Protective And Therapeutic Effect Of Exogenous Pulmonary Surfactant On The Experimental Chronic Obstructive Pulmonary Disease In Rats

[OBJECTIVE] To investigate the protective and therapeutic effect of pulmonary surfactant in the pathogenesis of chronic obstructive pulmonary disease in rats.[METHODS] COPD animal model was established by smoke inhalations and intratracheal instillations of lipopolysaccharide in Wistar rats. Thirty Wistar rats were randomly divided into 3 groups as follows: normal group(N), control group(C),and treatment group(T) .The last two groups received smoke inhalations daily for 6 weeks and received intratracheal instillations of lipopolysaccharide twice, one of which received exogenous pulmonary surfactant treatment(100mg/Kg BW) in the 2nd,3rd,5th,6th week(4 times) by intratracheal instillation before exposure to cigarette smoking. Lung function test blood gas analysis . light microscopy and electromicroscopy observations were performed in each group. Pulmonary mean linear intercept (MLI), mean alveolar numbers (MAN), and pulmonary alveolar area (PAA) were measured by image analysis. The expression of surfactant protein A(SP-A) were observed by immunohistochemistry.[RESULTS] Smoking for 30 days and instillations of lipopolysaccharide twice resulted in chronic bronchitis and emphysema(Fig 2,5). MLI and PAA increased and MAN decreased in the two experimental groups compared with in the normal group (P< O.OlXtable l).FEV_0.3 and FEV0.3/FVC decreased and Re increased in the two experiment groups compared with in the normal group (P<0.01)(table 2).PaO₂ decreased and PaCO₂ increased in the two experimental groups compared with in the normal group(table 3). The expression of SP-A in the two experimental groups were decreased compared with in the normal group (P<0.01) (table 4). Administration of exogenous pulmonary surfactant for 4 times resulted in statistically significant inhibition of pulmonary injury (Fig 3, 6). MLI and PAA decreased and MAN increased in T compared with in C(P<0.01).The lung function was improved in T compared with in C(P<0.01): FEV0.3 and FEV0.3/FVC increased and Re decreased in T, also the PaO₂ increased and PaCO₂ decreased .The SP-A positive cells increased in T(Fig 9) compared with in C(Fig 8).[CONCLUSION] exogenous pulmonary surfactant may have a protective andtherapeutic effect on COPD model of rats by alleviating airway inflammatory reaction , decreasing the destruction of alveolar and improving the lung function.