Long intergenic non-coding RNAs regulate human lung fibroblast function: Implications for idiopathic pulmonary fibrosis

Marina R Hadjicharalambous,Benoit T Roux,Eszter Csomor,Carol A Feghali-Bostwick,Deborah L Clarke,Lynne A Murray,Mark A Lindsay

doi:10.1038/s41598-019-42292-w

Abstract

Phenotypic changes in lung fibroblasts are believed to contribute to the development of Idiopathic Pulmonary Fibrosis (IPF), a progressive and fatal lung disease. Long intergenic non-coding RNAs (lincRNAs) have been identified as novel regulators of gene expression and protein activity. In non-stimulated cells, we observed reduced proliferation and inflammation but no difference in the fibrotic response of IPF fibroblasts. These functional changes in non-stimulated cells were associated with changes in the expression of the histone marks, H3K4me1, H3K4me3 and H3K27ac indicating a possible involvement of epigenetics. Following activation with TGF-β1 and IL-1β, we demonstrated an increased fibrotic but reduced inflammatory response in IPF fibroblasts. There was no significant difference in proliferation following PDGF exposure. The lincRNAs, LINC00960 and LINC01140 were upregulated in IPF fibroblasts. Knockdown studies showed that LINC00960 and LINC01140 were positive regulators of proliferation in both control and IPF fibroblasts but had no effect upon the fibrotic response. Knockdown of LINC01140 but not LINC00960 increased the inflammatory response, which was greater in IPF compared to control fibroblasts. Overall, these studies demonstrate for the first time that lincRNAs are important regulators of proliferation and inflammation in human lung fibroblasts and that these might mediate the reduced inflammatory response observed in IPF-derived fibroblasts.

Highlights

Idiopathic pulmonary fibrosis (IPF) is a fatal progressive chronic disease characterised by scar tissue accumulation in the lungs leading to impaired gas exchange and restricted ventilation[1,2,3]
TGF-β1-induced activation of lung fibroblasts triggers the expression of PAI-1, a protein known as an important regulator of fibrinolysis and wound healing and implicated in the process of fibrosis[28]
Following exposure to TGF-β1, we observed a significant increase in PAI-1 release from both control and Idiopathic Pulmonary Fibrosis (IPF) fibroblasts (Fig. 6B), the magnitude of this response was smaller than that observed in non-transfected cells (Fig. 1)

Summary

Introduction

Idiopathic pulmonary fibrosis (IPF) is a fatal progressive chronic disease characterised by scar tissue accumulation in the lungs leading to impaired gas exchange and restricted ventilation[1,2,3]. The etiology and pathogenesis of the disease are still unclear, recent research has indicated that persistent epithelial injury and/or exposure to pathogens, leads to the secretion of fibrotic, proliferative and inflammatory mediators such as TGF-β14, PDGF5 and IL-1β6 These are thought to act upon surrounding fibroblasts, to induce an exaggerated wound healing response that contributes towards the development and progression of IPF1. We have demonstrated differences in the functional responses between fibroblasts derived from control and IPF lungs These are reflected by changes in H3K4me[1], a histone epigenetic marker of primed genes and enhancers[26,27] and up-regulation of two lincRNAs, LINC00960 and LINC01140 in IPF fibroblasts. Given that LINC01140 is upregulated in both IPF fibroblasts and lung biopsies, our data suggest that LINC01140 mediates the reduced inflammatory response in IPF fibroblasts

Methods

Results

Conclusion