Vaccinating against Helicobacter pylori infection

Novel therapeutic regimens against Helicobacter pylori: an updated systematic review

Helicobacter pylori (H. pylori) is a strict microaerophilic bacterial species that exists in the stomach, and H. pylori infection is one of the most common chronic bacterial infections affecting humans. Eradicating H. pylori is the preferred method for the long-term prevention of complications such as chronic gastritis, peptic ulcers, gastric mucosa-associated lymphoid tissue lymphoma, and gastric cancer. However, first-line treatment with triple therapy and quadruple therapy has been unable to cope with increasing antibacterial resistance. To provide an updated review of H. pylori infections and antibacterial resistance, as well as related treatment options, we searched PubMed for articles published until March 2024. The key search terms were "H. pylori", "H. pylori infection", "H. pylori diseases", "H. pylori eradication", and "H. pylori antibacterial resistance." Despite the use of antimicrobial agents, the annual decline in the eradication rate of H. pylori continues. Emerging eradication therapies, such as the development of the new strong acid blocker vonoprazan, probiotic adjuvant therapy, and H. pylori vaccine therapy, are exciting. However, the effectiveness of these treatments needs to be further evaluated. It is worth mentioning that the idea of altering the oxygen environment in gastric juice for H. pylori to not be able to survive is a hot topic that should be considered in new eradication plans. Various strategies for eradicating H. pylori, including antibacterials, vaccines, probiotics, and biomaterials, are continuously evolving. A novel approach involving the alteration of the oxygen concentration within the growth environment of H. pylori has emerged as a promising eradication strategy.

Copper-Bearing Metal-Organic Framework with Mucus-Penetrating Function for the Multi-Effective Clearance of Mucosal Colonized Helicobacter pylori

Helicobacter pylori colonizes over 50% of people worldwide. Biofilm formation through penetrating gastric mucus and resistance acquired by H. pylori markedly reduces the efficacy of traditional antibiotics. The present triple therapy and bismuth-based quadruple therapy inevitably causes intestinal flora disturbance and fails to address the excessive H. pylori-triggered inflammatory response. Herein, a mucus-permeable therapeutic platform (Cu-MOF@NF) that consists of copper-bearing metal-organic framework (Cu-MOF) loaded with nitrogen-doped carbon dots and naturally active polysaccharide fucoidan is developed. The experimental results demonstrate that Cu-MOF@NF can penetrate the mucus layer and hinder H. pylori from adhering on gastric epithelial cells of the stomach. Notably, released Cu2+ can degrade the polysaccharides in the biofilm and interfere with the cyclic growing mode of "bacterioplankton ↔ biofilm", thereby preventing recurrent and persistent infection. Compared with traditional triple therapy, the Cu-MOF@NF not only possesses impressive antibacterial effect (even include multidrug-resistant strains), but also improves the inflammatory microenvironment without disrupting the balance of intestinal flora, providing a more efficient, safe, and antibiotic-free new approach to eradicating H. pylori.

An M cell-targeting recombinant L. lactis vaccine against four H. pylori adhesins

The acidic environment and enzyme degradation lead to oral vaccines often having little immune effect. Therefore, it is an attractive strategy to study an effective and safe oral vaccine delivery system that can promote gastrointestinal mucosal immune responses and inhibit antigen degradation. Moreover, the antigens uptake by microfold cells (M cells) is the determining step in initiating efficient immune responses. Therefore, M cell-targeting is one promising approach for enhancing oral vaccine potency. In the present study, an M cell-targeting L. lactis surface display system (plSAM) was built to favor the multivalent epitope vaccine antigen (FAdE) to achieve effective gastrointestinal mucosal immunity against Helicobacter pylori. Therefore, a recombinant Lactococcus lactic acid vaccine (LL-plSAM-FAdE) was successfully prepared, and its immunological properties and protective efficacy were analyzed. The results showed that LL-plSAM-FAdE can secretively express the recombinant proteins SAM-FAdE and display the SAM-FAdE on the bacterial cell surface. More importantly, LL-plSAM-FAdE effectively promoted the phagocytosis and transport of vaccine antigen by M cells in the gastrointestinal tract of mice, and simulated high levels of cellular and humoral immune responses against four key H. pylori adhesins (Urease, CagL, HpaA, and Lpp20) in the gastrointestinal tract, thus enabling effective prevention of H. pylori infection and to some extent eliminating H. pylori already present in the gastrointestinal tract. KEY POINTS: • M-cell-targeting L. lactis surface display system LL- plSAM was designed • This system displays H. pylori vaccine-promoted phagocytosis and transport of M cell • A promising vaccine candidate for controlling H. pylori infection was verified.

Prophylactic immunization to Helicobacter pylori infection using spore vectored vaccines

BACKGROUND

Helicobacter pylori infection remains a major public health threat leading to gastrointestinal illness and increased risk of gastric cancer. Mostly affecting populations in developing countries no vaccines are yet available and the disease is controlled by antimicrobials which, in turn, are driving the emergence of AMR.

MATERIALS AND METHODS

We have engineered spores of Bacillus subtilis to display putative H. pylori protective antigens, urease subunit A (UreA) and subunit B (UreB) on the spore surface. Following oral dosing of mice with these spores, we evaluated immunity and colonization in animals challenged with H. pylori.

RESULTS

Oral immunization with spores expressing either UreA or UreB showed antigen-specific mucosal responses (fecal sIgA) including seroconversion and hyperimmunity. Following challenge, colonization by H. pylori was significantly reduced by up to 1-log.

CONCLUSIONS

This study demonstrates the utility of bacterial spores for mucosal vaccination to H. pylori infection. The heat stability and robustness of Bacillus spores coupled with their existing use as probiotics make them an attractive solution for either protection against H. pylori infection or potentially for therapy and control of active infection.

Fructose potentiates the protective efficiency of live Edwardsiella tarda cell vaccine

Vaccination is an effective measure to prevent infection by pathogens. Live vaccines have higher protective efficacy than inactivated vaccines. However, how live vaccines interact with the host from a metabolic perspective is unknown. The present study aimed to explore whether a live Edwardsiella tarda vaccine regulates host metabolism and whether this regulation is related to the protective efficacy of the vaccine. Therefore, a gas chromatography mass spectrometry (GC-MS)-based metabolomics approach was used to investigate the metabolomic profile of mice serum after vaccination with live E. tarda vaccine. Fructose was identified as a key biomarker that contributes to the immune protection induced by the live vaccine. Moreover, co-administration of exogenous fructose and the live vaccine synergistically promoted survival of mice and fish after bacterial challenge. These results indicate that metabolites, especially fructose, can potentiate the live E. tarda vaccine to increase its protective efficiency.

