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

Chitosan-LeoA-DNA Nanoparticles Promoted the Efficacy of Novel LeoA-DNA Vaccination on Mice Against Helicobacter pylori

More than half of the world's population is infected with Helicobacter pylori (H. pylori), which may lead to chronic gastritis, peptic ulcers, and stomach cancer. LeoA, a conserved antigen of H. pylori, aids in preventing this infection by triggering specific CD3+ T-cell responses. In this study, recombinant plasmids containing the LeoA gene of H. pylori are created and conjugated with chitosan nanoparticle (CSNP) to immunize BALB/c mice against the H. pylori infection. We used the online Vaxign tool to analyze the genomes of five distinct strains of H. pylori, and we chose the outer membrane as a prospective vaccine candidate. Afterward, the proteins' immunogenicity was evaluated. The DNA vaccine was constructed and then encapsulated in CSNPs. The effectiveness of the vaccine's immunoprotective effects was evaluated in BALB/c mice. Purified activated splenic CD3+ T cells are used to test the anticancer effects in vitro. Nanovaccines had apparent spherical forms, were small (mean size, 150-250 nm), and positively charged (41.3 ± 3.11 mV). A consistently delayed release pattern and an entrapment efficiency (73.35 ± 3.48%) could be established. Compared to the non-encapsulated DNA vaccine, vaccinated BALB/c mice produced higher amounts of LeoA-specific IgG in plasma and TNF-α in splenocyte lysate. Moreover, BALB/c mice inoculated with nanovaccine demonstrated considerable immunity (87.5%) against the H. pylori challenge and reduced stomach injury and bacterial burdens in the stomach. The immunological state in individuals with GC with chronic infection with H. pylori is mimicked by the H. pylori DNA nanovaccines by inducing a shift from Th1 to Th2 in the response. In vitro human GC cell development is inhibited by activated CD3+ T lymphocytes. According to our findings, the H. pylori vaccine-activated CD3+ has potential immunotherapeutic benefits.

Strategies of Helicobacter pylori in evading host innate and adaptive immunity: insights and prospects for therapeutic targeting

Helicobacter pylori (H. pylori) is the predominant pathogen causing chronic gastric mucosal infections globally. During the period from 2011 to 2022, the global prevalence of H. pylori infection was estimated at 43.1%, while in China, it was slightly higher at approximately 44.2%. Persistent colonization by H. pylori can lead to gastritis, peptic ulcers, and malignancies such as mucosa-associated lymphoid tissue (MALT) lymphomas and gastric adenocarcinomas. Despite eliciting robust immune responses from the host, H. pylori thrives in the gastric mucosa by modulating host immunity, particularly by altering the functions of innate and adaptive immune cells, and dampening inflammatory responses adverse to its survival, posing challenges to clinical management. The interaction between H. pylori and host immune defenses is intricate, involving evasion of host recognition by modifying surface molecules, manipulating macrophage functionality, and modulating T cell responses to evade immune surveillance. This review analyzes the immunopathogenic and immune evasion mechanisms of H. pylori, underscoring the importance of identifying new therapeutic targets and developing effective treatment strategies, and discusses how the development of vaccines against H. pylori offers new hope for eradicating such infections.

Helicobacter pylori induces urease subunit B-specific CD8+ T cell responses in infected individuals via cytosolic pathway of cross-presentation

BACKGROUND

Urease subunit B (UreB), a conserved and key virulence factor of Helicobacter pylori (H. pylori), can induce the host CD4+ T cell immune responses to provide protection, but less is known regarding CD8+ T cell responses. The characteristics of H. pylori-specific CD8+ T cell responses and the mechanism underlying antigen processing and presentation pathways remain unclear. This study was focus on protective antigen recombinant UreB (rUreb) to detect specific CD8+ T cell responses in vitro and elucidate the mechanism of UreB antigen processing and presentation.

