The GroES homolog of Helicobacter pylori confers protective immunity against mucosal infection in mice

Embedding of exogenous B cell epitopes on the surface of UreB structure generates a broadly reactive antibody response against Helicobacter pylori

Since Helicobacter pylori (H. pylori) resistance to antibiotic regimens has increased, vaccination is becoming an increasingly important alternative therapy to control H. pylori infection. UreB, FlaA, AlpB, SabA, and HpaA proteins of H. pylori were previously proved to be used as candidate vaccine antigens. Here, we developed an engineered antigen based on a recombinant chimeric protein containing a structural scaffold from UreB and B cell epitopes from FlaA, AlpB, SabA, and HpaA. The multi-epitope chimeric antigen, named MECU, could generate a broadly reactive antibody response including antigen-specific antibodies and neutralising antibodies against H. pylori urease and adhesins. Moreover, therapeutic immunisation with MECU could reduce H. pylori colonisation in the stomach and protect the stomach in BALB/c mice. This study not only provides promising immunotherapy to control H. pylori infection but also offers a reference for antigen engineering against other pathogens.

DnaJ-induced miRNA-146a negatively regulates the expression of IL-8 in macrophages

As a member of the damage-associated molecular patterns, heat shock proteins (HSPs) are widely recognized for their role in initiating innate immune responses. These highly conserved proteins are expressed ubiquitously in both prokaryotes and eukaryotes. In this study, our aim was to investigate how DnaJ, a HSP40 homolog derived from Pseudomonas aeruginosa (P. aeruginosa), influences the regulation of IL-8 expression in macrophages. Treatment with DnaJ served as a stimulus, inducing a more robust expression of IL-8 compared to other HSP homologs, including DnaK, GroEL, and HtpG. This effect was achieved through the activation of the NF-κB signaling pathway. Interestingly, DnaJ treatment also significantly increased the expression of microRNA-146a (miR-146a), which appears to play a role in modulating the expression of innate defense genes. As a consequence, pre-treatment with DnaJ led to a reduction in the extent of IL-8 induction in response to P. aeruginosa treatment. Notably, this reduction was counteracted by transfection of a miR-146a inhibitor, highlighting the involvement of miR-146a in P. aeruginosa-mediated induction of IL-8 expression. Therefore, this study uncovers the role of DnaJ in triggering the expression of miR-146a, which, in turn, modulates the excessive expression of IL-8 induced by P. aeruginosa infection.

How Long Will It Take to Launch an Effective Helicobacter pylori Vaccine for Humans?

Helicobacter pylori infection often occurs in early childhood, and can last a lifetime if not treated with medication. H. pylori infection can also cause a variety of stomach diseases, which can only be treated with a combination of antibiotics. Combinations of antibiotics can cure H. pylori infection, but it is easy to relapse and develop drug resistance. Therefore, a vaccine is a promising strategy for prevention and therapy for the infection of H. pylori. After decades of research and development, there has been no appearance of any H. pylori vaccine reaching the market, unfortunately. This review summarizes the aspects of candidate antigens, immunoadjuvants, and delivery systems in the long journey of H. pylori vaccine research, and also introduces some clinical trials that have displayed encouraging or depressing results. Possible reasons for the inability of an H. pylori vaccine to be available over the counter are cautiously discussed and some propositions for the future of H. pylori vaccines are outlined.

Oral Administration of a Shigella 2aT32-Based Vaccine Expressing UreB-HspA Fusion Antigen With and Without Parenteral rUreB-HspA Boost Confers Protection Against Helicobacter pylori in Mice Model

Helicobacter pylori (H. pylori) is a gram-negative pathogen classified as a class I carcinogen. The H. pylori urease B subunit (UreB) and heat shock protein A (HspA) are two important vaccine candidate antigens. In this study, we evaluated the immunogenicity and immunoprotective effect of the attenuated Shigella vector vaccine SH02 expressing the UreB-HspA fusion protein of H. pylori in a mouse model. Oral SH02 with or without subcutaneous injection of rUreB-HspA induced antigen-specific serum IgG, mucosal sIgA, and T cells immune response. Subcutaneous injection of the candidate antigen rUreB-HspA enhanced the level of serum antigen-specific IgG antibodies (p < 0.0001) and the levels of IgG1/IgG2a/IgG2b subtypes. In addition, injection boost also increased the proportion of spleen antigen-specific CD4+CD154+ T cells (p < 0.001), and the proportion of CD4+CD154+ T cells that secrete IFN-γ and IL-17A. Following the H. pylori challenge, the levels of H. pylori colonization in the two experimental groups (Groups A and B) significantly reduced compared with the control group (p < 0.001), indicating that the candidate vaccine yielded a preventive effect of anti-H.pylori infection. Compared with the non-subcutaneous booster injection group (Group A), the subcutaneous booster injection group (Group B) exhibited less gastric inflammation, but there was no significant difference in the level of colonization (p > 0.05). These results lay a foundation for the development of a vaccine against H. pylori and the optimization of immunization methods and procedures to prevent H. pylori infection.

