The Expression Of Collagenases And TIMP-1 And Its Effect On COPD Lung Tissue Remodeling In Rats

Objective: COPD is one of the common respiratory chronic diseases in adults ,especially in the elder. Chronic airway inflammation and airway remodeling are key features of COPD. Recently,matrix metalloproteinases (MMPs) and their inhibitors, tissue inhibitors of metalloproteinases (TIMPs) are thought to contribute to the pathogenesis of COPD via their influence on the matrix deposition and degradation.The main aim of this study is to investigate the expression of the collagenases (MMP-1, MMP-8 and MMP-13)and its inhibitor,tissue inhibtor metalloproteinase-1 (TIMP-1) in the rat lung of the experimental models of COPD.Methods: Male Wistar rats (10 weeks of age) were given intratracheal instillation of 0.2 mg lipopolysaccharide(LPS) once for every two weeks(twice), and then animals were exposed to 5% cigarette smoke for 0.5 h/twice per day for 32 days.One group of these rats hadbeen inhaled Ipratropium bromide once per day since the 8th day . The lung function was measured ,pathological changes were also observed. The neutrophils, lymphocytes and alveolar macrophages of the bronchoalveolar lavage fluid (BALF) were counted. The expression of MMP-1,MMP-8,and TIMP-1 in small airway and lung tissue was verified by immunohistochemical analysis. Transcriptional levels of MMP-13 and TIMP-1 mRNA extracted from the lungs were assessed by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). Result: 1. In COPD model group,the pathological changes of bronchi and lung tissue, the changes of lung function were similar to those of the COPD patients. In COPD model group and Ipratropium bromide group, the epithelial and smooth muscle of small airway were thicker than in control group(p<0.05);the area of alveolus were also lager than in controls(P<0.05).The number of neutrophils, lymphocytes and alveolar macrophages in BALF of the model group were significantly increased than those of control group (P<0.05). 2. By using image analyzer, immunoreactivity of MMP-1,MMP-8,TIMP-1 were markedly increased in cells of bronchi, fibroblasts, macrophages and pneumocytes in COPD model group,ipratropium bromide group as compared to those of control group. 3.The mRNA expression of MMP-13 and TIMP-1 in COPD model group (0.761±0.189, 0.950±0.158 respectively),inIpratropium bromide group ( 0.744±0.216, 0.840±0.250 respectively) were significantly increased than those in control group (0.497±0.150, 0.301±0.093 respectively) as well (P < 0.01 or P < 0.001). 4.Positive correlation between area of alveolus and MMP-1 (r=0.534,P<0.05),area of alveolus and MMP-8 (r=0.534,P<0.05),but a negetive correlation between area of alveolus and TIMP-1 (r=0.355,P>0.05)were found. Positive correlation between area of bronchial smooth muscle and MMP-1 (r=0.353,P<0.05),area of bronchial smooth muscle and TIMP-1 (r=0.345,P<0.05),but a negetive correlation between area of bronchial smooth muscle and MMP-8(r=0.210,P>0.05) were found. 5.Between the COPD model group and Ipratropium bromide group,there were no significant difference in the area of the epithelial and smooth muscle of small bronchi,area of alveolus.Comparing with COPD group,the expression of collangenases and TIMP-1 also no significant change in Ipratropium bromide group. Conclusions: 1.We successfully replicated the COPD experimental models through intratracheal instillation of LPS combined with fumigation;2. The expression of MMP-1,MMP-8,MMP-13 and TIMP-1 increas significantly in the bronchi and lung tissue of COPD rats;the imbalance between collages and TIMP-1may due to the impication of the process of COPD lung remodeling.3.Comparing with the COPD model group,there were decrease expression of MMP-1, MMP-8, MMP-13 andTIMP-1 in the iprtropium bromide group,but no statistic significance,further observation through extending the number of samples,prolong the drug use period,and dditional studies in patients with COPD are needed.