Predominant Api m 10 sensitization as risk factor for treatment failure in honey bee venom immunotherapy

Clinical features, severity, and immunological changes during venom immunotherapy in children and adults

Background: Hymenoptera venom allergy (HVA) is among the most common causes of severe allergic reactions worldwide. Objective: To investigate clinical features and factors that affect the severity of HVA and to determine the alterations in immunologic biomarkers after venom immunotherapy (VIT). Methods: Seventy-six adults and 36 children were prospectively investigated. We analyzed specific immunoglobulin E (sIgE) and sIgG4 levels of venom extracts and components (rApi m1, rApi m10, rVes v1, rVes v5, rPol d5) before and after the first year of VIT. Results: Although cardiovascular symptoms were more common in adults (p < 0.001), the skin was the most affected organ in children (p = 0.009). Serum basal tryptase (sBT) levels were higher in the adults than the children (p < 0.001). The absence of urticaria (odds ratio [OR] 4.208 [95% confidence interval {CI}, 1.395-12.688]; p = 0.011) and sBT ≥ 5.2 ng/mL (OR 11.941 [95% CI, 5.220-39.733]; p < 0.001) were found as the risk factors for grade IV reactions. During VIT, changes in sIgE levels were variable. In the Apis VIT group, we observed remarkable increases in sIgG4 levels in Apis extract and rApi m1 but not in Api m10. Vespula extract, rVes v1, and rVes v5 sIgG4 levels were significantly increased in Vespula VIT group, we also detected significant increases in the Polistes extract and rPol d5 sIgG4 levels, which were not observed in the Apis VIT group. In the patients who received both Apis and Vespula VIT, increases in sIgG4 levels were observed for both venoms. Conclusion: Adults and children can have different clinical patterns. After 1 year, VIT induced a strong IgG4 response. Although Apis immunotherapy (IT) induced Apis sIgG4, excluding Api m10, Vespula IT induced both Vespula and Polistes sIgG4.

Potential and limitations of epitope mapping and molecular targeting in Hymenoptera venom allergy

Hymenoptera venom (HV) allergy can lead to life threatening conditions by specific IgE (sIgE)-mediated anaphylactic reactions. The knowledge about major allergens from venom of different clinically relevant species increased in the last decades, allowing the development of component-resolved diagnostics in which sIgE to single allergens is analysed. Despite these advances, the precise regions of the allergens that bind to IgE are only known for few HV allergens. The detailed characterization of IgE epitopes may provide valuable information to improve immunodiagnostic tests and to develop new therapeutic strategies using allergen-derived peptides or other targeted approaches. Epitope-resolved analysis is challenging, since the identification of conformational epitopes present in many allergens demands complex technologies for molecular analyses. Furthermore, functional analysis of the epitopeś interaction with their respective ligands is needed to distinguish epitopes that can activate the allergic immune response, from those that are recognized by irrelevant antibodies or T cell receptors from non-effector cells. In this review, we focus on the use of mapping and molecular targeting approaches for characterization of the epitopes of the major venom allergens of clinically relevant Hymenoptera species. The screening of the most relevant allergen peptides by epitope mapping could be helpful for the development of molecules that target major and immunodominant epitopes blocking the allergen induced cellular reactions as novel approach for the treatment of HV allergy.

Revealing clinically relevant specific IgE sensitization patterns in Hymenoptera venom allergy with dimension reduction and clustering

Background

Immunoglobulin E (IgE) blood tests are used to detect sensitizations and potential allergies. Recent studies suggest that specific IgE sensitization patterns due to molecular interactions affect an individual's risk of developing allergic symptoms.

Objective

The aim of this study was to reveal specific IgE sensitization patterns and investigate their clinical implications in Hymenoptera venom allergy.

Methods

In this cross-sectional study, 257 hunters or fishers with self-filled surveys on previous Hymenoptera stings were analyzed. Blood samples were taken to determine Hymenoptera IgE sensitization levels. Using dimensionality reduction and clustering, specific IgE for 10 Hymenoptera venom allergens were evaluated for clinical relevance.

Results

Three clusters were unmasked using novel dimensionality reduction and clustering methods solely based on specific IgE levels to Hymenoptera venom allergens. These clusters show different characteristics regarding previous systemic reactions to Hymenoptera stings.

Conclusion

Our study was able to unmask non-linear sensitization patterns for specific IgE tests in Hymenoptera venom allergy. We were able to derive risk clusters for anaphylactic reactions following hymenoptera stings and pinpoint relevant allergens (rApi m 10, rVes v 1, whole bee, and wasp venom) for clustering.

Venom Anaphylaxis: Decision Points for a More Aggressive Workup

Diagnostic testing of patients who present for evaluation of insect venom allergy can involve many levels of investigation. A detailed initial history is critical for diagnosis and prognosis. The severity of previous sting reactions and the presence or absence of urticaria or hypotension predict severe future sting reactions and underlying mast cell disorders. Venom skin tests and specific IgE measurement can confirm the diagnosis but have limited positive predictive value for the frequency and severity of future sting reactions. Testing for serum IgE to recombinant venom component allergens can distinguish true allergy from cross-reactivity to honey bee and yellowjacket venoms. Basophil activation tests can improve the detection of venom allergy and predict the severity of reactions and the efficacy of venom immunotherapy but are limited in availability. An elevated basal serum tryptase level is an important marker for severe sting anaphylaxis and underlying mast cell disorders (eg, hereditary α-tryptasemia and clonal mast cell disease). When there is high suspicion (eg, using the Red Espanola de Mastocytosis score), bone marrow biopsy is the definitive tool to characterize mast cell disorders that are associated with the most severe outcomes in patients with insect sting allergy.

