Quantification of Lung Fibrosis in IPF-Like Mouse Model and Pharmacological Response to Treatment by Micro-Computed Tomography

Abstract

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive degenerative lung disease leading to respiratory failure and death. Although anti-fibrotic drugs are now available for treating IPF, their clinical efficacy is limited and lung transplantation remains the only modality to prolong survival of IPF patients. Despite its limitations, the bleomycin (BLM) animal model remains the best characterized experimental tool for studying disease pathogenesis and assessing efficacy of novel potential drugs. In the present study, the effects of oropharyngeal (OA) and intratracheal (IT) administration of BLM were compared in C57BL/6 mice. The development of lung fibrosis was followed in vivo for 28 days after BLM administration by micro-computed tomography and ex vivo by histological analyses (bronchoalveolar lavage, histology in the left lung to stage fibrosis severity and hydroxyproline determination in the right lung). In a separate study, the antifibrotic effect of Nintedanib was investigated after oral administration (60 mg/kg for two weeks) in the OA BLM model. Lung fibrosis severity and duration after BLM OA and IT administration was comparable. However, a more homogeneous distribution of fibrotic lesions among lung lobes was apparent after OA administration. Quantification of fibrosis by micro-CT based on % of poorly aerated tissue revealed that this readout correlated significantly with the standard histological methods in the OA model. These findings were further confirmed in a second study in the OA model, evaluating Nintedanib anti-fibrotic effects. Indeed, compared to the BLM group, Nintedanib inhibited significantly the increase in % of poorly aerated areas (26%) and reduced ex vivo histological lesions and hydroxyproline levels by 49 and 41%, respectively. This study indicated that micro-computed tomography is a valuable in vivo technology for lung fibrosis quantification, which will be very helpful in the future to better evaluate new anti-fibrotic drug candidates.

Evaluation of the long-term effect of polyhexamethylene guanidine phosphate in a rat lung model using conventional chest computed tomography with histopathologic analysis

“…Several studies have reported lung fibrosis in a mouse model using micro-CT [ 32 , 33 ]. However, previous studies using a mouse model quantitively assessed fibrosis as lung density on micro-CT.…”

Alfaxalone and Dexmedetomidine as an Alternative to Gas Anesthesia for Micro-CT Lung Imaging in a Bleomycin-Induced Pulmonary Fibrosis Murine Model

“…Pulmonary fibrosis was induced through the oropharyngeal aspiration (OA) ( 5 ) of 25 μg/mouse bleomycin hydrochloride ( Baxter, BLM ) diluted in 50 μl of saline, while only saline was instilled in vehicle mice. OA procedure was performed at day 0 and day 4 in mice previously anesthetized with 2.5% isoflurane.…”

“…Three weeks after the first OA administration, which represents our common endpoint for lung fibrosis evaluation ( 5 ), mice were randomized into two distinct subgroups (Iso: n = 8 vehicle, n = 11 BLM; Alfa+Dex: n = 12 vehicle, n = 23 BLM).…”

“…Recently, micro-CT imaging has been applied in some animal models of lung diseases including fibrosis and emphysema ( 3 – 5 ), emerging as a powerful tool for the longitudinal assessment of disease progression ( 2 , 3 , 6 ). However, translating CT technique to pre-clinical research has some challenging issues, namely due to the small size of rodents and their rapid respiratory cycle ( 3 , 7 ).…”

SSC-ILD mouse model induced by osmotic minipump delivered bleomycin: effect of Nintedanib

“…Recent results of clinical trials showed that NINT has a beneficial effect reducing the rate of decline in forced vital capacity in patients with ILD associated with SSc over 1-year period, even though no clinical benefits of NINT was observed for other manifestations of SSc 18 , 19 . As regard to animal models, the in vivo efficacy of NINT was explored either on silica-induced lung fibrosis in mice or BLM-induced lung fibrosis in mice and rats 20 – 23 , but it has not yet been tested in the SSc-ILD mouse model using BLM delivered through osmotic minipumps. In the present research, NINT was orally administered for 2 weeks following a therapeutic protocol after acute inflammation phase, starting at day 14 24 , 25 .…”