Contribution of HLA-DQA gene to host's response against Helicobacter pylori

Designing and development of multi-epitope chimeric vaccine against Helicobacter pylori by exploring its entire immunogenic epitopes: an immunoinformatic approach

BACKGROUND

Helicobacter pylori is a prominent causative agent of gastric ulceration, gastric adenocarcinoma and gastric lymphoma and have been categorised as a group 1 carcinogen by WHO. The treatment of H. pylori with proton pump inhibitors and antibiotics is effective but also leads to increased antibiotic resistance, patient dissatisfaction, and chances of reinfection. Therefore, an effective vaccine remains the most suitable prophylactic option for mass administration against this infection.

RESULTS

We modelled a multi-chimera subunit vaccine candidate against H. pylori by screening its secretory/outer membrane proteins. We identified B-cell, MHC-II and IFN-γ-inducing epitopes within these proteins. The population coverage, antigenicity, physiochemical properties and secondary structure were evaluated using different in-silico tools, which showed it can be a good and effective vaccine candidate. The 3-D construct was predicted, refined, validated and docked with TLRs. Finally, we performed the molecular docking/simulation and immune simulation studies to validate the stability of interaction and in-silico cloned the epitope sequences into a pET28b(+) plasmid vector.

CONCLUSION

The multiepitope-constructed vaccine contains T- cells, B-cells along with IFN-γ inducing epitopes that have the property to generate good cell-mediated immunity and humoral response. This vaccine can protect most of the world's population. The docking study and immune simulation revealed a good binding with TLRs and cell-mediated and humoral immune responses, respectively. Overall, we attempted to design a multiepitope vaccine and expect this vaccine will show an encouraging result against H. pylori infection in in-vivo use.

Helicobacter pylori and Respiratory Diseases: 2021 Update

Helicobacter pylori (H. pylori) is a Gram-negative bacterium involved in the development of gastritis, peptic ulcer disease, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue. Unexplained iron deficiency anemia, idiopathic thrombocytopenic purpura and vitamin B12 deficiency have also been related to H. pylori infection, whereas for other extra-gastric diseases, the debate is still open. In this review, we evaluate and discuss the potential involvement of H. pylori infection in the pathogenesis of several respiratory diseases. A MEDLINE search of all studies published in English from 1965 to 2021 was carried out. Controversial findings have been reported in patients with bronchial asthma, chronic obstructive pulmonary disease, bronchiectasis, lung cancer, tuberculosis, cystic fibrosis, and sarcoidosis. Most of the available literature is concerned with case-control studies based on seroprevalence, with a small sample size and low consideration of confounders, which represents a potential issue. So far, there is no clear evidence of a causal association between H. pylori infection and respiratory diseases, and larger studies with appropriate epidemiological design are required.

A large-scale investigation into the role of classical HLA loci in multiple types of severe infections, with a focus on overlaps with autoimmune and mental disorders

Background

Infections are a major disease burden worldwide. While they are caused by external pathogens, host genetics also plays a part in susceptibility to infections. Past studies have reported diverse associations between human leukocyte antigen (HLA) alleles and infections, but many were limited by small sample sizes and/or focused on only one infection.

Methods

We performed an immunogenetic association study examining 13 categories of severe infection (bacterial, viral, central nervous system, gastrointestinal, genital, hepatitis, otitis, pregnancy-related, respiratory, sepsis, skin infection, urological and other infections), as well as a phenotype for having any infection, and seven classical HLA loci (HLA-A, B, C, DPB1, DQA1, DQB1 and DRB1). Additionally, we examined associations between infections and specific alleles highlighted in our previous studies of psychiatric disorders and autoimmune disease, as these conditions are known to be linked to infections.

Results

Associations between HLA loci and infections were generally not strong. Highlighted associations included associations between DQB1*0302 and DQB1*0604 and viral infections (P = 0.002835 and P = 0.014332, respectively), DQB1*0503 and sepsis (P = 0.006053), and DQA1*0301 with “other” infections (a category which includes infections not included in our main categories e.g. protozoan infections) (P = 0.000369). Some HLA alleles implicated in autoimmune diseases showed association with susceptibility to infections, but the latter associations were generally weaker, or with opposite trends (in the case of HLA-C alleles, but not with alleles of HLA class II genes). HLA alleles associated with psychiatric disorders did not show association with susceptibility to infections.

Conclusions

Our results suggest that classical HLA alleles do not play a large role in the etiology of severe infections. The discordant association trends with autoimmune disease for some alleles could contribute to mechanistic theories of disease etiology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-02888-1.

Flavodoxins as Novel Therapeutic Targets against Helicobacter pylori and Other Gastric Pathogens

Flavodoxins are small soluble electron transfer proteins widely present in bacteria and absent in vertebrates. Flavodoxins participate in different metabolic pathways and, in some bacteria, they have been shown to be essential proteins representing promising therapeutic targets to fight bacterial infections. Using purified flavodoxin and chemical libraries, leads can be identified that block flavodoxin function and act as bactericidal molecules, as it has been demonstrated for Helicobacter pylori (Hp), the most prevalent human gastric pathogen. Increasing antimicrobial resistance by this bacterium has led current therapies to lose effectiveness, so alternative treatments are urgently required. Here, we summarize, with a focus on flavodoxin, opportunities for pharmacological intervention offered by the potential protein targets described for this bacterium and provide information on other gastrointestinal pathogens and also on bacteria from the gut microbiota that contain flavodoxin. The process of discovery and development of novel antimicrobials specific for Hp flavodoxin that is being carried out in our group is explained, as it can be extrapolated to the discovery of inhibitors specific for other gastric pathogens. The high specificity for Hp of the antimicrobials developed may be of help to reduce damage to the gut microbiota and to slow down the development of resistant Hp mutants.

HLA-DQB1*03 genotype and perioperative blood transfusion are not conducive to the prognosis of patients with gastric cancer

BACKGROUND

Gastric cancer (GC) is a disease associated with a higher incidence and mortality, and some host genetic polymorphisms have been reported as potential factors contributing to the development of GC. In view of this, the study was conducted to investigate the effects of HLA-DQB1 gene polymorphisms and perioperative blood transfusion on prognosis of patients with gastric cancer (GC).

METHODS

A total of 142 patients with GC (case group) and 150 healthy controls (control group) were enrolled. Relationship between HLA-DQB1 gene polymorphisms, perioperative blood transfusion, and clinical pathological parameters of patients with GC after operation was analyzed. Kaplan-Meier curve was applied for analyzing survival rate of patients with GC, and Cox multivariate regression analysis for prognostic factors of patients with GC.

RESULTS

The frequency of HLA-DQB1*03 gene was increased in patients with GC. Patients with GC with HLA-DQB1*03 genotype had higher number of tumor size >6 cm, deeper depth of infiltration, higher LNM rate, and later stage of disease. Patients with HLA-DQB1*03 genotype had lower survival rate compared with other genotypes. Anemia before operation, depth of infiltration in T3 stage and T4 stage, LNM in N1 stage and N2 stage, and HLA-DQB1*03 genotype were regarded as independent risk factors for patients with GC.

CONCLUSION

These results demonstrate that HLA-DQB1*03 genotype and perioperative blood transfusion are not conducive to the prognosis of patients with GC, which could provide a reference for the treatment of GC.

Ethnic/racial differences in gastrointestinal symptoms and diagnosis associated with the risk of Helicobacter pylori infection in the US

Background

In the US, neither the prevalence nor the gastrointestinal (GI) diagnosis/symptoms associated with Helicobacter pylori (HP) have been examined in different racial/ethnic groups.

Aim

To determine the racial/ethnic differences in HP infection associated with GI diagnoses/symptoms using the Cerner Health Facts^® database.

Methods

This cross-sectional study collected data during the period of 2000–2015 from the following ethnic/racial groups: 8,236,317 white, 2,085,389 black, 426,622 Hispanic, 293,156 Asian Pacific/Islander (APIs), and 89,179 Native American/Alaskan Native (NA/AN) patients aged 21–65 years old; the data were then analyzed. The primary dependent variable was a diagnosis of HP (ICD-9-Clinical Modification/ICD-10 classification). SAS version 9.4 was used for the statistical analysis. The statistical analysis was performed on 11,130,663 patients with GI symptoms, and of these, 152,086 patients were positive for the infection.

