Expression and immunogenicity of the major house dust mite allergen Der p 1 following DNA immunization

Nucleic acid vaccines and CpG oligodeoxynucleotides for allergen immunotherapy

PURPOSE OF REVIEW

Molecular forms of allergen-specific immunotherapy (AIT) are continuously emerging to improve the efficacy of the treatment, to shorten the duration of protocols and to prevent any side effects. The present review covers the recent progress in the development of AIT based on nucleic acid encoding allergens or CpG oligodeoxynucleotides (CpG-ODN).

RECENT FINDINGS

Therapeutic vaccinations with plasmid deoxyribonucleic acid (DNA) encoding major shrimp Met e 1 or insect For t 2 allergen were effective for the treatment of food or insect bite allergy in respective animal models. DNA expressing hypoallergenic shrimp tropomyosin activated Foxp3+ T regulatory (Treg) cells whereas DNA encoding For t 2 down-regulated the expression of pruritus-inducing IL-31. Co-administrations of major cat allergen Fel d 1 with high doses of CpG-ODN reduced Th2 airway inflammation through tolerance induction mediated by GATA3+ Foxp3hi Treg cells as well as early anti-inflammatory TNF/TNFR2 signaling cascade. Non-canonical CpG-ODN derived from Cryptococcus neoformans as well as methylated CpG sites present in the genomic DNA from Bifidobacterium infantis mediated Th1 or Treg cell differentiation respectively.

SUMMARY

Recent studies on plasmid DNA encoding allergens evidenced their therapeutic potential for the treatment of food allergy and atopic dermatitis. Unmethylated or methylated CpG-ODNs were shown to activate dose-dependent Treg/Th1 responses. Large clinical trials need to be conducted to confirm these promising preclinical data. Moreover, tremendous success of messenger ribonucleic acid (mRNA) vaccines against severe acute respiratory syndrome coronavirus 2 must encourage as well the re-exploration of mRNA vaccine platform for innovative AIT.

Intranasal immunization with DNA vaccine coexpressing Der p 1 and ubiquitin in an allergic rhinitis mouse model

BACKGROUND

The worldwide prevalence of allergic rhinitis (AR) is increasing, whereas treatments for AR remain limited in effect. Therefore, a new type of effective drug is eagerly in demand.

OBJECTIVE

To create a hypoallergenic vaccine by forced ubiquitination.

METHODS

In the present study, we constructed a DNA vaccine coexpressing Der p 1 allergen and murine ubiquitin, which used chitosan as a carrier. Through the vitro and vivo experiments, we evaluated its protective efficacy against AR.

RESULTS

The results indicated that the DNA vaccine pVAX1-Ub-Derp1/CS had been successfully constructed. This nanoparticle could not only transfect 293T cells in vitro but also transform cells in vivo. The inflammation of nasal mucosa in an AR murine model via immunization with pVAX1-Ub-Derp1/CS was less severe than those without treatments. Furthermore, it found that mice immunized with pVAX1-Ub-Derp1/CS generated a high level of specific IgG but a low level of specific IgE (P < .01). The significantly increased levels of interferon-γ and the significantly decreased levels of interleukins 4, 10, and 17 indicated that a TH1-type response was elicited by immunization with pVAX1-Ub-Derp1/CS (P < .01). This effect was especially stronger through intranasal immunization.

CONCLUSION

Nasal mucosal immunization and ubiquitination are efficacious strategies to enhance the efficiency and safety of DNA vaccine. The nanoparticle pVAX1-Ub-Derp1/CS is expected to be a new kind of effective vaccine for AR.

In planta expression of a mature Der p 1 allergen isolated from an Italian strain of Dermatophagoides pteronyssinus

European (Dermatophagoides pteronyssinus) and American (Dermatophagoides farinae) house dust mite species are considered the most common causes of asthma and allergic symptoms worldwide. Der p 1 protein, one of the main allergens of D. pteronyssinus, is found in high concentration in mites faecal pellets, which can became easily airborne and, when inhaled, can cause perennial rhinitis and bronchial asthma. Here we report the isolation of the Der p 1 gene from an Italian strain of D. pteronyssinus and the PVX-mediated expression of its mature form (I-rDer p 1) in Nicotiana benthamiana plants. Human sera from characterized allergic patients were used for IgE binding inhibition assays to test the immunological reactivity of I-rDer p 1 produced in N. benthamiana plants. The binding properties of in planta produced I-rDer p 1 versus the IgE of patients sera were comparable to those obtained on Der p 1 preparation immobilized on a microarray. In this paper we provide a proof of concept for the production of an immunologically active form of Der p 1 using a plant viral vector. These results pave the way for the development of diagnostic allergy tests based on in planta produced allergens.

