Effects of a Th1- versus a Th2-biased immune response in protection against Helicobacter pylori challenge in mice

High galectin expression in Helicobacter pylori-infected gastric mucosa in childhood

BACKGROUND

Mild Th1 and Th17 immune responses in childhood against Helicobacter pylori are presumed to be responsible for H. pylori colonization and mucosal atrophy reduction. However, the mechanism remains unclear. In this study, we aimed to investigate the childhood-specific immune responses observed after H. pylori infection by analyzing galectin expression in the gastric mucosa. We focused on galectin-1 (Gal-1) and galectin-9 (Gal-9), which function to suppress Th1 and Th17 immune responses.

METHODS

We analyzed changes in the expression of Gal-1 and Gal-9 in the gastric mucosa of pediatric patients with H. pylori infection. Ten pediatric patients with and ten patients without H. pylori infection who underwent biopsy to assess the cause of chronic abdominal symptoms using esophagogastroduodenoscopy were evaluated. Gal-1 and Gal-9 expression in the biopsy tissues of the gastric antrum and corpus was analyzed by immunohistochemical staining.

RESULTS

Gal-1 expression was significantly increased in the stromal cells of the corpus owing to H. pylori infection. No alterations in Gal-1 expression due to H. pylori infection were observed in the antral tissue. Helicobacter pylori infection considerably increased Gal-9 expression in all tissues. According to previous reports, the increased expression of Gal-9 associated with H. pylori infection is not observed in adults. Therefore, the increased expression of Gal-9 associated with H. pylori infection is specific to pediatric patients.

CONCLUSION

The increased expression of Gal-1 and Gal-9 may suppress Th1 and Th17 immune responses against H. pylori infection during childhood, promote H. pylori colonization, and reduce inflammation in the gastric mucosa of pediatric patients.

The Expression Kinetics and Immunogenicity of Lipid Nanoparticles Delivering Plasmid DNA and mRNA in Mice

In recent years, lipid nanoparticles (LNPs) have emerged as a revolutionary technology for vaccine delivery. LNPs serve as an integral component of mRNA vaccines by protecting and transporting the mRNA payload into host cells. Despite their prominence in mRNA vaccines, there remains a notable gap in our understanding of the potential application of LNPs for the delivery of DNA vaccines. In this study, we sought to investigate the suitability of leading LNP formulations for the delivery of plasmid DNA (pDNA). In addition, we aimed to explore key differences in the properties of popular LNP formulations when delivering either mRNA or DNA. To address these questions, we compared three leading LNP formulations encapsulating mRNA- or pDNA-encoding firefly luciferase based on potency, expression kinetics, biodistribution, and immunogenicity. Following intramuscular injection in mice, we determined that RNA-LNPs formulated with either SM-102 or ALC-0315 lipids were the most potent (all p-values < 0.01) and immunogenic (all p-values < 0.05), while DNA-LNPs formulated with SM-102 or ALC-0315 demonstrated the longest duration of signal. Additionally, all LNP formulations were found to induce expression in the liver that was proportional to the signal at the injection site (SM102: r = 0.8787, p < 0.0001; ALC0315: r = 0.9012, p < 0.0001; KC2: r = 0.9343, p < 0.0001). Overall, this study provides important insights into the differences between leading LNP formulations and their applicability to DNA- and RNA-based vaccinations.

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.

A Genetic and Immunohistochemical Analysis of Helicobacter pylori Phenotypes and p27 Expression in Adenocarcinoma Patients in Jordan

Stomach (gastric) cancer is one of the most prevalent and deadly cancers worldwide and most gastric cancers are adenocarcinomas. Based on prior research, there is an association between Helicobacter pylori (H. pylori) infection together with the frequency of duodenal ulcer, distal gastric adenocarcinoma, mucosa-associated lymphoid tissue (MALT) lymphoma, and antral gastritis. Helicobacter pylori virulence and toxicity factors have been identified before that significantly influence the clinical outcomes of H. pylori infection and gastric adenocarcinoma. However, it remains unclear exactly how different strains of H. pylori affect gastric adenocarcinoma. Current research suggests this involves tumor suppressor genes, like p27 but also H. pylori toxic virulence proteins. Therefore, we quantified known H. pylori genotypes within adenocarcinoma patients to establish the prevalence of known toxins that include cytotoxin-associated gene A (cagA) as well as vacuolating cytotoxin A (vacA) within patients of variable adenocarcinoma diagnosis. This analysis used gastrectomy samples validated for DNA viability. The incidence of H. pylori in adenocarcinoma patients in Jordan was established to be 54.5% positive (ureA gene positive) with cagA genotype occurrence at 57.1%, but also in this population study vacA gene ratios found to be 24.7%:22.1%:14.3%:14.3%. (vacAs1:vacAs2:vacAm1:vacAm2). Using immunohistochemistry (IHC), we confirmed with statistical significance that p27 was dysregulated and suppressed, within nearly all H. pylori vacA genotypes. In addition, within 24.6% of H. pylori samples analyzed was a different bacterial genotype, and curiously that p27 protein expression was retained in 12% of tested adenocarcinoma H. pylori samples. This is suggestive that p27 could be used as a prognostic indicator but also that an unknown genotype could be contributing to the regulatory effects of p27 protein within this bacterial and cellular environment that may include other virulence factors and unknown immune system regulatory changes.

Molecular mechanisms of the virulence and efficacy of a highly virulent Vibrio anguillarum strain and its formalin-inactivated vaccine in rainbow trout

In this study, we have isolated four strains of Vibrio anguillarum, revealing that they share the same serotype of O1, biochemical characteristics and virulence factor genes. However, there were differences in haemolytic activity among the bacterial strains; a strain with lower pathogenicity showed γ-haemolytic activity, whereas other virulent strains showed α-haemolytic activity on blood agar and higher empA gene expression in RTG-2 cell line. The most virulent strain was V. anguillarum RTBHR from diseased masu salmon (Oncorhynchus masou), which resulted in mortality of 100% and 93.3% when injected intraperitoneally at concentrations of 9 × 10⁵ and 6.3 × 10⁵ colony-forming units/fish in rainbow trout (Oncorhynchus mykiss) and Coho salmon (Oncorhynchus kisutch), respectively. A formalin-inactivated vaccine of V. anguillarum RTBHR induced a protective and specific immunity in rainbow trout as the vaccinated fish exhibited low cumulative mortality in a challenge test and a high specific antibody response in enzyme-linked immunosorbent assay at 8 weeks post-vaccination. The produced antibody was bound to bacterial proteins of 30-37 kDa in size. This adaptive immune response was detected as early as day 1, with quantitative polymerase chain reaction analysis revealing the upregulated expression of genes encoding for TCRα, T-bet, mIgM and sIgM in rainbow trout. This suggested that the vaccine induced T (probably a more dominant Th1 response) and B cell responses. In conclusion, the vaccine successfully protected fish from V. anguillarum infection by eliciting cellular and humoral immune responses.