Results

Hispanics and NA/ANs had the highest prevalence of HP associated with upper GI symptoms/diagnosis. Nevertheless, blacks and APIs presented the highest relative risk (RR) of HP associated with dyspepsia (RR [95% CI] =11.2 [10.7–11.9] and 14.2 [12.8–15.6]), peptic ulcer (RR =13.8 [13.3–14.5] and 10.7 [9.3–12.3]), and atrophic gastritis (RR =9 [8.5–9.6] and 7.4 [6.4–8.5]), respectively. In all racial/ethnic groups, HP was also associated with inflammatory bowel diseases, liver diseases, and celiac diseases.

Conclusion

Black and API populations had the highest risk of HP associated with upper GI symptoms/diagnosis. Black patients also had the highest risk for HP associated with GI cancer.

Helicobacter pylori infection and light chain gammopathy

Objective. Helicobacter pylori provokes a host of immune alterations upon colonizing the gastric mucosa. Design. We report 22 individuals with confirmed Helicobacter pylori infection who were also managed for the concurrent elevation of immunoglobulin free light chain (kappa and lambda) levels. Result. Of the 22 patients, 15 patients (68.2%) had elevated free light chain levels: 6 patients (40%) had only kappa chain elevation, 2 patients (13.3%) had only lambda chain elevation, and 7 patients (46.7%) had both kappa and lambda chain elevation. Twenty out of the 22 patients (90.9%) were microbiologically confirmed cured with 3 patients being lost to follow-up for repeat levels. Of the 3 patients who were lost to follow-up, 1 patient had only kappa chain elevation, 1 patient had only lambda chain elevation, and 1 patient had both kappa and lambda chain elevation. For those who were cured (19 patients), 5 patients with kappa elevation had normalized values, 4 patients with lambda elevation had normalized values, and 2 patients with combined kappa and lambda elevation had normalized values. For 6 out of the 19 patients, the light chain levels remained elevated. Conclusion. We speculate that the Helicobacter pylori infection disrupts the immunoglobulin system with potential implications being discussed below.

Low rate of recurrence of Helicobacter pylori infection in spite of high clarithromycin resistance in Pakistan

BACKGROUND

The aim was to investigate the reinfection rate of H. pylori during a follow-up period of 12 months in adults who had undergone eradication therapy.

METHODS

One hundred-twenty patients; 116 with gastritis, 3 with duodenal ulcer and 1 gastric ulcer, were studied. Their mean age was 41±13 years (range 18-77) and male: female ratio of 2:1. H. pylori were cultured and antibiotic sensitivity was determined by Epsilometer test (E-test) for clarithromycin (CLR) and amoxicillin (AMX). Primers of urease C gene of H. pylori and Sau-3 and Hha I restriction enzymes were used for polymerase chain reaction-restriction fragment length polymorphism analysis (PCR-RFLP). 14C urea breath test (14C-UBT) was performed 4 weeks after the eradication therapy. The successfully treated patients were observed for 12 months with 14C-UBT to assess H. pylori status. If 14C-UBT was negative, it was repeated after every 12 weeks. If 14C-UBT was positive, endoscopy was repeated with biopsies.

RESULT

The eradication therapy was successful in 102(85%) patients. Out of forty-seven H. pylori isolates cultured, clarithromycin sensitivity was present in 30(64%) and amoxicillin in 45(98%), respectively. Follow-up 14C-urea breath tests of all 102 patients who eradicated H. pylori remained negative up to 9 months. However, in 6 patients, the 14C-UBT confirmed recurrence at 12 months. The recurrence rate was 6%.

CONCLUSION

A low rate of recurrence of H. pylori infection was found in patients with dyspeptic symptoms. H. pylori isolates demonstrated a high invitro clarithromycin resistance.

Suppressed Gastric Mucosal TGF-beta1 Increases Susceptibility to H. pylori-Induced Gastric Inflammation and Ulceration: A Stupid Host Defense Response

BACKGROUND/AIMS

Loss of transforming growth factor beta1 (TGF-beta1) exhibits a similar pathology to that seen in a subset of individuals infected with Helicobacter pylori, including propagated gastric inflammation, oxidative stress, and autoimmune features. We thus hypothesized that gastric mucosal TGF-beta1 levels could be used to determine the outcome after H. pylori infection.

METHODS

Northern blot for the TGF-beta1 transcript, staining of TGF-beta1 expression, luciferase reporter assay, and enzyme-linked immunosorbent assay for TGF-beta1 levels were performed at different times after H. pylori infection.

RESULTS

The TGF-beta1 level was markedly lower in patients with H. pylori-induced gastritis than in patients with a similar degree of gastritis induced by nonsteroidal anti-inflammatory drugs. There was a significant negative correlation between the severity of inflammation and gastric mucosal TGF-beta1 levels. SNU-16 cells showing intact TGF-beta signaling exhibited a marked decrease in TGF-beta1 expression, whereas SNU-638 cells defective in TGF-beta signaling exhibited no such decrease after H. pylori infection. The decreased expressions of TGF-beta1 in SNU-16 cells recovered to normal after 24 hr of H. pylori infection, but lasted very spatial times, suggesting that attenuated expression of TGF-beta1 is a host defense mechanism to avoid attachment of H. pylori.

CONCLUSIONS

H. pylori infection was associated with depressed gastric mucosal TGF-beta1 for up to 24 hr, but this apparent strategy for rescuing cells from H. pylori attachment exacerbated the gastric inflammation.

Peptic ulcer disease

Peptic ulcer disease had a tremendous effect on morbidity and mortality until the last decades of the 20th century, when epidemiological trends started to point to an impressive fall in its incidence. Two important developments are associated with the decrease in rates of peptic ulcer disease: the discovery of effective and potent acid suppressants, and of Helicobacter pylori. With the discovery of H pylori infection, the causes, pathogenesis, and treatment of peptic ulcer disease have been rewritten. We focus on this revolution of understanding and management of peptic ulcer disease over the past 25 years. Despite substantial advances, this disease remains an important clinical problem, largely because of the increasingly widespread use of non-steroidal anti-inflammatory drugs (NSAIDs) and low-dose aspirin. We discuss the role of these agents in the causes of ulcer disease and therapeutic and preventive strategies for drug-induced ulcers. The rare but increasingly problematic H pylori-negative NSAID-negative ulcer is also examined.

Review article: 'true' re-infection of Helicobacter pylori after successful eradication--worldwide annual rates, risk factors and clinical implications

BACKGROUND

The incidence of 'true' re-infection with Helicobacter pylori after successful eradication remains uncertain.

AIM

To determine the worldwide rates, risk factors and clinical implications of 'true' re-infection of Helicobacter pylori. 'True' re-infection of H. pylori is defined as the situation where tests for H. pylori infection, which were negative for 12 months after eradication, become positive again at a later stage.

RESULTS

Thirty six studies were identified through a literature search to be able to produce annual rates of 'true' re-infection, and data from 33 original articles were considered reliable and adequate in the further review. Generally, the reported rates varied from 0% to 23.4% in adults and from 1.9% to 9.6% in children. Most studies from developed countries reported rates of less than 1%, whereas relatively higher rates were reported in most of the developing countries. Small sample sizes included in the studies appeared to be associated with increased re-infection rates. Interfamilial transmission is the major cause of re-infection, although iatrogenic re-infection through contaminated endoscopic equipment has been reported.

CONCLUSION

Helicobacter pylori re-infection is not a concern in a clinical setting, especially in the developed world; however, caution must be exercised in most developing countries.

Advance in research of genes associated with peptic ulcer

At present, studies about peptic ulcer have developed from cellular level to molecular level. More and more genes associated with peptic ulcer have been discovered, including human leukocyte antigen (HLA) genes, epidermal growth factor (EGF) genes, apoptosis-associated genes, calcitonin genes and trefoil peptide genes. These genes play important roles in the development and healing of peptic ulcer, providing theoretical basis for clinical diagnosis and cure of peptic ulcer.