Real-World Safety and Efficacy Clinical Data of an Improved Allergen-Specific Immunotherapy Product for the Treatment of Bee Venom Allergy

The aim of this study is to explore the safety and efficacy of bee venom immunotherapy without HSA, in real-life patients. Methods: This is an observational retrospective study developed in seven hospitals in Spain, where patients treated with this immunotherapy were included. They gathered the protocol used to initiate the immunotherapy, adverse reactions, field re-stings, and the patient clinical data (clinical history, biomarkers, and skin prick test). Results: A total of 108 patients were included. In total, 4 protocols were used (5 weeks reaching 200 μg, and 4, 3, and 2 weeks reaching 100 μg). An incidence of systemic adverse reactions for each 100 injections of 1.5, 1.7, 0, and 0.58, respectively, was found. The demographic data showed not to directly affect the appearance of adverse reactions, except for those having a grade 2 systemic reaction with immunotherapy previously had a grade 4 systemic reaction; the IgE to Apis mellifera was 3 times higher in patients with systemic reactions of grade 1 than in the general group, and other specific IgEs were lower in those with systemic reactions. Most of the patients recognized Api m 1 followed by Api m 10. In the sample, 32% experienced spontaneous re-stings, without presenting systemic reactions, after a year of treatment.

Molecular diagnostics and inhibition of cross‐reactive carbohydrate determinants in Hymenoptera venom allergy

Background

The composition of venom extracts, cross‐reactive carbohydrate determinants (CCD) and the component‐resolved diagnostics (CRD) are important fields of investigation. IgE‐reactivity to CCD complicates the interpretation of IgE to Hymenoptera venoms, especially in patients with multiple‐positivity. We analyzed the clinical importance of CRD and CCD‐inhibition for selection of allergens for venom immunotherapy (VIT).

Methods

In 71 patients, we measured specific IgE (sIgE) to honeybee venom (HBV), wasp venom (WV), hornet venom (HV), CCD, and recombinant allergens: phospholipase A2 (rApi m 1), hyaluronidase (rApi m 2), icarapin (rApi m 10), antigen 5 (rVes v 5), and phospholipase A1 (Immunoblot). In 29/71 HBV/WV/HV/CCD‐positive patients CCD‐inhibition was performed. According to CRD and CCD‐inhibition, we identified true sensitization and defined groups of multiple‐positive patients who needed CCD‐inhibition before starting VIT.

Results

sIgE‐rApi m 1, sIgE‐rApi m 2, and sIgE‐rApi m 10 were detected in 65.7%, 68.4%, and 58%, respectively. In HBV allergic patients, CRD sensitivity was 86.8%. In WV allergic patients, sensitivity of sIgE‐rVes v 5 was 94%. True multiple‐sensitization was found in 44.8% of HBV/WV/HV/CCD‐positive patients after CCD‐inhibition. Patients with multiple venom‐ and CCD‐positivity had more frequent severe allergic reactions (p < 0.001). CCD‐inhibition was helpful in HBV/WV/HV/CCD‐positive patients who were negative to all tested recombinant honeybee allergens. Persistence of HBV‐positivity after CCD‐inhibition requires CRD to other honeybee recombinant allergens.

Conclusion

CRD, using a profile of five most important recombinant allergens and CCD, has a high sensitivity for the diagnosis of venom allergy, especially in patients positive to several venom extracts. CRD and CCD‐inhibition are helpful to reveal the clinically relevant, true sensitization and improve the selection of venoms for long‐lasting VIT.

EAACI Molecular Allergology User's Guide 2.0

Since the discovery of immunoglobulin E (IgE) as a mediator of allergic diseases in 1967, our knowledge about the immunological mechanisms of IgE-mediated allergies has remarkably increased. In addition to understanding the immune response and clinical symptoms, allergy diagnosis and management depend strongly on the precise identification of the elicitors of the IgE-mediated allergic reaction. In the past four decades, innovations in bioscience and technology have facilitated the identification and production of well-defined, highly pure molecules for component-resolved diagnosis (CRD), allowing a personalized diagnosis and management of the allergic disease for individual patients. The first edition of the "EAACI Molecular Allergology User's Guide" (MAUG) in 2016 rapidly became a key reference for clinicians, scientists, and interested readers with a background in allergology, immunology, biology, and medicine. Nevertheless, the field of molecular allergology is moving fast, and after 6 years, a new EAACI Taskforce was established to provide an updated document. The Molecular Allergology User's Guide 2.0 summarizes state-of-the-art information on allergen molecules, their clinical relevance, and their application in diagnostic algorithms for clinical practice. It is designed for both, clinicians and scientists, guiding health care professionals through the overwhelming list of different allergen molecules available for testing. Further, it provides diagnostic algorithms on the clinical relevance of allergenic molecules and gives an overview of their biology, the basic mechanisms of test formats, and the application of tests to measure allergen exposure.

Allergic March in Children: The Significance of Precision Allergy Molecular Diagnosis (PAMD@) in Predicting Atopy Development and Planning Allergen-Specific Immunotherapy

The allergic march is a progression of naturally occurring symptoms whose nature changes with age. The classic allergic march typically begins in infancy and manifests in the form of atopic dermatitis and food allergy. As immune tolerance develops over time, these conditions may resolve by the age of 3-5 years; however, they may evolve into allergic rhinitis and bronchial asthma. Traditional diagnostic assessments, such as skin prick testing or serum allergen-specific immunoglobulin E (sIgE) level testing, are conducted to introduce effective treatment. Recent years saw the emergence of precision allergy molecular diagnosis (PAMD@), which assesses sIgE against allergenic molecules. This new technology helps more accurately evaluate the patient's allergy profile, which helps create more precise dietary specifications and personalize allergen-specific immunotherapy. This review presents possible predictions regarding the allergic march and the means of controlling it based on PAMD@ results.

Diagnosis of Apis dorsata venom allergy: use of recombinant allergens of Apis mellifera and a passive basophil activation test

Background

Allergy to Apis dorsata (Giant Asian Honeybee) venom is the commonest insect allergy in Sri Lanka and South East Asia. However, laboratory diagnosis is difficult as the pure venom and diagnostic reagents are not commercially available.

