Tolerance to egg proteins in egg-sensitized infants without previous consumption

Systematic review and meta-analyses on the accuracy of diagnostic tests for IgE-mediated food allergy

The European Academy of Allergy and Clinical Immunology (EAACI) is updating the Guidelines on Food Allergy Diagnosis. We aimed to undertake a systematic review of the literature with meta-analyses to assess the accuracy of diagnostic tests for IgE-mediated food allergy. We searched three databases (Cochrane CENTRAL (Trials), MEDLINE (OVID) and Embase (OVID)) for diagnostic test accuracy studies published between 1 October 2012 and 30 June 2021 according to a previously published protocol (CRD42021259186). We independently screened abstracts, extracted data from full texts and assessed risk of bias with QUADRAS 2 tool in duplicate. Meta-analyses were undertaken for food-test combinations for which three or more studies were available. A total of 149 studies comprising 24,489 patients met the inclusion criteria and they were generally heterogeneous. 60.4% of studies were in children ≤12 years of age, 54.3% were undertaken in Europe, ≥95% were conducted in a specialized paediatric or allergy clinical setting and all included oral food challenge in at least a percentage of enrolled patients, in 21.5% double-blind placebo-controlled food challenges. Skin prick test (SPT) with fresh cow's milk and raw egg had high sensitivity (90% and 94%) for milk and cooked egg allergies. Specific IgE (sIgE) to individual components had high specificity: Ara h 2-sIgE had 92%, Cor a 14-sIgE 95%, Ana o 3-sIgE 94%, casein-sIgE 93%, ovomucoid-sIgE 92/91% for the diagnosis of peanut, hazelnut, cashew, cow's milk and raw/cooked egg allergies, respectively. The basophil activation test (BAT) was highly specific for the diagnosis of peanut (90%) and sesame (93%) allergies. In conclusion, SPT and specific IgE to extracts had high sensitivity whereas specific IgE to components and BAT had high specificity to support the diagnosis of individual food allergies.

Egg Allergy in Children and Weaning Diet

Eggs are a fundamental food in the human diet, and together with cow’s milk, they are the most common food allergen. This work highlights the main nutritional characteristics of eggs to show how their absence from a child’s diet can constitute a serious deficiency. We then analyze the risk factors that facilitate the onset of egg allergy. The third part of the paper reports possible interventions to lower the appearance of food allergy that have been occurred in trials. The last part of the paper is a synthesis of this research study that has been taken from several of the latest guidelines or from position papers.

Skin barrier defects in atopic dermatitis: From old idea to new opportunity

Atopic dermatitis (AD) is the most common chronic skin inflammatory disease, with a profound impact on patients’ quality of life. AD varies considerably in clinical course, age of onset and degree to which it is accompanied by allergic and non-allergic comorbidities. Skin barrier impairment in both lesional and nonlesional skin is now recognized as a critical and often early feature of AD. This may be explained by a number of abnormalities identified within both the stratum corneum and stratum granulosum layers of the epidermis. The goal of this review is to provide an overview of key barrier defects in AD, starting with a historical perspective. We will also highlight some of the commonly used methods to characterize and quantify skin barrier function. There is ample opportunity for further investigative work which we call out throughout this review. These include: quantifying the relative impact of individual epidermal abnormalities and putting this in a more holistic view with physiological measures of barrier function, as well as determining whether these barrier-specific endotypes predict clinical phenotypes (e.g. age of onset, natural history, comorbidities, response to therapies, etc). Mechanistic studies with new (and in development) AD therapies that specifically target immune pathways, Staphylococcus aureus abundance and/or skin barrier will help us understand the dynamic crosstalk between these compartments and their relative importance in AD.

Sensitization to peanut, egg or pets is associated with skin barrier dysfunction in children with atopic dermatitis

BACKGROUND

Children with atopic dermatitis (AD) are often sensitized to food and aeroallergens, but sensitization patterns have not been analysed with biologic measures of disease pathogenicity.

OBJECTIVE

We sought to define allergen sensitization grouping(s) using unbiased machine learning and determine their associations with skin filaggrin (FLG) and transepidermal water loss (TEWL) (assesses skin barrier integrity), S100A8 and S100A9 expression (assesses skin inflammation) and AD severity.

