Histological and clinical predictive value of determination of tissue CagA status by PCR in Helicobacter pylori infected patients; results of the large population based study in western Turkey

BACKGROUND/AIMS: Early experimental and epidemiological studies have suggested that the presence of cagA gene was a virulence factor for Helicobacter pylori. We aimed to investigate the clinical significance of tissue CagA status in Helicobacter pylori infected patients and to assess its association with histological changes in gastric mucosa. METHODOLOGY: Three hundred and forty-five patients with Helicobacter pylori infection established by both urease test and histological examination were included in the study. The symptoms of the patients were recorded according to the Glasgow dyspepsia scale. Biopsies (cardia, corpus, angulus and antrum) were evaluated histologically according to the Sidney system. The cagA status was determined by polymerase chain reaction method from an antral biopsy. Polymerase chain reaction studies were performed by Wizard genomic DNA purification system (promega). We also determined the serum levels of tumor necrosis factor-alpha, and gastrin. They were all prescribed lansoprazole (30 mg b.i.d.), clarithromycin (500 mg b.i.d.), and amoxycillin (1 g b.i.d.) for a week. At the 8th week a second endoscopy was performed and further biopsy specimens were obtained from the same sites. Mann-Whitney U and chi 2 tests were used for statistical analyses. RESULTS: Two hundred and thirty-five patients (68.1%) were infected with cagA-positive strains of Helicobacter pylori and the other 110 patients (31.8%) were infected with cagA-negative strains. We compared the parameters and measurements studied in this trial between the patients infected with cagA-positive and negative Helicobacter pylori strains. Helicobacter pylori density was greater in the cagA-positive group by 1.9 +/- 0.9 than in the cagA-negative group by 1.2 +/- 0.7 (P = 0.01). Helicobacter pylori activity and chronic inflammation also were significantly higher in the cagA-positive group with the values of 1.4 +/- 0.8 and 2.1 +/- 1.1 than in the cagA-negative group with 0.7 +/- 0.2 and 1.3 +/- 0.5, respectively (P = 0.001, P = 0.002). The presence of atrophy and lymphoid aggregate was not different between the two groups (P > 0.05). However intestinal metaplasia was shown to be significantly frequent in patients infected with cagA-positive Helicobacter pylori strains (0.001). Serum tumor necrosis factor-alpha and gastrin levels which were accepted as the markers of inflammation in Helicobacter pylori infection were increased in the cagA-positive group compared with the cagA-negative group. Serum tumor necrosis factor-alpha level was 11.3 +/- 7.0 pg/mL in the cagA-positive group and 4.9 +/- 2.7 pg/mL in the cagA-negative group (P = 0.001). Gastrin level also showed a significant difference between two groups by 66.8 +/- 31.1 pg/mL and 37.2 +/- 19.2 pg/mL, respectively, in the cagA-positive and negative groups (P = 0.001). The virulent strains seem to cause peptic ulcer more frequently. Peptic ulcer was determined in 17% of patients in the cagA-positive group but this ratio was 9% in the cagA-negative group (P = 0.608). Although, all these differences of the degree of inflammation, clinical spectrum and biochemical parameters were seen, interestingly there was no significant difference in the severity of the symptoms of the patients in both groups according to Glasgow dyspepsia severity score (P = 0.20). CONCLUSIONS: Our results confirm that cagA-positive strains of Helicobacter pylori cause greater histological changes. However this virulence is not associated with more severe symptoms. The histological changes can be predictable by determining the tissue cagA status.     

Functional dyspepsia is associated with cagA-positive Helicobacter pylori strains

