Immunity and Vaccine Development Against Helicobacter pylori

Chitosan Nanoparticles for Enhanced Immune Response and Delivery of Multi-Epitope Helicobacter pylori Vaccines in a BALB/c Mouse Model

Background/Objectives: Helicobacter pylori is the leading cause of chronic gastritis, peptic ulcer, gastric adenocarcinoma, and mucosal-associated lymphoma. Due to the emerging problems with antibiotic treatment against H. pylori in clinical practice, H. pylori vaccination has gained more interest. Oral immunization is considered a promising approach for preventing initial colonization of this bacterium in the gastrointestinal tract, establishing a first line of defense at gastric mucosal surfaces. Chitosan nanoparticles can be exploited effectively for oral vaccine delivery due to their stability, simplicity of target accessibility, and beneficial mucoadhesive and immunogenic properties. Methods: In this study, new multi-epitope pDNA- and recombinant protein-based vaccines incorporating multiple H. pylori antigens were produced and encapsulated in chitosan nanoparticles for oral and intramuscular administration. The induced immune response was assessed through the levels of antigen-specific IgGs, secreted mucosal SIgA, and cytokines (IL-2, IL-10, and IFN-γ) in immunized BALB/C mice. Results: Intramuscular administration of both pDNA and recombinant protein-based vaccines efficiently stimulated the production of specific IgG2a and IgG1, which was supported by cytokines levels. Oral immunizations with either pDNA or recombinant protein vaccines revealed high SIgA levels, suggesting effective gastric mucosal immunization, contrasting with intramuscular immunizations, which did not induce SIgA. Conclusions: These findings indicate that both pDNA and recombinant protein vaccines encapsulated into chitosan nanoparticles are promising candidates for eradicating H. pylori and mitigating associated gastric diseases in humans.

Helicobacter pylori-targeted AI-driven vaccines: a paradigm shift in gastric cancer prevention

Helicobacter pylori (H. pylori), a globally prevalent pathogen Group I carcinogen, presents a formidable challenge in gastric cancer prevention due to its increasing antimicrobial resistance and strain diversity. This comprehensive review critically analyzes the limitations of conventional antibiotic-based therapies and explores cutting-edge approaches to combat H. pylori infections and associated gastric carcinogenesis. We emphasize the pressing need for innovative therapeutic strategies, with a particular focus on precision medicine and tailored vaccine development. Despite promising advancements in enhancing host immunity, current Helicobacter pylori vaccine clinical trials have yet to achieve long-term efficacy or gain approval regulatory approval. We propose a paradigm-shifting approach leveraging artificial intelligence (AI) to design precision-targeted, multiepitope vaccines tailored to multiple H. pylori subtypes. This AI-driven strategy has the potential to revolutionize antigen selection and optimize vaccine efficacy, addressing the critical need for personalized interventions in H. pylori eradication efforts. By leveraging AI in vaccine design, we propose a revolutionary approach to precision therapy that could significantly reduce H. pylori -associated gastric cancer burden.

Animal Models of Helicobacter pylori Infection and Vaccines: Current Status and Future Prospects

Helicobacter pylori infection causes chronic gastritis, ulcers, and gastric cancer, making it a threat to human health. Despite the use of antibiotic therapy, the global prevalence of H. pylori infection remains high, necessitating early eradication measures. Immunotherapy, especially vaccine development, is a promising solution in this direction, albeit the selection of an appropriate animal model is critical in efficient vaccine production. Accordingly, we conducted a literature, search and summarized the commonly used H. pylori strains, H. pylori infection-related animal models, and models for evaluating H. pylori vaccines. Based on factors such as the ability to replicate human diseases, strain compatibility, vaccine types, and eliciting of immune responses, we systematically compared the advantages and disadvantages of different animal models, to obtain the informed recommendations. In addition, we have proposed novel perspectives on H. pylori-related animal models to advance research and vaccine evaluation for the prevention and treatment of diseases such as gastric cancer.

Recombinant outer membrane vesicles delivering eukaryotic expression plasmid of cytokines act as enhanced adjuvants against Helicobacter pylori infection in mice

The widespread prevalence of Helicobacter pylori (H. pylori) infection remains a great challenge to human health. The existing vaccines are not ideal for preventing H. pylori infection; thus, exploring highly effective adjuvants may improve the immunoprotective efficacy of H. pylori vaccines. In a previous study, we found that the outer membrane vesicles (OMVs), a type of nanoscale particle spontaneously produced by Gram-negative bacteria, could act as adjuvants to boost the immune responses to vaccine antigens. In this study, we explored the potential application of OMVs as delivery vectors for adjuvant development. We constructed recombinant OMVs containing eukaryotic expression plasmid of cytokines, including interleukin 17A or interferon-γ, and evaluated their function as adjuvants in combination with inactivated whole-cell vaccine (WCV) or UreB as vaccine antigens. Our results showed that recombinant OMVs as adjuvants could induce stronger humoral and mucosal immune responses in mice than wild-type H. pylori OMVs and the cholera toxin (CT) adjuvant. Additionally, the recombinant OMVs significantly promoted Th1/Th2/Th17-type immune responses. Furthermore, the recombinant OMV adjuvant induced more potent clearance of H. pylori than CT and wild-type OMVs. Our findings suggest that the recombinant OMVs coupled with cytokines may become potent adjuvants for the development of novel and effective vaccines against H. pylori infection.

