Immune response against a cross-reactive epitope on the heat shock protein 60 homologue of Helicobacter pylori

Causal relationships of Helicobacter pylori and related gastrointestinal diseases on Type 2 diabetes: Univariable and Multivariable Mendelian randomization

BACKGROUND

Previous observational studies have demonstrated a connection between the risk of Type 2 diabetes mellitus (T2DM) and gastrointestinal problems brought on by Helicobacter pylori (H. pylori) infection. However, little is understood about how these factors impact on T2DM.

METHOD

This study used data from the GWAS database on H. pylori antibodies, gastroduodenal ulcers, chronic gastritis, gastric cancer, T2DM and information on potential mediators: obesity, glycosylated hemoglobin (HbA1c) and blood glucose levels. Using univariate Mendelian randomization (MR) and multivariate MR (MVMR) analyses to evaluate the relationship between H. pylori and associated gastrointestinal diseases with the risk of developing of T2DM and explore the presence of mediators to ascertain the probable mechanisms.

RESULTS

Genetic evidence suggests that H. pylori IgG antibody (P = 0.006, b = 0.0945, OR = 1.0995, 95% CI = 1.023-1.176), H. pylori GroEL antibody (P = 0.028, OR = 1.033, 95% CI = 1.004-1.064), gastroduodenal ulcers (P = 0.019, OR = 1.036, 95% CI = 1.006-1.068) and chronic gastritis (P = 0.005, OR = 1.042, 95% CI = 1.012-1.074) are all linked to an increased risk of T2DM, additionally, H. pylori IgG antibody is associated with obesity (P = 0.034, OR = 1.03, 95% CI = 1.002-1.055). The results of MVMR showed that the pathogenic relationship between H. pylori GroEL antibody and gastroduodenal ulcer in T2DM is mediated by blood glucose level and obesity, respectively.

CONCLUSION

Our study found that H. pylori IgG antibody, H. pylori GroEL antibody, gastroduodenal ulcer and chronic gastritis are all related to t T2DM, and blood glucose level and obesity mediate the development of H. pylori GroEL antibody and gastroduodenal ulcer on T2DM, respectively. These findings may inform new prevention and intervention strategies for T2DM.

Recombinant L. lactis vaccine LL-plSAM-WAE targeting four virulence factors provides mucosal immunity against H. pylori infection

BACKGROUND

Helicobacter pylori (H. pylori) causes chronic gastric disease. An efficient oral vaccine would be mucosa-targeted and offer defense against colonization of invasive infection in the digestive system. Proteolytic enzymes and acidic environment in the gastrointestinal tract (GT) can, however, reduce the effectiveness of oral vaccinations. For the creation of an edible vaccine, L. lactis has been proposed as a means of delivering vaccine antigens.

RESULTS

We developed a plSAM (pNZ8148-SAM) that expresses a multiepitope vaccine antigen SAM-WAE containing Urease, HpaA, HSP60, and NAP extracellularly (named LL-plSAM-WAE) to increase the efficacy of oral vaccinations. We then investigated the immunogenicity of LL-plSAM-WAE in Balb/c mice. Mice that received LL-plSAM-WAE or SAM-WAE with adjuvant showed increased levels of antibodies against H. pylori, including IgG and sIgA, and resulted in significant reductions in H. pylori colonization. Furthermore, we show that SAM-WAE and LL-plSAM-WAE improved the capacity to target the vaccine to M cells.

CONCLUSIONS

These findings suggest that recombinant L. lactis could be a promising oral mucosa vaccination for preventing H. pylori infection.

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

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

Causal associations of circulating Helicobacter pylori antibodies with stroke and the mediating role of inflammation

BACKGROUND

Observational studies have shown that Helicobacter pylori (H. pylori) infection and H. pylori antibodies are associated with an increased risk of stroke. However, which and how H. pylori antibodies serve as the causal determinant of the development of stroke remains largely unknown.

METHODS

Genome-wide association studies (GWAS) on seven different antibodies of H. pylori-specific proteins, stroke, and stroke subtypes were included in this study. Mendelian randomization (MR) and multivariable MR (MVMR) analysis were performed to assess the causal associations between H. pylori antibodies and the development of stroke and to determine the potential mechanisms underlying the associations.

RESULTS

Genetically predicted serum H. pylori vacuolating cytotoxin-A (VacA) antibody level was associated with an increased risk of all-cause stroke (odds ratio [OR] = 1.04, 95% CI 1.01-1.07, P = 0.017) and cardioembolic stroke (CES, OR = 1.11, 95% CI 1.04-1.18, P = 0.001). The results of multivariable MR (MVMR) showed that C-reactive protein (CRP), but not monocyte chemoattractant protein-1 and peptic ulcer, mediated the causal effects of VacA-positive H. pylori infection on all-cause stroke and CES. No strong causal associations were found between other H. pylori antibodies and stroke and its subtypes.

CONCLUSIONS

Our results demonstrate that H. pylori VacA antibody is the only causal determinant associated with the risk of stroke in the spectrum of H. pylori-related antibodies, in which CRP may mediate the association. This study suggests that inhibition of the CRP signaling pathway may reduce the risk of stroke in patients with VacA-positive H. pylori infection.

Mechanistic Insight Into the Interaction Between Helicobacter pylori Urease Subunit α and Its Molecular Chaperone Hsp60

Helicobacter pylori is the etiologic agent in a variety of gastroduodenal diseases. As its key pathogenic factors, both urease and Hsp60 play important roles in the pathogenesis of H. pylori. Previous studies have suggested that there is close relationship between urease and Hsp60, which implied that Hsp60 may act as a chaperone in urease stabilization and assembly. However, how these two proteins interact remains unclear. In this study, the impact of Hsp60 on urease activity of H. pylori lysate was first detected to confirm the interaction between urease and Hsp60. Pull-down assays further indicated that Hsp60 could bind to UreA subunit but not UreB. Then, the 3D structure of Hsp60 was modeled using I-TASSER to simulate the binding complex with UreA by molecular docking. The results showed that UreA is a perfect fit for the cavity of Hsp60. Analysis of the resulting model demonstrated that at least seven residues of UreA, located on two interfaces, participate in the interaction. Site-directed mutagenesis of these potential residues showed reduced affinity with Hsp60 than the wild type UreA through surface plasmon resonance (SPR) experiments, and D68 appears to have an important role in the affinity. Further analysis also showed that mutation of E25 and K26 caused a more rapid association and dissociation than with wild UreA, implying that they have roles in stabilizing the interaction complex. These affinity comparisons suggested that the interfaces predicted by molecular docking are credible. Our study indicated a direct interaction between Hsp60 and urease and revealed the binding interfaces and key residues involved in the interaction. These results provide further evidence for the chaperone activity of Hsp60 toward urease and lay a foundation to better understand the maturation mechanism of urease in H. pylori.

