Retinoic acid induced repair in the lung of adult hyperoxic mice, reducing transforming growth factor-beta 1 (TGF-beta 1) mediated abnormal alterations

The aim of the study was to determine the effects of retinoic acid on lung alveolar repair in adult hyperoxic mice and to investigate the relationship between TGF-beta 1 and retinoic acid during the repair processes. Adult mice were divided into 4 groups. Two groups were given daily intraperitoneal injections of peanut oil/dimethylsulfOxide mixture and retinoic acid (50 mg/kg body weight, 50 mu l of volume) dissolved in peanut oil/dimethylsulfoxide mixture for 12 days with a 2-day break on days 6 and 7. Following hyperoxia (100% oxygen) for 72 h the remaining two groups were treated in the same manner as already described: peanut oil/dimethylsulfoxide mixture and retinoic acid. Lung structure was investigated by light microscopy. TGF-beta 1 and Smad protein expressions in the lung were assayed by biochemical methods. Hyperoxic mice exhibited damage to the alveolar walls, increased cell proliferation and induced Smad3/TGF-beta 1 signaling. Smad2 and phospho-Smad2 protein expressions were unchanged in all groups. Retinoic acid administration improved the degenerative alterations caused by hyperoxia and helped in alveolar repair. This positive effect of retinoic acid resulted from the inhibition of Smad3/TGF-beta 1 signaling via reduced Smad4 mRNA and increased Smad7 protein expression. Retinoic acid also induced alveolarization and restricted Smad3/TGF-beta 1 signaling by decreasing Smad4 mRNA in healthy mice. Thus, retinoic acid helped repair Smad3/TGF-beta 1-induced lung damage in hyperoxic mice. (C) 2014 Elsevier GmbH. All rights reserved

Dasatinib attenuated bleomycin-induced pulmonary fibrosis in mice

Anti-fibrotic effect of dasatinib, a platelet-derived growth factor receptor (PDGFR) and Src-kinase inhibitor, was tested on pulmonary fibrosis (PF). Adult mice were divided into four groups: mice dissected 21d after the bleomycin (BLM) instillation (0.08mg/kg in 200 mu l) (I) and their controls (II), and mice treated with dasatinib (8mg/kg in 100 mu l, gavage) for one week 14d after BLM instillation and dissected 21d after instillation (III) and their controls (IV). The fibrosis score and the levels of fibrotic markers were analyzed in lungs. BLM treatment-induced cell proliferation and increased the levels of collagen-1, alpha smooth muscle actin, phospho (p)-PDGFR-alpha, p-Src, p-extracellular signal-regulated kinases1/2 and p-cytoplasmic-Abelson-kinase (c-Abl) in lungs, and down-regulated PTEN expression. Dasatinib reversed these alterations in the fibrotic lung. Dasatinib limited myofibroblast activation and collagen-1 accumulation by the inhibition of PDGFR-alpha, and Src and c-Abl activations. In conclusion, dasatinib may be a novel tyrosine and Src-kinase inhibitor for PF regression in mice

Gastrin-releasing peptide induces fibrotic response in MRC5s and proliferation in A549s

Idiopathic pulmonary fibrosis (IPF) is a complex lung disease, whose build-up scar tissue is induced by severalmolecules. Gastrin-releasing peptide (GRP) is released from pulmonary neuroendocrine cells, alveolar macrophages,and some nerve endings in the lung. A possible role of GRP in IPF is unclear. We aimed to investigate the fibroticresponse to GRP, at the cellular level in MRC5 and A549 cell lines. The proliferative and fibrotic effects of GRP onthese cells were evaluated by using BrdU, immunoblotting, immunofluorescence and qRT-PCR for moleculesassociated with myofibroblast differentiation, TGF-β and Wnt signalling. All doses of GRP increased the amount ofBrdU incorporation in A549 cells. In contrast, the amount of BrdU increased in MRC5 cells in the first 24 h, thoughprogressively decreased by 72 h. GRP did not stimulate epithelial-mesenchymal transition in A549 cells, rather, itstimulated the differentiation of MRC5 cells into myofibroblasts. Furthermore, GRP induced gene and proteinexpressions of p-Smad2/3 and Smad4, and reduced the levels of Smad7 in MRC5 cells. In addition, GRP decreasedWnt5a protein levels and stimulated β-catenin activation by increasing Wnt4, Wnt7a and β-catenin protein levels.GRP caused myofibroblast differentiation by inducing TGF-βand Wnt pathways via paracrine and autocrinesignalling in MRC5 cells. In conclusion, GRP may lead to pulmonary fibrosis due to its proliferative and fibroticeffects on lung fibroblasts. The abrogation of GRP-mediated signal activation might be considered as a treatmentmodality for fibrotic lung diseases