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

Dysregulation of lncRNA in Helicobacter pylori-Infected Gastric Cancer Cells

Helicobacter pylori (H. pylori) infection is the most common cause of gastric cancer (GC). This microorganism is genetically diverse; GC is caused by several genetic deregulations in addition to environmental factors and bacterial virulence factors. lncRNAs (long noncoding RNAs) are significant biological macromolecules in GC, have specific functions in diseases, and could be therapeutic targets. Altered lncRNAs can lead to the abnormal expression of adjacent protein-coding genes, which may be important in cancer development. Their mechanisms have not been well understood, so we are going to investigate the risk of GC in a population with both high lncRNA and H. pylori infection.

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.

The autoimmune susceptibility gene, PTPN2, restricts expansion of a novel mouse adherent-invasive E. coli

Inflammatory bowel disease (IBD) pathogenesis involves significant contributions from genetic and environmental factors. Loss-of-function single-nucleotide polymorphisms (SNPs) in the protein tyrosine phosphatase non-receptor type 2 (PTPN2) gene increase IBD risk and are associated with altered microbiome population dynamics in IBD. Expansion of intestinal pathobionts, such as adherent-invasive E. coli (AIEC), is strongly implicated in IBD pathogenesis as AIEC increases pro-inflammatory cytokine production and alters tight junction protein regulation - suggesting a potential mechanism of pathogen-induced barrier dysfunction and inflammation. We aimed to determine if PTPN2 deficiency alters intestinal microbiome composition to promote expansion of specific bacteria with pathogenic properties. In mice constitutively lacking Ptpn2, we identified increased abundance of a novel mouse AIEC (mAIEC) that showed similar adherence and invasion of intestinal epithelial cells, but greater survival in macrophages, to the IBD-associated AIEC, LF82. Furthermore, mAIEC caused disease when administered to mice lacking segmented-filamentous bacteria (SFB), and in germ-free mice but only when reconstituted with a microbiome, thus supporting its classification as a pathobiont, not a pathogen. Moreover, mAIEC infection increased the severity of, and prevented recovery from, induced colitis. Although mAIEC genome sequence analysis showed >90% similarity to LF82, mAIEC contained putative virulence genes with >50% difference in gene/protein identities from LF82 indicating potentially distinct genetic features of mAIEC. We show for the first time that an IBD susceptibility gene, PTPN2, modulates the gut microbiome to protect against a novel pathobiont. This study generates new insights into gene-environment-microbiome interactions in IBD and identifies a new model to study AIEC-host interactions.

Helicobacter pylori cagE, cagG, and cagM can be a prognostic marker for intestinal and diffuse gastric cancer

It is known that Helicobacter pylori is the main cause of peptic ulceration and gastric cancer. However, there is a lack of information on whether H. pylori strains may differ in gastric cancer histological subtypes. This study aimed to investigate different H. pylori strains considering six cag Pathogenicity Island - cagPAI genes (cagA, cagE, cagG, cagM, cagT, and virb11), and vacuolating cytotoxin - vacA alleles, and their relation to gastric cancer histologic subtypes. For this purpose, tumor samples from 285 patients with gastric carcinoma were used. H. pylori infection and genotypes were determined by polymerase chain reaction (PCR). H. pylori was detected in 93.9% of gastric tumors. For comparative analyzes between histopathological subtypes considering H. pylori cagPAI genes the strains were grouped according to the vacA s1/s2 alleles. In the vacAs1 group, the strains cagA(-)cagE(+), cagA(+)cagE(+)cagG(+), cagA(+)cagM(+), or only cagE(+) strains were more frequent in the intestinal subtype (P = .009; P = .024; P = .046, respectively). In contrast, cagM(+)cagG(+)cagA(-) and cagE(-) were associated with diffuse tumors (P = .036), highlighting the presence of cagE in the development of intestinal tumors, and the presence of cagG and absence of cagE in diffuse tumors. Furthermore, WEKA software and Decision Tree (CART) analyses confirmed these findings, in which cagE presence was associated with intestinal tumors, and cagE absence and cagG(+) with diffuse tumors. In conclusion our results showed that vacAs1 (cagG + cagM) strains, mainly cagG positive with cagE absence, were relevant in the studied population for the diffuse outcome, while the presence of cagE was relevant for the intestinal outcome. These findings suggest the relevance of these H. pylori genes as potential markers for gastric cancer histological outcomes.