BACKGROUND: The antigen CagA can be used as a marker for virulence of Helicobacter pylori. It is tempting to assume that H. pylori strains positive for cytotoxin-associated gene A (cagA) could be responsible for functional dyspepsia. A cross-sectional study was performed in patients presenting with functional dyspepsia to correlate the clinical presentation with the presence of cagA-positive and -negative H. pylori strains. METHODS: Consecutive patients referred for endoscopy were studied. An inclusion criterion was the absence of any endoscopic abnormality. Biopsy specimens were obtained from the gastric antrum for HE and immunoperoxidase stain, rapid urease test, and culture. A serum sample was taken for detection of IgG antibodies against H. pylori as well as CagA. A validated questionnaire of 14 questions regarding the upper gastrointestinal tract was used for assessment of the clinical presentation. Nine questions were scored on a 5-point Likert scale. RESULTS: 422 patients were included, 222 were H. pylori-positive, the remaining 200 were H. pylori-negative. Mean symptom score in patients with cagA-positive strains was significantly higher than in patients with cagA-negative strains. No difference was present if cagA-negative patients were compared with H. pylori-negative dyspeptics. Four different complaints were more prevalent in the cagA-positive patients compared with cagA-negatives. When cagA-positive patients were compared with H. pylori-negative dyspeptics, seven complaints were significantly more prevalent in cagA-positives; when cagA-negatives were compared this number was only two. CONCLUSIONS: Functional dyspeptics with cagA-positive H. pylori strains have more dyspeptic symptoms and higher symptom scores than patients with cagA-negative H. pylori strains as well as H. pylori-negative functional dyspeptics.     

Effects of Helicobacter pylori on proliferation of gastric epithelial cells in vitro

OBJECTIVE: H. pylori infection of the gastric mucosa has been associated with an increase in gastric epithelial cell proliferation. However, in vitro adherence of H. pylori to gastric epithelial cells is associated with reduced cell proliferation. Reduction of epithelial cell proliferation may contribute to ulcer formation and delay ulcer healing. The following study was undertaken to elucidate the ability of cagA-positive and -negative strains to impede gastric epithelial cell proliferation. METHODS: A human gastric adenocarcinoma cell line (AGS) was overlaid with either cagA-positive or cagA-negative H. pylori strains suspended in cell culture medium. Proliferation of AGS cells was analyzed by performing direct cell counts and by measuring metabolism of a soluble tetrazolium compound (MTS), after exposure to H. pylori for 24 h. RESULTS: When compared with control cells cultured in medium alone, AGS cell proliferation was reduced by 45.6% and 28.5% due to exposure to cagA-negative and cagA-positive strains, respectively. When bacterial-induced cytotoxicity was assessed by measuring release of lactose dehydrogenase (LDH) into the culture medium, cagA-positive strains were shown to induce significantly more cytotoxicity than cagA-negative strains. CONCLUSIONS: These experiments demonstrate that H. pylori exposure to AGS cells significantly reduces cell proliferation. However, cagA-positive strains that induce more cell injury reduce cell proliferation to a lesser extent than cagA-negative strains. Persistent replication of gastric epithelial cells injured by exposure to cagA-positive strains may be partially responsible for the stronger association with gastric cancer in persons infected with cagA-positive H. pylori strains.     

CagA status and virulence of Helicobacter pylori strains. Results of a French multicentric prospective study

Previous experimental and epidemiological studies with few patients suggested that the presence of the cagA gene was a virulence factor for Helicobacter pylori (H. pylori). AIM: To establish in this large epidemiological cohort study the relationship between the histological virulence of H. pylori infection and the cagA status of the bacteria. METHODS: This prospective cohort study (6 month follow-up) was conducted on adult patients undergoing endoscopy for upper gastrointestinal symptoms. The cagA status of H. pylori-positive patients was established using the polymerase chain reaction (PCR) method on an antral biopsy. A score of histological virulence (inflammation, activity) was recorded on the basis of the Sydney system (on antral, angular and fundic biopsies). Eradication treatment given was not imposed and a clinical follow-up was performed at 3 and 6 months. H. pylori eradication was verified by a 13C urea breath test at 3 months. RESULTS: Four hundred and twenty two centers recruited 652 patients (mean age: 51 +/- 15 years, 55% female). Upper GI endoscopy was abnormal in 80% of the patients of whom 68% had a gastritis aspect; 38% were infected by H. pylori, and among them 51% were cagA-positive. The histological virulence scores associated with the cagA-positive strains were significantly higher than those associated with the cagA-negative strains, globally (P = 0.0035), in the antrum (P = 0.0063), and in the angulus (P = 0.046), but not in the fundus (P = 0.05). The cagA status was correlated neither with the symptom severity at inclusion and at 6 months (P > 0.05), nor with the H. pylori eradication rate at 3 months (75% in cagA-positive and 70% in cagA-negative strains, P = 0.52). CONCLUSION: This study on a large cohort of patients confirms the greater histological virulence of H. pylori cagA-positive strains. However, this virulence was not associated with more severe symptoms nor with an increase in resistance to H. pylori eradication treatment.     

