Meat allergy associated with galactosyl-α-(1,3)-galactose (α-Gal)-Closing diagnostic gaps by anti-α-Gal IgE immune profiling

Connecting Diagnostics and Clinical Relevance of the α-Gal Syndrome-Individual Sensitization Patterns of Patients with Suspected α-Gal-Associated Allergy

BACKGROUND/OBJECTIVES

Sensitization to the carbohydrate antigen α-Gal is associated with allergic reactions against different types of food that contain α-Gal (e.g., mammalian meat). This form of allergy is termed α-Gal syndrome (AGS), and the diagnosis is challenging due to delayed symptom onset and cross-reactivity with multiple mammalian products. It is estimated that AGS is underdiagnosed, pointing to an unmet need for patient care.

METHODS

Sera from patients with suspected AGS based on clinical history were analyzed by ImmunoCAP and the IgE cross-reactivity immune profiling (ICRIP) system specifically developed by us. IgE from patient sera against different forms of α-Gal was analyzed using α-Gal-containing analytes and negative controls.

RESULTS

Sera from 33 patients with suspected AGS were analyzed. Sera from 22 patients yielded a clearly positive signal (>0.35 kU/L) for IgE against α-Gal in ImmunoCAP. For 7 of the remaining 11 patients with negative or ambiguous (IgE level between 0.1 and 0.35 kU/L) results in ImmunoCAP, ICRIP analyses supported the suspected association of the allergy symptoms with IgE against α-Gal components. This component-resolved analysis helps the allergist to provide an individual diagnosis for each patient.

CONCLUSIONS

The diagnosis of AGS is challenging. An interplay between clinical history and lab analysis via ImmunoCAP and the specifically developed ICRIP system helps patients and allergists in establishing the correct diagnosis, thereby preventing accidental exposure and recurrent AGS episodes.

Allergenic potency of various foods of mammalian origin in patients with α-Gal syndrome

BACKGROUND

The α-Gal syndrome (AGS) is an emerging allergy to mammalian food caused by IgE-mediated reactions to the carbohydrate galactose-α-1,3-galactose (α-Gal). Mammalian food sources contain α-Gal, but the amount differs. The objective of this study was to investigate the allergenic potency of various foods of mammalian origin among AGS patients.

METHODS

Twenty-six AGS patients were included. Food extracts from innards, lean meats, processed meat products, milk, and whey were analyzed. Immunoblot, ELISA, immunofluorescence, and basophil activation test were used to determine the α-Gal content, characterize IgE binding, and assess foods' allergenicity.

RESULTS

The determined amount of α-Gal, IgE reactivity to food extracts, and food extract potencies to activate patients' basophils correlated well with each other. Pork and beef kidney showed the highest allergenicity. Beef liver and bacon showed allergenicity comparable to that of lean meats. Game meat seemed to have a higher allergenic potency than meats from farm-raised animals. The processed meat products liver pâté and black pudding, despite lower α-Gal content, demonstrated moderate allergenicity. Milk showed the lowest allergenicity. IgE reactivity to food extracts was highly similar for all patients and strongly dominated by the α-Gal epitope.

CONCLUSIONS

The allergenic potency of mammalian meat depends on the origin of the meat, the different cuts, and type of processing, with innards posing the greatest risk to AGS patients. Even processed mammalian meat constitutes a risk. Dairy products show the lowest risk. This study highlights the importance of analyzing even more foods to improve the management of AGS.

Biologics in allergology and clinical immunology: Update on therapies for atopic diseases, urticaria, and angioedema and on safety aspects focusing on hypersensitivity reactions

The development of targeted therapies for atopic diseases, urticaria, and angioedema with biologics is progressing rapidly: New "targets" of clinical-therapeutic relevance have been identified, the corresponding targeted antibodies developed, tested in clinical trials, and approved for therapy. These include the anti-IgE antibody omalizumab (also effective and approved for the treatment of urticaria), the anti-IL-4/13 receptor-specific antibody dupilumab, the two anti-IL-13 antibodies lebrikizumab and tralokinumab, the anti-TSLP antibody tezepelumab, the two anti-IL-5 antibodies mepolizumab and reslizumab, and the anti-IL5 receptor-specific antibody benralizumab for the treatment of atopic diseases. For the treatment of hereditary angioedema, C1 inhibitor and the antibody lanadelumab (directed against kallikrein) have also long been approved as biologics in addition to low-molecular substances. Other therapeutic antibodies are in various stages of development. Furthermore, the range of indications for some very effective biologics has been successfully expanded to include additional diseases. In this context, the first results on biologic therapy of food allergy and eosinophilic esophagitis are interesting. Biologics that address different target structures are also increasingly being administered in combination, either simultaneously or sequentially, in order to achieve optimal efficacy. A developing area is the use of biologics in children and the observation of immunological and non-immunological side effects. In some cases, new unexpected side effects and hypersensitivity reactions have emerged, which in turn raise pathomechanistic questions, such as conjunctivitis with dupilumab therapy, which only appears to occur in the treatment of atopic dermatitis but not in the treatment of other atopic diseases. In dermatology, paradoxical reactions have been described under therapy with some biologics. And immune reactions of type alpha to epsilon to biologics (hypersensitivity reactions) continue to be a clinically relevant problem, whereby the selection of an alternative therapeutic agent is a challenge and the diagnostics that support this have not yet been sufficiently incorporated into routine work.

[Chronic rhinosinusitis with nasal polyps-extension of dupilumab treatment intervals]

BACKGROUND

In patients with severe, uncontrolled chronic rhinosinusitis with nasal polyps (CRSwNP), dupilumab 300 mg every 2 weeks can completely resolve nasal polys, sinus disease, and symptoms. In this case, patients ask for de-escalation. Although trials have demonstrated recurrence after stopping the biologic at 24 weeks, reducing the dose of dupilumab to once every 4 weeks did not result in deterioration of control. An extension of the treatment intervals would, however, diverge from the approval text, and is currently not recommended.

