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

Infiltration to infection: key virulence players of Helicobacter pylori pathogenicity

PURPOSE

This study aims to comprehensively review the multifaceted factors underlying the successful colonization and infection process of Helicobacter pylori (H. pylori), a prominent Gram-negative pathogen in humans. The focus is on elucidating the functions, mechanisms, genetic regulation, and potential cross-interactions of these elements.

METHODS

Employing a literature review approach, this study examines the intricate interactions between H. pylori and its host. It delves into virulence factors like VacA, CagA, DupA, Urease, along with phase variable genes, such as babA, babC, hopZ, etc., giving insights about the bacterial perspective of the infection The association of these factors with the infection has also been added in the form of statistical data via Funnel and Forest plots, citing the potential of the virulence and also adding an aspect of geographical biasness to the virulence factors. The biochemical characteristics and clinical relevance of these factors and their effects on host cells are individually examined, both comprehensively and statistically.

RESULTS

H. pylori is a Gram-negative, spiral bacterium that successfully colonises the stomach of more than half of the world's population, causing peptic ulcers, gastric cancer, MALT lymphoma, and other gastro-duodenal disorders. The clinical outcomes of H. pylori infection are influenced by a complex interplay between virulence factors and phase variable genes produced by the infecting strain and the host genetic background. A meta-analysis of the prevalence of all the major virulence factors has also been appended.

CONCLUSION

This study illuminates the diverse elements contributing to H. pylori's colonization and infection. The interplay between virulence factors, phase variable genes, and host genetics determines the outcome of the infection. Despite biochemical insights into many factors, their comprehensive regulation remains an understudied area. By offering a panoramic view of these factors and their functions, this study enhances understanding of the bacterium's perspective, i.e. H. pylori's journey from infiltration to successful establishment within the host's stomach.

Hp0521 inhibited the virulence of H. pylori 26,695 strain via regulating CagA expression

Hp0521 is the number of cag pathogenicity island (cagPAI) family in Helicobacter pylori (H. pylori, Hp), which encoded Cag2 protein. The aim of this study was to investigate the role of hp0521 on the H. pylori 26,695 strain. We constructed the recombinant prokaryotic expression plasmid pET-32a-hp0521 and pET-32a-hpc0521. Then, we co-cultured the H. pylori wild strain 26,695 and Δhp0521 strain with GES-1 cells to detect CagA protein transport and IL-8 secretion. We found that Δhp0521 mutation increased the expression of cagA, rpoB and promoted the transportation of CagA protein in GES-1 cells. In addition, we also observed that Δhp0521 mutation had no effect on other cagPAI protein stability and the expression of IL-8. Our findings suggested that hp0521 may down-regulated the expression of cagA, rpoB and inhibited the transportation of CagA protein in GES-1 cells and had no effect on growth.

Efficacy and safety of bifidobacterium quadruple viable tablets in the treatment of Helicobacter pylori-infected peptic ulcer or gastritis patients: a systematic review and meta-analysis

BACKGROUND

To better understand the efficacy and safety of Bifidobacterium quadruple viable tablets in the treatment of helicobacter pylori (H. pylori)-infected peptic ulcer or gastritis patients.

METHODS

A systematic review of the studies published to June 2022 was performed in English database PubMed, Embase, Chinese database CNKI, Wanfang. There were 17 studies were included in this systematic review and meta-analysis. The outcomes measured included H. pylori eradication rate, changes in clinical symptoms of epigastric pain scores, and the incidence of adverse reactions.

RESULTS

The results of the fixed effect model showed that the eradication rate of H. pylori in the combination of Bifidobacterium quadruple viable bacteria tablets combined with bismuth-containing conventional quadruple therapy was greater than that of bismuth-containing conventional quadruple therapy, and the difference was statistically significant (OR = 3.73, 95%CI (2.79,5.00), Z = 2.78, P < 0.001; I² = 0.0%, P > 0.999). The results of random effects model showed that the epigastric pain score of Bifidobacterium quadruple viable bacteria tablets combined with bismuth-containing conventional quadruple therapy was lower than that of bismuth-containing conventional quadruple therapy, and the difference was statistically significant (WMD=-0.70, 95%CI (-1.06,-0.34), Z = 3.82, P < 0.001; I² = 96.7%, P < 0.001). The results of random effects model showed that the acid reflux score of Bifidobacterium quadruple viable bacteria tablets combined with bismuth-containing conventional quadruple therapy was lower than that of bismuth-containing conventional quadruple therapy, and the difference was statistically significant (WMD=-0.98, 95%CI (-1.70,-0.26), Z = 2.66, P < 0.001; I² = 99.7%, P < 0.001).

CONCLUSIONS

The eradication rate of H. pylori by Bifidobacterium quadruple viable bacteria tablets combined with bismuth-containing quadruple therapy is better than that of bismuth-containing quadruple therapy. The improvement of clinical symptoms of patients is better than that of bismuth-containing quadruple therapy, and the incidence of adverse reactions is lower than that of bismuth-containing quadruple therapy. Bifidobacterium quadruple viable bacteria tablet combined with bismuth-containing quadruple therapy was effective and safe. It provides a new way to treat patients with H. pylori.

The heterogeneic distribution of Helicobacter pylori cag pathogenicity island reflects different pathologies in multiracial Malaysian population

Background

Results

Conclusions

Epidemiology and role of Helicobacter pylori virulence factors in gastric cancer carcinogenesis

Infection with Helicobacter pylori is associated with the development of gastric cancer. Although the prevalence of gastric cancer has declined throughout years due to improvement in early screening strategy, mortality due to gastric cancer has not changed. Incidence and mortality due to gastric cancer are higher in developing countries as compared to developed countries. Diagnosis and prognosis of gastric cancer are still poor with patients usually diagnosed with cancer at an advanced stage. Eradication of H. pylori is pertinent for the prevention of gastric cancer. However, the rise in antimicrobial resistance among H. pylori isolates has complicated the prevention strategy. H. pylori express multiple virulence factors for survival in the hostile acid gastric environment. The expression of oncogenic protein cytotoxin-associated gene A (CagA), vacuolating cytotoxin A (VacA), and outer inflammatory protein is essential for H. pylori to exert pathogenesis towards the host. Interestingly, <3% of H. pylori-infected subjects develop gastric cancer, suggesting a unique way of interaction between the host's immune response and H. pylori virulence factors. This article is aimed to review the epidemiology and role of H. pylori in gastric carcinogenesis. A better understanding of the interaction between H. pylori virulence factors and host is required for better gastric cancer prevention.

