Early clinical predictors of remission of peanut allergy in children

A mutation in Themis contributes to anaphylaxis severity following oral peanut challenge in CC027 mice

BACKGROUND

The development of peanut allergy is due to a combination of genetic and environmental factors, although specific genes have proven difficult to identify. Previously, we reported that peanut-sensitized Collaborative Cross strain CC027/GeniUnc (CC027) mice develop anaphylaxis upon oral challenge to peanut, in contrast to C3H/HeJ (C3H) mice.

OBJECTIVE

This study aimed to determine the genetic basis of orally induced anaphylaxis to peanut in CC027 mice.

METHODS

A genetic mapping population between CC027 and C3H mice was designed to identify the genetic factors that drive oral anaphylaxis. A total of 356 CC027xC3H backcrossed mice were generated, sensitized to peanut, then challenged to peanut by oral gavage. Anaphylaxis and peanut-specific IgE were quantified for all mice. T-cell phenotyping was conducted on CC027 mice and 5 additional Collaborative Cross strains.

RESULTS

Anaphylaxis to peanut was absent in 77% of backcrossed mice, with 19% showing moderate anaphylaxis and 4% having severe anaphylaxis. There were 8 genetic loci associated with variation in response to peanut challenge-6 associated with anaphylaxis (temperature decrease) and 2 associated with peanut-specific IgE levels. There were 2 major loci that impacted multiple aspects of the severity of acute anaphylaxis, at which the CC027 allele was associated with worse outcome. At one of these loci, CC027 has a private genetic variant in the Themis gene. Consistent with described functions of Themis, we found that CC027 mice have more immature T cells with fewer CD8+, CD4+, and CD4+CD25+CD127- regulatory T cells.

CONCLUSIONS

Our results demonstrate a key role for Themis in the orally reactive CC027 mouse model of peanut allergy.

Longitudinal peanut and Ara h 2 specific-IgE, -IgG4, and -IgG4/-IgE ratios are associated with the natural resolution of peanut allergy in childhood

BACKGROUND

There are no studies of longitudinal immunoglobulin measurements in a population-based cohort alongside challenge-confirmed peanut allergy outcomes. Little is known about biomarkers for identifying naturally resolving peanut allergy during childhood.

OBJECTIVES

To measure longitudinal trends in whole peanut and component Ara h 2 sIgE and sIgG4 in the first 10 years of life, in a population cohort of children with challenge-confirmed peanut allergy, and to determine whether peanut-specific immunoglobulin levels or trends are associated with peanut allergy persistence or resolution by 10 years of age.

METHODS

One-year-old infants with challenge-confirmed peanut allergy (n = 156) from the HealthNuts study (n = 5276) were prospectively followed at ages 4, 6, and 10 years with questionnaires, skin prick tests, oral food challenges, and plasma total-IgE, sIgE and sIgG4 to peanut and Ara h 2.

RESULTS

Peanut allergy resolved in 33.9% (95% CI = 25.3%, 43.3%) of children by 10 years old with most resolving (97.4%, 95% CI = 86.5%, 99.9%) by 6 years old. Decreasing Ara h 2 sIgE (p = .01) and increasing peanut sIgG4 (p < .001), Ara h 2 sIgG4 (p = .01), peanut sIgG4/sIgE (p < .001) and Ara h 2 sIgG4/sIgE (p < .001) from 1 to 10 years of age were associated with peanut allergy resolution. Peanut sIgE measured at 1 year old had the greatest prognostic value (AUC = 0.75 [95% CI = 0.66, 0.82]); however, no single threshold produced both high sensitivity and specificity.

CONCLUSION

One third of infant peanut allergy resolved by 10 years of age. Decreasing sIgE and sIgG4 to peanut and Ara h 2 over time were associated with natural resolution of peanut allergy. However, biomarker levels at diagnosis were not strongly associated with the natural history of peanut allergy.

Biomarkers of peanut allergy in children over time

BACKGROUND

Various biomarkers are used to define peanut allergy (PA). We aimed to observe changes in PA resolution and persistence over time comparing biomarkers in PA and peanut sensitised but tolerant (PS) children in a population-based cohort.