Genes inside the cagPAI of Helicobacter pylori are not associated with gastric cancer in Japan

BACKGROUND/AIMS: In Japan, infection with cagA-positive H. pylori is not associated with gastric cancer unlike Western populations. Both cagE and Agrobacterium VirD4 homologue are genes inside the cagPAI. The aim of this study was to examine whether the presence of genes inside the cagPAI, cagA, cagE and Agrobacterium VirD4 homologue, is associated with gastric cancer in Japan. METHODOLOGY: Thirty-nine patients with gastric cancer and 39 subjects with only chronic gastritis were infected with H. pylori. Seventy-eight H. pylori strains were isolated from gastric biopsies and the presence of 23S rRNA, cagA, cagE, and VirD4 homologue were studied by polymerase chain reaction. RESULTS: The positivity of cagA was 97.4% in patients with gastric cancer, and 92.3% in control subjects. Thirty-six strains (92.3%) isolated from patients and 35 strains (89.7%) from control subjects had both cagE and VirD4. All the 3 cagA-negative strains did not have both cagE and VirD4. There were no significant differences in the positivities of cagA, cagE, and VirD4 between patients and control subjects. CONCLUSIONS: cagE and VirD4 were possessed by most Japanese strains, and thus the structure of the cagPAI of H. pylori might not be associated with the development of gastric cancer in Japan.     

Detection of Helicobacter pylori cagA gene by polymerase chain reaction in faecal samples.

OBJECTIVE: The polymerase chain reaction (PCR) has been extensively and successfully used to detect Helicobacter pylori in gastric juice and gastric biopsies. In contrast, the results obtained using faeces as biological samples for PCR are rather conflicting. This may be due to the presence of faecal inhibitory compounds (polysaccharides) which can inhibit the amplification reaction. The aim of this study was to characterize the H. pylori genotype in faecal samples by using specific primers for the cagA gene. To overcome the problem of contamination by polysaccharides, we used a filter-based extraction technique already applied in a previous study. METHODS: Antral and body biopsies were obtained from 30 symptomatic patients undergoing upper endoscopy. PCR was used to detect the presence of H. pylori organisms in faecal samples by using primers selected for the urease gene A. In addition, H. pylori organisms were characterized both in faecal samples and paraffin-embedded biopsies by PCR with specific primers for the cagA gene. RESULTS: All patients showed a positive CLO test (rapid urease test) and evidence of H. pylori by Warthin-Starry stain. PCR detected the urease A gene in the faecal samples of all patients. The cagA gene was detected in the faecal and biopsy samples of 18 subjects (60%). Duodenal ulcer and/or antral erosions were observed in 15 of the 18 cagA-positive patients (83.3%) and in five of the 12 cagA-negative patients (41.7%). Endoscopic features of normal mucosa or gastritis were observed in three cagA-positive patients (16.7%) and in seven cagA-negative patients (56.3%). cagA-positive status was found to be significantly related to the endoscopic features of duodenal ulceration and/or antral erosions. CONCLUSIONS: Our findings prove that faeces are suitable samples for the detection of cagA status. Moreover, they confirm the existence of a significant relationship between cagA-positive status and duodenal ulcer and/or antral erosions.     

Gastric epithelial cell proliferation and cagA status in Helicobacter pylori gastritis at different gastric sites

OBJECTIVE: Helicobacter pylori infection causes hyperproliferation which is believed to predispose to the development of gastric carcinoma. The aim of this study was to analyze epithelial cell proliferation topographically in H. pylori gastritis in relationship to cagA status. MATERIAL AND METHODS: The proliferative index (PI: Ki-67-labeled nuclei/total number of foveolar nuclei) was determined in gastric mucosa biopsies taken at the antrum (lesser and greater curvatures), incisura, and corpus (greater curvature) from 78 patients with H. pylori gastritis and 20 H. pylori-negative patients. H. pylori and cagA status were determined by polymerase chain reaction (PCR) and serology. RESULTS: PIs were significantly higher in H. pylori- and cagA-positive patients, in comparison with H. pylori- and cagA-negative patients, at all sites (p相似文献   

