Multiple Sclerosis (MS) is a heterogeneous disease in terms of disease course and treatment response. miRNAs are small non-coding RNA molecules usually dysregulated in numerous immunologic disorders including MS making them promising diagnostic and treatment response biomarker. This study aimed to identify miRNA signatures in serum and immune cells associated with therapeutic responses to teriflunomide.

Functional properties of two miRNAs that showed significant expression and correlation levels from discovery phase were studied in T-cells and monocytes of five healthy controls. Blood was collected after obtaining informed consent from healthy individual and Monocytes and T Cells were isolated. miR-21-5p and miR-34 were inhibited in T-cells and monocytes by miRCURY LNA miRNA power Inhibitors (Qiagen) and negative inhibitors as controls. After successful miRNA inhibition, cytokine secretion was studied as a measure of immune cell function in the modified T-cells and monocytes by FACs. All statistical analyses were performed using GraphPad Prism. Paired and unpaired non-parametric t tests were used to test for group differences. A p-value of less than 0.05 was considered statistically significant.

Successful inhibition of two miRNA candidates were observed in T-cell and Monocytes. Despite changes in IL-10 levels produced by hsa-miR21-5p inhibited CD4+ T cells (p=0.0831) and hsa-miR34a-5p inhibited T-cells (p=0.0599); the overall cytokine expression levels did not show any statistically significant changes induced by either hsa-miR21-5p and hsa-miR34a-5p miRNA inhibition in healthy control T-cells or monocytes.

Despite various studies describing immuno regulatory functions of miR-21 and miR-34 we did not see statistically significant functional changes due to inhibition of miR-21 and miR-34 in T-cells and monocytes profiles when compared to negative inhibition control. Potential reasons are that miR-21 and miR-34 functionality maybe independent of the immune cells we studied in healthy controls.