A comprehensive evaluation of an animal model for Helicobacter pylori-associated stomach cancer: Fact and controversy

Even though Helicobacter pylori infection was the most causative factor of gastric cancer, numerous in vivo studies failed to induce gastric cancer using H. pylori infection only. The utilization of established animal studies in cancer research is crucial as they aim to investigate the coincidental association between suspected oncogenes and pathogenesis as well as generate models for the development and testing of potential treatments. The methods to establish gastric cancer using infected animal models remain limited, diverse in methods, and showed different results. This study investigates the differences in animal models, which highlight different pathological results in gaster by literature research. Electronic databases searched were performed in PubMed, Science Direct, and Cochrane, without a period filter. A total of 135 articles were used in this study after a full-text assessment was conducted. The most frequent animal models used for gastric cancer were Mice, while Mongolian gerbils and Transgenic mice were the most susceptible model for gastric cancer associated with H. pylori infection. Additionally, transgenic mice showed that the susceptibility to gastric cancer progression was due to genetic and epigenetic factors. These studies showed that in Mongolian gerbil models, H. pylori could function as a single agent to trigger stomach cancer. However, most gastric cancer susceptibilities were not solely relying on H. pylori infection, and numerous factors are involved in cancer progression. Further study using Mongolian gerbils and Transgenic mice is crucial to conduct and establish the best models for gastric cancer associated H. pylori.

Cellular and humoral immune responsiveness to inactivated Leptospira interrogans in dogs vaccinated with a tetravalent Leptospira vaccine

Vaccination is commonly used to protect dogs against leptospirosis, however, memory immune responses induced by canine Leptospira vaccines have not been studied. In the present study, antibody and T cell mediated responses were assessed in dogs before and 2 weeks after annual revaccination with a commercial tetravalent Leptospira vaccine containing serogroups Canicola and Australis. Vaccination significantly increased average log₂ IgG titers from 6.50 to 8.41 in year 1, from 5.99 to 7.32 in year 2, from 5.32 to 8.32 in year 3 and from 5.32 to 7.82 in year 4. The CXCL-10 levels, induced by in vitro stimulation of PBMC with Canicola and Australis, respectively, significantly increased from 1039.05 pg/ml and 1037.38 pg/ml before vaccination to 2547.73 pg/ml and 2730.38 pg/ml after vaccination. IFN-γ levels increased from 85.60 pg/ml and 178.13 pg/ml before vaccination to 538.62 pg/ml and 210.97 pg/ml after vaccination. The percentage of proliferating CD4⁺ T cells in response to respective Leptospira strains significantly increased from 1.43 % and 1.25 % before vaccination to 24.11 % and 14.64 % after vaccination. Similar responses were also found in the CD8⁺ T cell subset. Vaccination also significantly enhanced the percentages of central memory CD4⁺ T cells from 12 % to 26.97 % and 27.65 %, central memory CD8⁺ T cells from 3 % to 9.47 % and 7.55 %, and effector CD8⁺ T cells from 3 % to 7.6 % and 6.42 %, as defined by the expression of CD45RA and CD62L, following stimulation with Canicola and Australis, respectively. Lastly, enhanced expression of the activation marker CD25 on T cells after vaccination was found. Together, our results show that next to IgG responses, also T cell responses are induced in dogs upon annual revaccination with a tetravalent Leptospira vaccine, potentially contributing to protection.

Disruption of sncRNA Improves the Protective Efficacy of Outer Membrane Vesicles against Helicobacter pylori Infection in a Mouse Model

The outer membrane vesicles (OMVs) secreted by Helicobacter pylori contain various bacterial components, such as proteins, phospholipids, toxins, and nucleic acids, including small noncoding RNA (sncRNA), which have regulatory functions in cell envelope structure, metabolism, bacterial communication, biofilm formation, and virulence. We previously showed that knocking out sncRNAs sR-989262 and sR-2509025 at the cellular level increased interleukin 8 (IL-8) levels in mice exposed to OMVs. In this study, we show that immunization with ΔsR-989262 and ΔsR-2509025 OMVs intragastrically significantly increased immunoglobulin G (IgG) and secreted IgA levels in mice compared to wild-type OMVs and without weight changes, which indicated that sncRNA-deficient OMVs are relatively safe to immunize mice. The detection of IgG subtypes IgG1 and IgG2c showed that the sncRNA-deficient OMVs primarily stimulate the T helper 2 (Th2)-mediated immune response. Moreover, levels of the cytokines IL-4, IL-13, gamma interferon (IFN-γ), IL-12 (p40), IL-8, and IL-17 indicate that ΔsR-989262 and ΔsR-2509025 OMVs trigger the Th2-type immune response but primarily trigger a Th1-mediated and Th17-mediated immune response. These findings show that OMV-encapsulated sncRNA plays an important role in regulating the immune response in hosts infected by H. pylori at the animal level. Moreover, they show that knocking out of sR-989262 and sR-2509025 improves the immunogenicity and protective efficacy of OMVs, and this may be beneficial to the design of OMV-based H. pylori vaccines.

