Amprenavir Protects Lung Epithelial Cells From Pepsin Induced Inflammation and Fibrotic Changes.

OBJECTIVES: Chronic reflux-related microaspiration is increasingly recognized as a modifiable risk factor for progressive fibrotic lung diseases such as idiopathic pulmonary fibrosis (IPF) and chronic lung allograft dysfunction (CLAD). Nonacid reflux constituents, including the gastric enzyme pepsin, are thought to be a primary source of aspiration-attributed injury. We previously showed that the FDA-approved HIV protease inhibitor amprenavir reduces pepsin-mediated inflammation and fibrosis in in vivo and in vitro models of the upper airways. Repurposing amprenavir offers a novel strategy to prevent aspiration-related lung disease progression. Our aim was to evaluate time- and dose-dependent effects of pepsin on proinflammatory and fibrotic responses in human bronchial/tracheal epithelial cells (HBECs) and assess the protective role of amprenavir. METHODS: HBECs were treated in triplicate with 0.1 or 1 mg/mL pepsin and/or 10 μM amprenavir at pH 6.5 for 15 or 30 min, followed by 6 or 24 h rest. Cell secretions were assessed by IL-8 and fibronectin ELISA, and cell lysate was assessed by E-cadherin, β-catenin, and vimentin Western blot. RESULTS: Low-dose pepsin exposure (15 min, 0.1 mg/mL, 6 h rest) induced IL-8 (p < 0.01), reversed by amprenavir (p < 0.01). High-dose pepsin (30 min, 1 mg/mL, 24 h rest) depleted E-cadherin (p < 0.05) and increased vimentin (p < 0.01), both reversed by amprenavir. CONCLUSION: Pepsin elicited dose- and time-dependent proinflammatory and fibrotic effects in airway epithelial cells in vitro, which were prevented by amprenavir. This supports the capacity of amprenavir to mitigate airway damage caused by chronic reflux-related microaspiration and highlights its potential therapeutic utility for progressive fibrotic lung diseases. LEVEL OF EVIDENCE: N/A.