METHODS

The peripheral blood mononuclear cells (PBMCs) collected from H. pylori-infected individuals were stimulated with rUreB in vitro to detect specific CD8+ T cell responses after co-culture with rUreB-pulsed autologous hMDCs. Through blocking assay, we investigated the potential pathway of UreB antigen processing and presentation via the cytosolic pathway or vacuolar pathway. The cytokines production of UreB specific CD8+ T cell were evaluated as well.

RESULTS

We demonstrated UreB can induce specific CD8+ T cell immune responses in H. pylori infected individuals. Importantly, we characterized that UreB were mainly processed by proteasome instead of lysosomal proteases and presented through cytosolic pathway of cross-presentation, which requires endoplasmic reticulum-Golgi transport and newly synthesized MHC-I molecules, to induce functional-specific CD8+ T cell (IFN-γ + TNF-α + Grz A+ Grz B+) responses.

CONCLUSIONS

These results suggest that H. pylori UreB induces specific CD8+ T cell responses through cytosolic pathway of cross-presentation in infected individuals.

Synthetic Self-Adjuvanted Lipopeptide Vaccines Conferred Protection against Helicobacter pylori Infection

Helicobacter pylori (H. pylori) colonizes the stomach epithelium of half the world's population and is responsible for various digestive diseases and even stomach cancer. Vaccine-mediated protection against H. pylori infection depends primarily on the specific mucosal and T-cell responses. In this study, the synthetic lipopeptide vaccines, Hp4 (Pam2 Cys modified UreB T-cell epitope) and Hp10 (Pam2 Cys modified CagA T/B cell combined epitope), not only induce the bone marrow derived dendritic cells (BMDCs) maturation by activating a variety of pattern-recognition receptors (PRRs) such as Toll-like receptor (TLR), Nod-like receptor (NLR), and retinoic acid-inducing gene (RIG) I-like receptor (RLR), and but also stimulate BMDCs to secret cytokines that have the potential to modulate T-cell activation and differentiation. Although intranasal immunization with Hp4 or Hp10 elicits robust epitope-specific T-cell responses in mice, only Hp10 confers protection against H. pylori infection, possibly due to the fact that Hp10 also induces substantial specific sIgA response at mucosal sites. Interestingly, Hp4 elevates the protective response against H. pylori infection of Hp10 when administrated in combination, characterized by better protective effect and enhanced specific T-cell and mucosal antibody responses. The results suggest that synthetic lipopeptide vaccines based on the epitopes derived from the protective antigens are promising candidates for protection against H. pylori infection.

UreB immunodominant epitope-specific CD8+ T-cell responses were beneficial in reducing gastric symptoms in Helicobacter pylori-infected individuals

BACKGROUND AND AIMS

Although Helicobacter pylori is recognized as an extracellular infection bacterium, it can lead to an increase in the number of CD8⁺ T cells after infection. At present, the characteristics of H. pylori antigen-specific CD8⁺ T cells and the epitope response have not been elucidated. This study was focused on putative protective antigen UreB to detect specific CD8⁺ T-cell responses in vitro and screen for predominant response epitopes.

METHODS

The PBMCs collected from H. pylori-infected individuals were stimulated by UreB peptide pools in vitro to identify the immunodominant CD8⁺ T-cell epitopes. Furthermore, their HLA restriction characteristics were detected accordingly by NGS. Finally, the relationship between immunodominant responses and appearance of gastric symptoms after H. pylori infection was conducted.

RESULTS

UreB-specific CD8⁺ T-cell responses were detected in H. pylori-infected individuals. Three of UreB dominant epitopes (A-2 (UreB_443-451 : GVKPNMIIK), B-4 (UreB_420-428 : SEYVGSVEV), and C-1 (UreB_5-13 : SRKEYVSMY)) were firstly identified and mainly presented by HLA-A*1101, HLA-B*4001 and HLA-C*0702 alleles, respectively. C-1 responses were mostly occurred in H. pylori-infected subjects without gastric symptoms and may alleviate the degree of gastric inflammation.