Objective

This study assessed the use of four recombinant allergens of A. mellifera venom and the passive basophil activation test in the diagnosis of A. dorsata venom anaphylaxis.

Methods

Serum IgE levels to four recombinant allergens of A. mellifera, rApi m 1, 2, 5 and 10 were assessed and compared with serum IgE to the crude venom of A. mellifera or V. vulgaris by Phadia ImmunoCAP, in patients who developed anaphylaxis to A. dorsata stings. Basophil activation in response to venom of A. dorsata or V. affinis was assessed using a passive basophil activation test. Association of the severity of the reaction with basophil activation was compared.

Results

rApi m 1 and 10 combinedly had significant correlation (r = 0.722; p < 0.001) with the crude venom of A. mellifera (Western honeybee) and a higher positivity rate of 90% (27/30). Whereas, IgE reactivity to rApi m 2 or 5 had significant correlation (p = 0.02 and p = 0.005 respectively) with V. vulgaris crude venom. All 30 (100%) were positive to A. dorsata venom in passive BAT; 70% (21/30) had over 80% activation, 96.7% (29/30) had over 60% activation and 100% had over 50% activation. Percentage activation of basophils in patients who had mild or moderate reactions (n = 20) was significantly low (p = 0.02) from that of patients who had severe reactions (n = 10).

Conclusions

rApi m 1 and 10 when combined was sensitive for the diagnosis of A. dorsata allergy. This combination had the lowest cross-reactivity rate with Vespula vulgaris. The passive BAT is highly sensitive in A. dorsata allergy. The basophil reactivity was significantly higher in severe anaphylaxis compared to mild/moderate anaphylaxis. This finding should be further explored in further studies.

Diagnosis of Hymenoptera Venom Allergy: State of the Art, Challenges, and Perspectives

Hymenoptera venom allergy is the most common cause of anaphylaxis in adults and the second-most frequent in children. The proper diagnosis of this life-threatening allergy remains a challenge. This review focuses on the current knowledge regarding diagnostics of Hymenoptera venom allergy. The paper includes a brief description of the representatives of Hymenoptera order and the composition of their venoms. Then, diagnostic tests for allergy to Hymenoptera venom are described. Common diagnostic problems, especially double positivity in tests for IgE antibodies specific to honeybee and wasp venom, are also discussed. Special attention is paid to the search for new diagnostic capabilities using modern methodologies. Multidimensional molecular analysis offers an opportunity to characterize changes in body fluids associated with Hymenoptera venom allergy and yields a unique insight into the cell status. Despite recent developments in the diagnostics of Hymenoptera venom allergy, new testing methodologies are still needed to answer questions and doubts we have.

Allergen Content of Therapeutic Preparations for Allergen-Specific Immunotherapy of European Paper Wasp Venom Allergy

Allergy to Polistes dominula (European paper wasp) venom is of particular relevance in Southern Europe, potentially becoming a threat in other regions in the near future, and can be effectively cured by venom immunotherapy (VIT). As allergen content in extracts may vary and have an impact on diagnostic and therapeutic approaches, the aim was to compare five therapeutic preparations for VIT of P. dominula venom allergy available in Spain. Products from five different suppliers were analyzed by SDS-PAGE and LC-MS/MS and compared with a reference venom sample. Three products with P. dominula venom and one product with a venom mixture of American Polistes species showed a comparable band pattern in SDS-PAGE as the reference sample and the bands of the major allergens phospholipase A1 and antigen 5 were assignable. The other product, which consists of a mixture of American Polistes species, exhibited the typical band pattern in one, but not in another sample from a second batch. All annotated P. dominula allergens were detected at comparable levels in LC-MS/MS analysis of products containing P. dominula venom. Due to a lack of genomic information on the American Polistes species, the remaining products were not analyzed by this method. The major Polistes allergens were present in comparable amounts in the majority, but not in all investigated samples of venom preparations for VIT of P. dominula venom allergy.

Component-Resolved Evaluation of the Risk and Success of Immunotherapy in Bee Venom Allergic Patients

Venom immunotherapy (VIT) is the only efficient therapy for the Hymenoptera insect venom allergy. Immunotherapy with bee venom is encumbered with a higher risk of systemic side effects and/or therapeutic failures. The objective of the study was to assess if specific profiles of molecular IgE (Immunoglobulin E) responses are associated with an increased risk of systemic side effects and/or the treatment’s inefficacy. The study group numbered 64 bee venom allergic patients (BVA) who received venom immunotherapy modo ultra-rush (VIT-UR), (f/m: 32/32, mean age 43.4 ± 17.2). In total, 54.84% of them manifested allergic reactions of grades I-III (acc. to Mueller’s scale), while 48.66% manifested reactions of grade IV. In all the patients, IgE against bee venom extract, rApi m 1 and tryptase (sBT) were assessed. In 46 patients, assessments of IgE against rApi m 2, 3, 5, 10 were also performed. BVA patients manifesting cardiovascular symptoms (SYS IV0) showed higher levels of both sIgE-rApi m 5 (p = 0.03) and tryptase (p = 0.07) than patients with SYS I−III. Systemic adverse events during VIT with bee venom were more frequent in the induction phase than in the maintenance phase: 15.22% vs. 8.7%. In BVA patients who experienced systemic adverse events during VIT, higher concentrations of sIgE-rApi m 5 (p < 0.05), rApi m 1 (p = 0.009), and sBT (p = 0.019) were demonstrated. We conclude that higher levels of sIgE against rApi m 1, rApi m 5, and tryptase many constitute a potential marker of the severity of allergic reactions and therapeutic complications that can occur during VIT with bee venom.

