A109-23 The Profibrotic Effect of Mechanical Force on Airway Basal Cells in Pulmonary Fibrosis

Abstract Rationale Idiopathic pulmonary fibrosis (IPF) is a progressive scarring lung disease characterized by a highly heterogeneous mechanical microenvironment. Emerging evidence suggests that abnormal responses of the airway epithelial cells contribute to IPF progression. We hypothesize that elevated mechanical stress disrupts airway basal cell (ABSC) function, thereby promoting fibrotic remodeling. Methods In vitro; ABSCs were isolated from healthy mice (H-ABSCs) and mice exposed to bleomycin for 14 days (B-ABSCs). ABSCs were subjected to cyclic stretch (20% elongation) for 24, 48, or 72 hours using the Flexcell FX-5000 tension system. Ex vivo: Lungs were harvested from healthy and bleomycin-treated mice (day 14), ventilated (30cmH2O, 6h). ABSCs were then isolated from these lungs for further analysis. Apoptosis of ABSCs was assessed using Annexin V-FITC/PI staining, while cell cycle dynamics were analyzed with PI staining. The differentiation state of ABSCs was evaluated using air-liquid interface (ALI) culture. qRT-PCR was used to measure the gene expression. The lung structure was evaluated by H 0.05). Prolonged stretching for 48-72 hours significantly increased apoptosis (18.9%-19.9% vs. 11%-12%, P 0.05) and upregulated TGF-β1 (FC 1.4, P 0.01), while reducing P63 and Krt5 (FC -0.77 and -0.56, P 0.05). Other differentiation markers (Scgb1a1, Muc5b, Muc5ac, Krt8, Foxj1) also declined. No significant changes were observed in stretched H-ABSCs. Ex vivo: Histological evaluation of the ventilated lungs demonstrated significant alveolar destruction (P 0.05). In ventilated B-ABSCs, mechanosensitive genes TRPV4, ITGB2, and ITGB6 were strongly elevated (FC 6.8, 6.2, and 8.5, respectively; all P 0.01), along with fibrotic genes TGF-β1, FBLN1, and GPR87 (FC 1.2, 2.1, and 6.2, respectively; P 0.05-0.01). In contrast, the expression of senescent and mechanosensitive genes, including CDKN2A, YAP1, and Piezo1, was decreased significantly (FC -0.08, -0.6, and -0.5, respectively; P 0.01). In ventilated H-ABSCs, a similar pattern was observed for ITGB2, ITGB6, Piezo1, TRPV4, CDKN2A, and FBLN1 expression; however, no significant changes were detected in GPR87 and TGF-β1 expression. Conclusions Pathological mechanical stretch induces apoptosis and alters differentiation and gene expression in B-ABSCs, promoting profibrotic and mechanosensitive signaling. In contrast, healthy ABSCs show minimal response to stretching, highlighting that prior injury sensitizes alveolar stem cells to mechanical stress and may contribute to fibrosis progression. This abstract is funded by: None