Epithelial damage by Helicobacter pylori in gastric ulcers

On review of 136 consecutive biopsies of benign gastric ulcer, Helicobacter pylori was detected in 78 cases (57.3%). The gastric epithelium colonized by Helicobacter pylori showed a characteristic constellation of changes, including loss of apical mucous portion of individual cells, drop-out of epithelial cells, epithelial pits, erosions and cellular tufts, indicative of cellular injury and regeneration. Among the 58 Helicobacter-negative cases, similar changes were not observed in the ulcer edges, except for two cases which exhibited some cellular tufts. Thus, the topographic association of Helicobacter pylori with epithelial damage in the gastric ulcer edges in more than half of the cases suggests that this organism probably plays an aetiological role in ulcerogenesis, at least in these cases. Furthermore, the epithelial changes are so distinctive that they can serve as a helpful histological indicator for the presence of Helicobacter pylori in gastric biopsies.     

Prevalence of Helicobacter pylori vacA,cagA and iceA genotypes in Nigerian patients with duodenal ulcer disease

Distinct virulence factors of Helicobacter pylori have been associated with clinical outcome of the infection; however, considerable variations have been reported from different geographic regions. Data on genotypes of African H. pylori isolates are sparse. The aim of this study was to determine the prevalence of specific genotypes of H. pylori in Nigerian patients with duodenal ulcer and non-ulcer dyspepsia. H. pylori was cultured from endoscopic biopsies obtained from 41 Nigerian patients (19 with duodenal ulcer, 22 with non-ulcer dyspepsia). The vacA alleles, cagA and iceA genotypes were determined by PCR. The vacA s1,m1 and s1,m2 genotypes were found in 26.3% and 22.7%, and in 73.7% and 72.7% of H. pylori isolates from patients with duodenal ulcer and non-ulcer dyspepsia, respectively. The iceA1 genotype was present in 94.7% and 86.4% of isolates from duodenal ulcer and non-ulcer dyspepsia patients, respectively. cagA+ infection was found predominantly (> 90%) in Nigerian H. pylori isolates irrespective of the clinical diagnosis. In conclusion, vacA s1,m2, iceA1 and cagA+ are common genotypes of H. pylori isolated from Nigerian patients. As in several other developing countries there seems to be no association between these genotypes and duodenal ulcer disease.     

Helicobacter pylori cagA, vacA and iceA genotypes in western Indian population of Maharashtra with varied gastroduodenal diseases

Scarce reports relying on rapid urease test, serology and histopathology are currently known for H. pylori from Western India, Maharashtra. We investigated H. pylori genotypes at molecular level in gastro-duodenal disease population during the years 2002-2005. H. pylori presence was scored by polymerase chain reaction in the infected biopsies (n = 95) in various gastric diseases. H. pylori specific 16S rDNA gene amplification based preliminary identification coupled with protein coding gene amplification scores were assessed for the incidence. H. pylori 16S rDNA and 7 housekeeping genes were detected in all biopsies, whereas 71.18% and 28% found to be cagA positive and negative respectively. The vacA toxigenic alleles (vacA s1) and middle region subunit vac m1a were found in 54%, and 59% patients. However, the iceA1 was present in 40.06%; the iceA2 was less i.e. in 13.5% patients. The most common allelic combinations in different age groups irrespective of disease types were 13-30, 31-45, 46-60 and 61-73 were cagA-vac m1a-vacA s1-iceA1. In our analysis, PCR was found to be 100% accurate in detecting H. pylori in gastric biopsies. Among West Indian population H. pylori was found to be present, irrespective of any correlation with the genotype and gender of patients with the clinical outcome. However, the genotype incidences were related to age of the patients, wherein the age group ranging from 46 to 60 years was found be susceptible for H. pylori infection.     

cagA, vacA and iceA Virulence Genes of Helicobacter pylori Isolates of Children in Finland

 cagA, vacA s and m genotypes and iceA alleles were analyzed from Helicobacter pylori strains isolated from 17 Finnish children and 32 children of non-Finnish origin living in Finland. Twelve children in the latter group were eastern European and 15 were of African origin. Only three children of non-Finnish origin were born in Finland. The vacA s1a subtype was more prevalent in the isolates from Finnish children than African children (76% vs. 7%, P<0.001);vacA s1b frequencies were 5% and 67%, respectively (P<0.001). The iceA1 allele was significantly more prevalent in African than Finnish isolates (93% vs. 35%, P<0.01). Considerable variation was noted in the frequency of vacA s1 subtypes and iceA alleles in children originating from different geographic regions, but the geographic variation of s1 subtypes resembled that described in other reports.     

