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.

Phenotype and risk factors of venom-induced anaphylaxis: A case-control study of the European Anaphylaxis Registry.

BACKGROUND: Venom-induced anaphylaxis (VIA) is a common, potentially life-threatening hypersensitivity reaction associated with (1) a specific symptom profile, 2) specific cofactors, and 3) specific management. Identifying the differences in phenotypes of anaphylaxis is crucial for future management guidelines and development of a personalized medicine approach. OBJECTIVE: This study aimed to evaluate the phenotype and risk factors of VIA. METHODS: Using data from the European Anaphylaxis Registry (12,874 cases), we identified 3,612 patients with VIA and analyzed their cases in comparison with sex- and age-matched anaphylaxis cases triggered by other elicitors (non-VIA cases [n = 3,605]). RESULTS: VIA more frequently involved more than 3 organ systems and was associated with cardiovascular symptoms. The absence of skin symptoms during anaphylaxis was correlated with baseline serum tryptase level and was associated with an increased risk of a severe reaction. Intramuscular or intravenous epinephrine was administered significantly less often in VIA, in particular, in patients without a history of anaphylaxis. A baseline serum tryptase level within the upper normal range (8-11.5 ng/mL) was more frequently associated with severe anaphylaxis. CONCLUSION: Using a large cohort of VIA cases, we have validated that patients with intermediate baseline serum tryptase levels (8-11 ng/mL) and without skin involvement have a higher risk of severe VIA. Patients receiving ß-blockers or angiotensin-converting enzyme inhibitors had a higher risk of developing severe cardiovascular symptoms (including cardiac arrest) in VIA and non-VIA cases. Patients experiencing VIA received epinephrine less frequently than did cases with non-VIA.

ß-blockers and ACE inhibitors are not a risk factor for severe systemic sting reactions and adverse events during venom immunotherapy.

BACKGROUND: There is controversy whether taking ß-blockers or ACE inhibitors (ACEI) is a risk factor for more severe systemic insect sting reactions (SSR) and whether it increases the number or severity of adverse events (AE) during venom immunotherapy (VIT). METHODS: In this open, prospective, observational, multicenter trial, we recruited patients with a history of a SSR and indication for VIT. The primary objective of this study was to evaluate whether patients taking ß-blockers or ACEI show more systemic AE during VIT compared to patients without such treatment. RESULTS: In total, 1,425 patients were enrolled and VIT was performed in 1,342 patients. Of all patients included, 388 (27.2%) took antihypertensive (AHT) drugs (10.4% took ß-blockers, 11.9% ACEI, 5.0% ß-blockers and ACEI). Only 5.6% of patients under AHT treatment experienced systemic AE during VIT as compared with 7.4% of patients without these drugs (OR: 0.74, 95% CI: 0.43-1.22, p = 0.25). The severity of the initial sting reaction was not affected by the intake of ß-blockers or ACEI (OR: 1.14, 95% CI: 0.89-1.46, p = 0.29). In total, 210 (17.7%) patients were re-stung during VIT and 191 (91.0%) tolerated the sting without systemic symptoms. Of the 19 patients with VIT treatment failure, 4 took ß-blockers, none an ACEI. CONCLUSIONS: This trial provides robust evidence that taking ß-blockers or ACEI does neither increase the frequency of systemic AE during VIT nor aggravate SSR. Moreover, results suggest that these drugs do not impair effectiveness of VIT. (Funded by Medical University of Graz, Austria; Clinicaltrials.gov number, NCT04269629).

Hereditary angioedema in Austria: prevalence and regional peculiarities.

BACKGROUND: Data on the prevalence and clinical features of Austrian patients with hereditary angioedema (HAE) with C1-inhibitor (C1-INH) deficiency (HAE-1) or dysfunction (HAE-2) are lacking. METHODS: Current baseline data were collected in a national survey. The records of HAE patients at the Medical University of Graz were analyzed with regard to clinical characteristics. RESULTS: A total of 137 patients were identified, yielding a prevalence of 1 : 64,396. The median age at the onset of symptoms was 6.5 years, and the median age at the time of correct diagnosis 21.0 years. The median delay in diagnosis was 15.0 years for newly diagnosed patients without a family history of HAE. Patients with a family history of HAE received an immediate diagnosis. HAE patients without a family history of HAE and born before 1960 had to wait a median of 16.0 years until they were diagnosed correctly. Patients born after 1980 still experienced a median diagnostic delay of 6.5 years. CONCLUSION: Patients with this condition still face an excessive diagnostic delay in some parts of Austria, or their disorder may even remain unrecognized by specialists. This underlines the need for better awareness of the disease.

