Effect of Helicobacter pylori infection on gastric cell proliferation and genomic instability in a paediatric population of southern Italy

Antibiotic Resistance and Therapeutic Efficacy of Helicobacter pylori Infection in Pediatric Patients-A Tertiary Center Experience

One of the most widespread bacterial infections worldwide, Helicobacter pylori is thought to affect almost half of the world's population. Due to rising antibiotic resistance, treatment should be tailored according to antibiotic susceptibility testing (AST). This study aims to evaluate Helicobacter pylori antibiotic resistance and its therapeutic efficacy in children. We conducted a prospective, single-center study, that evaluated 68 children referred for upper gastrointestinal endoscopy (UGE) following chronic dyspeptic syndrome. Each patient underwent multiple biopsies to perform bacterial cultures with AST and histopathological examinations for the diagnosis. Patients without antibiotic resistance or negative cultures received a 10-day sequential therapy, while the others had the antibiotic regimen tailored based on AST. Fifty-nine patients with a positive biopsy-based diagnosis (24 males) were finally included. Bacterial cultures with AST were positive for 13 patients (22.03%) and the antibiotic resistance for clarithromycin was 15.38%. Fifty-seven patients were administered sequential therapy with an eradication rate of 94.73%. Clarithromycin-resistant patients were successfully treated with 10-day triple therapy of esomeprazole, amoxicillin, and metronidazole. Although bacterial cultures had a low positivity rate, sequential therapy had a successful eradication rate. Further studies are necessary to better assess Helicobacter pylori antibiotic resistance to provide tailored treatment and identify children that need closer monitoring.

Gastric Damage and Cancer-Associated Biomarkers in Helicobacter pylori-Infected Children

Helicobacter pylori (H. pylori) is well-known to be involved in gastric carcinogenesis, associated with deregulation of cell proliferation and epigenetic changes in cancer-related genes. H. pylori infection is largely acquired during childhood, persisting long-term in about half of infected individuals, a subset of whom will go on to develop peptic ulcer disease and eventually gastric cancer, however, the sequence of events leading to disease is not completely understood. Knowledge on carcinogenesis and gastric damage-related biomarkers is abundant in adult populations, but scarce in children. We performed an extensive literature review focusing on gastric cancer related biomarkers identified in adult populations, which have been detected in children infected with H. pylori. Biomarkers were related to expression levels (RNA or protein) and/or methylation levels (DNA) in gastric tissue or blood of infected children as compared to non-infected controls. In this review, we identified 37 biomarkers of which 24 are over expressed, three are under expressed, and ten genes are significantly hypermethylated in H. pylori-infected children compared to healthy controls in at least 1 study. Only four of these biomarkers (pepsinogen I, pepsinogen II, gastrin, and SLC5A8) have been studied in asymptomatically infected children. Importantly, 13 of these biomarkers (β-catenin, C-MYC, GATA-4, DAPK1, CXCL13, DC-SIGN, TIMP3, EGFR, GRIN2B, PIM2, SLC5A8, CDH1, and VCAM-1.) are consistently deregulated in infected children and in adults with gastric cancer. Future studies should be designed to determine the clinical significance of these changes in infection-associated biomarkers in children and their persistence over time. The effect of eradication therapy over these biomarkers in children if proven significant, could lead to modifications in treatment guidelines for younger populations, and eventually promote the development of preventive strategies, such as vaccination, in the near future.

Alpha-defensin expression in the gastric tissue of children with Helicobacter pylori-associated chronic gastritis: an immunohistochemical study

In this study, we evaluated the expression of alpha-defensin and its correlation with histological criteria in children with and without Helicobacter pylori-associated gastritis. Forty-five children were included. Immunohistochemical staining was performed and the relationship between alpha-defensin immunoscoring and H. pylori status and histological criteria was evaluated. Expression of alpha-defensin was significantly higher in the H. pylori-positive group (P < 0.001) and it was significantly associated with higher grades of chronic inflammation and neutrophil density (P < 0.001 for both). Our data show that alpha-defensin expression is increased in H. pylori infection in childhood and is associated with inflammatory tissue damage.

H pylori (CagA) and Epstein-Barr virus infection in gastric carcinomas: Correlation with p53 mutation and c-Myc, Bcl-2 and Bax expression

AIM: To investigate the interrelationship between H pylori and Epstein-Barr virus (EBV) infection in the gastric carcinogenesis having in focus the p53 mutation and the c-Myc, Bcl-2 and Bax expression.

METHODS: seventy-one gastric carcinoma tissues were assessed by polymerase chain reaction (PCR) for H pylori and in situ hybridization for EBV. c-Myc, Bcl-2 and Bax expression were detected by immunohistochemistry and single-stranded conformational polymorphism (SSCP) for p53 mutation.

RESULTS: The positivity rates for H pylori and EBV were 94.4% and 8.45%, respectively. The majority of the cases displayed only the H pylori presence. All EBV positive cases were also H pylori positive. None infectious agent was observed in 5.55% of the cases. The intestinal type tumor was more frequent in the co-infected and non-infected groups. The female predominated in the non-infected group showing statistical significance (70.4% vs 29.6%, P = 0.039). The Bcl-2 was only detected in the group exclusively infected by H pylori. However, c-Myc and Bax were detected in the three groups but with a low frequency in the co-infected group. Mutation of p53 was present in all groups, with the highest frequencies in the H pylori positive groups.

