H. pylori infection and genotyping in patients undergoing upper endoscopy at inner city hospitals

Racial Differences in Helicobacter pylori Prevalence in the US: A Systematic Review

BACKGROUND AND AIMS:

Helicobacter pylori remains an important risk factor for noncardia gastric cancer and a spectrum of disease from H. pylori infection to gastric cancer. As a step toward improved clinical strategies for gastric cancer prevention, we assessed racial differences in prevalence of H. pylori from studies across the United States. This systematic review provides a comprehensive evaluation of the literature regarding racial differences in H. pylori in the United States.

METHODS:

MEDLINE, Embase, and Web of Science database searches were performed through May 26, 2021. Ultimately, 25 studies that reported H. pylori infection prevalence by race were included.

RESULTS:

All studies included in the review documented higher H. pylori prevalence in Blacks and Hispanics than in whites. The ratio of H. pylori prevalence for Blacks compared to non-Hispanic whites ranged from 1.3 to 5.4, and the ratio for Hispanics compared to non-Hispanic whites ranged from 1.8 to 4.4. Of the 5 studies that examined H. pylori CagA prevalence by race, 4 found higher prevalence among Blacks and Hispanics compared to whites, with CagA prevalence ranging from 19% to 77% in whites, 62% to 90% in Blacks, and 64% to 74% in Hispanics.

CONCLUSION:

In this review, across 25 studies, varying in underlying population, time period, and geographic location, Blacks and Hispanics appeared to have a higher prevalence of H. pylori infection than whites. This increased prevalence of H. pylori among populations also at a higher risk of gastric cancer is relevant in the clinical setting for decision-making related to H. pylori testing and gastric cancer prevention.

Variations in the multimerization region of the Helicobacter pylori cytotoxin CagA affect virulence

Helicobacter pylori colonizes the human stomach by infecting gastric epithelial cells. It is the primary cause of peptic ulcer disease and gastric cancer (GC). Cytotoxin-associated gene A (CagA) is a virulence factor produced by H. pylori. Strains positive for the CagA protein are associated with more severe gastric diseases. The 3' region of the cagA gene exhibits heterogeneity with respect to tyrosine phosphorylation motifs (EPIYA) and CagA multimerization motifs (CM). CagA proteins are categorized as either Western or Eastern based on EPIYA sequences. CM motifs are also identified as Western and Eastern based on CM sequences identified in Western and East Asian countries. It has been suggested that CagA proteins possessing an Eastern CM type are associated with less severe gastric disorders. In the present study, the effects of two CagA peptides with different CM motifs on cell function were compared: CagA with a Western and Eastern CM motif (CagA-WE), and CagA with two Western CM motifs (CagA-WW). CagA sequences were fused with green fluorescent protein (GFP) to form GFP-CagA fusion proteins. GFP-CagA and GFP control constructs were transfected into human gastric adenocarcinoma cells (AGS). GFP-CagA expression was verified by immunoblotting and immunofluorescence. The results demonstrated that, following 18 h, the CagA-WE-transfected cells were less adherent compared with the CagA-WW transfected cells. CagA has also been reported to cause cell elongation in AGS cells. In the current study, cell elongation was more frequent in the CagA-WW-transfected cells compared with the CagA-WE transfected cells (8.34 vs. 3.97% cells, respectively). The CagA peptides did not affect proliferation or apoptosis rates. These results suggest that different CM motif types may affect CagA virulence.

