Use of Comet assay to assess DNA damage in patients infected by Helicobacter pylori: comparisons between visual and image analyses

Studies of DNA damage in gastric epithelial cells of Helicobacter pylori (H. pylori)-infected patients are conflicting, possibly due to different methods used for scoring DNA damage by Comet assay. Therefore, we compared the sensitivity of visual microscopic analysis (arbitrary units-scores and comets%) and image analysis system (tail moment), in the gastric epithelial cells from the antrum and corpus of 122 H. pylori-infected and 32 non-infected patients. The feasibility of cryopreserved peripheral blood lymphocytes and whole-blood cells for DNA damage biomonitoring was also investigated. In the antrum, the levels of DNA damage were significantly higher in H. pylori-infected patients with gastritis than in non-infected patients with normal mucosa, when evaluated by image analysis system, arbitrary units and comets%. In the corpus, the comets% was not sufficiently sensitive to detect the difference between H. pylori-infected patients with gastritis and non-infected patients with normal mucosa. The image analysis system was sensitive enough to detect differences between non-infected patients and H. pylori-infected patients with mild gastritis and between infected patients with moderate and severe gastritis, in both antrum and corpus, while arbitrary units and comets% were unable to detect these differences. In cryopreserved peripheral blood lymphocytes, the levels of DNA damage (tail moment) were significantly higher in H. pylori-infected patients with moderate and severe gastritis than in non-infected patients. Overall, our results indicate that the image analysis system is more sensitive and adequate to measure the levels of DNA damage in gastric epithelial cells than the other methods assayed.     

Four modes of adhesion are used during Helicobacter pylori binding to human mucins in the oral and gastric niches

Background:  Helicobacter pylori causes peptic ulcer disease and gastric cancer, and the oral cavity is likely to serve as a reservoir for this pathogen. We investigated the binding of H. pylori to the mucins covering the mucosal surfaces in the niches along the oral to gastric infection route and during gastric disease and modeled the outcome of these interactions.
Materials and Methods:  A panel of seven H. pylori strains with defined binding properties was used to identify binding to human mucins from saliva, gastric juice, cardia, corpus, and antrum of healthy stomachs and of stomachs affected by gastritis at pH 7.4 and 3.0 using a microtiter-based method.
Results:  H. pylori binding to mucins differed substantially with the anatomic site, mucin type, pH, gastritis status, and H. pylori strain all having effect on binding. Mucins from saliva and gastric juice displayed the most diverse binding patterns, involving four modes of H. pylori adhesion and the MUC5B, MUC7, and MUC5AC mucins as well as the salivary agglutinin. Binding occurred via the blood-group antigen-binding adhesin (BabA), the sialic acid-binding adhesin (SabA), a charge/low pH-dependent mechanism, and a novel saliva-binding adhesin. In the healthy gastric mucus layer only BabA and acid/charge affect binding to the mucins, whereas in gastritis, the BabA/Le^b-dependent binding to MUC5AC remained, and SabA and low pH binding increased.
Conclusions:  The four H. pylori adhesion modes binding to mucins are likely to play different roles during colonization of the oral to gastric niches and during long-term infection.     

The size of cagA based on repeat sequence has the responsibility of the location of Helicobacter pylori in the gastric mucus and the degree of gastric mucosal inflammation

The aim of this study was to examine whether there is a relationship between cagA size of Japanese Helicobacter pylori strains and the location of these strains in the mucous layer, the degree of gastric inflammation and acid survival. Upper gastrointestinal endoscopies were done to 144 patients with dyspeptic symptom with informed consent, sera, biopsy specimens and H. pylori strains were obtained, and gastric histology and susceptibility to pH 3 of the strains were evaluated. To determine cagA size of Japanese strains using PCR, cagA of strain CPY3401 was sequenced. 74 H. pylori samples (72 cagA+) were obtained from the body and 56 samples (56 cagA +) obtained from the antrum. cagA size of 72 H. pylori strains from the body was mainly classified into 3 groups (short (48), middle (8), long (9), and others (7)) by PCR and all of that of 56 strains from the antrum except 2 was short. The size of cagA of isolated strains from the body is associated with enhanced gastritis, acid survival, and the location in the mucus. The long size cagA of which strain is acid sensitive, may be a strong selective pressure on strain that colonizes close to the host, which enhanced gastritis.     

