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

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.

HELICOBACTER PYLORI OIPA VIRULENCE GENE AS A MOLECULAR MARKER OF SEVERE GASTROPATHIES

BACKGROUND

Helicobacter pylori is an etiologic agent of gastroduodenal diseases. The microorganism, considered a type I carcinogen, affects about 50% of the global population. H. pylori virulence factors are determinant for the clinical outcome of the infection. The outer inflammatory protein A (oipA) gene encodes an outer membrane adhesin and is related to severe gastropathies, such as gastric cancer.

OBJECTIVE

The aim of this study was to evaluate the association of the oipA gene with the severity of gastroduodenal diseases in dyspeptic patients in region Central Brazil.

METHODS

The polymerase chain reaction (PCR) was used to determine the presence of H. pylori. Samples positives were used for molecular screening of the oipA gene. Gastropathies were categorized as non-severe and severe diseases.

RESULTS

Approximately 68% of patients had H. pylori and 36% were infected with H. pylori oipA+ strains. Infection was significantly associated in patients aged over 44 years (P=0.004). However, there was no association between oipA and patients' age (P=0.89). Approximately 46% of patients infected with oipA+ strains had some severe illness. Gastric adenocarcinoma was the most frequent severe gastropathy. The H. pylori oipA genotype was inversely associated with the severity of gastroduodenal diseases (OR=0.247, 95%CI: 0.0804-0.7149 and P=0.007).

CONCLUSION

The characterization of possible molecular markers will contribute to personalized medicine, impacting the prognosis of patients.

BACKGROUND

• Evidence points to an association between the H. pylori oipA gene and gastropathies.

BACKGROUND

• There is a high prevalence of H. pylori infection with a relevant percentage of oipA+ strains.

BACKGROUND

• More severe gastropathies were observed in those infected with H. pylori oipA+ strains.

Effect of the switch status of Helicobacter pylori outer inflammatory protein A on gastric diseases

Helicobacter pylori OipA (Outer Inflammatory Protein A) is an outer membrane protein that takes role in the adherence and colonization to the stomach. oipA gene expression is regulated by the slipped-strand mispairing mechanism through a hypermutable CT dinucleotide repeat motif in the 5΄ region. Alterations in the CT number repeats cause frame-shift mutations to result in phase variation of oipA expression. While a functional "On" status has been recognized as a risk factor for peptic ulcer diseases and gastric cancer in many studies, some controversial findings still exist. To this end, this study compiled the sequence data of oipA from 10 different studies between 2000-2019 and 50 oipA DNA sequences from our own research that examined the relationship between the phase On/Off status of oipA and gastric diseases based on CT repeat number. Overall, we have reached 536 oipA DNA sequences from patients. This large collection of oipA sequences first clarified the absolute conservation of the peptide-pentamer of FWLHA for phase ''On'' status, suggesting this pentamer as a superior marker for the determination of oipA status than counting the number of CT repeats. Combining the sequence and patient data, we have re-analyzed the association between the ''On'' status of oipA and gastric diseases. Our results showed a strong association between oipA ''On'' status and gastric cancer supporting previous findings. We also investigated the AlphaFold2 computed structure of OipA that adopts a beta-barrel fold closely resembling to the autotransporter family of H. pylori. Altogether, this study confirms a strong association between oipA ''On'' statuses and severe gastrointestinal diseases like cancer and provides useful insights into the FWLHA pentamer as an indicator of "On" status of oipA putative autotransporter function rather than CT repeats number.

