Ceu Figueiredo

Clinical relevance of the cagA, vacA, and iceA status of Helicobacter pylori.

BACKGROUND & AIMS Clinical outcome of Helicobacter pylori infection may be associated with specific virulence-associated bacterial genotypes. The aim of this study was to assess the relationships between H. pylori cagA, vacA, and iceA status and severity of disease. METHODS Gastric biopsy specimens from 94 patients in The Netherlands were analyzed by polymerase chain reaction and reverse hybridization. RESULTS cagA was present in 63 (67%) of 94 cases and was associated with peptic ulcer disease (P = 0.0019). vacA geno-types s1a/m1, s1b/m2, s1b/m1, s1b/m2, and s2/m2 were found in 36.2%, 23.4%, 2.1%, 5.3%, and 20.2%, respectively. Ten isolates (10.6%) contained multiple vacA genotypes. The presence of peptic ulcers was associated with type s1 strains (P = 0.0006) but not with the m type (P = 0.2035). cagA and vacA s1 were strongly associated (P < 10(-5)). iceA1 was found in 53 (56.4%) and iceA2 in 25 (26.6%) of the 94 cases. In 14 isolates (14.9%), both iceA alleles were found, and 2 (2.1%) were negative for both iceA1 and iceA2. iceA1 was also associated with peptic ulcer disease (P = 0.0042). The iceA allelic type was independent of the cagA and vacA status. CONCLUSIONS vacA s1, cagA, and iceA1 are markers of H. pylori strains that are more likely to lead to ulcer disease.

A proinflammatory genetic profile increases the risk for chronic atrophic gastritis and gastric carcinoma

BACKGROUND & AIMS Pro-inflammatory polymorphisms within the genes interleukin (IL)-1B and IL-1RN are associated with risk for gastric carcinoma (GC) in Helicobacter pylori-infected individuals. We aimed to determine the association between variation of the tumor necrosis factor (TNF)-alpha gene and the risk for chronic atrophic gastritis (CAG) and GC. We also investigated the extent to which the combined effect of proinflammatory genetic polymorphisms (IL-1B, IL-1RN, and TNF-alpha), and the combined effect of TNF-alpha and bacterial genotypes each influence such a risk. METHODS In a case-control study including 306 controls, 221 individuals with chronic gastritis, and 287 GC patients, the TNF-alpha-308 and IL-1B-511 bi-allelic polymorphisms, the IL-1RN variable number of tandem repeats (VNTR), and the H. pylori genes vacA (s and m regions) and cagA were genotyped. RESULTS We found that carriers of the TNF-alpha-308*A allele are at increased risk for GC development with an odds ratio (OR) of 1.9 (95% confidence interval [CI], 1.3-2.7). For both CAG and GC, the odds of developing disease increased with the number of high-risk genotypes. Individuals carrying high-risk genotypes at the 3 loci are at increased risk for CAG and GC with an OR of 5.8 (95% CI, 1.1-31.0) and 9.7 (95% CI, 2.6-36.0), respectively. The risk for GC was not affected significantly by the combination of bacterial and TNF-alpha-308 genotypes. CONCLUSIONS These findings show that a proinflammatory polymorphism in the TNF-alpha gene is associated with increased risk for GC, and that it is possible to define a specific genetic profile associated with highest risk for CAG and GC.

