Alfizah H, Noraziah M Z, Chao M Y, Rahman M M, Ramelah M
Department of Medical Microbiology and Immunology, Faculty of Medicine, Universiti Kebangsaan Malaysia, 56000 Cheras, Kuala Lumpur, Malaysia.
Clin Ter. 2013;164(4):301-5. doi: 10.7417/CT.2013.1577.
Helicobacter pylori strains secrete a vacuolating cytotoxin (VacA), plays an important role for the development of peptic ulcer disease and gastro-duodenal diseases. vacA gene is responsible to regulate the activity of the vacuolating cytotoxin. The objective of this study was molecular detection of vacA gene and observes the vacuolating activity on human gastric adenocarcinoma (AGS) cells.
H. pylori vacA gene was determined by polymerase chain reaction. Vacuolation activity of VacA toxin in broth culture filtrates was assessed in AGS cells and quantified by neutral uptake assay. Different concentration dosages of VacA and incubation time were used in the measurement of the vacuolating activity on AGS cells.
The results showed that VacA toxin could stimulate vacuolating activity on AGS cells with minimum concentration 1.0 μg/ml from both of s1m1 and s1m2 alleles (vacA gene). The toxin produced optimal reaction at 5.0 μg/ml with significant differences observed between the alleles. The results also showed that both alleles commenced the vacuolating activity at the minimum of 3 hr incubation time, and the activity showed in time-dependent manner.
Optimal concentration of VacA toxin (s1m1 allele) causes more interaction with AGS cell producing more vacuolating activities. Time-dependent vaculation of both alleles might allow H. pylori for persistent infection without rapid destruction of gastric cells might promote gastro-duodenal diseases. The study provided us better understanding of the pathogenesis of the diseases associated with H. pylori infection which is an emerging problem in developing countries.
幽门螺杆菌菌株分泌一种空泡毒素（VacA），对消化性溃疡疾病和胃十二指肠疾病的发展起重要作用。vacA基因负责调节空泡毒素的活性。本研究的目的是对vacA基因进行分子检测，并观察其对人胃腺癌（AGS）细胞的空泡形成活性。
采用聚合酶链反应测定幽门螺杆菌vacA基因。通过中性摄取试验评估肉汤培养滤液中VacA毒素在AGS细胞中的空泡形成活性并进行定量。在测量VacA对AGS细胞的空泡形成活性时，使用了不同浓度剂量的VacA和孵育时间。
结果表明，VacA毒素可刺激AGS细胞产生空泡形成活性，来自s1m1和s1m2等位基因（vacA基因）的最低浓度均为1.0μg/ml。该毒素在5.0μg/ml时产生最佳反应，等位基因之间存在显著差异。结果还表明，两个等位基因在孵育时间至少3小时时开始产生空泡形成活性，且该活性呈时间依赖性。
VacA毒素（s1m1等位基因）的最佳浓度与AGS细胞的相互作用更强，产生更多的空泡形成活性。两个等位基因的时间依赖性空泡形成可能使幽门螺杆菌持续感染而不迅速破坏胃细胞，这可能会促进胃十二指肠疾病。该研究让我们更好地理解了与幽门螺杆菌感染相关疾病的发病机制，这在发展中国家是一个新出现的问题。