Card15 mutations and gastric cancer in a Portuguese population

BACKGROUND. CARD15 is involved in the innate immune response and mutations of this gene have been linked with increased risk of Crohn's disease and colorectal cancer. The relation between CARD15 mutations and gastric cancer (GC) remains controversial. AIMS. To assess whether CARD15 mutations are risk factors for GC in Portugal and whether there are genotype-phenotype correlations in these patients. METHODS. The 3 main CARD15 mutations (3020insC, R702W and G908R) were searched in 150 patients with GC and in 202 healthy controls. RESULTS. Overall, CARD15 mutations were found in 28 patients (18.7%) and in 27 controls (13.4%) (p = 0.176). Individually, the incidence of 3020insC was significantly higher in patients than in controls (6.0% vs. 1.0%, p = 0.021). This polymorphism was linked with an increased risk for the intestinal-type of GC (p = 0.002), while no association was found with the diffuse and/or mixed types. Genotype frequencies for R702W (10.0% vs. 7.9%) and G908R (4.0% vs. 4.0%) were not statistically different between the two groups. Similarly, no significant associations were detected between these two polymorphisms and the different histological GC types. No correlations were observed between CARD15 mutations and family history, mean age at diagnosis or GC stage. CONCLUSIONS. The CARD15 3020insC variant is a risk factor for intestinal GC in Portugal. CARD15 variants are not correlated with age of diagnosis or family aggregation of the disease neither with the GC stage.

Analysis of the 3'-variable region of the cagA gene from Helicobacter pylori strains infecting patients at New York City hospitals

Helicobacter pylori infects the gastric mucosa in humans and is a causative agent for peptic ulcer disease (PUD) and gastric cancer (GC). CagA is produced by H. pylori and is associated with more severe outcomes. cagA genes vary at the 3'-region with respect to phosphorylation motifs (EPIYA-A, -B, -C, or -D) and CagA multimerization motifs (CM). This variability may be associated with the clinical outcomes. We examined the variable region of cagA genes expressed in H. pylori-infected patients treated at three NYC Hospitals. DNA was isolated from gastric biopsies of patients undergoing upper endoscopy. Most H. pylori-infected patients were Black or Hispanic. The cagA 3'-region of CagA-positive samples was amplified by PCR, purified and sequenced. The patterns of EPIYA and CM motifs were examined and related to clinical outcomes. We obtained 42 CagA sequences from our sample collection. The EPIYA phosphorylation motif pattern was ABC in 81.0% of our samples. Western (W) and Eastern (E) CM motifs have also been defined. CagA proteins lacking an Eastern CM motif and possessing one or two Western CM motifs were observed more frequently in patients with PUD and GC when compared with non-ulcer gastritis (50.0% vs 11.8%, respectively), suggesting that these CM motif patterns are more virulent than those containing at least one Eastern CM motif. We conclude that In H. pylori-infected patients treated at NYC Hospitals, CM motif patterns in the CagA 30-variable region may be more significant than EPIYA motif patterns with respect to clinical outcomes.

Diversity of VacA intermediate region among Helicobacter pylori strains from several regions of the world

Helicobacter pylori is known to be a major cause of gastric carcinoma and peptic ulceration. cagA positivity and vacA's signal regions and mid-regions are well-characterized markers of H. pylori's virulence. Recently, an intermediate region has been identified as another strong marker of H. pylori-associated disease, and its i1 allele has been linked with severe diseases in colonized hosts. The goal of this study was to determine the prevalence of the intermediate alleles in H. pylori isolates from China, Turkey, and Uruguay and from U.S. Africans and to compare their distribution with other well-characterized virulence factors. Originally, 123 H. pylori strains were studied, but 3 were excluded due to the failure to amplify the intermediate region in these samples. Therefore, a total of 120 strains were analyzed: 30 Chinese isolates, 35 Turkish isolates, 30 Uruguayan isolates, and 25 U.S. African isolates. The s type and the m type were determined by PCR amplification. The i type was identified by PCR amplification and DNA sequencing. CagA status was determined by PCR methodology. There was a strong correlation among CagA positivity, s1, and i1 in Chinese, U.S. African, and Uruguayan isolates, but less correlation among these markers in Turkish isolates. A new intermediate variant (i3) was identified in 25.7% of Turkish strains and 3.3% of the Chinese strains. In summary, the distribution of CagA positivity and s1 correlated with the i1 in the three populations, except in the Turkish population, which showed a disproportionate representation of the i3 allele. Phylogenetic mapping confirmed the i-typing method previously defined and adopted for this study. The phylogenetic tree showed country-specific correlation with the intermediate region. Our results showed that the i1 allele is strongly associated with CagA positivity and the vacA s1 allele, suggesting its role as a virulence marker and potential predictor for clinical outcome.

