Country-specific constancy by age in cagA+ proportion of Helicobacter pylori infections

Infection by CagA-Positive Helicobacter pylori Strains and Bone Fragility: A Prospective Cohort Study

Helicobacter pylori (HP) infection is a common and persistent disorder acting as a major cofactor for the development of upper gastrointestinal diseases and several extraintestinal disorders including osteoporosis. However, no prospective study assessed the effects of HP on bone health and fracture risk. We performed a HP screening in a population-based cohort of 1149 adults followed prospectively for up to 11 years. The presence of HP infection was assessed by serologic testing for serum antibodies to HP and the cytotoxin associated gene-A (CagA). The prevalence of HP infection did not differ among individuals with normal bone mineral density (BMD), osteoporosis, and osteopenia. However, HP infection by CagA-positive strains was significantly increased in osteoporotic (30%) and osteopenic (26%) patients respect to subjects with normal BMD (21%). Moreover, anti-CagA antibody levels were significantly and negatively associated with lumbar and femoral BMD. Consistent with these associations, patients affected by CagA-positive strains had a more than fivefold increased risk to sustain a clinical vertebral fracture (HR 5.27; 95% CI, 2.23-12.63; p < .0001) and a double risk to sustain a nonvertebral incident fracture (HR 2.09; 95% CI, 1.27-2.46; p < .005). Reduced estrogen and ghrelin levels, together with an impaired bone turnover balance after the meal were also observed in carriers of CagA-positive HP infection. HP infection by strains expressing CagA may be considered a risk factor for osteoporosis and fractures. Further studies are required to clarify in more detail the underlying pathogenetic mechanisms of this association. © 2020 American Society for Bone and Mineral Research (ASBMR).

Is the Utilization of Helicobacter pylori Stool Antigen Tests Appropriate in an Urban Canadian Population?

OBJECTIVES

Helicobacter pylori stool antigen test (HpSAT) appropriateness was investigated by assessing its testing and positivity rates in Calgary, Canada.

METHODS

The laboratory information system was accessed for all patients who received an HpSAT in 2018. Testing volume, test results, age, and sex of patients were collected. Sociodemographic risk factors and geospatial analysis were performed by matching laboratory data to the 2016 census data. Testing appropriateness was defined as a concordance between testing and positivity rates for each sociodemographic variable.

RESULTS

In 2018, 25,518 H pylori stool antigen tests were performed in Calgary, with an overall positivity rate of 14.7%. Geospatial mapping demonstrated significant distribution variations of testing and positivity rates of HpSAT in the city. Certain sociodemographic groups studied (eg, recent immigrants) appeared to be appropriately tested (testing rate relative risk [RR] = 2.26, positivity rate RR = 4.32; P < .0001), while other groups (eg, male) may have been undertested (testing rate RR = 0.85, positivity rate RR = 1.14; P < .0001).

CONCLUSIONS

Determining concordance of testing and positivity rate of a laboratory test can be used for assessing testing appropriateness for other diseases in other jurisdictions. This study demonstrated some at-risk patients may be missed for H pylori testing.

Correlates of infection with Helicobacter pylori positive and negative cytotoxin-associated gene A phenotypes among Arab and Jewish residents of Jerusalem

We examined the prevalence and correlates of Helicobacter pylori (H. pylori) infection according to cytotoxin-associated gene A (CagA) phenotype, a main virulence antigen, among the ethnically diverse population groups of Jerusalem. A cross-sectional study was undertaken in Arab (N = 959) and Jewish (N = 692) adults, randomly selected from Israel's national population registry in age-sex and population strata. Sera were tested for H. pylori immunoglobulin G (IgG) antibodies. Positive samples were tested for virulence IgG antibodies to recombinant CagA protein, by enzyme-linked immunosorbent assay. Multinomial regression models were fitted to examine associations of sociodemographic factors with H. pylori phenotypes. H. pylori IgG antibody sero-prevalence was 83.3% (95% confidence interval (CI) 80.0%–85.5%) and 61.4% (95% CI 57.7%–65.0%) among Arabs and Jews, respectively. Among H. pylori positives, the respective CagA IgG antibody sero-positivity was 42.3% (95% CI 38.9%–45.8%) and 32.5% (95% CI 28.2%–37.1%). Among Jews, being born in the Former Soviet Union, the Middle East and North Africa, vs. Israel and the Americas, was positively associated with CagA sero-positivity. In both populations, sibship size was positively associated with both CagA positive and negative phenotypes; and education was inversely associated. In conclusion, CagA positive and negative infection had similar correlates, suggesting shared sources of these two H. pylori phenotypes.

When is Helicobacter pylori acquired in populations in developing countries? A birth-cohort study in Bangladeshi children

Helicobacter pylori colonization is prevalent throughout the world, and is predominantly acquired during childhood. In developing countries, >70% of adult populations are colonized with H. pylori and >50% of children become colonized before the age of 10 years. However, the exact timing of acquisition is unknown. We assessed detection of H. pylori acquisition among a birth cohort of 105 children in Mirzapur, Bangladesh. Blood samples collected at time 0 (cord blood), and at 6, 12, 18, and 24 months of life were examined for the presence of IgG and IgA antibodies to whole cell H. pylori antigen and for IgG antibodies to the CagA antigen using specific ELISAs and immunoblotting. Breast milk samples were analyzed for H. pylori-specific IgA antibodies. Cord blood was used to establish maternal colonization status. H. pylori seroprevalence in the mothers was 92.8%. At the end of the two-year follow-up period, 50 (47.6%) of the 105 children were positive for H. pylori in more than one assay. Among the colonized children, CagA prevalence was 78.0%. A total of 58 children seroconverted: 50 children showed persistent colonization and 8 (7.6%) children showed transient seroconversion, but immunoblot analysis suggested that the transient seroconversion observed by ELISA may represent falsely positive results. Acquisition of H. pylori was not influenced by the mother H. pylori status in serum or breastmilk. In this population with high H. pylori prevalence, we confirmed that H. pylori in developing countries is detectable mainly after the first year of life.

Review article: the global emergence of Helicobacter pylori antibiotic resistance

BACKGROUND

Helicobacter pylori is one of the most prevalent global pathogens and can lead to gastrointestinal disease including peptic ulcers, gastric marginal zone lymphoma and gastric carcinoma.

AIM

To review recent trends in H. pylori antibiotic resistance rates, and to discuss diagnostics and treatment paradigms.

METHODS

A PubMed literature search using the following keywords: Helicobacter pylori, antibiotic resistance, clarithromycin, levofloxacin, metronidazole, prevalence, susceptibility testing.

RESULTS

The prevalence of bacterial antibiotic resistance is regionally variable and appears to be markedly increasing with time in many countries. Concordantly, the antimicrobial eradication rate of H. pylori has been declining globally. In particular, clarithromycin resistance has been rapidly increasing in many countries over the past decade, with rates as high as approximately 30% in Japan and Italy, 50% in China and 40% in Turkey; whereas resistance rates are much lower in Sweden and Taiwan, at approximately 15%; there are limited data in the USA. Other antibiotics show similar trends, although less pronounced.

CONCLUSIONS

Since the choice of empiric therapies should be predicated on accurate information regarding antibiotic resistance rates, there is a critical need for determination of current rates at a local scale, and perhaps in individual patients. Such information would not only guide selection of appropriate empiric antibiotic therapy but also inform the development of better methods to identify H. pylori antibiotic resistance at diagnosis. Patient-specific tailoring of effective antibiotic treatment strategies may lead to reduced treatment failures and less antibiotic resistance.

Community-driven research on environmental sources of H. pylori infection in arctic Canada

The role of environmental reservoirs in H. pylori transmission remains uncertain due to technical difficulties in detecting living organisms in sources outside the stomach. Residents of some Canadian Arctic communities worry that contamination of the natural environment is responsible for the high prevalence of H. pylori infection in the region. This analysis aims to estimate associations between exposure to potential environmental sources of biological contamination and prevalence of H. pylori infection in Arctic Canada. Using data from 3 community-driven H. pylori projects in the Northwest and Yukon Territories, we estimated effects of environmental exposures on H. pylori prevalence, using odds ratios (OR) and 95% confidence intervals (CI) from multilevel logistic regression models to adjust for household and community effects. Investigated exposures include: untreated drinking water; livestock; dogs; cats; mice or mouse droppings in the home; cleaning fish or game. Our analysis did not identify environmental exposures associated clearly with increased H. pylori prevalence, except any exposure to mice or mouse droppings (OR = 4.6, CI = 1.2-18), reported by 11% of participants. Our multilevel models showed H. pylori clustering within households, but environmental exposures accounted for little of this clustering; instead, much of it was accounted for by household composition (especially: having infected household members; number of children). Like the scientific literature on this topic, our results do not clearly implicate or rule out environmental reservoirs of H. pylori; thus, the topic remains a priority for future research. Meanwhile, H. pylori prevention research should seek strategies for reducing direct transmission from person to person.

