Pirfenidone attenuates lung fibrotic fibroblast responses to transforming growth factor-\u03b21

Jin Jin,Kotaro Kadoya,Yuzo Kodama,Moulid Hidayat,Kazuhisa Takahashi,Yukiko Namba,Miniwan Tulafu,Hideya Kitamura,Shinichi Sasaki,Norikazu Kitamura,Kumi Nagahama,Kazuho Ikeo,Moe Iwai,Takashi Ogura,Junko Watanabe,Shigeru Tominaga,Takahiro Okabe,Shinsaku Togo

doi:10.1186/s12931-019-1093-z

Abstract

BackgroundPirfenidone, an antifibrotic agent used for the treatment of idiopathic pulmonary fibrosis (IPF), functions by inhibiting myofibroblast differentiation, which is involved in transforming growth factor (TGF)-β1-induced IPF pathogenesis. However, unlike normal lung fibroblasts, the relationship between pirfenidone responses of TGF-β1-induced human fibrotic lung fibroblasts and lung fibrosis has not been elucidated.MethodsThe effects of pirfenidone were evaluated in lung fibroblasts isolated from fibrotic human lung tissues after TGF-β1 exposure. The ability of two new pharmacological targets of pirfenidone, collagen triple helix repeat containing protein 1(CTHRC1) and four-and-a-half LIM domain protein 2 (FHL2), to mediate contraction of collagen gels and migration toward fibronectin were assessed in vitro.ResultsCompared to control lung fibroblasts, pirfenidone significantly restored TGF-β1-stimulated fibroblast-mediated collagen gel contraction, migration, and CTHRC1 release in lung fibrotic fibroblasts. Furthermore, pirfenidone attenuated TGF-β1- and CTHRC1-induced fibroblast activity, upregulation of bone morphogenic protein-4(BMP-4)/Gremlin1, and downregulation of α-smooth muscle actin, fibronectin, and FHL2, similar to that observed post-CTHRC1 inhibition. In contrast, FHL2 inhibition suppressed migration and fibronectin expression, but did not downregulate CTHRC1.ConclusionsOverall, pirfenidone suppressed fibrotic fibroblast-mediated fibrotic processes via inverse regulation of CTHRC1-induced lung fibroblast activity. Thus, CTHRC1 can be used for predicting pirfenidone response and developing new therapeutic targets for lung fibrosis.

Highlights

Pirfenidone, an antifibrotic agent used for the treatment of idiopathic pulmonary fibrosis (IPF), functions by inhibiting myofibroblast differentiation, which is involved in transforming growth factor (TGF)-β1induced IPF pathogenesis
We evaluated the effects pirfenidone on TGF-β1-mediated contraction of extracellular matrix (ECM) and migration of lung fibroblasts isolated from patients with lung fibrosis toward fibronectin and compared them with those of normal lung fibroblasts for understanding the mechanisms underlying lung fibroblast-dependent antifibrotic effects of pirfenidone
We demonstrated that the magnitude of pirfenidone-dependent suppression of TGF-β1-induced gel contraction and migration was positively related to serum surfactant protein (SP)-D levels and negatively related to serum Krebs von den Lungen (KL)-6 levels respectively, but was not related to any other clinical parameters, including histological pattern and lung function (%vital capacity (VC), %forced vital capacity (FVC), and %Percent diffusing capacity of carbon monoxide (DLCO))

Summary

Introduction

Pirfenidone, an antifibrotic agent used for the treatment of idiopathic pulmonary fibrosis (IPF), functions by inhibiting myofibroblast differentiation, which is involved in transforming growth factor (TGF)-β1induced IPF pathogenesis. Accumulation of activated lung myofibroblasts and excessive deposition of extracellular matrix (ECM) produced by these cells result in lung tissue contraction, as has been observed in fibrotic lung tissues [1]. This can disrupt lung function, and inhibition of fibrotic processes may alter the progression of lung fibrosis-related diseases. TGF-β1, a key mediator of normal tissue repair [6], strongly stimulates mesenchymal cells to produce large amounts of ECM, including fibronectin and collagen, resulting in the development of fibrosis [4]. We demonstrated that fibrotic fibroblasts, characterized by high response to TGF-β1, stimulated TGF-β1-induced contraction of collagen gels, fibroblast migration, and expression of α-smooth muscle actin and fibronectin. These observations suggest that fibrotic fibroblasts respond to fibroblast-mediated fibrotic processes and anti-fibrotic compounds

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