Frequent occurrence of T cell-mediated late reactions revealed by atopy patch testing with hypoallergenic rBet v 1 fragments

B-cell epitope peptide immunotherapy alleviates chitin-binding protein-induced type 2 airway inflammation in a Blomia tropicalis-murine model

BACKGROUND

Peptide immunotherapy (PIT) offers a safe and effective treatment with minimal side effects. This study aims to identify B-cell epitopes of a novel allergen from Blomia tropicalis (B. tropicalis), specifically the Chitin-binding domain type 2 (ChtBD2) protein, and evaluate the therapeutic effects of peptide treatment in a murine model.

METHODS

Using Alphafold2, the 3D structure of ChtBD2 was constructed. AI-based and traditional computational tools predicted the predominant B-cell epitopes. Twelve synthesized peptides were assessed for allergenicity and immunogenicity. A murine model of B. tropicalis-induced allergic airway inflammation mimicking human atopic asthma was developed and analyzed.

RESULTS

Predominant B-cell epitopes of ChtBD2 were identified as promising IgE-binding domains. Peptide 1 (PT1: 1-15) showed significant IgE-binding activity and the highest inhibition rate in competitive IgE-binding assays. PT1 upregulated IL-4, IL-13, and CD63 in B. tropicalis-sensitized patients' PBMCs and basophils, respectively. Notably, IT groups showed reduced lung cellular infiltration and type 2 cytokine expression in BALF. Specific IgE levels were reduced, with a decline in the IgG1/IgG2a ratio.

CONCLUSIONS

This study represents the first AI-facilitated development of a B-cell epitope-based ChtBD2 PIT, showing promise as an immunotherapy for B. tropicalis-allergic patients with reduced allergenicity and high immunogenicity in inducing IgG-blocking antibodies.

CLINICAL TRIAL

Not applicable.

Recombinant PreS-fusion protein vaccine for birch pollen and apple allergy

BACKGROUND

IgE cross-sensitization to major birch pollen allergen Bet v 1 and pathogenesis-related (PR10) plant food allergens is responsible for the pollen-food allergy syndrome.

METHODS

We designed a recombinant protein, AB-PreS, consisting of non-allergenic peptides derived from the IgE-binding sites of Bet v 1 and the cross-reactive apple allergen, Mal d 1, fused to the PreS domain of HBV surface protein as immunological carrier. AB-PreS was expressed in E. coli and purified by chromatography. The allergenic and inflammatory activity of AB-PreS was tested using basophils and PBMCs from birch pollen allergic patients. The ability of antibodies induced by immunization of rabbits with AB-PreS and birch pollen extract-based vaccines to inhibit allergic patients IgE binding to Bet v 1 and Mal d 1 was assessed by ELISA.

RESULTS

IgE-binding experiments and basophil activation test revealed the hypoallergenic nature of AB-PreS. AB-PreS induced lower T-cell activation and inflammatory cytokine production in cultured PBMCs from allergic patients. IgG antibodies induced by five injections with AB-PreS inhibited allergic patients' IgE binding to Bet v 1 and Mal d 1 better than did IgG induced by up to 30 injections of six licensed birch pollen allergen extract-based vaccines. Additionally, immunization with AB-PreS induced HBV-specific antibodies potentially protecting from infection with HBV.

CONCLUSION

The recombinant AB-PreS-based vaccine is hypoallergenic and superior over currently registered allergen extract-based vaccines regarding the induction of blocking antibodies to Bet v 1 and Mal d 1 in animals.

Peptide immunotherapy for aeroallergens

Background: Allergen specific immunotherapy (SIT) has been used for more than a century. Researchers have been working to improve efficacy and reduce the side effects. Objective: We have reviewed the literature about peptides immunotherapy for inhaled allergens. The mechanism of SIT is to induce regulatory T (Treg) cells and to reduce T helper (Th)2 cells to induce class switching from IgE to IgG and induce blocking antibodies to inhibit allergen binding of IgE. Methods: The relevant published literatures on the peptide SIT for aeroallergens have been searched on the medline. Results: Modification of allergens and routes of treatment has been performed. Among them, many researchers were interested in peptide immunotherapy. T-cell epitope peptide has no IgE epitope, that is able to bind IgE, but rather induces Treg and reduces Th2 cells, which was considered an ideal therapy. Results from cellular and animal model studies have been successful. However, in clinical studies, T-cell peptide immunotherapy has failed to show efficacy and caused side effects, because of the high effective rate of placebo and the development of IgE against T-cell epitope peptides. Currently, the modifications of IgE-allergen binding by blocking antibodies are considered for successful allergen immunotherapy. Conclusion: Newly developed hypoallergenic B cell epitope peptides and computational identification methods hold great potential to develop new peptide immunotherapies.

