Objective To investigate the mechanism by which baicalein alleviates osteoarthritis by regulating Sirtuin(Sirt)to inhibit the senescence of fibroblast-like synoviocytes(FLS).Methods FLS were extracted from synovium of non-osteoar-thritis patients(3 patients)and osteoarthritis patients(3 patients),and assessed the senescence of FLS in osteoarthritis patients by Western blot,β-galactosidase staining and immunofluorescence,and examined the changing levels of Sirt family proteins and mRNAs in FLS.The relative expression level of Sirt1 in FLS was knocked down by transfection with Sirt1 siRNA,and the antioxi-dative capacity and senescence degree of FLS were analyzed.Chondrocytes were co-cultured with FLS and functional changes in chondrocytes were detected by Western blot.After inducing FLS senescence with bleomycin(BLM),different concentrations of ba-icalein were administered to detect the expression levels of Sirt1,p16,and p21 proteins and intracellular reactive oxygen species(ROS).The expression level of Sirt1 in FLS was knocked down,and BLM and baicalein treatments were applied.The relative ex-pression levels of Sirt1 and ROS were detected using Western blot and ROS assays.After BLM-induced FLS senescence,baicalein and Compound C were added.The relative expression levels of phosphorylated AMP-activated protein kinase(pAMPK),nuclear factor erythroid 2-related factor 2(NRF2),p 16,p21,and ROS were detected by Western blot and ROS assays.Results The rela-tive expression of p 16 and p21 in FLS in the osteoarthritic group were 3.66±0.38 and 3.55±0.34,which were higher than those in non-osteoarthritis group 1.00±0.07 and 1.00±0.09(t=1 1.860,P＜0.001;t=12.520,P＜0.001).The relative expression levels of Sirtl and Sirt6 in FLS in the osteoarthritis group were 0.30±0.04 and 0.16±0.01,which were smaller than those in the non-osteoarthritis group 1.00±0.03 and 1.00±0.04(t=23.840,P＜0.001;t=34.130,P＜0.001).After baicalein treatment,the relative expression of ROS was 2.58±0.28,1.65±0.14 and 1.00±0.24 in the BLM,BLM+Bai and control groups,respectively,with statistically signifi-cant differences between the groups(F=35.700,P＜0.001),which was greater in the BLM and BLM+Bai than in the control group,and lower in the BLM+Bai than in the BLM group(P＜0.05).The relative expression of pAMPK and NRF2 was 0.28±0.02 and 0.38±0.09 after Compound C+Baicalein treatment,which was lower than that of 0.56±0.07 and 0.60±0.08 in the BLM+Bai group(P＜0.05).The relative expression of ROS increased from 1.75±0.16 to 3.45±0.12(P＜0.001).The proportion of positivity in the BLM+Bai+Compound C,BLM+Bai and control groups was 47.30％±4.29％,18.18％±3.89％and 7.70％±3.53％(F=109.700,P＜0.001),respectively,with the BLM+Bai+Compound C group being higher than that in the BLM+Bai group(P＜0.05).Conclusion The downregulation of Sirt1 expression in patients with osteoarthritis leads to FLS senescence and accelerates the progression of osteoarthritis.Baicalein can inhibit FLS senescence by activating Sirt1/AMPK/NRF2 pathway,which may delay the progression of osteoarthritis and improve the function of chondrocytes.
维普
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