Detection of Helicobacter pylori cagA gene in gastric biopsies, clinical isolates and faeces

Purpose: Helicobacter pylori infection is common in the developing countries. The cagA gene is a marker of pathogenicity island (PAI) in H. pylori. The aim of this study was to determine the prevalence of cagA among dyspeptic patients in Bahrain directly from gastric biopsy and stool specimen. Methods: A total of 100 gastric biopsy samples, 16 clinical isolates and 44 faecal specimens were collected from Bahraini adult dyspeptic patients. cagA gene of H. pylori was assessed using polymerase chain reaction (PCR). Results: The cagA gene was detected in 59 (59%) from biopsy specimens, 10 (62%) clinical isolates and in 10 (22.7%) faecal specimens. The detection of cagA positive H. pylori was significantly higher in patients with duodenal ulcer (80%) compared to those with other endoscopic finding (42%) (P<0.05). Conclusions: Using PCR to detect cagA gene directly from biopsy is a rapid and reliable technique. However, using stool specimen for genotyping in our patients showed reduced sensitivity.     

The efficacy of laboratory diagnosis of Helicobacter pylori infections in gastric biopsy specimens is related to bacterial density and vacA, cagA, and iceA genotypes

A total of 500 consecutive patients undergoing upper endoscopy were biopsied and tested for H. pylori infection by the Campylobacter-like organism (CLO) test, culture, histology, and PCR. Serum samples were tested by two different serological assays. Patients were considered H. pylori positive if at least two of the four biopsy specimen-based methods yielded positive results. PCR had the highest diagnostic sensitivity (99.4%), followed by histology (92.2%), culture (89.5%), and the CLO test (89.0%). The specificities of all methods were higher than 98%. Of the organisms from the 181 PCR-positive patients, the vacA (s and m regions), cagA, and iceA genotypes were determined by reverse hybridization (line probe assay) or an allele-specific PCR. Organisms that were detected by PCR but that remained undetected by the CLO test were significantly more often vacA s1 (P = 0.006), m1 (P = 0.028), and cagA positive (P = 0.029) than vacA s2, m2, and cagA negative, respectively. Organisms that were detected by PCR but that remained undetected by culture or histology more often contained iceA1 (P = 0. 034 and P = 0.029, respectively) than iceA2. Higher H. pylori density was associated with vacA s2 (P = 0.024), vacA m2 (P = 0.050), and cagA-negative (P = 0.035) genotypes. Also, the diagnostic results of the CLO test (P = 0.001) and culture (P = 0.031) but not those of the PCR (P = 0.130) were significantly associated with the H. pylori density. The rate of detection by the four biopsy specimen-based tests was lower for patients who used proton pump inhibitors, but this was independent of the H. pylori genotypes. These observations may be explained by different bacterial densities, as established by the distinct genotypes of H. pylori, and confirm that the biologies of strains with such genotypes are considerably different.     

Distribution of vacA alleles and cagA status of Helicobacter pylori in peptic ulcer disease and non-ulcer dyspepsia

The occurrence of cagA and vacA alleles among Helicobacter pylori isolates from Turkish patients and their relationship with ulcer disease outcome was investigated. Among isolates from 47 patients with peptic ulcer disease and 51 patients with non-ulcer dyspepsia, 72.3% and 44.4%, respectively, were cagA-positive (p 0.019). Most (88.8%) isolates were typed as vacA s1, and all of these were subtype s1a. The commonest (51.0%) vacA genotype was s1a m1. The results of multivariate analysis indicated that infection with cagA-positive H. pylori was the only variable associated with an increased risk of peptic ulcer disease (odds ratio, 3.01; 95% confidence interval, 1.27-7.10; p 0.012).     

