幽门螺杆菌的研究现状

幽门螺杆菌是定植于胃粘膜表面与胃粘膜层之间的微需氧菌,大量研究表明它是胃炎,消化性溃疡的主要致病因素,并且与胃癌的发生有关,本文从微生物学特点,致病机制,实验室诊断,治疗和预防等方面对幽门螺杆菌的研究现状进行综述。     

幽门螺杆菌vacA基因的克隆和序列分析

空泡毒素是幽门螺杆菌产生的已知的唯一蛋白毒素,该毒素与感染者胃肠上皮务和溃疡形成密切相关,同时也是幽门螺杆菌免疫预防和免疫治疗的重要候选组分。从幽门螺杆菌NCTC11637染色体DNA中经PCR方法获得了2.9kb的该基因成熟肽全长序列,将该基因克隆至载体pET22b ,经PCR扩增和酶切鉴定后序列分析表明,该基因与已知序列完全一致。     

幽门螺杆菌毒素及相关疾病的研究进展

幽门螺杆菌是引起胃炎,消化性溃疡等多种胃肠疾病的重要病原体。目前认为该菌的主要致病因子是细胞空泡毒素和细胞毒相关蛋白。本文综述这两种毒素的基因特征,基因分型方法,致病机制和临床相关疾病的国内外最新研究成果。     

幽门螺杆菌空泡毒素及编码基因的研究

幽门螺杆菌是胃部疾病的主要病原菌。近几年,它已成为研究热点之一,发展很快。本文就幽门螺杆菌空泡毒素及其编码基因的结构特性与胃部疾病的关系作了较为全面的介绍。     

幽门螺杆菌毒力基因分型与相关胃病

幽门螺杆菌毒力基因是其致病的原因之一,目前已知的主要毒力基因包cagPAI,vacA,iceA,babA等,不同毒力基因分型及其结合与相关性胃疾病的关系在不同地区报道不同。对幽门螺杆菌毒力基因分型的研究有利于鉴别其毒力菌株,揭示其致病机制及为幽门螺杆菌感染的流行病学研究提供帮助。     

幽门螺杆菌毒力相关基因及所致疾病

幽门螺杆菌（Ｈｐ）作为各种常见胃肠疾患的重要病原已得以确认,但其确切的致病机制的尚未阐明。目前倍受关注的是其两个特征性致病因子：细胞空泡毒素（ＶａｃＡ）和细胞毒相蛋白（ＣａｇＡ）。国外科研人员对这两种因子编码基因、同常见胃肠疾患的相关性以及在ＨＰ致病机制中的作用进行了广泛而深入的研究。     

幽门螺杆菌尿素酶基因的研究进展

近年来,幽门螺杆菌的分子生物学研究取得了很大进展,而既是定植因子、又是毒力因子的幽门螺杆菌尿素酶也得到了更加深入的研究。本文就近年来幽门螺杆菌尿素酶基因的结构、转录、表达调控等方面一些新的研究进展作一综述。     

胃癌与幽门螺杆菌cagA、hrgA基因相关性的研究

目的:探讨幽门螺杆菌(Hpylori)菌株中cagA和hrgA基因对胃癌的致病作用及其检测的意义。方法:胃癌及消化性溃疡术后切除标本,组织学检查,快速尿素酶法和PCR检测。结果:40例标本经组织学检查24例为胃腺癌,2例为胃黏膜相关淋巴样组织(MALT)瘤,14例为消化性溃疡。经快速尿素酶法检测,胃腺癌中,12例H pylori( ),消化性溃疡中,12例H pylori( )。经PCR检测,胃腺癌中,18例hrgA( ),6例hrgA(-),20例cagA( ),4例cagA(-);消化性溃疡中,6例hrgA( ),8例hrgA(-),12例cagA( ),2例cagA(-)。结论:H pylori感染与胃癌的发生有密切关系。PCR检测较快速尿素酶法准确。检测cagA和hrgA基因对了解Hpylori菌株的致病性、估计疾病程度、了解病变预后及临床治疗都具有重要意义。     

幽门螺杆菌临床分离株CagA的序列比对及其对胃上皮细胞形态与功能的影响

[背景]细胞毒素相关基因A蛋白(Cytotoxin Associated Gene A Protein,CagA)是幽门螺杆菌(Helicobacter pylori)重要的效应蛋白,CagA的多态性与胃癌的发生发展密切相关.[目的]比较幽门螺杆菌临床分离株的CagA结构差异,探讨不同CagA对胃上皮细胞形态及功能的影...     