Genetic diversity of the oipA gene among Helicobacter pylori isolates and clinical outcome in Vietnam

Outer inflammatory protein A (OipA), which is encoded by the oipA gene, can induce interleukin-8 secretion in gastric epithelial cells. The functional status of the oipA gene is regulated by the slipped-strand mispairing mechanism based on the CT dinucleotide repeat number in the 5' region. This study aimed to investigate the oipA functional status ("on/off") of Helicobacter pylori (H. pylori) and its association with gastroduodenal diseases in southwestern Vietnam. The cross-sectional study was conducted on 173H. pylori isolates from 173 patients with gastroduodenal diseases. Sanger sequencing was used to determine the functional status of oipA. Multivariable logistic regression analysis was performed to identify the association between oipA status and gastroduodenal diseases. The oipA "on" status accounted for 96% of H. pylori isolates. Twenty-five CT repeat patterns of the oipA 5' signal region were observed, five of which were novel CT repeat patterns. The oipA "on" status was found in 100%, 97.8%, and 86.8% of H. pylori isolates from patients with peptic ulcer, precancerous lesions, and chronic gastritis, respectively (p < 0.01). The oipA "on" status was related to gastric precancerous lesions versus chronic gastritis (adjusted OR = 7.39, 95% CI: 1.35-40.59, p = 0.021) and peptic ulcers versus chronic gastritis (adjusted OR = 12.79, 95% CI: 1.19-1760.32, p = 0.033). Our data show a high prevalence of the oipA "on" status, which was associated with precancerous gastric lesions and peptic ulcers. Moreover, genetic diversity in the number and pattern of CT dinucleotide repeat of oipA among Vietnamese H. pylori strains was identified.

Analysis of Functional Status of Genetically Diverse OipA Gene in Indian Patients with Distinct Gastrointestinal Disease

Helicobacter pylori (H. pylori,) a genetically diversified bacteria which colonizes human gastric epithelium, is now established causative agent for gastric cancer worldwide. Outer membrane protein (OMP)-coding genes of H. pylori are responsible for attachment and colonization of bacteria. These genes which code proteins on outer membrane of H. pylori is a group of 33 genes which with other virulent genes are causative of giving rise to disease-causing factors in the host. OipA (Outer inflammatory protein A), a participant of Hop family of OMP, is effective in acting as a biomarker for studying progression of diseases like gastric cancer. The functionality of oipA gene is regulated by phase variation within CT repeat pattern. It is the expression, i.e., "on"/"off" of oipA gene which is related with the development of distinct gastric diseases. 40 amplified DNA sequences were studied to investigate functional status of oipA. Our results reveal 57.2% isolates with functional oipA along with significant association with cagA (P = 0.0011) and vacAs1m1/s1m2 (P = 0.0034, P = 0.0093) genotypes, respectively. In conclusion, our results indicate diversity in CT repeat pattern among Indian H. pylori strains. The prevalence of functional oipA gene was found to be ranging between 50% and 64.2% though it did not show significant correlation between functional oipA and disease outcome.

Frequency of virulence-associated genotypes of Helicobacter pylori and their correlation with clinical outcome and histological parameters in infected patients

Helicobacter pylori (H. pylori) is a gram-negative which can cause several gastroduodenal diseases, including gastritis and peptic ulcer disease (PUD). H. pylori specific genotypes have been related to increased occurrence of gastritis and PUD. The aim of this study was to investigate the clinical relevance of the major virulence factors of H. pylori with clinical outcomes and histological parameters in Iranian patients. Totally, 200 subjects with PUD and gastritis disease who underwent gastroduodenal endoscopy were enrolled in this study. The presence of the cagA, vacA, oipA, babA2, and iceA genes in antral gastric biopsy specimens were determined by polymerase chain reaction (PCR) and the results were compared with clinical outcomes and histological parameters. The frequency of babA2 ⁺ , oipA ⁺ , vacA s1/m2, and vacA m2 genes was significantly higher in patients with peptic ulcer disease compared with patients with gastritis. In contrast, the frequency of vacA s1/m1 gene was significantly higher in gastritis subjects than PUD subjects. The high-density scores of H. pylori were strongly associated with iceA1 ^¯ , babA2 ⁺ , and oipA ⁺ genes. Additionally, the high polymorphonuclear cell infiltration and high mononuclear cell infiltration scores were strongly associated with the cagA ⁺ , iceA1 ^¯ , oipA ⁺ genes and cagA ⁺ , babA2 ⁺ , oipA ⁺ genes, respectively. Our study indicated that the vacA, babA2, and oipA virulence factors are related to a higher risk of PUD in subjects with H. pylori-infection. Infection with these strains was associated with a more severe gastropathy.

