IFN-induced protein with tetratricopeptide repeats 2 (Ifit2) limits autoimmune inflammation by regulating myeloid cell activation and metabolic activity

Besides anti-viral functions, Type I IFN expresses potent anti-inflammatory properties and is being widely used to treat certain autoimmune conditions, such as multiple sclerosis (MS). In murine model of MS, experimental autoimmune encephalomyelitis (EAE), administration of IFNβ effectively attenuates the disease development. However, the precise mechanisms underlying the treatment remain elusive. In this study, we report that IFN-induced protein with tetratricopeptide repeats 2 (Ifit2), a type I and type III IFN-stimulated gene, plays a previously unrecognized immune regulatory role during autoimmune neuroinflammation. Mice deficient in Ifit2 display greater susceptibility to EAE and escalated immune cell infiltration in the central nervous system. Ifit2 deficiency is also associated with microglial activation and increased myeloid cell infiltration. Unexpectedly, myelin debris clearance and the subsequent remyelination is impaired in Ifit2 -/- CNS tissues. Clearing myelin debris is an important property of reparative M2 type myeloid cells to promote remyelination. Indeed, we observed that bone marrow derived macrophages, CNS infiltrating myeloid cells, and microglia from Ifit2 -/- mice express cytokine and metabolic genes associated with proinflammatory M1 type subsets. Taken together, our findings uncover a novel regulatory function of Ifit2 in autoimmune inflammation in part by modulating myeloid cell function and metabolic activity.