幽门螺杆菌毒力蛋白CagA诱导AGS细胞IL-8mRNA表达的研究

目的 研究AGS细胞的白细胞介素8(IL-8)mRNA表达与野生型幽门螺杆菌(H.pylori)和cagA基因突变株感染的关系.方法 采用RT-PCR法检测野生株西方型(WSS-type)H.pylori 26695和东方型(ESS-type)H.pylori HPK5、cagA基因突变株(cagA disrupted mutant strain)26695CA 和HPK5CA,按照细菌与细胞比例( multiplicity of infection,MOI) 150感染AGS 细胞的 IL-8 mRNA 动态(time-course)含量.同步感染试验排除菌株动力(motility)可能影响感染早期IL-8表达水平.结果 H.pylori诱导AGS细胞IL-8 mRNA表达.野生株西方型26695感染AGS细胞3小时后,IL-8 mRNA呈现时间依赖性(time-dependent)升高,持续升高至48小时;野生株东方型HPK5时间依赖性(time-dependent)表现为感染3小时后升高,随后降低,12小时再次出现峰值,随后又降低;突变株26695CA感染3小时后升高,持续至48小时,峰值表现在6小时和12小时;而突变株HPK5CA 感染3小时后未升高,6小时迅速达峰值,随后降低,48小时又出现峰值.结论 虽然cagA基因是诱导细胞表达IL-8 mRNA的重要因子,但并非是唯一因素,其他信号通路也参与IL-8 mRNA表达.

IL-8 mRNA expression induced by Helicobacter pylori CagA protein in AGS cells

Objective To investigate the role of mRNA IL-8 induction in AGS cells infected with wild-type H.pylori strain and cagA disrupted mutant strain.Methods AGS were infected with wild-type WSS-type 26695 and ESS-type HPK5,cagA disrupted mutant strains 26695CA and HPK5CA at an MOI of 150:1.Cells were collected at time-course after co-culture such as 3,6,12,24 and 48 h,and were utilized for measurement of RT-PCR for IL-8.Synchronized infection assays were detected to eliminate the possibility that bacterial motility influences such difference in the mRNA IL-8 level at early phase due to bacterial moving and attaching to AGS.Results H.pylori induced the expression level of mRNA IL-8 in AGS.Wild-type WSS-type 26695 time-dependently induced production of mRNA IL-8 as early as 3 h post-infection and the increament was sustained until 48 h post-infection;Wild-type ESS-type HPK5 induced mRNA IL-8 at 3 h,and mRNA IL-8 was suppressed,recovered at 12 h,then gradually decreased;mRNA IL-8 from cagA disrupted mutant strain 26695CA rapidly reached high level of mRNA IL-8 at 3 hours and sustained till 48 h,peaked at 6 h and 12 h;The mRNA IL-8 of HPK5CA showed peak at 6 h,not at 3 h,gradually decreased,and peaked at 48 h.Conclusion Although cagA is responsible for this effect on mRNA IL-8 in cells,other bacterial signal pathway are clearly essential.