Effects of dexamethasone on dynamic changes of lung tissue pathology,ultrastructure and levels of TGF-β_1 and IL-8 in the serum of Pingyangmycin-induced pulmonary fibrosis in rats

Objective To investigate the effects of dexamethasone on dynamic changes of lung tissue pathology,ultra-structure and the levels of TGF-β1 and IL-8 in the serum of Pingyangmycin-induced pulmonary fibrosis in rats.Methods 105 healthy male Wistar rats were randomly divided into three groups: the control group(n =25),the model group(n =40) and the dexamethasone group(n = 40).Rats in both the model group and the dexamethasone group were injected with Pingyangmycin(5 mg /kg) through tracheofistulization to induce pulmonary fibrosis,while rats in the control group were injected with equivalent physiological saline.After operation,dexamethasone(4 mg /kg body weight) was intrap-eritoneally subjected to the dexamethasone group rats once per day.Equivalent saline was administered to rats in both the control group and the model group.On the 1st,7th,14th,21st and 28th day,five rats in the control group and eight rats in both of the other two groups were dissected to observe the pathological changes of lung tissues.The ultra-structure and levels of TGF-β1 and IL-8 in the serum were determined by enzyme-linked immunosorbent assay.Results Histopathological examination results were consistent with the characteristics of rat pulmonary fibrosis models.The lung ultra-structures of the model group and the dexamethasone group significantly changed compared with the control group.At different time points,concentrations of TGF-β1 and IL-8 in serum were increased and then decreased in both the model group and the dexamethasone group,and were significantly higher than those of the control group,especially on the 7th day.Levels of TGF-β1 and IL-8 in the serum were similar between the model group and the dexamethasone group,and there were no significant difference between them(P 0.05).Conclusion TGF-β1 and IL-8 play an im-portant role in the process of alveolitis and the pulmonary fibrosis induced by Pingyangmycin in rats.Dexamethasone(4 mg /kg) does not reduce the levels of TGF-β1 and IL-8 in serum of Pingyangmycin-induced pulmonary fibrosis in rats,this may be associated with the immuno-compromised state,which increases the risk of the chance of infection.