Geographic Distribution of vacA Allelic Types of Helicobacter pylori

BACKGROUND & AIMS Distinct allelic types of Helicobacter pylori vacA have been defined. The geographic distribution of vacA alleles and cagA was assessed in this study. METHODS A total of 735 cultures from patients in 24 countries were analyzed by polymerase chain reaction and reverse hybridization on a line probe assay (LiPA). RESULTS In 124 (16.9%) of the 735 cultures, multiple vacA genotypes were detected, permitting analysis of 611 strains. In Europe, a distribution gradient of s1 subtypes was observed. In northern and eastern Europe, 89% were subtype s1a. s1a and s1b were equally present in France and Italy, whereas in Spain and Portugal 89% of strains were subtype s1b. s1a and s1b were approximately equally prevalent in North America. In Central and South America, virtually all s1 strains were subtype s1b. Subtype s1c was observed in 77% of the s1 isolates from East Asia. m1 and m2a have equal presence, except on the Iberian peninsula and in Central and South America, where m1 (86.2%) is more prevalent than m2 (13.8%). Subtype m2b was found exclusively among East Asian s1c strains. In all parts of the world, vacA s1/cagA-positive genotypes were associated with peptic ulcer disease (P < 0.001). CONCLUSIONS These data indicate a geographic distribution of H. pylori genotypes and aid in understanding the relationship of H. pylori with disease.

Helicobacter pylori genotypes may determine gastric histopathology.

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

Helicobacter pylori Genotypes Are Associated with Clinical Outcome in Portuguese Patients and Show a High Prevalence of Infections with Multiple Strains

BACKGROUND Clinical outcome of Helicobacter pylori infection is associated with virulence-associated bacterial genotypes. This study assessed the relationships between vacA, cagA and iceA genotypes and gastric diseases in Portuguese patients. METHODS A total of 319 patients were endoscoped and gastric biopsy specimens were studied by PCR and reverse hybridization (LiPA). RESULTS vacA genotypes s1/m1, s1/m2 and s2/m2 were observed in 53%, 14.5% and 32.5% of the cases, respectively. The majority (93.4%) of the s1 cases were s1b and 6.6% were s1a. Multiple vacA genotypes were found in 37.3% of the cases. Gastric ulcer and gastric carcinoma were associated with the presence of vacA s1 (P = 0.008 and P < 0.001, respectively) and vacA m1 genotypes (P = 0.007 and P < 0.001, respectively). Duodenal ulcers were associated with vacA s1 (P < 0.001) but not with the vacA m genotype (P = 0.221). cagA was present in 71.2% of the cases and was associated with duodenal ulcer (P < 0.001), gastric ulcer (P = 0.009) and gastric carcinoma (P < 0.001). iceA1 was found in 27.3% and iceA2 in 32.3% of the cases. In 36.7% of the isolates both iceA alleles were found, and 3.8% were negative for iceA. The iceA genotype was not associated with clinical outcome. CONCLUSIONS vacA s1 and cagA+ H. pylori strains are associated with duodenal ulcer, gastric ulcer or gastric carcinoma. vacA m1 is associated with gastric ulcer or carcinoma but not with duodenal ulcer. Infection with multiple H. pylori strains is remarkably high in Portugal and is more frequent in duodenal ulcer patients.Background: Clinical outcome of Helicobacter pylori infection is associated with virulence-associated bacterial genotypes. This study assessed the relationships between vacA, cagA and iceA genotypes and gastric diseases in Portuguese patients. Methods: A total of 319 patients were endoscoped and gastric biopsy specimens were studied by PCR and reverse hybridization (LiPATM). Results:vacA genotypes s1/ m1, s1/m2 and s2/m2 were observed in 53%, 14.5% and 32.5% of the cases, respectively. The majority (93.4%) of the s1 cases were s1b and 6.6% were s1a. Multiple vacA genotypes were found in 37.3% of the cases. Gastric ulcer and gastric carcinoma were associated with the presence of vacA s1 (P = 0.008 and P < 0.001, respectively) and vacA m1 genotypes (P = 0.007 and P < 0.001, respectively). Duodenal ulcers were associated with vacA s1 (P < 0.001) but not with the vacA m genotype (P = 0.221). cagA was present in 71.2% of the cases and was associated with duodenal ulcer (P < 0.001), gastric ulcer (P = 0.009) and gastric carcinoma (P < 0.001). iceA1 was found in 27.3% and iceA2 in 32.3% of the cases. In 36.7% of the isolates both iceA alleles were found, and 3.8% were negative for iceA. The iceA genotype was not associated with clinical outcome. Conclusions:vacA s1 and cagA + H. pylori strains are associated with duodenal ulcer, gastric ulcer or gastric carcinoma. vacA m1 is associated with gastric ulcer or carcinoma but not with duodenal ulcer. Infection with multiple H. pylori strains is remarkably high in Portugal and is more frequent in duodenal ulcer patients.