High incidence of antibiotic resistance amongst isolates of Helicobacter pylori collected in Nottingham, UK, between 2001 and 2018

Introduction. Helicobacter pylori is the leading cause of peptic ulcers and gastric cancer. The most common treatment regimens use combinations of two or three antibiotics and a proton pump inhibitor (PPI) to suppress stomach acid. The World Health Organization designated clarithromycin-resistant H. pylori as a high priority pathogen for drug development, due to increasing antibiotic resistance globally.Hypothesis/Gap Statement. There is no routine surveillance of H. pylori primary antimicrobial sensitivities in the UK, and published data are lacking.Aim. This study aimed to characterize antimicrobial sensitivities of isolates collected in Nottingham, UK, between 2001 and 2018.Methodology. Gastric biopsy samples were collected, with informed written consent and ethics approval, from 162 patients attending the Queen's Medical Centre in Nottingham for an upper GI tract endoscopy. Antibiotic sensitivity was assessed using E-Tests and a more cost-effective disc diffusion test.Results. The clarithromycin, amoxicillin and levofloxacin disc diffusion tests provided identical results to E-Tests on a subset of 30 isolates. Disparities were observed in the metronidazole test results, however. In total, 241 isolates from 162 patients were tested using at least one method. Of all isolates, 28 % were resistant to clarithromycin, 62 % to metronidazole and 3 % to amoxicillin, which are used in first-line therapies. For those antibiotics used in second- and third-line therapies, 4 % were resistant to levofloxacin and none of the isolates were resistant to tetracycline. Resistance to more than one antibiotic was found in 27 % of isolates. The frequency of patients with a clarithromycin-resistant strain increased dramatically over time: from 16 % between 2001 and 2005 to 40 % between 2011 and 2018 (P=0.011). For the same time periods, there was also an increase in those with a metronidazole-resistant strain (from 58 to 78 %; P=0.05). The frequencies of clarithromycin and metronidazole resistance were higher in isolates from patients who had previously received eradication therapy, compared to those who had not (40 % versus 77 %, and 80 % versus 92 %, respectively). Of 79 pairs of isolates from the antrum and corpus regions of the same patient's stomach, only six had differences in their antimicrobial susceptibility profiles.Conclusion. Although there was high and increasing resistance to clarithromycin and metronidazole, there was no resistance to tetracycline and the frequencies of amoxicillin and levofloxacin resistance were very low.

Vitamin D3 eradicates Helicobacter pylori by inducing VDR-CAMP signaling

Background

Vitamin D₃ [VitD₃, 1,25 (OH)₂D₃] is known to have immunomodulatory and anti-microbial properties; however, its activity against Helicobacter pylori is unclear. In this study, we established H. pylori infection models in wild-type and VitD₃ receptor (VDR) knockdown mice and analyzed the effects of VitD₃ and their underlying mechanisms.

Methods

VDR^+/+ and VDR^+/- mice were intragastrically infected with the H. pylori SS1 strain. After confirmation of H. pylori infection, mice were treated with different doses of VitD₃. The infection levels in stomach tissues were quantified using the colony-forming assay, and the expression levels of the VDR and cathelicidin antimicrobial peptide (CAMP) in the gastric mucosa were analyzed by immunohistochemistry and western blotting.

Results

The gastric mucosa of VDR^+/- mice was more susceptible to H. pylori colonization and had lower levels of VDR and CAMP expression than that of VDR^+/+ mice. H. pylori infection upregulated VDR and CAMP expression in the stomach of both wild-type and mutant mice, and VitD₃ treatment resulted in further increase of VDR and CAMP levels, while significantly and dose-dependently decreasing the H. pylori colonization rate in both mouse groups, without affecting blood calcium or phosphorus levels.

Conclusion

Our data indicate that oral administration of VitD₃ reduces the H. pylori colonization rate and upregulates VDR and CAMP expression in the gastric mucosa, suggesting a role for VitD₃/VDR/CAMP signaling in the eradication of H. pylori in the stomach. These findings provide important insights into the mechanism underlying the anti-H. pylori activity of VitD₃ and should be useful in the development of measures to eradicate H. pylori.

