The role of the local immune response in the pathogenesis of peptic ulcer formation

Recent research progress on the correlation between metabolic syndrome and Helicobacter pylori infection

Background

Globally, metabolic syndrome (MS) and Helicobacter pylori (HP) infection, which have gained an epidemic status, are major challenges to human health, society, and medical professionals. Recent studies have demonstrated that MS is closely related to HP infection. Additionally, HP is an important risk factor for gastric cancer. However, systematic reviews on HP are lacking. This review aimed to summarize and analyze the potential correlation of HP infection with MS and its components, as well as the underlying mechanism, to provide reference and strategies for clinical prevention and treatment.

Methodology

Previous studies examining the correlation between HP and MS since 1990 were retrieved from the PubMed, Web of Science, and Embase databases. The potential correlation between HP infection and MS and its components was comprehensively analyzed. The keywords "Helicobacter pylori," "HP," "metabolic syndrome," "hypertension," "obesity," "diabetes," or "dyslipidemia" were used in all fields. No language restrictions were imposed.

Results

MS was strongly correlated to HP infection. The inflammatory response and inflammatory factors produced during HP infection are important etiological factors for insulin resistance and MS. The co-occurrence of long-term chronic inflammation and immune dysfunction with MS may be the predisposing factor for HP infection. MS components, such as diabetes, hypertension, dyslipidemia, and obesity were also correlated with HP infection in one or both directions.

Conclusions

HP infection and MS may promote the pathogenesis of each other. The contribution of HP infection and MS to gastric cancer cannot be ruled out based on co-occurrence. The MS components diabetes and obesity may be bidirectionally correlated with HP infection.

Association of Helicobacter pylori infection with the risk of metabolic syndrome and insulin resistance: an updated systematic review and meta-analysis

BACKGROUND

Conflicting results of recent studies on the association between Helicobacter pylori (H. pylori) infection and the risk of insulin resistance and metabolic syndrome explored the need for updated meta-analysis on this issue. Therefore, this systematic review aimed to estimate the pooled effect of H. pylori infection on the risk of insulin resistance and metabolic syndrome.

METHODS

To identify case-control studies and cohort studies evaluating the association of H. pylori infection with insulin resistance and metabolic syndrome, a comprehensive literature search was performed from international databases including Medline (PubMed), Web of Sciences, Scopus, EMBASE, and CINHAL from January 1990 until January 2021. We used odds ratio with its 95% confidence interval to quantify the effect of case-control studies and risk ratio with its 95% CI for the effect of cohort studies.

RESULTS

22 studies with 206,911 participants were included for meta-analysis. The pooled estimate of odds ratio between H. pylori infection and metabolic syndrome in case-control studies was 1.19 (95% CI 1.05-1.35; I2 = 0%), and in cohort studies, the pooled risk ratio was 1.31 (95% CI 1.13-1.51; I2 = 0%). Besides, case-control studies showed the pooled odds ratio of 1.54 (95% CI 1.19-1.98; I2 = 6.88%) for the association between H. pylori infection and insulin resistance.

CONCLUSION

In this meta-analysis, the results showed that there was a possibility of metabolic syndrome and insulin resistance in case of H. pylori infection.

Amelioration of alcohol‑induced gastric mucosa damage by oral administration of food‑polydeoxyribonucleotides

Gastritis refers to inflammation caused by injury to the gastric epithelium, which is usually due to excessive alcohol consumption and prolonged use of nonsteroidal anti-inflammatory drugs. Millions of individuals worldwide suffer from this disease. However, the lack of safe and promising treatments makes it urgent to explore and develop leads from natural resources. Therefore, food as medicine may be the best approach for the treatment of these disorders. The present study described the protective effects of food-polydeoxyribonucleotides (f-PDRNs) in a rat model of gastric mucosal injury induced by HCl-EtOH. Administration of f-PDRN was performed with low-PRF002 (26 mg/kg/day), medium-PRF002 (52 mg/kg/day) and high-PRF002 (78 mg/kg/day) on the day of autopsy. The site of damage to the mucous membrane was also analysed. In addition, an increase in gastric juice pH, total acidity of gastric juice and decrease in gastric juice secretion were confirmed, and gastric juice secretion-related factors corresponding to the administration of f-PDRN were analysed. Administration of f-PDRN reduced the mRNA expression of histamine H2 receptor, muscarinic acetylcholine receptor M3, cholecystokinin 2 receptor and H⁺/K⁺ ATPase related to gastric acid secretion and downregulation of histamine, myeloperoxidase and cyclic adenosine monophosphate. In addition, it was histologically confirmed that the loss of epithelial cells and the distortion of the mucosa were recovered in the group in which f-PDRN was administered compared to the model group with gastric mucosa damage. In summary, the present study suggested that f-PDRN has therapeutic potential and may have beneficial effects if taken regularly as a food supplement.