Genetic diversity and virulence characteristics of Helicobacter pylori isolates in different human ethnic groups

Helicobacter pylori is the most predominant bacterium in almost 50% of the world's population and colonization causes a persistent inflammatory response leading to chronic gastritis. It shows high genetic diversity and individuals generally harbour a distinct bacterial population. With the advancement of whole-genome sequencing technology, new H. pylori subpopulations have been identified that show admixture between various H. pylori strains. Genotypic variation of H. pylori may be related to the presence of virulence factors among strains and is associated with different outcomes of infection in different individuals. This review summarizes the genetic diversity in H. pylori strain populations and its virulence characteristics responsible for variable outcomes in different ethnic groups.

Helicobacter pylori virulence genes

Helicobacter pylori (H. pylori) is one of the most important human pathogens, infecting approximately half of the global population. Despite its high prevalence, only a subset of H. pylori infected individuals develop serious gastroduodenal pathology. The pathogenesis of H. pylori infection and disease outcome is thus thought to be mediated by an intricate interplay between host, environmental and bacterial virulence factors. H. pylori has adapted to the harsh milieu of the human stomach through possession of various virulence genes that enable survival of the bacteria in the acidic environment, movement towards the gastric epithelium, and attachment to gastric epithelial cells. These virulence factors enable successful colonization of the gastric mucosa and sustain persistent H. pylori infection, causing chronic inflammation and tissue damage, which may eventually lead to the development of peptic ulcers and gastric cancer. Numerous studies have focused on the prevalence and role of putative H. pylori virulence genes in disease pathogenesis. While several virulence factors with various functions have been identified, disease associations appear to be less evident, especially among different study populations. This review presents key findings on the most important H. pylori virulence genes, including several bacterial adhesins and toxins, in children and adults, and focuses on their prevalence, clinical significance and potential relationships.

Inverse association of Helicobacter pylori cagPAI genotypes with risk of cardia and non-cardia gastric adenocarcinoma

Iran is a high‐risk country for cardia gastric adenocarcinoma (CGA) in Central Asia, with an incidence rate five times the average global rate, and shows a high infection rate for Helicobacter pylori (69%). The aim was to examine the associations of multiple H. pylori cagPAI genotypes (ie cagH, cagL, cagG, and orf17) with the risk of CGA, non‐CGA, and different histological types of GA in Iran. A large number of H. pylori strains (N = 336) were successfully cultured and genotyped. Histopathological evaluations were performed. The analysis showed an inverse association between the cagH⁺ genotype and the risk of CGA and intestinal‐type gastric adenocarcinoma (IGA) (adjusted ORs; 0.312 and 0.283, respectively), where the controls were nontumors. The orf17⁺ genotype decreased the risk of non‐CGA and diffuse‐type gastric adenocarcinoma (DGA)(adjusted ORs; 0.310 and 0.356, respectively). When the controls were those with nonatrophic gastritis, the cagG⁺ genotype was negatively associated with the risk of CGA, non‐CGA, IGA, and DGA (adjusted ORs; 0.324, 0.366, 0.306, and 0.303, respectively). We did not find such a significant association for the cagL⁺ genotype in multiple logistic regression analysis. Combination of the vacA c2 and cagPAI genotypes further decreased the risk estimates for GAs. This study showed the reverse association of H. pylori cagPAI genotypes—cagH⁺ and cagG⁺—with the risk of CGA in male patients aged ≥ 55 in Iran. Presence of the vacA c2 genotype in combination with cagPAI genotypes showed strong inverse associations with the risk of CGA and non‐CGA. These findings may reveal a coordinated relationship between the vacA c2 and cagPAI genotypes.

Differential Helicobacter pylori Plasticity in the Gastric Niche of Subjects at Increased Gastric Cancer Risk

Helicobacter pylori (H. pylori) represents an independent risk factor for Gastric Cancer (GC). First Degree Relatives (FDR) of GC subjects and Autoimmune Gastritis (AG) patients are both at increased risk for GC. H. pylori genetic heterogeneity within the gastric niche of FDR and AG individuals has been little explored. To understand whether they exploit an increased H. pylori stability and virulence, 14 AG, 25 FDR, 39 GC and 13 dyspeptic patients (D) were investigated by a cultural PCR-based approach characterizing single colonies-forming-units. We chose three loci within the Cytotoxin-associated gene-A Pathogenicity Island (CagPAI) (cagA,cagE,virB11), vacA, homA and homB as markers of virulence with reported association to GC. Inflammatory/precancerous lesions were staged according to Sydney System. When compared to D, FDR, similarly to GC patients, were associated to higher atrophy (OR = 6.29; 95% CI:1.23-31.96 in FDR; OR = 7.50; 95% CI:1.67-33.72 in GC) and a lower frequency of mixed infections (OR = 0.16; 95% CI:0.03-0.81 in FDR; OR = 0.10; 95% CI:0.02-0.48 in GC). FDR presented also an increased neutrophil infiltration (OR = 7.19; 95% CI:1.16-44.65). Both FDR and GC carried a higher proportion of CagPAI⁺vacAs1i1mx⁺homB⁺ profiles (OR = 2.71; 95% CI: 1.66-4.41 and OR = 3.43; 95% CI: 2.16-5.44, respectively). Conversely, AG patients presented a lower frequency of subtypes carrying a stable CagPAI and vacAs1i1mx. These results underline different H. pylori plasticity in FDR and AG individuals, and thus, a different host-bacterium interaction capacity that should be considered in the context of eradication therapies.

