The Influence Of Bilirubin On Expression Of Ln And EGF In Rat Pulmonary Emphysema Model

Objective: To investigate the influence of bilirubin on expression of Ln and EGF in rat pulmonary emphysema model. Method: Forty-eight Wistar rats were randomly divided into three groups, the control group, the pulmonary emphysema model group (the model group) and the bilirubin treated group (the treated group). Rat pulmonary emphysema model was established by chronic exposure to cigarette smoke in model group. Rats were treated by bilirubin (20mg/kg/d) through feeding before the pulmonary emphysema model had been established in bilirubin treated group, once a day, six days a week, six months in all. Rats in model group were treated by the equal amount of normal saline through feeding before exposed to smoke. All of the rats in three groups were killed to be tested at the end of six months. The levels of MAD and GSH of serum and broncho alveolar lavage fluid (BALF) were determined. The levels of laminin(Ln) in serum, in BALF and in the culture supernatants of ATII were measured by radioimmunoassay method. The expression of EGF and Ln were examined by immunohistochemical method and immunofluorescence method, respectively. The histopathological changes were evaluated. Results: (1) The levels of MDA of serum and BALF in model group were significantly increased than those of the control group (P<0.05,P<0.05), and those of BALF in treated group were significantly decreased than those of the model group (P<0.05). Significant decrease of the levels of GSH of serum and BALF were found in model group in comparison with those of the control group (P<0.05,P<0.05), and significant increase of those of BALF were found in treated group as compared with those of the model group (P<0.05). Significant negative correlation was observed between the levels of MDA and GSH of BALF(r=-0.81,P<0.05). (2) The levels of Ln in serum, BALF and the culture supernatants of ATII in model group were higher than those in control group to vary extent (P<0.05,P<0.05 and P<0.05) and the above mentioned parameters were reduced in different extent in treated groups than those in model group(P<0.05,P<0.05 and P<0.05). Statistically positive relationships were shown between the levels of Ln in BALF and in the culture supernatants ofATII(r=0.74,P<0.05). (3) The expression of Ln in the alveolar wall was significantly increased in model group than in control group (P<0.05) and those in treated group was significantly decreased than in model group (P<0.05). (4) Expression of EGF in the epithelial cell of bronchic of the model group was significantly higher than that of the control group (P<0.05), and that of the treated group was lower than that of the model group (P<0.05). (5) From histological observation, the pathological change in model group was accorded with those of pulmonary emphysema, and the change in the treated group was slight obviously. Conclusion: (1) There are complex changes of Ln during the form of pulmonary emphysema in rats, but bilirubin can prevent the development of pulmonary emphysema. (2) EGF and ATII play important roles in Ln remodelling of pulmonary emphysema. (3) Antioxidation can be provided by bilirubin and is very important in maintaining an oxidant/antioxidant balance.