H. pylori infection: bacterial virulence factors and cytokine gene polymorphisms as determinants of infection outcome

Helicobacter pylori infection and the risk of colorectal cancer: a nationwide population-based cohort study

BACKGROUND

The role of Helicobacter pylori (H. pylori) infection in the development of colorectal neoplasia has been a matter of scientific debate with controversial findings.

AIMS

This study examined the association between H. pylori infection and colorectal cancer (CRC) in a nationwide population-based Chinese cohort study.

METHODS

A total of approximately 3936 individuals with newly diagnosed H. pylori infection (the H. pylori-infected cohort) and 15 744 age- and sex-matched patients with diagnoses absence of H. pylori infection (the comparison cohort) from 2000 to 2005 were identified from Taiwan's National Health Insurance Research Database. The Kaplan-Meier method was used for measuring the cumulative incidence of CRC in each cohort. Cox proportional hazards models were used to compute hazard ratios (HRs) and accompanying 95% confidence intervals (CIs) for the estimation of the association between H. pylori infection and CRC.

RESULTS

The cumulative incidence of CRC was higher in H. pylori-infected cohort than that in the comparison cohort (log-rank test, P < 0.001). After adjustment for potential confounders, H. pylori infection was associated with a significantly increased risk of CRC (adjusted HR 1.87; 95% CI 1.37-2.57). In addition, the HR of CRC appeared to increase with increasing frequency of clinical visits for H. pylori infection.

CONCLUSIONS

Our study demonstrated that H. pylori infection was associated with an increased risk of CRC, which warrants confirmation and exploration of the underlying biologic mechanisms by future studies.

Association between TNFA Gene Polymorphisms and Helicobacter pylori Infection: A Meta-Analysis

Background

Several host genetic factors are thought to affect susceptibility to Helicobacter pylori infection-related diseases, including tumor necrosis factor (TNF)-α. Previous studies have evaluated the association between TNFA gene polymorphisms and H. pylori infection, but the results were inconclusive. We conducted this meta-analysis to clarify the association between TNFA polymorphisms and H. pylori infection.

Methods

Published literature within PubMed, Embase, and the Cochrane Library were used in our meta-analysis. Data were analyzed with the Stata13.1 software package using pooled odds ratios (ORs) with 95% confidence intervals (CI).

Results

A total of 24 studies were included in our study. The TNFA -308G>A polymorphism was associated with decreasing H. pylori infection (AA vs. AG+GG, OR = 0.64, 95% CI = 0.43–0.97; AA vs. GG, OR = 0.64, 95% CI = 0.43–0.97). A significantly decreased risk was also found for -1031T>C polymorphism (CC vs. CT+TT, OR = 0.61, 95% CI = 0.44–0.84). -863C>A polymorphism was associated with increasing risk of H. pylori infection (AA+AC vs. CC, OR = 1.47, 95% CI = 1.16–1.86; A allele vs. C allele, OR = 1.40, 95% CI = 1.14–1.72). There was no significant association between -857C>T polymorphism and H. pylori infection. When stratified analysis was conducted on H. pylori infection detection methods, -857C>T and -863C>A polymorphisms were associated with H. pylori infection for the non-ELISA subgroup. When stratified for ethnicity or study design, -863C>A significantly increased the risk and -1031T>C decreased the risk for the Asian subgroup and hospital-based subgroup.

Conclusion

Results of our meta-analysis demonstrate that TNFA -308G>A and -1031 T>C polymorphisms may be protective factors against H. pylori infection, and -863C>A may be a risk factor, especially in Asian populations. Further studies with larger sample sizes are required to validate these results.

Helicobacter pylori strains harboring babA2 from Indian sub population are associated with increased virulence in ex vivo study

Background

The babA2 gene along with the cagA and vacA of Helicobacter pylori has been considered as a risk factor for the disease outcome in certain populations. This study was aimed to understand the role of babA2 of H. pylori with the background of cagA and vacA in disease manifestations in Indian sub population.

