Utility of Component-Resolved Diagnostics in Food Allergy

Current Practice in Pediatric Cow's Milk Protein Allergy-Immunological Features and Beyond

Cow's milk protein allergy is one of the most common pediatric food allergies. It poses a significant socioeconomic burden in industrialized countries and has a profound effect on the quality of life of affected individuals and their families. Diverse immunologic pathways can lead to the clinical symptoms of cow's milk protein allergy; some of the pathomechanisms are known in detail, but others need further elucidation. A comprehensive understanding of the development of food allergies and the features of oral tolerance could have the potential to unlock more precise diagnostic tools and novel therapeutic approaches for patients with cow's milk protein allergy.

Real world use of peanut component testing among children in the Chicago metropolitan area

Background: Peanut component tests (PCT) have become important in the evaluation of peanut allergy. There remains a paucity of research across the United States in investigating the utility of PCT in clinical practice in conjunction with current standards of care. Objective: The primary aims were to evaluate the performance and sensitization patterns of PCT in clinical practice when first available at our institution. Methods: We performed a retrospective chart review of 184 children with PCT and oral food challenge (OFC) results between 2012 and 2017. Simple logistic regression models assessed the associations between PCT and OFC outcomes. Receiver operator characteristic curves were constructed, and a predicted probability curve was derived for Ara h2. Results: The median (interquartile range [IQR]) age at OFC was 4 years (2-7 years), and 111 patients (60%) were boys. Ara h 2 was the most commonly sensitized PCT. Sixty-one patients (33%) reacted at OFC. Ara h 2 specific immunoglobulin E (sIgE) ≥ 0.35 kU_A/L was associated with increased odds of reacting at OFC (odds ratio 5.91 95% confidence interval, 2.93-11.89; p < 0.001); however, 19 patients (37%) positive for Ara h 2 did not react. Ara h 2 sIgE of 0.49 kU_A/L and 4.58 kU_A/L were associated with 50% and 90% probability, respectively, of reacting at OFC. Among those sensitized only to Ara h 8 or 9 (n = 21), 86% had no reaction. There was no statistically significant association with polysensitization to Ara h 1, 2, and 3, and peanut OFC outcome. Conclusion: Although the Ara h 2 sIgE value was associated with clinical reactivity, a significant proportion of the patients sensitized to Ara h 2 tolerated peanut. OFC remains an important tool in the evaluation of peanut allergy.

Recent update on the management of anaphylaxis

Anaphylaxis is a life-threatening systemic allergic reaction presenting various clinical manifestations. Its prevalence has increased in almost all age groups and both sexes. Food, venom, and drugs are major causes in both children and adults; a higher prevalence of food-induced anaphylaxis is noted in children, while a higher prevalence of drug-induced anaphylaxis is noted in adults. The pathogenic mechanism is mediated by immunologic and nonimmunologic mechanisms, where mast cells and basophils are key cells that release mediators. A diagnosis of anaphylaxis is mainly based on clinical symptoms and physical findings; however, an increased serum tryptase level is a useful biomarker. Epinephrine is the first-line drug to treat acute symptoms, and an epinephrine auto-injector should be prescribed for each patient. Antihistamines and systemic corticosteroids are used to relieve symptoms. This review updates current issues in the management of anaphylaxis as well as the new guidelines for proper diagnosis and treatment.

Combining Anti-IgE Monoclonal Antibodies and Oral Immunotherapy for the Treatment of Food Allergy