METHODS

The course of 29 patients with severe CRSwNP, type‑2 inflammation-associated comorbidities, and an indication for biologic was retrospectively analyzed. After resolution of CRSwNP and symptoms under biweekly dupilumab 300 mg, the dupilumab interval had been prolonged individually, initially up to 4 weeks, thereafter up to 6 weeks, if applicable. Control was assessed via quality of life (22-item sinonasal outcome test, SNOT-22), nasal polyp score, and smell identification test (Sniffin' Sticks; Burghart Messtechnik, Holm, Germany).

RESULTS

All patients showed an excellent improvement within the first 3 months. The dupilumab application interval was extended to 4 weeks after 7-31 months (median 13 months) and to 6 weeks (n = 9) after 17-35 months (median 23 months). No recurrent polyps or symptoms were subsequently observed.

CONCLUSION

In case of maximal regression of polyps and discomfort, extension of dupilumab injection intervals to 4 and potentially 6 weeks is possible without clinical worsening. Further studies on de-escalation or termination of biologic treatment when CRSwNP control is achieved are essential.

A systematic review of allergen cross-reactivity: Translating basic concepts into clinical relevance

Access to the molecular culprits of allergic reactions allows for the leveraging of molecular allergology as a new precision medicine approach-one built on interdisciplinary, basic, and clinical knowledge. Molecular allergology relies on the use of allergen molecules as in vitro tools for the diagnosis and management of allergic patients. It complements the conventional approach based on skin and in vitro allergen extract testing. Major applications of molecular allergology comprise accurate identification of the offending allergen thanks to discrimination between genuine sensitization and allergen cross-reactivity, evaluation of potential severity, patient-tailored choice of the adequate allergen immunotherapy, and prediction of its expected efficacy and safety. Allergen cross-reactivity, defined as the recognition of 2 or more allergen molecules by antibodies or T cells of the same specificity, frequently interferes with allergen extract testing. At the mechanistic level, allergen cross-reactivity depends on the allergen, the host's immune response, and the context of their interaction. The multiplicity of allergen molecules and families adds further difficulty. Understanding allergen cross-reactivity at the immunologic level and translating it into a daily tool for the management of allergic patients is further complicated by the ever-increasing number of characterized allergenic molecules, the lack of dedicated resources, and the need for a personalized, patient-centered approach. Conversely, knowledge sharing paves the way for improved clinical use, innovative diagnostic tools, and further interdisciplinary research. Here, we aimed to provide a comprehensive and unbiased state-of-the art systematic review on allergen cross-reactivity. To optimize learning, we enhanced the review with basic, translational, and clinical definitions, clinical vignettes, and an overview of online allergen databases.

Immunoassay Testing of Alpha-Gal Specific Immunoglobulin-E: Data from a National Reference Laboratory

BACKGROUND

Immunoassay measurements of serum alpha-gal (AG) specific IgE (sIgE) enable antibody detection and quantification with high sensitivity and specificity and are essential for AG syndrome diagnosis and patient management. We here present and analyze results from over 15 000 patient serum samples tested using the ImmunoCAP (Thermo/Phadia) assay.

METHODS

AG-sIgE levels and positivity rates were correlated to patient age, gender, geographic location, repeat testing results, sIgE levels to co-tested red meat whole allergen extracts, and Rocky Mountain spotted fever (RMSF) serology performed on a subset of patient samples.

RESULTS

Of the tested samples, 36.7% contained detectable (>0.1 KUA/L) AG-sIgE. Antibody levels were higher in patients of older age, in samples submitted from lower midwestern and southern states, and during the June-December period of the year. Specific IgE to co-tested red meat whole allergens showed moderate to strong correlation to AG-sIgE and were of lower levels. Samples with positive RMSF IgG titers (≥1:64) were of overall higher AG-IgE levels.

CONCLUSION

Findings are consistent with the role of lone star ticks in AG syndrome pathogenesis. Levels of measured sIgE to AG are higher than co-tested sIgE to red meat whole allergen, consistent with the improved diagnostic performance of component-resolved testing.

The α-Gal epitope - the cause of a global allergic disease

The galactose-α-1,3-galactose (α-Gal) epitope is the cause of a global allergic disease, the α-Gal syndrome (AGS). It is a severe form of allergy to food and products of mammalian origin where IgE against the mammalian carbohydrate, α-Gal, is the cause of the allergic reactions. Allergic reactions triggered by parenterally administered α-Gal sources appear immediately, but those triggered via the oral route appear with a latency of several hours. The α-Gal epitope is highly immunogenic to humans, apes and old-world monkeys, all of which produce anti-α-Gal antibodies of the IgM, IgA and IgG subclasses. Strong evidence suggests that in susceptible individuals, class switch to IgE occurs after several tick bites. In this review, we discuss the strong immunogenic role of the α-Gal epitope and its structural resemblance to the blood type B antigen. We emphasize the broad abundance of α-Gal in different foods and pharmaceuticals and the allergenicity of various α-Gal containing molecules. We give an overview of the association of tick bites with the development of AGS and describe innate and adaptive immune response to tick saliva that possibly leads to sensitization to α-Gal. We further discuss a currently favored hypothesis explaining the mechanisms of the delayed effector phase of the allergic reaction to α-Gal. We highlight AGS from a clinical point of view. We review the different clinical manifestations of the disease and the prevalence of sensitization to α-Gal and AGS. The usefulness of various diagnostic tests is discussed. Finally, we provide different aspects of the management of AGS. With climate change and global warming, the tick density is increasing, and their geographic range is expanding. Thus, more people will be affected by AGS which requires more knowledge of the disease.

Oral immunotherapy in alpha-gal red meat allergy: Could specific IgE be a potential biomarker in monitoring management?

BACKGROUND

Oral immunotherapy (OIT) is a promising treatment for food allergies. Our aim was to establish the long-term safety and efficacy of a novel red meat (RM) OIT in galactose-alpha-1,3-galactose (alpha-gal) allergy in adults.

