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

Ozgecan Kayalar,Hurrem Gul Ongen,Fusun Oztay

doi:10.1186/s12964-020-00585-y

Ozgecan Kayalar, Hurrem Gul Ongen + Show 1 more

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https://doi.org/10.1186/s12964-020-00585-y

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Abstract

Idiopathic pulmonary fibrosis (IPF) is a complex lung disease, whose build-up scar tissue is induced by several molecules. 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 fibrotic response to GRP, at the cellular level in MRC5 and A549 cell lines. The proliferative and fibrotic effects of GRP on these cells were evaluated by using BrdU, immunoblotting, immunofluorescence and qRT-PCR for molecules associated with myofibroblast differentiation, TGF-β and Wnt signalling. All doses of GRP increased the amount of BrdU incorporation in A549 cells. In contrast, the amount of BrdU increased in MRC5 cells in the first 24 h, though progressively decreased by 72 h. GRP did not stimulate epithelial-mesenchymal transition in A549 cells, rather, it stimulated the differentiation of MRC5 cells into myofibroblasts. Furthermore, GRP induced gene and protein expressions of p-Smad2/3 and Smad4, and reduced the levels of Smad7 in MRC5 cells. In addition, GRP decreased Wnt5a 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 autocrine signalling in MRC5 cells. In conclusion, GRP may lead to pulmonary fibrosis due to its proliferative and fibrotic effects on lung fibroblasts. The abrogation of GRP-mediated signal activation might be considered as a treatment modality for fibrotic lung diseases.BiWGXPLUnt4V7uQDSjX_9sVideo .Graphical abstract

Highlights

Several growth factors, cytokines, and chemokines released from pulmonary epithelial, mesenchymal and inflammatory cells contribute to the generation of pulmonary fibrosis, by regulating the proliferation and differentiation of fibroblast/myofibroblast in addition to the production, secretion, and accumulation of extracellular matrix (ECM) components [1, 2]
Proliferative responses of Adenocarcinomic human alveolar epithelial cell line (A549) and Human lung fibroblast cell line (MRC5) cells treated with Gastrin-releasing peptide (GRP) In A549 cells stimulated with a 10− 5 M dose of GRP, BrdU level was not altered at 24 h, 48 h and 72 h compared with their controls
The present study provided the first data regarding the crosstalk between GRP, Transforming growth factor-beta (TGF-β) and Wnt signalling pathways and their active role in the differentiation of MRC5 cells into myofibroblasts and in the production of ECM elements

Summary

Introduction

Cytokines, and chemokines released from pulmonary epithelial, mesenchymal and inflammatory cells contribute to the generation of pulmonary fibrosis, by regulating the proliferation and differentiation of fibroblast/myofibroblast in addition to the production, secretion, and accumulation of extracellular matrix (ECM) components [1, 2]. There are Pulmonary neuroendocrine cells (PNECs) are found in the airway epithelium of lungs [3, 4]. They first differentiate during lung development [5]. PNECs are localized solitary or in clusters among the other epithelial cells, such as ciliated cells, goblet cells and pneumocytes They are capable of synthesizing and releasing serotonin and peptide hormones such as bombesin, substance P, cholecystokinin, calcitonin and somatostatin regulating the biology of target cells in the lung epithelium and parenchyma by paracrine or endocrine pathways [6,7,8]. Kayalar et al Cell Communication and Signaling (2020) 18:96

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