Genetic diversity and amino acid sequence polymorphism in Helicobacter pylori CagL hypervariable motif and its association with virulence markers and gastroduodenal diseases

Genetic variability in cagL gene especially within the Helicobacter pylori CagL hypervariable motif (CagLHM) may affect the development of gastric cancer. Therefore, this study was conducted to investigate the association of CagL diversity with clinical outcomes and with H pylori virulence markers. A total of 126 patients with different gastric diseases including non-ulcer dyspepsia (NUD), peptic ulcer disease (PUD), gastric erosion (GE), and gastric cancer (GC) were enrolled. H pylori was cultured from gastric biopsies, and the isolates were screened for the presence of cagL, cagA, vacA, babA2, sabA, and cagPAI integrity by PCR. The amino acid polymorphisms of cagL were analyzed using DNA sequencing. We isolated 61 (48.4%) H pylori strains from 36 NUD, eight PUD, 12 GE, and five GC patients. Almost all isolates were cagL positive (97%), and their RGD, RHS, and SKIIVK motifs were highly conserved. Among 10 CagLHM variants identified, NEIGQ and NKIGQ were detected as the most prevalent sequences. Interestingly, a significant association was found between the presence of NKMGK and PUD (P = 0.002). Notably, the NEIGQ isolates with multiple C-type EPIYA repeat that carried intact cagPAI correlated with disease risk for PUD, GE, and GC (P = 0.021). In conclusion, we identified novel variants of H pylori CagLHM sequences in Iranian population such as NKMGK, which was associated with disease risk for PUD. Further studies using a large number of strains are required to better clarify the function of certain CagLHM motifs in gastric carcinogenesis and disease outcome.

CagL polymorphisms D58/K59 are predominant in Helicobacter pylori strains isolated from Mexican patients with chronic gastritis

Background

Helicobacter pylori is a Gram-negative bacterium that colonizes the gastric mucosa in humans. One of the main virulence factors of H. pylori is the cag pathogenicity island (cagPAI), which encodes a type 4-secretion system (T4SS) and the cytotoxin CagA. Translocation of CagA through the T4SS triggers host-signaling pathways. One of the T4SS proteins is CagL, which is necessary for CagA translocation. CagL is a 26-kDa protein that contains a hypervariable motif, which spans residues 58 to 62. Several polymorphisms in this region have been associated with different disease outcomes, e.g. in Mexico, N58 is associated with a higher risk of gastric cancer. The aim of this work is to analyze the sequence of the hypervariable motif (residues 58 to 62) of clinical isolates from Mexican patients with chronic gastritis, and to correlate these polymorphisms with the vacA genotype.

Results

Of the 164 biopsies analyzed, only 30.5% (50/164) were positive for H. pylori. Thirty-six of the 50 clinical isolates (72%) were cagA positive, and 40 (80%) had the most virulent vacA genotype (s1/m1). Of the cagA positive strains, 94.4% were vacA s1/m1. All the cagA⁺ strains contained the cagL gene. The most prevalent sequence in the polymorphic region (residues 58–62) was DKMGE (75.8%, 25/33), followed by NKMGQ and NEIGQ (6.1%, 2/33), and DEIGQ, NKMGE, DKIGE, and DKIGK (3%, 1/33). Regarding polymorphisms in positions 58 and 59, the most common were D58/K59 (81.8%, 27/33), followed by N58/K59 (9.1%, 3/33), and D58/E59 (3%, 1/33). Only two isolates (6.1%) contained residues N58/E59, which correspond to those found in H. pylori strain ATCC 26695. 92.6% of the clinical isolates having polymorphism D58/K59 had the genotype vacA s1/m1, considered to be the most virulent, while 7.4% had the genotypes vacA s1/m2 and s2/m2.

Conclusions

In Mexican patients, CagL polymorphisms D58, K59, M60, E62, K122, and I134 are more common in patients with chronic gastritis.

oipA "on" status of Helicobacter pylori is associated with gastric cancer in North-Eastern Brazil

Background

Although, outer membrane protein OipA of Helicobacter pylori has been associated with gastric mucosal damage and gastroduodenal diseases, studies evaluating gastric cancer patients are scarce. We investigated whether the functional oipA “on” status was associated with gastric cancer in the North-eastern Brazil, region with high prevalence of gastric cancer.

Methods

We included samples from 95 H. pylori positive subjects (23 patients with gastritis, 24 with gastric cancer, 32 first-degree relatives of gastric cancer patients and 16 children). oipA was assayed by polymerase chain reaction (PCR) and DNA sequencing. cagA and vacA status were evaluated by PCR.

Results

Overall 81.1% of the H. pylori strains had functional oipA. In adults, the oipA “on” status (OR = 9.20; 95%CI = 1.45–58.48, P = 0.02) and increasing age (OR = 1.08; 95%CI = 1.03–1.14; P = 0.003) were independently associated with gastric cancer in a logistic model. The oipA “on” status (OR = 14.75; 95%CI: 2.53–86.13, P = 0.003) was also associated with first-degree relatives of gastric cancer patients when compared with gastritis. The frequency of oipA “on” status did not differ between children and adults (P = 0.87). The oipA “on” status was significantly correlated with the presence of cagA and vacA s1 m1.

Conclusion

oipA “on” status was independently associated with gastric cancer and first-degree relatives of gastric cancer patients in North-eastern Brazil.

Helicobacter pylori outer inflammatory protein A (OipA) suppresses apoptosis of AGS gastric cells in vitro

Outer inflammatory protein A (OipA) is an important virulence factor associated with gastric cancer and ulcer development; however, the results have not been well established and turned out to be controversial. This study aims to elucidate the role of OipA in Helicobacter pylori infection using clinical strains harbouring oipA "on" and "off" motifs. Proteomics analysis was performed on AGS cell pre-infection and postinfection with H. pylori oipA "on" and "off" strains, using liquid chromatography/mass spectrometry. AGS apoptosis and cell cycle assays were performed. Moreover, expression of vacuolating cytotoxin A (VacA) was screened using Western blotting. AGS proteins that have been suggested previously to play a role or associated with gastric disease were down-regulated postinfection with oipA "off" strains comparing to oipA "on" strains. Furthermore, oipA "off" and ΔoipA cause higher level of AGS cells apoptosis and G0/G1 cell-cycle arrest than oipA "on" strains. Interestingly, deletion of oipA increased bacterial VacA production. The capability of H. pylori to induce apoptosis and suppress expression of proteins having roles in human disease in the absence of oipA suggests that strains not expressing OipA may be less virulent or may even be protective against carcinogenesis compared those expressing OipA. This potentially explains the higher incidence of gastric cancer in East Asia where oipA "on" strains predominates.

