Tabel Ghasan, Hoa Neil T, Tarnawski Andrzej, Chen Joseph, Domek Mathew, Ma Thomas Y
Department of Internal Medicine, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA.
J Lab Clin Med. 2003 Dec;142(6):421-30. doi: 10.1016/j.lab.2003.06.001.
Helicobacter pylori (Hp) infection causes duodenal ulcers, delays the healing of such ulcers, and is associated with ulcer recurrence. The pathogenic mechanisms involved in Hp-induced duodenal mucosal injury and delay in ulcer healing remain unclear. In this study we sought to investigate the possible pathogenic actions of Hp infection and vacuolating cytotoxin (Vac A) on duodenal epithelial wound healing, using an in vitro wound model consisting of excisionally scraped or eroded IEC-6 duodenal monolayers. Two isogenic strains of Hp were used: wild-type strain 60190, producing Vac A; and an isogenic mutant strain, 60190-v1, that lacks the gene to produce the cytotoxin. The addition of Vac A-positive or Vac A-negative Hp (50:1 ratio of bacterial to epithelial cells) to the eroded or "wounded" IEC-6 monolayers resulted in significant inhibition of wound reepithelialization. The Vac A-positive Hp produced significantly greater inhibition than did the Vac A-negative Hp (70% and 35% inhibition, respectively; P <.001). Additionally, the bacterial supernatant containing Vac A (but not the supernatant lacking the cytotoxin) caused significant inhibition of IEC-6 wound reepithelialization in the absence of Hp infection, indicating that Vac A has an independent inhibitory action on wound reepithelialization. The Vac A inhibition of IEC-6 reepithelialization correlated with down-regulation of actin stress fibers in the migrating cells. Epidermal growth factor (EGF) stimulated IEC-6 wound reepithelialization with a corresponding increase in the formation of actin stress fiber. Vac A-positive bacterial supernatant (but not Vac A-negative supernatant) prevented the EGF-stimulated increase in IEC-6 actin stress fiber formation and wound reepithelialization. These findings demonstrate that Hp infection inhibits the process of duodenal epithelial wound healing. Hp inhibition of duodenal wound healing may therefore be an important pathogenic factor contributing to duodenal mucosal injury and delay in ulcer healing in vivo.
幽门螺杆菌（Hp）感染可导致十二指肠溃疡，延缓此类溃疡的愈合，并与溃疡复发相关。Hp诱导十二指肠黏膜损伤和溃疡愈合延迟所涉及的致病机制尚不清楚。在本研究中，我们试图利用由切除刮除或侵蚀的IEC-6十二指肠单层细胞组成的体外伤口模型，研究Hp感染和空泡毒素（Vac A）对十二指肠上皮伤口愈合可能的致病作用。使用了两种Hp同基因菌株：产生Vac A的野生型菌株60190；以及缺乏产生细胞毒素基因的同基因突变菌株60190-v1。向侵蚀或“受伤”的IEC-6单层细胞中添加Vac A阳性或Vac A阴性的Hp（细菌与上皮细胞的比例为50:1），导致伤口再上皮化受到显著抑制。Vac A阳性的Hp产生的抑制作用明显大于Vac A阴性的Hp（分别为70%和35%的抑制率；P<.001）。此外，含有Vac A的细菌上清液（但不含细胞毒素的上清液）在无Hp感染的情况下，导致IEC-6伤口再上皮化受到显著抑制，表明Vac A对伤口再上皮化具有独立的抑制作用。Vac A对IEC-6再上皮化的抑制作用与迁移细胞中肌动蛋白应激纤维的下调相关。表皮生长因子（EGF）刺激IEC-6伤口再上皮化，同时肌动蛋白应激纤维的形成相应增加。Vac A阳性细菌上清液（但不是Vac A阴性上清液）阻止了EGF刺激的IEC-6肌动蛋白应激纤维形成增加和伤口再上皮化。这些发现表明，Hp感染抑制十二指肠上皮伤口愈合过程。因此，Hp对十二指肠伤口愈合的抑制作用可能是导致体内十二指肠黏膜损伤和溃疡愈合延迟的重要致病因素。
