BMP4 and pulmonary emphysema: Mfap4 knockout mice spontaneously develop emphysema,27 and plasma MFAP4 serves as a potential COPD biomarker;28 pan-LOX inhibition disrupts peribronchial collagen I organization, impairing functional integrity;29 and BMP4 suppresses fibroblast-to-myofibroblast differentiation by reducing autophagy and cellular senescence.30 Additionally, the finding that SERPING1 is expressed at the highest level in MSCs within fibroblasts suggests that it has unexplored repair functions, which requires further experimental validation.