Impact of ATP Synthase Subunit β on TLR Signaling Pathway in Promoting Airway Remodeling and Heterogeneity of Small Airway Epithelial Cells in Chronic Obstructive Pulmonary Disease.

Chronic obstructive pulmonary disease (COPD) is characterized by airway remodeling and epithelial cell dysfunction, yet the underlying regulatory mechanisms remain incompletely understood. This study aimed to investigate the role of ATP synthase subunit β (ATP5B) in COPD pathogenesis, with a focus on epithelial heterogeneity and airway remodeling. We employed single-cell RNA sequencing (scRNA-seq) to analyze small airway epithelial cells and identify key cell populations and hub genes. ATP5B was identified through the intersection of differentially expressed genes (DEGs) and epithelial markers. In vitro experiments were conducted using 2% (volume/volume, v/v) cigarette smoke extract (CSE)-treated BEAS-2B cells, and in vivo validation was performed in CS/LPS-induced COPD mouse models. scRNA-seq identified 12 distinct epithelial clusters, with ATP5B emerging as a central hub gene. ATP5B expression was significantly upregulated in CSE-treated BEAS-2B cells (fold change = 1.92, p < 0.05). ATP5B knockdown reversed CSE-induced apoptosis (fold change = 0.397, p < 0.05), reduced inflammatory cytokines (e.g., IL-6: 0.40; TNF-α: 0.46, p < 0.05), and suppressed EMT marker expression (E-cadherin↑, Vimentin↓). In vivo, ATP5B silencing alleviated airway remodeling and inflammation. Mechanistically, GSEA and experimental validation demonstrated that ATP5B activates the Toll-like receptor (TLR) signaling pathway to promote airway remodeling. Our findings reveal ATP5B as a key regulator of airway remodeling in COPD via TLR signaling activation, suggesting its potential as a diagnostic biomarker and therapeutic target.