Contrasting association of Helicobacter pylori oipA genotype with risk of peptic ulceration and gastric cancer

Helicobacter pylori OipA (outer inflammatory protein A) is an outer membrane protein that involves in the binding and colonization of the bacterium in the stomach. The oipA status is associated with the risk of peptic ulcerations (PUs) and gastric cancer (GC) diseases. However, the association trend with PUs compared to GC is often different and highly challenging. We therefore aimed to determine the presence of this genotype in Iranian strains and assess its association with the risk of PUs and GC in a larger number of samples. A total of 319 strains were obtained from 172 patients with non-atrophic gastritis (NAG), 52 with PUs and 95 with GC. The prevalence of the oipA⁺vs. oipA^- genotype was 67.7% (216/319). The total frequency of the oipA⁺vs. oipA^- genotypes in NAG, PUs, GC, non-peptic ulceration (including NAG and GC), and non-tumor (including NAG and PUs) groups was 121/172 (70.3%), 50/52 (96.2%), 45/95 (47.4%), 166/267 (62.2%), and 171/224 (76.3%), respectively. In multiple logistic regression analysis, the oipA⁺vs. oipA^- genotype showed a strong direct association with PUs; the OR_adj (95% CI) was 18.751 (4.421-79.531), (p = 0.00007). In contrast, it had a significant reverse association with GC; the OR_adj (95% CI) was 0.330 (0.179-0.607), (p = 0.00036). In the present study, we interestingly found a contrasting association of the H. pylori oipA genotype with the risk of PUs and GC in Iran. Therefore, the contrasting effect of this genotype may emphasize its independent role in predicting clinical outcomes.

Helicobacter pylori Virulence Factors-Mechanisms of Bacterial Pathogenicity in the Gastric Microenvironment

Gastric cancer constitutes one of the most prevalent malignancies in both sexes; it is currently the fourth major cause of cancer-related deaths worldwide. The pathogenesis of gastric cancer is associated with the interaction between genetic and environmental factors, among which infection by Helicobacter pylori (H. pylori) is of major importance. The invasion, survival, colonization, and stimulation of further inflammation within the gastric mucosa are possible due to several evasive mechanisms induced by the virulence factors that are expressed by the bacterium. The knowledge concerning the mechanisms of H. pylori pathogenicity is crucial to ameliorate eradication strategies preventing the possible induction of carcinogenesis. This review highlights the current state of knowledge and the most recent findings regarding H. pylori virulence factors and their relationship with gastric premalignant lesions and further carcinogenesis.

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.

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.

Genetic diversity and functional analysis of oipA gene in association with other virulence factors among Helicobacter pylori isolates from Iranian patients with different gastric diseases

Helicobacter pylori (H. pylori) is one of the most genetically diverse bacterial pathogens that persistently colonizes the human gastric epithelium. This remarkable genomic plasticity may act as a driving force for successful adaptation and persistence of the bacteria in the harsh gastric environment. Outer inflammatory protein A (OipA) encoded by oipA gene (HP0638/hopH) is a member of the outer membrane proteins (OMPs) of H. pylori involved in induction of IL-8 secretion and is associated with development of peptic ulcer and gastric cancer. Expression of OipA is regulated by phase variation within a CT dinucleotide repeat motif of the oipA gene. In this study we carried out direct DNA sequence analysis of 53 amplified fragments to investigate the oipA "On/Off" status among Iranian H. pylori isolates from patients with various gastric diseases. The prevalence of cagL, cagA, EPIYA motifs, vacA alleles, babA2 and sabA genotypes as well as cagPAI integrity of the isolates were determined by PCR. Our results demonstrated a high prevalence of strains with functional oipA status (79%) and significant associations were found between functional oipA and cagA (P = 0.027) and vacA s1m1 (P = 0.022) genotypes. The vacA s1m2 genotype was also found to be statistically associated with PUD (P = 0.0001). Interestingly, we showed that H. pylori strains with intact cagPAI co-expressed oipA gene in a significant synergistic relationship (P < 0.01). However, no significant association was observed between the functional oipA status and clinical outcomes (P > 0.05). In conclusion, our findings denotes great diversity in the number and pattern of CT dinucleotide repeats of oipA among Iranian H. pylori strains. The synergistic link between functional oipA and other important virulence factors is proposed to be critical in the pathogenesis of H. pylori, which needs further studies with a larger number of samples.

