MicroRNA-92a Drives Th1 Responses in the Experimental Autoimmune Encephalomyelitis

Dysregulation of microRNAs (miRNAs) has been linked to the progress of a number of autoimmune diseases including multiple sclerosis (MS), and its animal model, experimental autoimmune encephalomyelitis (EAE). IFN-γ-producing Th1 cells are major players in MS/EAE pathogenesis. It is known that differentiation of T cells towards the Th1 phenotype is influenced by various factors including miRNAs. The miR-92a shows substantial upregulation in MS; however, little is known about its role in the development of autoimmune and inflammatory responses. Herein, we investigated the role of miR-92a in the pathogenesis of MS, focusing on its potential effects on differentiation of Th1 cells. The expression levels of miR-92a were assessed in the spinal cord tissues and splenocytes from mice with EAE using real-time RT-PCR. Next, using transfection with miR-92a mimic sequences, the potential involvement of miR-92a in Th1 polarization was investigated by flow cytometric analysis. Moreover, the expression levels of miR-92a targets were explored in spinal cord tissues of EAE mice. miR-92a expression was enhanced in mouse spinal cord samples at the peak of EAE disease. Overexpression of miR-92a in splenocytes led to increased differentiation of Th1 cells compared with cells transfected with negative control sequences. Enhanced miR-92a expression was accompanied by reduced expression TSC1 or DUSP10, predicted miR-92a targets, in EAE spinal cords. Our data point to a potential role for miR-92a in neuroinflammatory responses in EAE. Our results indicate that miR-92a might affect Th1 differentiation, likely due to downregulation of TSC1 and DUSP10.