The pertussis hypothesis: Bordetella pertussis colonization in the etiology of asthma and diseases of allergic sensitization

Decades of peer reviewed evidence demonstrate that: 1)Bordetellapertussisand pertussis toxin are potent adjuvants, inducing asthma and allergic sensitization in animal models of human disease, 2)Bordetella pertussisoften colonizes the human nasopharynx, and is well documented in highly pertussis-vaccinated populations and 3) in children, a history of whooping cough increases the risk of asthma and allergic sensitization disease. We build on these observations with six case studies and offer a pertussis-based explanation for the rapid rise in allergic disease in former East Germany following the fall of the Berlin Wall; the current asthma, peanut allergy, and anaphylaxis epidemics in the United States; the correlation between the risk of asthma and gross national income per capita by country; the lower risk of asthma and allergy in children raised on farms; and the reduced risk of atopy with increased family size and later sibling birth order. To organize the evidence for the pertussis hypothesis, we apply the Bradford Hill criteria to the association between Bordetella pertussisand asthma and allergicsensitization disease. We propose that, contrary to conventional wisdom that nasopharyngealBordetella pertussiscolonizing infections are harmless, subclinicalBordetella pertussiscolonization is an important cause of asthma and diseases of allergic sensitization.

The Associations Between Helicobacter pylori Infection, Serum Vitamin D, and Metabolic Syndrome: A Community-Based Study

The associations between Helicobacter pylori infection, serum vitamin D level, and metabolic syndrome (MS) are controversial. The present community-based study aimed to investigate the effect of H pylori infection and serum vitamin D deficiency on MS development.Individuals from the northeastern region of Taiwan were enrolled in a community-based study from March, 2014 to August, 2015. All participants completed a demographic survey and underwent the urea breath test (UBT) to detect H pylori infection as well as blood tests to determine levels of vitamin D, adiponectin, leptin, and high-sensitivity C-reactive protein. The ATP III criteria for MS were used in this study.A total of 792 men and 1321 women were enrolled. The mean age was 56.4 ± 13.0 years. After adjusting for age and sex, the estimated odds of MS development for a UBT-positive subject were 1.503 (95% confidence interval [CI]: 1.206-1.872, P < 0.001) when compared to a UBT-negative subject. For participants with vitamin D deficiency (<20 ng/mL), the odds of MS development were 1.423 (95% CI: 1.029-1.967, P = 0.033) when compared to those with sufficient vitamin D level (>30 ng/mL). For participants with both H pylori infection and vitamin D deficiency, the odds of MS development were 2.140 (95% CI: 1.348-3.398, P = 0.001) when compared to subjects without H pylori infection and with sufficient vitamin D levels.H pylori infection and vitamin D deficiency could be predictors of MS. For individuals with both H pylori infection and vitamin D deficiency, the odds of MS development were 2.140 when compared to individuals without H pylori infection and with sufficient vitamin D levels.

Helicobacter pylori Infection Increases Insulin Resistance and Metabolic Syndrome in Residents Younger than 50 Years Old: A Community-Based Study

This study aimed to analyze the influence of H. pylori infection on insulin resistance and metabolic syndrome (MS) by multivariate analysis of a community-based cohort study. From January 2013 to February 2014,811 subjects were enrolled in a community-based cohort study from the northeastern region of Taiwan. All subjects received a demographic survey and blood tests, including an H. pylori antibody test, liver biochemistry tests, lipid profiles, sugar/insulin levels for Homeostatic model assessment (HOMA-IR index), and measurements of adipokines and inflammatory cytokines. A total of 264 men and 547 women were included in this study. The mean age was 59.2 ± 12.7 years. Subjects seropositive for H. pylori antibodies exhibited higher rates of hypertension, an increased incidence of a HOMA-IR index > 2.5 and a higher level of tumor necrosis factor-α than those without H. pylori antibodies. We found a significant difference in the presence of H. pylori antibodies between subjects with MS and those without MS (76.7% vs. 53.7%, p = 0.007) among subjects < 50 y/o. A HOMA-IR index >2.5, H. pylori antibody presence and leptin were predictors for MS in subjects < 50 y/o. The estimated odds ratio of MS for a subject with H. pylori antibodies was 3.717 (95% CI = 1.086–12.719) times that of a subject without H. pylori antibodies. In addition, no difference in H. pylori antibody status was detected for MS prediction in subjects that were ≧ 50 y/o (p = 0.861). In conclusion, subjects with H. pylori antibodies had a higher incidence of a HOMA-IR >2.5 than those without H pylori antibodies. For subjects aged < 50 y/o, the H. pylori antibody was a predictor for MS.

