Abstract Rationale There is increasing evidence for senescent cells playing an important role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). The present study aimed to evaluate molecular signatures of pulmonary senescence in the single and repetitive bleomycin (BLEO)-induced and spirometry-confirmed mouse model of IPF. Methods Mice received either a single intratracheal instillation of BLEO (n = 14) or a repetitive regimen involving bi-weekly BLEO instillations over 4 weeks (n = 30). Two weeks after the last BLEO dose, mice were assigned as baseline (n = 13) or repetitive BLEO-IPF mice (terminated 8 weeks after baseline, n = 17). Saline-treated mice served as healthy controls (CTRL, n = 10 per model). Terminal pulmonary endpoints included spirometry, hydroxyproline content, Ashcroft fibrosis score, quantitative histological markers of inflammation (CD3, CD20, CD45, Gal-3), fibrogenesis (α-SMA), fibrosis (PSR, Col1a1, Col3) as well as histological (p16+αSMA+, p21+) and transcriptome signatures of cellular senescence. Results Both the single and repetitive BLEO-IPF mouse models reproduced functional, biochemical, and histological features of IPF. Pulmonary cellular senescence was evident from a markedly increased %-area of p21+ staining and a higher proportion of p16+ myofibroblasts (α-SMA+) in both models. Notably, in the repetitive BLEO-IPF model, the number of p16+ myofibroblasts further increased, whereas %-area of p21+ declined relative to baseline, suggesting a persistent senescent myofibroblast phenotype that may contribute to sustained fibrotic remodelling. RNA sequencing revealed significant upregulation of key genes associated with the senescence-associated secretory phenotype (SASP) and DNA damage responses in both models, overall aligning with molecular profiles observed in IPF patients. Conclusions The single and repetitive BLEO-IPF mouse models demonstrated impaired pulmonary function and lung fibrosis accompanied by an evolving cellular senescence phenotype, supporting their suitability for evaluating the efficacy of candidate senotherapeutics in IPF. This abstract is funded by: None
Petersen et al. (Fri,) studied this question.