Epithelial E- and P-cadherins: Role and clinical significance in cancer

E-cadherin and P-cadherin are major contributors to cell-cell adhesion in epithelial tissues, playing pivotal roles in important morphogenetic and differentiation processes during development, and in maintaining integrity and homeostasis in adult tissues. It is now generally accepted that alterations in these two molecules are observed during tumour progression of most carcinomas. Genetic or epigenetic alterations in E- and P-cadherin-encoding genes (CDH1 and CDH3, respectively), or alterations in their proteins expression, often result in tissue disorder, cellular de-differentiation, increased invasiveness of tumour cells and ultimately in metastasis. In this review, we will discuss the major properties of E- and P-cadherin molecules, its regulation in normal tissue, and their alterations and role in cancer, with a specific focus on gastric and breast cancer models.

Helicobacter pylori Infection Induces Genetic Instability of Nuclear and Mitochondrial DNA in Gastric Cells

Purpose:Helicobacter pylori is a major cause of gastric carcinoma. To investigate a possible link between bacterial infection and genetic instability of the host genome, we examined the effect of H. pylori infection on known cellular repair pathways in vitro and in vivo. Moreover, various types of genetic instabilities in the nuclear and mitochondrial DNA (mtDNA) were examined. Experimental Design: We observed the effects of H. pylori infection on a gastric cell line (AGS), on C57BL/6 mice, and on individuals with chronic gastritis. In AGS cells, the effect of H. pylori infection on base excision repair and mismatch repair (MMR) was analyzed by reverse transcription-PCR, Western blot, and activity assays. In mice, MMR expression was analyzed by reverse transcription-PCR and the CA repeat instabilities were examined by Mutation Detection Enhancement gel electrophoresis. Mutation spectra in AGS cells and chronic gastritis tissue were determined by PCR, single-stranded conformation polymorphism, and sequencing. H. pylori vacA and cagA genotyping was determined by multiplex PCR and reverse hybridization. Results: Following H. pylori infection, the activity and expression of base excision repair and MMR are down-regulated both in vitro and in vivo. Moreover, H. pylori induces genomic instability in nuclear CA repeats in mice and in mtDNA of AGS cells and chronic gastritis tissue, and this effect in mtDNA is associated with bacterial virulence. Conclusions: Our results suggest that H. pylori impairs central DNA repair mechanisms, inducing a transient mutator phenotype, rendering gastric epithelial cells vulnerable to the accumulation of genetic instability and thus contributing to gastric carcinogenesis in infected individuals.

Helicobacter pylori induces gastric epithelial cell invasion in a c-Met and type IV secretion system-dependent manner

Helicobacter pylori interacts with gastric epithelial cells, activating signaling pathways important for carcinogenesis. In this study we examined the role of H. pylori on cell invasion and the molecular mechanisms underlying this process. The relevance of H. pylori cag pathogenicity island-encoded type IV secretion system (T4SS), CagA, and VacA for cell invasion was also investigated. We found that H. pylori induces AGS cell invasion in collagen type I and in Matrigel invasion assays. H. pylori-induced cell invasion requires the direct contact between bacteria and cancer cells. H. pylori-mediated cell invasion was dependent on the activation of the c-Met receptor and on increased MMP-2 and MMP-9 activity. The abrogation of the c-Met receptor using the specific NK4 inhibitor or the silencing of c-Met expression with small interference RNA suppressed both cell invasion and MMP activity. Studies with different H. pylori strains revealed that cell invasion, c-Met tyrosine phosphorylation, and increased MMP-2 and MMP-9 activity were all dependent on the presence of a functional bacterial T4SS, but not on VacA cytotoxicity. Our findings demonstrate that H. pylori strains with a functional T4SS stimulate gastric epithelial cell invasion through a c-Met-dependent signaling pathway that comprises an increase in MMP-2 and MMP-9 activity.

