The Role Of P53 On Inflammation And Proliferation Of Fibroblast-like Synoviocytes

Objective.To investigate the role of p53 on inflammation and proliferation of fibroblast-like synoviocytes(FLS),including the relationship between p53 and NF-κB, p38,JNK and their downstream pro-inflammatory cytokines and matrix metalloproteinases(MMPs),as well as the influence of p53 on synovial proliferation and related signal transduction pathway.Materials and Methods.Synovial tissues were obtained from patients at joint replacement surgery,and FLS were cultured in vitro.(1) FLS was co-incubated with TNF-αor IL-1βat the concentration of 0.1 ng/ml,1 ng/ml,10ng/ml respectively for 24 hours.The supernatant was then collected for ELISA assay to detect cytokines and MMPs,while the cells were lysed for Western blot to evaluate the expression of p53 and p21.(2) p53 small interfering RNA(siRNA) or scrambled siRNA(sc siRNA) were electrotransfected into FLS.Three days later,step(1) was repeated,or FLS was co-incubated with IL-1β2ng/ml for 15 minutes and then lyzed for Western Blot to identify the activation of signal transduction pathways like NF-κB,p38,JNK and ERK.Results.(1) TNF-αand IL-1βcan inhibit expression of p53,and they both can stimulate FLS overexpressing IL-6 and MMP-1(P＜0.001)(2) p53 siRNA can effectively knockdown p53,leading to significant increase of IL-6 and MMP-1 secretion (P＜0.05).When IL-1βwas introduced,suppression of p53 by p53 siRNA provokes activation of P-JNK,P-p38 and P-IκBα,compared with control group.(3) Transfection of p53 siRNA into FLS induces p21 decline along with the suppression of p53.When coincubated with IL-1β,suppression of p53 results in elevated P-ERK in FLS.Conclusions.(1) p53 defect in FLS may play an essential role in synovitis.Inhibition of p53 leads to activation of signal transduction pathways like NF-κB,p38 and JNK, results in subsequent elevation of downstream expression of pro-inflammatory cytokines as well as MMPs.Meanwhile,cytokines further downregulate expression of p53.This feedback loop involving p53 may well explain the development and propagation of synovitis.(2) In addition to promote FLS proliferation by inducing elevated cytokines, suppression of p53 also contributes to FLS proliferation via p21 and ERK in the pathway of cell cycle.