Abstract
BackgroundThe aim of this study was to investigate the regulative activity of (5R)-5-hydroxytriptolide (LLDT-8) on receptor activator of nuclear factor κ-B ligand (RANKL)/receptor activator of nuclear factor κ-B (RANK)/Osteoprotegerin (OPG) system in rheumatoid arthritis (RA) and its anti-osteoclastogenesis mechanism.MethodsThe expression of OPG, RANK and RANKL in CD3+ T leukomonocytes in both peripheral blood and synovial fluid of RA patients was evaluated by flow cytometry. The levels of interleukin (IL) 1β, IL-6, IL-10, IL-21 and IL-23 in the supernatants of peripheral blood mononuclear cells (PBMCs) and synovial fluid mononuclear cells (SFMCs) were assayed by ELISA. Tartaric acid phosphatase (TRAP) staining was used to identify the osteoclast-like cells derived from RAW264.7. Western blotting analysis was used to check the downstream molecules of RANKL.ResultsLLDT-8 increased the rate of OPG expression in CD3+ T leukomonocytes in peripheral blood as well as the ratio of OPG/RANKL in both peripheral blood and synovial fluid. LLDT-8 inhibited IL-1β, IL-6, IL-21 and IL-23 secretion, but promoted the secretion of IL-10 in the supernatants of PBMCs and SFMCs. In addition, LLDT-8 decreased the number of TRAP-positive cells derived from RAW264.7 in the presence of RANKL and M-CSF. Furthermore, LLDT-8 also inhibited the expression of p-IκB, a key regulator of RANKL signaling pathway.ConclusionsLLDT-8 exerts its anti-osteoclastogenesis effect in RA probably through regulating RANKL/RANK/OPG system and its downstream signaling pathway as well as cytokine productions.
Highlights
The aim of this study was to investigate the regulative activity of (5R)-5-hydroxytriptolide (LLDT-8) on receptor activator of nuclear factor κ-B ligand (RANKL)/receptor activator of nuclear factor κ-B (RANK)/Osteoprotegerin (OPG) system in rheumatoid arthritis (RA) and its anti-osteoclastogenesis mechanism
Our work suggested that LLDT-8 upregulated OPG expression in CD3+T leukomonocytes in peripheral blood as well as the ratio of OPG/Receptor activator of nuclear factor κ-B ligand (RANKL) in both peripheral blood and synovial fluid, and it inhibited inflammatory cytokine secretion in the supernatants of peripheral blood mononuclear cells (PBMCs) and synovial fluid mononuclear cells (SFMCs)
The results showed that LLDT-8 up-regulated OPG expression on CD3+ T leukomonocyte in peripheral blood at doses of 25 nM and 50 nM (Figure 1B), and increased the ratio of OPG/RANKL at the dose of 50 nM (Figure 1C)
Summary
The aim of this study was to investigate the regulative activity of (5R)-5-hydroxytriptolide (LLDT-8) on receptor activator of nuclear factor κ-B ligand (RANKL)/receptor activator of nuclear factor κ-B (RANK)/Osteoprotegerin (OPG) system in rheumatoid arthritis (RA) and its anti-osteoclastogenesis mechanism. Methods: The expression of OPG, RANK and RANKL in CD3+ T leukomonocytes in both peripheral blood and synovial fluid of RA patients was evaluated by flow cytometry. Tripterygium Wil’fordii Hook.F, belonging to plants of the genus Euonymus Corey Gong, is a traditional Chinese medicine, the extracts of which have a variety of pharmacological effects, such as anti-inflammatory, antibiosis, antifertility, immunosuppression, anti tumor and etc. They are widely used in the treatment of rheumatic disease, autoimmune disease, organ transplantation, nephroma, asthma and tumor [2].
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