Immunosuppression of TH2 responses in Trichinella spiralis infection by Helicobacter pylori neutrophil-activating protein

HP-NAP of Helicobacter pylori: The Power of the Immunomodulation

The miniferritin HP-NAP of Helicobacter pylori was originally described as a neutrophil-activating protein because of the capacity to activate neutrophils to generate oxygen radicals and adhere to endothelia. Currently, the main feature for which HP-NAP is known is the ability to promote Th1 responses and revert the immune suppressive profile of macrophages. In this review, we discuss the immune modulating properties of the protein regarding the H. pylori infection and the evidence that support the potential clinical application of HP-NAP in allergy and cancer immunotherapy.

Helicobacter pylori Neutrophil-Activating Protein Directly Interacts with and Activates Toll-like Receptor 2 to Induce the Secretion of Interleukin-8 from Neutrophils and ATRA-Induced Differentiated HL-60 Cells

Helicobacter pylori neutrophil-activating protein (HP-NAP)-induced production of reactive oxygen species (ROS) by neutrophils and monocytes is regulated by pertussis toxin (PTX)-sensitive G proteins, whereas HP-NAP-induced cytokine secretion by monocytes is mediated by Toll-like receptor 2 (TLR2). However, it is unclear whether TLR2 participates in HP-NAP-induced cytokine secretion by neutrophils. Here, all-trans retinoic acid (ATRA)-induced differentiated HL-60 cells were first employed as a neutrophil model to investigate the molecular mechanisms underlying neutrophil responses to HP-NAP. HP-NAP-induced ROS production in ATRA-induced differentiated HL-60 cells is mediated by the PTX-sensitive heterotrimeric G protein-dependent activation of extracellular signal-regulated kinase 1/2 and p38-mitogen-activated protein kinase, which is consistent with the findings reported for human neutrophils. Next, whether TLR2 participated in HP-NAP-induced secretion of interleukin-8 (IL-8) was investigated in neutrophils and ATRA-induced differentiated HL-60 cells. In both cells, TLR2 participated in HP-NAP-induced IL-8 secretion but not HP-NAP-induced ROS production. Interestingly, PTX-sensitive G proteins also contributed to the HP-NAP-induced secretion of IL-8 from neutrophils and the differentiated HL-60 cells. Our ELISA-based binding assay further revealed the competitive binding of Pam₃CSK₄, a TLR2 agonist, and HP-NAP to TLR2, which suggests the presence of specific and direct interactions between HP-NAP and TLR2. Thus, HP-NAP directly interacts with and activates TLR2 to induce IL-8 secretion in neutrophils and ATRA-induced differentiated HL-60 cells.

HP-NAP ameliorates OXA-induced atopic dermatitis symptoms in mice

BACKGROUND

Atopic dermatitis (AD) is a chronic skin inflammatory disease characterized by disequilibrium between Th1/Th2 lymphocytes. Helicobacter pylori neutrophil-activating protein (HP-NAP) has been reported that it has the potential immunomodulatory effect able to regulate the Th1/Th2 balance.

OBJECTIVE

This study aimed to investigate the therapeutic effect of HP-NAP in AD mice model.

METHODS

The model of AD was built with oxazolone (OXA) in BALB/c mice, then HP-NAP was used to treat AD by intraperitoneal injection. Ear thickness was measured by a digital thickness gauge. The ears tissues were collected and subjected to hematoxylin-eosin (H&E) and toluidine blue (TB) staining. The mRNA expression levels of inflammatory cytokines (IL-1β, IL-5, IL-6, and TNF-α) in ear tissue were measured using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The secretion of IgE, IL-4, and IFN-γ was measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Treatment with HP-NAP successfully alleviated the symptoms of AD, such as erythema, horny substance, and swelling. The infiltration of lymphocytes and mast cells were significantly reduced following HP-NAP therapy. The secretion of IgE and IL-4 was significantly attenuated following treatment with HP-NAP. Additionally, HP-NAP observably downregulated inflammatory cytokine expression (e.g. IL-1β, IL-5, IL-6, and TNF-α) in ear tissues.

CONCLUSIONS AND CLINICAL RELEVANCE

Taken together, our results showed that HP-NAP possessed the potential to be a novel immunomodulatory candidate drug against AD.

Protein malnutrition impairs the immune control of Trichinella spiralis infection

OBJECTIVES

We aimed to analyze the effect of a protein-deficient diet on mucosal and systemic immunity during a Trichinella spiralis infection.

METHODS

Two groups of weaning Wistar rats received a protein-deficient diet (6.5% casein) and the other two groups received a control diet (20% casein). After 10 d, one group of each diet was infected (PD_I and C_I) with muscle larvae (infecting stage). Food intake and body weight were assessed over time. Blood eosinophils counts, antibodies in serum, and tissue extracts were assessed at different days postinfection. Histologic studies were done in the lungs and intestines, and adult worm (AW) fecundity index score and muscle parasite burden were determined.

RESULTS

Food and protein intake were lower in PD_I than in C_I. Body weight was lower in PD_I than in a non-infected protein-deficient diet. Eosinophils counts were lower in PD_I than in C_I. Total and specific antibodies were lower in PD_I than C_I. PD_I had a reduced number of mast and goblet cells in the lungs and intestines compared with C_I. The persistence of AW in the intestines and migrant larvae at the lungs was longer in PD_I than in C_I.. The AW fecundity index score was higher in PD_I than in C_I. Finally, PD_I evidenced a higher muscular parasite burden than C_I.

CONCLUSIONS

Protein deficiency affects the mucosal and systemic immune response to Trichinella spiralis and delays the expulsion and increases the fecundity index score of AW, which leads to a higher parasite burden in the muscles.