Immunoglobulin E (IgE)-mediated food allergy is a real public health problem worldwide. The prevalence of food allergy is particularly high in children. Patients with food allergy experience high morbidity with a change in quality of life due to the risk of severe anaphylaxis. Current treatment options are poor. Allergen avoidance is widely recommended but exposes patients to accidental ingestion. Oral immunotherapy is also used in patients with food allergies to the most common allergens. Oral immunotherapy consists of a daily administration of small, gradually increasing amounts of allergens to induce desensitisation. This procedure aims at inducing immune tolerance to the ingested food allergens. However, some patients experience adverse reactions and discontinue oral immunotherapy.Given that IgE plays a crucial role in food allergy and anti-IgE are effective in allergic asthma, the use of anti-IgE therapeutic monoclonal antibodies (mAbs) such as omalizumab has been assessed in food allergy patients. The use of omalizumab as a monotherapy in food allergy has not been extensively studied but looks promising. There is more published evidence regarding the effect of omalizumab and oral immunotherapy in food allergy. Given the promising results of oral immunotherapy regarding sustained tolerance in clinical trials and the potential capacity of omalizumab to reduce symptoms in case of accidental exposure, a strategy combining oral immunotherapy with omalizumab pre-treatment has been suggested as a safer option in patients with severe food allergy compared to isolated therapy. Omalizumab seems useful in ensuring safer administration of oral immunotherapy with the oral immunotherapy maintenance dose being reached more rapidly. Quality-of-life improvement is greater with oral immunotherapy + omalizumab compared to oral immunotherapy alone. Moreover, sustained unresponsiveness is achieved more frequently with omalizumab. Considering that precision medicine and personalised therapy are major goals for allergic diseases, predictive biomarkers are crucial in order to identify food allergy patients more likely to benefit from anti-IgE therapies.

Pollen-related food allergy in children with seasonal allergic rhinitis

INTRODUCTION

Seasonal allergic rhinitis (SAR) and bronchial asthma are typical manifestations of pollen-food sensitization in adults. There is limited information regarding the sensitization patterns of pollen-food allergy in children.

AIM

To evaluate the prevalence of SAR in children with pollen-food sensitization and assess the impact of food allergens on nasal symptoms.

MATERIAL AND METHODS

Forty-three children with pollen-food sensitization aged 2-14 years were evaluated for evidence of SAR. The inclusion criteria was IgE-mediated sensitization to pollen and homologous food allergens. The control group consisted of 19 children with SAR caused by pollen without sensitization to homologous food allergens.

RESULTS

Allergic rhinitis was the main symptom in 65.1% of children; in 25.6% an association between ingestion of pollen-related foods and nasal symptoms was observed. The simultaneous sensitization to animal origin food allergens was stated in 63.3% of children with SAR. In 25.6% anaphylactic reactions to foods were registered. 37.2% of children were asymptomatic to pollen origin foods despite pollen-food sensitization. The statistically significant differences between values were noticed in comparison to the control group.

CONCLUSIONS

Allergic rhinitis is a common manifestation of pollen-food sensitization in children and this type of immunological hyperreactivity should be taken into account regardless of age. The lack of association of symptoms with plant origin foods in the majority of cases and the asymptomatic course of food sensitization in more than one third of patients indicates the need for follow-up and being careful in routine recommending the avoidance diet.

Accuracy of component-resolved diagnostics in peanut allergy: Systematic literature review and meta-analysis

BACKGROUND

Peanut allergy diagnosis relies on clinical reactivity to peanut supported by detection of specific IgE (sIgE) antibodies. Extract-based sIgE tests have low specificity, so component-resolved diagnostics may complement whole-extract testing.

METHODS

We systematically collected peanut allergen component data in seven databases and studied the diagnostic accuracy of peanut storage proteins (Arah1, 2, 3) and cross-reactive peanut proteins (Arah8 PR-10 and Arah9 lipid transfer protein) through meta-analyses. The systematic literature review included studies employing peanut components and oral food challenge (OFC) as reference standard in patients suspected of peanut allergy. Data for component sIgE at pre-defined detection thresholds were extracted and combined in random-effects bivariate meta-analyses. Risk of bias was assessed as recommended by Cochrane, with two additional quality items of importance for this review.

RESULTS

Nineteen eligible studies presented data suitable for meta-analysis. In cross-sectional pediatric studies, the pooled sensitivity of Arah2-sIgE at 0.35 kU_A /L cutoff was 83.3% [95% CI 75.6, 88.9] and specificity in diagnosing objective peanut allergy was 83.6% [95% CI 77.4, 88.4]. Compared with 0.1 and 1.0 kU_A /L, this threshold provided the best diagnostic accuracy. At 0.35 kU_A /L, Arah1 and Arah3 had comparable specificity (86.0% and 88.0%, respectively) but significantly lower sensitivity compared with Arah2 (37.0% and 39.1%, respectively; P < .05).