Durability of ChAdOx1 nCoV-19 vaccination in people living with HIV

Duration of protection from SARS-CoV-2 infection in people living with HIV (PWH) following vaccination is unclear. In a substudy of the phase II/III the COV002 trial (NCT04400838), 54 HIV+ male participants on antiretroviral therapy (undetectable viral loads, CD4+ T cells > 350 cells/μL) received 2 doses of ChAdOx1 nCoV-19 (AZD1222) 4-6 weeks apart and were followed for 6 months. Responses to vaccination were determined by serology (IgG ELISA and Meso Scale Discovery [MSD]), neutralization, ACE-2 inhibition, IFN-γ ELISpot, activation-induced marker (AIM) assay and T cell proliferation. We show that, 6 months after vaccination, the majority of measurable immune responses were greater than prevaccination baseline but with evidence of a decline in both humoral and cell-mediated immunity. There was, however, no significant difference compared with a cohort of HIV-uninfected individuals vaccinated with the same regimen. Responses to the variants of concern were detectable, although they were lower than WT. Preexisting cross-reactive T cell responses to SARS-CoV-2 spike were associated with greater postvaccine immunity and correlated with prior exposure to beta coronaviruses. These data support the ongoing policy to vaccinate PWH against SARS-CoV-2, and they underpin the need for long-term monitoring of responses after vaccination.

Gastric eosinophils are detrimental for Helicobacter pylori vaccine efficacy

Helicobacter pylori (Hp) colonizes the human gastric mucosa with a high worldwide prevalence. Currently, Hp can be eradicated by the use of antibiotics. Due to the increase of antibiotic resistance, new therapeutic strategies need to be devised: one such approach being prophylactic vaccination. Pre-clinical and clinical data showed that a urease-based vaccine is efficient in decreasing Hp infection through the mobilization of T helper (Th)-dependent immune effectors, including eosinophils. Preliminary data have shown that upon vaccination and subsequent Hp infection, eosinophils accumulate in the gastric mucosa, suggesting a possible implication of this granulocyte subset in the vaccine-induced reduction of Hp infection. In our study, we confirm that activated eosinophils, expressing CD63, CD40, MHCII and PD-L1 at their cell surface, infiltrate the gastric mucosa during vaccine-induced reduction of Hp infection. Strikingly, we provide evidence that bone marrow derived eosinophils efficiently kill Hp in vitro, suggesting that eosinophils may participate to the vaccine-induced reduction of Hp infection. However, conversely to our expectations, the absence of eosinophils does not decrease the efficacy of this Hp vaccine in vivo. Indeed, vaccinated mice that have been genetically ablated of the eosinophil lineage or that have received anti-Sialic acid-binding immunoglobulin-like lectin F eosinophil-depleting antibodies, display a lower Hp colonization when compared to their eosinophil sufficient counterparts. Although the vaccine induces similar urease-specific humoral and Th responses in both eosinophil sufficient and deficient mice, a decreased production of anti-inflammatory cytokines, such as IL-10, TGFβ, and calgranulin B, was specifically observed in eosinophil depleted mice. Taken together, our results suggest that gastric eosinophils maintain an anti-inflammatory environment, thus sustaining chronic Hp infection. Because eosinophils are one of the main immune effectors mobilized by Th2 responses, our study strongly suggests that the formulation of an Hp vaccine needs to include an adjuvant that preferentially primes Hp-specific Th1/Th17 responses.

Outer Membrane Vesicles of Helicobacter pylori 7.13 as Adjuvants Promote Protective Efficacy Against Helicobacter pylori Infection

Helicobacter pylori(H. pylori), a gram-negative bacterium in the human stomach with global prevalence, is relevant to chronic gastrointestinal diseases. Due to its increasing drug resistance and the low protective efficacy of some anti-H. pylori vaccines, it is necessary to find a suitable adjuvant to improve antigen efficiency. In our previous study, we determined that outer membrane vesicles (OMVs), a multicomponent secretion generated by gram-negative bacteria, of H. pylori were safe and could induce long-term and robust immune responses against H. pylori in mice. In this study, we employed two common vaccines, outer membrane proteins (OMPs) and whole cell vaccine (WCV) to assess the adjuvanticity of OMVs in mice. A standard adjuvant, cholera toxin (CT), was used as a control. Purified H. pylori OMVs used as adjuvants generated lasting anti-H. pylori resistance for 12 weeks. Additionally, both systematic and gastric mucosal immunity, as well as humoral immunity, of mice immunized with vaccine and OMVs combinations were significantly enhanced. Moreover, OMVs efficiently promoted Th1 immune response, but the response was skewed toward Th2 and Th17 immunity when compared with that induced by the CT adjuvant. Most importantly, OMVs as adjuvants enhanced the eradication of H. pylori. Thus, OMVs have potential applications as adjuvants in the development of a new generation of vaccines to treat H. pylori infection.

Type I interferon shapes the quantity and quality of the anti-Zika virus antibody response

Objectives

Zika virus (ZIKV) is a mosquito-borne flavivirus that re-emerged in 2015. The association between ZIKV and neurological complications initiated the development of relevant animal models to understand the mechanisms underlying ZIKV-induced pathologies. Transient inhibition of the type I interferon (IFN) pathway through the use of an IFNAR1-blocking antibody, MAR1-5A3, could efficiently permit active virus replication in immunocompetent animals. Type I IFN signalling is involved in the regulation of humoral responses, and thus, it is crucial to investigate the potential effects of type I IFN blockade towards B-cell responses.

Methods

In this study, comparative analysis was conducted using serum samples collected from ZIKV-infected wild-type (WT) animals either administered with or without MAR1-5A3.

Results

Serological assays revealed a more robust ZIKV-specific IgG response and subtype switching upon inhibition of type I IFN due to the abundance of antigen availability. This observation was corroborated by an increase in germinal centres, plasma cells and germinal centre B cells. Interestingly, although both groups of animals recognised different B-cell linear epitopes in the E and NS1 regions, there was no difference in neutralising capacity. Further characterisation of these epitopes in the E protein revealed a detrimental role of antibodies that were generated in the absence of type I IFN.

Conclusion

This study highlights the role of type I IFN in shaping the anti-ZIKV antibody response to generate beneficial antibodies and will help guide development of better vaccine candidates triggering efficient neutralising antibodies and avoiding detrimental ones.

Construction, Cloning, and Expression of CagA Recombinant Protein of Helicobacter pylori

BACKGROUND

This study aimed to assess construction and expression of CagA recombinant protein of Helicobacter pylori (H. pylori) in Escherichia coli (E. coli) BL21.