DnaJ-induced TLR7 mediates an increase in interferons through the TLR4-engaged AKT/NF-κB and JNK signaling pathways in macrophages

Toll-like receptor 7 (TLR7) signaling plays pivotal roles in innate immunity by sensing viral single-stranded RNA thereby triggering inflammatory signaling cascades and eliciting protective antiviral responses. In this study, we found that TLR7 expression is highly induced in response to Pseudomonas aeruginosa (P. aeruginosa) infection in a dose- and time-dependent manner. P. aeruginosa-derived DnaJ, a homolog of HSP40, was identified as a related inducing agent for TLR7 expression, and expression of DnaJ was stimulated when host cells were infected with P. aeruginosa. Interestingly, DnaJ was not involved in mediating an increase in the expression levels of TLR3 and TLR8, other well-known antiviral receptors. The induction of TLR7 in response to DnaJ was mediated by the activation of the AKT (Thr308 and Ser473)/NF-κB and p38/JNK MAPKs signaling pathways, consequently transmitting related signals for the expression of interferons (IFNs). Of note, these antiviral responses were regulated, at least in part, by TLR4, which senses the presence of DnaJ and then promotes downstream activation of the AKT (Ser473)/NF-κB and JNK signaling cascades. Taken together, these results suggest that P. aeruginosa-derived DnaJ is sufficient to promote an increase in TLR7 expression in the TLR4-engaged AKT/NF-κB and JNK signaling pathways, thereby promoting an increased antiviral response through the elevated expression of IFNs.

Identification of B-Cell Epitopes of HspA from Helicobacter pylori and Detection of Epitope Antibody Profiles in Naturally Infected Persons

Helicobacter pylori (H. pylori), heat-shock protein A (HspA), is a bacterial heat-shock chaperone that serves as a nickel ion scavenging protein. Ni²⁺ is an important co-factor required for the maturation and enzymatic activity of H. pylori urease and [NiFe] hydrogenase, both of which are key virulence factors for pathogen survival and colonization. HspA is an important target molecule for the diagnosis, treatment, and immune prevention of H. pylori. In this work, HspA was truncated into five fragments to determine the location of an antigen immunodominant peptide. A series of overlapping, truncated 11-amino-acid peptides in immunodominant peptide fragments were synthesized chemically and screened by ELISA. The immunogenicity and antigenicity of the screened epitope peptides were verified by ELISA, Western blot, and lymphocyte proliferation tests. Two novel B-cell epitopes were identified, covering amino acids 2–31 of HspA, which are HP11 (2–12; KFQPLGERVLV) and HP19 (18–28; ENKTSSGIIIP). The antiserum obtained from HP11-KLH and HP19-KLH immunized mice can bind to naive HspA in H. pylori SS2000, rHspA expressed in E. coli, and the corresponding GST fusion peptide. Among HspA seropositive persons, the seropositive rates of HP11 and HP19 were 21.4% and 33.3%, respectively. Both of the B-cell epitopes of HspA are highly conserved epitopes with good antigenicity and immunogenicity.

DNA vaccine containing Flagellin A gene induces significant immune responses against Helicobacter pylori infection: An in vivo study

Objective(s):

Helicobacter pylori is one of the most prevalent human infectious agents that is directly involved in various upper digestive tract diseases. Although antibiotics-based therapy and proton pump inhibitors eradicate the bacteria mostly, their effectiveness has been declined recently due to emergence of antibiotic-resistant strains. Development of a DNA vaccine is a promising approach against bacterial pathogens. Genes encoding motility factors are promising immunogens to develop a DNA vaccine against H. pylori infection due to critical role of these genes in bacterial attachment and colonization within the gastric lumen. The present study aimed to synthesize a DNA vaccine construct based on the Flagellin A gene (flaA), the predominant flagellin subunit in H. pylori flagella.

Materials and Methods:

The coding sequence of flaA was amplified through PCR and sub-cloned in the pBudCE4.1 vector. The recombinant vector was introduced into the human dermal fibroblast cells, and its potency to express the flaA protein was analyzed using SDS-PAGE. The recombinant construct was intramuscularly (IM) injected into the mice, and the profiles of cytokines and immunoglobulins were measured using ELISA.

Results:

It has been found that flaA was successfully expressed in cells. Recombinant-vector also increased the serum levels of evaluated cytokines and immunoglobulins in mice.

Conclusion:

These findings showed that the pBudCE4.1-flaA construct was able to activate the immune responses. This study is the first step towards synthesis of recombinant-construct based on the flaA gene. Immunization with such construct may inhibit the H. pylori-associated infection; however, further experiments are urgent.

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

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

HSP70-Homolog DnaK of Pseudomonas aeruginosa Increases the Production of IL-27 through Expression of EBI3 via TLR4-Dependent NF-κB and TLR4-Independent Akt Signaling

IL-27, a heterodimeric cytokine composed of the p28 subunit and Epstein–Barr virus-induced gene 3 (EBI3), acts as a potent immunosuppressant and thus limits pathogenic inflammatory responses. IL-27 is upregulated upon Pseudomonas aeruginosa infection in septic mice, increasing susceptibility to the infection and decreasing clearance of the pathogen. However, it remains unclear which P. aeruginosa-derived molecules promote production of IL-27. In this study, we explored the mechanism by which P. aeruginosa DnaK, a heat shock protein 70-like protein, induces EBI3 expression, thereby promoting production of IL-27. Upregulation of EBI3 expression did not lead to an increase in IL-35, which consists of the p35 subunit and EBI3. The IL-27 production in response to DnaK was biologically active, as reflected by stimulation of IL-10 production. DnaK-mediated expression of EBI3 was driven by two distinct signaling pathways, NF-κB and Akt. However, NF-κB is linked to TLR4-associated signaling pathways, whereas Akt is not. Taken together, our results reveal that P. aeruginosa DnaK potently upregulates EBI3 expression, which in turn drives production of the prominent anti-inflammatory cytokine IL-27, as a consequence of TLR4-dependent activation of NF-κB and TLR4-independent activation of the Akt signaling pathway.

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.

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

BACKGROUND

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

How far are we from vaccination against Helicobacter pylori infection?

INTRODUCTION

Helicobacter pylori infection results in chronic gastritis, peptic ulcer, or gastric cancer; therefore, eradication of this bacterium is essential. The strategy for developing effective vaccines against H. pylori entails immunization of mice with a combination of classical and recombinant H. pylori antigens, but this has proven to be onerous in all cases.

