SAT0656 Circulating mir-99b-5p is a marker of inflammation and structural damage on mri in early rheumatoid arthritis

Background Expression of several miRNAs occurs in the plasma and synovial fluid of patients with established rheumatoid arthritis (RA). We found that microRNA-143–3 p (miR-143–3 p), miR-145–5 p, and miR-99b-5p expression was associated with greater erosion volume in early RA (ERA)EULAR 2018-abstract no 1980). Whether these miRNAs are associated with bone erosion and joint inflammation on magnetic resonance imaging (MRI) is unknown. Objectives To determine whether plasma cell-free circulating miRNAs are associated with (a) bone erosion and (b) inflammation severity on MRI in patients with ERA. Methods 66 ERA patients were recruited at presentation for this cross-sectional study. 60 of these 66 patients (90.9%) were treatment naive. MRI of the most severely affected wrist was performed in all patients. The degree of bone damage (i.e. erosions), bone inflammation (osteitis) and soft tissue inflammation (synovitis/tenosynovitis) was scored on MRI (a) semi-quantitatively using the Rheumatoid Arthritis MRI score (RAMRIS) for scoring the severity of erosions, bone marrow oedema, synovitis and tenosynovitis; and (b) quantitatively by measuring synovial and tenosynovial volume (mm3). The three most dysregulated miRNAs (miR-143–3 p, miR-145–5 p, and miR-99b-5p) identified in our previous ERA study were validated by TaqMan® qRT-PCR in all patients. Results Expression of miR-99b-5p was higher in ERA patients with erosions (1.28±0.61) on MRI than those without erosions (0.23±0.43, p Table 1 Univariate and multivariate analysis for factors associated with synovial volume and tenosynovitis volume at baseline in all ERA patients Conclusions Increased cell-free circulating miR-99b-5p is associated with increased synovial and tenosynovial volume as well as more severe bone erosion in ERA patients at presentation. Whether it may serve as a biomarker for monitoring the progression of synovitis and damage would need to be addressed in prospective studies. Acknowledgements This study was partly supported by the Health and Medical Research Fund (project no 10110071). Disclosure of Interest None declared