Background Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease characterised by exuberant tissue remodelling and associated with high unmet medical needs. Outcomes are even worse when IPF results in secondary pulmonary hypertension (PH). Importantly, exaggerated resistance to cell death, excessive proliferation and enhanced synthetic capacity are key endophenotypes of both fibroblasts and pulmonary artery smooth muscle cells, suggesting shared molecular pathways. Under persistent injury, sustained activation of the DNA damage response (DDR) is integral to the preservation of cells survival and their capacity to proliferate. Checkpoint kinases 1 and 2 (CHK1/2) are key components of the DDR. The objective of this study was to assess the role of CHK1/2 in the development and progression of IPF and IPF+PH.
Methods and results Increased expression of DNA damage markers and CHK1/2 were observed in lungs, remodelled pulmonary arteries and isolated fibroblasts from IPF patients and animal models. Blockade of CHK1/2 expression or activity-induced DNA damage overload and reverted the apoptosis-resistant and fibroproliferative phenotype of disease cells. Moreover, inhibition of CHK1/2 was sufficient to interfere with transforming growth factor beta 1-mediated fibroblast activation. Importantly, pharmacological inhibition of CHK1/2 using LY2606368 attenuated fibrosis and pulmonary vascular remodelling leading to improvement in respiratory mechanics and haemodynamic parameters in two animal models mimicking IPF and IPF+PH.
Conclusion This study identifies CHK1/2 as key regulators of lung fibrosis and provides a proof of principle for CHK1/2 inhibition as a potential novel therapeutic option for IPF and IPF+PH.
- idiopathic pulmonary fibrosis
- primary pulmonary hypertension
Data availability statement
All data relevant to the study are included in the article or uploaded as supplementary information. All data relevant to the study are included in the article or uploaded as supplementary information.
Statistics from Altmetric.com
SP and OB are joint senior authors.
SP and OB contributed equally.
Contributors W-HW, SB, SP and OB conceived and designed the research study. W-HW, TS, VT, YG, CR, AB, GV, JO, ET, VN, MO, SB-B and SM were responsible for acquiring, analysing and interpreting the data. PF provided human lung tissues. FP and RP revised the manuscript for important intellectual content. W-HW, SP, SB and OB drafted the manuscript. OB, SP and SB revised the manuscript.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.