Tuberc Respir Dis.  1987 Jun;34(2):95-108. 10.4046/trd.1987.34.2.95.

The Effect of Steroid on the Bleomycin-Induced Pulmonary Fibrosis in Rat -Analysis of Cell Patterns in the Broncholaveolar Lavage Fluid, Histopathologic Findings and Total Collagen Content of the Lung-

• KMID: 2528653
• DOI: http://doi.org/10.4046/trd.1987.34.2.95

Abstract

To study the effect of steroid on bleomycin-induced pulmonary fibrosis serial bronchoalveolar lavages (BAL) were done with histopathologic examination and the measurement of total hydroxyproline content of the lung after the intratracheal instillation of bleomycin in the rats. The animals were divided into 3 groups: control group received intratracheal injection of normal saline only, bleomycin group received intratracheal injection of 1.0mg of bleomycin and prednisolone group received daily injection of solumedrol (18mg/kg) in addition to intratracheal injection of bleomycin. We found: 1) In bleomycin group, total cell counts in BAL fluid was significantly increased from one day to 7days after the bleomycin administration. The percentage of neutophils was also elevated to 23.7% on one day after bleomycin and it remained to be higher than control group until 2 weeks after the bleomycin. The percentage of lymphocytes began to increase from 3 days after the bleomycin and it was persistent1y high until 2 weeks after the bleomycin. In prednisolone group, total cell counts and the percentage of neutrophils were the same as bleomycin group. But in the prednisolone one group, the percentage of lymphocytes was significant1y lower than the bleomycin group from one week to 2 weeks after the bleomycin injection. 2) In bleomycin group, from one day after bleomycin adÍninistration. patchy areas of interstitial edema with infiltration of neutrophils and monocytes were found and these inflammatory change was more progressive with time. At one week after bleomycin adiministration, reticulin condensation and collagen deposition was observed for the first time. Later on, inf1ammatory change began to subside but fibrotic change was more evident. In prednisolone group, essentially similar changes were found but the degree and extent of fibrosis seemed to be much less than bleomycin group. 3) In bleomycin group the total hydroxyproline content of the lung was significantly increased than the control group from one week after the bleomycin injection. In prednisolone group, the collagen content of the lung was lower than bleomycin group at all times and at 6 weeks after blomycin injection, the difference between prednisolone group and bleomycin group was statistically significant. These results suggest that steroid can reduce the degree of pulmonary fibrosis induced by bleomycin and the antiinf1ammatory action of steroid may not be the main mechanism of steroid effect. But steroid may act through the reduction in lymphocyte reaction in the lung.