Precision medicine in the allergy clinic: the application of component resolved diagnosis

INTRODUCTION

A precise diagnosis is key for the optimal management of allergic diseases and asthma. In vivo or in vitro diagnostic methods that use allergen extracts often fail to identify the molecules eliciting the allergic reactions.

AREAS COVERED

Component-resolved diagnosis (CRD) has solved most of the limitations of extract-based diagnostic procedures and is currently valuable tool for the precision diagnosis in the allergy clinic, for venom and food allergy, asthma, allergic rhinitis, and atopic dermatitis. Its implementation in daily practice facilitates: a) the distinction between genuine multiple sensitizations and cross-reactive sensitization in polysensitized patients; b) the prediction of a severe, systemic reaction in food or insect venom allergy; c) the optimal selection of allergen immunotherapy based on the patient sensitization profile. This paper describes its main advantages and disadvantages, cost-effectiveness and future perspectives.

EXPERT OPINION

The diagnostic strategy based on CRD is part of the new concept of precision immunology, which aims to improve the management of allergic diseases.

Molecular allergology and its impact in specific allergy diagnosis and therapy

Progressive knowledge of allergenic structures resulted in a broad availability of allergenic molecules for diagnosis. Component-resolved diagnosis allowed a better understanding of patient sensitization patterns, facilitating allergen immunotherapy decisions. In parallel to the discovery of allergenic molecules, there was a progressive development of a regulation framework that affected both in vitro diagnostics and Allergen Immunotherapy products. With a progressive understanding of underlying mechanisms associated to Allergen immunotherapy and an increasing experience of application of molecular diagnosis in daily life, we focus in analyzing the evidences of the value provided by molecular allergology in daily clinical practice, with a focus on Allergen Immunotherapy decisions.

Anaphylaxis to Stinging Insect Venom

Hymenoptera stinging insects are common culprits for allergic reactions. Anaphylaxis to insect stings can be life threatening and is associated with a significant risk of recurrence. Insect allergy requires referral to an allergist/immunologist for education and for diagnostic evaluation that will direct further management and treatment. Venom immunotherapy is safe and effective; it prevents sting anaphylaxis in up to 98% of patients. Potential risk factors for side effects during testing and treatment should be assessed for every patient to mitigate risk and to guide treatment recommendations and the duration of immunotherapy.

CytoBas: Precision component-resolved diagnostics for allergy using flow cytometric staining of basophils with recombinant allergen tetramers

BACKGROUND

Diagnostic tests for allergy rely on detecting allergen-specific IgE. Component-resolved diagnostics incorporate multiple defined allergen components to improve the quality of diagnosis and patient care.

OBJECTIVE

To develop a new approach for determining sensitization to specific allergen components that utilizes fluorescent protein tetramers for direct staining of IgE on blood basophils by flow cytometry.

METHODS

Recombinant forms of Lol p 1 and Lol p 5 proteins from ryegrass pollen (RGP) and Api m 1 from honeybee venom (BV) were produced, biotinylated, and tetramerized with streptavidin-fluorochrome conjugates. Blood samples from 50 RGP-allergic, 41 BV-allergic, and 26 controls were incubated with fluorescent protein tetramers for flow cytometric evaluation of basophil allergen binding and activation.

RESULTS

Allergen tetramers bound to and activated basophils from relevant allergic patients but not controls. Direct fluorescence staining of Api m 1 and Lol p 1 tetramers had greater positive predictive values than basophil activation for BV and RGP allergy, respectively, as defined with receiver operator characteristics (ROC) curves. Staining intensities of allergen tetramers correlated with allergen-specific IgE levels in serum. Inclusion of multiple allergens coupled with distinct fluorochromes in a single-tube assay enabled rapid detection of sensitization to both Lol p 1 and Lol p 5 in RGP-allergic patients and discriminated between controls, BV-allergic, and RGP-allergic patients.

CONCLUSION

Our novel flow cytometric assay, termed CytoBas, enables rapid and reliable detection of clinically relevant allergic sensitization. The intensity of fluorescent allergen tetramer staining of basophils has a high positive predictive value for disease, and the assay can be multiplexed for a component-resolved and differential diagnostic test for allergy.

Venom Immunotherapy: From Proteins to Product to Patient Protection

In this review, we outline and reflect on the important differences between allergen-specific immunotherapy for inhalant allergies (i.e., aeroallergens) and venom-specific immunotherapy (VIT), with a special focus on Venomil® Bee and Wasp. Venomil® is provided as a freeze-dried extract and a diluent to prepare a solution for injection for the treatment of patients with IgE-mediated allergies to bee and/or wasp venom and for evaluating the degree of sensitivity in a skin test. While the materials that make up the product have not changed, the suppliers of raw materials have changed over the years. Here, we consolidate relevant historical safety and efficacy studies that used products from shared manufacture supply profiles, i.e., products from Bayer or Hollister-Stier. We also consider the characterization and standardization of venom marker allergens, providing insights into manufacturing controls that have produced stable and consistent quality profiles over many years. Quality differences between products and their impacts on treatment outcomes have been a current topic of discussion and further research. Finally, we review the considerations surrounding the choice of depot adjuvant most suitable to augmenting VIT.

[Significance of molecular diagnostics in allergen immunotherapy : Practical tips for the application in various groups of allergens with exemplary cases]

The basis of allergen immunotherapy (AIT) is the diagnosis of the eliciting allergen sources, which is a challenge, especially in the case of multiple sensitizations. Molecular allergy diagnostics can be of special help, since detection of "marker allergens", usually important major allergens, allows to distinguish between primary sensitization and cross-reactions. Thus, the indication and extract selection for AIT can be facilitated. While molecular diagnosis is particularly useful for double-sensitized hymenoptera venom and polysensitized pollen allergic patients, the benefit is probably lower in case of house dust mite allergy.

