| Objective To study the effects of amiloride- an inhibitor of urokinase on pathological and pathophysiological changes of chronic obstructive pulmonary disease (COPD) model, and to investigate the role of urokinase plasminogen activator system components in pathogensis of COPD. Methods Healthy 24 Wistar rats were divided into control group, model group and amiloride group randomly. The model group rats were established by intratracheal instillation of lipopolysaccharide (LPS) twice and exposure to cigarette smoke. Amiloride group rats first accepted the same process as the model group, and then were administered amiloride in the drinking water after the second LPS instillation. The lung function measurements were carried out, the total and different white blood cell counts of bronchoalveolar lavage fluid(BALF) were determined , also collagen deposition of lung sections was observed by picrosirius staining. The protein expressions of uPA, uPAR, PAI-1 and MMP-9 in bronchial lung tissue were verfied by immunohistochemical analysis. The gene levels of uPA , uPAR, PAI-1 and MMP-9 were investigated by real time quantitative PCR.Results (1) Lung function: in COPD group expiratory resistance (Re) was significantly higher than that of control group [(4.17± 0.72)mmHg . s-1. g-1 vs (1.95 ± 0.56) mm Hg . s-1 . g-1, P<0.01]and amiloride group[ (4.17± 0.72) mm Hg.s-1 . g-1 vs (1.61±0.25), P<0.01], while forced expiratory volume in the 0.3 second/ forced expiratory capacity(FEV0.3/FVC %)and peak expiratory flow (PEF) were significantly lower than those of control group[ (51.80 ± 3.86) % vs (95.34±2.80) %, (15.37 ± 1.76) ml/s vs(31.57 ± 5.17) ml/s , respectively,P<0.01]and amiloride group[(51.80±3.86) % vs (98.46 ± 0.94) %, (15.37±1.76) ml/s vs(41.65 ± 3.21) ml/s , respectively, P<0.01].(2) Inflammatory cells in BALF: significant increase in total white blood cells and percentage of neutrophils and macrophages in BALF was found in COPD group [(6.64 ± 1.43) × 106/ml, ( 3.43±1.74) % , (5.35±2.53) %, respectively] than those of control group [(2.14 ± 0.68) × 106/ml,(1.13±1.59) % , (1.27±1.18) % ,respectively]and amiloride group[ (4.17 ± 1.18)× 106ml, (1.05 ± 0.20) % , (2.52±1.60) %, respectively] (P<0. 001) . There was no significant difference between control group and amiloride group.(3) Collagen quantitation analysis: the collagen in COPD group, mainly type I collagen , in airway walls was significantly increased. Area of collagen were significantly higher than control group [ (67050±14710) VS (11797 ± 2806), P<0.001]and amiloride group[ (67050±14710) VS(17113 ± 5945), P<0. 001]. There was no difference between control group and amiloride group.(4)The protein expressions of uPA, uPAR,PAI-1 and MMP-9:there were maily expressed in inflammatory cells(including monocyte-macrophage , neurophils and lymphocyte) , alveolar epithelial cells, airway epithelial cells and fibroblasts. In model group, uPA ,uPAR and PAI-1 levels [(0.166 ± 0.010), (0.158 ± 0.024), (0.171±0.012), (0.159 ± 0.007), respecti vely] were significantly increased compared to those in control group[(0.137 ± 0.015), (0.122 ± 0.009), (0.144 ± 0.005), (0.128 ± 0.133), respectively, P<0.001] and amiloride group[(0.126 ± 0.004 ) ,(0.120±0.010) , (0.122 ± 0.004) (0.131±0.006) , respectively, P<0.001]. Moreover, the protein expression of uPAR was positively correlated with neutrophils in BALF in COPD group (r=0.7.54, P<0.031) ; uPA and PAI-1 levels in amiloride group were significantly decreased than those in control group.(5) The mRNA levels of uPA, uPAR, PAI-1 and MMP-9:the level of uPA, uPAR, PAI-1, MMP-9 in model group [(4.37±1.85) × 10-5, (4.40±1.55) ×10-5,(6.61 ±4.07)×10-5, (5.91±2.52)× 10-5, respectively] were significantly increased compared with those in control group[(1.30±1.08)×10-5,(2.39 ± 2.05) ×10-5, (1.89 ± 0.74) × 10-5, (1.85 ± 0.72)×10-5, respectively](P<0.05) . uPA and MMP-9 mRNA levels in amiloride group were decreased than those of model group (P<0.05) ; uPAR and PAI-1 mRNA levels were also decreased, but there were no significant difference between amiloride group and model group (P>0. 05) .Conclusions ?In the COPD model group rats, established by intratracheal instillation of LPS and exposure to cigarette smoke, the protein and gene levels of uPA, uPAR, PAI-1 and MMP-9 are significantly increased than those in control group .(2)Administration of uPA inhibitor-amiloride could down-regulate the expressions of uPA system componemts and MMP-9, significantly palliate the pathological and pathophysiological changes in COPD rats. uPA system componemts are the key mediators regulating inflammatory reaction and tissue remodeling in COPD pathological process.
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