Molecular fingerprinting of Helicobacter pylori strains from duodenal ulcer patients

AIMS: To characterize the molecular fingerprinting of Helicobacter pylori population isolated in duodenal ulcer patients treated with triple therapy. METHODS AND RESULTS: Gastric biopsy specimens from corpus and antrum, were cultured for H. pylori isolation. Helicobacter pylori eradication was evaluated after 4 and 16 weeks. DNAs of all isolates were characterized by random amplified polymorphic DNA typing and cagA gene was also detected. After the therapy, five patients harboured the microorganism at 4 weeks and two of them remained H. pylori positive at 16 weeks. The analysis of DNA fingerprinting of strains isolated from antrum and corpus of patients susceptible to treatment, showed similar patterns. Instead, when the therapy was not effective, strains isolated from sequential biopsies from initial and after 4 and 16 weeks, showed distinct fingerprintings and retained the cagA status, over time. CONCLUSIONS: The drugs used for therapy could exercise an effect in genotypical rearrangement among H. pylori cells. SIGNIFICANCE AND IMPACT OF THE STUDY: The variableness among H. pylori strains represents a way to challenge environmental stress.     

Apoptosis in Helicobacter pylori gastritis is related to cagA status

BACKGROUND: Helicobacter pylori infection increases gastric epithelial cell apoptosis; however, the influence of cagA status is still controversial. We aimed to investigate if cagA status is related to apoptosis in H. pylori gastritis at different anatomic sites of the gastric mucosa. MATERIALS AND METHODS: We studied by immunohistochemistry (streptavidin-biotin method) pro-apoptotic (Bax and Bak) and antiapoptotic (Bcl-2 and Bcl-x) proteins expression, scored from 0 to 4, in gastric biopsies, at the antrum (lesser and greater curvatures), incisura, and corpus (greater curvature) from 50 patients with H. pylori gastritis (22 males, 28 females, median age 40 years) and eight non-infected patients (6 males, median age 39.6 years). H. pylori and cagA status were determined by polymerase chain reaction. RESULTS: Apoptotic proteins were expressed in a granular pattern, in the cytoplasm of foveolar cells; Bax and Bak expression was higher than Bcl-2 and Bcl-x in most cases and was significantly higher in patients infected by cagA-positive strains than in those infected by cagA-negative strains (p = .001). Bak expression was higher at the lesser curvature (antrum and incisura) than in the other regions (p = .002) and was correlated with atrophy. Anti-apoptotic proteins were significantly more expressed at the antral lesser curvature than in the other regions of the stomach (Bcl-2: p = .02; Bcl-x: p < .001). CONCLUSIONS: Infection with cagA-positive strains is significantly associated with overexpression of pro-apoptotic proteins in the gastric mucosa, mainly at the antral lesser curvature, which may have a role on atrophy development. Anti-apoptotic proteins were also overexpressed at the lesser curvature, which may occur to keep epithelial cell turnover or might be related to malignant transformation.     

When Does Gastric Atrophy Develop in Japanese Children?