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

BACKGROUND

The specificities of IgE and IgG for allergen molecules in patients with inborn errors of immunity (IEI) have not been investigated in detail.

OBJECTIVE

To study IgE and IgG antibody specificities in patients with defined hyper-IgE syndromes (HIES) using a comprehensive panel of allergen molecules.

METHODS

We 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.

RESULTS

Median 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.

CONCLUSION

The 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.

The role of allergen-specific IgE, IgG and IgA in allergic disease

Immunoglobulin E (IgE)‐mediated allergy is the most common hypersensitivity disease affecting more than 30% of the population. Exposure to even minute quantities of allergens can lead to the production of IgE antibodies in atopic individuals. This is termed allergic sensitization, which occurs mainly in early childhood. Allergen‐specific IgE then binds to the high (FcεRI) and low‐affinity receptors (FcεRII, also called CD23) for IgE on effector cells and antigen‐presenting cells. Subsequent and repeated allergen exposure increases allergen‐specific IgE levels and, by receptor cross‐linking, triggers immediate release of inflammatory mediators from mast cells and basophils whereas IgE‐facilitated allergen presentation perpetuates T cell–mediated allergic inflammation. Due to engagement of receptors which are highly selective for IgE, even tiny amounts of allergens can induce massive inflammation. Naturally occurring allergen‐specific IgG and IgA antibodies usually recognize different epitopes on allergens compared with IgE and do not efficiently interfere with allergen‐induced inflammation. However, IgG and IgA antibodies to these important IgE epitopes can be induced by allergen‐specific immunotherapy or by passive immunization. These will lead to competition with IgE for binding with the allergen and prevent allergic responses. Similarly, anti‐IgE treatment does the same by preventing IgE from binding to its receptor on mast cells and basophils. Here, we review the complex interplay of allergen‐specific IgE, IgG and IgA and the corresponding cell receptors in allergic diseases and its relevance for diagnosis, treatment and prevention of allergy.

From Allergen Molecules to Molecular Immunotherapy of Nut Allergy: A Hard Nut to Crack

Peanuts and tree nuts are two of the most common elicitors of immunoglobulin E (IgE)-mediated food allergy. Nut allergy is frequently associated with systemic reactions and can lead to potentially life-threatening respiratory and circulatory symptoms. Furthermore, nut allergy usually persists throughout life. Whether sensitized patients exhibit severe and life-threatening reactions (e.g., anaphylaxis), mild and/or local reactions (e.g., pollen-food allergy syndrome) or no relevant symptoms depends much on IgE recognition of digestion-resistant class I food allergens, IgE cross-reactivity of class II food allergens with respiratory allergens and clinically not relevant plant-derived carbohydrate epitopes, respectively. Accordingly, molecular allergy diagnosis based on the measurement of allergen-specific IgE levels to allergen molecules provides important information in addition to provocation testing in the diagnosis of food allergy. Molecular allergy diagnosis helps identifying the genuinely sensitizing nuts, it determines IgE sensitization to class I and II food allergen molecules and hence provides a basis for personalized forms of treatment such as precise prescription of diet and allergen-specific immunotherapy (AIT). Currently available forms of nut-specific AIT are based only on allergen extracts, have been mainly developed for peanut but not for other nuts and, unlike AIT for respiratory allergies which utilize often subcutaneous administration, are given preferentially by the oral route. Here we review prevalence of allergy to peanut and tree nuts in different populations of the world, summarize knowledge regarding the involved nut allergen molecules and current AIT approaches for nut allergy. We argue that nut-specific AIT may benefit from molecular subcutaneous AIT (SCIT) approaches but identify also possible hurdles for such an approach and explain why molecular SCIT may be a hard nut to crack.

Novel vaccines for allergen-specific immunotherapy

PURPOSE OF REVIEW

Allergen-specific immunotherapy (AIT) is a highly economic, effective and disease-modifying form of allergy treatment but requires accurate prescription and monitoring. New molecular approaches are currently under development to improve AIT by reducing treatment-related side effects, cumbersome protocols and patients' compliance. We review the current advances regarding refined diagnosis for prescription and monitoring of AIT and the development of novel molecular vaccines for AIT. Finally, we discuss prophylactic application of AIT.

RECENT FINDINGS

There is evidence that molecular allergy diagnosis not only assists in the prescription and monitoring of AIT but also allows a refined selection of patients to increase the likelihood of treatment success. New data regarding the effects of AIT treatment with traditional allergen extracts by alternative routes have become available. Experimental approaches for AIT, such as virus-like particles and cell-based treatments have been described. New results from clinical trials performed with recombinant hypoallergens and passive immunization with allergen-specific antibodies highlight the importance of allergen-specific IgG antibodies for the effect of AIT and indicate opportunities for preventive allergen-specific vaccination.