Group 2 Innate Lymphoid Cells Are Involved in Skewed Type 2 Immunity of Gastric Diseases Induced by Helicobacter pylori Infection

H. pylori induces a complicated local and systematic immune response and contributes to the carcinogenesis of gastric cancer. A primary type 1 immune response is evoked by H. pylori since its occurrence. However, it is not unusual that an inhibitory immunity is dominant in H. pylori-associated diseases, which are promoted by the formation of immunosuppressive microenvironment. But whether group 2 innate lymphoid cells (ILC2s) plays a critical role in H. pylori-induced skewed type 2 immunity is still unclear. In the present study, firstly, we confirmed that type 1 immunity was inhibited and type 2 immunity were undisturbed or promoted after H. pylori infection in vitro and in vivo. Secondly, GATA-3 was firstly found to be increased in the interstitial lymphocytes from H. pylori-associated gastric cancer, among them, Lin-GATA-3⁺ cells and Lin⁺GATA-3⁺ cells were also found to be enhanced, which indicated an important role for ILC2s in H. pylori infection. More importantly, ILC2s were found to be increased after H. pylori infection in clinical patients and animal models. In conclusion, our results indicated that ILC2-mediated innate immune response might play a potential role in dominant type 2 phenotype and immunosuppressive microenvironment in H. pylori infection.

The recombinant fusion protein of cholera toxin B and neutrophil-activating protein expressed on Bacillus subtilis spore surface suppresses allergic inflammation in mice

The neutrophil-activating protein of Helicobacter pylori (HP-NAP) has been identified as a modulator with anti-Th2 inflammation activity, and cholera toxin B (CTB) is a mucosal adjuvant that can also induce antigen tolerance. In this study, we constructed a CTB-NAP fusion protein on the surface of Bacillus subtilis spore and evaluate the efficiency of oral administration of the recombinant CTB-NAP spores in preventing asthma in mice. Oral administration of recombinant CTB or CTB-NAP spores significantly decreased serum ovalbumin (OVA)-specific IgE (p < 0.001) and increased fecal IgA (p < 0.01) compared to the treatment with non-recombinant spores. Oral administration of recombinant CTB or CTB-NAP spores induced IL-10 and IFN-γ expression and reduced IL-4 levels in bronchoalveolar lavage fluid (BALF). Moreover, CTB and CTB-NAP spores reduced the eosinophils in BALF and inflammatory cell infiltration in the lungs. Furthermore, CD4⁺CD25⁺Foxp3⁺ Tregs in splenocytes were significantly increased in mice treated with recombinant CTB or CTB-NAP spores. The number of CD4⁺CD25⁺Foxp3⁺ Tregs caused by CTB-NAP was higher than that by CTB alone. Our study indicated that B. subtilis spores with surface expression of subunit CTB or CTB-NAP could inhibit OVA-induced allergic inflammation in mice. The attenuated inflammation was attributed to the induction of CD4⁺CD25⁺Foxp3⁺ Tregs and IgA. Moreover, the fusion protein CTB-NAP demonstrated a better efficiency than CTB alone in inhibiting the inflammation.

Systemic and mucosal pre-administration of recombinant Helicobacter pylori neutrophil-activating protein prevents ovalbumin-induced allergic asthma in mice

PURPOSE

Previous epidemiologic studies have demonstrated an inverse association between Helicobacter pylori infection and the frequency of allergic asthma. The neutrophil-activating protein (NAP) of H. pylori has been identified as a modulator possessing anti-Th2 inflammation activity. Here, we sought to determine whether systemic or mucosal pre-administration of recombinant H. pylori NAP (rNAP) could prevent ovalbumin (OVA)-induced allergic asthma in mice.

METHODS

Mice were exposed to purified rNAP through intraperitoneal injection or inhalation and then sensitized with OVA. Following a challenge with aerosolized OVA, the bronchoalveolar lavage fluid (BALF) cell count, lung tissue histology, BALF cytokines and serum IgE were evaluated.

RESULTS

Both intraperitoneal injection and inhalation of rNAP prior to OVA sensitization significantly reduced eosinophil accumulation and inflammatory infiltration in lung tissue in OVA-induced asthma mice; eosinophils were reduced in the BALF of rNAP-treated mice. In addition, IL-4 and IL-13 levels were lower (P < 0.01), IL-10 and IFN-γ levels were higher (P < 0.01) and IgE serum levels were lower (P < 0.01) in the treated groups compared to the control group.

CONCLUSIONS

Systemic and mucosal pre-administration of rNAP could suppress the development of OVA-induced asthma in mice; rNAP may be utilized as part of novel strategies for the prevention or treatment of allergic diseases.

Metabolic and adaptive immune responses induced in mice infected with tissue-dwelling nematode Trichinella zimbabwensis

Tissue-dwelling helminths are known to induce intestinal and systemic inflammation accompanied with host compensatory mechanisms to counter balance nutritional and metabolic deficiencies. The metabolic and immune responses of the host depend on parasite species and tissues affected by the parasite. This study investigated metabolic and immuno-inflammatory responses of mice infected with tissue-dwelling larvae of Trichinella zimbabwensis and explored the relationship between infection, metabolic parameters and Th1/Th17 immune responses. Sixty (60) female BALB/c mice aged between 6 to 8 weeks old were randomly assigned into T. zimbabwensis-infected and control groups. Levels of Th1 (interferon-γ) and Th17 (interleukin-17) cytokines, insulin and blood glucose were determined as well as measurements of body weight, food and water intake. Results showed that during the enteric phase of infection, insulin and IFN-γ levels were significantly higher in the Trichinella infected group accompanied with a reduction in the trends of food intake and weight loss compared with the control group. During systemic larval migration, trends in food and water intake were significantly altered and this was attributed to compensatory feeding resulting in weight gain, reduced insulin levels and increased IL-17 levels. Larval migration also induced a Th1/Th17 derived inflammatory response. It was concluded that T. zimbabwensis alters metabolic parameters by instigating host compensatory feeding. Furthermore, we showed for the first time that non-encapsulated T. zimbabwensis parasite plays a role in immunomodulating host Th1/Th17 type responses during chronic infection.