Genetic variation in the cag pathogenicity island of Helicobacter pylori strains detected from gastroduodenal patients in Thailand

There is a lack of evidence of genetic variation in the Helicobacter pylori cag-PAI in Thailand, a region with the low incidence of gastric cancer. To clarify this issue, variation in the H. pylori cag-PAI in strains detected in Thailand was characterized and simultaneously compared with strains isolated from a high-risk population in Korea. The presence of ten gene clusters within cag-PAI (cagA, cagE, cagG, cagH, cagL, cagM, cagT, orf13, virB11, and orf10) and IS605 was characterized in H. pylori strains detected from these two countries. The cagA genotypes and EPIYA motifs were analyzed by DNA sequencing. The overall proportion of the ten cag-PAI genes that were detected ranged between 66 and 79%; additionally, approximately 48% of the strains from Thai patients contained an intact cag-PAI structure, while a significantly higher proportion (80%) of the strains from Korean patients had an intact cag-PAI. A significantly higher proportion of IS605 was detected in strains from Thai patients (55%). Analysis of cagA genotypes and EPIYA motifs revealed a higher frequency of Western-type cagA in Thai patients (87%) relative to Korean patients (8%) who were predominately associated with the East Asian-type cagA (92%). Variations in the Western-type cagA in the Thai population, such as EPIYA-BC patterns and EPIYA-like sequences (EPIYT), were mainly detected as compared with the Korean population (p < 0.05). In summary, H. pylori strains that colonize the Thai population tend to be associated with low virulence due to distinctive cag-PAI variation, which may partially explain the Asian paradox phenomenon in Thailand.

Expression levels of A disintegrin and metalloproteases (ADAMs), and Th17-related cytokines and their association with Helicobacter pylori infection in patients with gastroduodenal diseases

Expression levels of A disintegrin and metalloproteases (ADAMs) (10 and 17) and Th17-related cytokines [interleukin (IL) 17A, IL-17F, IL-33, IL-23, IL-23R] were investigated by quantitative real time polymerase chain reaction in gastric biopsies of patients with different gastroduodenal pathologies in the presence and absence of Helicobacter pylori infection. Patients with gastric cancer (GC) (n = 70, intestinal-type 38 and diffuse type 32), peptic ulcer disease [n = 50, duodenal ulcer (DU) 16 and gastric ulcer (GU) 34] and functional dyspepsia (n = 120) were included in the study. Further, the expression levels of ADAMs and Th17 cytokines were correlated with H. pylori cytotoxin-associated genes pathogenicity island (cagPAI) status. Expression levels of ADAMs (10 and 17) and Th17-related cytokines (IL-17A, IL-23, IL-23R) were significantly higher in H. pylori-positive than in H. pylori-negative gastric biopsies. Significant increase in ADAM17 and Th17 cytokines (IL-17A and IL-23) expressions was observed in patients with GU and intestinal-type GC in the presence of H. pylori infection and in strains harbouring intact cagPAI. Expression levels of IL-17A, IL-23 and ADAM17 were strongly correlated with GU and intestinal-type GC and weakly with DU and diffuse-type GC in the presence of H. pylori infection. Higher expression levels of ADAM17 and Th17 cytokines (IL-17A and IL-23), and their strong correlation with GU and intestinal-type GC patients in the presence of H. pylori and its intact cagPAI status, suggest a possible role of strain specificity in the pathogenesis of these diseases.

Association of heterogenicity of Helicobacter pylori cag pathogenicity island with peptic ulcer diseases and gastric cancer

OBJECTIVE

To investigate the frequency and integrity of certain cag pathogenicity island genes (cagPAI) in Helicobacter pylori strains and their association with peptic ulcer disease (PUD) and gastric cancer.

MATERIAL AND METHODS

We enrolled 240 adult patients [120 with functional dyspepsia (FD), 50 with PUD and 70 with gastric cancer] undergoing upper gastrointestinal endoscopy. H. pylori infection was diagnosed when either culture or any two of the three tests (rapid urease test, histopathology and specific ureA PCR) were positive. DNA extracted from H. pylori isolates and positive gastric tissues were tested by PCR for the presence of different genes of cagPAI using specific primers.

RESULTS

A total of 122 (51%) patients were H. pylori positive. Frequencies of cagPAI genes cagA, cagE, cagT and cagM in H. pylori strains from different groups of patients were as follows: functional dyspepsia 73, 83, 76 and 60%, PUD 70, 94, 91, 70% and gastric cancer 75, 95, 90 and 70%, respectively. Risk associated for the presence of PUD and gastric cancer with cagPAI genes cagE, cagT and cagM was 5.0-, 4.6- and 4.1- and 3.0-, 2.8- and 2.5-folds, respectively. Prevalence of intact cagPAI was significantly higher in PUD and gastric cancer compared to functional dyspepsia (PUD vs. functional dyspepsia, 71% vs. 38%, P = 0.01; gastric cancer vs. functional dyspepsia, 75% vs. 38%, P < 0.01). Intact cagPAI was associated with increased risk for the presence of PUD (odds ratio 5.2, 95% CI 2.4-11.3) and for the presence of gastric cancer (odds ratio 4.5, 95% CI 2.3-7.1).