METHODS

We studied 400 children with AD in the Mechanisms of Progression from Atopic Dermatitis to Asthma in Children (MPAACH) cohort to identify groupings of food and aeroallergen sensitizations. MPAACH is a paediatric AD cohort, aged 1-2, recruited through hospital/community settings between 2016 and 2018. We analysed these groupings' associations with AD biomarkers: skin FLG, S100A8 and S100A9 expression, total IgE, TEWL and AD severity.

RESULTS

An unbiased machine learning approach revealed five allergen clusters. The most common cluster (N = 131), SPT_PEP, had sensitization to peanut, egg and/or pets. Three low prevalence clusters, which included children with allergen sensitization other than peanut, egg or pets, were combined into SPT_Other . SPT_NEG included children with no sensitization(s). SPT_PEP children had higher median non-lesional TEWL (16.9 g/m² /h) and IgE (90 kU/L) compared with SPT_OTHER (8.8 g/m² /h and 24 kU/L; p = .01 and p < .001) and SPT_NEG (9 g/m² /h and 26 kU/L; p = .003 and p < .001). SPT_PEP children had lower median lesional (0.70) and non-lesional (1.09) FLG expression compared with SPT_OTHER (lesional: 0.9; p = .047, non-lesional: 1.78; p = .01) and SPT_NEG (lesional: 1.47; p < .001, non-lesional: 2.21; p < .001). There were no differences among groupings in S100A8 or S100A9 expression.

CONCLUSIONS AND CLINICAL RELEVANCE

In this largely clinic-based cohort of young children with AD, allergic sensitization to peanut, egg, cat or dog was associated with more severe disease and skin barrier function but not markers of cutaneous inflammation. These data need replicating in a population-based cohort but may have important implications for understanding the interaction between AD and allergic sensitization.

Relationship between specific IgE to egg components and natural history of egg allergy in Danish children

BACKGROUND

The majority of egg-allergic children develop tolerance over time. However, it may take numerous of consecutive egg challenges to get there as no good indices to predict tolerance exist.

OBJECTIVE

To investigate whether serial measurements of specific IgE to egg white, ovomucoid, ovalbumin, conalbumin, lysozyme, and egg yolk could improve the specificity of the diagnostic workup and aid in the decision when to rechallenge egg-allergic children.

METHODS

The outcome of oral food challenges with hen's egg and corresponding specific IgE levels were evaluated in children referred to The Allergy Center within an 8-year period. The egg-allergic children were rechallenged and had specific IgE levels measured once a year.

RESULTS

During a median follow-up of 26 months, 287 challenges and corresponding 287 serum analyses were performed in 130 children. Of the 130 children, 99 were egg allergic and 82 of these were rechallenged. Based on the initial diagnostic challenges only, area under the curve (AUC) estimates of the ability of specific IgE titers to distinguish between egg sensitization and egg allergy were only modest (maximum 0.83) and provided no clinical meaningful decision points. Specific IgE levels at baseline did not differ between tolerant and persistent allergic children. However longitudinally, acquisition of tolerance was associated with a decrease in IgE to egg white and to ovomucoid. In all cases of an increase in IgE to ovomucoid, the rechallenge was positive.

CONCLUSION

The decision when to rechallenge egg-allergic children should encounter the course of specific IgE.

Prevalence of food allergy in infants and pre-schoolers in Brazil

BACKGROUND

Food allergy is an increasing problem in public health, especially in childhood. Its incidence has increased in the last decade. Despite this, estimates of the actual incidence and prevalence are uncertain. The aim of this study was to estimate the prevalence of food allergy in infants and pre-schoolers.

METHODS

The parents of 3897 children completed questionnaires on the occurrence of any reaction to food. Children with parentally reported reactions were selected for further examination including a clinical interview, physical examination, allergic tests, and if necessary, oral food challenge to conclude the diagnosis of FA.

RESULTS

The estimated prevalence of allergy in children aged 4-59 months was 0.61%, being, 1.9% in infants and 0.4% in pre-schoolers. Among the 604 patients physicians evaluated with parent-reported FA, 24 (4%) had a confirmed diagnosis of food allergy, and 580 (96%) were excluded in the remaining. Of these, approximately half (51/52.6%) of 97 infants and (128/48%) of 487 pre-schoolers already performed the diet exclusion suspected food for a period of time.

