Gabasa Marta, Royo Dolores, Molina-Molina Maria, Roca-Ferrer Jordi, Pujols Laura, Picado Cesar, Xaubet Antoni, Pereda Javier
Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain.
PLoS One. 2013 Jun 3;8(6):e65445. doi: 10.1371/journal.pone.0065445. Print 2013.
Prostaglandin E2 (PGE2), the main metabolite of cyclooxygenase (COX), is a well-known anti-fibrotic agent. Moreover, myofibroblasts expressing α-smooth muscle actin (α-SMA), fibroblast expansion and epithelial-mesenchymal transition (EMT) are critical to the pathogenesis of idiopathic pulmonary fibrosis (IPF). Our aim was to investigate the expression of COX-2 and PGE2 in human lung myofibroblasts and establish whether fibroblast-myofibroblast transition (FMT) and EMT are associated with COX-2 and PGE2 down-regulation.
Fibroblasts obtained from IPF patients (n = 6) and patients undergoing spontaneous pneumothorax (control, n = 6) and alveolar epithelial cell line A549 were incubated with TGF-β1 and FMT and EMT markers were evaluated. COX-2 and α-SMA expression, PGE2 secretion and cell proliferation were measured after IL-1β and PGE2 incubation.
Myofibroblasts from both control and IPF fibroblast cultures stimulated with IL-1β showed no COX-2 expression. IPF fibroblasts showed increased myofibroblast population and reduced COX-2 expression in response to IL-1β. TGF-β1 increased the number of myofibroblasts in a time-dependent manner. In contrast, TGF-β1 induced slight COX-2 expression at 4 h (without increase in myofibroblasts) and 24 h, but not at 72 h. Both IPF and control cultures incubated with TGF-β1 for 72 h showed diminished COX-2 induction, PGE2 secretion and α-SMA expression after IL-1β addition. The latter decreased proliferation in fibroblasts but not in myofibroblasts. A549 cells incubated with TGF-β1 for 72 h showed down-regulated COX-2 expression and low basal PGE2 secretion in response to IL-1β. Immuno-histochemical analysis of IPF lung tissue showed no COX-2 immuno-reactivity in myofibroblast foci.
Myofibroblasts are associated with COX-2 down-regulation and reduced PGE2 production, which could be crucial in IPF development and progression.
前列腺素E2（PGE2）是环氧化酶（COX）的主要代谢产物，是一种众所周知的抗纤维化剂。此外，表达α平滑肌肌动蛋白（α-SMA）的肌成纤维细胞、成纤维细胞增殖和上皮-间质转化（EMT）在特发性肺纤维化（IPF）的发病机制中至关重要。我们的目的是研究COX-2和PGE2在人肺肌成纤维细胞中的表达，并确定成纤维细胞-肌成纤维细胞转化（FMT）和EMT是否与COX-2和PGE2下调有关。
将从IPF患者（n = 6）和自发性气胸患者（对照组，n = 6）获得的成纤维细胞以及肺泡上皮细胞系A549与转化生长因子-β1（TGF-β1）一起孵育，并评估FMT和EMT标志物。在白细胞介素-1β（IL-1β）和PGE2孵育后，测量COX-2和α-SMA的表达、PGE2的分泌以及细胞增殖。
用IL-1β刺激的对照组和IPF成纤维细胞培养物中的肌成纤维细胞均未显示COX-2表达。IPF成纤维细胞对IL-1β的反应显示肌成纤维细胞数量增加且COX-2表达降低。TGF-β1以时间依赖性方式增加肌成纤维细胞的数量。相比之下，TGF-β1在4小时（此时肌成纤维细胞未增加）和24小时诱导轻微的COX-2表达，但在72小时未诱导。用TGF-β1孵育72小时的IPF和对照培养物在添加IL-1β后均显示COX-2诱导、PGE2分泌和α-SMA表达减少。后者降低了成纤维细胞的增殖，但未降低肌成纤维细胞的增殖。用TGF-β1孵育72小时的A549细胞对IL-1β的反应显示COX-2表达下调和基础PGE2分泌较低。IPF肺组织的免疫组织化学分析显示肌成纤维细胞灶中无COX-2免疫反应性。
肌成纤维细胞与COX-2下调和PGE2产生减少有关，这可能在IPF的发生和发展中起关键作用。