Background: Long-term Helicobacter pylori infection causes inflammatory sequelae such as atrophy and intestinal metaplasia in the stomach, which is thought to increase the risk of developing gastric malignancy. We previously reported that gastric atrophy can develop in Japanese children with H. pylori infection, predominantly in the antrum. However, detailed data about the age of children with atrophy are largely lacking.
Methods and results: In the present study, 131 children (79 boys) with H. pylori infection were re-analyzed for an association between age and the grade of gastric atrophy. The gastric antrum was histologically evaluated in all 131 patients and the corpus in 46 patients. Grade 2 and 3 antral atrophy was observed in 13 and one patients, respectively: the mean age was 12.1 years. Two patients (11 and 14 years old) had grade 2 corpus atrophy but no patients had grade 3. No significant difference was found in age among patients with grade 0, 1 and 2 or 3 atrophy in the antrum ( p =  .97) and in the corpus ( p =  .59). None of the patients with grade 2 or 3 atrophy had intestinal metaplasia either in the antrum or in the corpus.
Conclusions: The results of the present study require a careful interpretation because of the retrospective analysis. In high-risk countries of gastric cancer, however, eradicating H. pylori in childhood could prove more effective in preventing gastric atrophy, ultimately, the development of cancer.     

Molecular analysis of Helicobacter pylori populations in antral biopsies from individual patients using randomly amplified polymorphic DNA (RAPD) fingerprinting

Abstract In the present study, randomly amplified polymorphic DNA (RAPD) fingerprinting has been used to analyse multiple single colony isolates of Helicobacter pylori from antral biopsies in an attempt to ascertain whether or not multiple strains are present in individual patients using single biopsy samples. The RAPD fingerprints derived from single colonies obtained from the same biopsy specimen were in all cases indistinguishable. The previously noted heterogeneity between H. pylori strains from different individuals was confirmed. RAPD fingerprinting, combined with a simple method of template preparation, was shown to be an excellent method for H. pylori strain differentiation. The results of this study indicate that the H. pylori population is homogeneous in individual patients at a single gastric site.     

The Best Gastric Site for Obtaining a Positive Rapid Urease Test

Background Rapid urease tests (RUTs) provide a simple, sensitive method of detecting Helicobacter pylori infection.
Objectives. Our aim, therefore, was to determine whether the yield of detecting H. pylori infection by RUT varied depending on the site of gastric biopsy.
Materials and Methods. Gastric biopsies were obtained from 50 patients for RUT by use of hp fast (GI Supply, Camp Hill, PA). Biopsies were taken from the prepyloric greater curve antrum, from the gastric angle, and from the greater curve in mid-corpus. One biopsy specimen was placed in the RUT gel, and the biopsy from the adjacent mucosa was placed in formalin for subsequent histological evaluation by using the Genta stain. RUTs were examined and scored at intervals of 5, 10, 15, 30, and 45 minutes and after 1, 2, 4, and 24 hours.
Results. Fifty patients were entered in the test (150 RUTs), 32 having H. pylori infection. There were no false-positive RUTs (specificity, 100%). The gastric angle site was positive in 100%. The prepyloric site was positive in 87%, and the corpus site was positive in 84.4% ( p < .052 for angle or prepyloric antrum versus corpus). The most common pattern was for all to be positive (74%). The median time to positivity was similar with angle and prepyloric sites (37.5 and 60 minutes, respectively, p = not significant) and shorter than the corpus biopsy (180 minutes); ( p < .05 for angle or prepyloric antrum versus corpus).
Conclusion. The maximum probability for detecting H. pylori infection using a RUT is to obtain a biopsy from the gastric angle. To prevent missing a positive result when intestinal metaplasia is present, we recommend that (at a minimum) biopsies be taken from both the angle and the corpus.     

Detection of Helicobacter pylori and determination of clarithromycin susceptibility using formalin-fixed, paraffin-embedded gastric biopsy specimens by fluorescence in situ hybridization