AREAS COVERED

We have reviewed literature databases in PubMed and Scopus using the key words H. pylori, vaccine, and vaccination and have conducted a systematic review of published clinical trials and animal model studies on vaccines against H. pylori and have tried to summarize why the vaccines are not effective or only partially effective.

EXPERT COMMENTARY

This is the perfect time to review vaccine development against H. pylori as, after several failed attempts, promising results were reported by Zeng et al. in 2015. Successful vaccine development requires knowledge of both the immune mechanisms active during natural infection by H. pylori, owing to the complicated host response against the pathogen, and the factors that allow the persistence of bacteria, such as genetic diversity of H. pylori. Moreover, various clinical trials are needed to prove vaccine efficacy.

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.

Whole genome sequencing data of 1110 Mycobacterium tuberculosis isolates identifies insertions and deletions associated with drug resistance

Background

Drug resistance in Mycobacterium tuberculosis (MTB) is one of the major challenges in tuberculosis (TB) treatment. However, known mutations cannot explain all of the cases of resistance and little research has focused on the relationship between insertions / deletions (indels) and drug resistance.

Results

Here, we retrieved whole genome sequencing data of 743 drug-resistant MTB strains and 367 pan-susceptible strains from TB patients from the public domain to identify novel genomic markers of drug resistance. A total of 20 region markers containing genes and intergenic regions (IGRs) with significant statistical correlation with antibiotic resistance were revealed, four of which have been previously reported to be associated with drug resistance. In addition, 83 point markers containing frameshift (FS) mutations and IGR indels were also identified independently based on differences in their incidence rates between drug-sensitive and -resistant strains. Among the 83 point markers, eight indels were detected in known drug-associated genes or IGRs. Furthermore, the overlap between 20 region markers and 83 point markers further indicated their associations with drug resistance. The markers identified were involved in essential bacterial metabolic functions, including cell wall and transmembrane transporter functions. A strong correlation between FS mutations and mutations in DNA repair genes including I21V in alkA, R48G in mutT4 and P2R in nth was also found.

Conclusions

This study identified a set of novel genetic markers with FS mutations and IGR indels associated with MTB drug resistance, which greatly broadens the pool of mutations related to MTB drug resistance. This insight may be important in identifying novel mechanisms of drug resistance in MTB.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-4734-6) contains supplementary material, which is available to authorized users.

A survey on chimeric UreB229-561-HpaA protein targeting Helicobacter pylori: Computational and in vitro urease activity valuation

Helicobacter pylori (H. pylori) as microaerophilic, Gram-negative bacterium colonize the human gastric milieu, where it impetuses chronic disorders. Vaccination is a complementary plan, along with antibiotic therapy, for clearance of H. pylori. Today, Computer based tools are essential for the evaluation, design, and experiment for novel chimeric targets for immunological administration. The purpose of this experiment was immunoinformatic analysis of UreB and HpaA molecules in a fusion arrangement and also, construction and expression of recombinant protein containing chimeric sequences. The targets sequences were screened by using of standard in silico tools and immunoinformatic web servers. The high-resolution 3D models of the protein were created and were validated; indeed, the B-and T-cell restricted epitopes were mapped on the chimeric protein. The recombinant protein in frame of the expression vector pET28a were expressed and purified successfully. The urease activity and immunoblotting were performed in vitro condition. This study confirmed that the engineered protein as a highly conserved, hydrophilic, non-allergenic contained remarkable B-cell and T-cell epitopes. It was magnificently attained; chimeric UreB_229-561-HpaA could provoke both humoral and cellular immunity. The immunoblotting was shown that the chimeric protein could be detected by serum of immunized animal and H.pylori positive patients. In this study, several antigenic patches from UreB and HpaA were identified that could be an efficient immune system activator. The in vitro analysis of our chimeric molecule confirmed its urease activity. It also confirmed that the chimeric protein could be detected by serum of immunized animal and H.pylori positive patients.

Inflammation and Genes

Inflammation is a protective immune response to infection, trauma, or injury; however, only a subset of patients develops inflammation, suggesting other contributing factors involved, such as the environment and genes. Inflammationassociated genes involving those with pro- and anti-inflammatory effect should be properly balanced and regulated; the protein products of these genes ultimately determine the outcome of inflammation. Apart from gene mutations, gene polymorphisms related to some inflammatory markers also appear to correlate with the incidence and/or outcome of serious inflammatory events. Some genes recently recognized to be associated with inflammation are briefly reviewed. Modern genomic approaches, such as DNA micro-arrays and serial analysis of gene expression, allow for determining the extremely complex profile of inflammatory genes.

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.

Helicobacter pylori antigenic Lpp20 is a structural homologue of Tipα and promotes epithelial-mesenchymal transition

BACKGROUND

Helicobacter pylori is a bacterium that affects about 50% of the world population and, despite being often asymptomatic, it is responsible of several gastric diseases, from gastritis to gastric cancer. The protein Lpp20 (HP1456) plays an important role in bacterium survival and host colonization, but the possibility that it might be involved in the etiology of H. pylori-related disorders is an unexplored issue. Lpp20 is a lipoprotein bound to the external membrane of the bacterium, but it is also secreted inside vesicles along with other two proteins of the same operon, i.e. HP1454 and HP1457.

RESULTS

In this study we determined the crystal structure of Lpp20 and we found that it has a fold similar to a carcinogenic factor released by H. pylori, namely Tipα. We demonstrate that Lpp20 promotes cell migration and E-cadherin down-regulation in gastric cancer cells, two events recalling the epithelial-mesenchymal transition (EMT) process. Differently from Tipα, Lpp20 also stimulates cell proliferation.

