Effects of Granulocyte Colony-Stimulating Factor on the Development of Inflammation in Bleomycin-Induced Lung Injury

抄録

We investigated the effects of granulocyte colony-stimulating factor (G-CSF) on the development of inflammation in the lung induced by intratracheal administration of bleomycin (BLM, 2 mg/200 μl) in rats. G-CSF (100 μg/kg/day) was subcutaneously administered for 7 days starting from 3 (inflammatory phase) or 14 days (fibrogenic phase) after BLM administration. The administration of G-CSF to BLM-treated rats in the inflammatory phase increased the total lung lesion per unit pulmonary parenchyma, the score of lung fibrosis, the peripheral neutrophil count and the number of neutrophils infiltrating the pulmonary lesion, as well as the severity of other histopathologic changes (edema, hemorrhage and proliferation of myofibroblasts in the alveolar lumen, hyperplasia of bronchial and alveolar epithelial cells, and bronchiolization). Although increases in the peripheral neutrophil count and the number of neutrophils infiltrating the pulmonary lesion were observed following treatment with G-CSF, there were no further increases on lung injury in the fibrogenic phase in BLM-treated rats. These findings suggest that the effects of neutrophils on the lung in the rats treated with G-CSF may be closely related not only to the number of neutrophils, but also to the inflammatory phase of BLM-induced pulmonary lesions.