Possible pathogenetic role of Helicobacter pylori infection in cardiac syndrome X

The diagnosis of cardiac syndrome X (CSX) is often a diagnosis of exclusion and hence requires a systematic and comprehensive assessment of each patient to rule out more common causes of chest discomfort. The definitive technique for the diagnosis of CSX is not currently available. Many patients with chest pain and normal coronary angiograms have neither metabolic nor hemodynamic evidence of myocardial ischemia. Causes of nonischemic chest pain such as esophageal dysfunction, pulmonary hypertension, and mitral valve prolapse, should also be considered and pursued. Although chronic inflammation induced by Helicobacter pylori infection might play a part in the pathophysiology of CSX, one can conclude that nonischemic chest pain resulting from gastrointestinal disease such as esophagitis, gastritis cannot be completely excluded in the patients with CSX. We believe future large scale prospective cohort studies will be needed to solve that dilemma.

N/A

N/A

Association of interleukin 1 gene family polymorphisms with duodenal ulcer disease

Cytokine genes taking part in the immunological response to Helicobacter pylori infection are good candidates to study for genetic predisposition to duodenal ulcer disease (DU). Among cytokines, interleukin (IL)-1beta and its natural specific inhibitor, the interleukin-1 receptor antagonist, are cytokines that play a key role in regulating gastric acid secretion and modulating the immune response in the gastrointestinal mucosa. We aimed to investigate whether polymorphisms in the IL-1B and IL-1RN genes are involved in the susceptibility to duodenal ulcer. DNA from 131 unrelated Spanish Caucasian patients with DU and 105 ethnically matched healthy controls was typed for the IL-1B-511, IL-1B-31, and IL-1B + 3954 gene polymorphisms, and the VNTR polymorphism in intron 2 of the IL-1RN gene by polymerase chain reaction (PCR)-based methods and TaqMan assays. H. pylori status and non-steroidal anti-inflammatory drugs (NSAIDs) use was determined in all patients and controls. Logistic regression analysis identified H. pylori infection (OR: 9.74; 95%CI = 3.53-26.89) and NSAIDs use (OR: 8.82; 95%CI = 3.51-22.17) as independent risk factors for DU. In addition, the simultaneous carriage of IL-1RN*2, IL-1B-511*C, IL-1B-31*T and IL-1B + 3954*C alleles was a genetic risk factor for DU in patients with H. pylori infection (OR: 3.22; 95%CI = 1.09-9.47). No significant differences in IL-1RN and IL-1B genotypes were found when patients were categorized according to gender, age of onset, smoking habit, NSAIDs use, type of complication and positive family history. Our results provide further evidence that host genetic factors play a key role in the pathogenesis of duodenal ulcer.

Helicobacter pylori infection in the Australian community: current prevalence and lack of association with ABO blood groups

AIMS

To assess the current prevalence of Helicobacter pylori infection in an Australian urban population sample and to relate this to age, gender and ABO and Rhesus blood groups.

METHODS

We performed a prospective epidemiological survey of H. pylori serological status in 500 consecutive voluntary blood donors who presented for the purpose of blood donation at the central -Melbourne branch of the Australian Red Cross Blood Service, Victoria, Australia, and gave a Melbourne suburban home address.

RESULTS

The overall prevalence of specific anti-H. pylori IgG antibodies in this cohort was 32% (95% confidence interval = 28-36%) and H. pylori sero-positivity increased with age. The rate of H. pylori infection was not significantly different in men and women, with anti-H. pylori IgG anti-bodies detected in 35% (97/277) of men compared with 28% (63/233) of women (P = 0.12). Similarly, H. pylori serological status was not significantly different between subjects of different ABO (P = 0.18) or Rhesus blood groups (P = 0.55).

CONCLUSION

This study showed that, contrary to expectation, the updated prevalence of H. pylori seropositivity (32%) in this Melbourne sample is at least as high as that found in previous Australian studies over the past 19 years. Seropositivity increased with age, and was not related to gender, confirming the infection pattern seen in other developed nations. Despite epidemiological evidence of increased peptic ulcer disease in ABO blood group O subjects, and recent evidence that H. pylori adhesion to gastric epithelial cells is mediated by blood group epitopes, no significant association between blood groups and H. pylori serological status was detected.