Role of the HLA-DQ locus in the development of chronic gastritis and gastric carcinoma in Mexican patients

AIM: To determine the HLA-DQ locus in Mexican patients with Chronic gastritis and gastric adenocarcinoma.

METHODS: Oligotyping for HLA-DQ locus was performed in 45 Mexican patients with chronic gastritis and 13 Mexican patients with diffuse-type gastric adenocarcinoma, and was then compared with 99 clinically healthy unrelated individuals. H pylori infection and CagA status were assessed in patients by enzyme-linked immunosorbent assay (ELISA) method.

RESULTS: We found a significant increased frequency of HLA-DQB1*0401 allele in H pylori-positive patients with chronic gastritis when compared with healthy subjects [19 vs 0%, P = 1 × 10^-7, odds ratio (OR) = 4.96; 95% confidence interval (95% CI), 3.87-6.35]. We also found a significant increased frequency of HLA-DQB1*0501 in patients with diffuse-type gastric carcinoma in comparison with healthy individuals (P = 1 × 10^-6, OR = 13.07; 95% CI, 2.82-85.14).

CONCLUSION: HLA-DQ locus may play a different role in the development of H pylori-related chronic gastritis and diffuse-type gastric adenocarcinoma in the Mexican Mestizo population.

Helicobacter pylori infection as a possible risk factor for respiratory system disease: a review of the literature

Helicobacter pylori (HP) infection may cause extradigestive manifestations directly or indirectly, by potential mechanisms. HP infection triggers a marked local inflammatory response and a chronic systemic immune response. Some of the mediators that are thought to be possibly involved in the pathogenesis of extradigestive diseases caused by HP infection include IL-1, TNF-alpha, interferon (IFN)-gamma, leukotriene C4 and platelet-activating factor. Previous epidemiological and serological case control studies have revealed that HP infection might have a role in the development of chronic bronchitis, bronchiectasis, lung cancer and tuberculosis. However HP infection does not appear to have a role in the development of bronchial asthma. Considering the importance and prevalence of respiratory system diseases, it may be time to conduct well-designed sets of studies to clarify whether there is an association with HP infection and respiratory system diseases, and to answer questions that have been posed regarding the patterns of histology, genotypes of HP, and the effects of eradication therapy. The aim of this review was to analyze the possible association between HP and respiratory disease and provide a critical review of the relevant literature.

Respiratory diseases and Helicobacter pylori infection: is there a link?

Recent studies suggest an epidemiological association between Helicobacter pylori infection and several extra-gastroduodenal pathologies, including cardiovascular, rheumatic, skin and liver diseases. The observed associations might be explained by a role of H. pylori infection in the pathogenesis of certain extra-digestive disorders, as a variety of inflammatory mediators are activated by H. pylori infection. The present review summarizes the current literature, including our own studies, concerning the association between respiratory diseases and H. pylori infection. A small number of epidemiological and serologic case-control studies suggest that patients with chronic obstructive pulmonary disease have an increased seroprevalence of H. pylori. A frequent coexistence of bronchiectasis and H. pylori infection has also been found. Moreover, recent studies have shown an increased prevalence of H. pylori infection in patients with pulmonary tuberculosis and in those with lung cancer. On the other hand, bronchial asthma does not seem to be related to H. pylori infection. At present, there is no definite proof of a causal relationship between H. pylori and respiratory diseases. The primary evidence rests on case-control studies, concerning relatively small numbers of patients. Future studies should be large enough for moderate-sized effects to be assessed or registered reliably. The activation of inflammatory mediators by H. pylori infection might be the pathogenetic mechanism underlying the observed associations. Therefore, the role of genetic predisposition of the infected host, the presence of strain-specific virulence factors and the serum concentration of proinflammatory markers in H. pylori-infected patients with respiratory diseases need further evaluation.

Preservation of gastric acid secretion may be important for the development of gastroesophageal junction adenocarcinoma in Japanese people, irrespective of the H. pylori infection status

BACKGROUND

We have previously reported that Helicobacter pylori infection prevents reflux esophagitis (RE) and Barrett's esophagus (BE) by decreasing gastric acid secretion. Gastroesophageal (GE) junction adenocarcinoma, including Barrett's adenocarcinoma, has been thought to be a complication of gastroesophageal reflux disease (GERD). However, the relationship between H. pylori infection, gastric acid secretion, and GE junction adenocarcinoma has not yet been investigated in Japan. The aim of this study was to evaluate this relationship in the Japanese population.

METHODS

A total of 168 Japanese patients (RE alone: 80, short-segment BE (SSBE): 16, long-segment BE (LSBE): 20, GE junction adenocarcinoma: 12, distal early gastric cancer (EGC): 40; male/female = 106/62; mean age 61.5 yr) and 80 Japanese control subjects who had no localized lesions in the upper gastrointestinal tract (male/female = 43/37, mean age 58.1 yr) were enrolled for this study. The prevalence of H. pylori infection was determined by biopsy, the rapid urease test, and measurement of the serum H. pylori IgG antibody. Gastric acid secretion was assessed by the endoscopic gastrin test (EGT). RE was diagnosed according to the Los Angeles classification.

RESULTS

The prevalence of H. pylori infection in the patients with RE alone (30%) was significantly lower than that in control subjects (71.2%). There was also a tendency for the prevalence of H. pylori infection to be lower in patients with BE (SSBE, 18.7%; LSBE, 0%) when compared to that in patients with RE alone. On the other hand, while the prevalence of H. pylori infection in patients with GE junction adenocarcinoma (58.3%) was significantly lower than that in patients with EGC (87.5%), it tended to be higher than that in patients with RE alone or BE. The mean EGT value in patients with RE alone (3.74 mEq/10 min) was significantly higher than that in control subjects (1.83). The mean EGT value in patients with BE (SSBE, 4.74; LSBE, 4.76) tended to be even higher than that in patients with RE alone. The mean EGT value in patients with GE junction adenocarcinoma (3.94) was significantly higher than that in control subjects and patients with EGC (0.67), but it was comparable to that independent of the H. pylori infection status in patients with RE alone or BE.

CONCLUSION

Preservation of gastric acid secretion may be important for the development of GE junction adenocarcinoma in Japanese people, irrespective of the H. pylori infection status.

HLA-DQB1 locus and gastric cancer in Helicobacter pylori infection

BACKGROUND AND AIMS

It has been suggested that the incidence of digestive diseases associated with Helicobacter pylori is influenced by the strain diversity of H. pylori, factors involving the host or environment, and the duration of infection. The authors have previously reported that human leukocyte antigen (HLA)-DQB1*0401 plays an important role in the development of atrophic gastritis in H. pylori infected patients. The aim of the present study was to investigate the relationship between HLA-DQB1 genotype and cancer development.

METHODS

HLA-DQB1 genotyping was performed by the PCR-RFLP method on 122 H. pylori-infected non-ulcer dyspepsia (NUD) patients, 53 gastric cancer patients and 28 uninfected controls. To reliably estimate the grade of atrophic gastritis, histological evaluation was performed.

RESULTS

The allele frequency of DQB1*0401 was significantly higher in intestinal type cancer patients compared with age- and sex-matched H. pylori-infected NUD patients. There was no significant difference in the mean atrophic scores of the biopsy samples from the lesser curvature of the mid-corpus between these groups.

CONCLUSIONS

HLA-DQB1*0401 is a useful marker for determining susceptibility to intestinal type gastric cancer.

Implications of anti-parietal cell antibodies and anti-Helicobacter pylori antibodies in histological gastritis and patient outcome

AIM

To develop a serum or histological marker for early discovery of gastric atrophy or intestinal metaplasia.

METHODS

This study enrolled 44 patients with gastric adenocarcinoma, 52 patients with duodenal ulcer, 14 patients with gastric ulcer and 42 consecutive healthy adults as controls. Each patient received an endoscopy and five biopsy samples were obtained. The degrees of histological parameters of gastritis were categorized following the Updated Sydney System. Anti-parietal cell antibodies (APCA) and anti-Helicobacter pylori (H pylori) antibodies (AHPA) were analyzed by immunoassays. H pylori infection was diagnosed by rapid urease test and histological examination.