Methods

A total of 114 H. pylori strains isolated from duodenal ulcer (DU) (n = 53) and non-ulcer dyspepsia (NUD) patients (n = 61) were screened for the prevalence of these virulence markers by PCR. The comparative study of IL-8 production and apoptosis were done by co-culturing the AGS cell line with H. pylori strains with different genotypes. Adherence assay was performed with babA2 positive and negative strains. Two isogenic mutants of babA2 were constructed and the aforesaid comparative studies were carried out.

Results

PCR results indicated that 90.6 % (48/53), 82 % (50/61) and 73.6 % (39/53) strains from DU patients were positive for cagA, vacA, and babA2, respectively. Whereas the prevalence of these genes in NUD subjects were 70.5 % (43/61); 69.8 % (37/53), and 65.6 % (39/61), respectively. Although adherence to AGS cells was comparable among strains with babA2 positive and negative genotypes, but the triple positive strains could induce highest degree of IL-8 production and apoptosis, followed by the cagA⁻/vacA⁻/babA2⁺ strains and triple negative strains, respectively. The wild type strains showed significantly higher IL-8 induction as well as apoptosis in ex vivo than its isogenic mutant of babA2.

Conclusion

PCR study demonstrated that there was no significant association between the distribution of babA2 genotype or of triple positive strains and disease outcome in this sub population. The adherence assay showed that there was no significant difference in the extent of adherence to AGS cells among babA2 positive and negative strains. But the ex vivo study indicated that the triple positive or even the babA2 only positive strains are involved in increased virulence. The wild type strains also exhibited increased virulence compared to the babA2 mutant strains. This inconsistency demonstrated that bacterial genotype along with host genetic polymorphisms or other factors play important role in determining the clinical manifestation of H. pylori infections.

Correlation Between Mucosal IL-6 mRNA Expression Level and Virulence Factors of Helicobacter pylori in Iranian Adult Patients With Chronic Gastritis

BACKGROUND

Helicobacter pylori infection is associated with gastritis and marked infiltration of the gastric mucosa by several cytokines secreting inflammatory cells that contribute to sustained local inflammation. In this study, we sought to examine IL-6 expression in H. pylori-infected and uninfected gastric mucosa and elucidate the implication in the pathogenesis of H. pylori-associated gastritis in human.

OBJECTIVES

The current study aimed to determine mucosal IL-6 mRNA expression level and their correlation with virulence factors and the grade of chronic gastritis among H. pylori infected patients with chronic gastritis from Shahrekord, Iran.

PATIENTS AND METHODS

Mucosal IL-6 mRNA levels was measured by real-time PCR using endoscopic biopsies taken from the gastric antrum of 58 subjects infected with H. pylori and 44 uninfected subjects. Presence of vacA and cagA virulence factors was evaluated using PCR.

RESULTS

The IL-6 mRNA expression levels were significantly more elevated in H. pylori-positive patients than uninfected individuals and expression of this cytokine was independent from the virulence factors. There was a correlation between IL-6 expression level and the grade of chronic gastritis.

CONCLUSIONS

Enhanced induction of IL-6 may be involved in the pathogenesis of H. pylori-associated gastritis.

Mucosal interleukin-21 mRNA expression level is high in patients with Helicobacter pylori and is associated with the severity of gastritis

Helicobacter pylori (H. pylori) infection is associated with gastritis and marked infiltration of the gastric mucosa by several cytokines secreting inflammatory cells. Different clinical forms of the infection may reflect distinctive patterns of cytokine expression. Interleukin (IL)-17, IL-21, IL-22, and IL-23 have been reported to be involved in H. pylori-induced gastric mucosal inflammation, but the details and relationship to different patterns of inflammation and virulence factors remain unclear. The present study was launched to analyse IL-6 expression in H. pylori-infected and uninfected gastric patients and to investigate its correlation with chronic gastritis among H. pylori-infected patients. Total RNA was extracted from the gastric antrum biopsies of 48 H. pylori-infected patients and 38 H. pylori uninfected patients. Mucosal IL-21 mRNA expression level in H. pylori-infected and uninfected gastric biopsy was determined by real-time PCR. The presence of vacA (vacuolating cytotoxin A) and cagA (cytotoxin associated gene A) virulence factors were evaluated using PCR. Interleukin-21 mRNA expression was significantly high in biopsies of H. pylori-infected patients compared to H. pylori uninfected patients, and the mucosal IL-21 mRNA level was positively correlated with the grade of chronic inflammation. There was no association between virulence factors and IL-21 mRNA expression. We believe that IL-21 might be involved in the pathogenesis of H. pylori and might be an index of the severity of chronic gastritis.