METHODS

Bioinformatics was used in designing the desired gene by Gene Runner. Next, the construct was subcloned to pET21b vector and this process was confirmed by Polymerase Chain Reaction (PCR), enzyme digestion and sequencing techniques. Then, it was cloned in the Escherichia coli BL21 as an expression host. Expression of protein was verified using sodium dodecyl sulfate- polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting technique. For purification of the protein, the Ni-NTA column was used. Protein concentration was determined by the Bicinchoninic Acid Protein Assay Kit (Parstoos). Finally, Western blotting was performed using CagA antibodies and normal human serum for determining immunogenicity feature with human antiserum.

RESULTS

According to the results of the present study, CagA construct was cloned into the pET21b vector and after confirmation and cloning in host expression, recombinant protein with the size of 38 kDa was successfully expressed and purified. The recombinant CagA protein showed immunogenicity characteristics with human antiserum.

CONCLUSION

In conclusion, only 5'-end of recombinant protein CagA with high immunogenicity effects was successfully constructed, cloned and expressed. Also, CagA recombinant protein showed good immunogenicity activity with human antiserum.

Immunoinformatics approaches to explore Helicobacter Pylori proteome (Virulence Factors) to design B and T cell multi-epitope subunit vaccine

Helicobacter Pylori is a known causal agent of gastric malignancies and peptic ulcers. The extremophile nature of this bacterium is protecting it from designing a potent drug against it. Therefore, the use of computational approaches to design antigenic, stable and safe vaccine against this pathogen could help to control the infections associated with it. Therefore, in this study, we used multiple immunoinformatics approaches along with other computational approaches to design a multi-epitopes subunit vaccine against H. Pylori. A total of 7 CTL and 12 HTL antigenic epitopes based on c-terminal cleavage and MHC binding scores were predicted from the four selected proteins (CagA, OipA, GroEL and cagA). The predicted epitopes were joined by AYY and GPGPG linkers. Β-defensins adjuvant was added to the N-terminus of the vaccine. For validation, immunogenicity, allergenicity and physiochemical analysis were conducted. The designed vaccine is likely antigenic in nature and produced robust and substantial interactions with Toll-like receptors (TLR-2, 4, 5, and 9). The vaccine developed was also subjected to an in silico cloning and immune response prediction model, which verified its efficiency of expression and the immune system provoking response. These analyses indicate that the suggested vaccine may produce particular immune responses against H. pylori, but laboratory validation is needed to verify the safety and immunogenicity status of the suggested vaccine design.

The important role played by chemokines influence the clinical outcome of Helicobacter pylori infection

The extended infection with Helicobacter pylori (H. pylori), one of the most frequent infectious agents in humans, may cause gastritis, peptic ulcers, gastric mucosa-associated lymphoid tissue (MALT) lymphoma, and gastric cancer. During H. pylori infection, different kinds of inflammatory cells such as dendritic cells, macrophages, neutrophils, mast cells, eosinophils, T cells and B cells are accumulated into the stomach. The interactions between chemokines and their respective receptors recruit particular types of the leukocytes that ultimately determine the nature of immune response and therefore, have a main influence on the consequence of infection. The suitable production of chemokines especially in the early stages of H. pylori infection shapes appropriate immune responses that contribute to the H. pylori elimination. The unbalanced expression of the chemokines can contribute in the induction of inappropriate responses that result in the tissue damage or malignancy. Thus, chemokines and their receptors may be promising potential targets for designing the therapeutic strategies against various types H. pylori-related gastrointestinal disorders. In this review, a comprehensive explanation regarding the roles played by chemokines in H. pylori-mediated peptic ulcer, gastritis and gastric malignancies was provided while presenting the potential utilization of these chemoattractants as therapeutic elements.

Activation of CD3+ T cells by Helicobacter pylori DNA vaccines in potential immunotherapy of gastric carcinoma

Most of gastric carcinoma (GC) is attributed to infection by Helicobacter pylori (H. pylori) but there is increasing evidence that the positive H. pylori status correlates with better prognosis in GC. The H. pylori-induced cellular immune response may suppress cancer and in this work, recombinant pcDNA3 plasmids encoding various fragments of H. pylori virulence genes of cagA, vacA and babA are constructed and combined into groups to immunize BALB/c mice. The activated splenic CD3⁺ T cells are purified and the anticancer effects are investigated in vitro and in vivo. The H. pylori DNA vaccines induce a shift in the response from Th1 to Th2 that mimicks the immune status in patients of GC with chronic H. pylori infection. The stimulated CD3⁺ T cells inhibit the growth of human GC cells in vitro and adoptive transfusions of the CD3⁺ T cells suppress the growth of GC xenograft in vivo. The effects may be caused by the larger ratios of infiltrated CD8⁺/CD4⁺ T cells, reduced infiltration of regulatory FOXP3⁺ T cells, and enhanced apoptosis induced by upregulation of Caspase-9/Caspase-3 and downregulation of Survivin. Our results reveal the potential immunotherapeutic value of H. pylori vaccine-activated CD3⁺ T cells in those with advanced GC.

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.

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.

Study of serum bactericidal and splenic activity of Total-OMP- CagA combination from Brucella abortus and Helicobacter pylori in BALB/c mouse model

BACKGROUND

Brucella is a Gram-negative and facultative intracellular organism that causes brucellosis, a common zoonotic disease. Over 500,000 people are annually affected by brucellosis. Brucella is highly infectious through inhalation route; for this reason it is used for biological warfare aims. This study aimed to study the serum bactericidal and splenic activity of Total-OMP-r CagA immunogens from Brucella abortus and Helicobacter pylori in a BALB/c mouse model.

METHODS

Immunization of BALB/c mice was performed with immunogenic proteins three times subcutaneously (S.C.) at 14-day intervals. The protective effects of two component vaccines with CpG adjuvant were evaluated after mice were challenged with H. pylori ss1 and Brucella abortus strain 544. The specific IgG1 and IgG2a antibodies in sera were assessed using ELISA test. For measuring the antigen-specific IL-4, IL-12 and IFN-γ responses in sera of immunized mice after challenge, RT-PCR technique was applied. Twenty days after the challenge, mice were killed then gastric, splenic and serum samples were assessed and bacterial colony count was measured based on the pour plate count agar.

RESULTS

The results indicated that rCagA + OMP decreased bacterial colonization in these tissues, and significant difference was observed between test and control groups (p value˂0.001).

