Food allergy phenotypes: The key to personalized therapy

[Phenotypes and endotypes of food allergy]

Food allergy is a common event, especially in the pediatric population, affecting between 3-6% of children. There are various challenges in the care of patients with food allergy, but certainly the diversity of symptoms and the outcome of the disease are important aspects in the treatment of patients, in the development of care guidelines and in the knowledge of the Natural history of disease. The classification into phenotypes allows a better understanding of the evolution of food allergy. The endotype is a subtype of a phenotype defined by its pathophysiological characteristic. Genetic, epigenetic, and environmental characteristics interfere with the construction of the phenotype and its possible endotypes. Understanding the phenotypes and endotypes of food allergies brings with it two fundamental aspects: 1) the need to understand that the analysis of phenotypes and endotypes in food allergies will allow establishing prognoses and helping in intervention with specific therapies, and 2) the importance of understanding The characterization of local endotypes and phenotypes, and the dietary diversity of the different countries that make up Latin America brings with it a varied menu of foods that may pose a risk of allergy that needs to be studied.

[Physiopathology of food allergies]

Food allergy is an adverse reaction to certain foods that have demonstrated "immunological mechanisms"; therefore, this term covers both food allergies mediated or not by immunoglobulin E (IgE). The common pathophysiological mechanism among forms of allergy to foods mediated or not by IgE is found in the failure of clinical and immunological tolerance towards that food. The induction and maintenance of immunological tolerance depends on the active generation of regulatory T cells specific for food antigens. This process is influenced by genetic factors (FOXP3 genes) and epigenetic factors conditioned by the environment (diet, microbiota, and their products). Since the intestinal microbiome can normally promote oral tolerance, current evidence suggests that perturbations of the microbiome may correlate, or even predispose, with food allergy. Understanding the pathogenic mechanism underlying IgE-mediated food allergies allows the implementation of measures aimed at restoring clinical and immunological tolerance. Knowledge of the mechanisms of food allergy will improve the outlook for patients with more severe immediate food allergies and anaphylaxis, as well as those who have comorbidities (atopic dermatitis, eosinophilic esophagitis and EGEIDs).

Biomarkers associated with persistence and severity of IgE-mediated food allergies: a systematic review

OBJECTIVE

The prevalence of food allergies (FA) has increased worldwide over the last few decades. Milk, eggs, and peanuts are among the most common allergens and can cause anaphylaxis. Therefore, we aimed to identify biomarkers that could predict the persistence and/or severity of IgE-mediated allergies to milk, eggs, and peanuts via a systematic review.

METHODS

This systematic review proceeded according to a protocol registered in the International Prospective Register of Systematic Reviews. Two independent authors extracted studies of interest from PubMed, SciELO, EMBASE, Scopus, and Ebsco databases and assessed their quality using the Newcastle-Ottawa Scale.

RESULTS

We selected 14 articles describing 1,398 patients. Among eight identified biomarkers, total IgE, specific IgE (sIgE), and IgG4 were the most often cited biomarkers of persistent allergies to milk, eggs, and peanuts. Skin prick tests, endpoint tests, and sIgE cutoff levels may predict positive responses to challenges with these foods. The basophil activation test is a biomarker for the severity and/or threshold of allergic reactions to milk and peanuts.

CONCLUSION

Only a few publications identified possible prognostic indicators of the persistence or severity of FA and outcomes of oral food challenges, indicating that more accessible biomarkers are needed to determine the likelihood of having a severe food allergic reaction.

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.

Phenotypic Distinctions Between Omega-5-Gliadin Allergy and Peanut Allergy: Clinical Profile, Reaction Rates and Triggers, and Quality of Life

Background

Different phenotypes of food allergy may exist, exhibiting distinct clinical features, and driven by different pathogenic mechanisms. We compared omega-5-gliadin (O5G) allergy to peanut allergy, focusing on clinical features, reaction rates and triggers, and quality of life (QOL).

Methods

We surveyed adults with O5G allergy and peanut allergy regarding their diagnosis, co-morbidities, allergic reactions, and QOL measured by the FAQLQ-AF.