The evaluation of immunogenic impact of selected bacterial, recombinant Hsp60 antigens in DBA/2J mice

Heat Shock Proteins (HSP) are highly conserved proteins that are widely spread throughout all organisms. They function in the cytoplasm as chaperones; however, they could be expressed on the cell surface. It has been shown that Hsp60 obtained from gram-negative bacteria are able to stimulate cells of the acquired and innate immune system. The aim of this study was the evaluation of the immunogenic properties of recombinant Hsp60 proteins derived from four common pathogenic bacteria: Escherichia coli, Histophilus somni, Pasteurella multocida and Salmonella Enteritidis. The analysis of the humoral immune response in DBA/2J mice hyperimmunized with selected rHsp60 revealed high levels of IgG rHsp60-antibody with the predominance of the IgG₁ subclass, in the reaction with both homologous and heterologous antigens. The presence of IgG_2a and IgG_2b was also observed; however, no antibodies of subclass IgG₃ were detected. The comparison of plasma IgG antibody reactivity of mice immunized with two different doses of rHsp60 (10/20 μg) showed that the lower dose was sufficient to induce a strong humoral response. The reactivity of the IgG rHsp60-antibody with whole bacterial cells showed a significantly higher reaction with H. somni compared with other pathogens. It was demonstrated that the addition of all rHsp60 with polymyxin B to the culture medium stimulated splenocytes isolated from hyperimmunized mice to release IL-1β and IL-6. As a strong stimulator of the immune system, bacterial-origin Hsp60 seems to be an interesting potential component of subunit vaccines aimed at the development of protection for animals during infections caused by gram-negative bacteria.

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

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

Current views of the relationship between Helicobacter pylori and Henoch-Schonlein purpura in children

Helicobacter pylori (H. pylori) is one of the factors involved in the pathogenesis of various gastrointestinal diseases and may play a potential role in certain extra-intestinal diseases. H. pylori infection are mainly acquired during childhood, and it has been reported that in endemic areas of China the infection rates are extraordinarily higher in HSP children, particular those with abdominal manifestations. Furthermore, eradication therapy may ameliorate Henoch-Schonlein purpura (HSP) manifestations and decrease the recurrence of HSP. Therefore, results suggested that detection of H. pylori infection by appropriate method ought to be applied in HSP children. Current evidences indicate that local injury of gastric mucosa and immunological events induced by H. pylori infection are involved in the development of HSP. Increased serum IgA, cryoglobulins, C3 levels, autoimmunity, proinflammatory substances and molecular mimicry inducing immune complex and cross-reactive antibodies caused by H. pylori infection might play their roles in the course of HSP. However, there are no investigations confirming the causality between H. pylori infection and HSP, and the pathogenesis mechanism is still unclear. More bench and clinical studies need to be executed to elaborate the complex association between H. pylori and HSP.

B-cell epitopes in GroEL of Francisella tularensis

The chaperonin protein GroEL, also known as heat shock protein 60 (Hsp60), is a prominent antigen in the human and mouse antibody response to the facultative intracellular bacterium Francisella tularensis (Ft), the causative agent of tularemia. In addition to its presumed cytoplasmic location, FtGroEL has been reported to be a potential component of the bacterial surface and to be released from the bacteria. In the current study, 13 IgG2a and one IgG3 mouse monoclonal antibodies (mAbs) specific for FtGroEL were classified into eleven unique groups based on shared VH-VL germline genes, and seven crossblocking profiles revealing at least three non-overlapping epitope areas in competition ELISA. In a mouse model of respiratory tularemia with the highly pathogenic Ft type A strain SchuS4, the Ab64 and N200 IgG2a mAbs, which block each other’s binding to and are sensitive to the same two point mutations in FtGroEL, reduced bacterial burden indicating that they target protective GroEL B-cell epitopes. The Ab64 and N200 epitopes, as well as those of three other mAbs with different crossblocking profiles, Ab53, N3, and N30, were mapped by hydrogen/deuterium exchange–mass spectrometry (DXMS) and visualized on a homology model of FtGroEL. This model was further supported by its experimentally-validated computational docking to the X-ray crystal structures of Ab64 and Ab53 Fabs. The structural analysis and DXMS profiles of the Ab64 and N200 mAbs suggest that their protective effects may be due to induction or stabilization of a conformational change in FtGroEL.

Common antigens prediction in bacterial bioweapons: a perspective for vaccine design

Bioweapons (BWs) are a serious threat to mankind and the lack of efficient vaccines against bacterial bioweapons (BBWs) further worsens the situation in face of BW attack. Experts believe that difficulties in detection and ease in dissemination of deadly pathogens make BW a better option for attack compared to nuclear weapons. Molecular biology techniques facilitate the use of genetically modified BBWs thus creating uncertainty on which bacteria will be used for BW attack. In the present work, available resources such as proteomic sequences of BBWs, protective antigenic proteins (PAPs) reported in Protegen database and VaxiJen dataset, and immunogenic epitopes in immune epitope database (IEDB) were used to predict potential broad-specific vaccine candidates against BBWs. Comparison of proteomes sequences of BBWs and their analyses using in-house PERL scripts identified 44 conserved proteins and many of them were known to be immunogenic. Comparison of conserved proteins against PAPs identified six either as PAPs or their homologues with a potential of providing protection against multiple pathogens. Similarly, mapping of conserved proteins against experimentally known IEDB epitopes identified six epitopes which had exact epitope match in four proteins including three from earlier predicted six PAPs. These epitopes were also reported to provide protection against several pathogens. In the backdrop of conserved heat shock GroEL protein from Salmonella enterica providing protection against five diverse bacterial pathogens involved in different diseases, and synthetic proteins produced by combination of epitopes from Mycobacterium tuberculosis and 4 viruses providing protection against both bacterium and viruses, the identified putative immunogenic conserved proteins and immune-protective epitopes can further be explored for their potential as broad-specific vaccine candidates against BBWs.