Helicobacter pylori Infection: Current Status and Future Prospects on Diagnostic, Therapeutic and Control Challenges

Helicobacter pylori (H. pylori) infection, which affects approximately half of the world's population, remains a serious public health problem. As H. pylori infection leads to a number of gastric pathologies, including inflammation, gastroduodenal ulcers, and malignancies, early detection and treatment are crucial to preventing the spread of the infection. Multiple extragastric complications, such as iron deficiency anaemia, immune thrombocytopenic purpura, vitamin B12 deficiency, diabetes mellitus, cardiovascular diseases, and certain neurological disorders, have also been linked to H. pylori infection. An awareness of H. pylori and associated health hazards is necessary to minimize or even eradicate the infection. Therefore, there is an urgent need to raise the standards for the currently employed diagnostic, eradication, alternative treatment strategies. In addition, a brief overview of traditional and cutting-edge approaches that have proven effective in identifying and managing H. pylori is needed. Based on the test and laboratory equipment available and patient clinical characteristics, the optimal diagnostic approach requires weighing several factors. The pathophysiology and pathogenic mechanisms of H. pylori should also be studied, focusing more on the infection-causing virulence factors of this bacterium. Accordingly, this review aims to demonstrate the various diagnostic, pathophysiological, therapeutic, and eradication tactics available for H. pylori, emphasizing both their advantages and disadvantages. Invasive methods (such as quick urease testing, biopsy, or culture) or noninvasive methods (such as breath tests, stool investigations, or serological tests) can be used. We also present the most recent worldwide recommendations along with scientific evidence for treating H. pylori. In addition to the current antibiotic regimens, alternative therapies may also be considered. It is imperative to eradicate the infections caused by H. pylori as soon as possible to prevent problems and the development of stomach cancer. In conclusion, significant advances have been made in identifying and treating H. pylori. To improve eradication rates, peptide mass fingerprinting can be used as a diagnostic tool, and vaccines can also eliminate the infection.

Detection and Treatment of Helicobacter pylori: Problems and Advances

Helicobacter pylori (H. pylori) infection is chronic and etiologically linked to gastric cancer (GC) derived from gastric epithelium. The potential mechanism is complex, covering chronic inflammation, epithelial senescence, NF-κB activation, the cytotoxin-associated gene A protein translocation, and related abnormal signaling pathways. In clinical practice, the test-and-treat strategy, endoscopy-based strategy, and (family-based) screen-and-treat strategy are recommended to detect H. pylori and prevent GC. It has been demonstrated that the decreasing annual incidence of GC is largely attributable to the management of H. pylori. This study reviews the current clinical practice of H. pylori on the detection and eradication, alternative treatment strategies, and related problems and advances, and hopes to contribute to the better clinical management of H. pylori.

Evaluation of the diagnostic value of FliD, a Helicobacter pylori flagellar protein

Novel immunodominant antigens are urgently required for diagnosis and vaccine of Helicobacter pylori(HP). FliD, an important colonization factor was cloned and expressed(rFliD) to evaluate the levels of specific-IgG, IgM and IgA antibodies in the serum of patients by ELISA. Rabbit anti-rFliD polyclonal antibody (pAb) was obtained by subcutaneous injections of rFliD. The rFliD-specific IFN-γ and IL-4 of peripheral blood mononuclear cells and CD4⁺ T cells from human were analyzed by enzyme-linked immunospot and flow cytometry. We found that the levels of rFliD-specific IgG, IgM and IgA were significantly higher in HP-infected-patients compared with healthy controls. IgG, IgM and IgA had diagnostic sensitivities of 92.6, 89.8 and 83.2%; specificities of 91.1, 88.7 and 64.6%; and areas under the receiver operating curves of 0.97, 0.96 and 0.92, respectively. Furthermore, rFliD-pAb was used in the immunohistochemical analysis of gastritis and gastric cancer tissues from patients infected with HP. The levels of rFliD-specific IFN-γ and IL-4 were significantly elevated in HP-infected patients and exhibited a T helper type 1-dominant subtype. These findings indicate that rFliD exhibits high validity as a biomarker in HP diagnosis and may also be a potent antigen for vaccine design due to its high cellular and humoral immune response.

A new antibacterial 3,5-dimethylorsellinic acid-based meroterpene from the marine fungus Aspergillus sp. CSYZ-1

Chemical investigation of the extracts of Aspergillus sp. CSYZ-1 resulted in the identification of compound 1, aspergillactone, a new 3,5-dimethylorsellinic acid-based meroterpenoid, together with four known metabolites (2-5). The structure and relative configuration of 1 were unambiguously determined by nuclear magnetic resonance (NMR), mass spectrometry. The absolute configuration of 1 was defined by quantum chemical TDDFT calculated and the experimental ECD spectra. The possible biosynthetic pathway of compound 1 was also proposed. The new compound exhibited potent antimicrobial activity against Helicobacter pylori and Staphylococcus aureus with MIC values of around 1-4 and 2-16 μg/mL, respectively.

Helicobacter pylori adhesins: HpaA a potential antigen in experimental vaccines for H. pylori

BACKGROUND

Helicobacter pylori is a gram-negative bacterium involved in many gastric pathologies such as ulcers and cancers. Although the treatment for this infection has existed for several years, the development of a vaccine is nevertheless necessary to reduce the severe forms of the disease. For more than three decades, many advances have been made particularly in the understanding of virulence factors as well as the pathogenesis of gastric diseases caused by H. pylori. Among these key virulence factors, specific antigens have been identified: Urease, Vacuolating cytotoxin A (VacA), Cytotoxin-associated gene A (CagA), Blood group antigen-binding adhesin (BabA), H. pylori adhesin A (HpaA), and others.

OBJECTIVES

This review will focus on H. pylori adhesins, in particular, on HpaA and on the current knowledge of H. pylori vaccines.

METHODS

All of the information included in this review was retrieved from published studies on H. pylori adhesins in H. pylori infections.

RESULTS

These proteins, used in their native or recombinant forms, induce protection against H. pylori in experimental animal models.

CONCLUSION

H. pylori adhesins are known to be promising candidate vaccines against H. pylori. Future research should be carried out on adhesins, in particular, on HpaA.

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.

Vitamin D3 Inhibits Helicobacter pylori Infection by Activating the VitD3/VDR-CAMP Pathway in Mice

Helicobacter pylori (H. pylori) infection is closely associated with the occurrence and development of gastric diseases. Therefore, eliminating H. pylori infection should help to prevent gastric diseases. Vitamin D3 (VitD3, 1,25(OH)2D3) was previously observed to exhibit anti-H. pylori infection activity in clinic, but these results were reported in heterogeneous in vivo studies without elucidation of the underlying mechanisms. In the present study, we established H. pylori infection models in both wild-type and VDR knockdown (VDR-KD) mice, which were used to demonstrate that VitD3 inhibits H. pylori infection by enhancing the expression of VitD receptor (VDR) and cathelicidin antimicrobial peptide (CAMP). Furthermore, VDR-KD mice that exhibited lower VDR expression were more susceptible to H. pylori infection. In cultured mouse primary gastric epithelial cells, we further demonstrated that the VitD3/VDR complex binds to the CAMP promoter region to increase its expression. These data provide a mechanistic explanation of the anti-H. pylori infection activity of VitD3 at the molecular level in mice and suggest a new avenue for the clinical management of H. pylori eradication therapy.

