Allergen-specific IgG Responses Research Articles

Self-Assembling Allergen Vaccine Platform Raises Therapeutic Allergen-Specific IgG Responses without Induction of Systemic Allergic Responses.

Allergen immunotherapies are often successful at desensitizing allergic patients but can require life-long dosing and suffer from frequent adverse events including instances of systemic anaphylaxis, leading to poor patient compliance and high cost. Allergen vaccines, in turn, can generate more durable immunological allergen desensitization with far fewer doses. However, like immunotherapies, allergen vaccines are often highly reactogenic in allergic patients, hampering their use in therapeutic settings. In this work, we utilize a peptide-based self-assembling nanofiber platform to design allergen vaccines against allergen B-cell epitopes that do not elicit systemic anaphylaxis when administered subcutaneously to allergic mice. We show that, in contrast to protein vaccines, nanofiber vaccines prevent leakage of allergen material into the vascular compartment, a feature that likely underpins their reduced systemic reactogenicity. Further, we show that our allergen vaccine platform elicits therapeutic IgG antibody responses capable of desensitizing allergic mice to allergen-induced Type I hypersensitivity reactions. Finally, we have demonstrated a proof-of-concept for the therapeutic potential of nanofiber-based peanut allergen vaccines directed against peanut allergen-derived epitopes.

Profound differences in IgE and IgG recognition of micro-arrayed allergens in hyper-IgE syndromes.

BackgroundThe specificities of IgE and IgG for allergen molecules in patients with inborn errors of immunity (IEI) have not been investigated in detail.ObjectiveTo study IgE and IgG antibody specificities in patients with defined hyper‐IgE syndromes (HIES) using a comprehensive panel of allergen molecules.MethodsWe used chips containing micro‐arrayed allergen molecules to analyze allergen‐specific IgE and IgG levels in sera from two groups of HIES patients: Autosomal recessive mutations in phosphoglucomutase‐3 (PGM3); Autosomal dominant negative mutations of STAT3 (STAT3); and age‐matched subjects with allergic sensitizations. Assays with rat basophil leukemia cells transfected with human FcεRI were performed to study the biological relevance of IgE sensitizations.ResultsMedian total IgE levels were significantly lower in the sensitized control group (212.9 kU/L) as compared to PGM3 (5042 kU/L) and STAT3 patients (2561 kU/L). However, PGM3 patients had significantly higher allergen‐specific IgE levels and were sensitized to a larger number of allergen molecules as compared to STAT3 patients. Biological relevance of IgE sensitization was confirmed for PGM3 patients by basophil activation testing. PGM3 patients showed significantly lower cumulative allergen‐specific IgG responses in particular to milk and egg allergens as compared to STAT3 patients and sensitized controls whereas total IgG levels were comparable to STAT3 patients and significantly higher than in controls.ConclusionThe analysis with multiple micro‐arrayed allergen molecules reveals profound differences of allergen‐specific IgE and IgG recognition in PGM3 and STAT3 patients which may be useful for classification of IEI and clinical characterization of patients.

Vaccination of nonallergic individuals with recombinant hypoallergenic fragments of birch pollen allergen Bet v 1: Safety, effects, and mechanisms

Summary This is the first double-blind, placebo-controlled study showing that vaccination with recombinant hypoallergenic allergen-derivatives is safe and induces sustained allergen-specific IgG responses which block allergic patients IgE binding to the allergen.

Mechanisms, safety and efficacy of a B cell epitope-based vaccine for immunotherapy of grass pollen allergy

BackgroundWe have developed a recombinant B cell epitope-based vaccine (BM32) for allergen-specific immunotherapy (AIT) of grass pollen allergy. The vaccine contains recombinant fusion proteins consisting of allergen-derived peptides and the hepatitis B surface protein domain preS as immunological carrier. MethodsWe conducted a randomized, double-blind, placebo-controlled AIT study to determine safety, clinical efficacy and immunological mechanism of three subcutaneous injections of three BM32 doses adsorbed to aluminum hydroxide versus aluminum hydroxide (placebo) applied monthly to grass pollen allergic patients (n=70). Primary efficacy endpoint was the difference in total nasal symptom score (TNSS) through grass pollen chamber exposure before treatment and 4weeks after the last injection. Secondary clinical endpoints were total ocular symptom score (TOSS) and allergen-specific skin response evaluated by titrated skin prick testing (SPT) at the same time points. Treatment-related side effects were evaluated as safety endpoints. Changes in allergen-specific antibody, cellular and cytokine responses were measured in patients before and after treatment. ResultsSixty-eight patients completed the trial. TNSS significantly decreased with mean changes of −1.41 (BM32/20μg) (P=0.03) and −1.34 (BM32/40μg) (P=0.003) whereas mean changes in the BM32/10μg and placebo group were not significant. TOSS and SPT reactions showed a dose-dependent decrease. No systemic immediate type side effects were observed. Only few grade 1 systemic late phase reactions occurred in BM32 treated patients. The number of local injection site reactions was similar in actively and placebo-treated patients. BM32 induced highly significant allergen-specific IgG responses (P<0.0001) but no allergen-specific IgE. Allergen-induced basophil activation was reduced in BM32 treated patients and addition of therapy-induced IgG significantly suppressed T cell activation (P=0.0063). ConclusionThe B cell epitope-based recombinant grass pollen allergy vaccine BM32 is well tolerated and few doses are sufficient to suppress immediate allergic reactions as well as allergen-specific T cell responses via a selective induction of allergen-specific IgG antibodies. (ClinicalTrials.gov number, NCT01445002.)

