Reduction of bleomycin induced lung fibrosis by transforming growth factor β soluble receptor in hamsters

Department of Molecular Biosciences, University of California, Davis, California 95616, USA Biogen Inc, Cambridge, Massachusetts 02142, USA.
Thorax (Impact Factor: 8.29). 10/1999; 54(9):805-12.
Source: PubMed


Transforming growth factor beta (TGF-beta) is a key mediator of collagen synthesis in the development of lung fibrosis. It has previously been shown that the administration of TGF-beta antibody and TGF-beta binding proteoglycan, decorin, reduced bleomycin (BL) induced lung fibrosis in animals. The present study was carried out to investigate whether intratracheal instillation of TGF-beta soluble receptor (TR) would minimise the BL induced lung fibrosis in hamsters.
The effect of a recombinant TR (TGFbetaRII) on the lung collagen accumulation was evaluated in a BL hamster model of pulmonary fibrosis. Animals were divided into four groups and intratracheally injected with saline or BL at 6.5 U/4 ml/kg followed by intratracheal instillation of phosphate buffered saline (PBS) or 4 nmol TR in 0.3 ml twice a week. Twenty days after the first intratracheal instillation the hamsters were killed for bronchoalveolar lavage (BAL) fluid, biochemical, and histopathological analyses.
Treatment of hamsters with TR after intratracheal instillation of BL significantly reduced BL induced lung fibrosis as shown by decreases in the lung hydroxyproline level and prolyl hydroxylase activity, although they were still significantly higher than those of the saline control. Histopathological examination showed a considerable decrease in BL induced fibrotic lesions by TR treatment. However, TR did not prevent the BL induced increases in total cells and protein in the BAL fluid.
These results suggest that TR has antifibrotic potential in vivo and may be useful in the treatment of fibrotic diseases where increased TGF-beta is associated with excess collagen accumulation.