Tackling Bet v 1 and associated food allergies with a single hybrid protein.

BACKGROUND: Allergy vaccines should be easily applicable, safe, and efficacious. For Bet v 1-mediated birch pollen and associated food allergies, a single wild-type allergen does not provide a complete solution. OBJECTIVE: We aimed to combine immunologically relevant epitopes of Bet v 1 and the 2 clinically most important related food allergens from apple and hazelnut to a single hybrid protein, termed MBC4. METHODS: After identification of T cell epitope-containing parts on each of the 3 parental allergens, the hybrid molecule was designed to cover relevant epitopes and evaluated in silico. Thereby a mutation was introduced into the hybrid sequence, which should alter the secondary structure without compromising the immunogenic properties of the molecule. RESULTS: MBC4 and the parental allergens were purified to homogeneity. Analyses of secondary structure elements revealed substantial changes rendering the hybrid de facto nonreactive with patients' serum IgE. Nevertheless, the protein was monomeric in solution. MBC4 was able to activate T-cell lines from donors with birch pollen allergy and from mice immunized with the parental allergens. Moreover, on immunization of mice and rabbits, MBC4 induced cross-reactive IgG antibodies, which were able to block the binding of human serum IgE. CONCLUSION: Directed epitope rearrangements combined with a knowledge-based structural modification resulted in a protein unable to bind IgE from allergic patients. Still, properties to activate specific T cells or induce blocking antibodies were conserved. This suggests that MBC4 is a suitable vaccine candidate for the simultaneous treatment of Bet v 1 and associated food allergies.

Influence of Intrinsic and Lifestyle Factors on the Development of IgE Sensitization.

BACKGROUND: IgE sensitization is a prerequisite for the development of allergic symptoms. The investigation of factors influencing the development of IgE is therefore crucial for understanding the onset of allergic diseases. METHODS: This epidemiological study investigated personal, intrinsic, and lifestyle factors in a nonselected cohort of 501 Austrian adolescents (aged 12-21 years). IgE levels to 112 allergen molecules were analyzed in the serum of participants using the ImmunoCAP ISAC®. Allergic sensitization, IgE levels to single allergens, and ISAC score sums were correlated with results obtained from a questionnaire. RESULTS: In this adolescent cohort, male participants showed a higher sensitization frequency (56.8%) compared to females (50.9%) and significantly increased IgE levels to profilins. Underweight subjects demonstrated a stronger IgE sensitization. Family size inversely correlated with IgE levels to PR-10 allergens, and predominately paternal allergies were a predictive factor for IgE sensitization in the children. Vaccination, breastfeeding, and delivery mode showed no influence, while a highly protective effect was observed for growing up on a farm. Of all of the investigated lifestyle factors, only smoking significantly influenced the risk for IgE development. Participants with moderate frequencies of colds showed increased sensitization levels. CONCLUSION: A hereditary predisposition and lifestyle factors such as a farming environment, smoking, family size, body weight, or frequency of colds significantly influenced the development of allergen-specific IgE in this cohort of adolescents.

Nanoparticle-allergen interactions mediate human allergic responses: protein corona characterization and cellular responses.

