Konoeda C, Koinuma D, Morishita Y, Sano A, Nagayama K, Motomura N, Kakimi K, Miyazono K, Nakajima J, Nicolls M R, Murakawa T
Department of Thoracic Surgery, Graduate School of Medicine, University of Tokyo, Japan.
Transplant Proc. 2013 Jun;45(5):1797-801. doi: 10.1016/j.transproceed.2012.11.024.
Aberrant epithelial repair is a crucial event in the airway remodeling that characterizes obliterative bronchiolitis (OB) in transplanted lungs. Recent data from experiments using epithelial cell lines and human airway tissues from lung transplant recipients suggest that epithelial to mesenchymal transition (EMT) plays an important role in OB. The aim of this study was to clarify whether EMT is involved in airway remodeling in an animal model.
We performed orthotopic tracheal transplantation from BALB/c to C57BL/6 mice with from BALC/c to BALB/c mouse grafts as controls. Five allogeneic and 3 syngeneic recipients were humanely killed at predetermined postoperative days 2-12 as well as 14 and 21. Histology was evaluated using hematoxylin-eosin (H&E) staining. We studied the expression of specific markers, including E-cadherin, an epithelial marker; α-smooth muscle actin (SMA), and S100A4, mesenchymal markers, and zinc finger E-box-binding homeobox 1 (ZEB1), an EMT-related transcription factor.
Histologic assessment of serial H&E stains of allogeneic grafts showed remarkable pseudostratified respiratory epithelium with subepithelial inflammatory cell infiltration, as well as denuded and flattened epithelium and subepithelial fibrosis. The dynamic epithelial changes occurred earlier than the subepithelial fibrosis. Immunohistochemical evaluation indicated the emergence of α-SMA- positive epithelial cells that were most prominent on day 7. The expression of E-cadherin was attenuated in α-SMA-positive epithelial cells. S100A4 was also expressed in epithelial cells. A few days before the intraepithelial expression of α-SMA, ZEB1 emerged in the nuclei of epithelial cells.
We observed expression of an EMT-related transcription factor and mesenchymal markers along with the attenuation of epithelial marker expression in epithelial cells, several days before prominent subepithelial fibrosis formation, results that suggest epithelial cells to play an important fibrosis role in airway remodeling during epithelial to mesenchymal transition.
异常上皮修复是移植肺闭塞性细支气管炎（OB）特征性气道重塑中的关键事件。最近使用上皮细胞系和肺移植受者的人气道组织进行的实验数据表明，上皮-间质转化（EMT）在OB中起重要作用。本研究的目的是阐明EMT是否参与动物模型中的气道重塑。
我们将BALB/c小鼠的气管原位移植到C57BL/6小鼠，以BALC/c小鼠之间的移植作为对照。在术后预定的第2 - 12天以及第14天和第21天，对5只同种异体和3只同基因受体实施安乐死。使用苏木精-伊红（H&E）染色评估组织学。我们研究了特定标志物的表达，包括上皮标志物E-钙黏蛋白、间质标志物α-平滑肌肌动蛋白（SMA）和S100A4，以及EMT相关转录因子锌指E盒结合同源框1（ZEB1）。
对同种异体移植物连续进行H&E染色的组织学评估显示，有明显的假复层呼吸上皮，伴有上皮下炎性细胞浸润，以及上皮剥脱、扁平，上皮下纤维化。动态上皮变化早于上皮下纤维化出现。免疫组织化学评估表明，α-SMA阳性上皮细胞在第7天最为明显。E-钙黏蛋白在α-SMA阳性上皮细胞中的表达减弱。S100A4也在上皮细胞中表达。在α-SMA上皮内表达前几天，ZEB1出现在上皮细胞核中。
我们观察到，在显著的上皮下纤维化形成前几天，上皮细胞中出现了EMT相关转录因子和间质标志物的表达，同时上皮标志物表达减弱，这些结果表明上皮细胞在上皮-间质转化过程中的气道重塑中发挥重要的纤维化作用。
