The Effects of Early Nutritional Interventions on the Development of Atopic Disease in Infants and Children: The Role of Maternal Dietary Restriction, Breastfeeding, Hydrolyzed Formulas, and Timing of Introduction of Allergenic Complementary Foods

This clinical report updates and replaces a 2008 clinical report from the American Academy of Pediatrics, which addressed the roles of maternal and early infant diet on the prevention of atopic disease, including atopic dermatitis, asthma, and food allergy. As with the previous report, the available data still limit the ability to draw firm conclusions about various aspects of atopy prevention through early dietary interventions. Current evidence does not support a role for maternal dietary restrictions during pregnancy or lactation. Although there is evidence that exclusive breastfeeding for 3 to 4 months decreases the incidence of eczema in the first 2 years of life, there are no short- or long-term advantages for exclusive breastfeeding beyond 3 to 4 months for prevention of atopic disease. The evidence now suggests that any duration of breastfeeding ≥3 to 4 months is protective against wheezing in the first 2 years of life, and some evidence suggests that longer duration of any breastfeeding protects against asthma even after 5 years of age. No conclusions can be made about the role of breastfeeding in either preventing or delaying the onset of specific food allergies. There is a lack of evidence that partially or extensively hydrolyzed formula prevents atopic disease. There is no evidence that delaying the introduction of allergenic foods, including peanuts, eggs, and fish, beyond 4 to 6 months prevents atopic disease. There is now evidence that early introduction of peanuts may prevent peanut allergy.

The Consortium for Food Allergy Research (CoFAR): The first generation

The Consortium for Food Allergy Research (CoFAR) was established by the National Institute of Allergy and Infectious Diseases in 2005 as a collaborative research program bringing together centers focused on the study of food allergy. CoFAR was charged with developing studies to better understand the pathogenesis and natural history of food allergy, as well as potential approaches to the treatment of food allergy. In its first iteration an observational study of infants with milk and egg allergy was established, and studies of oral immunotherapy for egg allergy and sublingual immunotherapy for peanut allergy were initiated, as was a phase 1 study of a recombinant peanut protein vaccine. CoFAR was renewed in 2010 for an additional 5-year period during which the initial observational study was continued, a study of eosinophilic esophagitis was initiated, and new therapeutic trials were established to study epicutaneous immunotherapy for peanut allergy and to compare the safety and efficacy of egg oral immunotherapy to the ingestion of baked egg for the treatment of egg allergy. The results of these efforts will be reviewed in this rostrum, with a brief look to the future of CoFAR.

The Journal of Allergy and Clinical Immunology: In Practice 2018 Highlights

A large number of clinically impactful studies and reviews were published in this journal in 2018. This article provides highlights of the original research published in 2018 issues of The Journal of Allergy and Clinical Immunolgy: In Practice on the subjects of anaphylaxis, asthma, dermatitis, drug allergy, eosinophilic disorders, food allergy, immune deficiency, rhinitis, and urticaria/angioedema and mast cell disorders. Within each topic, practical aspects of diagnosis and management are emphasized. Treatments discussed include lifestyle modifications, allergen avoidance therapy, positive and negative effects of pharmacologic therapy, and various forms of immunologic and desensitization management. We hope this review will help readers consolidate and use this extensive and practical knowledge for the benefit of patients.

Phenotypic Characterization of Eosinophilic Esophagitis in a Large Multicenter Patient Population from the Consortium for Food Allergy Research

BACKGROUND

Eosinophilic esophagitis (EoE) is increasingly common, but data on phenotypic aspects are still incomplete.

OBJECTIVES

To describe the clinical, endoscopic, and histopathologic features of a large number of children and adults with EoE across the United States.

METHODS

This was a multisite single visit registry enrolling subjects aged 6 months to 65 years with EoE. Participants provided responses regarding their medical history, with verification of the diagnosis and history by the study teams.