SUMMARY

Molecular allergy diagnosis is useful for the prescription and monitoring of AIT and may improve the success of AIT. Results with molecular allergy vaccines and by passive immunization with allergen-specific IgG antibodies indicate the importance of allergen-specific IgG capable of blocking allergen recognition by IgE and IgE-mediated allergic inflammation as important mechanism for the success of AIT. New molecular vaccines may pave the road towards prophylactic allergen-specific vaccination.

Preventive Allergen-Specific Vaccination Against Allergy: Mission Possible?

Vaccines for infectious diseases have improved the life of the human species in a tremendous manner. The principle of vaccination is to establish de novo adaptive immune response consisting of antibody and T cell responses against pathogens which should defend the vaccinated person against future challenge with the culprit pathogen. The situation is completely different for immunoglobulin E (IgE)-associated allergy, an immunologically-mediated hypersensitivity which is already characterized by increased IgE antibody levels and T cell responses against per se innocuous antigens (i.e., allergens). Thus, allergic patients suffer from a deviated hyper-immunity against allergens leading to inflammation upon allergen contact. Paradoxically, vaccination with allergens, termed allergen-specific immunotherapy (AIT), induces a counter immune response based on the production of high levels of allergen-specific IgG antibodies and alterations of the adaptive cellular response, which reduce allergen-induced symptoms of allergic inflammation. AIT was even shown to prevent the progression of mild to severe forms of allergy. Consequently, AIT can be considered as a form of therapeutic vaccination. In this article we describe a strategy and possible road map for the use of an AIT approach for prophylactic vaccination against allergy which is based on new molecular allergy vaccines. This road map includes the use of AIT for secondary preventive vaccination to stop the progression of clinically silent allergic sensitization toward symptomatic allergy and ultimately the prevention of allergic sensitization by maternal vaccination and/or early primary preventive vaccination of children. Prophylactic allergy vaccination with molecular allergy vaccines may allow halting the allergy epidemics affecting almost 30% of the population as it has been achieved for vaccination against infectious diseases.

Recombinant allergens for immunotherapy: state of the art

PURPOSE OF REVIEW

More than 30 years ago, the first molecular structures of allergens were elucidated and defined recombinant allergens became available. We review the state of the art regarding molecular AIT with the goal to understand why progress in this field has been slow, although there is huge potential for treatment and allergen-specific prevention.

RECENT FINDINGS

On the basis of allergen structures, several AIT strategies have been developed and were advanced into clinical evaluation. In clinical AIT trials, promising results were obtained with recombinant and synthetic allergen derivatives inducing allergen-specific IgG antibodies, which interfered with allergen recognition by IgE whereas clinical efficacy could not yet be demonstrated for approaches targeting only allergen-specific T-cell responses. Available data suggest that molecular AIT strategies have many advantages over allergen extract-based AIT.

SUMMARY

Clinical studies indicate that recombinant allergen-based AIT vaccines, which are superior to existing allergen extract-based AIT can be developed for respiratory, food and venom allergy. Allergen-specific preventive strategies based on recombinant allergen-based vaccine approaches and induction of T-cell tolerance are on the horizon and hold promise that allergy can be prevented. However, progress is limited by lack of resources needed for clinical studies, which are necessary for the development of these innovative strategies.

Two years of treatment with the recombinant grass pollen allergy vaccine BM32 induces a continuously increasing allergen-specific IgG4 response

Background

BM32, a grass pollen allergy vaccine containing four recombinant fusion proteins consisting of hepatitis B-derived PreS and hypoallergenic peptides from the major timothy grass pollen allergens adsorbed on aluminium hydroxide has been shown to be safe and to improve clinical symptoms of grass pollen allergy upon allergen-specific immunotherapy (AIT). We have investigated the immune responses in patients from a two years double-blind, placebo-controlled AIT field trial with BM32.

Methods

Blood samples from patients treated with BM32 (n = 27) or placebo (Aluminium hydroxide) (n = 13) were obtained to study the effects of vaccination and natural allergen exposure on allergen-specific antibody, T cell and cytokine responses. Allergen-specific IgE, IgG, IgG₁ and IgG₄ levels were determined by ImmunoCAP and ELISA, respectively. Allergen-specific lymphocyte proliferation by ³H thymidine incorporation and multiple cytokine responses with a human 17-plex cytokine assay were studied in cultured peripheral blood mononuclear cells (PBMCs).