Designing a multimer allergen for diagnosis and immunotherapy of dog allergic patients.

BackgroundDog dander extract used for diagnosis and allergen-specific immunotherapy is often of variable and of poor quality.ObjectiveTo assemble four well-established dog allergen components into one recombinant folded protein for improved diagnosis and vaccination of allergy to dog.MethodsA linked molecule, comprising the four dog lipocalin allergens Can f 1, Can f 2, Can f 4 and Can f 6 was constructed. The tetrameric protein was structurally characterized by small angle X-ray scattering, and compared with each single recombinant lipocalin allergen or an equimolar mix of the four allergens by analytical size exclusion chromatography, circular dichroism, allergen-specific IgE in serum by ELISA and allergen-dependent capacity to activate basophils. The immunogenicity of the fusion protein was evaluated in immunized mice by assessing splenocyte proliferation and antibody production.ResultsThe linked tetrameric construct was produced as a soluble fusion protein, with the specific folds of the four individual allergens conserved. This multi-allergen molecule was significantly more efficient (p<0.001) than each single recombinant allergen in binding to dog-specific IgE, and the epitope spectrum was unaffected compared to an equimolar mix of the four allergens. Basophil degranulation revealed that the biologic activity of the linked molecule was retained. Immunization of mice with the linked construct induced comparable allergen-specific IgG responses with blocking capacity towards all included allergens and generated comparably low T-cell responses.ConclusionWe provide the first evidence for a linked recombinant molecule covering the major dog allergens for potential use in diagnostics and allergy vaccination of dog allergic patients.

Induction of allergen-specific blocking IgG using patch delivered recombinant Bet v 1 in guinea pigs

Background Allergen-specific immunotherapy (SIT) is the only specific, disease-modifying treatment for allergy and may have long-lasting effects. It is given traditionally in the form of multiple subcutaneous injections which makes the treatment inconvenient. Furthermore, systemic allergenadministration may cause severe side effects. Therefor the development of alternative routes for SIT has been a longsought goal. The aim of this study was to investigate if epicutaneous application of recombinant birch pollen allergen Bet v 1 (i.e., patch vaccination) can induce systemic allergen-specific IgG responses with protective activity.

Microarrayed dog, cat, and horse allergens show weak correlation between allergen-specific IgE and IgG responses⋆

Microarrayed dog, cat, and horse allergens show weak correlation between allergen-specific IgE and IgG responses⋆

Genetic engineering of trimers of hypoallergenic fragments of the major birch pollen allergen, Bet v 1, for allergy vaccination

An immunotherapy trial performed in allergic patients with hypoallergenic recombinant fragments, comprising aa 1–74 and 75–160 of the major birch pollen allergen, Bet v 1, has indicated that the induction of allergen-specific IgG responses may be an important mechanism of this treatment. To investigate whether the immunogenicity of the rBet v 1 fragments can be increased, recombinant trimers of the fragments were produced. For this purpose, DNA trimers of rBet v 1 aa 1–74 as well as of rBet v 1 aa 75–160 were subcloned into expression plasmid pET 17b, expressed in Escherichia coli and purified. The fragments as well as the fragment trimers showed a reduced IgE-binding capacity and allergenic activity compared to rBet v 1 wildtype when tested in allergic patients. Both rBet v 1 aa 75–160 monomer and trimer induced high titers of allergen-specific IgG1 Abs in mice. Interestingly, rBet v 1 aa 1–74 trimer induced a much higher IgG1 response to rBet v 1 than rBet v 1 aa 1–74 monomer. Consequently, IgG Abs induced with the rBet v 1 aa 1–74 trimer inhibited birch pollen allergic patients’ IgE-binding 10-fold more efficiently than IgG Abs induced with the monomer. Our data show that the immunogenicity of allergy vaccines can be increased by oligomerization.

