Effect Of Smoking On The Expressional Levels Of Matrix Metalloproteinase-9 And Its Inhabitor-1 In Sensitized Rats

Objective To observe the effect of smoking on the expressional levels of lung tissue base correlation factor: matrix metalloproteinase-9 and its inhibitor, tissue inhibitor of Metalloproteinase in sensitized rats, and investigate the role of smoking in the processes of airway remodeling of asthma.Methods twenty-four male Wistar rats (GradeⅡ) were divided randomly into a control group, a sensitized group and a smoking sensitized group. The rats of post two groups were sensitized and challenged by ovalbumin to establish the asthmatic model. From the challenged third weeks, the smoking sensitized group rats were put in the self-made fumigating box to smoke passively, one time every day, ten cigarettes every time, one cigarette burned one hour, six day one week and eight weeks in all. The expressions of genes and their products of MMP-9 and timp-1 in lung tissue were defected using immunohistochemistry, RT-PCR in all rats of groups, and the total bronchial wall area was measured by image analysis system.Results 1.The bronchial wall thickness of the smoking sensitized group(23.28±2.38)was significantly higher than that of the sensitized group(20.06±2.94)and the control group(11.64±2.43,all P < 0.05),so did the sensitized group and the control group(P <0.05).2.The expression of lung tissue MMP-9mRNA(0.49±0.02) and the protein levels of airway endothelial cell MMP-9(32.78±2.60)were significantly higher than those of the sensitized group(0.41±0.04;23.05±2.11) and the control group(0.23±0.03;15.88±1.69; all P<0.01),so did the sensitized group and the control group(P < 0.01).3.The expression of lung tissue TIMP-1mRNA(0.53±0.02)and the protein levels of airway endothelial cell TIMP-1(34.54±2.9) were significantly higher than those of the sensitized group(0.37±0.05;21.25±2.28)and the control group(0.23±0.04;15.78±1.97; all P<0.01),so did the sensitized group and the control group(P<0.01).4.The ratio in lung tissue between MMP-9mRNA and TIMP-1mRNA of the smoking sensitized group was lower than that of the sensitized group(1.12±0.06)and the control group(1.03±0.09,all P<0.01),but the ratio of the sensitized group was higher than that of the control group(P<0.01).5.The ratio of protein levels in airway endothelial cell between MMP-9 and TIMP-1 ,in the smoking sensitized group(0.94±0.03) was lower than that of the sensitized group(1.09±0.07) and the control group(1.01±0.06, respectively P<0.05,<0.01),but the ratio of the sensitized group was higher than that of the control group(P<0.01).Conclusion Smoking can cause MMP-9 and TIMP-1 overexpression , disproportion and increase airway remodeling in the lung tissue of the smoking sensitized rats.