Gastric Helicobacter pylori infection associates with an increased risk of colorectal polyps in African Americans

Background

Gastric Helicobacter pylori (H. pylori) infection and colorectal polyps are more prevalent in African Americans than in the general population. We aimed to investigate whether gastric H. pylori infection is associated with colorectal polyps in African Americans.

Methods

Medical records of African Americans, 40 years and older (n = 1256) who underwent bidirectional gastrointestinal endoscopy on the same day were reviewed. H. pylori status was assessed by immunohistochemistry on gastric specimens. Colorectal polyps were confirmed by histological examination of colorectal biopsies. A subset of serum samples from healthy and polyp-bearing patients (n = 163) were analyzed by ELISA for anti-H. pylori and anti-CagA antibodies. The crude and adjusted effect of H. pylori on the risk of colorectal adenoma and polyp were computed by logistic regression models.

Results

The prevalence of colorectal polyps and adenomas were 456 (36%) and 300 (24%) respectively. Colorectal polyps were more prevalent in gastric H. pylori infected than non-infected subjects [43% vs. 34%; Odds Ratio (OR) (95% CI): 1.5 (1.2-1.9), P = 0.001]. Patients with H. pylori-associated chronic active gastritis were at high risk to have adenomas [Unadjusted OR (95% CI): 1.3 (1.0-1.8); P = 0.04]. There was no difference in histopathology, size, or location of polyps with respect to H. pylori status. Gastric H. pylori infection, age, male gender and high risk clinical presentations were independent risk factors for colorectal polyps. Serological testing also revealed a higher prevalence of H. pylori and its toxin Cag-A in polyp patients vs. non polyp patients’ sera, although in a non-statistically significant manner.

Conclusions

This study showed that current gastric H. pylori infection is associated with an increased risk of colorectal polyps in African Americans. Patients with H. pylori induced gastritis may benefit from early screening colonoscopy as a preventative measure for colorectal cancer.

Platelet Count Response to Helicobacter pylori Eradication in Iranian Patients with Idiopathic Thrombocytopenic Purpura

Idiopathic thrombocytopenic purpura (ITP) is an autoimmune hematological disorder characterized by auto antibody-mediated platelet destruction. Although the main cause of ITP remains unclear, but its relationship with some infection was demonstrated. In recent years, many studies have demonstrated improvement of platelet counts in ITP patients after treating Helicobacter pylori infection. The aim of this study was to investigate the effects of H. pylori eradication on platelet count response in Iranian ITP patients.

A total of 26 patients diagnosed with both ITP and H. pylori infection. ITP were diagnosed whose platelet counts were less than 100×10³/μL. These patients were tested for H. pylori infection by Urea Breath Test and serum H. pylori antibody. All patients received triple therapy for 7 or 14 days to eradicate H. pylori infection. These patients followed for six months.

Prevalence of H. pylori was 67.3%. H. pylori eradication achieved in 89.5% (26/29). Of the 26 patients, 15 (57.7%) exhibited a complete response (CR) and 11 (42.3%) were unresponsive. We did not find partial responders. There was a significant difference in the baseline platelet count of responders and non-responders patients (p<0.001). All responders had platelet count ≥50×10³/μL and all non-responders had platelet count <50×10³/μL.

Results of this study revealed that eradication therapy of H. pylori infection can improve platelet counts in ITP patients especially with mild thrombocytopenia and support routine detection and treatment of H. pylori infection in ITP patients in populations with a high prevalence of this infection.

Helicobacter pylori and the birth cohort effect: evidence for stabilized colonization rates in childhood

BACKGROUND

The prevalence of Helicobacter pylori has declined over recent decades in developed countries. The increasing prevalence with age is largely because of a birth cohort effect. We previously observed a decline in H. pylori prevalence in 6- to 8-year-old Dutch children from 19% in 1978 to 9% in 1993. Knowledge about birth-cohort-related H. pylori prevalence is relevant as a predictor for the future incidence of H. pylori-associated conditions.

AIM

The aim of this study was to investigate whether the birth cohort effect of H. pylori observed between 1978 and 1993 continued in subsequent years.

METHODS

Anti-H. pylori IgG antibodies and anti-CagA IgG antibodies were determined in serum samples obtained in 2005/2006 from 545 Dutch children aged 7-9 years who participated in the Prevention and Incidence of Asthma and Mite Allergy birth cohort. The H. pylori and CagA antibodies were determined by enzyme-linked immunosorbent assays that have been extensively validated in children, with a 94% sensitivity for H. pylori colonization and a 92.5% sensitivity for colonization with a cagA-positive strain.

RESULTS

Of the 545 children (M/F 300/245), most (91.5%) were of Dutch descent. The H. pylori positivity rate was 9% (95% CI 6.6-11.4%). The prevalence of CagA antibodies was 0.9% (95% CI 0.1-1.6%). No significant differences were demonstrated in H. pylori and cagA prevalence in relation to gender or ethnicity.

CONCLUSION

The prevalence of H. pylori in childhood has remained stable in the Netherlands from 1993 to 2005, suggesting a stabilization of the previously decreasing trend in subsequent birth cohorts. This finding may reflect stabilization in determinants such as family size, housing, and hygienic conditions (or offset by day care). If confirmed in other populations in developed countries, it implies that colonization with H. pylori will remain common in the coming decades. Remarkably however, the rate of colonization with cagA(+) H. pylori strains has become very low, consistent with prior observations that cagA(+) strains are disappearing in Western countries.

Infection with Helicobacter pylori is associated with protection against tuberculosis

Background

Helicobacter pylori, a lifelong and typically asymptomatic infection of the stomach, profoundly alters gastric immune responses, and may benefit the host in protection against other pathogens. We explored the hypothesis that H. pylori contributes to the control of infection with Mycobacterium tuberculosis.

Methodology/Principal Findings

We first examined M. tuberculosis-specific IFN-γ and H. pylori antibody responses in 339 healthy Northern Californians undergoing routine tuberculin skin testing. Of 97 subjects (29%) meeting criteria for latent tuberculosis (TB) infection (LTBI), 45 (46%) were H. pylori seropositive. Subjects with LTBI who were H. pylori-seropositive had 1.5-fold higher TB antigen-induced IFN-γ responses (p = 0.04, ANOVA), and a more Th-1 like cytokine profile in peripheral blood mononuclear cells, compared to those who were H. pylori seronegative. To explore an association between H. pylori infection and clinical outcome of TB exposure, we evaluated H. pylori seroprevalence in baseline samples from two high risk TB case-contact cohorts, and from cynomolgus macaques experimentally challenged with M. tuberculosis. Compared to 513 household contacts who did not progress to active disease during a median 24 months follow-up, 120 prevalent TB cases were significantly less likely to be H. pylori infected (AOR: 0.55, 95% CI 0.0.36–0.83, p = 0.005), though seroprevalence was not significantly different from non-progressors in 37 incident TB cases (AOR: 1.35 [95% CI 0.63–2.9] p = 0.44). Cynomolgus macaques with natural H. pylori infection were significantly less likely to progress to TB 6 to 8 months after M. tuberculosis challenge (RR: 0.31 [95% CI 0.12–0.80], p = 0.04).

Conclusions/Significance

H. pylori infection may induce bystander effects that modify the risk of active TB in humans and non-human primates. That immunity to TB may be enhanced by exposure to other microbial agents may have important implications for vaccine development and disease control.