Helicobacter pylori antibody responses and evolution of precancerous gastric lesions in a Chinese population

Helicobacter pylori-specific proteins are involved in gastric carcinogenesis. To investigate the seroprevalence of six H. pylori-specific antibodies in patients with different gastric histology, and the impact of seropositivities on the evolution of precancerous gastric lesions, a follow-up study was conducted in Linqu County, China. The seropositivities for CagA, VacA, GroEL, UreA, HcpC and gGT were assessed by recomLine analysis in 573 H. pylori-positive subjects and correlated with evolution of precancerous gastric lesions. We found that the score of H. pylori recomLine test was significantly increased in subjects with chronic atrophic gastritis (CAG, p < 0.0001) or intestinal metaplasia (IM, p = 0.0125), and CagA was an independent predictor of advanced gastric lesions, adjusted odds ratios (ORs) were 2.54 (95% CI = 1.42-4.55) for IM and 2.38 (95% CI = 1.05-5.37) for dysplasia (DYS). Moreover, seropositivities for CagA and GroEL were identified as independent predictors for progression of gastric lesions in a longitudinal study, and ORs were 2.89 (95% CI = 1.27-6.59) and 2.20 (95% CI = 1.33-3.64), respectively. Furthermore, the risk of progression was more pronounced in subjects with more than three positive antigens (p(for) trend = 0.0003). This population-based study revealed that seropositivities for CagA and GroEL might be potential markers to identify patients infected with high-risk H. pylori strains, which are related to the development of GC in a Chinese high-risk population, and recomLine test might serve as a tool for risk stratification.

Immunoproteomics: the key to discovery of new vaccine antigens against bacterial respiratory infections

The increase in antibiotic resistance and the shortage of new antimicrobials to prevent difficult bacterial infections underlines the importance of prophylactic therapies to prevent infection by bacterial pathogens. Vaccination has reduced the incidence of many serious diseases, including respiratory bacterial infections. However, there are many pathogens for which no vaccine is available and some vaccines are not effective among all age groups or among immunocompromised individuals. Immunoproteomics is a powerful technique which has been used to identify potential vaccine candidates to protect against pathogenic bacteria. The combination of proteomics with the detection of immunoreactive antigens using serum highlights immunogenic proteins that are expressed during infection. This is particularly useful when patient serum is used as the antigens that promote a humoral response during human infection are identified. This review outlines examples of vaccine candidates that have been identified using immunoproteomics and have successfully protected animals against challenge when tested in immunisation studies. Many immunoreactive proteins are common to several unrelated pathogens, however some of these are not always protective in animal immunisation and challenge studies. Furthermore, examples of well-established immunogens, including Bordetella pertussis antigen FHA were not detected in immunoproteomics studies, indicating that this technology may underrepresent the immunoreactive proteins in a pathogen. Although only one step in the pathway towards an efficacious approved vaccine, immunoproteomics is an important technology in the identification of novel vaccine antigens.

Is Helicobacter pylori infection associated with Henoch-Schonlein purpura in Chinese children? a meta-analysis

BACKGROUND

The prevalence of Helicobacter pylori (H. pylori) infection is high in China. It not only causes the damage of gastric epithelium, but also plays a potential pathogenic role in several extraintestinal diseases. Henoch-Schonlein purpura (HSP) is one of the most common vasculitis syndromes affecting children. Although its cause is unclear, HSP is often considered to be associated with infectious agents. This metaanalysis of previously published studies was conducted using a predefined protocol to evaluate the underlying association between H. pylori infection and HSP in Chinese children.

METHODS

Predefined search strategy and inclusion criteria were set up to select studies reporting the prevalence of H. pylori infection among HSP children and control groups. Included studies were subjected to quality assessment and data extraction by two independent reviewers. The pooled odds ratio (OR) was calculated as the effect size via both traditional and cumulative meta-analysis. Heterogeneity was investigated by subgroup analysis, and the nonparametric "trim and fill" method was performed to adjust the overall estimate for the existence of publication bias.

RESULTS

Ten eligible studies covering 749 HSP children and 560 controls were included for metaanalysis. Observational epidemiology studies clearly aimed at detecting the potential association between H. pylori infection and HSP with retrospective data collection from the children enrolled consecutively. Overall, 49.27% (369/749) of HSP children had evidence of H. pylori infection compared with 23.39% (131/560) of children in the control group. The pooled OR of H. pylori infection in HSP children (10 studies with 749 HSP children) was 3.80 [95% confidence interval (CI): 2.54-5.68, P<0.001], and the overall estimate from the cumulative meta-analysis confirmed the association with more narrow confidence interval (OR=3.35, 95% CI: 2.95-3.81). In HSP children mainly with abdominal manifestations (8 studies with 337 HSP children), the pooled OR was 4.62 (95% CI: 2.66-8.01, P<0.001). The adjusted pooled OR was 2.04 (95% CI: 1.48-2.82, P<0.001), determined by the nonparametric "trim-andfill" method for eliminating the effect of publication bias. H. pylori eradication therapy (4 studies with 266 HSP children) was capable of reducing the recurrence of HSP (RR=0.38, 95% CI: 0.25-0.58, P<0.001). Although the subgroup analysis for heterogeneity suggested that diagnostic methods and geographical diversity might be account for the heterogeneity, statistical analysis of differences revealed no differences between subgroups, indicating their limited impact on the overall estimates.

CONCLUSIONS

These results suggest the necessity of screening H. pylori infection in HSP children, particularly in those with gastrointestinal manifestations in China. Eradication therapy may reduce the recurrence of HSP in children with H. pylori infection. However, further mechanistic and more clinical studies in different populations and regions are needed to confirm this association and the effect of eradication of H. pylori in HSP children.

Comparison of epitope specificity of anti-heat shock protein 60/65 IgG type antibodies in the sera of healthy subjects, patients with coronary heart disease and inflammatory bowel disease

Previously, we reported on the presence of antibodies to linear epitopes of human and mycobacterial 60 kD heat shock proteins (HSP) in the sera of healthy blood donors. Since many recent findings indicate that the levels of these antibodies may be altered in coronary heart disease (CHD) and also inflammatory bowel diseases (IBD), it seemed worthwhile to compare the epitope specificity of the anti-HSP60 and anti-HSP65 antibodies in the sera of patients with these diseases to those in healthy subjects. The multipin enzyme-linked immunosorbent assay method was applied with a large overlapping set of synthetic 10-mer peptides covering selected regions of human HSP60 and Mycobacterium bovis HSP65. Sera of 12 healthy persons (HP), 14 CHD, and 14 IBD patients with the same concentration of total anti-HSP60 and HSP65 IgG antibodies were tested. We have identified CHD-specific epitopes in the equatorial domain of the HSP60 protein but in neither region of the HSP65 molecule, indicating that the formation of anti-HSP60 antibodies is not or only partially due to the cross-reaction between human HSP60 and bacterial HSP65. IBD-specific epitopes were found in many regions of the HSP60 and in even more regions of the HSP65 molecule including an IBD-specific T cell epitope in region X as well. These findings indicate that the epitope specificity of the anti-human and anti-mycobacterial HSP60 antibodies associated with various diseases is different.