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.

Low Rate of babA2 Genotype among Iranian Helicobacter pylori Clinical Isolates

INTRODUCTION

The Blood Group Antigen-Binding Adhesion (babA), Outer Inflammatory Protein (oipA) and Sialic Acid-Binding Adhesin (sabA) as outer membrane proteins involved in Helicobacter pylori adherence to gastric mucosa have been suggested to have a role in the pathogenesis.

AIM

To investigate the frequency of H. pylori isolates babA2, oipA and sabA genes in Iranian dyspeptic patients.

MATERIALS AND METHODS

DNAs were extracted from H. pylori -positive cultures taken from 100 different dyspeptic patients. Genotyping was performed by Polymerase Chain Reaction (PCR), using the specific primers for babA2, oipA and sabA genes. Chi square test was used to investigate association between variables, p<0.05 was considered statistically significant.

RESULTS

All (100%) isolates possessed oipA and sabA genotypes, whereas babA2 was detected in 22% of isolates. There was no significant relationship between presence of genes with clinical outcome. The combined genotype oipA +/sabA +/ babA2- was correlated with gastritis. The rate of babA2 genotype in our isolates was lower than other Iranian reports.

CONCLUSION

Frequency of babA2 genotype among H. pylori isolates from Southwest of Iran is considerably less than other regions of Iran. Due to heterogeneity of H. pylori strains in different geographic regions, further work will be needed to understand the role of these virulence genes in H. pylori pathogenesis and their possible association with disease outcome.

Helicobacter pylori Outer Membrane Protein-Related Pathogenesis

Helicobacter pylori colonizes the human stomach and induces inflammation, and in some cases persistent infection can result in gastric cancer. Attachment to the gastric mucosa is the first step in establishing bacterial colonization, and outer membrane proteins (OMPs) play a pivotal role in binding to human cells. Some OMP interaction molecules are known in H. pylori, and their associated host cell responses have been gradually clarified. Many studies have demonstrated that OMPs are essential to CagA translocation into gastric cells via the Type IV secretion system of H. pylori. This review summarizes the mechanisms through which H. pylori utilizes OMPs to colonize the human stomach and how OMPs cooperate with the Type IV secretion system.

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.

A systematic review on the association between the Helicobacter pylori vacA i genotype and gastric disease

Helicobacter pylori (H. pylori) has been recognized as a cause of gastrointestinal diseases and progress of the pathology of gastrointestinal diseases is related to the genotype of H. pylori. Published studies have indicated that the H. pylori vacuolating cytotoxin gene A (vacA) i1/i2 genotype is associated with peptic ulcer disease (PUD) and gastric cancer (GC), but their conclusions are inconsistent. This study aimed to further assess the risk of vacA i gene for PUD and/or GC. A systematic search was conducted across three main electronic databases (PubMed, Web of Science, and CNKI). A meta-analysis was then performed on the pooled data of the published articles to estimate the overall influence of vacA i polymorphisms on PUD and/or GC by crude odds ratio (OR) with 95% confidence intervals (CI). The reliability of the results were confirmed by publication bias and sensitivity analysis of included studies. A total of 14 studies were selected according to the specific inclusion and exclusion criteria. The pooled results revealed that patients with GC were more vulnerable to infection by H. pylori i1 genotype (OR = 5.12; 95% CI: 2.66-9.85; P < 0.001) than those with chronic gastritis or nonulcer disease. Moreover, the results of subgroup analysis indicated that the i1 genotype of H. pylori was associated with an increased GC risk (OR = 10.89; 95% CI: 4.11-20.88; P < 0.001) in the Middle Asian population. The H. pylori vacA i1 genotype is associated with an increased GC risk, especially in the Middle Asian population.

