Helicobacter pylori cagA status and s and m alleles of vacA in isolates from individuals with a variety of H. pylori-associated gastric diseases

Functional and biochemical characterisation of remote homologues of type IV pili proteins PilN and PilO in Helicobacter pylori

Helicobacter pylori encodes homologues of PilM, PilN and PilO from bacteria with Type IV pili, where these proteins form a pilus alignment complex. Inactivation of pilO changes H. pylori motility in semi-solid media, suggesting a link to the chemosensory pathways or flagellar motor. Here, we showed that mutation of the pilO or pilN gene in H. pylori strain SS1 reduced the mean linear swimming speed in liquid media, implicating PilO and PilN in the function, or regulation of, the flagellar motor. We also demonstrated that the soluble variants of H. pylori PilN and PilO share common biochemical properties with their Type IV pili counterparts which suggests their adapted function in the bacterial flagellar motor may be similar to that in the Type IV pili.

Biochemical characterization of paralyzed flagellum proteins A (PflA) and B (PflB) from Helicobacter pylori flagellar motor

Motility by means of flagella plays an important role in the persistent colonization of Helicobacter pylori in the human stomach. The H. pylori flagellar motor has a complex structure that includes a periplasmic scaffold, the components of which are still being identified. Here, we report the isolation and characterization of the soluble forms of two putative essential H. pylori motor scaffold components, proteins PflA and PflB. We developed an on-column refolding procedure, overcoming the challenge of inclusion body formation in Escherichia coli. We employed mild detergent sarkosyl to enhance protein recovery and n-dodecyl-N,N-dimethylamine-N-oxide (LDAO)-containing buffers to achieve optimal solubility and monodispersity. In addition, we showed that PflA lacking the β-rich N-terminal domain is expressed in a soluble form, and behaves as a monodisperse monomer in solution. The methods for producing the soluble, folded forms of H. pylori PflA and PflB established in this work will facilitate future biophysical and structural studies aimed at deciphering their location and their function within the flagellar motor.

Pal power: Demonstration of the functional association of the Helicobacter pylori flagellar motor with peptidoglycan-associated lipoprotein (Pal) and its preliminary crystallographic analysis

The bacterial flagellar motor is a molecular nanomachine, the assembly and regulation of which requires many accessory proteins. Their identity, structure and function are often discovered through characterisation of mutants with impaired motility. Here, we demonstrate the functional association of the Helicobacter pylori peptidoglycan-associated lipoprotein (HpPal) with the flagellar motor by analysing the motility phenotype of the ∆pal mutant, and present the results of the preliminary X-ray crystallographic analysis of its globular C-terminal domain HpPal-C. Purified HpPal-C behaved as a dimer in solution. Crystals of HpPal-C were grown by the hanging drop vapour diffusion method using medium molecular weight polyethylene glycol (PEG) Smear as the precipitating agent. The crystals belong to the primitive orthorhombic space group P1 with unit cell parameters a = 50.7, b = 63.0, c = 75.1 Å. X-ray diffraction data were collected to 1.8 Å resolution on the Australian Synchrotron beamline MX2. Calculation of the Matthews coefficient (VM=2.24 Å3/Da) and molecular replacement showed that the asymmetric unit contains two protein subunits. This study is an important step towards elucidation of the non-canonical role of H. pylori Pal in the regulation, or function of, the flagellar motor.

Relationship between weight gain and survival rate in patients with metastatic lung cancer

Background: Lung cancer accounts for about 13% of all cancers and about 60% of patients with lung cancer also experience weight loss during treatment. There seems to be a clear correlation between the therapeutic outcomes of patients based on their weight changes during treatment. The aim of this study was to investigate the relationship between weight changes during and after treatment and the therapeutic outcomes of a patient with metastatic lung cancer.

Methods: This cohort study was performed on patients with the diagnosis of non-surgical metastatic lung cancer referred to Hematology and Oncology Clinic, Rasoul-e-Akram Hospital. Patients were divided into two groups with a weight gain of more than 5% and a weight gain of 5% and less. The information was entered into the SPSS version 21 software. In the descriptive analysis, mean and standard deviation (SD) were used. To compare quantitative variables, independent samples t-test, Mann-Whitney, chi-square or Fisher exact tests were used to compare qualitative variables and correlation test was used to determine the correlation between quantitative data. Survival curves were used to show differences in two groups of studies. A regression model was used to calculate the hazard ratio. The significance level was less than 0.05.

Results: Sixty patients, including 40 males (66.7%) and 20 females (33.3%) were studied. The mean age of patients was 62.22±9.00 years (43-83 years). The mean weight changes in the patients were -1.28±6.11 kg (-16 to 16kg). Forty-seven patients (78.3%) had weight gain less than 5%. There was no significant difference in overall survival (OS) and progression-free survival (PFS) according to weight gain.

Conclusion: Finally, the findings of the study showed that, despite the fact that PFS and OS in the weight gain group were greater than 5% of the original weight; the difference was not statistically significant.

Relationship between ureB Sequence Diversity, Urease Activity and Genotypic Variations of Different Helicobacter pylori Strains in Patients with Gastric Disorders

Association of the severity of Helicobacter pylori induced diseases with virulence entity of the colonized strains was proven in some studies. Urease has been demonstrated as a potent virulence factor for H. pylori. The main aim of this study was investigation of the relationships of ureB sequence diversity, urease activity and virulence genotypes of different H. pylori strains with histopathological changes of gastric tissue in infected patients suffering from different gastric disorders. Analysis of the virulence genotypes in the isolated strains indicated significant associations between the presence of severe active gastritis and cagA+ (P = 0.039) or cagA/iceA1 genotypes (P = 0.026), and intestinal metaplasia and vacA m1 (P = 0.008) or vacA s1/m2 (P = 0.001) genotypes. Our results showed a 2.4-fold increased risk of peptic ulcer (95% CI: 0.483-11.93), compared with gastritis, in the infected patients who had dupA positive strains; however this association was not statistically significant. The results of urease activity showed a significant mean difference between the isolated strains from patients with PUD and NUD (P = 0.034). This activity was relatively higher among patients with intestinal metaplasia. Also a significant associa-tion was found between the lack of cagA and increased urease activity among the isolated strains (P = 0.036). While the greatest sequencevariation of ureB was detected in a strain from a patient with intestinal metaplasia, the sole determined amino acid change in UreB sequence (Ala201Thr, 30%), showed no influence on urease activity. In conclusion, the supposed role of H. pylori urease to form peptic ulcer and advancing of intestinal metaplasia was postulated in this study. Higher urease activity in the colonizing H. pylori strains that present specific virulence factors was indicated as a risk factor for promotion of histopathological changes of gastric tissue that advance gastric malignancy.

Helicobacter pylori vacuolating cytotoxin genotypes and preneoplastic lesions or gastric cancer risk: a meta-analysis

BACKGROUND AND AIM

Disease progression to gastric cancer (GC) occurs in only a small proportion of Helicobacter pylori (H.  pylori) infected patients. The bacterium vacuolating cytotoxin A (vacA) gene polymorphisms may determine the clinical consequences. We examined the strength of this association in adult-infected populations and modeled the impact of mean age-standardized incidence rates (ASRs) of GC as a hypothesized moderator variable.

METHODS

Pooled relative risk (RR) estimates were calculated. Subgroup, sensitivity, and meta-regression analyses were conducted.

RESULTS

Totally, 33 studies (1446 cases/2697 controls) were analyzed. The vacA-s1 genotype was significantly associated with an increased risk of atrophic gastritis(AG), intestinal metaplasia(IM), and GC (RR = 1.116, 95% CI, 1.019-1.222; RR = 1.418, 95% CI, 1.035-1.942; and RR = 1.333, 95% CI, 1.115-1.593, respectively); however, the vacA m1 genotype strongly increased the risk of IM and GC, but not AG (RR = 1.571, 95% CI, 1.247-1.980 and RR = 1.431, 95% CI, 1.180-1.735, respectively). The vacA s1m1 allelic combination was linked to an increased risk of GC. The m1-type of vacA was more potent than s1 for predicting the risk of GC within the subgroups with the mean ASRs of 11/100,000-19/100,000 and less than 10/100,000. The meta-regression analysis indicated that the ASR of GC modified the association between H.  pylori genotypes and GC risk, where the estimated risk was significantly decreased with increasing the mean ASRs of GC (P-values = 0.025, 0.00009, and 0.0005 for s1, m1, and s1m1, respectively).

