Luteolin-7-O-rutinoside alleviates rheumatoid arthritis through downregulation of the PI3K/AKT/NF-κB and cell cycle signaling pathways
Rheumatoid arthritis (RA) is a chronic autoimmune disease with limited therapeutic options, and current therapies are often associated with considerable adverse effects. Traditional Chinese medicinal plants such as Cirsium japonicum contain luteolin-7-O-rutinoside (lut-7-O-rutin), a flavonoid with reported anti-inflammatory activity. Lut-7-O-rutin is a flavonoid compound found in various medicinal plants. This study aimed to investigate the therapeutic effects of lut-7-O-rutin on RA and elucidate the underlying mechanisms using both in vitro and in vivo models, with a particular focus on the phosphatidylinositol 3-kinase/protein kinase B/nuclear factor-κB (PI3K/AKT/NF-κB) and cell cycle signaling pathways. In vitro experiments, including ELISA, Western blotting, and immunofluorescence assays, were performed to evaluate the anti-inflammatory effects of lut-7-O-rutin on the IL-1β-induced inflammatory response in fibroblast-like synoviocytes (FLSs) derived from rat knee synovium. The effects of lut-7-O-rutin on the PI3K/AKT/NF-κB and cell cycle signaling pathways were also examined. In vivo experiments were conducted to assess the therapeutic effects of lut-7-O-rutin administered by gastric gavage in collagen-induced arthritis (CIA) rats. Lut-7-O-rutin at 3.75 μg/mL significantly reduced the levels of TNF-α, IL-6, and COX-2 in IL-1β-induced FLSs. It also decreased the phosphorylation levels of key components of the PI3K/AKT/NF-κB signaling pathway, thereby attenuating inflammation. In addition, lut-7-O-rutin downregulated the expression of the cell cycle-associated proteins CDK4 and CCND and inhibited FLS proliferation. In vivo , 21 days of lut-7-O-rutin administration by gastric gavage resulted in a significant reduction in arthritis scores, organ indices, and serum inflammatory mediator levels in CIA rats. Histopathological analysis showed that lut-7-O-rutin alleviated synovial inflammation, synovial hyperplasia, and bone erosion. Immunohistochemistry (IHC) analysis further showed that lut-7-O-rutin significantly inhibited the expression of key proteins in the PI3K/AKT and cell cycle signaling pathways. These findings demonstrate that lut-7-O-rutin alleviates joint inflammation and synovial hyperplasia in RA may be mediated through inhibiting the PI3K/AKT/NF-κB signaling pathway and downregulating cell cycle-associated proteins, highlighting its potential as a therapeutic agent for RA.