Helicobacter pylori in bottled mineral water: genotyping and antimicrobial resistance properties

BACKGROUND

Up to now, fecal-oral and oral-oral are the most commonly known routes for transmission of H. pylori, therefore, contaminated water can play an important role in transmission of H. pylori to humans. Genotyping using virulence markers of H. pylori is one of the best approaches to study the correlations between H. pylori isolates from different samples. The present research was carried out to study the vacA, cagA, cagE, oipA, iceA and babA2 genotyping and antimicrobial resistance properties of H. pylori isolated from the bottled mineral water samples of Iran.

RESULTS

Of 450 samples studied, 8 samples (1.77%) were contaminated with H. pylori. Brand C of bottled mineral water had the highest prevalence of H. pylori (3.63%). The bottled mineral water samples of July month had the highest levels of H. pylori-contamination (50%). H. pylori strains had the highest levels of resistance against metronidazole (62.5%), erythromycin (62.5%), clarithromycin (62.5%), amoxicillin (62.5%) and trimethoprim (62.5%). Totally, 12.5% of strains were resistant to more than 6 antibiotics. VvacAs1a (100%), vacAm1a (87.5%), cagA (62.5%), iceA1 (62.5%), oipA (25%), babA2 (25%) and cagE (37.5%) were the most commonly detected genotypes. M1as1a (62.5%), m1as2 (37.5%), m2s2 (37.5%) and S1a/cagA+/IceA2/oipA-/babA2-/cagE- (50%) were the most commonly detected combined genotypes.

CONCLUSIONS

Contaminated bottled mineral water maybe the sources of virulent and resistant strains H. pylori. Careful monitoring of bottled mineral water production may reduce the risk of H. pylori transmission into the human population.

Investigation of association between oipA and iceA1/iceA2 genotypes of Helicobacter pylori and gastric cancer in Iran

BACKGROUND

H pylori is the main causative agent of Gastric cancer and chronic gastritis. Genetic diversity of H. pylori has major contribution in its pathogenesis. We investigated the prevalence of oipA and iceA1/iceA2 positive strains of H. pylori among patients with gastric cancer and gastritis.

MATERIALS AND METHODS

Sampling performed by means of endoscopy from 86 patients. DNA was extracted from tissue samples using DNA extraction kit. PCR assay was performed and products were monitored by Agarose Gel Electrophoresis.

RESULTS

Urease Test and 16S rRNA PCR did not show significant differences in detection of H. pylori. The frequency of iceA1 allele in patients with gastric cancer was significantly higher than those with gastritis (p<0.05). However, there was no significant difference in prevalence of oipA and iceA2 genes among the two groups of patients (p>0.05).

CONCLUSIONS

The iceA1 gene, but the oipA and iceA2 genes , is associated with H. pylori-induced gastric cancer. However, confirmatory studies must be performed in future.

Application of recombinant Helicobacter pylori outer inflammatory protein A peptide for diagnosis of high virulent Helicobacter pylori infection

AIM: To evaluate the feasibility of recombinant Helicobacter pylori (H. pylori) outer inflammatory protein A (OipA) peptide as a clinical diagnostic agent for high virulent H. pylori infection.