VacA and CagA Status as Biomarker of Two Opposite End Outcomes of Helicobacter pylori Infection (Gastric Cancer and Duodenal Ulcer) in a Moroccan Population

Helicobacter pylori (H. pylori) infection induces inflammation of the gastric mucosa, which may progress to precancerous lesions leading to gastric cancer. Pathological determinism is associated to some virulence genes of the bacterium, notably the vacA and cagA genes. The present study aimed to determine the H. pylori genotypes distribution and their association with sex, age and gastric diseases in a Moroccan population. Gastric biopsy was taken from 1079 consenting patients. The specimens were processed by PCR to identify H. pylori and to determine the genotypic profile by PCR characterizing vacA s, vacA m and vacA i regions directly from biopsies H. pylori positives. VacA genotyping revealed the predominance of vacA m2 (53.2%), vacA s2 (52.9%) and vacA i2 (52%). The most virulent vacA alleles (s1, i1 and m1) are more predominant in men (47.3%, 41.9% and 46.1% respectively) than in women (38.3%, 33.3% and 37% respectively). However, the association between vacA genotypes and age did not reach a statistical significant value. Logistic regression analysis results show that vacA i1m1 and vacA i1m2 genotypes were strongly associated with the risk of GC, the Odds Ratio (95% confidence interval) was 29.73 [5.08-173.73] and 9.17 [2.06-40.82] respectively, while vacAs1/cagA+ seems to be a risk factor for DU since it is inversely associated with GC (OR was 0.13 [0.02-0.75]. The results of this study suggest that vacA i1 genotype independently to vacAm status may be of a clinical usefulness and will help to identify patients at a high risk of GC development.

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.

Autophagy in Helicobacter pylori Infection and Related Gastric Cancer

BACKGROUND

Autophagy, a degradation pathway in which cytoplasmic content is engulfed and degraded by lysosomal hydrolases, plays a pivotal role in infection and inflammation. Given that defects in autophagy lead to increased susceptibility to infection, we investigated the role of autophagy in Helicobacter pylori-related gastric cancer (GC).

MATERIALS AND METHODS

Gene expression of 84 molecules was examined through quantitative real-time PCR in gastric epithelial cells (AGS) and macrophages (THP-1) upon exposure to H. pylori GC026 (GC) and 26695 (gastritis). Further, ATG16L1 rs2241880, IRGM rs13361189, and IRGM rs4958847, polymorphisms that have been investigated in relation to H. pylori infection or GC in Caucasians, were detected by MALDI-TOF mass spectrometry in 304 ethnic Chinese (86 noncardia GC cases/218 functional dyspepsia controls).

RESULTS

Gene expression analyses showed twenty-eight molecules involved in vesicle nucleation, elongation, and maturation to be significantly down-regulated in H. pylori GC026-challenged AGS cells. Further, core autophagy proteins and autophagy regulators were differentially expressed in H. pylori-challenged THP-1-derived macrophages. Analyses of the selected polymorphisms showed that ATG16L1 rs2241880 increased the risk of GC (OR: 2.38, 95% CI: 1.34-4.24) and H. pylori infection (OR: 1.49, 95% CI: 1.02-2.16) while IRGM rs4958847 decreased GC risk (OR: 0.26, 95% CI: 0.09-0.74) in ethnic Chinese, these effect sizes being especially strong in H. pylori-infected individuals (ATG16L1 rs2241880 and IRGM rs13361189).

CONCLUSIONS

Our findings indicate that highly virulent H. pylori strains markedly modulate autophagy in the host cell. Further, for the first time, autophagy polymorphisms were associated with GC in Chinese, a high GC-risk population.

Helicobacter pylori with the Intact dupA Cluster is more Virulent than the Strains with the Incomplete dupA Cluster

The duodenal ulcer promoting gene (dupA), located in the plasticity region of Helicobacter pylori (H. pylori), is predicted to form a type IV secretory system (T4SS) with vir genes around dupA. In the study, we investigated the association between the dupA cluster status and the virulence of H. pylori in a littoral region of Northeast China. Two hundred and sixty-two H. pylori strains isolated from the chronic gastritis were examined to evaluate the dupA cluster status, cag PAI genes and vacA genotype using PCR and Western blot. Histopathologic evaluations of biopsy specimens were performed to analysis the association between the dupA cluster and the inflammatory response. IL-8 productions in gastric mucosa and from GES-1 cells co-cultured with H. pylori were measured, respectively, to analysis the association between the dupA cluster status and IL-8 production. We found that gastric mucosal inflammatory cell infiltration was significantly higher in patients with dupA-positive H. pylori, including H. pylori with complete dupA cluster (2.71 ± 0.79) and incomplete dupA cluster (2.09 ± 0.61) than in patients with dupA-negative strain (1.73 ± 0.60, p < 0.01), whereas no significant difference in the gastric mucosal atrophy was found according to the status of dupA cluster. Gastric mucosal IL-8 levels were higher in the complete dupA cluster group than in other groups (p < 0.01), and IL-8 production from GES-1 cells was also significantly higher in strains with a complete dupA cluster (1527.9 ± 180.0 pg/ml) than in those with an incomplete dupA cluster (1229.4 ± 75.3 pg/ml, p < 0.01) or those with dupA negative (1201.9 ± 92.3 pg/ml, p < 0.01). In conclusion, the complete dupA cluster in H. pylori is associated with inflammatory cell infiltration and IL-8 secretion, and H. pylori strain with a complete dupA cluster seems to be more virulent than other strains with the incomplete dupA cluster or dupA negative.