High prevalence of cagA-positive strains in Helicobacter pylori-infected, healthy, young Chinese adults

BACKGROUND: Cytotoxin-associated gene A (cagA) has been implicated as a potential pathogenic marker for Helicobacter pylori-induced severe gastroduodenal diseases. Although the prevalence of cagA-positive strains has been reported in patient populations from developed countries, only limited information from developing countries is available. METHODS: Polymerase chain reaction (PCR) in combination with immunoblot analysis was used to determine the prevalence of cagA and its adjacent cagE genes and to evaluate the expression of CagA protein in 55 H. pylori clinical isolates from China. RESULTS: The expected PCR products derived from H. pylori cagA and cagE genes were identified in all Chinese H. pylori clinical isolates. Similarly, the CagA protein was detected in all 40 isolates tested. CONCLUSIONS: These results demonstrated that the presence of the cagA gene correlated well with expression of the CagA protein in all surveyed Chinese H. pylori isolates and that infection with cagA-positive H. pylori strains is highly common in China and independent of clinical presentation.     

The role of cagA Helicobacter pylori strains in gastro-oesophageal reflux disease

BACKGROUND AND AIMS: The role of Helicobacter pylori infection in gastro-oesophageal reflux disease is controversial. The aim of this study was to evaluate the prevalence of colonization by cagA-positive and cagA-negative H. pylori strains in the spectrum of gastro-oesophageal reflux disease. METHODS: A total of 108 patients (50 male/58 female; mean age, 50.3 years) with dyspepsia and peptic ulcer or erosive gastritis/duodenitis were categorized into patients without reflux and patients with reflux oesophagitis graded from I to IV. All patients underwent upper endoscopy with biopsies of the antrum. H. pylori was detected by histology, urease test and polymerase chain reaction. The cagA status was diagnosed in the gastric biopsy by polymerase chain reaction. RESULTS: The overall prevalence of H. pylori colonization in patients with reflux was 68.6% and was 70.2% in those without oesophageal disease (P = 0.862). Colonization by cagA-positive strains was also not statistically different between the two groups (31.4% versus 40.4%, P = 0.332). However, patients with grades II-IV reflux oesophagitis were less colonized by the bacterium (36.4%) than patients with grade I oesophagitis (77.5%) (P = 0.009). H. pylori cagA-positive strains were also less likely to colonize the stomach of patients with grades II-IV oesophagitis (0%), than grade I reflux oesophagitis (40%) patients and controls (40.4%). CONCLUSIONS: Infection of the stomach by H. pylori and especially by H. pylori cagA strains may play a protective role against the development of the most severe forms of gastro-oesophageal reflux disease.     

Relevance of underlying disease and bacterial vacA and cagA status on the efficacy of Helicobacter pylori eradication

AIM: To study the effects of Helicobacter pylori associated diseases and the bacterial vacA and cagA statuses on the efficacy of H. pylori eradication. METHODS: A prospective study in a consecutive series of outpatients of a gastroenterological institution and of a primary practice. A series of 146 H. pylori positive patients with peptic ulcer disease (PUD; n = 40) or nonulcer dyspepsia (NUD; n = 106) were evaluated. H. pylori vacA genotpyes and cagA status were determined directly in gastric biopsy specimens by polymerase chain reaction. The patients were treated with triple-therapy regimens consisting of a proton pump inhibitor and two antibiotics twice daily for 7 days. Reevaluation of H. pylori was determined 4-5 weeks later by endoscopy or 13C urea breath test. RESULTS: 123 patients completed the study. In 8 patients, colonization with two or more H. pylori strains was found. The overall cure rate was 84.6% (104/123). The eradication rates were significantly higher in patients with PUD (94.4%, 34/36) than in those with NUD (81.6%, 71/87; p < 0.05). In patients with cagA-positive H. pylori strains, the eradication rate was 89.0% (73/82) as compared with 78.8% (26/33) in those with cagA-negative strains (p = 0.15). The vacA genotype had no effect on the efficacy of H. pylori eradication. CONCLUSION: Using 1-week triple-therapy regimens, treatment of H. pylori infection is more effective in patients with PUD than in those with NUD.     