Orally administrated chitosan microspheres bind Helicobacter pylori and decrease gastric infection in mice

Persistent Helicobacter pylori (H. pylori) infection is related to 90% of gastric cancers. With bacterial resistance rising and treatment inefficiency affecting 15% of the patients, alternative treatments urge. Chitosan microspheres (ChMics) have been proposed as an H. pylori-binding system. This work evaluates ChMics biocompatibility, mucopenetration and capacity to treat H. pylori infection in mice after oral administration. ChMics of different size (XL, ∼120 µm and XS, ∼40 µm) and degree of acetylation (6% and 16%) were developed and revealed to be able to adhere both human and mouse-adapted H. pylori strains without cytotoxicity towards human gastric cells. Ex vivo studies showed that smaller (XS) microspheres penetrate further within the gastric foveolae, suggesting their ability to reach deeply adherent bacteria. In vivo assays showed 88% reduction of infection when H. pylori-infected mice (C57BL/6) were treated with more mucoadhesive XL6 and XS6 ChMics. Overall, ChMics clearly demonstrate ability to reduce H. pylori gastric infection in mice, with chitosan degree of acetylation being a dominant factor over microspheres' size on H. pylori removal efficiency. These results evidence the strong potential of this strategy as an antibiotic-free approach to fight H. pylori infection, where microspheres are orally administered, bind H. pylori in the stomach, and remove them through the gastrointestinal tract. STATEMENT OF SIGNIFICANCE: Approximately 90% of gastric cancers are caused by the carcinogenic agent Helicobacter pylori, which infects >50% of the world population. Bacterial resistance, reduced antibiotic bioavailability, and the intricate distribution of bacteria in mucus and within gastric foveolae hamper the success of most strategies to fight H. pylori. We demonstrate that an antibiotic-free therapy based on bare chitosan microspheres that bind and remove H. pylori from stomach can achieve 88% reduction of infection from H. pylori-infected mice. Changing size and mucoadhesive properties, microspheres can reach different areas of gastric mucosa: smaller and less mucoadhesive can penetrate deeper into the foveolae. This promising, simple and inexpensive strategy paves the way for a faster bench-to-bedside transition, therefore holding great potential for clinical application.

Helicobacter pylori: Perturbation and restoration of gut microbiome

Alternate remedies with natural products provides unlimited opportunities for new drug development. These can be either as pure compounds or as standardized set of compounds. The phytochemicals and secondary metabolites are in great demand for screening bioactive compounds and plays an important role towards drug development. Natural products have many advantages over to synthetic chemical drugs. Helicobacter pylori (H. pylori) a Gram-negative bacteria has been classified as Class I carcinogen by World Health Organization in 1994. Current treatment regimens for H. pylori is ‘triple therapy’ administrated for two weeks which includes a combination of two antibiotics like Amoxicillin and Clarithromycin and a proton pump inhibitor (PPI) like Lansoprazole, and for ‘quadruple therapy’ in addition to antibiotics and a PPI, Bismuth is used. Antibiotic resistance can be named as the main factor for failure of treatment of H. pylori infection. The need of the hour is to develop a herbal remedy that could combat the growth of H. pylori. Probiotics can also be used as ‘feasible’ tool for H. pylori infection management. Present review is an attempt to briefly discuss about the pathogenicity, genetic predisposition, perturbation of gut microbiota due to antibiotic treatment and restoration of healthy gut microbiota with phytochemicals and probiotics.

Fullerenol Nanoparticles Eradicate Helicobacter pylori via pH-Responsive Peroxidase Activity

Helicobacter pylori (H. pylori) eradication by antibiotics and proton pump inhibitor treatment is limited by the low pH microenvironment in the stomach and can lead to antibiotic resistance. We fabricated fullerenol nanoparticles (FNPs) with varied chemical structures responding to a pinacol rearrangement of vicinal hydroxyl to form carbonyls in low pH environments. An obvious increase in C═O/C-O was induced in low pH and was positively correlated with a peroxidase-like activity. The FNPs exerted an excellent effect on H. pylori eradication in vitro and in vivo because of their peroxidase-like activity. FNP treatment of a H. pylori biofilm revealed that FNPs broke down polysaccharides in cell wall components, resulting in collapse of the bacteria. The cycles of FNPs combining and dissociating with the peroxidase substrate were detected by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and confirmed that FNPs enhance peroxidase-like activity. Further, the isothermal titration calorimetry results showed that FNPs with more C═O/C-O had greater affinity to bind the peroxidase substrates. Therefore, we suggest that varied C═O/C-O serves as a switch to respond to low pH in the stomach to kill H. pylori by inducing a peroxidase-like activity. FNPs can also overcome the challenge of antibiotic resistance to achieve H. pylori eradication in the stomach.

Comprehensive analysis of Helicobacter pylori infection-associated diseases based on miRNA-mRNA interaction network

Helicobacter pylori (H. pylori) infection remains a cause of significant morbidity and mortality worldwide. Comprehensive understanding of the pathogenic mechanism of H. pylori and its interaction with host will contribute to developing novel prophylactical and therapeutical strategies. Here, we first determined microRNA (miRNA) levels in H. pylori-infected patients with gastritis, duodenal ulcer, gastric cancer or mucosa-associated lymphoid tissue lymphoma using miRNA data sets. Thirty-four differentially expressed miRNAs were identified and functional enrichment analysis of those miRNA target genes revealed that H. pylori infection were strongly associated with pathway in cancer and regulation of mRNA synthesis. Using disease connectivity analysis of 28 hub genes, we found that H. pylori may increase the risk of many extragastric diseases (e.g. cardiovascular disease, hemic and lymphatic diseases and nervous system disease). Altogether, our integrated analysis provided a new method to predict pathogen–human disease connectivity based on miRNA-mRNA interaction network and indicated anti-H. pylori therapy as an effective means of human diseases prevention.

Perivascular Lymphocyte Clusters Induced by Gastric Subserous Layer Vaccination Mediate Optimal Immunity against Helicobacter through Facilitating Immune Cell Infiltration and Local Antibody Response

Background

In situ vaccination-induced local inflammatory response resulted in the establishment of a pool of tissue-resident memory T (T_RM) cells and new vessels after the resolution of inflammation. T_RM cells have received increasing attention; however, the role of new vessels in protective response is still unknown.

Materials and Methods

We performed the laparotomy to access the stomach and injected alum-based vaccine into the gastric subserous layer (GSL). At 28 days post vaccination, a parabiosis mouse model along with depletion of anti-CD90.2 antibody was employed to explore the function of perivascular lymphocyte clusters in recall responses. The composition of the gastric lymphocyte clusters was analyzed by immunofluorescence staining. Antibody responses were detected using ELISA. Gastric lymphocytes were analyzed using flow cytometry.

Results

GSL vaccination induced the formation of new vessels in the inflamed region. These new vessels were different from native vessels in that they were generally accompanied by perivascular lymphocyte clusters that mainly consisted of CD90-expressing cells. Additionally, histological analysis revealed the presence of CD4⁺ and CD8⁺ T cells in the perivascular lymphocyte clusters. Administration of a dose of an anti-CD90.2 antibody to GSL-vaccinated mice resolved these clusters. The efficacy of protection was compared in the parabiosis mice. Upon challenge, the presence of perivascular lymphocyte clusters was responsible for the fast recall response, as depletion of these clusters by CD90.2 antibody administration resulted in decreased expressions of VCAM-1, Madcam-1, and TNF-α, as well as lower recruitment of proinflammatory immune cells, decreased antibody levels, and poor protection.

