Pulmonary Fibrosis

Idiopathic pulmonary fibrosis is a lethal lung disease characterized by the progressive formation of fibroblasts, accumulation of extracellular matrix and decrease in pulmonary function. Current treatments include corticosteroids and other immunosuppressants, but they have limited success. It is believed that antifibrotic agents may have the capability to impede the progression toward chronic pulmonary failure.

Intratracheal Bleomycin-Induced Pulmonary Fibrosis

The bleomycin-induced pulmonary fibrosis model is the standard model of human lung fibrosis. After being anesthetized, animals have a cannula inserted into the trachea and down into the lungs and then bleomycin is slowly infused into the lungs. Animals are evaluated daily for body weight and respiratory status. After animals are sacrificed, lung weight, collagen content and fibrosis scores are determined.

Study Design Table

Model Description Duration Endpoints
Intratracheal bleomycin-induced pulmonary fibrosis Bleomycin introduced directly to lungs via cannula 21 Days Weight and respiratory status; Weight, Collagen content, and Fibrosis score of lungs

 

Fibrosis scores resulting from intratracheal bleomycin exposure
Lung collagen content resulting from intratracheal bleomycin exposure
Wet lung weight resulting from intratracheal bleomycin exposure
Effects of intratracheal Bleomycin dosing on body weight in mice.
Pressure volume curves show improved lung function in mice dosed with Bleomycin (IT) when treated with either Pirfenidone or anti-TGFβ neutralizing antibody.
Lung functional measures are improved in mice dosed with Bleomycin (IT) when treated with either Pirfenidone or anti-TGFβ neutralizing antibody.
Measures of fibrosis are improved in mice dosed with Bleomycin (IT) when treated with either Pirfenidone or anti-TGFβ neutralizing antibody.
(Left) Bleomycin-induced fibrosis: Ashcroft score = 6 (4x Magnification) Majority of space is effaced by fibrosis (bound by arrows) with secondary nodules of fibrosis (dashed arrows). (Right) Bleomycin-induced fibrosis: Ashcroft score = 6 (40x Magnification) Virtually entire field replaced by fibrosis with only a few scattered alveoli remaining visible (asterisk).
Intravenous Bleomycin-Induced Pulmonary Fibrosis

The bleomycin-induced pulmonary fibrosis model is the standard model of human lung fibrosis. Animals are given intravenous (i.v.) dosing with bleomycin for days 0-4 and are evaluated daily for body weight and respiratory status. After animals are sacrificed, lung weight, collagen content and fibrosis scores are determined.

Study Design Table

Model Description Duration Endpoints
Intravenous bleomycin-induced pulmonary fibrosis Bleomycin introduced intravenously for 5 days 42 Days Weight and respiratory status; Weight, Collagen content, and Fibrosis score of lungs

 

Fibrosis scores resulting from intravenous bleomycin exposure
Lung collagen content resulting from intravenous bleomycin exposure
Wet lung weight resulting from intratracheal bleomycin exposure
Effects of intravenous Bleomycin dosing on body weight in mice.
Bleomycin-induced fibrosis: (Left) Ashcroft score = 5 (4x Magnification) Arrows show areas of subpleural fibrosis that extend into pulmonary parenchyma and effacing ~30% of section. (Right) Bleomycin-induced fibrosis: Ashcroft score = 5 (40x Magnification) Alveolar walls thickened by fibrosis (most visible at arrows) admixed with scattered inflammatory cells
Human in vitro model of TGFβ-induced Fibrosis in Normal Human Lung Fibroblasts (NHLF)

TGFβ is added to confluent NHLF for 48 hours.  Supernatants and cell lysates are collected for endpoint analysis.  Protein levels of Procollagen type 1-C peptide (PIP) and Plasminogen activator Inhibitor-1 (PAI-1) are determined to evaluate progression of fibrosis.  Additionally, alpha smooth muscle actin (αSMA) is measured to indicate myofibroblast formation. 

TGFβ stimulation significantly induced protein levels of PIP and PAI-1 in cell supernatants indicating activation of pathways for production of collagen and fibronectin respectively. TGFβ stimulation significantly induced αSMA protein levels in cell lysates indicating presence of myofibroblasts. Treatment of cells with Relaxin reduces levels of PIP and similar effects were observed on PAI-1 and αSMA levels (data not shown).
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