METHODS

Out of 20 patients with confirmed RM allergy, five (41.66%) underwent an early OIT, seven (58.33%) underwent a delayed protocol and eight patients who were not desensitized formed the patient control group. 15 and 27 day RM OIT for early-onset and delayed-onset alpha-gal allergy were administered, respectively. Desensitized patients were recommended to continue eating at least 100 g RM every day for 6 months and every other day in the following 6 months. After a year, the consumption was recommended 2/3 times in a week. Patients were followed up with skin tests with commercial beef and lamb extracts, fresh raw/cooked beef and lamb and cetuximab and also with serum alpha-gal specific Immunoglobulin-E (sIgE) in the first and fifth years.

RESULTS

All patients who underwent OIT became tolerant to RM. During the 5 year follow-up, the median alpha-gal sIgE concentration gradually decreased in nine patients who consumed RM uneventfully while remained unchanged in the control group (p = .016). In two patients, rare tick bites acted as inducers of hypersensitivity reactions with concomitant elevation of alpha-gal sIgE concentrations whereas one patient with low follow-up alpha-gal sIgE concentrations consumed RM uneventfully after frequent tick bites.

CONCLUSIONS

Our study showed the long-term safety and efficacy of alpha-gal OIT. Additionally, alpha-gal sIgE seems to be a potential biomarker to monitor OIT.

Study protocol to investigate the efficacy of confocal laser endomicroscopy-based selective single-elimination diet over standard fivefold elimination diet in patients with endomicroscopically proven food intolerance: app-assisted, monocentric, double-blind, randomised and controlled trial in Germany

INTRODUCTION

Imprecise nutritional recommendations due to a lack of diagnostic test accuracy are a frequent problem for individuals with adverse reactions to foods but no precise diagnosis. Consequently, patients follow very broad and strict elimination diets to avoid uncontrolled symptoms such as diarrhoea and abdominal pain. Dietary limitations and the uncertainty of developing gastrointestinal symptoms after the inadvertent ingestion of food have been demonstrated to reduce the quality of life (QoL) of affected individuals and subsequently might increase the risk of malnutrition and intestinal dysbiosis. This trial aims to investigate the effects of a tailored diet based on the confocal laser endoscopy (CLE) examination result to limit the side effects of unspecific and broad elimination diets and to increase the patient's QoL.

METHODS AND ANALYSIS

The study is designed as a prospective, double-blind, monocentric, randomised and controlled trial conducted at the University Hospital of Schleswig-Holstein, Campus Lübeck, Germany. One hundred seventy-two patients with non-IgE-related food allergies and positive CLE results will be randomised to either a tailored diet or a standard fivefold elimination diet. The primary endpoints are the difference between the end and the start of the intervention in health-related QoL and the sum score of the severity of symptoms after 12 weeks. Key secondary endpoints are changes in the severity of symptoms, further QoL measurements, self-assessed state of health and number of days with a pathologically altered stool. Microbiome diversity and metabolome of stool, urine and blood will also be investigated. Safety endpoints are body composition, body mass index and adverse events.

ETHICS AND DISSEMINATION

The study protocol was accepted by the ethical committee of the University of Lübeck (AZ: 22-111) on 4 May2022. Results of the study will be published in peer-reviewed journals and presented at scientific meetings.

TRIAL REGISTRATION NUMBER

German Clinical Trials Register (DRKS00029323).

Clinical Use of the ImmunoCAP Inhibition Test in the Diagnosis of Meat Allergy Caused by a Tick Bite in an Adult Male with No Previous Atopic History

(1) Background: alpha-gal syndrome (AGS) is a serious, potentially life-threatening allergic reaction. This is a type of food allergy to red meat and other mammalian products (e.g., gelatin). In Poland, this problem seems to be rare or, more likely, very underdiagnosed. The diagnosis of AGS is difficult. It seems that the knowledge about this syndrome is insufficient. There are no effective diagnostic tools able to clearly diagnose this cross-reactive allergy. This paper presents the clinical application of a non-standard method in the diagnosis of a cross-reactive allergy using the example of AGS. (2) Methods: standard tests for in vitro allergy diagnostics and the non-standard ImmunoCAP inhibition test(IT) were carried out for serum collected from a patient with a red meat allergy. (3) Results: the serum concentration of anti-α-Gal IgE was very high (302 kUA/L), and IgE antibodies toanti-mammalian-meat allergens were found. The level of IgE antibodies to mammalian meat allergens decreased after blocking on α-GAL-CAP. The concentration of anti-α-Gal IgE decreased after blocking on CAPs coated with various mammalian meat allergens. Blocking with allergens of poultry meat did not affect the concentration of anti-α-Gal IgE. (4) Conclusions: the ImmunoCAP ITseems to be a useful tool in the diagnosis of cross-reactive allergies. Based on their clinical history and test results, the patient was diagnosed with AGS caused by a primary sensitization to α-Gal after a tick bite. This is the second case of AGS described in Poland and the first in Pomerania.

Specific IgE against the house dust mite allergens Der p 5, 20 and 21 influences the phenotype and severity of atopic diseases

BACKGROUND

House dust mites (HDM) are among the most important sources for airborne allergens with high relevance for atopic diseases. Routine tests contain only 4 of 32 registered allergens of Dermatophagoides pteronyssinus. Clinical relevance and pathomechanistic properties of many allergens are not well understood.

OBJECTIVE

The association of several HDM allergens with allergic rhinitis, allergic asthma, and atopic dermatitis was investigated to identify allergens with biomarker potential and to transfer them into diagnostics.

METHODS

Eight out of nine D. pteronyssinus allergens (nDer p 1, rDer p 2, rDer p 5, rDer p 7, rDer p 10, rDer p 13, rDer p 20, rDer p 21, rDer p 23) were recombinantly expressed and purified. Sensitization patterns of 384 HDM-allergic individuals exhibiting different clinical phenotypes were analyzed with a serum-saving multiplex array.