Conclusions

Our research demonstrates that in situ vaccination-induced regional inflammatory response contributes to optimal recall response not only by establishing a CD4⁺ T_RM pool but also by creating an “expressway,” i.e., perivascular lymphocyte cluster.

The frequency of circulating integrin α4β7+ cells correlates with protection against Helicobacter pylori infection in immunized mice

BACKGROUND

Chronic Helicobacter pylori infection is the cause of peptic ulcers in a subpopulation of individuals and a risk factor for the development of gastric cancer. A vaccine against H pylori infection can prevent the acquisition of the infection and protect against reinfections. Clinical trials to date evaluating the efficacy of H pylori vaccines in human challenge models have shown moderate to poor protection with difficulties in predicting efficacy. Thus, while further studies are needed to design an effective vaccine, we also need to find relevant correlates for vaccine efficacy.

OBJECTIVE

To find immune correlates to vaccine efficacy, the frequencies of neutrophils, eosinophils and inflammatory monocytes and CD4⁺ T-cell memory and mucosa homing integrin α4β7⁺ cells were assessed by flow cytometry in the blood of mice after vaccination.

MATERIALS AND METHODS

H pylori antigens and cholera toxin or the multiple mutant CT (mmCT) were administered via the sublingual (SL) and intragastric route (IG). The vaccinated mice were infected with H pylori strain SS1 bacteria, and colonization in the stomach and immune responses were evaluated.

RESULTS

The H pylori vaccine was effective in reducing bacterial load in the stomach of mice and enhancing immune responses compared to unvaccinated infection controls. In the blood of mice after SL or IG route of vaccination, we observed changes in frequencies of innate and adaptive immune cell subsets compared to infection controls. Remarkably, the frequency of circulating mucosal homing α4β7⁺ CD4⁺ T cells after vaccination correlated with low bacterial load in the stomach of individual mice irrespective of the immunization route.

CONCLUSIONS

Our study shows that the innate and adaptive immune cell subsets can be measured in the blood after vaccination and that increased frequency of α4β7⁺ CD4⁺ in the blood after immunization could be used as a predictive marker for the efficacy of vaccine against H pylori infection.

A mass spectrometry guided approach for the identification of novel vaccine candidates in gram-negative pathogens

Vaccination is the most effective method to prevent infectious diseases. However, approaches to identify novel vaccine candidates are commonly laborious and protracted. While surface proteins are suitable vaccine candidates and can elicit antibacterial antibody responses, systematic approaches to define surfomes from gram-negatives have rarely been successful. Here we developed a combined discovery-driven mass spectrometry and computational strategy to identify bacterial vaccine candidates and validate their immunogenicity using a highly prevalent gram-negative pathogen, Helicobacter pylori, as a model organism. We efficiently isolated surface antigens by enzymatic cleavage, with a design of experiment based strategy to experimentally dissect cell surface-exposed from cytosolic proteins. From a total of 1,153 quantified bacterial proteins, we thereby identified 72 surface exposed antigens and further prioritized candidates by computational homology inference within and across species. We next tested candidate-specific immune responses. All candidates were recognized in sera from infected patients, and readily induced antibody responses after vaccination of mice. The candidate jhp_0775 induced specific B and T cell responses and significantly reduced colonization levels in mouse therapeutic vaccination studies. In infected humans, we further show that jhp_0775 is immunogenic and activates IFNγ secretion from peripheral CD4+ and CD8+ T cells. Our strategy provides a generic preclinical screening, selection and validation process for novel vaccine candidates against gram-negative bacteria, which could be employed to other gram-negative pathogens.

Review of current diagnostic methods and advances in Helicobacter pylori diagnostics in the era of next generation sequencing

Helicobacter pylori (H. pylori) infection is highly prevalent in the human population and may lead to severe gastrointestinal pathology including gastric and duodenal ulcers, mucosa associated tissue lymphoma and gastric adenocarcinoma. In recent years, an alarming increase in antimicrobial resistance and subsequently failing empiric H. pylori eradication therapies have been noted worldwide, also in many European countries. Therefore, rapid and accurate determination of H. pylori’s antibiotic susceptibility prior to the administration of eradication regimens becomes ever more important. Traditionally, detection of H. pylori and its antimicrobial resistance is done by culture and phenotypic drug susceptibility testing that are cumbersome with a long turn-around-time. Recent advances in diagnostics provide new tools, like real-time polymerase chain reaction (PCR) and line probe assays, to diagnose H. pylori infection and antimicrobial resistance to certain antibiotics, directly from clinical specimens. Moreover, high-throughput whole genome sequencing technologies allow the rapid analysis of the pathogen’s genome, thereby allowing identification of resistance mutations and associated antibiotic resistance. In the first part of this review, we will give an overview on currently available diagnostic methods for detection of H. pylori and its drug resistance and their implementation in H. pylori management. The second part of the review focusses on the use of next generation sequencing technology in H. pylori research. To this end, we conducted a literature search for original research articles in English using the terms “Helicobacter”, “transcriptomic”, “transcriptome”, “next generation sequencing” and “whole genome sequencing”. This review is aimed to bridge the gap between current diagnostic practice (histology, rapid urease test, H. pylori culture, PCR and line probe assays) and new sequencing technologies and their potential implementation in diagnostic laboratory settings in order to complement the currently recommended H. pylori management guidelines and subsequently improve public health.

Therapeutic Protection Against H. pylori Infection in Mongolian Gerbils by Oral Immunization With a Tetravalent Epitope-Based Vaccine With Polysaccharide Adjuvant

Urease is an effective target for design of a therapeutic epitope vaccine against Helicobacter pylori (H. pylori). In our previous studies, an epitope vaccine CTB-UE containing Th and B epitopes from H. pylori urease was constructed, and the CTB-UE vaccine could provide therapeutic effect on H. pylori infection in mice. However, a multivalent vaccine, combining different antigens participating in different aspects of H. pylori colonization and pathogenesis, may be more effective as a therapeutic vaccine than a univalent vaccine targetting urease. Therefore, a multivalent epitope vaccine FVpE, containing Th1-type immune adjuvant NAP, three selected functional fragments from CagA and VacA, and an urease multi-epitope peptide (UE) from CTB-UE, was constructed in this study and expected to obtain better sterilizing immunity than the univalent epitope vaccine CTB-UE. The therapeutic effect of multivalent epitope vaccine FVpE with polysaccharide adjuvant (PA) was evaluated in H. pylori-infected Mongolian gerbil model. The results showed that both FvpE and CTB-UE vaccine could induce similar levels of specific antibodies against H. pylori urease, and had similar inhibition effect on H. pylori urease activity. However, only FVpE could induce high levels of specific antibodies to CagA, VacA, and NAP. In addition, oral therapeutic immunization with FVpE plus PA significantly reduced the number of H. pylori colonies in the stomach of Mongolian gerbils compared with oral immunization with CTB-UE plus PA, or FVpE only, and the FVpE vaccine with PA even exhibited sterilizing immunity. The protection of FVpE was related to the mixed CD4⁺ T cell responses and epitope-specific antibodies against various H. pylori antigens. These results indicate that a multivalent epitope vaccine targetting various H. pylori antigens could be a promising candidate against H. pylori infection.

