Relationship of epigenetic variability of miR-124 to extracellular matrix remodelling and age-related MMP-3 expression in rheumatoid arthritis

The aim of study was to examine relation among miR-124 and serum levels of selected cytokines and chemokines, MMP-3, production of auto-antibodies, and factors describing clinical activity (DAS28) and radiographic progression in rheumatoid arthritis (RA). A total of 80 RA patients according to the ACR classification criteria, and 32 control subjects were recruited into study. The measurements of miR-124 and U-6 expression, CRP anti-CCP, rheumatoid factors (RFs), radiographs of both hands with calculation of total sharp score (TSS), DAS28 and cytokines, chemokines and MMP levels in serum were obtained from all RA patients. miR-124 was down-regulated in RA patients compared to controls (7-fold decrease). The miR-124 expression correlated to MMP-3 levels (p < 0.001), which were in multivariate analysis associated to age of RA onset. Higher levels were detected in younger subjects. No relation of miR-124 expression to measures of RA activity (DAS28 score; TSS), auto-antibodies (anti-CCP, RR, RF IgG, RF IgA, RF IgM), acute inflammatory markers (CRP, IL-6), and other cytokine and chemokines (IL-13, IL-15, IL-8, TNF-alpha, MCP-1, RANTES) was observed. In conclusion, we present a down-regulation of miR-124 in RA patients and its correlation to MMP-3 levels, which associated to age of RA onset.