implication of the structure of the Helicobacter pylori cag pathogenicity island in induction of interleukin-8 secretion

Helicobacter pylori virulence genotypes in Bogotá River and wastewater treatment plants in Colombia

BACKGROUND

Helicobacter pylori is a bacterium that infects 70%-80% of the population in Colombia, causing chronic gastritis in all those infected and gastric cancer in 1%-2% of those infected. In Colombia, some studies have identified the presence of vacA and cagA genes in environmental samples such as treated, surface, and wastewater, but they have not been evaluated in the Bogotá River. For this, the aim of this study was to identify the virulence genotypes of H. pylori present in samples from the Bogotá River and domestic wastewater treatment plants (WWTPs).

MATERIALS AND METHODS

A total of 75 water samples (51 from the Bogotá River and 24 from wastewater treatment plants) were collected. The presence of H. pylori DNA and its virulence genotypes was determined by polymerase chain reaction (PCR).

RESULTS

The presence of H. pylori DNA was demonstrated in 44% (33/75) of the samples, obtaining 63.6% (21/33) from the Bogotá River and 36.4% (12/33) from the WWTPs. The most prevalent H. pylori genotype was cagA (-) and vacAm1/s1/i1 being the most virulent of the vacA gene.

CONCLUSIONS

This is the first study in Colombia that determines the cagA and vacA genotypes in surface water and WWTPs, indicating the circulation of virulent genotypes in the population. The presence of this pathogen in the waters can be represent a risk to the health of the surrounding population since these waters are reused by the communities for different purposes.

Helicobacter Pylori-Induced Gastric Infections: From Pathogenesis to Novel Therapeutic Approaches Using Silver Nanoparticles

Helicobacter pylori is the first formally recognized bacterial carcinogen and the most important single digestive pathogen responsible for the induction of gastroduodenal diseases such as gastritis, peptic ulcer, and, finally, gastric neoplasia. The recently reported high rates of antimicrobial drug resistance hamper the current therapies of H. pylori, with therapeutic failure reaching up to 40% of patients. In this context, new treatment options and strategies are urgently needed, but the successful development of these new therapeutic tools is conditioned by the understanding of the high adaptability of H. pylori to the gastric acidic environment and the complex pathogenic mechanism. Due to several advantages, including good antibacterial efficiency, possible targeted delivery, and long tissular persistence, silver nanoparticles (AgNPs) offer the opportunity of exploring new strategies to improve the H. pylori therapy. A new paradigm in the therapy of H. pylori gastric infections using AgNPs has the potential to overcome the current medical limitations imposed by the H. pylori drug resistance, which is reported for most of the current organic antibiotics employed in the classical therapies. This manuscript provides an extensive overview of the pathology of H. pylori-induced gastritis, gastric cancer, and extradigestive diseases and highlights the possible benefits and limitations of employing AgNPs in the therapeutic strategies against H. pylori infections.

CagE, cagA and cagA 3' region polymorphism of Helicobacter pylori and their association with the intra-gastric diseases in Moroccan population

Helicobacter pylori infection is the most important etiological factor in gastroduodenal diseases development. Its evolution is influenced by several factors, including bacterial virulence genes such as cagA and cagE. This work aimed to evaluate the predictive value of cagE alone and in combination with cagA and CagA-EPIYA-C motifs number as a marker of the infection evolution. A total of 823 H. pylori DNA extracted from biopsies of consenting patients suffering from gastritis, peptic ulcer, or gastric cancer. The cagE, cagA status and cagA 3' region polymorphism were determined by PCR. The analysis shows that the risk of duodenal ulcer is 1.97-fold higher (CI = 1.18-3.30) in patients infected by strains cagA+/cagE+. And the risk of gastric cancer is 5.19-fold higher (CI = 1.18-22.70) in patients harboring strains cagE+/2EPIYA-C. The results suggest that cagE in combination with cagA-EPIYA-C motifs number can be used as predictive biomarker of H. pylori infection evolution.

Presence of cagPAI genes and characterization of vacA s, i and m regions in Helicobacter pylori isolated from Alaskans and their association with clinical pathologies

Introduction. Gastric cancer is a health disparity in the Alaska Native people. The incidence of Helicobacter pylori infection, a risk factor for non-cardia gastric adenocarcinoma, is also high. Gastric cancer is partially associated with the virulence of the infecting strain.Aim. To genotype the vacA s, m and i and cag pathogenicity island (cagPAI) genes in H. pylori from Alaskans and investigate associations with gastropathy.Methodology. We enrolled patients with gastritis, peptic ulcer disease (PUD) and intestinal metaplasia (IM) in 1998-2005 and patients with gastric cancer in 2011-2013. Gastric biopsies were collected and cultured and PCR was performed to detect the presence of the right and left ends of the cagPAI, the cagA, cagE, cagT and virD4 genes and to genotype the vacA s, m and i regions.Results. We recruited 263 people; 22 (8 %) had no/mild gastritis, 121 (46 %) had moderate gastritis, 40 (15%) had severe gastritis, 38 (14 %) had PUD, 30 (11 %) had IM and 12 (5 %) had gastric cancer. H. pylori isolates from 150 (57%) people had an intact cagPAI; those were associated with a more severe gastropathy (P≤0.02 for all comparisons). H. pylori isolates from 77 % of people had either the vacA s1/i1/m1 (40 %; 94/234) or s2/i2/m2 (37 %; 86/234) genotype. vacA s1/i1/m1 was associated with a more severe gastropathy (P≤0.03 for all comparisons).Conclusions. In this population with high rates of gastric cancer, we found that just over half of the H. pylori contained an intact cagPAI and 40 % had the vacA s1/i1/m1 genotype. Infection with these strains was associated with a more severe gastropathy.

Role of Plasticity Region Genes and cagE gene of cagPAI of Helicobacter pylori in Development of Gastrointestinal (GI) Diseases

Backround::

Helicobacter pylori is a Gram-negative, micro aerophilic bacterium in the human stomach that is associated with the development of gastrointestinal ailments such as peptic ulcer (PU) and gastric cancer (GC). In the present study, plasticity region genes (jhp0940, jhp0945 and jhp0947) and and cagE gene of cag PAI were assessed independently and in combination for their ability to predict clinical consequences.

Materials and Methods::

A total of 211 strains which were isolated from patients with different gastrointestinal diseases (114 with non-atrophic gastritis, 59 with PU, and 38 with GC) were genotyped by PCR and sequencing. Data were collected and analyzed using SPSS software version 19. Logistic regression models were applied to determine relationships between the plasticity region genes and cagE of H.pylori and clinical status.

Results::

The cagE gene (71.1%) had the highest frequency and jhp0945 (13.7%) was the least abundant among the genes examined. The jhp0940 gene was significantly associated with GC (P = 0.0007), but not PU. On multiple logistic regression analysis, adjusted for both age and sex, the jhp0940 genotype was significantly associated with GC (odds ratio, OR = 2.8, 95%CI = 1.1–7.0; P = 0.027). The jhp0940+/ jhp0945+/jhp0947+ genotype was also linked to an increased risk of GC (OR = 50.4, 95%CI = 5.1–500.0; P = 0.0008) while no genotype correlation was found with PU in Iran (P > 0.05).

Conclusions::

Given the high frequency of cagE, this gene could be a suitable marker for the presence of cag PAI in Iranian strains. The jhp0940 genotype could also be a strong predictor of GC in Iran.

Helicobacter pylori cag Pathogenicity Island cagL and orf17 Genotypes Predict Risk of Peptic Ulcerations but not Gastric Cancer in Iran

BACKGROUND

Gastric cancer (GC) is the third most common cancer regarding mortality in the world. The cag pathogenicity island (PAI) of Helicobacter pylori which contains genes associated with a more aggressive phenotype may involve in the pathogenesis of gastrointestinal disease. We here aimed to examine the associations of cagH, cagL, orf17, and cagG genotypes of H. pylori cag PAI with severe gastrointestinal disease.

MATERIALS AND METHODS

A total of 242 H. pylori strains were genotyped. Histopathological examination and classification of subjects were performed.

RESULTS

The frequencies of the cagH, cagL, cagG, and orf17 genotypes were 40/54 (74.1%), 53/54 (98.1%), 38/54 (70.4%), and 43/54 (79.6%), respectively, in patients with peptidic ulceration (PU),while in the control group, the frequencies were 87/147 (59.6%) for cagH, 121/146 (82.9%) for cagL, 109/146 (74.7%) for cagG, and 89/146 (61.0%) for orf17. The results of simple logistic regression analysis showed that the cagL and orf17 genotypes were significantly associated with an increased risk of PU not GC; the ORs (95% CI) were 10.950 (1.446-82.935), and 2.504 (1.193-5.253), respectively. No significant association was found between the cagH and cagG genotypes and the risk of both the PU and the GC in Iran (P>0.05). Finally, multiple logistic regression analysis showed that the cagL genotype was independently and significantly associated with the age- and sex-adjusted risk for PU; the OR (95% CI) was 9.557 (1.219-17.185).

CONCLUSIONS

We conclude that the orf17 and especially cagL genotypes of H. pylori cag PAI could be factors for risk prediction of PU, but not GC in Iran.