RESULTS

A total of 705 subjects were analyzed (median [interquartile range] age at enrollment 11.2 [6.7-17.7] years, 68.2% male, 87.9% whites). Of these, 67 subjects had concurrent gastrointestinal eosinophilia, with gastric mucosa most common. An age- and race-dependent time gap was present between symptom onset and time of diagnosis (adults and whites with longer gap). Food allergy and atopic dermatitis were associated with a decrease in this gap. Symptoms varied with age (more dysphagia and food impaction in adults) and with race (more vomiting in non-whites). Esophageal rings and strictures at diagnosis were more common in adults, although esophageal eosinophilia was comparable among age groups. Concomitant allergic disease (91%), infectious/immunologic disorders (44%), neurodevelopmental disorders (30%), and failure to thrive (21%) were common. Depression/anxiety increased with age. EoE was reported in 3% of parents and 4.5% of siblings.

CONCLUSIONS

Gastrointestinal eosinophilia is present in approximately 10% of patients with EoE; the symptom-diagnosis time gap is influenced by age, race, food allergy, and atopic dermatitis; symptoms vary with race; concurrent infectious/immunologic disorders and mental health disorders are common; and the level of esophageal eosinophils is comparable in patients with and without fibrostenotic features.

Early-life gut microbiome and egg allergy

BACKGROUND

Gut microbiota may play a role in egg allergy. We sought to examine the association between early-life gut microbiota and egg allergy.

METHODS

We studied 141 children with egg allergy and controls from the multicenter Consortium of Food Allergy Research study. At enrollment (age 3 to 16 months), fecal samples were collected, and clinical evaluation, egg-specific IgE measurement, and egg skin prick test were performed. Gut microbiome was profiled by 16S rRNA sequencing. Analyses for the primary outcome of egg allergy at enrollment, and the secondary outcomes of egg sensitization at enrollment and resolution of egg allergy by age 8 years, were performed using Quantitative Insights into Microbial Ecology, Phylogenetic Investigation of Communities by Reconstruction of Unobserved States, and Statistical Analysis of Metagenomic Profiles.

RESULTS

Compared to controls, increased alpha diversity and distinct taxa (PERMANOVA P = 5.0 × 10-4 ) characterized the early-life gut microbiome of children with egg allergy. Genera from the Lachnospiraceae, Streptococcaceae, and Leuconostocaceae families were differentially abundant in children with egg allergy. Predicted metagenome functional analyses showed differential purine metabolism by the gut microbiota of egg-allergic subjects (Kruskal-Wallis Padj  = 0.021). Greater gut microbiome diversity and genera from Lachnospiraceae and Ruminococcaceae were associated with egg sensitization (PERMANOVA P = 5.0 × 10-4 ). Among those with egg allergy, there was no association between early-life gut microbiota and egg allergy resolution by age 8 years.

CONCLUSION

The distinct early-life gut microbiota in egg-allergic and egg-sensitized children identified by our study may point to targets for preventive or therapeutic intervention.

Single-cell profiling of peanut-responsive T cells in patients with peanut allergy reveals heterogeneous effector TH2 subsets

BACKGROUND

The contribution of phenotypic variation of peanut-specific T cells to clinical allergy or tolerance to peanut is not well understood.

OBJECTIVES

Our objective was to comprehensively phenotype peanut-specific T cells in the peripheral blood of subjects with and without peanut allergy (PA).

METHODS

We obtained samples from patients with PA, including a cohort undergoing baseline peanut challenges for an immunotherapy trial (Consortium of Food Allergy Research [CoFAR] 6). Subjects were confirmed as having PA, or if they passed a 1-g peanut challenge, they were termed high-threshold subjects. Healthy control (HC) subjects were also recruited. Peanut-responsive T cells were identified based on CD154 expression after 6 to 18 hours of stimulation with peanut extract. Cells were analyzed by using flow cytometry and single-cell RNA sequencing.

RESULTS

Patients with PA had tissue- and follicle-homing peanut-responsive CD4+ T cells with a heterogeneous pattern of TH2 differentiation, whereas control subjects had undetectable T-cell responses to peanut. The PA group had a delayed and IL-2-dependent upregulation of CD154 on cells expressing regulatory T (Treg) cell markers, which was absent in HC or high-threshold subjects. Depletion of Treg cells enhanced cytokine production in HC subjects and patients with PA in vitro, but cytokines associated with highly differentiated TH2 cells were more resistant to Treg cell suppression in patients with PA. Analysis of gene expression by means of single-cell RNA sequencing identified T cells with highly correlated expression of IL4, IL5, IL9, IL13, and the IL-25 receptor IL17RB.