Results

We received responses from 43/80 (54%) individuals with O5G allergy and 43/130 (33%) with peanut allergy. Compared to peanut allergic individuals, those with O5G allergy were older at age of onset (37.2 vs 2.5 years, p < 0.001), had fewer additional atopic conditions (0.88 vs 2.93, p < 0.001) or food allergies (0.15 vs 1.86, p < 0.001), and more frequent reactions before diagnosis (1.085 vs 0.29 per month, p < 0.05) Reaction rates improved in both groups following diagnosis. Reactions to peanut were more often triggered by accidental exposure (84% vs 26%, p < 0.001) and being away from home (65% vs 28%, p < 0.001), while reactions to O5G were more often due to deliberate ingestion (30% vs 9%, p < 0.05) or unexpected exercise (35% vs 2%, p < 0.001). Overall QOL score was similar between groups (4.2 in O5G allergy, 4.7 in peanut allergy, p = 0.12), but worse among women and those with additional food allergies.

Conclusion

Phenotypic differences between O5G and peanut allergy support the development of different clinical approaches and the possibility of targeting distinct pathogenic mechanisms for prevention and treatment. Quality of life was impaired to a similar degree between groups.

Bronchial hyperresponsiveness and asthma during oral immunotherapy for egg or peanut allergy in children

Background

Bronchial hyperresponsiveness (BHR) and asthma are frequently present in children with food allergy. We assessed BHR in children receiving oral immunotherapy (OIT) for persistent egg or peanut allergy and examined whether OIT affects asthma control.

Methods

Methacholine challenge testing was performed in 89 children with persistent egg or peanut allergy diagnosed by double-blind, placebo-controlled food challenge and 80 control children without food allergy. Of the 89 food-allergic children, 50 started OIT for egg allergy and 39 for peanut allergy. Sensitization to aeroallergens was evaluated by skin prick testing. Forty of the 89 children with regular controller treatment for asthma underwent methacholine challenge testing and 34 measurement of exhaled nitric oxide (FeNO) at baseline and after 6-12 months of OIT.

Results

Methacholine challenge testing revealed significant BHR in 29/50 children (58%) with egg allergy, 15/39 children (38%) with peanut allergy, and 6/80 controls (7.5%). The mean cumulative dose of methacholine causing a 20% fall in FEV1 differed significantly between the egg and peanut-allergic versus the control children (1009 μg, 1104 μg, and 2068 μg, respectively, p < 0.001). Egg or peanut OIT did not affect lung function, the degree of BHR or FeNO levels in children with asthma and had no adverse effect on asthma control. Lung function or BHR did not associate with the OIT outcome.

Conclusion

BHR was significantly more frequent in children with persistent egg or peanut allergy than in children without food allergy. Oral immunotherapy did not increase BHR and was safe for children on regular asthma medication.

Living with Food Hypersensitivity as an Adolescent Impairs Health Related Quality of Life Irrespective of Disease Severity: Results from a Population-Based Birth Cohort

Food hypersensitivity (FHS) refers to food-related symptoms, with or without concurrent Immunoglobulin E (IgE) antibodies related to food(s). It remains unclear how different FHS phenotypes affect health-related quality of life (HRQoL). We examined self-reported HRQoL (with the generic instrument EQ-5D (dimensions and a Visual Analogue Scale (VAS), range 0–100) in association with phenotypes of FHS, and food-specific symptoms among adolescents (n = 2990) from a population-based birth cohort. Overall, 22% of the adolescents had FHS. Compared to adolescents without FHS, those with FHS reported more problems in the dimensions of pain/discomfort (p < 0.001), and anxiety/depression (p = 0.007). Females with FHS reported more problems than males in these dimensions (p < 0.001). Different FHS phenotypes (IgE-sensitization, allergic co-morbidity, and severity of symptoms) were not associated with differences in HRQoL. EQ-VAS scores were lowest for adolescents with symptoms for wheat vs. no wheat, median 80 vs. 89, p = 0.04) and milk vs. no milk (median 85 vs. 90, p = 0.03). Physician-diagnosed lactose intolerance median EQ-VAS was 80 vs. 90, p = 0.03 and also associated with more problems in the dimension of anxious/depression. In conclusion, FHS is associated with lower HRQoL in adolescence, irrespective of phenotypes, but differentially affects females vs. males, and those with vs. without symptoms for milk or wheat.

