Inflammation, Immunity, and Vaccine Development for the Gastric Pathogen Helicobacter pylori

Efficacy and eradication effect of vonoprazan and high-dose amoxicillin dual therapy in CagA+VacA+ Helicobacter pylori infected patients

OBJECTIVE

Helicobacter pylori (HP) eradication rates are higher by treated with the potassium-competitive acid blocker vonorasan than with proton pump inhibitors (PPIs). Herein, this study analyzed the clinical efficacy of vonoprazan combined with high-dose amoxicillin for dual therapy in personalized eradication of HP.

METHODS

This retrospective analysis included 452 patients with type I HP who were assigned to the observation and control groups. Cytotoxin-associated gene A (CagA) and vacuolating cytotoxin A (VacA) antibodies were detected using the H. pylori antibody typing classification assay kit by Western blot. The control group underwent PPI quadruple therapy (oral administration of esomeprazole, amoxicillin, clarithromycin, and colloidal bismuth subcitrate). The observation group was treated with vonoprazan combined with high-dose amoxicillin orally. The clinical efficacy was evaluated after 14 days of treatment, and adverse reactions during treatment were compared. The eradication rates for different HP types in the two groups were detected using a 13C-urea breath test.

RESULTS

There was no significant difference between the control and observation groups in sex, age, BMI, disease duration, smoking history, or drinking history. The observation group exhibited higher total effective rates and better eradication effects than the control group. The CagA+, VacA+, or CagA+VacA+ type patients showed no statistical difference in the incidence of adverse reactions, but the observation group showed a lower total incidence of adverse reactions than the control group.

CONCLUSION

Vonoprazan combined with high-dose amoxicillin has better clinical efficacy and eradication effect for patients with CagA+VacA+ HP, along with reduced adverse reactions.

Helicobacter pylori: Routes of Infection, Antimicrobial Resistance, and Alternative Therapies as a Means to Develop Infection Control

Helicobacter pylori (H. pylori) is a Gram-negative, spiral-shaped bacterium that colonizes the gastric epithelium and is associated with a range of gastrointestinal disorders, exhibiting a global prevalence of approximately 50%. Despite the availability of treatment options, H. pylori frequently reemerges and demonstrates increasing antibiotic resistance, which diminishes the efficacy of conventional therapies. Consequently, it is imperative to explore non-antibiotic treatment alternatives to mitigate the inappropriate use of antibiotics. This review examines H. pylori infection, encompassing transmission pathways, treatment modalities, antibiotic resistance, and eradication strategies. Additionally, it discusses alternative therapeutic approaches such as probiotics, anti-biofilm agents, phytotherapy, phototherapy, phage therapy, lactoferrin therapy, and vaccine development. These strategies aim to reduce antimicrobial resistance and enhance treatment outcomes for H. pylori infections. While alternative therapies can maintain low bacterial levels, they do not achieve complete eradication of H. pylori. These therapies are designed to bolster the immune response, minimize side effects, and provide gastroprotective benefits, rendering them suitable for adjunctive use alongside conventional treatments. Probiotics may serve as adjunctive therapy for H. pylori; however, their effectiveness as a monotherapy is limited. Photodynamic and phage therapies exhibit potential in targeting H. pylori infections, including those caused by drug-resistant strains, without the use of antibiotics. The development of a reliable vaccine is also critical for the eradication of H. pylori. This review identifies candidate antigens such as VacA, CagA, and HspA, along with various vaccine formulations, including vector-based and subunit vaccines. Some vaccines have demonstrated efficacy in clinical trials, while others have shown robust immune protection in preclinical studies. Nevertheless, each of the aforementioned alternative therapies requires thorough preclinical and clinical evaluation to ascertain their efficacy, side effects, cost-effectiveness, and patient compliance.

Comparison of gastric inflammation and metaplasia induced by Helicobacter pylori or Helicobacter felis colonization in mice