A new subtype of 3′ region of cagA gene in Helicobacter pyloristrains isolated from Zhejiang Province in China

AIM: To isolate the subtypes of 3′ region of cagA gene in Helicobacter pylori (H pylon) strains from Zhejiang Province in China and to investigate their relations to H pylori-associated gastroduodenal diseases. METHODS: One hundred and thirty-seven H pylori clinical strains were isolated from the gastric mucosa specimens of 74 patients with chronic gastritis, 61 with peptic ulceration, and 2 with gastric cancer. Bacterial genomic DNA was extracted and 3′ region of cagA gene was amplified by polymerase chain reaction (PCR). Subtypes of 3′ region of cagA gene were determined by the size of PCR amplified segments. The sequences of the subtypes were analyzed by PCR-based sequencing. RESULTS: Of the 137 H pyloriisolates from Zhejiang Province, 132 (96.4%) yielded PCR products that could be classified into three groups of subtypes, named as subtypes Ⅰ, Ⅱ, and Ⅲ according to their sizes. The sizes of subtypes Ⅰ, Ⅱ, and Ⅲ were 648-650bp, 705-707bp, and 815bp, respectively. Among the 132 cagA-positive H pylori strains, 123(93.2%) belonged to the group of subtype Ⅰ, 6 (4.5%) presented subtype Ⅱ, 1(0.8%) was subtype Ⅲ, and 2(1.5%) presented subtypes Ⅰ and Ⅲ both. The primary structure of subtype Ⅰ was composed of 3 repeats of R1, 1 repeat of R2 and 1 repeat of R3. Subtype Ⅱ possessing 4 repeats of R1, 2 repeats of R2 and 1 repeat of R3 was a newly found type of 3′ region of cagA gene which had not been reported before. The primary structure of subtype Ⅲ consisted of 4 repeats of R1, Ⅰ repeat of R2 and 2 repeats of R3. Comparison of the sequences of subtype Ⅰ strains with the corresponding sequences deposited in GenBank, showed a similarity of 95.0% (94.0-96.1%) for nucleotide sequences and 95.9% (94.9-97.4%) for deduced amino acid sequences. Comparison of the sequences of subtype Ⅲ strains with the corresponding sequences deposited in GenBank, showed a similarity of 93.9% (90.8-96.9%) for nucleotide sequences and 93.2% (90.2-96.2%) for deduced amino acid sequences. Among subtype Ⅱ strains, the nucleotide and deduced amino acid sequences showed a similarity of 95.2% (94.1-96.5%) and 96.4% (93.8-97.9%),respectively. There were no statistical differences in the distribution of subtypes of 3′ region of cagA gene among different H pylori-associated gastroduodenal diseases (x^2=11.544, P&gt;0.05). CONCLUSION: There are three subtypes (Ⅰ,Ⅱ, and Ⅲ) of 3′ region of cagA gene in Hpylori strains isolated from Zhejiang Province, and subtype Ⅰ is predominant. Subtype Ⅱ is a newly found subtype of 3′ region of cagA gene. The result of this study does not support the view that the subtypes of 3′ region of cagA gene in H pylori isolated from Zhejiang Province are correlated with the clinical outcomes of H pylori infection.     

广东地区幽门螺杆菌cagA基因与细菌定植及其致病性关系的研究

目的：分析广东地区细胞毒素相关基因（cagA）在幽门螺杆菌（H.pylori)中的分布情况及其与患者性别、年龄的关系；探讨H.pylori cagA在不同胃肠疾病发生中的作用及其与胃粘膜慢性炎症程度及H.pylori定植密度的关系。方法：采用改良Skirrow培养基分离培养得到191株H.pylori，用特定引物对各株细菌的cagA 3′端行聚合酶链反应（PCR）扩增鉴定；对其中83例患者再各取胃窦粘膜2块，经HE及Giemsa染色后观察胃粘膜慢性炎症程度及H.pylori定植密度。结果：广东地区H.pylori cagA阳性者占85.3%(163/191)；H.pylori cagA阳性率与患者的性别、年龄无关；消化性溃疡及胃癌患者的H.pylori cagA阳性率显著高于慢性胃炎患者；cagA阳性H.pylori菌株在胃粘膜表面的定植密度较cagA阴性菌株更高，引起的胃粘膜慢性炎症也更为严重；H.pylori的定植密度与其引起的慢性炎症程度呈正相关。结论：广东地区cagA阳性H.pylori感染者占绝大多数；cagA阳性菌株较cagA阴性菌株具有更强的致病力，可能引起更为严重的胃肠道损害。     