BACKGROUND: Engineered nanomaterials (ENMs) interact with different biomolecules as soon as they are in contact, resulting in the formation of a biomolecule 'corona'. Hence, the 'corona' defines the biological identity of the ENMs and could affect the response of the immune system to ENM exposure. With up to 40 % of the world population suffering from type I allergy, a possible modulation of allergen effects by binding to ENMs is highly relevant with respect to work place and consumer safety. Therefore, the aim of this present study was to gain an insight into the interactions of gold nanoparticles with different seasonally and perennially occurring outdoor and indoor allergens. METHODS: Gold nanoparticles (AuNPs) were conjugated with the major allergens of birch pollen (Bet v 1), timothy grass pollen (Phl p 5) and house dust mite (Der p 1). The AuNP-allergen conjugates were characterized by means of TEM negative staining, dynamic light scattering (DLS), z-potential measurements and hyperspectral imaging. Furthermore, 3D models were constructed, based on the characterization data, to visualize the interaction between the allergens and the AuNPs surface. Differences in the activation of human basophil cells derived from birch/grass pollen- and house dust mite-allergic patients in response to free allergen and AuNP-allergen conjugates were determined using the basophil activation assay (BAT). Potential allergen corona replacement during BAT was controlled for using Western blotting. The protease activity of AuNP-Der p 1 conjugates compared to free Der p 1 was assessed, by an enzymatic activity assay and a cellular assay pertaining to lung type II alveolar epithelial cell tight junction integrity. RESULTS: The formation of a stable corona was found for all three allergens used. Our data suggest, that depending on the allergen, different effects are observed after binding to ENMs, including enhanced allergic responses against Der p 1 and also, for some patients, against Bet v 1. Moreover elevated protease activity of AuNP-Der p 1 conjugates compared to free Der p 1 was found. CONCLUSION: In summary, this study presents that conjugation of allergens to ENMs can modulate the human allergic response, and that protease activity can be increased. Graphical Abstract Cross-linking of IgE receptors and degranulation of human basophils due to epitope alignment of nanoparticle-coated allergens.

Dendritic cells activated by IFN-γ/STAT1 express IL-31 receptor and release proinflammatory mediators upon IL-31 treatment.

IL-31 is a T cell-derived cytokine that signals via a heterodimeric receptor composed of IL-31Rα and oncostatin M receptor ß. Although several studies have aimed to investigate IL-31-mediated effects, the biological functions of this cytokine are currently not well understood. IL-31 expression correlates with the expression of IL-4 and IL-13 and is associated with atopic dermatitis in humans, indicating that IL-31 is involved in Th2-mediated skin inflammation. Because dendritic cells are the main activators of Th cell responses, we posed the question of whether dendritic cells express the IL-31R complex and govern immune responses triggered by IL-31. In the current study, we report that primary human CD1c(+) as well as monocyte-derived dendritic cells significantly upregulate the IL-31Rα receptor chain upon stimulation with IFN-γ. EMSAs, chromatin immunoprecipitation assays, and small interfering RNA-based silencing assays revealed that STAT1 is the main transcription factor involved in IFN-γ-dependent IL-31Rα expression. Subsequent IL-31 stimulation resulted in a dose-dependent release of proinflammatory mediators, including TNF-α, IL-6, CXCL8, CCL2, CCL5, and CCL22. Because these cytokines are crucially involved in skin inflammation, we hypothesize that IL-31-specific activation of dendritic cells may be part of a positive feedback loop driving the progression of inflammatory skin diseases.

Age- and Elicitor-Dependent Characterization of Hymenoptera Venom-Induced Anaphylaxis in Children and Adolescents.

BACKGROUND: Hymenoptera venom is one of the most frequent causes of anaphylaxis. Studies from adults indicate the clinical profiles and risk factors of Hymenoptera venom-induced anaphylaxis (VIA). Much less is known about pediatric VIA. OBJECTIVE: To understand elicitor- and age-related factors determining pediatric VIA by analyzing data from the anaphylaxis registry. METHODS: We selected pediatric VIA, pediatric food-induced anaphylaxis (FIA), and adult VIA cohorts from the anaphylaxis registry and performed a comparative data analysis regarding elicitors, symptoms, and management. RESULTS: We identified 725 pediatric patients with VIA, 3,149 with pediatric FIA, and 5,534 with adult VIA. In pediatric VIA, boys were more frequently affected, atopy was not increased, and the onset of the reaction after exposure was fast (≤30 min; 91%) compared with pediatric FIA. Symptoms in pediatric VIA were age dependent, and although respiratory symptoms occurred most frequently besides skin symptoms in both pediatric patients with VIA and FIA, cardiovascular symptoms were more frequently reported in pediatric patients with VIA than pediatric patients with FIA. The analysis of pediatric versus adult VIA revealed clear differences in the frequency of involved organ systems (skin: 93% vs 78%; respiratory: 77% vs 64%; and cardiovascular: 61% vs 85%). For both pediatric and adult VIA, the rates of adrenaline application by a professional were low (29% vs 31%) but hospitalization rates were higher in children than in adults (61% vs 42%). Venom immunotherapy was frequently initiated regardless of age (78% each). CONCLUSIONS: Pediatric VIA is more frequent in boys, symptoms are age dependent, and hospitalization is often required. Adrenaline should be applied according to current guidelines. Venom immunotherapy is an important treatment option in pediatric VIA and should be considered in severely affected children.