CONCLUSIONS

cagPAI integrity and its different genes are linked to different forms of gastric disease and so may have a role in pathogenesis, diagnosis and management.

Comparative Genomics Revealed Multiple Helicobacter pylori Genes Associated with Biofilm Formation In Vitro

Background

Biofilm formation by Helicobacter pylori may be one of the factors influencing eradication outcome. However, genetic differences between good and poor biofilm forming strains have not been studied.

Materials and Methods

Biofilm yield of 32 Helicobacter pylori strains (standard strain and 31 clinical strains) were determined by crystal-violet assay and grouped into poor, moderate and good biofilm forming groups. Whole genome sequencing of these 32 clinical strains was performed on the Illumina MiSeq platform. Annotation and comparison of the differences between the genomic sequences were carried out using RAST (Rapid Annotation using Subsystem Technology) and SEED viewer. Genes identified were confirmed using PCR.

Results

Genes identified to be associated with biofilm formation in H. pylori includes alpha (1,3)-fucosyltransferase, flagellar protein, 3 hypothetical proteins, outer membrane protein and a cag pathogenicity island protein. These genes play a role in bacterial motility, lipopolysaccharide (LPS) synthesis, Lewis antigen synthesis, adhesion and/or the type-IV secretion system (T4SS). Deletion of cagA and cagPAI confirmed that CagA and T4SS were involved in H. pylori biofilm formation.

Conclusions

Results from this study suggest that biofilm formation in H. pylori might be genetically determined and might be influenced by multiple genes. Good, moderate and poor biofilm forming strain might differ during the initiation of biofilm formation.

Analysis of clinical isolates of Helicobacter pylori in Pakistan reveals high degrees of pathogenicity and high frequencies of antibiotic resistance

BACKGROUND

Antibiotic resistance in Helicobacter pylori contributes to failure in eradicating the infection and is most often due to point and missense mutations in a few key genes.

METHODS

The antibiotic susceptibility profiles of H. pylori isolates from 46 Pakistani patients were determined by Etest. Resistance and pathogenicity genes were amplified, and sequences were analyzed to determine the presence of mutations.

RESULTS

A high percentage of isolates (73.9%) were resistant to metronidazole (MTZ), with considerable resistance to clarithromycin (CLR; 47.8%) and amoxicillin (AML; 54.3%) also observed. Relatively few isolates were resistant to tetracycline (TET; 4.3%) or to ciprofloxacin (CIP; 13%). However, most isolates (n = 43) exhibited resistance to one or more antibiotics. MTZ-resistant isolates contained missense mutations in oxygen-independent NADPH nitroreductase (RdxA; 8 mutations found) and NADH flavin oxidoreductase (FrxA; 4 mutations found). In the 23S rRNA gene, responsible for CLR resistance, a new point mutation (A2181G) and 4 previously reported mutations were identified. Pathogenicity genes cagA, dupA, and vacA s1a/m1 were detected frequently in isolates which were also found to be resistant to MTZ, CLR, and AML. A high percentage of CagA and VacA seropositivity was also observed in these patients. Phylogenetic analysis of partial sequences showed uniform distribution of the 3' region of cagA throughout the tree.

CONCLUSIONS

We have identified H. pylori isolates in Pakistan which harbor pathogenicity genes and worrying antibiotic resistance profiles as a result of having acquired multiple point and missense mutations. H. pylori eradication regimens should therefore be reevaluated in this setting.

An Update on Helicobacter pylori as the Cause of Gastric Cancer

BACKGROUND

Gastric cancer is the second most common cause of cancer deaths worldwide. The vast majority of gastric cancers are inflammation-related cancers caused by infection with Helicobacter pylori. H. pylori-induced oxidative stress damages DNA, resulting in genetic instability. In addition, H. pylori itself can cause DNA damage and epigenetic changes that trigger genetic instability and neoplastic transformation.

SUMMARY

H. pylori strain-specific components act in combination with host factors and environmental and dietary factors to greatly enhance the inflammatory response and thus the cancer risk. Variations in several key factors, such as the cag pathogenicity island and the VacA protein, can trigger a greater inflammatory response in host cells. Genetic polymorphisms in the host such as in the IL-1β gene, and chromosomes 9p21.3 and 10q23 also play a contributing role. Finally, diet is a major external factor that modulates the risk of gastric cancer.

KEY MESSAGE

The majority of gastric cancers are inflammation-related cancers caused by infection with H. pylori. Eradication of H. pylori is important for the prevention and treatment of gastric cancer.

