Su Bin, Ceponis Peter J M, Sherman Philip M
Research Institute, Hospital for Sick Children, Departments of Paediatrics and Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada M5G 1X8.
J Med Microbiol. 2003 Oct;52(Pt 10):861-867. doi: 10.1099/jmm.0.05229-0.
Helicobacter pylori causes host epithelial cell cytoskeletal rearrangements mediated by the translocation and tyrosine phosphorylation of an outer-membrane protein, CagA, and by the vacuolating cytotoxin, VacA. However, the mechanisms by which H. pylori mediates cytoskeletal rearrangements in infected host cells need to be more clearly defined. The aim of this study was to determine the effects of H. pylori isolates from children on the architecture of host gastric epithelial cells. Gastric epithelial (AGS) cells were infected with type I (cagE(+), cagA(+), VacA(+)) H. pylori, a type II H. pylori strain (cagE(-), cagA(-), VacA(-)) or a cagE isogenic mutant. Double-labelled immune fluorescence was used to detect adherent H. pylori and the distribution of F-actin, alpha-actinin and Arp3. Both type I and type II H. pylori strains induced stress fibres in gastric epithelial cells that were not observed in uninfected cells. Type I H. pylori also induced cell elongation (hummingbird phenotype) after 4 h of infection, whereas the type II H. pylori strain did not. Less elongation occurred when AGS cells were exposed to a cagE isogenic mutant, compared with the parental strain. Confocal microscopy showed Arp3 accumulation in AGS cells infected with wild-type H. pylori, but not in response to infection with the cagE mutant. These findings indicate that type I H. pylori induce a stress fibre-like phenotype in infected gastric epithelia by a mechanism that is different from the induction of host-cell elongation. In addition to CagA and VacA, cagE also impacts on the morphology of infected gastric epithelial cells.
幽门螺杆菌可通过外膜蛋白CagA的易位和酪氨酸磷酸化以及空泡毒素VacA介导宿主上皮细胞的细胞骨架重排。然而，幽门螺杆菌介导受感染宿主细胞中细胞骨架重排的机制仍需更明确地界定。本研究的目的是确定来自儿童的幽门螺杆菌分离株对宿主胃上皮细胞结构的影响。胃上皮（AGS）细胞分别感染I型（cagE(+)、cagA(+)、VacA(+)）幽门螺杆菌、II型幽门螺杆菌菌株（cagE(-)、cagA(-)、VacA(-)）或cagE同基因突变体。采用双标免疫荧光法检测黏附的幽门螺杆菌以及F-肌动蛋白、α-辅肌动蛋白和Arp3的分布。I型和II型幽门螺杆菌菌株均在胃上皮细胞中诱导出未感染细胞中未观察到的应力纤维。I型幽门螺杆菌在感染4小时后还诱导细胞伸长（蜂鸟表型），而II型幽门螺杆菌菌株则无此现象。与亲本菌株相比，AGS细胞暴露于cagE同基因突变体时伸长较少。共聚焦显微镜显示，野生型幽门螺杆菌感染的AGS细胞中有Arp3积累，而cagE突变体感染则无此反应。这些发现表明，I型幽门螺杆菌通过一种不同于诱导宿主细胞伸长的机制，在受感染的胃上皮细胞中诱导出类似应力纤维的表型。除了CagA和VacA外，cagE也影响受感染胃上皮细胞的形态。
