The Role Of ICAM-1in Lung Injury Of The Experimental Rat Model With Chronic Obstructive Pulmonary Disease

Background Chronic obstructive pulmonary disease (COPD) is a chronic respiratory diseases with high prevalence, high morbidity, high mortality. The lung function of patients with COPD was decreased. But the mechanism was unclear, smoking and infection were the main risk factor; especially respiratory infections and repeated chronic inflammation were an important part of COPD development. Studies showed that chronic inflammation and inflammatory injury was pathophysiological foundation of COPD.Objectives To explore the role of ICAM-1in Chronic Obstructive Pulmonary Disease based on the analysis and study on the expression of ICAM-1and TNF-a in lung tisse of rat with chronic obstructive pulmonary disease.Methods30rats were divided into3equal groups randomly:group1is examination group (EG), group2is control group(CG), group3is blank control group(BG). To all rats, anaesthesia by4%chloral hydrate solution (10ml.kg-1), immobilized rats, skin preparation, place endotracheal intubation and Left carotid artery catheterization, the diaphragm are connected with BL-420biological signal collect and analysis system through needle electrode for recording respiratory curve. In EG group, rats of the model of chronic obstructive pulmonary disease(COPD) was established by both intratracheal instillation of lipopolysaccharide (LPS) and passive smoking for28days, that is, LPS (1mg-Kg-1) was instilled intratracheally for first day and fourteenth day, these rats were exposed to cigarette smoke for28days.In CG group, rats were merely exposed to cigarette smoke for28days.But BG group is the no-treatment group. These respiratory curve dates of3groups were retained to comparative analysis. Take5ml peripheral blood and arterial blood, then rats were sacrificed, lung were taked out, bronchial pulmonary alveolus was lavaged immediately, so5ml bronchoalveolar lavage fluids(BALF)can be get, the level of tumor necrosis factor-a(TNF-a) in peripheral blood and BALF were measured in BALF by Enzyme Linked Immunosorbent Assay (ELISA) methods. Inferior lobe of right lung tissures were divided into foour partsrthe first part was fixed with4%formaldehydum polymerisatum, embedded by paraffin and sliced into4jam continuous sections for HE staining to test the morphological changes of lung tissue and immunohistochemical staining to test the expression of inflammatory cell adhesion molecules-1(ICAM-1)and TNF-a; the second part was homogenized to test the activity of Myeloperoxidase(MPO) by colorimetric method; the third part was dried in vacuum to test water content of lung tisse; the fourth part was immediateiy processed for reverse transcription-polymerase chain reaction(RT-PCR). The expression of mRNA of ICAM-1and TNF-a were detected by RT-PCR. All datas were retained and analysed through SPSS13.0statistical software, statistical methods include Spearman rank sum test, Independent t-test and chi-square test (size of test α=0.05).Result①Compared with CG and BG, the result of respiratory curve dates showed that, the inspiratory phase time of EG was shorted(t=6.125, p<0.001; t=10.511, P<0.001), the expiratory phase time of EG was prolonged(t=17.327, p<0.001; t=13.261; p<0.001), the amplitude of EG was decreased(t=21.412,(P<0.001; t=13.225, P<0.001), but the frequency of EG was incredsed(t=14.085, P<0.001; t=14.172, p<0.001).Compared with CG and BG, the PaO2of EG was obviously lower (t=17.125, P<0.001; t=9.016, P<0.001), the PaO2of EG was obviously higher (t=16.412, P<0.001t=20.233, P<0.001); The Wet/Dry of lung tisse of EG was higher than that of CG (t=14.136, P<0.001) and BG (t=11.145, P<0.001), the water content of lung tisse of EG was higher than that of CG (t=12.147, P<0.001) and BG (t=13.625, P<0.001)②Compared with CG and BG, the activity of MPO of EG lung tisse was increased (t=13.137, P<0.001;t=10.166, P<0.001).③Compared with CG (t=15.135, P<0.001) and BG (t=11.124, p<0.05), the result of Enzyme linked immunosorbent assay (ELISA) showed that, the level of TNF-a in peripheral blood was higher, in BALF was also higher, the differences was statically significant.④The result of HE staining showed that, compared with CG and BG, the pathomorphism of lung tissue of EG was the expression of COPD with chronic inflammatory injury, such as denaturalization and necrosis Emerg-ed in the alveolar epithelial cell, infiltration of neutrophilic granulocyteand macrophage, pulmonary bulla, and so on.the result of immunohistochemistry showed that, the expression of IC AM-land TNF-a of EG were obviously stronger than CG (x2=9.24, p<0.05;x2=6.52,p<0.05) and BEG Cx2=7.21, p<0.05; x2=5.93, p<0.05), and the Spearman rank sum test result showed positive correlation between the expression ICAM-1with the expression of TNF-a(r=0.472. p=0.014).⑤the result of RT-PCR showed that,, the expression of ICAM-land TNF-a were up-regulated compared with CG (t=18.022, p<0.001; t=13.625,p<0.001) and BG (t=14.125, p<0.001; t=21.126, p<0.05) the differences was statically significant.Conclusion LPS and cigarette smoke, are important risk factors for occurrence and development of COPD, they can stimulate pulmonary vascular endothelial cells to release ICAM-1, ICAM-1can start the aggregation and adhesion of neutrophils, that is, pro-inflammatory cytokines TNF-a is increased, so inflammatory reaction will be unbalanced, the finish result is lung injury and Respiratory dysfunction.These is the important mechanism of COPD.