Relationship between Helicobacter pylori iceA, cagA, and vacA Status and Clinical Outcome: Studies in Four Different Countries

There is continuing interest in identifying Helicobacter pylori virulence factors that might predict the risk for symptomatic clinical outcomes. It has been proposed that iceA and cagA genes are such markers and can identify patients with peptic ulcers. We compared H. pylori isolates from four countries, looking at the cagA and vacA genotypes, iceA alleles, and presentation of the infection. We used PCR to examine iceA, vacA, and cagA status of 424 H. pylori isolates obtained from patients with different clinical presentations (peptic ulcer, gastric cancer, and atrophic gastritis). The H. pylori isolates examined included 107 strains from Bogota, Colombia, 70 from Houston, Tex., 135 from Seoul, Korea, and 112 from Kyoto, Japan. The predominant genotype differed among countries: the cagA-positive iceA1 vacA s1c-m1 genotype was predominant in Japan and Korea, the cagA-positive iceA2 vacA s1b-m1 genotype was predominant in the United States, and the cagA-positive iceA2 vacA s1a-m1 genotype was predominant in Colombia. There was no association between the iceA, vacA, or cagA status and clinical outcome in patients in the countries studied. iceA status shows considerable geographic differences, and neither iceA nor combinations of iceA, vacA, and cagA were helpful in predicting the clinical presentation of an H. pylori infection.     

Prevalence of Helicobacter pylori vacA and cagA genotypes in Ethiopian dyspeptic patients

A total of 300 gastric biopsy samples and 50 Helicobacter pylori isolates were collected from Ethiopian adult dyspeptic patients. The vacA and cagA genes were detected in 90 and 79% of biopsy specimens, respectively, and in 100 and 87% of clinical isolates, respectively. Both genes were detected in 84% of the gastric biopsy samples and in 87% of the clinical isolates. Among vacA genotypes, the s1/m1 genotype was the most common in gastric biopsy samples (48%). The vacA and cagA positive H. pylori strains were detected to a higher degree in patients with chronic active gastritis (71%) than patients with other histopathological findings (29%) (P < 0.05).     

Prevalence and distribution of Helicobacter pylori cagA and vacA genotypes in the Moroccan population with gastric disease

Helicobacter pylori infection is the etiologic agent of various gastric pathologies. The severity of disease outcome has been attributed to some H. pylori genotypes, which varies geographically. In Morocco, there are no data regarding the pattern of H. pylori genotypes; therefore, this is the first prospective study conducted in our country to investigate the genotype profiles (vacA and cagA) of H. pylori in patients with gastric pain. Endoscopic biopsies were obtained in patients attending the gastroenterology department of the Hospital University Hassan II of Fez for gastric pain and were directly used for H. pylori detection and genotyping by polymerase chain reaction (PCR). The SPSS software program was used to study the genotype correlation to different clinical outcomes. A total of 429 patients were included in this study, with an infection rate of 69.9%. cagA was detected in 42.3% of cases. However, vacA genotyping reveal a large predominance of s2m2. Infection with multiple strains was detected in 10.8% of cases and incomplete vacA was observed in 31.5%. In Morocco, vacA s1m1 was significantly associated to peptic ulcer diseases, while s2m2 was associated to gastritis. Moroccan H. pylori vacA genotype profiles differ from the Latin American, European, and South African profiles, with more similarities to the North African profile. Because of the small number of cases with gastric cancer, no correlations with H. pylori have been studied, so, further studies will be required in order to highlight the effects of those genes on this disease.     

Diversity of Helicobacter pylori vacA gene and cytotoxin production

Objective: To determine the frequency of different alleles of the vacA gene among the strains of Helicobacter pylori isolated from children and adults, and to compare vacuolating cytotoxin production with different combinations of vacA alleles.
Methods: H. pylori strains were isolated from the gastric biopsy samples of 100 patients with duodenal ulcer (32) and chronic gastritis (68). Bacterial DNA was extracted and the vacA alleles typed using PCR. Cytotoxin activity was assessed by an Intestine 407 cell vacuolation assay.
Results: Alleles s1 and s2 of vacA were identified in 72% and 28% of the tested strains, respectively. Of the 72 type s1 strains, 71 were classified as type s1a and only one as s1b. The predominant sequence observed in the vacA middle region was the m2 type (65%). Combinations of vacA genotypes s1a m1, s1a m2 and s2 m2 were found in 35%, 36% and 28% of strains, respectively. Vacuolating cytotoxin was produced by vacA s1a m1 strains isolated from patients with duodenal ulcer (84.6%) and chronic gastritis (68.2%). Subtype s1a m2 strains expressed vacuolating cytotoxin less frequently in both duodenal ulcer (47.1%) and chronic gastritis (21.1%) patients (   p <0.01  ). Antibodies to VacA (89 kDa) were found in 71.9% of patients with duodenal ulcer and in 42.6% of patients with chronic gastritis.
Conclusions: Most H. pylori vacA s1 m1 strains are toxic, whereas s2 m2 forms are essentially non-toxic.     