Association of CagPAI integrity with severeness of Helicobacter pylori infection in patients with gastritis

BACKGROUND AND AIM

The Helicobacter pylori cag pathogenicity island (cagPAI) is involved in delivery of CagA effector protein and peptidoglycan into host cells and also in IL-8 induction in the human gastric tissue. Diversity of cagPAI may affect disease status and clinical outcome of the infected patients. Our study was aimed to investigate diversity of this island and its intactness in Iranian patients to investigate possible associations between cagPAI integrity and pathological changes of the infected tissue.

MATERIAL/PATIENTS AND METHODS

Out of the 75 patients, H. pylori strains were obtained from 30 patients with severe active gastritis (SAG) (n=11), moderate chronic gastritis (CG) (n=14) and intestinal metaplasia/dysplasia (IM) (n=5). Intactness of the cagPAI was determined using 12 sets of primer pairs specific for functionally important loci of cagPAI by polymerase chain reaction (PCR).

RESULTS

The cagPAI positive strains were significantly observed in patients with SAG (52.4%) in comparison to those presenting CG (33.3%) and IM (14.3%). In addition, the presence of intact cagPAI was 87.5% in H. pylori strains isolated from patients with SAG, which was higher than those obtained from patients with CG (12.5%) or IM (0%). A significant increase in the frequency of cagα-cagY and cagW-cagT segments, as exterior proteins of the CagPAI, was illustrated in strains from SAG patients compared with those from patients with CG.

CONCLUSIONS

Overall, these results strongly proposed an association between the severity of histopathological changes and intactness of cagPAI in the gastric tissue of patients infected with H. pylori.

Analysis of the intactness of Helicobacter pylori cag pathogenicity island in Iranian strains by a new PCR-based strategy and its relationship with virulence genotypes and EPIYA motifs

Variants of the Helicobacter pylori cag pathogenicity island (cagPAI) and certain virulence genotypes have been proposed to be associated with different gastric disorders. In the present study, we designed a new PCR-based strategy to investigate the intactness of cagPAI in Iranian patients using highly specific primer sets spanning the cagPAI region. The possible relationship between the cagPAI status of the strains and clinical outcomes was also determined. We also characterized virulence genotypes (cagL, cagA, vacA, babA2 and sabA) and variants of CagA EPIYA motifs in these strains. H. pylori was detected in 61 out of 126 patients with various gastroduodenal diseases. The cagL, cagA, vacA s1m1, vacA s1m2, vacA s2m2, babA2, and sabA genotypes were detected in 96.7%, 85.2%, 29.5%, 45.9%, 24.6%, 96.7%, and 83.6% of the strains, respectively. Among the 52 cagA-positive strains, EPIYA motifs ABC, ABCC, ABCCC, and mixed types were orderly detected in the 39, 7, 1, and 5 strains. The cagPAI positivity included both intact and partially deleted, with the overall frequencies of 70.5% and 26.2%, respectively. The majority of the strains from patients with PUD (87.5%), gastric erosion (83.3%) and cancer (80%) presented an intact cagPAI, while a lower frequency of cagPAI intactness was detected in gastritis patients (61.1%). However, no significant relationship was found between the possession of intact cagPAI and clinical outcomes. Furthermore, we found that cagA and vacA s1m1 genotypes were significantly correlated with intact cagPAI (P=0.015 and P=0.012). A significant correlation was also found between EPIYA-ABC and intact cagPAI (P=0.010). The proposed PCR-based scheme was found to be useful for determining the intactness of cagPAI. Our findings also indicate that the cagPAI appears to be intact and rather conserved in majority of Iranian strains. Finally, our study proposed that H. pylori strains with partially deleted cagPAI were less likely to cause severe diseases in comparison with those carrying intact cagPAI.

Correlation of Helicobacter pylori genotypes with gastric histopathology in the central region of a South-European country

BACKGROUND

Outcome of Helicobacter pylori (H. pylori) infection results from interaction of multiple variables including host, environmental and bacterial-associated virulence factors.

AIM

This study aimed to investigate the correlation of cagA, cagE, vacA, iceA and babA2 genotypes with gastric histopathology and disease phenotype in the central region of a South-European country.

METHODS

This prospective study involved 148 infected patients (110 female; mean age 43.5 ± 13.4 years) submitted to endoscopy with corpus and antrum biopsies. H. pylori was cultured and DNA extracted from the isolates. Genotypes were determined by PCR. Histopathological features were graded according to the updated Sydney system and OLGA/OLGIM classification. Only patients with single H. pylori genotypes and complete histopathological results were included.

RESULTS

Antrum samples presented higher degrees of atrophy, intestinal metaplasia, chronic inflammation and neutrophil activity. Genotype distribution was as follows: cagA-31.8 %; cagE-45.9 %; vacA s1a-24.3 %; vacA s1b-19.6 %; vacA s1c-0.7 %; vacA s2-55.4 %; vacA m1-20.9 %; vacA m2-79.1 %; vacA s1m1-18.9 %; vacA s1m2-25.7 %; vacA s2m1-2 %; vacA s2m2-53.4 %; iceA1-33.8 %; iceA2-66.2 %; babA2-12.2 %. CagA genotype was significantly associated with higher degrees of intestinal metaplasia, neutrophil activity, chronic inflammation and OLGIM stages. BabA2 was linked with higher H. pylori density. Strains with vacA s1m1 or vacA s1m1 + cagA positive genotypes had a significant association with peptic ulcer and vacA s2m2 with iron-deficient anemia.

CONCLUSIONS

cagA, vacA s1m1 and babA2 genotypes are relatively rare in the central region of Portugal. cagA-positive strains are correlated with more severe histopathological modifications. This gene is commonly associated with vacA s1m1, and such isolates are frequently found in patients with peptic ulcer.

Heterogeneity of cag genotypes of Helicobacter pylori in the esophageal mucosa of dyspeptic patients and its relation to histopathological outcomes

BACKGROUND

A high prevalence of Helicobacter pylori in the esophageal mucosa of dyspeptic Venezuelan patients has been reported. We aimed to assess the genetic composition of the cag genotypes of H. pylori and its relation to histopathological outcomes in the gastroesophageal mucosa.

METHODS

The presence of cagA, cagE, and virB11 cag pathogenicity island (PAI) genes was detected by PCR in 80 of 150 H. pylori-positive dyspeptic patients in both mucosae. Alterations of the gastroesophageal mucosa were assessed by histological techniques.

RESULTS

The frequency of intact, partial, and deleted cag-PAI genes in the stomach of dyspeptic patients was found to be 57.5%, 21.3%, and 21.3%, respectively, whereas in the esophagus, frequencies were 33.8%, 33.8%, and 32.5% respectively. The genetic composition in the stomach was 57.5% cagA-positive, 20.0% cagA-negative, 75.0% cagE, and 77.5% virB11, whereas in the esophagus the distribution was 36.3% cagA-positive, 30.0% cagA-negative, 61.3% cagE, and 63.8% virB11. The gene with the largest difference between the two mucosae was cagA, with 58.8% in the stomach and 37.5% in the esophagus; cagE and virB11 were less variable. The correlation among single and/or mixed cag genotypes with histopathological outcomes in both mucosae from the same patient was higher for intact single cag-PAI genotypes, showing severe alterations.

CONCLUSIONS

H. pylori may coexist in similar proportions without dominance of one cag genotype, suggesting a heterogeneous distribution in the esophagus. The cagE and virB11 genes can be used as markers of cag-PAI in the esophagus. The single cag-PAI genotype in both mucosae confers an increased risk of developing histological damage.

Seroepidemiology of Helicobacter pylori infection in elderly people in the Beijing region, China

AIM

To investigate seroepidemiology of cagA(+) and vacA(+) strains of Helicobacter pylori (H. pylori) in an elderly population in Beijing and to determine risk factors for seropositivity.

METHODS

A total of 2006 elderly persons (> 60 years) were selected using a random cluster sampling method in different parts of the Beijing area (urban, suburban and mountainous districts). Structured questionnaires were completed during home visits, including history of H. pylori infection, history of gastrointestinal diseases, diet types, hygiene habits, occupation and economic status. Blood samples (2 mL) were collected from each participant, and serum IgG antibodies to cagA, vacA and H. pylori urease antigens were measured by immunodetection.

RESULTS

The prevalence of H. pylori infection in elderly subjects was 83.4% and the type I H. pylori strain infection rate was 56%. The seroprevalence for type I H. pylori strain infection in urban and suburban districts was higher than that in the mountainous areas (P < 0.001). Elderly subjects who had previously performed manual labor or were in the young-old age group (age < 75 years) had a higher seroprevalence of H. pylori infection than those who had previously performed mental labor or were in the oldest-old age group (age ≥ 75 year) (P < 0.05). The type I H. pylori strain infection rate in the elderly with vegetarian diets was higher than in those eating high-protein foods (P < 0.001). There was no significant difference in the prevalence of H. pylori strains between male and female elderly participants (P > 0.05).

CONCLUSION

Type I H. pylori seroprevalence is higher in elderly people. The distribution of strains of H. pylori is significantly affected by age, area and dietary habits.

