Abstract：Objective To investigate the role and mechanism of epithelial-mesenchymal transition (EMT) in a rat model of bronchopulmonary dysplasia (BPD). Methods The experiment consisted of two parts. (1) Forty-eight preterm rats were randomly divided into a normoxia group and a hyperoxia group, with 24 rats in each group. The hyperoxia group was exposed to 85% oxygen to establish a BPD model, while the normoxia group was kept in room air at normal pressure. Lung tissue samples were collected on days 1, 4, 7, and 14 of the experiment. (2) Rat type II alveolar epithelial cells (RLE-6TN) were randomly divided into a normoxia group (cultured in air) and a hyperoxia group (cultured in 95% oxygen), and cell samples were collected 12, 24, and 48 hours after hyperoxia exposure. Hematoxylin-eosin staining was used to observe alveolarization in preterm rat lungs, and immunofluorescence was used to detect the co-localization of surfactant protein C (SPC) and α-smooth muscle actin (α-SMA) in preterm rat lung tissue and RLE-6TN cells. Quantitative real-time polymerase chain reaction and protein immunoblotting were used to detect the expression levels of EMT-related mRNA and proteins in preterm rat lung tissue and RLE-6TN cells. Results (1) Compared with the normoxia group, the hyperoxia group showed blocked alveolarization and simplified alveolar structure after 7 days of hyperoxia exposure. Co-localization of SPC and α-SMA was observed in lung tissue, with decreased SPC expression and increased α-SMA expression in the hyperoxia group at 7 and 14 days of hyperoxia exposure compared to the normoxia group. In the hyperoxia group, the mRNA and protein levels of TGF-β1, α-SMA, and N-cadherin were increased, while the mRNA and protein levels of SPC and E-cadherin were decreased at 7 and 14 days of hyperoxia exposure compared to the normoxia group (P<0.05). (2) SPC and α-SMA was observed in RLE-6TN cells, with decreased SPC expression and increased α-SMA expression in the hyperoxia group at 24 and 48 hours of hyperoxia exposure compared to the normoxia group. Compared to the normoxia group, the mRNA and protein levels of SPC and E-cadherin in the hyperoxia group were decreased, while the mRNA and protein levels of TGF-β1, α-SMA, and E-cadherin in the hyperoxia group increased at 48 hours of hyperoxia exposure (P<0.05). Conclusions EMT disrupts the tight connections between alveolar epithelial cells in a preterm rat model of BPD, leading to simplified alveolar structure and abnormal development, and is involved in the development of BPD. Citation:Chinese Journal of Contemporary Pediatrics, 2024, 26(7): 765-773
LIN Ya-Ting,YAN Chong-Bin,HONG Wen-Chao et al. Role and mechanism of epithelial-mesenchymal transition in a rat model of bronchopulmonary dysplasia induced by hyperoxia exposure[J]. CJCP, 2024, 26(7): 765-773.
Shin SH, Shin SH, Kim SH, et al. The association of pregnancy-induced hypertension with bronchopulmonary dysplasia: a retrospective study based on the Korean neonatal network database[J]. Sci Rep, 2020, 10(1): 5600. PMID: 32221404. PMCID: PMC7101434. DOI: 10.1038/s41598-020-62595-7.
Salimi U, Dummula K, Tucker MH, et al. Postnatal sepsis and bronchopulmonary dysplasia in premature infants: mechanistic insights into "new BPD"[J]. Am J Respir Cell Mol Biol, 2022, 66(2): 137-145. PMID: 34644520. PMCID: PMC8845139. DOI: 10.1165/rcmb.2021-0353PS.
Yang CG, Mao XL, Wu JF, et al. Amelioration of lung fibrosis by total flavonoids of Astragalus via inflammatory modulation and epithelium regeneration[J]. Am J Chin Med, 2023, 51(2): 373-389. PMID: 36655684. DOI: 10.1142/S0192415X23500192.
Gloushankova NA, Zhitnyak IY, Rubtsova SN. Role of epithelial-mesenchymal transition in tumor progression[J]. Biochemistry (Mosc), 2018, 83(12): 1469-1476. PMID: 30878022. DOI: 10.1134/S0006297918120052.
10 Yao HC, Zhu Y, Lu HY, et al. Type 2 innate lymphoid cell-derived amphiregulin regulates type II alveolar epithelial cell transdifferentiation in a mouse model of bronchopulmonary dysplasia[J]. Int Immunopharmacol, 2023, 122: 110672. DOI: 10.1016/j.intimp.2023.110672.
12 Wu D, Bai D, Yang M, et al. Role of Sox9 in BPD and its effects on the Wnt/β-catenin pathway and AEC-II differentiation[J]. Cell Death Discov. 2024 Jan 11;10(1):20. DOI: 10.1038/s41420-023-01795-2.
Chen X, Peng W, Zhou R, et al. Montelukast improves bronchopulmonary dysplasia by inhibiting epithelial?mesenchymal transition via inactivating the TGF?β1/smads signaling pathway[J]. Mol Med Rep, 2020, 22(3): 2564-2572. PMID: 32705209. DOI: 10.3892/mmr.2020.11306.
15 Feng Z, Jing Z, Li Q, et al. Exosomal STIMATE derived from type II alveolar epithelial cells controls metabolic reprogramming of tissue-resident alveolar macrophages. Theranostics, 13(3): 991-1009. PMID:36793853. PMCID: PMC9925314[J]. DOI: 10.7150/thno.82552.
Yang H, Fu J, Yao L, et al. Runx3 is a key modulator during the epithelial-mesenchymal transition of alveolar type II cells in animal models of BPD[J]. Int J Mol Med, 2017, 40(5): 1466-1476. PMID: 28949375. PMCID: PMC5627869. DOI: 10.3892/ijmm.2017.3135.
17 Yang JX, Li M, Chen XO, et al. Lipoxin a(4) ameliorates lipopolysaccharide-induced lung injury through stimulating epithelial proliferation, reducing epithelial cell apoptosis and inhibits epithelial-mesenchymal transition[J]. Respir Res, 2019, 20(1): 192. DOI: 10.1186/s12931-019-1158-z.
Zhenye L, Chuzhong L, Youtu W, et al. The expression of TGF-β1, Smad3, phospho-Smad3 and Smad7 is correlated with the development and invasion of nonfunctioning pituitary adenomas[J]. J Transl Med, 2014, 12: 71. PMID: 24636138. PMCID: PMC3995298. DOI: 10.1186/1479-5876-12-71.