CONCLUSIONS

This identifies Lpp20 as a new pathogenic factor produced by H. pylori that promotes EMT and thereby the progression of cancer to the metastatic state.

Protein signature characterizing Helicobacter pylori strains of patients with autoimmune atrophic gastritis, duodenal ulcer and gastric cancer

Background

Helicobacter pylori (H. pylori) represents a key factor in the etiology of autoimmune atrophic gastritis (AAG), duodenal ulcer (DU) and gastric cancer (GC). The aim of this study was to characterize the differential protein expression of H. pylori isolated from gastric biopsies of patients affected by either AAG, DU or GC.

Methods

The H. pylori strains were isolated from endoscopic biopsies from the stomach of patients with gastric disease. Protein profiles of H. pylori were compared by two-dimensional difference in gel electrophoresis (2D-DIGE) coupled with mass spectrometry (MS) for the identification of significantly different spots (Student t-test, p < 0.05).

Results

A total of 47 differentially expressed spots were found between H. pylori isolated from patients with either DU or AAG diseases and those isolated from patients with GC (Anova < 0.05, log fold change >1.5). These spots corresponded to 35 unique proteins. The identity of 7 protein spots was validated after one-dimensional electrophoresis and MS/MS analyses of excised gel portions. In H. pylori isolated from DU-patients a significant increase in proteins with antioxidant activity emerged (AroQ, AspA, FldA, Icd, OorA and ScoB), together with a higher content of proteins counteracting the high acid environment (KatA and NapA). In H. pylori isolated from AAG-patients proteins neutralizing hydrogen concentrations through organic substance metabolic processes decreased (GroL, TrxB and Tuf). In addition, a reduction of bacterial motility (FlhA) was found to be associated with AAG-H. pylori isolates. In GC-H. pylori strains it was found an increase in nucleic acid-binding proteins (e.g. DnaG, Tuf, RpoA, RplU) which may be involved in a higher demand of DNA- and protein-related processes.

Conclusion

Our data suggest the presence of specific protein signatures discriminating among H. pylori isolated from either AAG, DU or GC. Changes in protein expression profiles evaluated by DIGE succeeded in deciphering part of the molecular scenarios associated with the different H. pylori-related gastric diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/s13027-017-0133-x) contains supplementary material, which is available to authorized users.

The study of H. pylori putative candidate factors for single- and multi-component vaccine development

Helicobacter pylori has grown to colonize inside the stomach of nearly half of the world's population, turning into the most prevalent infections in the universe. Medical care failures noticeably confirm the need for a vaccine to hinder or deal with H. pylori. This review is planned to discuss the most known factors as a vaccine candidate, including single (AhpC, BG, CagA, KatA, Fla, Hsp, HWC, Lpp, LPS, NAP, OMP, OMV, SOD, Tpx, Urease, VacA) and multi-component vaccines. Many promising results in the field of single and multivalent vaccine can be seen, but there is no satisfactory outcome and neither a prophylactic nor a therapeutic vaccine to treat or eradicate the infection in human has been acquired. Hence, selecting suitable antigen is an important factor as an appropriate adjuvant. Taken all together, the development of efficient anti-H. pylori vaccines relies on the fully understanding of the interactions between H. pylori and its host immune system. Therefore, more work should be done on epitope mapping, analysis of molecular structure, and determination of the antigen determinant region as well due to design a vaccine, preferably a multi-component vaccine to elicit specific CD4 T-cell responses that are required for H. pylori vaccine efficacy.

DnaJ (hsp40) of Streptococcus pneumoniae is involved in bacterial virulence and elicits a strong natural immune reaction via PI3K/JNK

As a heat shock protein, DnaJ plays an important role in the pathogenesis of pneumococcal infection. However, how the virulence factor-DnaJ elicits host natural immunity still remains unclear. In this study, we investigated the effects of dnaJ deficiency in Streptococcus pneumoniae (S. pneumoniae) on bacterial virulence, and further explored the related molecular mechanisms in vivo and in vitro. By generating dnaJ deficient mutant (ΔdnaJ), the virulence and colonization were detected in murine pneumonia and sepsis models in vivo. Compared with wild-type parent strain, the abilities of rapid colonization and induction of inflammatory responses of ΔdnaJ in mouse lungs were significantly impaired. Simultaneously, recombinant DnaJ purified from E. coli expression system (rDnaJ) induced macrophage strain RAW264.7 to secrete IL-6 by activation of PI3K and JNK signal pathways, which were confirmed by the specific signaling inhibitors. In conclusion, DnaJ, a novel virulence protein, was essential for the virulence and colonization of S. pneumoniae and induced pro-inflammatory cytokine production in macrophages through PI3K/JNK.

Identification of Helicobacter pylori and the evolution of an efficacious childhood vaccine to protect against gastritis and peptic ulcer disease

Establishment of Helicobacter pylori infection as an etiologic agent of peptic ulcer disease and other gastric pathologies marked a revolution in gastroenterology which spurred an enormous interest in gastric physiology and immunology research. The association was soon also demonstrated in children as well. Application of antimicrobial therapies have proven remarkably efficacious in eradicating H. pylori and curing pediatric patients of duodenal ulcers as well as gastritis, negating a lifetime of ineffective therapy and life-threatening disease. Countries with high H. pylori prevalence and where H. pylori associated gastric cancer remains a primary cause of death due to cancer however would benefit from childhood vaccination. Studies in rodents and humans utilizing oral vaccination with bacterial exotoxin adjuvants demonstrated potential for limiting H. pylori colonization in the stomach. Almost 25 y of vaccine research recently culminated in a phase III clinical trial of over 4,000 children aged 6-15 y old to test an oral vaccine consisting of the H. pylori urease B subunit genetically fused to the E. coli heat labile toxin. Vaccination was demonstrated to have an efficacy of over 70%. Vaccination may now serve as an effective strategy to significantly reduce H. pylori associated disease in children throughout the world.

