AB0020 The Role of Epigenetics in Determining the Clinical Response To Methotrexate for the Treatment of Rheumatoid Arthritis

BackgroundRheumatoid Arthritis (RA) is a chronic inflammatory autoimmune disease, affecting around 1% of the population, causing significant ill health, disability and increased mortality. The precise etiology of RA is not known, but both genetic and environmental influences play a role. Methotrexate (MTX) is the most commonly used disease modifying anti-rheumatic drug in the management of RA, however its mechanism of action has not been extensively studied.ObjectivesThe aim of this study is to determine the functional effect of MTX in the RA joint.MethodsPrimary RA synovial fibroblasts (RASFC) were isolated from synovial biopsies obtained from patients undergoing arthroscopic examination. RASFC were cultured in the presence or absence of MTX (10-100uM) and cell migration, invasion, cytoskeletal rearrangement, viability, proliferation and pro-inflammatory cytokine expression were assessed by wound repair assays, transwell matrigel™ invasion chambers, F-actin immunofluorescent staining, MTT/ Crystal violet cell growth assay and ELISA respectively. In parallel, CD14+monocytes were isolated from peripheral blood mononuclear cells from RA patients both pre- and 12 weeks post-MTX therapy (n=5) and global methylation was assessed by a 5-methylcytosine DNA ELISA kit.ResultsMTX (10-100uM) inhibited RASFC repopulation of the wound margins in comparison to vehicle control where migration across the wound was clearly evident (p