Findings

Two years AIT comprising two courses of 3 pre-seasonal injections of BM32 and a single booster after the first pollen season induced a continuously increasing (year 2 > year 1) allergen-specific IgG₄ response without boosting allergen-specific IgE responses. Specific IgG₄ responses were accompanied by low stimulation of allergen-specific PBMC responses. Increases of allergen-specific pro-inflammatory cytokine responses were absent. The rise of allergen-specific IgE induced by seasonal grass pollen exposure was partially blunted in BM32-treated patients.

Interpretation

AIT with BM32 is characterised by the induction of a non-inflammatory, continuously increasing allergen-specific IgG₄ response (year 2 > year1) which may explain that clinical efficacy was higher in year 2 than in year 1. The good safety profile of BM32 may be explained by lack of IgE reactivity and low stimulation of allergen-specific T cell and cytokine responses.

Fundings

Grants F4605, F4613 and DK 1248-B13 of the Austrian Science Fund (FWF).

Allergen-specific IgE levels and the ability of IgE-allergen complexes to cross-link determine the extent of CD23-mediated T-cell activation

Background

CD23 mediates IgE-facilitated allergen presentation and subsequent allergen-specific T-cell activation in allergic patients.

Objective

We sought to investigate key factors regulating IgE-facilitated allergen presentation through CD23 and subsequent T-cell activation.

Methods

To study T-cell activation by free allergens and different types of IgE–Bet v 1 complexes, we used a molecular model based on monoclonal human Bet v 1–specific IgE, monomeric and oligomeric Bet v 1 allergen, an MHC-matched CD23-expressing B-cell line, and a T-cell line expressing a human Bet v 1–specific T-cell receptor. The ability to cross-link Fcε receptors of complexes consisting of either IgE and monomeric Bet v 1 or IgE and oligomeric Bet v 1 was studied in human FcεRI-expressing basophils. T-cell proliferation by monomeric or oligomeric Bet v 1, which cross-links Fcε receptors to a different extent, was studied in allergic patients’ PBMCs with and without CD23-expressing B cells.

Results

In our model non–cross-linking IgE–Bet v 1 monomer complexes, as well as cross-linking IgE–Bet v 1 oligomer complexes, induced T-cell activation, which was dependent on the concentration of specific IgE. However, T-cell activation by cross-linking IgE–Bet v 1 oligomer complexes was approximately 125-fold more efficient. Relevant T-cell proliferation occurred in allergic patients’ PBMCs only in the presence of B cells, and its magnitude depended on the ability of IgE–Bet v 1 complexes to cross-link CD23.

Conclusion

The extent of CD23-mediated T-cell activation depends on the concentration of allergen-specific IgE and the cross-linking ability of IgE-allergen complexes.

Tracing IgE-Producing Cells in Allergic Patients

Immunoglobulin E (IgE) is the key immunoglobulin in the pathogenesis of IgE associated allergic diseases affecting 30% of the world population. Recent data suggest that allergen-specific IgE levels in serum of allergic patients are sustained by two different mechanisms: inducible IgE production through allergen exposure, and continuous IgE production occurring even in the absence of allergen stimulus that maintains IgE levels. This assumption is supported by two observations. First, allergen exposure induces transient increases of systemic IgE production. Second, reduction in IgE levels upon depletion of IgE from the blood of allergic patients using immunoapheresis is only temporary and IgE levels quickly return to pre-treatment levels even in the absence of allergen exposure. Though IgE production has been observed in the peripheral blood and locally in various human tissues (e.g., nose, lung, spleen, bone marrow), the origin and main sites of IgE production in humans remain unknown. Furthermore, IgE-producing cells in humans have yet to be fully characterized. Capturing IgE-producing cells is challenging not only because current staining technologies are inadequate, but also because the cells are rare, they are difficult to discriminate from cells bearing IgE bound to IgE-receptors, and plasma cells express little IgE on their surface. However, due to the central role in mediating both the early and late phases of allergy, free IgE, IgE-bearing effector cells and IgE-producing cells are important therapeutic targets. Here, we discuss current knowledge and unanswered questions regarding IgE production in allergic patients as well as possible therapeutic approaches targeting IgE.

Molecular Approaches for Diagnosis, Therapy and Prevention of Cow´s Milk Allergy

Cow´s milk is one of the most important and basic nutrients introduced early in life in our diet but can induce IgE-associated allergy. IgE-associated allergy to cow´s milk can cause severe allergic manifestations in the gut, skin and even in the respiratory tract and may lead to life-threatening anaphylactic shock due to the stability of certain cow´s milk allergens. Here, we provide an overview about the allergen molecules in cow´s milk and the advantages of the molecular diagnosis of IgE sensitization to cow´s milk by serology. In addition, we review current strategies for prevention and treatment of cow´s milk allergy and discuss how they could be improved in the future by innovative molecular approaches that are based on defined recombinant allergens, recombinant hypoallergenic allergen derivatives and synthetic peptides.