[Hereditary angioedema due to C1-inhibitor deficiency, a national disease management programme]. / Hereditäres Angioödem durch C1-Inhibitor-Mangel, eine nationale Versorgungsleitlinie.

Hereditary angioedema (HAE) is a rare, painful, disabling and potentially fatal disease, where early diagnosis and effective treatment are critical. These Austrian guidelines for the diagnosis and management of HAE provide instructions and advice on the state of the art management of HAE in Austria in contrast to global guidelines, where the situation of all countries worldwide must be taken into account. Our goal is to help Austrian physicians to consider HAE as a differential diagnosis with corresponding symptoms, to make rational decisions for the diagnosis and management of HAE with C1-inhibitor deficiency (type 1 or type 2). The guidelines provide information on common and important clinical symptoms, diagnostic methods, treatment modalities, available HAE-specific medications in Austria and last but not least to motivate physicians to refer patients to HAE centers for confirmation of the diagnosis and adequate treatment decisions.

Proteomic profiling of birch (Betula verrucosa) pollen extracts from different origins.

Pollen of the European white birch is a major source of spring pollinosis in Europe. Pollen-allergy diagnosis and treatment by specific immunotherapy commonly rely on extracts of natural origin. To gain insight into the protein content and its variability, we evaluated the profile of allergenic and non-allergenic proteins in extracts of pollen from different origins by MS-based proteomics. Aqueous extracts prepared from commercially available Swedish birch pollen, pollen collected from Austrian trees and a commercial skin prick extract were analyzed by 1-DE, 2-DE, immunoblotting and mass spectrometry, resulting in a complete inventory of extractable, disease-relevant pollen proteins. A main focus of this study was on the isoform distribution of Bet v 1, the major allergen of birch pollen. Using a combination of intact mass determination and peptide sequencing, five isoforms (a, b, d, f and j) were unequivocally identified in Swedish and Austrian birch pollen extracts, while the skin prick extract contained only isoforms a, b and d. Using the same methods as for Bet v 1, divergencies in the sequence of birch profilin (Bet v 2), a plant panallergen, were solved. The molecular characterization of pollen extracts is relevant for standardization and development of new reagents for specific immunotherapy.

Provoking allergens and treatment of anaphylaxis in children and adolescents--data from the anaphylaxis registry of German-speaking countries.

Anaphylaxis is the most severe reaction of an IgE-mediated hypersensitivity. Data about affected patients may help to improve our knowledge of anaphylaxis and its medical care. We analysed data from the anaphylaxis registry of German speaking countries with regard to the provoking allergens and treatment modalities of anaphylaxis in children and adolescents. Inclusion criteria were severe systemic allergic reactions with concomitant pulmonary and/or cardiovascular symptoms. The data are collected by a password-controlled online-questionnaire. For this analysis, data of 197 reported anaphylactic reactions from children and adolescents registered between 2006 and 2009 were included. The data show that within the registered cases the most frequently affected organ systems for children and adolescents were the skin (89%) and the respiratory tract (87%) followed by symptoms of the cardiovascular system (47%) and the gastrointestinal tract (43%). The most frequent elicitors were food allergens accounting for 58% of cases, followed by insect venom (24%) and drugs (8%). The most frequent food allergens were peanuts followed by tree nuts and animal related food products. In 18% aggravating factors such as physical exercise were noted by the clinicians. 26% of the analysed patients had experienced more than one reaction. The data regarding the emergency treatment show that antihistamines (87%) and corticosteroids (85%) were often used but that adrenaline was rarely used (22% of the registered cases). Taken together these data show that the analysis of anaphylaxis by registration of affected individuals can provide data about provoking allergens and treatment measures but also suggest the impact of aggravating factors on anaphylactic reactions. The under-represented usage of adrenaline indicates the need of educational measures for patients and their physicians.