Role of the N-Acetylmuramoyl-l-Alanyl Amidase, AmiA, of Helicobacter pylori in Peptidoglycan Metabolism, Daughter Cell Separation, and Virulence

The human gastric pathogen, Helicobacter pylori, is becoming increasingly resistant to most available antibiotics. Peptidoglycan (PG) metabolism is essential to eubacteria, hence, an excellent target for the development of new therapeutic strategies. However, our knowledge on PG metabolism in H. pylori remains poor. We have further characterized an isogenic mutant of the amiA gene encoding a N-acetylmuramoyl-l-alanyl amidase. The amiA mutant displayed long chains of unseparated cells, an impaired motility despite the presence of intact flagella and a tolerance to amoxicillin. Interestingly, the amiA mutant was impaired in colonizing the mouse stomach suggesting that AmiA is a valid target in H. pylori for the development of new antibiotics. Using reverse phase high-pressure liquid chromatography, we analyzed the PG muropeptide composition and glycan chain length distribution of strain 26695 and its amiA mutant. The analysis showed that H. pylori lacked muropeptides with a degree of cross-linking higher than dimeric muropeptides. The amiA mutant was also characterized by a decrease of muropeptides carrying 1,6-anhydro-N-acetylmuramic acid residues, which represent the ends of the glycan chains. This correlated with an increase of very long glycan strands in the amiA mutant. It is suggested that these longer glycan strands are trademarks of the division site. Taken together, we show that the low redundancy on genes involved in PG maturation supports H. pylori as an actractive alternative model to study PG metabolism and cell shape regulation.

In Silico Design of a Chimeric Protein Containing Antigenic Fragments of Helicobacter pylori; A Bioinformatic Approach

Helicobacter pylori is a global health problem which has encouraged scientists to find new ways to diagnose, immunize and eradicate the H. pylori infection. In silico studies are a promising approach to design new chimeric antigen having the immunogenic potential of several antigens. In order to obtain such benefit in H. pylori vaccine study, a chimeric gene containing four fragments of FliD sequence (1-600 bp), UreB (327-334 bp),VacA (744-805 bp) and CagL(51-100 bp) which have a high density of B- and T-cell epitopes was designed. The secondary and tertiary structures of the chimeric protein and other properties such as stability, solubility and antigenicity were analyzed. The in silico results showed that after optimizing for the purpose of expression in Escherichia coli BL21, the solubility and antigenicity of the construct fragments were highly retained. Most regions of the chimeric protein were found to have a high antigenic propensity and surface accessibility. These results would be useful in animal model application and accounted for the development of an epitope-based vaccine against the H. pylori.

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

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

Current Status and Prospects for a Helicobacter pylori Vaccine

Helicobacter pylori infection contributes to a variety of gastric diseases. H pylori-associated gastric cancer is diagnosed in advanced stages, and a vaccine against H pylori is desirable in parts of the world where gastric cancer remains a common form of cancer. Some of the strategies of vaccine development used in animals have been tested in several phase 3 clinical trials; these trials have been largely unsuccessful, although H pylori-specific immune responses have been induced. New insights into promoting immunity and overcoming the immunosuppressive nature of H pylori infection are required to improve the efficacy of an H pylori vaccine.

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.

Co-administration of rIpaB domain of Shigella with rGroEL of S. Typhi enhances the immune responses and protective efficacy against Shigella infection

Shigella species cause severe bacillary dysentery in humans and are associated with high morbidity and mortality. The Invasion plasmid antigen (IpaB) protein, which is conserved across all Shigella spp., induces macrophage cell death and is required to invade host cells. The present study evaluates the immunogenicity and protective efficacy of the recombinant (r) domain region of IpaB (rIpaB) of S. flexneri. rIpaB was administered either alone or was co-administered with the rGroEL (heat shock protein 60) protein from S. Typhi as an adjuvant in a mouse model of intranasal immunization. The IpaB domain region (37 kDa) of S. flexneri was amplified from an invasion plasmid, cloned, expressed in BL21 Escherichia coli cells and purified. Immunization with the rIpaB domain alone stimulated both humoral and cell-mediated immune responses. Furthermore, robust antibody (IgG, IgA) and T-cell responses were induced when the rIpaB domain was co-administered with rGroEL. Antibody isotyping revealed higher IgG1 and IgG2a antibody titers and increased interferon-gamma (IFN-γ) secretion in the co-administered group. Immunization of mice with the rIpaB domain alone protected 60%-70% of the mice from lethal infection by S. flexneri, S. boydii and S. sonnei, whereas co-administration with rGroEL increased the protective efficacy to 80%-85%. Organ burden and histopathological studies also revealed a significant reduction in lung infection in the co-immunized mice compared with mice immunized with the rIpaB domain alone. This study emphasizes that the co-administration of the rIpaB domain and rGroEL protein improves immune responses in mice and increases protective efficacy against Shigella infection. This is also the first report to evaluate the potential of the GroEL (Hsp 60) protein of S. Typhi as an adjuvant molecule, thereby overcoming the need for commercial adjuvants.

Helicobacter pylori recombinant UreG protein: cloning, expression, and assessment of its seroreactivity

Background

Helicobacter pylori is a human pathogen and during the process of infection, antigens from the bacterium elicit strong host humoral immune responses. In our previous report, native H. pylori UreG protein showed good reactivity with sera from H. pylori patients. This study was aimed at producing the recombinant form of the protein (rUreG) and determining its seroreactivities.

