Abstract
BackgroundIdiopathic pulmonary fibrosis (IPF) is an incurable lung disease with a poor prognosis. Fibroblasts and myofibroblasts are the key cells in the fibrotic process. Recently two drugs, pirfenidone and nintedanib, were approved for clinical use as they are able to slow down the disease progression. The mechanisms by which these two drugs act in in vitro cell systems are not known. The aim of this study was therefore to examine the effects of pirfenidone and nintedanib on fibroblasts and myofibroblasts structure and function established from patients with or without IPF.MethodsStromal cells were collected and cultured from control lung (n = 4) or IPF (n = 7). The cells were treated with pirfenidone and/or nintedanib and the effect of treatment was evaluated by measuring cell proliferation, alpha smooth muscle actin (α-SMA) and fibronectin expression by Western analysis and/or immunoelectron microscopy, ultrastructural properties by transmission electron microscopy and functional properties by collagen gel contraction and invasion assays.ResultsBoth pirfenidone and nintedanib reduced in vitro proliferation of fibroblastic cells in a dose dependent manner. The number of cells from control lung was reduced to 47 % (p = 0.04) and of IPF cells to 42 % (p = 0.04) by 1 mM pirfenidone and correspondingly to 67 % (p = 0.04) and 68 % (p = 0.04), by 1 μM nintedanib. If both drugs were used together, a further reduced proliferation was observed. Both pirfenidone and nintedanib were able to reduce the amount of α-SMA and the myofibroblastic appearance although the level of reduction was cell line dependent. In functional assays, the effect of both drugs was also variable.ConclusionsWe conclude that the ultrastructure and function of fibroblasts and myofibroblasts are affected by pirfenidone and nintedanib. Combination of the drugs reduced cell proliferation more than either of them individually. Human lung derived cell culture systems represent a potential platform for screening and testing drugs for fibrotic diseases.Electronic supplementary materialThe online version of this article (doi:10.1186/s12931-016-0328-5) contains supplementary material, which is available to authorized users.
Highlights
Idiopathic pulmonary fibrosis (IPF) is an incurable lung disease with a poor prognosis
Pirfenidone and nintedanib reduced the proliferation of both control lung and IPF derived fibroblastic cells Three stromal cell lines derived from control lung and three cell lines derived from IPF were used for proliferation assay
The proliferation of control cells was reduced to 47 % (p = 0.04) and that of IPF cells to 42 % (p = 0.04) by 1 mM pirfenidone and to % (p = 0.04) and % (p = 0.04), respectively, by 1 μM nintedanib (KW test)
Summary
Idiopathic pulmonary fibrosis (IPF) is an incurable lung disease with a poor prognosis. Pirfenidone and nintedanib, were approved for clinical use as they are able to slow down the disease progression. The aim of this study was to examine the effects of pirfenidone and nintedanib on fibroblasts and myofibroblasts structure and function established from patients with or without IPF. The pathogenesis of IPF is still unclear, marked progress has been made recently both in clarifying disease mechanisms and in developing new therapeutic agents. No pharmacological therapy is able to cure the disease but two drugs, pirfenidone and nintedanib i.e. BIBF1120, have been shown to slow the progression of the disease [2,3,4] whereas the previously used N-acetylcysteine had no effect on the outcome [5, 6]. The extent of expression of alpha smooth muscle actin (α-SMA), as a marker of myofibroblasts, in the lungs of IPFpatients, has been shown to be negatively associated with patient survival [10]
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