Genetic Susceptibility of Gastroduodenal Disease in Ethnic and Regional Diversity

No abstract available.

Relationship between Helicobacter pylori Virulence Genes and Clinical Outcomes in Saudi Patients

Helicobacter pylori has been strongly associated with gastritis, gastric and duodenal ulcers, and it is a risk factor for gastric cancer. Two major virulence factors of H. pylori have been described: the cytotoxin-associated gene product (cagA) and the vacuolating toxin (vacA). Since considerable geographic diversity in the prevalence of H. pylori virulence factors has been reported, the aim of this work was to determine if there is a significant correlation between different H. pylori virulence genes (cagA and vacA) in 68 patients, from Saudi Arabia, and gastric clinical outcomes. H. pylor was recognized in cultures of gastric biopsies. vacA and cagA genes were detected by polymerase chain reaction (PCR). The cagA gene was obtained with 42 isolates (61.8%). The vacA s- and m- region genotypes were determined in all strains studied. Three genotypes were found: s1/m1 (28%), s1/m2 (40%) and s2/m2 (26%). The s2/m1 genotype was not found in this study. The relation of the presence of cagA and the development of cases to gastritis and ulcer was statistically significant (P < 0.05). The study showed a significant correlation between the vacA s1/m2 genotype and gastritis cases, and a significant correlation between vacA s1/m1 genotype and peptic ulcer cases. The results of this study might be used for the identification of high-risk patients who are infected by vacA s1/m1 genotype of H. pylori strains. In conclusion, H. pylori strains of vacA type s1 and the combination of s1/m1 were associated with peptic ulceration and the presence of cagA gene.

DNA Double Strand Breaks in Gastric Epithelium with Helicobacter pylori Infection / 대한소화기학회지

BACKGROUND/AIMS: DNA double strand breaks (DSB) is one of the critical types of DNA damage. If unrepaired, DSB is accumulated in the nucleus of cells, the cells become apoptotic or transform to tumor by way of genomic instability. Some of malignant cancers and its premalignant lesions were proven to have DSB in their nuclei. There was no report that Helicobacter pylori (H. pylori), the gastric carcinogen, induce DNA DSB in gastric epithelium in vivo. The aim of this study was to investigate whether H. pylori induce DSB in the gastric epithelial cells of chronic gastritis. METHODS: Immunohistochemical stains were performed for the DSB markers, phospho-53BP1 and gammaH2AX, in the gastric epithelium derived from 44 peptic ulcer disease patients before and after H. pylori eradication. DNA fragmentation assay was performed in the cell line to investigate the DNA damage by H. pylori infection. RESULTS: The mean expression score of gammaH2AX was significantly higher in the H. pylori infected gastric epithelium as compared to the H. pylori eradicated gastric epithelium (8.8+/-5.5 vs. 6.2+/-5.3 respectively; p=0.008). The expression score of phospho-53BP1 between before and after eradication of H. pylori was not statistically different, but tended to be higher in H. pylori infection. DNA fragmentation was developed significantly more in the cell lines after infection with H. pylori. CONCLUSIONS: DSB of DNA damage was typical feature of H. pylori infection in the gastric epithelium.

Evolutionary dynamics of Helicobacter pylori cagA and vacA genes in Iran and their association with clinical outcomes

There is a relationship between specific genotypes of Helicobacter pylori cagA and vacA genes and the increased risk of peptic ulcer diseases and gastric cancer. These genes also possess strong patterns of geographical differentiation. The present study aims to determine the patterns of variation of the virulence genes in Iran and their association with clinical status. Sequence fragments for cagAand vacA were obtained from a total of 147 H. pylori isolates from diverse geographical and ethnic sources within Iran. We used phylogenetic methods to determine the patterns of allelic diversity, and the relationship between evolutionary lineages and clinical status. Phylogenetic analyses of Iranian cagA gene disclosed four lineages, whereas the vacA gene had two distinct lineages. The cagA lineage II showed extensive genetic diversity compared with lineage I. cagA lineages III and IV disclosed mixed ancestries with recombinant nucleotides that originated from lineages I and H Iranian strains with vac A lineage II genotype were significantly cagA+ [> 90%, p = 0.0] and correlated with a higher rate of peptic ulcers in infected individuals [p =0.003]. Most strains in the cagA lineage I showed a vacA lineage II genotype [p = 0.003] and significantly correlated with an increased risk of peptic ulcers in infected individuals [p = 0.022]. Strains with cagA lineage III genotype significantly correlated with gastritis [p = 0.0]. The increased level of allelic diversity in the virulence genes shows strong evolutionary dynamics, resulting in the emergence of new clonal genealogies of the cagA gene within Iran. Particular lineages of the Iranian cagA and vac A genes correlate with peptic ulcer diseases