Platelet count response to H. pylori treatment in patients with immune thrombocytopenic purpura with and without H. pylori infection: a systematic review

Eradication of H. pylori improves thrombocytopenia in some patients with immune thrombocytopenic purpura by mechanisms that remain obscure. Platelet count responses may occur independently of H. pylori infection as a result of the immune modulating effects of macrolide antimicrobials or the removal of other commensal bacteria. We performed a systematic review of the literature to determine the effect of H. pylori eradication therapy in patients with immune thrombocytopenic purpura by comparing the platelet response in patients who were, and who were not infected with H. pylori. MEDLINE, EMBASE, Cochrane central registry and abstracts from the American Society of Hematology (from 2003) were searched in duplicate and independently without language or age restrictions. Eleven studies, 8 from Japan, were included enrolling 282 patients with immune thrombocytopenic purpura who received eradication therapy; 205 were H. pylori-positive and 77 were H. pylori-negative. The odds of achieving a platelet count response following eradication therapy were 14.5 higher (95% confidence interval 4.2 to 83.0) in patients with H. pylori infection (51.2% vs. 8.8%). No study reported bleeding or quality of life. Adverse events were reported in 12 patients. H. pylori eradication therapy was of little benefit for H. pylori-negative patients. These findings strengthen the causal association between H. pylori infection and immune thrombocytopenia in some patients. Randomized trials are needed to determine the applicability of H. pylori eradication therapy across diverse geographical regions.

Platelet count response to H. pylori treatment in patients with immune thrombocytopenic purpura with and without H. pylori infection: a systematic review

Eradication of H. pylori improves thrombocytopenia in some patients with immune thrombocytopenic purpura by mechanisms that remain obscure. Platelet count responses may occur independently of H. pylori infection as a result of the immune modulating effects of macrolide antimicrobials or the removal of other commensal bacteria. We performed a systematic review of the literature to determine the effect of H. pylori eradication therapy in patients with immune thrombocytopenic purpura by comparing the platelet response in patients who were, and who were not infected with H. pylori. MEDLINE, EMBASE, Cochrane central registry and abstracts from the American Society of Hematology (from 2003) were searched in duplicate and independently without language or age restrictions. Eleven studies, 8 from Japan, were included enrolling 282 patients with immune thrombocytopenic purpura who received eradication therapy; 205 were H. pylori-positive and 77 were H. pylori-negative. The odds of achieving a platelet count response following eradication therapy were 14.5 higher (95% confidence interval 4.2 to 83.0) in patients with H. pylori infection (51.2% vs. 8.8%). No study reported bleeding or quality of life. Adverse events were reported in 12 patients. H. pylori eradication therapy was of little benefit for H. pylori-negative patients. These findings strengthen the causal association between H. pylori infection and immune thrombocytopenia in some patients. Randomized trials are needed to determine the applicability of H. pylori eradication therapy across diverse geographical regions.

Effects of eradication of Helicobacter pylori infection in patients with immune thrombocytopenic purpura: a systematic review

Whether the eradication of Helicobacter pylori infection can increase the platelet count in patients with immune thrombocytopenic purpura (ITP) is still a controversial issue. To provide evidence-based guidance, we performed a systematic review of the literature published in English, selecting articles reporting 15 or more total patients. We identified 25 studies including 1555 patients, of whom 696 were evaluable for the effects of H pylori eradication on platelet count. The weighted mean complete response (platelet count ≥ 100 × 109/L) and overall response (platelet count ≥ 30 × 109/L and at least doubling of the basal count) were 42.7% (95% confidence interval [CI], 31.8%-53.9%) and 50.3% (95% CI, 41.6%-59.0%), respectively. In 222 patients with a baseline platelet count less than 30 × 109/L, the complete response rate was 20.1% (95% CI, 13.5%-26.7%) and the overall response rate was 35.2% (95% CI, 28.0%-42.4%). The response rate tended to be higher in countries with a high background prevalence of H pylori infection and in patients with milder degrees of thrombocytopenia. These findings suggest that the detection and eradication of H pylori infection should be considered in the work-up of patients with seemingly typical ITP.

Cross-reaction of antibody against Helicobacter pylori urease B with platelet glycoprotein IIIa and its significance in the pathogenesis of immune thrombocytopenic purpura

Many clinical investigations have suggested that Helicobacter pylori (H. pylori) infection might be associated with immune thrombocytopenic purpura (ITP), but its role in the pathogenesis of ITP is unsettled. In this study, we cultured H. pylori, produced recombinant H. pylori urease (ure) B, and then prepared monoclonal antibody (MoAb) against ureB, 1F11, both 1F11 and MoAb against human platelet glycoprotein (GP) IIIa, SZ21, could bind to the band of GP IIIa of normal platelet lysate, but not to that from a patient with Glanzmann thrombasthenia (GT) whose GP IIb-IIIa complex was absent. Flow cytometry showed that normal platelets were reacted with 1F11 and SZ21, while GT platelets were not. In immuno-radiometric assay, the binding of (125)I-labeled 1F11 to GP IIIa was higher than that to GP Ib, GP IIb, GP VI, and P-selectin. 1F11 could partly compete with SZ21 in a binding to platelet surface. In addition, 1F11 inhibited platelet aggregation induced by adenosine diphosphate, but had no effect on platelet P-selectin expression or Thromboxane B(2) production of platelets. These results indicate that H. pylori ureB antibody could cross-react with human platelet GP IIIa and partly inhibit platelet aggregation. UreB may be a crucial component of H. pylori involved in the pathogenesis of a subset of ITP.

Outcome of immunosuppressive therapy with Helicobacter pylori eradication therapy in patients with chronic idiopathic thrombocytopenic purpura

We initiated this study to investigate whether combining Helicobacter pylori eradication with immunosuppressive therapy provides an additional benefit to patients with idiopathic thrombocytopenic purpura (ITP) that has relapsed or has not responded to steroid and/or danazol therapy in patients who have H. pylori infection. Thirty- four patients with chronic ITP that had relapsed or failed to steroid and/or danazol therapy were assessed for H. pylori infection. Of the 21 confirmed cases, 12 patients were given H. pylori eradication therapy alone (EA), while 9 patients received eradication therapy combined with immunosuppressive therapy (EI). The response rate was not significantly different between patients in the EA and those in the EI group (41.7% in the EA group vs. 66.7% in the EI group, p=0.345). The median platelet count at 6 months after therapy was higher in the EI group patients (75 x 10(9)/L in the EI group patients vs. 18 x 10(9)/L in the EA group patients, p=0.028). The median response duration was also longer in the EI group patients (9 months in the EI group patients vs. 3 months in the EA group patients, p=0.049). These results show that a significant benefit is gained by the use of H. pylori eradication combined with immunosuppressive therapy over the use of eradication therapy alone for patients with chronic ITP.

Helicobacter pylori infection in Canadian and related Arctic Aboriginal populations

In 2006, the Canadian Helicobacter Study Group identified Aboriginal communities among Canadian population groups most at risk of Helicobacter pylori-associated disease. The objective of this systematic review was to summarize what is known about the H pylori-associated disease burden in Canadian and related Arctic Aboriginal populations to identify gaps in knowledge. Six health literature databases were systematically searched to identify reports on H pylori prevalence in Canadian population groups, or any topic related to H pylori in Canadian Aboriginals, Alaska Natives or Aboriginals of other Arctic regions. Identified reports were organized by subtopic and summarized in narrative form. Key data from studies of H pylori prevalence in defined populations were summarized in tabular form. A few Arctic Aboriginal communities were represented in the literature: two Canadian Inuit; one Canadian First Nation; two Greenland Inuit; one Russian Chutkotka Native; and several Alaska Native studies. These studies uniformly showed elevated H pylori prevalence; a few studies also showed elevated occurrence of H pylori-related diseases and high rates of treatment failure. Based on the evidence, it would be warranted for clinicians to relax the criteria for investigating H pylori and related diseases in patients from Arctic Aboriginal communities, and to pursue post-therapy confirmation of eradication. Additional community-based research is needed to develop public health policies for reducing H pylori-associated health risks in such communities.

Dyspepsia in homeless adults

GOALS

To determine the prevalence of and risk factors for dyspepsia in a representative sample of homeless persons using shelters in Toronto, Canada.

BACKGROUND

Homeless people have many risk factors for dyspepsia, but little information is available on gastrointestinal symptoms in this population.

STUDY

Cross-sectional survey of a representative sample of 100 homeless adults, with serologic testing for Helicobacter pylori infection.