In situ correlation of cytokine secretion and apoptosis in Helicobacter pylori-associated gastritis

Tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) are important for the pathogenesis of Helicobacter pylori-associated gastritis and peptic ulcer disease. Gastric biopsies from H. pylori-positive and -negative patients were used to examine the in situ correlation of TNF-alpha and IFN-gamma with epithelial cell apoptosis, bacterial load, and histological parameters of gastritis. From the same patients, we isolated H. pylori-specific T cell lines and clones and examined their ex vivo release of proinflammatory cytokines. We found a highly significant correlation of TNF-alpha and IFN-gamma production with activity and grade of gastritis (P < 0.01), H. pylori density (P = 0.01), epithelial cell apoptosis (P < 0.001), and Fas/Fas-ligand expression (P < 0.001). T cell lines and clones were all TCR-alphabeta(+) and showed T helper 1 functional phenotype. With the use of serial histological sections, this study showed for the first time the in situ correlation of TNF-alpha and IFN-gamma with epithelial cell apoptosis, bacterial load, and histological severity of disease and emphasizes the role of these cytokines in the pathophysiology of H. pylori-associated disease.

Role of Helicobacter pylori infection in the incidence and clinical course of monoclonal gammopathy of undetermined significance

OBJECTIVES

We aimed to evaluate the hypothesis that chronic antigenic stimulation is an etiological factor of monoclonal gammopathy of undetermined significance (MGUS) with special relevance to Helicobacter pylori infection.

METHODS

We performed a retrospective, observational study. The diagnosis of MGUS was based on serum protein electrophoresis, serum IgM levels (<3 gr/dl), urinary M protein, a normal bone marrow biopsy, normal renal function, and a negative skeletal survey. H. pylori infection was ascertained by rapid urease testing and endoscopy with gastric biopsy for histology. Eradication of H. pylori was assessed by urea breath test and stool antigen assay 4 wk after completion of an appropriate treatment regimen.

RESULTS

Sixty-nine patients with MGUS were included in the study. Of these, 57 had undergone evaluation for H. pylori infection for various GI symptoms. Thirty-nine of 57 patients (68.42%) with MGUS also had evidence of H. pylori infection. In 11 of these 39 patients (28.21%), eradication of H. pylori infection with an appropriate regimen led to normalization of the serum protein electrophoresis and resolution of the gammopathy.

CONCLUSION

The results of our study give increased credibility to the theory that in a proportion of patients the pathogenesis of MGUS involves chronic antigenic stimulation and H. pylori is implicated. The search for H. pylori infection and an attempt to eradicate the bacterium in positive cases seem to be appropriate in patients diagnosed with MGUS.

Childhood peptic ulcer in the Ural area of Russia: clinical status and Helicobacter pylori-associated immune response

BACKGROUND

The relation of between Helicobacter pylori and the symptoms in children is still controversial. Determination of specific immunoglobulin (Ig) G antibodies to H. pylori may represent a useful test to screen the patients with acid peptic disease in childhood. The aim of this study was to investigate the spectrum of clinical symptoms, endoscopic and histologic lesions, and clinical value of serum IgG response to H. pylori in school-aged children residing in the Ural area of Russia for the identification of Helicobacter -related acid-peptic disease.

METHODS

During 1998, 129 pediatric outpatients (mean age, 12.1 +/- 2.3 years; age range, 10-15 years; 41 boys, 88 girls) were undergoing gastroduodenal endoscopy for evaluation of chronic abdominal pain. H. pylori colonization was determined by histology, urease test, and polymerase chain reaction. H. pylori IgG antibodies were found by using an enzyme-linked immunosorbent assay.

RESULTS

There was a high prevalence of H. pylori infection (80%) and peptic ulcers (24%) among the study group. Duodenal ulcers were detected in 31 of the children; all of them were H. pylori positive. Family history of peptic ulcers, nighttime pain associated with nocturnal awakening, fasting pain relieved by food, pain associated with meals, postprandial pain, bitter taste, and heartburn were the clinical signs that helped to distinguish the ulcer-positive children from the ulcer-negative H. pylori group. Duodenal ulcer patients had higher anti- H. pylori IgG titers compared with the levels of IgG antibodies in the infected children without ulcers ( P < 0.001). Peptic ulcer disease was a more common finding in the Ural ethnic group of Asians (Bashkirs) compared with the pediatric population of Russian origin.

