Influence of oral Helicobacter pylori on the success of eradication therapy against gastric Helicobacter pylori

Background. The goal of this study was to see whether Helicobacter pylori ( H. pylori ) in the oral cavity might adversely affect the outcome of eradication therapy for gastric H. pylori.
Materials and Methods. Forty-seven patients (36 males, 11 females) with gastric H. pylori infection were enrolled in this study. Gastric H. pylori infection was confirmed by both immunohistological staining with anti- H. pylori antibody and bacterial culture of biopsy specimens. The therapeutic regimen consisted of 30 mg/day lansoprazole, 750 mg/day metronidazole, and 400 mg/day clarithromycin administered for 2 weeks. A fragment of the H. pylori urease gene was amplified by nested PCR for DNA extracted from saliva and dental plaque from the same patients. We examined the correlation between the gastric eradication success rate and the prevalence of H. pylori in the oral cavity as determined by PCR before and after the eradication therapy.
Results. The eradication success rate was significantly lower in the oral H. pylori -positive cases (12/23, 52.1%) than in the negative cases (22/24, 91.6%) at 4 weeks after the therapy (p = .0028). Two years later, only 16 of the 23 (69.5%) oral H. pylori -positive cases were disease-free, as compared to 23 of the 24 (95.8%) oral H. pylori -negative cases (p = .018).
Conclusions. H. pylori in the oral cavity affected the outcome of eradication therapy and was associated with a recurrence of gastric infection. We recommend that oral H. pylori should be examined by nested PCR and, if positive, should be considered a causal factor in refractory or recurrent cases.     

Early detection of gastric cancer after Helicobacter pylori eradication due to endoscopic surveillance

Background

Helicobacter pylori eradication therapy is commonly performed to reduce the incidence of gastric cancer. However, gastric cancer is occasionally discovered even after successful eradication therapy. Therefore, we examined the prognosis of gastric cancer patients, diagnosed after successful H. pylori eradication therapy.

Materials and Methods

All‐cause death rates and gastric cancer‐specific death rates in gastric cancer patients who received successful H. pylori eradication treatment was tracked and compared to rates in patients who did not receive successful eradication therapy.

Results

In total, 160 gastric cancer patients were followed‐up for up to 11.7 years (mean 3.5 years). Among them, 53 gastric cancer patients received successful H. pylori eradication therapy prior to gastric cancer diagnosis. During the follow‐up period, 11 all‐cause deaths occurred. In the successful eradication group, the proportion of patients with cancer stage I was higher. The proportions of patients who received curative endoscopic therapy and endoscopic examination in the 2 years prior to gastric cancer diagnosis were also higher in the successful eradication group. Kaplan–Meier analysis of all‐cause death and gastric cancer‐specific death revealed a lower death rate in patients in the successful eradication group (P = .0139, and P = .0396, respectively, log‐rank test). The multivariate analysis showed that endoscopy within 2 years before cancer diagnosis is associated with stage I cancer.

Conclusions

Possible early discovery of gastric cancer after H. pylori eradication due to regular endoscopic surveillance may contribute to better prognosis of patients with gastric cancer.     

Epigenetic changes in gastric cancer induction by Helicobacter pylori

Epigenetic disorder mechanisms are one of the causes of cancer. The most important of these changes is the DNA methylation, which leads to the spread of Helicobacter pylori and inflammatory processes followed by induction of DNA methylation disorder. Mutations and epigenetic changes are the two main agents of neoplasia. Epithelial cells infection by H. pylori associated with activating several intracellular pathways including: MAPK, NF-κB, Wnt/β-catenin, and PI3K are affects a variety of cells and caused to an increase in the production of inflammatory cytokines, changes in apoptosis, proliferation, differentiation, and ultimately leads to the transformation of epithelial cells into oncogenic. The arose of free radicals impose the DNA cytosine methylation, and NO can increase the activity of DNA methyltransferase. H. pylori infection causes an environment that mediates inflammation and signaling pathways that probably caused to stomach tumorigenicity. The main processes that change by decreasing or increasing the expression of various microRNAs expressions include immune responses, apoptosis, cell cycle, and autophagy. In this review will be describe a probably H. pylori roles in infection and mechanisms that have contribution in epigenetic changes in the promoter of genes.     

