miR-31 regulates energy metabolism and is suppressed in Tcells from patients with Sjogren's syndrome

Systemic autoimmune diseases are characterized by the overexpression of type I IFN stimulated genes, and accumulating evidence indicate a role for type I IFNs in these diseases. However, the underlying mechanisms for this are still poorly understood. To explore the role of type I IFN regulated miRNAs in systemic autoimmune disease, we characterized cellular expression of miRNAs during both acute and chronic type I IFN responses. We identified a Tcell-specific reduction of miR-31-5p levels, both after intramuscular injection of IFN and in patients with Sjogren's syndrome (SjS). To interrogate the role of miR-31-51p in Tcells we transfected human CD4(+) Tcells with a miR-31-5p inhibitor and performed metabolic measurements. This identified an increase in basal levels of glucose metabolism after inhibition of miR-31-5p. Furthermore, treatment with IFN- also increased the basal levels of human CD4(+) T-cell metabolism. In all, our results suggest that reduced levels of miR-31-5p in Tcells of SjS patients support autoimmune T-cell responses during chronic type I IFN exposure.