| Objective:To observe the expression of matrix metalloproteinase (MMP), tissue inhibitor of metalloproteinases (TIMP), apelin and angiotensin I receptor related protein (APJ) and the changes of MMP and TIMP induced by glucocorticoids in chronic obstructive pulmonary disease (COPD). To approach the effect of MMP and apelin-APJ system on the occurrence and development of COPD, and the mechanism of glucocorticoid treatment in COPD.Methods:1 Preparation of COPD model: SD rats were randomly divided into three groups: control group, the smoke-exposed group and the budesonide group. In addition to the control group, the rats in other two groups were exposed to secondhand cigarette smoke in the fume box twice a day for 4 months. The rats in budesonide group were treated with budesonide by spraying during the last month. The lung function was detected, the number and classification of WBC in bronchoalveolar lavage fluid (BALF) were determined, and pathological morphology of lung tissue was observed.2 The expression of MMP-1, MMP-2 and TIMP-2 proteins in rat BALF was detected with ELISA. The expression of MMP-1, MMP-2 and TIMP-2 mRNAs in rat lung tissue was measured by real-time quantitative RT-PCR.3 The expression of apelin and APJ protein in rat lung tissue was detected with immunohistochemistry and the mRNA expression was detected with real-time quantitative RT-PCR.4 The changes of apelin, NO, NOS and Ang-â…¡in blood plasm of COPD patients were dectected by ELISA. Results:1 Compared with the control group, FEV0.3/FVC and Cdy in smoke-exposed group were significantly decreased (P<0.01), and Ri and Re significantly increased (P<0.01). The percentage of neutrophils and total white blood cells in BALF of rats in smoke-exposed group were higher than those in control group (P<0.01), but the percentage of lymphocyte was lower (P<0.05). The mean lining interval (MLI) and bronchial wall thickness/diameter were significantly increased (P<0.01), and the mean alveolar number (MAN) was significantly decreased (P<0.01). Compared with the smoke-exposed group, budesonide treatment could increase FEV0.3/FVC (P<0.05), and decrease Re and Cdy (P<0.05). Budesonide had no significant effects on percentage of cells in each category, MAN, MLI and bronchial wall thickness/diameter (P>0.05).2 The proteins of MMP-1, MMP-2 and TIMP-2 in BALF were all expressed in three groups, which were most in smoke-exposed group and fewst in control group (P<0.01). Compared with smoke-exposed group, the protein expression of MMP-1 was decreased in budesonide group (P<0.05), but there were significant effects with MMP-2 and TIMP-2 (P>0.05). The mRNA expression of MMP-1 in rat lung tissue was 20.39 and 3.01 times in smoke-exposed group and budesonide group more than that in control group. The mRNA expression of MMP-2 in rat lung tissue of smoke-exposed group and budesonide group was 7.85 and 4.35 times more than that in control group. The mRNA expression of TIMP-2 in rat lung tissue of smoke-exposed group and budesonide group was 1.83 and 2.61 times compared with control group.The expressions of MMP-1, MMP-2 and TIMP-2 mRNAs were negatively correlated to FEV0.3/FVC (r =-0.37,-0.52,-0.40; P<0.05, P<0.01, P<0.05).3 Apelin and APJ were mainly expressed in the epithelial cells of bronch and lung, alveolar macrophages, vascular endothelial cells, and the membrane and cytoplasm of some alveolar wall cells. The expresstion of apelin and APJ protein in smoke-exposed group was lower than that in control group (P<0.05). The mRNA expression of apelin and APJ in smoke-exposed group was decreased by 44% and 13% compared with control group. The mRNA expression of apelin and APJ in rat lung tissue was negatively correlated to RV/(LV+S) (r=-0.454, -0.448; all P<0.05), while the mRNA expression of apelin and APJ in rat lung tissue was positively correlated to the FEV0.3/FVC (r= 0.529, 0.475; all P<0.05)4 The level of apelin, NO and NOS in plasm of COPD patients was lower than that in normal people, which was further decreased in pulmonary hypertension group and heart failure group (P<0.05). The concentration of Ang-â…¡in plasm of COPD patients was higher than that in the nomal people (P <0.05). The content of apelin, NO and NOS in plasm was negatively correlated to pulmonary artery pressure. FEV1%Pre was positively corelated to apelin (r = 0.797), and was negatively correlated to Ang-â…¡(r =- 0.881).Conclusion:1 In this study, COPD rat model was successfully established by inhalation of cigarette smoke. The number of inflammatory cells in BALF was decreased by budesonide treatment, but there was no significant effect on pathological morphology of rat lung.2 Expression of MMP-1, MMP-2 and TIMP-2 proteins and mRNA increased in lung tissue of rats with COPD, which was closely related to the occurrence and development of COPD. The proteins and mRNA expression of MMP-1 reduced after budesonide treatment, but the similar effect on MMP-2 and TIMP-2 wasn't observed, which was probably one of the mechanisms for budesonide improving lung function but having no effect on pathology.3 In the COPD rats, the mRNA and protein expression of apelin and its receptor APJ was decreased in lung tissue, which might be relate to decrease of lung function and right ventricular hypertrophy. It woud be one of the important factors leading to the development of COPD. Apelin-APJ system might be a new target for prevention and treatment of pulmonary hypertension and right ventricular hypertrophy induced by COPD.4 The level of apelin in plasm of COPD patients was decreased, which was further decreased in COPD patients with pulmonary hypertension or pulmonary heart failure. The change and interaction among apelin, NO, NOS and Ang-â…¡might be one of the mechanisms for disorder of pulmonary circulation homeostasis in COPD, concurrent pulmonary hypertension and pulmonary heart disease.
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