In vitro and in vivo effects of the Mongolian drug Amu-ru 7 on Helicobacter pylori growth and viability

Amu-ru 7, a Mongolian folk medicine, is used to treat digestive diseases such as gastritis and gastric and duodenal ulcers. We examined the effect of Amu-ru 7 on the growth and viability of Helicobacter pylori in vivo and in vitro. By the agar dilution method, the MIC of Amu-ru 7 for H. pylori strains was shown to be 100-200 μg/mL with a MIC(90) of 200 μg/mL. Two hundred micrograms per milliliter of Amu-ru 7 exhibited potent bactericidal activity against H. pylori in the stationary phase of growth 6 hr after treatment. Amu-ru 7 inhibited the growth of both AMPC-resistant and CAM-resistant strains, and also had a combined effect with AMPC on AMPC-resistant strain 403. The Amu-ru 7 inhibited biofilm formation by H. pylori and induced morphological changes, such as bleb-like formation and shortening of the cell. Although colonization of the stomach of the Mongolian gerbil by H. pylori was not cured by treatment with Amu-ru 7, both the mean number of H. pylori colonized and the colonization rate were decreased in Amu-ru 7 treated gerbils. These results suggest the effectiveness Amu-ru 7 as an adjunct therapy for eradication therapies consisting of a PPI combined with antibiotics.

Autoimmunity, infectious immunity, and atherosclerosis

INTRODUCTION

Vascular inflammation is common in certain systemic autoimmune diseases and contributes to the oxidation of low-density lipoprotein (oxLDL) and oxLDL/beta2-glycoprotein I (beta2GPI) complex formation. These complexes have been implicated as proatherogenic autoantigens that participate in the development of atherosclerotic disease.

DISCUSSION

We have demonstrated that the in vitro macrophage uptake of oxLDL/beta2GPI complexes increases in the presence of IgG anti-beta2GPI antibodies and that IgG immune complexes containing oxLDL/beta2GPI upregulate the expression of both scavenger and Fcgamma receptors to activate beta2GPI specific T cells. Some persistent infections may cause immune responses that promote atherogenesis. Cellular immunity (Th1) against Helicobacter pylori (H. pylori) derived heat shock protein 60 (Hp-HSP60) cross-reacts with endogenous HSP60 to cause cardiovascular disease likely by molecular mimicry.

CONCLUSION

Infectious cellular response may be proatherogenic,while the humoral response (antibody production) maybe protective. We review the recent progress in our understanding of autoimmunity and infectious immunity that promote atherosclerosis.

Regulation of cellular immunity prevents Helicobacter pylori-induced atherosclerosis

Helicobacter pylori (H. pylori) is a predominant pathogen that causes not only gastroduodenal diseases but also extra-alimentary tract diseases. In this study, we demonstrated that H. pylori infection promoted atherogenesis in heterozygous apoe(+/ --) ldlr(+/--) mice. The male mice were fed with high fat diet from the age of 6 weeks. At the age of 16 weeks, development of atherosclerotic lesions was observed in the H. pylori-infected mice, and it seemed to be associated with an elevation of Th1-immune response against H. pylori origin-heat shock protein 60 (Hp-HSP60) and an increment of transendothelial migration of T cells. Subcutaneous immunisation with Hp-HSP60 or H. pylori eradication with antibiotics significantly reduced the progression of atherosclerosis, accompanied by a decline of Th1 differentiation and reduction of their chemotaxis beyond the endothelium. Thus, oral infection with H. pylori accelerates atherosclerosis in mice and the active immunisation with Hp-HSP60 or the eradication of H. pylori with antibiotics can moderate/prevent cellular immunity, resulting in a reduction of atherosclerosis.

Efficacy of passive immunization with IgY antibodies to a 58-kDa H. pylori antigen on severe gastritis in BALB/c mouse model

Consecutive triple doses of 1 x 10(8) CFU/mL of a pathogenic H. pylori strain isolated from stomach of Egyptian patients with severe gastritis were used to establish infection in BALB/c mice model. White Leghorn hens were immunized with H. pylori whole cell lysate (HpLysate) antigen and with a highly reactive 58-kDa H. pylori (Hp58) antigen. Two months later, IgY antibodies (IgY-HpLysate & IgY-Hp58) were purified from egg yolk and its efficacy was evaluated in the adopted model. Microbiological culture and immunohistochemical staining revealed that H. pylori infection was inhibited 1 week after oral passive immunization in 70% of infected BALB/c mice with a significant decrease (p < 0.05) in the degrees of gastritis. In conclusion, we have adapted BALB/c mice model for human H. pylori pathogenic strain and oral passive immunization with specific IgY antibodies to the 58-kDa antigen inhibited active H. pylori infection and decreased gastritis.

Protective immunization with homologous and heterologous antigens against Helicobacter suis challenge in a mouse model

Helicobacter (H.) suis colonizes the stomach of more than 60% of slaughter pigs and is also of zoonotic importance. Recently, this bacterium was isolated in vitro, enabling the use of pure cultures for research purposes. In this study, mice were immunized intranasally or subcutaneously with whole bacterial cell lysate of H. suis or the closely related species H. bizzozeronii and H. cynogastricus, and subsequently challenged with H. suis. Control groups consisted of non-immunized and non-challenged mice (negative control group), as well as of sham-immunized mice that were inoculated with H. suis (positive control group). Urease tests on stomach tissue samples at 7 weeks after challenge infection were negative in all negative control mice, all intranasally immunized mice except one, and in all and 3 out of 5 animals of the H. cynogastricus and H. suis subcutaneously immunized groups, respectively. H. suis DNA was detected by PCR in the stomach of all positive control animals and all subcutaneously immunized/challenged animals. All negative control animals and some intranasally immunized/challenged mice were PCR-negative. In conclusion, immunization using antigens derived from the same or closely related bacterial species suppressed gastric colonization with H. suis, but complete protection was only achieved in a minority of animals following intranasal immunization.

Serum antibodies to Porphyromonas gingivalis chaperone HtpG predict health in periodontitis susceptible patients

Background

Chaperones are ubiquitous conserved proteins critical in stabilization of new proteins, repair/removal of defective proteins and immunodominant antigens in innate and adaptive immunity. Periodontal disease is a chronic inflammatory infection associated with infection by Porphyromonas gingivalis that culminates in the destruction of the supporting structures of the teeth. We previously reported studies of serum antibodies reactive with the human chaperone Hsp90 in gingivitis, a reversible form of gingival disease confined to the oral soft tissues. In those studies, antibodies were at their highest levels in subjects with the best oral health. We hypothesized that antibodies to the HSP90 homologue of P. gingivalis (HtpG) might be associated with protection/resistance against destructive periodontitis.