RESULTS

Sensitization to more than three mite allergens (sensitization count) was associated with allergic asthma and/or atopic dermatitis. Reactions to Der p 5 and Der p 21 were more frequent in allergic asthma compared to allergic rhinitis. Atopic dermatitis patients were more often sensitized to Der p 5, Der p 20, and Der p 21 among others. Der p 20-IgE > 80 kU/L was associated with severe atopic dermatitis in 75% of patients.

CONCLUSION

This study demonstrates the clinical importance of the sensitization count and of certain allergens (Der p 5, Der p 20, and Der p 21) not available for routine diagnostics yet. Implementing them as well as the sensitization count in diagnostic measures will improve diagnosis and risk assessment of HDM-allergic patients.

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.

The Two-Sided Experimental Model of ImmunoCAP Inhibition Test as a Useful Tool for the Examination of Allergens Cross-Reactivity on the Example of α-Gal and Mammalian Meat Sensitization-A Preliminary Study

Cross-reactivity of allergens is the cause of various, sometimes unexpected, clinical reactions. There are no standard methods to investigate cross-reactivity. We present an experimental model of a two-sided inhibition test (IT) on ImmunoCAP membranes (CAP). We constructed the described model based on the known cross-allergy syndrome to red meat developing in people bitten by ticks (α-Gal syndrome; AGS). Some individuals who are bitten by ticks develop IgE antibodies specific to the carbohydrate determinant, galactose-α-1,3-galactose (α-Gal), present in the tick's saliva. These antibodies can cross-react with α-Gal molecules expressed on mammalian meat proteins. The well-known property of anti-α-Gal IgE antibodies binding by various sources of this allergen was used by us in the proposed model of the two-sided inhibition test on ImmunoCAP membranes. We expected that anti-α-Gal IgE antibodies bind allergens from mammalian meat and blocking them abolishes this reactivity, and the two-sided inhibition test model we proposed on ImmunoCAP membranes allowed us to observe such a relationship. We conducted the experiment three times on biological material from people with different clinical manifestations of allergy to α-Gal, each time obtaining similar results. In conclusion, the model of bilateral inhibition on ImmunoCAP membranes proposed by us seems to be an attractive, simple tool for direct testing of allergic cross-reactivity.

The Meat of the Matter: Understanding and Managing Alpha-Gal Syndrome

Alpha-gal syndrome is an unconventional food allergy, characterized by IgE-mediated hypersensitivity responses to the glycan galactose-alpha-1,3-galactose (alpha-gal) and not to a food-protein. In this review, we discuss how alpha-gal syndrome reframes our current conception of the mechanisms of pathogenesis of food allergy. The development of alpha-gal IgE is associated with tick bites though the possibility of other parasites promoting sensitization to alpha-gal remains. We review the immune cell populations involved in the sensitization and effector phases of alpha-gal syndrome and describe the current understanding of why allergic responses to ingested alpha-gal can be delayed by several hours. We review the foundation of management in alpha-gal syndrome, namely avoidance, but also discuss the use of antihistamines, mast cell stabilizers, and the emerging role of complementary and alternative therapies, biological products, and oral immunotherapy in the management of this condition. Alpha-gal syndrome influences the safety and tolerability of medications and medical devices containing or derived from mammalian products and impacts quality of life well beyond food choices.

Current and Future Strategies for the Diagnosis and Treatment of the Alpha-Gal Syndrome (AGS)

The α-Gal syndrome (AGS) is a pathognomonic immunoglobulin E (IgE)-mediated delayed anaphylaxis in foods containing the oligosaccharide galactose-α-1,3-galactose (α-Gal) such as mammalian meat or dairy products. Clinical presentation of AGS can also comprise immediate hypersensitivity due to anticancer therapy, gelatin-containing vaccines or mammalian serum-based antivenom. The IgE initial sensitization is caused by hard-bodied tick bites and symptomatic individuals typically develop delayed pruritus, urticaria, angioedema, anaphylaxis, malaise or gut-related symptoms. Due to inapparent presentation, delayed reactions and a wide variety of patients´ clinical history, the AGS diagnosis and treatment remain challenging. This review covers not only current diagnostic methods used for AGS such as the skin prick test (SPT), the oral food challenge (OFC), anti-α-Gal IgE levels measurement and the basophil activation test (BAT), but also potentially relevant next-generation diagnostic tools like the mast cell activation test (MAT), the histamine-release (HR) assay, omics technologies and model-based reasoning (MBR). Moreover, it focuses on the therapeutical medical and non-medical methods available and current research methods that are being applied in order to elucidate the molecular, physiological and immune mechanisms underlying this allergic disorder. Lastly, future treatment and preventive tools are also discussed, being of utmost importance for the identification of tick salivary molecules, with or without α-Gal modifications, that trigger IgE sensitivity as they could be the key for further vaccine development. Bearing in mind climate change, the tick-host paradigm will shift towards an increasing number of AGS cases in new regions worldwide, which will pose new challenges for clinicians in the future.

α-Gal present on both glycolipids and glycoproteins contributes to immune response in meat-allergic patients

BACKGROUND

The α-Gal syndrome is associated with the presence of IgE directed to the carbohydrate galactose-α-1,3-galactose (α-Gal) and is characterized by a delayed allergic reaction occurring 2 to 6 hours after ingestion of mammalian meat. On the basis of their slow digestion and processing kinetics, α-Gal-carrying glycolipids have been proposed as the main trigger of the delayed reaction.

OBJECTIVE

We analyzed and compared the in vitro allergenicity of α-Gal-carrying glycoproteins and glycolipids from natural food sources.