RESULTS

The prevalence of moderate, severe, or very severe symptoms within the past 3 months was 18% for upper stomach pain and 59% for any dyspeptic symptom. Nonwhite ethnicity (odds ratio, 3.5; 95% confidence interval, 1.1-10.9) and a history of gastrointestinal disease (odds ratio, 8.6; 95% confidence interval, 2.5-29.6) were significantly associated with moderate to very severe upper stomach pain. H. pylori infection was identified in 31% of participants but was not significantly associated with dyspepsia.

CONCLUSIONS

Dyspepsia is a common problem among homeless adults in Toronto. The presence of upper stomach pain is most strongly associated with a history of gastrointestinal disease.

Is Helicobacter pylori infection a risk factor for acute coronary syndromes?

OBJECTIVES

To elucidate risk factors for acute coronary syndromes (ACS), the present study examined whether Helicobacter pylori infection is a risk factor for patients with ACS.

METHODS

We studied 33 male patients with acute coronary syndromes (ACS). All patients were incidence cases of ACS that they did not have a past history of IHD and were at the first onset of ACS. A control group was consisted of 66 males. Controls were at random selected from outpatients. All controls had normal resting electrocardiogram and had no history of IHD. H. pylori seropositivity was determined by an IgG-specific enzyme linked immunosorbent assay (ELISA). We serologically confirmed the presence of antibodies specific to the antigen CagA of H. pylori, using CagA ELISA.

RESULTS

Seropositive rate of IgG antibodies in patients with ACS was 87.9%. A rate of in controls was 66.7%. After adjustment for age, a statistically significant association was found in H. pylori seropositivity between ACS and controls (OR, 3.74; 95% CI, 1.15-12.13). This relation was also significant after adjusted for potential confounding factors (OR, 4.09; 95% CI, 1.10-15.17). Anti-CagA positive H. pylori were significantly recognized in ACS (adjusted OR, 3.58; 95% CI, 1.08-11.82). However, this significant association was disappeared after adjusted for potential confounding factors (P=0.054).

CONCLUSIONS

We confirmed a significant link between H. pylori infection and ACS. H. pylori infection is likely to be a risk factor for ACS.

Effect modification by vitamin C on the relation between gastric cancer and Helicobacter pylori

A hospital-based case-control study of 295 cases with histologically confirmed gastric cancer and age and sex-matched controls was conducted to evaluate the effect of dietary vitamin C intake upon the relation between Helicobacter pylori infection and gastric cancer in Korea in 1997-1998. Anti-H. pylori IgG was detected by ELISA. A food frequency questionnaire, and a questionnaire on demographic factors, including past medical history, smoking, alcohol consumption, and life style was also administered. The prevalences of H. pylori IgG in cases and controls were 80.7% and 71.2%, respectively, and the odds ratio (OR) of H. pylori for gastric cancer was 1.68 (95% confidence interval (CI): 1.14, 2.44), after adjusting for age, sex, educational level, and a past medical history of gastritis or gastric ulcer. In a stratified analysis, H. pylori seropositivity was found to be a significant risk factor for gastric cancer in the low vitamin C intake group (OR = 4.68; 95% CI: 1.97, 11.1), but not in the high vitamin C intake group (OR = 0.72; 95% CI: 0.32, 1.65). Vitamin C intake was found to modify the relation between H. pylori and gastric cancer.

The presence of thecagpathogenicity island is associated with increased superoxide anion radical scavenging activity byHelicobacter pylori

Reactive oxygen species (ROS) generated by Helicobacter pylori infection have been suggested to be important factors in induction of gastric malignancies. Utilizing electron spin resonance spectrometry, H. pylori-dependent radical formation and hydroxyl- and superoxide-anion radical scavenging activity was investigated. In contrast to previous reports, we found that H. pylori does not produce ROS, but displays superoxide scavenging activity. This scavenging activity was increased in cag-positive H. pylori strains when compared to strains lacking an intact cag pathogenicity island, and was dependent on enzyme activity. We hypothesize that the increased scavenging activity of cag-positive H. pylori strains is an adaptation to the increased inflammatory response associated with the cag-positive genotype of H. pylori.

Molecular mimicry by Helicobacter pylori CagA protein may be involved in the pathogenesis of H. pylori-associated chronic idiopathic thrombocytopenic purpura

The eradication of Helicobacter pylori often leads to platelet recovery in patients with chronic idiopathic thrombocytopenic purpura (cITP). Although this clinical observation suggests the involvement of H. pylori, little is known about the pathogenesis of cITP. We initially examined the effect of H. pylori eradication on platelet counts in 20 adult Japanese cITP patients. Then, using platelet eluates as the probe in immunoblot analyses, we examined the role of molecular mimicry in the pathogenesis of cITP. Helicobacter pylori infection was detected in 75% (15 of 20) of cITP patients. Eradication was achieved in 13 (87%) of the H. pylori-positive patients, seven (54%) of which showed increased platelet counts within the 4 months following treatment. Completely responsive patients also showed significant declines in platelet-associated immunoglobulin G (PAIgG) levels. Platelet eluates from 12 (nine H. pylori-positive and three H. pylori-negative) patients recognized H. pylori cytotoxin-associated gene A (CagA) protein, and in three completely responsive patients, levels of anti-CagA antibody in platelet eluates declined after eradication therapy. Cross-reactivity between PAIgG and H. pylori CagA protein suggests that molecular mimicry by CagA plays a key role in the pathogenesis of a subset of cITP patients.

Helicobacter pylori outer membrane vesicles modulate proliferation and interleukin-8 production by gastric epithelial cells

Helicobacter pylori infection, which is always associated with gastritis, can progress to ulceration or malignancy. The diversity in clinical outcomes is partly attributed to the expression of virulence factors and adhesins by H. pylori. However, H. pylori may not have to adhere to the epithelium to cause gastritis. We hypothesize that outer membrane vesicles (OMV), which are constantly shed from the surface of H. pylori, play a role as independent activators of host cell responses. In this study, we found that low doses of OMV from cag PAI+ toxigenic and cag PAI- nontoxigenic strains increased proliferation of AGS gastric epithelial cells. At higher doses, we detected growth arrest, increased toxicity, and interleukin-8 (IL-8) production. The only strain differences detected were vacuolation with the toxigenic strain and higher levels of IL-8 production with OMV from the cag PAI- nontoxigenic strain. In summary, we suggest that constitutively shed OMV play a role in promoting the low-grade gastritis associated with H. pylori infection.

Helicobacter pylori infection and gastric cancer: facing the enigmas

At an individual level Helicobacter pylori was associated with the occurrence of gastric cancer but in some African and Asian countries its prevalence runs with low gastric cancer rates, the so-called African and Asian enigmas. We assessed whether the association between gastric cancer and H. pylori prevalence at an area level is modified by the level of exposure to fruits and vegetables, alcohol or tobacco. Regression models were fitted to data from 58 countries using as dependent variable log transformed gastric cancer rates and as independent covariables the H. pylori prevalence, fruits and vegetables consumption, cigarette smoking, alcohol intake and interaction terms. The levels of alcohol consumption or cigarette smoking modified the association between gastric cancer and H. pylori infection. Models including H. pylori prevalence, alcohol consumption, cigarette smoking and the interaction terms H. pylori x alcohol or H. pylori x tobacco were used to compute gastric cancer incidence multiplying regression coefficients by a H. pylori prevalence of 85% (the approximate median in African countries) and the median figures observed in each continent for alcohol and tobacco availability. The expected gastric cancer incidence per 100,000 would be 5.7 assuming the alcohol and tobacco availability in African countries, 7.0 in Asia and Oceania, 16.0 in America and 26.0 in Europe. The interaction between H. pylori and cigarette or alcohol consumption may contribute to further explain the international variation in gastric cancer and the so-called African and Asian enigmas.

Colonization with cagA-positive Helicobacter pylori strains in intestinal metaplasia of the esophagus and the esophagogastric junction

OBJECTIVES

Recent studies indicate that colonization with cagA-positive Helicobacter pylori (H. pylori) strains may protect against gastroesophageal reflux disease (GERD) and its complications, but the role of cagA in the etiology of Barrett's esophagus has so far been poorly investigated. The pathogenesis of intestinal metaplasia (IM) at an endoscopically normal esophagogastric junction (EGJ) is still unclear, and the role of the H. pylori virulence factor cagA in it has not been investigated. The aim of our study was to assess the relationship between H. pylori and cagA-positive H. pylori in particular and IM at an endoscopically normal EGJ and Barrett's esophagus.