Gastric cancer is the fifth most diagnosed cancer in the world. Infection by the bacteria Helicobacter pylori (HP) is associated with approximately 75% of gastric cancer cases. HP infection induces chronic gastric inflammation, damaging the stomach and fostering carcinogenesis. Most mechanistic studies on gastric cancer initiation are performed in mice and utilize either mouse-adapted strains of HP or the natural mouse pathogen Helicobacter felis (HF). Here, we identified the differences in gastric inflammation, atrophy, and metaplasia associated with HP and HF infection in mice. PMSS1 HP strain or the CS1 HF strain were co-cultured with mouse peritoneal macrophages to assess their immunostimulatory effects. HP and HF induced similar cytokine production from cultured mouse peritoneal macrophages revealing that both bacteria exhibit similar immunostimulatory effects in vitro. Next, C57BL/6J mice were infected with HP or HF and were assessed 2 months post-infection. HP-infected mice caused modest inflammation within both the gastric corpus and antrum, and did not induce significant atrophy within the gastric corpus. In contrast, HF induced significant inflammation throughout the gastric corpus and antrum. Moreover, HF infection was associated with significant atrophy of the chief and parietal cell compartments and induced the expression of pyloric metaplasia (PM) markers. HP is poorly immunogenic compared to HF. HF induces dramatic CD4+ T cell activation, which is associated with increased gastric cancer risk in humans. Thus, HP studies in mice are better suited for studies on colonization, while HF is more strongly suited for studies on the effects of gastric inflammation on tumorigenesis.  .

IMPORTANCE

Mouse infection models with Helicobacter species are widely used to study Helicobacter pathogenesis and gastric cancer initiation. However, Helicobacter pylori is not a natural mouse pathogen, and mouse-adapted H. pylori strains are poorly immunogenic. In contrast, Helicobacter felis is a natural mouse pathogen that induces robust gastric inflammation and is often used in mice to investigate gastric cancer initiation. Although both bacterial strains are widely used, their disease pathogenesis in mice differs dramatically. However, few studies have directly compared the pathogenesis of these bacterial species in mice, and the contrasting features of these two models are not clearly defined. This study directly compares the gastric inflammation, atrophy, and metaplasia development triggered by the widely used PMSS1 H. pylori and CS1 H. felis strains in mice. It serves as a useful resource for researchers to select the experimental model best suited for their studies.

Hotspots and trends of risk factors in gastric cancer: A visualization and bibliometric analysis

BACKGROUND

The lack of specific symptoms of gastric cancer (GC) causes great challenges in its early diagnosis. Thus it is essential to identify the risk factors for early diagnosis and treatment of GC and to improve the survival rates.

AIM

To assist physicians in identifying changes in the output of publications and research hotspots related to risk factors for GC, constructing a list of key risk factors, and providing a reference for early identification of patients at high risk for GC.

METHODS

Research articles on risk factors for GC were searched in the Web of Science core collection, and relevant information was extracted after screening. The literature was analyzed using Microsoft Excel 2019, CiteSpace V, and VOSviewer 1.6.18.

RESULTS

A total of 2514 papers from 72 countries and 2507 research institutions were retrieved. China (n = 1061), National Cancer Center (n = 138), and Shoichiro Tsugane (n = 36) were the most productive country, institution, or author, respectively. The research hotspots in the study of risk factors for GC are summarized in four areas, namely: Helicobacter pylori (H. pylori) infection, single nucleotide polymorphism, bio-diagnostic markers, and GC risk prediction models.

CONCLUSION

In this study, we found that H. pylori infection is the most significant risk factor for GC; single-nucleotide polymorphism (SNP) is the most dominant genetic factor for GC; bio-diagnostic markers are the most promising diagnostic modality for GC. GC risk prediction models are the latest current research hotspot. We conclude that the most important risk factors for the development of GC are H. pylori infection, SNP, smoking, diet, and alcohol.

Advances in Helicobacter pylori vaccine research: From candidate antigens to adjuvants-A review

BACKGROUND

Helicobacter pylori is a Gram-negative, spiral-shaped bacterium that infects approximately 50% of the world's population and has been strongly associated with chronic gastritis, peptic ulcers, gastric mucosa-associated lymphoma, and gastric cancer. The elimination of H. pylori is currently considered one of the most effective strategies for the treatment of gastric-related diseases, so antibiotic therapy is the most commonly used regimen for the treatment of H. pylori infection. Although this therapy has some positive effects, antibiotic resistance has become another clinically prominent problem. Therefore, the development of a safe and efficient vaccine has become an important measure to prevent H. pylori infection.

METHODS

PubMed and ClinicalTrials.gov were systematically searched from January 1980 to March 2023 with search terms-H. pylori vaccine, adjuvants, immunization, pathogenesis, and H. pylori eradication in the title and/or abstract of literature. A total of 5182 documents were obtained. Based on the principles of academic reliability, authority, nearly publicated, and excluded the similar documents, finally, 75 documents were selected, organized, and analyzed.