Atopy and Sensitization to Allergens Known to Cause Systemic Contact Dermatitis

BACKGROUND

Atopic dermatitis (AD) associated with respiratory atopy may represent a form of systemic contact dermatitis (SCD), whereby AD flares after ingestion or inhalation of allergens.

OBJECTIVE

The aim of the study was to compare the prevalence of positive patch tests to allergens known to cause SCD in AD patients with and without respiratory atopy.

METHODS

This is a retrospective study of patients with AD patch tested to 23 allergens known to cause SCD. Positive patch tests were compared between AD patients with and without respiratory atopy, stratified by age and wet or dry work occupation.

CONCLUSIONS

Children and adolescents, but not adults, with AD and respiratory atopy were more likely than age-matched AD patients without respiratory atopy to have positive patch tests to these allergens (odds ratio, 2.33; 95% confidence interval, 1.13-4.79). Moreover, AD patients with respiratory atopy and engaging in wet work, but not dry work, occupations were more likely than AD patients without respiratory atopy to have positive patch tests to allergens known to cause SCD (odds ratio, 1.47; 95% confidence interval, 1.05-2.06). Thus, respiratory atopy and wet work are associated with sensitization to allergens known to cause SCD in patients with AD, and patch testing may be valuable in identifying systemic triggers of dermatitis in these patients.

The antimicrobial protein S100A12 identified as a potential autoantigen in a subgroup of atopic dermatitis patients

Background

Atopic dermatitis (AD) is a complex heterogeneous chronic inflammatory skin disease. Specific IgE antibodies against autoantigens have been observed in a subgroup of AD patients, however, little is known about IgG-auto-reactivity in AD. To investigate the presence of autoreactive IgG antibodies, we performed autoantibody profiling of IgG in patients with AD of different severities and in healthy controls (HC).

Methods

First, we performed an untargeted screening in plasma samples from 40 severe AD (sAD) patients and 40 HC towards 1152 protein fragments on planar antigen microarrays. Next, based on the findings and addition of more fragments, a targeted antigen suspension bead array was designed to profile a cohort of 50 sAD patients, 123 patients with moderate AD (mAD), and 84 HC against 148 protein fragments representing 96 unique proteins.

Results

Forty-nine percent of the AD patients showed increased IgG-reactivity to any of the four antigens representing keratin associated protein 17-1 (KRTAP17-1), heat shock protein family A (Hsp70) member 4 (HSPA4), S100 calcium binding proteins A12 (S100A12), and Z (S100Z). The reactivity was more frequent in the sAD patients (66%) than in those with mAD (41%), whereas only present in 25% of the HC. IgG-reactivity to S100A12, a protein including an antimicrobial peptide, was only observed in AD patients (13/173).

Conclusions

Autoantibody profiling of IgG-reactivity using microarray technology revealed an autoantibody-based subgroup in patients with AD. The four identified autoantigens and especially S100A12 could, if characterized further, increase the understanding of different pathogenic mechanisms behind AD and thereby enable better treatment.

Electronic supplementary material

The online version of this article (10.1186/s13601-019-0240-4) contains supplementary material, which is available to authorized users.

Next generation immunotherapy for tree pollen allergies

Tree pollen induced allergies are one of the major medical and public health burdens in the industrialized world. Allergen-Specific Immunotherapy (AIT) through subcutaneous injection or sublingual delivery is the only approved therapy with curative potential to pollen induced allergies. AIT often is associated with severe side effects and requires long-term treatment. Safer, more effective and convenient allergen specific immunotherapies remain an unmet need. In this review article, we discuss the current progress in applying protein and peptide-based approaches and DNA vaccines to the clinical challenges posed by tree pollen allergies through the lens of preclinical animal models and clinical trials, with an emphasis on the birch and Japanese red cedar pollen induced allergies.

Molecular Aspects of Allergens and Allergy

Immunoglobulin E (IgE)-associated allergy is the most common immune disorder. More than 30% of the population suffer from symptoms of allergy which are often severe, disabling, and life threatening such as asthma and anaphylaxis. Population-based birth cohort studies show that up to 60% of the world population exhibit IgE sensitization to allergens, of which most are protein antigens. Thirty years ago the first allergen-encoding cDNAs have been isolated. In the meantime, the structures of most of the allergens relevant for disease in humans have been solved. Here we provide an update regarding what has been learned through the use of defined allergen molecules (i.e., molecular allergology) and about mechanisms of allergic disease in humans. We focus on new insights gained regarding the process of sensitization to allergens, allergen-specific secondary immune responses, and mechanisms underlying allergic inflammation and discuss open questions. We then show how molecular forms of diagnosis and specific immunotherapy are currently revolutionizing diagnosis and treatment of allergic patients and how allergen-specific approaches may be used for the preventive eradication of allergy.