CONCLUSIONS

The H. pylori vacA-s1 and vacA-m1 allelic variants strongly increased susceptibility to IM and GC; however, only s1 showed an association with AG. These associations were largely influenced by geographic variations in the GC incidence rate.

Helicobacter pylori CagA and VacA genotypes and gastric phenotype: a meta-analysis

BACKGROUND

CagA+ and vacuolizing cytotoxin (VacA)-specific strains of Helicobacter pylori have been associated with different risks for developing gastric lesions. We aim to summarize a possible association between these genotypes and the risk for developing different gastric phenotypes.

MATERIALS AND METHODS

A MEDLINE database (PubMed) search was performed and a meta-analysis conducted.

RESULTS

Forty-four studies were retrieved, all with either a case-control (n=13) or cross-sectional (n=31) design, including 17 374 patients. CagA positivity was associated with an increased risk for gastric cancer [odds ratio (OR) 2.09 (95% confidence interval (CI), 1.48-2.94)] compared with that in individuals without gastric lesions [OR 2.44 (95% CI 1.27-4.70)] and in those with previously identified gastritis. In addition, there was an increased risk for peptic ulcer disease [OR 1.69 (95% CI 1.12-2.55)]. Individuals harboring the H. pylori strains VacA s1 (vs. s2), m1 (vs. m2), s1m1 (vs. s1m2), and s1m1 (vs. s2m2) had an increased risk for development of cancer [OR of 5.32 (95% CI 2.76-10.26), 2.50 (95% CI 1.67-3.750), 2.58 (95% CI 1.24-5.38), and 4.36 (95% CI 2.08-9.10), respectively]. s1m1 strains (vs. s2m2) were also associated with peptic ulcer disease [OR 2.04 (1.01-4.13)].

CONCLUSION

Our results indicate that individuals infected with CagA+ H. pylori strains and those infected with VacA s1 and m1 strains have an increased risk for gastric cancer. Cohort studies are welcome to integrate this information in the management of at-risk individuals such as those with precancerous cancer conditions and/or a family history of gastric cancer.

Helicobacter pylori vacA and cagA genotypes in patients from northeastern Brazil with upper gastrointestinal diseases

Helicobacter pylori causes chronic gastric inflammation and significantly increases the risk of duodenal and gastric ulcer disease and distal gastric carcinoma. In this study, we evaluated the Helicobacter pylori vacA and cagA genotypes in patients from a Brazilian region where there is a high prevalence of gastric cancer. Polymerase chain reaction (PCR) was used to investigate vacA mosaicism and cagA status in the gastric mucosa of 134 H. pylori-positive patients, including 76 with gastritis: 28 with peptic ulcer disease and 30 with gastric cancer. The s1m1 variant was the predominant vacA genotype observed, whereas the s1 allele was more frequently observed in patients with more severe diseases associated with H. pylori infection [p = 0.03, odds ratio (OR) = 5.72, 95% confidence interval (CI) = 1.15-38.60]. Furthermore, all of the s1 alleles were s1b. Mixed vacA m1/m2 strains were found more frequently in patients with gastric cancer and a cagA-positive status was significantly associated with gastric cancer (p = 0.016, OR = 10.36, 95% CI = 1.35-217.31). Patients with gastric cancer (21/21, 100%, p = 0.006) or peptic ulcers (20/21, 95%, p = 0.02) were more frequently colonised by more virulent H. pylori strains compared to gastritis patients (41/61, 67.2%). In conclusion, in the northeastern of Brazil, which is one of the regions with the highest prevalence of gastric cancer in the country, infection with the most virulent H. pylori strains, carrying the cagA gene and s1m1 vacA alleles, predominates and is correlated with more severe H. pylori-associated diseases.

Characterization of virulence genes cagA and vacA in Helicobacter Pylori and their prevalence in gastrointestinal disorders

Prevalence of H. pylori infection was determined using cultures of gastric biopsy samples of patients attended at the academic hospital of the Federal University of Paraná, Curitiba, Paraná, Brazil. Molecular methods were used to characterize the cagA and vacA genes from bacterial isolates associated with different diseases presented by patients. Out of a total of 81, forty-two gastric biopsy samples tested were positive for H. pylori, with a prevalence of 51.9%. No significant difference was found with regard to the gender (p=0.793) and age (p=0.183) of the patients. Genotype s1m1 vacA gene was found in 67% of the cases of peptic ulcer investigated (p=1.0), despite the limited number of patients with this disease (n=3). A correlation between the presence of less virulent strains (s2m2) and reflux esophagitis was found in the majority of the cases (45%), but without statistical significance. An association between the prevalence of cagA gene, found in 92% of isolates, and peptic ulcer was not observed (p=1.0), suggesting that this gene cannot be considered a specific marker of severity in our environment. The results reinforce the importance of conducting regional studies and the need to characterize H. pylori virulence genes associated with different diseases.

Helicobacter pylori genotypes and types of gastritis in first-degree relatives of gastric cancer patients

The frequency of Helicobacter pylori vacA alleles, cagA, and jhp0947 and their association with types and advanced forms of gastritis in 143 first-degree relatives of gastric cancer (GC) patients was assessed. The subjects included 64/143 with antral-predominant gastritis, 68/143 with pangastritis, and 11/143 with corpus-predominant gastritis, with or without atrophy or intestinal metaplasia (IM). Further classification included the severity of atrophy or IM. Group I (40/143) included the subjects with moderate-marked atrophy or IM, group II (58/143) those with no atrophy or IM, and group III (45/143) with mild atrophy or IM. The frequency of vacA s1 was 79.7%, vacA s2 20.3%, m1 49.7%, m2 50.3%, cagA 76.2%, and jhp0947 58%. The most prevalent combination was vacAs1 cagA (+) (65.7%) (P=0.001). Of the 143 subjects, 85 (59.4%) showed atrophy or IM, and 40/85 (47%) developed the moderate-marked atrophy or IM. No significant correlation was found between genotypes and the types of gastritis, non-atrophy, atrophy, or IM and severe forms of atrophy or IM (P>0.05). It is proposed that H. pylori genotype status might not be considered as an important determinant of the types and advanced forms of gastritis in the first-degree relatives of GC patients.

Prevalence of Helicobacter pylori genotypes (vacA, cagA, cagE and virB11) in gastric cancer in Brazilian's patients: an association with histopathological parameters

PURPOSE

To investigate the frequency and the association of vacA alleles, cagA, cagE and virB11 genes of Helicobacter pylori from patients with gastric cancer, considering the clinic histopathological parameters.

METHODS

One hundred and one gastric adenocarcinoma tissues were assessed by PCR to detect H. pylori and vacA alleles, cagA, cagE and virB11.

RESULTS

The distribution of cases according to the presence of the genes studied showed that the group containing vacA s1m1, cagA, cagE and virB11 H. pylori genes was significantly more frequent, followed by the group with at least one marker on the right side and left of the island. They were also present in the early stages and were the most frequent in nearly all histopathological grades.

CONCLUSIONS

This study verified that vacAs1m1 and cag-PAI genes, cagA, cagE and virB11 are important H. pylori markers for gastric cancer development. Also, this study corroborates the importance of cagE and cagA together as cag-PAI marker.

Gastric cancers of Western European and African patients show different patterns of genomic instability

Background

Infection with H. pylori is important in the etiology of gastric cancer. Gastric cancer is infrequent in Africa, despite high frequencies of H. pylori infection, referred to as the African enigma. Variation in environmental and host factors influencing gastric cancer risk between different populations have been reported but little is known about the biological differences between gastric cancers from different geographic locations. We aim to study genomic instability patterns of gastric cancers obtained from patients from United Kingdom (UK) and South Africa (SA), in an attempt to support the African enigma hypothesis at the biological level.

Methods

DNA was isolated from 67 gastric adenocarcinomas, 33 UK patients, 9 Caucasian SA patients and 25 native SA patients. Microsatellite instability and chromosomal instability were analyzed by PCR and microarray comparative genomic hybridization, respectively. Data was analyzed by supervised univariate and multivariate analyses as well as unsupervised hierarchical cluster analysis.

