Lysosomal Acidification: A New Perspective on the Pathogenesis and Treatment of Pulmonary Fibrosis

Pulmonary fibrosis is a complex pathophysiological process characterized by local pulmonary inflammation and fibrosis, along with systemic inflammation and distal organ damage. The acidic environment of lysosomes, as intracellular degradation and recycling centers, is important for cellular homeostasis and function. This review summarizes the potential role of lysosomal acidification in pulmonary fibrosis pathogenesis and its implications for cross-organ effects. Various proteins and ion channels, such as V-ATPase, ClC-7, CFTR, TRPML1, and NHE, regulate lysosomal acidification. Lung fibrosis involves many cells, including lung epithelial cells, endothelial cells, macrophages, fibroblasts, and myofibroblasts. Studies have shown that abnormal lysosomal acidification significantly contributes to the onset and progression of pulmonary fibrosis. Damaged epithelial cells activate inflammatory and fibrotic signals through lysosomal dysfunction; abnormal lysosomal acidification in endothelial cells causes tissue edema and inflammatory responses; macrophages exacerbate inflammatory responses due to impaired lysosomal acidification; and fibroblasts hyperproliferate and transform into myofibroblasts due to deficient lysosomal acidification. Chronic pulmonary inflammation increases blood-gas barrier permeability, facilitating extravasation of inflammatory mediators (e.g., IL-6, TNF-α, and TGF-β) into the circulation, where they act as endocrine signals affecting distant organs. These findings provide a rationale for exploring novel therapeutic targets; future pharmacologic modulation of lysosomal acidification and inhibition of key inflammatory mediators may represent important strategies for preventing and treating pulmonary fibrosis and its systemic complications.