INTRODUCTION: Increasing evidence indicates that microRNAs (miRNAs) play a 
critical role in the pathogenesis of inflammatory diseases. The aim of the study 
was to investigate the expression pattern and function of miRNAs in CD4+ T cells 
from patients with rheumatoid arthritis (RA).
METHODS: The expression profile of miRNAs in CD4+ T cells from synovial fluid 
(SF) and peripheral blood of 33 RA patients was determined by microarray assay 
and validated by qRT-PCR analysis. The correlation between altered expression of 
miRNAs and cytokine levels was determined by linear regression analysis. The 
role of miR-146a overexpression in regulating T cell apoptosis was evaluated by 
flow cytometry. A genome-wide gene expression analysis was further performed to 
identify miR-146a-regulated genes in T cells.
RESULTS: miRNA expression profile analysis revealed that miR-146a expression was 
significantly upregulated while miR-363 and miR-498 were downregulated in CD4+ T 
cells of RA patients. The level of miR-146a expression was positively correlated 
with levels of tumor necrosis factor-alpha (TNF-alpha), and in vitro studies 
showed TNF-alpha upregulated miR-146a expression in T cells. Moreover, miR-146a 
overexpression was found to suppress Jurkat T cell apoptosis. Finally, 
transcriptome analysis of miR-146a overexpression in T cells identified Fas 
associated factor 1 (FAF1) as a miR-146a-regulated gene, which was critically 
involved in modulating T cell apoptosis.
CONCLUSIONS: We have detected increased miR-146a in CD4+ T cells of RA patients 
and its close correlation with TNF-alpha levels. Our findings that miR-146a 
overexpression suppresses T cell apoptosis indicate a role of miR-146a in RA 
pathogenesis and provide potential novel therapeutic targets.