Pulmonary fibrosis distal airway epithelia are dynamically and structurally dysfunctional

The airway epithelium serves as the interface between the host and external environment. In many chronic lung diseases, the airway is the site of substantial remodeling after injury. While, idiopathic pulmonary fibrosis (IPF) has traditionally been considered a disease of the alveolus and lung matrix, the dominant environmental (cigarette smoking) and genetic (gain of function MUC5B promoter variant) risk factor primarily affect the distal airway epithelium. Moreover, airway-specific pathogenic features of IPF include bronchiolization of the distal airspace with abnormal airway cell-types and honeycomb cystic terminal airway-like structures with concurrent loss of terminal bronchioles in regions of minimal fibrosis. However, the pathogenic role of the airway epithelium in IPF is unknown. Combining biophysical, genetic, and signaling analyses of primary airway epithelial cells, we demonstrate that healthy and IPF airway epithelia are biophysically distinct, identifying pathologic activation of the ERBB-YAP axis as a specific and modifiable driver of prolongation of the unjammed-to-jammed transition in IPF epithelia. Furthermore, we demonstrate that this biophysical state and signaling axis correlates with epithelial-driven activation of the underlying mesenchyme. Our data illustrate the active mechanisms regulating airway epithelial-driven fibrosis and identify targets to modulate disease progression. Environmental and genetic risk factors affect the distal airway epithelium in idiopatic pulmonary fibrosis (IPF) but the role of the epithelium in IPF remains unclear. Here the authors show that pathologic activation of the ERBB-YAP axis induces dynamic and structural dysfunction in the distal airway epithelium eliciting a pro-fibrotic phenotype in mesenchymal cells.

Automated summary

Environmental and genetic risk factors affect the distal airway epithelium in idiopathic pulmonary fibrosis (IPF), but the specific role of the epithelium in the disease remains unclear. The study demonstrates that pathologic activation of the ERBB-YAP axis induces dysfunction in distal airway epithelium, leading to a pro-fibrotic phenotype in mesenchymal cells.