CONCLUSIONS

The UreB dominant epitope-specific CD8⁺ T-cell response was closely related to the gastric symptoms after H. pylori infection, and the C-1 (UreB_5-13 ) dominant peptides may be protective epitopes.

In Peripheral Blood Mononuclear Cells Helicobacter pylori Induces the Secretion of Soluble and Exosomal Cytokines Related to Carcinogenesis

Helicobacter pylori promotes the secretion of cytokines that regulate inflammation and carcinogenesis. Immune cells secrete cytokines into the extracellular medium or packaged in exosomes. The objective of this study was to analyze the profile of soluble and exosomal cytokines that were secreted by human peripheral blood mononuclear cells (PBMCs) that were infected with H. pylori and to build a network of interaction between cytokines and cellular proteins. PBMCs were obtained by density gradient centrifugation and infected with H. pylori for 24 h. The infection was verified by immunofluorescence and Western blot for CagA. The exosomes were obtained from culture supernatant by ultracentrifugation and characterized by transmission electron microscopy, particle size analysis, and Western blot for CD9 and CD81. Cytokines were quantified using a multiplex immunoassay in the culture supernatant, intact exosomes, and lysed exosomes. H. pylori adheres to lymphocytes and translocates CagA. In PBMCs, H. pylori induces an increase in the soluble and exosomal IL-1β, IL-6, TNF-α, IL-10, IL-17A, IL-21, and IL-22. The protein-protein interaction (PPI) network shows that soluble and exosomal cytokines interact with proteins that participate in signaling pathways such as NF-κB, MAPK, PI3K-Akt, Jak-STAT, FoxO, and mTOR, that are related to carcinogenesis; moreover, TNF-α had the highest number of interactions. Cytokine-loaded exosomes represent another means of intercellular communication that is activated by H. pylori to stimulate inflammation, carcinogenesis, or cancer progression. Cytokine-loaded exosomes are likely to be associated with extragastrointestinal diseases of inflammatory origin.

Oral Immunization With a M Cell-Targeting Recombinant L. Lactis Vaccine LL-plSAM-FVpE Stimulate Protective Immunity Against H. Pylori in Mice

There are many virulence factors of H. pylori that contribute in diverse ways to gastric disease. Therefore, designing multivalent epitope vaccines against many key virulence factors virulence factors of H. pylori is a promising strategy to control H. pylori infection. In previous studies, we constructed a multivalent epitope vaccine FVpE against four key virulence factors of H. pylori (Urease, CagA, VacA, and NAP), and oral immunization with the FVpE vaccine plus a polysaccharide adjuvant (PA) containing lycium barbarum polysaccharide and chitosan could provide protection against H. pylori infection in the Mongolian gerbil model. Oral vaccines have many advantages over injected vaccines, such as improved safety and compliance, and easier manufacturing and administration. However, the harsh gastrointestinal (GI) environment, such as gastric acid and proteolytic enzymes, limits the development of oral vaccines to some extent. Oral vaccines need a gastrointestinal delivery system with high safety, low price and promoting vaccine antigen to stimulate immune response in the gastrointestinal mucosa. Lactic acid bacteria are gastrointestinal probiotics that have unique advantages as a delivery system for oral vaccines. In this study, a M cell-targeting surface display system for L. lactis named plSAM was designed to help vaccine antigens to stimulate effective immune responses in the gastrointestinal tract, and a M cell-targeting recombinant L. lactis vaccine LL-plSAM-FVpE was constructed by using the surface display system plSAM. recombinant L. lactis vaccine LL-plSAM-FVpE could secretively express the SAM-FVpE protein and display it on the bacterial surface. Moreover, experimental results confirmed that LL-plSAM-FVpE had an enhanced M cell-targeting property. In addition, LL-plSAM-FVpE had excellent M cell-targeting property to promote the phagocytosis and transport of the antigen SAM-FVpE by gastrointestinal M cells. More importantly, oral immunization of LL-plSAM-FVpE or SAM-FVpE plus PA can stimulate IgG and sIgA antibodies and CD4⁺ T cell immune responses against four virulence factors of H. pylori (Urease, CagA, VacA, and NAP), thus providing protective immunity against H. pylori infection in mice. The M cell-targeting recombinant L. lactis vaccine against various key H. pylori virulence factors could be a promising vaccine candidate for controlling H. pylori infection.

