Luteolin inhibits proliferation and affects the function of stimulated rat synovial fibroblasts

Abstract Hyperproliferation of synovial fibroblasts is considered to be a pivotal event in the pathogenesis of rheumatoid arthritis (RA). Luteolin, a flavonoid, inhibits the proliferation of synovial fibroblasts in collagen‐induced arthritic rats. Treatment with luteolin also decreases the secretion of matrix metalloprotease‐1 and −3 and the expression of IL‐6, IL‐8, IL‐15, and TGF‐β. Luteolin treatment caused a delay of cells in the G 2 /M phase. Interestingly, combination treatment with luteolin and TNF‐α exhibited a synergistic inhibitory effect in all experiments. Western blotting demonstrated that treatment with luteolin alone or combined with TNF‐α inhibited the MAPK/ERKs and PI3K‐Akt pathways. These results indicate that luteolin inhibits the proliferation and partially blocks the pathogenic function of synovial fibroblasts in rheumatoid arthritis.