressor kelch‐like ECH‐associated protein 1 (Keap1) are characterized by hyperactivation of Nrf2‐signaling. Therefore, wild type mice and mice with a GFAP‐specific Keap1‐deletion were fed with 0.25% cuprizone for 1 or 3 weeks. Cuprizone intoxication induced pronounced oligodendrocyte loss, demyelination and reactive gliosis in wild type animals. In contrast, astrocyte‐specific Nrf2‐activation was sufficient to prevent oligodendrocyte loss and demyelination, to ameliorate brain intrinsic inflammation and to counteract axonal damage. Our results highlight the potential of the Nrf2/ARE system for the treatment of neuroinflammation in general and of multiple sclerosis in particular. © GLIA 2016;64:2219–2230 Main Points The activation of the astrocytic Nrf2/Are system ameliorates oligodendrocyte loss, microglia activation and demyelination in an animal model of multiple sclerosis.