RESULTS

Patients with gastric cancer and gastric ulcer are significantly older than healthy subjects, while also displaying higher frequency of APCA than healthy controls. Patients with positive APCA showed higher scores in gastric atrophy and intestinal metaplasia of corpus than patients with negative APCA. Patients with positive AHPA had higher scores in gastric atrophy, intestinal metaplasia, and gastric inflammation of antrum than those patients with negative AHPA. Elderly patients had greater prevalence rates of APCA. Following multivariant logistic regression analysis, the only significant risk factor for antral atrophy is positive AHPA, while that for corpus atrophy is positive APCA.

CONCLUSION

The existence of positive APCA correlates with glandular atrophy in corpus and the presence of positive AHPA correlates with glandular atrophy in antrum. The existence of serum APCA and AHPA betokens glandular atrophy and requires further examination for gastric cancer.

The prevalence of Helicobacter pylori infection and the status of gastric acid secretion in patients with Barrett's esophagus in Japan

OBJECTIVES

The acidity of the refluxate into the esophagus is a key factor for the pathogenesis of gastroesophageal reflux disease. Helicobacter pylori (H. pylori) infection can influence gastric acid secretion. We have reported that H. pylori infection prevents reflux esophagitis by decreasing gastric acid secretion in Japanese patients, but the role of this organism in Barrett's esophagus is unclear. The aim of this study was to investigate the prevalence of H. pylori infection and gastric acid secretion in Japanese patients with reflux esophagitis with or without Barrett's esophagus.

METHODS

We enrolled 112 reflux esophagitis patients who were examined for the status of H. pylori and acid secretion in this study. They were divided into three groups, according to the presence or absence of Barrett's esophagus as follows: reflux esophagitis group without Barrett's esophagus (reflux esophagitis alone) (80 patients); short-segment Barrett's esophagus group (16 patients); and long-segment Barrett's esophagus group (LSBE) (16 patients). Age- and sex-matched control subjects were also assigned to the 80 patients with reflux esophagitis alone. The prevalence of H. pylori infection was determined by histology, rapid urease tests, and serum IgG antibodies. Gastric acid secretion was evaluated by the endoscopic gastrin test (EGT).

RESULTS

The overall prevalence of H. pylori infection in the reflux esophagitis patient group (24.1%) was significantly lower than the control group (71.2%) (odds ratio 0.13, 95% confidence interval 0.07-0.24; p < 0.0001). The prevalence of H. pylori infection in the patients with Barrett's esophagus tended to be lower than that in the patients with reflux esophagitis alone (reflux esophagitis alone; 30.0%, SSBE; 18.7%, LSBE; 0%), especially in the patients with LSBE compared with the reflux esophagitis alone group (p < 0.01). The EGT value of the respective reflux esophagitis patient group was significantly higher than the control group. The EGT value in the patients with Barrett's esophagus tended to be higher than that in the patients with reflux esophagitis alone, but the difference was not statistically significant. When examined in H. pylori-negative subjects, no difference was found in the EGT value between the control subjects and the patients with reflux esophagitis alone, but it was significantly higher in patients with Barrett's esophagus than the control subjects (p < 0.05). On the other hand, when examined in the H. pylori-positive subjects, the EGT value was significantly higher in the patients with reflux esophagitis alone than in the control subjects (p < 0.01).

CONCLUSIONS

H. pylori infection may play a protective role in the development of Barrett's esophagus, especially in the development of LSBE in Japan. Gastric acid hypersecretion may be concerned with the development of Barrett's esophagus in addition to the absence of H. pylori infection.

Human leukocyte antigen class II genes and Helicobacter pylori infection: does genotype overwhelm environmental exposure?

OBJECTIVE

We investigated associations between human leukocyte antigen class II genes, environmental exposures, and Helicobacter pylori infection.

METHODS

Sixty-eight subjects with histologically confirmed H. pylori and intestinal metaplasia (cases) and 70 healthy subjects without H. pylori (controls) matched for age, sex, and year of birth were included in this study. All patients answered a detailed questionnaire designed to collect sociodemographic characteristics, smoking, alcohol drinking, and dietary habits. Human leukocyte antigen class II genes were typed with genomic DNA. The cytotoxins CagA and VacA were investigated with serology. Odds ratios and corresponding 95% confidence intervals were estimated from multivariate conditional logistic regression. Multiple correspondence analysis was used to represent the interrelationships of a multiple contingency table.

RESULTS

Human leukocyte antigen DRB1, DQA1, and DQB1 genotypes were not significantly associated with H. pylori infection and intestinal metaplasia. No significant association with blood group or Lewis antigen system was found. However, multiple correspondence analysis clearly associated H. pylori with environmental exposure: the control group largely consumed olive oil, fresh fruits, and vegetables and histories of never or formerly smoking and the case group (those positive for H. pylori and metaplasia) largely consumed eggs, meat and butter and had histories of smoking cigarettes.

CONCLUSIONS

These findings suggested that H. pylori infection is not influenced by a genetic compound and confirmed the relevance of environmental exposure.

Association of the HLA-DRB1 gene locus with gastric adenocarcinoma in Japan

BACKGROUND AND AIM

Helicobacter pylori infection is associated with gastric adenocarcinoma, however, the odds ratio is relatively low. The aim of the present study was to investigate host genetic factors that increase the risk of gastric adenocarcinoma among H. pylori-infected individuals.

METHODS

A total of 70 patients with early gastric adenocarcinoma and 121 unrelated healthy controls were examined for H. pylori infection and HLA-DRB1 genotyping. The frequencies of HLA-DRB1 alleles were compared among groups.

RESULTS

The allele frequency of DRB1*04051 was significantly higher in patients with gastric adenocarcinoma (17.9%) than in controls (7.9%) (P(correct) = 0.045). The odds ratio of gastric adenocarcinoma associated with the presence of the HLA-DRB1*04051 allele compared with its absence was 2.55 (95% confidence limits, 1.35-4.83). This genetic risk was not associated with H. pylori infection. There was no significant difference in the HLA-DRB1 allele frequency between H. pylori-positive and H. pylori-negative controls. The frequency of genotypes that possessed the DRB1*04051 allele in gastric adenocarcinoma patients (34.3%) was significantly higher than that in H. pylori-negative controls (11.9%) (p = 0.0089) and H. pylori-positive controls (15.2%) (p = 0.0066).

CONCLUSION

These findings suggest that immunogenetic factors for susceptibility to gastric adenocarcinoma are present in the host, the HLA-DRB1*04051 allele is a host genetic risk factor for gastric adenocarcinoma, and that this genetic risk is independent of H. pylori infection.

Platelet recovery in patients with idiopathic thrombocytopenic purpura after eradication of Helicobacter pylori

The relationship between Helicobacter pylori infection and idiopathic thrombocytopenic purpura (ITP) has been investigated in several studies. We investigated the prevalence of H. pylori infection and the clinical effects of eradication in 22 Japanese patients with chronic ITP. H. pylori infection was found in 14 (63.6%) of the patients by histologic and culture examinations of biopsy samples obtained by gastrointestinal endoscopy. H. pylori was eradicated by proton pump inhibitors and 2 kinds of antibiotics in 13 (92.9%) of the 14 patients in whom the results of treatment could be evaluated. Five (38.4%) of those 13 patients had platelet recovery (platelet count of more than 100 x 10(9)/L and an increase of more than 30 x 10(9)/L with respect to the baseline value) after eradication. The median follow-up period was 15 months. One patient who had a complete response had a partial relapse after cessation of prednisolone treatment without any evidence of H. pylori reinfection. Another patient, in whom H. pylori was not eradicated even after 2 treatment sessions, had a partial response after treatment. A screening examination for H. pylori infection may be necessary for Japanese patients with newly diagnosed ITP. Although the exact mechanism underlying platelet recovery after H. pylori eradication is not clear, the results of this study indicated that H. pylori eradication treatment is a good option for some patients with chronic ITP.

