Abstract
Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease with limited therapeutic options. KCa3.1 ion channels play a critical role in TGFβ1-dependent pro-fibrotic responses in human lung myofibroblasts. We aimed to develop a human lung parenchymal model of fibrogenesis and test the efficacy of the selective KCa3.1 blocker senicapoc. 2 mm3 pieces of human lung parenchyma were cultured for 7 days in DMEM ± TGFβ1 (10 ng/ml) and pro-fibrotic pathways examined by RT-PCR, immunohistochemistry and collagen secretion. Following 7 days of culture with TGFβ1, 41 IPF- and fibrosis-associated genes were significantly upregulated. Immunohistochemical staining demonstrated increased expression of ECM proteins and fibroblast-specific protein after TGFβ1-stimulation. Collagen secretion was significantly increased following TGFβ1-stimulation. These pro-fibrotic responses were attenuated by senicapoc, but not by dexamethasone. This 7 day ex vivo model of human lung fibrogenesis recapitulates pro-fibrotic events evident in IPF and is sensitive to KCa3.1 channel inhibition. By maintaining the complex cell-cell and cell-matrix interactions of human tissue, and removing cross-species heterogeneity, this model may better predict drug efficacy in clinical trials and accelerate drug development in IPF. KCa3.1 channels are a promising target for the treatment of IPF.
Highlights
Idiopathic pulmonary fibrosis (IPF) is a common, progressive and invariably fatal lung disease[1,2,3]
The causes of IPF remain unresolved, but evidence favours alveolar epithelial cell injury as the initial event which triggers the release of TGFβ18, a central pro-fibrotic growth factor driving lung parenchymal fibrosis[9,10]
When we treated the tissue with TGFβ1 (10 ng/ml) for 7 days and compared this with control day 7 tissue, we observed significant increases in the expression of the extracellular matrix (ECM) molecules collagens type I and III, α-smooth muscle actin (αSMA) and the numbers of fibroblast surface protein (FSP)+ fibroblast-like cells present in the tissue (Fig. 3A–E)
Summary
Idiopathic pulmonary fibrosis (IPF) is a common, progressive and invariably fatal lung disease[1,2,3]. The mechanism of action of pirfenidone is poorly understood, while nintedanib is an inhibitor of PDGF/VEGF/FGF receptor tyrosine kinases[6,7]. Both drugs are of limited efficacy[6,7] and often poorly tolerated. The causes of IPF remain unresolved, but evidence favours alveolar epithelial cell injury as the initial event which triggers the release of TGFβ18, a central pro-fibrotic growth factor driving lung parenchymal fibrosis[9,10]. Major discrepancies between drug effects in the bleomycin mouse model of lung fibrosis and human clinical trials for IPF are evident[15]. Correspondence and requests for materials should be addressed to K.M.R. (email: kmr11@ le.ac.uk) www.nature.com/scientificreports/
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