Helicobacter pylori genetic diversity and gastro-duodenal diseases in Malaysia

Helicobacter pylori infection results in diverse clinical conditions ranging from chronic gastritis and ulceration to gastric adenocarcinoma. Among the multiethnic population of Malaysia, Indians consistently have a higher H. pylori prevalence as compared with Chinese and Malays. Despite the high prevalence of H. pylori, Indians have a relatively low incidence of peptic ulcer disease and gastric cancer. In contrast, gastric cancer and peptic ulcer disease incidence is high in Chinese. H. pylori strains from Chinese strains predominantly belong to the hspEAsia subpopulation while Indian/Malay strains mainly belong to the hspIndia subpopulation. By comparing the genome of 27 Asian strains from different subpopulations, we identified six genes associated with risk of H. pylori-induced peptic ulcer disease and gastric cancer. This study serves as an important foundation for future studies aiming to understand the role of bacterial factors in H. pylori-induced gastro-duodenal diseases.

The NOD-like receptor signalling pathway in Helicobacter pylori infection and related gastric cancer: a case-control study and gene expression analyses

Background

Currently, it is well established that cancer arises in chronically inflamed tissue. A number of NOD-like receptors (NLRs) form inflammasomes, intracellular multiprotein complexes critical for generating mature pro-inflammatory cytokines (IL-1β and IL-18). As chronic inflammation of the gastric mucosa is a consequence of Helicobacter pylori infection, we investigated the role of genetic polymorphisms and expression of genes involved in the NLR signalling pathway in H. pylori infection and related gastric cancer (GC).

Materials and Methods

Fifty-one genetic polymorphisms were genotyped in 310 ethnic Chinese (87 non-cardia GC cases and 223 controls with functional dyspepsia). In addition, gene expression of 84 molecules involved in the NLR signalling pathway was assessed in THP-1 cells challenged with two H. pylori strains, GC026 (GC) and 26695 (gastritis).

Results

CARD8-rs11672725, NLRP3-rs10754558, NLRP3-rs4612666, NLRP12-rs199475867 and NLRX1-rs10790286 showed significant associations with GC. On multivariate analysis, CARD8-rs11672725 remained a risk factor (OR: 4.80, 95% CI: 1.39–16.58). Further, NLRP12-rs2866112 increased the risk of H. pylori infection (OR: 2.13, 95% CI: 1.22–3.71). Statistical analyses assessing the joint effect of H. pylori infection and the selected polymorphisms revealed strong associations with GC (CARD8, NLRP3, CASP1 and NLRP12 polymorphisms). In gene expression analyses, five genes encoding NLRs were significantly regulated in H. pylori-challenged cells (NLRC4, NLRC5, NLRP9, NLRP12 and NLRX1). Interestingly, persistent up-regulation of NFKB1 with simultaneous down-regulation of NLRP12 and NLRX1 was observed in H. pylori GC026-challenged cells. Further, NF-κB target genes encoding pro-inflammatory cytokines, chemokines and molecules involved in carcinogenesis were markedly up-regulated in H. pylori GC026-challenged cells.

Conclusions

Novel associations between polymorphisms in the NLR signalling pathway (CARD8, NLRP3, NLRP12, NLRX1, and CASP1) and GC were identified in Chinese individuals. Our genetic polymorphisms and gene expression results highlight the relevance of the NLR signalling pathway in gastric carcinogenesis and its close interaction with NF-κB.

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).

Differential proteomics of Helicobacter pylori associated with autoimmune atrophic gastritis

Atrophic autoimmune gastritis (AAG) is a condition of chronic inflammation and atrophy of stomach mucosa, for which development can be partially triggered by the bacterial pathogen Helicobacter pylori (HP). HP can cause a variety of gastric diseases, such as duodenal ulcer (DU) or gastric cancer (GC). In this study, a comparative proteomic approach was used by two-dimensional fluorescence difference gel electrophoresis (DIGE) to identify differentially expressed proteins of HP strains isolated from patients with AAG, to identify markers of HP strain associated with AAG. Proteome profiles of HP isolated from GC or DU were used as a reference to compare proteomic levels. Proteomics analyses revealed 27 differentially expressed spots in AAG-associated HP in comparison with GC, whereas only 9 differential spots were found in AAG-associated HP profiles compared with DU. Proteins were identified after matrix-assisted laser desorption ionization (MALDI)-TOF and peptide mass fingerprinting. Some AAG-HP differential proteins were common between DU- and GC-HP (peroxiredoxin, heat shock protein 70 [HSP70], adenosine 5'-triphosphate [ATP] synthase subunit α, flagellin A). Our results presented here may suggest that comparative proteomes of HP isolated from AAG and DU share more common protein expression than GC and provide subsets of putative AAG-specific upregulated or downregulated proteins that could be proposed as putative markers of AAG-associated HP. Other comparative studies by two-dimensional maps integrated with functional genomics of candidate proteins will undoubtedly contribute to better decipher the biology of AAG-associated HP strains.

Association of presence/absence and on/off patterns of Helicobacter pylori oipA gene with peptic ulcer disease and gastric cancer risks: a meta-analysis

BACKGROUND

There are increasing studies examining the relationship between the status of H. pylori oipA gene and peptic ulcer disease (PUD) and gastric cancer (GC) but the results turn out to be controversial. We attempted to clarify whether oipA gene status is linked with PUD and/or GC risks.

METHODS

A systematically literature search was performed through four electronic databases. According to the specific inclusion and exclusion criteria, seven articles were ultimately available for the meta-analysis of oipA presence/absence with PUD and GC, and eleven articles were included for the meta-analysis of oipA on/off status with PUD and GC.

RESULTS

For the on/off functional status analysis of oipA gene, the "on" status showed significant associations with increased risks of PUD (OR = 3.97, 95% CI: 2.89, 5.45; P < 0.001) and GC (OR = 2.43, 95% CI: 1.45, 4.07; P = 0.001) compared with gastritis and functional dyspepsia controls. Results of the homogeneity test indicated different effects of oipA "on" status on PUD risk between children and adult subgroups and on GC risk between PCR-sequencing and immunoblot subgroups. For the presence/absence analysis of oipA gene, we found null association of the presence of oipA gene with the risks of PUD (OR = 1.93, 95% CI: 0.60, 6.25; P = 0.278) and GC (OR = 2.09, 95% CI: 0.51, 8.66; P = 0.308) compared with gastritis and functional dyspepsia controls.

