Combined serum IgG response to Helicobacter pylori VacA and CagA predicts gastric cancer

Simultaneous and alternative IgG seroreactivity against Helicobacter pylori antigens VacA ,30 kDa and 50 kDa is a better biomarker approach for the outcome of infection than VacA and 50 kDa alone

Background/Aim. In our previous study, IgG seropositivities against Helicobacter (H) pylori antigens VacA, 50 kDa, 30 kDa, and 26 kDa were highlighted as biomarkers for the specific outcome of infection. We designed and conducted this study in order to investigate whether synchronous and/or alternative seroreactivity against H. pylori antigens VacA, 50 kDa, 30 kDa and 26 kDa in patients with gastric cancer and peptic ulcers exhibit stronger association than with dyspepsia and vice versa. Methods. In order to determine IgG antibodies to H. pylori antigens, a Western blot test was performed in 123 patients: 31 with gastric cancer, 31 with duodenal ulcer, 31 with gastric ulcer and 30 with functional dyspepsia. We analyzed IgG sero-reactivity against four H. pylori antigens (VacA, 50 kDa, 30 kDa, 26 kDa) in their synchronous/alternative combination as well as seroreactivity to synchronous and alternative combinations of H. pylori antigens between a group with functional dyspepsia and others. The analysis of diagnostic characteristics of the best synchronous and alternative seroreactivity combination was done, and tested versus VacA a s biomarker for gastric cancer and peptic ulcer, and 50 kDa as a biomarker for dyspepsia. Results. VacA seropositivity or 50 kDa seronegativity (p = 0.015) and VacA seropositivity or 50 kDa and 30 kDa seronegativity (p =0.044) had the better diagnostic characteristics with statistically significantly better fraction correct than VacA seropositivity alone. VacA seronegativity along with50 kDa and 30 kDa seropositivity (p = 0.003), 50 kDa seropositivity (p = 0.01), 30 kDa seropositivity (p = 0.015) and 50 kDa or 30 kDa seropositivity (p = 0.02) had better diagnostic characteristics and significantly better fraction correct than 50 kDa seropositivity alone. Conclusion. Simultaneous and alternative IgG seroreactivity/unreactivity against H. pylori antigens VacA, 50 kDa and 30 kDa have stronger association with the specific infection outcome, considering gastric cancer and peptic ulcer, or dyspepsia, than VacA and 50 kDa IgG seropositivity alone.

Seroreactivity against Helicobacter pylori VacA,50kDa and 30kDa along with alarm features may improve the diagnostic approach to uninvestigated dyspepsia: A pilot study

Background/Aim. Alarm features (AF) are of limited utility in predicting endoscopic findings, and the majority of patients with uninvestigated dyspepsia will have no organic pathology identified at upper gastrointestinal endoscopy. In our previous study, we highlighted seroreactivity against Helicobacter pylori (HP) antigens VacA, 50 kDa, and 30 kDa as biomarkers for gastric cancer, peptic ulcers, and functional dyspepsia. We designed and conducted this pi-lot study in order to compare the diagnostic utility of seroreactivity against HP VacA, 50 kDa, and 30 kDa with AF and investigate the possibility and adequacy of its synchronous application. Method. A careful history and physical examination with special attention to AF, esophagogastroduodenoscopy with biopsy, abdominal ultra-sound or computer tomography, complete blood count (CBC) and blood biochemistry, a Western Blot IgG against HP antigens VacA, 50 kDa, and 30 kDa, were per-formed in 123 patients with dyspepsia: 31 with gastric cancer, 31 with duodenal ulcer, 31 with gastric ulcer, and 30 with gastritis and functional dyspepsia. AF vs various combinations of seroreactivity against HP VacA, 50 kDa, and 30 kDa in patients with functional dyspepsia and others were analyzed in this study. Synchronous and alternative seroreactivity against VacA, 50 kDa, and 30 kDa, along with/without AF in patients with functional dyspepsia and other groups of patients were also analyzed. Results. VacA and 50 kDa seropositivity or AF had excellent case-findings clinical utility index for investigating dyspepsia. The absence of AF and seroreactivity against VacA either with: 50 kDa or 30 kDa seropositivity or 50 kDa and 30 kDa seropositivity had an excellent screening clinical utility index for investigating dyspepsia. Conclusion. Se-roreactivity against HP antigens VacA, 50 kDa, and 30 kDa might improve our approach to patients in investigating dyspepsia if used along with AF.