CONCLUSION

sIgE to Arah2 can enhance the certainty of diagnosis and reduce the number of OFC necessary to rule out clinical peanut allergy in unclear cases.

Oral Food Challenges in Infants and Toddlers

Oral food challenges (OFCs) are an indispensable tool for accurately diagnosing clinically relevant food allergy. Despite perceived concerns, data suggest OFCs, including infant OFCs, are both safe and practical in the clinical setting. The benefits of OFCs can be far reaching and impactful for the patient and parents, with improved quality of life, clarifying unnecessary dietary restrictions, increased social interactions, and reducing fear and anxiety. Demand for OFCs in infants and toddlers will continue to increase in the coming years and board-certified allergists will need to meet these demands by providing appropriate care in a safe and welcoming environment.

Allergen components in diagnosing childhood hazelnut allergy: Systematic literature review and meta-analysis

BACKGROUND

Hazelnut-specific IgE antibodies (sIgEs) in serum support the diagnosis of hazelnut allergy, but extract-based tests have low diagnostic specificity, commonly leading to over-diagnosis. Measuring sensitization to individual allergen components may enhance the diagnosis of hazelnut allergy. We systematically examined data on diagnostic accuracy of sIgE to commercially available hazelnut components to compare their individual contributions in diagnosing hazelnut allergy.

METHODS

Seven databases were searched for diagnostic studies on patients suspected of having hazelnut allergy. Studies employing component-specific IgE testing on patients whose final diagnosis was determined by oral food challenges were included in the meta-analysis. Study quality was assessed as recommended by Cochrane.

RESULTS

Seven cross-sectional studies and one case-control study were identified, seven presenting data on children (N = 635), and one on a mixed age population. Overall, the diagnostic accuracies of sIgE to both Cor a 9 and Cor a 14 were significantly higher than for Cor a 1-sIgE (P < .05). In children, the specificity of Cor a 14-sIgE at 0.35 kU_A /L cutoff was 81.7% (95% CI 77.1, 85.6), and 67.3% (60.3, 73.6) for Cor a 9-sIgE. The specificities for Cor a 1-sIgE and hazelnut-sIgE were 22.5% (7.4, 51.2) and 10.8% (3.4, 29.8), respectively. The sensitivity of Cor a 1-sIgE (60.2% [46.9, 72.2]) was lower than for hazelnut extract-sIgE (95.7% [88.7, 98.5]), while their specificities did not differ significantly.

CONCLUSION

sIgE to Cor a 14 and Cor a 9 hazelnut storage proteins increases diagnostic specificity in assessing hazelnut allergy in children. The combined use of hazelnut extract and hazelnut storage proteins may improve diagnostic value.

Oral Food Challenge

Oral food challenge (OFC) is the gold standard for diagnosis of IgE-mediated and non-IgE mediated food allergy. It is usually conducted to make diagnosis, to monitor for resolution of a food allergy, or to identify the threshold of responsiveness. Clinical history and lab tests have poor diagnostic accuracy and they are not sufficient to make a strict diagnosis of food allergy. Higher concentrations of food-specific IgE or larger allergy prick skin test wheal sizes correlate with an increased likelihood of a reaction upon ingestion. Several cut-off values, to make a diagnosis of some food allergies (e.g., milk, egg, peanut, etc.) without performing an OFC, have been suggested, but their use is still debated. The oral food challenge should be carried out by experienced physicians in a proper environment equipped for emergency, in order to carefully assess symptoms and signs and correctly manage any possible allergic reaction. This review does not intend to analyse comprehensively all the issues related to the diagnosis of food allergies, but to summarize some practical information on the OFC procedure, as reported in a recent issue by The Expert Review of Food Allergy Committee of Italian Society of Pediatric Allergy and Immunology (SIAIP).

