Faezeh Molaei - Department of genetics, Faculty of basic Sciences, Islamic Azad University, Zanjan Branch, Zanjan, Iran.
Afsaneh Nazari - Department of genetics, Faculty of basic Sciences, Islamic Azad University, Zanjan Branch, Zanjan, Iran.
Abdoreza Ghoreishi - Assistant professor of Neurology, Zanjan university of medical science.
Sanaz Mahmazi - Department of genetics, Faculty of basic Sciences, Islamic Azad University, Zanjan Branch, Zanjan, Iran.

Objective: Multiple sclerosis (MS) is a chronic inflammatory autoimmune demyelinating disease of the central nervous system with an unknown etiology. MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression by binding to complementary target mRNAs and either promoting their decay or inhibiting their translation. In the human immune system, miRNAs play an important role in modulating innate and adaptive immune responses. They regulate B and T cell development and differentiation, inaddition to pro-inflammatory responses mediated by Treg cells. Dysregulation of miRNAs involved in immune responses leads to autoimmunity. In this study, we investigated the amounts of circulating miR-320a and miR-17 in plasma samples from MS patients. Methods: We investigated miR-320a and miR-17 in plasma samples of 24 MS patients and 24 healthy subjects by quantitative real-time PCR.Results: miR-320a was down- regulated in all MS patients.miR-17 expression reduced in 60% of MS patients and overexpression of miR-17 observed in 40% of patients.Conclusion: Down-regulation of miR-320a induced the overexpression of pro-inflammatory cytokines. They could activate Th1 and Th17 that are important in the pathogenesis of MS. Ectopic expression of miR-17 imparted effector-T-cell-like characteristics to Treg cells via the de-repression of genes encoding effector cytokines. MiR-17 provides a potent layer of Treg cell control. A major challenge in multiple sclerosis (MS) is to develop biomarkers that could help in understanding individual MS patients miRNAs could be a potential biomarker for diagnosis and evaluation of MS.

Multiple Sclerosis, MicroRNAs, Autoimmunity, miR-17, miR-320a