BACKGROUND: Clarithromycin resistance and poor compliance to therapy are often responsible for Helicobacter pylori eradication therapy failure. AIM: To evaluate fluorescence in situ hybridization (FISH) as a nonculture method to simultaneously detect H. pylori and to identify clarithromycin resistance. METHODS: Fifty-four patients with dyspepsia (17 male, 37 female subjects; mean age, 46.5; range, 21-78 years) were studied. Two antrum and corpus biopsies were taken from each patient. Positive rapid urease test (RUT) and histopathologic examinations defined H. pylori positivity. A total of 108 formalin-fixed paraffin-embedded gastric mucosal biopsies were examined retrospectively by the FISH (seaFAST H. pylori Combi-Kit) method. RESULTS: Forty-five patients (83.3%) were H. pylori positive and 43 (95.5%) were also positive by FISH. There were two false-positive FISH results. Fourteen patients (31.1%) had clarithromycin-susceptible strains, 4 (8.9%) resistant strains, and 27 (60%) both susceptible and resistant strains. CONCLUSION: FISH results correlated well with H. pylori infection and were able to identify clarithromycin-susceptible and -resistant strains. This technique will be helpful in determining the bacterial density and the success of treatment where clarithromycin has been widely used in populations to increase the efficacy of the treatment and to clarify the treatment failure in vitro.     

Helicobacter pylori Infection and Family History of Gastric Cancer Decrease Expression of FHIT Tumor Suppressor Gene in Gastric Mucosa of Dyspeptic Patients

Background:  The expression of a fragile histidine triad (FHIT) protein is lost in stomach tumors. The study aimed at determining whether FHIT expression is affected by Helicobacter pylori infection, strain virulence ( vacA and cagA genes) and histopathological changes in the gastric mucosa of patients with functional dyspepsia having first-degree relatives with gastric cancer.
Materials and Methods:  Eighty-eight never-smoking patients with functional dyspepsia were selected for the study, and 48 of them had first-degree relatives with gastric cancer. Bacterial DNA amplification was used to identify H. pylori colonization. The level of FHIT gene expression was determined by qRT-PCR (mRNA) and Western blot (FHIT protein) analyses.
Results:  For patients having first-degree relatives with gastric cancer FHIT expression was lower (mRNA by ca. 40–45% and protein by 30%) compared with the control patients ( p  < .05). H. pylori infection decreased the FHIT mRNA level by 10–35% and the protein level by 10–20%. Bacterial strain vacA (+) cagA (+) lowered FHIT mRNA by ca. 30–35% in the antrum samples of both groups and in corpus samples of patients with first-degree relatives with gastric cancer ( p  < .05). The FHIT mRNA level was twice as high in control H. pylori- negative patients with intestinal metaplasia, compared with those with non-atrophic gastritis.
Conclusions:  The decreased FHIT gene expression associated with hereditary factors and with H. pylori infection, especially with vacA (+) cagA (+)-positive strains, may be related to gastric carcinoma development.     

Is Antrum or Corpus the Best Site for Culture of Helicobacter pylori?

Background Isolating Helicobacter pylori on culture media and performing antibiotic susceptibility testing is potentially the most useful tool for guiding antibiotic therapy, especially when antimicrobial resistance is suspected. The aim of this study was to determine whether the yield of H. pylori culture was related to the site from which the gastric specimen was obtained either before or after therapy.
Methods. Gastric mucosal biopsies from the antrum and the corpus of the stomach were cultured. H. pylori status was determined by histological assessment using the Genta stain.
Results. Fifty-two patients with documented H. pylori infection were studied: Twenty-three were tested before antibiotic therapy and 29 after therapy had failed. In 47 patients (90%), both antral and corpus culture specimens were positive. In 5 patients (10%), only one site was positive, with three false-negative antral and two false negative corpus cultures. The overall sensitivity of culture in detecting H. pylori infection was 95% (95% confidence interval = 89–98%) and was not significantly different for the antrum or corpus, either before or after therapy.
Conclusion. Culture of gastric biopsies from either the antrum or the corpus has an excellent diagnostic yield even in patients who failed antimicrobial therapy.     