METHODS

Serum samples were obtained from 62 patients without IM, 43 patients with IM at an endoscopically normal junction, and 51 patients with Barrett's esophagus. IM was defined as presence of goblet cells with positive staining with Alcian blue. The prevalence of H. pylori and cagA was investigated by assessment of IgG antibody levels as determined by ELISA.

RESULTS

The overall H. pylori prevalence was 59% (92/156), and the cagA prevalence was 29% (46/156). Although 63% (39/62) of IM negative subjects and 74% (32/43) of those with IM at the junction were H. pylori positive, only 41% (21/51) of Barrett's patients tested positive. The differences between the IM negative and the Barrett's group (p = 0.02) and between IM at the junction and Barrett's were significant (p = 0.002). The relative cagA prevalence (percentage with cagA positivity and H. pylori positivity) was 56% (22/39) in patients who were IM negative, 59% (19/32) in those with IM at the junction, and 24% (5/21) in those with Barrett's. The prevalence of anti-CagA was significantly lower in patients with Barrett's esophagus compared with patients who were IM negative (p = 0.002) and those who had IM at the junction (p < 0.001). No difference in cagA prevalence was seen between the latter groups.

CONCLUSIONS

These findings are in line with the concept that H. pylori and cagA-positive strains in particular protect against the development of Barrett's esophagus. In contrast, our findings do not support the theory that IM at an endoscopically normal esophagogastric junction is associated with H. pylori or cagA-positive strains. IM at the junction and Barrett's esophagus seem to have different etiologies.

Transient and persistent Helicobacter pylori colonization in Native American children

Helicobacter pylori is chiefly acquired in childhood, but the exact timing of acquisition is not well understood. The main goal of this study was to assess H. pylori acquisition in a pediatric population. We studied two cohorts of Native American children: a birth cohort of 50 children and 58 older children (mean age, 53 months). We measured serum immunoglobulin G (IgG), IgM, and IgA antibodies to H. pylori whole-cell antigen and IgG antibodies to CagA. Among 44 birth cohort children monitored for more than 12 months, 24 (54.5%) had seroconversions, 7 (15.9%) were transient, and 17 (38.6%) were persistent. Among the older children, 49 (84.5%) of the 58 children were monitored for 1 year; 34 (69.4%) had H. pylori antibodies at study entry. During the next year, 7 (20.6%) children seroreverted, and of 15 initially negative children, 5 (33.3%) seroconverted. In both groups, evaluation of CagA antibodies increased the sensitivity of H. pylori detection. Serum pepsinogen I (PGI) levels in H. pylori-negative children rose significantly until age 6 months and remained constant for the next 19 months. At the time of H. pylori seroconversion, PGI peaked to levels significantly higher than in the never-seroconverted (P = 0.02) and the pre-seroconverted (P = 0.03) children, but then declined to levels paralleling those of H. pylori-negative children. Thus, H. pylori acquisition, accompanied by a transient PGI increase, was frequent in this population, especially in the second and third years of life, but often was brief.

Role of Helicobacter pylori CagA+ strains and risk of adenocarcinoma of the stomach and esophagus

Infection with Helicobacter pylori (H. pylori), especially CagA+ strains, has been associated with an increased risk of noncardia gastric adenocarcinoma. The relationship with junctional cancer (adenocarcinomas of the esophagus and gastric cardia combined) has not been adequately investigated, although some studies have reported a reduced risk associated with H. pylori and CagA seroseropositivity. We investigated this question in a subset of cases and controls from a recently completed, large population-based case-control study of gastric and esophageal adenocarcinomas in Los Angeles County. Using established antigen-specific ELISAs, serum IgG antibodies to H. pylori whole-cell antigens (Helico-G) and CagA were measured in population controls (n = 356) and patients with incident esophageal adenocarcinoma (n = 80), gastric cardia cancer (n = 87) or distal gastric cancers (noncardia gastric adenocarcinoma) (n = 127). After controlling for demographic characteristics (age, gender, race, birthplace, education), smoking and body mass index, seropositivity for H. pylori was associated with a statistically significant increased risk of distal gastric cancer (adjusted odds ratio [OR] = 1.85, 95% confidence interval [CI] = 1.03, 3.32) but the risk of junctional cancer was not increased (adjusted OR = 1.26, 95% CI = 0.82, 1.94). The risk of junctional cancer was not changed when CagA and H. pylori were both considered, but the risk of distal gastric cancer was further increased. Subjects who were seropositive for both CagA and H. pylori compared to those who were seronegative for H. pylori showed a risk of 2.20 (95% CI = 1.13, 4.26) for distal gastric cancer and 0.86 (95% CI = 0.47, 1.59) for junctional cancer. Although tests for interaction between smoking and H. pylori were not statistically significant for junctional or distal gastric cancers, risk for both tumor types tended to be higher among current smokers who were also H. pylori seropositive. In conclusion, we find no evidence that infection with CagA+ strains of H. pylori reduces risk of esophageal and gastric cardia adenocarcinoma in this population. Our findings confirm the positive association between risk of distal gastric cancer and infection with H. pylori infection, especially CagA+ strains.

Accuracy of a commercial enzyme-linked immunosorbent assay for CagA in patients from Brazil with and without gastric carcinoma

We validated a commercial enzyme-linked immunosorbent assay for the detection of anti-CagA antibodies in Brazilian patients with Helicobacter pylori infection. The test presented high sensitivity (97.4%) and specificity (88.9%) when employed in patients without gastric carcinoma. However, in gastric carcinoma patients, the test was neither sensitive nor specific enough to detect cagA-positive H. pylori infection.

Responses of endoscopy patients in Ladakh, India, to Helicobacter pylori whole-cell and Cag A antigens

Although Helicobacter pylori is a cosmopolitan colonizer of the human stomach, the responses among persons in remote populations from whom H. pylori was cultured have not been studied. We report on studies of 189 persons in the Ladakh region of India in whom serum immunoglobulin G responses to H. pylori whole-cell and Cag A antigens were measured. H. pylori was isolated from 68 of these patients. An H. pylori whole-cell antigen derived from Ladakhi strains outperformed a similar antigen from U.S. strains, as determined by antigen-specific enzyme-linked immunosorbent assays. In total, 95% of the population was seropositive, including individuals responding only to the Cag A antigen. Correlation with culture results showed that these were true positives and, therefore, that the H. pylori whole-cell serology was falsely negative in some cases. In addition to establishing a collection of H. pylori isolates from a remote area in the world, we show that use of H. pylori whole-cell and Cag A serology together increases the sensitivity for the detection of colonization.

Helicobacter pylori-specific immune responses of children: implications for future vaccination strategy

We analyzed the specific anti-Helicobacter pylori immunoglobulin G (IgG) antibody profile for a sample of 824 asymptomatic schoolchildren in southern Germany (mean age, 10.7 +/- 0.65 years) with an H. pylori-specific IgG enzyme-linked immunosorbent assay and Western blot analysis. The prevalence of infection was 19.8% (95% confidence interval, 17.1 to 22.7%). The immunoresponses were characterized predominantly by antibodies against low-molecular-mass antigens of 14 and 29 kDa, with a significant difference between children of German and Turkish nationalities (P = 0.0012 and P < 0.0001, respectively).

Study of p53 immunostaining in the gastric epithelium of cagA-positive and cagA-negative Helicobacter pylori gastritis

BACKGROUND

p53 mutations are an early event in the multistep progression of gastric carcinoma. These mutations are often present in dysplastic and intestinal metaplastic gastric epithelium. However, the presence of immunohistochemically detectable p53 protein and p53 mutations in nondysplastic/nonmetaplastic gastric mucosa is more controversial. Recent reports have suggested that immunohistochemically detectable p53 protein may be present in the gastric epithelium of Helicobacter pylori gastritis. Furthermore, because cagA-positive H. pylori is associated with greater mucosal injury but decreased apoptosis, it would be interesting to determine if this phenotype is associated with greater immunostaining of p53, as the wild-type p53 gene helps to initiate apoptosis.

METHODS

One hundred thirty-five patients with H. pylori-associated gastritis were immunohistochemically stained for p53 and quantified for the extent and intensity of the staining using a semiquantitative method (0, nil staining; 6, extensive and strong staining). The cagA status of the organism was determined by Western blot.