Effect of Helicobacter pylori eradication on gastric precancerous lesions: A systematic review and meta-analysis

Background

The question of whether eradication of Helicobacter pylori (Hp) can reverse gastric precancerous lesions, including intestinal metaplasia, remains uncertain, leading to ongoing debate. Therefore, a meta-analysis was performed to evaluate the effect of Hp eradication on gastric precancerous lesions.

Materials and Methods

PubMed, Embase, Cochrane Library, Web of Science, Scopus database, and ClinicalTrials.gov were systematically searched from inception to April 2023 for studies that explored the impact of Hp eradication on gastric precancerous lesions. Risk ratios (RRs) and their 95% confidence intervals (95% CIs) were selected as the effect size. We used the random-effects model to assess pooled data. We also performed quality assessments, subgroup analyses, and sensitivity analyses.

Results

Fifteen studies were included. Compared with placebo, Hp eradication could significantly prevent the progression of gastric precancerous lesions (RR = 0.87, 95% CI: 0.81–0.94, p < 0.01) and reverse them (RR = 1.32, 95% CI: 1.17–1.50, p < 0.01). Then, specific precancerous lesions were further explored. The progression of intestinal metaplasia was significantly prevented by Hp eradication compared to placebo or no treatment (RR = 0.80, 95% CI: 0.69–0.94, p < 0.01). Moreover, compared with placebo or no treatment, Hp eradication also improved chronic atrophic gastritis (RR = 1.84, 95% CI: 1.30–2.61, p < 0.01) and intestinal metaplasia (RR = 1.41, 95% CI: 1.15–1.73, p < 0.01). However, in terms of preventing dysplasia progression (RR = 0.86, 95% CI: 0.37–2.00) and improving dysplasia (RR = 0.89, 95% CI: 0.47–1.70), Hp eradication had no advantage compared to placebo or no treatment.

Conclusions

Hp eradication therapy could prevent the progression of gastric precancerous lesions and reverse them. Notably, intestinal metaplasia can be reversed, but this may only be appropriate for patients with epigenetic alterations and milder lesions.     

Strategy for eliminating gastric cancer in Japan

A study conducted by the Japan Gast Study Group showed that eradication of Helicobacter pylori reduced the risk of gastric cancer by about one-third. However, it did not completely prevent the onset of latent gastric cancer among those at high risk (i.e., with atrophic gastritis). To prevent deaths from gastric cancer, it is necessary to eradicate H. pylori infection. We propose a program of risk stratification based on the presence of H. pylori infection with or without atrophic gastritis followed by targeted interventions. Those at no risk for gastric cancer (no H. pylori, no atrophic gastritis) need no therapy or follow-up. Those at low risk (H. pylori infected, nonatrophic gastritis) need only H. pylori eradication therapy. The smaller groups at high or very high risk need eradication and cancer surveillance. We estimated the costs and the benefits of this strategy. Gastric cancer screening by simultaneous measurement of serum pepsinogen and H. pylori antibody combined with eradication of H. pylori in all individuals at risk would initially increase national healthcare expenditure, but this would be offset by markedly reducing the cost of treating gastric cancer. The proposed strategy should prevent about 150,000 deaths from gastric cancer during the 5 years after its adoption. If the loss caused by these deaths is also taken into account, the economic effect of this strategy becomes enormous. It would probably reduce the incidence of gastric cancer by more than 80-90% within 10 years. The Japanese government should take the initiative to implement this strategy as soon as possible.     