[Assessment the relationship of cagA gene with different gastroduodenal diseases in Helicobacter pylori infected patients]

The gastric pathogen Helicobacter pylori is introduced as an etiologic agent of gastritis and peptic ulcer and is associated with development of gastric adenocarcinoma. One of the most studied virulence marker of H. pylori is cytotoxin-associated gene A [cagA] with significant geographical heterogeneity around the world. This study was undertaken to assess the status of cagA gene of H .pylori strains infecting Iranian patients suffering from various gastrointestinal diseases and to evaluate the detection of this gene as a screening marker of high-risk patients. In this study, 180 patients [Mean age: 44 years] with upper gastrointestinal manifestations referred for endoscopy to Amir-Alam Hospital or Cancer Institute in Tehran were included. Among one hundred twenty H. pylori infected patients 81, 17 and 22 had non-ulcer dyspepsia [NUD], peptic ulcer disease [PUD], and gastric carcinoma [GC] respectively. Tissue samples were homogenized and incubation was performed up to 5 days. Identification was based on morphology under Gram staining and biochemical tests. The status of conserved region of cagA gene was determined by gene specific PCR. For statistical analysis, chi square test was used. Among the 180 of studied patients, 120 H. pylori strains were isolated. One hundred and one [84.2%] of the tested strains were positive for cagA and the remaining strains [15.8%] were negative. All of gastric cancer cases were infected with cagA -positive strains. The cagA -positive strains were significantly associated with GC as compared with NUD [p < 0.05] but this association did not gain statistical significance for other clinical outcomes. Although the possession of cagA is associated with GC when compared to NUD, due to the uniform distribution of cagA in all other disease categories detection of cagA alone can not be considered as a discriminative marker for a specific clinical outcome. Hence, the study of other virulence determinants and functional characteristics of cagA gene might be necessary for screening high risk patients

[DNA fingerprinting of h. pylori isolates from Iranian patients by REP-PCR]

H. pylori has been implicated in peptic diseases, some with detrimental consequences such as ulcer or cancer. Since considerable genetic heterogeneity has been observed within H. pylori population worldwide, it appears an ideal achievement to recruit PCR-based methods and design genetic markers which recognize isolates from normal and symptomatic individuals. In this study 61 H. pylori isolates from dyspeptic patients were fingerprinted by REP-PCR. REP-PCR was performed on extracted DNAs of 61 H. pylori isolates from 39 normal, 18 ulcer and 4 cancer patients. Synthetic 18-nt primers, specific for interspersed repetitive elements in the bacterial genome, were recruited. PCR conditions were optimized and reproducibility of the reactions were confirmed. The size and number of PCR products were determined and DNA fingerprints of all isolates were analyzed by NTSYSpc programme, and dendrograms were generated. Results: Among 39 H. pylori isolates from normal patients 28 comprised a distinct cluster and 5 clustered along with isolates from ulcer patients. The remaining 6 isolates comprised a separate cluster distinct from other groups. Among 18 isolates from ulcer patients, 17 classified in a specific cluster, only one isolate was clustered along with isolates from normal patients. Isolates from cancer patients consisted a quite distinct cluster. In this study REP-PCR was used to show that majority of isolates from normal, ulcer, and cancer patients have distinct fingerprints which can be recruited for predicting the outcome of the infection with certain H. pylori isolates. It is concluded that REP-PCR is an effective and reproducible technique for fingerprinting H. pylori isolates from different human origins

[Study of the CagA gene prevalence in helicobacter pylori strains isolated from patients with upper gastrointestinal disorders in Iran]