CONCLUSIONS

These results demonstrate the presence of highly differentiated TH2 cells producing TH2-associated cytokines with functions beyond IgE class-switching in patients with PA. A multifunctional TH2 response was more evident than a Treg cell deficit among peanut-responsive T cells.

Egg-specific IgE and basophil activation but not egg-specific T-cell counts correlate with phenotypes of clinical egg allergy

BACKGROUND

Egg allergy is phenotypically heterogeneous. A subset of patients with egg allergy can tolerate egg in an extensively heated form. Inclusion of baked egg (BE) into the diet accelerates resolution of egg allergy. Conversely, BE reactivity is associated with persistent disease. The immune basis of this clinical heterogeneity is unknown.

OBJECTIVES

We sought to study egg-specific antibody, basophil, and T-cell responses in children with reactivity or tolerance to BE.

METHODS

All participants underwent double-blind, placebo-controlled challenges to BE, and those who tolerated BE were challenged with unheated egg white protein to confirm clinical egg reactivity. Laboratory studies included serum antibody measurements, basophil activation tests, and CD154-based detection of egg-responsive T cells by using flow cytometry.

RESULTS

Of the 129 children studied, BE-reactive participants had significantly greater levels of egg-, ovalbumin-, and ovomucoid-specific IgE; lower ratios of egg-specific IgG₄/IgE; and increased basophil activation in response to egg. Among all participants, CD154-based profiling revealed egg-responsive T cells producing IL-4 and IL-13 but little IL-10 or IFN-γ, as well as the presence of egg-responsive Foxp3⁺CD25⁺CD127^low regulatory T cells. Egg-responsive T cells expressed CCR4, CCR6, and CXCR5, indicating capacity for homing to the skin, mucosa, and B-cell follicles. However, neither the frequency nor phenotype of egg-responsive T cells was different in those with tolerance or reactivity to BE.

CONCLUSIONS

Egg-specific antibody and basophil responses, but not T-cell responses, are greater in those with reactivity versus tolerance to BE. Egg-specific antibody and T-cell responses were highly heterogeneous in this cohort. The clinical implications of this immune heterogeneity will need to be studied longitudinally.

The Journal of Allergy and Clinical Immunology: In Practice 2017 Year in Review

An impressive number of clinically impactful studies and reviews were published in The Journal of Allergy and Clinical Immunology: In Practice in 2017. As a service to our readers, the editors provide this Year in Review article to highlight and contextualize the advances published over the past year. We include information from articles on asthma, allergic rhinitis, rhinosinusitis, immunotherapy, atopic dermatitis, contact dermatitis, food allergy, anaphylaxis, drug hypersensitivity, urticarial/angioedema, eosinophilic disorders, and immunodeficiency. Within each topic, epidemiologic findings are presented, relevant aspects of prevention are described, and diagnostic and therapeutic advances are enumerated. Treatments discussed include behavioral therapy, allergen avoidance therapy, positive and negative effects of pharmacologic therapy, and various forms of immunologic and desensitization management. We hope this review will help readers consolidate and use this extensive and practical knowledge for the benefit of patients.

The Allergist's Role in Anaphylaxis and Food Allergy Management in the School and Childcare Setting

Anaphylaxis and food allergy management in childcare facilities and schools are growing challenges. An increasing number of children experience severe allergic reactions on school grounds as evidenced by reports of epinephrine use. Data also suggest that the prevalence of food allergy may be increasing, with a large percentage of school-aged children at risk for anaphylaxis. Moreover, anaphylaxis may occur for the first time in a previously undiagnosed child at school or childcare setting, suggesting that general preparedness is essential. Management includes strategies for minimizing the risk of reactions and allergen exposures as well as readiness to recognize and treat allergic reactions of any severity. The primary objective of this report is to offer health care providers an overview of relevant evidence, resources, and expert opinion to assist with developing interprofessional collaborative counsel on school food allergy management and anaphylaxis preparedness with families, schools, and childcare settings. We present the current evidence base, suggest resources, and highlight areas of current controversy that warrant further study.