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Available from: Shri N Giri, Jan 14, 2014
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    • "Transforming growth factor-b (TGF-b) is a key cytokine that has been implicated in both epithelial repair and matrix deposition and there is considerable evidence that it plays a central role the pathogenesis of fibrotic diseases. Increased levels of TGF-b have been found in fibroblastic foci of IPF patients (Broekelmann et al. 1991), overexpression of active TGF-b induces fibrosis (Sime et al. 1997), whereas inhibition has prevented fibrosis (Wang et al. 1999) in animal models of disease. Despite the considerable evidence implicating TGF-b in pulmonary fibrosis, no specific inhibitors of TGF-b have emerged as therapies for IPF. "
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    ABSTRACT: Transforming growth factor-β (TGF-β) plays an important role in the development of tissue fibrosis, and molecules inhibiting this pathway are attractive therapeutic targets for fibrotic diseases such as idiopathic pulmonary fibrosis (IPF). Activation of TGF-β is the rate-limiting step in TGF-β bioavailability, and activation by the αVβ6 integrin is important in fibrosis of the lung, liver, and kidney. Activation of TGF-β by αVβ6 requires direct cell–cell contact and measurable release of active TGF-β in extracellular fluid compartments does not reflect tissue specific activation. The aim of this study was to determine the effect of antifibrotic compounds on both total, and specific αVβ6 integrin-mediated TGF-β activity. Using a transformed mink lung cell (TMLC) TGF-β reporter, the effects of potential antifibrotic therapies including an activin-like kinase (Alk5) inhibitor, Dexamethasone, Pirfenidone, N-acetylcysteine (NAC), and BIBF1120 were assessed. Effects due to αVβ6 integrin-mediated TGF-β activity were measured using reporter cells cocultured with cells expressing αVβ6 integrins. These high-throughput studies were validated using a phosphorylated Smad2 Enzyme-Linked Immunosorbent Assay. Alk5 inhibitors are potent inhibitors of TGF-β activity, whereas the novel antifibrotics, Pirfenidone, BIBF1120, and NAC are only moderate inhibitors, and Dexamethasone does not specifically affect TGF-βactivity, but inhibits TGF-β-induced gene expression. None of the current small molecular inhibitors inhibit αVβ6-mediated TGF-β activity. These results demonstrate the potential of this high-throughput assay of αVβ6-specific TGF-β activity and illustrate that currently available antifibrotics have limited effects on αVβ6 integrin-mediated TGF-β activity.
    08/2014; 2(4). DOI:10.1002/prp2.30
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    • "Currently, there are no highly effective agents for the treatment of fibrotic lung diseases. Several studies using anti-TGFβ agents have demonstrated protection from lung fibrosis in disease models [46, 56, 57]. Given the homeostatic roles of TGFβ in inflammation, immune regulation, and carcinogenesis, perhaps a better strategy for TGFβ inhibition would be to specifically target tissue-restricted activators of TGFβ such as the αvβ6 integrin. "
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    ABSTRACT: Interstitial lung disease (ILD) is a commonly encountered complication of systemic sclerosis (SSc) and accounts for a significant proportion of SSc-associated morbidity and mortality. Its pathogenesis remains poorly understood, and therapies that treat SSc ILD are suboptimal, at best. SSc ILD pathogenesis may share some common mechanisms with other fibrotic lung diseases, in which dysregulation of lung epithelium can contribute to pathologic fibrosis via recruitment or in situ generation and activation of fibroblasts. TGFβ, a master regulator of fibrosis, is tightly regulated in the lung by the integrin αvβ6, which is expressed at low levels on healthy alveolar epithelial cells but is highly induced in the setting of lung injury or fibrosis. Here we discuss the biology of αvβ6 and present this integrin as a potentially attractive target for inhibition in the setting of SSc ILD.
    International Journal of Rheumatology 10/2011; 2011(1687-9260):208219. DOI:10.1155/2011/208219
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    • "Transient (7-10 days) overexpression of active TGF-ß1 by adenoviral vector gene transfection in rat lungs induces a severe and progressive fibrosis [7]. Moreover, the blocking of TGF-ß1 in animal models, such as with the use of soluble type II receptors for TGF-ß1 [8], may be effective in reducing fibrosis. "
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    ABSTRACT: ABSTRACT: Interstitial pulmonary fibrosis is characterized by an altered cellular composition of the alveolar region with excessive deposition of collagen. Lung inflammation is also common in pulmonary fibrosis. This study aims to test the inhibition of 5-lipooxygenase (5-LOX) by boswellic acid (BA) extract in an experimental model of pulmonary fibrosis using bleomycin (BL). Boswellic acid extract (1 g/kg) was force-fed to rats seven days prior to administration of BL or gamma irradiation or both. BL (0.15 U/rat) in 25 μl of 0.9% normal saline (NS) or 0.9% NS alone was administered intratracheally. Rats were exposed to two fractionated doses of gamma irradiation (0.5 Gy/dose/week) with a gamma cell-40 (Cesium-137 irradiation units, Canada) during the last two weeks of the experiment. BA was administered during BL or irradiation treatment or both. After the animals were sacrificed, bronchoalveolar lavage was performed; lungs were weighed and processed separately for biochemical and histological studies. In rats treated with BL, levels of transforming growth factor-β1 (TGF-β1) and tumor necrosis factor-α (TNF-α) were significantly elevated (P = 0.05 and P = 0.005). Hydroxyproline was highly and extensively expressed. Immunoreactive compounds were abundantly expressed, represented in the levels of macrophages infiltrate, accumulation of eosinophils and neutrophils in the lung as well as the aggregation of fibroblasts in the fibrotic area. The levels of lipoxygenase enzyme activity were significantly increased (P = 0.005). Antioxidant activities measured in BL-treated rats deteriorated, coupled with the elevation of both levels of plasma lipid peroxide (LP) content and bronchoalveolar lavage lactate dehydrogenase activity. BA-treated rats had reduced number of macrophages, (P = 0.01), neutrophils in bronchoalveolar lavage (P = 0.01) and protein (P = 0.0001). Moreover, the hydroxyproline content was significantly lowered in BA-treated rats (P = 0.005). BA extract inhibited the TGF-ß induced fibrosis (P = 0.01) and 5-LOX activity levels (P = 0.005).Histologically, BA reduced the number of infiltrating cells, ameliorated the destruction of lung architecture and attenuated lung fibrosis. BA attenuates the BL-induced injury response in rats, such as collagen accumulation, airway dysfunction and injury. This study suggests that the blocking of 5-LOX may prevent the progression of fibrosis.
    Chinese Medicine 09/2011; 6(1):36. DOI:10.1186/1749-8546-6-36 · 1.49 Impact Factor
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