CONCLUSION

Our results showed that the combination vaccine was effective against an oral exposure and the bacterial burden in the spleen, serum and gastric tissues were reduced in mice immunized with the Total- OMP-CagA.

Validation of immunomodulatory effects of lipopolysaccharide through expression profiling of Th1 and Th2 biased genes in Newcastle disease virus vaccinated indigenous chicken

Background and Aim

Newcastle disease (ND) is considered one of the most important poultry diseases with chicken morbidity and mortality rates up to 100%. Current vaccination programs allow the use of live attenuated vaccines in the field to protect against the disease, which alone is inefficient and requires repeat booster doses. Toll-like receptor agonists (e.g., lipopolysaccharide [LPS]) as adjuvants are the ones, most extensively studied and have shown to be very promising in delivering a robust balanced immune response. In the present study, we have evaluated the potential of LPS to elicit a strong immune response with respect to the elicitation of both Th1 (cell-mediated) and Th2 (humoral) immune arms.

Materials and Methods

A total of 72 apparently healthy 1-day-old indigenous unvaccinated chicks were randomly divided into six experimental Groups A to F (n=12). At 8-week of age chicks in Group A, C, and E were vaccinated with live attenuated La Sota strain ND vaccine along with LPS, bovine serum albumin, and normal saline solution, respectively, and those in Group B, D, and E were kept separately without vaccination. Sampling was done on days 0, 1, 3, 7, 14, 21, 35, and 60 after vaccination. After vaccination and respective adjuvant application, Th1 and Th2 cytokine expression were measured in mRNA of both blood and tissue samples.

Results

The results were validated by, hemagglutination inhibition and enzyme-linked immunosorbent assay tests, to check for the humoral as well as cell-mediated immune response in blood serum levels. The results showed an increase in mRNA expression of the Th1 biased cytokines in Group A (LPS+NDV) as compared to the control groups. Similar mRNA expression pattern was seen in blood as well as tissue samples. Validation of results also indicates an increase in Cell-mediated Immunity as well as a humoral immune response in Group A (LPS+NDV).

Conclusion

The results of the study provided enough evidence to consider LPS as a potential vaccine adjuvants candidate against ND in chicken.

T cell subsets play an important role in the determination of the clinical outcome of Helicobacter pylori infection

Helicobacter pylori (H. pylori) is one of the most prevalent human pathogen and a persistent infection with this bacterium causes common pathologies, such as gastritis or peptic ulcers, and also less common but more serious pathologies, such as gastric cancer or gastric mucosa-associated lymphoid tissue (MALT) lymphoma. The clinical outcome of gastrointestinal infection sustained by H. pylori is determined by the reciprocal interactions between virulence factors of the bacterium and host factors, including immune response genes. Although H. pylori induces a strong immune response, the bacterium is not eliminated. The eradication failure could be attributed to the bacterial capability to regulate helper T (Th) cell-related responses. H. pylori specific CD4⁺ T cells play a fundamental role in regulating host immunity and immunopathologic events. It has been documented that Th1, Th2, Th9, Th17, Th22 and T regulatory (Treg) cells, separately or in coordination with each other, can affect the outcome of the infection sustained by of H. pylori. Some studies indicated that both Th1 and Th17 cells may be protective or pathogenic, whereas Treg and Th2 cells perform anti-inflammatory impacts during H. pylori infection. This review gathers recent information regarding the association of the CD4⁺ T cells-mediated immunological responses and the clinical consequence of H. pylori infection.

Host Determinants of Expression of the Helicobacter pylori BabA Adhesin

Expression of the Helicobacter pylori blood group antigen binding adhesin A (BabA) is more common in strains isolated from patients with peptic ulcer disease or gastric cancer, rather than asymptomatic colonization. Here we used mouse models to examine host determinants that affect H. pylori BabA expression. BabA expression was lost by phase variation as frequently in WT mice as in RAG2−/− mice that do not have functional B or T cells, and in MyD88−/−, TLR2−/− and TLR4−/− mice that are defective in toll like receptor signaling. The presence of other bacteria had no effect on BabA expression as shown by infection of germ free mice. Moreover, loss of BabA expression was not dependent on Le^b expression or the capacity of BabA to bind Le^b. Surprisingly, gender was the host determinant most associated with loss of BabA expression, which was maintained to a greater extent in male mice and was associated with greater bacterial load. These results suggest the possibility that loss of BabA expression is not driven by adaptive immunity or toll-like receptor signaling, and that BabA may have other, unrecognized functions in addition to serving as an adhesin that binds Le^b.

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.

Immunization with Heat Shock Protein A and γ-Glutamyl Transpeptidase Induces Reduction on the Helicobacter pylori Colonization in Mice

The human gastric pathogen Helicobacter pylori (H. pylori) is a successful colonizer of the stomach. H. pylori infection strongly correlates with the development and progression of chronic gastritis, peptic ulcer disease, and gastric malignances. Vaccination is a promising strategy for preventing H. pylori infection. In this study, we evaluated the candidate antigens heat shock protein A (HspA) and H. pylori γ-glutamyl transpeptidase (GGT) for their effectiveness in development of subunit vaccines against H. pylori infection. rHspA, rGGT, and rHspA-GGT, a fusion protein based on HspA and GGT, were constructed and separately expressed in Escherichia coli and purified. Mice were then immunized intranasally with these proteins, with or without adjuvant. Immunized mice exhibited reduced bacterial colonization in stomach. The highest reduction in bacterial colonization was seen in mice immunized with the fusion protein rHspA-GGT when paired with the mucosal adjuvant LTB. Protection against H. pylori colonization was mediated by a strong systemic and localized humoral immune response, as well as a balanced Th1/Th2 cytokine response. In addition, immunofluorescence microscopy confirmed that rHspA-GGT specific rabbit antibodies were able to directly bind H. pylori in vitro. These results suggest antibodies are essential to the protective immunity associated with rHspA-GGT immunization. In summary, our results suggest HspA and GGT are promising vaccine candidates for protection against H. pylori infection.

Cytokines, cytokine gene polymorphisms and Helicobacter pylori infection: Friend or foe?