Epitope peptides of Helicobacter pylori CagA antibodies from sera by whole-peptide mapping

BACKGROUND

Helicobacter pylori CagA has been found to be immuno-dominant protein and utilized for the diagnosis of the infection with cagA-positive strains. It is important to characterize the peptide epitopes capable of detecting serum anti-CagA antibodies to understand CagA immunogenicity.

METHODS

Sera from 171 Japanese patients were subjected for the epitope mapping study. Eighty seven peptides were designed from the CagA consensus sequence and were used for ELISA protocol to test the serum samples. The reacting anti-CagA IgG amounts to specific peptides were measured and compared.

RESULTS

The study revealed a strong reactivity of two peptides (c7-NNTEPIYAQVNKKKAGQAT and c8-AGQATSPEEPIYAQVAKKV) in H. pylori-infected group. Interestingly, these two peptides contained the well-known EPIYA-A and EPIYA-B region, respectively, which are two out of three CagA phosphorylation domains. Tyrosine-phosphorylation of these peptides reduced their reactivity in most sera. Moreover, additional peptides' mapping and chimeric-peptides' experiments indicated that the amino acids (QV and KK) accommodated in right-side flanking regions of both EPIYA-motifs were essential for their strong reactivity, whereas the third EPIYA-motif containing peptide (c12-GRSASPEPIYATIDFDEA) with differing flanking amino acids was not reactive in most cases.

CONCLUSIONS

Our results suggest that the amino acid sequences constituted in the two reactive peptides are the important immunogenic regions of CagA which would be useful to develop next-generation peptide-based diagnostic assays.

Diagnosis of Helicobacter pylori: Changes towards the Future

Since the first evidence demonstrating the dramatically high incidence of H. pylori infection and the subsequent medical challenges it incurs, health management of H. pylori infection has been a high priority for health authorities worldwide. Despite a decreasing rate of infection in western countries, prevalence of H. pylori infection in developing and in some industrial countries is still very high. Whereas treatment and vaccination against H. pylori is a contemporary issue in medical communities, selective treatment and prior high-throughput screening of the subject population is a major concern of health organizations. So far, diagnostic tests are either elaborative and require relatively advanced medical care infrastructure or they do not fulfill the criteria recommended by the Maastricht IV/Florence consensus report. In this review, in light of recent scientific studies, we highlight current and possible future approaches for the diagnosis of H. pylori. We point out that novel non-invasive tests may not only cover the requirements of gold standard methods in H. pylori detection but also offer the potential for risk stratification of infection in a high throughput manner.

A review of Helicobacter pylori diagnosis, treatment, and methods to detect eradication

Helicobacter pylori (H. pylori) affects nearly half of the world’s population and, thus, is one of the most frequent and persistent bacterial infections worldwide. H. pylori is associated with peptic ulcer disease, gastric ulcers, mucosa-associated lymphoid tissue lymphoma, and gastric cancer. Various diagnostic methods exist to detect infection, and the choice of one method or another depends on several factors, such as accessibility, advantages and disadvantages of each method, cost, and the age of patients. Once H. pylori infection is diagnosed, the clinician decides whether treatment is necessity, according to the patient’s clinical condition. Typically, eradication of H. pylori is recommended for treatment and prevention of the infection. Cure rates with the standard triple therapy are acceptable, and effective quadruple therapies, sequential therapies, and concomitant therapies have been introduced as key alternatives to treat H. pylori infection. In this work, we review the main diagnostic methods used to identify H. pylori infection and to confirm eradication of infection. In addition, key factors related to treatment are reviewed.

Seroreactivity to Helicobacter pylori antigens as a risk indicator of gastric cancer

BACKGROUND

Multiple etiologic factors are suspected to cause gastric cancer, the most important of which is infection with virulent types of Helicobacter pylori.