IL-9 contributes to the host immune response against Helicobacter pylori and helps limit infection in a Mouse Model

BACKGROUND

As an important mediator in lots of diseases, interleukin-9 (IL-9) can be a protector or pro-inflammatory cytokine depending on the complicated inflammatory milieu. Helicobacter pylori (H. pylori) induced a series of immunology cells and cytokines change, and however, the role of IL-9 in H. pylori infection remains unknown.

MATERIALS AND METHODS

Wild-type and IL-9 deficient mice were infected with H. pylori by means of intragastric administration. The colonization of H. pylori bacteria was measured by detecting specific 16s rDNA, and the intensity of inflammation was observed by H&E stain. The expression level of inflammation cytokines was determined by ELISA and quantitative real-time PCR.

RESULTS

IL-9 was increased due to the attack of H. pylori, besides deletion of Il9 aggravated the bacterial colonization and inflammation intensity. In addition, treatment of rmIL-9 reduced colonized H. pylori and inflammation level, indicated that IL-9 was a protector for the host against this bacterium. Followed by the H. pylori infection, interferon (IFN)-γ and interleukin (IL)-17A were up-regulated as expected, and nevertheless, the expression of IL-17A shared a positive relationship with IL-9 while IFN-γ negative associated with IL-9. Moreover, we also proved that Treg cells were not involved in the protective effect of IL-9, and meanwhile, CD4⁺ CD25^- T cells secreted more IFN-γ and less IL-17A in vitro due to the deletion of Il9.

CONCLUSIONS

IL-9 plays a protective role against H. pylori and the protection associated with cytokines change including IFN-γ and IL-17A.

Designing and development of epitope-based vaccines against Helicobacter pylori

Helicobacter pylori infection is the principal cause of serious diseases (e.g. gastric cancer and peptic ulcers). Antibiotic therapy is an inadequate strategy in H. pylori eradication because of which vaccination is an inevitable approach. Despite the presence of countless vaccine candidates, current vaccines in clinical trials have performed with poor efficacy which makes vaccination extremely challenging. Remarkable advancements in immunology and pathogenic biology have provided an appropriate opportunity to develop various epitope-based vaccines. The fusion of proper antigens involved in different aspects of H. pylori colonization and pathogenesis as well as peptide linkers and built-in adjuvants results in producing epitope-based vaccines with excellent therapeutic efficacy and negligible adverse effects. Difficulties of the in vitro culture of H. pylori, high genetic variation, and unfavourable immune responses against feeble epitopes in the complete antigen are major drawbacks of current vaccine strategies that epitope-based vaccines may overcome. Besides decreasing the biohazard risk, designing precise formulations, saving time and cost, and induction of maximum immunity with minimum adverse effects are the advantages of epitope-based vaccines. The present article is a comprehensive review of strategies for designing and developing epitope-based vaccines to provide insights into the innovative vaccination against H. pylori.

Helicobacter urease suppresses cytotoxic CD8 + T cell responses through activating Myh9-dependent induction of PD-L1