CONCLUSION: The frequency of H pylori infection in gastric carcinomas was high. The presented data indicated that gastric carcinogenesis has different pathways depending of the presence of the two investigated infectious agents, suggesting a possible involvement of H pylori with apoptotic process. The low expression of c-Myc and Bax in the EBV-positive groups suggests that EBV may inhibit the expression of these proteins. Nevertheless, p53 mutation shows to be a relevant alteration, independent of both infectious agents.

Gastrokine 1 expression in patients with and without Helicobacter pylori infection

BACKGROUND

To understand the molecular changes underlying Helicobacter pylori-related gastric diseases is mandatory to prevent gastric cancer. Proteomic technology is providing a rapid expansion of the basic knowledge, particularly in the discovery of new biomarkers involved in the tumourigenesis.

AIM

To characterise changes in protein expression level of the gastric mucosa in H. pylori-infected patients.

METHODS

The population enrolled comprised 41 dyspeptic patients. Proteins extracted from gastric mucosal specimens were analysed by 2-dimensional electrophoresis, sequenced by MALDI-TOF and identified by Edman's degradation.

RESULTS

Twenty-one out of 41 patients had H. pylori infection of whom 17 had anti-CagA IgG antibodies. Several proteins were identified, of which Rho guanosine diphosphatase dissociation inhibitor alpha and heat shock protein 27 increased and glutathione transferase and antrum mucosa protein-18 decreased in H. pylori-positive in respect to H. pylori-negative patients. Interestingly, antrum mucosa protein-18, currently referred as gastrokine-1, showed two isoforms differing in the first N-terminal amino acid residue. Both gastrokine-1 isoforms were observed in the H. pylori-negative group whereas a lower expression or even absence of the gastrokine-1 basic isoform was found in a subgroup (7/21) of H. pylori-positive patients with moderate-severe gastritis.

CONCLUSION

Our study demonstrated the presence of gastrokine-1 isoforms of which the basic isoform was reduced in a subset of patients with H. pylori infection.

Altered expression of Skp2, c-Myc and p27 proteins but not mRNA after H. pylori eradication in chronic gastritis

Helicobacter pylori infection is associated with increased gastric epithelial cell turnover and non-cardia gastric cancer. Cell cycle progression is dependent on the proteasomal degradation of p27, a cyclin-dependent kinase inhibitor and gastric tumor suppressor, following ubiquitination mediated by Skp2. c-Myc is a transcriptional repressor of p27 and also a target of Skp2. In vitro, H. pylori decreases p27 protein post-translationally. We aimed to determine how p27 is regulated by H. pylori in vivo. The effect of eradicating H. pylori on gastric epithelial p27, Skp2, and c-Myc proteins and mRNA was investigated in 22 patients with chronic gastritis, by immunohistochemistry and laser capture microdissection. The percentage of gastric antral epithelial cells expressing p27 protein was significantly higher after eradication of H. pylori (mean+/-s.e.m. 37+/-2.4% pre-eradication vs 55+/-2.8% post-eradication; P<0.001), while Skp2 and c-Myc protein-expressing cells were lower (Skp2: 35+/-3.8 vs 23+/-2.6%, P=0.009; c-Myc: 47+/-3.6 vs 30+/-3.8%, P<0.001). mRNA expressions of p27, Skp2, and c-Myc (normalized for 18SrRNA) were not changed by H. pylori eradication. H. pylori increases c-Myc and decreases gastric epithelial p27 protein expression in association with increased expression of Skp2, the regulator of p27's ubiquitin ligase complex. H. pylori may influence cell cycle progression and carcinogenesis through post-translational effects on specific gene expression.

Helicobacter pylori status and symptom assessment two years after eradication in pediatric patients from a high prevalence area

OBJECTIVES

To establish the rate of Helicobacter pylori reinfection in children from an H. pylori high prevalence area, possible clinical features predictive of reinfection and the usefulness of re-treatment.

METHODS

65 consecutive children attending the authors' department between 1998 and 2000 who had proven successful H. pylori eradication were enrolled; 52 took part. Patients and family members were invited to undergo C-urea breath testing and to complete a simple questionnaire regarding symptoms and socioeconomic status. Patients with H. pylori reinfection were offered treatment; eradication was assessed by C-urea breath test 8 weeks after completion of treatment.

RESULTS

Of 52 children, 15 (28.8%) were H. pylori positive. Variables predictive of reinfection were age at primary infection and presence of an infected sibling. Although reinfected children were more frequently symptomatic than non-reinfected patients, no specific symptom was associated with reinfection. Of the nine re-treated patients who returned 8 weeks after completing therapy, the bacterium was eradicated in five (56%).

CONCLUSIONS

The 12.8% per year reinfection rate in childhood at 2 years that we observed should prompt a re-evaluation of H. pylori status even after a successful eradication. Living in an H. pylori high prevalence area increases the annual risk of reinfection by approximately fourfold over the annual risk in H. pylori low prevalence areas.