Helicobacter pylori (H. pylori) is a flagellated, spiral-shaped, microaerophilic Gram-negative bacillus that colonises the gastric mucosa of more than 50% of the human population. Infection is a risk factor for gastritis, ulcer disease and stomach cancer. Immunity against H. pylori is mainly related to Th1/Th17 skewing, and the activation of regulatory T cells is the main strategy used to limit inflammatory responses, which can result in the pathogen persistence and can lead to chronic gastrointestinal diseases, including cancer. Furthermore, host genetic factors that affect cytokines may determine differences in the susceptibility to many diseases. In this review, we present the cytokine profiles and the main cytokine gene polymorphisms associated with resistance/susceptibility to H. pylori and discuss how such polymorphisms may influence infection/disease outcomes.

Laser-engineered dissolving microneedle arrays for protein delivery: potential for enhanced intradermal vaccination

OBJECTIVES

We aimed to highlight the utility of novel dissolving microneedle (MN)-based delivery systems for enhanced transdermal protein delivery. Vaccination remains the most accepted and effective approach in offering protection from infectious diseases. In recent years, much interest has focused on the possibility of using minimally invasive MN technologies to replace conventional hypodermic vaccine injections.

METHODS

The focus of this study was exploitation of dissolving MN array devices fabricated from 20% w/w poly(methyl vinyl ether/maleic acid) using a micromoulding technique, for the facilitated delivery of a model antigen, ovalbumin (OVA).

KEY FINDINGS

A series of in-vitro and in-vivo experiments were designed to demonstrate that MN arrays loaded with OVA penetrated the stratum corneum and delivered their payload systemically. The latter was evidenced by the activation of both humoral and cellular inflammatory responses in mice, indicated by the production of immunoglobulins (IgG, IgG1, IgG2a) and inflammatory cytokines, specifically interferon-gamma and interleukin-4. Importantly, the structural integrity of the OVA following incorporation into the MN arrays was maintained.

CONCLUSION

While enhanced manufacturing strategies are required to improve delivery efficiency and reduce waste, dissolving MN are a promising candidate for 'reduced-risk' vaccination and protein delivery strategies.

Virulence factors of Helicobacter pylori vacA increase markedly gastric mucosal TGF-β1 mRNA expression in gastritis patients

OBJECTIVE

Helicobacter pylori (H. pylori) infection is the main cause of gastric inflammation. Regulatory T cells (Treg cells) suppress the activation and proliferation of antigen-specific T cells and mediate immunologic tolerance. TGF-β1 was shown to be secreted in a subset of Treg cells known as 'Th3 cells'. These cells have not been sufficiently studied in context to H. pylori-induced inflammation in human gastric mucosa. In this study we therefore, aimed to investigate the expression of TGF-β1 in the context of H. pylori colonization in chronic gastritis, to examine the relationship between it and histopathologic findings and to compare it with virulence factors.

PATIENTS AND METHODS

Total RNA was extracted from gastric biopsies of 48 H. pylori-infected patients and 38 H. pylori-negative patients with gastritis. Mucosal TGF-β1 mRNA expression in H. pylori-infected and uninfected gastric biopsies was determined by real-time PCR. Presence of vacA, cagA, iceA, babA2 and oipA virulence factors was evaluated using PCR.

RESULTS

TGF-β1 mRNA expression was significantly increased in biopsies of H. pylori-infected patients compared to H. pylori-uninfected patients. There was association between virulence factors and TGF-β1 mRNA expression. TGF-β1 mRNA expression in mucosa was significantly higher in patients with vacA s1 and s1m1.

CONCLUSIONS

TGF-β1 may play an important role in the inflammatory response and promote the chronic and persistent inflammatory changes in the gastric. This may ultimately influence the outcome of H. pylori-associated diseases that arise within the context of gastritis and vacA may suffice to induce expression of TGF-β1 mRNA.

Optimising the quantification of cytokines present at low concentrations in small human mucosal tissue samples using Luminex assays

Sensitive measurement of multiple cytokine profiles from small mucosal tissue biopsies, for example human gastric biopsies obtained through an endoscope, is technically challenging. Multiplex methods such as Luminex assays offer an attractive solution but standard protocols are not available for tissue samples. We assessed the utility of three commercial Luminex kits (VersaMAP, Bio-Plex and MILLIPLEX) to measure interleukin-17A (IL-17) and interferon-gamma (IFNγ) concentrations in human gastric biopsies and we optimised preparation of mucosal samples for this application. First, we assessed the technical performance, limits of sensitivity and linear dynamic ranges for each kit. Next we spiked human gastric biopsies with recombinant IL-17 and IFNγ at a range of concentrations (1.5 to 1000 pg/mL) and assessed kit accuracy for spiked cytokine recovery and intra-assay precision. We also evaluated the impact of different tissue processing methods and extraction buffers on our results. Finally we assessed recovery of endogenous cytokines in unspiked samples. In terms of sensitivity, all of the kits performed well within the manufacturers' recommended standard curve ranges but the MILLIPLEX kit provided most consistent sensitivity for low cytokine concentrations. In the spiking experiments, the MILLIPLEX kit performed most consistently over the widest range of concentrations. For tissue processing, manual disruption provided significantly improved cytokine recovery over automated methods. Our selected kit and optimised protocol were further validated by measurement of relative cytokine levels in inflamed and uninflamed gastric mucosa using Luminex and real-time polymerase chain reaction. In summary, with proper optimisation Luminex kits (and for IL-17 and IFNγ the MILLIPLEX kit in particular) can be used for the sensitive detection of cytokines in mucosal biopsies. Our results should help other researchers seeking to quantify multiple low concentration cytokines in small tissue samples.

Lower circulating levels of chemokine CXCL10 in Helicobacter pylori-infected patients with peptic ulcer: Influence of the bacterial virulence factor CagA

BACKGROUND AND OBJECTIVES

Alterations in CXCL10 (a Th1 chemokine) expression have been associated with various diseases. The aim of this study was to evaluate the serum CXCL10 levels in H. pylori-infected patients with peptic ulcer (PU), H. pylori-infected asymptomatic (AS) subjects and healthy H. pylori-negative subjects, and also to determine its association with bacterial virulence factor cytotoxin-associated gene A (CagA).