As a key virulence factor for persistent colonization, Urease B subunit (UreB) is considered to be an ideal vaccine antigen against Helicobacter pylori (H. pylori) infection. However, the role and molecular mechanisms of UreB involved in immune microenvironment dysregulation still remains largely unknown. In the present study, we evaluated the effects of UreB on macrophage activation and found that UreB induced PD-L1 accumulation on Bone marrow-derived macrophages (BMDMs). Co-culture assays further revealed that UreB-induced PD-L1 expression on BMDMs significantly decreased the proliferation and secretion of cytolytic molecules (granzyme B and perforin) of splenic CD8 + T cells isolated from inactivated H. pylori-immunized mice. More importantly, myosin heavy chain 9 (Myh9) was confirmed to be a direct membrane receptor of UreB via using LC-MS/MS and Co-immunoprecipitation and required for PD-L1 upregulation on BMDMs. Molecular studies further demonstrated that the interaction between UreB and Myh9 decreased GCN2 autophosphorylation and enhanced intracellular pool of amino acids, leading to the upregulation of S6K phosphorylation, a commonly used marker for monitoring activation of mTORC1 signaling activity. Furthermore, blocking mTORC1 activation with its inhibitor Temsirolimus reversed UreB-induced PD-L1 upregulation and the subsequently inhibitory effects of BMDMs on activation of cytotoxic CD8 + T cell responses. Overall, our data unveil a novel immunosuppressive mechanism of UreB during H. pylori infection, which may provide valuable clue for the optimization of H. pylori vaccine.

Immune Polarization Potential of the S. aureus Virulence Factors SplB and GlpQ and Modulation by Adjuvants

Protection against Staphylococcus aureus is determined by the polarization of the anti-bacterial immune effector mechanisms. Virulence factors of S. aureus can modulate these and induce differently polarized immune responses in a single individual. We proposed that this may be due to intrinsic properties of the bacterial proteins. To test this idea, we selected two virulence factors, the serine protease-like protein B (SplB) and the glycerophosphoryl diester phosphodiesterase (GlpQ). In humans naturally exposed to S. aureus, SplB induces a type 2-biased adaptive immune response, whereas GlpQ elicits type 1/type 3 immunity. We injected the recombinant bacterial antigens into the peritoneum of S. aureus-naïve C57BL/6N mice and analyzed the immune response. This was skewed by SplB toward a Th2 profile including specific IgE, whereas GlpQ was weakly immunogenic. To elucidate the influence of adjuvants on the proteins’ polarization potential, we studied Montanide ISA 71 VG and Imject™Alum, which promote a Th1 and Th2 response, respectively. Alum strongly increased antibody production to the Th2-polarizing protein SplB, but did not affect the response to GlpQ. Montanide enhanced the antibody production to both S. aureus virulence factors. Montanide also augmented the inflammation in general, whereas Alum had little effect on the cellular immune response. The adjuvants did not override the polarization potential of the S. aureus proteins on the adaptive immune response.

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.

Notch 1 Is Involved in CD4+ T Cell Differentiation Into Th1 Subtype During Helicobacter pylori Infection

Helicobacter pylori infection induces CD4⁺ T differentiation cells into IFN-γ-producing Th1 cells. However, the details of mechanism underlying this process remain unclear. Notch signal pathway has been reported to regulate the differentiation of CD4⁺ T cells into Th1 subtype in many Th1-mediated inflammatory disorders but not yet in H. pylori infection. In the present study, the mRNA expression pattern of CD4⁺ T cells in H. pylori-infected patients differed from that of healthy control using Human Signal Transduction Pathway Finder RT2 Profiler PCR Array, and this alteration was associated with Notch signal pathway, as analyzed by Bioinformation. Quantitative real-time PCR showed that the mRNA expression of Notch1 and its target gene Hes-1 in CD4⁺ T cells of H. pylori-infected individuals increased compared with the healthy controls. In addition, the mRNA expression of Th1 master transcription factor T-bet and Th1 signature cytokine IFN-γ was both upregulated in H. pylori-infected individuals and positively correlated with Notch1 expression. The increased protein level of Notch1 and IFN-γ were also observed in H. pylori-infected individuals confirmed by flow cytometry and ELISA. In vitro, inhibition of Notch signaling decreased the mRNA expression of Notch1, Hes-1, T-bet, and IFN-γ, and reduced the protein levels of Notch1 and IFN-γ and the secretion of IFN-γ in CD4⁺ T cells stimulated by H. pylori. Collectively, this is the first evidence that Notch1 is upregulated and involved in the differentiation of Th1 cells during H. pylori infection, which will facilitate exploiting Notch1 as a therapeutic target for the control of H. pylori infection.