Gastric Subserous Vaccination With Helicobacter pylori Vaccine: An Attempt to Establish Tissue-Resident CD4+ Memory T Cells and Induce Prolonged Protection

Tissue-resident memory T (Trm) cells are enriched at the sites of previous infection and required for enhanced protective immunity. However, the emergence of Trm cells and their roles in providing protection are unclear in the field of Helicobacter pylori (H. pylori) vaccinology. Here, our results suggest that conventional vaccine strategies are unable to establish a measurable antigen (Ag)-specific memory cell pool in stomach; in comparison, gastric subserous injection of mice with micro-dose of Alum-based H. pylori vaccine can induce a pool of local CD4+ Trm cells. Regional recruitment of Ag-specific CD4+ T cells depends on the engagement of Ag and adjuvant-induced inflammation. Prior subcutaneous vaccination enhanced this recruitment. A stable pool of Ag-specific CD4+ T cells can be detected for 240 days. Two weeks of FTY720 administration in immune mice suggests that these cells do not experience the recirculation. Immunohistochemistry results show that close to the vaccination site, abundant CD4+T cells locate on epithelial niches, independent of lymphocyte cluster. Paradigmatically, Ag-specific CD4+ T cells with a phenotype of CD69+CD103- are preferential on lymphocytes isolated from epithelium. Upon Helicobacter infection, CD4+ Trm cells orchestrate a swift recall response with the recruitment of circulating antigen-specific Th1/Th17 cells to trigger a tissue-wide pathogen clearance. This study investigates the vaccine-induced gastric CD4+ Trm cells in a mice model, and highlights the need for designing a vaccine strategy against H. pylori by establishing the protective CD4+ Trm cells.

Toxic adjuvants alter the function and phenotype of dendritic cells to initiate adaptive immune responses induced by oral Helicobacter pylori vaccines

BACKGROUND

Toxic adjuvant is considered as an indispensable constituent for oral Helicobacter pylori (H. pylori) vaccines. However, the elaborate role of toxic adjuvant in the initiation of adaptive immune response is largely undescribed.

MATERIALS AND METHODS

We employed an acid-resistant HP55/PLGA nanoparticles (NPs) delivery system encapsulating three antigens (Hsp, Nap, and Lpp20) from H. pylori and accompanied with three adjuvants (LPS, CpG, and chimeric flagellum (CF)) to explore the underlying mechanism of the adjuvant constituent. H. pylori-specific antibody responses were detected by ELISA. Gastric inflammatory and Th1/Th17 responses were analyzed by flow cytometry. Expressions of inflammatory cytokines were measured by quantitative real-time PCR.

RESULTS

In bone marrow-derived dendritic cells' (BMDCs) model, the addition of toxic adjuvants is responsible for the proinflammatory function, but not the mature phenotype of BMDCs. In vivo, intestinal loop injection with NPs + LPS, rather than NPs alone, altered the dendritic cell (DC) phenotypes in mesenteric lymph nodes and drove a local proinflammatory microenvironment. In a prophylactic vaccination model, mice immunized with NPs + adjuvants significantly reduced the gastric colonization of H. pylori, induced antigen-specific antibody responses and Th1/Th17 cell responses. After H. pylori challenge, these mice showed potent recall responses involving both neutrophil and inflammatory monocyte infiltration. Additionally, TLR4 knockout mice were immunized with NPs + LPS and NPs + CF, respectively; only the recipients of NPs + CF orchestrated a protective response to control bacterial infection.

CONCLUSIONS

Our study indicated that toxic adjuvants within oral H.pylori vaccines altered the function and phenotype of dendritic cells and facilitated the establishment of proinflammatory microenvironment to initiate adaptive immune responses.

Immunization with a recombinant fusion protein protects mice against Helicobacter pylori infection

More than 50% of the world's population is infected with the bacterium Helicobacter pylori. If left untreated, infection with H. pylori can cause chronic gastritis and peptic ulcer disease, which may progress into gastric cancer. Owing to the limited efficacy of anti-H. pylori antibiotic therapy in clinical practice, the development of a protective vaccine to combat this pathogen has been a tempting goal for several years. In this study, a chimeric gene coding for the antigenic parts of H. pylori FliD, UreB, VacA, and CagL was generated and expressed in bacteria and the potential of the resulting fusion protein (rFUVL) to induce humoral and cellular immune responses and to provide protection against H. pylori infection was evaluated in mice. Three different immunization adjuvants were tested along with rFUVL: CpG oligodeoxynucleotides (CpG ODN), Addavax, and Cholera toxin subunit B. Compared to the control group that had received PBS, vaccinated mice showed significantly higher cellular recall responses and antigen-specific IgG2a, IgG1, and gastric IgA antibody titers. Importantly, rFUVL immunized mice exhibited a reduction of about three orders of magnitude in their stomach bacterial loads. Thus, adjuvanted rFUVL might be considered as a promising vaccine candidate for the control of H. pylori infection.

Protection Against Helicobacter pylori Infection in BALB/c Mouse Model by Oral Administration of Multivalent Epitope-Based Vaccine of Cholera Toxin B Subunit-HUUC

Vaccination is an increasingly important alternative approach to control Helicobacter pylori infection, since H. pylori resistance to previously efficacious antibiotic regimens is increased, and H. pylori eradication treatment for upper gastrointestinal diseases is becoming less successful. Fortunately, an efficient oral monovalent H. pylori vaccine has been developed. However, compared with monovalent vaccines, multivalent vaccines have the potential to induce more effective and comprehensive protection against H. pylori infection. In this study, we designed and produced a multivalent epitope-based vaccine cholera toxin B subunit (CTB)-HUUC with the intramucosal adjuvant CTB and tandem copies of B-cell epitopes (HpaA132-141, UreA183-203, and UreB321-339) and T-cell epitopes (HpaA88-100, UreA27-53, UreB229-251, UreB317-329, UreB373-385, UreB438-452, UreB546-561, CagA149-164, and CagA196-217) from H. pylori adhesion A subunit (HpaA), urease A subunit (UreA), urease B subunit (UreB), and cytotoxin-associated antigen (CagA). Serum IgG, stomach, and intestine mucosal sIgA from mice after CTB-HUUC vaccination neutralized H. pylori urease activity in vitro. CTB-HUUC vaccination promoted H. pylori-specific lymphocyte responses and a mixed CD4⁺ T cell immune response as indicated by IFN-γ, interleukin-4, and interleukin-17 production in mice. Both oral prophylactic and therapeutic CTB-HUUC vaccinations reduced gastric urease activity and H. pylori infection and protected stomachs in mice. Taken together, CTB-HUUC is a promising potent and safe multivalent vaccine in controlling H. pylori infection in BALB/c mouse model.