Serum Antibodies against Helicobacter pylori Neutrophil Activating Protein in Carriers of IL-4 C-590T Genetic Polymorphism Amplify the Risk of Gastritis and Gastric Cancer

BACKGROUND

Gastric cancer arises, mainly, on an inflammatory background. Helicobacter pylori neutrophil activating (HP-NAP) protein functions as a potent pro-inflammatory mediator. Similarly, IL-4 plays a critical role in the inflammation pathway, the levels of which are altered by C to T transition at position -590 in its promoter region. Here, we have aimed to assess the risk of gastritis and gastric cancer in the co-presence of these two inflammation modulating mediators.

METHODS

Gastritis (n=58) and gastric cancer (n=31) patients were evaluated and compared with H. pylori-positive asymptomatic controls (n=46), for serum antibodies against recombinant HP-NAP and IL-4 C-590T single nucleotide polymorphism using immunoblotting and PCR-RFLP, respectively. Multivariable logistic regression, adjusting for age, gender and ethnicity, was used for data analysis.

RESULTS

In terms of susceptibility to gastritis, seropositivity to HP-NAP projected a risk impact of 4.62 fold (OR=4.62, 95% CI=1.50-14.22), which when present in IL-4 -590 T carriers augmented the risk up to 9.7 fold (OR=9.70, 95% CI=2.06-45.69). A similar pattern, but of a stronger magnitude, occurred for the risk of gastric cancer, which was estimated at 9.07 fold (OR=9.07, 95% CI=1.99-42.0) for HP-NAP-seropositive subjects and was drastically amplified (OR=33.64, 95% CI=2.06-548.68), when double-positive (HP-NAP seropositive/IL-4 -590 T carrier) subjects were examined against double negatives (HP-NAP seronegative/IL-4 -590 CC).

CONCLUSION

Our preliminary data indicate that serum antibodies against HP-NAP represent a state of risk, which is further exacerbated in IL-4 -590 T carriers. These biomarkers, if validated in larger prospective studies, can be used to screen for gastric cancer susceptibility.

One-step Negative Chromatographic Purification of Helicobacter pylori Neutrophil-activating Protein Overexpressed in Escherichia coli in Batch Mode

Helicobacter pylori neutrophil-activating protein (HP-NAP) is a major virulence factor of Helicobacter pylori (H. pylori). It plays a critical role in H. pylori-induced gastric inflammation by activating several innate leukocytes including neutrophils, monocytes, and mast cells. The immunogenic and immunomodulatory properties of HP-NAP make it a potential diagnostic and vaccine candidate for H. pylori and a new drug candidate for cancer therapy. In order to obtain substantial quantities of purified HP-NAP used for its clinical applications, an efficient method to purify this protein with high yield and purity needs to be established. In this protocol, we have described a method for one-step negative chromatographic purification of recombinant HP-NAP overexpressed in Escherichia coli (E. coli) by using diethylaminoethyl (DEAE) ion-exchange resins (e.g., Sephadex) in batch mode. Recombinant HP-NAP constitutes nearly 70% of the total protein in E. coli and is almost fully recovered in the soluble fraction upon cell lysis at pH 9.0. Under the optimal condition at pH 8.0, the majority of HP-NAP is recovered in the unbound fraction while the endogenous proteins from E. coli are efficiently removed by the resin. This purification method using negative mode batch chromatography with DEAE ion-exchange resins yields functional HP-NAP from E. coli in its native form with high yield and purity. The purified HP-NAP could be further utilized for the prevention, treatment, and prognosis of H. pylori-associated diseases as well as cancer therapy.

Potential protective effect of Helicobacter pylori on the development of gastrointestinal GvHD

Previous reports ascribe a modulating capacity of the immune response to Helicobacter pylori (HP). Our hypothesis was to demonstrate in a prospective study that HP infection could have a protective effect against development of gastrointestinal GvHD in patients receiving allogeneic hematopoietic cell transplantation (HCT). Presence of HP before transplant was determined using C(13) urea breath test. Seventy-nine patients receiving an allogeneic HCT were included and 93.7% of them received PBSC; in 51.9%, the donor was unrelated. Acute gastrointestinal GvHD was diagnosed in 51.9% (n=41). In the multivariable analysis, HP infection was associated with a lower frequency of gastrointestinal GvHD (odds ratio (OR)=0.19 (95% confidence interval (CI): 0.05-0.67); in contrast, an unrelated donor was associated with a higher frequency of gastrointestinal GvHD (odds ratio=5.4 (95% confidence interval: 1.6-18.2). One year overall survival (OS) was 74%. In the multivariate Cox proportional-hazards regression analysis, stages 0-II gastrointestinal GvHD (hazards ratio (HR)=0.19), reduced intensity conditioning (HR=0.04) and tacrolimus-sirolimus GvHD prophylaxis (HR=0.06) were all associated with a better OS. In summary, HP infection could have a role in decreasing gastrointestinal GvHD in patients receiving allogeneic HCT from peripheral blood including related and unrelated donors.