The Exopolysaccharide of Lactobacillus fermentum UCO-979C Is Partially Involved in Its Immunomodulatory Effect and Its Ability to Improve the Resistance against Helicobacter pylori Infection

Lactobacillus fermentum UCO-979C (Lf979C) beneficially modulates the cytokine response of gastric epithelial cells and macrophages after Helicobacter pylori infection in vitro. Nevertheless, no in vivo studies were performed with this strain to confirm its beneficial immunomodulatory effects. This work evaluated whether Lf979C improves protection against H. pylori infection in mice by modulating the innate immune response. In addition, we evaluated whether its exopolysaccharide (EPS) was involved in its beneficial effects. Lf979C significantly reduced TNF-α, IL-8, and MCP-1 and augmented IFN-γ and IL-10 in the gastric mucosa of H. pylori-infected mice. The differential cytokine profile induced by Lf979C in H. pylori-infected mice correlated with an improved reduction in the pathogen gastric colonization and protection against inflammatory damage. The purified EPS of Lf979C reduced IL-8 and enhanced IL-10 levels in the gastric mucosa of infected mice, while no effect was observed for IFN-γ. This work demonstrates for the first time the in vivo ability of Lf979C to increase resistance against H. pylori infection by modulating the gastric innate immune response. In addition, we advanced knowledge of the mechanisms involved in the beneficial effects of Lf979C by demonstrating that its EPS is partially responsible for its immunomodulatory effect.

Generating mucosal and systemic immune response following vaccination of vibrio cholerae adhesion molecule against shigella flexneri infection

Introduction

Previous studies have shown 37.8 kDa pili subunit protein of Vibrio cholerae and 49.8 kDa pili subunit protein of Shigella flexneri can act as an adhesion molecule to initiate infection. These molecules also have the ability to agglutinate blood. The present study assessed mucosal and systemic immunity following vaccination using 37.8 kDa V. cholerae and protection against S. flexneri.

Subjects and Methods

Haemagglutination test was performed after purification of V. cholerae protein, followed by an anti-haemagglutination test. The intestinal weight and colony count were used to validate the protective effect on balb/c mice which were divided into the naive group, Shigella-positive control group, Vibrio-positive control group, V. cholerae infected-Vibrio-vaccinated group and S. flexneri-infected-Vibrio-vaccinated group. Th17, Treg, interleukin (IL) IL-17A, β-defensin and secretory-immunoglobulin A (s-IgA) were also measured to determine the systemic and mucosal immunity after vaccination.

Results

The haemagglutination and anti-haemagglutination tests showed that the 37.8 kDa protein could inhibit 49.8 kDa of the S. flexneri pili subunit. Decreased intestinal weight and colony count of vaccinated group compared to naive group also support cross reaction findings. Vaccination also generates higher level of Th17, Treg, IL-17A, β-defensin and s-IgA significantly.

Conclusions

37.8 kDa subunit pili can act as a homologous vaccine candidate to prevent V. cholerae and S. flexneri infection.

Th17 Cells in Helicobacter pylori Infection: a Dichotomy of Help and Harm

Helicobacter pylori is a Gram-negative bacterium that infects the gastric epithelia of its human host. Everyone who is colonized with these pathogenic bacteria can develop gastric inflammation, termed gastritis. Additionally, a small proportion of colonized people develop more adverse outcomes, including gastric ulcer disease, gastric adenocarcinoma, or gastric mucosa-associated lymphoid tissue lymphoma. The development of these adverse outcomes is dependent on the establishment of a chronic inflammatory response. The development and control of this chronic inflammatory response are significantly impacted by CD4⁺ T helper cell activity. Noteworthy, T helper 17 (Th17) cells, a proinflammatory subset of CD4⁺ T cells, produce several proinflammatory cytokines that activate innate immune cell antimicrobial activity, drive a pathogenic immune response, regulate B cell responses, and participate in wound healing. Therefore, this review was written to take an intricate look at the involvement of Th17 cells and their affiliated cytokines (interleukin-17A [IL-17A], IL-17F, IL-21, IL-22, and IL-26) in regulating the immune response to H. pylori colonization and carcinogenesis.

