Introduction Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease with limited treatment options. Most single-cell studies rely on end-stage explant lungs, leaving early disease mechanisms poorly understood. Profiling earlier stages may reveal distinct cellular phenotypes that could be pharmacologically targeted. Recent evidence also implicates airway epithelial cells in IPF disease development and progression. Methods To investigate early-stage IPF mechanisms, we profiled the airway mucosa of newly diagnosed, treatment-naïve patients using single-cell RNA-sequencing of air–liquid interface cultures. We further assessed the transcriptional and functional responses of these cells to antifibrotic drugs (nintedanib and pirfenidone) and a Src kinase inhibitor (saracatinib). Results Profiling of 129 986 transcriptomes identified primed fibroblasts ( PDGFRA + , SPP1 + ), dysregulated basal cells ( TP63 + , KRT5 + , FN1 + ), and proinflammatory airway epithelial cells (SAA, CXCL, CCL). Integrative analyses with explant-derived IPF atlases revealed different basal and fibroblast phenotypes spanning tissue regions and disease stages. In vitro, bronchial epithelial cells stimulated fibroblast proliferation and activation, and fibroblasts remained sensitive to TGF-β. While all three drugs attenuated many IPF signatures, saracatinib most effectively suppressed fibroblast activation and epithelial proliferation. Conclusions This study defines epithelial-mesenchymal programmes of the airway mucosa at an early, diagnostic stage of IPF and demonstrates distinct drug responses at single-cell resolution. By linking airway-derived phenotypes to antifibrotic efficacy, our findings highlight the therapeutic potential of saracatinib and may inform future treatment strategies.
Chua et al. (Wed,) studied this question.