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Open Access Research article

MicroRNA-26a negatively regulates toll-like receptor 3 expression of rat macrophages and ameliorates pristane induced arthritis in rats

Congshan Jiang12, Wenhua Zhu12, Jing Xu12, Bo Wang12, Weikun Hou3, Rui Zhang3, Nannan Zhong12, Qilan Ning12, Yan Han12, Hongchuan Yu4, Jian Sun12, Liesu Meng12* and Shemin Lu125*

Author Affiliations

1 Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, West Yanta Road No.76, Xi’an, Shaanxi 710061, PR China

2 Key Laboratory of Environment and Genes Related to Diseases, (Xi’an Jiaotong University), Ministry of Education, Xi’an, Shaanxi, PR China

3 Department of Bone and Joint Diseases, Hong Hui Hospital, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi 710054, PR China

4 Department of Respiratory Medicine, Xi’an Children Hospital, Xi’an, Shaanxi 710003, China

5 Department of Epidemiology and Health Statistics, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, Shaanxi, China

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Arthritis Research & Therapy 2014, 16:R9  doi:10.1186/ar4435

Published: 14 January 2014

Abstract

Introduction

Abnormal toll-like receptor (TLR)3 signaling plays an indispensable role in pathogenesis of both experimental and human rheumatoid arthritis, and microRNAs (miRNAs) might orchestrate this signaling pathway. This study was performed to determine the relationship between miR-26a and TLR3 in rat macrophages and to observe effects of miR-26a mimic on pristane induced arthritis (PIA) in rats.

Methods

Dual luciferase reporter assay was used to validate the direct interaction between miR-26a (a candidate miRNA to target tlr3 mRNA) and tlr3 3′UTR. MiR-26a regulation on TLR3 gene expression was determined using RT-qPCR and Western blotting after miR-26a mimics and inhibitors were transfected into rat macrophage line NR8383 cells. Poly I:C (TLR3 ligand) was used to trigger TLR3 activation, and mRNA expression of its downstream cytokines interferon (ifn)-β and tumor necrosis factor (tnf)-α was accordingly detected to determine the regulation of TLR3 signaling. Expressions of TLR3 and miR-26a were detected during rat bone marrow derived macrophage (BMDM) induction, in pristane stimulated NR8383 cells and spleens from methotrexate (MTX) treated PIA rats. A miR-26a mimic was administrated intraperitoneally to PIA rats, and arthritis severity was evaluated by macroscopic or microscopic observations.

Results

Direct target relationship between miR-26a and tlr3 mRNA in rats was confirmed. Modifications of miR-26a function by transfection of miR-26a mimics and inhibitors exhibited corresponding repression and augmentation of TLR3 and its signaling downstream cytokine expressions in NR8383 cells. The alteration of miR-26a expression was negatively related with TLR3 expression during BMDM induction, in pristane-primed NR8383 cells and PIA rat spleens. Moreover, both abnormal expressions were rescued in MTX treated arthritis rat spleens. The miR-26a mimic treatment displayed the depression of TLR3 expression and ameliorated the disease severity in the rats with pristane induced arthritis.

Conclusions

MiR-26a negatively regulates TLR3 signaling via targeting of TLR3 itself in rat macrophages, and this finding provides a novel insight into abnormal TLR3 overexpression during experimental arthritis.