Objective:To explore the potential effect of peptide KLF14-P1 secreted from mesenchymal stem cells（MSCs）in bronchopulmonary dysplasia（BPD）.Methods:Low，medium and high doses of the paracrine peptide KLF14-P1 from MSCs were intraperitoneally injected into neonatal mice with BPD induced by hyperoxia. The pathological changes in lung tissue were observed，and the expression of surfactant protein C（SPC）in lung tissue was analyzed by immunofluorescence staining. Meanwhile，the levels of inflammatory factors in bronchoalveolar lavage fluid（BALF）and lung tissue，including tumor necrosis factor alpha（TNF-α），interleukin-1β（IL-1β），IL-6，and IL-10，were detected. And after pretreating with low，medium and high doses of KLF14-P1 for 24 hours，mouse lung epithelial cells MLE-12 were stimulated with H 2O 2 for 2 hours. The cell proliferation，levels of inflammatory factors（TNF-α，IL-1β，IL-6，IL-10），reactive oxygen species（ROS），and c-Jun N-terminal kinase（JNK）protein level were then detected. Results:The lung dry-to-wet weight ratio of the medium-dose KLF14-P1 group（0.202±0.011）and the high-dose KLF14-P1 group（0.209±0.010）of the newborn mice increased significantly compared with the BPD group（0.187±0.008）（ P<0.01）. Compared with the BPD group，the lung alveolar structure of the newborn mice in the medium-dose and high-dose KLF14-P1 groups improved significantly，and the levels of TNF-α，IL-1β，and IL-6 in lung tissue and BALF decreased，while IL-10 increased（all P< 0.01）. Compared with the H 2O 2 group（49.296%±0.980%），the survival rate of MLE-12 cells in the low-dose group（56.390%±0.810%），the medium-dose group（73.506%±2.504%），and the high-dose group（81.699%±1.554%）increased significantly，cell apoptosis decreased significantly，inflammatory factors TNF-α，IL-1β，and IL-6 decreased，and IL-10 level increased（all P<0.01）. Moreover，the ROS accumulation of cells in the low，medium，and high-dose KLF14-P1 groups was lower than that of the H 2O 2 group，and the phosphorylated JNK protein level decreased（all P<0.05）. Conclusion:KLF14-P1 alleviated the lung injury and inflammatory response in BPD mouse，possibly through the inhibition of the ROS/JNK pathway.

Premature infants are frequently prone to adverse pulmonary outcomes due to inadequate lung development.During the neonatal period，It is manifested as restrictive ventilatory impairments characterized by reduced lung volume and compliance，as well as obstructive ventilatory impairments marked by increased airway resistance.Although there is some improvement in lung volume and compliance from infancy to school age，varying degrees of persistent airway obstruction still exist，particularly in extremely preterm infants，which may persist into adulthood and lead to chronic pulmonary diseases.The techniques utilized for lung function test in premature infants differ in different age groups.School-age and adolescent children can employ the same test methods as adults.However，for preschool-aged children and particularly newborns，due to their tender age，limited capacity for complete cooperation and distinctive physiological characteristics，the current test techniques have not yet been widely implemented which are still in research.This article presents a comprehensive review of lung function characteristics and assessment methods at various stages of premature infants.