USP15 regulates type I interferon response in vivo and is required for pathogenesis of microbial and autoimmune neuroinflammation

Genes and pathways in which inactivation dampens tissue inflammation present new opportunities for understanding the pathogenesis of common human inflammatory diseases, including inflammatory bowel disease, rheumatoid arthritis and multiple sclerosis. We identified a mutation in the gene encoding the deubiquitination enzyme USP15 (Usp15L749R) that protected mice against both experimental cerebral malaria (ECM) induced by Plasmodium berghei and experimental autoimmune encephalomyelitis (EAE). Combining immunophenotyping and RNA sequencing in brain (ECM) and spinal cord (EAE) revealed that Usp15L749R-associated resistance to neuroinflammation was linked to dampened type I interferon responses in situ. In hematopoietic cells and in resident brain cells, USP15 was coexpressed with, and functionally acted together with the E3 ubiquitin ligase TRIM25 to positively regulate type I interferon responses and to promote pathogenesis during neuroinflammation. The USP15-TRIM25 dyad might be a potential target for intervention in acute or chronic states of neuroinflammation. Overall design: Sequencing of RNA extracted from target tissue in two experimental neuroinflammation models in wild-type (B6), USP15(L749R) and Trim25 KO mutant mice: (1) brains at day 3 and 5 following Plasmodium berghei ANKA (PbA) infection for the cerebral malaria model (ECM); and (2) spinal cords at day 7 following induction of experimental autoimmune encephalomyelitis (EAE) for B6 and Usp15 mutant mice only.

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Torre S, Polyak MJ, Langlais D, Fodil N, Kennedy JM, Radovanovic I, Berghout J, Leiva-Torres GA, Krawczyk CM, Ilangumaran S, Mossman K, Liang C, Knobeloch KP, Healy LM, Antel J, Arbour N, Prat A, Majewski J, Lathrop M, Vidal SM, Gros P