CONCLUSIONS

These results provide further evidence for a causal relation between H. pylori -associated peptic ulcer disease in childhood and relevant clinical symptoms. High titers of anti- H. pylori IgG might serve as a useful noninvasive indicator of ulcer disease.

The polymorphic IL-1B and IL-1RN genes in the aetiopathogenesis of peptic ulcer

Besides environmental factors, the genetic background of an individual may contribute to the development and final outcome of peptic ulcer disease. Interleukin-1beta (IL-1beta) and the interleukin-1 receptor antagonist (IL-1ra) are cytokines that play a key role in modulating the inflammatory response in the gastrointestinal mucosa. This study aimed to investigate whether polymorphisms in the IL-1B and IL-RN genes are involved in the susceptibility to and final outcome of peptic ulcer disease. DNA from 179 unrelated Spanish Caucasian patients with peptic ulcer diseases and 99 ethnically matched healthy controls was typed for the TaqI polymorphism at position + 3954 in the IL-1B gene and the variable number of tandem repeats polymorphism in intron 2 of the IL-1RN gene. The determination of Helicobacter pylori status and non-steroidal anti-inflammatory drug (NSAIDs) use was studied in all patients and in controls. H. pylori infection and NSAID use were more frequent in ulcer patients than in controls. There were no significant differences in carriage rate, genotype and allele frequencies of the IL-1RN and the IL-1B(+3954) gene polymorphisms between peptic ulcer patients and controls. However, a strong allelic association between IL-1B and IL-1RN genes was found in duodenal ulcer patients (P < 0.0006). Logistic regression identified H. pylori infection and NSAIDs use as independent risk factors for peptic ulcer diseases whereas the simultaneous carriage of IL-1B(+3954) allele 2 and IL-1RN allele 2 was associated with reduced risk for duodenal ulcer disease (OR: 0.37, 95% CI = 0.14-0.9). Our data suggest that IL-1B and IL-1RN genes in addition to bacterial and environmental factors play a key role in determining the final outcome of peptic ulcer disease.

Immune response to autologous and heterologous Helicobacter pylori antigens in humans

Infection of humans with Helicobacter pylori results in the development of chronic gastritis and plays an important role in gastric ulcer pathogenesis. Despite the infiltration of the mucosa with specific immunocompetent cells and production of specific antibodies, the infection usually persists for life. This study was performed to investigate if immunologic mechanisms exist which could contribute to the inability of the host to terminate the infection. Therefore, we compared the in vitro immunoreactivity of peripheral blood mononuclear cells (PBMC) from H. pylori-infected patients after stimulation with sonicated H. pylori bacteria from the stomach of the patient (autologous bacterial strain) with stimulation by bacteria from other patients (heterologous bacteria). We measured cell proliferation, expression of T cell activation markers CD25, HLA-DR, and CD71, as well as production ofinterleukin-10 (IL-10), an inhibitory cytokine. We found that the proliferative response of PBMC was significantly lower after autologous than after heterologous stimulation. Furthermore, secretion of IL-10 in the culture supernatants was significantly higher when PBMC were incubated with autologous than with heterologous H. pylori antigens. No significant differences between autologous or heterologous stimulation were observed in the increased expression of T cell activation markers. These data indicate that systemic immunologic response to H. pylori are strain-dependent. For further studies of the immune responses towards H. pylori, the use of an autologous stimulatory system seems necessary.

Validation of serological tests forHelicobacter pylori infection in an Irish population

BACKGROUND

Serological tests for Helicobacter pylori using laboratory and 'office' formats are commonly used, easy to perform, inexpensive and widely available. Local validation of test performance is required.

AIMS

This study examined the performance of a laboratory and 'office' ELISA in a population of Irish dyspeptics presenting for endoscopy.

METHODS

Consecutive patients presenting for endoscopy had blood drawn at sedation. Samples were analysed using two ELISA formats; a standard laboratory format and an 'office' ELISA test card. H. pylori infection was diagnosed by analysis of antral and corpus biopsies using the rapid urease test, culture and histology. A combination of two positive invasive tests was considered indicative of infection.

RESULTS

The sensitivity and specificity of laboratory ELISA was 82.4% and 85% respectively while the values for the 'office' ELISA were 87.7% and 85.7% respectively. In patients under 45 years sensitivities and specificities of the 'office' test exceeded 90%. The two serological tests agreed in 87.5% of subjects.

CONCLUSIONS

Both tests performed satisfactorily. However, indeterminate results impaired the usefulness of the laboratory ELISA particularly when using a new cut-off. The 'office' ELISA performed particularly well in young patients. A simpler test using antigens from locally prevalent strains to optimise accuracy is awaited.

