Background Iguratimod (T‐614), exerting a powerful anti‐inflammatory ability, has therapeutic efficacy in multiple autoimmune diseases. However, the effect of T‐614 on systemic sclerosis (SSc) is unclear. Here, we investigate the effect and molecular mechanism of T‐614 in experimental SSc models. Methods In vitro, cultured dermal fibroblasts from four SSc patients were subjected to different doses of T‐614 in the presence or absence of TGF‐β1 stimulation. Cell proliferation, apoptosis and migration were determined by CCK‐8, flow cytometry and transwell assay, respectively. Fibrosis markers and smad signalling pathway‐related proteins were detected by immunoblotting and immunofluorescence. In vivo, a bleomycin‐induced SSc mouse model was used to evaluate the effect of T‐614 on skin fibrosis. Pathological changes in skin tissues were evaluated by HE, Masson staining and immunohistochemistry. Results In the study, we found T‐614 inhibited TGF‐β1‐induced cell proliferation, migration and promoted apoptosis in a dose‐dependent manner (all p < 0.01). T‐614 partially reversed TGF‐β1‐induced upregulation of fibrosis markers and phosphorylation of smad2 and smad3 and blocked p‐Smad3 nuclear translocation (all p < 0.05), suggesting T‐614 may inhibit dermal fibroblasts activation by regulating TGF‐β1/smad pathway. In vivo experiments, T‐614 alleviated skin thickness in bleomycin‐induced SSc mice (all p < 0.05). The expression of fibrosis markers and the infiltration of macrophages in skin tissue were significantly decreased after T‐614 treatment (all p < 0.05). Conclusion Our preliminary data indicated T‐614 inhibited dermal fibroblasts activation and skin fibrosis at least partly by regulating TGF‐β1/smad pathway in experimental SSc models and may be a promising therapeutic agent for SSc.

IntroductionResveratrol, a polyphenol extracted from many plant species, has emerged as a promising pro-apoptotic agent in various cancer cells. However, the role of resveratrol in cell proliferation and apoptosis of fibroblast-like synoviocytes in rheumatoid arthritis (RA-FLS) is not fully understood. The study was aimed at elucidating the role of resveratrol in cell proliferation and apoptosis of RA-FLS and the underlying molecular mechanism.Material and methodsCultured RA-FLSs were subjected to tumour necrosis factor  (TNF-). The cell proliferation was measured by Cell Counting Kit-8 assay. Cell apoptosis and cell cycle of RA-FLSs were determined by flow cytometry. The levels of apoptosis or autophagy or cell cycle-related protein were detected by immunoblot analysis.ResultsIn our study, we confirmed that resveratrol reversed TNF- mediated cell proliferation in RA-FLS. Meanwhile, resveratrol blocked cells at the G2/M stage and reduced the ratio of S phase cells through upregulation of p53 and consequently led to apoptotic cell death. Quite interestingly, we found that resveratrol reversed TNF--induced autophagy. Inhibition of autophagy by resveratrol or autophagy inhibitor or Beclin-1 siRNA suppressed TNF- mediated cell survival and promoted cell apoptosis. However, the autophagy inducer rapamycin (RAPA) reversed the effect of resveratrol on autophagy and cell proliferation. Mechanistic studies revealed that resveratrol inhibited the activation of the phosphoinositide 3-kinases/serine-threonine kinase (PI3K/AKT) pathway. Inhibition of PI3K/AKT pathway by inhibitor LY294002 or resveratrol increased the expression of p53 and decreased the expression of cycle protein (cyclin B1), which further led to block cells in the G2/M arrest.ConclusionsOur preliminary study indicated that resveratrol may suppress RA-FLS cell survival and promote apoptosis at least partly through regulation of autophagy and the AKT-p53 axis.