Assessment of Helicobacter pylori vacA and cagA genotypes and host serological response

Helicobacter pylori strains can be distinguished by genotyping of virulence-associated genes, such as vacA and cagA. Because serological discrimination between strain types would reduce the need for endoscopy, 61 patients carrying H. pylori were studied by vacA and cagA genotyping of H. pylori in gastric biopsy specimens and by detection of specific serum antibodies. Serological responses to H. pylori were determined by Helicoblot (versions 2.0 and 2.1). Antibodies to CagA also were determined by a rapid anti-CagA assay (Pyloriset screen CagA) as well as by two noncommercially developed enzyme immunoassays, each using a recombinant CagA protein. Assessment of performance of the Helicoblot assays indicated substantial interobserver variation, with kappa values between 0.20 and 0.93. There was no relationship between the serological profiles on the Helicoblot and the genotypes from the same patients, except for strong associations between the presence of anti-CagA and the cagA-positive and vacA s1 H. pylori genotypes. Detection of anti-CagA by the five different assays varied considerably, with kappa values ranging from 0.21 to 0.78. Using the cagA genotype as the "gold standard," the sensitivity and specificity of the anti-CagA assays varied from 71.4 to 85.7% and from 54.2 to 100%, respectively. Thus, serological profiles of antibodies to H. pylori are heterogeneous and, with the exception of anti-CagA antibodies, show no relation to the H. pylori vacA and cagA genotypes. Detection of anti-CagA antibodies is strongly dependent on the test used.     

Genetic characterisation of Helicobacter pylori isolates from an Argentinean adult population based on cag pathogenicity island right-end motifs, lspA–glmM polymorphism and iceA and vacA genotypes

Isolates of Helicobacter pylori from 88 patients were characterised by cagA status, cagA pathogenicity island (PAI) right-end motifs, iceA, vacA and lspA-glmM genotypes, primarily by PCR-based analysis, to investigate whether Argentinean isolates differed from those recovered in southern Europe or other Latin American countries. PCR-based analysis of vacA alleles was confirmed by reverse hybridisation in 56 cases, while sequence analysis was performed either when iceA and vacA genotypes could not be determined by PCR, or to investigate PCR and reverse hybridisation vacA genotyping discordance. Typing by lspA-glmM restriction fragment length polymorphism was performed with HhaI and AluI. The pattern of cag PAI right-end motifs and the prevalence of type Ia were similar to those in isolates from southern European countries, with cagA(+)/iceA1/vacA-s1 m1 being the commonest genotype. Reverse hybridisation identified a vacA-s1a/s1b recombinant allele, confirmed by sequencing analysis. Analysis of lspA-glmM genotypes identified at least 73 unrelated strains. Few mixed infections were identified, but in one case, isolates from a single biopsy exhibiting two vacA alleles were shown by lspA-glmM fingerprints to be two unrelated strains. No associated effect on ulcer disease risk was demonstrated by analysis of cagA, vacA and iceA status. Overall, the isolates of H. pylori from Argentina were similar to isolates from southern Europe or Latin American countries, and infections were associated mainly with single H. pylori strains.     

