The deubiquitinase OTUD7B ameliorates central nervous system autoimmunity by inhibiting degradation of glial fibrillary acidic protein and astrocyte hyperinflammation

Astrocytes are central to the pathogenesis of multiple sclerosis; however, their regulation by intrinsic post-translational ubiquitination and deubiquitination is unresolved. This study shows that the deubiquitinating enzyme OTUD7B in astrocytes confers protection against murine experimental autoimmune encephalomyelitis, a model of MS, by limiting neuroinflammation. RNA-sequencing of isolated astrocytes and spatial transcriptomics showed that in EAE OTUD7B downregulates the expression of chemokines in astrocytes of inflammatory lesions, which is associated with reduced recruitment of encephalitogenic CD4+ T cells. Furthermore, OTUD7B was essential for GFAP protein expression of astrocytes bordering inflammatory lesions. Mechanistically, OTUD7B (i) restricted TNF-induced chemokine production of astrocytes by sequential K63- and K48-deubiquitination of RIPK1 limiting NF-κB and MAPK activation and (ii) enabled GFAP protein expression by supporting GFAP mRNA expression and preventing its proteasomal degradation through K48-deubiquitination of GFAP. This dual action on TNF signaling and GFAP identifies astrocyte-intrinsic OTUD7B as a central inhibitor of astrocyte-mediated inflammation.