Helicobacter pylori genotypes associated with gastric histo-pathological damages in a Moroccan population

H. pylori persistent infection induces chronic gastritis and is associated with peptic ulcer disease and gastric carcinoma development. The severity of these diseases is related to human's genetic diversity, H. pylori genetic variability and environmental factors. To identify the prevalence of histo-pathological damages caused by H. pylori infection in Moroccan population, and to determine their association to H. pylori genotypes, a prospective study has been conducted during 3 years on patients attending the gastroenterology department of Hassan II University Hospital (CHU) of Fez, Morocco. A total of 801 Moroccan adults' patients were recruited; H. pylori was diagnosed and genotyped by PCR in biopsy specimens and histological exam was performed. We found a high rate of glandular atrophy. Chronic inflammation, neutrophil activity and glandular atrophy showed statistically significant association with H. pylori infection. However, intestinal metaplasia was inversely associated to this infection and no association was observed with gastric cancer cases. A statistically significant association was found between intestinal metaplasia and vacAs1 and vac Am1 genotypes in patients aged 50 years and more but not in younger. This last genotype is also associated to gastric cancer. In this study, gastric cancer showed no significant association with H. pylori. Further studies are warranted to determine the role of other etiological agents such as Epstein-Barr virus, human papillomavirus and possibly environmental and dietetic factors in the occurrence of this pathology.

Investigation of the association between clinical outcome and the cag pathogenicity-island and other virulence genes of Helicobacter pylori isolates from patients with dyspepsia in Eastern Turkey

The aims of our work were to determine the presence of the cag pathogenicity-island (cag PAI) and other virulence genes of Helicobacter pylori recovered from patients with gastritis and peptic ulcer, and to investigate the correlation of these virulence genes with clinical outcome. The presence of the cagA, the promoter regions of cagA, cagE, cagT, and the left end of cag-PAI (LEC), cag right junction (cagRJ), the plasticity region open reading frames (ORFs), vacA and oipA genes among 69 H. pylori isolates were determined by polymerase chain reaction. Intact cag PAI was detected in only one (1.4%) isolate. The cagA gene was identified in 52.1% and 76.2% of isolates from patients with dyspepsia (gastritis and peptic ulcer), respectively. The plasticity region ORFs i.e. JHP912 and JHP931 were predominantly detected in isolates from peptic ulcer. Less than 25% of the isolates carried other ORFs. Types I, II and III were the most commonly found among the isolates. None of the isolates possessed type Ib, 1c, IIIb, IV and V motifs. The most commonly vacA genotypes were s1am1a and s1m2 in isolates with peptic ulcer and gastritis, respectively. The results confirmed that the prevalence of oipA (Hp0638) gene was 75% and 85.7% in patients with gastritis and peptic ulcer, respectively. Furthermore, vacA s1am1a positivity was significantly related to peptic ulcer (p < 0.05).

Ethnicity association of Helicobacter pylori virulence genotype and metronidazole susceptibility

AIM: To characterise the cag pathogenicity island in Helicobacter pylori (H. pylori) isolates by analysing the strains’vacA alleles and metronidazole susceptibilities in light of patient ethnicity and clinical outcome.

METHODS: Ninety-five H. pylori clinical isolates obtained from patients with dyspepsia living in Malaysia were analysed in this study. Six genes in the cagPAI region (cagE, cagM, cagT, cag13, cag10 and cag67) and vacA alleles of the H. pylori isolates were identified by polymerase chain reaction. The isolates’ metronidazole susceptibility was also determined using the E-test method, and the resistant gene was characterised by sequencing.

RESULTS: More than 90% of the tested isolates had at least one gene in the cagPAI region, and cag67 was predominantly detected in the strains isolated from the Chinese patients, compared with the Malay and Indian patients (P < 0.0001). The majority of the isolates (88%) exhibited partial deletion (rearrangement) in the cagPAI region, with nineteen different patterns observed. Strains with intact or deleted cagPAI regions were detected in 3.2% and 8.4% of isolates, respectively. The prevalence of vacA s1m1 was significantly higher in the Malay and Indian isolates, whereas the isolates from the Chinese patients were predominantly genotyped as vacA s1m2 (P = 0.018). Additionally, the isolates from the Chinese patients were more sensitive to metronidazole than the isolates from the Malay and Indian patients (P = 0.047). Although we attempted to relate the cagPAI genotypes, vacA alleles and metronidazole susceptibilities to disease outcome, no association was observed. The vacA alleles were distributed evenly among the strains with intact, partially deleted or deleted cagPAI regions. Interestingly, the strains exhibiting an intact cagPAI region were sensitive to metronidazole, whereas the strains with a deleted cagPAI were more resistant.

CONCLUSION: Successful colonisation by different H. pylori genotypes is dependent on the host’s genetic makeup and may play an important role in the clinical outcome.

Low frequency of cagA-positive Helicobacter pylori strains isolated from Iranian patients with MALT lymphoma

Helicobacter pylori is predominantly involved in the etiology of digestive diseases. The aim of our study is to determine the relationship of cagA frequency with less investigated gastroduodenal disorders such as MALT (mucosal associated lymphoid tissue) lymphoma and gastric cancer. One hundred-twenty eight H. pylori-positive patients including: gastritis (n = 74), gastric cancer (n = 26) and MALT lymphoma (n = 28) were entered in our study. Antral biopsy specimen transport, bacterial culture and cagA detection were performed based on standard protocols. In brief, biopsies from positive H. pylori patients were investigated for presence of cagA gene by polymerase chain reactions (PCR) method. Of 128 consecutive Iranian patients with gastroduodenal disorders examined in our study, we identified 84 (65.6%) cagA-positive strains. However, six patients were excluded because of negative culture for identification of H. pylori. Prevalence of cagA in each categorized groups are following: 63/74 (85.1%) of gastritis patients, 16/28 (57.1%) and 5/26 gastric cancer (19.2%) of MALT lymphoma, respectively. Current findings reveal that the presence of cagA is not a reliable marker for prediction of digestive disorders caused by H. pylori infection. All our patients with gastric cancer were diagnosed as adenocarcinoma. The low rate of cagA among gastric cancer and MALT lymphoma groups was not statistically significant, possibly due to the small number of patients enrolled in the study. We suggest that a study with a high number of patients is needed for making more definitive assessment of the correlation between cagA-positive H. pylori and gastric cancer and MALT lymphoma.

A novel NOD1- and CagA-independent pathway of interleukin-8 induction mediated by the Helicobacter pylori type IV secretion system

The type IV secretion system (T4SS) of Helicobacter pylori triggers massive inflammatory responses during gastric infection by mechanisms that are poorly understood. Here we provide evidence for a novel pathway by which the T4SS structural component, CagL, induces secretion of interleukin-8 (IL-8) independently of CagA translocation and peptidoglycan-sensing nucleotide-binding oligomerization domain 1 (NOD1) signalling. Recombinant CagL was sufficient to trigger IL-8 secretion, requiring activation of α5 β1 integrin and the arginine-glycine-aspartate (RGD) motif in CagL. Mutation of the encoded RGD motif to arginine-glycine-alanine (RGA) in the cagL gene of H. pylori abrogated its ability to induce IL-8. Comparison of IL-8 induction between H. pylori ΔvirD4 strains bearing wild-type or mutant cagL indicates that CagL-dependent IL-8 induction can occur independently of CagA translocation. In line with this notion, exogenous CagL complemented H. pylori ΔcagL mutant in activating NF-κB and inducing IL-8 without restoring CagA translocation. The CagA translocation-independent, CagL-dependent IL-8 induction involved host signalling via integrin α5 β1 , Src kinase, the mitogen-activated protein kinase (MAPK) pathway and NF-κB but was independent of NOD1. Our findings reveal a novel pathway whereby CagL, via interaction with host integrins, can trigger pro-inflammatory responses independently of CagA translocation or NOD1 signalling.

Helicobacter pylori genotypes can predict gastric tissue histopathology: a longitudinal study of Iranian patients

INTRODUCTION

Several factors have been suggested to account for differences in the virulence of Helicobacter pylori infections in various populations. Evidence suggests the existence of different strains of H. pylori with different degrees of virulence. The present study aimed to investigate the gastric histopathology in Iranian patients infected with H. pylori and to investigate the relationship between the severity of gastritis and four different bacterial virulence-associated genotypes.

METHODS AND MATERIALS

All of the patients with positive results from a pathological examination, a rapid urease test, and PCR analysis for H. pylori infection were consecutively included into the study. The classification and grading of gastritis were performed according to the Sydney System. Esophagitis was classified endoscopically according to the Savary-Miller grading system. The primers used in this study targeted 16S rRNa (521 bp), Urease A (411 bp), Cag A (400 bp), and 26 kDa (303 bp).

RESULTS

Twenty-eight patients were included in the study. The presence of Cag A showed a significant relationship with higher gastritis grades (3.0±0.7 vs. 2.3±0.9, p=0.024) and higher scores for H. pylori infection (3.0±0.7 vs. 2.3±0.7, p=0.027). The patients infected with 26 kDa-positive H. pylori had significantly higher infection scores (3.5±0.6 vs. 2.5±0.6, p=0.020).

CONCLUSION

This study showed that CagA-positive H. pylori infection is associated with more severe gastritis and with increased bacterial density and inflammation in the biopsy specimens. The 303-bp positive genotype was also significantly associated with higher grades of esophagitis. Additional in-depth trials will be helpful in extending our findings.

Infection with specific Helicobacter pylori-cag pathogenicity island strains is associated with interleukin-1B gene polymorphisms in Venezuelan chronic gastritis patients

BACKGROUND

The cag pathogenicity island (cag-PAI) is one of the major virulence factors of Helicobacter pylori, showing considerable geographic variation.

AIM

We investigated the prevalence of cagA, cagE, and cagT genes of cag-PAI and their association with proinflammatory IL-1B-511/-31/+3954 polymorphisms in Venezuelan chronic gastritis patients from a high-risk gastric cancer region.