Correlation between IL-8 induction, cagA status and vacA genotypes in 153 French Helicobacter pylori isolates

The polymorphism of clinical presentations associated with Helicobacter pylori infection is potentially due to differences in the virulence of individual strains. H. pylori virulence has been associated with the ability to induce secretion of interleukin-8 (IL-8), the vacA genotypes, and the cagA status. The aim of this study was to determine the virulence profiles of 153 French H. pylori isolates on the basis of vacA genotypes, cagA status, and IL-8 induction ability. A total of 153 H. pylori isolates from patients with chronic gastritis (n = 74) or gastro-duodenal ulcers (n = 79) was examined for vacA genotypes and cagA status by polymerase chain reaction (PCR) and dot blot, and for their ability to induce IL-8 secretion by HEp-2 cells. The prevalence of vacA genotypes was: s1/m1 44.3%, s1/m2 24.9%, and s2/m2 23.5%. The cagA gene was present in 64% of the strains. IL-8 secretion was induced by 58.7% of the isolates. The presence of the cagA gene was significantly correlated with the s1/m1 vacA genotype and with the induction of IL-8. Thirty-four strains were atypical (cagA-positive/IL-8 noninducer or cagA-negative/IL-8 inducer). vacA genotypes, cagA status, and IL-8 induction ability are not correlated with the presence or absence of ulcer. The cagA status is not sufficient to predict the proinflammatory ability of H. pylori.     

幽门螺旋杆菌引起胃黏膜免疫损伤机制研究进展

幽门螺旋杆菌(Helicobacter plyori,Hp)是消化道疾病最常见的病因,通过多种机制诱导炎症通路激活、免疫细胞及炎症因子释放改变胃黏膜周围微环境引起慢性炎症,持久性的慢性炎症可导致胃黏膜萎缩、甚至诱发胃癌.正常机体T淋巴细胞在免疫反应中起主导作用,其中正向调节与负向调节系统相互诱导和制约T细胞网络维持免疫系统平衡,当Hp感染后两项调节比例出现异常,导致免疫系统紊乱从而引起免疫损伤.近年来免疫细胞的分子生物学研究已经成为临床过继性细胞免疫治疗的理论基础.     

Clinical and histological associations of cagA and vacA genotypes in Helicobacter pylori gastritis.

AIMS: To determine the relation among the cytotoxin associated gene (cagA) and vacuolating cytotoxin gene (vacA) status of Helicobacter pylori isolates, the associated clinical diseases, and the severity and pattern of chronic gastritis. METHODS: Helicobacter pylori was cultured from gastric biopsies obtained from dyspeptic patients. DNA was extracted from the isolates and the cagA and vacA status determined by the polymerase chain reaction (PCR). The prevalence of the different cagA and vacA genotypes in three clinical groups, duodenal ulcer, gastric ulcer, and non-ulcer dyspepsia was compared. The histological features in sections from two antral and two corpus biopsies were graded by one blinded observer. The grades were compared with age and sex matched groups with different cagA and vacA genotypes, and with duodenal ulcers, or non-ulcer dyspepsia. RESULTS: Isolates from 161 patients were included. One hundred and nine (68%) harboured a cagA+ strain and 143 (89%) harboured a vacA s1 strain. The prevalence of cagA+ strains in duodenal ulcer patients (94%) was highly significantly greater than in those with non-ulcer dyspepsia (56%). However, of the patients infected with a cagA+ strain, almost equal numbers had non-ulcer dyspepsia or peptic ulceration. Chronic inflammation, polymorph activity, surface epithelial degeneration, atrophy, and intestinal metaplasia were all significantly more severe in the cagA+ than in the cagA- group, whereas only corpus epithelial degeneration was significantly more severe in the vacA s1 group compared with the vacA s2 group. Patients infected with cagA+ strains were almost four times more likely to have antral intestinal metaplasia than cagA- patients. An antral predominant gastritis was present in duodenal ulcer patients compared with matched non-ulcer dyspepsia patients, but this was not attributable to cagA or vacA status. CONCLUSIONS: Helicobacter pylori strains showing cagA positively and the vacA s1 genotype are associated with more severe gastritis but these virulence factors do not appear to determine the overall pattern. The pattern is closely linked to clinical disease. Therefore, it is likely that the nature of the disease complicating chronic infection is determined by host and environmental factors, while bacterial factors determine the magnitude of the risk of developing such disease.     

