Idiopathic pulmonary fibrosis (IPF) is a complex global disease with a pathological mechanism that remains poorly understood and for which there is currently no effective treatment. Endothelial-mesenchymal transition (EndMT) , identified as a pathological basis for various chronic vascular diseases, has recently been recognised as a significant risk factor for IPF. However, the related mechanisms have yet to be clarified.

To observe the effects of the Jagged1/Notch1 signalling pathway on EndMT to elucidate the related mechanisms during IPF.

From March to June 2021, human pulmonary arterial endothelial cells (HPAEC) were cultured in vitro. A control group was established using HPAEC with blank serum, while a model group was created by stimulating HPAEC with 5 mg/L TGF-β₁ for 72 hours. In the DAPT group, the same TGF-β₁ stimulation was followed by the addition of 500 nmol/L Notch signalling inhibitor for 72 hours. Reverse transcription quantitative polymerase chain reaction (RT-PCR) was employed to measure the expression of Notch1, Jagged1, and the CBF1 Promoter (CBF1) mRNA, while Western blotting (WB) was used to assess the protein expressions of Notch1, Jagged1, and CBF1. Co-immunoprecipitation (Co-IP) was conducted to examine the binding of Notch1 intracellular domain protein (NICD1) with CBF1, and the Methylthiazoltetrazolium Colorimetry (MTT) assay was performed to evaluate cell proliferation. Transwell and scratch assays were conducted to measure cell migration ability, and immunofluorescence was used to detect the expression of endothelial cell markers CD₃₁ and VE-cadherin, as well as mesenchymal cell markers fibroblast-specific protein 1 (FSP1) and α-smooth muscle actin (α-SMA) .

Statistical analysis revealed significant differences (P<0.05) in the expression levels of Notch1, Jagged1, CBF1 mRNA and proteins, as well as cell proliferation and migration abilities among the three groups. The blank group and DAPT group exhibited lower expressions of Notch1, Jagged1, and CBF1 mRNA and proteins, alongside reduced cell proliferation and migration compared to the model group, with significant differences noted (P<0.05) . Co-IP results indicated discrepancies in the binding of NICD1 and CBF1 among the three groups, with binding inhibited in the blank and DAPT groups, while binding occurred in the model group. Immunofluorescence results demonstrated differences in the expressions of CD₃₁, VE-Cadherin, FSP1, and α-SMA among the 3 groups, where the blank and DAPT groups showed higher expressions of endothelial markers CD₃₁ and VE-Cadherin compared to the model group, while FSP1 and α-SMA expressions were lower.

The Jagged1/Notch1 signalling pathway is involved in the EndMT process during IPF, and inhibiting this signalling pathway can suppress EndMT.

特发性肺纤维化（IPF）是一种病理机制复杂且尚无有效治疗手段的世界性疾病，内皮间质转化（EndMT）作为多种慢性血管疾病的病理基础，近年来发现也是IPF的重要危险因素之一，但其相关机制却尚未明确。

观察Jagged1/Notch1信号通路对EndMT的影响，以阐明IPF过程中EndMT的相关机制。

2021年3—6月体外培养人肺动脉内皮细胞（HPAEC），取HPAEC加空白血清作为对照组，5 mg/L TGF-β₁刺激HPAEC 72 h作为模型组，造模后加500 nmol/L Notch信号阻断剂（DAPT）作为DAPT组。采用反转录·聚合酶链反应（RT-PCR）检测Notch1、Jagged1和启动子结合因子（CBF1）mRNA的表达，蛋白质印迹法（WB）检测Notch1，Jagged1和CBF1蛋白的表达，免疫共沉淀法（Co-IP）检测Notch1活性胞内结构域蛋白（NICD1）与CBF1的结合情况，噻唑蓝比色法（MTT）检测细胞增殖情况，Transwell和划痕试验检测细胞迁移能力，免疫荧光检测内皮细胞标志物血小板内皮细胞黏附分子1（CD₃₁）和血管内皮钙粘蛋白（VE-cadherin）以及间质细胞标志物成纤维细胞特异性蛋白1（FSP1）和α-平滑肌肌动蛋白（α-SMA）的表达。

3组Notch1、Jagged1和CBF1 mRNA和蛋白表达水平、细胞增殖和迁移能力比较，差异均有统计学意义（P<0.05）。其中空白组和DAPT组Notch1、Jagged1和CBF1 mRNA和蛋白表达、细胞增殖和迁移能力均低于模型组（P<0.05）。Co-IP实验结果显示，3组NICD1与CBF1的结合情况有差异，其中空白组和DAPT组NICD1与CBF1的结合受到抑制，模型组NICD1与CBF1发生结合。免疫荧光结果显示，3组CD₃₁、VE-Cadherin、FSP1和α-SMA表达比较，差异均有统计学意义（P<0.05）；其中空白组和DAPT组内皮细胞标志物CD₃₁、VE-Cadherin表达高于模型组，间质细胞标志物FSP1、α-SMA表达低于模型组（P<0.05）。

Jagged1/Notch1信号通路参与了IPF过程中的EndMT进程，阻断该信号通路可抑制EndMT。