Various animal models of pulmonary fibrosis have been established using bleomycin to clarify the pathogenesis of pulmonary fibrosis and find new drug targets. However, most pulmonary fibrosis models targeting lung tissue have uneven drug administration. Here, we propose a model of uniform pulmonary fibrosis induced by nasal bleomycin nebulization.
Pulmonary fibrosis is characteristic of several human lung diseases that arise from various causes. Given that treatment options are fairly limited, mouse models continue to be an important tool for developing new anti-fibrotic strategies. In this study, intrapulmonary administration of bleomycin (BLM) is carried out by nasal nebulization to create a mouse model of pulmonary fibrosis that closely mimics clinical disease characteristics. C57BL/6 mice received BLM (7 U/mL, 30 min/day) by nasal nebulization for 3 consecutive days and were sacrificed on day 9, 16, or 23 to observe inflammatory and fibrotic changes in lung tissue. Nasal aerosolized BLM directly targeted the lungs, resulting in widespread and uniform lung inflammation and fibrosis. Thus, we successfully generated an experimental mouse model of typical human pulmonary fibrosis. This method could easily be used to study the effects of the administration of various nasal aerosols on lung pathophysiology and validate new anti-inflammatory and anti-fibrotic treatments.
Pulmonary fibrosis is a progressive disease process in which excessive deposition of extracellular matrix components, primarily type I collagen, in the interstitium of the lungs leads to impaired lung function1. The pathophysiology of pulmonary fibrosis is complex, and treatment options are currently quite limited. Mouse models remain an important tool to study the pathogenic mechanisms that contribute to the emergence and progression of the disease, as well as new strategies for drug development.
A variety of animal models of pulmonary fibrosis rely on intratracheal instillation of BLM2,3,4,5,6,7,8,9,10,11,12. However, the distribution of fibrotic changes that BLM causes in the lungs is not uniform, and the animals are at risk of asphyxiation during the instillation process. Although intraperitoneal injection of BLM induces relatively uniform fibrotic changes in the lung, it requires multiple doses because of insufficient drug targeting. Intratracheal aerosol administration via a laryngoscope does not require tracheotomy or puncture, and the resulting drug distribution within the lung is optimal. However, the aerosolized particles are large (5-40 µm), and thus cannot reach the subpleural area of the lung tissue.
In this study, intrapulmonary administration of BLM is carried out by nasal nebulization. During nebulization, the mice breathed spontaneously and inhaled the drug particles. The aerosolized particles were 2.5-4 µm in size, which enabled them not only to distribute evenly throughout the lung but also to reach the subpleural area. Under low magnification, the most significant lung histopathological features of patients with idiopathic pulmonary fibrosis (IPF) are the varying severity of lesions, inconsistent distribution, alternating distribution of different phase lesions, and the presence of interstitial inflammation, fibrotic lesions, and honeycomb lung changes, alternating with normal lung tissue. These pathological changes predominantly involve the peripheral subpleural parenchyma or lobular septum around the bronchioli. Thus, given that this approach enables BLM particles to reach the subpleural area of the lungs, this model closely simulates the clinical characteristics of the disease in humans.
Intratracheal injection of bleomycin results in an acute inflammatory and fibrotic response in both lungs and can be considered an effective approach to establish an experimental mouse model of human interstitial lung disease. Intratracheal administration is the most commonly used route of administration2,3,4,5,6,7,</sup…
The authors have nothing to disclose.
This work was supported by the National Natural Science Foundation of China (No. 92068108).
bleomycin | Bioway/Nippon Kayaku Co Ltd | DP721 | Fibrosis model drugs |
0.9% saline for injection | Baxter Healthcare(Tianjin)Co.,Ltd. | Bleomycin preparation | |
1 mL syringe | BD | 300481 | Anesthetize animals |
10% neutral formalin buffer | TechaLab Biotech Company | Fix lung tissue | |
15 mL centrifuge tube | corning | 430790 | Prepare for anesthesia |
20 °C refrigerator | New-fly group | BCD-213K | Store drugs |
4 °C refrigerator | New-fly group | BCD-213K | Store drugs |
Adobe illustrator cc2020 | Adobe | Process images | |
blue back liquid | Beijing Chemical Works | tissue staining | |
clean bench | Suzhou Sujie Purifying Equipment Co.,Ltd. | Bleomycin preparation | |
differentiation fluid | Beijing Chemical Works | tissue staining | |
Electronic balance | METTLER TOLEDO | AA-160 | Prepare for anesthesia |
eosin stain | Beijing Yili Fine Chemicals Co,Ltd. | tissue staining | |
Heating pad | HIDOM | Mice incubation | |
hematoxylin stain | Beijing Yili Fine Chemicals Co,Ltd. | tissue staining | |
phosphate buffered saline (PBS) buffer | Hyclone | SH30256.01 | Clean lung tissue |
Photoshop drawing software | Adobe | Process images | |
SCIREQ INEXPOSE | EMKA Biotech Beijing Co.,Ltd. | Atomizing device | |
Upright fluorescence microscope | Olympus | BX53 | Observe the slice |
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