PRACTICAL IMPLICATIONS

H. pylori eradication results in healing of gastritis and prevention of further H. pylori-induced genetic damage. Eradication of H. pylori prior to development of atrophic gastritis can prevent the development of gastric cancer. Japan has undertaken a nationwide program to identify and eliminate H. pylori, along with surveillance for those who underwent H. pylori eradication too late to eliminate cancer risk. Population-wide eradication of H. pylori will result in gastric cancer becoming a vanishingly rare disease.

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).

Clinical relevance of the cagA, tnpA and tnpB genes in Helicobacter pylori

Background

Numerous proteins have been proposed as virulence factors for the gram negative gastric bacterium Helicobacter pylori but only for a few this has unequivocally been demonstrated. The aim of the current study was to evaluate the association of the putative virulence factors tnpA and tnpB (no cagA) with H. pylori associated gastroduodenal diseases.

Methods

A PCR based assay was used to determine the presence of the tnpA and tnpB genes, as well as of cagA, in 360H. pylori strains isolated from H. pylori infected patients.

Results

Of 360H. pylori culture positive patients (196 men, 164 women; average age 42.1 years (range 17–73), 95 had gastritis, 92 had gastric ulcers, 108 had duodenal ulcers, and 65 had gastric cancer. Using the gastritis group as a reference a significantly aberrant gene distribution was observed for the tnpA (Relative risk: 1.45; 95% CI 1.04-1.93), the cagA (Relative risk: 1.81; 95% CI 1.44-2.29), but not the tnpB gene in the gastric cancer group.

Conclusions

The increased incidence of the tnpA gene in gastric cancer patients suggests a role of the tnpA gene in the development of H. pylori induced gastric cancer.

A possible role of IL-1RN gene polymorphism in the outcome of gastrointestinal diseases associated with H. pylori infection

Objective

To verify whether the variable number of tandem repeat (VNTR) polymorphism in the IL-1RN gene that encodes the interleukin (IL)-1 receptor antagonist (IL-1Ra) plays a role in the outcome of gastrointestinal diseases associated with Helicobacter pylori (H. pylori) infection.

Methods

Patients with normal endoscopy (n = 71), inflammation of the upper gastrointestinal tract only (n = 196), gastric ulcer (n = 28), duodenal ulcer (n = 76), and gastric cancer (n = 19) were studied. H. pylori infection was diagnosed by the urease test, histological examination, and polymerase chain reaction. The IL-1 receptor antagonist gene (IL-1RN intron 2 VNTR) was analyzed by polymerase chain reaction. Gastritis was scored according to the updated Sydney system of classification.

Results

H. pylori infection was an independent risk factor for mild (odds ratio [OR] = 5.53 [95% confidence interval [CI] = 2.63–11.64; P < 0.05]), moderate (OR = 83.93 [95% CI = 29.7–237.18; P < 0.05]) and marked (OR = 47.47 [95% CI = 5.39–418.05; P < 0.05]) gastritis. The carriage of IL-1RN*2/*2 had a significant protective effect of H. pylori infection (OR = 0.31 [95% CI = 0.17–0.57; P < 0.05]). H. pylori infection was identified as an independent risk of inflammation, duodenal ulcer, and gastric ulcer. The carriage of IL-1RN*2/*2 was an independent risk factor for gastric cancer (OR = 5.81 [95% CI = 1.06–31.98; P < 0.05]); nonetheless, the carriage of allele 2 (IL-1RN*2/*2 plus IL-1RN*L/*2) had an independent protective effect on duodenal ulcer (OR = 0.45 [95% CI = 0.22–0.91; P < 0.05]).

Conclusions

Allele 2 of the VNTR IL-1RN polymorphism had a protective effect against duodenal ulcer and H. pylori infection; however, it increased the risk of gastric cancer.

Quadruple therapy for eradication of Helicobacter pylori

AIM: To investigate quadruple therapy with rabeprazole, amoxicillin, levofloxacin and furazolidone for the eradication of Helicobacter pylori (H. pylori) infection.

METHODS: A total of 147 patients were divided into the experimental treatment group (n = 78) and the standard triple treatment group (n = 69). The experimental treatment group received rabeprazole 20 mg, amoxicillin 1.0 g, levofloxacin 0.2 g and furazolidone 0.1 g, twice daily. The standard triple treatment group received omeprazole 20 mg, amoxicillin 1.0 g and clarithromycin 0.5 g, twice daily.

RESULTS: One month after treatment, the ¹³C urea breath test was carried out to detect H. pylori. The eradication rate using per-protocol analysis was 94.3% in the experimental treatment group and 73% in the standard triple treatment group (P < 0.05), and using intention to test analysis, these figures were 86% and 67% in the two groups, respectively. Side effects were observed in 34 patients, and included mild dizziness, nausea, diarrhea and increased bowel movement. Eleven of the 34 patients needed no treatment for their side effects.