Positive effect of rebamipide on gastric permeability in mice after eradication of Helicobacter felis

BACKGROUND

Despite Helicobacter pylori eradication, gastric inflammation persists for months or years. Preliminary results have indicated that an increase in gastric permeability could be one reason. Our aim was to evaluate the effect of a mucosal protective drug, rebamipide, on gastric permeability in a model of H. felis-infected mice.

METHODS

Thirty-three C57/BL6 mice were inoculated with H. felis, and seven controls were kept non-inoculated. After 2 months 20 infected mice were treated with omeprazole, amoxicillin, and clarithromycin for 1 week and then for 4 weeks with either rebamipide (n = 9) or placebo (n = 11). The 13 remaining mice were kept untreated. After cessation of treatment, a fragment of antrum obtained from each mouse was mounted in a small Ussing chamber to study the electric resistance of the tissue (R) and antral permeability.

RESULTS

No modification of the paracellular permeability (R, JNa, JMan) was observed in either group. However, the transcellular permeability to horseradish peroxidase (HRP) was significantly increased in H. felis-infected non-treated mice (1131 +/- 463, 948 +/- 339, and 182 +/- 312 ng/h x cm2) as compared with non-infected controls (469 +/- 262, 458 +/- 261, and 10 +/- 6 ng/ h x cm2, for J3H-HRP, JD, and JHRPi, respectively) (P < 0.003). Eradication of the bacteria by antibiotics without subsequent treatment with rebamipide led to a non-significant decrease in the HRP fluxes. However, when rebamipide was used after the antibiotic treatment, a significant (P < 0.01) decrease in HRP fluxes as compared with non-treated mice was observed.

CONCLUSIONS

These results confirm that gastric permeability to macromolecules remains increased despite H. felis eradication and show that rebamipide can facilitate the normalization of gastric permeability to macromolecules after bacterial eradication.

Replication-defective adenovirus infection reduces Helicobacter felis colonization in the mouse in a gamma interferon- and interleukin-12-dependent manner

Helicobacter infection leads to chronic inflammation of the stomach. Although the infection persists in spite of an immune response, animal studies have shown that adjuvant-based oral vaccines can protect against infection and even eliminate established infection. These vaccines are thought to induce a Th2 immune response, counterbalancing the Th1 response seen with natural infections. As a prelude to using adenovirus vectors carrying cytokine genes to modulate the immune response to established Helicobacter felis infection, we first examined the effect of the replication-defective adenovirus (RDA) vector itself. C57BL/6 mice chronically infected with H. felis (8 to 10 weeks) received intramuscular injections of RDA. The effect of RDA on the severity of H. felis colonization and the degree of gastric inflammation was assessed 2 weeks later. RDA caused a significant decrease in H. felis colonization without significantly altering the associated inflammation. RDA did not alter the H. felis-specific immunoglobulin G1 (IgG1), IgG2a, and IgA responses in the serum but was associated with an increase in gamma interferon (IFN-gamma)-producing CD8(+) spleen cells. To determine if IFN-gamma or Th1 cytokines were involved in the response to RDA, we examined RDA treatment of H. felis infection in mice lacking either IFN-gamma or interleukin-12 (IL-12). RDA failed to alter H. felis colonization in either of these two mouse strains. Thus, viral infection of mice chronically infected with H. felis led to a significant decrease in H. felis colonization in an IFN-gamma- and IL-12-dependent manner. These results demonstrate that Th1 responses associated with systemic viral infection can influence an established H. felis infection.

Does quantitative serologic testing for Helicobacter pylori predict peptic ulcer disease in cirrhosis?

BACKGROUND

Helicobacter Pylori is strongly associated with peptic ulcer disease. A correlation between high IgG serum antibody concentrations and a clinical diagnosis has been reported. It has been recognized that peptic ulcer disease occurs with increased frequency in cirrhosis. In this study, we attempted to establish a relation between the magnitude of serum IgG antibody to H pylori and the endoscopic diagnoses in H pylori-infected cirrhotic patients.

METHODS

All cirrhotic patients who had undergone esophagogastroduodenoscopy with a positive H pylori IgG serology and who did not receive anti-H pylori treatment or take medications noxious to the gastroduodenal mucosa were included in the study. H pylori IgG serology was determined by an enzyme-linked immunosorbent assay with values of greater than 50 units/mL being seropositive. The functional reserve of cirrhosis was classified by modified Pugh-Child criteria.