Status of vaccine research and development for Helicobacter pylori

Gastric adenocarcinoma is globally the third leading cause of death due to malignancy, with the bulk of this disease burden being suffered by low and middle income countries (LMIC), especially in Asia. The majority of these cancers develop as a result of a chronic gastritis that arises in response to infection with the stomach-dwelling bacterium, Helicobacter pylori. A vaccine against this pathogen would therefore be a powerful tool for preventing gastric adenocarcinoma. However, notwithstanding a proof-of-concept that vaccination can protect children from acquisition of H. pylori infection, there are currently no advanced vaccine candidates with only a single vaccine in Phase I clinical trial. Further, the development of a vaccine against H. pylori is not a current strategic priority of major pharmaceutical companies despite the large global disease burden. Given the involvement of such companies is likely to be critical for late stage development, there is therefore a need for an increased appreciation of the burden of this disease in LMIC and more investment to reinvigorate research in H. pylori vaccine Research and Development.

Immunologic properties and therapeutic efficacy of a multivalent epitope-based vaccine against four Helicobacter pylori adhesins (urease, Lpp20, HpaA, and CagL) in Mongolian gerbils

BACKGROUND

Therapeutic vaccination is a desirable alternative for controlling Helicobacter pylori (H. pylori) infection. Attachment to the gastric mucosa is the first step in establishing bacterial colonization, and adhesins, which are on the surface of H. pylori, play a pivotal role in binding to human gastric mucosa.

MATERIALS AND METHODS

In the present study, we constructed a multivalent epitope-based vaccine named CFAdE with seven carefully selected antigenic fragments from four H. pylori adhesins (urease, Lpp20, HpaA and CagL). The specificity, immunogenicity and ability to produce neutralizing antibodies of CFAdE were evaluated in BALB/c mice. After that, its therapeutic efficacy and protective immune mechanisms were explored in H. pylori-infected Mongolian gerbils.

RESULTS

The results indicated that CFAdE could induce comparatively high levels of specific antibodies against urease, Lpp20, HpaA and CagL. Additionally, oral therapeutic immunization with CFAdE plus polysaccharide adjuvant (PA) significantly decreased H. pylori colonization compared with oral immunization with urease plus PA, and the protection was correlated with IgG and sIgA antibody and antigen-specific CD4⁺ T cells.

CONCLUSIONS

This study indicated that the multivalent epitope-based vaccine, which targeted multiple adhesins in adherence of H. pylori to the gastric mucosa, is more effective than the univalent vaccine targeting urease only. This multivalent epitope-based vaccine may be a promising therapeutic candidate vaccine against H. pylori infection.

Oral Immunization with a Multivalent Epitope-Based Vaccine, Based on NAP, Urease, HSP60, and HpaA, Provides Therapeutic Effect on H. pylori Infection in Mongolian gerbils

Epitope-based vaccine is a promising strategy for therapeutic vaccination against Helicobacter pylori (H. pylori) infection. A multivalent subunit vaccine containing various antigens from H. pylori is superior to a univalent subunit vaccine. However, whether a multivalent epitope-based vaccine is superior to a univalent epitope-based vaccine in therapeutic vaccination against H. pylori, remains unclear. In this study, a multivalent epitope-based vaccine named CWAE against H. pylori urease, neutrophil-activating protein (NAP), heat shock protein 60 (HSP60) and H. pylori adhesin A (HpaA) was constructed based on mucosal adjuvant cholera toxin B subunit (CTB), Th1-type adjuvant NAP, multiple copies of selected B and Th cell epitopes (UreA_27–53, UreA_183–203, HpaA_132–141, and HSP60_189–203), and also the epitope-rich regions of urease B subunit (UreB_158–251 and UreB_321–385) predicted by bioinformatics. Immunological properties of CWAE vaccine were characterized in BALB/c mice model. Its therapeutic effect was evaluated in H. pylori-infected Mongolian gerbil model by comparing with a univalent epitope-based vaccine CTB-UE against H. pylori urease that was constructed in our previous studies. Both CWAE and CTB-UE could induce similar levels of specific antibodies against H. pylori urease, and had similar inhibition effect of H. pylori urease activity. However, only CWAE could induce high levels of specific antibodies to NAP, HSP60, HpaA, and also the synthetic peptides epitopes (UreB_158–172, UreB_181–195, UreB_211–225, UreB_349–363, HpaA_132–141, and HSP60_189–203). In addition, oral therapeutic immunization with CWAE significantly reduced the number of H. pylori colonies in the stomach of Mongolian gerbils, compared with oral immunization using CTB-UE or H. pylori urease. The protection of CWAE was associated with higher levels of mixed CD4⁺ T cell (Th cell) response, IgG, and secretory IgA (sIgA) antibodies to H. pylori. These results indic ate that a multivalent epitope-based vaccine including Th and B cell epitopes from various H. pylori antigens could be a promising candidate against H. pylori infection.

A global burden of gastric cancer: the major impact of China

Gastric cancer (GC) is a highly aggressive cancer and a major cause of cancer-related deaths worldwide. Approximately half of the world's GC cases and deaths occur in china. GC presents challenges in early diagnosis and effective therapy due to a lack of understanding of the underlying molecular biology. The primary goals of this review are to outline current GC research in china and describe future trends in this field. Areas covered: This review mainly focuses on a series of GC-related advances China has achieved. Considerable progress has been made in understanding the role of H. pylori in GC by a series of population-based studies in well-established high-risk areas; A few germline and somatic alterations have been identified by 'omics' studies; Studies on the mechanisms of malignant phenotypes have helped us to form an in-depth understanding of GC and advance drug discovery. Moreover, identification of potential biomarkers and targeted therapies have facilitated the diagnosis and treatment of GC. However, many challenges remain. Expert commentary: To combat GC, sufficient funding is important. More attention should be paid on early diagnosis and the discovery of novel efficient biomarkers and the development of biomarker-based or targeted therapeutics in GC.

Pangenome and immuno-proteomics analysis of Acinetobacter baumannii strains revealed the core peptide vaccine targets

BACKGROUND

Acinetobacter baumannii has emerged as a significant nosocomial pathogen during the last few years, exhibiting resistance to almost all major classes of antibiotics. Alternative treatment options such as vaccines tend to be most promising and cost effective approaches against this resistant pathogen. In the current study, we have explored the pan-genome of A. baumannii followed by immune-proteomics and reverse vaccinology approaches to identify potential core vaccine targets.

RESULTS

The pan-genome of all available A. baumannii strains (30 complete genomes) is estimated to contain 7,606 gene families and the core genome consists of 2,445 gene families (~32 % of the pan-genome). Phylogenetic tree, comparative genomic and proteomic analysis revealed both intra- and inter genomic similarities and evolutionary relationships. Among the conserved core genome, thirteen proteins, including P pilus assembly protein, pili assembly chaperone, AdeK, PonA, OmpA, general secretion pathway protein D, FhuE receptor, Type VI secretion system OmpA/MotB, TonB dependent siderophore receptor, general secretion pathway protein D, outer membrane protein, peptidoglycan associated lipoprotein and peptidyl-prolyl cis-trans isomerase are identified as highly antigenic. Epitope mapping of the target proteins revealed the presence of antigenic surface exposed 9-mer T-cell epitopes. Protein-protein interaction and functional annotation have shown their involvement in significant biological and molecular processes. The pipeline is validated by predicting already known immunogenic targets against Gram negative pathogen Helicobacter pylori as a positive control.

