Calycosin suppresses expression of pro-inflammatory cytokines via the activation of p62/Nrf2-linked heme oxygenase 1 in rheumatoid arthritis synovial fibroblasts

• Published in: Pharmacological research 2016-11, Vol.113 (Pt A), p.695-704
• Main Authors: Su, Xiaohui, Huang, Qingchun, Chen, Jianyu, Wang, Maojie, Pan, Hudan, Wang, Rui, Zhou, Hua, Zhou, Zhanqing, Liu, Juan, Yang, Fen, Li, Ting, Liu, Liang
• Format: Article
• Language: English
• Subjects: Anti-Inflammatory Agents - pharmacology; Antioxidants - physiology; Arthritis, Rheumatoid - drug therapy; Arthritis, Rheumatoid - metabolism; Calycosin; Cell Nucleus - drug effects; Cell Nucleus - metabolism; Cells, Cultured; Cytokines - metabolism; Cytoplasm - drug effects; Cytoplasm - metabolism; Fibroblasts - drug effects; Fibroblasts - metabolism; Gene Expression - drug effects; Heme Oxygenase-1 - metabolism; HO-1; Humans; Inflammation - drug therapy; Inflammation - metabolism; Isoflavones - pharmacology; NF-E2-Related Factor 2 - metabolism; Nrf2/ARE signaling; RASFs; Rheumatoid arthritis; RNA, Messenger - metabolism; RNA-Binding Proteins - metabolism
• ISSN: 1043-6618; 1096-1186
• DOI: 10.1016/j.phrs.2016.09.031

Calycosin (CAL) suppresses the mRNA expression of pro-inflammatory cytokines as well as COX-2 mRNA and protein expression in synovial fibroblasts derived from RA patients (RASFs), which is correlated with the up-regulation of HO-1 and NQO1 expression by facilitating Nrf2 nucleus translocation in RASF. Additionally, the results demonstrated that CAL significantly potentiates Nrf2/ARE activation by inducing p62 accumulation and Keap-1 degradation of RASFs. [Display omitted] The activation of synovial fibroblasts (SFs) and the subsequent production and expression of pro-inflammatory cytokines play a crucial role in the pathogenesis and progression of rheumatoid arthritis (RA). In the current study, rheumatoid arthritis synovial fibroblasts (RASFs) isolated from the joint of the patients were used to evaluate the suppressive effects of calycosin (CAL), a compound derived from the Chinese medicinal herb Radix Astragali, on the expression of pro-inflammatory cytokines in RASFs. The results demonstrated that increased mRNA expression levels of interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-25 (IL-25), interleukin-33(IL-33) were significantly inhibited by CAL. Furthermore, the compound obviously suppressed IL-6 and IL-33 secretion. The key inflammatory mediator, cyclooxygenase-2 (COX-2) was significantly attenuated by CAL. A mechanistic study showed that the antioxidant enzymes heme oxygenase-1 (HO-1), NAD(P)H dehydrogenase quinone 1(NQO1) and Nrf2 of RASFs were markedly activated by CAL. Furthermore, CAL potentiated the accumulation of sequestosome 1 (SQSTM1, p62) and the degradation of Kelch-like ECH-associated protein 1 (Keap1), thereby inducing Nrf2 translocation from the cytoplasm to the nucleus. Thus, CAL suppresses the expression of pro-inflammatory cytokines via p62/Nrf2-linked HO-1 induction in RASFs, which suggests that the compound should be further investigated as a candidate anti-inflammatory and anti-arthritic agent.