METHODS

Participants were recruited from the EAT and EAT-On studies, conducted across England and Wales, and were exclusively breastfeed babies recruited at 3 months old and followed up until 7-12 years old. Clinical characteristics, skin prick test (SPT), sIgE to peanut and peanut components and mast cell activation tests (MAT) were assessed at 12 months, 36 months and 7-12 years. PA status was determined at the 7-12 year time point.

RESULTS

The prevalence of PA was 2.1% at 7-12 years. Between 3 and 7-12 year, two children developed PA and one outgrew PA. PA children had larger SPT, higher peanut-sIgE, Ara h 2-sIgE and MAT (all p < .001) compared to PS children from 12 months onwards. SPT, peanut-sIgE, Ara h 2-sIgE and MAT between children with persistent PA, new PA, outgrown PA and PS were statistically significant from 12 months onwards (p < .001). Those with persistent PA had SPT, peanut-sIgE and Ara h 2-sIgE that increased over time and MAT which was highest at 36 months. New PA children had increased SPT and peanut-sIgE from 36 months to 7-12 years, but MAT remained low. PS children had low biomarkers across time.

CONCLUSIONS

In this cohort, few children outgrow or develop new PA between 36 months and 7-12 years. Children with persistent PA have raised SPT, peanut-sIgE, Ara h 2-sIgE and MAT evident from infancy that consistently increase over time.

Natural course of IgE-mediated food allergy in children

The prevalence of food allergy and food-induced anaphylaxis in children is increasing worldwide. Cow's milk, hen's eggs, and wheat allergies in young children have a more favorable prognosis with a relatively early outgrow, while allergies to peanuts, tree nuts, and seafood are more likely to be persistent. Although our understanding of the mechanism underlying the resolution of food allergy is incomplete, the roles of dendritic cells, regulatory T cells, and regulatory B cells are important. Many past studies on the natural course of food allergy were retrospective analyses of specific study groups, but large-scale population-based prospective studies are now being published. This review summarizes recent studies of the natural course of cow's milk, hen's eggs, wheat, peanuts, tree nuts, soy, sesame, and seafood allergies. The potential factors affecting the natural course of food allergy include symptom severity on ingestion, age at diagnosis, allergic comorbidities, skin prick test reaction size or serum food-specific immunoglobulin (Ig) E levels, changes in sensitization degree, IgE epitope specificity, ratio of food-specific IgE to IgG4, food-specific IgA levels, component-resolved diagnostic profile, diet, gut microbiome, and interventions such as immunotherapy. Since food allergy places a significant burden on patients and their caregivers in daily life, clinicians should be able to provide relevant knowledge on the natural course of food allergy, appropriately evaluate its resolution, and offer therapeutic options whenever possible.

Oral immunotherapy as a curative treatment for food-allergic preschool children: Current evidence and potential underlying mechanisms

The worldwide rising prevalence of food allergy is a major public health concern. Standard care consists of allergen avoidance and rescue medication upon accidental exposure. Oral immunotherapy (OIT) is increasingly being studied as a treatment option. Although desensitization (an increased reaction threshold) is often achieved during OIT, sustained unresponsiveness (SU; clinical nonreactivity after finishing OIT) is not achieved in most patients. A few studies have investigated the effectiveness of OIT in children younger than 4 years of age (early = e-OIT) and have shown a much more favorable outcome in terms of SU development. Together with food allergy prevention studies, which have demonstrated high efficacy of early oral allergen exposure, the outcomes of e-OIT studies indicate an early-life window of opportunity to achieve SU, allowing unrestricted dietary intake. However, the underlying mechanism of the high effectiveness of e-OIT is not understood yet. Both cohort and OIT studies indicate early-life immune plasticity. An immature food-allergic response in the first years of life seems to be a major driver of this immune plasticity, along with a higher tolerogenic immunological state. Allergy maturation can likely be disrupted effectively by early intervention, preventing the development of persistent food allergy. Upcoming studies will provide important additional data on the safety, feasibility, and effectiveness of e-OIT. Combined with immune mechanistic studies, this should inform the implementation of e-OIT.

