Abstract:

Objective  To investigate the effects of dexamethasone on dynamic changes of lung tissue pathology, ultrastructure and the levels of TGF-β1 and IL-8 in 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(5mg/kg)through tracheofistulization to induce pulmonary fibrosis, while rats in the control group were injected with equivalent physiological saline. After operation, dexamethasone (4mg/kg body weight) was intraperitoneally 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 the lung tissues. The ultrastructure and the levels of TGF-β1 and IL-8 in serum were determined by enzymelinked immunosorbent assay. Results   Histopathologic examination results were consistent with the characteristics of rat pulmonary fibrosis models. The lung ultrastructures of the model group and the dexamethasone group significantly changed compared with the control group. At different time points, the 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 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 important role in the process of alveolitis and the pulmonary fibrosis induced by Pingyangmycin in rats. Dexamethasone (4mg/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 immunocompromised state, which increases the risk of the chance of infection.

Key words: Pulmonary fibrosis; Pingyangmycin; TGF-β1;  Interleukin-8