Methodology/Principal Findings

ELISA assays using cloned HtpG and peptide antigens confirmed gingivitis subjects colonized with P. gingivalis had higher serum levels of anti-HtpG and, concomitantly, lower levels of attachment loss. Additionally, serum antibody levels to P. gingivalis HtpG protein were higher in healthy subjects compared to patients with either chronic or aggressive periodontitis. We found a negative association between tooth attachment loss and anti-P. gingivalis HtpG (p = 0.043) but not anti-Fusobacterium nucleatum (an oral opportunistic commensal) HtpG levels. Furthermore, response to periodontal therapy was more successful in subjects having higher levels of anti-P. gingivalis HtpG before treatment (p = 0.018). There was no similar relationship to anti-F. nucleatum HtpG levels. Similar results were obtained when these experiments were repeated with a synthetic peptide of a region of P. gingivalis HtpG.

Conclusions/Significance

Our results suggest: 1) anti-P. gingivalis HtpG antibodies are protective and therefore predict health periodontitis-susceptable patients; 2) may augment the host defence to periodontitis and 3) a unique peptide of P. gingivalis HtpG offers significant potential as an effective diagnostic target and vaccine candidate. These results are compatible with a novel immune control mechanism unrelated to direct binding of bacteria.

Mutation of luxS affects motility and infectivity of Helicobacter pylori in gastric mucosa of a Mongolian gerbil model

Helicobacter pylori is associated with gastric disorders in humans and some experimental animals, and possesses the luxS/type 2 autoinducer (AI-2) system. The effects of a specific luxS mutation on the characteristics of H. pylori were examined. On 0.3 % agar medium, motility of H. pylori HPKY08 (luxS : : cat) was significantly lower than that of wild-type H. pylori TK1402. The luxS-complemented strain HPKY21 exhibited motility comparable to that of H. pylori TK1402. It was shown that the luxS/AI-2 system plays an important role in H. pylori motility. The luxS mutant exhibited a reduced infection rate relative to the wild-type parent strain TK1402 in a Mongolian gerbil model. At 3 months after oral inoculation, lower numbers of H. pylori were detected by semi-quantitative real-time reverse transcription PCR (qRT-PCR) in luxS(-) mutant-infected gerbils than in TK1402-infected gerbils. Gastric inflammation and increased antibody titre for H. pylori were observed in TK1402-infected gerbils only.

Long-term infection of Mongolian gerbils with Helicobacter pylori: microbiological, histopathological, and serological analyses

The effects of long-term infection with Helicobacter pylori on the gastric mucosa of Mongolian gerbils were examined. Colonization by H. pylori was evaluated by both microaerobic cultivation and real-time reverse transcriptase PCR (RT-PCR). Persistent infection with H. pylori in gastric mucosa was detected by real-time RT-PCR during 6 months after infection, but no H. pylori was isolated 4 months after infection by cultivation. Infiltration with neutrophils and mononuclear cells was observed from 2 months after infection. Both intestinal metaplasia and gastric atrophy were also detected from 2 months after infection. The results by enzyme-linked immunosorbent assay indicated that antibody titers against whole H. pylori antigens, H. pylori heat shock protein 60 (HSP60), and Escherichia coli GroEL were significantly higher in the infected gerbils than in noninfected gerbils. After long-term infection with H. pylori for 18 months, marked atrophy of gastric mucosa and multiple cysts in the submucosa were observed in the glandular stomach of the infected gerbils. In addition, squamous cell papilloma with hyperkeratosis was observed in cardia of all the infected gerbils. These results indicate that evaluation of bacterial colonization during long-term infection can be done by real-time RT-PCR and that mucosal damage might be induced by host immune response against whole H. pylori antigen.

Human peripheral and gastric lymphocyte responses to Helicobacter pylori NapA and AphC differ in infected and uninfected individuals

BACKGROUND

In this study, we identify the nature of the immunological response of human peripheral blood mononuclear cells (PBMC) and lamina propria gastric lymphocytes (LPL) to two Helicobacter pylori antigens, the neutrophil activating protein (NapA) and alkyl hydroperoxide reductase (AphC). These antigens were identified and selected for study based on the observation that serological recognition of these proteins was associated with H pylori negative status in humans.

AIMS

The aim was to study the serological, proliferative, and cytokine responses of PBMC and LPL, obtained from H pylori infected and uninfected individuals, to these antigens.

METHODS

Patient serum, PBMC, and LPL were used to determine antibody isotype, and proliferative and cytokine responses to recombinant forms of NapA and AphC using western blotting and ELISA.

RESULTS

Western blotting revealed antibody reactivity to recombinant NapA and AphC among the H pylori negative population studied. Both the proliferative and interferon gamma responses of PBMC and LPL to NapA and AphC were significantly higher in H pylori negative compared with H pylori positive subjects. Analysis of the IgG subclass profiles to both antigens revealed a T helper 1 associated IgG3 antibody response in uninfected individuals. However, interleukin 10 production was greater in H pylori positive individuals in response to these antigens.

CONCLUSIONS

Taken together these data are consistent with an immune response to these antigens skewed towards a T helper 1 response in the uninfected cohort.

Effect of dietary anti-Helicobacter pylori-urease immunoglobulin Y on Helicobacter pylori infection

Recently, chicken egg yolk was recognized as an inexpensive antibody source, and the therapeutic usefulness of egg yolk immunoglobulin Y (IgY) in oral passive immunization has been investigated. Although multiple antibiotic treatments eradicate most Helicobacter pylori (H. pylori) infections, therapy fails in 10-15% of cases due to the development of drug resistance. Consequently, it is important that new, more broadly based therapies for the treatment of H. pylori infection should be identified. The present study evaluated the effect, on H. pylori infection, of IgY prepared from egg yolk of hens immunized with H. pylori urease (anti-HpU IgY). Seventeen asymptomatic volunteers diagnosed as H. pylori-positive by the 13C-urea breath test (UBT) were orally administered anti-HpU IgY for 4 weeks. Four weeks later, UBT values were significantly decreased although no case showed H. pylori eradication. An H. pylori-positive 53-year-old female gastritis patient administered anti-HpU IgY plus lansoprazole for 8 weeks showed a decrease in serum pepsinogen (PG) I and UBT values as well as an increase in the PG I/II ratio. In conclusion, anti-HpU IgY may mitigate H. pylori-associated gastritis and partially attenuate gastric urease activity. Furthermore, anti-HpU IgY combined with antacids appears to ameliorate gastric inflammation. These encouraging results may represent a novel approach to the management of H. pylori-associated gastroduodenal disease.

