MiRNA-506 inhibits rheumatoid arthritis fibroblast-like synoviocytes proliferation and induces apoptosis by targetting TLR4.

Dan Li,Gaojian Hu,Gang Wang,Qingchen Zhou

doi:10.1042/bsr20182500

Abstract

Fibroblast-like synoviocytes (FLSs) play a crucial role in rheumatoid arthritis (RA) pathogenesis. While miRNA (miR)-506 has been implicated in the progression of multiple diseases, its role in RA remains to be explored. The present study evaluated the function of miR-506 in the regulation of RA-FLSs. FLSs were prepared from RA and healthy synovial tissues. The expression of miR-506 was measured by quantitative real time PCR (qRT-PCR). The effects of miR-506 on RA-FLSs proliferation and apoptosis were detected by cell counting Kit-8 and flow cytometry assays, respectively. The determination of TNF-α, IL-6, and IL-1β concentrations in RA-FLSs supernatant were done by ELISA. The levels of miR-506 were detected to be significantly lower in the synovial tissues and FLSs of RA than in the synovial tissues and FLSs of healthy controls. The miR-506 up-regulation in RA-FLSs significantly inhibited the proliferation and promoted cell cycle arrest at the G0/G1 phase. The overexpression of miR-506 induced apoptosis, along with an increase in activities of caspase-3 and -8. A target gene Toll-like receptor 4 (TLR4) under the direct regulation of miR-506 was identified through the luciferase assay, qRT-PCR and western blot analysis. Forced overexpression of TLR4 in the rescue experiments showed that TLR4 effectively reversed the effect on proliferation and apoptosis in miR-506-overexpressing RA-FLSs. Thus, miR-506 may be a potential target for RA prevention and therapy of RA.

Highlights

As a chronic and systemic inflammatory disease, rheumatoid arthritis (RA) is identified through symptoms such as hyperplasia of the synovium and extraarticular manifestations, which leads to cartilage damage, joint destruction, and deformation [1]
Flow cytometric analysis revealed that miR-506 overexpressed in RA-fibroblast-like synoviocytes (FLS) led to significant increase in the G1/G0-phase cells (79.5 +− 7.4% vs 62.6 +− 5.5%) and a decrease in the of S-phase cells (11.2 +− 1.1% vs 28.4 +− 1.6%), compared with that in RA-FLSs transfected with miR-NC (Figure 2C)
The results demonstrated that miR-506 overexpression significantly decreased Cyclin A1, Cyclin B1, and CyclinD2 protein expression in RA-FLSs

Summary

Introduction

As a chronic and systemic inflammatory disease, rheumatoid arthritis (RA) is identified through symptoms such as hyperplasia of the synovium and extraarticular manifestations, which leads to cartilage damage, joint destruction, and deformation [1]. RA-FLSs are similar to malignant cancer cells in some properties, such as resistance to apoptosis, uncontrolled growth, and high invasiveness [3]. To explore therapeutic strategies to treat RA, it is urgent need to find molecular mechanisms of the aggressive phenotype of RA-FLSs. In recent years, studies on small non-coding RNAs (miRNAs) have widely focussed on multiple diseases because of their involvement in the regulation of several physiological and pathological processes, including cell metabolism, proliferation, migration, invasion, and inflammation [4,5]. Abnormal miRNAs have been reported to be associated with the occurrence and development of RA, suggesting miRNAs as a diagnostic marker or therapy target of RA [6,7]

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Results

Conclusion