MicroRNA-150 controls experimental autoimmune encephalomyelitis by regulating CD4 T cell differentiation and function [RNA-seq I]

MicroRNAs are small non-coding RNA molecules that have an important role in the fine tuning of all biological processes and are often found to be dysregulated in diseases, such as multiple sclerosis (MS). MS is an immune-mediated disease of the central nervous system characterized by demyelination, axonal loss and neurodegeneration. We have previously shown microRNA-150 (miR-150) levels to be elevated in cell-free cerebrospinal fluid (CSF) of MS patients compared to controls. The aim of this study is to further understand the physiopathological function of miR-150 using experimental autoimmune encephalomyelitis (EAE), a mouse model for MS. To establish its role in-vivo, we generated miR-150 knock-out (KO) and knock-in (KI) mice using CRISPR/Cas9. After induction of EAE, miR-150 KO mice showed ameliorated disease compared to WT littermate controls while miR-150 KI mice presented with exacerbated disease. An ameliorated disease in miR-150 KO was accompanied by a decreased infiltration of CD4 T cells compared to WT and KI. At priming stage of EAE we found that miR-150 KO had an increase in regulatory CD4 T cells (TREGS). Furthermore, after reconstitution of T cell deficient animals, CD4 T cells from miR-150 KO mice could protect against EAE and also showed an increased FOXP3 expression. A role of miR-150 in regulating TREG cells was further substantiated by transcriptome profiling, where miR-150 KO CD4 T cells suggested an enhancement of TREG phenotype as well as a diminished translation in miR-150 KO CD4 T cells. Moreover the results implicated miR-150 with mechanisms such as translation, autophagy and metabolism as well T cell proliferation and differentiation. In conclusion, miR-150 deficiency favored a more anti-inflammatory environment while miR-150 expression promoted pathogenic CD4 T cells subsets, potentially associated with metabolic mechanisms.