SAT0656 Circulating mir-99b-5p is a marker of inflammation and structural damage on mri in early rheumatoid arthritis
Authors: J. Yue, F. Xiao, J. Xu, P.C. Wong, E.K. Li, L.P. Tam, M. Li, L. Qin, J.F. Griffith, L.-S. Tam
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> 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)<sup>EULAR 2018</sup>-abstract no 1980). Whether these miRNAs are associated with bone erosion and joint inflammation on magnetic resonance imaging (MRI) is unknown. <h3>Objectives</h3> To determine whether plasma cell-free circulating miRNAs are associated with (a) bone erosion and (b) inflammation severity on MRI in patients with ERA. <h3>Methods</h3> 66 ERA patients were recruited at presentation for this cross-sectional study. 60 of these 66 patients (90.9%) were treatment naïve. 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 (mm<sup>3</sup>). 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<sup>®</sup> qRT-PCR in all patients. <h3>Results</h3> 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&lt;0.05). Subdivided according to mean RAMRIS synovitis score (5.69), miR-99b-5p expression was higher in ERA patients with relatively more synovitis (0.75±1.24) on MRI than those with relatively less synovitis (0.34±1.14, p&lt;0.05). Bone marrow oedema or tenosynovitis on MRI were not found to be associated with specific miRNA expression. Expression of miR-99b-5p did, however, correlate with synovial (r=0.443, p=0.018) and tenosynovial volume (r=0.423, p=0.025) on MRI. Linear regression analysis revealed miR-99b-5p expression to be independently associated with both increased synovial volume (B=15.65, 95% CI 3.42~27.89, p=0.014) and increased tenosynovial volume (B=7.39, 95% CI 0.41~14.38, p=0.039) (Table). Table 1 Univariate and multivariate analysis for factors associated with synovial volume and tenosynovitis volume at baseline in all ERA patients <h3>Conclusions</h3> 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. <h3>Acknowledgements</h3> This study was partly supported by the Health and Medical Research Fund (project no 10110071). <h3>Disclosure of Interest</h3> None declared