Novel diagnostic techniques and therapeutic strategies for IgE-mediated food allergy

Background: Immunoglobulin E (IgE) mediated food allergy is a potentially life-threatening condition and represents a heavy burden for patients and their families. Identification of the most suitable way for management of each patient has currently become the primary goal for physicians. Methods: This study reviewed the current literature related to IgE-mediated food allergy. Results: The use of innovative diagnostic tools, such as allergen-specific IgG4 determination, basophil activation test, and component-resolved diagnostics, is currently available to facilitate a proper diagnosis of food allergy. After several decades of "passive clinical management" of the disease, which was based only on avoidance of the allergenic food and the use of epinephrine in the event of anaphylaxis, there has been a switch to active treatment. The most recent evidence-practice guidelines strongly recommend the use of immunotherapy as an effective therapeutic option, particularly in cases of allergy to cow's milk, egg, or peanut. The use of omalizumab, in association with immunotherapy or alone, has been tested in several studies, and results on its effectiveness seemed to be encouraging. Other biologics, such as dupilumab, reslizumab, mepolizumab, and other anticytokines therapies, are being investigated. Another interesting future treatment strategy could be the use of DNA vaccines. Conclusion: In recent years, the management of IgE-mediated food allergy has greatly improved. Knowledge of pathogenetic mechanisms, understanding of the disease course, and the introduction of novel biomarkers led to more accurate diagnoses along with the active treatment of patients.

Precision medicine in atopic diseases

PURPOSE OF REVIEW

To analyze the status of precision medicine in atopic diseases.

RECENT FINDINGS

Atopic diseases are increasingly recognized as heterogeneous in nature and they can be quite different in severity, response to therapy, triggers, genetic back ground, ancestral risk and type of inflammation. This significant variability in the landscape of atopic diseases is not reflected in the common treatment guidelines that follow 'one fits all' approach for their management. Such an approach is largely based on minimal 'phenotype' elements, such as severity of disease and response to therapy and does not reflect the information accumulate in the last 20 years about particular pathogenic pathways (endotypes) leading to disease (phenotypes) based on biomolecular analysis of the single individuals. Accumulating data have defined asthma allergic rhinitis, food allergy based on their endotypes and clinically relevant phenotypes. In general, atopic diseases can be largely classified as high or low Th2 inflammatory status, which may explain the severity and response to therapy.

SUMMARY

Precision medicine is aiming to use known endotype phenotype to guide specific individualized treatment. The work aimed in deep characterization of diseases to guide the disease management is crucial in light of the availability of ever more precise treatment able to target specific pathways.

Gender aspects in food allergy

PURPOSE OF REVIEW

The difference of food allergy prevalence between male and female individuals is well documented and should have more impact for personalized diagnosis and management. Although in younger age male sex dominates, in adults more women are affected by food allergies. This sex disparity diminishes again around menopause, underlining the influence of sex hormones, but in addition, also metabolic gender-specific factors and differences in microbiome composition might contribute to the different expression of food allergy in the two genders. The sex-dependent and gender-dependent influence on development of food allergy, disease severity, as well as on social, dietary and neuropsychological factors in studies mainly published within past 18 months are discussed in this review.

RECENT FINDINGS

Sex and gender differences likely play a role in food allergy development, for instance via influence on immune cells and mediators, or on the composition of the microbiome, but only few controlled studies on this specific topic are available.

SUMMARY

Future prospective studies need to clearly take into account the sex and gender difference in order to provide personalized diagnosis, management and treatment of food allergy.

Personalized Nutrition in Food Allergy: Tips for Clinical Practice

Nowadays, food allergies are considered as a wide spectrum of disorders that need different approaches. The "one size fits all" approach is giving way to a "targeted approach," based on the identification of the patient's phenotype. Thus, the approach of nutritional management of food allergy has moved on from simply being "yes or no" to "how much?", "in which form?" and "for which patients?" Different factors should be considered in order to make a patient-tailored nutritional plan in clinical practice. Tailored nutritional plans may help to reduce the nutritional, social and economic burden of food allergy.

Sex and Gender Aspects for Patient Stratification in Allergy Prevention and Treatment

Allergies are rapidly worsening in recent decades, representing the most common immunological diseases. The mechanism of disorders such as asthma, rhinocongiuntivitis, urticaria, atopic dermatitis, food and drug allergies, and anaphylaxis still remain unclear and consequently treatments is mostly still symptomatic and aspecific while developments of new therapies are limited. A growing amount of data in the literature shows us how the prevalence of allergic diseases is different in both sexes and its changes over the course of life. Genes, hormones, environmental and immunological factors affect sex disparities associated with the development and control of allergic diseases, while they more rarely are considered and reported regarding their differences related to social, psychological, cultural, economic, and employment aspects. This review describes the available knowledge on the role of sex and gender in allergies in an attempt to improve the indispensable gender perspective whose potential is still underestimated while it represents a significant turning point in research and the clinic. It will offer insights to stimulate exploration of the many aspects still unknown in this relationship that could ameliorate the preventive, diagnostic, and therapeutic strategies in allergic diseases.