CONCLUSION

The study, based upon combinatorial approach of pan-genomics, core genomics, proteomics and reverse vaccinology led us to find out potential vaccine candidates against A. baumannii. The comprehensive analysis of all the completely sequenced genomes revealed thirteen putative antigens which could elicit substantial immune response. The integration of computational vaccinology strategies would facilitate in tackling the rapid dissemination of resistant A.baumannii strains. The scarcity of effective antibiotics and the global expansion of sequencing data making this approach desirable in the development of effective vaccines against A. baumannii and other bacterial pathogens.

Gastric cancer: somatic genetics as a guide to therapy

Gastric cancer is the leading cause of cancer-related mortality across the world, with poor prognosis and a median overall survival of ≤12 months for advanced stage gastric cancer. Environmental, genetic and other predisposing factors contribute to the development of gastric cancer and a predominant factor was found to be infection of Helicobacter pylori Advances in understanding the deranged signalling pathways that are critical for normal cellular homeostasis helped in the development of novel drugs that target specific proteins and pathways to curtail the growth of gastric cancer. Genetic studies revealed several single nucleotide polymorphisms, chromosomal aberrations and epigenetic alterations that likely play a major role in elevating the susceptibility to develop gastric cancer. Methylation pattern of specific genes may likely prove to be a valid biomarker for early detection of gastric cancer, but much progress is needed to establish specific markers. Important developments have been made in targeting human epidermal growth factor receptor-2 and vascular endothelial growth factor receptor 2 for treating advanced gastro-oesophageal junction cancer, using specific monoclonal antibodies. Lack of efficacy with regard to targeting other signalling pathways including mesenchymal-epithelial transition/hepatocyte growth factor and mammalian target of rapamycin is probably due to suboptimal patient selection for these clinical trials, which is probably due to the lack of appropriate biomarkers, to decide on responsive patient population. Besides the development of antagonists for the cell growth-related signalling pathways, advances are also being made to tackle gastric cancer by immunotherapies, targeting immune check-points, which may hold promise for better treatment options in future.

TolC plays a crucial role in immune protection conferred by Edwardsiella tarda whole-cell vaccines

Although vaccines developed from live organisms have better efficacy than those developed from dead organisms, the mechanisms underlying this differential efficacy remain unexplored. In this study, we combined sub-immunoproteomics with immune challenge to investigate the action of the outer membrane proteome in the immune protection conferred by four Edwardsiella tarda whole-cell vaccines prepared via different treatments and to identify protective immunogens that play a key role in this immune protection. Thirteen spots representing five outer membrane proteins and one cytoplasmic protein were identified, and it was found that their abundance was altered in relation with the immune protective abilities of the four vaccines. Among these proteins, TolC and OmpA were found to be the key immunogens conferring the first and second highest degrees of protection, respectively. TolC was detected in the two effective vaccines (live and inactivated-30-F). The total antiserum and anti-OmpA titers were higher for the two effective vaccines than for the two ineffective vaccines (inactivated-80-F and inactivated-100). Further evidence demonstrated that the live and inactivated-30-F vaccines demonstrated stronger abilities to induce CD8+ and CD4+ T cell differentiation than the other two evaluated vaccines. Our results indicate that the outer membrane proteome changes dramatically following different treatments, which contributes to the effectiveness of whole-cell vaccines.

Gastric Cancer: How Can We Reduce the Incidence of this Disease?

Gastric cancer remains a prevalent disease worldwide with a poor prognosis. Helicobacter pylori plays a major role in gastric carcinogenesis. H. pylori colonization leads to chronic gastritis, which predisposes to atrophic gastritis, intestinal metaplasia, dysplasia, and eventually gastric cancer. Screening, treatment, and prevention of H. pylori colonization can reduce the incidence of gastric cancer. Other interventions that may yield a similar effect, although of smaller magnitude, include promotion of a healthy lifestyle including dietary measures, non-smoking, low alcohol intake, and sufficient physical activity. This chapter reviews interventions that can lead to a decline in gastric cancer incidence in high and low incidence countries.

Production of IFN-γ and IL-4 Against Intact Catalase and Constructed Catalase Epitopes of Helicobacter pylori From T-Cells

Background:

Helicobacter pylori infection is highly prevalent in the developing countries. It causes gastritis, peptic ulcer disease, and gastrocarcinoma. Treatment with drugs and antibiotics is problematic due to the following reasons: cost, resistance to antibiotics, prolonged treatment and using multiple drugs. Catalase is highly conserved among the Helicobacter species and is important to the survival of the organism. It is expressed in high amounts and is exposed to the surface of this bacterium; therefore it represents a suitable candidate vaccine antigen.

Objectives:

A suitable approach in H. pylori vaccinology is the administration of epitope based vaccines. Therefore the responses of T-cells (IFN-γ and IL-4 production) against the catalase of H. pylori were determined. Then the quality of the immune responses against intact catalase and three epitopes of catalase were compared.

Materials and Methods:

In this study, a composition of three epitopes of the H. pylori catalase was selected based on Propred software. The effect of catalase epitopes on T-cells were assayed and immune responses identified.

Results:

The results of IFN-γ, IL-4 production against antigens, epitopes, and recombinant catalase by T-cells were compared for better understanding of epitope efficiency.

Conclusions:

The current research demonstrated that epitope sequence stimulates cellular immune responses effectively. In addition, increased safety and potency as well as a reduction in time and cost were advantages of this method. Authors are going to use this sequence as a suitable vaccine candidate for further research on animal models and humans in future.

Role of Helicobacter pylori infection in gastric carcinogenesis: Current knowledge and future directions

Helicobacter pylori (H. pylori) plays a role in the pathogenesis of gastric cancer. The outcome of the infection depends on environmental factors and bacterial and host characteristics. Gastric carcinogenesis is a multistep process that is reversible in the early phase of mucosal damage, but the exact point of no return has not been identified. Therefore, two main therapeutic strategies could reduce gastric cancer incidence: (1) eradication of the already present infection; and (2) immunization (prior to or during the course of the infection). The success of a gastric cancer prevention strategy depends on timing because the prevention strategy must be introduced before the point of no return in gastric carcinogenesis. Although the exact point of no return has not been identified, infection should be eradicated before severe atrophy of the gastric mucosa develops. Eradication therapy rates remain suboptimal due to increasing H. pylori resistance to antibiotics and patient noncompliance. Vaccination against H. pylori would reduce the cost of eradication therapies and lower gastric cancer incidence. A vaccine against H. pylori is still a research challenge. An effective vaccine should have an adequate route of delivery, appropriate bacterial antigens and effective and safe adjuvants. Future research should focus on the development of rescue eradication therapy protocols until an efficacious vaccine against the bacterium becomes available.