METHODS

Presence of cag-PAI genes and IL-1B polymorphisms in 121 biopsy specimens was evaluated by polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism (RFLP), respectively.

RESULTS

cagA (+) and triple-positive (cagAET (+)) strains were detected in 79.3% and 70.2% of patients, respectively. We found that infection with cagA (+) and cagAET (+) strains was associated (P < 0.05) with hosts harboring both IL-1B +3954C allele and IL-1B-511T/-31C/+3954C haplotype (TCC (+)). The frequency of gastric atrophy was significantly higher (P < 0.020) among cagAET (+)/IL-1B-TCC (+) combined genotype carriers.

CONCLUSION

Carriage of IL-1B +3954C allele and IL-1B-TCC (+) haplotype could favor colonization of bacterial cagAET (+) strains, and the combination of these bacterial and host haplotypes could play a synergistic role in development of premalignant gastric lesions. This work contributes to understanding of the complex interaction between H. pylori virulence factors and cytokine genotypes involved in gastrointestinal diseases.

Intact cag pathogenicity island of Helicobacter pylori without disease association in Kolkata, India

Several genes including the cagA in the cag pathogenicity island (cag PAI) of Helicobacter pylori are thought to be associated with the gastroduodenal diseases and hence variation in the genetic structure of the cag PAI might be responsible for different clinical outcomes. Our study was undertaken to characterize the cag PAI of H. pylori strains from duodenal ulcer (DU) patients and asymptomatic or non-ulcer dyspepsia (NUD/AV) subjects from Kolkata, India. Strains isolated from 52 individuals (30DU and 22NUD/AV) were analyzed by PCR using 83 different primers for the entire cag PAI and also by dot-blot hybridization. Unlike H. pylori strains isolated from other parts of India, 82.6% of the strains used in this study had intact cag PAI, 9.6% had partially deleted cag PAI, and 7.7% of the strains lacked the entire cag PAI. Dot-blot hybridization yielded positive signals in 100% and 93.8% of PCR-negative strains for HP0522-523 and HP0532-HP0534 genes, respectively. An intact cagA promoter region was also detected in all cagA-positive strains. Furthermore, the expression of cagA mRNA was confirmed by RT-PCR for the representative strains from both DU and NUD/AV subjects indicating the active cagA promoter regions of these strains. A total of 66.7% of Kolkata strains produced a ∼390-bp shorter amplicon than the standard strain 26695 for the HP0527 gene, homologue of virB10. However, sequence analyses confirmed that the deletion did not alter the reading frame of the gene, and mRNA transcripts were detected by RT-PCR analysis. The strains isolated from DU and NUD/AV express CagA protein and possess a functional type IV secretion system, as revealed by Western blot analyses. Interestingly, no significant differences in cag PAI genetic structure were found between DU and NUD/AV individuals suggesting that other bacterial virulence factors, host susceptibility, and environmental determinants also influence the disease outcome at least in certain geographical locations.

Helicobacter pylori defines local immune response through interaction with dendritic cells

The bacterial pathogen Helicobacter pylori colonizes the human gastric and duodenal mucosa, evades clearance by the host response and is associated with peptic ulcer disease and an increased risk of gastric adenocarcinoma. Dendritic cells (DCs) are initiators of the immune response to H. pylori. The aim of the current study was to investigate the interaction between H. pylori with DCs. To determine the impact of H. pylori on the maturation and the activation of monocyte-derived DCs, the effect of 20 clinical H. pylori strains with different inflammatory backgrounds on adenocarcinoma gastric epithelial cells was investigated. The inflammatory background was defined according to the degree of lymphocyte and granulocyte infiltration and the bacterial density at the site of infection. DC maturation and activation varied after exposure to the different strains. While maturation appeared to be independent of any virulence factor tested, a significant increase in the average level of cytokine production was observed for the proinflammatory cytokines interleukin-12 (IL-12), tumour necrosis factor-α, IL-6 and IL-1β when comparing strains with low inflammatory backgrounds with those of the medium or high backgrounds. In conclusion, the DC response towards different strains in vitro was associated with the clinical outcome of the individual host, suggesting a major role of this cell type in modulating strain-specific H. pylori infection.

The cag PAI is intact and functional but HP0521 varies significantly in Helicobacter pylori isolates from Malaysia and Singapore

Helicobacter pylori-related disease is at least partially attributable to the genotype of the infecting strain, particularly the presence of specific virulence factors. We investigated the prevalence of a novel combination of H. pylori virulence factors, including the cag pathogenicity island (PAI), and their association with severe disease in isolates from the three major ethnicities in Malaysia and Singapore, and evaluated whether the cag PAI was intact and functional in vitro. Polymerase chain reaction (PCR) was used to detect dupA, cagA, cagE, cagT, cagL and babA, and to type vacA, the EPIYA motifs, HP0521 alleles and oipA ON status in 159 H. pylori clinical isolates. Twenty-two strains were investigated for IL-8 induction and CagA translocation in vitro. The prevalence of cagA, cagE, cagL, cagT, babA, oipA ON and vacA s1 and i1 was >85%, irrespective of the disease state or ethnicity. The prevalence of dupA and the predominant HP0521 allele and EPIYA motif varied significantly with ethnicity (p < 0.05). A high prevalence of an intact cag PAI was found in all ethnic groups; however, no association was observed between any virulence factor and disease state. The novel association between the HP0521 alleles, EPIYA motifs and host ethnicity indicates that further studies to determine the function of this gene are important.

The relationship between Helicobacter pylori genes cagE and virB11 and gastric cancer

BACKGROUND

The association between Helicobacter pylori gene diversity and gastric cancer has been poorly reported, although it is one of the important ways to explain the gastric pathogenesis. The aim of this study was to investigate the frequency of cagE and virB11 genes in H. pylori isolated from patients with gastric cancer and to analyze the histology profiles.

MATERIALS AND METHODS

The presence of H. pylori and subtypes (cagE and virB11) was detected by PCR from the genomic DNA of 101 patients who had been diagnosed with gastric cancer. The cases were grouped according to the presence/absence of the genes studied and were analyzed in relation to histopathological parameters.

RESULTS

H. pylori infection was detected in 94 out of 101 (93.1%) gastric carcinomas. The cases were categorized into the following groups: cagE+/virB11+, cagE+/virB11-, cagE-/virB11+, and cagE-/virB11-. Frequencies were: 50% (47/94) cagE+/virB11+, 3.2% (3/94) cagE+/virB11-, 10.6% (10/94) cagE-/virB11+, and 36.2% (34/94) cagE-/virB11-. Tumors in the gastric antrum were predominant. An exception was the cagE-/virB11- group, in which tumors had a tendency to be located in the gastric cardia; the majority of the cardia tumors (56% (14/25)) were in this group. Intestinal histology type was the most frequent, but the cagE+/virB11- group only had diffuse tumors. H. pyloricagE+/virB11+ occurred most frequently (except at stage III), and was present at all gastric cancer stages.

CONCLUSIONS

This study is the first to include a relevant number of gastric cancer cases with H. pylori infection, reporting the frequency and relationship of cagE and virB11 genes and the genesis of this tumor. The presence of these cag pathogenicity island genes shows that they are important factors for the pathogenesis and malignancy of gastric cancer related to H. pylori.

Helicobacter pylori cagA status and peptic ulcer disease in Iran

Helicobacter pylori contributes to the development of peptic ulcers and atrophic gastritis. Furthermore, H. pylori strains carrying the cagA gene are more virulent than cagA -negative strains and are associated with the development of gastric adenocarcinoma. The cagA gene is a putative H. pylori virulence factor of unknown function. The aim of this study was to determine the prevalence of the cagA gene among H. pylori isolates and its relationship with peptic ulcer disease in 128 Iranian patients. A total of 107 (83.6%) samples were positive, including 40 (95%) of the 42 patients with duodenal ulcer, 43 (86%) of the 50 patients with gastric ulcer, and 24 (66.6%) of the 36 patients with gastritis. cagA was present in 32 (80%) of 40 strains from duodenal ulcer patients, 33 (77%) of 43 strains from gastric ulcer patients, and 11 (46%) of 24 from gastritis patients. We also attempted to investigate the subtypes of 3' region of cagA gene in H. pylori strains isolated from Iranian patients and their relation to H. pylori-associated gastroduodenal diseases. The PCR product of cagA positive strains obtained with primer set CAG1/CAG2 differed in size, varying from 642 to 651 bp (subtype A) in 33 isolates to 756 bp (subtype B/D) in 13 isolates. This does not support the view that subtypes of the 3' region of cagA gene in H. pylori isolated from Iran correlate with the clinical outcomes of H. pylori, but colonization with cagA positive strains was significantly higher among duodenal ulcer than gastritis patients in Iran.