Suppression of Th2-Driven Airway Inflammation by Allergen Immunotherapy Is Independent of B Cell and Ig Responses in Mice

Allergen-specific immunotherapy (IT) uniquely renders long-term relief from allergic symptoms and is associated with elevated serum levels of allergen-specific IgG and IgA. The allergen-specific IgG response induced by IT treatment was shown to be critical for suppression of the immediate phase of the allergic response in mice, and this suppression was partially dependent on signaling through FcγRIIB. To investigate the relevance of the allergen-specific IgG responses for suppression of the Th2-driven late-phase allergic response, we performed IT in a mouse model of allergic asthma in the absence of FcγRIIB or FcγRI/FcγRIII signaling. We found that suppression of Th2 cell activity, allergic inflammation, and allergen-specific IgE responses is independent of FcγRIIB and FcγRI/FcγRIII signaling. Moreover, we show that the IT-induced allergen-specific systemic IgG or IgA responses and B cell function are dispensable for suppression of the late-phase allergic response by IT treatment. Finally, we found that the secretory mucosal IgA response also is not required for suppression of the Th2-driven allergic inflammation by IT. These data are in contrast to the suppression of the immediate phase of the allergic response, which is critically dependent on the induced allergen-specific serum IgG response. Hence, IT-induced suppression of the immediate and late phases of the allergic response is governed by divergent and independent mechanisms. Our data show that the IT-induced suppression of the Th2 cell-dependent late-phase allergic response is independent of the allergen-specific IgG and IgA responses that are associated with IT treatment.

Dermatophagoides farinae‐specific IgG responses in atopic dogs undergoing allergen‐specific immunotherapy with aqueous vaccines

The molecular and immunologic mechanisms associated with successful allergen-specific immunotherapy (ASIT) have not been completely elucidated. The aim of this study was to characterize the changes in Dermatophagoides farinae-specific IgG in atopic dogs undergoing ASIT using aqueous vaccines. Fifteen atopic dogs with a positive skin test reaction to D. farinae were treated with aqueous vaccines for a minimum of 2 months following a standard protocol. Serum samples were collected before and during therapy and used to probe Western blots containing separated proteins of D. farinae. IgG responses were detected using a polyclonal goat anticanine IgG antibody and a chromogenic substrate 3,3'-diaminobenzidine. The blots were analysed using a semiquantitative digital image analysis system that evaluated the number and molecular weight of bands, as well as their intensity, which was related to IgG concentration. Prior to ASIT, all dogs showed allergen-specific IgG responses to various antigens of D. farinae. During ASIT, there was a significant increase in the total quantity of D. farinae-specific IgG antibodies to various antigens from the mite (P = 0.015). Significant increases were observed for a 98-kDa band (P = 0.015), likely to be Der f 15; bands with molecular weights between 50 and 70kDa (P=0.012); and bands between 30 and 45 kDa (P = 0.035). These findings provide support for the hypothesis that ASIT induces IgG blocking antibodies to allergens known to be relevant in canine atopic dermatitis.

Comparison of allergenicity and immunogenicity of an intact allergen vaccine and commercially available allergoid products for birch pollen immunotherapy

Specific immunotherapy with intact allergen vaccine is a well-documented treatment for allergic diseases. Different vaccine formulations are currently commercially available, the active ingredient either being intact allergens or chemically modified allergoids. The rationale behind allergoids is to decrease allergenicity while maintaining immunogenicity. However, data from the German health authorities based on reporting of adverse events over a 10-year period did not indicate increased safety of allergoids over intact allergens. The objective of this study was to investigate the effect of chemical modification on allergenicity and immunogenicity comparing four commercial allergoid products for birch pollen immunotherapy with an intact allergen vaccine. Solid-phase IgE inhibition and histamine release assays were selected as model systems for allergenicity, and a combination of human T cell proliferation and IgG titres following mouse immunizations were used to address the immunogenicity of the intact allergen vaccine and the four allergoids. In all assays, the products were normalized with respect to the manufacturer's recommended maintenance dose. IgE inhibition experiments showed a change in epitope composition comparing intact allergen vaccine with allergoid. One allergoid product induced enhanced histamine release compared to the intact allergens, while the other three allergoids showed reduced release. Standard T cell stimulation assays using lines from allergic patients showed a reduced response for all allergoids compared with the intact allergen vaccine regardless of the cell type used for antigen presentation. All allergoids showed reduced capacity to induce allergen-specific IgG responses in mice. While some allergoids were associated with reduced allergenicity, a clear reduction in immunogenicity was observed for all allergoid products compared with the intact allergen vaccine, and the commercial allergoids tested therefore do not fulfil the allergoid concept.