Methods

The coding sequence of H. pylori UreG was cloned and the recombinant protein expressed and purified by affinity chromatography using nickel nitrilotriacetic acid (Ni-NTA) resin. The antigenicity of rUreG to detect H. pylori specific antibodies was determined by western blot, using HRP-conjugated anti-human IgG and IgA antibodies as probes. A total of 70 sera, comprising 30 positive and 40 control serum samples, were used. The positive sera were from culture-positive H. pylori-infected patients with duodenal ulcers, gastric ulcers, or gastritis. The control sera comprised three types of samples without detectable H. pylori antibodies, i.e. healthy individuals (with no history of gastric disorders) (n = 10); patients who attended an endoscopy clinic (because of gastrointestinal complaints) but were H. pylori culture negative (n = 20); and people with other diseases (n = 10). Additionally, hyperimmune mice serum against rUreG was raised and tested with the native and recombinant UreG protein.

Results

The ureG gene fragment was successfully cloned and expressed in both soluble and insoluble forms. Western blots on rUreG protein showed 70% (21/30) and 60% (18/30) reactivity with patients’ sera when probed with HRP-conjugated anti-human IgG and IgA antibodies, respectively; and the combination of the IgG and IgA western blots showed reactivity of 83.3% (25/30). By comparison, 97.5% and 92.5% of the control sera showed no reactivity when probed with HRP-conjugated anti-human IgG and IgA antibodies, respectively. Both the H. pylori lysate antigen and rUreG protein displayed a distinctive band at the expected molecular weight when probed with the hyperimmune mice serum.

Conclusion

The rUreG protein was successfully cloned and expressed and showed good reactivity with H. pylori culture-positive patients’ sera and no reactivity with most control sera. Thus, the diagnostic potential of this recombinant protein merits further investigation.

Helicobacter pylori: perspectives and time trends

The discovery of Helicobacter pylori three decades ago is a modern medical success story. It markedly changed our understanding of the pathophysiology of gastroduodenal diseases and led to an improvement in the treatment of diseases related to H. pylori infection. Many of these diseases (such as ulcer disease and mucosal associated lymphoid tissue lymphoma) have become curable, and others (gastric cancer) might be preventable with the application of H. pylori eradication therapy. Since its discovery, H. pylori has also been identified as a trigger for some extragastric diseases. Promising results in this exciting field might have a clinical effect in the near future. This Timeline gives an overview of the success of clinical research on H. pylori to date and highlights some future trends in this area.

Heat shock protein complex vaccination induces protection against Helicobacter pylori without exogenous adjuvant

BACKGROUND

The development of a vaccine against the human gastric pathogen Helicobacter pylori, the main causative agent of gastric adenocarcinoma, has been hampered by a number of issues, including the lack of a mucosal adjuvant for use in humans. Heat shock proteins (Hsp), highly conserved molecules expressed by both bacteria and mammalian species, possess a range of functions, including acting as chaperones for cellular proteins and the ability to activate innate immune receptors. Hsp complex (HspC) vaccines, containing Hsp derived from pathogenic bacteria, are immunostimulatory without addition of an exogenous adjuvant and can induce immunity against their chaperoned proteins. In this study we explored in mice the potential utility of a H. pylori HspC vaccine.

RESULTS

Vaccination with H. pylori HspC, by either the subcutaneous or respiratory mucosal route, induced a strong antibody response, elevated gastric cytokine levels and significant protection against subsequent live challenge with this pathogen. The level of protection induced by non-adjuvanted HspC vaccine was equivalent to that which resulted from vaccination with adjuvanted vaccines. While protection induced by immunisation with adjuvanted vaccines was associated with the development of a moderate to severe atrophic gastritis, that induced by H. pylori HspC only resulted in a mild inflammatory response, despite an increase in pro-inflammatory gastric cytokines. This reduced gastritis correlated with an increase in IL-10 and IL-13 levels in the gastric tissues of HspC vaccinated, H. pylori challenged mice.

CONCLUSIONS

H. pylori HspC vaccines have the potential to overcome some of the issues preventing the development of a human vaccine against this pathogen: HspC induced protective immunity against H. pylori without addition of an adjuvant and without the induction of a severe inflammatory response. However, complete protection was not obtained so further optimisation of this technology is needed if a human vaccine is to become a reality.

Immunization using GroEL decreases Clostridium difficile intestinal colonization

Clostridium difficile is a pathogen which is responsible for diarrhea and colitis, particularly after treatment with antibiotics. Clinical signs are mainly due to two toxins, TcdA and TcdB. However, the first step of pathogenesis is the colonization process. We evaluated C. difficile surface proteins as vaccine antigens in the hamster model to prevent intestinal colonization. This vaccination induced a partial protection of hamsters against death after a C. difficile challenge. A proteomic analysis of animal sera allowed us to identify proteins which could be responsible for the protection observed. Among these proteins, we identified the GroEL heat shock protein. To confirm the role of the specific GroEL antibodies in the delayed C. difficile colonization of hamsters, we performed an immunization assay in a mouse model. After intranasal immunization with the recombinant protein GroEL, we observed a lower C. difficile intestinal colonization in the immunized group as compared to the control group.

Vaccinating against Helicobacter pylori in the developing world

Helicobacter pylori infects more than half the world's population and in developing nations the incidence can be over 90%. The morbidity and mortality associated with H. pylori-associated diseases including ulcers and gastric cancer therefore, disproportionately impact the developing world. Mice have been used extensively to demonstrate the feasibility of developing a vaccine for H. pylori infection, and for testing antigens, routes of immunization, dose, and adjuvants. These successes however, have not translated well in clinical trials. Although there are examples where immune responses have been activated, there are few instances of achieving a reduced bacterial load. In vivo and in vitro analyses in both mice and humans demonstrates that the host responds to H. pylori infection through the activation of immunoregulatory mechanisms designed to suppress the anti-H. pylori response. Improved vaccine efficacy therefore, will require the inclusion of factors that over-ride or re-program these immunoregulatory rersponse mechanisms.

