www.jrpms.eu JOURNAL OF RESEARCH AND PRACTICE Journal of Research and Practice on the Musculoskeletal System Review Article The role of miRNAs in ankylosing spondylitis: a narrative review George E. Diakos 1,2 and George I. Lambrou 1,2,3 1 Laboratory for Research of the Musculoskeletal System “Th. Garofalidis”, Medical School, National and Kapodistrian University of Athens, General Hospital of Athens KAT, Greece; 2 Postgraduate Program “Metabolic Bones Diseases”, National and Kapodistrian University of Athens, Medical School, Goudi, Athens, Greece; 3 First Department of Pediatrics, National and Kapodistrian University of Athens, Choremeio Research Laboratory, Goudi, Athens, Greece Introduction Ankylosing spondylitis (AS) is a chronic, autoimmune inflammatory disease of the axial skeleton which belongs to the broader group of seronegative spondyloarthropathies. Ankylosing spondylitis affects in prevalence 80% mainly young male adults who are in their third decade of their life. The early symptoms of the disease include morning stiffness combined with low back pain, which, besides the fact that it limits the patient’s activity, has a negative influence on the patient’s psychology. Currently, the most novel approach in AS treatment is based on medication using either anti- inflammatory or immunomodulatory drugs (anti-TNF biologic agents) 1 . microRNAs (miRNAs) consist a group of small, non- coding RNAs with approximately 20-25 nucleotides length that regulate the expression of multiple target-genes mainly at the post-transcriptional level 2 . It is known that miRNAs play critical roles in many processes such as differentiation, cell proliferation and apoptosis. Their crucial role is their function as posttranscriptional regulators of gene expression through interacting with numerous mRNAs, thus promoting their degradation or decreasing their translation. The last two decades it has become widely known that miRNAs, apart from being important for normal cellular development, are involved in the pathologies of autoimmune diseases, susceptibility to cancer, inflammation and heart diseases as a result of epigenetic modifications such as DNA methylation and nucleosome structural changes via histone modifications 3 . Abstract Ankylosing Spondylitis (AS) is a chronic, autoimmune inflammatory disease mainly affecting the axial skeleton and it might lead to functional and structural impairments and cause severe disability, thus, jeopardize quality of life. The last two decades, the potential role of miRNAs in the pathogenesis of AS has been under investigation in numerous studies. The aim of this article is to review the available literature on the involvement of miRNAs in AS pathogenesis. An electronic literature search was conducted by two independent researchers up to 2013. Titles and abstracts of papers were validated by the authors for further inclusion in the present work. At the end, full texts of the included articles were retrieved. SNPs of miRNAs lead to an overexpression of pro-inflammatory cytokines. Deregulated miRNAs enhance the production of pro-inflammatory cytokines, suppress autophagy in T peripheral cells of the blood. MiRNAs through a vast number of research have a potential correlation with AS pathogenesis. Because of their stable structure which easily could be extracted from cells of blood samples, the different expressed levels of miRNAs in peripheral blood and tissues from the joints could be used as potential biomarkers of the activity and the efficacy of the treatment in AS. Keywords: Ankylosing spondylitis, microRNAs, HLA-B27, SNPs The authors have no conflict of interest. Corresponding author: George I. Lambrou, First Department of Paediatrics, National and Kapodistrian University of Athens, Choremeio Research Laboratory, Hematology and Oncology Unit, Thivon & Levadeias 8, 11527, Goudi, Athens, Greece E-mail: glamprou@med.uoa.gr Edited by: Konstantinos Stathopoulos Accepted 15 March 2019 45 JRPMS | June 2019 | Vol. 3, No. 2 | 45-51 10.22540/JRPMS-03-045