A Review of Honeybee Venom Allergens and Allergenicity

Honeybee venom is a source of proteins with allergenic properties which can result in in various symptoms, ranging from local reactions through to systematic life-threatening anaphylaxis, or even death. According to the World Allergy Organization (WAO), honeybee venom allergy is one of the most common causes of anaphylaxis. Among the proteins present in honeybee venom, 12 protein fractions were registered by the World Health Organization’s Allergen Nomenclature Sub-Committee (WHO/IUIS) as allergenic. Most of them are highly immunogenic glycoproteins that cross-react with IgE and, as a consequence, may give false positive results in allergy diagnosis. Allergenic fractions are different in terms of molecular weight and biological activity. Eight of these allergenic fractions have also been identified in honey. This explains frequent adverse reactions after consuming honey in people allergic to venom and sheds new light on the causes of allergic symptoms in some individuals after honey consumption. At the same time, it also indicates the possibility of using honey as a natural source of allergen in specific immunotherapy.

Precision medicine reaching out to the patients in allergology - a German-Japanese workshop report

An expert workshop in collaboration of the German Society of Allergy and Clinical Immunology (DGAKI) and the Japanese Society of Allergy (JSA) provided a platform for key opinion leaders of both countries aimed to join expertise and to highlight current developments and achievements in allergy research. Key domains of the meeting included the following seven main sections and related subchapters: 1) basic immunology, 2) bronchial asthma, 3) prevention of allergic diseases, 4) food allergy and anaphylaxis, 5) atopic dermatitis, 6) venom allergy, and 7) upper airway diseases. This report provides a summary of panel discussions of all seven domains and highlights unmet needs and project possibilities of enhanced collaborations of scientific projects.

Precision Medicine in Hymenoptera Venom Allergy: Diagnostics, Biomarkers, and Therapy of Different Endotypes and Phenotypes

Allergic reactions to stings of Hymenoptera species may be severe and are potentially fatal deviations of the immunological response observed in healthy individuals. However, venom-specific immunotherapy (VIT) is an immunomodulatory approach able to cure venom allergy in the majority of affected patients. An appropriate therapeutic intervention and the efficacy of VIT not only depend on a conclusive diagnosis, but might also be influenced by the patient-specific manifestation of the disease. As with other diseases, it should be borne in mind that there are different endotypes and phenotypes of venom allergy, each of which require a patient-tailored disease management and treatment scheme. Reviewed here are different endotypes of sting reactions such as IgE-mediated allergy, asymptomatic sensitization or a simultaneous presence of venom allergy and mast cell disorders including particular considerations for diagnosis and therapy. Additionally, phenotypical manifestations of venom allergy, as e.g. differences in age of onset and disease severity, multiple sensitization or patients unsusceptible to therapy, are described. Moreover, biomarkers and diagnostic strategies that might reflect the immunological status of the patient and their value for therapeutic guidance are discussed. Taken together, the increasing knowledge of different disease manifestations in venom hypersensitivity and the growing availability of diagnostic tools open new options for the classification of venom allergy and, hence, for personalized medical approaches and precision medicine in Hymenoptera venom allergy.

The role of component-resolved diagnosis in Hymenoptera venom allergy

PURPOSE OF REVIEW

Component-resolved diagnostics (CRD) is a new tool aiming at detecting IgE-mediated sensitizations against individual, relevant allergens. Here, we discuss recent literature on molecular diagnosis in the field of Hymenoptera venom allergy (HVA) as well as CRD strengths and weaknesses.

RECENT FINDINGS

CRD, using single molecules or panels of allergens, may discriminate between primary sensitization and cross-reactivity in patients with double/multiple positivity in diagnostic tests with whole extracts, allowing the specialist to choose the most suitable venom for specific immunotherapy (VIT), avoiding unnecessary VIT and reducing the risk of side effects. Future availability of the cross-reactive recombinant pairs of allergens of different species may further increase the diagnostic performance. CRD may be useful in patients with negative allergy tests and a proven history of a previous systemic reaction, including those with mast cell disorders, who could benefit from VIT. In honeybee venom allergy, different sensitization profiles have been identified, which could be associated with a greater risk of VIT failure or treatment side effects.

SUMMARY

CRD is undoubtedly an innovative diagnostic method that leads to a more precise definition of the sensitization profile of the HVA patient. Together with a better knowledge of the molecular composition of different venom extracts, CRD may contribute to optimize patient-tailored therapy.

Natural history and long-term follow-up of Hymenoptera allergy

PURPOSE OF REVIEW

Information on the natural history of hypersensitivity reactions is helpful for deciding which patient urgently needs a venom immunotherapy (VIT).

RECENT FINDINGS

The frequency of self-reported systemic allergic reactions (SAR) to Hymenoptera stings is approximately 3-7% in the Northern Hemisphere. About 25% of SAR are severe (anaphylactic shock). Fatal sting reactions are very rare. The most important risk factor for severe insect sting anaphylaxis is mast cell disease. Other risk factors are higher age, vespid venom allergy (in contrast to honeybee venom allergy), repeated stings, male sex, and treatment with ACE inhibitors. Preceding large local reactions seem not to play a risk factor for subsequent SAR.

SUMMARY

The majority of risk factors for severe anaphylaxis are not modifiable. For patients presenting with well defined risk factors for a very severe or even fatal anaphylaxis, VIT is of utmost importance, and they should be performed for the rest of their life. Sting challenge tests are required to identify patients in whom treatment was ineffective. Those patients, who did not receive VIT although presenting with a firm indication, or in whom VIT was stopped, require yearly monitoring to teach preventive measures and to renew the emergency kit.

The Honeybee Venom Major Allergen Api m 10 (Icarapin) and Its Role in Diagnostics and Treatment of Hymenoptera Venom Allergy

PURPOSE OF REVIEW

In Hymenoptera venom allergy, the research focus has moved from whole venoms to individual allergenic molecules. Api m 10 (icarapin) has been described as a major allergen of honeybee venom (HBV) with potentially high relevance for diagnostics and therapy of venom allergy. Here, we review recent studies on Api m 10 characteristics as well as its role in component-resolved diagnostics and potential implications for venom-specific immunotherapy (VIT).