Predictors of side effects during the buildup phase of venom immunotherapy for Hymenoptera venom allergy: the importance of baseline serum tryptase.

BACKGROUND: Severe side effects during venom immunotherapy (VIT) are associated with a variety of risk factors. OBJECTIVE: Our aim was to evaluate the association of baseline serum tryptase concentration (BTC) and of other parameters, which are routinely recorded during patient evaluation, with the frequency of severe reactions requiring an emergency intervention during the buildup phase of VIT. METHODS: In this observational prospective multicenter study, we enrolled 680 patients with established honeybee or vespid venom allergy who underwent VIT. Data were collected on tryptase concentration, age, sex, culprit insect, cardiovascular medication, degree of preceding sting reaction, preventive antiallergic medication before therapy, time between last preceding sting reaction and VIT, venom specific IgE concentration, and type of buildup procedure. Relative rates were calculated with generalized additive models. RESULTS: Fifty-seven patients (8.4%) required an emergency intervention during buildup because of a severe systemic reaction. The frequency of interventions increased significantly with higher BTC (log-linear association; adjusted odds ratio, 1.56; 95% CI, 1.15-2.11; P < .005). The predictive power of BTC was markedly greater when VIT was performed for vespid venom allergy than for bee venom (for bee VIT, no significant association; for vespid VIT, log-linear association; adjusted odds ratio, 2.33; 95% CI, 1.28-4.26; P = .005). The most important other factor significantly associated with severe reactions during the buildup phase of VIT was bee venom allergy. CONCLUSION: Before vespid VIT, measurement of baseline serum tryptase concentration should be used to identify patients with a high risk for side effects. Patients with bee venom allergy require a particularly high degree of surveillance during VIT.

Anaphylaxis in middle-aged patients.

Age is one of the most important factors influencing the course of anaphylaxis: moreover, the frequency of elicitors of anaphylaxis is age-associated. We analyzed 8,465 anaphylactic episodes in adult patients in three age groups with a focus on patients in the middle-age group (35 - 65 years old). Insect venom was the most frequent trigger in this age group (51.2%) followed by drugs (22.8%) and food (17.3%). Severe reactions were observed in 40.1% of middle-aged patients and occurred more frequently in this age group than in patients below 35 years (27.6%) and less frequently than in patients over 65 years (55.6%). The symptoms and comorbidity profile also changed with age, most significantly regarding the increase in rates of concomitant cardiologic diseases and (severe) cardiovascular symptoms.

Wheat Anaphylaxis in Adults Differs from Reactions to Other Types of Food.

BACKGROUND: Wheat is one of the most commonly consumed foods and a known elicitor of anaphylaxis in children and adults. Reactions in adults are often cofactor dependent and characterized by a prolonged time between food intake and the onset of symptoms making the diagnosis of wheat anaphylaxis challenging. OBJECTIVE: To characterize a cohort of patients with the history of wheat anaphylaxis to better understand this atypical phenotype of anaphylaxis. METHODS: Data from the European Anaphylaxis Registry from 2007 to 2019 (n = 10,636) including 250 patients (213 adults and 37 children) with a history of anaphylaxis caused by wheat were analyzed. RESULTS: Wheat was the most common food elicitor of anaphylaxis in adults in the registry in Central Europe. Reactions to wheat in adults were frequently associated with exercise as a cofactor (82.8%) and partially delayed (57.5%). Only 36.9% of patients had atopic comorbidities, which was uncommonly low for adult patients allergic to other kinds of foods (63.2%). Anaphylaxis to wheat presented frequently with cardiovascular symptoms (86.7%) including severe symptoms such as loss of consciousness (41%) and less often with respiratory symptoms (53.6%). The reactions to wheat were more severe than reactions to other foods (odds ratio [OR] = 4.33), venom (OR = 1.58), or drugs (OR = 2.11). CONCLUSIONS: Wheat is a relevant elicitor of anaphylaxis in adults in Central Europe. Wheat anaphylaxis is highly dependent on the presence of cofactors and less frequently associated with atopic diseases compared with other food allergies. More data on mechanisms of wheat-induced anaphylaxis are required to develop preventive measures for this potentially life-threatening disease.