RESULTS

One hundred four seropositive cirrhotic patients were recruited. The serum IgG titers ranged from 51 to 1200 units/mL with a peak frequency at 50 to 99 units/mL (35. 6%). Statistical analysis did not reveal any relation between the quantitative H pylori IgG values and the endoscopic diagnoses, which included gastric ulcers, duodenal ulcers, gastroduodenal erosions, and normal findings.

CONCLUSIONS

In cirrhosis, the magnitude of H pylori IgG serology cannot be used to predict the presence or absence of peptic ulcer disease.

Cellular Immune Responses Are Essential for the Development of Helicobacter felis-Associated Gastric Pathology

The bacteria Helicobacter pylori is a major human pathogen that infects over half of the world’s population. Infection initiates a series of changes in the gastric mucosa, beginning with atrophic gastritis and leading in some patients to peptic ulcer disease, mucosa-associated lymphomas, and gastric adenocarcinoma. Although this cascade of events clearly occurs, little is known about the role of the host immune response in disease progression. We have utilized the C57BL/6 Helicobacter felis mouse model to critically analyze the role of the adaptive immune response in the development of Helicobacter-associated gastric pathology. Infection of B and T cell-deficient RAG-1−/− mice or T cell-deficient TCRβδ−/− mice with H. felis resulted in high levels of colonization, but no detectable gastric pathology. Conversely, infection of B cell-deficient μMT mice resulted in severe gastric alterations identical with those seen in immunocompetent C57BL/6-infected mice, including gastric mucosal hyperplasia and intestinal metaplasia. These results demonstrate that the host T cell response is a critical mediator of Helicobacter-associated gastric pathology, and that B cells and their secreted Abs are not the effectors of the immune-mediated gastric pathology seen after H. felis infection. These results indicate that in addition to specific Helicobacter virulence factors, the host immune response is an important determinant of Helicobacter-associated disease.

Helicobacter pylori: from art to a science

Helicobacter pylori infection is widely prevalent especially in developing countries. Increasing knowledge of the pathophysiology associated with H. pylori is leading to an understanding of the mechanisms of mucosal inflammation and gastritis and how this leads to peptic ulcer disease, gastric mucosal associated lymphoid tissues (MALT), lymphoma and gastric cancer. More accurate diagnostic testing for the infection is now possible with both endoscopic and non-endoscopic tests to identify patients most appropriate for eradication therapy. Modern treatments tend to overcome the problems of metronidazole resistance and compliance seen with two week bismuth triple therapy and widely studied is a proton pump inhibitor given with clarithromycin and amoxicillin or metronidazole for one week. These achieve amongst the highest eradication rates and have also been shown to be cost effective. This paper reviews these recent advances and addresses areas of clinical interest and future directions.

Helicobacter pylori infection enhances mucosal interleukin-1 beta, interleukin-6, and the soluble receptor of interleukin-2

It is thought that Helicobacter pylori colonization of the gastric mucosa might stimulate the production of several cytokines, which might trigger and maintain the gastric inflammation associated with Helicobacter pylori infection. In the present study we evaluated interleukin-1 beta. interleukin-6, and the soluble receptor of interleukin-2 both in mucosal homogenates and in the sera of Helicobacter pylori-infected (39 cases) and uninfected (40 cases) patients to investigate whether there was any relationship between variations in cytokines and (1) the severity of Helicobacter pylori-associated gastritis or (2) CagA-positive Helicobacter pylori strains. Mucosal, but not serum levels of interleukins-1 and -6 and interleukin-2 receptor were significantly higher in infected than uninfected patients. Serum levels of Helicobacter pylori antibodies were significantly higher in infected than uninfected patients. These levels correlated with mucosal interleukin-1 beta. The degree of antral or body inflammatory grade was higher in infected than in uninfected patients; cytokines levels were higher in patients with high-grade gastritis, most of whom were Helicobacter pylori positive. Patients infected with CagA-positive strains also had higher levels of interleukin-1 beta, but not of interleukin-2 receptor or interleukin-6. In conclusion. Helicobacter pylori infection results in a local increase in interleukins-1 beta and -6 and interleukin-2 receptor associated with high-grade mucosal inflammation. Interleukin-1 beta seems to favor anti-Helicobacter pylori antibody production, and mucosal levels are enhanced mainly in patients infected with cytotoxic Helicobacter pylori strains.