RESULTS

Thirty-one patients (23%) showed strong p53 staining (> or = 4 of 6) in inflamed but otherwise normal gastric epithelium. In the 123 cagA-positive H. pylori gastritis patients, the average p53 staining score was 2.5 of 6. This is significantly higher than the corresponding score of 1.7 of 6 observed in the 12 patients with cagA-negative H. pylori gastritis (P = 0.04).

CONCLUSIONS

Our results indicate that p53 protein is immunohistochemically detectable even before gastric metaplastic/dysplastic change occurs. The results also suggest that cagA-positive H. pylori might be associated with greater p53 immunohistochemical staining. This would indicate that p53 immunohistochemical staining does not reliably differentiate between gastric dysplasia and reactive inflammatory atypia. If the p53 protein detected is a consequence of mutation, this would help to explain why cagA-positive H. pylori gastritis is associated with decreased apoptosis.

Multifocal atrophic gastritis and gastric carcinoma

Gastric carcinoma remains a major cause of morbidity and mortality worldwide despite its significant decline in recent years. H. pylori infection begins with nonatrophic gastritis, and most individuals continue to have nonatrophic H. pylori gastritis throughout their lifetime. A minority of those with severe antral inflammation will develop a duodenal ulcer, and a few, for unknown reasons, may develop gastric MALT lymphoma. Others, who acquired the H. pylori infection in early childhood, develop progressive multifocal atrophic gastritis with loss of gastric glands. A small proportion of these individuals develop extensive, incomplete (type III) intestinal metaplasia, and an even smaller proportion will progress to dysplasia and intestinal-type gastric carcinoma. H. pylori-associated gastritis is also a risk factor for diffuse-type gastric carcinoma, which is not preceded by atrophy, intestinal metaplasia, or dysplasia. Appropriate screening and preventive measures should be considered in high-risk groups. It is also crucial to identify cofactors such as genetic susceptibility and environmental factors that might interact with H. pylori infection to increase gastric cancer risk. To make an impact on gastric cancer incidence and mortality, serious consideration should be given to early H. pylori eradication in high-risk groups and endoscopic surveillance according to the updated Sydney system in some patients with high-risk preneoplastic lesions, whereas dysplastic lesions should be removed without delay. Studies currently in progress may tell us whether H. pylori eradication can prevent later development of gastric carcinoma and thus eliminate a major cause of mortality worldwide.

In vivo and in vitro activation of caspase-8 and -3 associated with Helicobacter pylori infection

In vivo and in vitro studies have shown an increase in apoptosis in gastric epithelial cells in persons infected with Helicobacter pylori. H. pylori-induced activation of caspase-8 and -3 was evaluated using a human gastric adenocarcinoma cell line (AGS) and gastric tissue from humans and monkeys colonized with H. pylori. The enzymatic activity of caspase-8 was detected only in AGS cells exposed to H. pylori up to 24 h. The active form of caspase-8 was present by Western blot after exposure to H. pylori for 3 h and persisted through 24 h. Caspase-3 activity was present in AGS cells exposed to H. pylori for 3 h, reaching a maximum after 24 h (a sevenfold increase in activity). Caspase-8-mediated cleavage of procaspase-3 generated a 20-kDa band (indicative of the presence of active caspase-3) present only in AGS cells exposed to H. pylori. Active caspase-3 staining was markedly increased in gastric mucosa from infected persons and animals, compared to uninfected controls by immunohistochemistry. Stimulation of downstream events leading to apoptosis, such as the cleavage of PARP (poly adenosine-diphosphate-ribose polymerase) and DFF45 (DNA fragmentation factor 45) as a result of activation of caspase-3, was evaluated. PARP was cleaved, resulting in the presence of both an 89- and a 24-kDa band along with DFF45, resulting in the presence of 10- and 12-kDa bands only in gastric cells exposed to H. pylori. Our data show that H. pylori stimulates the activation of caspases and downstream mediators of caspase-induced apoptosis. This suggests that H. pylori-induced apoptosis is mediated through caspase pathways, which include the activation of caspase-8 and subsequent cleavage and activation of caspase-3. This is consistent with caspase-3 activation that was found in the gastric mucosa of humans and monkeys infected with H. pylori.

Intrafamilial transmission of Helicobacter pylori: the association between a parent and an offspring with respect to the presence of anti-CagA antibody

In this study, we examined whether the transmission of Helicobacter pylori occurred in married couples. We also examined whether a correlation existed between H. pylori seropositivity in a parent and an offspring, which may be related to H. pylori transmission. A cross-sectional study of residents living in a rural area in Japan was conducted in 1998. The study population consisted of 1910 volunteers, aged from 22 to 79 years, residing in this area. We serologically confirmed the presence of the antigen, CagA (cytotoxin-associated gene A), of H. pylori, using a recombinant CagA antigen, in addition to examining for antibodies to H. pylori, as determined by an IgG-specific enzyme immunoassay. The data were analyzed using logistic regression models. A significant association of H. pylori seropositivity was observed ( P < 0.001) in married couples, but no significant difference with respect to the presence of anti-CagA antibodies was observed in the married couples with H. pylori seropositive results ( P = 0.053). The odds ratio was 8.08 (95% confidence interval [CI], 1.39-40.05) for infection in offspring with seropositive mothers and 2.93 (95% CI, 0.25-33.85) for infection in offspring with seropositive fathers when compared with seronegative fathers or mothers as the reference. There was a concordance between the presence or absence of anti-CagA antibodies in 11 of 13 groups of mothers and offspring (84.6%) compared with concordance in 6 of 14 groups of fathers and offspring (42.9%; P < 0.05). Our results suggest that maternal influence is likely to be more powerful than paternal influence in the transmission of H. pylori.

Oesophageal and gastric cardia adenocarcinomas: analysis of regional variation using the Cancer Incidence in Five Continents database

BACKGROUND

Adenocarcinomas of the oesophagus and proximal stomach are the most rapidly increasing malignancies in some countries; however, there are no comparative studies on global disease incidence, and the relationships between these two malignancies are undefined.

METHODS

We evaluated the cumulative rates and age-specific incidence rates per 100 000 population for adenocarcinomas of the oesophagus and proximal stomach for all countries in the Cancer Incidence in Five Continents database, and compared them with rates for oesophageal squamous cell carcinoma.

RESULTS

Substantial variations in cumulative cancer rates were found between genders, between countries, between different ethnicities within the same country, and within the same ethnicity residing in different countries. Cumulative rates (ages 0-74 years) for oesophageal adenocarcinoma varied from 0 (e.g. Thailand) to 0.6 (Scotland, males, 95% CI : 0.56, 0.64); for proximal stomach cancer from 0 (Singapore, Malay females, 95% CI : -0.01, 0.11) to 0.52 (The Netherlands, males, 95% CI : 0.49, 0.55); and for oesophageal squamous cell carcinomas from 0 (non-Jews in Israel, females) to 1.84 (Brazil, Porto Alegre, males, 95% CI : 1.42, 2.26). There was a continuous increase in age-specific incidence rates with advancing age for oesophageal/proximal stomach adenocarcinomas, but a decrease in age-specific incidence rates for oesophageal squamous cell carcinoma after age 75 years. The cumulative rate trends for adenocarcinomas of the oesophagus and proximal stomach were often dissimilar, and varied by country, gender, and ethnicity.

CONCLUSIONS

These results suggest that different risk factors may be associated with adenocarcinomas of the oesophagus versus the proximal stomach; the marked rate variation implies a substantial environmental component to the recent incidence changes.

Helicobacter pylori prevalence and CagA status among children in two counties of China with high and low risks of gastric cancer

BACKGROUND

Studies in adult populations in selected countries with widely varying rates of gastric cancer have shown a weak correlation between gastric cancer mortality rates and the prevalence of CagA+ strains of H. pylori. However, only limited data are available in ethnically homogenous populations with varying rates in the same region. METHODS; We compared the prevalence of H. pylori in general and of CagA+ strains in particular among children in Shandong Province, China in areas at high (Linqu County) and low risk (Cangshan County) of gastric cancer. H. pylori status among children aged 3 to 12 years was determined by 13C-UBT, and CagA status was determined by enzyme-linked immunosorbent assay (ELISA). Because of the difficulty in obtaining blood from young children aged 3 to 4 years and from some children aged 5 years, CagA status was determined among part of children 5 years old and children 6 to 12 years old. RESULTS; Among 98 children aged 3 to 12 years in Linqu, 68 (69.4%) was H. pylori-positive, as compared with 29 (28.7%) among 101 children in Cangshan. Among children positive for 13C-UBT, the proportion of the CagA+ strains were identified was 46 (88.5%) of 52 in Linqu and 13 (81.3%) of 16 in Cangshan, respectively.