Multiple infections and cancer: implications in epidemiology

Approximately 18% of the global cancer burden has been attributed to infectious agents, with estimates ranging from 7% in developed countries to about 22% in developing countries. Chronic infections caused by the hepatitis B and C viruses, human papilloma viruses (HPV), and Helicobacter pylori (H. pylori) are reported to be responsible for approximately 15% of all human cancers. Interestingly, although many of the infectious agents that have been associated with cancer--such as HPV, Epstein-Barr virus (EBV), and H. pylori--are highly prevalent in the world, most infected individuals do not develop cancer but remain lifelong carriers. Malignancies associated with infectious agents may result from prolonged latency as a result of chronic infections. Pathogenic infections are necessary but are not sufficient for cancer initiation or progression. Cancer initiation may require additional cofactors, including secondary infections. Therefore, in patients with chronic infection with one agent, secondary co-infection with another agent may serve as an important co-factor that may cause cancer initiation and progression. Additionally, opportunistic co-infections could significantly inhibit response to cancer treatment and increase cancer mortality. Co-infections are relatively common in areas with a high prevalence of infectious agents, especially in developing countries. These co-infections can cause an imbalance in the host immune system by affecting persistence of and susceptibility to malignant infections. Several articles have been published that focus on infectious agents and cancer. In this article, we discuss the role of infectious agents in malignancies, highlight the role of multiple/co-infections in cancer etiology, and review implications for cancer epidemiology.

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

Objective

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

Methods

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

Results

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

Conclusions

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

Helicobacter pylori breath testing in an open access system has a high rate of potentially false negative results due to protocol violations

BACKGROUND

Among available tests to detect Helicobacter pylori (H. pylori), urea breath test (UBT) is the most accurate when performed correctly in research protocols with unknown validity in clinic settings.

MATERIAL AND METHODS

A total of 595 subjects at a gastroenterology clinic were tested 620 times with UBT. Detailed information about three known factors (recent proton-pump inhibitors (PPI), antibiotics, or bismuth, H. pylori eradication treatment finished <4 weeks ago, and gastric resection) to make UBT unreliable were prospectively recorded before each test.

RESULTS

Twenty-three percent (120 of 526) of all negative tests fell in one or more of the three categories, which had the potential to make UBT unreliable. Of those carried out on persons without being treated before, the potential false negative rate was 15%. Among those with previous eradication treatment, the rate was around 45%.

CONCLUSIONS

If a negative UBT could be false negative in up to 23% of cases, then it has a serious lack of negative predictive value. A negative UBT should be considered false negative until potential protocol violations are excluded.

Circulating interleukin-27 levels in Helicobacter pylori-infected patients with gastric or duodenal ulcers, independent of the bacterial cytotoxin-associated gene A virulence factor

OBJECTIVE

The aim was to evaluate the interleukin (IL)-27 levels in Helicobacter pylori (H. pylori)-infected patients with gastric ulcer (GU) or duodenal ulcer (DU) and to determine its association with H. pylori virulence factor cytotoxin-associated gene A (CagA).

METHODS

In all, 127 H. pylori infected patients (including 96 DU patients, of whom 61 were anti-CagA(+) and 35 were anti-CagA(-)) and 31 GU patients (of whom 15 were anti-CagA(+) and 16 were anti-CagA(-)), 60 asymptomatic (AS) carriers (of whom 30 were anti-CagA(+) and 30 were anti-CagA(-)) and 30 healthy H. pylori-negative participants (as a control) were enrolled in the study. Serum concentrations of IL-27 were measured by the enzyme-linked immunosorbent assay method.

