Anti-inflammatory and Pro-apoptotic Effects of 18beta-Glycyrrhetinic Acid In Vitro and In Vivo Models of Rheumatoid Arthritis

Abstract

18β-Glycyrrhetinic acid (18β-GA), an active component from Glycyrrhiza glabra L. root (licorice), has been demonstrated to be able to protect against inflammatory response and reduce methotrexate (MTX)-derived toxicity. This study was therefore designed to test the therapeutic possibility of 18β-GA on rheumatoid arthritis (RA) and to explore the underlying mechanism. LPS or TNF-α-induced inflammatory cell models and collagen-induced arthritis (CIA) animal models were applied in this study. Real-time quantitative PCR (RT-qPCR) was used to measure the mRNA levels of various cytokines and FOXO family members. The protein levels of molecules in the MAPK/NF-κB signaling pathway were analyzed using western blot. The cell proliferation assay and colony-forming assay were used to test the influence of 18β-GA on cell viability. The cell apoptosis assay and cell cycle assay were performed to detect the effect of 18β-GA on cell proliferative capacity by using flow cytometry. Hematoxylin and eosin (H&E) staining was performed to evaluate pathological changes after drug administration. The enzyme-linked immunosorbent assay (ELISA) was carried out for the detection of cytokines in serum. In vitro, we found that 18β-GA decreased the mRNA levels of IL-1β, IL-6, and COX-2 by inhibiting the MAPK/NF-κB signaling pathway in MH7A and RAW264.7 cell lines. Moreover, 18β-GA was able to suppress cell viability, trigger cell apoptosis, and G1 phase cell cycle arrest in our in vitro studies. 18β-GA dramatically enhanced the mRNA level of FOXO3 in both TNF-α- and LPS-induced inflammation models in vitro. Interestingly, after analyzing GEO datasets, we found that the FOXO3 gene was significantly decreased in the RA synovial tissue as compared to healthy donors in multiple microarray studies. In vivo, 18β-GA exhibited a promising therapeutic effect in a collagen-induced arthritis mouse model by alleviating joint pathological changes and declining serum levels of TNF-α, IL-1β, and IL-6. Finally, we observed that 18β-GA administration could mitigate liver damage caused by collagen or MTX. Collectively, the current study demonstrates for the first time that 18β-GA can inhibit inflammation and proliferation of synovial cells, and the underlying mechanism may be associated with its inhibition of MAPK/NF-κB signaling and promotion of FOXO3 signaling. Therefore, 18β-GA is expected to be a new drug candidate for RA therapy.

Inflammation-Driven Secretion Potential Is Upregulated in Osteoarthritic Fibroblast-Like Synoviocytes

“…To induce an immune response, cells were stimulated with two pro-inflammatory factors—lipopolysaccharide (LPS) and tumor necrosis factor alpha (TNFα). LPS, isolated from the outer membrane of Escherichia coli, leads to strong pro-inflammatory stimulation, so it is often used to model the general immune response [ 19 , 20 , 21 , 22 ]. TNFα occurs naturally during the development of inflammation in the human body and is produced mainly by immune cells; thus, it invokes a more physiological FLS inflammatory response [ 23 ].…”

Recent Advances Regarding the Molecular Mechanisms of Triterpenic Acids: A Review (Part II)

“…Similar mechanisms were reported by Zhou et al [ 166 ] in LPS-induced inflammation murine macrophage RAW 264.7 cells; the results showed that the anti-inflammatory activity of GA occurs through the inhibition of NF-κB expression and attenuation of its nuclear translocation. Furthermore, the inhibition of the MAPK/NF-κB signaling pathway by GA was once again demonstrated by an in vitro and in vivo study as the main mechanism of GA anti-inflammatory action in rheumatoid arthritis [ 167 ].…”

18β-Glycyrrhetinic Acid Ameliorates Neuroinflammation Linked Depressive Behavior Instigated by Chronic Unpredictable Mild Stress via Triggering BDNF/TrkB Signaling Pathway in Rats

“…Enoxolone, glycyrrhetin, 3β-hydroxy-11oxo-18β, 20β-olean12-en-29oic acid, uralenic acid, or sub-glycyrrhelinic acid are all names for 18β-glycyrrhetinic acid. 18β-glycyrrhetinic acid have been described to reduce airway inflammation [ 16 , 17 ], alpha-naphthylisothiocyanate-induced cholestasis [ 18 ], D-GalN/LPS-induced acute liver injury [ 19 ], cyclophosphamide-induced hepatotoxicity [ 20 ], prostate tumor [ 21 ], lung cancer [ 22 ], gastric tumor [ 23 ], streptozotocin-induced diabetes [ 24 ], pulmonary arterial hypertension [ 25 ], visceral leishmaniasis [ 26 ], rotavirus replication [ 27 ], bacterial load [ 28 , 29 ], antipsychotic-induced hyperprolactinemia [ 30 ], myocardial infarction [ 31 ], hyperoxia exposure effects in neonatal rats [ 32 ], rheumatoid arthritis [ 33 ], fructose-induced nephropathy [ 34 ], radiation-induced skin damage [ 35 ], cisplatin-induced oxidative intestinal damage [ 36 ].…”