Abstract： Objective To investigate the effect of transforming growth factor β1 (TGF-β1) on the expression of matrix metalloproteinase 9 (MMP-9),tissue inhibitor of metalloproteinase 1 (TIMP-1),nuclear factor kappa B(NF-κB) and the possible signalling pathways in human amniotic cells WISH.Methods The WISH cell line was cultured.WISH cells were added with TGF-β1 of different concentrations (0,2,10 and 20 ng/ml,respectively) for 24 hours.Then,reverse transcription (RT) PCR and western blotting were used to analyze the protein and mRNA expression of TIMP-1 and MMP-9; and the expression of NF-κB was analyzed by western blot.Results (1) The profile of TIMP-1 mRNA (0.413 ±0.036,0.623 ±0.058,1.392 ±0.124,1.387 ±0.102) in WISH cells elevated when the concentration of TGF-β1 increased (0,2,10,20 ng/ml).In accordance with TIMP-1 mRNA,the expression of TIMP-1 also elevated with the increase of TGF-β1 (0.357 ± 0.031,0.596 ± 0.048,1.243 ± 0.097 and 1.359 ± 0.121,respectively).And when 2,10 or 20 ng/ml of TGF-β1 was added,the TIMP-1 mRNA and protein were significantly higher than the TIMP-1 mRNA and protein when no TGF-β1 was added(P ＜ 0.05).(2)In contrast with TIMP-1,MMP-9 mRNA (1.325 ±0.056,0.987 ±0.081,0.610 ±0.034,0.347 ±0.023) in WISH cells decreased when the concentration of TGF-β1 increased (0,2,10,20 ng/ml).The MMP-9 protein (1.119 ±0.064,1.008 ±0.052,0.578 ±0.041,0.401 ±0.015) also decreased with the increase of TGF-β1.And when 2,10 or 20 ng/ml of TGF-β1 was added,the MMP-9 mRNA and protein were significantly lower than the MMP-9 mRNA and protein when no TGF-β1 was added (P ＜ 0.05).(3) The NF-κB protein (1.423 ±0.065,1.116 ± 0.045,0.796 ± 0.041,0.359 ± 0.021) was significandy reduced with the increase of TGF-β1 (0,2,10,20 ng/ml; P ＜ 0.05).Conclusions The mRNA and protein expression of TIMP-1 decreased when TGF-β1 was low in WISH cells,whereas those of MMP-9 elevated when TGF-β1 was low.The unbalance of TIMP-1 and MMP-9 was related to the pathology of the premature rupture of membrane.And the NF-κB singalling pathway might be an important mechanism in the regulation of TIMP-1 and MMP-9 system.