A mutation in Themis contributes to peanut-induced oral anaphylaxis in CC027 mice

Background

The development of peanut allergy is due to a combination of genetic and environmental factors, although specific genes have proven difficult to identify. Previously, we reported that peanut-sensitized CC027/GeniUnc (CC027) mice develop anaphylaxis upon oral challenge to peanut, unlike C3H/HeJ (C3H) mice.

Objective

To determine the genetic basis of orally-induced anaphylaxis to peanut in CC027 mice.

Methods

A genetic mapping population between CC027 and C3H mice was designed to identify the genetic factors that drive oral anaphylaxis. A total of 356 CC027xC3H backcrossed mice were generated, sensitized to peanut, then challenged to peanut by oral gavage. Anaphylaxis and peanut-specific IgE were quantified for all mice. T-cell phenotyping was conducted on CC027 and five additional CC strains.

Results

Anaphylaxis to peanut was absent in 77% of backcrossed mice, with 19% showing moderate anaphylaxis, and 4% having severe anaphylaxis. A total of eight genetic loci were associated with variation in response to peanut challenge, six associated with anaphylaxis (temperature decrease) and two associated with peanut-specific IgE levels. There were two major loci that impacted multiple aspects of the severity of acute anaphylaxis, at which the CC027 allele was associated with worse outcome. At one of these loci, CC027 has a private genetic variant in the Themis (thymocyte-expressed molecule involved in selection) gene. Consistent with Themis' described functions, we found that CC027 have more immature T cells with fewer CD8+, CD4+, and CD4+CD25+CD127- regulatory T cells.

Conclusion

Our results demonstrate a key role for Themis in the orally-reactive CC027 mouse model of peanut allergy.

Allergen immunotherapy: progress and future outlook

INTRODUCTION

Allergy, the immunological hypersensitivity to innocuous environmental compounds, is a global health problem. The disease triggers, allergens, are mostly proteins contained in various natural sources such as plant pollen, animal dander, dust mites, foods, fungi and insect venoms. Allergies can manifest with a wide range of symptoms in various organs, and be anything from just tedious to life-threatening. A majority of all allergy patients are self-treated with symptom-relieving medicines, while allergen immunotherapy (AIT) is the only causative treatment option.

AREAS COVERED

This review will aim to give an overview of the state-of-the-art allergy management, including the use of new biologics and the application of biomarkers, and a special emphasis and discussion on current research trends in the field of AIT.

EXPERT OPINION

Conventional AIT has proven effective, but the years-long treatment compromises patient compliance. Moreover, AIT is typically not offered in food allergy. Hence, there is a need for new, effective and safe AIT methods. Novel routes of administration (e.g. oral and intralymphatic), hypoallergenic AIT products and more effective adjuvants holds great promise. Most recently, the development of allergen-specific monoclonal antibodies for passive immunotherapy may also allow treatment of patients currently not treated or treatable.

Food Allergen Immunotherapy in Preschool Children: Do We Have the Evidence?

Standard care for the management of food allergies previously centered on allergen avoidance and the treatment of adverse reactions after allergen exposure. An increase in the development of immunotherapy treatments for food allergy has occurred over the past 2 decades, with many centers now offering immunotherapy. Previous studies mainly focused on school-age children in whom food allergies are likely to be persistent. However, there is increasing evidence that delivering immunotherapy for food allergy to preschool-age children may deliver higher rates of success, and that peanut allergen immunotherapy leads the way. Conversely, the natural resolution of food allergies occurs primarily in these younger age groups, resulting in challenges to selecting patients who will ultimately benefit from these treatments. Both immunotherapy and natural history studies reveal the inherent plasticity of the immune system in early life, which may be more amenable to intervention, but this raises a delicate yet unknown balance between the optimal timing of intervention versus waiting for natural resolution of the food allergy. Here we review the evidence for early food allergen immunotherapy in preschoolers, and present the pros and cons of this approach while acknowledging important research gaps in this age group.

Oral immunotherapy for food allergy: Translation from studies to clinical practice?

