Chronic fibrosis formation is the primary pathological mechanism of alveolar epithelial cell injury (37).KL-6 is a glycoprotein, with the MUC1 gene as its main regulator, and it is highly expressed on the surface of regenerating type II alveolar epithelial cells (38, 39), a view validated by the single-cell sequencing dataset in the present study. Here, MUC1 is linked to fibrosis.