Molecular characterization of Helicobacter pylori VacA induction of IL-8 in U937 cells reveals a prominent role for p38MAPK in activating transcription factor-2, cAMP response element binding protein, and NF-kappaB activation

Helicobacter pylori VacA induces multiple effects on susceptible cells, including vacuolation, mitochondrial damage, inhibition of cell growth, and enhanced cyclooxygenase-2 expression. To assess the ability of H. pylori to modulate the production of inflammatory mediators, we examined the mechanisms by which VacA enhanced IL-8 production by promonocytic U937 cells, which demonstrated the greatest VacA-induced IL-8 release of the cells tested. Inhibitors of p38 MAPK (SB203580), ERK1/2 (PD98059), IkappaBalpha ((E)-3-(4-methylphenylsulfonyl)-2-propenenitrile), Ca(2+) entry (SKF96365), and intracellular Ca(2+) channels (dantrolene) blocked VacA-induced IL-8 production. Furthermore, an intracellular Ca(2+) chelator (BAPTA-AM), which inhibited VacA-activated p38 MAPK, caused a dose-dependent reduction in VacA-induced IL-8 secretion by U937 cells, implying a role for intracellular Ca(2+) in mediating activation of MAPK and the canonical NF-kappaB pathway. VacA stimulated translocation of NF-kappaBp65 to the nucleus, consistent with enhancement of IL-8 expression by activation of the NF-kappaB pathway. In addition, small interfering RNA of activating transcription factor (ATF)-2 or CREB, which is a p38MAPK substrate and binds to the AP-1 site of the IL-8 promoter, inhibited VacA-induced IL-8 production. VacA activated an IL-8 promoter containing an NF-IL-6 site, but not a mutated AP-1 or NF-kappaB site, suggesting direct involvement of the ATF-2/CREB binding region or NF-kappaB-binding regions in VacA-induced IL-8 promoter activation. Thus, in U937 cells, VacA directly increases IL-8 production by activation of the p38 MAPK via intracellular Ca(2+) release, leading to activation of the transcription factors, ATF-2, CREB, and NF-kappaB.

Helicobacter pylori cagA and iceA genotypes status and risk of peptic ulcer in Saudi patients

OBJECTIVE

To determine the prevalence of cagA+ and iceA genotypes among Helicobacter pylori (H. pylori) isolates from a group of Saudi patients with gastric complaints, and to find out any significant correlation between these strains and severe gastric clinical outcomes such as peptic ulcer and gastric cancer in Saudi population.

METHODS

A total of 1104 gastric biopsies from 368 patients who presented with symptoms suggestive of chronic gastritis, peptic ulcer disease, or gastric carcinoma were taken from the main hospitals in the Western region of Saudi Arabia from July 2004 to July 2005. We cultured the samples for H. pylori and a polymerase chain reaction was carried out to check for the presence or absence of cagA gene and the status of iceA genotypes.

RESULTS

Among the 368 suspected patients to be infected with H. pylori by means of clinical features and endoscopic findings; 103 (28%) were positive using culture technique. The relation of the presence of cagA and the development of cases to gastritis and ulcer was statistically significant (p=0.0001). Furthermore, this study revealed that 100% of ulcer cases were infected with iceA1 with a statistically significant correlation (p=0.0001), while 94.6% of gastritis and 90.9% of normal were infected with iceA2 (p=0.0001). Moreover cagA+/iceA1 combined genotypes was statistically correlated with peptic ulcer (100%) but not cagA-/iceA1 (0%; p=0.0001).

CONCLUSION

Certain H. pylori genotypes were more virulent than others. Multiple clinical implications based on these finding might be studied further.

A preliminary study on the genetic profile of cag pathogenicity-island and other virulent gene loci of Helicobacter pylori strains from Turkey

Helicobacter pylori genetic diversity affects the function and antigenicity of virulence factors associated with the disease outcome. Gene profile was done to identify the distribution of gene loci within and outside the cag pathogenicity-island (PAI). H. pylori strains from 35 patients [21 gastritis, 14 peptic ulcer diseases (PUD)] were analyzed using PCR. The profile of the cag PAI was evaluated using primers spanning the 3' end, cagA, promoter region of the cagA, cagE, cagT, 5' end (LEC), extreme right end, plasticity region open reading frames (ORFs), oipA (Hp0638) and vacA alleles. We found few intact cag PAI in the strains examined. Deletions were found in LEC1 (9.5% versus 14.3%), LEC2 (4.8% versus 14.3%), cagT (33.3% versus 28.6%), cagE (28.6% versus 28.6%) and the promoter region of the cagA (19.0% versus 42.9%) of gastritis and PUD strains, respectively. The cagA gene was detectable in 57.1% of gastritis and 92.9% of PUD-associated strains. The cagRJ region also showed deletions for many of its genes. The oipA (Hp0638) gene was detected in 80.9% of gastritis and in 92.9% of PUD strains. The plasticity region ORFs JHP912 and JHP931 were predominant in PUD strains. The vacA-s1a-m1a genotype was predominant in PUD, while s2m2 in gastritis strains. This comprehensive analysis showed deletions in several genes within and outside the cag PAI. However, cagA, oipA, JHP912, JHP931 and vacA-s1a-m1a were more predominant in PUD strains than gastritis-associated strains, suggesting the importance of genetic diversity on the disease progression and clinical outcome.

Heterogeneity in the activity of Mexican Helicobacter pylori strains in gastric epithelial cells and its association with diversity in the cagA gene

Helicobacter pylori CagA is translocated into gastric epithelial cells by a type IV secretion system and interacts with the Src homology 2 phosphatase, altering cell morphology. Multiple EPIYA motifs in CagA are associated with increased activity in cells and with gastric cancer. The aim of this work was to study the heterogeneity in activity in cells of multiple H. pylori single colonies isolated from a single patient and its association with polymorphism in cagA. The presence of cagA, cagE, cagT, and cag10 was studied with 318 H. pylori isolates from the antra and corpora of 18 patients. AGS gastric epithelial cells were infected with 75 isolates, and interleukin-8 (IL-8) secretion, cytoskeletal changes, CagA translocation, and tyrosine phosphorylation were measured. The cagA 3'-variable region was sequenced for 30 isolates to determine the number and types of EPIYA motifs. Isolates from an individual stomach were usually genetically related and had quantitatively similar phenotypic effects on cells (IL-8 induction and cytoskeletal changes). However, strains from different patients with similar CagA EPIYA motif patterns varied widely in these phenotypes. Among isolates with an EPIYA-ABC pattern, the phenotype was variable: IL-8 induction ranged from 200 to 1,200 pg/ml, and morphological changes occurred in 20 to 70% of cells. In several cases, cagA sequence diversity appeared to explain the lack of CagA activity, as isolates with an EPIYA-ACC pattern or a modified B motif had reduced cell activity. cag pathogenicity island-positive H. pylori isolates displayed a high level of heterogeneity in the capacity to induce IL-8 secretion and morphological changes; an absent or modified B motif was associated with low activity.

Helicobacter pylori cag pathogenicity island genes: clinical relevance for peptic ulcer disease development in Brazil

The purpose of this study was to verify whether the presence of any of the Helicobacter pylori cagPAI genes or segments--cagA, cagA promoter, cagE, cagM, tnpB, tnpA, cagT and the left end of the cag II (LEC) region--would be a useful marker for the risk of peptic ulcer disease development. H. pylori DNA extracted from positive urease tests of 150 peptic ulcer patients and 65 dyspeptic controls was analysed by PCR. Duodenal ulcers were present in 110, gastric ulcers in 23 and both gastric and duodenal ulcers in 17 patients. A significant association (P <0.001) was found between a conserved cagPAI and peptic ulcer disease (34 %). The positivity of the cagA gene varied according to the region of the gene that was amplified. The region near to the promoter was present in almost all of the H. pylori isolates (97.2 %). The segment from nt 1764 to 2083 and the extreme right end were frequently deleted in the isolates from the controls (P <0.01). The positivity of the promoter region of cagA and cagT, cagE, cagM and LEC showed a significant difference between the isolates from peptic ulcer patients and from the controls (P <0.01). Patients usually had moderate gastritis; however, the intensity of the active inflammation was higher in the peptic ulcer group (P <0.001). cagT, cagM, LEC and the right end terminus of the cagA-positive H. pylori isolates were associated with a 27-fold, 8-fold, 4-fold and 4-fold risk of peptic ulcer disease, respectively, and may be useful markers to identify individuals at higher risk of peptic ulcer disease development in Brazil.

Prevalence of Helicobacter pylori vacA, cagA, cagE, iceA, babA2 genotypes and correlation with clinical outcome in Turkish patients with dyspepsia

BACKGROUND

Distinct virulence factors of Helicobacter pylori have been associated with clinical outcome of the infection; however, considerable variations have been reported from different geographic regions and data on genotypes of Turkish H. pylori isolates are sparse.

AIM

To determine the prevalence of specific genotypes of H. pylori in Turkish patients with dyspepsia.

MATERIALS AND METHODS

Ninety-three H. pylori-positive patients [30 with non-ulcer dyspepsia (NUD), 30 with duodenal ulcer (DU), and 33 with gastric cancer (GC)] who were admitted to our endoscopy unit due to dyspepsia were enrolled in the study. H. pylori infection was confirmed in all patients by histology and rapid urease test (RUT). The presence of vacA alleles, cagA, cagE, iceA, and babA2 genotypes were determined by polymerase chain reaction (PCR). Chi-squared test and Fisher's exact test were used for statistical comparisons and multivariate regression analysis was performed to find out independent predictors of different clinical outcomes.