CONCLUSION: Rabeprazole, amoxicillin, levofloxacin and furazolidone quadruple therapy is a safe method for the eradication of H. pylori with high efficacy and good tolerability.

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.

The utility of serologic tests as biomarkers for Helicobacter pylori-associated precancerous lesions and gastric cancer varies between Latin American countries

PURPOSE

Currently, studies on serologic diagnosis of Helicobacter pylori-associated gastric cancer (GC) in Latin America are scarce. The aim of the present study was to evaluate the association between H. pylori serology tests in patients with early precancerous lesions or GC, when compared with non-atrophic gastritis in Colombia, Paraguay, and Mexico, three countries in Latin America with a high prevalence of H. pylori infection but contrasting rates of GC mortality.

METHODS

Gastric biopsies and blood samples were obtained from patients attending the gastroenterology or oncology services of hospitals in the three participating countries. IgG antibodies against H. pylori whole-cell antigens and CagA were tested in 1,117 sera using an enzyme-linked immunoabsorbent assay.

RESULTS

Positive and significant associations were shown for H. pylori seropositivity and preneoplastic lesions in Mexico (OR 2.0; 95 % CI 1.1-3.4) but not in Colombia (OR 1.2; 95 % CI 0.6-2.1) or Paraguay (OR 1.5; 95 % CI 0.6-3.2); no significant associations were shown for GC in any country. CagA seropositivity was associated with preneoplasic lesions in all three countries (ORs = 2.1, 3.0, and 3.1 for Mexico, Colombia, and Paraguay, respectively), and with GC only in Colombia (OR 4.3; 95 % CI 2.1-9.2).

CONCLUSIONS

In countries of Latin America, the IgG CagA test might be a useful biomarker for patients with gastric preneoplastic lesions and for those at risk of developing gastric cancer.

Molecular analysis of Helicobacter pylori virulent-associated genes in hepatobiliary patients

OBJECTIVES

The Helicobacter pylori virulence-associated genes in hepatobiliary patients, including vacA, iceA, babA2, cagA and cagE, have not been reported. The aim of this study was to investigate these genes and the association of those and the clinical outcomes in hepatobiliary diseases.

METHODS

Eighty H. pylori-PCR-positive cases were obtained from hepatobiliary patients, representing both cholangiocarcinoma (CCA) (n= 58) and cholelithiasis (n= 22). The diversity of virulence genes was examined by polymerase chain reaction and DNA sequencing. Phylogenetic analysis of cagA was determined using the maximum parsimony method.

RESULTS

The vacAs1a + c/m1, iceA1 and babA2 genes were the most predominant genotypes in both CCA and cholelithiasis patients. The cagA and cagE genes were found significantly more frequently in patients with CCA than those with cholelithiasis (P < 0.05). The cagA positive samples were the Western-type cagA and showed that almost all of the detected sequences in Thai hepatobiliary and Thai gastric cancer patients were classified in the same cluster but separated from the cluster of Japan and other countries.

CONCLUSIONS

The cagA and cagE genes may be associated in the pathogenesis of hepatobiliary diseases, especially of CCA. Besides the bacterial variation, other host factors may be involved in the pathogenesis of hepatobiliary cancer.

Helicobacter pylori infection is strongly associated with gastric and duodenal ulcers in a large prospective study

BACKGROUND & AIMS

Infection with Helicobacter pylori (H pylori) is a risk factor for peptic ulcer disease (PUD), but there are limited longitudinal data on the associations between infection and incident gastric or duodenal ulcers.

METHODS

Information on potential risk factors, lifetime history of PUD, and serologic measurements of H pylori infection were obtained from a German cohort of 9953 adults, 50 to 74 years old at baseline (2000-2002). The incidence of ulcers was determined by questionnaires sent to study participants and general practitioners 2 and 5 years later, and was validated by medical records.

RESULTS

A lifetime history of PUD was reported by 1030 participants, and during the follow-up period 48 had a first gastric and 22 had a first duodenal ulcer. Infection with H pylori strains that express cytotoxin-associated gene A (cagA) was significantly associated with a lifetime history of PUD (odds ratio, 1.75; 95% confidence interval [CI], 1.50-2.04). Based on longitudinal analyses with physician-validated end points, the adjusted hazard ratios for incident gastric and duodenal ulcer disease were 2.9 (95% CI, 1.5-5.5) and 18.4 (95% CI, 4.2-79.9), respectively, among patients infected with cagA-positive strains of H pylori.