Oral immunotherapy (OIT) is now recognized as an alternative active treatment to strict food avoidance in certain patients with IgE-mediated food allergy. Studies have confirmed the efficacy of OIT to desensitize children with allergy to cow's milk, eggs, and peanuts. The benefits, risks, and constraints of OIT are becoming increasingly well understood. However, there is no consensual criteria to select patients to whom OIT could be proposed, and many issues remain to address including the definitions of desensitization and long-term efficacy, the assessment of patient's experience in real life, the optimization of buildup and maintenance protocols, and the utility of multiple food OIT. The recent authorization by medical agency concerning the first medicine for peanut OIT is a step forward towards higher standardization in the practice of OIT. This article summarizes in comprehensive narrative format data on efficacy, tolerance, impact on quality of life and adverse effects of OIT and discuss elements to consider in clinical practice before starting OIT.

Prevalence of Food Allergy in France up to 5.5 Years of Age: Results from the ELFE Cohort

Background: In France, updated data on food allergies (FAs) are lacking, despite the need for efficient FA management and prevention. This study aimed to evaluate the prevalence of FAs in children in France, describe the most common allergens and determine the prevalence of atopic diseases in children with FAs. Methods: The ELFE study comprises a French nationwide birth cohort, including 18,329 children born in 2011. FAs were assessed by parental reports of food avoidance based on medical advice related to FAs, provided at 2 months and 2, 3.5 and 5.5 years of age. Data regarding FAs were available for 16,400 children. Data were weighted to account for selection and attrition bias. Results: From birth to 5.5 years of age, FAs were reported for 5.94% (95% CI: 5.54–6.34) children. Milk was the most common allergen, followed by egg, peanut, exotic fruits, tree nuts, gluten and fish. Among children with FAs, 20.5% had an allergy to at least two different groups of allergens; 71% reported eczema at least once before 5.5 years of age; 24.4% reported incidence of asthma; and 42.3% reported incidence of allergic rhinitis or conjunctivitis. Conclusion: In France, the prevalence of FAs in children up to 5.5 years of age is approximately 6%. It was demonstrated that 1 in 5 children with allergies had multiple FAs.

The natural history of peanut and egg allergy in children up to age 6 years in the HealthNuts population-based longitudinal study

BACKGROUND

Prospectively collected data on the natural history of food allergy are lacking.

OBJECTIVE

We examined the natural history of egg and peanut allergy in children from age 1 to 6 years and assessed whether a skin prick test (SPT) result or other clinical factors at diagnosis are associated with the persistence or resolution of food allergy in early childhood.

METHODS

The HealthNuts cohort consists of 5276 children who were recruited at age 1 year and have been followed prospectively. Children with food allergy at age 1 year (peanut [n = 156] or raw egg [n = 471] allergy ) and children who developed new sensitizations or food reactions after age 1 year were assessed for food sensitization and allergy (confirmed by oral food challenge when indicated) at the 6-year follow-up.

RESULTS

New-onset food allergy developed by age 6 years was more common for peanut (0.7% [95% CI = 0.5%-1.1%]) than egg (0.09% [95% CI = 0.03%-0.3%]). Egg allergy resolved more commonly (89% [95% CI = 85%-92%]) than peanut allergy (29% [95% CI = 22%-38%]) by age 6 years. The overall weighted prevalence of peanut allergy at age 6 years was 3.1% (95% CI = 2.6-3.7%) and that of egg allergy was 1.2% (95% = CI 0.9%-1.6%). The factors at age 1 year associated with persistence of peanut allergy were peanut SPT result of 8 mm or larger (odds ratio [OR] = 2.35 [95% CI 1.08-5.12]), sensitization to tree nuts (adjusted OR [aOR] = 2.51 [95% CI = 1.00-6.35]), and early-onset severe eczema (aOR = 3.23, [95% CI 1.17-8.88]). Factors at age 1 associated with persistence of egg allergy at age 6 were egg SPT result of 4 mm or larger (OR = 2.98 [95% CI 1.35-6.36]), other (peanut and/or sesame) food sensitizations (aOR = 2.80 [95% CI = 1.11-7.03]), baked egg allergy (aOR = 7.41 [95% CI = 2.16-25.3]), and early-onset severe eczema (aOR = 3.77 [95% CI = 1.35-10.52]).

