Background Idiopathic inflammatory myopathies (IIMs) are chronic autoimmune disorders characterized by skeletal muscle weakness, inflammatory immune cells in muscle tissues and frequent presence of serum autoantibodies. Besides a genetic risk located within the MHC complex, also epigenetic regulations including changes in miRNAs expression profiles have been implicated recently in many autoimmune diseases. Extracellular miRNAs circulate in the bloodstream and such miRNAs are remarkably stable. It is hypothesized that circulating miRNA may be delivered to recipient cells and regulate translation of target genes.
Objectives The aim of this study was to analyze the differences in expression profiles of circulating extracellular miRNAs between patients and controls with possible selection of relevant candidate miRNA molecules involved in disease progression.
Methods Expression profile of 1,347 miRNA molecules was analyzed in 47 myositis patients and 16 healthy controls. Circulating miRNAs were prepared from serum using the Trizol® reagent. The expression of miRNAs was measured using the 44K high density microarray from Agilent Company.
Results The miRNA expression profiles clearly separate between healthy controls and patients with myositis. In total, 87 miRNA molecules were found to be differentially expressed in myositis patients. Analysis of the associated biological pathways regulated by the detected miRNAs revealed that 44 (50%) differentially expressed miRNAs are predicted to regulate immune response, 38 (43%) miRNAs are related to muscle activity and 40 (46%) miRNAs were predicted to be involved in cell death.
Conclusions A number of miRNAs differentially expressed in patients with IIMs were identified. These molecules are potentially involved in the etiopathogenesis of the disease since all are related to important immune mechanisms or muscle function.
Acknowledgements This study was supported by the Internal Grant Agency of the Ministry of Health in the Czech Republic [MZČR NT 12452-4], Institutional support of MHCR VZ (00023728) and The Charles University Grant agency (No.621812).
Disclosure of Interest None Declared