Molecular aspects of allergens in atopic dermatitis

PURPOSE OF REVIEW

Molecular allergology uses pure, mainly recombinant and structurally defined allergen molecules and allergen-derived epitopes to study mechanisms of IgE-associated allergy, to diagnose, and even predict the development of allergic manifestations and to treat and prevent IgE-associated allergies. Atopic dermatitis, a chronic inflammatory skin disease is almost always associated with IgE sensitization to allergens. However, also non-IgE-mediated pathomechanisms seem to be operative in atopic dermatitis and it is often difficult to identify the disease-causing allergens. Here we review recent work showing the usefulness of molecular allergology to study mechanisms of atopic dermatitis, for diagnosis and eventually for treatment and prevention of atopic dermatitis.

RECENT FINDINGS

IgE sensitization to airborne, food-derived, microbial allergens, and autoallergens has been found to be associated with atopic dermatitis. Using defined allergen molecules and non-IgE-reactive allergen derivatives, evidence could be provided for the existence of IgE- and non-IgE-mediated mechanisms of inflammation in atopic dermatitis. Furthermore, effects of epicutaneous allergen administration on systemic allergen-specific immune responses have been studied. Multi-allergen tests containing micro-arrayed allergen molecules have been shown to be useful for the identification of culprit allergens in atopic dermatitis and may improve the management of atopic dermatitis by allergen-specific immunotherapy, allergen avoidance, and IgE-targeting therapies in a personalized medicine approach.

SUMMARY

Molecular allergology allows for dissection of the pathomechanisms of atopic dermatitis, provides new forms of allergy diagnosis for identification of disease-causing allergens, and opens the door to new forms of management by allergen-specific and T cells-targeting or IgE-targeting interventions in a personalized medicine approach.

Single recombinant and purified major allergens and peptides: How they are made and how they change allergy diagnosis and treatment

Objective

To review the current knowledge regarding recombinant and purified allergens and allergen-derived peptides.

Data Sources

PubMed, homepages relevant to the topic, and the National Institutes of Health clinical trial database were searched.

Study Selections

The literature was screened for studies describing purified and recombinant allergens and allergen-derived peptides. Studies relevant to the topic were included in this review.

Results

Advantages and drawbacks of pure and defined recombinant allergens and peptides over allergen extracts in the context of allergy research, diagnosis, and allergen immunotherapy are discussed. We describe how these molecules are manufactured, which products are currently available on the market, and what the regulative issues are. We furthermore provide an overview of clinical studies with vaccines based on recombinant allergens and synthetic peptides. The possibility of prophylactic vaccination based on recombinant fusion proteins consisting of viral carrier proteins and allergen-derived peptides without allergenic activity are also discussed.

Conclusion

During the last 25 years more than several hundred allergen sequences were determined, which led to a production of recombinant allergens that mimic biochemically and immunologically their natural counterparts. Especially in Europe, recombinant allergens are increasingly replacing allergen extracts in diagnosis of allergy. Despite many challenges, such as high cost of clinical trials and regulative issues, allergy vaccines based on recombinant allergens and peptides are being developed and will likely soon be available on the market.

Epicutaneous allergen application preferentially boosts specific T cell responses in sensitized patients

The effects of epicutaneous allergen administration on systemic immune responses in allergic and non-allergic individuals has not been investigated with defined allergen molecules. We studied the effects of epicutaneous administration of rBet v 1 and rBet v 1 fragments on systemic immune responses in allergic and non-allergic subjects. We conducted a clinical trial in which rBet v 1 and two hypoallergenic rBet v 1 fragments were applied epicutaneously by atopy patch testing (APT) to 15 birch pollen (bp) allergic patients suffering from atopic dermatitis, 5 bp-allergic patients suffering from rhinoconjunctivitis only, 5 patients with respiratory allergy without bp allergy and 5 non-allergic individuals. Epicutaneous administration of rBet v 1 and rBet v 1 fragments led to strong and significant increases of allergen-specific T cell proliferation (CLA+ and CCR4+T cell responses) only in bp-allergic patients with a positive APT reaction. There were no relevant changes of Bet v 1-specific IgE and IgG responses. No changes were noted in allergic subjects without bp allergy and in non-allergic subjects. Epicutaneous allergen application boosts specific T cell but not antibody responses mainly in allergic, APT-positive patients suggesting IgE-facilitated allergen presentation as mechanism for its effects on systemic allergen-specific immune responses.