MATERIALS AND METHODS

We have compared 102 gastric cancer patients with 122 non-ulcer, non-cancer dyspeptic patients. Gastric specimens were evaluated for H. pylori infection by tissue-based detection methods. Patient sera underwent antigen-specific ELISA and western blotting using a Helicoblot 2.1 kit and antibody responses to various H. pylori antigens were assessed.

RESULTS

The absolute majority (97-100%) of both groups were H. pylori seropositive. Multivariate regression analysis demonstrated serum antibodies to the low molecular weight 35kDa protein to be protective and reduce the risk of gastric cancer by 60% (OR:0.4; 95%CI:0.1-0.9). Conversely, seroreactivity to the 89kDa (VacA) protein was significantly higher in gastric cancer patients (OR:2.7; 95%CI:1.0-7.1). There was a highly significant association (p<0.001) between seroreactivity to the 116kDa (CagA) and 89kDa (VacA) proteins, and double positive subjects were found at nearly five fold (OR:4.9; 95%CI:1.0-24.4) enhanced risk of gastric cancer as compared to double negative subjects.

CONCLUSIONS

Seroreactivity to H. pylori low (35kDa) and high (116kDa/89kDa) molecular weight antigens were respectively revealed as protective and risk indicators for gastric cancer.

Biomarkers of Helicobacter pylori-associated gastric cancer

Helicobacter pylori-associated gastric cancer is a major cause of morbidity and mortality worldwide, and is predicted to become even more common in developing countries as the population ages. Since gastric cancer develops slowly over years to decades, and typically progresses though a series of well-defined histologic stages, cancer biomarkers have potential to identify asymptomatic individuals in whom surgery might be curative, or even those for whom antibiotics to eradicate H. pylori could prevent neoplastic transformation. Here we describe some of the challenges of biomarker discovery, summarize current approaches to biomarkers of gastric cancer, and explore some recent novel strategies.

Helicobacter pylori protein-specific antibodies and risk of colorectal cancer

BACKGROUND

There is biologic plausibility as to why infection with Helicobacter pylori, the leading cause of gastric cancer, may also increase the risk of colorectal cancer, but the epidemiologic findings have been inconsistent. We assessed the association of H. pylori protein-specific infection and colorectal cancer risk in the prospective cohort, the Southern Community Cohort Study.

METHODS

Multiplex serology was used to measure antibodies to 15 H. pylori proteins in prediagnostic blood among 188 incident colorectal cancer cases and 370 controls matched by age, race, sex, and blood collection timing. Conditional logistic regression was used to calculate ORs and 95% confidence intervals (CI).

RESULTS

Overall H. pylori prevalence was not associated with colorectal cancer risk (OR, 1.03; 95% CI, 0.59-1.77). However, seropositivity to any of five specific H. pylori proteins (VacA, HP231, HP305, NapA, and HcpC) was associated with a significant 60% to 80% increase in odds of risk. These associations became even stronger when limited to colon cancer risk, particularly for the known H. pylori toxin VacA (OR, 2.24; 95% CI, 1.22-4.11), including a significant, positive dose-response association by VacA antibody levels in quartiles (P < 0.05). Associations with VacA seropositivity were especially strong for early-onset and late-stage cancers.

CONCLUSIONS

The findings raise the hypothesis that individuals with high levels of antibodies to specific H. pylori proteins may be at higher risk of colon cancer.

IMPACT

Further investigation of the H. pylori-colorectal cancer association is warranted to determine the possibility of protein-specific antibody levels as a risk biomarker.

Diagnosis of Helicobacter pylori

The different invasive and noninvasive diagnostic tests for Helicobacter pylori have been applied mainly in emerging countries. Molecular methods have been developed, especially a test for detection of H. pylori and its clarithromycin resistance directly from stools. The long-term effects of eradication on histologic lesions have been studied in a meta-analysis and the prognostic value of post-treatment in gastric mucosa-associated lymphoid tissue lymphoma has been assessed. An operating link for gastritis assessment (the OLGA staging) has also been published. Attempts to simplify the urea breath test protocol have been made, and new stool antigen tests have been proposed and compared to those previously available.