布拉酵母菌辅助治疗对老年CagA和VacA阳性幽门螺杆菌感染患者IL-6和IL-8及肠道菌群的影响

评价布拉酵母菌（S. boulardii）对老年细胞毒素相关蛋白A（cytotoxin-associated gene A protein, CagA）和空泡毒素（vacuolating cytotoxin A, VacA）阳性幽门螺杆菌（H. pylori）感染患者炎症因子及肠道菌群的影响,以探讨S. boulardii治疗H. pylori I型高毒力株感染的机制。

选择我院200例CagA和VacA阳性的老年H. pylori感染者,采用随机数字表分成四联组和S. boulardii组。四联组患者采用铋剂四联疗法,S. boulardii组在铋剂四联疗法基础上加用S. boulardii。比较两组患者H. pylori根除率、胃黏膜组织学评分、临床疗效评分、不良反应、血清白细胞介素（IL）-6及IL-8水平、肠道菌群分布。

（1）S. boulardii组H. pylori根除率按方案（PP）分析和按意向性（ITT）分析均高于四联组（85.1% vs 72.8%;80.0% vs 67.0%）,差异均有统计学意义（均P＜0.05）。（2）S. boulardii组患者不良反应发生率（7.0%）低于四联组（21.0%）,差异有统计学意义（χ² = 8.140,P = 0.004）。（3）治疗后,两组患者胃黏膜组织学评分、临床症状评分、血清IL-6及IL-8水平均较治疗前降低,且S. boulardii组低于四联组（均P＜0.05）。（4）治疗后,四联组患者肠道乳杆菌、双歧杆菌数量较治疗前减少,肠杆菌、肠球菌数量较治疗前增加（均P＜0.05）;而S. boulardii组患者肠道乳杆菌、双歧杆菌数量较治疗前增加（均P＜0.05）,肠杆菌、肠球菌数量较治疗前差异无统计学意义（均P＞0.05）。

S. boulardii辅助四联疗法可提高老年患者H. pylori I型高毒力株的根除效果,减轻患者胃黏膜组织炎症,降低不良反应,其机制可能与S. boulardii下调免疫炎症介质表达和改善肠道菌群分布有关。

     

Comparison of genotyping of Helicobacter pylori cagA and vacA virulence genes from gastric biopsies and stool specimens

Background. We compared results of genotyping of Helicobacter pylori cagA and vacA virulence genes in DNA from gastric biopsies, both paraffin‐embedded and frozen, and from stool samples, in order to evaluate the comparative sensitivity of the stool assay. Methods. Genomic DNA from paraffin‐embedded biopsies, unfixed frozen biopsies, and stool samples of the same 20 patients was amplified for the cagA gene, an empty site (which provides a positive signal for cagA negative strains) and for the s and m alleles of the vacA gene. Composite genotypes were determined by combining data from analysis of all three materials. Results. Analysis of none of the materials taken singly showed all of the genotypes revealed by all three materials taken together, probably because of sampling error. Analysis of paraffin biopsies revealed 83.5%, that of frozen biopsies revealed 74.7% and that of stools revealed 75.9% of the genotypes. There was no significant difference in the percentage of the H. pylori genotypes identified from the three materials. Analysis of combinations of frozen biopsies and stools revealed 89.9% of the composite genotypes, and that of paraffin biopsies and stools revealed 96.2% of the composite genotypes. Evidence of multiple genotypes was found in 10 of 20 (50%) of the cases. Conclusions. Any one of the investigated biological materials can be used for detection of cagA and vacA genes, but no single assay provided a complete genotype. The use of a combination of two materials may generate a more accurate representation of H. pylori genotypes in each individual.     

Distribution of vacA genotypes in Helicobacter pylori strains isolated from Brazilian adult patients with gastritis,duodenal ulcer or gastric carcinoma

This PCR-based analysis is the first molecular epidemiological study in Brazil testing Helicobacter pylori cagA and vacA distribution in adults with gastric complaints, that includes a large number of carcinoma patients. Multiple-strain infection was identified in 11/13.4% patients. vacA s1-m1 and cagA(+) genotypes were the most common in patients with a non-mixed infection. All vacA s1 strains were s1b, so subtyping s1 strains was not useful. vacA s1b-m1 and cagA(+) strains were associated with higher prevalence of peptic ulcer and gastric carcinoma than vacA s2-m2 and cagA(-) ones. In conclusion, cagA and vacA genotyping may have clinical relevance in Brazil.     