Results

Tumors from Caucasian and native SA patients showed significantly more microsatellite instable tumors (p < 0.05). For the microsatellite stable tumors, geographical origin of the patients correlated with cluster membership, derived from unsupervised hierarchical cluster analysis (p = 0.001). Several chromosomal alterations showed significantly different frequencies in tumors from UK patients and native SA patients, but not between UK and Caucasian SA patients and between native and Caucasian SA patients.

Conclusions

Gastric cancers from SA and UK patients show differences in genetic instability patterns, indicating possible different biological mechanisms in patients from different geographical origin. This is of future clinical relevance for stratification of gastric cancer therapy.

Gastric adenocarcinoma and Helicobacter pylori: correlation with p53 mutation and p27 immunoexpression

INTRODUCTION

Helicobacter pylori infection is an established risk factor for gastric cancer development, but the exact underlying mechanism still remains obscure. The inactivation of tumor suppressor genes such as p53 and p27(KIP1) is a hypothesized mechanism, although there is no consensus regarding the influence of H. pylori cagA(+) in the development of these genetic alterations.

GOALS

To verify the relationship among H. pylori infection, p53 mutations and p27(Kip1) Protein (p27) expression in gastric adenocarcinomas (GA) seventy-four tissues were assayed by PCR for H. pylori and cagA presence. Mutational analysis of p53 gene was performed by single-strand conformation polymorphism (SSCP). Seventy tissues were analyzed by an immunohistochemical method for p27 expression.

RESULTS

From the samples examined, 95% (70/74) were H. pylori positive, 63% cagA(+). Altered p53 electrophoretic mobility was found in 72% of cases and significantly more frequent in the presence of cagA. Considerable reduction in p27 expression (19%) was found with a tendency for association between cagA(+) and p27(-), although the results were not statistically significant. Concomitant alterations of both suppressor genes were detected in 60% of cases. In the cases cagA(+), 66.7% of them had these concomitant alterations.

CONCLUSIONS

The data suggest that H. pylori cagA(+) contributes to p53 alteration and indicate that concomitant gene inactivation, with reduced p27 expression, may be a mechanism in which H. pylori can promote the development and progression of gastric cancer.

CagA status and VacA subtypes of Helicobacter pylori in relation to histopathologic findings in Iranian population

BACKGROUND/OBJECTIVE

The aim of this study was to detect dominant cagA/vacA genotypes of Helicobacter Pylori (H. pylori) and determine correlations between different cagA/vacA genotypes and histologic features of chronic gastritis in Iranian patients.

METHODS

Gastric biopsy was taken from 166 patients with nonulcer dyspepsia. The specimens were processed and DNA from each H. pylori isolate was extracted from multiple colony sweeps for identification of glmM gene. The vacA subtypes and cagA gene were tested by PCR . Histopathological features were recorded and graded according to partial Sydney system.

RESULTS

Of the 86 strains, 66 (76.7%) were cagA positive. The proportions of vacA gene subtypes s1, s2, m1 and m2 in the 78 strains isolated were 70.5%, 29.5%, 37.2% and 62.8%, respectively. About 83.3% of the vacA-positive strains had s1 allele. Twenty-six strains (33.3%) were positive for both cagA and m1 allele. Positive cagA status and vacA subtypes were not associated significantly with presence of neutrophil infiltration, intestinal metaplasia or H. pylori density. Only vacA s1 was significantly associated with more severe inflammation (P=0.02). The dominant genotype of H. pylori was vacA plus s1/m2. CagA gene positivity rate was not closely associated with severity of the disease.

CONCLUSION

H. pylori strains showing vacA s1 genotype were associated with more severe gastritis. These findings show that vacA genotyping may have clinical relevance in Iran.

The association of vacA genotype and Helicobacter pylori-related disease in Latin American and African populations

In the populations of Western countries, particular genotypes of the vacuolating cytotoxin gene, vacA (vacA s, signal region variants; vacA m, middle region variants) of Helicobacter pylori are believed to be risk factors for the development of peptic ulcers and gastric cancer. However, it was unclear whether these vacA gene variants are associated with the development of gastrointestinal diseases in developing nations. The relationship between vacA genotypes and H. pylori-related disease development in Latin American and African populations was investigated using meta-analysis of 2612 patients from Latin America (2285 strains) and 520 patients from Africa (434 strains). The frequencies of vacA s and m genotypes differed between strains from Latin America (77.2% for s1 and 68.1% for m1) and Africa (83.9% for s1 and 56.7% for m1). Latin American strains with s1 and m1 genotypes increased the risk of gastric cancer (OR 4.17, 95% CI 2.49-6.98 for s1, and 3.59, 2.27-5.68 for m1) and peptic ulcers (e.g. 1.73, 1.37-2.20 for s1). African strains with the s1 or m1 genotypes also increased the risk of peptic ulcers (8.69, 1.16-64.75 for s1) and gastric cancer (10.18, 2.36-43.84 for m1). The cagA-positive genotype frequently coincided with s1 and m1 genotypes in both populations. Overall, the vacA s and m genotypes were related to gastric cancer and peptic ulcer development and might be useful markers of risk factors for gastrointestinal disease, especially in Latin America. Further studies will be required to evaluate the effects of vacA genotypes in African populations because of the small sample number currently available.

Association of H. pylori virulence genes CagA, VacA and UreAB with ulcer and nonulcer diseases in Iranian population

To evaluate the association of virulence genes CagA, VacA and UreAB of H. pylori with the development of different gastric disorders, polymerase chain reaction was performed on H. pylori organisms isolated from biopsy samples of stomach of patients with ulcerative disease and nonulcerative disease. The difference between the groups was statistically significant (p < 0.05) only for VacA gene. We detected 8 phenotypes, characterized as CagA(+)-VacA(-)-UreAB(+) (phe 1), CagA(-)-VacA(-)-UreAB(-) (phe 2), CagA(+)-VacA(+)-UreAB(-) (phe 3), CagA(+)-VacA(-)-UreAB(+) (phe 4), CagA(-)-VacA(+)-UreAB(+) (phe 5), CagA(+)-VacA(-)-UreAB(-) (phe 6), CagA(-)-VacA(+)-UreAB(-) (phe 7), CagA(-)VacA(-)-UreAB(+) (phe 8). The prevalence of phenotype 1 was significantly higher in the patients with UD than that in the patients with NUD (p < 0.05). These results suggest that in the population under our study, being infected by a H. pylori strain with the genotype CagA(+)-VacA(+)-UreAB(+) may be associated with an increased risk of acquiring an ulcer disease.

The prevalence of cagA and cagE genes in Helicobacter pylori strains isolated from different patient groups by polymerase chain reaction

The aim of this study was to investigate the prevalence of cagA and cagE genes in H. pylori strains isolated from different patient groups with Non-Ulcer Dyspepsia (NUD), Duodenal Ulcer (DU), Gastric Ulcer (GU) and Gastric Cancer (GC). The patients admitted to the gastroenterology unit at Sharyati hospital in Tehran in 2006 were included in this study. Gastric biopsy specimens were obtained from the antrum of the stomach from each patient then cultured for detection of H. pylori. Identification of H. pylori was performed according to the standard bacteriological methods. Genomic DNA was extracted using a commercially available Qia gene kit. PCR was done using primers cagA-F, cagA-R and cagE-F, cagE-R to detect the target genes cagA and cagE, respectively. Amplified products of target genes were confirmed by sequencing. The cagA and cagE were detected among 85 and 86% of H. pylori isolates, respectively. Prevalence of cagA and cagE genes in the patients with NUD, DU, GU and GC were 22 (64.7%), 28 (100%), 18 (90%), 10 (100%) and 25 (73.5%), 27 (96.4%), 19 (95%), 7 (70%), respectively. The current study demonstrated a significant correlation between peptic ulceration and the presence of H. pylori isolates carrying cagE and cagA genes in Iranian patients.

cagA gene and protein status among Iranian Helicobacter pylori strains

The wide geographic genetic diversity of Helicobacter pylori (Hp) and, in particular, the varying prevalence of cagA in different countries has been documented repeatedly. This study was designed to determine the frequency of cagA in Iranian Hp strains by means of genotyping and assessment of host antibodies. Helicobacter pylori strains from 235 patients, including 174 non-ulcer dyspepsia, 25 peptic ulcer and 36 gastric cancer patients, were studied. The frequencies of the 5', middle and 3' terminal regions of the cagA gene were 90.6, 57.6, 89%, respectively, with no correlation to the clinical outcomes. Antibodies against the CagA protein were present in 90.7% of patients. Multiple biopsy sampling in 97 cases revealed multiple infection in 16.5% of the patients. Sequencing of the seven variants of the 3' end of the cagA gene revealed no clustering and the distribution of the Iranian strains among those of other countries. Our results from the genotyping and serology analyses confirm that the majority of Iranian Hp strains are cagA-positive.