CONCLUSION

Most egg allergy and nearly one-third of peanut allergy resolves naturally by age 6 years. The prevalence of peanut allergy at age 6 years was similar to that observed at age 1 year, largely owing to new-onset food peanut allergy after age 1 year. Infants with early-onset eczema, larger SPT wheals, or multiple food sensitizations and/or allergies were less likely to acquire tolerance to either peanut or egg.

Characteristics of patients with spontaneous resolution of sesame allergy

BACKGROUND

The prevalence of sesame allergy is increasing; strict avoidance is the mainstay of therapy. Lately, sesame oral immunotherapy was presented as an alternative treatment, with a high rate of success. Therefore, data on the natural history and the clinical characteristics of patients with persistent sesame allergy are important for the management of patients with sesame allergy.

OBJECTIVE

To describe the natural history of patients with sesame allergy and the clinical characteristics of patients with spontaneous resolution of sesame allergy compared with patients with persistent sesame allergy.

METHODS

In our retrospective study, electronic health records of patients with sesame allergy diagnosis were reviewed for demographic and clinical data. Statistical analysis of clinical characteristics of patients with spontaneous resolution compared with persistent sesame allergy was performed.

RESULTS

A total of 190 patients with sesame allergy were followed for 3.86 ±4.43 years. Of these patients, 61 (32.1%) had spontaneous resolution of sesame allergy. Patients with mild, early (before the age of 10 months) first sesame allergic reaction, with smaller than 7-mm skin prick test and without concomitant tree nut allergy had better resolution rate (56.1%).

CONCLUSION

Sesame allergy spontaneously resolved in approximately one-third of our patients and in more than half of the patients with mild first reaction (grade 1) at a young age (<10 months), with small skin prick test (<7 mm) and no concomitant tree nut allergy. Larger prospective studies with longer follow-up period are needed to better characterize the sesame allergic patients with persistent allergy who may need oral immunotherapy.

Oral Immunotherapy in Food Allergy: A Critical Pediatric Perspective

There is evidence that in children with persistent IgE-mediated food allergy (FA) to cow's milk, hen's egg, and peanut, oral allergen-specific immunotherapy (OIT) may increase the reaction threshold to the culprit food allergen(s). OIT may protect patients from the occurrence of severe reactions in case of accidental ingestion of the culprit food during treatment. Notwithstanding, many gaps are still unsolved, including safety issues, identification of predictive biomarkers, and post-desensitization efficacy. In this perspective, the use of omalizumab (Anti-IgE monoclonal antibody) has been proposed as an adjunctive treatment to OIT in order to reduce the risk of allergic reactions related to OIT. This review aims to summarize the current evidence and unmet needs on OIT in children with FA to enhance the development of longitudinal, prospective, and well-designed studies able to fill the current gaps soon.

White paper on peanut allergy - part 1: Epidemiology, burden of disease, health economic aspects

Peanuts are Leguminosae, commonly known as the legume or pea family, and peanut allergy is among the most common food allergies and the most common cause of fatal food reactions and anaphylaxis.

The prevalence of peanut allergy increased 3.5-fold over the past two decades reaching 1.4–2% in Europe and the United States. The reasons for this increase in prevalence are likely multifaceted. Sensitization via the skin appears to be associated with the development of peanut allergy and atopic eczema in infancy is associated with a high risk of developing peanut allergy.

Until recently, the only possible management strategy for peanut allergy was strict allergen avoidance and emergency treatment including adrenaline auto-injector in cases of accidental exposure and reaction.

This paper discusses the various factors that impact the risks of peanut allergy and the burden of self-management on peanut-allergic children and their caregivers.

Prevalence and characteristics of peanut allergy in US adults

BACKGROUND

Peanut allergy (PA) is the leading pediatric food allergy and a common cause of anaphylaxis. Little is known, however, on the prevalence and characteristics of PA in the adult population and whether phenotypic differences exist between adult-onset and childhood-onset PA.

OBJECTIVES

This study describes the current US population-level burden of adult PA.