Cytokine gene polymorphisms influence mucosal cytokine expression, gastric inflammation, and host specific colonisation during Helicobacter pylori infection

BACKGROUND AND AIMS: Recent studies linked cytokine gene polymorphisms to H pylori related gastric cancer development. The current study evaluated the role of cytokine gene polymorphisms for mucosal cytokine expression, the gastric inflammatory response, and bacterial colonisation during H pylori infection. PATIENTS AND METHODS: In 207 H pylori infected patients with chronic gastritis, polymorphisms at different loci of the interleukin (IL)-10, IL-1B, IL-1 receptor antagonist (IL-1RN), tumour necrosis factor (TNF)-A, and interferon (IFN)-G genes were genotyped by polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP) analysis, and allelic discriminating TaqMan PCR. Mucosal cytokine mRNA copy numbers were determined by real time quantitative PCR. Presence of bacterial virulence factors was investigated by cagA, vacAs1/2, and babA2 PCR. Biopsies were assessed with regard to the degrees of granulocytic/lymphocytic infiltration and the presence of intestinal metaplasia (IM) and atrophic gastritis (AG). RESULTS: Proinflammatory IL-1 polymorphisms (IL-1RN*2(+)/IL-1B-511T/-31C(+)) were associated with increased IL-1beta expression, more severe degrees of inflammation, and an increased prevalence of IM and AG. Carriers of the IL-10-1082G/-819C/-592C alleles (GCC haplotype) had higher mucosal IL-10 mRNA levels than ATA haplotype carriers and were associated with colonisation by more virulent cagA(+), vacAs1(+), and babA2(+) H pylori strains. The TNF-A-307(G/A) and IFN-G+874(A/T) polymorphisms did not influence mucosal cytokine expression or the inflammatory response to H pylori. CONCLUSIONS: Cytokine gene polymorphisms influence mucosal cytokine expression, gastric inflammation, and the long term development of precancerous lesions in H pylori infection. Host polymorphisms are associated with certain bacterial strain types, suggesting host specific colonisation or adaptation. These findings contribute to the understanding of the complex interplay between host and bacterial factors involved in the development of gastric pathology.     

Geographic differences and the role of cagA gene in gastroduodenal diseases associated with Helicobacter pylori infection.

Helicobacter pylori (H. pylori) is the major causal agent of gastritis, peptic ulcer and gastric cancer. Several bacterium genes seem to be involved in the pathogenicity mechanism. One of them, the cagA gene, has been extensively studied and characterized. In this article we have carried out a study of characteristics and genetic variability of cagA gene in different geographic areas of the world. At the same time, we have summarized several studies that evaluate possible relation of cagA with gastroduodenal diseases associated by H. pylori infection. In our study we found that the presence of the cagA gene has been confirmed in more than 60% H. pylori strains distributed throughout the world. The prevalence of cagA genotype is of 65.4% in gastritis patients, 84.2% in patients with peptic ulcer and 86.5% in those with gastric cancer. It shows a high genetic variability of cagA associated with gastroduodenal diseases that could serve as a virulence marker in H. pylori infected subjects. However, the high prevalence of H. pylori cagA positive strains in some geographic areas does not confirm the strong association between cagA and virulence of strains as described in other countries. Nowadays, cagA gene is considered as a marker for the presence of cag pathogenicity island (cag-PAI) in H. pylori genoma. This region contains several genes that has been involved with the production of cytokines that results in an increased inflammation of host gastric mucosa, but its function is unknown. Probably, others bacterium factors, such as susceptibility host and environmental cofactors could influence in the risk of developing different gastroduodenal diseases associated with H. pylori infection.     