CONCLUSIONS

In cross-sectional analysis, infection with cagA-positive strains of H pylori was associated with a 1.75-fold increased risk of peptic ulcer disease. Longitudinal analyses revealed an 18.4- and 2.9-fold increased risk for duodenal ulcer and gastric ulcer, respectively. The proportion of PUD that is attributable to H pylori infection might be larger than previously believed.

High prevalence of duodenal ulcer in a tertiary care hospital in the city of São Paulo, SP, Brazil

CONTEXT: In spite of Helicobacter pylori infection being the etiological cause of peptic ulcer and its high prevalence in Brazil, the prevalence of peptic ulcer disease has been poorly studied. OBJECTIVES: To verify the peptic ulcer disease prevalence in patients of a tertiary care hospital. METHODS: Diagnostic findings from 1,478 consecutive endoscopies were correlated with the urease test results for H. pylori infection diagnosis and demographic data in a total of 3,779 endoscopies performed in 2005. The mean age of the patients was 51.14 ± 16.46, being 613 (41.5%) men. RESULTS: Peptic ulcer was diagnosed in 494 (33.4%) patients with a mean age of 54.86 ± 14.53, 205 (52%) were men, being 391 (26.5%) duodenal ulcer and 103 (7%) gastric ulcer. Normal endoscopy was found in 272 (18.4%) patients with a mean age of 38.4 ± 15.22, being 49 (18%) men. The comparison of peptic ulcer group with the patients that had normal endoscopy revealed that H. pylori infection [P = 0.005; OR = 1.70; 95% CI = 1.17-2.47][ign], male gender [P<0.0001; OR = 5.53; 95%CI = 3.67-8.34][ign] and older age [P<0.0001; OR = 1.08; 95%CI = 1.06-1.09] increased the risk of peptic ulcers. The overall H. pylori prevalence was 53% (786). CONCLUSIONS: Prevalence of duodenal ulcer is high in a Brazilian population that had H. pylori infection associated with older age and male gender as important determinants to gastrointestinal diseases outcome. Future prospective studies should confirm these 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.

Validation of a rapid stool antigen test for diagnosis of Helicobacter pylori infection

The aim of this study was to validate the rapid lateral flow Helicobacter pylori stool antigen test (One step H. pylori antigen test, ACON laboratories, San Diego, USA; Prime diagnostics, São Paulo), using 13C-Urea Breath Test as the gold standard for H. pylori infection diagnosis. A total of 98 consecutive patients, asymptomatic or dyspeptic, entered the study. Sixty-nine were women, with a mean age of 45.76 ± 14.59 years (14 to 79 years). In the H. pylori-positive group, the rapid stool antigen test detected H. pylori antigen in 44 of the 50 positive patients (sensitivity 88%; 95% CI: 75.7-95.5%), and six false-negative; and in the H. pylori-negative group 42 presented negative results (specificity 87.5%; 95% CI: 74.7-95.3%), and six false-positive, showing a substantial agreement (Kappa Index = 0.75; p < 0.0001; 95% CI: 0.6-0.9). Forty four of fifty patients that had positive stool antigen were H. pylori-positive, the PPV of the stool antigen test was 88% (95% CI: 75.7-95.5%), and 42 patients with negative stool antigen test were H. pylori-negative, the NPV of the stool antigen test was 87.5% (95% CI: 74.7-95.3%). We conclude that the lateral flow stool antigen test can be used as an alternative to breath test for H. pylori infection diagnosis especially in developing countries.

Molecular characterization and susceptibility testing of Helicobacter pylori strains isolated in western Argentina

OBJECTIVE

To characterize Helicobacter pylori isolates from western Argentina using virulence markers and antimicrobial susceptibility patterns in order to assess the association between virulent genotypes, antimicrobial resistance, and disease. DNA fingerprinting was also evaluated for the segregation of virulent or resistant strain clusters.

METHODS

Genotyping of 299 H. pylori isolates was performed by PCR using specific primers for the cagA, vacA and iceA genes. Random amplification of polymorphic DNA (RAPD)-PCR and rep-PCR genetic clustering were assessed using five random primers and BOXA1R and ERIC primers, respectively. Resistance to clarithromycin (Cla) and metronidazole (Mtz) was assessed by the agar dilution method.

RESULTS

It was observed that 40.8% of the genotypes were cagA-positive; 66.9% were vacA s1m1 genotype and the iceA1 allele was found in 40.8%. A significant correlation (p=0.0000) was observed between cagA positivity and vacA s1m1/iceA1 genotypes. Triple virulent genotypes were statistically associated with peptic ulcer (PU) (p=0.0001) and Cla resistance (p=0.0000). RAPD fingerprints obtained with AO2 primers identified clusters that were strongly associated with PU, virulence markers, and resistance to Cla and Mtz.