Advances in atopic dermatitis in 2015

This review aims to highlight recently published articles on atopic dermatitis (AD). Updated are the insights into epidemiology, pathology, diagnostics, and therapy. Epidemiologic studies have revealed a positive correlation between AD and systemic conditions, such as rheumatoid arthritis, inflammatory bowel disease, and neonatal adiposity. Pathologic findings highlight the involvement of novel barrier factors (desmoplakin and claudin), novel immune cell subsets (pathogenic effector T_H2 cells and group 2 innate lymphoid cells), and differential skewing of helper T cells (eg, T_H17 dominance in Asians with AD). As diagnostics, noninvasive examinations of the transepidermal water loss of neonates, the density of epidermal Staphylococcus species, and the gut flora might prognosticate the onset of AD. As for therapy, various methods are proposed, including conventional (petrolatum and UV) and molecule-oriented regimens targeting Janus kinase, signal transducer and activator of transcription 3, extracellular signal-regulated kinase, sirtuin 1, or aryl hydrocarbon receptor.

Recombinant allergy vaccines based on allergen-derived B cell epitopes

Immunoglobulin E (IgE)-associated allergy is the most common immunologically-mediated hypersensitivity disease. It affects more than 25% of the population. In IgE-sensitized subjects, allergen encounter can causes a variety of symptoms ranging from hayfever (allergic rhinoconjunctivitis) to asthma, skin inflammation, food allergy and severe life-threatening anaphylactic shock. Allergen-specific immunotherapy (AIT) is based on vaccination with the disease-causing allergens. AIT is an extremely effective, causative and disease-modifying treatment. However, administration of natural allergens can cause severe side effects and the quality of natural allergen extracts limits its application. Research in the field of molecular allergen characterization has allowed deciphering the molecular structures of the disease-causing allergens and it has become possible to engineer novel molecular allergy vaccines which precisely target the mechanisms of the allergic immune response and even appear suitable for prophylactic allergy vaccination. Here we discuss recombinant allergy vaccines which are based on allergen-derived B cell epitopes regarding their molecular and immunological properties and review the results obtained in clinical studies with this new type of allergy vaccines.

Circulating CLA+ T cells in atopic dermatitis and their possible role as peripheral biomarkers

Cutaneous lymphocyte-associated antigen (CLA⁺ ) T cells are specialized for skin homing and represent the main T-cell population in atopic dermatitis (AD) lesions. CLA⁺ is expressed on the surface of circulating CD45RO⁺ memory T cells and most skin-infiltrating T cells. Mechanistic studies and thus treatment advancements are limited by the need of large number of skin biopsies. Circulating CLA⁺ T cells may be a reliable surrogate marker of the inflammatory events occurring in the skin, and thus, the evaluation of CLA⁺ T cells in the blood may eliminate the need for skin biopsies. Preliminary work in AD has established that disease-associated T-cell abnormalities can be approached by either a study of skin lesions or activated CLA⁺ T-cell subsets in peripheral blood. Future studies in adults and children, across different skin disorders, correlating blood and skin phenotypes and determining skin-homing T-cell functional properties are needed to establish whether CLA⁺ memory subsets can be used as biomarkers and a substitute for skin biopsies. This review summarizes the latest advancements reached on circulating CLA⁺ in AD and the great potential they harbor in understanding AD mechanisms.

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

BACKGROUND

We 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.

METHODS

We 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.

RESULTS

Sixty-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).

CONCLUSION

The 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.).

Potential of nanoparticles for allergen-specific immunotherapy - use of silica nanoparticles as vaccination platform

INTRODUCTION

Allergen-specific immunotherapy is the only curative approach for the treatment of allergies. There is an urgent need for improved therapies, which increase both, efficacy and patient compliance. Novel routes of immunization and the use of more advanced vaccine platforms have gained heightened interest in this field. Areas covered: The current status of allergen-specific immunotherapy is summarized and novel routes of immunization and their challenges in the clinics are critically discussed. The use of nanoparticles as novel delivery system for allergy vaccines is comprehensively reviewed. Specifically, the advantages of silica nanoparticles as vaccine carriers and adjuvants are summarized. Expert opinion: Future allergen-specific immunotherapy will combine engineered hypoallergenic vaccines with novel routes of administration, such as the skin. Due to their biodegradability, and the easiness to introduce surface modifications, silica nanoparticles are promising candidates for tailor-made vaccines. By covalently linking allergens and polysaccharides to silica nanoparticles, a versatile vaccination platform can be designed to specifically target antigen-presenting cells, render the formulation hypoallergenic, and introduce immunomodulatory functions. Combining potent skin vaccination methods, such as fractional laser ablation, with nanoparticle-based vaccines addresses all the requirements for safe and efficient therapy of allergic diseases.