Helicobacter pylori induces β3GnT5 in human gastric cell lines, modulating expression of the SabA ligand sialyl–Lewis x

Chronic Helicobacter pylori infection is recognized as a cause of gastric cancer. H. pylori adhesion to gastric cells is mediated by bacterial adhesins such as sialic acid-binding adhesin (SabA), which binds the carbohydrate structure sialyl-Lewis x. Sialyl-Lewis x expression in the gastric epithelium is induced during persistent H. pylori infection, suggesting that H. pylori modulates host cell glycosylation patterns for enhanced adhesion. Here, we evaluate changes in the glycosylation-related gene expression profile of a human gastric carcinoma cell line following H. pylori infection. We observed that H. pylori significantly altered expression of 168 of the 1,031 human genes tested by microarray, and the extent of these alterations was associated with the pathogenicity of the H. pylori strain. A highly pathogenic strain altered expression of several genes involved in glycan biosynthesis, in particular that encoding beta3 GlcNAc T5 (beta3GnT5), a GlcNAc transferase essential for the biosynthesis of Lewis antigens. beta3GnT5 induction was specific to infection with highly pathogenic strains of H. pylori carrying a cluster of genes known as the cag pathogenicity island, and was dependent on CagA and CagE. Further, beta3GnT5 overexpression in human gastric carcinoma cell lines led to increased sialyl-Lewis x expression and H. pylori adhesion. This study identifies what we believe to be a novel mechanism by which H. pylori modulates the biosynthesis of the SabA ligand in gastric cells, thereby strengthening the epithelial attachment necessary to achieve successful colonization.

Helicobacter pylori cagA and vacA Genotypes as Predictors of Progression of Gastric Preneoplastic Lesions: A Long-Term Follow-Up in a High-Risk Area in Spain

OBJECTIVES:There are no established predictive markers of progression of gastric preneoplastic lesions. The aim of this study was to analyze the relationship between Helicobacter pylori cagA and vacA genotypes and progression of gastric preneoplastic lesions.METHODS:This was a follow-up study that carried out in a province of Spain with a high risk of gastric cancer. A total of 312 patients who underwent upper endoscopy with gastric biopsy in 1988–1994 with diagnoses of normal mucosa, non-atrophic gastritis (NAG), non-metaplastic multifocal atrophic gastritis (MAG), and complete or incomplete intestinal metaplasia (IM), and who accepted to undergo a new biopsy during 2005–2007 or had an end point during follow-up, were included in this study. Detection and characterization of H. pylori cagA and vacA genotypes was performed directly in baseline paraffin-embedded gastric biopsy specimens by PCR followed by reverse hybridization onto a line probe assay. Inter- and intra-observer variability of histological diagnosis was assessed. Analysis was done using unconditional logistic regression.RESULTS:The mean age of patients was 48.5 years (45% males) and the mean of follow-up was 12.8 years. H. pylori strains harboring cagA, vacA s1, and vacA m1 genotypes were more frequently found in patients with more advanced gastric preneoplastic lesions. Infection with cagA-positive, vacA s1, and vacA m1 strains was associated with progression of gastric preneoplastic lesions (multivariate odds ratio (OR)=2.28, 95% confidence interval (CI) 1.13–4.58; OR=2.90, 95% CI 1.38–6.13; and OR=3.38, 95% CI 1.34–8.53, respectively). Infection with strains that are simultaneously cagA positive and vacA s1/m1 was associated with progression of gastric precancerous lesions with an OR of 4.80 (95% CI 1.71–13.5) in relation to those infected with cagA-negative/vacA s2/m2 strains.CONCLUSIONS:H. pylori genotyping may be useful for the identification of patients at high risk of progression of gastric preneoplastic lesions and who need more intensive surveillance.