IgE-mediated food allergy

Food allergy is defined as an adverse immunologic response to a food protein. Food-related reactions are associated with a broad range of signs and symptoms that may involve any body system, including the skin, gastrointestinal and respiratory tracts, and cardiovascular system. Immunoglobulin E (IgE)-mediated food allergy is a leading cause of anaphylaxis and, therefore, referral to an allergist for timely and appropriate diagnosis and treatment is imperative. Diagnosis entails a careful history and diagnostic tests, such as skin prick tests, serum-specific IgE and, if indicated, an oral food challenge. Once the diagnosis of food allergy is confirmed, strict elimination of the offending food allergen from the diet is generally necessary; however, in the case of cow’s milk and egg allergy, many allergic children are able to eat these foods in their baked form. This article provides an overview of the epidemiology, pathophysiology, diagnosis, and management of IgE-mediated food allergy.

Anaphylaxis in the 21st century: phenotypes, endotypes, and biomarkers

Anaphylaxis is the most serious of all allergic reactions and can be fatal. The diagnosis is frequently delayed, and misdiagnosis often occurs with asthma or urticaria. Biomarkers such as tryptase are not routinely checked, and appropriate treatment with epinephrine is not administered in a majority of cases, increasing the risk of poor outcomes. The objective of this review is to provide a better understanding of the pathophysiology of anaphylaxis with a description of phenotypes, endotypes, and biomarkers available in both the clinical and research settings. Expanding knowledge with regard to the presentation, causes, and triggers for anaphylaxis among health care providers will improve its diagnosis and management, increase patient safety, and decrease morbidity and mortality.

Food allergy and anaphylaxis

Anaphylaxis is a severe and potentially life-threatening allergic reaction. There are numerous potential causes, with food allergy being the leading cause in children and the focus of this review. Most reactions involve an IgE-mediated mechanism, although non-IgE-mediated and nonimmunologic reactions can occur. Various cofactors to be discussed can place certain individuals at an increased risk of severe or fatal anaphylaxis. The clinical manifestations of anaphylaxis are broad and may involve multiple body systems. Diagnosis of food-related anaphylaxis is primarily based on signs and symptoms and supported, wherever possible, by identification and confirmation of a culprit food allergen. First-line treatment of anaphylaxis is intramuscular administration of epinephrine. Long-term management is generally focused on strict allergen avoidance and more recently on food desensitization using immunotherapy. This review provides an overview of anaphylaxis with a specific focus on food allergy.

Precision medicine in cow's milk allergy: proteomics perspectives from allergens to patients

Cow's milk allergy (CMA) is one of the most common food allergies, especially during childhood. CMA is an immunological mediated adverse reaction to one or more cow's milk proteins, which are normally harmless to a non-allergic individual, as the result of a failure of oral tolerance. To make a correct diagnosis of CMA and a proper treatment is critical in clinical practice. Application of proteomics along with new bio-informatics tools in the field of food allergy is one of the hot topics presented in recent years. In the present review, we focus on recent applications of proteomics to the field of cow's milk allergy, from allergens quantification to the diagnosis, treatment and prognosis. Furthermore, we also shed a light on potential future directions and developments, that are parts of personalized medicine but also of the One Health approach.

SIGNIFICANCE

The field of food allergies is becoming a milestone in public health. Food allergies, in fact, can cause life-threatening reactions and profoundly influence the quality of life. Precise, fast and reliable diagnosis of food allergies, and in particular milk allergies is essential to avoid severe allergic reactions and also to prevent dangerous and eventually unnecessary dietary restrictions; but this can be difficult also due to a complex interaction of genetic background, environment, and microbiota. In this sense, proteomics represents steps toward researching food and milk allergy integrated with the clinic to improve pathophysiology, diagnosis, therapy, and prognosis.

Immune monitoring for precision medicine in allergy and asthma

'Precision Medicine' embodies the analyses of extensive data collected from patients and their environments to identify and apply patient-specific prophylactic strategies and medical treatments to improve clinical outcomes and healthcare cost-effectiveness. Many new methods have been developed for evaluating the activity of the human immune system. Such 'immune monitoring' approaches are now being used in studies of allergy and asthma in the hope of identifying better correlates of disease status, predictors of therapeutic outcomes, and potential side-effects of treatment. Together with analyses of family histories, genetic and other biometric data, and measurements of exposures to environmental and other risk factors for developing or exacerbating disease, immune monitoring approaches promise to enable 'Precision Medicine' for allergic diseases and asthma.