CONCLUSIONS

To be concluded, when oipA exists, the functional "on" status of this gene showed association with increased risks for PUD and GC compared with gastritis and FD controls. However, merely investigating the presence/absence of oipA would overlook the importance of its functional on/off status and would not be reliable to predict risks of PUD and GC. Further large-scale and well-designed studies concerning on/off status of oipA are required to confirm our meta-analysis results.

Evaluation of the effect of cagPAI genes of Helicobacter pylori on AGS epithelial cell morphology and IL-8 secretion

Helicobacter pylori cagPAI genes play an important role in pathogenesis, however little is known about their functions in isolates from Turkish patients. We aimed to evaluate the intactness and the effect of the cagPAI genes (cagT, cagM, cagE, cagA) and cagA EPIYA motifs on the AGS morphological changes and IL-8 induction. Of 53 patients 38 were found infected with H. pylori. PCR amplification of the cagPAI genes showed 42.1 % intact, 39.5 % partially deleted and 18.4 % with complete deletions. Isolates from gastritis, duodenal and gastric ulcer patients with intact and partially deleted cagPAI genes induced higher IL-8 secretion than those with complete deletions. Isolates from gastritis patients had higher deletion frequencies of the cagT and cagM genes than the other two genes. Infection of AGS cells with isolates that possess intact cagPAI and EPIYA-ABC resulted in the formation of the hummingbird phenotype. The cagA positive isolates induced higher IL-8 secretion than cagA negative isolates. Isolates from DU patients with more than one EPIYA-C motif induced higher concentrations of IL-8 than those with EPIYA-ABC. In conclusion, the intactness of the cagPAI in our isolates from different patients was not conserved. An intact cagPAI was found to play an important role in the pathogenesis of DU but not GU or gastritis. The cagA gene, but not other cagPAI genes, was associated with the induction of IL-8 and the morphological changes of the AGS cells. An increase in the number of EPIYA-C motifs had noticeable effect on the formation of the hummingbird phenotype.

Helicobacter pylori cagL amino acid polymorphisms and its association with gastroduodenal diseases

CagL is a pilus protein of Helicobacter pylori that interacts with host cellular α5β1 integrins through its arginine-glycine-aspartate (RGD) motif, guiding proper positioning of the T4SS and translocation of CagA. Deletion or sequence variations of cagL significantly diminished the ability of H. pylori to induce secretion of IL-8 by the host cell. Therefore, this study was undertaken to investigate the association of cagL and its amino acid sequence polymorphisms with gastric cancer (GC), peptic ulcer disease (PUD), and non-ulcer dyspepsia (NUD) as there are no such studies from India. In total, 200 adult patients (NUD 120, PUD 30, GC 50) who underwent an upper gastrointestinal endoscopy were enrolled. H. pylori infection was diagnosed by rapid urease test, culture, histopathology, and PCR. The collected isolates were screened for cagL genotype by PCR and assessed for amino acid sequence polymorphisms using sequence translation. The prevalence of H. pylori infection in study population was 52.5%. Most of the isolates were cagL genopositive (86.6%), and all had RGD motif in their amino acid sequences. D58 and K59 polymorphisms in cagL-genopositive strains were significantly higher in GC patients (P < 0.05). Combined D58K59 polymorphism was associated with higher risk of GC (3.8-fold) when compared to NUD. In conclusion, H. pylori cagL amino acid polymorphisms such as D58K59 are correlated with a higher risk of GC in the Indian population. Further studies are required to know the exact role of particular cagL amino acid polymorphisms in the pathogenicity of H. pylori infection.

Distribution of Helicobacter pylori virulence markers in patients with gastroduodenal diseases in a region at high risk of gastric cancer

ABSTRACT BACKGROUND

Helicobacter pylori (H. pylori) is a major human pathogen that is responsible for various gastroduodenal diseases. We investigated the prevalence of H. pylori virulence markers in a region at high risk of gastric cancer.

METHODS

One hundred and sixteen H. pylori strains were isolated from patients with gastroduodenal diseases. cagA, the cagA 3' variable region, cagPAI genes, vacA, and dupA genotypes were determined by PCR, and some amplicons of the cagA 3' variable region, cagPAI genes and dupA were sequenced.

RESULTS

cagA was detected in all strains. The cagA 3' variable region of 85 strains (73.3%) was amplified, and the sequences of 24 strains were obtained including 22 strains possessing the East Asian-type. The partial cagPAI presented at a higher frequency in chronic gastritis (44.4%) than that of the severe clinical outcomes (9.7%, p < 0.001). The most prevalent vacA genotypes were s1a/m2 (48.3%) and s1c/m2 (13.8%). Thirty-six strains (31.0%) possessed dupA and sequencing of dupA revealed an ORF of 2449-bp. The prevalence of dupA was significantly higher in strains from patients with the severe clinical outcomes (40.3%) than that from chronic gastritis (20.4%, p = 0.02).

CONCLUSION

The high rate of East Asian-type cagA, intact cagPAI, virulent vacA genotypes, and the intact long-type dupA may underlie the high risk of gastric cancer in the region.

Association of IS605 and cag-PAI of Helicobacter pylori Isolated from Patients with Gastrointestinal Diseases in Taiwan

Background. The cag pathogenicity island (cag-PAI) is one of the most important virulent determinants of Helicobacter pylori. An insertion sequence (IS) element of cag-PAI (IS605) has been found to generate H. pylori strains with varying virulence. Aim. To evaluate the impact of IS605 and cag-PAI on H. pylori strains isolated from Taiwanese patients with severity of gastric diseases. Methods. H. pylori isolates were cultured from gastric biopsies from 99 patients with peptic ulcer, chronic gastritis, and gastric carcinoma. Six distinct, well-separated colonies were isolated from each patient and analyzed by genotyping. Results. cagA, cagE, cagM, cagT, orf10, and orf13 were found to be present in 90.0%–100.0% of the H. pylori isolates. A total deletion of cagA, cagE, cagM, cagT, orf10, and orf13 was found in 1 isolate (1.0%). The IS605 element was found to be positive in 15.2% of the isolates. The presence of IS605 was higher in H. pylori isolated from patients with gastric carcinoma (25.0%) than in patients with duodenal ulcer (6.5%) or chronic gastritis (6.3%) (P < 0.001). Conclusions. The majority of the patients examined had intact cag-PAI. IS605 was present in 15.2% and was higher in H. pylori isolated from patients with gastric carcinoma than in those with peptic ulcer.

