Congenital diaphragmatic hernia (CDH) is a common and often lethal birth defect characterized by congenital lung malformation, which severely affects neonate prognosis and mortality. This study aimed to investigate differences in protein expression in order to elucidate the mechanism of CDH-associated pulmonary hypoplasia during the early stage of lung development using tandem mass tag (TMT) quantitative proteomics.

Nitrofen was administered orally to establish a rat CDH model, and pathological changes were evaluated through hematoxylin-eosin (H&E), PCNA, and Ki67 staining at the pseudoglandular stage. Fetal lungs were then collected, pooled before TMT labeling, and subjected to mass spectrometry. Immunohistochemistry (IHC), Western blotting, and Q-PCR were used to further validate the candidate proteins.

A total of 79 differentially expressed proteins (DEPs) were identified when CDH and control lungs were compared, and further bioinformatics analysis showed that these proteins play important roles in tight-junctions, phospholipase D signaling, and the HIF-1 signaling pathway. Three differentially expressed proteins, Cldn3, Magi1, and Myh9 are involved in the tight-junction pathway (P < 0.05), and their differential expressions were confirmed by IHC, Western blotting, and Q-PCR.

These findings indicate that alterations of tight-junction protein expression may play an important role in the pathogenesis of abnormal lung development in CDH. Further studies are warranted to verify the mechanism by which these tight-junction proteins influence the pathogenesis of CDH-associated pulmonary hypoplasia.