Abstract Rational Chronic Obstructive Pulmonary Disease (COPD) is characterized by progressive alveolar destruction and impaired epithelial repair. Club cells in the small airways act as facultative progenitors capable of differentiating into alveolar type II (ATII) cells, yet their regenerative capacity is compromised in COPD. MUC5B, a major secreted mucin, is aberrantly overexpressed in small airway club cells, but its impact on epithelial lineage plasticity and repair remains unclear. Understanding how MUC5B dysregulation influences club cell fate is critical for uncovering mechanisms of defective alveolar regeneration. Methods MUC5B expression and club cell function were analyzed in human emphysematous lung tissue, a cigarette smoke-induced ferret COPD model, and a porcine pancreatic elastase (PPE)-induced mouse model of emphysema. Genetic lineage tracing of club cells in transgenic mice with Muc5b overexpression or conditional knockout was used to assess their role in alveolar repair. Flow cytometry and immunofluorescence quantified club cell differentiation over time. Spatial transcriptomics using Visium HD was performed on lung tissues from control mice, PPE-treated mice, PPE-treated Muc5b knockout mice, and Muc5b-overexpressing mice to identify signaling pathways associated with Muc5b dysregulation and club-to-ATII differentiation. Results Muc5b was markedly upregulated in human emphysema samples and animal COPD models. Transgenic Muc5b overexpression inhibited club-to-ATII differentiation and worsened alveolar destruction, whereas Muc5b knockout enhanced club cell differentiation post-injury, peaking at days 16-18 after PPE treatment compared with PPE-treated and saline controls. Spatial transcriptomic profiling identified five transcriptionally and spatially distinct club cell subpopulations with unique disease- and genotype-specific patterns. Differential gene expression analyses revealed signaling pathways associated with Muc5b overexpression and impaired club-to-ATII differentiation, providing mechanistic insight into defective epithelial repair. Conclusions Muc5b overexpression disrupts club cell mediated alveolar regeneration and promotes emphysema progression, whereas Muc5b deletion enhances epithelial repair. Spatial transcriptomics reveal distinct club cell subsets and signaling pathways underlying Muc5b driven impairment of lung regeneration in COPD. This abstract is funded by: NIH
Hu et al. (Fri,) studied this question.