RESULTS

Turkish strains examined predominantly possessed the vacA s1,m2 (48.4%) and s1,m1 (40.7%) genotypes. The vacA s1a genotype was detected in 66.7, 96.4, and 87.9% of isolates from patients with NUD, DU, and GC, respectively, and its presence was significantly associated with that of DU (p = .004), GC (p = .043), and cagA gene (p = .021). None of the cases was found to harbor the s1c genotype. The frequencies of the cagA and cagE genes among studied isolates were 73.6 and 59.3%, respectively. The cagA gene was significantly associated with the presence of DU (p = .004) and GC (p = .003), and the cagE gene, too, was significantly associated with the presence of DU (p = .002) and GC (p = .000). All H. pylori isolates possessed the iceA gene. In all, 68 isolates (74.7%) were positive for iceA1 and 23 (25.3%) for iceA2. The frequency of icea1 gene was significantly higher in cases with GC (85%) than in cases with NUD (60%) (p = .026). The frequency of babA2 gene was 23.3, 46.4, and 87.9% in isolates of patients with NUD, DU, and GC, respectively. When compared to cases with NUD (p = .000) and DU (p = .000), the presence of babA2 gene was significantly higher in cases with GC. Multivariate regression analysis disclosed cagE (p = .006) and vacA s1a (p = .027) genotypes to be independent predictors of DU and babA2 (p = .000) and cagE (p = .013) genotypes to be independent predictors of GC.

CONCLUSIONS

H. pylori vacA s1a, cagA, cagE genotypes have significant relations with the presence of DU and GC, and iceA1, babA2 with GC in Turkish patients with dyspepsia, whereas cagE and vacA s1a genotypes are independent predictors of DU, and babA2 and cagE genotypes are independent predictors of GC.

Cag pathogenicity island-independent up-regulation of matrix metalloproteinases-9 and -2 secretion and expression in mice by Helicobacter pylori infection

Helicobacter pylori cag pathogenicity island (PAI) is a major determinant of gastric injury via induction of several matrix metalloproteinases (MMPs). In the present study, we examined the influence of the cag PAI on gastric infection and MMP-9 production in mice and in cultured cells. A new mouse colonizing Indian H. pylori strain (AM1) that lacks the cag PAI was used to study the cag PAI importance in inflammation. Groups of C57BL/6 mice were inoculated separately with H. pylori strains AM1 and SS1 (cag+), gastric tissues were histologically examined, and bacterial colonization was scored by quantitative culture. Mice infected with either cag+ or cag- H. pylori strains showed gastric inflammation and elevated MMP-3 production. Significant up-regulation of pro-MMP-9 secretion and gene expression in H. pylori infected gastric tissues indicate dispensability of cag PAI for increased pro-MMP-9 secretion and synthesis in mice. In agreement, cell culture studies revealed that both AM1 and SS1 were equipotent in pro-MMP-9 induction in human gastric epithelial cells. Both strains showed moderate increase in MMP-2 activity in vivo and in vitro. In addition, increased secretion of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and IL-6 induced pro-MMP-9 secretion and synthesis in AM1 or SS1 strain-infected mice suggesting elicitation of pro-inflammatory cytokines by both cag- and cag+ genotype. Moreover, tissue inhibitors of metalloproteinase-1 expression were decreased with increase in pro-MMP-9 induction. These data show that H. pylori may act through different pathways other than cag PAI-mediated for gastric inflammation and contribute to up-regulation of MMP-9 via pro-inflammatory cytokines.

Association between cag-pathogenicity island in Helicobacter pylori isolates from peptic ulcer, gastric carcinoma, and non-ulcer dyspepsia subjects with histological changes

AIM

To investigate the presence of the cag-pathogenicity island and the associated histological damage caused by strains with complete cag-PAI and with partial deletions in correlation to the disease status.

METHODS

We analyzed the complete cag-PAI of 174 representative Helicobacter pylori (H pylori ) clinical isolates obtained from patients with duodenal ulcer, gastric ulcer, gastric cancer, and non-ulcer dyspepsia using eight different oligonucleotide primers viz cagA1, cagA2, cagAP1, cagAP2, cagE, cagT, LEC-1, LEC-2 spanning five different loci of the whole cag-PAI by polymerase chain reaction (PCR).

RESULTS

The complete screening of the genes comprising the cag-PAI showed that larger proportions of subjects with gastric ulcer (97.8%) inhabited strains with complete cag-PAI, followed by gastric cancer (85.7%), non-ulcer dyspepsia (7.1%), and duodenal ulcer (6.9%), significant differences were found in the percentage distribution of the genes in all the clinical groups studied. It was found that strains with complete cag-PAI were able to cause severe histological damage than with the partially deleted ones.

CONCLUSION

The cag-PAI is a strong virulent marker in the disease pathogenesis as it is shown that a large number of those infected with strain with complete cag-PAI had one or the other of the irreversible gastric pathologies and interestingly 18.5% of them developed gastric carcinoma. The presence of an intact cag-PAI correlates with the development of more severe pathology, and such strains were found more frequently in patients with severe gastroduodenal disease. Partial deletions of the cag-PAI appear to be sufficient to render the organism less pathogenic.

Heterogeneity of cag genotypes and clinical outcome of Helicobacter pylori infection

Helicobacter pylori infecting strains may include colony subtypes with different cytotoxin-associated gene (cag) genotypes. We sought to determine whether the cag heterogeneity of infecting strains is related to the clinical outcome of infection. Gastric biopsies for culture and histologic study were taken from 19 patients infected with cagA-positive strains (6 with duodenal ulcer, 8 with atrophic gastritis, and 5 with nonatrophic gastritis). For each biopsy, DNA was extracted from 10 single colonies and from a sweep of colonies. Polymerase chain reaction (PCR) for cagA and cagE (both located in the right half of cag) and virB11 (located in the left half of cag) was performed. Random amplified polymorphic DNA PCR (RAPD-PCR) and sequencing of glmM PCR product were performed to verify strain identity of colonies with different cag genotypes. In all patients, PCR from sweeps were positive for cagA, showing that all specimens contained cagA-positive H. pylori subtypes. In 11 patients, PCR products from all colonies were positive for cagA, cagE, and virB11, but in 8 patients, PCR products from varying numbers of colonies were negative for 1 or more cag genes. RAPD-PCR and sequencing of glmM PCR product confirmed the strain identities of colonies with different cag genotypes. We detected cag deletions in 6 of 8, 2 of 5, and 0 of 6 patients with atrophic gastritis, nonatrophic gastritis, and duodenal ulcer, respectively (P = .02). In conclusion, changes in cag genotype in single colony isolates from subjects infected with cagA-positive H. pylori strains are more common in atrophic than in nonatrophic gastritis or duodenal ulcer. These findings are consistent with host-induced (acid secretion?) adaptive changes in cag genotype during infection.

Etiology of Gastric Cancer: What Is New?

Recent advances in understanding of risk factors for gastric cancer have focused attention on genetic polymorphisms in both the human host and in Helicobacter pylori. Variation in genes for cytokines such as interleukin-1beta and its receptor antagonist may allow identification of those individuals predisposed to mount an immune response that puts them at elevated risk for gastric cancer. Likewise, analysis of how genetic variation in the genome of H. pylori may modulate the action of virulence factors like CagA may prove useful in identification of persons for whom H. pylori eradication efforts would be most important. This review examines recent studies on interleukin-1beta polymorphisms and H. pylori CagA variation with respect to their modulation of risk for gastric cancer.

The cag pathogenicity island of Helicobacter pylori is disrupted in the majority of patient isolates from different human populations

The cag pathogenicity island (cag-PAI) is one of the major virulence determinants of Helicobacter pylori. The chromosomal integrity of this island or the lack thereof is speculated to play an important role in the progress of the gastroduodenal pathology caused by H. pylori. We determined the integrity of the cag-PAI by using specific flanking and internally anchored PCR primers to know the biogeographical distribution of strains carrying fully integral cag-PAI with proinflammatory behavior in vivo. Genotypes based on eight selected loci were studied in 335 isolates obtained from eight different geographic regions. The cag-PAI appeared to be disrupted in the majority of patient isolates throughout the world. Conservation of cag-PAI was highest in Japanese isolates (57.1%). However, only 18.6% of the Peruvian and 12% of the Indian isolates carried an intact cag-PAI. The integrity of cag-PAI in European and African strains was minimal. All 10 strains from Costa Rica had rearrangements. Overall, a majority of the strains of East Asian ancestry were found to have intact cag-PAI compared to strains of other descent. We also found that the cagE and cagT genes were less often rearranged (18%) than the cagA gene (27%). We attempted to relate cag-PAI rearrangement patterns to disease outcome. Deletion frequencies of cagA, cagE, and cagT genes were higher in benign cases than in isolates from severe ulcers and gastric cancer. Conversely, the cagA promoter and the left end of the cag-PAI were frequently rearranged or deleted in isolates linked to severe pathology. Analysis of the cag-PAI genotypes with a different biogeoclimatic history will contribute to our understanding of the pathogen-host interaction in health and disease.

Helicobacter pylori and gastroduodenal pathology: new threats of the old friend

The human gastric pathogen Helicobacter pylori causes chronic gastritis, peptic ulcer disease, gastric carcinoma, and mucosa-associated lymphoid tissue (MALT) lymphoma. It infects over 50% of the worlds' population, however, only a small subset of infected people experience H. pylori-associated illnesses. Associations with disease-specific factors remain enigmatic years after the genome sequences were deciphered. Infection with strains of Helicobacter pylori that carry the cytotoxin-associated antigen A (cagA) gene is associated with gastric carcinoma. Recent studies revealed mechanisms through which the cagA protein triggers oncopathogenic activities. Other candidate genes such as some members of the so-called plasticity region cluster are also implicated to be associated with carcinoma of stomach. Study of the evolution of polymorphisms and sequence variation in H. pylori populations on a global basis has provided a window into the history of human population migration and co-evolution of this pathogen with its host. Possible symbiotic relationships were debated since the discovery of this pathogen. The debate has been further intensified as some studies have posed the possibility that H. pylori infection may be beneficial in some humans. This assumption is based on increased incidence of gastro-oesophageal reflux disease (GERD), Barrett's oesophagus and adenocarcinoma of the oesophagus following H. pylori eradication in some countries. The contribution of comparative genomics to our understanding of the genome organisation and diversity of H. pylori and its pathophysiological importance to human healthcare is exemplified in this review.