RESULTS

Most of the candidate antigens used as H. pylori vaccines in these literatures are whole-cell antigens and virulence antigens such as UreB, VacA, CagA, and HspA, and the main types of vaccines for H. pylori are whole bacteria vaccines, vector vaccines, subunit vaccines, nucleic acid vaccines, epitope vaccines, etc. Some vaccines have shown good immune protection in animal trials; however, few vaccines show good in clinical trials. The only H. pylori vaccine passed phase 3 clinical trial is a recombinant subunit vaccine using Urease subunit B (UreB) as the vaccine antigen, and it shows good prophylactic effects. Meanwhile, the adjuvant system for vaccines against this bacterium has been developed considerably. In addition to the traditional mucosal adjuvants such as cholera toxin (CT) and E. coli heat labile enterotoxin (LT), there are also promising safer and more effective mucosal adjuvants. All these advances made safe and effective H. pylori vaccines come into service as early as possible.

CONCLUSIONS

This review briefly summarized the advances of H. pylori vaccines from two aspects, candidates of antigens and adjuvants, to provide references for the development of vaccine against this bacterium. We also present our prospects of exosomal vaccines in H. pylori vaccine research, in the hope of inspiring future researchers.

Comparison of gastric inflammation and metaplasia induced by Helicobacter pylori or Helicobacter felis colonization in mice

Background

Gastric cancer is the fifth most diagnosed cancer in the world. Infection by the bacteria Helicobacter pylori (HP) is associated with approximately 75% of gastric cancer cases. HP infection induces chronic gastric inflammation, damaging the stomach and fostering carcinogenesis. Most mechanistic studies on Helicobacter- induced gastric cancer initiation are performed in mice and utilize either mouse-adapted strains of HP or the natural mouse pathogen Helicobacter felis (HF). Each of these infection models is associated with strengths and weaknesses. Here, we identified the differences in immunogenicity and gastric pathological changes associated with HP and HF infection in mice.

Material and Methods

PMSS1 HP strain or with the CS1 HF strain were co-cultured with mouse peritoneal macrophages to assess their immunostimulatory effects. C57BL/6J mice were infected with HP or HF, and gastric inflammation, atrophy, and metaplasia development were assessed 2 months post-infection.

Results

HP and HF induced similar cytokine production from cultured mouse peritoneal macrophages. HP-infected mice caused modest inflammation within both the gastric corpus and antrum and did not induce significant atrophy within the gastric corpus. In contrast, HF induced significant inflammation throughout the gastric corpus and antrum. Moreover, HF infection was associated with significant atrophy of the chief and parietal cell compartments and induced expression of pyloric metaplasia markers.

Conclusions

HP is poorly immunogenic compared to HF. HF induces dramatic CD4+ T cell activation, which is associated with increased gastric cancer risk in humans. Thus, HP studies in mice are better suited for studies on colonization, while HF is more strongly suited for pathogenesis and cancer initiation studies.

Targeting IL-1β in patients with advanced Helicobacter pylori infection: a potential therapy for gastric cancer

Helicobacter pylori (H. pylori) infection is a causal factor of gastric cancer. Among the cytokines secreted during this infection, IL-1β is highly associated with promotion and progression of gastric cancer. On the therapeutic front, eradication of H. pylori was thought to be efficient to restore gastric homeostasis. However, successful H. pylori eradication in patients with advanced stages (intestinal metaplasia) failed to diminish inflammation that is due to heightened Th17 response and elevated IL-1β levels. In fact, association between these two components was established, suggesting that IL-1β is a critical target in these cases. In this review, we will discuss the functional relevance of IL-1β in advanced H. pylori infection and how its targeting may bring clinical benefit.

Helicobacter pylori infection is correlated with the incidence of erosive oral lichen planus and the alteration of the oral microbiome composition

BACKGROUND

Oral lichen planus (OLP), a common clinical oral disease, is associated with an increased risk of malignant transformation. The mechanism underlying the pathogenesis of OLP is unknown. Oral dysbacteriosis is reported to be one of the aetiological factors of OLP. Although Helicobacter pylori infection is associated with various oral diseases, the correlation between H. pylori infection and OLP is unclear. This study aimed to investigate the effect of H. pylori infection on OLP pathogenesis and oral microbiome composition in the Chinese population, which has a high incidence of H. pylori infection.