Helicobacter pylori infection and respiratory diseases: a review

In the past few years, a variety of extradigestive disorders, including cardiovascular, skin, rheumatic and liver diseases, have been associated with Helicobacter pylori (H. pylori) infection. The activation of inflammatory mediators by H. pylori seems to be the pathogenetic mechanism underlying the observed associations. The present review summarizes the current literature, including our own studies, concerning the association between H. pylori infection and respiratory diseases.

A small number of epidemiological and serologic, case-control studies suggest that H. pylori infection may be associated with the development of chronic bronchitis. A frequent coexistence of pulmonary tuberculosis and H. pylori infection has also been found. Moreover, recent studies have shown an increased H. pylori seroprevalence in patients with bronchiectasis and in those with lung cancer. On the other hand, bronchial asthma seems not to be related with H. pylori infection.

All associations between H. pylori infection and respiratory diseases are primarily based on case-control studies, concerning relatively small numbers of patients. Moreover, there is a lack of studies focused on the pathogenetic link between respiratory diseases and H. pylori infection. Therefore, we believe that larger studies should be undertaken to confirm the observed results and to clarify the underlying pathogenetic mechanisms.

Role of Helicobacter pylori infection among offspring or siblings of gastric cancer patients

A positive family history is an increased risk factor for gastric cancer within family members, and one of the possible causes of this is the intrafamilial clustering of Helicobacter pylori infection. Our study examined the prevalence of H. pylori infection, serum antibodies to CagA and VacA and atrophic gastritis and/or intestinal metaplasia in the offspring or siblings of gastric cancer patients. A total of 726 subjects included 300 relatives of 300 separate gastric cancer patients and 426 controls. All subjects underwent upper gastrointestinal endoscopic examination with a rapid urease test. Blood samples were obtained to test for the presence of serum antibodies to the CagA and VacA proteins of H. pylori. The prevalence of H. pylori infection was higher in relatives of cancer patients (75.3%) than in controls (60.1%), and the adjusted odds ratio was 2.1 (95% CI 1.5-2.9). When either siblings or 2 or more family members were gastric cancer patients, the prevalence of H. pylori infection was much higher compared to the prevalence in controls. There was no specific relationship between CagA and VacA, and H. pylori infection. Atrophic gastritis and/or intestinal metaplasia were more frequently found in H. pylori-infected relatives of cancer patients (26.1%) than in H. pylori-infected controls (12.9%). These results strongly support a role for H. pylori infection in familial aggregation of gastric cancer. The prophylactic eradication of H. pylori infection in the offspring or siblings of gastric cancer patients may be clinically beneficial.

[Epidemiological aspects of Helicobacter pylori infection in childhood and adolescence]

The scope of the review is to study the epidemiological aspects of Helicobacter pylori infection and its importance during childhood and adolescence, focusing on incidence, prevalence, transmission and risk factors. The study's references included the following databases: LILACS (PAHO/ Bireme), MEDLINE, the US's National Library of Medicine and the thesis developed at University of São Paulo for the period 1983 to 1999. It was noted that Helicobacter pylori infection is mainly acquired during childhood, age-related prevalence, main risk factors are associated to low socioeconomic status, and its transmission mechanism remains unclear.

Serological comparison of serum pepsinogen and anti-parietal cell antibody levels between Japanese and German patients

BACKGROUND

Atrophic gastritis is more common in Japan than in Germany. The expression of anti-parietal cell antibody has been implicated in the genesis of atrophic gastritis associated with Helicobacter pylori infection.

OBJECTIVE

We investigated the difference in serum levels of pepsinogens and in anti-parietal cell antibody expression between Japanese and German patients.

METHODS

We recruited 102 Japanese and 46 German patients with dyspepsia. Endoscopic examination detected no localized lesions in the upper gastrointestinal tract of any patients. Anti-parietal cell antibody was investigated by enzyme-linked immunosorbent assay with the purified porcine H+,K+-ATPase fraction and immunohistochemistry. H. pylori infection was diagnosed by the presence of anti-H. pylori antibody, by using the urease test and by histological examination. Serum levels of pepsinogen I and II and of gastrin were measured by a modified radioimmunoassay.

RESULTS

Seventy-one Japanese (70%) and 17 Germans (37%) were positive for H. pylori. Serum levels of anti-parietal cell antibody were not significantly different between Japanese and Germans in both H. pylori negative and positive groups. The serum pepsinogen I/II ratio and gastrin levels were altered by H. pylori infection in both populations. Moreover, anti-parietal cell antibody levels were higher in H. pylori-positive patients with low pepsinogen levels than in those with high pepsinogen levels in both populations.

CONCLUSIONS

The levels of anti-parietal cell antibody do not differ statistically between Japanese and Germans. Anti-parietal cell antibody might play a role in the progression of atrophic gastritis in both Japanese and German patients.

In the European population HLA-class II genes are not associated with Helicobacter pylori infection

OBJECTIVE

Genetic variability influences susceptibility to several diseases and depends on the specific ethnic background of individuals. HLA-class II genes have repeatedly been investigated as candidate genes for predisposition to Helicobacter pylori infection. Certain HLA-DQA1 alleles have been reported to be associated with gastric and duodenal ulcer disease in infected patients in the Japanese population. But conflicting results were reported on European and Japanese populations.

METHODS

HLA-DRB1 typing of 382 German individuals with well-defined H. pylori status and different clinical course of the disease was performed by polymerase chain reaction and allele-specific oligonucleotide hybridization.

RESULTS

No association with the infection status itself was observed in the German cohort. Similar results have been found in other European populations. In contrast, re-analysis of published data in a Japanese cohort revealed a highly significant association of DRB1*1501 with uninfected controls (P = 0.00035). In the German population, the carrier frequency of DRB1*15 was higher in H. pylori-positive individuals with gastric or duodenal ulcer but without statistical significance (gastric ulcer: odds ratio, 2.13; chi2 = 3.77; P = 0.05; Bonferroni correction, Pc = not significant; and duodenal ulcer: odds ratio, 2.15; chi2 = 3.4; P = 0.06; Pc = not significant). In infected individuals, autoantibodies to gastric mucosa were investigated, but no statistical significant difference in carrier frequencies of HLA-DRB1 alleles was evident.

CONCLUSION

The DRB1*1501-DQA1*01021-DQB1*0602 haplotype seems to provide protection from H. pylori infection in the Japanese population, whereas genetic variability in HLA-class II genes has only a minor impact on H. pylori infection and its clinical course in the European population.

Major histocompatibility complex class II polymorphisms in Macaca mulatta: factors influencing comprehensive genotyping of Macaca mulatta (Mamu)-DQA1 alleles by PCR-RFLP in archival samples

In the last 5 years, HLA class II genotyping methods have been adapted for genotyping of class II loci in rhesus macaques. Since previously published typing protocols were used on samples that were collected and stored under ideal conditions, it was of interest to determine if these methods were adequate for genotyping a large collection of archival samples from which DNA had been isolated and stored under various conditions. Established macaque DQA1 typing protocols were modified to optimize the typing procedure and enhance the ability to successfully genotype DNA from samples that were of poor quality and/or quantity. Long-term storage of whole-blood buffy coats or stored DNA extracted from whole-blood buffy coats did not affect typing success; however, amplification and typing of DNA extracted from archival samples of plasma were difficult and resulted in a low success rate. This suggests that amplification and DQA1-genotyping of archival samples is possible with a modified protocol, but is influenced by the age and source of the sample, and to a lesser extent, the method used to extract DNA from sample substrates.

Identification of an antigenic epitope in Helicobacter pylori urease that induces neutralizing antibody production

We previously reported a mouse monoclonal antibody (MAb), termed L2, specific for Helicobacter pylori urease strongly inhibited its enzymatic activity. Here, to gain insight into how this antibody affects urease activity, the epitope that was recognized by the antibody was determined. By screening a panel of overlapping synthetic peptides covering the entire sequence of the two subunits (UreA and UreB), we identified a stretch of UreB-derived 19 amino acid (aa) residues (UB-33; aa 321 to 339, CHHLDKSIKEDVQFADSRI) that was specifically recognized by the L2 antibody. Further sequential amino acid deletion of the 19-mer peptide from either end allowed us to determine the minimal epitope as 8 amino acid residues (F8; SIKEDVQF) for L2 reactivity. This epitope appears to lie exactly on a short sequence which formed a flap over the active site of urease, suggesting that binding of the L2 antibody sterically inhibits access of urea, the substrate of urease. Finally, immunization of rabbits with either the 19-mer peptide or the 8-mer minimal epitope resulted in generation of antiurease antibodies that were capable of inhibiting the enzymatic activity. Since urease is critical for virulence of H. pylori, antigenic peptides that induce production of antibodies to inhibit its enzymatic activity may potentially be a useful tool as a vaccine for prevention and treatment of H. pylori infection.