No correlation of babA2 with vacA and cagA genotypes of Helicobacter pylori and grading of gastritis from peptic ulcer disease patients in Brazil

BACKGROUND: The babA2 gene, which encodes a blood-group antigen-binding adhesin that mediates attachment of Helicobacter pylori to human Lewis(b) antigens on gastric epithelial cells, has been associated with a higher risk of peptic ulcer and gastric cancer. The purpose of this study was to ascertain the frequency of babA2 genotype in H. pylori strains of patients with peptic ulcer and to correlate with other virulence factors. MATERIALS AND METHODS: vacA, cagA, and babA2 genotypes of H. pylori were determined by using polymerase chain reaction (PCR). DNA was extracted from positive urease test gastric samples of 150 patients with peptic ulcer. Antrum and corpus biopsies were taken for histologic examination according to the updated Sydney system classification. RESULTS: babA2 genotype was present in 104 (69.3%) and cagA in 113 (75.3%) gastric samples. No significant correlation was observed between babA2 and vacAs1 genotype or between babA2 and cagA status. The correlation of vacAs1 genotype with positive cagA was statistically significant ( p < .001). The babA2-positive strain was more frequently found from the gastric samples of men, than of women (p = .01). Strains harboring cagA, vacAs1, and babA2 genotypes had no association to the grading of gastritis, presence of glandular atrophy, or intestinal metaplasia. The simultaneous presence of cagA, vacAs1, and babA2 was found in 32.6% of the H. pylori strains. CONCLUSIONS: babA2 genotype is frequently found in H. pylori strains from peptic ulcer disease in Brazil, although it has no significant correlation to the worsening of the gastritis and to other virulence markers such as vacAs1 and cagA.     

cagA gene and vacA alleles in Spanish Helicobacter pylori clinical isolates from patients of different ages

The prevalence of the cagA gene and vacA alleles in 124 Spanish Helicobacter pylori clinical isolates from patients of different ages ranging from 3 to 78 years was studied (21 patients < or = 10 years, 30 patients 11-20 years, 17 patients 21-40 years, 31 patients 41-60 years and 25 patients 61-80 years). The cagA gene and vacA s1 or vacA s2 alleles were identified by PCR from the strain. 66.9% of the isolates were cagA+ and 33.1% cagA-. vacA s1 was detected in 48.4% of the isolates and vacA s2 in 51.6%. 44.4% of patients were cagA+/vacA s1, 22.5% were cagA+/vacA s2, 4% were cagA-/vacA s1 and 29% were cagA-/vacA s2. The percentage of cagA+ isolates and the vacA s1 alleles in the different groups were as follows: 23.8% and 28.6% in 0-10 years, 40% and 30% in 11-20 years, 88.2% and 70.6% in 21-40 years, 90.3% and 70.9% in 41-60 years and 92% and 44% in the 61-78 years group. 93% (54/58) of isolates found in ulcer patients and 90.9% (10/11) of isolates from gastritis patients older than 20 years were cagA+. In patients younger than 20 years ulcer disease was rare with 60% of isolates being cagA+ (3/5) compared with 31.6% cagA+ isolates (12/38) in patients suffering from gastritis in the younger group. The prevalence of the cagA gene and vacA s1 allele increased with age, being more frequent in older patients than in younger.     

The diversity of vacA and cagA genes of Helicobacter pylori in East Asia

It has been reported that Helicobacter pylori infection with the type I strain, which expresses the VacA and CagA antigens, is associated with duodenal ulcer. We examined the diversity of vacA and cagA genes in 143 isolates obtained from patients with duodenal ulcer or chronic gastritis in East Asia (two different areas of Japan, Fukui and Okinawa, and also in Hangzhou, China) by polymerase chain reaction (PCR) and sequence analysis. Diversities of cagA and vacA genes were detected in East Asia. The prevalence of cagA-positive H. pylori was significantly different between Fukui and Okinawa (P=0.0032). The prevalence of Western type CagA was significantly higher in Okinawa than in Fukui (P<0.0001). However, there was no significant association between the genotype of cagA and clinical outcome. In Japan, the predominant vacA genotype was s1c/m1b. In contrast, in Hangzhou, the predominant vacA genotype was s1c/m2, and they were all East Asian CagA-positive. These findings suggest that a distinct distribution of the vacA and cagA genotypes is present in East Asia, regardless of clinical outcome.     