METHODS

Proteins and lipids were extracted from pork kidney (PK), beef, and chicken. Glycolipids were purified from rabbit erythrocytes. The presence of α-Gal and IgE binding of α-Gal-allergic patient sera (n = 39) was assessed by thin-layer chromatography as well as by direct and inhibition enzyme-linked immunosorbent assay. The in vitro allergenicity of glycoproteins and glycolipids from different meat extracts was determined by basophil activation test. Glycoprotein stability was evaluated by simulated gastric and intestinal digestion assays.

RESULTS

α-Gal was detected on glycolipids of PK and beef. Patient IgE antibodies recognized α-Gal bound to glycoproteins and glycolipids, although binding to glycoproteins was more potent. Rabbit glycolipids were able to strongly activate patient basophils, whereas lipid extracts from PK and beef were also found to trigger basophil activation, but at a lower capacity compared to the respective protein extracts. Simulated gastric digestion assays of PK showed a high stability of α-Gal-carrying proteins in PK.

CONCLUSION

Both α-Gal-carrying glycoproteins and glycolipids are able to strongly activate patient basophils. In PK and beef, α-Gal epitopes seem to be less abundant on glycolipids than on glycoproteins, suggesting a major role of glycoproteins in delayed anaphylaxis upon consumption of these food sources.

Poly-L-Lysine-Based αGal-Glycoconjugates for Treating Anti-αGal IgE-Mediated Diseases

Anti-αGal IgE antibodies mediate a spreading allergic condition known as αGal-syndrome (AGS). People exposed to hard tick bites are sensitized to αGal, producing elevated levels of anti-αGal IgE, which are responsible for AGS. This work presents an immunotherapy based on polymeric αGal-glycoconjugates for potentially treating allergic disorders by selectively inhibiting anti-αGal IgE antibodies. We synthesized a set of αGal-glycoconjugates, based on poly-L-lysine of different degrees of polymerization (DP1000, DP600, and DP100), to specifically inhibit in vitro the anti-αGal IgE antibodies in the serum of αGal-sensitized patients (n=13). Moreover, an animal model for αGal sensitization in GalT-KO mice was developed by intradermal administration of hard tick' salivary gland extract, mimicking the sensitization mechanism postulated in humans. The in vitro exposure to all polymeric glycoconjugates (5-10-20-50-100 µg/mL) mainly inhibited anti-αGal IgE and IgM isotypes, with a lower inhibition effect on the IgA and IgG, respectively. We demonstrated a differential anti-αGal isotype inhibition as a function of the length of the poly-L-lysine and the number of αGal residues exposed in the glycoconjugates. These results defined a minimum of 27 αGal residues to inhibit most of the induced anti-αGal IgE in vitro. Furthermore, the αGal-glycoconjugate DP1000-RA0118 (10 mg/kg sc.) showed a high capacity to remove the anti-αGal IgE antibodies (≥75% on average) induced in GalT-KO mice, together with similar inhibition for circulating anti-αGal IgG and IgM. Our study suggests the potential clinical use of poly-L-lysine-based αGal-glycoconjugates for treating allergic disorders mediated by anti-αGal IgE antibodies.

Component resolved diagnosis and risk assessment in food allergy

Allergy testing should only be performed in the context of the clinical history as history provides the cornerstone of diagnosis. In food allergy, some allergy tests often give rise to false positive results and thus can lead to unnecessary avoidance or delay on foods introduction. The use of Component Resolved Diagnosis in combination with conventional sensitization testing improves analytical and diagnostic performance and can lead to the reduction of diagnostic oral food challenges. Component Resolved Diagnosis can be helpful in identifying some risks for the allergic child. Molecular diagnosis can help also in predicting the development of the allergy march, in severe reactions (lipid transfer protein, seed storage proteins, etc.) in food allergy and for potential clinical cross-reactivity.

Carbohydrate epitopes currently recognized as targets for IgE antibodies

Until recently, glycan epitopes have not been documented by the WHO/IUIS Allergen Nomenclature Sub-Committee. This was in part due to scarce or incomplete information on these oligosaccharides, but also due to the widely held opinion that IgE to these epitopes had little or no relevance to allergic symptoms. Most IgE-binding glycans recognized up to 2008 were considered to be "classical" cross-reactive carbohydrate determinants (CCD) that occur in insects, some helminths and throughout the plant kingdom. Since 2008, the prevailing opinion on lack of clinical relevance of IgE-binding glycans has been subject to a reevaluation. This was because IgE specific for the mammalian disaccharide galactose-alpha-1,3-galactose (alpha-gal) was identified as a cause of delayed anaphylaxis to mammalian meat in the United States, an observation that has been confirmed by allergists in many parts of the world. Several experimental studies have shown that oligosaccharides with one or more terminal alpha-gal epitopes can be attached as a hapten to many different mammalian proteins or lipids. The classical CCDs also behave like haptens since they can be expressed on proteins from multiple species. This is the explanation for extensive in vitro cross-reactivity related to CCDs. Because of these developments, the Allergen Nomenclature Sub-Committee recently decided to include glycans as potentially allergenic epitopes in an adjunct section of its website (www.allergen.org). In this article, the features of the main glycan groups known to be involved in IgE recognition are revisited, and their characteristic structural, functional, and clinical features are discussed.

Immune-Inflammatory Responses of an Acellular Cartilage Matrix Biomimetic Scaffold in a Xenotransplantation Goat Model for Cartilage Tissue Engineering

The rapid development of tissue engineering and regenerative medicine has introduced a new strategy for ear reconstruction, successfully regenerating human-ear-shaped cartilage and achieving the first clinical breakthrough using a polyglycolic acid/polylactic acid (PGA/PLA) scaffold. However, its clinical repair varies greatly among individuals, and the quality of regenerated cartilage is unstable, which seriously limits further clinical application. Acellular cartilage matrix (ACM), with a cartilage-specific microenvironment, good biocompatibility, and potential to promote cell proliferation, has been used to regenerate homogeneous ear-shaped cartilage in immunocompromised nude mice. However, there is no evidence on whether ACM will regenerate homogeneous cartilage tissue in large animals or has the potential for clinical transformation. In this study, xenogeneic ACM assisted with gelatin (GT) with or without autologous chondrocytes was implanted subcutaneously into goats to establish a xenotransplantation model and compared with a PGA/PLA scaffold to evaluate the immune-inflammatory response and quality of regenerated cartilage. The results confirmed the superiority of the ACM/GT, which has the potential capacity to promote cell proliferation and cartilage formation. Although there is a slight immune-inflammatory response in large animals, it does not affect the quality of the regenerated cartilage and forms homogeneous and mature cartilage. The current study provides detailed insights into the immune-inflammatory response of the xenogeneic ACM/GT and also provides scientific evidence for future clinical application of ACM/GT in cartilage tissue engineering.

