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Background: Small non-coding RNA molecules (miRs) are involved in immune cell maturation and function and might influence immunopathological processes of systemic lupus erythematosus (SLE) pathogenesis., Methods and Results: This paper presents the results of a literature search for publications dealing with the relationship between miRs and pathological factors related to SLE such as genetic background, immune dysregulation and gender-associated differences participating in SLE development. In SLE, distinct miRs are differentially expressed in SLE cells of innate and adaptive immunity. The miR-146a and miR-155 genes, among others, interfere with intracellular signalling pathways downstream of toll-like receptors 7 and 9 (TLR- 7, TLR-9) and influences interferon (IFN)-type I synthesis in plasmacytoid dendritic cells. In T and B cells, miR-126, miR-21, miR-146a, miR-155, miR-1246 and others might influence gene expression by epigenetic modifications, support abnormal cytosine release, differentiation of cell subsets, B cell hyperactivity and autoantibody production. Besides, estrogen might up- and downregulate immunologically active miRs, which are potential mediators of hormonal influences in SLE development. Moreover, SLE genetic basis included some polymorphisms of the miR-146a gene, which varies across populations., Conclusion: Distinct miRs are differentially expressed in both SLE mice models and human patients and promote autoimmune features of immune processes. MiRs are important molecules modulating susceptibility to SLE as well as its onset, clinical diversity and progression.

Objectives: The aim of this study was a large scale investigation of myositis-associated circulating miRNA molecules and also determination of expression of these candidate molecules in relation to clinical activity of myositis., Methods: RNA, containing also miRNAs, was isolated from sera of 28 patients suffering from idiopathic inflammatory myopathies (IIM) and 16 healthy controls. Expression of miRNAs was determined using a miRNA microarray method. Statistical analysis of miRNA expression was carried out using Arraystar software., Results: Our results showed 23 significantly differentially expressed miRNAs. Six miRNAs were differentially expressed in IIM compared to healthy controls. In dermatomyositis (DM) we found 3 and in polymyositis (PM) 6 differentially expressed miRNAs compared to controls. Three miRNAs were up-regulated in patients with highly active disease compared to patients with low disease activity. Furthermore, we found 26 significantly differentially expressed miRNAs in SLE patients compared to IIM, DM and PM patients., Conclusions: This is the first study that comprehensively describes expression levels of circulating miRNAs in serum of patients suffering from IIM. It can be expected that some of these deregulated miRNA molecules are involved in aetiology of IIM and may potentially serve as molecular markers for IIM development or for monitoring of disease activity.