Helicobacter pylori and ulcerogenesis

The dictum "no acid-no ulcer" had, in the past, summarized the thinking concerning the pathogenesis of peptic ulcer disease. It is now recognized that infection with Helicobacter pylori is the major causal factor leading to both duodenal and gastric ulceration. Infection is associated with many of the acid secretory abnormalities that have traditionally characterized peptic ulcer disease; indeed, acid secretory physiology returns to normal following bacterial eradication. Since not all individuals infected with H. pylori develop ulcers, host susceptibility, bacterial virulence, and/or specific environmental factors must determine the response to infection and the ultimate clinical outcome. The relative importance of these factors and their complex interactions remain to be determined. H. pylori infection produces tissue damage indirectly because the organism does not directly invade gastroduodenal tissue. A variety of bacterial enzymes, toxins, and inflammatory mediators produced in response to bacterial colonization challenge the integrity of host mucosal defenses. In a susceptible host, breached defenses render epithelium more vulnerable to acid injury and ulcer development. Eradication of H. pylori leads to rapid ulcer healing and reversal of tissue injury, thereby obviating ulcer recurrence.

Clarithromycin and omeprazole as helicobacter pylori eradication therapy in patients with H. pylori-associated gastric disorders

Helicobacter pylori is susceptible to many antibacterial drugs in vitro but has proved difficult to eradicate in vivo. The macrolide clarithromycin has good activity against H. pylori in vitro and has demonstrated the highest eradication rate for any antibacterial monotherapy in vivo. However, it is clear that antibacterial monotherapy is not a sufficiently effective treatment for patients with H. pylori infection. The suggestion that high intragastric acidity impairs the action of antibacterial drugs led to the evaluation of combination H. pylori eradication regimens including H+,K+-ATPase inhibitors and antibacterial drug(s) with or without bismuth compounds. Noncomparative studies evaluating the efficacy of dual therapy with clarithromycin plus omeprazole in patients with H. pylori infection have reported eradication rates of between 58 and 83% > or = 4-weeks after therapy. In comparative studies, clarithromycin plus omeprazole was at least as effective as amoxicillin plus omeprazole. However, direct comparisons have shown that eradication rates achieved by dual therapy are not as high as those achieved by triple therapy. Indeed, triple therapy with clarithromycin plus omeprazole in combination with amoxicillin or a nitroimidazole has achieved eradication rates of up to 100%. Although 14-day triple drug regimes were initially considered necessary for effective eradication, it now seems clear that 7-day regimes are equally effective. Factors known to influence response to H. pylori eradication therapy include bacterial resistance and patient compliance. A review of 4 studies evaluating the efficacy of dual eradication therapy with clarithromycin plus omeprazole reported an overall incidence of adverse events (patient or investigator reported, whether related to treatment or not) of 45%. The most common adverse event was taste disturbance (an adverse event commonly reported during the development of clarithromycin); nausea, headache, diarrhoea, vomiting and abdominal pain occurred less frequently. Although dual therapy might be expected to cause fewer adverse events than triple therapy this has not been the case in direct comparisons conducted to date. Thus, although clarithromycin plus omeprazole is associated with an H. pylori eradication rate of approximately 70%, 1 week of triple therapy with these 2 drugs together with amoxicillin or a nitroimidazole, which eradicates the organism in approximately 90% of cases, may represent optimal H. pylori eradication therapy.

Effect of IL-4 on peripheral blood lymphocyte proliferation: implication in immunopathogenesis of H. pylori infection

Interleukin (IL) 4 is a type 2 cytokine which has a negative immunoregulatory role in human infection. IL-4 suppresses the production of interferon-gamma and enhances IL-10 synthesis. However, the effect of IL-4 on proliferative response of lymphocytes remains to be elucidated. We have previously reported an increase in production of IL-4 in subjects with Helicobacter pylori (H. pylori) infection. To evaluate whether the increased IL-4 is responsible for the down-regulation of immune responses in H. pylori infection, we observed the proliferative response of peripheral blood lymphocytes (PBL) co-cultured with phythaemagglutinin (PHA) or H. pylori in the presence and absence of added IL-4. As we have previously shown, PHA and H. pylori may increase PBL proliferation (P < 0.001). An increase in PBL proliferation was observed when PBL were co-cultured with PHA (P < 0.001) or H. pylori (P < 0.001) in the presence of IL-4 compared to that in the absence of IL-4. The optimal dose of IL-4 to give maximal lymphocyte proliferation is 50 pg/ml for the PHA-stimulated group or 100 pg/ml for the H. pylori-stimulated group. The data suggest that the increased IL-4 does not directly contribute to suppressed lymphocyte proliferation in H. pylori infection. Further studies will be required to determine the role of IL-4 in other aspects of down-regulation of immune responses in H. pylori infection.