'Doc, will I ever eat steak again?': diagnosis and management of alpha-gal syndrome

PURPOSE OF REVIEW

Alpha-gal syndrome encompasses a constellation of symptoms associated with immune-mediated hypersensitivity responses to galactose-alpha-1,3-galactose (alpha-gal). The purpose of this review is to discuss our current understanding of the etiology, clinical symptoms, natural history, epidemiology, and management of alpha-gal syndrome.

RECENT FINDINGS

Sensitization to alpha-gal is associated with bites from ectoparasites like the lone star tick Amblyomma americanum. Allergic reactions in alpha-gal syndrome are often delayed and inconsistent. The magnitude of the allergic response depends on co-factors like exercise and alcohol consumption and the amount of alpha-gal and fat present in the food. Assaying alpha-gal-specific IgE in the serum is the primary diagnostic test used to confirm the allergy. Long-term management of the condition involves avoidance of both mammalian food products and tick bites.

SUMMARY

Alpha-gal syndrome disrupts the current paradigm for understanding food allergy. Exposure to an ectoparasite is critical for the development of specific IgE antibodies underlying sensitization, and allergic reactions depend on the activation of mast cells and basophils sensitized with IgE against a carbohydrate rather than a protein. Research in this field may lead to the development of improved diagnostic and therapeutic tools that can revolutionize the management of patients with alpha-gal syndrome.

Safety of Intravenous Heparin for Cardiac Surgery in Patients With Alpha-Gal Syndrome

BACKGROUND

Alpha-gal syndrome is a tick-acquired disease caused by immunoglobulin E (IgE) to the oligosaccharide galactose-alpha-1,3-galactose (alpha-gal), causing allergic reactions to meat and products sourced from nonprimate mammals. As heparin is porcine-derived, we hypothesized that patients with alpha-gal syndrome who received high-dose heparin for cardiac surgery would have increased risk of anaphylaxis.

METHODS

All cardiac surgery patients at an academic medical center from 2007 to 2019 were cross-referenced with research and clinical databases for the alpha-gal IgE blood test. Clinical data were obtained through the institutional Society of Thoracic Surgeons Adult Cardiac Database and chart review. Patients were stratified by development of an allergic reaction for univariate statistical analysis.

RESULTS

Of the 8819 patients, 17 (0.19%) had a positive alpha-gal test before cardiac surgery. Of these 17 patients, 4 (24%) had a severe allergic reaction. The median alpha-gal titer was significantly higher in patients with a reaction (75 [interquartile range, 61-96] IU/mL vs 8 [interquartile range, 3-18] IU/mL; P = .006). There were no differences in median heparin loading dose, total dose, or maximum activated clotting time (all P > .05). In a subgroup of 8 patients with recent alpha-gal IgE level, 4 (50%) developed an allergic reaction.

CONCLUSIONS

Although alpha-gal is rare in patients undergoing cardiac surgery, there is up to a 50% risk of serious allergic reaction to heparin for cardiopulmonary bypass. Higher preoperative alpha-gal titers may confer a higher risk of severe allergic reaction. For patients with a clinical suspicion of alpha-gal syndrome, we recommend prescreening with IgE levels and premedicating before receiving high doses of intravenous heparin.

Alpha-gal syndrome: challenges to understanding sensitization and clinical reactions to alpha-gal

INTRODUCTION

The α-Gal syndrome (AGS) is a type of allergy characterized by an IgE antibody response against the carbohydrate Galα1-3Galβ1-4GlcNAc-R (α-Gal). Tick bites are recognized as the most important cause of anti-α-Gal IgE antibody increase in humans. Several risk factors have been associated with the development of AGS, but their integration into a standardized disease diagnosis has proven challenging.

AREAS COVERED

Herein we discuss the current AGS diagnosis based on anti-α-Gal IgE titers and propose an algorithm that considers all co-factors in the clinical history of α-Gal-sensitized patients to be incorporated into the AGS diagnosis. The need for identification of host-derived gene markers and tick-derived proteins for the diagnosis of the AGS is also discussed.

EXPERT OPINION

The current AGS diagnosis based on anti-α-Gal IgE titers has limitations because not all patients sensitized to α-Gal and with anti-α-Gal IgE antibodies higher than the cutoff (0.35 IU/ml) develop anaphylaxis to mammalian meat and AGS. The basophil activation test proposed to differentiate between patients with AGS and asymptomatic α-Gal sensitization cannot be easily implemented as a generalized clinical test. In coming years, the algorithm proposed here could be used in a mobile application for easier AGS diagnosis in the clinical practice.

Alpha-gal syndrome: An emerging cause of food and drug allergy

Alpha-gal syndrome (AGS) describes a wide spectrum of hypersensitivity reactions mediated by specific IgE to the α-gal epitope (galactose-α-1,3-galactose) ubiquitously expressed on glycolipids/glycoproteins of most mammals. This fascinating new entity has completely changed the paradigms of allergy as allergic response is directed against an oligosaccharide and the reactions can be both immediate and delayed. They appear to be stimulated only by tick bites which induce production of α-gal specific IgE antibodies that lead to (at times fatal) hypersensitivity response. AGS is completely different to previously described anaphylaxis to tick saliva. It provides unique insight into the interplay between different arms of the immune system and the role of ectoparasites in the development of anaphylaxis to food and medication in patients at risk of tick bites including travellers. This review summarises recent advances in our understanding of its clinical presentation, pathomechanism and role of various tick species in the development of AGS.