CONCLUSIONS

The H. pylori isolates that harbored two or three virulence markers were more resistant to Cla and Mtz. Combined analysis of virulent genotypes and resistance patterns may permit identification of high-risk patients to prevent PU later in life or to avoid antimicrobial treatment failure.

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.

Helicobacter pylori reinfection in Brazilian patients with peptic ulcer disease: a 5-year follow-up

BACKGROUND

The Helicobacter pylori reinfection seems to be higher in developing countries, than in developed ones. The aim of the study was to determine the annual recurrence rate of H. pylori, in Brazilian patients with peptic ulcer disease, in a 5-year follow-up.

METHODS

Patients, with peptic ulcer disease diagnosed by upper digestive endoscopy (UDE) and H. pylori infection verified by histological analysis, rapid urease test, polymerase chain reaction, and urea breath test (UBT), were treated for bacterial eradication. The cure of the infection was verified using the same tests, 3 months after. Clinical evaluation and UBT were performed after sixth and ninth month. After 1 year of follow-up, UBT and UDE were repeated. Up to the fifth year, patients were assessed twice a year and an UBT was performed annually. The patients included and all the reinfected were tested for 15 different genes of the H. pylori.

RESULTS

One hundred and forty-seven patients were followed: 19 for 1 year, eight for 2 years, four for 3 years, five for 4 years, and 98 for 5 years, totaling 557 patients/years. Recurrence did not occur in the first year. In the second year, two patients were reinfected; in the third, four patients; in the fourth, three patients; and in the fifth, one patient. The total of reinfected patients was 10. The annual reinfection rate was 1.8%.

CONCLUSION

Brazil presents a low prevalence of H. pylori reinfection, similar to the developed countries.

Association of LEC and tnpA Helicobacter pylori genes with gastric cancer in a Brazilian population

Background

H. pylori seroprevalence in Brazilians varies and is dependent on socioeconomic status, sanitation conditions and ethnicity; furthermore, H. pylori is not always associated with the incidence of gastric cancer, suggesting the role of more virulent strains. The purpose of this study was to analyze the association of more virulent H. pylori strains with gastric cancer.

Methods

DNA was extracted from gastric biopsies of thirty-four cases of gastric cancer (11 intestinal-type, 23 diffuse-type), and thirty-four of patients with endoscopic gastritis. The presence of cagPAI genes (cagA, cagA promoter, cagE, cagM, tnpB, tnpA, cagT and the left end of the cagII (LEC)) and babA were analyzed by PCR.

Results

Comparison of H. pylori isolates from gastric cancer and gastritis patients showed significant associations of tnpA and LEC with gastric cancer (73.5% [OR, 6.66; 95% CI, 2.30-19.25] and 58.8% [OR, 10.71; 95% CI, 3.07-37.28] of cases, respectively). Other cagPAI genes were detected in both groups at similar frequencies.

Conclusions

tnpA and LEC of H. pylori cagPAI were associated with gastric cancer; nonetheless, these results were restricted within this group of patients and further studies are needed to confirm these results in a larger sample and determine their role in gastric carcinogenesis.

Determination of Helicobacter pylori virulence by analysis of the cag pathogenicity island isolated from Iranian patients

BACKGROUND

The cag pathogenicity island (PAI), which can be divided into two parts, cagI and cagII, is the most well-known virulence factor of Helicobacter pylori.

AIMS

We investigated the association between genetic variations within the cag PAI (cagA and cagE in the cagI and cagT in the cagII) and clinical outcomes in Iranian patients.

SUBJECTS

A total of 231 patients including 182 patients with gastritis, 41 with peptic ulcer and 8 with gastric cancer.

METHODS

The presence of the cagA, cagE and cagT genes were measured by polymerase chain reaction and the results were compared with clinical outcomes and gastric histology.

RESULTS

The cagA, cagE and cagT genes were found in 154 (66.7%), 90 (39.0%) and 70 (30.3%) of clinical isolates. At least 144 (62.3%) strains possessed partially deleted cag PAI (e.g., 69 [29.9%] strains were cagA-positive, but cagE and cagT-negative).

CONCLUSION

The single genes as well as the combination of genes in the cag PAI appeared not to be useful markers to predict H. pylori-related diseases in Iranian patients. The genomic sequences of the cag PAI in Iranian strains might be considerably different from those in other geographic locations.

Oral cavity is not a reservoir for Helicobacter pylori in infected patients with functional dyspepsia

INTRODUCTION

Helicobacter pylori infection is very prevalent in Brazil, infecting almost 65% of the population. The aim of this study was to evaluate the presence of this bacterium in the oral cavity of patients with functional dyspepsia (epigastric pain syndrome), establish the main sites of infection in the mouth, and assess the frequency of cagA and vacA genotypes of oral H. pylori.

