Session Information
Session Type: Abstract Submissions (ACR)
Background/Purpose: MicroRNAs (miRs) are a novel class of post-transcriptional regulators. miR-155 was shown to be a regulator of B cell biology in haematological diseases as well as in myeloid cells in Rheumatoid Arthritis (RA). The regulation of the transcription factor PU.1 by miR-155 is required for the production of high-affinity IgG1 antibodies. The aim of this study was to investigate the expression of miR-155 in B cells of RA patients and its association with synovial inflammation.
Methods: 31 RA patients underwent ultrasound guided synovial tissue (ST) biopsy. ST samples were categorized through Hematoxiline and Eosine staining as diffuse or aggregate pattern. B cells from peripheral blood (PB) and matched synovial fluid (SF) of RA patients (n=19) and PB of healthy controls (HC) (n=10) were isolated by CD19+ microbeads (Mylteni). B-cell subsets were determined by Flow-Cytometry using IgD/CD27 classification and ZAP70 intracellular expression was assessed. IL-6 and BAFF levels in PB and SF were measured by ELISA. miR-155 expression was determined by qPCR on B cells from PB and SF and on ST of osteoarthritis (OA) (n=3), diffuse RA (n=5) and aggregate RA (n=5) patients. Finally, B cells from PB of HC (n=5) were isolated by CD19+ microbeads and cultured in RPMI with or without IL-6 (30 ng/ml), BAFF (20 ng/ml), IL-6+BAFF. Cells were collected after 24h, 48h and 72h to assess miR-155 and PU.1 expression by qPCR.
Results: 14(45,2%) RA patients showed an aggregate synovial pattern in ST. RA patients with an aggregate synovial pattern were more likely anti-CCP positive compared to RA patients with diffuse pattern (p=0.05). Moreover, anti-CCP plasma levels directly correlates with the synovial aggregate grade (r=0.38; p=0.01). IL-6 and BAFF levels were higher in SF than in PB of RA patients regardless to the synovial pattern (p=0.001 for both). CD19+/IgD-CD27- and CD19+/ZAP70+ cells were over-represented in PB of RA patients with an aggregate pattern (p=0.05 and p=0.04) compared to RA patients with a diffuse pattern. Moreover, anti-CCP+ RA patients showed higher percentages of CD19+/IgD-CD27- and CD19+/ZAP70+ in the PB (p=0.01 for both) compared to anti-CCP- RA patients. miR-155 was over-expressed in PB B-cells compared to HC (p=0.0002). miR-155 was over-expressed in SF B-cells compared to matched PB B-cells (p=0.05) in RA patients. Moreover, anti-CCP+ RA showed higher miR-155 expression in PB B-cells compared to anti-CCP- RA patients (p=0.02) and HC (p=0.001). miR-155 was over-expressed in ST of aggregate RA compared to diffuse RA (p=0.03) and OA (p=0.03) patients respectively. Finally, IL-6 and BAFF in vitro stimulation of healthy B-cells induced an overexpression of miR-155 after 72h of incubation (p=0.04 and p=0.03). Consistently PU.1 was down-regulated after in vitro stimulation (p=0.01 and p=0.03).
Conclusion: This study indicates that miR-155 is over-expressed in B-cells of RA patients and is associated to anti-CCP positivity and to an aggregate synovial pattern. IL-6 and BAFF, that are over-expressed in the SF environment, induce in vitro an over-expression of miR-155 in B-cells. Thus, miR-155 may represent a key regulator of B-cells in RA patients with an activated memory phenotype.
Disclosure:
S. Alivernini,
None;
B. Tolusso,
None;
S. Canestri,
None;
L. Petricca,
None;
C. Di Mario,
None;
E. Gremese,
None;
G. Ferraccioli,
None.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/microrna-155-as-an-epigenetic-regulator-of-b-cell-activation-in-rheumatoid-arthritis-in-vivo-and-in-vitro-evidences/