Hypersensitivity reactions to biologics (part II): classifications and current diagnostic and treatment approaches

Purpose

Biotechnological substances (BS) have rapidly expanded their clinical use. In parallel, there is an increase in expected or unexpected immunological or non-immunological adverse effects. In this part of the review, the current nomenclature of BSs, the classification of hypersensitivity reactions (HSR), as well as diagnostic and treatment approaches are documented to provide the tools to understand the nomenclature used throughout the databases and the need to harmonize it where applicable.

Methods

Detailed searches were performed on Pubmed, Web of Science, and Google Scholar to include all available publications. The search terms, such as specific BS, allergy, anaphylaxis, hypersensitivity, reactions, classification, diagnosis, grading, management, and desensitization, were determined for the search. Case reports, articles, and reviews on this subject were included.

Results

Today, a variety of non-standardized methods are used to support the clinical diagnosis. These include prick-to-prick tests and intradermal tests with the drug itself and its potentially allergenic ingredients. More rarely, anti-drug antibodies are detected and basophil activation tests are used by centers with research facilities. Although the treatment protocols for acute conditions vary, the overall approach is the same.

Conclusion

HSRs to BS are gradually increasing with the widening of their clinical use and indications. It is very important to prevent HSRs and to know the degree of severity as well as the emergency treatment algorithm. This review summarizes the diagnostic tests that should be applied: (a) immediately during/after a reaction, and (b) subsequently, and in the case that a switch of BS is not possible, desensitization is an option.

Galactose-α-1,3-galactose (alpha-gal) allergy: first pediatric case in a series of patients in Spain

INTRODUCTION AND OBJECTIVES

Allergy to galactose-α-1,3-galactose (alpha-gal) is a peculiar form of food allergy generally manifesting as an anaphylactic reaction hours after mammalian meat consumption, due to the presence of specific IgE against this oligosaccharide. In addition, immediate anaphylaxis may develop after exposure to other sources of alpha-gal, such as monoclonal antibody cetuximab, vaccines, plasma expanders or anti-snake venoms. Sensitization to alpha-gal has also been implicated in the rapid degeneration of biological valve implants, and recognized as a cause of occupational disease in cattle raisers. The implication of tick bites in this type of sensitization has been accepted by all the research groups dedicated to this disease.

PATIENTS AND METHOD

The present study describes the clinical and sensitization characteristics of 39 patients diagnosed with alpha-gal allergy in the hospitals of our province (Lugo, Monforte de Lemos and Burela, Spain).

RESULTS

Most patients were middle-age males. Of note, is the fact that the series includes the first pediatric patient reported in Spain to date. The predominant clinical manifestations were urticaria or delayed anaphylaxis after consumption of mammalian meat. Seventy-four percent of the patients reported having suffered a previous tick bite, and the clinical presentation of anaphylaxis was significantly more prevalent in those with a persistent local reaction following the bite than in those with no such reaction (p = 0.032).

CONCLUSIONS

A review is also made of the disorder which, due to its variable clinical expression, is referred to as alpha-gal syndrome. The study concludes that a diagnosis of alpha-gal allergy should be considered in patients with urticaria-anaphylaxis of uncertain origin or manifesting after the administration of vaccines or products of bovine/porcine origin.

On the cause and consequences of IgE to galactose-α-1,3-galactose: A report from the National Institute of Allergy and Infectious Diseases Workshop on Understanding IgE-Mediated Mammalian Meat Allergy

The mammalian meat allergy known as the "α-Gal syndrome" relates to IgE specific for galactose-α-1,3-galactose (α-Gal), an oligosaccharide that is present in cells and tissues of nonprimate mammals. The recognition of delayed reactions to food derived from mammals in patients with IgE to α-Gal and also the association with tick bites have been increasing worldwide. In 2018, the National Institute of Allergy and Infectious Diseases, Division of Allergy, Immunology and Transplantation, sponsored a workshop on this emerging tick-related disease. International experts from the fields of tick biology, allergy, immunology, infectious disease, and dermatology discussed the current state of our understanding of this emerging medical condition. The participants provided suggestions for specific research priorities and for the development of resources to advance our knowledge of the mechanisms, diagnosis, management, and prevention of this allergic disease. This publication is a summary of the workshop and the panel's recommendations are presented herein.

Alpha-Gal and Cross-Reactive Carbohydrate Determinants in the N-Glycans of Salivary Glands in the Lone Star Tick, Amblyomma americanum

Ticks are important ectoparasites and vectors of numerous human and animal pathogens. Ticks secrete saliva that contains various bioactive materials to evade the host defense system, and often facilitates the pathogen transmission. In addition, the Lone star tick saliva is thought to be the sensitizer in red meat allergy that is characterized by an allergic reaction to glycan moieties carrying terminal galactose-alpha-1,3-galactose (aGal). To assess N-glycome of Amblyomma americanum, we examined the N-glycan structures in male and female salivary glands at three different feeding stages and in carcasses of partially fed lone star ticks. We also surveyed the genes involved in the N-glycosylation in the tick species. The aGal epitopes and cross-reactive carbohydrate determinants (CCD) increases over time after the onset of blood feeding in both male and female A. americanum. These CCDs include xylosylation of the core mannose, 1,3-mono and 1,3- and 1,6-difucosylations of the basal GlcNac and mono- or diantennary aGal. Combinations of both xylosylation and aGal and fucosylation and aGal were also found on the N-glycan structures. While the enzymes required for the early steps of the N-glycosylation pathway are quite conserved, the enzymes involved in the later stages of N-glycan maturation in the Golgi apparatus are highly diverged from those of insects. Most of all, we propose that the aGal serves as a molecular mimicry of bioactive proteins during tick feedings on mammalian hosts, while it contributes as a sensitizer of allergy in atypical host human.