Gastric mucus glycoprotein in different rat strains

The extent of gastric damage induced by aspirin was found to differ according to rat strain. The occurrence of ulcers varied, from high to low, in the following strain order: Donryu, Sprague-Dawley (SD) and Wistar. The content of corpus mucus glycoprotein was essentially the same in all the strains: about 6 mg as hexose of dry tissue. Antral mucus glycoprotein content increased in the order Wistar, SD and Donryu: 7.1, 8.3 and 9.1 mg, respectively. Gastric mucus glycoprotein carbohydrate composition was essentially the same in all three strains. The relatively low proportions of N-acetylglucosamine, galactose and sialic acid from the antrum was a characteristic feature in contrast to mucus glycoprotein from the corpus which contained a high proportion of these sugars.     

Mixed-infection of antibiotic susceptible and resistant Helicobacter pylori isolates in a single patient and underestimation of antimicrobial susceptibility testing

Antibiotic resistance among Helicobacter pylori has been increasing worldwide and has begun to affect the overall efficacy of current antibiotic regimens adversely. We examined 220 pairs of H. pylori isolates obtained from both the antrum and corpus of separate patients; 109 (50%) harbored antibiotic-resistant H. pylori: amoxicillin (0.5%), clarithromycin (5.9%), furazolidone (1.4%), metronidazole (45.5%), nitrofurantoin (1.4%), and tetracycline (6.8%). Heteroresistance among the two biopsy sites from each patient was present in 41 of the 109 patients (38%) with antibiotic resistant H. pylori (e.g. 34% with resistant strains would be misclassified as susceptible if a biopsy of the antrum alone used for antimicrobial susceptibility testing). DNA fingerprinting genotype analysis was carried out on the 41 pairs of isolates with heteroresistance. While different patients had different fingerprinting patterns, each pair of isolates showed identical or similar fingerprinting patterns. These results suggest that antibiotic-resistant H. pylori typically develop from pre-existing susceptible strain rather than coinfection with a different strain. The minor differences in genotype (degeneration of genotype) seen reflect one of the processes for development of genetic diversity in H. pylori. No biopsy single site can be considered representative for antimicrobial susceptibility testing.     

DNA damage and repair in Helicobacter pylori-infected gastric mucosa cells

Helicobacter pylori is a common human pathogen and its infection is believed to contribute to gastric cancer. Impaired DNA repair may fuel up cancer transformation by the accumulation of mutation and increased susceptibility to exogenous carcinogens. To evaluate the role of infection of H. pylori in DNA damage and repair we determined: (1) the level of endogenous basal, oxidative and alkylative DNA damage, and (2) the efficacy of removal of DNA damage induced by hydrogen peroxide and the antibiotic amoxicillin in the H. pylori-infected and non-infected GMCs. DNA damage and the efficacy of DNA repair were evaluated by the alkaline single cell gel electrophoresis (comet assay). Specific damage to the DNA bases were assayed with the DNA repair enzymes formamidopyrimidine-DNA glycosylase (Fpg) recognizing oxidized DNA bases and 3-methyladenine-DNA glycosylase II (AlkA) recognizing alkylated bases. The level of basal and oxidative DNA in the infected GMCs was higher than non-infected cells. H. pylori-infected GMCs displayed enhanced susceptibility to hydrogen peroxide than control cells. There was no difference between the efficacy of DNA repair in the infected and non-infected cells after treatment with hydrogen peroxide and amoxicillin. Our results indicate that H. pylori infection may be correlated with oxidative DNA damage in GMCs. Therefore, these features can be considered as a risk marker for gastric cancer associated with H. pylori infection and the comet assay may be applied to evaluate this marker.     