Airway inflammation and IgE production induced by dust mite allergen-specific memory/effector Th2 cell line can be effectively attenuated by IL-35

CD4(+) memory/effector T cells play a central role in orchestrating the rapid and robust immune responses upon re-encounter with specific Ags. However, the immunologic mechanism(s) underlying these responses are still not fully understood. To investigate this, we generated an allergen (major house dust mite allergen, Blo t 5)-specific murine Th2 cell line that secreted IL-4, IL-5, IL-10, and IL-13, but not IL-9 or TNF-α, upon activation by the cognate Ag. These cells also exhibited CD44(high)CD62L(-) and CD127(+) (IL-7Rα(+)) phenotypes, which are characteristics of memory/effector T cells. Experiments involving adoptive transfer of this Th2 cell line in mice, followed by three intranasal challenges with Blo t 5, induced a dexamethasone-sensitive eosinophilic airway inflammation. This was accompanied by elevation of Th2 cytokines and CC- and CXC-motif chemokines, as well as recruitment of lymphocytes and polymorphic mononuclear cells into the lungs. Moreover, Blo t 5-specific IgE was detected 4 d after the last intranasal challenge, whereas elevation of Blo t 5-specific IgG1 was found at week two. Finally, pulmonary delivery of the pVAX-IL-35 DNA construct effectively downregulated Blo t 5-specific allergic airway inflammation, and i.m. injection of pVAX-IL-35 led to long-lasting suppression of circulating Blo t 5-specific and total IgE. This model provides a robust research tool to elucidate the immunopathogenic role of memory/effector Th2 cells in allergic airway inflammation. Our results suggested that IL-35 could be a potential therapeutic target for allergic asthma through its attenuating effects on allergen-specific CD4(+) memory/effector Th2 cell-mediated airway inflammation.

Production of monoclonal antibody by DNA immunization with electroporation

DNA immunization with in vivo electroporation is an efficient alternative protocol for the production of monoclonal antibodies (mAb). Generation of mAb by DNA immunization is a novel approach to circumvent the following technical hurdles associated with problematic antigens: low abundance and protein instability and use of recombinant proteins that lack posttranslational modifications. This chapter describes the use of a DNA-based immunization protocol for the production of mAb against a house dust mite allergen, designated as Blo t 11, which is a paramyosin homologue found in Blomia tropicalis mites. The Blo t 11 cDNA fused at the N terminus to the sequence of a signal peptide was cloned into the pCI mammalian expression vector. The DNA construct was injected intramuscularly with in vivo electroporation into mice, and the specific antibody production in mice was analyzed by enzyme-linked immunosorbent assay (ELISA). Hybridomas were generated by fusing mouse splenocytes with myeloma cells using the ClonaCell-HY Hybridoma Cloning Kit. Six hybridoma clones secreting Blo t 11 mAb were successfully generated, and these mAb are useful reagents for immunoaffinity purification and immunoassays.

Inflammatory and remodeling events in asthma with chronic exposure to house dust mites: a murine model

Although animal models with ovalbumin have been used to study chronic asthma, there are difficulties in inducing recurrence as well as in maintaining chronic inflammation in this system. Using a murine model of house dust mite (HDM)-induced bronchial asthma, we examined the airway remodeling process in response to the chronic exposure to HDM. During the seventh and twelfth weeks of study, HDM were inhaled through the nose for three consecutive days and airway responsiveness was measured. Twenty-four hours later, bronchoalveolar lavage and histological examination were performed. The degree of overproduction of mucus, subepithelial fibrosis, and the thickness of the peribronchial smooth muscle in the experimental group was clearly increased compared to the control group. In addition, HDM-exposed mice demonstrated severe airway hyperreactivity to methacholine. In the bronchoalveolar lavage fluid, the number of total cells and eosinophils was increased; during the twelfth week, the number of neutrophils increased in the experimental group. With regard to changes in cytokines, the concentrations of IL-4, IL- 13, and transforming growth factor-beta (TGF-beta) were increased in the experimental group. The data suggest that eosinophils, IL-4, IL-13, and TGF-beta might play an important role in the airway remodeling process and that neutrophils may be involved with increased exposure time.