A systematic approach toward stabilization of CagL, a protein antigen from Helicobacter pylori that is a candidate subunit vaccine

An important consideration in the development of subunit vaccines is the loss of activity caused by physical instability of the protein. Such instability often results from suboptimal solution conditions related to pH and temperature. Excipients can help to stabilize vaccines, but it is important to screen and identify excipients that adequately contribute to stabilization of a given formulation. CagL is a protein present in strains of Helicobacter pylori (H. pylori) that possess type IV secretion systems. It contributes to bacterial adherence via α5β1 integrin, thereby making it an attractive subunit vaccine candidate. We characterized the stability of CagL in different pH and temperature conditions using a variety of spectroscopic techniques. Stability was assessed in terms of transition temperature with the accumulated data, and then incorporated into an empirical phase diagram (EPD) that provided an overview of CagL physical stability. These analyses indicated maximum CagL stability at pH 4-6 up to 40°C in the absence of excipient. Using this EPD analysis, aggregation assays were developed to screen a panel of excipients with some found to inhibit CagL aggregation. Candidate stabilizers were selected to confirm their enhanced stabilizing effect. These analyses will help in the formulation of a stable vaccine against H. pylori.

Immunization with the immunodominant Helicobacter suis urease subunit B induces partial protection against H. suis infection in a mouse model

Helicobacter (H.) suis is a porcine and human gastric pathogen. Previous studies in mice showed that an H. suis infection does not result in protective immunity, whereas immunization with H. suis whole-cell lysate (lysate) protects against a subsequent experimental infection. Therefore, two-dimensional gel electrophoresis of H. suis proteins was performed followed by immunoblotting with pooled sera from H. suis- infected mice or mice immunized with lysate. Weak reactivity against H. suis proteins was observed in post-infection sera. Sera from lysate-immunized mice, however, showed immunoreactivity against a total of 19 protein spots which were identified using LC-MS/MS. The H. suis urease subunit B (UreB) showed most pronounced reactivity against sera from lysate-immunized mice and was not detected with sera from infected mice. None of the pooled sera detected H. suis neutrophil-activating protein A (NapA). The protective efficacy of intranasal vaccination of BALB/c mice with H. suis UreB and NapA, both recombinantly expressed in Escherichia coli (rUreB and rNapA, respectively), was compared with that of H. suis lysate. All vaccines contained choleratoxin as adjuvant. Immunization of mice with rUreB and lysate induced a significant reduction of H. suis colonization compared to non-vaccinated H. suis-infected controls, whereas rNapA had no significant protective effect. Probably, a combination of local Th1 and Th17 responses, complemented by antibody responses play a role in the protective immunity against H. suis infections.

Helicobacter pylori thiolperoxidase as a protective antigen in single- and multi-component vaccines

Helicobacter pylori is an important pathogen of the human stomach, and the development of a protective vaccine has been an enticing goal for many years. The H. pylori antioxidant enzymes superoxide dismutase (SOD) and catalase (KatA) have been shown to be protective as vaccine antigens in mice, demonstrating that the organism's antioxidant enzyme system is a fruitful target for vaccine development. The research described here demonstrates that an additional antioxidant enzyme, thiolperoxidase (Tpx), is effective as a prophylactic vaccine antigen via both systemic and mucosal routes. The functional relationship between SOD, KatA and Tpx also provided an opportunity to investigate synergistic or additive effects when the three antigens were used in combination. Although the antigens still provided equivalent protection when administered in combination, no additional protection was observed. Moreover a decrease in antibody titres to the individual antigens was observed when delivered in combination via the nasal route, though not when injected subcutaneously. The findings of this paper demonstrate that the antioxidant system of H. pylori presents a particularly rich resource for vaccine development.

Alkyl hydroperoxide reductase: a candidate Helicobacter pylori vaccine

Helicobacter pylori (H. pylori) is the most important etiological agent of chronic active gastritis, peptic ulcer disease and gastric cancer. The aim of this study was to evaluate the efficacy of alkyl hydroperoxide reductase (AhpC) and mannosylated AhpC (mAhpC) as candidate vaccines in the C57BL/6J mouse model of H. pylori infection. Recombinant AhpC was cloned, over-expressed and purified in an unmodified form and was also engineered to incorporate N and C-terminal mannose residues when expressed in the yeast Pichia pastoris. Mice were immunized systemically and mucosally with AhpC and systemically with mAhpC prior to challenge with H. pylori. Serum IgG responses to AhpC were determined and quantitative culture was used to determine the efficacy of vaccination strategies. Systemic prophylactic immunization with AhpC/alum and mAhpC/alum conferred protection against infection in 55% and 77.3% of mice, respectively. Mucosal immunization with AhpC/cholera toxin did not protect against infection and elicited low levels of serum IgG in comparison with systemic immunization. These data support the use of AhpC as a potential vaccine candidate against H. pylori infection.

Mouse models of Helicobacter-induced gastric cancer: use of cocarcinogens

The human pathogen Helicobacter pylori causes inflammation in the stomach of infected hosts, leading in some cases to the development of gastric cancer. Several mouse models have been developed to study Helicobacter-induced carcinogenesis with similarities to gastric adenocarcinoma and mucosa-associated lymphoid tissue lymphoma (MALToma) in humans. These models require chronic infection of animals with mouse-colonizing isolates of H. pylori or with related gastric Helicobacter spp., such as the canine/feline species Helicobacter felis. Furthermore, consistent with the known influence of host and environmental factors in human gastric cancer, it is possible to manipulate the type and severity of gastric lesions in mouse Helicobacter infection models through the use of different mouse genetic backgrounds and/or by the administration of known cocarcinogens, such as alkylating agents (e.g., N-nitroso-N-methylurea), or even elevated quantities of dietary salt. Here, we describe protocols for the inoculation of mice with gastric Helicobacter spp. and the administration of these cocarcinogens. Furthermore, we will describe the various methodologies used to study gastric inflammation and carcinogenesis in Helicobacter-infected animals.