Idiopathic anaphylaxis yardstick: Practical recommendations for clinical practice

Anaphylaxis is considered idiopathic when there is no known trigger. The signs and symptoms of idiopathic anaphylaxis (IA) are identical to those of anaphylaxis because of a known cause and can include cutaneous, circulatory, respiratory, gastrointestinal, and neurologic symptoms. Idiopathic anaphylaxis can be a frustrating disease for patients and health care providers. Episodes are unpredictable, and differential diagnosis is challenging. Current anaphylaxis guidelines have little specific guidance regarding differential diagnosis and long-term management of IA. Therefore, the objective of the Idiopathic Anaphylaxis Yardstick is to use published data and the authors' combined clinical experience to provide practical recommendations for the diagnosis and management of patients with IA.

[Alpha-Gal-associated delayed red meat anaphylaxis as an occupational disease]

In a 30-year-old chef with recurrent delayed angioedema history as well as the experimental detection of IgE antibodies against galactose-alpha-(1,3)-galactose (alpha-Gal) pointed to alpha-Gal as the causative agent. The diagnosis, therefore, was delayed anaphylaxis due to alpha-Gal. Because of the potential relationship to his profession, we submitted a dermatologist's report BK 5101 to the liability and insurance association, whereupon his contract of employment was terminated without notice. As a consequence, we reported an occupational disease. This case demonstrates an underdiagnosed, potentially life-threatening allergy to the disaccharide alpha-Gal in red meat as an occupational disease.

ABO blood type and risk of porcine bioprosthetic aortic valve degeneration: SWEDEHEART observational cohort study

OBJECTIVE

Blood type A antigen on porcine aortic bioprostheses might initiate an immune reaction leading to an increased frequency of structural valve deterioration in patients with blood type B or O. The aim was to analyse the association between ABO blood type and porcine bioprosthetic aortic valve degeneration.

DESIGN

Observational nationwide cohort study.

SETTING

Swedish population-based study.

PARTICIPANTS

Adult patients (n=3417) who underwent surgical aortic valve replacement and received porcine bioprosthetic aortic valves between 1995 and 2012 from the Swedish Web system for Enhancement and Development of Evidence-based care in Heart disease Evaluated According to Recommended Therapies register. The study database was enriched with information from other national registers.

EXPOSURE

The patients were categorised into type A/AB and type B/O blood groups.

PRIMARY AND SECONDARY OUTCOME MEASURES

Primary outcome measure was aortic valve reoperation, and secondary outcomes were heart failure and all-cause mortality. We report risk estimates that account for the competing risk of death.

RESULTS

In total, 3417 patients were identified: 1724 (50.5%) with blood type A/AB and 1693 (49.5%) with blood type B/O. Both groups had similar baseline characteristics. The cumulative incidence of aortic valve reoperation was 3.4% (95% CI 2.5% to 4.4%) and 3.6% (95% CI 2.6% to 4.6%) in the type B/O and the A/AB group, respectively, at 15 years of follow-up (absolute risk difference: -0.2% (95% CI -1.5% to 1.2%)). There was no significantly increased risk for aortic valve reoperation in patients with blood type B/O compared with type A/AB (HR 0.95, 95% CI 0.62 to 1.45). There was no significant difference in absolute or relative risk of heart failure or death between the groups.

CONCLUSIONS

We found no significant association between patient blood type and clinical manifestations of structural valve deterioration following porcine aortic valve replacement. Our findings suggest that it is safe to use porcine bioprosthetic valves without consideration of ABO blood type in the recipient.

TRIAL REGISTRATION NUMBER

NCT02276950.

Meat allergy and allergens

IgE-mediated hypersensitivity to ingested animal products, including both mammalian and avian sources, is increasingly appreciated as an important form of food allergy. Traditionally described largely in children, it is now clear that allergy to meat (and animal viscera) impacts both children and adults and represents a heterogeneous group of allergic disorders with multiple distinct syndromes. The recognition of entities such as pork-cat syndrome and delayed anaphylaxis to red meat, i.e- the α-Gal syndrome, have shed light on fundamental, and in some cases newly appreciated, features of allergic disease. These include insights into routes of exposure and mechanisms of sensitization, as well as the realization that IgE-mediated reactions can be delayed by several hours. Here we review mammalian and avian meat allergy with an emphasis on the molecular allergens and pathways that contribute to disease, as well as the role of in vitro IgE testing in diagnosis and management.

Glycan and Peptide IgE Epitopes of the TNF-alpha Blockers Infliximab and Adalimumab - Precision Diagnostics by Cross-Reactivity Immune Profiling of Patient Sera

Biological drugs like therapeutic antibodies are widely used for the treatment of various diseases like inflammatory disorders and cancer. A drawback of these novel treatments is the substantial proportion of patients experiencing adverse reactions such as loss-of-drug effect or hypersensitivity reactions. These reactions are associated with pre-existing and/or developing anti-drug antibodies. Especially IgE development is a risk factor for life-threatening systemic anaphylaxis.

Methods: In order to characterize the individual drug-specific serum IgE, an IgE cross-reactivity immune profiling (ICRIP) assay was developed. Individual IgG epitopes of anti-drug antibodies against adalimumab were identified by epitope mapping via peptide microarray.

Results: ICRIP analyses of sera from patients treated with the therapeutic antibodies adalimumab (ADL) and infliximab (IFX) reveal individual, distinct IgE binding patterns. IgG epitopes were identified mostly located in the variable region of ADL.

Conclusions: Using ICRIP and peptide microarrays for pharmacovigilance of the TNF-α blockers IFX and ADL, risk factors and biomarkers before and during therapy shall be identified. These diagnostic systems provide the basis for a safe and efficacious therapy decision for each patient in cases of adverse drug reactions mediated by different types of anti-drug antibodies.