Increased gastric acid secretion after Helicobacter pylori eradication may be a factor for developing reflux oesophagitis

BACKGROUND

The role of acid secretion in reflux oesophagitis which may develop after H. pylori eradication is not well known.

AIM

To investigate the participation of altered gastric acid secretion and the presence of hiatal hernia in the development of reflux oesophagitis after eradication therapy for H. pylori.

SUBJECTS AND METHODS

A total of 105 patients with H. pylori infection, but without reflux oesophagitis at the time of eradication therapy, were followed prospectively for 7 months after the clearance of this microorganism. Gastric acid secretion was assessed by endoscopic gastrin test, and the presence of hiatal hernia by endoscopy.

RESULTS

Reflux oesophagitis developed in 11 out of 105 (10.5%) patients when examined at 7 months after the eradication therapy. The incidence was correlated significantly with the increase in gastric acid secretion after the eradication of H. pylori, and was significantly higher in the patients with hiatal hernia (20%) than in those without it (0%).

CONCLUSIONS

Increased acid secretion after H. pylori eradication is an important risk factor of reflux oesophagitis, especially in patients with hiatal hernia.

[Helicobacter pylori and immunogenetic factors of the host: relevance of the HLADQA1 *0102 and *0301 alleles in peptic ulcer]

AIM

To investigate the potential contribution of the *0102 and *0301 alleles of the HLADQA1 gene in Helicobacter pylori infection and peptic ulcer disease in a Spanish Caucasian population.

PATIENTS AND METHODS

We studied 163 patients with peptic ulcer (117 duodenal ulcers and 46 gastric ulcers; 111 with recent upper gastrointestinal hemorrhage) and 90 controls. The *0102 and *0301 alleles of the HLADQA1 gene were typed by polymerase chain reaction using genomic DNA. H. pylori infection were determined by breath test and/or serology. The cytotoxins CagA and VacA were investigated using serology (Western-blot) in 98 patients and 48 controls with H. pylori infection.

RESULTS

H. pylori infection was found in 94.6% of patients with duodenal ulcer, in 84.4% of those with gastric ulcer and in 67.4% of controls (p < 0.001). The distribution of the *0102 allele of the HLADQA1 gene was similar in patients (31.9%) and in controls (36.7%). The *0301 was more frequent in patients with gastric ulcer (32.6%) than in those with duodenal ulcer (16.2%) (p < 0.05) but no differences were found on comparison with the control group (24.4%). No differences were found when the groups were analyzed according to H. pylori infection, CagA- and VacA-positive strains, consumption of non-steroidal antiinflammatory drugs or previous history of ulcer or hemorrhage.

CONCLUSION

The *0102 and *0301 alleles of the HLADQA1 gene did not alter susceptibility to H. pylori infection or the evolution of peptic ulcer disease in a Caucasian population in Spain.

Favourable effect of an acidified milk (LC-1) on Helicobacter pylori gastritis in man

OBJECTIVE

The supernatant of Lactobacillus johnsonii La1 culture was shown to be bactericidal and to have a partial, acid-independent suppressive effect on Helicobacter pylori in humans. The aim of the present study was to investigate the effect of L. johnsonii La1-acidified milk (LC-1) on H. pylori infection.

DESIGN AND METHODS

Fifty-three volunteers infected with H. pylori as determined by positive 13C-urea breath test and positive serology were randomized to receive either LC-1 or a placebo 180 ml twice a day for 3 weeks. All subjects also received clarithromycin 500 mg bid during the last two weeks of acidified milk therapy. Oesophagogastroduodenoscopy and biopsies were performed at inclusion and repeated 4-8 weeks after the end of the treatment. H. pylori infection was confirmed by urease test and histology. H. pylori density and inflammation were scored using a modified Sydney classification.

RESULTS

LC-1 ingestion induced a decrease in H. pylori density in the antrum (P= 0.02) and the corpus (P= 0.04). LC-1 also reduced inflammation and gastritis activity in the antrum (P= 0.02 and P= 0.01, respectively) and of activity in the corpus (P= 0.02). Clarithromycin eradicated H. pylori in 26% of the subjects; LC-1 did not improve the antibiotic effect.

CONCLUSION

These results suggest that H. pylori infection and gastritis can be down-regulated by LC-1.

[Physiopathology of Helicobacter pylori infections]

Helicobacter pylori (H.p.) causes active chronic gastritis in nearly all infected patients. Cytotoxic factors elaborated by H.p. as well as autoimmune cell damage from the abundant inflammatory response contribute to gastric epithelial cell injury. Antrum gastritis increases gastrin release. The impact of H.p.-infection on gastric acid physiology is complex and usually results in increased gastric acid secretion in duodenal ulcer patients and diminished acid output in patients with gastric cancer. Multiple clinical outcomes including asymptomatic gastritis, duodenal ulcer, gastric ulcer, gastric carcinoma and gastric MALT lymphoma are associated with H.p.-infection. Differences in disease manifestation seem to result from a complex interaction of bacterial virulence, host factors as well as environmental factors. The acid-secretory ability of the infected individual seems to be the main variable determining outcome: Patients with high acid production typically develop antrum-predominant gastritis and are at an increased risk for duodenal ulcer. In contrast patients with low gastric acid secretion frequently develop pangastritis, which may progress to chronic atrophic gastritis and carcinoma.

Review article: is Helicobacter pylori status relevant in the management of GORD?

There is growing interest in the relationship between H. pylori infection and gastro-oesophageal reflux disease (GORD). However, this relationship is complex, as yet not fully elucidated, and probably based on a multiplicity of factors. The prevalence of H. pylori infection in patients with GORD is similar, more often lower than in matched controls. There is a negative correlation between H. pylori infection and the severity of GORD. There are many hypothetical mechanisms by which H. pylori infection may protect from the development of GORD. Conversely, there are many possible mechanisms by which H. pylori infection could theoretically foster the GORD. Patients after H. pylori eradication may develop GORD, and this seems to suggest a protective role of H. pylori infection, but other possible explanations include weight gain after H. pylori eradication, changes in dietary habits and smoking, and pre-existing GORD. H. pylori infected patients treated by various acid-inhibiting therapies such as proton pump inhibitors (PPIs), H2-receptors antagonists (H2-RA) or vagotomy, have an increase of their corpus gastritis severity, both in the activity of inflammation and in the density of organisms. Long-term therapy of GORD in H. pylori infected may lead to rapid progression of atrophic gastritis intestinal metaplasia and dysplasia, and increase the risk of developing gastric cancer. More recently it has been shown that H. pylori infection may interfere with the acid suppressive therapies used for treating GORD. In our opinion the progression of gastritis depends on the threshold of acid output at which H. pylori can 'flourish'. Recently interest is growing on gastric transitional zones and Helicobacter ecology. Any decrease of acid secretion changes the behaviour of H. pylori: the activity of gastritis improves in the antrum, but it deteriorates in the body. During proton pump inhibitor treatment, H. pylori redistribution occurs within the stomach, from an antral to a corpus or fundus prevalent pattern; corpus-fundus gastritis, exacerbated by PPI therapy, may result both in a diminished acid secretion and gastro-oesophageal reflux. The interest in Barrett's oesophagus is growing due to the associated risk of adenocarcinoma. The literature seems to demonstrate that the prevalence of H. pylori infection of the stomach in Barrett's oesophagus patients is not different from that exhibited by controls, roughly one-third of the subjects. Intestinal metaplasia of the gastric cardia seems to be equally frequent in patients with and without GORD. Finally, it appears unlikely that a causal relationship exists between H. pylori infection and Barrett's-associated adenocarcinoma.