Development of Helicobacter pylori Infection Model in BALB/c Mice with Domestic cagA-Positive and-Negative Strains in Taiwan

We aimed to develop an H. pylori-infected mousemodel using clinically stored strains in Taiwan and totest whether development of H. pylori infection in an invivo animal model is related to the status of the cagA gene. A total of 100 male BALB/cmice, 6-8 weeks old, including 80 in the experimentalgroup and 20 in the control group, were used. Twoclinically stored H. pylori isolates, a cagA-positive and a cagA-negative strain, were selected toinduce the H. pylori infection in half (N = 40) of themice in the experimental group. Bacterial isolates of0.8 × 10⁹ CFU/ml were orally inoculatedin each mouse of the experimental group for threeconsecutive days. Ten mice in the control group weresacrificed to confirm the initial absence of H. pylori.Eight weeks after inoculation of the experimental group and no inoculation of the remaining 10mice of the control group, each mouse was killed.Gastrectomy was then performed for rapid urease test(CLOtest) and histology. In the control group, none of 20 mice had positive results from the CLOtestor histology. In contrast, excluding eight of 80 micethat died before the eighth week, 90.3% (65/72) of themice challenged with H. pylori showed persistent presence of H. pylori by histology. Theseverity of gastritis at the eighth week was moreevident in H. pylori-infected mice than in control andnoninfected mice (P < 0.05). Although gastritis wasmore severe in mice inoculated with thecagA-positive strain than with the cagA-negative strain,the rates of H. pylori infection in mice were notdifferent between cagA-positive and -negative strains(91.4% vs 89.2%, P > 0.05). In summary, storedstrains of H. pylori can be applied to induce aninfection model in BALB/c mice. The less virulentcagA-negative strain can induce H. pylori infection inmice as effectively as the cagA-positive strain. Thehigh prevalence of cagA-positive strains in Taiwanesepatients may be related to factors other than only thecagA gene of the bacteria.     

Relationship between the cagA 3' repeat region of Helicobacter pylori, gastric histology, and susceptibility to low pH.

BACKGROUND & AIMS: The variation in size of Helicobacter pylori CagA is related to repeat sequences in the 3' region of the cagA gene. We investigated whether structural subtypes of the cagA 3' region are associated with presentation of the infection or to susceptibility to acid. METHODS: We examined 319 cagA-positive H. pylori isolates: 84 isolates from Bogota, Colombia; 83 from Houston, Texas; 24 from Siena, Italy; and 128 from Seoul, Korea. The cagA 3' region was amplified by polymerase chain reaction. Gastric histology and susceptibility to pH 3 were evaluated in relation to the number of cagA repeat regions. RESULTS: Strains with more than three repeat regions were associated with significantly higher scores for gastric mucosal atrophy and intestinal metaplasia than those with fewer repeat regions. H. pylori strains with three repeat regions were also significantly more susceptible to pH 3 than isolates with fewer repeat regions. CONCLUSIONS: H. pylori strains with more than three repeat regions in the 3' region of the cagA gene are associated with enhanced histological injury and with reduced survival in acidic conditions. It is hypothesized that these variants arise within the stomach.     

Gastric ghrelin in relation to gender, stomach topography and Helicobacter pylori in dyspeptic patients

AIM: To investigate the level of gastric ghrelin in stomach mucosa of dyspeptic patients in relation to Helicobacter pylori ( H pylori) infection, bacterial cytotoxicity, topography and gender.METHODS: The study comprised 40 premenopausal women (19 H pylori positive) and 48 men (17 H pylori positive) with functional dyspepsia.All gastric biopsy specimens revealed normal mucosa or non-atrophic gastritis.Gastric ghrelin concentration was determined by Enzyme linked immunosorbent assay.The cagA and vacA strains of bacterial DNA were identified by multiplex polymerase chain reaction.RESULTS: In general, infection with H pylori caused an increase in gastric ghrelin level regardless of gender and stomach topography.Significantly more hormone was present in both, non-infected and H pylori positive female samples, as compared to males.The distribution of bacterial strains showed cagA(+) vacA s1m1 and cagA(-) vacA s2m2 genotypes as the most common infections in the studied population.A tendency to higher ghrelin levels was observed in less cytotoxic ( cagA negative) strain-containing specimens from the antrum and corpus of both gender groups (without statistical significance).CONCLUSION: An increase in gastric ghrelin levels at the stage of non-atrophic gastritis in H pylori positive patients, especially in those infected with cagA(-) strains, can exert a gastroprotective effect.