DNA vaccines and allergic diseases

1. Allergic diseases are characterized by inappropriate immune responses to common environmental antigens. The prevalence of these diseases has been increasing worldwide for reasons that are not exactly clear. 2. Current treatment is largely symptomatic. Because the initial observation that simple plasmid DNA injections resulted in in vivo protein expression and induction of adaptive immune responses to the encoded antigen, the potential of modifying the allergic immune responses by DNA vaccination so as to treat and prevent these diseases has been explored extensively. 3. In the present paper we review preclinical studies using animal models of allergic diseases, with an emphasis on DNA vaccine design, for house dust mite allergens-related allergic asthma.

[Genetic immunization: new ways for protective and therapeutic vaccines against allergic diseases]

Gene vaccines have proven to be a powerful tool to induce anti-allergic immune responses. Their underlying functional principle is based on the recruitment of allergen-specific Th1 cells and the establishment of a Th1 cytokine milieu, which protects against the development of a Th2-biased response and balances an already ongoing Th2-type response. Genetic immunization also offers novel approaches to the major problems associated with protein immunization, such as crosslinking of preexisting IgE on mast cells/basophils or induction of de novo synthesis of IgE by the protein immunization itself. In addition to the description of the principles of gene vaccination, this review gives a short overview of recently developed anti-allergic gene vaccines with an optimized efficacy and safety profile.

Nanoparticles as potential oral delivery systems of proteins and vaccines: a mechanistic approach

Peptides and proteins remain poorly bioavailable upon oral administration. One of the most promising strategies to improve their oral delivery relies on their association with colloidal carriers, e.g. polymeric nanoparticles, stable in gastrointestinal tract, protective for encapsulated substances and able to modulate physicochemical characteristics, drug release and biological behavior. The mechanisms of transport of these nanoparticles across intestinal mucosa are reviewed. In particular, the influence of size and surface properties on their non-specific uptake or their targeted uptake by enterocytes and/or M cells is discussed. Enhancement of their uptake by appropriate cells, i.e. M cells by (i) modeling surface properties to optimize access to and transport by M cells (ii) identifying surface markers specific to human M cell allowing targeting to M cells and nanoparticles transcytosis is illustrated. Encouraging results upon in vivo testing are reported but low bioavailability and lack of control on absorbed dose slow down products development. Vaccines are certainly the most promising applications for orally delivered nanoparticles.

Co-administration of vaccination with DNA encoding T cell epitope on the Der p and BCG inhibited airway remodeling in a murine model of chronic asthma

Therapeutic modalities of airway remodeling in asthma have proved to be unsuccessful regarding reversing the previously established chronic airway changes. Recently, the potential of plasmid DNA to inhibit the Th2 immune response has been demonstrated in animal models of asthma. Bacillus Calmette-Guerin (BCG) immunization also induced immunomodulation, which appeared to be reliant on the properties of the interferon-gamma that was produced. Mice were immunized with house dust mite extract (HDM). At the 3 week point, we injected BCG subcutaneously into mice on three successive weeks. One week after the BCG injection, we immunized mice with the DNA plasmid encoding for murine T-cell epitope on Dermatophagoide pteronyssinus 2 thrice weekly. At 9 weeks after immunization, we measured airway responsiveness. Twenty four hours later, we performed bronchoalveolar lavage and histological examinations. Co-administration of DNA vaccination and BCG resulted in a partial suppression of the overproduction of goblet cells and the thickness of the peribronchial smooth muscle in ongoing allergic responses. In the bronchoalveolar lavage fluid, the number of total cells and eosinophils was reduced, and regarding the change of cytokines, the concentration of IL-4 was also decreased, but interferon-gamma was increased in the co-administration group, opposed to the asthma group. These results suggest that co-administration of vaccination with the DNA encoding T-cell epitope and BCG are effective regarding ongoing allergic response and might constitute an ideal method for combating allergic disease in the future.

Intramuscular immunization with DNA construct containing Der p 2 and signal peptide sequences primed strong IgE production

BACKGROUND

Previous studies demonstrated that allergen gene vaccination induced TH1-skewed responses and inhibited IgE production. This study evaluated and characterized the immune responses induced by three DNA constructs encoding different forms of Der p 2 for safe and efficacious vaccination against mite allergy.

