NOTCH4 Is a New Player in the Development of Pulmonary Fibrosis

Abstract

Background and objectives: Idiopathic pulmonary fibrosis is a chronic, progressive, incurable lung disease, leading to irreversible lung tissue remodeling. The Notch signaling pathway, essential for lung development, has gained attention for its role in pulmonary fibrosis. While Notch1 and Notch3 have been extensively studied, the involvement of other Notch receptors, especially Notch4, remains less explored. This study aimed to evaluate the impact of Notch4 on lung fibroblast activation and its potential interaction with the transforming growth factor-beta 1 (TGFβ1) signaling. Methods: Primary human lung fibroblasts were transduced with lentivirus containing the intracellular domain of NOTCH4 (N4ICD). Changes in gene expression in transduced cells were assessed using real-time polymerase chain reaction, immunofluorescence staining, and Western blotting. Transcriptomic analysis was also performed on N4ICD-transduced lung fibroblasts. Results: N4ICD overexpression significantly upregulated key fibrotic markers such as ACTA2 and COL1A1. It also induced the TGFβ1 pathway, as evidenced by SMAD2 phosphorylation and elevated TGFβ1 mRNA level. Transcriptomic analysis revealed that N4ICD-induced cells exhibited characteristics of highly invasive myofibroblasts. Conclusions: This study establishes Notch4 as a novel contributor to pulmonary fibrosis, by demonstrating its ability to induce myofibroblast differentiation and interact with the TGFβ1 pathway.