Gastric organoids: Advancing the study of H. pylori pathogenesis and inflammation

For decades, traditional in vitro and in vivo models used for the study of Helicobacter pylori infection have relied heavily on the use of gastric cancer cell lines and rodents. Major challenges faced by these methods have been the inability to study cancer initiation in already cancerous cell lines, and the difficulty in translating results obtained in animal models due to genetic differences. These challenges have prevented a thorough understanding of the pathogenesis of disease and slowed the development of cancer therapies and a suitable vaccine against the pathogen. In recent years, the development of gastric organoids has provided great advantages over the traditional in vivo and in vitro models due to their similarities to the human stomach in vivo, their ease of use, and the capacity for long-term culture. This review discusses the advantages and limitations of existing in vivo and in vitro models of H. pylori infection, and how gastric organoids have been applied to study H. pylori pathogenesis, with a focus on how the pathogen interacts with the gastric epithelium, inflammatory processes, epithelial repair, and cancer initiation. The potential applications of organoids to address more complex questions on the role of hormones, vaccine-induced immunity are also discussed.

Homeostasis and Cancer Initiation: Organoids as Models to Study the Initiation of Gastric Cancer

Gastric cancer represents a significant disease burden worldwide. The factors that initiate cancer are not well understood. Chronic inflammation such as that triggered by H. pylori infection is the most significant cause of gastric cancer. In recent years, organoid cultures developed from human and animal adult stem cells have facilitated great advances in our understanding of gastric homeostasis. Organoid models are now being exploited to investigate the role of host genetics and bacterial factors on proliferation and DNA damage in gastric stem cells. The impact of a chronic inflammatory state on gastric stem cells and the stroma has been less well addressed. This review discusses what we have learned from the use of organoid models to investigate cancer initiation, and highlights questions on the contribution of the microbiota, chronic inflammatory milieu, and stromal cells that can now be addressed by more complex coculture models.

Vaccine development against Helicobacter pylori: from ideal antigens to the current landscape

Introduction: The interest of the world scientific community for an effective vaccine against Helicobacter pylori infection arises from its high prevalence and association with many diseases. Moreover, with an immunological response that is not always effective for the eradication of the bacteria and an increasing antibiotic resistance in the treatment of this infection, the search for a vaccine and new therapeutic modalities to control this infection is urgent.Areas covered: We bring an overview of the infection worldwide, discussing its prevalence, increasing resistance to antibiotics used in its therapy, in addition to the response of the immune system to the infection registered so far. Moreover, we address the most used antigens and their respective immunological responses expected or registered up to now. Finally, we address the trials and their partial results in development for such vaccines.Expert opinion: Although several studies for the development of an effective vaccine against this pathogen are taking place, many are still in the preclinical phase or even without updated information. In this sense, taking into account the high prevalence and association with important comorbidities, the interest of the pharmaceutical industry in developing an effective vaccine against this pathogen is questioned.

THE H. PYLORI-RELATED VIRULENCE FACTOR CAGA INFLUENCES THE EXPRESSION OF CHEMOKINES CXCL10, CCL17, CCL20, CCL22, AND THEIR RECEPTORS BY PERIPHERAL BLOOD MONONUCLEAR CELLS FROM PEPTIC ULCER PATIENTS

BACKGROUND

During the Helicobacter pylori (HP) infection, the infiltration of the leukocytes into stomach mucosa is directed by locally produced chemokines that play a decisive role in infection outcome. The CagA is the most potent virulence factor of HP, so that the infection with CagA + strains is associated with more severe complications than infection with CagA - HP.

OBJECTIVE

The aim was to determine the expression of chemokines CXCL10, CCL17, CCL20 and CCL22, and their receptors by CagA + HP- and CagA - HP-derived crude extract (HP-CE)-stimulated peripheral blood mononuclear cells (PBMCs) from peptic ulcer (PU) patients.

METHODS

The serum and the PBMCs were collected from 20 HP-infected PU patients, 20 HP-infected asymptomatic subjects (HIA) and 20 non-infected healthy subjects (NHS). The PBMCs were cultured in absence of stimulator or with 10 µg CagA + HP crude extract (CagA + CE), 10 µg CagA - HP crude extract (CagA - CE). Chemokines and receptors were measured by ELISA and real time-PCR respectively.

