School of Pharmacy and Pharmaceutical Sciences, Panoz Institute, Trinity College Dublin, Dublin 2, Ireland.
Cell Tissue Res. 2010 Oct;342(1):39-51. doi: 10.1007/s00441-010-1029-x. Epub 2010 Sep 17.
The generation of myofibroblasts via epithelial-mesenchymal transition (EMT), a process through which epithelial cells lose their polarity and become motile mesenchymal cells, is a proposed contributory factor in fibrosis of a number of organs. Currently, it remains unclear to what extent epithelia of the upper airways and large intestine are susceptible to this process. Herein, we investigated the ability of model cell lines of alveolar (A549), bronchial (Calu-3) and colonic (Caco-2) epithelial cells to undergo EMT when challenged with transforming growth factor-β1 (TGF-β1) and other pro-inflammatory cytokines. Western blot and immunofluorescence microscopy demonstrated that A549 cells readily underwent EMT, as evidenced by a spindle-like morphology, increase in the mesenchymal marker, vimentin, and down-regulation of E-cadherin, an epithelial marker. In contrast, neither Calu-3 nor Caco-2 cells exhibited morphological changes nor alterations in marker expression associated with EMT. Moreover, whilst stimulation of A549 cells enhanced migration and reduced their proliferative capacity, no such effect was observed in epithelial cell lines of the bronchus or colon. In addition, concomitant treatment of A549 cells with telmisartan, an angiotensin II receptor antagonist with antifibrotic properties, was found to reduce cytokine-induced collagen I production and cell migration, although expression levels of vimentin and E-cadherin remained unaltered. Mechanistically, telmisartan failed to inhibit phosphorylation of Smad2/3. Together, these results, using representative in vitro models of the alveolus, bronchus and colon, tentatively suggest that epithelial cell plasticity and susceptibility to EMT may differ depending on its tissue origin. Furthermore, our investigations point to the beneficial effect of telmisartan in partial abrogation of alveolar EMT.
上皮-间充质转化（EMT）是肌成纤维细胞的产生途径，上皮细胞通过这一途径失去极性并变成运动性间充质细胞，这是许多器官纤维化的一个提出的促成因素。目前，尚不清楚上呼吸道和大肠上皮在多大程度上易受这一过程影响。在此，我们研究了肺泡（A549）、支气管（Calu-3）和结肠（Caco-2）上皮细胞的模型细胞系在受到转化生长因子-β1（TGF-β1）和其他促炎细胞因子的刺激时发生 EMT 的能力。Western blot 和免疫荧光显微镜表明，A549 细胞容易发生 EMT，表现为梭形形态，间充质标志物波形蛋白增加，上皮标志物 E-钙粘蛋白下调。相比之下，Calu-3 和 Caco-2 细胞既没有表现出形态变化，也没有表现出与 EMT 相关的标志物表达改变。此外，虽然刺激 A549 细胞增强了迁移并降低了其增殖能力，但在支气管或结肠的上皮细胞系中没有观察到这种效应。此外，在用具有抗纤维化特性的血管紧张素 II 受体拮抗剂替米沙坦同时处理 A549 细胞时，发现其可减少细胞因子诱导的胶原 I 产生和细胞迁移，尽管波形蛋白和 E-钙粘蛋白的表达水平保持不变。从机制上讲，替米沙坦未能抑制 Smad2/3 的磷酸化。总之，这些使用肺泡、支气管和结肠的代表性体外模型的结果，初步表明上皮细胞的可塑性和对 EMT 的易感性可能因组织起源而异。此外，我们的研究表明替米沙坦在部分阻断肺泡 EMT 方面具有有益作用。