Helicobacter pylori neutrophil-activating protein induces release of histamine and interleukin-6 through G protein-mediated MAPKs and PI3K/Akt pathways in HMC-1 cells

Helicobacter pylori neutrophil-activating protein (HP-NAP) activates several innate leukocytes including neutrophils, monocytes, and mast cells. It has been reported that HP-NAP induces degranulation and interleukin-6 (IL-6) secretion of rat peritoneal mast cells. However, the molecular mechanism is not very clear. Here, we show that HP-NAP activates human mast cell line-1 (HMC-1) cells to secrete histamine and IL-6. The secretion depends on pertussis toxin (PTX)-sensitive heterotrimeric G proteins but not on Toll-like receptor 2. Moreover, HP-NAP induces PTX-sensitive G protein-mediated activation of extracellular signal-regulated kinase 1/2 (ERK1/2), p38-mitogen-activated protein kinase (p38 MAPK), and Akt in HMC-1 cells. Inhibition of ERK1/2, p38 MAPK, or phosphatidylinositol 3-kinase (PI3K) suppresses HP-NAP-induced release of histamine and IL-6 from HMC-1 cells. Thus, the activation of HMC-1 cells by HP-NAP is through Gi-linked G protein-coupled receptor-mediated MAPKs and PI3K/Akt pathways.

High yield purification of Helicobacter pylori neutrophil-activating protein overexpressed in Escherichia coli

BACKGROUND

Helicobacter pylori neutrophil-activating protein (HP-NAP) is involved in H. pylori-induced gastric inflammation. Due to its immunogenic and immunomodulatory properties, HP-NAP has been used for developing vaccines against H. pylori infection and new drugs for cancer therapy.

RESULTS

Here, we provide a simple process for high-yield production of HP-NAP by applying one-step negative chromatography to purify recombinant HP-NAP expressed in Escherichia coli (E. coli). In our E. coli expression system, recombinant HP-NAP constitutes nearly 70% of the total protein. Overexpressed recombinant HP-NAP is almost completely soluble upon cell lysis at pH 9.5. Under the optimal condition at pH 8.0, recombinant HP-NAP with purity higher than 95% can be obtained from E. coli by collecting the unbound fraction using diethylaminoethyl (DEAE) Sephadex resin in batch mode. The overall yield of HP-NAP from a 50-ml E. coli culture is ~19 mg. The purified HP-NAP folds into a multimer with a secondary structure of α-helix and is able to trigger the production of reactive oxygen species by neutrophils.

CONCLUSIONS

Purification of recombinant HP-NAP overexpressed in E. coli using DEAE Sephadex negative mode batch chromatography is an efficient method for high-yield production of highly pure HP-NAP in its native state. The purified HP-NAP is useful for various clinical applications including vaccine development, diagnosis, and new drug development.

Immune evasion strategies used by Helicobacter pylori

Helicobacter pylori (H. pylori) is perhaps the most ubiquitous and successful human pathogen, since it colonizes the stomach of more than half of humankind. Infection with this bacterium is commonly acquired during childhood. Once infected, people carry the bacteria for decades or even for life, if not treated. Persistent infection with this pathogen causes gastritis, peptic ulcer disease and is also strongly associated with the development of gastric cancer. Despite induction of innate and adaptive immune responses in the infected individual, the host is unable to clear the bacteria. One widely accepted hallmark of H. pylori is that it successfully and stealthily evades host defense mechanisms. Though the gastric mucosa is well protected against infection, H. pylori is able to reside under the mucus, attach to gastric epithelial cells and cause persistent infection by evading immune responses mediated by host. In this review, we discuss how H. pylori avoids innate and acquired immune response elements, uses gastric epithelial cells as mediators to manipulate host T cell responses and uses virulence factors to avoid adaptive immune responses by T cells to establish a persistent infection. We also discuss in this review how the genetic diversity of this pathogen helps for its survival.

Vector-encoded Helicobacter pylori neutrophil-activating protein promotes maturation of dendritic cells with Th1 polarization and improved migration

Helicobacter pylori neutrophil-activating protein (HP-NAP) is a major virulence factor involved in H. pylori infection. Both HP-NAP protein and oncolytic viruses encoding HP-NAP have been suggested as immunotherapeutic anticancer agents and adjuvants for vaccination but with little known about its mode of action to activate adaptive immunity. Dendritic cells (DCs) are key players in bridging innate and adaptive immune responses, and in this study we aim to evaluate the effect of HP-NAP on DC maturation, migration, and induction of adaptive immune response. Maturation markers CD83, CD80, CD86, HLA-DR, CD40, and CCR7 were upregulated on human DCs after treatment with supernatants from HP-NAP adenovirus-infected cells. HP-NAP-activated DCs had a Th1 cytokine secretion profile, with high IL-12 and relatively low IL-10 secretion, and migrated toward CCL19. Ag-specific T cells were efficiently expanded by Ag-presenting HP-NAP-activated DCs, which is an important property of functionally mature DCs. Furthermore, intradermal injections of HP-NAP-encoding adenovirus in C57BL/6 mice enhanced resident DC migration to draining lymph nodes, which was verified by imaging lymph nodes by two-photon microscopy and by phenotyping migrating cells by flow cytometry. In conclusion, therapeutic effects of HP-NAP are mediated by maturation of DCs and subsequent activation of Ag-specific T cells in addition to provoking innate immunity.

Helicobacter pylori neutrophil-activating protein: From molecular pathogenesis to clinical applications

Helicobacter pylori (H. pylori) neutrophil-activating protein (HP-NAP) was originally identified as a virulence factor of H. pylori for its ability to activate neutrophils to generate respiratory burst by releasing reactive oxygen species. Later on, HP-NAP was also found to be involved in the protection of H. pylori from DNA damage, supporting the survival of H. pylori under oxidative stress. This protein is highly conserved and expressed by virtually all clinical isolates of H. pylori. The majority of patients infected with H. pylori produced antibodies specific for HP-NAP, suggesting its important role in immunity. In addition to acting as a pathogenic factor by activating the innate immunity through a wide range of human leukocytes, including neutrophils, monocytes, and mast cells, HP-NAP also mediates adaptive immunity through the induction of T helper cell type I responses. The pro-inflammatory and immunomodulatory properties of HP-NAP not only make it play an important role in disease pathogenesis but also make it a potential candidate for clinical use. Even though there is no convincing evidence to link HP-NAP to a disease outcome, recent findings supporting the pathogenic role of HP-NAP will be reviewed. In addition, the potential clinical applications of HP-NAP in vaccine development, clinical diagnosis, and drug development will be discussed.

