DDIT3 and pulmonary fibrosis: Double-staining showed that the expression of the ER stress marker CHOP and NLRP3 colocalized with surfactant protein C (SPC) in the BLM model group, indicating that ER stress and NLRP3 inflammasome activation were closely linked in type II AECs in BLM-induced pulmonary fibrosis (Figures 3(a) and 3(b)).