Recent developments in the epidemiology of Helicobacter pylori

Prevalence determinations have been performed around the world, and regardless of how exotic a location, H. pylori is found in a substantial proportion of the population. H. pylori remains among the most universal of infections. Understanding of some features of infection has changed. Infection can be gained and lost at rates higher than previously realized. Oral-oral and oral-fecal transmission account for most, if not nearly all, cases of infection. H. pylori infection has declined rapidly in developed countries, which probably has contributed to declines in duodenal ulcer disease and gastric cancer. The full health implications of the potential elimination of infection are unknown.

Is autonomic dysfunction a necessary condition for chronic peptic ulcer formation?

BACKGROUND

The relationship between 1/f fluctuation of the heart rate variability and Helicobacter pylori infection was evaluated, in order to clarify whether autonomic nervous dysfunction is a necessary condition for chronic peptic ulcer formation.

METHODS

The subjects were 11 patients with recurrent chronic peptic ulcer and 20 age-matched normal subjects. Holter ECGs were recorded over 24 h, and the 1/f(-x) fluctuation of the heart rate was computed. The 1/f(-x) fluctuation of the heart rate is a novel index of autonomic function that has been shown to reflect a patient's pleasant mood. For 1/f(-x) fluctuation, the slope of the regression line (-x) was determined and cosine fitting of the absolute slope of the regression line over a 24-h period was performed.

RESULTS

For the normal group, the absolute slope of the regression line during daytime and night-time were 0.53 +/- 0.16 and 1.05 +/- 0.18, respectively. For the peptic ulcer group, the corresponding values during daytime and night-time were 0.94 +/- 0.15 and 1.84 +/- 0.18, respectively. The mean value of the cosine curve was 0.76 +/- 0.23 in the normal group and 1.12 +/- 0.25 in the peptic ulcer group. Thus, these values were significantly higher for the latter group than for the former group (P<0.05). No statistically significant difference in H. pylori infection between the two groups was observed.

CONCLUSIONS

Autonomic nervous dysfunction as well as H. pylori infection appears to be a necessary condition for chronic peptic ulcer formation.

Helicobacter pylori and gastroesophageal reflux disease

The nature of the relationship between Helicobacter pylori (Hp) infection and gastroesophageal reflux disease (GERD) remains unclear. This article reviews the current body of knowledge regarding the association between these two common entities. The authors examine the potential interactions of Hp and GERD from epidemiologic and pathophysiologic viewpoints and summarize and critique the prevalence and eradication studies that have been performed to date. Special consideration is given to the possible effects that long-term use of proton pump inhibitors may have on Hp gastritis.

Pathologic features of the gastric mucosa adjacent to primary MALT-lymphomas

The frequency of reported cases of primary gastric mucosa-associated lymphoid tissue (MALT)-lymphoma is increasing worldwide. Helicobacter pylori plays a preponderant role in its pathogenesis. Gastric MALT-lymphoma arises from nonrecirculating centrocytelike cells located at the periphery of reactive lymphoid follicles, which are common in patients infected with this microorganism. Histopathologic features other than lymphoid follicles have not been well described. In this study the authors describe the morphologic changes in the gastric mucosa adjacent to MALT-lymphomas. From the files of the departments of pathology at the Instituto Nacional de Cancerologia and the Instituto Nacional de la Nutricion in Mexico City, primary gastric MALT-lymphomas were retrieved. Patients with hematoxylin-eosin-stained histologic sections, including the overt neoplasia and the neighboring gastric mucosa, were selected. Lymphoid follicles as well as intestinal metaplasia, atrophy, and eosinophils were evaluated as present or absent and graded as proposed by the Updated Sydney System for gastritis. Fifty-one patients were eligible for analysis. There were 35 low-grade and 16 high-grade primary MALT-lymphomas. Forty-seven patients (92.6%) showed reactive lymphoid follicles in the neighboring mucosa, 32 patients (69.5%) had intestinal metaplasia, and 26 patients (54.1%) demonstrated atrophy. In 41 patients (73.8%) there was an increased number of eosinophils. Our findings suggest that lymphoid follicles, intestinal metaplasia, atrophy, and eosinophils in an endoscopic biopsy are markers of both gastric lymphoma and carcinoma.

Host determinants of Helicobacter pylori infection and its clinical outcome

Greater than one-half of the world's population harbors Helicobacter pylori. The majority of infected individuals, however, remain asymptomatic, with only 10% to 20% developing diseases, including peptic ulcer disease, gastric cancer, and gastric mucosa-associated lymphoid tissue lymphoma. This article reviews host factors that may predispose an individual to both the acquisition of H. pylori infection and subsequent clinical outcome. Individuals with specific blood group antigens and human leukocyte antigen genotypes may be more susceptible to H. pylori infection. Additional factors, such as the age of acquisition, the host immune response, the site of infection, acid secretion, and interactions with nonhost factors (including bacterial virulence factors and environmental influences) may play a role in determining clinical outcome. Further investigation is required to clarify the mechanisms by which these interactions occur and, more critically, to determine their relative importance. This knowledge will enable the identification of individuals at risk of developing clinical disease with H. pylori infection.

Association of Helicobacter pylori infection with gastric carcinoma: a meta-analysis

OBJECTIVE

As conflicting studies have recently been published, we aimed to determine if Helicobacter pylori (H. pylori) infection is associated with gastric adenocarcinoma.

METHODS

This was a meta-analysis of observational epidemiological studies.

RESULTS

A total of 42 studies met the selection criteria and were categorized by the type of study design: eight cohort and 34 case-control studies. The pooled odds ratio for H. pylori in relation to gastric carcinoma was 2.04 (95% CI: 1.69-2.45). Both patient age (OR 0.77, 95% CI: 0.68-0.89) and intestinal type cancers (OR 1.14, 95% CI: 1.05-1.25) were independent effect modifiers. Analysis of other effect modifiers showed no relationship with female gender (OR 0.76, 95% CI: 0.64-0.89), stage of cancer (advanced %) (OR 1.12, 95% CI: 0.88-1.43), anatomical location (cardia %) (OR 1.54, 95% CI: 0.32-7.39) or cohort (nested case-control) studies (OR 1.72, 95% CI: 0.32-9.17). There was significant heterogeneity among the studies (tau2 = 149; p < 0.001). The quality of the studies varied considerably, with the majority of excellent studies producing positive results and the very poor to moderate studies producing mixed results.

CONCLUSIONS

H. pylori infection is associated with a 2-fold increased risk of developing gastric adenocarcinoma.

Acquired gastric mucosa-associated lymphoid tissue (MALT): a review with special emphasis on association with extragastric diseases and management problems of gastric MALT

Mucosa-associated lymphoid tissue is absent physiologically in normal gastric mucosa, but it can develop in some pathologies (dyspepsia, celiac disease, autoimmune diseases) due to certain (Helicobacter pylori, gluten) or uncertain (viruses?) antigenic stimuli. Its importance is related to the consideration that it is the background for the development of gastric mucosa-associated lymphoid tissue (MALT) lymphoma, and its histologic progression to MALT lymphoma may be diagnosed using Isaacson's score. Monoclonal bands can be diagnosed in acquired gastric MALT as well as in gastric MALT lymphoma, but its role is unknown. To prevent development of MALT lymphoma from acquired MALT, currently anti-H. pylori treatment in all H. pylori- and MALT-positive patients is not suggested--only in patients with grade 3 of acquired MALT--due to the high risk of developing MALT lymphoma in these patients. At the same time, the etiology of gastric MALT in autoimmune extragastric diseases is not clear. Additional studies are needed to clarify this relation and its possible causes.