淮南地区幽门螺杆菌感染个体菌株基因多态性与感染结局的影响

目的:探讨淮南地区幽门螺杆菌感染个体菌株基因多态性及其与感染结局的影响。方法:选取125例幽门螺杆菌(H.pylori,HP)感染的慢性胃炎、消化性溃疡患者,常规获取胃窦、胃体部粘膜,进行HP分离、培养,提取HP基因组DNA,采用随机扩增多态性DNA(RAPD)指纹分析法检测菌株基因多态性;125例患者均给予质子泵抑制、H2受体拮抗剂、铋剂为基础的三联或四联疗法治疗,治疗后4~6周进行14C-尿素呼气试验评估Hp根除情况;获取HP根除失败患者的胃窦、胃体黏膜进行HP分离、培养、鉴定,并采用RAPD指纹分析法检测菌株来源,评估HP基因多态性对治疗结局的影响。结果:cagA、iceA1、iceA2、vacAs1、vacAm1、babA2阳性率分别为92.80%、36.00%、93.60%、93.60%、29.50%、53.50%,cagA、iceA2、vacAs阳性率均高于其他基因类型阳性率(P0.05或P0.01),其他基因类型阳性率比较差异无统计学意义(P0.05)。经治疗后HP根除率为86.4%(107/125),14.4%(18/125)根除失败;18例根除失败患者中,15例患者治疗前后的菌株具有相同的指纹图谱,证实为原菌株复发,其中cagA、iceA1、iceA2、vacAs1、vacAm1、babA2阳性率分别为93.33%、13.33%、86.67%、93.33%、6.67%、20.00%,cagA、iceA2、vacAs阳性率均高于其他基因类型阳性率(P0.05或P0.01)。结论:cagA+、vacAs+、iceA2+为淮南地区HP感染的优势基因型,该基因型易导致HP根除失败;未发现babA2与HP感染结局存在相关性。     

Negative association between Helicobacter pylori infection and reflux esophagitis in older patients: case-control study in Japan

Background. Recent studies have clarified a close association between H. pylori infection and gastritis, peptic ulcer disease, and gastric cancer, but there is little information concerning the relationship between H. pylori infection and reflux esophagitis (RE). We investigated the relationship between H. pylori , RE, and corpus gastritis.
Subjects and Methods. Ninety-five patients with RE and 190 sex- and age-matched asymptomatic healthy controls demonstrating no localized lesions in the upper GI tract were studied and evaluated for H. pylori infection, histologic gastritis, serum gastrin, and pepsinogens (PGs).
Results. H. pylori infection was significantly lower in RE patients than in asymptomatic controls (41% vs. 76%, p < .01). Histologic gastritis of both the antrum and corpus was significantly less frequent (antrum; p < .01, corpus; p < .01), and serum levels of PGI and the PG I/II ratio were significantly higher in RE patients than in controls (PGI; p < .05, PG I/II ratio; p < .01). When the subjects were divided into two age groups (59 years of age and younger and 60 years of age and older), a significant difference was found only among patients over 60 years of age (29% vs. 85%, p < .01). Among subjects in this age group, gastritis in both the antrum and corpus were significantly milder in RE patients than in controls. Although the prevalence of H. pylori infection was similar between the two groups of patients under 59 years of age, corpus gastritis was significantly milder in patients than in controls ( p < .05).
Conclusions. A significantly low prevalence of H. pylori infection was found in RE patients over 60 years of age but not in those under 59 in comparison with sex- and age-matched controls. The relative lack of corpus gastritis might play a role in the pathogenesis of RE in our population through preservation of the acid secretion area.     

Subtractive hybridization analysis of gastric diseases-associated Helicobacter pylori identifies peptidyl-prolyl isomerase as a potential marker for gastric cancer

Helicobacter pylori, a microaerophilic Gram-negative bacterium, is known to cause chronic gastritis, peptic ulcer and gastric cancer. Genes that are present in certain isolates may determine strain-specific traits such as disease association and drug resistance. In order to understand the pathogenic mechanisms of gastric diseases, identify molecular markers of the diseases associated with H. pylori strains and provide clues for target treatment of H. pylori-related diseases, a subtracted DNA library was constructed from a gastric cancer-associated H. pylori strain and a superficial gastritis-associated H. pylori strain by suppression subtractive hybridization. The presence of gastric cancer-specific genes was identified by dot blot hybridization, DNA sequencing and PCR-based screening. Twelve gastric cancer-specific high-copy genes and nine low-copy genes were found in gastric cancer compared with the superficial gastritis strain. These genes were confirmed by PCR analysis of H. pylori isolates. Notably, peptidyl-prolyl cis-trans isomerase (PPIase) was detected positively in 11 out of 22 (50%) gastric cancer-associated H. pylori strains. In contrast, <24% of the H. pylori strains from superficial gastritis showed positive results. Given the potential role of PPIases in cell growth, apoptosis and oncogenic transformation, our results suggest that PPIase may represent a novel marker and potential therapeutic target for gastric cancer.     