RESULTS

The mean levels of IL-27 in the GU (44.26 ± 7.12 pg/mL) and DU patients (40.84 ± 3.90 pg/mL) was significantly higher than those observed in the AS carriers (22.06 ± 1.90 pg/mL, P < 0.001) and the control group (18.12 ± 1.68 pg/mL, P < 0.001 and P < 0.002, respectively). In the GU, DU and AS groups the levels of IL-27 in anti-CagA(+) participants were not significantly differ from that in the anti-CagA(-) participants.

CONCLUSIONS

These results showed that the mean concentration of IL-27 in H. pylori-infected peptic ulcer (PU) patients was higher than in AS carriers and the healthy control group. The serum concentrations of IL-27 were not affected by the CagA factor.

Gastroesophageal Reflux Disease and Helicobacter pylori: What May Be the Relationship?

Relationship between Helicobacter pylori (H. pylori) and gastroesophageal reflux disease (GERD) is controversial. We aimed to review the possible relationship between H. pylori infection and GERD. Epidemiological data indicate an inverse relationship between frequency of H. pylori infection and prevalence of GERD and its complications like Barrett's esophagus and esophageal adenocarcinoma. H. pylori eradication in patients with peptic ulcer disease may be associated with increased risk of development of GERD compared with untreated patients. Infection with cagA bearing strains of H. pylori was associated with less severe GERD including endoscopic esophagitis, possibly due to pangastritis leading to hypochlorhydria. Recent studies on inflammatory markers (IL-1β and IL-1RN) suggest pro-inflammatory genotypes to be protective against development of severe GERD, especially in patients with H. pylori infection. Identification of candidate genes playing an important role in gastric acid secretion and visceral hypersensitivity to the esophageal epithelium might help in early detection of individuals susceptible to develop GERD. Interplay between H. pylori and host factors play an important role in the pathogenesis of GERD.

Angiotensin II-generating enzymes, angiotensin-converting enzyme (ACE) and mast cell chymase (CMA1), in gastric inflammation may be regulated by H. pylori and associated cytokines

BACKGROUND

The local angiotensin II system (LAS) has numerous functions, including the regulation of growth and differentiation in the gastrointestinal tract. Angiotensin II (AngII) may be generated by angiotensin-I-converting enzyme (ACE) or mast cell chymase (CMA1) and plays an important role in inflammatory processes, although opinions differ as to which AngII-generating enzyme is primarily associated with AngII-mediated effects. ACE inhibitors have been shown to have a protective or healing effect on gastric ulcers and colitis in animal models, which could be related to the local expression of ACE.

METHODS

The localisation of ACE and CMA1 was examined immunohistochemically in Helicobacter pylori gastritis, non-H. pylori gastritis, gastric ulcers and non-lesional gastric tissues. Using real-time qRT-PCR, ACE- and CMA1-mRNA expression in gastric cell lines were examined and changes in ACE levels after exposure to H. pylori or cytokines (IL-1beta, IL-6, IL-8, TNF, TGFbeta1) were quantified.

RESULTS

ACE and CMA1 were not expressed in the non-lesional foveolar epithelium. Cytoplasmic staining for ACE in fundic chief cells, and apical membranous expression of ACE in the mucin-secreting cells of the antral and pyloric region was observed. ACE was found in endothelial cells of the gastric ulcer granulation tissue and CMA1 was strongly expressed in mast cells. ACE but not CMA1 was expressed in the MKN28, N87 and MKN45 gastric cell lines, and ACE mRNA expression was regulated by both H. pylori and the cytokines.

CONCLUSIONS

ACE in the gastric mucosa and the microvasculature of granulation tissue may represent a novel therapeutic target for the promotion of healing processes in gastritis and ulceration using ACE inhibitors or AT1R antagonists.