Food allergy: A review and update on epidemiology, pathogenesis, diagnosis, prevention, and management

This review provides general information to serve as a primer for those embarking on understanding food allergy and also details advances and updates in epidemiology, pathogenesis, diagnosis, and treatment that have occurred over the 4 years since our last comprehensive review. Although firm prevalence data are lacking, there is a strong impression that food allergy has increased, and rates as high as approximately 10% have been documented. Genetic, epigenetic, and environmental risk factors are being elucidated increasingly, creating potential for improved prevention and treatment strategies targeted to those at risk. Insights on pathophysiology reveal a complex interplay of the epithelial barrier, mucosal and systemic immune response, route of exposure, and microbiome among other influences resulting in allergy or tolerance. The diagnosis of food allergy is largely reliant on medical history, tests for sensitization, and oral food challenges, but emerging use of component-resolved diagnostics is improving diagnostic accuracy. Additional novel diagnostics, such as basophil activation tests, determination of epitope binding, DNA methylation signatures, and bioinformatics approaches, will further change the landscape. A number of prevention strategies are under investigation, but early introduction of peanut has been advised as a public health measure based on existing data. Management remains largely based on allergen avoidance, but a panoply of promising treatment strategies are in phase 2 and 3 studies, providing immense hope that better treatment will be imminently and widely available, whereas numerous additional promising treatments are in the preclinical and clinical pipeline.

Time Trends in Food Allergy Diagnoses, Epinephrine Orders, and Epinephrine Administrations in New York City Schools

OBJECTIVES

To assess time trends in food allergy diagnoses, epinephrine autoinjector (EAI) prescriptions, and EAI administrations in the school setting.

STUDY DESIGN

In this retrospective study, deidentified student data from the New York City Department of Health and Mental Hygiene, which oversees >1 million students in 1800 schools, were provided to investigators. Data from school years 2007-2008 to 2012-2013 pertaining to diagnoses of food allergy, student-specific EAI orders, and EAI administrations among students in New York City were analyzed for trends over time, via the use of ORs and χ² calculation.

RESULTS

The prevalences of providing physician documentation of food allergy and EAI orders, and the incidence of EAI administrations, all increased approximately 3-fold over the years of the study. Of 337 EAI administrations, more than one-half used stock EAI, and three-quarters were for students without a student-specific order preceding the incident.

CONCLUSIONS

The rise in food allergy diagnoses, EAI prescriptions, and EAI administrations suggest either a true increase in allergic disease, increased reporting, and/or, in the case of EAI administrations, increased appropriate use. As the majority of EAI administrations used stock supply, availability of nonstudent-specific stock EAI appears vital to management of anaphylaxis in schools. Collaboration between physicians, families, and schools is needed to identify students at risk for severe allergic reactions and to ensure preparedness and availability of EAI in the event of anaphylaxis.

Critical Issues in Food Allergy: A National Academies Consensus Report

The National Academies of Sciences, Engineering, and Medicine convened an expert, ad hoc committee to examine critical issues related to food allergy. The authors of the resulting report, "Finding a Path to Safety in Food Allergy: Assessment of the Global Burden, Causes, Prevention, Management, and Public Policy," evaluated the scientific evidence on the prevalence, diagnosis, prevention, and management of food allergy and made recommendations to bring about a safe environment for those affected. The committee recommended approaches to monitor prevalence, explore risk factors, improve diagnosis, and provide evidence-based health care. Regarding diagnostics, emphasis was placed on utilizing allergy tests judiciously in the context of the medical history because positive test results are not, in isolation, diagnostic. Evidence-based prevention strategies were advised (for example, a strategy to prevent peanut allergy through early dietary introduction). The report encourages improved education of stakeholders for recognizing and managing as well as preventing allergic reactions, including an emphasis on using intramuscular epinephrine promptly to treat anaphylaxis. The report recommends improved food allergen labeling and evaluation of the need for epinephrine autoinjectors with a dosage appropriate for infants. The committee recommended policies and guidelines to prevent and treat food allergic reactions in a various settings and suggested research priorities to address key questions about diagnostics, mechanisms, risk determinants, and management. Identifying safe and effective therapies is the ultimate goal. This article summarizes the key findings from the report and emphasizes recommendations for actions that are applicable to pediatricians and to the American Academy of Pediatrics.