METHODS

Mice were immunized intramuscularly with DNA constructs encoding a major mite allergen, Der p 2, without a signal peptide (p2), with a signal peptide (p52), and with a signal peptide plus lysosomal-targeting sequence (p52-LA), respectively, followed by TH2-skewed protein challenge. Antibody and T-cell cytokine responses were assessed by ELISA. Primed dendritic cells (DCs) were adoptively transferred to naïve mice and humoral responses were examined after protein challenge. The circulating Der p 2 protein was detected by sandwich ELISA.

RESULTS

Mice immunized with p52-LA showed strong and clear-cut TH1-type response, as evident by high IFN-gamma production and elevated levels of Der p 2-specific IgG2a production whereas construct p2 induced only moderate levels of TH1 response. In contrast, mice immunized with construct p52 showed a mixed TH1/TH2 phenotype and produced substantial circulating Der p 2 protein. Mice adoptively transferred with DCs primed by p52 construct, but not by the p2 or p52-LA constructs, were sensitized to produce high levels of Der p 2-specific IgE.

CONCLUSIONS

Immunization with DNA construct encoding a signal peptide could potentially prime TH2-skewed responses and IgE production. The additional inclusion of lysosomal-targeting sequences to such construct could improve the safety and efficacy of DNA vaccination against allergy.

Is Genetic Vaccination against Allergy Possible?

Genetic immunization has proven a powerful method to induce antiallergic immune responses. The underlying functional principle has been described to be based on the recruitment of allergen-specific Th1 cells, CD8+ cells and the establishment of a Th1 cytokine milieu, which prevent the development of a Th2-biased response in a protective setup and can balance an ongoing Th2-type response in a therapeutic situation. Genetic immunization with plasmid DNA offers innovative solutions to the major problems associated with protein immunization, such as crosslinking of pre-existing immunoglobulin E on mast cells/basophils or induction of de novo synthesis of immunoglobulin E by the protein immunization itself. It easily enables the routine production of hypoallergenic vaccines, which do not translate native allergens, thus avoiding potential anaphylactic side effects. DNA vaccines can also be applied as mixtures of single vaccines, making them interesting candidates for treatment based on component-resolved diagnosis, followed by an individualized therapy with the relevant allergens. In addition to the description of up-to-date allergen gene vaccine approaches, this review gives an overview of animal studies dealing with the following topics: danger signals as the inherent adjuvant properties, methods to optimize the vaccine immunogenicity, modulation of the immune response, nonparenteral applications and low-dose vaccination strategies.

Efficacy evaluation of Der p 1 DNA vaccine for allergic asthma in an experimental mouse model

Der p 1 is a major allergen that reacts with IgE in more than 70% allergic sera, hence a good candidate for DNA vaccine development. Previous study demonstrated that intramuscular injection of plasmid DNA containing wild type Der p 1 gene induced specific Th1 skewed immune response. The aim of this study is to further optimize the DNA construct to achieve preventive and therapeutic efficacies. An optimized construct, containing mouse Igkappa light chain leader sequence followed by codon optimized mature Der p 1 gene, was generated and used to prevent or treat Der p1 induced allergic asthma in an experimental model. Results showed that this optimized construct was effective in the inhibition of Der p 1 specific IgE levels, attenuation of Th2 response and reduction of airway hyperresponsiveness in terms of prophylactic efficacy. It also showed therapeutic efficacy in IgE inhibition and up-regulation of IgG2a and IFN-gamma. The information obtained here could facilitate the design of DNA vaccines for allergy in general.

DNA immunization for the production of monoclonal antibodies to Blo t 11, a paramyosin homolog from Blomia tropicalis

BACKGROUND

Blo t 11 is a high molecular weight allergen from Blomia tropicalis with significant immunoglobulin (Ig)E binding frequency. Native and recombinant Blo t 11 are susceptible to degradation and the isolation and expression of the allergen is problematic thus obtaining sufficient amounts of purified Blo t 11 for antibody production is limiting. DNA-based immunization is an attractive alternative strategy that bypasses antigen purification for antibody production.

OBJECTIVES

To use a DNA-based immunization protocol for the production and characterization of Blo t 11 monoclonal antibodies (mAbs).

METHODS

The 2625 bp cDNA coding for Blo t 11 was cloned into a mammalian expression vector and immunized intramuscularly with electroporation into mice. Monoclonal antibodies to Blo t 11 were generated using a methylcellulose-based hybridoma cloning kit. These mAbs were utilized for native Blo t 11 isolation and the development of sandwich enzyme-linked immunosorbent assay (ELISA).