幽门螺杆菌vacA和cagA基因全长分子系统发育分析

文章从GenBank中下载所有含有vacA和cagA基因的H.pylori菌株的VacA和CagA全长氨基酸序列,利用ClastalX 2.0和MEGA 5.05软件构建VacA和CagA分子系统发育树,探讨两基因之间的分子系统发育关系和不同聚类群的临床感染结果与基因型特征。结果显示,VacA和CagA具有高度相似的分子系统发育树,并且所有H.pylori菌株在系统发育树中具有相同的分布特点,分别聚类为东亚株群1、2和西方株群3个聚类群。其中东亚株群1患萎缩性胃炎比例较高,vacA基因型以s1c/m1b和s1a/m1b为主,cagA基因型以EPIYA-ABD为主;东亚株群2患十二指肠溃疡的比例较高,vacA基因型以s1c/m2和s1a/m2为主,cagA基因型以EPIYA-AB’C为主;西方株群患十二指肠溃疡和胃炎的比例相当,萎缩性胃炎比例较低,vacA基因型以s1a/m1a和s1b/m1a为主,cagA基因型以EPIYA-AB/B’CC为主。这些结果说明,vacA和cagA基因可能具有共进化的遗传关系;东亚株群1、2和西方株群分别具有不同的vacA和cagA基因亚型,这可能与其临床感染结果密切相关,因此,在进行H.pylori相关性疾病分析时,有必要结合vacA和cagA基因型的亚型做深入分析。     

Evaluation of nested PCR in detection of Helicobacter pylori targeting a highly conserved gene: HSP60

Objective: To comparatively evaluate a new nested set of primers designed for the detection of Helicobacter pylori targeting a highly conserved heat shock protein gene (Hsp60). Methods: A total of 60 subjects having peptic ulcer diseases were tested for the detection of H. pylori using rapid urease test (RUT), histology, culture, and polymerase chain reaction (PCR) in their antral biopsy specimens. A newly designed Hsp60 gene‐based primer set was evaluated against commonly used PCR primers for detection of H. pylori. Results: Forty‐six of the 60 study subjects were found positive for culture isolation and all the 46 culture‐positive specimens were also positive with Hsp60 gene PCR. Of the 46 culture‐positive specimens, 44 were positive for 16S rRNA gene, ureC gene, RUT, and histology whereas only 29 were positive with ureA gene PCR. Of the 14 culture‐negative subjects, 10 were positive with 16S rRNA gene, 4 were positive with ureC (glmM) gene PCR, and 2 were positive with RUT and 1 was positive on histology. Conclusion: This study shows that nested amplification targeting Hsp60 gene is the most sensitive and specific with LR⁺ and LR^? values of ∝ and 0, respectively, when compared with the other three PCR methods. Also, HSP60 gene‐specific nested protocol was the most appropriate for detection of H. pylori in clinical specimens. This is particularly valuable because it can be used as a noninvasive method for detecting H. pylori infection in young children and also, in follow‐up studies with peptic ulcer patients, on samples like feces and saliva.     

Helicobacter pylori strain and the pattern of gastritis among first-degree relatives of patients with gastric carcinoma

Background. Relatives of gastric cancer patients have an increased risk of gastric cancer, possibly related to genetically‐related strains of Helicobacter pylori or a common environment. Methods. The pattern of gastritis and H. pylori from gastric cancer patients and their first‐degree relatives were compared using detailed DNA fingerprints and vacA, cagA, and iceA genotyping. Results. Sixteen index cases from Korea, the US, or Colombia and their 38 first‐degree relatives (brothers, sisters, sons and daughters) were studied. No definite, or consistent, relationship between the pattern of gastritis and the relatedness of the H. pylori strain was observed (i.e. relatives could have an identical or a totally different pattern of gastritis regardless if they were infected with identical or highly similar organisms). For example, three elderly siblings of an index case with atrophic pangastritis had identical H. pylori isolates and environments in childhood and yet two had antral predominant nonatrophic gastritis, which is typically associated with duodenal ulcer instead of gastric cancer. Conclusions. The results of this study are not consistent with the hypothesis that specific virulence factors or similar H. pylori strains correlate with a specific histologic pattern or outcome even among those sharing the same environment in childhood.     

cagA gene variants in Malaysian Helicobacter pylori strains isolated from patients of different ethnic groups

Helicobacter pylori infection of a distinct subtype of cagA may lead to different pathological manifestation. The aim of this study is to determine the presence of cagA gene and its variants in H. pylori infection among different ethnic groups and its effect on gastroduodenal diseases. Overall detection of cagA among the 205 clinical isolates of H. pylori was 94%. Variations in size of the 3' region of cagA gene were examined among 192 Malaysian H. pylori cagA-positive strains. Results showed that three cagA variants differing in fragment length of PCR products were detected and designated as type A (621-651bp), type B (732-735bp) and type C (525 bp). Although there was no association between any of the cagA subtypes with peptic ulcer disease (p>0.05), an association between cagA subtypes with a specific ethnic group was observed. Specific-cagA subtype A strains were predominantly isolated from Chinese compared to Malays and Indians (p<0.0005), and cagA subtype B strains were predominantly isolated from Malays and Indians compared to Chinese (p<0.05). The cagA type A strains of H. pylori is commonly found in the Chinese patients who have a higher risk of peptic ulcer disease, thus indicating that it could be used as an important clinical biomarker for a more severe infection.