METHODS

All 43 outpatients with epigastric pain syndrome, who entered the study, were submitted to upper gastrointestinal endoscopy to rule out organic diseases. Helicobacter pylori infection in the stomach was confirmed by a rapid urease test and urea breath tests. Samples of saliva, the tongue dorsum and supragingival dental plaque were collected from the oral cavity of each subject and subgingival dental plaque samples were collected from the patients with periodontitis; H. pylori infection was verified by polymerase chain reaction using primers that amplify the DNA sequence of a species-specific antigen present in all H. pylori strains; primers that amplify a region of urease gene, and primers for cagA and vacA (m1, m2, s1a, s1b, s2) genotyping.

RESULTS

Thirty patients harbored H. pylori in the stomach, but it was not possible to detect H. pylori in any oral samples using P1/P2 and Urease A/B. The genotype cagA was also negative in all samples and vacA genotype could not be characterized (s-m-).

CONCLUSION

The oral cavity may not be a reservoir for H. pylori in patients with epigastric pain syndrome, the bacterium being detected exclusively in the stomach.

Helicobacter pylori: phenotypes, genotypes and virulence genes

Helicobacter pylori is a Gram-negative, microaerophilic bacterium that colonizes the gastric mucus overlying the epithelium of the stomach in more than 50% of the world's population. This gastric colonization induces chronic gastric inflammation in all infected individuals, but only induces clinical diseases in 10-20% of infected individuals. These include peptic ulcers, acute and atrophic gastritis, intestinal metaplasia, gastric adenocarcinoma and gastric B-cell lymphoma. Various bacterial virulence factors are associated with the development of such gastric diseases, and the characterization of these markers could aid medical prognosis, which could be extremely important in predicting clinical outcomes. The purpose of this review is to summarize the role of the phenotypes, virulence-related genes and genotypes of H. pylori in the establishment of gastric colonization and the development of associated diseases.

Direct detection and analysis of vacA genotypes and cagA gene of Helicobacter pylori from gastric biopsies by a novel multiplex polymerase chain reaction assay

Several tests/methods for the infection, detection, and genotyping of Helicobacter pylori have been developed in the past; all these differ in specificity and sensitivity and thereby could not be routinely used in clinical study especially in resource-poor developing countries. In the present study, a novel method based on multiplex polymerase chain reaction (PCR) assay was developed to detect H. pylori in patients suffering from gastrointestinal diseases. This method does not require steps of sonication, boiling, or centrifugation for obtaining DNA from biopsy samples, which are otherwise prerequisite in detecting H. pylori by PCR assay. Two hundred seventy-six patients were examined, of which 182 cases (excluding 36 patients having multiple H. pylori strain infection and 8 showing amplification of 16S rDNA only) were H. pylori positive. The dominant vacA genotype was s1 and m1 being present in 168 (92.3%) and 106 (58.2%) patients, respectively, followed by m2 (41.7%), and the lowest being s2 (7.7%). Detection of H. pylori by this method seems rapid, simpler, and suitable for both types 1 and 2 bacteria. Furthermore, genotyping of vacA and cagA genes could also be routinely performed in a large number of patients for diagnostic purposes.

Involvement of the Helicobacter pylori plasticity region and cag pathogenicity island genes in the development of gastroduodenal diseases

Infection by Helicobacter pylori is associated with the development of several gastroduodenal diseases, including gastritis, peptic ulcer disease (gastric ulcers and duodenal ulcers), and gastric adenocarcinoma. Although a number of putative virulence factors have been reported for H. pylori, there are conflicting results regarding their association with specific H. pylori-related diseases. In this work, we investigated the presence of virB11 and cagT, located in the left half of the cag pathogenicity island (cagPAI), and the jhp917-jhp918 sequences, components of the dupA gene located in the plasticity zone of H. pylori, in Brazilian isolates of H. pylori. We also examined the association between these genes and H. pylori-related gastritis, peptic ulcer disease, and gastric and duodenal ulcers in an attempt to identify a gene marker for clinical outcomes related to infection by H. pylori. The cagT gene was associated with peptic ulcer disease and gastric ulcers, whereas the virB11 gene was detected in nearly all of the samples. The dupA gene was not associated with duodenal ulcers or any gastroduodenal disease here analyzed. These results suggest that cagT could be a useful prognostic marker for the development of peptic ulcer disease in the state of São Paulo, Brazil. They also indicate that cagT is associated with greater virulence and peptic ulceration, and that this gene is an essential component of the type IV secretion system of H. pylori.