Excretory/secretory products from Trichinella spiralis adult worms ameliorate DSS-induced colitis in mice

Background

Many evidences show the inverse correlation between helminth infection and allergic or autoimmune diseases. Identification and characterization of the active helminth-derived products responsible for the beneficial effects on allergic or inflammatory diseases will provide another feasible approach to treat these diseases.

Methods and Findings

Colitis was induced in C57BL/6 mice by giving 3% DSS orally for 7 days. During this period, the mice were treated daily with the excretory/secretory products from T. spiralis adult worms (AES) intraperitoneally. The severity of colitis was monitored by measuring body weight, stool consistency or bleeding, colon length and inflammation. To determine the T. spiralis AES product-induced immunological response, Th1, Th2, Th17 and regulatory cytokine profiles were measured in lymphocytes isolated from colon, mesenteric lymph nodes (MLN), and the spleen of treated mice. The CD4⁺ CD25⁺ FOXP3⁺ regulatory T cells (Tregs) were also measured in the spleens and MLN of treated mice. Mice treated with AES significantly ameliorated the severity of the DSS-induced colitis indicated by the reduced disease manifestations, improved macroscopic and microscopic inflammation correlated with the up-regulation of Treg response (increased regulatory cytokines IL-10, TGF-beta and regulatory T cells) and down-regulation of pro-inflammatory cytokines (IFN-gamma, IL-6 and IL-17) in the spleens, MLN and colon of treated mice.

Conclusions

Our results provide direct evidences that T. spiralis AES have a therapeutic potential for alleviating inflammatory colitis in mice. This effect is possibly mediated by the immunomodulation of regulatory T cells to produce regulatory and anti-inflammatory cytokines and inhibit pro-inflammatory cytokines.

Qualitative and quantitative studies of eosinophils in parasitic infections

Th2 responses such as peripheral and tissue eosinophilia are characteristic features in the host animals infected with Strongyloides venezuelensis and Trichinella spiralis. Th2 responses are characterized by a specific profile of cytokines and chemokines induced during the course of infection. In this chapter, we describe the methodology that is utilized in our laboratories to study the production of cytokine, chemokine, and antibodies related to the eosinophilia seen in mice infected with the parasites. Furthermore, protocols are described for the different methods used to study eosinophil functions in the blood and tissues of these experimental models of parasitic infections.

Measles virus expressed Helicobacter pylori neutrophil-activating protein significantly enhances the immunogenicity of poor immunogens

Helicobacter pylori neutrophil-activating protein (NAP) is a toll-like receptor 2 (TLR2) agonist and potent immunomodulator inducing Th1-type immune response. Here we present data about characterization of the humoral immune response against NAP-tagged antigens, encoded by attenuated measles virus (MV) vector platform, in MV infection susceptible type I interferon receptor knockout and human CD46 transgenic (Ifnarko-CD46Ge) mice. Immunogenicity of MV expressing a full-length human immunoglobulin lambda light chain (MV-lambda) was compared to that of MV expressing lambda-NAP chimeric protein (MV-lambda-NAP). MV-lambda-NAP immunized Ifnarko-CD46Ge mice developed significantly higher (6-20-fold) anti-lambda ELISA titers as compared to the MV-lambda-immunized control animal group, indicating that covalently-linked NAP co-expression significantly enhanced lambda immunogenicity. In contrast, ELISA titers against MV antigens were not significantly different between the animals vaccinated with MV-lambda or MV-lambda-NAP. NAP-tagged antigen expression did not affect development of protective anti-measles immunity. Both MV-lambda and MV-lambda-NAP-immunized groups showed strong virus neutralization serum titers in plaque reduction microneutralization test. These results demonstrated that MV-encoded lambda-NAP is highly immunogenic as compared to the unmodified full-length lambda chain. Boost of immune response to poor immunogens using live vectors expressing NAP-tagged chimeric antigens is an attractive approach with potential application in immunoprophylaxis of infectious diseases and cancer immunotherapy.

An infection-enhanced oncolytic adenovirus secreting H. pylori neutrophil-activating protein with therapeutic effects on neuroendocrine tumors

Helicobacter pylori neutrophil-activating protein (HP-NAP) is a major virulence factor involved in H. pylori infection. HP-NAP can mediate antitumor effects by recruiting neutrophils and inducing Th1-type differentiation in the tumor microenvironment. It therefore holds strong potential as a therapeutic gene. Here, we armed a replication-selective, infection-enhanced adenovirus with secretory HP-NAP, Ad5PTDf35-[Δ24-sNAP], and evaluated its therapeutic efficacy against neuroendocrine tumors. We observed that it could specifically infect and eradicate a wide range of tumor cells lines from different origin in vitro. Insertion of secretory HP-NAP did not affect the stability or replicative capacity of the virus and infected tumor cells could efficiently secrete HP-NAP. Intratumoral administration of the virus in nude mice xenografted with neuroendocrine tumors improved median survival. Evidence of biological HP-NAP activity was observed 24 hours after treatment with neutrophil infiltration in tumors and an increase of proinflammatory cytokines such as tumor necrosis factor (TNF)-α and MIP2-α in the systemic circulation. Furthermore, evidence of Th1-type immune polarization was observed as a result of increase in IL-12/23 p40 cytokine concentrations 72 hours postvirus administration. Our observations suggest that HP-NAP can serve as a potent immunomodulator in promoting antitumor immune response in the tumor microenvironment and enhance the therapeutic effect of oncolytic adenovirus.

