[Zhuanggu Jianxi Decoction reduces synovial tissue inflammation in human knee osteoarthritis by regulating LXRs/NF-κB signaling pathway].

Abstract

This study aims to explore the mechanism of Zhuanggu Jianxi Decoction in reducing synovial tissue inflammation in human knee osteoarthritis(KOA) via the liver X receptors(LXRs)/nuclear factor(NF)-κB signaling pathway. The synovial tissue samples were collected from 5 healthy volunteers and 30 KOA synovitis patients and cultured in vitro. The samples from the heathy volunteers were set as the normal group, and those from KOA synovitis patients were randomized into synovitis, Zhuanggu Jianxi Decoction, LXRα inhibitor, and N-CoR inhibitor groups. The synovitis tissue samples of the 5 groups were treated with 10% blank serum, 10% blank serum, 10% drug-containing serum, 10% drug-containing serum+LXRα inhibitor, and 10% drug-containing serum+N-CoR inhibitor, respectively, for 7 days. After intervention, the synovial tissue samples of each group were collected and stained with hematoxylin-eosin for observation and scoring of the pathological changes. The expression intensity of the fibroblast-specific marker α-smooth musle actin(α-SMA) in the synovial tissue was observed by immunofluorescence staining. The levels of interleukin-1β(IL-1β), tumor necrosis factor-α(TNF-α), matrix metalloproteinase-3(MMP-3), and matrix metalloproteinase-13(MMP-13) in the supernatant of synovium homogenate were determined by ELISA. The mRNA and protein levels of LXRα, N-CoR, P50, and P65 in the synovial tissue were determined by RT-qPCR and Western blot, respectively. The results showed that compared with the normal group, the synovitis group showcased obvious synovial lining cell proliferation, inflammatory cell infiltration, synovial cell disarrangement, increased histopathological score(P<0.05), enhanced α-SMA fluorescence intensity and increased number of synovial fibroblasts(P<0.05), elevated levels of IL-1β, TNF-α, MMP-3, and MMP-13 in the synovial tissue(P<0.05), down-regulated mRNA and protein levels of LXRα and N-CoR, and up-regulated mRNA and protein levels of P50 and P65(P<0.05). Compared with the synovitis group, the Zhuanggu Jianxi Decoction group showed alleviated pathological changes, declined histopathological score of the synovial tissue(P<0.05), decreased α-SMA fluorescence intensity and number of synovial fibroblasts(P<0.05), lowered levels of IL-1β, TNF-α, MMP-3, and MMP-13(P<0.05), up-regulated mRNA and protein levels of LXRα and N-CoR, and down-regulated mRNA and protein levels of P50 and P65(P<0.05) in the synovial tissue. Compared with the Zhuanggu Jianxi Decoction group, the LXRα inhibitor group and N-CoR inhibitor group showed aggravated pathological changes, risen histopathological score of the synovial tissue(P<0.05), enhanced α-SMA fluorescence intensity and increased number of synovial fibroblasts(P<0.05), elevated levels of IL-1β, TNF-α, MMP-3, and MMP-13(P<0.05), down-regulated mRNA and protein levels of LXRα and N-CoR, and up-regulated mRNA and protein levels of P50 and P65(P<0.05). The results above indicated that Zhuanggu Jianxi Decoction could alleviate the synovial tissue inflammation in KOA patients by upregulating the mRNA and protein levels of LXRα and N-CoR in the LXRs/NF-κB pathway to downregulate the mRNA and protein levels of P50 and P65 and reduce the activity of the NF-κB pathway in the synovial tissue.