Serum levels of high-sensitivity C-reactive protein (hs-CRP)in Helicobacter pylori-infected peptic ulcer patients and its association with bacterial CagA virulence factor

OBJECTIVE

CRP is a marker of inflammation and infection of the gastric mucosa with Helicobacter pylori, which causes an inflammatory reaction. It has been reported that CagA(+) H. pylori strains induce more severe gastric inflammation and are also associated with higher risks of peptic ulcer and gastric cancer. The purpose of this study was to compare serum concentrations of hs-CRP in H. pylori-infected peptic ulcer (PU) patients, H. pylori infected asymptomatic (AS) carriers, and a healthy control group, and their association with bacterial virulence factor CagA.

MATERIAL AND METHODS

A total of 60 H. pylori infected PU patients (30 patients were positive for anti-CagA antibody and 30 were negative for anti-CagA antibody), 53 H. pylori-infected AS carriers (25 subjects were positive for anti-CagA antibody and 28 were negative for anti-CagA antibody), and 22 healthy H. pylori-negative subjects (as a control group) were enrolled in the study. Serum concentrations of hs-CRP were measured by use of an ELISA method.

RESULTS

The mean serum level of hs-CRP in all PU patients (124.9±32.4 μg/dl) was significantly higher than that in all AS subjects (18.6±2.6 μg/dl; P<0.001) and the healthy uninfected control group (10.7±2.9 μg/dl; P<0.0001). Moreover, the mean serum level of hs-CRP in the AS group was significantly higher than that observed in the uninfected control group (P<0.04). No significant difference was observed between mean serum levels of hs-CRP of PU patients with positive test for anti-CagA antibody (132.6±49.4 μg/dl) and PU patients with negative test for anti-CagA antibody (117.1±42.9 μg/dl). Moreover, mean serum levels of hs-CRP were similar in AS subjects with positive test for anti-CagA (18.4±3.1 μg/dl) and in those who were negative for anti-CagA antibody (18.9±4.1 μg/dl).

CONCLUSION

The results of this study showed that mean serum concentrations of hs-CRP in PU patients and in H. pylori infected AS carriers were higher than in a healthy control group. Although H. pylori infection is associated with higher serum levels of hs-CRP, serum concentrations of this inflammatory marker were not affected by expression of bacterial CagA virulence factor.

Genetic variation in immune regulation and DNA repair pathways and stomach cancer in China

The incidence of stomach cancer is high in certain parts of the world, particularly in China. Chronic Helicobacter pylori infection is the main risk factor, yet the vast majority of infected individuals remain unaffected with cancer, suggesting an important role of other risk factors. We conducted a population-based case-control study including 196 incident stomach cancer cases and 397 matched controls to test the hypothesis that adverse single nucleotide polymorphism (SNP) genotypes and haplotypes within genes of the DNA repair and immune regulatory pathways are associated with increased stomach cancer risk. Genomic DNA isolated from blood samples was used for genotyping, and results were obtained for 57 putatively functional SNPs in 28 genes. Odds ratios (OR) and 95% confidence intervals (95% CI) were obtained from adjusted logistic regression models. For PTGS2, a gene involved in the inflammatory response, associations with stomach cancer risk were observed for TC genotype carriers of rs5279 (OR, 0.24; 95% CI, 0.08-0.73), CT genotype carriers of the 3'-untranslated region SNP rs689470 (OR, 7.49; 95% CI, 1.21-46.20), and CTTC haplotype carriers of rs5277, rs5278, rs5279, and rs689470 (OR, 0.41; 95% CI, 0.18-0.95). For ERCC5, a gene involved in nucleotide excision repair, TC genotype carriers of rs1047768 (OR, 0.65; 95% CI, 0.41-1.03), GC genotype carriers of the nonsynonymous SNP rs2227869 (OR, 0.30; 95% CI, 0.13-0.67), and CCG haplotype carriers of rs1047768, rs17655, and rs2227869 (OR, 0.45; 95% CI, 0.20-1.04) were associated with reduced stomach cancer risk. In conclusion, PTGS2 and ERCC5 were associated with stomach cancer risk in a Chinese population.