RECENT FINDINGS

Api m 10 is a major allergen of low abundance in HBV. It is an obviously unstable protein of unknown function that exhibits homologs in other insect species. Despite its low abundance in HBV, 35 to 72% of HBV-allergic patients show relevant sensitization to this allergen. Api m 10 is a marker allergen for HBV sensitization, which in many cases can help to identify primary sensitization to HBV and, hence, to discriminate between genuine sensitization and cross-reactivity. Moreover, Api m 10 might support personalized risk stratification in VIT, as dominant sensitization to Api m 10 has been identified as risk factor for treatment failure. This might be of particular importance since Api m 10 is strongly underrepresented in some therapeutic preparations commonly used for VIT. Although the role of Api m 10 in HBV allergy and tolerance induction during VIT is not fully understood, it certainly is a useful tool to unravel primary sensitization and individual sensitization profiles in component-resolved diagnostics (CRD). Moreover, a potential of Api m 10 to contribute to personalized treatment strategies in HBV allergy is emerging.

Bee Venom Immunotherapy: Current Status and Future Directions

Bee venom immunotherapy is the main treatment option for bee sting allergy. Its major limitations are the high percentage of allergic side effects and long duration, which are driving the development of novel therapeutic modalities. Three general approaches have been evaluated including the use of hypoallergenic allergen derivatives, adjunctive therapy, and alternative delivery routes. This article reviews preclinical and clinical evidence on the therapeutic potential of these new therapies. Among hypoallergenic derivatives, hybrid allergens showed a markedly reduced IgE reactivity in mouse models. Whether they will offer therapeutic benefit over extract, it is still not known since clinical trials have not been carried out yet. T cell epitope peptides have proven effective in small clinical trials. Major histocompatibility complex class II restriction was circumvented by using long overlapping or promiscuous T cell epitope peptides. However, the T cell-mediated late-phase adverse events have been reported with both short and longer peptides. Application of mimotopes could potentially overcome both T cell- and IgE-mediated adverse events. During this evolution of vaccine, there has been a gain in safety. The efficacy was further improved with the use of Toll-like receptor-activating adjuvants and delivery systems. In murine models, the association of allergen Api m 1 with cytosine-guanosine rich oligonucleotides stimulated strong T-helper type-1 response, whereas its encapsulation into microbubbles protected mice against allergen challenge. An intralymphatic administration of low-dose vaccine has shown the potential to decrease treatment from 5 years to only 12 weeks. Bigger clinical trials are needed to follow up on these results.

A WAO - ARIA - GA2LEN consensus document on molecular-based allergy diagnosis (PAMD@): Update 2020

Precision allergy molecular diagnostic applications (PAMD@) is increasingly entering routine care. Currently, more than 130 allergenic molecules from more than 50 allergy sources are commercially available for in vitro specific immunoglobulin E (sIgE) testing. Since the last publication of this consensus document, a great deal of new information has become available regarding this topic, with over 100 publications in the last year alone. It thus seems quite reasonable to publish an update. It is imperative that clinicians and immunologists specifically trained in allergology keep abreast of the new and rapidly evolving evidence available for PAMD@.

PAMD@ may initially appear complex to interpret; however, with increasing experience, the information gained provides relevant information for the allergist. This is especially true for food allergy, Hymenoptera allergy, and for the selection of allergen immunotherapy. Nevertheless, all sIgE tests, including PAMD@, should be evaluated within the framework of a patient's clinical history, because allergen sensitization does not necessarily imply clinical relevant allergies.

Safety and Effectiveness of a 3-Day Rush Insect Venom Immunotherapy Protocol

BACKGROUND

Venom immunotherapy (VIT) is an established and effective treatment for patients with Hymenoptera venom allergies. Especially during the build-up of VIT, systemic allergic reactions are a key issue.

OBJECTIVE

To investigate the safety and effectiveness of a 3-day rush insect VIT protocol and a strategy for the management of individuals with VIT-induced anaphylaxis.

METHODS

In this retrospective monocentric study, 11-year data regarding build-up cycles of VIT were retrieved from institutional records. The following parameters of VIT-induced anaphylaxis were analyzed: frequency, severity, time of occurrence within the build-up cycle, and impact on the success of VIT. The effectiveness of VIT was assessed by the results of sting challenges (SCs) by the culprit insect.

RESULTS

In total, 1,317 initial build-up cycles of VIT were evaluated in this study, and the frequency of VIT-induced anaphylaxis was 6.6%. Anaphylaxis occurred most frequently when the daily cumulative venom dose was ≥100 µg. A group (n = 65) of patients with VIT-induced anaphylaxis in this dose range temporarily received a reduced maintenance dose, and without additional co-medications or complications, the target dose was reached after a second build-up in 91% of the cycles. After completing the VIT build-up, SCs were performed in 76.9% of the cohort, and the effectiveness of VIT was confirmed by 98.5% of the tests.

CONCLUSIONS

In this study, we report a 3-day VIT rush protocol with a reasonable rate of VIT-induced anaphylaxis and excellent effectiveness of VIT.