Identification of candidate antigens for serologic detection of Helicobacter pylori-infected patients with gastric carcinoma

Helicobacter pylori colonizes the stomach of almost half the world population and is a causative agent of gastric carcinomas and duodenal ulcers. Only a small fraction of infected people will develop these severe illnesses and a predictive test to identify people at high risk would greatly benefit disease management. Our study aimed to identify conserved bacterial antigens that may be useful for the development of such a diagnostic test. High-resolution immunoproteomics by 2-dimensional electrophoresis of H. pylori 26695 proteins was carried out with sera from infected patients with either duodenal ulcer (n=30) or gastric carcinoma (n=30), 2 clinically divergent conditions. According to their antigen recognition patterns clear groups of patients were identified. Although this classification did not correspond to the clinical status, it may be correlated to other bacterial or host factors that influence the outcome of infection. In general antigen recognition patterns were found to be highly variable, however by utilizing powerful image analysis and statistical tests the recognition of 14 antigenic protein species was found to differ significantly (p<0.01) between both diseases. Particular protein species of GroEL, HyuA, GroES and AtpA appear to be useful surrogate markers for gastric carcinoma detection and consequently should be considered for further prospective studies to assess their predictive value. For one protein species of AtpA, evidence was found that different post-translational modifications may confer different immunogenicities.

Oral microbial heat-shock proteins and their potential contributions to infections

The oral cavity is a complex ecosystem in which several hundred microbial species normally cohabit harmoniously. However, under certain special conditions, the growth of some micro-organisms with a pathogenic potential is promoted, leading to infections such as dental caries, periodontal disease, and stomatitis. The physiology and pathogenic properties of micro-organisms are influenced by modifications in environmental conditions that lead to the synthesis of specific proteins known as the heat-shock proteins (HSPs). HSPs are families of highly conserved proteins whose main role is to allow micro-organisms to survive under stress conditions. HSPs act as molecular chaperones in the assembly and folding of proteins, and as proteases when damaged or toxic proteins have to be degraded. Several pathological functions have been associated with these proteins. Many HSPs of oral micro-organisms, particularly periodontopathogens, have been identified, and some of their properties-including location, cytotoxicity, and amino acid sequence homology with other HSPs-have been reported. Since these proteins are immunodominant antigens in many human pathogens, studies have recently focused on the potential contributions of HSPs to oral diseases. The cytotoxicity of some bacterial HSPs may contribute to tissue destruction, whereas the presence of common epitopes in host proteins and microbial HSPs may lead to autoimmune responses. Here, we review the current knowledge regarding HSPs produced by oral micro-organisms and discuss their possible contributions to the pathogenesis of oral infections.

Expression of Helicobacter pylori Hsp60 protein and its immunogenicity

AIM: To express Hsp60 protein of H pylori by a constructed vector and to evaluate its immunogenicity.

METHODS: Hsp60 DNA was amplified by PCR and inserted into the prokaryotie expression vector pET-22b (+), which was transformed into BL21 (DE3) E.coli strain to express recombinant protein. Immunogenicity of expressed Hsp60 protein was evaluated with animal experiments.

RESULTS: DNA sequence analysis showed Hsp60 DNA was the same as GenBank’s research. Hsp60 recombinant protein accounted for 27.2% of the total bacterial protein, and could be recognized by the serum from H pylori infected patients and Balb/c mice immunized with Hsp60 itself.

CONCLUSION: Hsp60 recombinant protein might become a potential vaccine for controlling and treating H pylori infection.

Effect of bacterial flora on postimmunization gastritis following oral vaccination of mice with Helicobacter pylori heat shock protein 60

In order to assess the efficacy of oral Helicobacter pylori heat shock protein 60 (HSP60) as a vaccine, protection against H. pylori infection in specific-pathogen-free (SPF) C57BL/6 and germfree (GF) IQI mice was examined. Prophylactic oral vaccination of these two strains of mice with either H. pylori HSP60 or Escherichia coli GroEL inhibited H. pylori colonization by 90 to 95% at 3 weeks postinfection (p.i.). However, these mice were only partially protected because bacterial loads increased in all animals at 10 weeks p.i. Anti-H. pylori HSP60 immunoglobulin G was detected in serum at 3 weeks p.i. in mice vaccinated with either H. pylori HSP60 or GroEL. Significant increases in the gastritis scores were observed only in SPF mice immunized with H. pylori HSP60. These results indicate that oral vaccination with H. pylori HSP60 has partial protective effects on subsequent H. pylori infection but also induces postimmunization gastritis. However, GF mice immunized with H. pylori HSP60 did not suffer from severe gastritis. Therefore, the presence of bacterial flora appears to contribute to the induction of postimmunization gastritis.

Surface localized Heat Shock Protein 20 (HslV) of Helicobacter pylori

BACKGROUND

Heat Shock Protein (HSP) has been regarded as a pathogenic factor in Helicobacter pylori infection. Heat Shock Protein 20 (HSP20) of H. pylori is identified as Hs1V based on open reading frame predication of genome sequences. It is a homologue of HslV of E. coli, a peptidase involved in protein degradation.

METHODS

The HSP20 gene was cloned and inserted into pET16b fused with His-tag. Recombinant HSP20 protein (rHSP20) was expressed and purified by nickel column. Rabbit anti-rHSP20 was purified by Protein A affinity chromatography and used as a probe to localize HSP20 in H. pylori by immuno-gold labeling and Western blotting. rHSP20 was also used as antigen to test for antibody against HSP20 in patients with H. pylori infection by enzyme-linked immunosorbant assay.

RESULTS

Immuno-gold labeled transmission electron microscopy shows that HSP20 is located on the cell surface of H. pylori. Western blotting of 2-D gel shows that HSP20 has a pI of approximately 5.5 and a molecular weight of approximately 18 kDa. The ELISA result shows that there is no significant difference in antibody titre against rHSP20 in all sera tested.

CONCLUSION

The presence of IgG to rHSP20 may imply an earlier exposure of the patients and normal subjects to H. pylori. However, the mechanism has not been established. HSP20 has been shown to localize on the surface of H. pylori. Surface localization of H. pylori HSP20 may provide the path to a better understanding of the role and function of HSP20 in bacteria-host interaction.

Construction of clone expressing adhesin Hsp60 of Helicobacter pylori

AIM

To construct a recombinant vector containing gene encoding Hsp60 gene of Helicobacter pylori and to express the vector in E.coli BL21.

METHODS

The Hsp60 gene was amplified from H.pylori chromosome by PCR and inserted into the prokaryotie expression vector pET-22b (+). The recombinant vector was transformed and expressed in E.coli BL21 (DE3). Recombinant Hsp60 protein immunogenicity was studied by Western blot.

RESULTS

The 1.6 kb Hsp60 gene was successfully isolated. Recombinant E.coli strains expressed Hsp60 were obtained, the expression protein amounted to 27.2% of the total bacterial protein after induced with IPTG for 3 h at 37 ℃, which included inclusion body and soluble protein. Inclusion body was the major pattern of the expression that amounted to 76.6% of the insoluble protein. Western blot analysis of rHsp60 confirmed that it could be specially recognized by serum from Hp infected patients.