Positive association between Helicobacter pylori and gastroesophageal reflux disease in children

OBJECTIVES

The role of Helicobacter pylori (H pylori) in gastroesophageal reflux disease (GERD) remains controversial, particularly in children, because there are limited published data. Adult studies suggested that H pylori infection may protect against GERD by causing atrophic gastritis, which leads to reduced gastric acid secretion. The objective of our study was to determine the role of H pylori infection in the development of GERD in a pediatric population.

PATIENTS AND METHODS

A retrospective analysis of 420 patients (M:F = 214:206) who underwent esophagogastroduodenoscopy (EGD) with biopsies between January 2000 and April 2006 was conducted. Patient demographics, clinical indications for EGD and the prevalence of reflux esophagitis (RE), the biomarker for GERD, in 2 groups, H pylori positive and H pylori negative, were reviewed. The prevalence of RE in the H pylori-positive and H pylori-negative groups was further analyzed on the basis of sex and age (<1 year, 1-10 years, >10 years). The mean age of the study population was 8.2 years (range 0-20 years). The clinical indications for EGD were as follows: recurrent abdominal pain (n = 186, 44%), malabsorption (n = 80, 19%), persistent vomiting (n = 80, 19%), suspected eosinophilic gastrointestinal disorders (n = 63, 15%), and others such as upper gastrointestinal bleeding or inflammatory bowel disease surveillance (n = 11, 3%). Statistical analysis was performed by using chi test, Fisher exact test, and multivariate logistical regression analysis.

RESULTS

Among the 420 patients, 16 patients (3.8%) were positive for H pylori and 167 patients (39.8%) were found to have RE. Thirteen patients with H pylori were found to have histologic evidence of RE. The prevalence of RE in the H pylori-positive population was 81.3% compared with 38.1% in the H pylori-negative population (P < or = 0.05). There were no patients with H pylori in the youngest age group. In the second age group (1-10 years), 100% of the H pylori-positive patients had RE, whereas 44.6% of the H pylori-negative patients had RE (P < or = 0.05). Both male and female patients with H pylori had a higher prevalence of RE, 77.8% and 85.7%, respectively. On a multivariate logistical regression, for the overall study cohort, H pylori-positive patients had an odds ratio of 5.79 of developing RE compared with H pylori-negative patients (P < or = 0.05).

CONCLUSIONS

Our study results indicate that there is a significantly higher prevalence of RE in an H pylori-infected cohort independent of age or sex. The findings suggest that H pylori infection in children is positively associated with RE.

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

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

Seroprevalence of Helicobacter pylori in New York City populations originating in East Asia

Helicobacter pylori prevalence is higher in developing countries than in industrialized countries, and within the latter, higher among immigrants than among nativeborn residents. Using a point-prevalence survey, we sought to identify risk factors for H. pylori seropositivity in US urban East Asian-born populations. At a clinic in New York City, we consecutively enrolled 194 East Asian-born adults, who then responded to a survey and provided a blood sample. Assays were performed to detect IgG antibodies against whole cell (WC) and cytotoxin associated gene A (CagA) antigens of H. pylori. For this group (mean age 50.2+/-14.7 years), the mean period of residence in the United States was 11.9+/-7.7 years. The total H. pylori seroprevalence was 70.1%, with highest (81.4%) in Fujianese immigrants. Multiple logistic regression analysis indicated an independent association of H. pylori seropositivity with Fujianese origin [odds ratios (OR) =2.3, 95% confidence interval (95% CI) =1.05-5.0] and inverse associations with period in the United States (OR per year of residency in the United States =0.95, 95% CI =0.91-0.99) and with a history of dyspepsia (OR for a history of stomach pain =0.52, 95% CI =0.3-1.0). We conclude that H. pylori is highly prevalent among recent East Asian immigrants, especially among Fujianese. The protective effects of history of dyspepsia and duration in the United States suggest that these may be markers for antibiotic therapies.