Modes of Helicobacter colonization and gastric epithelial damage

A total of 144 gastric biopsies colonized by Helicobacter-like organisms were studied under light and differential interference contrast microscopy for the modes of bacterial colonization. Biopsies were also graded for the degree of epithelial damage (epithelial-damage-grade: 0 to 6, in ascending order of severity) and density of Helicobacter-like organism (Helicobacter-grade: 0 to 6, in ascending order of bacterial density). Three modes of colonization were identified: free-in-mucus, surface-adhesion and intercellular colonization. Because light microscopy cannot definitely prove the presence of intracellular colonization, bacteria located between cells and below the apical cell border were counted together as intercellular colonization. Bacteria free-in-mucus were seen in all biopsies. Surface adhesion was seen in 50-87.9% of biopsies, without obvious correlation with the epithelial-damage- and Helicobacter-grades. The incidences of intercellular and intracellular colonization were directly proportional to the epithelial-damage- and Helicobacter-grades. Free-in-mucus as the predominant mode of colonization was mainly seen in biopsies with lower (1-3) epithelial-damage- and Helicobacter-grades. Conversely, biopsies with intercellular colonization as the predominant mode of colonization were mainly cases with higher (4-6) epithelial-damage- and Helicobacter-grades. In cases showing predominantly bacteria between cells, 69.2% had a gastric ulcer whereas only 38.8% of cases showing predominantly bacteria free-in-mucus showed ulceration (P < 0.01). These results indicate that Helicobacter-like organisms can invade and penetrate between epithelial cells. When free-in-mucus, Helicobacter-like organisms are less likely to induce epithelial damage. However, the more invasive modes of colonization (intercellular) were associated with severe epithelial damage and high Helicobacter density.(ABSTRACT TRUNCATED AT 250 WORDS)     

抗幽门螺杆菌血清IgE和胃粘膜肥大细胞在Hp致病中的作用

目的探讨机体免疫反应在幽门螺杆菌（Ｈｐ）致病中的作用。方法采用间接ＥＬＩＳＡ法检测了１４９例患者血清中抗ＨｐＩｇＥ,并用改良甲苯胺蓝染色法检测其胃粘膜中肥大细胞（ＭＣ）。结果①Ｈｐ阳性者血清抗ＨｐＩｇＥ含量、阳性率和胃粘膜中ＭＣ总数及脱颗粒比均显著高于Ｈｐ阴性者（Ｐ＜０．０１）;②不同胃部疾病之间血清抗ＨｐＩｇＥ含量、阳性率和胃粘膜中ＭＣ总数及脱颗粒比有显著差异,活动性胃炎显著高于非活动性胃炎和消化性溃疡（Ｐ＜０．０１）,中重度胃炎显著高于轻度胃炎（Ｐ＜０．００１）;③血清抗ＨｐＩｇＥ阳性者胃粘膜内ＭＣ总数及脱颗粒比均显著高于抗ＨｐＩｇＥ阴性者（Ｐ＜０．０１）,且血清抗ＨｐＩｇＥ含量与胃粘膜内ＭＣ脱颗粒比呈正相关（ｒ＝０．６０,Ｐ＜０．００１）。结论血清抗ＨｐＩｇＥ参与了Ｈｐ的致病过程,其机制可能为刺激ＭＣ脱颗粒,而致胃粘膜损伤。     

幽门螺杆菌vacA基因变异性研究

目的：探索幽门螺杆菌（Helicobacter pylori,简称Hp)vacA基因（vacuolating cytotoxin gene A)的变异性及其与产生空泡毒素活性的关系。方法：用自行设计的两两配对的4条引物对17株Hp的vacA基因进行PCR扩增。结果：每株细菌均可扩增出包括vacA基因不同区域的4条产物,但每种产物在不同菌株间长度有差异;对产毒株与非产毒株的扩增产物长度比较,未发现与产毒有关的区域。结论：Hp vacA基因的变异性相当大,变异部位不仅仅局限于某一区域,沿不能确定与产毒有关的基因区域。推测Hp表达VacA活性与否可能与分泌的量有关。     

Clinical Relevance of the vacA, iceA, cagA, and flaA genes of Helicobacter pylori strains isolated in Eastern Taiwan

The genotypes of Helicobacter pylori flaA, cagA, vacA, and iceA were determined for DNA isolated from patients with chronic gastritis or peptic ulcer in eastern Taiwan. The vacA gene encoding the s1a subtype was found to predominate in peptic ulcer patients, and the iceA1 genotype was associated with chronic gastritis. cagA and flaA genes were not found to be associated with these types of disease.