CONCLUSIONS

The prevalence of H. pylori was nearly three times higher among children in Linqu than in Cangshan, which may contribute to the large differential in gastric cancer rates for two neighboring populations in Shandong Province.

Assessment of Helicobacter pylori vacA and cagA genotypes and host serological response

Helicobacter pylori strains can be distinguished by genotyping of virulence-associated genes, such as vacA and cagA. Because serological discrimination between strain types would reduce the need for endoscopy, 61 patients carrying H. pylori were studied by vacA and cagA genotyping of H. pylori in gastric biopsy specimens and by detection of specific serum antibodies. Serological responses to H. pylori were determined by Helicoblot (versions 2.0 and 2.1). Antibodies to CagA also were determined by a rapid anti-CagA assay (Pyloriset screen CagA) as well as by two noncommercially developed enzyme immunoassays, each using a recombinant CagA protein. Assessment of performance of the Helicoblot assays indicated substantial interobserver variation, with kappa values between 0.20 and 0.93. There was no relationship between the serological profiles on the Helicoblot and the genotypes from the same patients, except for strong associations between the presence of anti-CagA and the cagA-positive and vacA s1 H. pylori genotypes. Detection of anti-CagA by the five different assays varied considerably, with kappa values ranging from 0.21 to 0.78. Using the cagA genotype as the "gold standard," the sensitivity and specificity of the anti-CagA assays varied from 71.4 to 85.7% and from 54.2 to 100%, respectively. Thus, serological profiles of antibodies to H. pylori are heterogeneous and, with the exception of anti-CagA antibodies, show no relation to the H. pylori vacA and cagA genotypes. Detection of anti-CagA antibodies is strongly dependent on the test used.

Helicobacter pylori seropositivity and subsite-specific gastric cancer risks in Linxian, China

BACKGROUND

Helicobacter pylori carriage (i.e., persistent exposure to the organism without gastric epithelial cell invasion) is an established risk factor for noncardia gastric cancer. However, its association with the risk of cancer of the gastric cardia is controversial. Consequently, we designed this prospective, nested case-control study to further explore the subsite-specific gastric cancer risks associated with H. pylori seropositivity (a surrogate marker for persistent exposure).

METHODS

A total of 99 patients with gastric cardia cancer, 82 patients with noncardia gastric cancer, and 192 cancer-free subjects were selected from among the participants (n = 29 584) of a nutrition intervention trial previously conducted in Linxian, China. H. pylori seropositivity was determined by assaying for the presence of H. pylori whole cell and CagA antibodies in baseline serum samples from all subjects. Seropositivity was defined as one or both serum assays being positive. Odds ratios (ORs) for subsite-specific gastric cancer were estimated by multivariate logistic regression analyses. All statistical comparisons were two-sided (alpha =.05).

RESULTS

H. pylori seropositivity rates for subjects with gastric cardia cancer, noncardia gastric cancer, and gastric cardia and noncardia cancers combined were 70% (P =.02), 72% (P: =.01), and 71% (P =.003) compared with 56% for cancer-free control subjects. OR estimates for H. pylori seropositivity were 1.87 (95% confidence interval [CI] = 1.10 to 3.17) for gastric cardia cancer, 2.29 (95% CI = 1.26 to 4.14) for noncardia gastric cancer, and 2.04 (95% CI = 1.31 to 3.18) for gastric cardia and noncardia cancers combined.

CONCLUSIONS

H. pylori seropositivity was associated with increased risks for both gastric cardia cancer and noncardia gastric cancer in this well-characterized cohort. Thus, H. pylori carriage may increase the risk of cancer throughout the stomach.

Is Helicobacter pylori infection in childhood a risk factor for gastric cancer?

Helicobacter pylori infection is associated with chronic gastritis and peptic ulcer disease. Furthermore, the World Health Organization has classified this organism as a carcinogen for gastric cancer. H pylori infection is mainly acquired in childhood. Children with H pylori infection are asymptomatic except for a very small number that develop peptic ulcer disease. However, if H pylori gastritis is associated with gastric cancer, do pediatricians need to screen children for this infection and treat those who are infected? In an attempt to determine the significance of the association between H pylori and gastric cancer, we have reviewed all of the English language literature on this topic. H pylori infection seems to be associated with an increased risk of developing gastric cancer. However, only a small number of infected individuals (~1%) will develop gastric cancer. Furthermore, there are potential cofactors other than H pylori that could be equally important. The effect of the eradication of H pylori alone on the development of gastric cancer is unknown. Based on our knowledge to date, we suggest that it is not indicated to treat all children with H pylori infection because of the risk of developing gastric cancer or to institute a screening and treatment program.

Consensus and variable region PCR analysis of Helicobacter pylori 3' region of cagA gene in isolates from individuals with or without peptic ulcer

The clinical outcome of Helicobacter pylori infection may be associated with the cagA bacterial genotype. To investigate the cagA status of H. pylori-infected patients and the relationship between cagA and peptic ulcer disease, gastric biopsy specimens from 103 Caucasian patients in Brazil were analyzed by PCR. Since allelic variation in cagA exists and distinct H. pylori subgenotypes may circulate in different regions, PCR using primers for a variable 3' region of the cagA gene according to a Japanese methodology and for a consensus cagA 3' region used in Western methods was used for cagA detection. cagA was present in 53 (71%) of 75 H. pylori-positive cases when analyzed by the consensus region method and was associated with duodenal ulcer disease (P = 0.02), but not with gastric ulcer (P = 0.26), when compared to patients with duodenitis or gastritis. The variable region PCR method was able to detect 43 (57%) cagA-positive cases within the same group of H. pylori-positive patients and showed three subtypes of cagA (A, B/D, and C) that were not associated with clinical outcome. However, in 8 (18%) of the cases, more than one subtype was present, and an association between patients with multiple subtypes and disease outcome was observed when compared to patients with isolated subtypes (P = 0.048). cagA was a marker of H. pylori strains for duodenal ulcer disease in our population, and in spite of the differences in the 3' region of the cagA gene, the Japanese methodology was able to detect the cagA status in most cases. The presence of multiple subgenotypes of cagA was associated with gastric ulcer.

Dyspepsia is associated with CagA-positive Helicobacter pylori

OBJECTIVE

The role of Helicobacter pylori in nonulcer dyspepsia is controversial. Speculation has arisen that only strains of H. pylori carrying the CagA virulence factor are important in the development of dyspepsia. The objective of this study was to determine whether nonulcer dyspepsia correlated with CagA-positive H. pylori infection.

METHODS

A total of 435 healthy blood donors and 102 general medicine clinic respondents completed the Bowel Disease Questionnaire and the PRIME-MD survey, a validated screen for common psychiatric disorders. Subjects were classified as cases of nonulcer dyspepsia if they reported pain in the upper abdomen more than six times in the previous year and denied a past or current history of peptic ulcer disease. Study participants were tested for IgG antibodies to H. pylori and the CagA protein.

RESULTS

Clinic respondents were more likely than healthy blood donors to meet the case definition for nonulcer dyspepsia (34% vs 13%, p < 0.001), to be seropositive for H. pylori (54% vs 18%, p < 0.001), and to be CagA seropositive (41% vs 10%, p = 0.01). Logistic regression identified CagA seropositivity (p = 0.03), race (p = 0.001), and positive screens for depression (p = 0.007) or somatization (p < 0.001) as variables independently associated with nonulcer dyspepsia.

CONCLUSION

Infection with a CagA-positive strain of H. pylori is associated with a clinical diagnosis of nonulcer dyspepsia. However, nonulcer dyspepsia was also strongly and independently associated with positive screens for depression or somatization disorder as well as with ethnicity. These potential sources of variance should be considered in the design of future studies evaluating nonulcer dyspepsia.