CONCLUSION

The gene coding for Hp Hsp60 is cloned and expressed successfully. The results obtained lay the foundation for constructing the H.pylori vaccine.

Helicobacter pylori and Campylobacter rectus share a common antigen

AIM

The aim of this study was to investigate the presence of antigens with immunological cross-reactivity in periodontopathogenic bacteria and Helicobacter pylori, the pathogen associated with gastritis and peptic ulcers in human.

MATERIALS AND METHODS/RESULTS

Among the putative periodontopathogens tested (Actinobacillus actinomycetemcomitans, Campylobacter rectus, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia and Treponema denticola), cross-reactive bands were only detected in C. rectus by SDS-PAGE/Western immunoblotting analysis using a polyclonal antibody directed to H. pylori cells. One of these cross-reactive antigens, a 64-kDa band antigen, also reacted with a monoclonal antibody directed to the human heat shock protein (HSP) 60. The N-terminal amino acid sequence of this C. rectus protein revealed a high degree of homology with corresponding regions of other HSPs belonging to the HSP60 family, indicating that the 64-kDa antigen was a GroEL protein. The nucleotide sequence of the C. rectus GroEL protein coded for a 547 amino acid protein with a predicted size of 57.8 kDa. Comparison of the alignment of the deduced amino acid sequence of the GroEL protein of C. rectus with that of H. pylori showed a high degree of similarity throughout its length (76.8%). GroEL protein from C. rectus possessed the ability to stimulate production of IL-6 by a confluent monolayer of human gingival epithelial cells and was cytotoxic when used at a high concentration.

CONCLUSIONS

This study reveals an immunological relationship between H. pylori and C. rectus, and clearly indicates that one of the shared antigens is a GroEL protein possessing a biological activity that might play a role in the initiation and progression of periodontal disease.

Identification of immunodominant Helicobacter pylori proteins with reactivity to H. pylori-specific egg-yolk immunoglobulin

The importance of hens eggs as a source of specific antibodies (IgY) is well recognized. The protective effect of IgY obtained from hens immunized with Helicobacter pylori whole-cell lysate has been reported for the control of H. pylori infection. However, IgY produced by whole-cell lysates presents the possibility of cross-reactivity with other bacteria, including the normal human flora, and this could decrease the efficiency of IgY. In the present study, the immunodominant proteins of H. pylori with reactivity to H. pylori-specific IgY (IgY-Hp) were identified. IgY obtained from hens immunized with various fractions of H. pylori proteins was isolated and purified, titres of IgY-Hp against H. pylori were determined and cross-reactivity between IgY-Hp and normal human bacteria was examined by Western blot analysis. Finally, immunodominant H. pylori proteins were identified by LC/MS analysis. IgY obtained 2 months after immunization with H. pylori whole-cell lysate showed the highest antibody titre. Five immunodominant proteins were identified that were strongly reactive to IgY-Hp: urease beta-subunit (62 kDa), heat-shock protein 60 (60 kDa), urease alpha-subunit (26 kDa), probable peroxiredoxin (22 kDa) and probable thiol peroxidase (18 kDa). Immunization of hens with the immunodominant proteins identified would produce a more specific IgY against H. pylori.

Molecular and functional analysis of the Rickettsia typhi groESL operon

The groESL operon from an obligate, intracellular, Gram-negative bacterium Rickettsia typhi, the etiologic agent of murine typhus, was cloned and sequenced. The sequence analysis of 2229 bp of the groESL operon reveals two open reading frames of 288 nucleotides (groES) and 1653 nucleotides (groEL) separated by 20 nucleotides. The deduced amino acid sequence of R. typhi GroES and GroEL shows a high degree of identity with other bacterial GroES and GroEL. Reverse transcriptase-polymerase chain reaction and Northern blot analysis indicated that both groES and groEL are transcribed as a single mRNA. The transcriptional start point at 81 nucleotides upstream of the groES start codon was determined by primer extension. The promoter analysis shows no regulatory CIRCE element as it is known for many Gram-positive and Gram-negative bacteria. However, it contains the sequence similar to the putative sigma(70)-dependent promoter and lacks the -35 sequence of the putative sigma(32)-dependent promoter. Complementation assay by R. typhi groESL in a temperature sensitive Escherichia coli groEL mutant restored significant growth ability at non-permissive temperature.

Helicobacter pylori infection in connective tissue disorders is associated with high levels of antibodies to mycobacterial hsp65 but not to human hsp60

BACKGROUND

To investigate whether the Helicobacter pylori status influences levels of antibodies against mycobacterial heat shock protein (hsp) 65 and human hsp60 in systemic autoimmune diseases and to study the concentration of anti-H. pylori antibodies in autoimmune patients and healthy controls.

MATERIALS AND METHODS

Antibodies against human heat-shock protein hsp60, mycobacterial heat-shock protein hsp65 were analyzed by ELISA. Anti-Helicobacter antibodies were determined by enzyme immunoassay.

RESULTS

There was a markedly higher prevalence of H. pylori infection in undifferentiated connective tissue disease (82%) (n = 33) and systemic sclerosis (78%) (n = 55) but not in systemic lupus erythematosus (n = 49), polymyositis/dermatomyositis (n = 14), rheumatoid arthritis (n = 21) or primary Raynaud's syndrome (n = 26) compared with controls (59%) (n = 349). In autoimmune diseases H. pylori infection was associated with elevated levels of antihsp65 (p =.008) but not of antihsp60. Anti-hsp65 levels were significantly higher in H. pylori-infected (n = 129) than in uninfected patients (n = 69) (p =.0007).

CONCLUSIONS

These findings indicate that in autoimmune diseases the infection with the H. pylori bacterium is associated with increased concentration of antimycobacterial hsp65.

Clarithromycin increases the release of heat shock protein B from Helicobacter pylori

BACKGROUND

Clarithromycin (CAM) may have certain indirect effects on Helicobacter pylori (H. pylori) other than its inhibitory activity on bacterial growth, as indicated in other infections with Gram-negative micro-organisms. In the present study, we examined the effects of lower concentrations of CAM on the release of heat shock protein B (HspB), one of the major antigenic proteins from H. pylori cells, as well as the changes in humoral immune response and histological degree of antral gastritis in patients who received eradication therapy with CAM.

METHODS

The H. pylori strain 26695 and three CAM-resistant clinical isolates were cultured in broth with and without CAM (2-500 ng/mL). Expression of H. pylori proteins was examined by two-dimensional (2D)-electrophoresis followed by N-terminal amino acid sequencing. Changes in host immune response and histological degree of antral gastritis were monitored in patients with peptic ulcer disease who received H. pylori eradication therapy.