Analysis of the risk factors and their combinations in acute gastroduodenal ulcer bleeding: a case-control study

OBJECTIVE

Traditional non-steroidal anti-inflammatory drugs (NSAIDs) including ASA for thrombosis prophylaxis (ASA-TP), for pain medication (ASA-P) or non-ASA NSAIDs (NANSAIDs), Helicobacter pylori infection, CagA strains of H. pylori and smoking are reported risk factors for peptic ulcer bleeding (PUB), but the combined and the dose effects of these factors are controversial. The aim of this study was to estimate the significance of these risk factors and their combinations in PUB.

MATERIAL AND METHODS

PUB patients (n = 94) were compared with an age- (+/- 5 years) and gender-matched control group of non-ulcer patients (n = 94) attending elective endoscopy. A questionnaire on the possible risk factors (previous gastric and duodenal ulcer, use of ASA-TP, ASA-P, NANSAIDs, warfarin, alcohol and smoking) was completed. H. pylori infection was determined as positive if histology and/or urease tests were positive. CagA antibodies of IgG class were determined using an immunoblot method.

RESULTS

H. pylori infection (odds ratio (OR) 8.8), the use of ASA-P (OR 3.5), ASA-TP (OR 4.07), NANSAIDs with > or =1 defined daily dose (OR 6.56), smoking > or =20 cigarettes daily (OR 6.43) and previous duodenal ulcer (DU) (OR 8.96) were independent risk factors for PUB. At least two risk factors were present in 65% of PUB patients. CagA strains were detected in 97% of the H. pylori-positive cases and in 96% of the respective controls. ASA, ibuprofen, ketoprofen and smoking were dose-dependent risk factors for PUB.

CONCLUSIONS

Previous DU, H. pylori, the use of any ASA and smoking explained the majority of the PUB episodes. CagA strains of H. pylori were not associated with PUB. Two-thirds of the PUB patients had at least two risk factors, but their combination did not potentiate the risk.

A new Helicobacter pylori vacuolating cytotoxin determinant, the intermediate region, is associated with gastric cancer

BACKGROUND & AIMS

Helicobacter pylori is the main cause of peptic ulceration and gastric adenocarcinoma. The vacuolating cytotoxin gene, vacA, is a major determinant of virulence. Two naturally polymorphic sites in vacA, the signal region and midregion, are well-characterized determinants of toxicity and markers of pathogenesis. The aim of this study was to characterize a new vacA polymorphic site, the intermediate (i) region.

METHODS

The vacA i-region was identified and characterized by constructing isogenic vacA exchange mutants and determining their vacuolating activity on HeLa, AGS, and RK13 cell lines. The vacA i-region types of H pylori isolates from patients undergoing routine endoscopy were determined by nucleotide sequencing and allele-specific polymerase chain reaction.

RESULTS

Two i-region types were identified, i1 and i2, and both were common among 42 Western clinical isolates. Interestingly, only naturally occurring s1/m2 strains varied in i-type; s1/m1 and s2/m2 strains were exclusively i1 and i2, respectively. Vacuolation assays showed that i-type determined vacuolating activity among these s1/m2 strains, and exchange mutagenesis confirmed that the i-region itself was directly responsible. Using a simple i-region polymerase chain reaction-based typing system, it was shown for 73 Iranian patients that i1-type strains were strongly associated with gastric adenocarcinoma (P < 10(-3)). Finally, logistic regression analysis showed this association to be independent of, and larger than, associations of vacA s- or m-type or cag status with gastric adenocarcinoma.

CONCLUSIONS

Together these data show that the vacA i-region is an important determinant of H pylori toxicity and the best independent marker of VacA-associated pathogenicity.

Helicobacter pylori may play a contributory role in the pathogenesis of primary sclerosing cholangitis

Helicobacter pylori (H. pylori) DNA has been identified in human livers and has been implicated in chronic liver disease and liver cancer. To better understand the role of H pylori in primary sclerosing cholangitis (PSC), 25 patients with end-stage PSC and 31 controls were studied. Genomic DNA was extracted from microdissected hilar hepatic ducts of liver explants and was amplified for H pylori DNA. Serum was tested for H pylori antibodies. Helicobacter DNA was detected in 9 of the 56 (16%) patients by 16SrRNA PCR (an additional case [for a total of 18%] was antibody positive). Seven of the 9 cases identified by polymerase chain reaction were positive for the CagA gene, confirming they were H pylori. Seven of the 25 (28%) patients with PSC and 3 of the 31 (9.7%) controls were positive for Helicobacter (P=.087). H pylori DNA was detected in microdissected hilar biliary epithelium in more PSC patients than controls, supporting the hypothesis that bile reflux from the duodenum into the biliary tract might carry H pylori organisms into the proximal biliary system, possibly contributing to PSC development and/or progression in some patients.

J. Análise das impressões digitais de DNA e de fatores de virulência de linhagens de Helicobacter pylori

RACIONAL: Helicobacter pylori é hoje aceito como o principal agente etiológico de gastrite em seres humanos e fator de risco para úlcera péptica e câncer gástrico. A evolução da infecção está relacionada a diversos fatores, inclusive bacterianos, como presença do gene cagA e o genótipo vacA s1m1, associados ao desenvolvimento de úlcera e adenocarcinoma gástrico. A técnica de RAPD ("random amplified polimorphic") tem sido amplamente utilizada para obtenção de impressões digitais de DNA para examinar a similaridade entre linhagens. OBJETIVOS: Avaliar a presença de cagA e alelos do vacA em amostras de H. pylori e associar os achados com a doença apresentada e também investigar possível clonicidade entre os fatores de virulência e as doenças com a impressão digital de DNA gerada pelo RAPD-PCR. MÉTODOS: Foram incluídas 112 amostras provenientes de pacientes com diferentes laudos endoscópicos: gastrite (n = 41), esofagite de refluxo (n = 14), úlcera gástrica (n = 19) e úlcera duodenal (n = 38). A análise dos fatores de virulência da bactéria foi feita por PCR e as impressões digitais de DNA foram estabelecidas pelo método de RAPD-PCR. RESULTADOS: Os resultados obtidos indicam que houve uma associação significativa entre úlcera duodenal e o mosaico vacA s1m1. Analisando-se os padrões de bandas geradas pelo RAPD-PCR, sete diferentes dendogramas foram construídos e não foi possível detectar associação significativa entre os agrupamentos, sugerindo que as amostras não possuem perfil clonal. CONCLUSÃO: Os resultados reforçam a importância do gene vacA como um marcador de virulência do H. pylori. O RAPD da impressão digital de DNA realizado foi incapaz de associar o padrão de bandas com as enfermidades e os genótipos de vacA e cagA.

Association between Helicobacter pylori genotypes and gastric disorders in relation to the cag pathogenicity island

Helicobacter pylori is a bacterium associated with upper gastrointestinal diseases in humans. However, only a small proportion of infected people become sick. Although several studies have tried to establish an association between known virulence markers and clinical outcomes, in many cases the results have been conflicting. The aim of this study was to investigate the importance of virulence markers to predict clinical outcome in Brazil. Mixed infections by genetically unrelated strains detected by vacA genotyping were found in 18% of the patients. The cagA and cagE genes and the vacAs1 genotype were associated with the development of peptic ulcer disease (PUD). The cagAvacAs1m1 genotype was associated with PUD and duodenal ulcer (DU). Conversely, jhp947 was not associated with DU or PUD, indicating that this gene is not a universal virulence marker. These results also show that a high proportion of the patients were simultaneously infected by cag-positive and cag-negative H. pylori types. This finding suggests the existence of a dynamic equilibrium between the loss and gain of the cag pathogenicity island, probably depending on the physiologic conditions of the patient's stomach. To the best of our knowledge, this is the first study that has documented this finding in Brazil.