Component-resolved diagnosis in anaphylaxis

PURPOSE OF REVIEW

Component-resolved diagnosis (CRD) is an advanced tool capable of aiding the clinician in fine tuning the diagnosis of the causal allergens of a reaction with the added value of providing information of severity risk, potential cross-reactivity, and subsequently, guiding management measures. This review will focus on the advantages of CRD of anaphylaxis in clinical practice.

RECENT FINDINGS

Research is continuously providing insight to which molecules are associated with genuine sensitization and/or potential severity risk for hymenoptera venom (Api m1, Ves v 1, Ves v 5, and Pol d 5), food allergy (seed storage proteins and nonspecific lipid transfer proteins), cofactor-enhanced food allergy (ω-5-gliadine, nonspecific lipid transfer proteins), red meat delayed anaphylaxis (α-gal), latex allergy (Hev b 1, Hev b 3, Hev b 5, and Hev b 6), and Anisakis allergy (Ani s 1, Ani s 4, Ani s 7, and Ani s 13); other molecules are primary associated with nonclinically relevant sensitizations, cross-reactivity, or mild reactions (carbohydrate determinants and profilins). New molecules, some minor allergens, are being identified as new potential biomarkers of severity.

SUMMARY

The usefulness of CRD in anaphylaxis is self-evident, since it improves the recognition of sensitization profiles associated with specific clinical outcomes and provides information to guide further management.

Toward precision medicine and health: Opportunities and challenges in allergic diseases

Precision medicine (also called personalized, stratified, or P4 medicine) can be defined as the tailoring of preventive measures and medical treatments to the characteristics of each patient to obtain the best clinical outcome for each person while ideally also enhancing the cost-effectiveness of such interventions for patients and society. Clearly, the best clinical outcome for allergic diseases is not to get them in the first place. To emphasize the importance of disease prevention, a critical component of precision medicine can be referred to as precision health, which is defined herein as the use of all available information pertaining to specific subjects (including family history, individual genetic and other biometric information, and exposures to risk factors for developing or exacerbating disease), as well as features of their environments, to sustain and enhance health and prevent the development of disease. In this article I will provide a personal perspective on how the precision health-precision medicine approach can be applied to the related goals of preventing the development of allergic disorders and providing the most effective diagnosis, disease monitoring, and care for those with these prevalent diseases. I will also mention some of the existing and potential challenges to achieving these ambitious goals.

Assessment of endogenous allergenicity of genetically modified plants exemplified by soybean - Where do we stand?

According to EU regulation, genetically modified (GM) plants considered to be allergenic have to be assessed concerning their endogenous allergens before placement on the EU market, in line with the international standards described in Codex Alimentarius. Under such premises, a quantitative relevant increase in allergens might occur in GM plants as an unintended effect compared with conventionally produced crops, which could pose a risk to consumers. Currently, data showing a connection between dose and allergic sensitisation are scarce since the pathophysiological mechanisms of sensitisation are insufficiently understood. In contrast, data on population dose-distribution relationships acquired by oral food challenge are available showing a connection between quantity of allergenic protein consumed and the population of allergic individuals experiencing reactions. Soybean is currently the only recognised allergenic GM food by law for which EFSA has received applications and was therefore taken as an example for defining an assessment strategy. Identification of potential allergens, methodology for quantification as well as risk assessment considerations, are discussed. A strategy is proposed for the identification, assessment and evaluation of potential hazards/risks concerning endogenous allergenicity in food derived from plants developed by biotechnology. This approach could be expanded to other allergenic foods in the future, whenever required.

Food allergy: immune mechanisms, diagnosis and immunotherapy

Food allergy is a pathological, potentially deadly, immune reaction triggered by normally innocuous food protein antigens. The prevalence of food allergies is rising and the standard of care is not optimal, consisting of food-allergen avoidance and treatment of allergen-induced systemic reactions with adrenaline. Thus, accurate diagnosis, prevention and treatment are pressing needs, research into which has been catalysed by technological advances that are enabling a mechanistic understanding of food allergy at the cellular and molecular levels. We discuss the diagnosis and treatment of IgE-mediated food allergy in the context of the immune mechanisms associated with healthy tolerance to common foods, the inflammatory response underlying most food allergies, and immunotherapy-induced desensitization. We highlight promising research advances, therapeutic innovations and the challenges that remain.

