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Structural and functional correlations in a large animal model of bleomycin-induced pulmonary fibrosis.

Organ L, Bacci B, Koumoundouros E, Barcham G, Milne M, Kimpton W, Samuel C, Snibson K - BMC Pulm Med (2015)

Bottom Line: Fibrotic changes persisted up to seven weeks in bleomycin-treated isolated lung segments (Pathology scores: bleomycin12.27 ± 0.07 vs. saline 4.90 ± 1.18, n = 9, p = 0.0003).Localization of bleomycin-induced injury and increased tissue density was confirmed by CT analysis (mean densitometric CT value: bleomycin -698 ± 2.95 Hounsfield units vs. saline -898 ± 2.5 Hounsfield units, p = 0.02).There was also a direct negative correlation between pathology scores and segmental compliance.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Veterinary and Agricultural Science, The University of Melbourne, Parkville, VIC, Australia. lorgan@student.unimelb.edu.au.

ABSTRACT

Background: Idiopathic pulmonary fibrosis (IPF) is a severe and progressive respiratory disease with poor prognosis. Despite the positive outcomes from recent clinical trials, there is still no cure for this disease. Pre-clinical animal models are currently largely limited to small animals which have a number of shortcomings. We have previously shown that fibrosis is induced in isolated sheep lung segments 14 days after bleomycin treatment. This study aimed to determine whether bleomycin-induced fibrosis and associated functional changes persisted over a seven-week period.

Methods: Two separate lung segments in nine sheep received two challenges two weeks apart of either, 3U bleomycin (BLM), or saline (control). Lung function in these segments was assessed by a wedged-bronchoscope procedure after bleomycin treatment. Lung tissue, and an ex vivo CT analysis were used to assess for the persistence of inflammation, fibrosis and collagen content in this model.

Results: Fibrotic changes persisted up to seven weeks in bleomycin-treated isolated lung segments (Pathology scores: bleomycin12.27 ± 0.07 vs. saline 4.90 ± 1.18, n = 9, p = 0.0003). Localization of bleomycin-induced injury and increased tissue density was confirmed by CT analysis (mean densitometric CT value: bleomycin -698 ± 2.95 Hounsfield units vs. saline -898 ± 2.5 Hounsfield units, p = 0.02). Masson's trichrome staining revealed increased connective tissue in bleomycin segments, compared to controls (% blue staining/total field area: 8.5 ± 0.8 vs. 2.1 ± 0.2 %, n = 9, p < 0.0001). bleomycin-treated segments were significantly less compliant from baseline at 7 weeks post treatment compared to control-treated segments (2.05 ± 0.88 vs. 4.97 ± 0.79 mL/cmH20, n = 9, p = 0.002). There was also a direct negative correlation between pathology scores and segmental compliance.

Conclusions: We show that there is a correlation between fibrosis and correspondingly poor lung function which persist for up to seven weeks after bleomycin treatment in this large animal model of pulmonary fibrosis.

No MeSH data available.


Related in: MedlinePlus

Myofibroblasts in bleomycin treated lung. Representative images of αSMA immunostaining seen in: saline-treated control lung segments (a), showing localization predominantly around the interstitial space of alveolar duct (arrowheads). In bleomycin-treated segments (b) αSMA positive cells were observed in remodelled fibrotic alveolar and formed organised bundles (arrows)
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Fig10: Myofibroblasts in bleomycin treated lung. Representative images of αSMA immunostaining seen in: saline-treated control lung segments (a), showing localization predominantly around the interstitial space of alveolar duct (arrowheads). In bleomycin-treated segments (b) αSMA positive cells were observed in remodelled fibrotic alveolar and formed organised bundles (arrows)

Mentions: Myofibroblasts are considered to be a key cell type in driving the persistent and progressive fibrosis in IPF. The presence of contractile myofibroblasts was observed in damaged regions of the interstitial and alveolar space, based on intense positive staining for alpha smooth muscle actin (α-SMA) (Fig. 10b, arrowheads). Thin, spindle like projections of the positive α-SMA stain could also be observed in the remodelled alveolar regions. The staining pattern observed in the saline-treated control was as expected, with positive staining localising predominantly to around the interstitial space of the alveolar duct (Fig. 10a, arrowheads).Fig. 10


Structural and functional correlations in a large animal model of bleomycin-induced pulmonary fibrosis.