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

It has been over 30 years since a link was established between H. pylori infection of the gastric mucosa and the development of chronic gastric diseases. Research in rodent models supported by data from human tissue demonstrated that the host immune response to H. pylori is limited by host regulatory T cells. Immunization has been shown to induce a potent Th1- and Th17-mediated immune response capable of eradicating or at least significantly reducing the bacterial load of H. pylori in the stomach in small animal models. These results have not translated well to humans. Clinical trials employing many of the strategies used in rodents for oral immunization including the use of a mucosal adjuvant such as Escherichia coli LT or delivery by attenuated enteric bacteria have failed to limit H. pylori infection and have highlighted the potential toxicity of exotoxin-based mucosal adjuvants. A recent study, however, utilizing a recombinant fusion protein of H. pylori urease and the subunit B of E. coli LT, was performed on over 4000 children. Efficacy of over 70% was demonstrated against naturally acquired infection compared to control volunteers one year post-immunization. Efficacy was reduced, but still above 50% at three years. This study provided new insight into the strategies for developing an improved vaccine for widespread use in countries with high infection rates and where gastric cancer (GC) remains one of the most common causes of death due to cancer.

Epitope-loaded nanoemulsion delivery system with ability of extending antigen release elicits potent Th1 response for intranasal vaccine against Helicobacter pylori

BACKGROUND

Helicobacter pylori (H. pylori) infection remains a global public health issue, especially in Asia. Due to the emergence of antibiotic-resistant strains and the complexity of H. pylori infection, conventional vaccination is the best way to control the disease. Our previous study found that the N-acetyl-neuroaminyllactose-binding hemagglutinin protein (HpaA) is an effective protective antigen for vaccination against H. pylori infection, and intranasal immunization with the immunodominant HpaA epitope peptide (HpaA 154-171, P22, MEGVLIPAGFIKVTILEP) in conjunction with a CpG adjuvant decreased bacterial colonization in H. pylori-infected mice. However, to confer more robust and effective protection against H. pylori infection, an optimized delivery system is needed to enhance the P22-specific memory T cell response.

RESULTS

In this study, an intranasal nanoemulsion (NE) delivery system offering high vaccine efficacy without obvious cytotoxicity was designed and produced. We found that this highly stable system significantly prolonged the nasal residence time and enhanced the cellular uptake of the epitope peptide, which powerfully boosted the specific Th1 responses of the NE-P22 vaccine, thus reducing bacterial colonization without CpG. Furthermore, the protection efficacy was further enhanced by combining the NE-P22 vaccine with CpG.

CONCLUSION

This epitope-loaded nanoemulsion delivery system was shown to extend antigen release and elicit potent Th1 response, it is an applicable delivery system for intranasal vaccine against H. pylori.

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.

Immunodominant antigens that induce Th1 and Th17 responses protect mice against Helicobacter pylori infection

Helicobacter pylori has infected more than half of the world's population, causing gastritis, gastric ulcers, gastric mucosa-associated lymphoid tissue lymphoma and gastric cancer. The oral recombinant Helicobacter pylori vaccine currently used has made great progress in addressing this problem, however, its efficacy and longevity still need to be improved. Th1 and Th17 cells play essential roles in local protection against Helicobacter pylori in the stomach mucosa. Additionally, protective immunodominant antigens are the preferred for a vaccine. In this work, Helicobacter pylori whole cell lysate was separated into 30 groups based on molecular weight by molecular sieve chromatography. The group best promoting CD4 T cells proliferation was selected and evaluated by immunization. The detail proteins were then analyzed by LC-MS/MS and expressed in Escherichia coli. Eleven proteins were selected and the dominant ones were demonstrated. As a result, three protective immunodominant antigens, inosine 5'-monophosphate dehydrogenase, type II citrate synthase, and urease subunit beta, were selected from Helicobacter pylori whole cell. Two of them (inosine 5'-monophosphate dehydrogenase and type II citrate synthase) were newly identified, and one (urease subunit beta) was confirmed as previously reported. The mixture of the three antigens showed satisfactory protective efficiency, with significant lower H. pylori colonization level (P < 0.001) and stronger Th1 (P < 0.001) and Th17 (P < 0.001) responses than PBS control group. Thus, inosine 5'-monophosphate dehydrogenase, type II citrate synthase, and urease subunit beta are three protective antigens inducing dominant Th1 and Th17 responses to defend against Helicobacter 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.

