Iguratimod Inhibits the Aggressiveness of Rheumatoid Fibroblast-Like Synoviocytes.

Jin Lin,Bei Xu,Guanhua Xu,Ye Yu,Yini Ke,Weiqian Chen,Xuanwei Wang,Nancy Olsen,Lihuan Yue,Heng Cao,Liqin Xu,Danyi Xu,Chuanyin Sun

doi:10.1155/2019/6929286

Abstract

Objective Iguratimod, a novel disease-modifying anti-rheumatic drug for the treatment of rheumatoid arthritis, has been approved in China and Japan. Here, we aimed to find whether iguratimod can inhibit the aggressive behavior and promote apoptosis of rheumatoid fibroblast-like synoviocytes (RA-FLSs). Methods The proliferation of RA-FLSs was assessed by 5-ethynyl-2′-deoxyuridine test and Cell Counting Kit-8. Migration and invasion were determined by the wound test and a transwell assay. Apoptosis was tested by flow cytometry. The mRNA expression of matrix metalloproteinases (MMPs) and proinflammatory cytokines in RA-FLSs were measured by quantitative PCR and ELISA. To gain insight into the molecular signaling mechanisms, we determined the effect of iguratimod on the activation of mitogen-activated protein kinases (MAPK) signaling pathways by the cellular thermal shift assay (CETSA) and western blot. Results Iguratimod treatment significantly reduced the proliferation, migration, and invasive capacities of RA-FLSs in a dose-dependent manner in vitro. MMP-1, MMP-3, MMP-9, Interleukin-6 (IL-6), and monocyte chemoattractant protein-1 mRNA and protein levels were all decreased after treatment with iguratimod. Furthermore, tumor necrosis factor-alpha- (TNF-α-) induced expression of phosphorylated c-Jun N-terminal kinases (JNK) and P38 MAPK were inhibited by iguratimod. Additionally, iguratimod promoted the apoptosis of RA-FLSs. Most importantly, iguratimod was shown to directly interact with JNK and P38 protein by CETSA assay. Moreover, activating transcription factor 2 (ATF-2), a substrate of both JNK and P38, was suppressed by iguratimod. Conclusions Our findings suggested that the therapeutic effects of iguratimod on RA might be, in part, due to targeting the aggressive behavior and apoptosis of RA-FLSs.

Highlights

Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by joint involvement and systemic features which affects 0.28% of Chinese people [1]
To assess the influence of iguratimod on the proliferation of rheumatoid fibroblast-like synoviocytes (RA-fibroblast-like synoviocytes (FLSs)), RA-FLSs were stimulated by platelet-derived growth factor (PDGF) and incubated with different doses of iguratimod (0, 0.05, 0.5, 5, and 50 μg/ml), and the proliferation was assessed by Edu incorporation assay
We checked the role of iguratimod in the regulation of matrix metalloproteinases (MMPs) and inflammatory cytokine production by TNF-α stimulated RA-FLSs

Summary

Introduction

Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by joint involvement and systemic features which affects 0.28% of Chinese people [1]. Solid evidence supports that activated fibroblast-like synoviocytes (FLSs) are key effector cells in the pathophysiological course of RA [2]. RA-FLSs contribute to the production of inflammatory cytokines and matrix metalloproteinases (MMPs) that degrade the extracellular matrix. RA-FLSs display a highly proliferative and invasive behavior which is similar to tumor cells and is critical in the development of pannus by migrating and invading the cartilage and bone [3]. RA-FLSs have an aggressive capacity to invade the extracellular matrix, mediating inflammation and further exacerbating joint damage. RA-FLSs cultured in vitro still retain their aggressive phenotype in the absence of exogenous stimulation. The strongest evidence to support that RA-FLSs

Methods

Results

Discussion

Conclusion