Analysis of the cag pathogenicity island and IS605 of Helicobacter pylori strains isolated from patients with gastric cancer in Japan

BACKGROUND

CagA protein is encoded by the cagA gene, which is part of the cag pathogenicity island (PAI) in Helicobacter pylori. Insertion sequence (IS) elements are a diverse set of specialized DNA segments that can move to new sites in bacterial genomes.

AIM

To determine the role of cagPAI and IS605 in the development of gastric cancer, we analysed cagPAI from patients with gastric cancer and compared the results with the host's CagA antibody status.

METHODS

H. pylori strains were isolated from 29 gastric cancer patients, and CagA status was determined by measuring serum antibody against CagA. The cagPAI region and IS605 were determined by PCR.

RESULTS

CagA seropositivity tended to be higher in the IS605/PAI+ group (5/7, 71.4%) than in the IS605/PAI- group (9/22, 40.9%). Association with cag13 was more frequent in the IS605+ group (92.3%; 12/13) than in the IS605- group (25.0%; 4/16; P = 0.0005).

CONCLUSIONS

cag13 may be associated with the presence of IS605 in gastric cancer patients.

Analysis of Helicobacter pylori genotypes and correlation with clinical outcome in Turkey

The predominant Helicobacter pylori strains circulating among geographic locations differ in regard to genomic structure. The association of the cagA-positive, vacA s1 genotypes with peptic ulcer disease (PUD) and gastric cancer was reported in Western countries but not in East Asian countries. Strains from Western countries predominantly possessed cagA type 2a, vacA s1a or s1b/m1a, or vacA m2a genotypes, whereas strains from East Asia possessed cagA type 1a, vacA s1c/m1b, or vacA m2b genotypes. Whether the Turkish strains possessed such genotypes was investigated and correlated with the disease outcome. Seventy-three patients from Turkey were enrolled. H. pylori was detected in 65 (89%) patients (22 with gastritis, 33 with PUD, and 10 with gastric cancer) by any of the following tests: Campylobacter-like organism test, culture, or PCR. Among the H. pylori-positive patients, presence of the cagA gene (78%) was significantly associated with PUD (P < 0.00001), gastric cancer (P < 0.001), and vacA s1a genotypes (P < 0.0001). Multiple vacA genotypes were more prevalent in PUD and gastric cancer patients than in patients with gastritis. Restriction fragment length polymorphism analysis of the cagA gene revealed three different patterns with no significant association with clinical outcome. Turkish strains examined predominantly possessed cagA type 2a, vacA s1a/m1a, or vacA m2a genotypes, which were typical genotypes in strains from Western countries. This fact might be one of the reasons for the low prevalence of severe gastroduodenal diseases in Turkey compared to the East Asian countries.

Functional analysis of the cag pathogenicity island in Helicobacter pylori isolates from patients with gastritis, peptic ulcer, and gastric cancer

Helicobacter pylori is the causative agent of a variety of gastric diseases, but the clinical relevance of bacterial virulence factors is still controversial. Virulent strains carrying the cag pathogenicity island (cagPAI) are thought to be key players in disease development. Here, we have compared cagPAI-dependent in vitro responses in H. pylori isolates obtained from 75 patients with gastritis, peptic ulcer, and gastric cancer (n = 25 in each group). AGS gastric epithelial cells were infected with each strain and assayed for (i) CagA expression, (ii) translocation and tyrosine phosphorylation of CagA, (iii) c-Src inactivation, (iv) cortactin dephosphorylation, (v) induction of actin cytoskeletal rearrangements associated with cell elongation, (vi) induction of cellular motility, and (vii) secretion of interleukin-8. Interestingly, we found high but similar prevalences of all of these cagPAI-dependent host cell responses (ranging from 56 to 80%) among the various groups of patients. This study revealed CagA proteins with unique features, CagA subspecies of various sizes, and new functional properties for the phenotypic outcomes. We further showed that induction of AGS cell motility and elongation are two independent processes. Our data corroborate epidemiological studies, which indicate a significant association of cagPAI presence and functionality with histopathological findings in gastritis, peptic ulcer, and gastric cancer patients, thus emphasizing the importance of the cagPAI for the pathogenicity of H. pylori. Nevertheless, we found no significant association of the specific H. pylori-induced responses with any particular patient group. This may indicate that the determination of disease development is highly complex and involves multiple bacterial and/or host factors.

Serum IL-8 as a possible marker for determining the status of Helicobacter pylori infection in patients with untreated and treated peptic ulcer

Failure to eradicate Helicobacter pylori can lead to peptic ulcer recurrence and gastric malignancy. Therefore, the objective of this study was to develop a noninvasive method for determining whether H. pylori infection was eradicated with antibiotic-based triple therapy. A total of 17 patients with duodenal ulcer (DU) and 17 with gastric ulcer (GU) were evaluated both before and after treatment. Outcomes included serum levels of interleukin-8 (IL-8), pepsinogen I, and gastrin, and the Wilcoxon signed rank test was used to test significance. Changes in these parameters were also correlated with disease status. In those patients where both GU and DU healing occurred as a result of treatment, most showed an increase in serum IL-8 and a decrease in serum pepsinogen. Serum gastrin levels were not significantly changed in either group. Posttreatment increases in serum IL-8 were seen in 15 of 17 (88%) recovered DU patients and 14 of 17 (82%) recovered GU patients (P<.05 for each). Posttreatment decreases in pepsinogen I were found in 15 of 17 DU and 15 of 17 GU patients (P<.05 for each). These preliminary findings suggest that an increase in serum IL-8 and possibly a decrease in pepsinogen I may be useful in identifying the successful eradication of H. pylori infection in patients with peptic ulcer treated with antibiotics. A more systematic analysis of these putative diagnostic markers is now warranted.

Eradication of Helicobacter pylori infection improves blood pressure values in patients affected by hypertension

BACKGROUND

Arterial hypertension is a risk factor for atherosclerosis of whose pathogenesis is unknown. Growing evidence underscores the causative role of endothelial dysfunction. A possible association between Helicobacter pylori infection and cardiovascular and autoimmune disorders has been found. The release of cytotoxic substances either of bacterial origin or produced by the host may represent mediators of these systemic sequelae. The aim of our study was to determine the prevalence of H. pylori infection in hypertensive patients and the effects of H. pylori eradication on blood pressure and on digestive symptoms.

MATERIALS AND METHODS

Seventy-two hypertensive patients (34 male and 38 female; mean age 53 +/- 12 years) and 70 normotensive controls (35 male and 35 female; mean age 52 +/- 10 years) were enrolled. All patients were subjected to a first ambulatory blood pressure monitoring (ABPM) at enrollment, a 13C urea breath test and a test for IgG-CagA antibodies, and completed the validated dyspepsia questionnaire. H. pylori-positive patients were treated with triple therapy (amoxicillin, clarithromycin and ranitidine bismute citrate) for 7 days. Control of eradication was assessed by 13C urea breath test, and all patients underwent a second ABPM 6 months after enrollment.

RESULTS

H. pylori infection was 55% in hypertensive patients, with 90% CagA positivity, and 50% in controls, with 60% CagA positivity. At the first ABPM, blood pressure values were similar in H. pylori-positive and -negative individuals; positive patients showed a significant increase in pyrosis and epigastric pain compared to negative patients. H. pylori was eradicated in 80% of patients and in 85% of controls. At the second ABPM, we found a statistically significant decrease in 24-hour mean blood pressure values when compared to the first ABPM only in the eradicated hypertensive group.

CONCLUSIONS

Our study demonstrated a significant decrease in blood pressure values, in particular in diastolic blood pressure values, after H. pylori eradication in hypertensive patients. A high prevalence of CagA positivity was found. The association between cardiovascular disease and H. pylori infection seems pronounced only in CagA-positive patients. The possible links between hypertensive disease and H. pylori infection may involve the activation of the cytokine cascade with the release of vasoactive substances from the primary site of infection, or molecular mimicry between the CagA antigens of H. pylori and some peptides expressed by endothelial cells and smooth muscle cells.

Correlation between cag pathogenicity island composition and Helicobacter pylori-associated gastroduodenal disease

Helicobacter pylori infection is associated with a variety of outcomes ranging from seemingly asymptomatic coexistence to peptic ulcer disease and gastric cancer. The cag pathogenicity island (PAI) contains genes associated with a more aggressive phenotype and has been suggested to be a determinant of severe disease outcome. The cagA gene has served as a marker for the cag PAI. However, the presence of this single gene does not necessarily indicate the presence of a complete set of cag PAI genes. We have analyzed the composition of the cag PAI in 66 clinical isolates obtained from patients with duodenal ulcer, gastric cancer, and nonulcer dyspepsia. Hybridization of DNA to microarrays containing all the genes of the cag PAI showed that 76 and 9% of the strains contained all or none of the cag PAI genes, respectively. Partial deletions of the cag PAI were found in 10 isolates (15%), of which 3 were cagA negative. The ability to induce interleukin-8 (IL-8) production in AGS cells was correlated to the presence of a complete cag PAI. Strains carrying only parts of the island induced IL-8 at levels significantly lower than those induced by cag PAI-positive isolates. The presence of an intact cag PAI correlates with development of more severe pathology, and such strains were found more frequently in patients with severe gastroduodenal disease (odds ratio, 5.13; 95% confidence interval, 1.5 to 17.4). Partial deletions of the cag PAI appear to be sufficient to render the organism less pathogenic.