METHODS: Serum and gastric mucosa biopsy specimens were obtained from 285 patients who underwent gastroscopy. H. pylori strains were isolated from urease positive samples and some urease negative samples. Isolated strains were identified by microscopy, urease test and 16S rRNA PCR. OipA and cytotoxin-associated gene A (cagA) of the isolates were obtained by PCR and the oipA signal region was analyed after sequencing. OipA antibody in serum specimen was detected using purified recombinant OipA6 peptide, and CagA antibody was detected by indirect ELISA using a commercial kit. The results of oipA gene and OipA antibody as well as OipA antibody and CagA antibody were compared. The feasibility of OipA6 as a diagnostic agent for high virulent H. pylori infection was evaluated.

RESULTS: A total of 83 isolated H. pylori were obtained, of which 66 was positive for oipA signal region (signal region was on in 62, and undefined in 4), and 59 was positive for cagA. The sensitivity, specificity and consistency rate of recombination antigen OipA6 were 95.16%, 95.83% and 95.28%, respectively, which were all higher than those of CagA (77.97%, 87.50% and 80.72%).

CONCLUSION: Recombinant OipA peptide may be used as an antigen for detection of high virulent H. pylori infection.

Study of the oipA genetic diversity and EPIYA motif patterns in cagA-positive Helicobacter pylori strains from Venezuelan patients with chronic gastritis

CagA and OipA are involved, among other virulence factors, in the ability of Helicobacter pylori to colonize the gastric mucosa and to modulate the host environment during the establishment of chronic infection. The number and type of EPIYA phosphorylation motifs and the presence and functional status of oipA have been involved in the induction of cellular transformations playing an important role in the development of H. pylori associated gastric diseases. This work determined the prevalence of the oipA virulence factor and EPIYA motif patterns in cagA-positive H. pylori gastric biopsies from chronic gastritis patients from the Central-Western region of Venezuela. DNA was extracted directly from gastric biopsies collected by upper endoscopy from 113 patients. The EPIYA motif genotyping and oipA gene functional status was determined by PCR and sequencing. Phylogenetic analysis with the 3' variable region of cagA sequences was performed. Only Western-type EPIYA variants were detected: ABC (68.14%), ABCC (29.20%) and ABCCC (2.66%). High prevalence of strains with the oipA gene (93.8%) and its functional status "ON" (83%) was observed. No significant association between EPIYA motif patterns or oipA functional status with the histological changes in the gastric mucosa was found. Our study demonstrated the absolute predominance of the Western-type cagA gene in a Venezuelan admixed population. This is the first report showing oipA status of H. pylori strains in Venezuela. Further studies with a larger number of samples and including other pathologies are necessary to continue evaluating the role of the H. pylori virulence factors in the prevalence of gastric diseases in our country.

Outer membrane inflammatory protein A, a new virulence factor involved in the pathogenesis of Helicobacter pylori

Outer membrane proteins (OMPs) represent an important class of proteins that are observed in gram-negative bacteria, mitochondria and chloroplasts. These proteins play diverse biological roles in protein translocation, cell-cell communication and signal transduction. A variety of OMPs have been identified in the gastrointestinal pathogen Helicobacter pylori (H. pylori) since it was first isolated in 1983. Among these proteins, outer membrane inflammatory protein A (OipA), which is encoded by hopH and unique to this pathogen, is a differentially expressed outer membrane protein that has been confirmed to be directly linked to H. pylori colonization, as well as to the pathogenesis of H. pylori and disease outcome. In this review, we will describe the progress of recent studies on OipA, particularly those on the functions and biological significance of this unique protein.

H. pylori virulence factors: influence on immune system and pathology

Helicobacter pylori is the most widespread chronic bacterial agent in humans and is well recognized for its association with ulcer disease and gastric cancer, with both representing major global health and socioeconomic issues. Given the high level of adaptation and the coevolution of this bacterium with its human host, a thorough and multidirectional view of the specific microbiological characteristics of this infection as well as the host physiology is needed in order to develop novel means of prevention of therapy. This review aims to pinpoint some of these potentially important angles, which have to be considered mutually when studying H. pylori's pathogenicity. The host's biological changes due to the virulence factors are a valuable pillar of H. pylori research as are the mechanisms by which bacteria provoke these changes. In this context, necessary adhesion molecules and significant virulence factors of H. pylori are discussed. Moreover, metabolism of the bacteria, one of the most important aspects for a better understanding of bacterial physiology and consequently possible therapeutic and prophylactic strategies, is addressed. On the other hand, we discuss the recent experimental proofs of the "hygiene hypothesis" in correlation with Helicobacter's infection, which adds another aspect of complexity to this infection.