Immunodominant epitope-specific Th1 but not Th17 responses mediate protection against Helicobacter pylori infection following UreB vaccination of BALB/c mice

Helicobacter pylori (H. pylori) infects more than half of the world’s population, causing chronic gastritis, peptic ulcers and gastric cancer. Urease B subunit (UreB), a conserved protein of H. pylori, is capable of inducing specific CD4⁺ T-cell responses and provides protection against this infection. Previous studies have confirmed the effectiveness of rUreB subunit vaccines in generating CD4⁺ T-cell-mediated protection, but less is known regarding the roles of different subtypes of T-cell immunity, such as Th1, Th2 and Th17, particularly the immunodominant epitopes inducing specific CD4⁺ T-cell responses, in vaccine-mediated protection. In this study, we demonstrated that the vaccination of BALB/c mice with rUreB resulted in significant antigen-specific Th1 and Th17 immune responses. Importantly, two novel Th epitopes, UreB_317–329 and UreB_409–421, which are recognized by a major population of CD4⁺ T cells, were identified in immunized mice. Our results demonstrated that two novel epitopes can simultaneously induce Th1 and Th17 immune responses; however, only the epitope vaccine-induced CD4⁺ T-cells secreting IFN-γ mediated the protection against H. pylori; cells secreting IL-17A did not. Taken together, our results suggest that two novel immunodominant epitopes can induce Th1 and Th17 immune responses, but only the induced Th1 lymphocytes mediate protection against H. pylori.

Defining the Roles of IFN-γ and IL-17A in Inflammation and Protection against Helicobacter pylori Infection

CD4⁺ T cells have been shown to be essential for vaccine-induced protection against Helicobacter pylori infection. However, the effector mechanisms leading to reductions in the gastric bacterial loads of vaccinated mice remain unclear. We have investigated the function of IFN-γ and IL-17A for vaccine-induced protection and inflammation (gastritis) using IFN-γ-gene-knockout (IFN-γ^-/-) mice, after sublingual or intragastric immunization with H. pylori lysate antigens and cholera toxin. Bacteria were enumerated in the stomachs of mice and related to the gastritis score and cellular immune responses. We report that sublingually and intragastrically immunized IFN-γ^-/- mice had significantly reduced bacterial loads similar to immunized wild-type mice compared to respective unimmunized infection controls. The reduction in bacterial loads in sublingually and intragastrically immunized IFN-γ^-/- mice was associated with significantly higher levels of IL-17A in stomach extracts and lower gastritis scores compared with immunized wild-type mice. To study the role of IL-17A for vaccine-induced protection in sublingually immunized IFN-γ^-/- mice, IL-17A was neutralized in vivo at the time of infection. Remarkably, the neutralization of IL-17A in sublingually immunized IFN-γ^-/- mice completely abolished protection against H. pylori infection and the mild gastritis. In summary, our results suggest that IFN-γ responses in the stomach of sublingually immunized mice promote vaccine-induced gastritis, after infection with H. pylori but that IL-17A primarily functions to reduce the bacterial load.

Protection against Helicobacter pylori infection in BALB/c mice by oral administration of multi-epitope vaccine of CTB-UreI-UreB

Chronic gastric infection by the Gram-negative bacterium Helicobacter pylori (H. pylori) is strongly associated with gastritis, gastric ulcer and the development of distal gastric carcinoma and gastric mucosal lymphoma in humans. Antibiotic treatment of H. pylori is becoming less effective because of increasing antibiotic resistance; other treatment approaches such as specifically targeted methods, etc. to destroy this organism would be beneficial. An epitope vaccine is a promising option for protection against H. pylori infection. In this study, a multi-epitope vaccine was constructed by linking cholera toxin B subunit (CTB), two antigenic fragments of H. pylori urease I subunit (UreI20-29, UreI98-107) and four antigenic fragments of H. pylori urease B subunit (UreB12-23, UreB229-251, UreB327-400, UreB515-561), resulting in the recombinant CTB-UreI-UreB (BIB). Its protective effect against H. pylori infection was evaluated in BALB/c mice. Significant protection against H. pylori challenge was achieved in BALB/c mice immunized with BIB (15/18, 83.3%), rIB plus rCTB (6/18, 33.3%) and rIB (2/18, 11.1%) separately, while no protective effect was found in the mice immunized with either adjuvant rCTB alone or PBS. The induction of significant protection against H. pylori is possibly mediated by specific serum IgA and mucosal sIgA antibodies, and a mixed Th1/Th2/Th17 cells response. This multi-epitope vaccine might be a promising vaccine candidate that helps to control H. pylori infection.

Helicobacter pylori update: gastric cancer, reliable therapy, and possible benefits

Helicobacter pylori infection contributes to the development of diverse gastric and extragastric diseases. The infection is necessary but not sufficient for the development of gastric adenocarcinoma. Its eradication would eliminate a major worldwide cause of cancer death, therefore there is much interest in identifying how, if, and when this can be accomplished. There are several mechanisms by which H pylori contributes to the development of gastric cancer. Gastric adenocarcinoma is one of many cancers associated with inflammation, which is induced by H pylori infection, yet the bacteria also cause genetic and epigenetic changes that lead to genetic instability in gastric epithelial cells. H pylori eradication reduces both. However, many factors must be considered in determining whether treating this bacterial infection will prevent cancer or only reduce its risk-these must be considered in designing reliable and effective eradication therapies. Furthermore, H pylori infection has been proposed to provide some benefits, such as reducing the risks of obesity or childhood asthma. When tested, these hypotheses have not been confirmed and are therefore most likely false.

Overview of the phytomedicine approaches against Helicobacter pylori

Helicobacter pylori (H. pylori) successfully colonizes the human stomach of the majority of the human population. This infection always causes chronic gastritis, but may evolve to serious outcomes, such as peptic ulcer, gastric carcinoma or mucosa-associated lymphoid tissue lymphoma. H. pylori first line therapy recommended by the Maastricht-4 Consensus Report comprises the use of two antibiotics and a proton-pomp inhibitor, but in some regions failure associated with this treatment is already undesirable high. Indeed, treatment failure is one of the major problems associated with H. pylori infection and is mainly associated with bacterial antibiotic resistance. In order to counteract this situation, some effort has been allocated during the last years in the investigation of therapeutic alternatives beyond antibiotics. These include vaccines, probiotics, photodynamic inactivation and phage therapy, which are briefly revisited in this review. A particular focus on phytomedicine, also described as herbal therapy and botanical therapy, which consists in the use of plant extracts for medicinal purposes, is specifically addressed, namely considering its history, category of performed studies, tested compounds, active principle and mode of action. The herbs already experienced are highly diverse and usually selected from products with a long history of employment against diseases associated with H. pylori infection from each country own folk medicine. The studies demonstrated that many phytomedicine products have an anti-H. pylori activity and gastroprotective action. Although the mechanism of action is far from being completely understood, current knowledge correlates the beneficial action of herbs with inhibition of essential H. pylori enzymes, modulation of the host immune system and with attenuation of inflammation.