One-step chromatographic purification of Helicobacter pylori neutrophil-activating protein expressed in Bacillus subtilis

Helicobacter pylori neutrophil-activating protein (HP-NAP), a major virulence factor of Helicobacter pylori (H. pylori), is capable of activating human neutrophils to produce reactive oxygen species (ROS) and secrete inammatory mediators. HP-NAP is a vaccine candidate, a possible drug target, and a potential in vitro diagnostic marker for H. pylori infection. HP-NAP has also been shown to be a novel therapeutic agent for the treatment of allergic asthma and bladder cancer. Hence, an efficient way to obtain pure HP-NAP needs to be developed. In this study, one-step anion-exchange chromatography in negative mode was applied to purify the recombinant HP-NAP expressed in Bacillus subtilis (B. subtilis). This purification technique was based on the binding of host cell proteins and/or impurities other than HP-NAP to DEAE Sephadex resins. At pH 8.0, almost no other proteins except HP-NAP passed through the DEAE Sephadex column. More than 60% of the total HP-NAP with purity higher than 91% was recovered in the flow-through fraction from this single-step DEAE Sephadex chromatography. The purified recombinant HP-NAP was further demonstrated to be a multimeric protein with a secondary structure of α-helix and capable of activating human neutrophils to stimulate ROS production. Thus, this one-step negative chromatography using DEAE Sephadex resin can efficiently yield functional HP-NAP from B. subtilis in its native form with high purity. HP-NAP purified by this method could be further utilized for the development of new drugs, vaccines, and diagnostics for H. pylori infection.

Development of monoclonal antibody-based immunoassays for detection of Helicobacter pylori neutrophil-activating protein

Neutrophil-activating protein (NAP) is a major virulence factor expressed by Helicobacter pylori isolates associated with severe chronic gastroduodenal inflammation and peptic ulcers. NAP is one of the main protective antigens and a target for vaccine development against Helicobacter infection. In addition, NAP is a potent immune stimulator with potential application as a general vaccine adjuvant and in treatment of allergic diseases and cancer immunotherapy. NAP-specific immunoassays are needed for both H. pylori diagnostics and characterization of NAP-based vaccines and immunomodulatory preparations. We generated a panel of NAP-specific monoclonal antibodies (MAbs) by immunization of BALB/c mice with synthetic NAP peptides. The antibody reactivity against recombinant or native NAP antigen was characterized by enzyme-linked immunosorbent assay (ELISA), immunoblotting and immunofluorescence. A sensitive capture ELISA was developed using MAbs 23C8 and 16F4 (directed against different NAP epitopes) for detection of native or measles virus (MV) vector-expressed recombinant NAP in a concentration range of 4 ng/ml to 2000 ng/ml. MAb 23C8 antigen-binding depends on Tyr101 in a variable amino acid sequence of the NAP molecule, indicating the existence of antigenic variants among H. pylori strains. MAb 16F4 reacted with NAP from different H. pylori strains and was a sensitive tool for detection of small amounts of isolated NAP antigen or whole bacteria by immunoblotting or immunofluorescence. In conclusion, MAb-based immunoassays are highly specific and sensitive for detection of native NAP antigen and recombinant NAP immunostimulatory transgenes expressed by replication competent virus vectors.

Expression of immunomodulatory neutrophil-activating protein of Helicobacter pylori enhances the antitumor activity of oncolytic measles virus

Helicobacter pylori neutrophil-activating protein (NAP) is a major virulence factor and powerful inducer of inflammatory reaction and Th1-polarized immune response. Here, we evaluated the therapeutic efficacy of measles virus (MV) strains engineered to express secretory NAP forms against metastatic breast cancer. Recombinant viruses encoding secretory NAP forms (MV-lambda-NAP and MV-s-NAP) efficiently infect and destroy breast cancer cells by cell-to-cell viral spread and large syncytia formation independently of hormone receptor status. Intrapleural administration of MV-s-NAP doubled the median survival in a pleural effusion xenograft model: 65 days as compared to 29 days in the control group (P < 0.0001). This therapeutic effect correlated with a brisk Th1 type cytokine response in vivo. Secretory NAP was expressed at high levels by infected tumor cells and increased tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and IL-12/23 cytokine concentrations were detected in the pleural effusion. In an aggressive model of lung metastatic breast cancer, MV-lambda-NAP and MV-s-NAP also significantly improved survival of the treated animals (P < 0.05) as compared to the control MV strain. These data suggest that potent immunomodulators of bacterial origin, such as H. pylori NAP, can enhance the antitumor effect of oncolytic viruses and support the feasibility and potential of a combined viroimmunotherapy approach.

Stimulation of TH1 Response by Helicobacter Pylori Neutrophil Activating Protein Decreases the Protective Role of IgE and Eosinophils in Experimental Trichinellosis

Th2 responses seem to play an important role in defence against Trichinella spiralis (Ts). The Neutrophil Activating Protein of Helicobacter pylori (HP-NAP), that induces IL-12, and IL-23 expression and shifts to Th1 allergen-specific Th2 cells in vitro was used as an anti-Th2 agent in BALB/c mice infected with T. spiralis. The muscle larvae (ML) burden was lower ( p < 0.02) in untreated infected animals than those infected treated with HP-NAP. In both groups there was an inverse relationship between ML burden of each animal and total IgE level (controls: r −0.617, p = 0.0013 and HP-NAP-treated: r −0.678, P = 0.0001) or eosinophil count, evaluated in the same mouse on day 42 (r −0.390, P = 0.0592 and r −0.803, P = 0.0001, respectively). Inflammatory response around the nurse cell-parasite complex was significantly higher in HP-NAP-treated infected animals than in those untreated infected, on the contrary the number of eosinophils, counted around each complex was significantly lower in the first animal group. This study provides evidence of a powerful anti-Th2 activity in vivo by HP-NAP and for the partial protective effect of Th2 responses in T. spiralis infection.