幽门螺杆菌在胃内定植的相关影响因素

胃内定植是引起幽门螺杆菌(Helicobacter pylori,H.pylori)感染的先决条件。H.pylori可穿过胃黏液层并与胃上皮细胞相互作用。这个定植过程主要受到H.pylori动力和尿素酶的影响。同时H.pylori形态、胃内pH、外膜蛋白及益生菌等也在其中扮演重要角色。该研究主要对H.pylori胃内定植过程中的相关影响因素进行综述。     

Conservation and microdiversity of the phospholipase A (pldA) gene of Helicobacter pylori infecting dyspeptics from different countries

Phospholipase activity is important in bacterial pathogenicity and could contribute to the pathogenic role of Helicobacter pylori by degradation of the gastric mucus, and in maintaining long-term colonisation. Our aim was to determine the degree of variation in the phospholipase A gene (pldA) of H. pylori from different geographic locations, and to investigate links between pldA genotype and clinical disease severity, as well as with variation in cagA status and vacA genotypes. PCR-restriction fragment length polymorphism (RFLP) analysis with MboI and HaeIII was used to study 124 isolates from 10 countries that included the two genome-sequenced strains (26695 and J99), as well as Tx30a and NCTC 11637 (type strain). The 925-bp pldA fragment was amplified with a frequency of 90%. The presence of pldA was confirmed in the other strains using an alternative forward primer. Isolates were distinguished by PCR-RFLP analysis with 10 MboI and four HaeIII restriction patterns that combined to give 25 distinct pldA RFLP types. The pldA M2H2 strain genotype was most common (20%) in the UK but similar strains came from several other countries. Microdiversity was evident in pldA sequences of strains representing different RFLP types, and five M2H2 strains each had a distinct pldA sequence type. Intragenic variation was independent of gastric disease severity as well as strain cagA status and vacA genotype, with the exception of eight geographically diverse strains all with the pldA M4H3/cagA+/vacA s1m1 genotype predominantly from peptic ulcer patients. The study indicated a spectrum of genotypic variants and was supportive of a pldA function in H. pylori colonisation and persistence rather than in chronicity of infection.     

Helicobacter pylori cag pathogenicity island-positive strains induce syndecan-4 expression in gastric epithelial cells

Helicobacter pylori is recognized as the main cause of gastritis and is associated with gastric carcinogenesis. Syndecan-4 represents the major source of heparan sulfate (HS) in the gastric cells. HS proteoglycans expressed on the cell surface constitute targets for H. pylori at the early stage of infection. The aim of this study was to determine whether H. pylori induction of syndecan-4 expression is affected by the virulence characteristics of the infecting strain, namely the cytotoxic-associated gene ( cag ) pathogenicity island (PAI). We observed that individuals infected with highly pathogenic H. pylori strains express syndecan-4 in the foveolar epithelium of the gastric mucosa. The association between the cag PAI status of the infecting strain and syndecan-4 expression was further demonstrated by infection of gastric epithelial cell lines with a panel of cag PAI⁺ and cag PAI⁻ H. pylori strains, showing that expression of syndecan-4 was significantly increased in response to infection with the highly pathogenic strains. Moreover, infection of gastric cells with cag A and cag E mutant strains further confirmed that syndecan-4 induction is dependent on an intact cag PAI. The present study shows that highly pathogenic H. pylori strains induce syndecan-4 expression, both in human gastric mucosa and in gastric cell lines, in a cag PAI-dependent manner.