MATERIALS AND METHODS

Serum samples from 90 H. pylori infected patients with PU (70 were anti-CagA(+), 20 were anti-CagA(-)), 65 AS carriers (40 were anti-CagA(+), 25 were anti-CagA(-)) and 30 healthy H. pylori-negative subjects (as a control group) were tested for concentrations of CXCL10 by using the ELISA method.

RESULTS

The mean serum levels of CXCL10 in PU patients (96.64 ± 20.85 pg/mL) were significantly lower than those observed in AS subjects (162.16 ± 53.31 pg/mL, P < 0.01) and the control group (193.93 ± 42.14 pg/mL, P < 0.02). In the PU group, the serum levels of CXCL10 in anti-CagA(+) subjects was significantly higher in comparison to anti-CagA(-) patients (P < 0.04).

CONCLUSION

These results showed that the mean concentrations of CXCL10 in H. pylori-infected-PU patients was lower than AS carriers and control group. In the PU group, the serum levels of CXCL10 were associated with bacterial factor CagA.

In silico experiment with an-antigen-toll like receptor-5 agonist fusion construct for immunogenic application to Helicobacter pylori

BACKGROUNDS

Helicobacter pylori colonize the gastric mucosa of half of the world's population. Although it is classified as a definitive type I carcinogen by World Health Organization, there is no effective vaccine against this bacterium. H. pylori evade the host immune response by avoiding toll-like detection, such as detection via toll-like receptor-5 (TLR-5). Thus, a chimeric construct consisting of selected epitopes from virulence factors that is incorporated into a TLR-5 ligand (Pseudomonas flagellin) could result in more potent innate and adaptive immune responses.

MATERIALS AND METHODS

Based on the histocompatibility antigens of BALB/c mice, in silico techniques were used to select several fragments from H. pylori virulence factors with a high density of B- and T-cell epitopes.

RESULTS

These segments consist of cytotoxin-associated geneA (residue 162-283), neutrophil activating protein (residue 30-135) and outer inflammatory protein A (residue 155-268). The secondary and tertiary structure of the chimeric constructs and other bioinformatics analyses such as stability, solubility, and antigenicity were performed. The chimeric construct containing antigenic segments of H. pylori proteins was fused with the D3 domain of Pseudomonas flagellin. This recombinant chimeric gene was optimized for expression in Escherichia coli. The in silico results showed that the conserved C- and N-terminal domains of flagellin and the antigenicity of selected fragments were retained.

DISCUSSION

In silico analysis showed that Pseudomonas flagellin is a suitable platform for incorporation of an antigenic construct from H. pylori. This strategy may be an effective tool for the control of H. pylori and other persistent infections.

Enhancement of Helicobacter pylori outer inflammatory protein DNA vaccine efficacy by co-delivery of interleukin-2 and B subunit heat-labile toxin gene encoded plasmids

Development of an effective vaccine for controlling H. pylori-associated infection, which is present in about half the people in the world, is a priority. The H. pylori outer inflammatory protein (oipA) has been demonstrated to be a potential antigen for a vaccine. In the present study, use of oipA gene encoded construct (poipA) for C57BL/6 mice vaccination was investigated. Whether co-delivery of IL-2 gene encoded construct (pIL-2) and B subunit heat-labile toxin of Escherichia coli gene encoded construct (pLTB) can modulate the immune response and enhance DNA vaccine efficacy was also explored. Our results demonstrated that poipA administered intradermally ('gene gun' immunization) promoted a strong Th2 immune response, whereas co-delivery of either pIL-2 or pLTB adjuvant elicited a Th1-biased immune response. PoipA administered with both pIL-2 and pLTB adjuvants promoted a strong Th1 immune response. Regardless of the different immune responses promoted by the various vaccination regimes, all immunized mice had smaller bacterial loads after H. pylori challenge than did PBS negative and pVAX1 mock controls. Co-delivery of adjuvant(s) enhances poipA DNA vaccine efficacy by shifting the immune response from being Th2 to being Th1-biased, which results in a greater reduction in bacterial load after H. pylori challenge. Both prophylactic and therapeutic vaccination can achieve sterile immunity in some subjects.

Therapeutic vaccination with Salmonella-delivered codon-optimized outer inflammatory protein DNA vaccine enhances protection in Helicobacter pylori infected mice

Vaccination had demonstrated as an alternative way to combat Helicobacter pylori challenge. In the present study, codon-optimized outer inflammatory protein gene (oipA) for Mus species codon usage, the inclusion of optimal Kozak sequence, and modified of GC content was applied to construct a novel DNA construct. The Salmonella-delivered wild type oipA construct (SL7207/poipA) and the Salmonella-delivered codon-optimized oipA construct (SL7207/poipA-opt) were prepared and their therapeutic efficacy was evaluated in H. pylori-infected mice. The codon-optimized oipA construct (poipA-opt) expressed almost six-fold higher protein than that of wild type construct (poipA) as normalized to the β-actin expression in AGS cells. Oral therapeutic immunization with SL7207/poipA-opt significantly eliminated H. pylori colonization in the stomach; and protection was related to a robust Th1/Th2 immune response. Therefore, our results suggested that fine therapeutic efficacy was related to sufficient expression of the antigen. It is supposed that codon-optimized oipA gene improves protein expression and consequently enhances the immunogenicity of DNA vaccine, which resulted in a significant reduction of bacterial loads in H. pylori infected mice. The Salmonella-delivered codon-optimized DNA construct could be a candidate vaccine against H. pylori for the clinical application.

Serum antibodies protect against intraperitoneal challenge with enterotoxigenic Escherichia coli

To assess whether anticolonization factor antigen I (CFA/I) fimbriae antibodies (Abs) from enterotoxigenic Escherichia coli (ETEC) can protect against various routes of challenge, BALB/c mice were immunized with a live attenuated Salmonella vaccine vector expressing CFA/I fimbriae. Vaccinated mice elicited elevated systemic IgG and mucosal IgA Abs, unlike mice immunized with the empty Salmonella vector. Mice were challenged with wild-type ETEC by the oral, intranasal (i.n.), and intraperitoneal (i.p.) routes. Naïve mice did not succumb to oral challenge, but did to i.n. challenge, as did immunized mice; however, vaccinated mice were protected against i.p. ETEC challenge. Two intramuscular (i.m.) immunizations with CFA/I fimbriae without adjuvant conferred 100% protection against i.p. ETEC challenge, while a single 30 μg dose conferred 88% protection. Bactericidal assays showed that ETEC is highly sensitive to anti-CFA/I sera. These results suggest that parenteral immunization with purified CFA/I fimbriae can induce protective Abs and may represent an alternative method to elicit protective Abs for passive immunity to ETEC.