Role of Helicobacter pylori cagA EPIYA motif and vacA genotypes for the development of gastrointestinal diseases in Southeast Asian countries: a meta-analysis

Background

Infection with cagA-positive, cagA EPIYA motif ABD type, and vacA s1, m1, and i1 genotype strains of Helicobacter pylori is associated with an exacerbated inflammatory response and increased risk of gastroduodenal diseases. However, it is unclear whether the prevalence and virulence factor genotypes found in Southeast Asia are similar to those in Western countries. Here, we examined the cagA status and prevalence of cagA EPIYA motifs and vacA genotypes among H. pylori strains found in Southeast Asia and examined their association with gastroduodenal disease.

Methods

To determine the cagA status, cagA EPIYA motifs, and vacA genotypes of H. pylori, we conducted meta-analyses of 13 previous reports for 1,281 H. pylori strains detected from several Southeast Asian countries.

Results

The respective frequencies of cagA-positive and vacA s1, m1, and i1 genotypes among examined subjects were 93% (1,056/1,133), 98% (1,010/1,033), 58% (581/1,009), and 96% (248/259), respectively. Stratification showed significant variation in the frequencies of cagA status and vacA genotypes among countries and the individual races residing within each respective country. The frequency of the vacA m-region genotype in patients infected with East Asian-type strains differed significantly between the northern and southern areas of Vietnam (p < 0.001). Infection with vacA m1 type or cagA-positive strains was associated with an increased risk of peptic ulcer disease (odds ratio: 1.46, 95%CI: 1.01-2.12, p = 0.046 and 2.83, 1.50-5.34, p = 0.001, respectively) in the examined Southeast Asian populations.

Conclusions

Both Western- and East Asian-type strains of H. pylori are found in Southeast Asia and are predominantly cagA-positive and vacA s1 type. In Southeast Asia, patients infected with vacA m1 type or cagA-positive strains have an increased risk of peptic ulcer disease. Thus, testing for this genotype and the presence of cagA may have clinical usefulness.

Helicobacter pylori oipA genetic diversity and its associations with both disease and cagA, vacA s, m, and i alleles among Bulgarian patients

Prevalence of outer inflammatory protein (oipA) gene functional status in Helicobacter pylori strains from Southeastern Europe is still unclear. H. pylori strains from 70 symptomatic patients were polymerase chain reaction (PCR) assessed for cagA and vacA types, and oipA gene functional status was evaluated by PCR and sequencing. Our results demonstrated a high prevalence of strains with oipA status "on" genes (81%) and strong association between them and peptic ulcers, cagA, and vacA s1 and s1/m1 genotypes, regardless of the patient gender, place of residence, and age. Importantly, most vacA i1 strains (93%) harbored oipA status "on" versus only 57% of those with vacA i2 type. The vacA i1 genotype was less frequent (66%) than both cagA and vacA s1 types. The virulent strains with cagA(+) and vacA s1, m1, and i1 were detected in 35% as a predominant genotype and almost all (96%) of these strains harbored oipA status "on". In conclusion, the high prevalence of in-frame oipA gene strains (81%), associated with peptic ulcers and cagA(+), vacA s1, m1, m2, and, importantly, i1 genotypes, indicates a strong synergistic activity of H. pylori virulence factors.

Helicobacter pylori with stronger intensity of CagA phosphorylation lead to an increased risk of gastric intestinal metaplasia and cancer

Background

Nearly all Taiwanese H. pylori stains are cagA-genopositive and encode CagA protein. In this study, we evaluated whether different intensity of tyrosine phosphorylated-CagA (p-CagA) had an impact on the clinical diseases and histological outcomes in this area.

Results

We enrolled 469 dyspeptic patients and prospectively obtained the gastric biopsy specimens and the H. pylori isolates. These patients were categorized according to the clinical diseases, such as duodenal ulcer, gastric ulcer, gastric cancer, and gastritis with or without intestinal metaplasia. Their gastric specimens were reviewed by the updated Sydney's system. Furthermore, a total of 146 patients were randomly selected from each clinical category for evaluation of their isolates' p-CagA intensity by in vitro AGS cells co-culture. The p-CagA was sparse in 30 (20.5%), weak in 59 (40.5%), and strong in 57 (39%) isolates. The isolates from the patients of gastric cancer or gastritis with intestinal metaplasia had stronger p-CagA intensity than those of gastritis without intestinal metaplasia (p ≤ 0.002). Moreover, the patients infected with isolates with strong or weak p-CagA intensity had a higher risk of gastric intestinal metaplasia (p < 0.05, odds ratio 3.09~15.26) than those infected with sparse p-CagA isolates.

Conclusions

Infection with H. pylori stains with stronger p-CagA intensity may lead to an increased risk of gastric intestinal metaplasia and cancer.

Structural and functional aspects of unique type IV secretory components in the Helicobacter pylori cag-pathogenicity island

Helicobacter pylori cytotoxin-associated gene-pathogenicity island (cagPAI) is responsible for the secretion of the CagA effector through a type IV secretion system (T4SS) apparatus, as well as of peptidoglycan and possibly other not yet identified factors. Twenty-nine different polypeptide chains are encoded by this cluster of genes, although only some of them show a significant similarity with the constitutive elements of well characterized secretion systems from other bacteria. The other cagPAI components represent almost unique proteins in this scenario. The majority of the T4SS include approximately fifteen components, taking into account either the transmembrane complex subunits, ATPases or substrate factors. The composition of the cagPAI is very complex: it includes proteins most likely involved at different levels in the pilus assembly, stabilization and processing of secreted substrate, as well as regulatory particles possibly involved in the control of the entire apparatus. Despite recent findings with respect to components that play a role in the interaction with the host cell, the function of several cagPAI proteins remains unclear or unknown. This is particularly true for those that represent unique members with no clear similarity to those of other T4SS and no obvious evidence of involvement in the secretion of CagA or induction of pro-inflammatory responses. We summarize what is known about these accessory components, both from a molecular and structural point of view, as well as their putative physiological role.