Organ L, Bacci B, Koumoundouros E, Barcham G, Milne M, Kimpton W, Samuel C, Snibson K - BMC Pulm Med (2015)

Myofibroblasts in bleomycin treated lung. Representative images of αSMA immunostaining seen in: saline-treated control lung segments (a), showing localization predominantly around the interstitial space of alveolar duct (arrowheads). In bleomycin-treated segments (b) αSMA positive cells were observed in remodelled fibrotic alveolar and formed organised bundles (arrows)
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4521476&req=5

Fig10: Myofibroblasts in bleomycin treated lung. Representative images of αSMA immunostaining seen in: saline-treated control lung segments (a), showing localization predominantly around the interstitial space of alveolar duct (arrowheads). In bleomycin-treated segments (b) αSMA positive cells were observed in remodelled fibrotic alveolar and formed organised bundles (arrows)
Mentions: Myofibroblasts are considered to be a key cell type in driving the persistent and progressive fibrosis in IPF. The presence of contractile myofibroblasts was observed in damaged regions of the interstitial and alveolar space, based on intense positive staining for alpha smooth muscle actin (α-SMA) (Fig. 10b, arrowheads). Thin, spindle like projections of the positive α-SMA stain could also be observed in the remodelled alveolar regions. The staining pattern observed in the saline-treated control was as expected, with positive staining localising predominantly to around the interstitial space of the alveolar duct (Fig. 10a, arrowheads).Fig. 10

Bottom Line: Fibrotic changes persisted up to seven weeks in bleomycin-treated isolated lung segments (Pathology scores: bleomycin12.27 ± 0.07 vs. saline 4.90 ± 1.18, n = 9, p = 0.0003).Localization of bleomycin-induced injury and increased tissue density was confirmed by CT analysis (mean densitometric CT value: bleomycin -698 ± 2.95 Hounsfield units vs. saline -898 ± 2.5 Hounsfield units, p = 0.02).There was also a direct negative correlation between pathology scores and segmental compliance.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Veterinary and Agricultural Science, The University of Melbourne, Parkville, VIC, Australia. lorgan@student.unimelb.edu.au.

ABSTRACT

Background: Idiopathic pulmonary fibrosis (IPF) is a severe and progressive respiratory disease with poor prognosis. Despite the positive outcomes from recent clinical trials, there is still no cure for this disease. Pre-clinical animal models are currently largely limited to small animals which have a number of shortcomings. We have previously shown that fibrosis is induced in isolated sheep lung segments 14 days after bleomycin treatment. This study aimed to determine whether bleomycin-induced fibrosis and associated functional changes persisted over a seven-week period.

Methods: Two separate lung segments in nine sheep received two challenges two weeks apart of either, 3U bleomycin (BLM), or saline (control). Lung function in these segments was assessed by a wedged-bronchoscope procedure after bleomycin treatment. Lung tissue, and an ex vivo CT analysis were used to assess for the persistence of inflammation, fibrosis and collagen content in this model.

Results: Fibrotic changes persisted up to seven weeks in bleomycin-treated isolated lung segments (Pathology scores: bleomycin12.27 ± 0.07 vs. saline 4.90 ± 1.18, n = 9, p = 0.0003). Localization of bleomycin-induced injury and increased tissue density was confirmed by CT analysis (mean densitometric CT value: bleomycin -698 ± 2.95 Hounsfield units vs. saline -898 ± 2.5 Hounsfield units, p = 0.02). Masson's trichrome staining revealed increased connective tissue in bleomycin segments, compared to controls (% blue staining/total field area: 8.5 ± 0.8 vs. 2.1 ± 0.2 %, n = 9, p < 0.0001). bleomycin-treated segments were significantly less compliant from baseline at 7 weeks post treatment compared to control-treated segments (2.05 ± 0.88 vs. 4.97 ± 0.79 mL/cmH20, n = 9, p = 0.002). There was also a direct negative correlation between pathology scores and segmental compliance.

Conclusions: We show that there is a correlation between fibrosis and correspondingly poor lung function which persist for up to seven weeks after bleomycin treatment in this large animal model of pulmonary fibrosis.

No MeSH data available.


Related in: MedlinePlus