Vaccine development for allergen-specific immunotherapy based on recombinant allergens and synthetic allergen peptides: Lessons from the past and novel mechanisms of action for the future

In the past, the development of more effective, safe, convenient, broadly applicable, and easy to manufacture vaccines for allergen-specific immunotherapy (AIT) has been limited by the poor quality of natural allergen extracts. Progress made in the field of molecular allergen characterization has now made it possible to produce defined vaccines for AIT and eventually for preventive allergy vaccination based on recombinant DNA technology and synthetic peptide chemistry. Here we review the characteristics of recombinant and synthetic allergy vaccines that have reached clinical evaluation and discuss how molecular vaccine approaches can make AIT more safe and effective and thus more convenient. Furthermore, we discuss how new technologies can facilitate the reproducible manufacturing of vaccines of pharmaceutical grade for inhalant, food, and venom allergens. Allergy vaccines in clinical trials based on recombinant allergens, recombinant allergen derivatives, and synthetic peptides allow us to target selectively different immune mechanisms, and certain of those show features that might make them applicable not only for therapeutic but also for prophylactic vaccination.

IgE Sensitization Profiles Differ between Adult Patients with Severe and Moderate Atopic Dermatitis

Background

Atopic dermatitis (AD) is a complex chronic inflammatory disease where allergens can act as specific triggering factors.

Aim

To characterize the specificities of IgE-reactivity in patients with AD to a broad panel of exogenous allergens including microbial and human antigens.

Methodology

Adult patients with AD were grouped according to the SCORAD index, into severe (n = 53) and moderate AD (n = 126). As controls 43 patients were included with seborrhoeic eczema and 97 individuals without history of allergy or skin diseases. Specific IgE reactivity was assessed in plasma using Phadiatop^®, ImmunoCap^™, micro-arrayed allergens, dot-blotted recombinant Malassezia sympodialis allergens, and immune-blotted microbial and human proteins.

Results

IgE reactivity was detected in 92% of patients with severe and 83% of patients with moderate AD. Sensitization to cat allergens occurred most frequently, followed by sensitization to birch pollen, grass pollen, and to the skin commensal yeast M. sympodialis. Patients with severe AD showed a significantly higher frequency of IgE reactivity to allergens like cat (rFel d 1) and house dust mite (rDer p 4 and 10), to Staphylococcus aureus, M. sympodialis, and to human antigens. In contrast, there were no significant differences in the frequencies of IgE reactivity to the grass pollen allergens rPhl p 1, 2, 5b, and 6 between the two AD groups. Furthermore the IgE reactivity profile of patients with severe AD was more spread towards several different allergen molecules as compared to patients with moderate AD.

Conclusion

We have revealed a hitherto unknown difference regarding the molecular sensitization profile in patients with severe and moderate AD. Molecular profiling towards allergen components may provide a basis for future investigations aiming to explore the environmental, genetic and epigenetic factors which could be responsible for the different appearance and severity of disease phenotypes in AD.

The adaptive immune system in atopic dermatitis and implications on therapy

In atopic dermatitis (AD), the skin inflammation is believed to occur due to a misdirected immune reaction against harmless antigens on the one hand, and to a disturbed skin barrier on the other. In recent years, vast efforts have been made to investigate the relevance and details of the immune response to allergens. Clinically, it was demonstrated for the first time that aeroallergen exposure leads to worsening of AD symptoms. An overexpression of Th2 cytokines has been observed in acute and subacute lesions of AD. The clinical impact of the key Th2 cytokines IL-4 and IL-13 on atopic dermatitis has recently been shown in clinical studies with dupilumab, a monoclonal antibody which blocks the IL-4/IL-13 receptor. In vitro data indicate, however, that the T cell response is not solely Th2-polarized but may lead to heterogeneous cytokine production involving IFN-γ and IL-17 in an allergen-dependent manner. Classical thymus-derived Foxp3 T cells have interestingly been detected in elevated numbers in the circulation of AD patients. Therapeutic approaches with allergen specific immunotherapy aim to induce regulatory T cells of the Tr1 type. The strikingly altered microbiome of AD skin with diminished diversity of bacteria on lesional skin but increases of S. aureus colonization and the sensitization against microbial allergens and homologue self-proteins deserve special attention. For the treatment of itch symptoms, which still represent a challenge in daily practice, promising data have been published on the relevance of the H(histamine)4-receptor and on mediators such as IL-31, TSLP.