METHODS

A cross-sectional food allergy survey was administered via phone and web in 2015 and 2016, resulting in nationally representative complex-survey weighted data for 40,443 adults. Reported food allergies were considered "convincing" if symptoms to specific allergens were consistent with an IgE-mediated reaction.

RESULTS

The prevalence of current self-reported PA was 2.9% among US adults, with 1.8% having convincing PA. Over 17% of adults with peanut allergy reported onset of their PA in adulthood. In adults with childhood-onset PA, 75.4% reported physician-diagnosed PA, compared with only 58.9% of adult-onset PA. Despite a similar frequency of food allergy-related emergency department visits within the past year (approximately 1 in 5 adults with PA allergy), adults with childhood-onset PA were significantly more likely to have a current epinephrine prescription compared with those with adult-onset PA (56% vs 44% respectively; P = .02) and were more likely to use an epinephrine autoinjector (48% vs 35%, P = .01).

CONCLUSIONS

Approximately 4.6 million US adults have PA-over 800,000 of whom appear to have developed their PA after age 18 years. Further examination of phenotypic differences between childhood-onset and adult-onset PA may improve understanding and management of adult PA.

APPEAL-1: A multiple-country European survey assessing the psychosocial impact of peanut allergy

Background

Peanut allergy (PA) is a common, potentially life‐threatening and typically lifelong condition with a significant burden of illness. However, information is lacking on how persons with PA (PwPA) and their caregivers perceive the psychosocial impact of living with PA. The Allergy to Peanuts imPacting Emotions And Life 1 (APPEAL‐1) survey, conducted across Europe, investigated the experience and impact of living with PA. Here, we report data evaluating the psychosocial impact of PA on PwPA and their caregivers.

Methods

Allergy to Peanuts imPacting Emotions And Life study 1 was an online survey conducted in eight European countries. Representatives of eight patient advocacy groups and five healthcare‐research specialists developed the survey. Eligible respondent groups included the following: adults diagnosed with PA (self‐report); parent/nonparent caregivers (proxy‐report for a child with PA); and parent/nonparent caregivers (self‐report of PA impact on themselves).

Results

Of 1846 total study respondents, 419 were adults with PA (self‐report); 546 were parents/caregivers (proxy‐report); and 881 were parents/caregivers (self‐report). Most respondents reported lifestyle restrictions regarding food (84%‐93%) and additional domains including parties and socializing, holiday activities and destinations, and taking public transport (53%‐89%). Approximately 40% rated themselves as “very” frustrated and “very” stressed. Two‐thirds (65%) felt socially isolated; 43% were bullied. Less than half felt confident in knowing when to use an adrenaline autoinjector. Several intercountry differences were observed such as high levels of uncertainty and stress in respondents from Ireland, highest rates of anxiety in respondents from Germany, and social exclusion and isolation most common in respondents from France.

Conclusions

Peanut allergy imposes an adverse psychosocial impact on patients and caregivers, leading to frustration, stress and isolation. Attention to the impact of PA is needed in research and clinical practice to improve PA healthcare and public education programmes.

Study protocol of a multicentre, randomised, controlled trial evaluating the effectiveness of probiotic and peanut oral immunotherapy (PPOIT) in inducing desensitisation or tolerance in children with peanut allergy compared with oral immunotherapy (OIT) alone and with placebo (the PPOIT-003 study)

INTRODUCTION

Peanut allergy is the the most common cause of life-threatening food-induced anaphylaxis. There is currently no effective long-term treatment. There is a pressing need for definitive treatments that improve the quality of life and prevent fatalities. Allergen oral immunotherapy (OIT) is a promising approach, which is effective at inducing desensitisation; however, OIT has a limited ability to induce sustained unresponsiveness (SU). We have previously shown that a novel treatment comprising a combination of the probiotic Lactobacillus rhamnosus CGMCC 1.3724 with peanut OIT (Probiotic Peanut Oral ImmunoTherapy (PPOIT)) is highly effective at inducing SU, with benefit persisting to 4 years after treatment cessation in the majority of initial treatment responders. Here we describe the protocol for a Phase IIb multicentre, double-blind, randomised, controlled trial (PPOIT-003) with dual primary objectives to evaluate the effectiveness of PPOIT at inducing SU (assessed at 8 weeks after treatment cessation) compared with placebo treatment and peanut OIT alone, in children with peanut allergy.