Helicobacter pylori infection is associated with a high incidence of intestinal metaplasia in the gastric mucosa of patients at inner-city hospitals in New York

Gastric carcinogenesis is a multistep process progressing from chronic gastritis, through glandular atrophy (GA), intestinal metaplasia (IM) and dysplasia. Infection of the stomach with H. pylori increases the risk of developing gastric cancer. Few studies have examined the degree to which Hp-induced changes occur in specific populations. In the present study, we examined the association between Hp infection and histological changes in the gastric mucosa of patients at two inner-city hospitals in New York. Patients enrolled in this study were undergoing endoscopy for gastrointestinal complaints. One antral biopsy was taken for detecting and genotyping Hp by PCR. Additional biopsies were taken from the antrum and fundic region for histological analysis and were scored with respect to acute and chronic inflammation, GA, IM and Hp infestation according to the Sydney classification. Hp strains infecting these patients were genotyped with respect to the expression of Hp virulence factors including VacA, CagA, and BabA2. Samples were collected from 126 patients at Kings County Hospital in Brooklyn and St. John's Episcopal Hospital in Queens. Hp infection rates were highest in Blacks (41.6%) and Hispanics (29.4%) and lowest in Caucasians (18.8%). Scores for acute and chronic inflammation and IM were higher in Hp-infected individuals in both the antrum and fundic regions, whereas Hp infection did not affect the incidence or intensity of GA. In Hp-infected individuals, the incidence of IM was greater in the antrum (Hp-infected 37.8% vs. non-infected 9.2%, p < 0.05) and fundic region (Hp-infected 15.1% vs. noninfected 1.8%, p < 0.05). Genotyping of the Hp strains infecting these patients revealed that the predominant VacA allele was s1 bm 1 and that the CagA gene was present in 69.8% of Hp-infected samples. Interestingly, the BabA2 gene was detected in only four samples (9.3%). The incidence of IM in the antrum was higher in CagA + samples when compared with CagA- samples (52.2% vs. 15.4%, respectively). Our findings indicate that the virulent Hp strain infecting minority patients treated at inner-city hospitals in New York City is associated with a high incidence of IM and that these patients may be at greater risk for developing gastric cancer than the general population.

Clinical and pathological importance of vacA allele heterogeneity and cagA status in peptic ulcer disease in patients from North Brazil

We have examined the prevalence of gene cagA and vacA alleles in 129 patients, 69 with gastritis and 60 with peptic ulcer diseases from North Brazil and their relation with histopathological data. vacA and cagA genotype were determined by polymerase chain reaction. Hematoxylin-eosin staining was used for histological diagnosis. 96.6% of the patients were colonized by Helicobacter pylori strains harboring single vacA genotype (nont-mixed infection). Among them, 11.8% had subtype s1a, 67.8% had subtype s1b, and 17% subtype s2. In regard to the middle region analysis, m1 alleles were found in 75.4% and m2 in 21.2% of patients. The cagA gene was detected in 78% patients infected with H. pylori and was associated with the s1-m1 vacA genotype. The H. pylori strains, vacA s1b m1/cagA-positive, were associated with increased risk of peptic ulcer disease and higher amounts of lymphocytic and neutrophilic infiltrates and the presence of intestinal metaplasia. These findings show that cagA and vacA genotyping may have clinical relevance in Brazil.

IL1RN polymorphism and cagA-positive Helicobacter pylori strains increase the risk of duodenal ulcer in children

Duodenal ulcers in children are associated with Helicobacter pylori gastric infection with cagA-positive strains, but factors linked to the host are poorly known. The authors evaluated the role of proinflammatory interleukin-1 gene cluster polymorphisms in the pathogenesis of duodenal ulcer. They studied prospectively 437 children 1 to years old, 209 of whom were H. pylori positive and 228 of whom were H. pylori negative. IL1B-511-C/T, -31T/C, and IL1RN Variable number of tandem repeats were genotyped by polymerase chain reaction (PCR) restriction fragment length polymorphism, PCR with confronting two-pair primers, and PCR, respectively. cagA status was evaluated by PCR. The role of the proinflammatory cytokine genotypes in the genesis of duodenal ulcer was evaluated before and after stratification of H. pylori status on logistic regression models. In the group of children without duodenal ulcer, no association was observed between H. pylori status and proinflammatory polymorphisms. Furthermore, no association between IL1 cluster genotypes and cagA status was seen in the H. pylori-positive children. However, increasing age, male sex, and IL1RN*2 were independently associated with duodenal ulcer. After stratification, in the H. pylori-positive children, increasing age, male sex, the presence of ILRN*2 allele, and cagA-positive status were independently associated with duodenal ulcer. The risk for the development of duodenal ulcer increased when a combined association of the presence of IL1RN*2 allele and infection by a cagA-positive H. pylori strain was the variable. This study provides evidence supporting independent roles of IL1RN*2 allele and cagA-positive status in the genesis of duodenal ulcer in children.

Helicobacter pylori endemic and gastric disease

H. pylori infection of the stomach is widespread among human populations including Iranians and is considered to play a major role in the pathogenesis of gastric diseases such as peptic ulcer, adenocarcinoma, and MALT lymphoma. The association between H. pylorivirulence markers and disease has been studied in other populations around the world. The aim of this study was to investigate the distribution of H. pylori vacA and cagA genotypes and their association with clinical outcomes in Iran. H. pylori was cultured from gastric biopsy specimens obtained from 137 Iranian patients (58 with duodenal ulcer, 61 with nonulcer dyspeptic [NUD], and 18 with gastric adenocarcinoma). The vacA alleles and cagA genotypes were determined by PCR. The vacA sl allele was present in 107 of the 137 subjects (78%). Multiple strains (m1 and m2) were detected in H. pylori isolates from the patients. VacA s1 genotypes were more frequent in patients with peptic ulcer (46/58; 79%) than in NUD patients (47/61; 77%). CagA was present in 44% of the patients. NUD patients had a frequency of cagA positivity similar to that of the overall population (46%). CagA was present more frequently more than cagA-negative (20% vs. 8%, respectively) in patients with gastric carcinoma (20%) than cagA-negative in patients with gastric carcinoma (8%). This is the first comprehensive study to demonstrate the frequency of colonization with mixed strain, vacA s1, m1 and m2 as the dominant genotype in these Iranian patients, where a high rate of H. pylori infection exists and is similar to the region with a low rate of H. pylori infection. Therefore, host genetics, environmental factors, and the substantial genetic heterogeneity among different H. pylori strains may contribute to the different clinical outcomes.

Relationships between cagA, vacA, and iceA genotypes of Helicobacter pylori and DNA damage in the gastric mucosa

Helicobacter pylori (H. pylori) is believed to predispose carriers to gastric cancer by inducing chronic inflammation. The inflammatory processes may result in the generation of reactive oxygen and nitrogen species that damage DNA. In this study, we investigated the relationships between DNA damage in the gastric mucosa and cagA, vacA, and iceA genotypes of H. pylori. The study was conducted with biopsies from the gastric antrum and corpus of 98 H. pylori-infected and 26 uninfected control patients. H. pylori genotypes were determined by PCR and DNA damage was measured in gastric mucosal cells by the Comet assay (single cell gel electrophoresis). All patients were nonsmokers, not abusing alcohol, and not using prescription or recreational drugs. Levels of DNA damage were significantly higher (P < 0.0001) in the H. pylori-infected patients than in uninfected patients. In comparison with the level of DNA damage in the uninfected controls, the extent of DNA damage in both the antrum (OR = 8.45; 95% CI = 2.33-37.72) and the corpus (OR = 6.55; 95% CI = 2.52-17.72) was related to infection by cagA+/vacAs1m1 and iceA1 strains. The results indicate that the genotype of H. pylori is related to the amount of DNA damage in the gastric mucosa. These genotypes could serve as biomarkers for the risk of extensive DNA damage and possibly gastric cancer.