RESULT

In this study, saliva samples of 30 patients with OLP (OLP group) and 21 negative controls (NC group) were collected. H. pylori infection was detected using the carbon-13-labeled urea breath test (UBT). The saliva samples were divided into the following four groups based on the H. pylori status: H. pylori-positive OLP (OLP+), H. pylori-positive NC (NC+), H. pylori-negative OLP (OLP-), and H. pylori-negative NC (NC-). Oral microbiome compositions were significantly different between the OLP and NC groups and between the OLP- and OLP+ groups. Compared with those in the OLP- group, those in the OLP+ group had a higher incidence of erosive OLP and higher levels of salivary cytokines. In contrast, the oral microbiome composition and cytokine levels were not significantly different between the NC- and NC+ groups.

CONCLUSIONS

This is the first report to demonstrate that H. pylori infection is significantly correlated with the pathogenesis of erosive OLP.

Helicobacter pylori outer membrane vesicles induce expression and secretion of oncostatin M in AGS gastric cancer cells

Helicobacter pylori, a human pathogen that colonizes the stomach of 50% of the world's population, is associated with gastritis, gastric adenocarcinoma, and mucosa-associated lymphoid tissue (MALT) lymphoma. Diseases are characterized by severe inflammatory responses in the stomach that are induced by various chemokines and cytokines. Recently, oncostatin M (OSM), an IL-6 family cytokine, was detected in early gastric cancer biopsies. In this study, we showed that Helicobacter pylori induced secretion of OSM and overexpression of its type II receptor OSMRβ (OSM/OSMRβ) in a human gastric adenocarcinoma cell line (AGS) over 24 h of infection. Furthermore, we showed that the induction of OSM and OSMRβ was carried out by heat-sensitive Helicobacter pylori outer membrane vesicle (OMV) protein. Collectively, our results established, for the first time, a direct relation between Helicobacter pylori OMVs and the OSM/OSMRβ signaling axis.

Innate Lymphoid Cells: Important Regulators of Host-Bacteria Interaction for Border Defense

Innate lymphoid cells (ILCs) are a recently discovered type of innate immune lymphocyte. They include three different groups classified by the nature of the transcription factors required for their development and by the cytokines they produce. ILCs mainly reside in tissues close to the mucosal barrier such as the respiratory and gastrointestinal tracts. Due to their close proximity to the mucosal surface, ILCs are exposed to a variety of both commensal and pathogenic bacteria. Under non-pathological conditions, ILCs have been shown to be important regulators for the maintenance of tissue homeostasis by mutual interactions with the microbiome. Besides these important functions at homeostasis, several studies have also provided emerging evidence that ILCs contribute to defense against pathogenic bacterial infection by responding rapidly to the pathogens as well as orchestrating other immune cells. In this review, we summarize recent advances in our understanding of the interactions of ILCs and bacteria, with special focus on the function of the different ILC subsets in bacterial infections.

Defining the Helicobacter pylori Disease-Specific Antigenic Repertoire

The analysis of the interaction between Helicobacter pylori (HP) and the host in vivo is an extremely informative way to enlighten the molecular mechanisms behind the persistency/latency of the bacterium as well as in the progression of the infection. An important source of information is represented by circulating antibodies targeting the bacteria that define a specific "disease signature" with prospective diagnostic implications. The diagnosis of some of the HP induced diseases such as gastric cancer (GC), MALT lymphoma (MALT), and autoimmune gastritis (AIG) is not easy because patients do not show symptoms of illness in early-onset stages, at the same time they progress rapidly. The possibility of identifying markers able to provide an early diagnosis would be extremely beneficial since a late diagnosis results in a delay in undergoing active therapy and reduces the survival rate of patients. With the aim to identify the HP antigens recognized during the host immune-response to the infection and possibly disease progression, we applied a discovery-driven approach, that combines "phage display" and deep sequencing. The procedure is based on the selection of ORF phage libraries, specifically generated from the pathogen's genome, with sera antibodies from patients with different HP-related diseases. To this end two phage display libraries have been constructed starting from genomic DNA from the reference HP 26695 and the pathogenic HP B128 strains; libraries were filtered for ORFs by using an ORF selection vector developed by our group (Di Niro et al., 2005; Soluri et al., 2018), selected with antibodies from patients affected by GC, MALT, and AIG and putative HP antigens/epitopes were identified after Sequencing and ranking. The results show that individual selection significantly reduced the library diversity and comparison of individual ranks for each condition allowed us to highlight a pattern of putative antigens specific for the different pathological outcomes or common for all of them. Within the putative antigens enriched after selection, we have validated protein CagY/Cag7 by ELISA assay as a marker of HP infection and progression. Overall, we have defined HP antigenic repertoire and identified a panel of putative specific antigens/epitopes for three different HP infection pathological outcomes that could be validated in the next future.