Defining challenge-proven coexistent nut and sesame seed allergy: A prospective multicenter European study

BACKGROUND

Peanut, tree nut, and sesame allergies are responsible for most life-threatening food-induced allergic reactions. Rates of coexistent allergy between these foods have been from mostly retrospective studies that include only a limited number of tree nuts or were not based on oral food challenges.

OBJECTIVE

The Pronuts study is a multicenter European study (London, Geneva, and Valencia) assessing the challenge-proven rate of coexistent peanut, tree nut, and/or sesame seed allergy.

METHODS

Children aged 0 to 16 years with at least 1 confirmed nut or sesame seed allergy underwent sequential diagnostic food challenges to all other nuts and sesame seed.

RESULTS

Overall, the rate of coexistent peanut, tree nut, and sesame seed allergy was 60.7% (n = 74/122; 95% CI, 51.4% to 69.4%). Peanut allergy was more common in London, cashew and pistachio nut allergies were more common in Geneva, and walnut and pecan allergies were more common in Valencia. Strong correlations were found between cashew-pistachio, walnut-pecan, and walnut-pecan-hazelnut-macadamia clusters. Age (>36 months) and center (Valencia > Geneva > London) were associated with an increased odds of multiple nut allergies. By pursuing the diagnostic protocol to demonstrate tolerance to other nuts, participants were able to introduce a median of 9 nuts.

CONCLUSION

We found a higher rate of coexistent nut and sesame seed allergies than previously reported. Performing sequential food challenges was labor intensive and could result in severe allergic reactions; however, it reduced dietary restrictions. Age was a significant predictor of multiple nut allergies, and thus the secondary spread of nut allergies occurred in older children.

Developments in the field of allergy in 2017 through the eyes of Clinical and Experimental Allergy

In this article, we described the development in the field of allergy as described by Clinical and Experimental Allergy in 2017. Experimental models of allergic disease, basic mechanisms, clinical mechanisms, allergens, asthma and rhinitis and clinical allergy are all covered.

How to cope with food allergy symptoms?

PURPOSE OF REVIEW

Food allergy symptoms may involve a wide variety of organs (skin, gastrointestinal tract, and eyes) and systems (respiratory, circulatory, and neurological). They are often associated. Their severity ranges from mild to potentially life-threatening reactions and the presentation from acute to chronic.

RECENT FINDINGS

Food allergies have been the focus of multiple studies, position papers, and guidelines in recent years. They have defined an approach in classifying symptoms as mild to anaphylactic, distinguishing objective from subjective symptoms, and describing their heterogeneity, specific phenotypes or syndromes (e.g., lipid transfer protein syndrome or pollen food syndrome). Cofactors can also influence food allergy reactions. Symptoms of non-IgE-gastrointestinal food allergies, illustrated by eosinophilic esophagitis and food-protein-induced enterocolitis syndrome, are also now better understood and defined. Improvement in the knowledge of food allergy symptoms is crucial for correct diagnosis and a personalized treatment approach.

SUMMARY

Through a better description and understanding of symptoms, the diversity of food allergies is now better known. The next step is to harmonize symptom assessment not only for clinicians but also for patients, researchers, and public health stakeholders, to describe food allergy phenotypes and their underlying mechanisms and endotypes, to develop targeted management.

Gender, prick test size and rAra h 2 sIgE level may predict the eliciting dose in patients with peanut allergy: Evidence from the Mirabel survey

BACKGROUND

Peanut allergy management is based on active avoidance and access to emergency treatment including self-injectable adrenaline. Knowing the dose at which a patient is likely to react is crucial for risk assessment and could significantly improve management by integrating a personalized approach.

OBJECTIVE

To develop a threshold dose distribution curve model from routinely collected data.

METHODS

The MIRABEL survey is an observational study of 785 patients with peanut allergy/sensitization conducted in France, Belgium and Luxemburg. The current analysis included the 238 participants for whom medical and oral food challenge data were available. Several statistical models (Kaplan-Meier, Cox model, Weibull and Lognormal with predictive factors, basic Weibull and Lognormal) were compared to select the best model and predictive factor combination associated with the threshold doses. Inferences were made with a Bayesian approach.