CONCLUSION

This study shows that high overall prevalence of parental belief of current food allergy however the same was not observed in the in physician-diagnosed food allergy. The prevalence of food allergy was lower than that observed in the literature. This study alerts health professionals to the risk entailed by overestimation of cases of food allergy and unnecessary dietary exclusion, which may result in impairment in growth and development of children, especially in their first years of life.

Predictive values of egg-specific IgE by two commonly used assay systems for the diagnosis of egg allergy in young children: a prospective multicenter study

Background

Specific IgE (sIgE) is often used to predict oral food challenge (OFC) outcomes in food allergy, but interpretation of the results may vary depending on the assay method employed and the patient population tested. The aim of this study was to use two commercial assay systems to determine egg‐sIgE values predictive of allergy within the most common populations treated at pediatric clinics.

Methods

In a multicenter prospective study, 433 children with suspected or confirmed egg allergy underwent oral challenge (OFC) using cooked egg (CE) and raw egg (RE) powders to diagnose either true allergy in 1‐year‐old (group A, n = 220) or tolerance in 2‐ to 6‐year‐old (group B, n = 213). Egg white (EW)‐ and ovomucoid (OM)‐sIgE values were measured using the ImmunoCAP^®sIgE (ImmunoCAP) and the IMMULITE^® 2000 3 gAllergy^™ (3gAllergy) systems. Children were recruited from six primary care clinics and 18 hospitals in Japan.

Results

Receiver‐operating characteristic (ROC) curve analysis yielded similar areas under the curve (AUC) for the two assays (0.7–0.8). The optimal cutoff values and the probability curves (PCs) of the sIgE by the two assays to predict CE and RE OFC outcomes were determined for both groups. Values for 3gAllergy were higher than for ImmunoCAP; however, correlation of sIgE and predicted probability calculated by PCs were strong between the two methods.

Conclusions

Cutoff values and PCs for egg‐sIgE established using both ImmunoCAP and 3gAllergy may be useful for predicting egg allergy in early childhood patient populations.

[Food allergies in paediatrics: Current concepts]

The concept of allergic reaction currently includes all those where an immunological reaction depends on a reaction mediated by IgE, as well as those that involve other immune mechanisms, such as T-cell regulators. There are many different clinical situations, like the classic immediate reactions (IgE mediated) such as urticaria, angioedema, immediate vomiting, abdominal pain, both upper respiratory (aphonia or rhinitis) and lower (wheezing or dyspnoea) symptom, and cardiovascular symptoms. The reactions that involve more than one organ, such as anaphylaxis, which could be an anaphylactic shock if there is cardiovascular involvement. The clinical signs and symptoms produced by non-IgE mediated reactions are usually more insidious in how they start, such as vomiting hours after the ingestion of food in enterocolitis, diarrhoea after days or weeks from starting food, dermatitis sometime after starting food. In these cases it is more difficult to associate these clinical symptoms directly with food. In this article, we attempt to clarify some concepts such as sensitisation/allergy, allergen/allergenic source, or the relationship of different clinical situations with food allergy, in order to help the paediatrician on the one hand, to prescribe strict diets in case of a suspicion based on the cause/effect relationship with the food, and on the other hand not to introduce unnecessary diets that very often have to last an excessively long time, and could lead to nutritional deficiencies in the children.

Update on food allergy

Food allergies are a global health issue with increasing prevalence. Allergic reactions can range from mild local symptoms to severe anaphylactic reactions. Significant progress has been made in diagnostic tools such as component-resolved diagnostics and its impact on risk stratification as well as in therapeutic approaches including biologicals. However, a cure for food allergy has not yet been achieved and patients and their families are forced to alter eating habits and social engagements, impacting their quality of life. New technologies and improved in vitro and in vivo models will advance our knowledge of the pathogenesis of food allergies and multicenter-multinational cohort studies will elucidate interactions between genetic background, lifestyle, and environmental factors. This review focuses on new insights and developments in the field of food allergy and summarizes recently published articles.