RESULTS

Six mAbs recognizing the native and recombinant Blo t 11 were generated and characterized. Native Blo t 11 was affinity purified from Bt extract and its identity was confirmed by matrix assisted laser desorption/ionization - time of flight mass spectrometry. The native Blo t 11 showed IgE reactivity with 67% of mite allergic sera. A two-site ELISA developed showed a detection limit of 100 pg/ml of Blo t 11.

CONCLUSION

A DNA-based immunization protocol was successfully used to generate Blo t 11 mAbs with a spectrum of distinct epitopes located throughout the whole molecule, and they are useful for immunoaffinity purification and immunoassays.

DNA vaccines for non-infectious diseases: new treatments for tumour and allergy

The last decade of DNA vaccine research was characterised by a pioneer spirit and enormous enthusiasm, with a large number of publications demonstrating the usefulness of this approach. Unfortunately, DNA vaccines have not necessarily met the high clinical expectations and a number of complications need to be overcome. In the case of cancer and allergy, the requirements for achieving the objectives are very different. Vaccines against allergies need to suppress or alter an unwanted immune response, while a cancer DNA vaccine has to overcome tolerance and/or immune suppression and initiate a powerful immune response. This review addresses currently used general optimisation strategies for DNA vaccines such as modification of immunisation regimens, improving the delivery systems and using molecular adjuvants. In addition, cancer-specific approaches, such as the stimulation of innate and adaptive immunity with replicase-based DNA vaccines, and targeting non-tumour-associated antigens (TAAs) are discussed. Specifically for the optimisation of DNA vaccination against allergies, procedures such as allergen gene recoding, T helper (Th)1 modulation, and the creation of safe DNA vaccines by gene fragmentation, ubiquitination or using artificial hypoallergens are being analysed. These strategies, individually or in combination, hold the potential of making DNA vaccines useful for application in the clinic.

Chitosan nanoparticles containing plasmid DNA encoding house dust mite allergen, Der p 1 for oral vaccination in mice

Our previous studies indicated that intramuscular (i.m.) immunisation with full length Der p 1 cDNA induced significant humoral response to the left domain (approximately corresponding to amino acids 1-116) but not to the right domain (approximately corresponding to amino acids 117-222) of Der p 1 allergen. This study explored the use of chitosan-DNA nanoparticles for oral immunisation to induce immune responses specific to both the left and right domains of Der p 1. DNA constructs pDer p 1 (1-222) and pDer p 1 (114-222) were complexed with chitosan and delivered orally followed by an i.m. injection of pDer p 1 (1-222) 13 weeks later. Such approach has successfully primed Th1-skewed immune responses against both domains of Der p 1. This strategy could be further optimised for more efficacious gene vaccination for full length Der p 1.

Generation of monoclonal antibodies against Blo t 3 using DNA immunization with in vivo electroporation

BACKGROUND

House dust mite allergy is closely associated with allergic diseases. Blomia tropicalis mite species is an important clinical species in the tropics. The cDNA clone encoding Blo t 3, a group 3 allergen from B. tropicalis, has been isolated in our laboratory.

OBJECTIVE

This study was designed to generate Blo t 3-specific monoclonal antibodies (mAbs) for the detection, characterization and purification of this allergen.

METHODS

Mice were immunized intramuscularly with naked plasmid DNA encoding Blo t 3 gene with in vivo electroporation. Hybridomas were generated by the fusion of the splenocytes to X63-Ag8.653 myeloma cells. Purified native Blo t 3 was obtained by mAb immuno-affinity purification and the allergenicity of native Blo t 3 was determined by human IgE enzyme-linked immunosorbent assay (ELISA).

RESULTS

A panel of class-switched and high-affinity mAb recognizing a wide spectrum of Blo t 3 epitopes have been generated. These mAbs are useful for western immunoblot assay, sandwich ELISA and affinity purification of native Blo t 3. Allergenicity of native Blo t 3 protein was examined with 44 mite-allergic sera and approximately 57% of the tested sera had positive serum IgE reactivity to the native Blo t 3.

CONCLUSIONS

These results demonstrated that intramuscular injection of naked DNA encoding Blo t 3 gene combined with in vivo electroporation is an effective and simple method to raise monoclonal antibodies that can be used for characterization and purification of Blo t 3.