Objective To study the influence of hepatocyte growth factor (HGF) antibody on the lung expression level of matrix metalloproteinases-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1). Methods Thirty male Wistar rats were randomly divided into 3 groups: control group

model group

and intervention group. Endotoxin was intratracheally infused in the model and intervention groups. HGF antibody was injected in the rats of the intervention group from day 1 to day 14

while the same volume of saline was injected in the control group. The rats were sacrificed on day 28 after endotoxin treatment. The amounts of MMP-9 mRNA and TIMP-1 mRNA were measured by reverse transcription-polymerase chain reaction

and protein expression levels of MMP-9 and TIMP-1 were measured by immunohistochem-istry. Results In the model group

both mRNA and protein expression levels of TIMP-1 were significantly increased

the same as MMP-9. In the intervention group

the increase of TIMP-1 was remarkably reduced compared with the model group

while the mRNA and protein expression levels of MMP-9 were still increased. Conclusion HGF activity may accelerate the repair of lung injury through contrary regulating the expression levels of TIMP-1 and MMP-9.