Prevalence of cagA and vacA genes in isolates from patients with Helicobacter pylori-associated gastroduodenal diseases in Recife, Pernambuco, Brazil

Geographical differences in the prevalence of Helicobacter pylori genes and their association with disease severity have been identified. This study analyzes the prevalences of the cagA gene and alleles of the vacA gene in H. pylori-associated gastroduodenal diseases in isolates from Recife, PE, Brazil. Gastric biopsy of 61 H. pylori-positive patients were submitted to DNA extraction and gene amplification by polymerase chain reaction. Among the 61 patients, 21 suffered from duodenal ulcer (DU) and 40 from gastritis (GT). The prevalence of H. pylori strains harbouring the cagA gene was higher in the DU group (90.5%) than in the GT group (60%) (p=0.02). The vacA gene was amplified in 56 out of 61 biopsies, of which 43 (76.8%) contained bacteria carrying the s1 allele and 13 (23.2%) the s2. However, the prevalence of the vacA s1 genotyping was the same in either DU or GT group. The majority of the s1-typed strains, 39 (90.7%) out of 43, were subtype s1b. In resume there was a strong association between the H. pylori cagA+ gene and DU. However, there were no differences between the DU and GT groups in relation to the vacA s1 and s2 alleles distribution, albeit the subtype s1b was predominant.

Association of CagA and VacA presence with ulcer and non-ulcer dyspepsia in a Turkish population

AIM: The mostly known genotypic virulence features, of H. pylori are cytotoxin associated gene A (CagA) and Vacuolating cytotoxin gene A (VacA). We investigated the association of these major virulence factors with ulcer and non-ulcer dyspepsia in our region.

METHODS: One hundred and forty two dyspeptic patients were studied (average age 44.8 ± 15.9 years, range 15-87 years, 64 males and 78 females). Antral and corpus biopsies were taken for detecting and genotyping of H. pylori. 107 patients who were H. pylori positive by histological assessment were divided into three groups according to endoscopic findings: Duodenal ulcer (DU), gastric ulcer (GU) and non-ulcer dyspepsia (NUD). The polymerase chain reaction (PCR) was used to detect CagA and VacA genes of H. pylori using specific primers.

RESULTS: H. pylori was isolated from 75.4% (107/142) of the patients. Of the 107 patients, 66 (61.7%) were CagA-positive and 82 (76.6%) were VacA-positive. CagA gene was positively associated with DU and GU (P < 0.01, P < 0.02), but not with NUD (P > 0.05). Although VacA positivity in ulcer patients was higher than that in NUD group, the difference was not statistically significant (P > 0.05).

CONCLUSION: There is a significantly positive association between CagA genes and DU and GU. The presence of VacA is not a predictive marker for DU, GU, and NUD in our patients.

New pathogenicity marker found in the plasticity region of the Helicobacter pylori genome

Comparison of gastric carcinoma and gastritis isolates showed the presence of genes, probably carcinoma associated (JHP947 and JHP940), that are situated in a Helicobacter pylori genome region (45 kb in J99 and 68 kb in 26695) called the "plasticity region." This region presents a great variability of DNA sequences. We investigated, by PCR, the presence of the JHP940 and JHP947 genes, as well as the presence of a third gene which seems to be associated with gastritis (HP986), on H. pylori strains isolated from 200 Brazilian patients, 79 of whom had gastric carcinomas and 53 of whom had duodenal ulcers, to confirm this association. Gastritis isolates (n = 68) were included as a control. We also evaluated if these genes were related to the virulence-associated cagA genotype. The present methodology did not permit definitive conclusions to be reached regarding the association between the JHP940 gene and gastric carcinoma or between the HP986 gene and gastritis. However, we showed that the JHP947 gene might be implicated in the development of both duodenal ulcer and gastric carcinoma. The presence of the JHP947 gene was associated with the cagA-positive genotype. The JHP947 gene is a novel virulence marker candidate of H. pylori.

Avaliação da prevalência da infecção por helicobacter pylori em pacientes portadores de câncer gástrico

OBJETIVO: Nos últimos anos, evidências de associação entre Helicobacter pylori e câncer gástrico têm sido relatadas por inúmeros estudos. Este trabalho objetiva investigar a prevalência da infecção por este microorganismo em pacientes com câncer gástrico, oriundos do Hospital de Câncer Napoleão Laureano (João Pessoa - PB) e determinar o risco relativo para o desenvolvimento desta neoplasia nos pacientes infectados. MÉTODO: Com esta finalidade, 16 pacientes com diagnóstico confirmado de adenocarcinoma gástrico foram submetidos à endoscopia digestiva alta para coleta de fragmentos da mucosa gástrica, para realização do teste da urease, sendo então, pareados com um grupo de 16 controles com exames endoscópicos normais. RESULTADOS: Dos 16 portadores de câncer, 28,1% estavam infectados, versus 25% para os do grupo controle. Nos indivíduos infectados, houve maior prevalência da infecção nos portadores de lesões gástricas distais (43,8%), nos tumores Borrmann III (37,6%), e moderadamente diferenciados (37,6%). Houve associação estatisticamente significante entre o grau de diferenciação e a presença da infecção pelo H. pylori (p<0,10). O risco relativo estimado para a associação entre câncer gástrico e infecção pelo H. pylori foi de 1,28% (odds ratio = 1,28%). CONCLUSÃO: Estes resultados permitem concluir que a infecção pelo H. pylori é um fator de risco relativo para o desenvolvimento do adenocarcinoma gástrico.

Determination of Helicobacter pylori vacA allelic types by single-step multiplex PCR

AIMS

To develop and evaluate a novel multiplex PCR assay that enables definition of Helicobacter pylori vacA allelic type in a single reaction.

METHODS AND RESULTS

Application of the one-step system to DNA extracts from 22 cultures of known vacA genotype demonstrated that it was highly accurate. Analysis of 15 matched gastric biopsy/culture pairs generated exactly correlating genotype profiles. vacA genotypes were determined from an additional 62/70 gastric biopsies from dyspeptic patients of known H. pylori positive status by the one-step assay, compared with 63/70 by the original two-reaction test. Types s1/m1, s1/m2 and s2/m2 were identified in 51.9%, 31.2% and 16.9% of biopsies, respectively.

CONCLUSIONS

The multiplex PCR system developed enables rapid one-step vacA genotyping that is accurate, easy to interpret and more economical than the alternative multiple-reaction tests. Application of this system to gastric biopsies from patients in South-east England demonstrated that s1/m1 was the most common genotype, while s1/m2 and s2/m2 were less prevalent.

SIGNIFICANCE AND IMPACT OF THE STUDY

This simple one-step system can be applied direct to antral gastric biopsies without the need for culture, thereby facilitating rapid surveillance of vacA genotype in relation to geographical location and disease status.

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

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

Association of cagA and vacA genotypes of Helicobacter pylori with gastric diseases in Estonia

Gastric biopsy specimens from 156 adult patients from southern Estonia suffering from chronic gastritis, peptic ulcer disease, and perforated peptic ulcer were analyzed by PCR. The cagA gene was evenly distributed throughout 87% of the specimens from the patients with the different gastric diseases. The presence of the cagA gene correlated with that of vacA signal sequence type s1a (99%). However, no clear differences were found in the distribution of cagA and vacA genotypes among patients in Estonia with severe perforated peptic ulcer, uncomplicated peptic ulcer, or chronic gastritis.

Distribution of distinct vacA, cagA and iceA alleles in Helicobacter pylori in Hong Kong

BACKGROUND

There is a substantial genetic heterogeneity among Helicobacter pylori strains, and certain genotypes have been suggested to be associated with the virulence of this pathogen. The aim of this study was to investigate the distribution of H. pylori vacA, cagA and iceA genotypes and their association with duodenal ulcer disease in Hong Kong.

MATERIALS AND METHODS

Gastric biopsies of 72 H. pylori infected patients were analyzed by specific polymerase chain reactions.

RESULTS

Of the 72 cases, 69 (95.8%) had vacA signal sequence s1c strains, and three (4.2%) had s1a strains. vacA middle region sequences, m1b and m2, were detected in 23 (31.9%) and 46 (63.9%), respectively. Six (8.3%) cases contained multiple vacA subtypes. vacA s2 allele was only observed in three (4.3%) cases, which were also infected with s1c subtype. cagA was present in 64 (88.9%) of 72 patients, and iceA1 subtype was detected in 46 (63.9%) cases. Neither cagA nor vacA and iceA were associated with duodenal ulcer disease.