Immunoprevention of KRAS-driven lung adenocarcinoma by a multipeptide vaccine

Lung cancer remains the leading cause of cancer death worldwide. Mutations in KRAS are detected in up to 30% of lung cancer cases. No effective therapies specifically targeting mutant KRAS have been developed. Vaccination against KRAS mutants is one of the venues of active exploration. The present study evaluated both immunogenicity and antitumor efficacy of a newly formulated multipeptide vaccine targeting multiple epitopes of the KRAS molecule. The formulated vaccine contained top four peptides, which elicited the strongest immunologic response and showed 100% sequence homology between human and mouse. The multipeptide KRAS vaccine was tested in an inducible CCSP-TetO-KRAS^G12D mouse model, where the vaccine was administered prior to activating the mutant KRAS protein. The KRAS peptide vaccine exhibited striking efficacy, reducing tumor number and tumor burden by >80% when compared with adjuvant alone. Splenocytes collected from vaccinated animals showed a robust immunologic response to the immunizing peptides. Furthermore, in vitro stimulation of these splenocytes by the vaccinated peptides resulted in the secretion of cytokines indicative of Th1 responses but with minimal secretion of Th2-related cytokines. The multipeptide KRAS vaccine was immunogenic and efficacious in the primary prevention of KRAS-induced lung cancer, indicating that the approach potentially can be used to prevent other KRAS-driven cancers, either alone or in combination with other modalities.

The influence of adjuvant on UreB protection against Helicobacter pylori through the diversity of CD4+ T-cell epitope repertoire

Adjuvants are widely used to enhance the effects of vaccines against pathogen infections. Interestingly, different adjuvants and vaccination routes usually induce dissimilar immune responses, and can even have completely opposite effects. The mechanism remains unclear. In this study, urease B subunit (UreB), an antigen of Helicobacter pylori (H. pylori) that can induce protective immune responses, was used as a model to vaccinate mice. We investigated the effects of different adjuvants and routes on consequent T cell epitope-specific targeting and protection against H. pylori infection. Comparison of the protective effects of UreB, administered either subcutaneously (sc) or intranasally (in), with the adjuvants AddaVax (sc), Complete Freund’s adjuvant (CFA; sc), or CpG oligonucleotide (CpG; sc or in), indicated that only CFA (sc) and CpG (in) were protective. Protective vaccines induced T cells targeting epitopes that differed from that targeted by control vaccination. Subsequent peptide vaccination demonstrated that only two of the identified epitopes were protective: UreB_373–385 and UreB_317–329. Overall, we found that both adjuvant and vaccination route affected the T cell response repertoire to antigen epitopes. The data obtained in this study contribute to improved characterization of the relationship between adjuvants, routes of vaccination, and epitope-specific T cell response repertoires.

Inflammation, immunity, and vaccines for Helicobacter pylori infection

The tight control of the innate and adaptive immune responses in the stomach mucosa during chronic Helicobacter pylori infection is of prime importance for the bacteria to persist and for the host to prevent inflammation-driven diseases. This review summarizes recent data on the roles of innate and adaptive immune responses during H. pylori/host interactions. In addition, the latest preclinical developments of H. pylori vaccines are discussed with a special focus on the clinical trial reported by Zeng et al., who provided evidence that oral vaccination significantly reduces the acquisition of natural H. pylori infection in children.