Helicobacter pylori infection and polymorphisms in the tumor necrosis factor region

Twin studies evidence that genetic factors of the host influence the acquisition and the clinical outcome of Helicobacter pylori infections in addition to bacterial and environmental factors. In the tumor necrosis factor (TNF) alpha-gene, allelic frequencies of the polymorphic microsatellite TNFa and the promoter polymorphism TNF-308 were studied for 209 H. pylori+ patients and compared to 184 H. pylori- controls. In the H. pylori+ group 34 individuals suffered from duodenal ulcer and 45 from gastric ulcer. Genotyping of the TNFa microsatellite and TNF-308 polymorphisms was performed after polymerase chain reaction by polyacrylamide gel electrophoresis (PAGE) and allele-specific oligonucleotide hybridizations, respectively. The phenotype frequency of microsatellite allele TNFa6 was lower in the H. pylori+ females as well as infected females with gastric ulcer compared to uninfected controls. Infected men with duodenal ulcer had a decreased frequency of allele TNFa10. The genotype TNF1/TNF1 of the polymorphism TNF-308 is a risk factor for duodenal ulcer in H. pylori+ females; p = 0.01; relative risk (RR) = 10.7; corrected p-value (Pc) = 0.05. Thus, the TNF region is crucial in the complex genetic predisposition for H. pylori infection for certain patient subgroups.

HLA-DQA1 alleles and the presence of Helicobacter pylori antibodies

Recent reports suggest that the HLA-DQA1 gene may be important in determining susceptibility to and outcome of Helicobacter pylori infection. To determine if there is an association between HLA-DQA1 alleles and H. pylori antibodies, DQA1 alleles and H. pylori-specific antibodies were determined in 199 random subjects of Finnish origin (mean age 43 years, range 22-69 years). H. pylori-specific class IgG antibodies were measured using the EIA method (Pyloriset-EIA-G, Orion Diagnostica, Espoo, Finland). HLA-DQA1 typing was carried out using PCR-SSP (PCR with sequence-specific primers). There were 64 subjects with H. pylori-specific class IgG antibodies (ab+) and 135 subjects without H. pylori-specific class IgG antibodies (ab-). Gene and phenotype frequencies of HLA-DQA1 alleles were similar in the ab+ and ab- subjects (P = NS). The data suggest that no single HLA-DQA1 allele is associated with the presence of serum antibodies against H. pylori.

Review article: Helicobacter pylori and gastro-oesophageal reflux disease-clinical implications and management

A significant proportion of patients with gastro-oesophageal reflux disease (GERD) have Helicobacter pylori infection, but it is unclear whether or not H. pylori should be treated in this clinical setting. The aim of this review was to critically assess the relationship between H. pylori and GERD and its potential implications for the management of GERD. Data for this review were gathered from the following sources up to April 1998-the biomedical database MEDLINE, a detailed review of medical journals, and a review of abstracts submitted to relevant international meetings. On average, 40% of GERD patients carry H. pylori infection, with a reported infection prevalence ranging from 16% to 88%. To date, there has been no reported controlled trial of effective H. pylori therapy in GERD. GERD has been reported to develop de novo following the cure of H. pylori in peptic ulcer disease. In the presence of H. pylori, proton pump inhibitor therapy appears to accelerate the development of atrophic corpus gastritis, a potentially precancerous condition. Conversely, proton pump inhibitor therapy seems to become less effective after cure of H. pylori. The mechanisms underlying these important contrasting phenomena are poorly understood. The relationship between H. pylori and GERD is complex, and it is difficult to give definitive guidelines on the management of H. pylori infection in GERD. Controlled trials of H. pylori therapy in GERD are urgently needed, as well as further long-term data on both the natural history of gastric histopathological changes in the H. pylori-positive GERD patient treated with proton pump inhibitors, and the impact of H. pylori status on the clinical efficacy of antisecretory therapy. Pending these data, it is perhaps advisable to advocate cure of H. pylori in young patients with proton pump inhibitor-dependent GERD who, in the absence of anti-reflux surgery, are faced with the likelihood of long-term medical therapy.

The interrelationship between Helicobacter pylori vacuolating cytotoxin and gastric carcinoma

OBJECTIVE

We aimed to determine whether cytotoxin-positive Helicobacter pylori strains are associated with gastric carcinoma.

METHODS

We studied 130 patients: 57 H. pylori-positive patients with gastric carcinoma, 53 H. pylori-positive patients without gastric carcinoma, and 20 H. pylori-negative subjects. The ability of H. pylori strains to produce vacuolating cytotoxin was tested in INT-407 and HeLa cells. The presence of antibodies to cytotoxin was investigated in blood serum from all subjects by immunoblotting. Fragments of the gastric mucosa from patients without gastric carcinoma and H. pylori-negative subjects were obtained for histopathological study.

RESULTS

Considering the results as a whole, 40 (70.2%) patients with and 22 (41.5%) without gastric carcinoma were colonized by cytotoxin-positive strains. Antibodies against cytotoxin were not observed in the serum from 17 (29.8%) gastric carcinoma patients and from 31 (58.5%) patients without gastric carcinoma. H. pylori strains isolated from these patients did not produce cytotoxin in vitro. In regard to cytotoxin positivity, a significant difference was observed between patients with and without gastric carcinoma (p=0.004; odds ratio [OR]: 3.3; 95% confidence interval [CI]: 1.4-7.9). Higher scores of mononuclear (p=0.0001) and polymorphonuclear (p=0.000003) cells were observed in the antral mucosa from H. pylori-positive patients without gastric carcinoma infected by cytotoxin-positive strains than in those harboring cytotoxin-negative strains.

CONCLUSION

Cytotoxin-producing H. pylori strains were more frequently observed in patients with gastric carcinoma and this aspect emphasizes the role of cytotoxin in the genesis of the tumor.

The effect of class II major histocompatibility complex expression on adherence of Helicobacter pylori and induction of apoptosis in gastric epithelial cells: a mechanism for T helper cell type 1-mediated damage

Helicobacter pylori infection is associated with gastric epithelial damage, including apoptosis, ulceration, and cancer. Although bacterial factors and the host response are believed to contribute to gastric disease, no receptor has been identified that explains how the bacteria attach and signal the host cell to undergo apoptosis. Using H. pylori as "bait" to capture receptor proteins in solubilized membranes of gastric epithelial cells, class II major histocompatibility complex (MHC) molecules were identified as a possible receptor. Signaling through class II MHC molecules leading to the induction of apoptosis was confirmed using cross-linking IgM antibodies to surface class II MHC molecules. Moreover, binding of H. pylori and the induction of apoptosis were inhibited by antibodies recognizing class II MHC. Since type 1 T helper cells are present during infection and produce interferon (IFN)-gamma, which increases class II MHC expression, gastric epithelial cell lines were exposed to H. pylori in the presence or absence of IFN-gamma. IFN-gamma increased the attachment of the bacteria as well as the induction of apoptosis in gastric epithelial cells. In contrast to MHC II-negative cell lines, H. pylori induced apoptosis in cells expressing class II MHC molecules constitutively or after gene transfection. These data describe a novel receptor for H. pylori and provide a mechanism by which bacteria and the host response interact in the pathogenesis of gastric epithelial cell damage.

Variation in the 13C-urea breath test value by nationality in Helicobacter pylori-infected children

BACKGROUND

The 13C-urea breath (13C-UBT) test value is (semi-)quantitatively related to Helicobacter pylori density in the gastric antrum, and the value correlates with the grade of gastritis. The aim of this study was to assess variation of the 13C-urea breath test value by sociodemographic factors in H. pylori-positive children.

METHODS

The analysis was performed on 127 asymptomatic children (aged 5-7 years) who were identified as H. pylori-positive with the 13C-UBT test in a large population-based epidemiologic study in the city of Ulm (southern Germany). The parents of the children were asked to fill out a standardized questionnaire about sociodemographic data.

RESULTS

Forty-two infected children (33.1%) were of German nationality, 47 children (37.0%) were of Turkish and 38 children (29.9%) were of another nationality. Turkish children had a significantly higher 13C-UBT value (geometric mean = 27.2%) than German children (16.7%) or children with another nationality (19.3%) (P < 0.001). Girls had a trend towards higher values than boys (P = 0.058 after adjustment for nationality). Body mass index, education of the parents, and prior use of antibiotics were unrelated to the extent of the 13C-UBT.

CONCLUSIONS

This study identified significant variation in the extent of the 13C value by nationality among H. pylori-infected children. Further studies are needed to elucidate the causes and potential consequences of these variations.