Repetitive intratracheal bleomycin models several features of idiopathic pulmonary fibrosis

• Published in: American journal of physiology. Lung cellular and molecular physiology 2010-10, Vol.299 (4), p.L442-L452
• Main Authors: Degryse, Amber L, Tanjore, Harikrishna, Xu, Xiaochuan C, Polosukhin, Vasiliy V, Jones, Brittany R, McMahon, Frank B, Gleaves, Linda A, Blackwell, Timothy S, Lawson, William E
• Format: Article
• Language: English
• Subjects: Animals; Antibiotics; Antibiotics, Antineoplastic - pharmacology; Apoptosis; beta-Galactosidase - metabolism; Bleomycin - pharmacology; Bronchoalveolar Lavage Fluid; Cell Proliferation; Cells, Cultured; Cystic fibrosis; Disease Models, Animal; Epithelial Cells - drug effects; Epithelial Cells - metabolism; Fibroblasts - drug effects; Fibroblasts - metabolism; Fluorescent Antibody Technique; Humans; Idiopathic Pulmonary Fibrosis - chemically induced; Idiopathic Pulmonary Fibrosis - metabolism; Idiopathic Pulmonary Fibrosis - pathology; Immunoenzyme Techniques; Immunohistochemistry; In Situ Nick-End Labeling; Integrases; Intubation, Intratracheal; Lungs; Mesoderm - drug effects; Mesoderm - metabolism; Mice; Mice, Inbred C57BL; Mice, Transgenic; Physiology; Rodents
• ISSN: 1040-0605; 1522-1504
• DOI: 10.1152/ajplung.00026.2010

Single-dose intratracheal bleomycin has been instrumental for understanding fibrotic lung remodeling, but fails to recapitulate several features of idiopathic pulmonary fibrosis (IPF). Since IPF is thought to result from recurrent alveolar injury, we aimed to develop a repetitive bleomycin model that results in lung fibrosis with key characteristics of human disease, including alveolar epithelial cell (AEC) hyperplasia. Wild-type and cell fate reporter mice expressing β-galactosidase in cells of lung epithelial lineage were given intratracheal bleomycin after intubation, and lungs were harvested 2 wk after a single or eighth biweekly dose. Lungs were evaluated for fibrosis and collagen content. Bronchoalveolar lavage (BAL) was performed for cell counts. TUNEL staining and immunohistochemistry were performed for pro-surfactant protein C (pro-SP-C), Clara cell 10 (CC-10), β-galactosidase, S100A4, and α-smooth muscle actin. Lungs from repetitive bleomycin mice had marked fibrosis with prominent AEC hyperplasia, similar to usual interstitial pneumonia (UIP). Compared with single dosing, repetitive bleomycin mice had greater fibrosis by scoring, morphometry, and collagen content; increased TUNEL+ AECs; and reduced inflammatory cells in BAL. Sixty-four percent of pro-SP-C+ cells in areas of fibrosis expressed CC-10 in the repetitive model, suggesting expansion of a bronchoalveolar stem cell-like population. In reporter mice, 50% of S100A4+ lung fibroblasts were derived from epithelial mesenchymal transition compared with 33% in the single-dose model. With repetitive bleomycin, fibrotic remodeling persisted 10 wk after the eighth dose. Repetitive intratracheal bleomycin results in marked lung fibrosis with prominent AEC hyperplasia, features reminiscent of UIP.