RESULTS

In PU patients, the production of chemokines CXCL10, CCL17, CCL20 and CCL22, and the expression of chemokine receptors CXCR3, CCR4 and CCR6 by CagA + CE-induced PBMCs were significantly higher than non-stimulated and CagA - CE stimulated cultures. The CXCL10 production by CagA + CE stimulated PBMCs from HIA subjects was significantly higher than the equal cultures from PU and NHS groups. The CCL17 and the CCL20 production by non-stimulated, CagA + CE stimulated, and CagA - CE stimulated PBMCs from PU subjects were significantly higher than the equal cultures from NHS and HIA groups. The CCL22 production by non-stimulated, CagA + CE stimulated and CagA - CE stimulated PBMCs from NHS group were significantly higher than the equal cultures from HIA and PU groups. The CagA + CE stimulated PBMCs from HIA subjects expressed lower amounts of CCR6 in comparison with CagA + CE stimulated PBMCs from NHS and PU groups. The serum levels CXCL10 and CCL20 in PU and HIA groups were significantly higher than NHS subjects. NHS and HIA groups displayed higher serum levels of CCL22 in comparison with PU patients.

CONCLUSION

Results indicated that the CagA status of bacterium influence the expression of chemokines and receptors by HP-CE stimulated PBMCs from PU patients.

Immune evaluation of a Saccharomyces cerevisiae-based oral vaccine against Helicobacter pylori in mice

BACKGROUND

Helicobacter pylori (H. pylori) is a common human pathogenic bacterium that is associated with gastric diseases. The current leading clinical therapy is combination antibiotics, but this treatment has safety issues, especially the induction of drug resistance. Therefore, developing a safe and effective vaccine against H. pylori is one of the best alternatives.

OBJECTIVE

To develop Saccharomyces cerevisiae (S. cerevisiae)-based oral vaccines and then demonstrate the feasibility of this platform for preventing H. pylori infection in the absence of a mucosal adjuvant.

MATERIALS AND METHODS

Saccharomyces cerevisiae (S. cerevisiae)-based oral vaccines, including EBY100/pYD1-UreB and EBY100/pYD1-VacA, were generated and analyzed by Western blot, Immunofluorescence analysis, flow cytometric assay, and indirect enzyme-link immunosorbent assay (ELISA). Further, antibody responses induced by oral administration of EBY100/pYD1-UreB, EBY100/pYD1-VacA, or EBY100/pYD1-UreB + EBY100/pYD1-VacA were measured in a mouse model. Lastly, the vaccinated mice were infected with H. pylori SS1, and colonization in the stomach were evaluated.

RESULTS

Saccharomyces cerevisiae-based H. pylori oral vaccines were successfully constructed. Mice orally administered with EBY100/pYD1-UreB, EBY100/pYD1-VacA, or EBY100/pYD1-UreB + EBY100/pYD1-VacA exhibited a significant humoral immune response as well as a mucosal immune response. Importantly, S. cerevisiae-based oral vaccines could effectively reduce bacterial loads with statistical significance after H. pylori infection.

CONCLUSIONS

Our study shows that S. cerevisiae-based platforms can serve as an alternative approach for the future development of promising bacterial oral vaccine candidates.

The Mechanisms of Sijunzi Decoction in the Treatment of Chronic Gastritis Revealed by Network Pharmacology

Chronic gastritis is characterized by inflammation in the gastric mucosa with a vicious circle in inflammatory cells and inflammatory mediators. Stomach adenocarcinoma would occur in the metaplastic gastric mucosa of chronic gastritis. Sijunzi decoction is a famous classical formula for the treatment of chronic gastritis. Although previous studies revealed some functions of Sijunzi decoction in treating chronic gastritis, the underlying mechanisms have not been illustrated clearly. In this study, we used network pharmacology to investigate the mechanism of Sijunzi decoction in treating chronic gastritis. Firstly, online datasets TCMSP, SWISS, and DisGeNET were used to investigate the functional mechanism of Sijunzi decoction against chronic gastritis and 18 genes were identified as targets of Sijunzi decoction in chronic gastritis. These 18 genes can be categorized into immunologically related genes and cancer-related genes. GO analysis showed that the 18 target genes were mainly enriched in angiogenesis, nitric oxide biosynthetic process, ERK1 and ERK2 cascade, cellular response to drug, and MAPK cascade. So, Sijunzi decoction alleviated chronic gastritis by inhibiting the local inflammatory response. Furthermore, we also investigated the impact of Sijunzi decoction on the peripheral blood leukocytes with our own RNA sequencing (RNA-seq) data of 11 chronic superficial gastritis patients. 102 differentially expressed genes (DEGs) were identified by comparing RNA-seq data of chronic superficial gastritis patients with healthy control groups. After performing a functional analysis on 102 DEGs and Sijunzi decoction potential targets and taking the intersection of these pathways, we found that platelet activation, angiogenesis, and pathways in cancer were candidate target pathways regulated by Sijunzi decoction. Thus, Sijunzi decoction also alleviates chronic gastritis by suppressing inflammatory response of peripheral blood leukocytes. Our results showed that Sijunzi decoction can ameliorate the local gastric inflammation and inflammations in peripheral blood leukocytes and might also reduce the incidence of stomach cancer in chronic gastritis.