Expression of T-cell immunoglobulin- and mucin-domain-containing molecules-1 and -3 (Tim-1 and Tim-3) in Helicobacter pylori infection

BACKGROUND

Th immune response plays an important role in Helicobacter pylori (H. pylori) infection. Tim-1 and Tim-3 are expressed on terminally differentiated Th2 and Th1 cells, respectively, and participate in the regulation of Th immune response. Until now, the role of Tim in H. pylori infection remains unclear.

MATERIALS AND METHODS

(1) Lymphocytes isolated from the spleen of BALB/c mice were co-cultured with different concentrations of viable H. pylori. Alternatively, mice were challenged by viable H. pylori to set up the H. pylori infection model. (2) The expression of Tim-1 and Tim-3 on mRNA level in lymphocytes or spleen of mice was determined by RT-PCR. The percentage of Tim-3-positive cells was determined by flow cytometric analysis. The production of cytokine in supernatants was measured by standard sandwich cytokine ELISA.

RESULTS

(1) Co-culture: At 12 hours, there was markedly decreased production of Tim-1 and increased production of Tim-3 in lymphocytes co-cultured with H. pylori compared with normal control. The change of Th2 cytokine had the similar tendency as that of Tim-1 expression; alternatively, the change of Th1 cytokine had the similar tendency as that of Tim-3 expression. (2) INFECTION: Tim-1 expression was declined in infected mice compared with control group; in the contrast, Tim-3 expression was increased. Furthermore, the expression of Tim-1 and Tim-3 mRNA in spleen was significantly positively correlated with the level of Th2 and Th1 cytokine in gastric homogenized supernatant, respectively.

CONCLUSION

H. pylori could inhibit the differentiation of T lymphocytes toward Th2 cells, promote the Th1 cell differentiation, and induce Th1-biased immune response. The expression of Tim-1 and Tim-3 could reflect Th2 and Th1 immune response, respectively, which provide evidence for the prevention and treatment of H. pylori infection and correlation diseases through regulation of Tim-1 and Tim-3.

A Campylobacter jejuni Dps homolog has a role in intracellular survival and in the development of campylobacterosis in neonate piglets

Iron acquisition is an absolute requirement by most microorganisms for host survival. In this work, we investigated the Campylobacter jejuni iron binding Dps protein for a potential role in virulence. In vitro assays using J774A.1 macrophage-like cells demonstrated a 2.5 log reduction in C. jejuni survival of the Dps mutant and a reduction of four logs in invasion of HEp-2 epithelial cells compared to the wild-type strain. To examine the role of the dps gene in host pathogenesis, the piglet model was used in C. jejuni challenge studies. In vivo inoculation studies of newborn piglets with wild-type C. jejuni demonstrated an 11-fold upregulation of the dps gene and intestinal lesion production typical of campylobacteriosis in humans. In contrast, piglets inoculated with the dps mutant were not colonized and remained normal throughout the study period. Mucosal lesion production was restored in piglets inoculated with the complemented Dps mutant strain. Based on these results, we conclude that the C. jejuni Dps homolog is a virulence factor in the production of campylobacteriosis, and warrants further investigation.

Trichinella inflammatory myopathy: host or parasite strategy?

The parasitic nematode Trichinella has a special relation with muscle, because of its unique intracellular localization in the skeletal muscle cell, completely devoted in morphology and biochemistry to become the parasite protective niche, otherwise called the nurse cell. The long-lasting muscle infection of Trichinella exhibits a strong interplay with the host immune response, mainly characterized by a Th2 phenotype.

The aim of this review is to illustrate the role of the Th2 host immune response at the muscle level during trichinellosis in different experimental models, such as knock-out or immuno-modulated mice. In particular, in knock-out mice a crucial role of IL-10 is evident for the regulation of inflammation intensity.

The muscular host immune response to Trichinella is partially regulated by the intestinal phase of the parasite which emphasizes the intensity of the following muscle inflammation compared with animals infected by synchronized injections of newborn larvae. In eosinophil-ablated mice such as PHIL and GATA-- animals it was observed that there was an increased NOS2 expression in macrophages, driven by higher IFN-γ release, thus responsible for muscle larva damage.

Besides modulation of the intestinal stage of the infection, using recombinant IL-12, increases the muscular parasite burden delaying adult worm expulsion from the intestine. Furthermore, a Th1 adjuvant of bacterial origin called Helicobacter pylori neutrophil activating protein (HP-NAP), administered during the intestinal phase of trichinellosis, alters the Th2 dependent response at muscle level.

All these data from the literature delineate then a mutual adaptation between parasite and host immune response in order to achieve a strategic compromise between two evolutionary forces pointed towards the survival of both species.

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

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

Role of virulence factors and host cell signaling in the recognition of Helicobacter pylori and the generation of immune responses

Helicobacter pylori colonizes a large proportion of the world's population, with infection invariably leading to chronic, lifelong gastritis. While the infection often persists undiagnosed and without causing severe pathology, there are a number of host, bacterial and environmental factors that can influence whether infection provokes a mild inflammatory response or results in significant morbidity. Intriguingly, the most virulent H. pylori strains appear to deliberately induce the epithelial signaling cascades responsible for activating the innate immune system. While the reason for this remains unclear, the resulting adaptive immune responses are largely ineffective in clearing the bacterium once infection has become established and, as a result, inflammation likely causes more damage to the host itself.