METHODS AND ANALYSIS

200 children 1 to 10 years of age with current peanut allergy confirmed by failed double-blind placebo-controlled food challenge (DBPCFC) at study screening will be recruited from three tertiary paediatric hospitals in Australia. There are three intervention arms-PPOIT, peanut OIT alone or placebo. Interventions are administered once daily for 18 months. The dual primary outcomes are: (1) the proportion of children who attain 8-week SU in the PPOIT group versus placebo group and (2) the proportion of children who attain 8-week SU in the PPOIT group versus OIT group.

ETHICS AND DISSEMINATION

This study has been approved by the Human Research Ethics Committees at the Royal Children's Hospital (HREC 35246) and the Child and Adolescent Health Service (RGS 2543). Results will be published in peer-reviewed journals and disseminated via presentations at international conferences.

TRIAL REGISTRATION NUMBER

ACTRN12616000322437.

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.

Epidemiology and Burden of Food Allergy

PURPOSE OF REVIEW

In recent decades, food allergy has become an increasing concern for families, clinicians, and policymakers. This review aims to summarize what is currently known about the epidemiology and population-level burden of IgE-mediated food allergy, including its effects on quality of life.

RECENT FINDINGS

Prevalence surveys, healthcare utilization data, and findings from longitudinal cohort studies across the globe indicate that food allergy imposes a growing societal burden. Worryingly, recent data indicate that food allergies may be more prevalent among adult populations than previously acknowledged, with many reported cases of adult-onset allergies. While it remains unclear how much of the current population-level burden of disease results from true, IgE-mediated allergy, as much epidemiological data does not incorporate clinical confirmation of disease prevalence-it is clear that affected individuals suffer impairments in their quality of life and incur substantial economic costs-beyond the physical health burden imposed by anaphylaxis.

Evaluation of the epidemiology of peanut allergy in the United Kingdom

Aims: To describe the epidemiology of peanut allergy (PA) in the UK over the last three decades.Methods: PA patients were identified from the Clinical Practice Research Datalink between 1987 and 2015. Incidence and prevalence of PA were compared between 2000 and 2015. Prevalence and relative risk (RR) of atopic comorbidities, anaphylaxis, adrenaline prescriptions versus matched controls were calculated.Results: Point prevalence of PA in the entire population and those <18 years increased from 31 to 202 and 116 to 635 per 100,000, respectively, between 2000 and 2015. Incidence increased from 8.6 to 18.2 per 100,000. Incidence in 2015 was 105 cases per 100,000 aged 0-4 years versus 13.4 per 100,000 aged 5+ years. Anaphylactic events affected 1.2% of the cases and 0.007% of the controls. The rate of adrenaline prescriptions was 5,910 per 100,000 person-years for PA patients. RRs for asthma, eczema and allergic rhinitis in PA patients versus controls were 4.5 (95% CI 4.2-4.8), 3.2 (3.1-3.4) and 2.6 (2.4-3.0), respectively.Conclusions: The prevalence and incidence of PA increased markedly over the study period. PA was associated with atopic conditions and anaphylaxis. PA patients had increased adrenaline prescriptions.

Sensitivity, specificity, and predictive value of oral mucosal brush biopsy for the diagnosis of peanut allergy

BACKGROUND

Current diagnostic testing methods for peanut allergy, including serum specific immunoglobulin E (sIgE) and skin-prick testing (SPT), have low specificity, whereas oral food challenge (OFC) carries significant risk of provoking adverse events. Mucosal brush biopsy (MBB) from the oral cavity is currently being studied as a new diagnostic test for peanut allergy, but normative data is not yet available with which to begin measuring specificity and predictive value.

METHODS

Twenty individuals with no history of adverse reactions from eating peanuts underwent oral MBB and serum testing for peanut sIgE. These data were then compared with previously published data from 10 individuals with a history of clinical peanut allergy, in order to generate receiver operating characteristic (ROC) curves and calculate the sensitivity, specificity, and positive and negative predictive values for both testing modalities.