Gastric cancer: new genetic developments

Gastric cancer's (GC) incidence shows large geographic differences worldwide with the lowest rates occurring in most Western industrialized countries including the United States and the United Kingdom; in contrast, relatively high rates of GC occur in Japan, Korea, China, and South America, particularly Chile. The Laurén classification system classifies GC under two major histopathological variants: 1) an intestinal type and 2) a diffuse type. The intestinal type is more common in the general population, more likely to be sporadic and related to environmental factors such as diet, particularly salted fish and meat as well as smoked foods, cigarette smoking, and alcohol use. It exhibits components of glandular, solid, or intestinal architecture, as well as tubular structures. On the other hand, the diffuse type is more likely to have a primary genetic etiology, a subset of which, known as hereditary diffuse gastric cancer (HDGC), is due to the E-cadherin (CDH1) germline mutation. The diffuse type pathology is characterized by poorly cohesive clusters of cells which infiltrate the gastric wall, leading to its widespread thickening and rigidity of the gastric wall, known as linitis plastica. Helicobacter pylori infection is associated with risk for both the intestinal and diffuse varieties of gastric cancer. Germline truncating mutations of the CDH1 gene, which codes for the E-cadherin protein, were initially identified in three Maori families from New Zealand that were predisposed to diffuse GC. Since then, similar mutations have been described in more than 40 additional HDGC families of diverse ethnic backgrounds. It is noteworthy that two-thirds of HDGC families reported to date have proved negative for the CDH1 germline mutation. A number of candidate genes have been identified through analysis of the molecular biology of E-cadherin. Patients with evidence of the CDH1 germline mutation in the context of a family history of HDGC must be considered as candidates for prophylactic gastrectomy, given the extreme difficulty in its early diagnosis and its exceedingly poor prognosis when there is regional or distant spread. Specifically, the E-cadherin cytoplasmic tail interacts with catenins, assembling the cell-adhesion complex involved with E-cadherin mediated cell:cell adhesion. Beta-catenin and gamma-catenin compete for the same binding site on the E-cadherin cytoplasmic tail, directly linking the adhesion complex to the cytoskeleton through alpha-catenin. Beta-catenin gene (CTNNB1) mutations have been described predominantly in intestinal-type gastric cancers and CTNNB1 gene amplification and overexpression have recently been described in a mixed-type gastric cancer. This paper reviews the genetics of both intestinal and diffuse types of gastric carcinoma, their differential diagnosis, molecular genetics, pathology, and, when known, their mode of genetic transmission within families.

Prevalence of Helicobacter pylori vacA and cagA genotypes in Ethiopian dyspeptic patients

A total of 300 gastric biopsy samples and 50 Helicobacter pylori isolates were collected from Ethiopian adult dyspeptic patients. The vacA and cagA genes were detected in 90 and 79% of biopsy specimens, respectively, and in 100 and 87% of clinical isolates, respectively. Both genes were detected in 84% of the gastric biopsy samples and in 87% of the clinical isolates. Among vacA genotypes, the s1/m1 genotype was the most common in gastric biopsy samples (48%). The vacA and cagA positive H. pylori strains were detected to a higher degree in patients with chronic active gastritis (71%) than patients with other histopathological findings (29%) (P < 0.05).

Diagnosis of Helicobacter pylori infection

Numerous studies are still published on diagnostic tests for Helicobacter pylori, essentially for noninvasive tests. The urea breath test is applied in different types of patients, and there are attempts to have quicker and simpler protocols. Stool tests using monoclonal antibodies are now evaluated while serology is still a subject of interest. The progress in PCR (multiplex PCR, real-time PCR) has also stimulated the research in this area of invasive tests, in order to get insight into virulence factors, macrolide susceptibility and to detect H. pylori in nonconventional specimens.