Anti-Rheumatic Properties of Gentiopicroside Are Associated With Suppression of ROS-NF-κB-NLRP3 Axis in Fibroblast-Like Synoviocytes and NF-κB Pathway in Adjuvant-Induced Arthritis.

Meiling Wang,Yuan Du,Yanfang Wang,Wenyu Xin,Yongying Lu,Yanfei Hao,Leiming Zhang,Yanan Huang,Xinlin Wang,Hongyan Li,Fenghua Fu

doi:10.3389/fphar.2020.00515

Abstract

Rheumatoid arthritis (RA) is among the most prevalent forms of autoimmunity. Gentiopicroside (Gent) is an iridoid glucoside derived from the Gentiana Macrophylla Pall which is used in traditional Chinese medicine to treat RA. The present study was designed to explore the ability of Gent to combat RA and to explore the molecular basis for such anti-RA activity both in vitro using tumor necrosis factor alpha (TNF-α)-stimulated human RA fibroblast-like synoviocytes (RA-FLS) and in vivo using a rat adjuvant-induced arthritis (AIA) model. We found that Gent was able to significantly reduce the swelling of joints and arthritic index scores, with corresponding reductions in synovial inflammatory cell infiltration, synovial hyperplasia, and bone erosion in treated AIA rats. Importantly, Gent 200 mg/kg reduced thymus index in AIA rats, but had no effect on spleen index and body weight, it revealed that Gent was relatively safe at the dose we chose. We further found that Gent was able to suppress the TNF-α-induced proliferation and migration of RA-FLS cells. This suppression was attributed to the ability of Gent to block NOD-like receptor protein 3 (NLRP3), apoptosis-associated speck-like protein containing a CARD (ASC), and caspase-1, thereby disrupting the activation of the NLRP3 inflammasome. Consistent with such suppression, Gent led to a significant decrease in IL-1β secretion by treated cells. Furthermore, this reduction in NLRP3 inflammasome activation was also associated with decreases in the activation of nuclear factor (NF-κB), the production of reactive oxygen species (ROS), and the expression of inflammatory IL-6. Together these findings indicate that Gent can suppress the ROS-NF-κB-NLRP3 axis to alleviate RA symptoms.Chemical compounds studied in this articleGentiopicroside (PubChem CID: 88708).

Highlights

Rheumatoid arthritis (RA) is a chronic and highly debilitating form of systemic autoimmunity associated with the progressive destruction of bone and cartilage, systemic synovitis, synovial lining thickening, and inflammatory cell infiltration of the subintimal layer (Schett and Gravallese, 2012)
We found that a 48-h treatment with tumor necrosis factor alpha (TNF-a) was sufficient to increase the expression of NOD-like receptor protein 3 (NLRP3), associated speck-like protein containing (ASC), and caspase-1 at the protein level as measured via immunofluorescence microscopy or western blotting
In vivo we found that Gent treatment was able to reduce joint inflammatory cell infiltration, pannus formation, and bone destruction in adjuvant-induced arthritis (AIA) model animals, confirming that Gent is capable of suppressing pathogenic inflammation in the context of RA progression

Summary

Introduction

Rheumatoid arthritis (RA) is a chronic and highly debilitating form of systemic autoimmunity associated with the progressive destruction of bone and cartilage, systemic synovitis, synovial lining thickening, and inflammatory cell infiltration of the subintimal layer (Schett and Gravallese, 2012). The formation of an inflamed and hyperplasic synovial lining referred to as a pannus is considered to be a pathological hallmark of RA. This pannus is composed of macrophages, neutrophils, and other inflammatory cell types that can secrete TNF-a. Fibroblast-like synoviocytes (FLS) within the pannus are responsive to paracrine TNF-a production, resulting in an inflammatory cell-TNF-a-FLS axis that can drive disease progression (Firestein, 2003; Noss and Brenner, 2008). Nuclear factor-kappa B (NF-kB) is well established as a key inflammatory regulator of RA This transcription factor is highly activated in RA, resulting in substantial pathogenic production of IL-6 and TNF-a (Zhou et al, 2014).

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