Distribution of cagG gene in Helicobacter pylori isolates from Chinese patients with different gastroduodenal diseases and its clinical and pathological significance

AIM: To determine the distribution of cagG gene of Helicobacter pylori (H pylori) isolates cultured from patients with various digestive diseases and its relationship with gastroduodenal diseases.

METHODS: cagG was amplified by polymerase chain reaction in 145 H pylori isolates cultured from patients with chronic gastritis (n = 72), duodenal ulcer (n = 48), gastric ulcer (n = 17), or gastric and duodenal ulcer (n = 8), and the relationship between cagG status and the grade of gastric mucosal inflammation was determined.

RESULTS: cagG was present in 91.7% of the 145 H pylori isolates, with the rates were 90.3%, 93.8%, 88.2% and 100.0%, respectively, in those from patients with chronic gastritis, duodenal ulcer, gastric ulcer, and gastric and duodenal ulcer. There was no significant difference among the four groups (P > 0.05). The average grade of gastric mucosal inflammation in the antrum and corpus was 1.819 ± 0.325 and 1.768 ± 0.312, respectively in cagG positive patients, whereas the average inflammation grade was 1.649 ± 0.297, 1.598 ± 0.278 respectively in cagG negative cases (P > 0.05).

CONCLUSION: cagG gene of H pylori was quite conservative, and most H pylori strains in Chinese patients were cagG positive. cagG status was not related to clinical outcome or the degree of gastric mucosal inflammation. Therefore, cagG can not be used as a single marker for discrimination of H pylori strains with respect to a specific digestive disease.

Investigation of the biological relevance of Helicobacter pylori cagE locus diversity, presence of CagA tyrosine phosphorylation motifs and vacuolating cytotoxin genotype on IL-8 induction in gastric epithelial cells

Isolates of Helicobacter pylori from dyspeptic patients in England and South Africa were tested for ability to induce interleukin-8 (IL-8) in gastric cells. All isolates were cagA-positive, which was used as a marker for the presence of the cag pathogenicity island. The aims were to determine if activities were related to diversity within cagE (HP0544), a locus encoding a key component in the Type IV secretion system, and if disease severity might be linked to a combination of strain features. We found that isolates were heterogeneous in ability to induce IL-8 activity with the 23 positive isolates (59%) showing activities ranging from 260 to 3200 pg ml(-1). The cagE locus was detected in most isolates and RFLP analysis of a 1.52-kb internal fragment showed interstrain diversity with 12 combined (MboI/NlaIII) types. Most cagE genotypes were not associated with IL-8 induction, however two genotypes were found only in IL-8-inducing strains and one genotype was associated with lack of IL-8 induction. IL-8 activity was not associated with either the number or composition of cagA tyrosine phosphorylation motifs and vacA m-type. Although we found a weak association between cagE type and the ability to induce IL-8, our results imply that gastric cell factors or bacterial factors other than vacA, cagA and cagE are involved in the induction of IL-8 and the development of severe gastric disease.

Heterogeneity of cag genotypes in Helicobacter pylori isolates from human biopsy specimens

The Helicobacter pylori chromosomal cluster of genes known as the cytotoxin-associated gene (cag) island may have different compositions in infecting strains. In this study, we analyzed 150 single colonies obtained from gastric biopsy specimens from 10 patients infected with cagA-positive H. pylori strains and sweep isolates (isolates harvested with sweep in different points of the plate) from 6 patients infected with cagA-negative strains. Three loci in the cag island (cagA, cagE, and virB11) and the conserved gene glmM (ureC) were investigated by PCR. The levels of anti-H. pylori and anti-CagA antibodies in patient sera were also measured. For subjects infected with cagA-negative strains, all sweep isolates were also negative for cagE and virB11, suggesting the complete absence of the cag island. For subjects infected with cagA-positive strains, most of the isolates were positive for all three genes studied, whereas 24.7% of the isolates had a partial or total deletion of the cag island. cagA, cagE, and virB11 were, respectively, present in 87.3, 77.3, and 90% of the colonies. The deletion of virB11 was always associated with the deletion of cagA and/or cagE. H. pylori colonies with different cag genotypes were isolated within a single gastric biopsy specimen from 3 of the 10 patients and were further characterized by random amplified polymorphic DNA (RAPD) analysis and by sequencing of an arbitrarily selected gene segment. Although the colonies had different cag genotypes, their RAPD profiles were highly similar within each patient, and the nucleotide sequences of the selected gene segment were identical. All of the patients had detectable antibodies against H. pylori, and 9 of 10 had anti-CagA antibodies. In conclusion, we show that a single infecting H. pylori strain may include variable proportions of colony subtypes with different cag genotypes. The extension of our analysis to patients with well-characterized gastric diseases may provide significant information on the relationship between cag genotypes and clinical outcomes of H. pylori infections.

cag pathogenicity island of Helicobacter pylori in Korean children

BACKGROUND

cag pathogenicity island is reported to be a major virulence factor of Helicobacter pylori. The aim of this study was to investigate the status of cag pathogenicity island genes and gastric histology in Korean children with H. pylori gastritis.

METHODS

Helicobacter pylori DNA was extracted from antral biopsy specimens from 25 children with H. pylori gastritis. Specific polymerase chain reaction assays were used for four genes of cag pathogenicity island. The features of gastritis were scored in accordance with the updated Sydney System.

RESULTS

cagA was present in 23 (92%) of 25 children, and cagE in 24 (96%). Twenty-two (88%) children were cagT positive and 19 (76%) virD4 positive. All of the selected genes of the cag pathogenicity island were present in 17 (68%) children and completely deleted in one child. There were no differences in neutrophil activity and chronic inflammation between children infected with intact cag pathogenicity island strains and those with partially or totally deleted-cag pathogenicity island strains.

CONCLUSION

cag pathogenicity island is not a uniform, conserved entity in Korea. Completeness of cag pathogenicity island may not be the major factor to determine the severity of H. pylori gastritis in children.

Functional analysis of the Helicobacter pylori cag pathogenicity island reveals both VirD4-CagA-dependent and VirD4-CagA-independent mechanisms

The type IV secretion machinery encoded by the cag pathogenicity island (PAI) of Helicobacter pylori has been implicated in a series of host responses during infection. Here, we analyzed the function of 12 cag PAI genes from both cag I and cag II loci, including the complete virB/D complex (virB4, virB7, virB8, virB9, virB10, virB11, and virD4). We monitored interleukin-8 (IL-8) secretion, CagA translocation and tyrosine phosphorylation, and induction of a scattering ("hummingbird") phenotype upon H. pylori infection of AGS gastric epithelial cells. For the first time, we have complemented individual cag PAI gene knockout mutants with their intact genes expressed from a shuttle vector and showed that complemented CagA and VirD4 restored wild-type function. Our results demonstrate that phenotypic changes and phosphorylation of CagA depended on all virB/D genes and several other genes of the cag PAI. Induction of IL-8 secretion depended largely on the same set of genes but was independent of CagA and VirD4. Thus, CagA translocation and induction of IL-8 secretion are regulated by VirD4-CagA-dependent and VirD4-CagA-independent mechanisms, respectively. The function of VirD4 as a possible adapter protein which guides CagA into the type IV secretion channel is presented in a model.

Host cell responses to genotypically similar Helicobacter pylori isolates from United States and Japan

Associations of Helicobacter pylori genotypes with disease differ between Western countries and Asia. Therefore, we directly compared histopathological and in vitro responses to clinical isolates with similar genotypes. Sixty-three cagA(+) vacAs1/m1 H. pylori isolates (United States, n = 24; Japan, n = 39) and eight cagA-negative vacAs2/m2 strains were incubated with AGS cells, and supernatants were assayed for interleukin-8 (IL-8) and for DNA fragmentation. CagA tyrosine phosphorylation in AGS cells and the sequence of the putative HP0638 (oipA) signal sequence region were determined for 22 representative strains. HP0638 and/or cag island mutant strains were created and examined in IL-8 and CagA tyrosine phosphorylation assays. Levels of IL-8 induction and DNA fragmentation were similar in the U.S. and Japanese cagA(+) vacAs1/m1 isolates. All 10 of the isolates with the highest IL-8 induction and 8 of the 10 isolates with the lowest IL-8 induction had an in-frame oipA open reading frame, and all 10 of the isolates with the highest IL-8 induction and 7 of the 10 isolates with the lowest IL-8 induction induced CagA tyrosine phosphorylation in AGS cells. Eight isolates from gastric ulcer patients induced significantly more apoptosis in vitro, and more severe gastritis and atrophy in vivo, than other Japanese isolates. Disruption of HP0638 did not affect IL-8 induction or CagA tyrosine phosphorylation. Thus, H. pylori cagA(+) vacAs1/m1 isolates from the United States and Japan induce similar IL-8 and apoptosis levels. Inactivation of HP0638 does not alter epithelial responses mediated by the cag island in vitro. Assessment of apoptosis in vitro identified a group of H. pylori isolates that induce more severe gastric inflammation and atrophy.