重庆地区幽门螺杆菌的EPIYA基序多态性与胃十二指肠疾病的关系

Relationship between EPIYA motif polymorphisms of Helicobacter pylori and gastroduodenal diseases in Chongqing

目的：幽门螺杆菌（Helicobacter pylori,H.pylori）产生的细胞毒素相关蛋白A（cytotoxin associated antigen A,Cag A）羧基末端的EPIYA序列与胃十二指肠疾病的关系一直存在争议。本研究采集大量H.pylori高感染率同时也是胃癌高发病率的中国重庆地区的病例,通过检测患者感染的H.pylori Cag A羧基末端EPIYA基序的多态性,探讨EPIYA基序与临床胃十二指肠疾病发生的潜在关系。方法：收集消化不良患者的胃黏膜标本分离培养H.pylori,提取细菌基因组DNA,PCR扩增Cag A基因的3＇端区域并分型,根据分型结果随机抽样测序确认,结合分离出H.pylori患者的病历资料,分析EPIYA类型与胃十二指肠疾病之间的关系。结果：292（97.3%）株为Cag A阳性,但Cag A阳性与胃十二指肠疾病病型无关（P〉0.5）。19例（6.51%）为不同EPIYA类型菌株混合感染,胃癌病例中混合感染出现的概率明显高于NUD者（OR=4.46,95%CI=1.17~17.03）。单一菌株感染者273株（93.49%）,其中EPIYA-ABD型254株（93.04%）,EPIYA分型和胃十二指肠疾病的临床病型之间无显著性差异。另外,基因测序标本中发现8株EPIYA-B基序的核苷酸序列存在基因突变。结论：该研究中EPIYA-ABD型占H.pylori感染者的绝大多数,但Cag A阳性和EPIYA-ABD型均与H.pylori感染引起的胃十二指肠疾病无关;然而胃癌患者中混合感染出现的概率明显高于非溃疡性胃炎患者。

Objective ： The relationship between EPIYA motif type of Helicobacter pylori （H. pylori） CagA protein and the category of gastroduodenal diseases has been controversial. The aim of this study is to evaluate the correlation between the EPIYA type of H. pylori CagA C-terminal region and the category of gastroduodenal disea- ses. Methods： H. pylori strains were cultured and isolated from gastric biopsy specimens collected from patients with gastroduodenal symptoms. The genomic DNA was extracted and the PCR amplification was conducted to study the variations of EPIYA motifs in CagA C-terminal region. The EPIYA types were randomly selected to further veri- fy by DNA sequencing according to the classification results. Finally, the relationship between EPIYA type and the category of gastroduodenal diseases was analyzed combined with clinical data of the H. pylori-isolated patients. Re- suits： Totally, 292 （97.33%） strains were CagA gene positive, but CagA was not correlated with the type of gas- troduodenal diseases （P 〉 0.5）. Nineteen patients （6.51% ） were infected by multiply H. pylori. The probability of mixed infection was higher in gastric carcinoma than in non-ulcerative gastritis （OR =4.46, 95% CI = 1.17 to 17.03）. The rest 273 （93.49%） strains were proved to be of single infection, which comprised 254 （93.04%） EPIYA-ABD type strains. No correlation was found between EPIYA type and gastroduodenal disease type. Besides, 8 mutants of EPIYA were found in EPIYA-B segment by DNA sequencing. Conclusion： The major EPIYA type in H. pylori strains in this study is EPIYA-ABD. Neither CagA nor its C-terminal EPIYA type is correlated with the category of gastroduodenal diseases in Chinese patients. However, the probability of mixed infection in gastric car- cinoma is higher than in non-ulcerative gastritis.