Is it possible to make a diagnosis of raw, heated, and baked egg allergy in children using cutoffs? A systematic review

The diagnosis of IgE-mediated egg allergy lies both on a compatible clinical history and on the results of skin prick tests (SPTs) and IgEs levels. Both tests have good sensitivity but low specificity. For this reason, oral food challenge (OFC) is the ultimate gold standard for the diagnosis. The aim of this study was to systematically review the literature in order to identify, analyze, and synthesize the predictive value of SPT and specific IgEs both to egg white and to main egg allergens and to review the cutoffs suggested in the literature. A total of 37 articles were included in this systematic review. Studies were grouped according to the degree of cooking of the egg used for OFC, age, and type of allergen used to perform the allergy workup. In children <2 years, raw egg allergy seems very likely when SPTs with egg white extract are ≥4 mm or specific IgEs are ≥1.7 kUA /l. In children ≥2 years, OFC could be avoided when SPTs with egg white extract are ≥10 mm or prick by prick with egg white is ≥14 mm or specific IgE is ≥7.3 kUA /l. Likewise, heated egg allergy can be diagnosed if SPTs with egg white extract are >5 and >11 mm in children <2 and ≥2 years, respectively. Further and better-designed studies are needed to determine the remaining diagnostic cutoff of specific IgE and SPT for heated and baked egg allergy.

Egg Food Challenges are Associated with More Gastrointestinal Reactions

Egg allergy is a common pediatric allergy, and is usually outgrown by elementary school age. There is, therefore, a need to perform an oral food challenge (OFC) to establish the presence of food allergy to egg. In this study, we conducted a retrospective review of 2304 OFCs at a pediatric center and analyzed the severity of reactions during egg OFCs and compared them with other foods. The gastrointestinal system (GI) has been reported as more affected in egg food challenge. This study confirmed that 11% of patients undergoing egg OFC had GI symptoms vs. 7% undergoing food challenges for other foods or compared to milk, peanut and tree nut, individually. However, the involvement of lower respiratory tract was less frequent with egg than observed in peanut and tree nut OFC and similar to observed rate in milk. In conclusion, our study confirmed that OFC to egg causes more GI symptoms and less respiratory symptoms compared to other foods, in particular peanuts and tree nuts. However, 27% of children who failed egg OFC had lower respiratory tract reactions and required the use of epinephrine, similarly to children undergoing milk challenge.

Diagnosis and treatment of pediatric food allergy: an update

The prevalence of pediatric food allergy and anaphylaxis has increased in the last decades, especially in westernized countries where this emerging phenomenon was marked as a "second wave" of the allergic epidemic. Over recent years great advances have been achieved in the field of in vitro allergy testing and component-resolved diagnosis has increasingly entered clinical practice. Testing for allergen components can contribute to a more precise diagnosis by discriminating primary from cross-reactive sensitizations and assessing the risk of severe allergic reactions.The basic concept of the management of food allergy in children is also changing. Avoidance of the offending food is still the mainstay for disease management, especially in primary health care settings, but it severely affects the patients' quality of life without reducing the risk of accidental allergic reactions. There is a growing body of evidence to show that specific oral tolerance induction can represent a promising treatment option for food allergic patients. In parallel, education of food allergic patients and their caregivers as well as physicians about anaphylaxis and its treatment is becoming recognized a fundamental need. International guidelines have recently integrated these new evidences and their broad application all over Europe represents the new challenge for food allergy specialists.

Egg and egg-derived foods: effects on human health and use as functional foods

Eggs are sources of protein, fats and micronutrients that play an important role in basic nutrition. However, eggs are traditionally associated with adverse factors in human health, mainly due to their cholesterol content. Nowadays, however, it is known that the response of cholesterol in human serum levels to dietary cholesterol consumption depends on several factors, such as ethnicity, genetic makeup, hormonal factors and the nutritional status of the consumer. Additionally, in recent decades, there has been an increasing demand for functional foods, which is expected to continue to increase in the future, owing to their capacity to decrease the risks of some diseases and socio-demographic factors such as the increase in life expectancy. This work offers a brief overview of the advantages and disadvantages of egg consumption and the potential market of functional eggs, and it explores the possibilities of the development of functional eggs by technological methods.