Oral immunization with recombinant Mycobacterium smegmatis expressing the outer membrane protein 26-kilodalton antigen confers prophylactic protection against Helicobacter pylori infection

Helicobacter pylori infection is prevalent worldwide and results in chronic gastritis, which may lead to gastric mucosa-associated lymphoid tissue lymphoma and gastric cancer. We have previously reported that oral immunization with recombinant Mycobacterium smegmatis expressing the H. pylori outer membrane protein 26-kilodalton (Omp26) antigen affords therapeutic protection against H. pylori infection in mice. In the present study, we investigated the prophylactic effects of this vaccine candidate on H. pylori challenge in mice. We found that oral immunization with recombinant Mycobacterium Omp26 significantly reduced H. pylori colonization in the stomach compared to inoculation with wild-type M. smegmatis in control mice. Six of the recombinant Mycobacterium-immunized mice (60%) were completely protected from H. pylori infection. The severity of H. pylori-associated chronic gastritis assessed histologically was significantly milder in mice vaccinated with recombinant Mycobacterium than in control animals. Mice immunized with recombinant Mycobacterium showed enhanced antigen-specific lymphocyte proliferation and antibody responses. Moreover, immunization with recombinant Mycobacterium resulted in an increased expression of interleukin-2 and gamma interferon in the stomach and spleen, as determined by reverse transcription-PCR analysis. Our results collectively suggest that vaccination with recombinant Mycobacterium Omp26 confers prophylactic protection against H. pylori infection. The inhibition of H. pylori colonization is associated with the induction of antigen-specific humoral and cell-mediated immune responses.

Dendritic cells prevent rather than promote immunity conferred by a helicobacter vaccine using a mycobacterial adjuvant

BACKGROUND & AIMS

Immunization against the gastric bacterium Helicobacter pylori could prevent many gastric cancers and other disorders. Most vaccination protocols used in preclinical models are not suitable for humans. New adjuvants and a better understanding of the correlates and requirements for vaccine-induced protection are needed to accelerate development of vaccines for H pylori.

METHODS

Vaccine-induced protection against H pylori infection and its local and systemic immunological correlates were assessed in animal models, using cholera toxin or CAF01 as adjuvants. The contribution of B cells, T-helper (Th)-cell subsets, and dendritic cells to H pylori-specific protection were analyzed in mice.

RESULTS

Parenteral administration of a whole-cell sonicate, combined with the mycobacterial cell-wall-derived adjuvant CAF01, protected against infection with H pylori and required cell-mediated, but not humoral, immunity. The vaccine-induced control of H pylori was accompanied by Th1 and Th17 responses in the gastric mucosa and in the gut-draining mesenteric lymph nodes; both Th subsets were required for protective immunity against H pylori. The numbers of memory CD4+ T cells and neutrophils in gastric tissue were identified as the best correlates of protection. Systemic depletion of dendritic cells or regulatory T cells during challenge infection significantly increased protection by overriding immunological tolerance mechanisms activated by live H pylori.

CONCLUSIONS

Parenteral immunization with a Helicobacter vaccine using a novel mycobacterial adjuvant induces protective immunity against H pylori that is mediated by Th1 and Th17 cells. Tolerance mechanisms mediated by dendritic cells and regulatory T cells impair H pylori clearance and must be overcome to improve immunity.

Immunogenicity of attenuated measles virus engineered to express Helicobacter pylori neutrophil-activating protein

Helicobacter pylori is a Gram-negative, spiral-shaped microorganism associated with acute and chronic gastritis, peptic ulcer, gastric cancer and gastric lymphomas in humans. H. pylori neutrophil-activating protein (NAP) is a major virulence factor playing a central role in pathogenesis of mucosal inflammation by immune cell attraction and Th1 cytokine response polarization. NAP is protective antigen and promising vaccine candidate against H. pylori infection. Here we present the development of measles virus (MV) vaccine strain encoding the NAP antigen. In order to facilitate the extracellular transport and detection, NAP was inserted in the human lambda immunoglobulin chain replacing a major part of the variable domain. We generated two MV vectors expressing secretory NAP forms: MV-lambda-NAP encoding the full-length constant lambda light chain domain and MV-s-NAP encoding only the N-terminus of the lambda light chain with the leader peptide. Immunization of MV permissive Ifnarko-CD46Ge transgenic mice by a single intraperitoneal injection of the NAP-expressing strains induced a robust, long-term humoral and cellular immune response against MV. Nine months post vaccination measles-neutralizing antibody titers were above the serum level considered protective for humans. Furthermore, all animals immunized with MV strains expressing the secretory NAP antigen developed strong humoral immunity against NAP, reaching titers >1:10,000 within 2-4 weeks. IFN-γ ELISpot assay confirmed that NAP-encoding MV vectors can also stimulate NAP-specific cell-mediated immunity. Our data demonstrate that MV is an excellent vector platform for expression of bacterial antigens and development of vaccines for H. pylori immunoprophylaxis in humans.

Inflammation, immunity, and vaccines for Helicobacter pylori

Helicobacter pylori infects almost half of the population worldwide and represents the major cause of gastroduodenal diseases, such as duodenal and gastric ulcer, gastric adenocarcinoma, autoimmune gastritis, and B-cell lymphoma of mucosa-associated lymphoid tissue. Helicobacter pylori induces the activation of a complex and fascinating cytokine and chemokine network in the gastric mucosa. Different bacterial and environmental factors, other concomitant infections, and host genetics may influence the balance between mucosal tolerance and inflammation in the course of H. pylori infection. An inverse association between H. pylori prevalence and the frequencies of asthma and allergies was demonstrated, and the neutrophil activating protein of H. pylori was shown to inhibit the allergic inflammation of bronchial asthma. During the last year, significant progress was made on the road to the first efficient vaccine for H. pylori that will represent a novel and very important bullet against both infection and gastric cancer.