Background/Purpose:

Enthesitis related arthritis (ERA) is the most common category of JIA in India. MicroRNA dysregulation has been associated with arthritis and autoimmune diseases. In rheumatoid arthritis (RA) over-expression of miR-146a, miR-155 miR-132 and miR-16 has been found in PBMC. Data on miRNA profiling in serum of patients with systemic lupus erythematosus (SLE) shows over-expression of miR-142-3p and miR-181a whereas miR-106a, miR-17, miR-20a, miR-203, and miR-92a were found to be down-regulated. No such data is available in case of ERA. Thus we studied global miRNA expression profile of ERA patients using peripheral blood mononuclear cells and synovial fluid mononuclear cells (PBMCs and SFMCs). PBMCs from healthy subjects were used as controls.

Methods:

Total RNA was isolated from PBMCs and SFMCs of ERA patients (n= 8 each) and PBMCs of healthy controls (n= 8). miRNA profiling was done using Agilent Human miRNA Microarray G4470A chips. Log₂-transformed expression values of miRNAs were analysed using RMA algorithms. Differential expression analyses were done using Empirical Bayes moderated t statistics. Highly dysregulated miRNAs were validated by quantitative RT-PCR by comparing fold change (in relation to Let-7a as internal control) in 13 PBMCs with 11 SFMCs from ERA patients. Targets of dysregulated miRNAs were predicted by computational analysis using databases like DIANA LAB, miR Base, Target Scan, etc.

Results:

The miRNAs profiling of ERA PBMCs were not significantly different from healthy controls. While comparing ERA SFMCs 38 miRNAs were down-regulated and 52 were up-regulated at cut offs of 0.05 as compared to ERA PBMCs. Among them miR-34a, miR-210, miR-29b, miR-155, miR-21, miR-27a, miR-132, miR-140-5p, miR-15a, and miR-660 were upregulated and miR-146a, miR-126, miR-130a, miR-150, miR-26a, miR-23b, miR-199a, miR-451, miR-151 and miR-221 were down-regulated in SFMCs. Among these 5 down-regulated and 5 up-regulated miRNAs were validated by RT-PCR using 11 ERA SFMCs and 13 ERA PBMCs.The comparison of fold change between ERA SFMCs and ERA PBMCs (p value) of dysregulated miRNAs showed:  miR-34a (p=0.035), miR-210 (p=0.424), miR-29b (p=0.865), miR-155 (p=0.072), miR-21 (p=0.047), miR-146a (p=0.006), miR-126 (p<0.001), miR-130a (p<0.001), miR-150 (p=0.150) and miR-26a (p=0.011). The targets of dysregulated miRNAs formed a part of multiple immune pathways like MAPK signaling pathways, TLR signaling pathways, T cell receptor signaling pathways, mTOR signaling pathways, Wnt signaling pathways, etc.

Conclusion:

ERA SFMC has a distinct miRNA gene expression profile compared to ERA PBMCs. miR-34a and miR-21 are significantly up-regulated whereas miR-146a, miR-126, miR-130a and miR-26a are significantly down-regulated in ERA SFMCs and all these dysregulated miRNAs are involved in multiple immune pathways. This difference in SFMC may be related to difference in composition of cells, cytokine mileu that modulates miRNA expression as well as differential expression of miRNAs as they have feedback regulatory function.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/global-mirna-expression-profiling-in-peripheral-blood-and-synovial-fluid-mononuclear-cells-of-patients-with-enthesitis-related-arthritis/