CONCLUSION

The distribution of vacA, cagA and iceA alleles in H. pylori strains in Hong Kong is similar to that in east Asia. There is a difference in the distribution of genotypes between strains in Hong Kong and those in mainland China, although strains in the two regions exhibit a very close relation. The association of these virulence genes and duodenal ulcer disease needs reappraisal, particularly under geographic considerations.

Comparison of genomic structures and antigenic reactivities of orthologous 29-kilodalton outer membrane proteins of Helicobacter pylori

We purified a 29-kDa Helicobacter pylori outer membrane protein (Omp29 protein) and cloned the gene encoding the protein from H. pylori strain ATCC 43504. The Omp29 gene corresponded to the reported JHP73 and the HP78-79 genes of H. pylori strains. A corresponding nucleotide fragment was detected in all 150 tested H. pylori clinical isolates by PCR or Southern blotting. The amplified Omp29-corresponding fragments were categorized into a ca. 770-bp-long group and a larger-fragment group. Sequence analysis indicated that the larger fragments were likely synthesized from the 770-bp fragments by insertion of an irrelevant fragment via 17-bp-long repeat sequences. Immunoblot analysis implies that the ca. 770-bp fragment is responsible for the protein homologous to Omp29, whereas the larger fragments are not responsible for those proteins or encoding antigenically distinct proteins. We postulate that the H. pylori outer membrane protein Omp29 can alter its antigenicity through gene modifications mediated by nucleotide transfer.

Helicobacter pylori genotypes may determine gastric histopathology

The outcome of Helicobacter pylori infection has been associated with specific virulence-associated bacterial genotypes. The present study aimed to investigate the gastric histopathology in Portuguese and Colombian patients infected with H. pylori and to assess its relationship with bacterial virulence-associated vacA, cagA, and iceA genotypes. A total of 370 patients from Portugal (n = 192) and Colombia (n = 178) were studied. Corpus and antrum biopsy specimens were collected from each individual. Histopathological features were recorded and graded according to the updated Sydney system. H. pylori vacA, cagA, and iceA genes were directly genotyped in the gastric biopsy specimens by polymerase chain reaction and reverse hybridization. Despite the significant differences between the Portuguese and Colombian patient groups, highly similar results were observed with respect to the relation between H. pylori genotypes and histopathology. H. pylori vacA s1, vacA m1, cagA+ genotypes were significantly associated with a higher H. pylori density, higher degrees of lymphocytic and neutrophilic infiltrates, atrophy, the type of intestinal metaplasia, and presence of epithelial damage. The iceA1 genotype was only associated with epithelial damage in Portuguese patients. These findings show that distinct H. pylori genotypes are strongly associated with histopathological findings in the stomach, confirming their relevance for the development of H. pylori-associated gastric pathology.

Consensus and variable region PCR analysis of Helicobacter pylori 3' region of cagA gene in isolates from individuals with or without peptic ulcer

The clinical outcome of Helicobacter pylori infection may be associated with the cagA bacterial genotype. To investigate the cagA status of H. pylori-infected patients and the relationship between cagA and peptic ulcer disease, gastric biopsy specimens from 103 Caucasian patients in Brazil were analyzed by PCR. Since allelic variation in cagA exists and distinct H. pylori subgenotypes may circulate in different regions, PCR using primers for a variable 3' region of the cagA gene according to a Japanese methodology and for a consensus cagA 3' region used in Western methods was used for cagA detection. cagA was present in 53 (71%) of 75 H. pylori-positive cases when analyzed by the consensus region method and was associated with duodenal ulcer disease (P = 0.02), but not with gastric ulcer (P = 0.26), when compared to patients with duodenitis or gastritis. The variable region PCR method was able to detect 43 (57%) cagA-positive cases within the same group of H. pylori-positive patients and showed three subtypes of cagA (A, B/D, and C) that were not associated with clinical outcome. However, in 8 (18%) of the cases, more than one subtype was present, and an association between patients with multiple subtypes and disease outcome was observed when compared to patients with isolated subtypes (P = 0.048). cagA was a marker of H. pylori strains for duodenal ulcer disease in our population, and in spite of the differences in the 3' region of the cagA gene, the Japanese methodology was able to detect the cagA status in most cases. The presence of multiple subgenotypes of cagA was associated with gastric ulcer.

Helicobacter pylori genotypes may determine gastric histopathology

The outcome of Helicobacter pylori infection has been associated with specific virulence-associated bacterial genotypes. The present study aimed to investigate the gastric histopathology in Portuguese and Colombian patients infected with H. pylori and to assess its relationship with bacterial virulence-associated vacA, cagA, and iceA genotypes. A total of 370 patients from Portugal (n = 192) and Colombia (n = 178) were studied. Corpus and antrum biopsy specimens were collected from each individual. Histopathological features were recorded and graded according to the updated Sydney system. H. pylori vacA, cagA, and iceA genes were directly genotyped in the gastric biopsy specimens by polymerase chain reaction and reverse hybridization. Despite the significant differences between the Portuguese and Colombian patient groups, highly similar results were observed with respect to the relation between H. pylori genotypes and histopathology. H. pylori vacA s1, vacA m1, cagA+ genotypes were significantly associated with a higher H. pylori density, higher degrees of lymphocytic and neutrophilic infiltrates, atrophy, the type of intestinal metaplasia, and presence of epithelial damage. The iceA1 genotype was only associated with epithelial damage in Portuguese patients. These findings show that distinct H. pylori genotypes are strongly associated with histopathological findings in the stomach, confirming their relevance for the development of H. pylori-associated gastric pathology.

Human serum antibody response to Helicobacter pylori whole cell antigen in an institutionalized Bangladeshi population

AIMS

To use a commercial ELISA kit and an immunoblot assay to investigate the antibody levels of selected members of the Bangladeshi population to Helicobacter pylori protein antigens.

METHODS AND RESULTS

Using immunoblotting, high seroprevalence rates were observed in all age groups, although the subjects within the 1-9 years age group had the highest seroprevalence of antibodies to H. pylori antigens. By ELISA, the highest level of seroprevalence was observed in those over the age of 20 years.

CONCLUSION

On the basis of these results the overall prevalence rate of H. pylori infection for the whole population was 77.4%; 77.9% for orphan boys and 76% for carers. CagA antibodies were detected in 86% of those with high levels of antibodies to H. pylori antigens.

SIGNIFICANCE AND IMPACT OF THE STUDY

A combination of immunoblotting and ELISA was the most efficient means of detecting serum antibodies to H. pylori antigens and could be applied to the screening of human sera for H. pylori-specific antibodies.

vacA genotypes in Helicobacter pylori strains isolated from children with and without duodenal ulcer in Brazil

Data concerning the association between vacA genotypes and disease in children in both developed and developing countries are scarce, especially because of the small number of children with a duodenal ulcer studied. The vacA genotypes of Helicobacter pylori strains obtained from 65 children (24 with a duodenal ulcer and 41 without a duodenal ulcer; 33 girls; mean age, 10.2 years; age range, 1 to 17 years) were investigated as described by J. C. Atherton et al. (J. Clin. Microbiol. 37:2979-2982, 1999). Ten (15.4%) children were infected with more than one H. pylori strain. None of these patients were included in our analysis of the relationship between gastric disorders and specific vacA genotypes. The s1 allele was detected in all H. pylori strains isolated from patients with a duodenal ulcer and from 21 (58.3%) patients without a duodenal ulcer (P = 0.003). Strains with the s2 allele were found only in patients without ulcer (n = 15; 41.7%). Most s1 strains had the s1b allele (97.5%), a result similar to that reported for adults from the Iberian peninsula, which could reflect the Brazilian population origin. One untypeable s1 strain was isolated. The m1 allele was also more frequently found in strains obtained from duodenal ulcer patients (P = 0.028). The m2 allele was found in strains obtained from 20 (36. 4%) children, 3 (15.8%) with an ulcer and 17 (47.2%) without an ulcer. Only one m hybrid strain (m1 and m2 hybrid) was detected. It was demonstrated for the first time that the frequencies of colonization with strains with the s1 allele (14.3% in children up to 8 years of age and 85.7% in older patients; P = 0.012) and of strains with the m1 allele (11.1% in patients up to the age 8 years and 88.9% in older children; P = 0.013) increase with age.