Current information on the association of Helicobacter pylori with autophagy and gastric cancer

Helicobacter pylori (H. pylori) is a Gram-negative bacterium and causative agent of gastric cancer. H. pylori induce defective autophagy or inhibit it by means of CagA and vacuolating cytotoxin A (VacA) toxins leading to the gastric cancer induction. Impaired or defective autophagy leads to the accumulation of cytotoxic materials, such as ROS and P62 that lead to increased mutations in the DNA, genome instability, and risk of cancer formation. H. pylori CagA may inhibit autophagy through the c-Met-PI3k/Akt-mTOR signaling pathway. However, VacA induces autophagy by some signaling pathways. In the gastric epithelial cells, VacA is a necessary and sufficient factor for the creation of autophagy. While CagA is a negative regulator of this phenomenon, the elimination of this gene from H. pylori has increased autophagy and the production of inflammatory cytokines is reduced. In gastrointestinal cancers, some of the microRNAs (miRNAs) act as tumor suppressors and some other are oncogenes by regulating various genes expression. H. pylori can also modify autophagy through a mechanism that includes the function of miRNAs. In autophagy, oncogenic miRNAs inhibit activation of some tumor suppressor signaling pathways (e.g., ULK1 complex, Beclin-1 function, and Atg4 messaging), whereas tumor suppressor miRNAs can block the activation of oncogenic signaling pathways. For instance, Beclin-1 is negatively regulated by miRNA-376b (oncogenic miRNA) and miRNA-30a (tumor suppressor miRNA). Similarly, Atg4 by miRNA-376b (oncogenic miRNA) and miRNA-101 (tumor suppressor miRNA). So, this apparent paradox can be explained as that both Beclin-1 and Atg4 play different roles in a particular cell or tissue.     

Genome-wide DNA methylation profiles in noncancerous gastric mucosae with regard to Helicobacter pylori infection and the presence of gastric cancer

Background and Aims: To determine genome‐wide DNA methylation profiles induced by Helicobacter pylori (H. pylori) infection and to identify methylation markers in H. pylori‐induced gastric carcinogenesis. Methods: Gastric mucosae obtained from controls (n = 20) and patients with gastric cancer (n = 28) were included. A wide panel of CpG sites in cancer‐related genes (1505 CpG sites in 807 genes) was analyzed using Illumina bead array technology. Validation of the results of Illumina bead array technique was performed using methylation‐specific PCR method for four genes (MOS, DCC, CRK, and PTPN6). Results: The Illumina bead array showed that a total of 359 CpG sites (269 genes) were identified as differentially methylated by H. pylori infection (p < .0001). The correlation between methylation‐specific PCR and bead array analysis was significant (p < .0001, Spearman coefficient = 0.5054). Methylation profiles in noncancerous gastric mucosae of the patients with gastric cancer showed quite distinct patterns according to the presence or absence of the current H. pylori infection; however, 10 CpG sites were identified to be hypermethylated and three hypomethylated in association with the presence of gastric cancer regardless of H. pylori infection (p < .01). Conclusions: Genome‐wide methylation profiles showed a number of genes differentially methylated by H. pylori infection. Methylation profiles in noncancerous gastric mucosae from the patients with gastric cancer can be affected by H. pylori‐induced gastritis. Differentially methylated CpG sites in this study needs to be validated in a larger population using quantitative methylation‐specific PCR method.     

Progress in vaccine development against Helicobacter pylori

Based on the very high prevalence of diseases caused by Helicobacter pylori, particularly in the developing world, and the rapid emergence of antibiotic resistance among clinical isolates, there is a strong rationale for an effective vaccine against H. pylori. In this review we describe recent promising candidate vaccines and prophylactic or therapeutic immunization strategies for use against H. pylori, as well as studies to identify immune responses that are related to protection in experimental animals. We also describe identification of different types of immune responses that may be related to protection against symptoms based on comparisons of H. pylori-infected patients with duodenal ulcers or gastric cancer and asymptomatic carriers. We conclude that there is still a strong need to clarify the main protective immune mechanisms against H. pylori as well as to identify a cocktail of strong protective antigens, or recombinant bacterial strains that express such antigens, that could be administered by a regimen that gives rise to effective immune responses in humans.