Background: Rheumatoid arthritis (RA) is a chronic progressive autoimmune disease. The traditional Chinese herbal formula Er-miao-san (EMS) has been used to treat RA demonstrating significant clinical efficacy; however, the mechanism of action remains unclear. In view of the important role of α7 nicotinic acetylcholine receptor (α7nAChR) in the cholinergic anti-inflammatory pathway (CAP)for the regulation of inflammation and cytokines. Indeed, we previously found a correlation between CHRNA7 (encoding α7nAChR) expression and EMS, we hypothesized that it may play a role in the anti-inflammatory effects of EMS.
Objectives: The mechanism of EMS in the treatment of RA based on CHRNA7 involved in the regulation of CAP.
Methods: We established a CIA model with female Wistar, and the effects of intragastric administration of EMS on the expression of CHRNA7, arthritis score, inflammatory, and articular cartilage changes, was examined in the joints. The serum levels of TNF-α, IL-6, and IL-1β were determined using commercial ELISA kit.
Results: The CIA model was successfully established. Macroscopic changes of arthritis, such as redness and swelling, were clearly observed in the CIA rats, but were attenuated by the treatment of EMS. The mean arthritis score was markedly lower in the EMS-treated group (EG, P < 0.05). The serum level of TNF-α was significantly lower in EG compared with CIA group (P < 0.05). The same results were found in the serum levels of IL-6 and IL-1β. Synovial edema and extensive infiltration of inflammatory cells occurred in the CIA rats, but were repaired by the treatment of EMS. Cartilage tissue was thinning, dissolution and disappearance, as well as extensive inflammatory cell infiltration with plasma cells and lymphocytes, was observed in the articular cartilage of the ankles in CIA group. In contrast, EMS treatment prevented cartilage degeneration and markedly reduced inflammation. Immunohistochemistry (IHC) analysis showed positive signals of CHRNA7 was expressed on fibroblast-like synoviocytes, macrophages, and endothelial cells in the joints. Effect of EMS on the expression of CHRNA7 protein in the joint by Western blot (WB) analysis. IHC and WB relative optical density values of CHRNA7 was significantly higher in EG compared with CIA group (P < 0.05).
Conclusion: EMS can significantly alleviate the symptoms of arthritis in CIA rats by regulating the expression of CHRNA7 in CAP. It provides a scientific research foundation for the further development of EMS and explores more ways to treat RA.
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Disclosure of Interests: None declared
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