Worldwide perspectives on venom allergy

Venom immunotherapy is the standard of care for people with severe reactions and has been proven to reduce risk of future anaphylactic events. There is a moral imperative to ensure production, supply and worldwide availability of locally relevant, registered, standardized commercial venom extracts for diagnosis and treatment. Insects causing severe immediate allergic reactions vary by region worldwide. The most common culprits include honeybees (Apis mellifera), social wasps including yellow jackets (Vespula and Dolichovespula), paper wasps (Polistes) and hornets (Vespa), stinging ants (Solenopsis, Myrmecia, Pachycondyla, and Pogonomyrmex), and bumblebees (Bombus). Insects with importance in specific areas of the world include the Australian tick (Ixodes holocyclus), the kissing bug (Triatoma spp), horseflies (Tabanus spp), and mosquitoes (Aedes, Culex, Anopheles). Reliable access to high quality venom immunotherapy to locally relevant allergens is not available throughout the world. Many current commercially available therapeutic vaccines have deficiencies, are not suitable for, or are unavailable in vast areas of the globe. New products are required to replace products that are unstandardized or inadequate, particularly whole-body extract products. New products are required for insects in which no current treatment options exist. Venom immunotherapy should be promoted throughout the world and the provision thereof be supported by health authorities, regulatory authorities and all sectors of the health care service.

Hymenoptera Venom Allergy: How Does Venom Immunotherapy Prevent Anaphylaxis From Bee and Wasp Stings?

Hymenoptera stings may cause both local and systemic allergic reactions and even life threatening anaphylaxis. Along with pharmaceutical drugs and foods, hymenoptera venom is one of the most common causes of anaphylaxis in humans. To date, no parameter has been identified that may predict which sensitized people will have a future systemic sting reaction (SSR), however some risk factors, such as mastocytosis and age >40 years are known. Venom immunotherapy (VIT) is the most effective method of treatment for people who had SSR, which is shown to be effective even after discontinuation of the therapy. Development of peripheral tolerance is the main mechanism during immunotherapy. It is mediated by the production of blocking IgG/IgG4 antibodies that may inhibit IgE dependent reactions through both high affinity (FcεRI) and low affinity (FcεRII) IgE receptors on mast cells, basophils and B cells. The generation of antigen specific regulatory T cells produces IL-10 and suppresses Th2 immunity and the immune responses shift toward a Th1-type response. B regulatory cells are also involved in the production of IL-10 and the development of long term immune tolerance. During VIT the number of effector cells in target organs also decreases, such as mast cells, basophils, innate type 2 lymphocytes and eosinophils. Several meta-analyses and randomized controlled studies have proved that VIT is effective for preventing SSR to a sting and improves the quality of life. In this review, the risk of SSR in venom allergy and how VIT changed this risk are discussed.

Genome-Wide Identification of Long Non-Coding RNAs and Their Regulatory Networks Involved in Apis mellifera ligustica Response to Nosema ceranae Infection

Long non-coding RNAs (lncRNAs) are a diverse class of transcripts that structurally resemble mRNAs but do not encode proteins, and lncRNAs have been proven to play pivotal roles in a wide range of biological processes in animals and plants. However, knowledge of expression patterns and potential roles of honeybee lncRNA response to Nosema ceranae infection is completely unknown. Here, we performed whole transcriptome strand-specific RNA sequencing of normal midguts of Apis mellifera ligustica workers (Am7CK, Am10CK) and N. ceranae-inoculated midguts (Am7T, Am10T), followed by comprehensive analyses using bioinformatic and molecular approaches. A total of 6353 A. m. ligustica lncRNAs were identified, including 4749 conserved lncRNAs and 1604 novel lncRNAs. These lncRNAs had minimal sequence similarities with other known lncRNAs in other species; however, their structural features were similar to counterparts in mammals and plants, including shorter exon and intron length, lower exon number, and lower expression level, compared with protein-coding transcripts. Further, 111 and 146 N. ceranae-responsive lncRNAs were identified from midguts at 7-days post-inoculation (dpi) and 10 dpi compared with control midguts. Twelve differentially expressed lncRNAs (DElncRNAs) were shared by Am7CK vs. Am7T and Am10CK vs. Am10T comparison groups, while the numbers of unique DElncRNAs were 99 and 134, respectively. Functional annotation and pathway analysis showed that the DElncRNAs may regulate the expression of neighboring genes by acting in cis and trans fashion. Moreover, we discovered 27 lncRNAs harboring eight known miRNA precursors and 513 lncRNAs harboring 2257 novel miRNA precursors. Additionally, hundreds of DElncRNAs and their target miRNAs were found to form complex competitive endogenous RNA (ceRNA) networks, suggesting that these DElncRNAs may act as miRNA sponges. Furthermore, DElncRNA-miRNA-mRNA networks were constructed and investigated, the results demonstrated that a portion of the DElncRNAs were likely to participate in regulating the host material and energy metabolism as well as cellular and humoral immune host responses to N. ceranae invasion. Our findings revealed here offer not only a rich genetic resource for further investigation of the functional roles of lncRNAs involved in the A. m. ligustica response to N. ceranae infection, but also a novel insight into understanding the host-pathogen interaction during honeybee microsporidiosis.

Component-resolved diagnosis in selecting patients for yellowjacket venom immunotherapy

BACKGROUND

Venom immunotherapy is effective in preventing systemic allergic reactions (SARs), but the diagnosis of venom allergy is problematic.

OBJECTIVE

To compare the performance of component-resolved diagnosis and conventional tests in patients referred for venom immunotherapy.

METHODS

We measured serum-specific immunoglobulin E to yellowjacket and honeybee venoms (Ves v 1 and Ves v 5 and Api m 1), cross-reactive carbohydrate determinants, serum basal tryptase (ImmunoCAP, ThermoFisher Scientific, Uppsala, Sweden), and skin prick test reactions in 84 patients referred to receive venom immunotherapy. History of SAR and its severity were evaluated.

RESULTS

Of the 78 patients with suspected yellowjacket venom (YJV) allergy, a history of SAR was confirmed in 47 (60%) and 31 (40%) had a non-SAR reaction. The most accurate tests to confirm venom allergy after a SAR were serum-specific immunoglobulin E to yellowjacket whole-venom extract spiked with Ves v 5 (area under the curve 0.87, 95% confidence interval 0.77-0.97, P < .001) and Ves v 5 (area under the curve 0.86, 95% confidence interval 0.76-0.96, P < .001). Sensitization to Ves v 1 was infrequent and its area under the curve was low (0.62, 95% confidence interval 0.47-0.76, P = .106). Sensitivity of the YJV skin prick test was 86%, but its specificity was low at 54%. Double sensitization to yellowjacket and honeybee occurred frequently in skin prick tests. Of the patients without a SAR, 26% showed a positive reaction to YJV in any serum test and 46% showed a positive reaction in skin tests.