RESULTS

Patients were mainly children (mean age: 9 years [IQR: 6-11]; 87% < 16 years) and males (62%). Median Ara h2 s IgE was of 8kUA/L [IQR: 1-55] and median skin prick test size of 10 mm [IQR: 7-13]. OFC was positive in 204 patients (86%). The median threshold dose was of 67 mg of peanut protein [IQR: 16-244]. The dose at which 1% of the patients are likely to react with objective symptoms was 0.26 [0.03; 2.24] mg of peanut protein. Gender, size of the skin prick test (SPT) and Ara h 2 specific IgE level had a significant impact on the threshold dose distribution curve. The Cox model was the most effective to predict threshold doses with this combination of factors. Girls react to lower doses than boys with a beta coefficient associated to the risk and a 95% credible interval of 0.44 [0.04; 0.77]. The higher the size of the SPT and the Ara h 2 specific IgE level are, the higher the risk of reacting to a small amount of peanut, with beta coefficients associated to the risk and 95% credible intervals of 0.05 [0.02; 0.08] and 0.01 [0.01; 0.02], respectively.

CONCLUSION AND CLINICAL RELEVANCE

According to the model, routinely collected data could be used to estimate the threshold dose. The consequences could be the identification of high-risk patients who are susceptible to react to small amounts of peanut and a personalized management of peanut allergy integrating the risk of allergic reaction. Limitations of this study are that assessors of OFC outcome were aware of SPT and Arah2 results, and a further validation study is required to confirm the predictive value of these parameters.

Personalized Nutrition Approach in Food Allergy: Is It Prime Time Yet?

The prevalence of food allergy appears to be steadily increasing in infants and young children. One of the major challenges of modern clinical nutrition is the implementation of individualized nutritional recommendations. The management of food allergy (FA) has seen major changes in recent years. While strict allergen avoidance is still the key treatment principle, it is increasingly clear that the avoidance diet should be tailored according to the patient FA phenotype. Furthermore, new insights into the gut microbiome and immune system explain the rising interest in tolerance induction and immunomodulation by microbiota-targeted dietary intervention. This review article focuses on the nutritional management of IgE mediated food allergy, mainly focusing on different aspects of the avoidance diet. A personalized approach to managing the food allergic individual is becoming more feasible as we are learning more about diagnostic modalities and allergic phenotypes. However, some unmet needs should be addressed to fully attain this goal.

[Personalized medicine in allergology]

BACKGROUND

Personalized medicine offers new perspectives for diagnostic measurements and medical treatment, but also puts greater demands on the physician.

OBJECTIVES

Developments, potentials and potential pitfalls of personalized medicine in allergology.

METHODS

Overview, evaluation and discussion of the current state of science on the basis of selected examples.

RESULTS

Allergic diseases like allergic rhinitis, atopic eczema or anaphylaxis can be classified into various clinical phenotypes, which are based on different immunological endotypes. These can be captured and categorized by a wide variety of omics technologies. The identification of endotype specific biomarkers holds promising opportunities of more precise diagnostics, the implementation of novel targeted therapies or the development of optimized preventive strategies. However, individualized analysis and assessment of the significance of the measurements represent special challenges.

CONCLUSIONS

Findings of the complex omics technologies need to be evaluated by comprehensive prospective studies in order to validate their clinical relevance and suitability for personalized medicine in allergology.

How the Smartphone Is Changing Allergy Diagnostics

PURPOSE OF REVIEW

Evidence-based clinical diagnosis of allergic disorders is increasingly challenging. Clinical decision support systems implemented in mobile applications (apps) are being developed to assist clinicians in diagnostic decisions at the point of care. We reviewed apps for allergic diseases general diagnosis, diagnostic refinement and diagnostic personalisation. Apps designed for specific medical devices are not addressed.

RECENT FINDINGS

Apps with potential usefulness in the initial diagnosis and diagnostic refinement of respiratory, food, skin and drug allergies are described. Apps to support diagnostic personalisation are not yet available. There is an urgent need to increase the scientific evidence on the real usefulness of these apps, as well as to develop new scientifically grounded apps designed and validated to support all allergic diseases and diagnostic levels. Apps have the potential to change the diagnosis of allergic diseases becoming part of the routine diagnostics toolset, but its usefulness needs to be established.