Helicobacter pylori

H. pylori infection is now recognized as causing serious and life threatening disease in 20% to 30% of those infected. Reliable therapy is problematic. This article addresses the current approach to diagnosis and therapy and new considerations regarding whom to treat. The emphasis of the association of the gastric cancer phenotype of H. pylori infection (cagA positive H. pylori corpus gastritis) and protection against gastroesophageal reflux disease is an example of epidemiology without regard to the biology. Improvements in health and diet and an increase in body mass have accompanied the natural loss of H. pylori from the population. The search for virulence factors to help direct therapy to those who would most benefit has, to date, proved fruitless. Whenever H. pylori is diagnosed, it should be treated.

Chronic Helicobacter pylori infection induces an apoptosis-resistant phenotype associated with decreased expression of p27(kip1)

Helicobacter pylori infection is associated with the development of gastric cancer. In short-term coculture with AGS gastric cells, H. pylori inhibits cell cycle progression and induces dose-dependent apoptosis. Based on the concept that an imbalance between proliferation and apoptosis may contribute to the emergence of gastric cancer, we chronically exposed AGS cells to H. pylori as a model of chronic exposure in humans. The AGS derivatives selected by this process were stably resistant not only to H. pylori-induced apoptosis but also to apoptosis induced by other enteric bacteria and by several toxic agents including radiation and cancer chemotherapy. Like the parental AGS cells, the derivatives underwent G(1)/S-phase cell cycle inhibition in response to H. pylori. The AGS derivatives displayed a marked decrease in cellular levels of the cell cycle control protein p27(kip1). We found a similar decrease in epithelial cell p27(kip1) expression in gastric biopsy specimens from H. pylori-infected patients. These findings are consistent with observations that link decreases in the p27(kip1) level to increased susceptibility to cancer in mice with p27(kip1) deleted and to a poor prognosis of gastric cancer in humans. This is the first demonstration that bacterial infection can lead to apoptosis resistance and to cross-resistance to other inducers of apoptosis such as bacteria, chemotherapeutic agents, and radiation. The development of apoptosis resistance and downmodulation of p27(kip1) may contribute to the increased risk for gastric cancer observed in humans chronically exposed to H. pylori.

Significant association of cagA positive Helicobacter pylori strains with risk of premature myocardial infarction

OBJECTIVE

To investigate whether genetic diversity of Helicobacter pylori influences its association with coronary heart disease, and specifically whether the risk is confined to infection with the more virulent strains bearing the cytotoxin associated gene-A (cagA) antigen.

DESIGN AND SETTING

Case-control study in hospital admitting unselected patients with myocardial infarction.

METHODS AND SUBJECTS

Serological status for cagA and H pylori were determined in 342 cases of acute myocardial infarction and 214 population based control subjects free of clinical coronary heart disease.

RESULTS

38.0% of cases and 30.8% of controls were cagA seropositive (odds ratio 1.38, 95% confidence interval (CI) 0.94 to 2.01, p = 0.08). In subjects < 65 years old (153 cases, 153 controls), cagA seropositivity was associated with a 1.80-fold increase (95% CI 1.07 to 3.03, p = 0.02) in myocardial infarction risk, which increased further to 2.25-fold (95% CI 1.12 to 4.53, p = 0.01) in subjects < 55 years. There was no significant association of cagA status with classical coronary heart disease risk factors. H pylori seropositivity was present in 60.2% of cases and 53.7% of controls (odds ratio 1.12, 95% CI 0.83 to 1.51, p = 0.43). H pylori seropositivity was not increased in young cases and did not show any interaction with age.

CONCLUSIONS

The association of chronic H pylori infection with risk of myocardial infarction appears to be restricted to cagA bearing strains. The association is age dependent and stronger in younger subjects. Genetic heterogeneity of H pylori may explain some of the discordant findings with regard to the association of H pylori with coronary heart disease.

Disease-specific Helicobacter pylori virulence factors: the unfulfilled promise

A number of putative virulence factors for Helicobacter pylori have been identified including cagA, vacA and iceA. The criteria for a true virulence factor includes meeting the tests of biologically plausibility with the associations being both experimentally and epidemiologically consistent. Although disease-specific associations have been hypothesized/claimed, there are now sufficient data to conclusively state that none of these putative virulence factors have disease specificity. CagA has been claimed to be associated with increased mucosal IL-8 and inflammation, increased density of H. pylori in the antrum, duodenal ulcer (DU), gastric cancer, and protection against Barrett's cancer. Only the increase in IL-8/inflammation is direct and substantiated. Different H. pylori strains with functional cag pathogenicity islands do not vary in virulance as it has been shown that mucosal IL-8 levels are proportional to the number of cagA + H. pylori independent of the disease from which the H. pylori were obtained. It is now known that the density of either cagA + and cagA-H. pylori in the antrum of patients with H. pylori gastritis is the same. In contrast, the mean density of H. pylori in the antrum in DU is greater than in the antrum of patients with H. pylori gastritis. Of interest, the density of H. pylori is higher in the corpus of patients with H. pylori gastritis than those with DU, suggesting that acid secretion plays a critical role in these phenomena. The presence of a functional cag pathogenicity island increases inflammation and it is likely that any factor that results in an increase in inflammation also increases the risk of a symptomatic outcome. Nevertheless, the presence of a functional cag pathogenicity island has no predictive value for the presence, or the future development of a clinically significant outcome. The hypothesis that iceA has disease specificity has not been confirmed and there is currently no known biological or epidemiological evidence for a role for iceA as a virulence factor in H. pylori-related disease. The claim that vacA genotyping might prove clinically useful, e.g. to predict presentation such as duodenal ulcer, has been proven wrong. Analysis of the worldwide data show that vacA genotype s1 is actually a surrogate for the cag pathogenicity island. There is now evidence to suggest that virulence is a host-dependent factor. The pattern of gastritis has withstood the test of time for its relation to different H. pylori-related diseases (e.g. antral predominant gastritis with duodenal ulcer disease). The primary factors responsible for the different patterns of gastritis in response to an H. pylori infection are environmental (e.g. diet), with the H. pylori strain playing a lesser role. Future studies should work to eliminate potential bias before claiming disease associations. Controls must exclude regional or geographic associations related to the common strain circulation and not to the outcome. The authors must also control for both the presence of the factor and for the disease association. The study should be sufficiently large and employ different diseases and ethnic groups for the results to be robust. The findings in the initial sample (data derived hypothesis) should be tested in a new group (hypothesis testing), preferably from another area, before making claims. Finally, it is important to ask whether the results are actually a surrogate for another marker (e.g. vacA s1 for cagA) masquerading for a new finding. Only the cag pathogenicity island has passed the tests of biological plausibility (increased inflammation) and experimental and epidemiological consistency.

Atrophy and intestinal metaplasia one year after cure of H. pylori infection: a prospective, randomized study

BACKGROUND & AIMS

Helicobacter pylori-infected gastric mucosa evolves through stages of chronic gastritis, intestinal metaplasia (IM), glandular atrophy (GA), and dysplasia before carcinoma develops. We studied if H. pylori eradication would alter the course of premalignant histologic changes in the stomach.

METHODS

Volunteers from the Yantai County in China underwent upper endoscopy with biopsy specimens obtained from the antrum and corpus. H. pylori-infected subjects were randomized to receive either a 1-week course of omeprazole, amoxicillin, and clarithromycin (OAC) or placebo. At 1 year, endoscopies with biopsies were repeated.

RESULTS

A total of 587 H. pylori-infected subjects were randomized to OAC (n = 295) and placebo (n = 292). At 1 year, H. pylori was eradicated in 226 subjects assigned to OAC. In the placebo group, 245 patients remained H. pylori infected. Analysis of paired samples obtained from the same patients showed that acute and chronic gastritis decreased in both the antrum and corpus after H. pylori eradication (P<0.001) and activity of IM decreased in antrum (P = 0.014). In the H. pylori-infected group, antral biopsy specimens had more pronounced acute gastritis (P = 0.01), whereas corpus specimens showed increased acute and chronic gastritis (P<0.001) and a marginal increase in GA (P = 0.052). When histologic changes were compared between the 2 groups, decrease in acute and chronic gastritis was more frequent after H. pylori eradication (P<0.001) but changes in IM were similar. In the H. pylori-infected group, increase in GA was seen in the corpus (P = 0.01).

CONCLUSIONS

At 1 year, H. pylori eradication is beneficial in preventing progression of pathologic changes of the gastric mucosa.