Effects of Recombinant Activated Protein-C derivated from Drotrekogin-alpha on the Bleomycin-induced pulmonary fibrosis in rats

Objective: In this study we aimed to test the preventive effects of intraperitoneal drotrecogin alpha which is derivated from activated protein C (APC), bleomycin (BLM) induced lung fibrosis in rats. We planned to compare the results of lung tissue and bronchoalveolar lavage (BAL) liquid specimens in histological and biochemical analyses both with negative control (placebo) and steroid treatment that has a proven efficacy.Material and Methods: In the study 30 male Wistar albino rats were used. In the day ?0? when BLM was injected, the control group (n=6) was given intratracheal saline, BLM group (n=7), steroid group (n=7) and APC group (n=10) were given BLM (2,5 mg/kg) intratracheally. Two days before the BLM injection, the APC group was given drotrecogin-alpha which is derivated from APC 100 µg/kg/day and steroid group was given metilprednisolon 5mg/kg/day intraperitoneally. This process continued for 16 days until the 14th day when the rats were decapitated. BAL liquid were taken from each group and the periferal blood elements were analysed microscopically. The hydroxyproline volues in the lung tissue were evaluated biochemically by Woessner method and the fibrosis that was made in the lung was staged histopathologically from 0 to 8 according to Ashcroft?s criterias.Findings: In this study fibrosis was succesfully made in the lungs of rats by BLM experimentally. As an indicator of the pulmonary fibrosis , the levels of the pulmonary tissue hydroxyproline which is the basic aminoacid of the collagen?s structure and histopathologically the Ashcroft fibrosis scores were used. In the histopathological analysis, no fibrotic area was seen in the lungs of the rats in the control group while fibrosis was seen in all of the other groups. The fibrosis scores in the BLM group (4,86±0,93) were found significiantly higher than the ones in the other groups (p<0,05). In BLM+steroid (2,57±0,94) and BLM+APC (2,67±0,76) groups, fibrosis scores were significiantly lower than the BLM group (p<0,05). In the comparison of the hydroxyproline levels, it was significiantly higher (p<0,05) in the BLM group (5,65 ±0,78) and BLM + steroid group (4,72 ±0,25) than the control group (3,37 ±0,51) but the hydroxyproline values in the BLM+APC (2,67 ±0,76) were significiantly lower (p<0,05) than all of the other groups. In the peripheral smears taken from the BAL liquid of each group, the neutrophil percentage rates were significiantly higher in the BLM group (21,1 ±2,7) than the ones in all of the other groups (p<0,05), but the macrophage percentages (76,7 ±2,3) were significiantly lower than the ones in all of the other groups (p<0,05). In the comparison between the groups excluding BLM group, no significiant difference was noticed. Also, there was no significiant difference in the lymphocite and eosinophil percentage rates between the groups.Results: These study results show that the drotrecogin alpha that?s derivated from recombinant APC has protective and regressive effects in the pulmonary fibrosis that?s induced by BLM. Also, it shows that APC has antifibrotic effects in addition to its anticoagulant effects. In the cases where the beginning of the pulmonary fibrosis is diagnosed, the use of drotrecogin alpha may be advised so as to decelerate the fibrosis process, because of its useful effects observed in our study. However, further studies are needed to say whether drotrecogin alpha is useful or not.Keywords: Pulmonary fibrosis, rats, bleomycin, activated protein C, drotrekogin-alfa, hydroxyprolinee