Expression And Significance Of IL-32 In Lung Tissues Of Mice With Pulmonary Fibrosis Induced By Bleomycin

Objective To determine the expression and significance of IL-32 in lung tissues of mice with pulmonary fibrosis (PF) induced by bleomycin at various periods and to study the effects of the cytokine on pulmonary fibrosis.Methods Seventy two male mice were randomly divided into three groups:control group (n=24), experimental group (n=24) and treated group(n=24). Seventy two mice were assigned to receive intratracheal instillation of bleomycin (BLM) in experiment group and treated group and normal saline in control group. The mice of treated group were injected into abdominal cavity with dexamethasone(5mg/kg) every day. On the day of 3rd,7th,14th and 28th after administration,6 mice of each group were sacrificed and the lung tissues were harvested. The lung tissues were performed with immunohistochemical staining, pathological sections and the expressions of IL-32 protein were detected with the method of Western Blotting.Results In the control group, after the investigation of histopathology of the lung tissues, infiltration of inflammatory cell and inflammatory exudation of alveolars were rarely to be found, meanwhile, without finding alveolar septum thickening,the proliferation of fibroblast and remarkable alterations of PF. Dynamic changes range from alveolitis to pulmonary fibrosis could be observed in the slices by pathological method according to times in the experimental group. In the early stage, the inflammatory exudation in alveolars was heavier, there were a large number of inflammatory cells infiltration in the alveolar wall.In the middle and late stages, reduction of the inflammatory exudation could be seen gradually, alveolars collapsed and disappeared, the sizes were drfferent, alveolar septum became thicken gradually, a large number of proliferating fibroblasts could be seen. The scores of alveolitis and lung fibrosis were higher in the experimental group than those in the control group and the treatment group (P<0.05). In the treatment group, dynamics of changes from alvealitis to pulmonary fibrosis could be seen in the pathological examination, however, alveolitis and pulmonary fibrosis in the experimental group were lighter than those in the experimental group. There is only a lower amount of expression of IL-32 in the control group by Immunohistochemistry, the expression of IL-32 is main in the alveolar walls. The expression of IL-32 was significantly high in the 7th,14th days and significantly low on the 28th day in the experimental group which mainly appeared in the alveolar walls of mesothelial cells, macrophages, neutrophils, lymphocytes and alveolar cavity exudation. In the treatment group, the expression of IL-32 was relatively low, but still higher than those in the control group. The expression of IL-32 protein shows that there is only a lower amount of expression in the control group, in different stages there was no significant difference (P>0.05) by the Western Blot examination. In the experimental group, the expressions of IL-32 protein were higher from the third day than those in the control group and the treatment group, the expression of IL-32 reached a peak on the 14th day and decreased on the 28th day, but the expression of IL-32 were still higher than those in the control group and treatment group (P<0.01). There was no statistically significance (P>0.05) on the third day compared with the 28th day in the group, there were statistically significant (P<0.05) on the rest days. A similar trend showed in the treatment group, but the expression of IL-32 were lower than the the experimental group, there was a significant statistical significance (P<0.01).Conclusion IL-32 may play an important role in the early and mid-term during the pulmonary fibrosis because it is high expression in the pulmonary fibrosis. Dexamethasone has a certain degree therapeutic effect on the early pulmonary fibrosis.