Department of Cellular and Molecular Biology, Texas Lung Injury Institute, University of Texas at Tyler Health Science Center, Tyler, TX, USA.
Xinxiang Medical University, Xinxiang, Henan, China.
Stem Cell Res Ther. 2023 Jul 27;14(1):185. doi: 10.1186/s13287-023-03414-4.
Acute lung injury is characterized by overwhelmingly elevated PAI-1 in both lung edema fluid and the circulating system. The role of increased PAI-1, encoded by Serpine1 gene, in the regeneration of injured lung epithelium has not been understood completely. This study aimed to investigate the role of Serpine1 in the regulation of alveolar type 2 epithelial cell (AT2) fate in a humanized mouse line carrying diseased mutants (Serpine1).
Wild-type (wt) and Serpine1 AT2 cells were either cultured as monolayers or 3D alveolospheres. Colony-forming assay and total surface area of organoids were analyzed. AT1 and AT2 cells in organoids were counted by immunohistochemistry and fluorescence-activated cell sorting (FACS). To test the potential effects of elevated PAI-1 on the permeability in the epithelial monolayers, we digitized the biophysical properties of polarized AT2 monolayers grown at the air-liquid interface.
A significant reduction in total AT2 cells harvested in Serpine1 mice was observed compared with wt controls. AT2 cells harvested from Serpine1 mice reduced significantly over the wt controls. Spheroids formed by Serpine1 AT2 cells were lesser than wt control. Similarly, the corresponding surface area, a readout of re-alveolarization of injured epithelium, was markedly reduced in Serpine1 organoids. FACS analysis revealed a significant suppression in the number of AT2 cells, in particular, the CD44 subpopulation, in Serpine1 organoids. A lesser ratio of AT1:AT2 cells in Serpine1 organoids was observed compared with wt cultures. There was a significant increase in transepithelial resistance but not amiloride inhibition.
Our study suggests elevated PAI-1 in injured lungs downregulates alveolar epithelial regeneration by reducing the AT2 self-renewal, particularly in the CD44 cells.
急性肺损伤的特征是肺水肿液和循环系统中 PAI-1 显著升高。编码 Serpine1 基因的 PAI-1 增加在受损肺上皮细胞的再生中的作用尚未完全理解。本研究旨在研究 Serpine1 在调节携带疾病突变体（Serpine1）的人源化小鼠系中肺泡 2 型上皮细胞（AT2）命运中的作用。
野生型（wt）和 Serpine1 AT2 细胞分别在单层或 3D 肺泡球体中培养。分析集落形成试验和类器官的总表面积。通过免疫组织化学和荧光激活细胞分选（FACS）计数类器官中的 AT1 和 AT2 细胞。为了测试升高的 PAI-1 对上皮单层通透性的潜在影响，我们数字化了在气液界面生长的极化 AT2 单层的生物物理特性。
与 wt 对照组相比，在 Serpine1 小鼠中观察到总 AT2 细胞的明显减少。从 Serpine1 小鼠中收获的 AT2 细胞明显少于 wt 对照组。Serpine1 AT2 细胞形成的球体也小于 wt 对照组。同样，相应的表面积，即受损上皮细胞再肺泡化的读数，在 Serpine1 类器官中明显降低。FACS 分析显示，在 Serpine1 类器官中，AT2 细胞数量，特别是 CD44 亚群显著减少。与 wt 培养物相比，Serpine1 类器官中的 AT1:AT2 细胞比例较低。跨上皮电阻显著增加，但阿米洛利抑制作用没有增加。
我们的研究表明，受伤肺中的高 PAI-1 通过减少 AT2 自我更新，特别是在 CD44 细胞中，下调肺泡上皮细胞再生。