Helicobacter pylori and type 1 diabetes mellitus: possibility of modifying chronic disease susceptibility with vaccinomics at the anvil

The human gastric pathogen, Helicobacter pylori, colonizes more than 50% of the world population and is a well-known cause of peptic ulcer disease. H. pylori has been epidemiologically linked to various other diseases, among which its putative link with certain complex diseases such as type 1 diabetes mellitus (T1DM) is of interest. Although antibiotic resistance is a significant clinical problem in H. pylori infection control, the exact cause and much of the underlying mechanisms of T1DM are not clearly understood. In addition, commensal microflora, gut-adapted microbial communities, and plausible roles of some of the chronic human pathogens add an important dimension to the control of T1DM. Given this, the present review attempts to analyze and examine the confounding association of H. pylori and T1DM and the approaches to tackle them, and how the emerging field of vaccinomics might help in this pursuit.

Antigenic diversity among Portuguese clinical isolates of Helicobacter pylori

BACKGROUND

 The human gastroduodenal pathogen, Helicobacter pylori, is characterized by an unusual extent of genetic heterogeneity. This dictates differences in the antigenic pattern of strains resulting in heterogeneous human humoral immune responses. Here, we examined the antigenic variability among a group of 10 strains isolated from Portuguese patients differing in age, gender, and H. pylori-associated gastric diseases.

MATERIAL AND METHODS

 Immunoassays were performed on two-dimensional electrophoresis gels obtained for the proteome of each strain, using a commercial pool of antibodies produced in rabbit, against the whole cell lysate of an Australian H. pylori strain. Relevant proteins were identified by mass spectrometry.

RESULTS

Immunoproteomes of the Portuguese strains showed no correlation between the number of antigenic proteins or the antigenic profile, and the disease to which each strain was associated. The Heat shock protein B was the unique immunoreactive protein common to all of them. Additionally, seven proteins were found to be antigenic in at least 80% of strains: enoyl-(acyl-carrier-protein) reductase (NADH); Catalase; Flagellin A; 2 isoforms of alkyl hydroperoxide reductase; succinyl-CoA transferase subunit B; and an unidentified protein. These proteins were present in the proteome of all tested strains, suggesting that differences in their antigenicity are related to antigenic variance.

CONCLUSIONS

 This study showed evidence of the variability of antigenic pattern among H. pylori strains. We believe that this fact contributes to the failure of anti-H. pylori vaccines and the low accuracy of serological tests based on a low number of proteins or antigens of only one strain.

Vaccinating against Helicobacter pylori infection

Helicobacter pylori infection of the gastric mucosa remains a cause of significant morbidity and mortality almost 30 years after its discovery. H. pylori infection can lead to several gastric maladies, including gastric cancer, and although antimicrobial therapies for the infection exist, the cost of treatment for gastric cancer and the prognosis of individuals who present with this disease make vaccine development a cost effective alternative to bacterial eradication. Experimental mucosal and systemic H. pylori vaccines in mice significantly reduce bacterial load and sometimes provide sterilizing immunity. Clinical trials of oral vaccines consisting of H. pylori proteins with bacterial exotoxin adjuvants or live attenuated bacterial vectors expressing H. pylori proteins induce adaptive immune mechanisms but fail to consistently reduce bacterial load. Clinical trials and murine studies demonstrate that where H. pylori is killed, either spontaneously or following vaccination, the host demonstrated cellular immunity. Improved efficacy of vaccines may be achieved in new trials of vaccine formulations that include multiple antigens and use methods to optimize cellular immunity. Unfortunately, the industrial sponsors that served as the primary engine for much of the previous animal and human research have withdrawn their support. A renewed or expanded commitment from the biotechnology or pharmaceutical industry that could exploit recent advances in our understanding of the host immune response to H. pylori is necessary for the advancement of an H. pylori vaccine.

Role of heat shock proteins in diseases and their therapeutic potential

Heat shock proteins are ubiquitously expressed intracellular proteins and act as molecular chaperones in processes like protein folding and protein trafficking between different intracellular compartments. They are induced during stress conditions like oxidative stress, nutritional deficiencies and radiation. They are released into extracellular compartment during necrosis. However, recent research findings highlights that, they are not solely present in cytoplasm, but also released into extracellular compartment during normal conditions and even in the absence of necrosis. When present in extracellular compartment, they have been shown to perform various functions like antigen presentation, intercellular signaling and induction of pro-inflammatory cytokines. Heat shock proteins represents as dominant microbial antigens during infection. The phylogenetic similarity between prokaryotic and eukaryotic heat shock proteins has led to proposition that, microbial heat shock proteins can induce self reactivity to host heat shock proteins and result in autoimmune diseases. The self-reactivity of heat shock proteins protects host against disease by controlling induction and release of pro-inflammatory cytokines. However, antibodies to self heat shock proteins haven been implicated in pathogenesis of autoimmune diseases like arthritis and atherosclerosis. Some heat shock proteins are potent inducers of innate and adaptive immunity. They activate dendritic cells and natural killer cells through toll-like receptors, CD14 and CD91. They play an important role in MHC-antigen processing and presentation. These immune effector functions of heat shock proteins are being exploited them as therapeutic agents as well as therapeutic targets for various infectious diseases and cancers.