The role of heparan sulfate on adhesion of 47 and 51 kDa outer membrane proteins ofHelicobacter pylorito gastric cancer cellsThis study was done in memory of the late Dr. Roberto Carlos Vazquez-Juarez

Helicobacter pylori is a common gastrointestinal pathogenic bacterium in humans and the usual preference for the stomach’s outer membrane proteins (OMPs) are antigens involved in the adhesion process. Through SDS–PAGE and blotting analyses, using horseradish peroxidase-labeled heparan sulfate (HRP-HS) as a probe, we identified H. pylori OMPs with affinity for heparan sulfate (OMP-HS). Biotin–streptavidin bacterial-adhesion assay was used to evaluate participation of OMP-HS in the adhesion of H. pylori to semi-confluent HeLa S3 and Kato III cell monolayers. The results provide evidence that induction of antibodies against 2 OMP-HSs (HSBP-47 and HSBP-51) could reduce binding of H. pylori to both cell lines and induce detachment of cell-bound bacteria from infected cultured cells.

Expression of Helicobacter pylori virulence factors and associated expression profiles of inflammatory genes in the human gastric mucosa

Helicobacter pylori virulence factors have been suggested to be important in determining the outcome of infection. The H. pylori adhesion protein BabA2 is thought to play a crucial role in bacterial colonization and in induction of severe gastric inflammation, particularly in combination with expression of CagA and VacA. However, the influence of these virulence factors on the pathogenesis of H. pylori infection is still poorly understood. To address this question, the inflammatory gene expression profiles for two groups of patients infected with triple-negative strains (lacking expression of cagA, babA2, and vacAs1 but expressing vacAs2) and triple-positive strains (expressing cagA, vacAs1, and babA2 but lacking expression of vacAs2) were investigated. The gene expression patterns in the antrum gastric mucosa from patients infected with different H. pylori strains were very similar, and no differentially expressed genes could be identified by pairwise comparisons. Our data thus suggest that there is a lack of correlation between the host inflammatory responses in the gastric mucosa and expression of the babA2, cagA, and vacAs1 genes.

No correlation of babA2 with vacA and cagA genotypes of Helicobacter pylori and grading of gastritis from peptic ulcer disease patients in Brazil

BACKGROUND

The babA2 gene, which encodes a blood-group antigen-binding adhesin that mediates attachment of Helicobacter pylori to human Lewis(b) antigens on gastric epithelial cells, has been associated with a higher risk of peptic ulcer and gastric cancer. The purpose of this study was to ascertain the frequency of babA2 genotype in H. pylori strains of patients with peptic ulcer and to correlate with other virulence factors.

MATERIALS AND METHODS

vacA, cagA, and babA2 genotypes of H. pylori were determined by using polymerase chain reaction (PCR). DNA was extracted from positive urease test gastric samples of 150 patients with peptic ulcer. Antrum and corpus biopsies were taken for histologic examination according to the updated Sydney system classification.

RESULTS

babA2 genotype was present in 104 (69.3%) and cagA in 113 (75.3%) gastric samples. No significant correlation was observed between babA2 and vacAs1 genotype or between babA2 and cagA status. The correlation of vacAs1 genotype with positive cagA was statistically significant ( p < .001). The babA2-positive strain was more frequently found from the gastric samples of men, than of women (p = .01). Strains harboring cagA, vacAs1, and babA2 genotypes had no association to the grading of gastritis, presence of glandular atrophy, or intestinal metaplasia. The simultaneous presence of cagA, vacAs1, and babA2 was found in 32.6% of the H. pylori strains.

CONCLUSIONS

babA2 genotype is frequently found in H. pylori strains from peptic ulcer disease in Brazil, although it has no significant correlation to the worsening of the gastritis and to other virulence markers such as vacAs1 and cagA.