CONCLUSION

Specific immunoglobulin E to the YJV spiked with Ves v 5 confirmed the allergy after a SAR. A history of SAR should be confirmed before testing, because venom sensitization is frequent in other types of reactions.

Hymenoptera Venom Extracts in Clinical Practice

Venom immunotherapy is the only treatment for the prevention of anaphylaxis and remains the prototypical model for its diagnosis and management. Unlike other causes of anaphylaxis, such as foods and drugs, preventative treatment using venom immunotherapy is highly effective with well-established protocols, and is widely available. Hymenoptera venoms are also unique in that the primary allergens are directly measurable in terms of micrograms, rather than labeled on the basis of potency. As such, venoms were the first truly standardized extracts. However, Hymenoptera venom presents unique challenges in collection, processing, and stabilization of the venom extract product. Historically, there have been minor variations in insect composition in venom extract content. These differences were in part based on variation in insect availability and venom collection and have created minor challenges. However, it is a recognized need that venom extracts contain an optimal and complete repertoire of relevant venoms so as to be assured of appropriate diagnosis and treatment. As such, insect availability and collection, as well as storage, stability, and sterility of venom extracts, have remained critical components to appropriate diagnosis and prevention of venom-induced anaphylaxis. In recent years there has been concerns about adequate supplies of venom for appropriate diagnosis and treatment of venom allergy, but these concerns seem to have stabilized, with the movement to a single venom supplier. This movement to a single supplier may provide its own challenges.

Immunological differences between insect venom-allergic patients with and without immunotherapy and asymptomatically sensitized subjects

BACKGROUND

Currently available tests are unable to distinguish between asymptomatic sensitization and clinically relevant Hymenoptera venom allergy. A reliable serological marker to monitor venom immunotherapy (VIT) does also not exist. Our aim was to find reliable serological markers to predict tolerance to bee and vespid stings.

METHODS

We included 77 asymptomatically sensitized subjects, 85 allergic patients with acute systemic sting reactions, and 61 allergic patients currently treated with VIT. Levels of sIgE and sIgG₄ to bee and vespid venom, rApi m 1, and rVes v 5 were measured immediately after allergic sting reactions or before sting challenges and 4 weeks later. All sting challenges were tolerated. The inhibitory activity was determined using BAT inhibition and ELIFAB assay.

RESULTS

Median sIgG₄ levels were 96-fold higher in VIT patients (P < .001) while sIgE/sIgG₄ ratios were consistently lower (P < .001). The ELIFAB assay was paralleled by low sIgE/sIgG₄ ratios in VIT patients, showing markedly higher allergen-blocking capacity (P < .001). An almost complete inhibition of the basophil response was seen in all patients treated with vespid venom, but not in those treated with bee venom. Four weeks after the sting, sIgE and sIgG₄ levels were increased in allergic and asymptomatically sensitized patients, but not in VIT patients.

CONCLUSION

Immunological responses after stings varied in bee and vespid venom-allergic patients. In patients under VIT, sIgE and sIgG₄ remained completely stable after sting challenges. Monitoring VIT efficacy was only possible in vespid venom allergy, and the sIgG₄ threshold for rVes v 5 had the highest sensitivity to confirm tolerance. The BAT inhibition test was the most reliable tool to confirm tolerance on an individual basis.

Characterization of the honeybee venom proteins C1q-like protein and PVF1 and their allergenic potential

Honeybee (Apis mellifera) venom (HBV) represents an ideal model to study the role of particular venom components in allergic reactions in sensitized individuals as well as in the eusociality of Hymenoptera species. The aim of this study was to further characterize the HBV components C1q-like protein (C1q) and PDGF/VEGF-like factor 1 (PVF1). C1q and PVF1 were produced as recombinant proteins in insect cells. Their allergenic properties were examined by determining the level of specific IgE antibodies in the sera of HBV-allergic patients (n = 26) as well as by their capacity to activate patients' basophils (n = 11). Moreover, the transcript heterogeneity of PVF1 was analyzed. It could be demonstrated that at least three PVF1 variants are present in the venom gland, which all result from alternative splicing of one transcript. Additionally, recombinant C1q and PVF1 from Spodoptera frugiperda insect cells exhibited specific IgE reactivity with approximately 38.5% of sera of HBV-allergic patients. Interestingly, both proteins were unable to activate basophils of the patients, questioning their role in the context of clinically relevant sensitization. Recombinant C1q and PVF1 can build the basis for a deeper understanding of the molecular mechanisms of Hymenoptera venoms. Moreover, the conflicting results between IgE sensitization and lack of basophil activation, might in the future contribute to the identification of factors that determine the allergenic potential of proteins.

Component-resolved diagnosis in hymenoptera allergy

Component-resolved diagnosis based on the use of well-defined, properly characterised and purified natural and recombinant allergens constitutes a new approach in the diagnosis of venom allergy. Prospective readers may benefit from an up-to-date review on the allergens. The best characterised venom is that of Apis mellifera, whose main allergens are phospholipase A2 (Api m1), hyaluronidase (Api m2) and melittin (Api m4). Additionally, in recent years, new allergens of Vespula vulgaris have been identified and include phospholipase A1 (Ves v1), hyaluronidase (Ves v2) and antigen 5 (Ves v5). Polistes species are becoming an increasing cause of allergy in Europe, although only few allergens have been identified in this venom. In this review, we evaluate the current knowledge about molecular diagnosis in hymenoptera venom allergy.