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.

The functional interplay of Helicobacter pylori factors with gastric epithelial cells induces a multi-step process in pathogenesis

Infections with the human pathogen Helicobacter pylori (H. pylori) can lead to severe gastric diseases ranging from chronic gastritis and ulceration to neoplastic changes in the stomach. Development and progress of H. pylori-associated disorders are determined by multifarious bacterial factors. Many of them interact directly with host cells or require specific receptors, while others enter the host cytoplasm to derail cellular functions. Several adhesins (e.g. BabA, SabA, AlpA/B, or OipA) establish close contact with the gastric epithelium as an important first step in persistent colonization. Soluble H. pylori factors (e.g. urease, VacA, or HtrA) have been suggested to alter cell survival and intercellular adhesions. Via a type IV secretion system (T4SS), H. pylori also translocates the effector cytotoxin-associated gene A (CagA) and peptidoglycan directly into the host cytoplasm, where cancer- and inflammation-associated signal transduction pathways can be deregulated. Through these manifold possibilities of interaction with host cells, H. pylori interferes with the complex signal transduction networks in its host and mediates a multi-step pathogenesis.

The Role of Helicobacter pylori Outer Membrane Proteins in Adherence and Pathogenesis

Helicobacter pylori is one of the most successful human pathogens, which colonizes the mucus layer of the gastric epithelium of more than 50% of the world’s population. This curved, microaerophilic, Gram-negative bacterium induces a chronic active gastritis, often asymptomatic, in all infected individuals. In some cases, this gastritis evolves to more severe diseases such as peptic ulcer disease, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. H. pylori has developed a unique set of factors, actively supporting its successful survival and persistence in its natural hostile ecological niche, the human stomach, throughout the individual’s life, unless treated. In the human stomach, the vast majority of H. pylori cells are motile in the mucus layer lining, but a small percentage adheres to the epithelial cell surfaces. Adherence to the gastric epithelium is important for the ability of H. pylori to cause disease because this intimate attachment facilitates: (1) colonization and persistence, by preventing the bacteria from being eliminated from the stomach, by mucus turnover and gastric peristalsis; (2) evasion from the human immune system and (3) efficient delivery of proteins into the gastric cell, such as the CagA oncoprotein. Therefore, bacteria with better adherence properties colonize the host at higher densities. H. pylori is one of the most genetically diverse bacterial species known and is equipped with an extraordinarily large set of outer membrane proteins, whose role in the infection and persistence process will be discussed in this review, as well as the different receptor structures that have been so far described for mucosal adherence.

Polymorphism in the Helicobacter pylori CagA and VacA toxins and disease

Half of the world's population is infected with Helicobacter pylori and approximately 20% of infected individuals develop overt clinical disease such as ulcers and stomach cancer. Paradoxically, despite its classification as a class I carcinogen, H. pylori has been shown to be protective against development of asthma, allergy, and esophageal disease. Given these conflicting roles for H. pylori, researchers are attempting to define the environmental, host, and pathogen interactions that ultimately result in severe disease in some individuals. From the bacterial perspective, the toxins, CagA and VacA, have each been shown to be polymorphic and to contribute to disease in an allele-dependent manner. Based on the notable advances that have recently been made in the CagA field, herein we review recent studies that have begun to shed light on the role of CagA polymorphism in H. pylori disease. Moreover, we discuss the potential interaction of CagA and VacA as a mediator of gastric disease.