Helicobacter pylori and its effect on innate and adaptive immunity: new insights and vaccination strategies

Infection with the gastric bacterium Helicobacter pylori invariably leads to active chronic gastritis, and is strongly correlated to peptic ulcer disease, gastric adenocarcinoma and mucosa-associated lymphoid tissue lymphoma. The infection leads to local accumulation of inflammatory cells and strong activation of B- and T-cell immunity. Still, the immune response can not eliminate the bacteria, and unless antibiotic treatment is used, the infection is usually lifelong. During the last few years, several immunomodulatory properties of H. pylori have been described, which probably contribute to the inability of the immune system to eradicate the bacterium. Another factor promoting bacterial persistence is probably the induction of a substantial regulatory T-cell response by the infection. Several different immunization schedules have resulted in protective immunity in animal models, while in humans no reliable vaccine is available as yet. In this article, we describe the innate and adaptive immune responses to H. pylori, and the attempts to create an effective vaccine.

Systematic review and meta-analysis: the relationship between the Helicobacter pylori dupA gene and clinical outcomes

Background

In 2005, the first disease-specific Helicobacter pylori virulence factor that induced duodenal ulcer and had a suppressive action on gastric cancer has been identified, and was named duodenal ulcer promoting gene (dupA). However, the importance of the dupA gene on clinical outcomes is conflicting in subsequent studies. The aim of this study was to estimate the magnitude of the risk for clinical outcomes associated with dupA gene.

Methods

A meta-analysis of case-control studies which provided raw data on the infection rates with the dupA-positive H. pylori detected by polymerase chain reaction was performed.

Results

Seventeen studies with a total of 2,466 patients were identified in the search. Infection with the dupA-positive H. pylori increased the risk for duodenal ulcer by 1.41-fold (95% confidence interval [CI], 1.12-1.76) overall. Subgroup analysis showed that the summary odds ratio (OR) was 1.57 (95% CI, 1.19-2.06) in Asian countries and 1.09 (95% CI, 0.73-1.62) in Western countries. There was no association between the presence of the dupA gene and gastric cancer and gastric ulcer. Publication bias did not exist.

Conclusion

Our meta-analysis confirmed the importance of the presence of the dupA gene for duodenal ulcer, especially in Asian countries.

Matrix metalloproteinase-3 promoter polymorphisms but not dupA-H. pylori correlate to duodenal ulcers in H. pylori-infected females

Background

This study investigated if the H. pylori dupA genotype and certain host single nucleotide polymorphisms (SNPs) of matrix metalloproteinases (MMPs) and their inhibitors (TIMPs), including MMP-3, MMP-7, MMP-9, TIMP-1 and TIMP-2, might correlate with ulcer risk of H. pylori-infected Taiwanese patients.

Results

Of the 549 H. pylori-infected patients enrolled, 470 patients (265 with gastritis, 118 with duodenal ulcer, and 87 with gastric ulcer) received SNPs analysis of MMP-3_{-1612 6A > 5A}, MMP-7_{-181 A > G}, MMP-9_{exon 6 A > G}, TIMP-1_{372 T > C} and TIMP-2_{-418 G > C} by PCR-RFLP. The 181 collected H. pylori isolates were detected for the dupA genotype by PCR. The rates of dupA-positive H. pylori infection were similar among patients with duodenal ulcer (22.8%), gastric ulcer (20.0%), and gastritis (25.5%) (p > 0.05). Males had higher rates of duodenal ulcer and gastric ulcer than females (p < 0.01). Of H. pylori-infected patients, the MMP-3 6A6A genotype were more common in patients with duodenal ulcers than in those with gastritis (87.7% vs. 74.9%, p < 0.05) in females. This genotype had a 2.4-fold (95% CI: 1.02-5.66) increased risk of duodenal ulcer, compared to those with the 5A carrier. Combining the MMP-3/TIMP-1 genotype as 6A6A/CC, the risk of duodenal ulcer increased up to 3.6 fold (p < 0.05) in H. pylori-infected females.

Conclusions

The MMP-3 promoter polymorphism, but not the dupA-status, may correlate with susceptibility to duodenal ulcer after H. pylori infection in Taiwanese females.

Different cagA and vacA Polymorphisms are Found in the Chinese versus the Malay and Indian Populations: An Analysis of Helicobacter Pylori Virulence Genes in Singapore

Aim:

Helicobacter pylori causes peptic ulcer disease and gastric cancer. Western studies suggest that polymorphisms in the virulence factors cagA and vacA may determine the ability of bacteria to cause gastroduodenal diseases. Differences in the cagA EPIYA motifs and polymorphisms of the signal (s), middle (m) and intermediate (i) regions of vacA are thought to be important. The aim of this study was to compare the polymorphisms of cagA and vacA of H. pylori isolated from the Chinese, Malay and Indian populations living in Singapore.

Method:

A total of 104 H. pylori isolates obtained from patients with dyspeptic symptoms were analysed. Of the 104 patients, 80 were Chinese, 9 Malays and 15 Indians. DNA was extracted from the isolates and the vacA allelic types and cagA EPIYA motifs were determined by polymerase chain reaction (PCR) and sequencing, respectively.

Results:

Differences in the vacA and cagA polymorphisms were found between the Chinese, Malays and Indians. Significantly more non-Chinese patients carried vacA s1/m1 strains versus Chinese patients ( p < 0.05). All 9 Malay patients, 11/15 (73.3%) Indians and 31/80 (38.8%) Chinese patients carried H. pylori strains with the vacA s1/m1/i1. Significantly more Chinese patients carried isolates with East Asian cagA EPIYA motifs versus non-Chinese patients ( p < 0.05). 79/80 (98.8%) of the Chinese isolates, 2/15 (13%) of Indian isolates, and 5/9(55.6%) of Malay isolates possessed CagA with the East Asian ABD type motif.

Conclusion:

Results from the current study demonstrated marked differences in the polymorphisms of vacA and CagA EPIYA motifs in strains isolated from Chinese versus non-Chinese patients. Epidemiologically, the Chinese are at the highest risk of developing gastric cancer. Work is ongoing to determine if differences found in the CagA EPIYA motifs of isolates from the Chinese patients can contribute to a subject's risk of developing gastric cancer.