Genotyping of cagA and vacA, Lewis antigen status, and analysis of the poly-(C) tract in the alpha(1,3)-fucosyltransferase gene of Irish Helicobacter pylori isolates

Much work has focused on trying to identify markers in Helicobacter pylori that might allow the eventual disease outcome of an infection to be predicted. In this study we examined the cagA and vacA genotype, and Lewis status in a panel of 43 Irish H. pylori clinical isolates, and investigated a possible correlation with disease pathology. In addition, differences in the poly-(C) tract of the alpha(1,3)-fucosyltransferase gene were examined to identify a possible correlation with gene expression. Only three of 43 isolates were cagA-negative, whereas the remaining 40 isolates, independent of pathology, were cagA-positive. In all the strains we examined, the vacA signal-sequence was type s1a. For the vacA mid-region 12/43 isolates were type m1 and 31/43 isolates were type m2. These data, and examination of isolates from different pathology groups, suggests that there is no correlation between virulence and vacA genotype in the Irish population of H. pylori isolates. Western blotting of whole cell lysates from 32 H. pylori isolates showed 3/32 displayed only the Le(x) epitope, 12/32 only the Le(y), 13/32 both epitopes and 4/32 neither epitope. No apparent association between Lewis phenotype and disease pathology was evident. A range of lengths of poly-(C) tract were observed in the alpha(1, 3)-fucosyltransferase gene, however the length of the tract in an isolate did not correlate with the Lewis structures present. We conclude that future studies on H. pylori pathogenesis should not alone focus on the importance of molecular markers, but also on the host response, including genetic background and immune responsiveness.

Immunoblot analysis of humoral immune response to Helicobacter pylori in children with and without duodenal ulcer

Several studies have demonstrated that enzyme-linked immunosorbent assay is not a sensitive and specific method to diagnose Helicobacter pylori infection in children, especially in the younger ones. Since serum immune response can also be determined by immunoblotting and it permits the detection of antibodies to virulence factors such as CagA and VacA, we evaluated the accuracy of a commercial immunoblotting test to diagnose H. pylori infection and to assess the humoral immune response to different H. pylori antigens in 122 children who underwent upper gastrointestinal endoscopy. The presence of H. pylori was determined in antral biopsy specimens by culture, preformed urease test, and histological analysis. H. pylori was identified by microbiological and histopathological methods in 66 children (including all of the 21 who had duodenal ulcer). Antibodies to H. pylori were detected in 63 infected children and in 8 noninfected ones. The sensitivity, specificity, and positive and negative predictive values of the immunoblotting test were 95.5, 85.7, 88.7, and 94.1%, respectively. The number of immunoreactive bands increased with age (P = 0.003), and the bands of 35 kDa (P = 0.013); 89 kDa, the VacA antigen (P = 0.001); and 116 kDa, the CagA antigen (P = 0.00004) were more frequently observed in older children. The frequency of the bands of 89 kDa (P = 0.001) and 116 kDa (P = 0.03) was higher in children with duodenal ulcer than in H. pylori-positive children without the disease. In conclusion, the immunoblotting test appears to be useful for the diagnosis of H. pylori infection in children, even in the younger ones.

Conservation of the cag pathogenicity island of Helicobacter pylori: associations with vacuolating cytotoxin allele and IS605 diversity

BACKGROUND & AIMS

Specific regions of the cag pathogenicity island (PAI) believed to enhance the virulence of Helicobacter pylori, as well as vacuolating cytotoxin gene alleles and IS605 inserts, were investigated to define diversity within infecting strain populations from patients with peptic ulcer disease and from healthy individuals.

METHODS

The H. pylori studied comprised 67 isolates from 26 subjects and 14 reference strains. Specific polymerase chain reaction assays were used to test for cagA and picB in the cagI region, the virD4 homologue in the cagII region, IS605 in the genome and in the cag PAI, the "empty site" indicating absence of the cag PAI, and different vacA gene alleles.

RESULTS

Most (89%) subjects were infected by H. pylori with a contiguous cag PAI. No intermediate forms were found. IS605 was not detected within the cag PAI of any strain but was present elsewhere in the genomes of strains from 62% of subjects. Twenty individuals were infected with genotypically conserved populations of H. pylori. Six subjects had mixed infections, and in 3 of these cag(+)/cag(-) variants were present.

CONCLUSIONS

The cag PAI-positive H. pylori was a feature of most infected individuals, irrespective of severity of associated disease. Combined genotyping showed that 8 individuals (31%) had mixed infections, which suggests that strain population structure may be an additional contributing factor in disease development.

Contributions of genome sequencing to understanding the biology of Helicobacter pylori

About half of the world's population carries Helicobacter pylori, a gram-negative, spiral bacterium that colonizes the human stomach. The link between H. pylori and, ulceration as well as its association with the development of both gastric cancer and mucosa-associated lymphoid tissue lymphoma in humans is a serious public health concern. The publication of the genome sequences of two stains of H. pylori gives rise to direct evidence on the genetic diversity reported previously with respect to gene organization and nucleotide variability from strain to strain. The genome size of H. pylori strain 26695 is 1,6697,867 bp and is 1,643,831 bp for strain J99. Approximately 89% of the predicted open reading frames are common to both of the strains, confirming H. pylori as a single species. A region containing approximately 45% of H. pylori strain-specific open reading frames, termed the plasticity zone, is present on the chromosomes, verifying that some strain variability exists. Frequent alteration of nucleotides in the third position of the triplet codons and various copies of insertion elements on the individual chromosomes appear to contribute to distinct polymorphic fingerprints among strains analyzed by restriction fragment length polymorphisms, random amplified polymorphic DNA method, and repetitive element-polymerase chain reaction. Disordered chromosomal locations of some genes seen by pulsed-field gel electrophoresis are likely caused by rearrangement or inversion of certain segments in the genomes. Cloning and functional characterization of the genes involved in acidic survival, vacuolating toxin, cag-pathogenicity island, motility, attachment to epithelial cells, natural transformation, and the biosynthesis of lipopolysaccharides have considerably increased our understanding of the molecular genetic basis for the pathogenesis of H. pylori. The homopolymeric nucleotide tracts and dinucleotide repeats, which potentially regulate the on- and off-status of the target genes by the strand-slipped mispairing mechanism, are often found in the genes encoding the outer-membrane proteins, in enzymes for lipopolysaccharide synthesis, and within DNA modification/restriction systems. Therefore, these genes may be involved in the H. pylori-host interaction.

Heterogeneity in the Helicobacter pylori vacA and cagA genes: association with gastroduodenal disease in South Africa?

BACKGROUND

Helicobacter pylori infection is universally associated with gastritis, but only sometimes with clinically significant disease. Candidate virulence markers seem to be useful in identifying the pathogenic infections in some populations.

AIMS

To investigate the association between putative virulence markers and disease in an African population.

METHODS

Fifty nine H pylori strains isolated from dyspeptic patients (11 with peptic ulceration, eight with gastric adenocarcinoma, and 28 with no pathology other than gastritis) were studied for differences in the genes vacA and cagA.

RESULTS

Forty seven (80%) of 59 strains had the vacA signal sequence genotype s1 (one s1a, 46 s1b) and 12 (20%) had subtype s2. vacA mid-region analysis revealed that 40 (68%) strains were vacA m1 and 19 (32%) were m2. All 14 strains from patients with peptic ulceration were vacA s1, in contrast to 23 (66%) of 35 strains from patients with gastritis alone (p<0.01). vacA s2 was found exclusively in patients with gastritis alone (p<0.01). All strains isolated from patients with gastric adenocarcinoma were s1b/m1 (p<0. 005 versus gastritis alone). cagA was detectable in 56 (95%) of 59 isolates. Strains from patients with peptic ulceration (12/13 versus 19/30 with gastritis alone, p=0.05) had the shortest fragment length in the 3' region of cagA, while 4/10 strains from patients with gastric cancer had the longest fragment length in this region (p<0. 02 versus gastritis alone).

CONCLUSION

In this study, the vacA s1 genotype, and fragment length of the 3' region of cagA identified isolates associated with significant clinical disease. The vacA s1bm1 genotype seems to be strongly associated with gastric cancer.