We found miR 146, 155 and 203 to be upregulated in rheumatoid arthritis synovial fibroblasts compared to osteoarthritis SF.

Based on the comprehensive analysis on the expression of 260 miRs we found miR 196a to be one of the most downregulated CB1 receptor antagonist miRs in RASF. Methods: MiRs from sera of patients with treatment na?ve early RA, with treated established RA and HC were isolated by phenol chloroform extraction. TaqMan Low Density Array was used to analyze the expression of 260 miRs in RASF and OASF. MiR 196a expression was further analyzed in additional RASF and OASF, RA and OA synovial tissues.

TaqMan RealTime PCR was used for quantification of miRs and functional experiments were performed following transfection with pre miR or miR 196a inhibitor. Results: In sera of sufferers with ERA, the expression of miR 146a was lower than Ribonucleic acid (RNA) in both HC and established RA sera while miR 155, 132, 203 and 223 showed no differences. In RASF, the expression of miR 196a is significantly lower than in OASF as well as in RA synovial tissues compared with OA. RASF transfection with pre miR/miR 196a inhibitor resulted in down/upregulation of predicted targets HOXC8 and ANXA1. Pre miR 196a suppressed cell proliferation and migration and induced apoptosis while miR 196a inhibitor enhanced both proliferation and migration and reduced apoptosis in RASF.

Conclusion: In contrast to established RA synovial fibroblasts where an increased expression of miR 146a abl was reported, our data showed that in early arthritis sera miR 146a is significantly downregulated and might characterize an early clinical stage in the disease. The low expression of miR 196a in both RA synovial tissue and in isolated SF contributes to the aggressive and invasive phenotype of RASF by modifying proliferation, migration and apoptosis with an impact on the pathogenesis of RA. Acknowledgements: This work was supported by IAR EPALINGES, FP7 Masterswitch, MH CR grant project No. 10065 4 and ARTICULUM fellowship. Immune cell derived microparticles are present at increased amounts in synovial fluid of rheumatoid arthritis individuals and can activate disease relevant signalling pathways in RA synovial fibroblasts.

Increased resistance to apoptosis is one with the main characteristics of aggressive phenotype of RASF and MPs have been shown to mediate both pro and anti apoptotic effects in different target cells. The aim of the present study was to investigate the functional role of immune cell derived MPs in modulating the apoptosis of SF in RA. Methods: MPs were isolated by the differential centrifugation from cell culture supernatants of U937 cells, untreated or stimulated with TNFa or poly for sixteen h. Flow cytometry was used to measure the counts and surface expression of CD4 and Fas on MP. Proinflammatory response of RASF induced by MPs was determined by measuring IL 6 protein levels by ELISA. Proliferation of OASF and RASF stimulated with MPs for 24 h was investigated by MTT Cell Proliferation Assay.

Functional role of MPs in spontaneous apoptosis and apoptosis mediated by Fas Ligand or TNFa Related Apoptosis Inducing Ligand was measured by flow cytometry using Annexin V/propidium iodide staining of RASF and OASF. Results: Poly induced MPs but not MPs from unstimulated U937 cells increased the production of IL 6 in RASF, type I interferon and plasmacytoid DCs are supposed to play important roles.