Pearls and Pitfalls in Diagnosing IgE-Mediated Food Allergy

The term "food allergy" is used by many patients and clinicians to describe a range of symptoms that occur after ingestion of specific foods. However, not all symptoms occurring after food exposure are due to an allergic, or immunologic, response. It is important to properly evaluate and diagnose immunoglobulin E (IgE)-mediated food allergy as this results in reproducible, immediate onset, allergic reactions that can progress toward life-threatening anaphylaxis. Proper diagnosis requires understanding of the common foods that cause these reactions in addition to key historical elements such as symptoms, timing and duration of reaction, and risk factors that may predispose to development of IgE-mediated food allergy. Diagnostic testing for food-specific IgE can greatly aid the diagnosis. However, false-positive test results are very common and can lead to overinterpretation, misdiagnosis, and unnecessary dietary elimination. This review discusses important aspects to consider during evaluation of a patient for suspected IgE-mediated food allergy.

Multiplex component-based allergen microarray in recent clinical studies

During the last decades component-resolved diagnostics either as singleplex or multiplex measurements has been introduced into the field of clinical allergology, providing important information that cannot be obtained from extract-based tests. Here we review recent studies that demonstrate clinical applications of the multiplex microarray technique in the diagnosis and risk assessment of allergic patients, and its usefulness in studies of allergic diseases. The usefulness of ImmunoCAP ISAC has been validated in a wide spectrum of allergic diseases like asthma, allergic rhinoconjunctivitis, atopic dermatitis, eosinophilic esophagitis, food allergy and anaphylaxis. ISAC provides a broad picture of a patient's sensitization profile from a single test, and provides information on specific and cross-reactive sensitizations that facilitate diagnosis, risk assessment, and disease management. Furthermore, it can reveal unexpected sensitizations which may explain anaphylaxis previously categorized as idiopathic and also display for the moment clinically non-relevant sensitizations. ISAC can facilitate a better selection of relevant allergens for immunotherapy compared with extract testing. Microarray technique can visualize the allergic march and molecular spreading in the preclinical stages of allergic diseases, and may indicate that the likelihood of developing symptomatic allergy is associated with specific profiles of sensitization to allergen components. ISAC is shown to be a useful tool in routine allergy diagnostics due to its ability to improve risk assessment, to better select relevant allergens for immunotherapy as well as detecting unknown sensitization. Multiplex component testing is especially suitable for patients with complex symptomatology.

Kiwifruit Allergy in Children: Characterization of Main Allergens and Patterns of Recognition

Kiwifruit allergy has been described mostly in the adult population, but immunoglobulin (Ig)E-mediated allergic reactions to kiwifruit appear to be occurring more frequently in children. To date, 13 allergens from kiwifruit have been identified. Our aim was to identify kiwifruit allergens in a kiwifruit allergic-pediatric population, describing clinical manifestations and patterns of recognition. Twenty-four children were included. Diagnosis of kiwifruit allergy was based on compatible clinical manifestations and demonstration of specific IgE by skin prick test (SPT) and/or serum-specific IgE determination. SDS-PAGE and immunoblotting were performed with kiwifruit extract, and proteins of interest were further analyzed by mass spectrometry/mass spectrometry. For component-resolved in vitro diagnosis, sera of kiwifruit-allergic patients were analyzed by an allergen microarray assay. Act d 1 and Act d 2 were bound by IgE from 15 of 24 children. Two children with systemic manifestations recognized a protein of 15 kDa, homologous to Act d 5. Act d 1 was the allergen with the highest frequency of recognition on microarray chip, followed by Act d 2 and Act d 8. Kiwifruit allergic children develop systemic reactions most frequently following ingestion compared to adults. Act d 1 and Act d 2 are major allergens in the pediatric age group.