Infection of non-encapsulated species of Trichinella ameliorates experimental autoimmune encephalomyelitis involving suppression of Th17 and Th1 response

Epidemiological and experimental studies have indicated that helminth infections can ameliorate autoimmune diseases. The present study investigated the amelioration effect of the Trichinella pseudospiralis infection on experimental autoimmune encephalomyelitis (EAE), a T-cell-mediated autoimmune disease of central nervous system (CNS), and expression kinetics of Th17 and Th1 cytokine which play a crucial role in the pathogenesis of EAE. The results indicated that the infection of helminth T. pseudospiralis obviously ameliorated clinical severity and greatly delayed the onset of EAE induced by myelin oligodendrocyte glycoprotein (MOG) immunization. Infection caused much lesser inflammatory infiltration and demyilination in the CNS of infected EAE mice than uninfected EAE mice. The reduced infiltration was also suggested by the expressions of the inflammation cytokines, IL-17, IL-6, IL-1β, IFN-γ, and TNF-α, which were high in the spinal cords of the uninfected EAE mice, but was nearly normal or low in the infected EAE mice. The increased production of MOG-induced IL-17 and IFN-γ and the expression of IL-6, IL-1β, TGF-β in splenocytes after restimulation with MOG was inhibited in the infected EAE mice. On the other hand, the greatly induced Th2 response was observed in the splenocytes of the infected EAE mice. The present study showed that T. pseudospiralis infection can suppresses EAE by reducing the inflammatory infiltration in CNS, likely associated with the suppression of Th17 and Th1 responses by the infection.

Immunity against helminths: interactions with the host and the intercurrent infections

Helminth parasites are of considerable medical and economic importance. Studies of the immune response against helminths are of great interest in understanding interactions between the host immune system and parasites. Effector immune mechanisms against tissue-dwelling helminths and helminths localized in the lumen of organs, and their regulation, are reviewed. Helminth infections are characterized by an association of Th2-like and Treg responses. Worms are able to persist in the host and are mainly responsible for chronic infection despite a strong immune response developed by the parasitized host. Two types of protection against the parasite, namely, premune and partial immunities, have been described. Immune responses against helminths can also participate in pathogenesis. Th2/Treg-like immunomodulation allows the survival of both host and parasite by controlling immunopathologic disorders and parasite persistence. Consequences of the modified Th2-like responses on co-infection, vaccination, and inflammatory diseases are discussed.

Development of vaccines against Helicobacter pylori

Helicobacter pylori is a Gram-negative, microaerophilic bacterium adapted to survive in the stomach of humans where it can cause peptide ulcers and gastric cancer. Although effective antibiotic treatment exists, there is a consensus that vaccines are necessary to limit the severity of this infection. Great progress has been made since its discovery 25 years ago in understanding the virulence factors and several aspects of the pathogenesis of the H. pylori gastric diseases. Several key bacterial factors have been identified: urease, vacuolating cytotoxin, cytotoxin-associated antigen, the pathogenicity island, neutrophil-activating protein, and among others. These proteins, in their native or recombinant forms, have been shown to confer protection against infectious challenge with H. pylori in experimental animal models. It is not known, however, through which effector mechanisms this protection is achieved. Nevertheless, a number of clinical trials in healthy volunteers have been conducted using urease given orally as a soluble protein or expressed in bacterial vectors with limited results. Recently, a mixture of H. pylori antigens was reported to be highly immunogenic in H. pylori-negative volunteers following intramuscular administration of the vaccine with aluminium hydroxide as an adjuvant. These data show that vaccination against this pathogen is feasible. More research is required to understand the immunological mechanisms underlying immune-mediate protection.

Inflammation, immunity, and vaccines for Helicobacter pylori

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

Helicobacter pylori, asthma and allergy

Bronchial asthma and allergic diseases are orchestrated by T-cells producing T-helper type 2 (Th2) cytokines, such as interleukin-4 (IL-4) and IL-5, and are inhibited by Th1 responses. Helicobacter pylori has chronically infected the human population for c. 100,000 years and preferentially elicits a Th1 mucosal immune response with the production of interferon-gamma and IL-12. Among several bacterial factors, the neutrophil-activating protein of H. pylori (HP-NAP) not only plays a key role in driving Th1 inflammation but it is also able to inhibit Th2 responses in vitro and in vivo in allergic bronchial asthma, in humans and mice. Both systemic and mucosal administrations of HP-NAP are successful in reducing eosinophilia, immunoglobulin E and systemic Th2 cytokines at the bronchial level. Thus, these results identify HP-NAP as a candidate for novel strategies for the prevention and treatment of allergic diseases.

Advances in basic and clinical immunology in 2008

We reviewed selected reports in the field of basic and clinical immunology published in 2008. Research progress in the immunologic mechanisms of allergic disease included the modulation of T(H)2 responses by specific transcription factors and receptors associated with the innate immunity, underscoring the importance of the interactions between adaptive and innate immune mechanisms. Investigations of the pathophysiology of hereditary angioedema included a variety of host factors with roles in bradykinin metabolism and vasomotor activity, explaining the variable severity of the clinical presentation. The research focus in HIV infection has shifted from control of disease progression to the barriers for viral eradication, and the search for vaccine designs that provide immunity in the short window between infection and establishment of viral reservoirs. HIV-infected individuals who receive antiviral treatment develop a high incidence of asthma, resembling the inflammatory processes associated with immunoreconstitution. The correlation of molecular diagnosis and clinical presentation was analyzed in 4 relatively rare primary immunodeficiencies: hyper-IgE syndrome; immune dysfunction, polyendocrinopathy, enteropathy, X-linked disease; cartilage-hair hypoplasia; and nuclear factor-kappaB essential modulator deficiency. Studies of patients with partial DiGeorge syndrome and chronic granulomatous disease unveiled subclinical deficiencies that might have an impact in their care. Long-term outcomes from patients with severe combined immunodeficiency who received bone marrow transplants were considered successful compared with the alternative of no intervention. However, the occurrence of adverse events reinforces the need for coordinate efforts to develop optimal protocols for hematopoietic stem cell transplantation for severe immune defects.