RESULTS

2D electrophoresis showed 26 spots in extracellularly released proteins with different profiles from those in cytoplasmic proteins. The release of HspB increased after incubation with CAM (30-500 ng/mL) in all three H. pylori clinical isolates tested. Patients with failed H. pylori eradication after triple therapy with CAM, but not those with failed eradication after dual therapy without CAM, showed an increase in serum IgG1 and IgG2 antibodies against HspB along with a decrease in the degree of neutrophil and H. pylori colonization density in tissue sections.

CONCLUSIONS

CAM may induce a humoral immune response against H. pylori and a decrease in gastric mucosal inflammation through up-regulation of the release of HspB from the bacteria in infected patients.

Vaccination of mice with live recombinant Salmonella typhimurium aroA against H. pylori: parameters associated with prophylactic and therapeutic vaccine efficacy

Previously we described a recombinant attenuated Salmonella typhimurium aroA strain (SL3261[pYZ97]) with constitutive expression of plasmid encoded Helicobacter pylori urease subunits A and B (UreAB). Single dose oral vaccination effectively induced prophylactic immunity against bacterial challenge in BALB/c mice. Here we successfully extended this approach to several mouse strains with allelic differences in NRAMP-1 and H-2 genes. The respective host determinants are known to influence the immune response against S. typhimurium. A comparative analysis of the vaccine efficacy in C57BL/6 and BALB/c mice showed that the live vaccine confers long lasting immunity in both strains (>18 weeks). In C57BL/6 mice, protection was still observed 54 weeks while not all vaccinated BALB/c were immune when challenged after this time. BALB/c mice also needed higher doses of SL3261[pYZ97] for full protection. We also demonstrate a therapeutic potential of SL3261[pYZ97] in H. pylori infected BALB/c and C57BL/6 mice. Urease- and carrier-specific serum antibody responses as well as the level of colonization by the Salmonella were analyzed in both mouse strains after immunization with low (4 x 10(7)CFU) or high (1 x 10(9)CFU) vaccine doses. The results are discussed in the context of inoculum size and the mode of antigen supply required for effective vaccination with recombinant Salmonella.

Vaccines: an ongoing promise?

Over the past decade, intensive research has focused on developing a vaccine therapy for Helicobacter pylori. Substantial unresolved questions cloud the current approach, and the development of a vaccine against this unique organism has proved very challenging. Many candidate vaccines have been tested in animal models. The immunogenicity and the safety of some vaccine formulations have been recently evaluated through clinical trials, and the efficacy of these vaccine therapies in humans will be determined in the near future. This article will provide an overview of the current knowledge of natural and vaccine-induced immune responses to H. pylori infection. It will also review past vaccine successes and failures in animal models and the limited experience to date in using vaccine therapy in humans. Several obstacles to H. pylori vaccine development efforts along with the future direction of these efforts will be discussed.

The design of vaccines against Helicobacter pylori and their development

Helicobacter pylori is a gram negative, spiral, microaerophylic bacterium that infects the stomach of more than 50% of the human population worldwide. It is mostly acquired during childhood and, if not treated, persists chronically, causing chronic gastritis, peptic ulcer disease, and in some individuals, gastric adenocarcinoma and gastric B cell lymphoma. The current therapy, based on the use of a proton-pump inhibitor and antibiotics, is efficacious but faces problems such as patient compliance, antibiotic resistance, and possible recurrence of infection. The development of an efficacious vaccine against H. pylori would thus offer several advantages. Various approaches have been followed in the development of vaccines against H. pylori, most of which have been based on the use of selected antigens known to be involved in the pathogenesis of the infection, such as urease, the vacuolating cytotoxin (VacA), the cytotoxin-associated antigen (CagA), the neutrophil-activating protein (NAP), and others, and intended to confer protection prophylactically and/or therapeutically in animal models of infection. However, very little is known of the natural history of H. pylori infection and of the kinetics of the induced immune responses. Several lines of evidence suggest that H. pylori infection is accompanied by a pronounced Th1-type CD4(+) T cell response. It appears, however, that after immunization, the antigen-specific response is predominantly polarized toward a Th2-type response, with production of cytokines that can inhibit the activation of Th1 cells and of macrophages, and the production of proinflammatory cytokines. The exact effector mechanisms of protection induced after immunization are still poorly understood. The next couple of years will be crucial for the development of vaccines against H. pylori. Several trials are foreseen in humans, and expectations are that most of the questions being asked now on the host-microbe interactions will be answered.

B-Cell epitope mapping of the VapA protein of Rhodococcus equi: implications for early detection of R. equi disease in foals

Linear B-cell epitopes of the Rhodococcus equi virulence-associated protein (VapA) were mapped using a synthetic peptide bank in this study. The peptides were screened in an enzyme-linked immunosorbent assay (ELISA) with a total of 70 sera from foals with current R. equi disease (51 sera), as well as from foals that had either recovered from R. equi infection 10 months previously (3 sera) or that had no known history of R. equi disease (16 sera). An epitope with the sequence NLQKDEPNGRA was identified and was universally recognized by all 51 sera from foals with R. equi disease and was not recognized by any of the other sera. There was poor reactivity between all sera and peptides relating to other areas of the VapA protein. It is proposed that an ELISA based upon a defined peptide epitope may be used in an improved serological diagnostic test for R. equi infection in foals.

Seropositivity to Helicobacter pylori heat shock protein 60 is strongly associated with intensity of chronic inflammation, particularly in antrum mucosa: an extension of an 18-year follow-up study of chronic gastritis in Saaremaa, Estonia

Helicobacter pylori is a cause of chronic gastritis and leads to development of atrophy in some cases. There is evidence that the heat shock protein 60 (HSP60) of H. pylori is involved in induction of chronic inflammation. Seroprevalence of IgG antibodies to H. pylori HSP60 in an adult cohort from Saaremaa, Estonia (68 persons, median age 57 years), with a high prevalence of antibodies to cell surface proteins of H. pylori (92%) and a well characterized dynamics of chronic gastritis in an 18-year follow-up study, was tested using purified H. pylori HSP60 at a concentration of 1 microg ml(-1) with ELISA. The state of the gastric mucosa and the presence of H. pylori in histological sections in the samples of 1979 and 1997 were assessed in accordance with the Sydney system. Seropositivity for H. pylori HSP60 was 65%. Immunological response to H. pylori HSP60 is associated with the morphological presence of H. pylori in the antrum and corpus (P=0.01) and is strongly correlated with the grade of chronic inflammation, particularly in the antrum mucosa (r=0.34; P=0.003; OR=5.97 (95% CI 1.21-29.3)), but is not associated with development of atrophy during 18 years of follow-up, or with the activity of gastritis. This finding supports the evidence that immunological response to H. pylori HSP60 may play a role in triggering of the inflammatory process in the gastric mucosa.