Helicobacter pylori virulence factors that act at different stages of infection

Helicobacter pylori (H. pylori) plays an essential role in the development of various gastroduodenal diseases, such as chronic superficial gastritis, peptic ulcer, gastric mucosa associated lymphoid tissue (MALT) lymphoma, and gastric adenocarcinoma. The diverse clinical outcomes after H. pylori infection are partly attributable to various H. pylori virulence factors. These virulence factors can act at different stages of infection, including (1) establishing successful colonization; (2) evading the host's immune system and (3) invading the gastric mucosa. In this paper, we review the recent advances in research of H. pylori virulence factors associated with the pathogenic process of H. pylori infection.

[Helicobacter pylori - 2012]

The author overviews some aspects of literature data of the past 2 years. Genetic research has identified polymorphisms of Helicobacter pylori virulence factors and the host which could play a role in the clinical outcome of the infection (peptic ulcer or gastric cancer). So far they have been performed in research centers but with a decrease of costs, they will take their place in diagnosing the diseases and tailoring the treatment. Antibiotic resistance is still growing in Southern European countries and is decreasing in Belgium and Scandinavia. Currently, the clarithromycin resistance rate is of 17-33% in Budapest and levofloxacin resistance achieved 27%. With careful assessment of former antibiotic use the resistance to certain antibiotics can be avoided and the rates of eradication improved. Immigration is a growing problem worldwide: according to Australian, Canadian and Texan studies, the prevalence of Helicobacter pylori is much higher in the immigrant groups than in the local population. An Italian study showed that the eradication rate of triple therapy is significantly lower in the Eastern European immigrants than in the Italians. A recent research has suggested a link between female/male infertility, habitual abortion and Helicobacter pylori infection. However, there are no published data or personal experience to show whether successful eradication of the virus in these cases is followed by successful pregnancies or not. The author overviews the Maastricht process and analyzes the provisions of the Maastricht IV/Florence consensus, in which the new diagnostic algorithms and indications of eradication therapy are reformulated according to the latest levels of evidence and recommendation grading. According to the "test and treat" strategy, either the urea breath test or the stool monoclonal antigen test are recommended as a non-invasive diagnostic method in primary care. Endoscopy is still recommended in case of alarm symptoms, complicated ulcer, or if there is a suspicion of malignancy or MALT lymphoma. Local resistance to clarithromycin and levofloxacin should be considered in the choice of first-line therapy, in case of levels >15-20% these compounds should not be used. In regions with low resistance rates, classical triple therapy remains the regimen of choice; its alternative is the bismuth-based quadruple therapy. Determining antimicrobial resistance is justified after failed second- or third-line therapies; where available, molecular methods (fluorescence in situ hybridization, polymerase chain reaction) should be used. As second/third line treatments, the sequential, bismuth-based quadruple, concomitant quadruple regimens, hybrid are all possible alternatives. The Hungarian diagnostic and therapeutic approach in practice is different in some aspects from the provisions of the European consensus. Orv. Hetil., 2012, 153, 1407-1418.

Epidemiology and diagnosis of Helicobacter pylori infection

Medline, PubMed and the Cochrane databases were searched on epidemiology and diagnosis of Helicobacter pylori for the period of April 2011-March 2012. Several studies have shown that the prevalence of H. pylori infection is decreasing in adults and children in many countries. Various diagnostic tests are available, and most of them have high sensitivity and specificity. The Maastricht IV/Florence consensus report states that the urea breath test using (13)C urea remains the best test to diagnose H. pylori infection. Among the stool antigen tests, the ELISA monoclonal antibody test is recommended. All these tests were used, either as a single diagnostic test or in combination, to investigate H. pylori infection among different populations throughout the world. Of particular interest, current improvements in high-resolution endoscopic technologies enable increased diagnostic accuracy for the detection of H. pylori infection, but none of these techniques, at present, are specific enough for obtaining a real-time diagnosis of H. pylori infection.