Helicobacter pylori commonly is associated with gastritis: but only sometimes it causes clinically significant diseases such as gastric and duodenal ulcer. The development of disease depends on the virulence of the infecting H. pylori strain, the susceptibility of the host, and environment co-factors. The cytotoxin associated protein encoded by cagA gene is an important virulence factor that is produced by some H. pylori strains, and has been used as virulence marker in some populations. The aim of the study was to examine the prevalence of cagA gene in the isolated strains of H. pylori from patients with dyspeptic disease and to investigate the association of cagA gene and the severity of H. pylori related diseases in Iran. In this study, biopsy specimens were obtained from the antrum of 180 patients. After isolation of H. pylori and its DNA by standard methods, polymerase chain reaction [PCR] technique was used for detection of cagA bacterial gene. 92 out of the 180 patients had H. pylori strains. 70% were cagA gene positive. All patients with peptic ulcer [100%] and 44 out of 72 [61%] patients with non-ulcer dyspepsia were cagA positive [p<0.01]. There was significant difference in frequency of cagA gene in peptic ulcer disease and non-ulcer dyspepsia [p<0.01]. It showed that the risk of PUD in patients with cagA+ H. pylori infection may be higher than in those with cagA- H. pylori infection

[Genotype variation in H. pylori isolates from Iranian patients by RAPD-PCR]

Do H. pylori isolates from normal and dyspeptic patients have similar genetic profiles? Since genotype variation occurs within H. pylori population with high frequency, it is tempting to exploit techniques such as RAPD-PCR to examine the possible correlation between specific H. pylori genotypes and different peptic diseases. In this study, H. pylori isolates from different dyspeptic patients were genotyped by RAPD-PCR. H. pylori isolates from 66 patients, 41 normal, 21 with ulcer, and 4 with cancer were cultured, DNAs were extracted by phenol-chloroform. RAPD-PCR was optimized, using 10-nt primers of arbitrary sequences [1281, 1254, 1247] and isolate-specific fingerprints were generated. Analysis of PCR products on agarose gel was performed using NTSYSpc program. Dendrograms were calculated according to Jaccard and Nei. According to differences in genetic profiles, H. pylori isolates were clustered into 4 distinct groups: 2 groups consisted of isolates from normal patients, 2 groups of isolates from patients with ulcer, and isolates from patients with cancer were clustered along with isolates from normal and ulcer patients. Furthermore, isolates from ulcer patients appeared in the cluster related to isolates from normal patients. Genetic variation is quite frequent within H. pylori populations; thus RAPD-PCR is an effective technique to reveal genetic diversity of isolates from different dyspeptic patients. In this study, H. pylori strains were clustered into 4 groups: 2 groups from normal patients, and 2 from patients with ulcer. Further studies in larger populations will help to correlate a certain peptic disease to specific strain of H. pylori

Relevance of vacA Genotypes of Helicobacter pylori to cagA Status and Its Clinical Outcome

BACKGROUND: Determination of vacA mosaicism may be important because specific Helicobacter pylori vacA genotype can be used to predict different clinical outcome. The aim of this study was to assess the relationship of vacA genotypes of Helicobacter pylori to cagA status and its development of peptic ulcer diseases in Korean patients. METHODS: Gastric biopsy specimens were obtained from 53 patients with gastric ulcer(GU), 57 with duodenal ulcer (DU) and 26 with chronic gastritis(CG) patients; all patients were infected with Helicobacter pylori. Bacterial mRNAs in the gastric mucosa were amplified by RT-PCR, using synthetic oligonucleotide primers specific for the vacA and the cagA gene. Patients with vacA s1 subtype were further examined to determine whether they had s1a or s1b subtype. RESULTS: There was no correlation in frequency of vacA s1 and/or s1a genotype between CG and either GU or DU, as the vacA s1 and s1a/m1 were present in the majority of strains independent of clinical status(s1 ; 100.0% versus 94.3 % or 93.0 % and s1a/m1 ; 76.9% versus 62.3% or 64.9%, res pectively). Likewise, there was no difference in the prevalence of the cagA gene between CG and either GU or DU patients (92.3% versus 90.6% or 98.2%, respectively). In addition, the cagA-negative status did not predict the presence of vacA s2 genotype. CONCLUSION: These results strongly suggest that either cagA or vacA s1 and/or s1a is not proved to be a useful marker to distinguish disease-specific Helicobacter pylori strains for the development of peptic ulcer diseases in Korean patients.