Session Title: Rheumatoid Arthritis: Human Etiology and Pathogenesis II
Session Type: Abstract Submissions (ACR)
Whereas molecular mechanisms mediating treatment responses to biologic DMARDS in Rheumatoid Arthritis (RA) are emerging, those pathways that subserve treatment resistance are poorly explored. MicroRNAs (miRs) post-transcriptionally regulate different elements of given signal pathways, and as such capture a ‘snapshot’ of the cell state. We previously assembled a cross-sectional cohort of RA patients with distinct therapy response characteristics including rapid sustained response to conventional (c)DMARD, cDMARD failure and recurrent DMARD (conventional and biologic) resistance. We sought herein to identify dysregulated miR species in therapy resistant patients.
Peripheral blood (PB) CD14+ monocytes were isolated from three groups of RA patients meeting ACR 2010 criteria: good responders to cDMARD (n=20), failing cDMARDs (n=17) or resistant to biologic agents (n=30). Comparative samples from age-matched healthy volunteers (n=23) were obtained. Candidate miR profiling (based on cytokine receptor targeting miRs) was performed using real-time quantitative PCR. Potential miR-27a/b targets were identified using TargetScan with transcriptional pathway analysis data from PB RA CD14+ cells and functionally validated by Luciferase reporter assay. THP-1 cells were transfected with control or miRNA-27a/b antagomiR and membrane IL-6R expression evaluated by flow cytometry.
We identified that miR-27b was significantly down-regulated in sorted CD14+ monocytes obtained from cDMARD failure and biologic treatment resistant, compared to cells from patients responding well to cDMARD and HV (p<0.03). Elevated levels of serum IL-6 were evident in both therapy resistant groups (p<0.001). TargetScan identified several potential miR-27 targets in the IL-6R signal pathway, including soluble and membrane bound variants of IL-6 receptor (IL-6R). Both IL-6R isoforms were confirmed as direct targets of miR-27a/b by luciferase reporter assay. Inhibition of endogenous miR-27a/b via antagomiR in THP-1 cells (myeloid line) significantly increased surface levels of Il-6R (p=0.05, n=4), demonstrating that miR-27a/b actively regulates membrane IL-6R expression.
Together our data uncover a previously unrecognized miR-27:IL-6R pathway interaction that operates particularly in monocytes of RA patients with active or treatment refractory disease. Our study thereby identifies a potential new biomarker and functional mechanism associated with disease chronicity.
A. A. Rainey,
D. S. Gilchrist,
I. B. McInnes,
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/mir-27b-as-biomarker-and-regulator-of-il-6r-pathway-in-resistant-rheumatoid-arthritis-monocyte/