RESULTS

The optimal cutoff levels for oral MBB and sIgE testing were 0.12 kU/L and 1.0 kU/L, respectively. At 0.12 kU/L, the sensitivity of oral MBB testing was 80% and the specificity was 85%, whereas at 1.0 kU/L, the sensitivity of sIgE testing was 50% and the specificity was 100%. From the ROC curves, the areas under the ROC curve (AUC) for oral MBB and sIgE were 0.91 (p < 0.001) and 0.74 (p = 0.007), respectively. Combination testing further increased both sensitivity and accuracy over oral MBB alone.

CONCLUSION

In this pilot study, oral MBB demonstrated high sensitivity and specificity for screening individuals with and without oral cavity clinical reactivity to peanuts and may represent a potentially useful testing method for the diagnosis of peanut allergy in the future.

Recent advances in understanding and preventing peanut and tree nut hypersensitivity

Peanut allergy, the most persistent and deadly of the food allergies, has become more prevalent worldwide in recent decades. Numerous explanations have been offered for the rise in peanut allergy, which has been more pronounced in Western, industrialized nations. In infants who are at increased risk of peanut allergy, new evidence indicates that early introduction of peanuts can help prevent allergy development. This counterintuitive finding directly contradicts the previously established practice of peanut avoidance for high-risk infants but is supported by clinical and basic science evidence. Here, we review the literature contributing to our evolving understanding of nut allergy, emphasizing the translation of this work to clinical practice.

Debates in Allergy Medicine: Does oral immunotherapy shorten the duration of milk and egg allergy? The pro argument

The development of oral tolerance or food allergy is an active process, related to dynamic interactions between host immune cells, microbiome, dietary factors, and food allergens. Oral tolerance is the default immune response in the gut. A food allergy occurs when this process fails and a pathologic Th2 response is activated. Oral food immunotherapy (OIT) aims to restore immune tolerance in food-allergic individuals. The stimulation of Tregs production seems to represent a crucial step in inducing long-term tolerance, but other mechanisms (e.g., the suppression of mast cell and basophil reactivity, changes in allergen-specific cells with regulatory markers) are involved. Several studies reported the efficacy of OIT in terms of "sustained unresponsiveness" (SU), an operational definition of immune tolerance. In successfully treated subjects, the ability to pass an oral food challenge 2 to 8 weeks after stopping the food allergen exposure seems to be conditioned by the treatment starting age, frequency, amount or type of food consumed, and by the duration of the maintenance phase. Based on the available data, the percentage of milk- and egg-allergic subjects achieving sustained unresponsiveness after an OIT ranges from 21% to 58,3%. A comprehensive understanding of mechanisms underlying the induction of oral tolerance with OIT, or natural tolerance to food allergens in healthy individuals, could potentially lead to advances in development of better treatment options for food allergic patients.

BSACI guideline for the diagnosis and management of peanut and tree nut allergy

Peanut nut and tree nut allergy are characterised by IgE mediated reactions to nut proteins. Nut allergy is a global disease. Limited epidemiological data suggest varying prevalence in different geographical areas. Primary nut allergy affects over 2% of children and 0.5% of adults in the UK. Infants with severe eczema and/or egg allergy have a higher risk of peanut allergy. Primary nut allergy presents most commonly in the first five years of life, often after the first known ingestion with typical rapid onset IgE-mediated symptoms. The clinical diagnosis of primary nut allergy can be made by the combination of a typical clinical presentation and evidence of nut specifc IgE shown by a positive skin prick test (SPT) or specific IgE (sIgE) test. Pollen food syndrome is a distinct disorder, usually mild, with oral/pharyngeal symptoms, in the context of hay fever or pollen sensitisation, which can be triggered by nuts. It can usually be distinguish clinically from primary nut allergy. The magnitude of a SPT or sIgE relates to the probability of clinical allergy, but does not relate to clinical severity. SPT of ≥ 8 mm or sIgE ≥ 15 KU/L to peanut is highly predictive of clinical allergy. Cut off values are not available for tree nuts. Test results must be interpreted in the context of the clinical history. Diagnostic food challenges are usually not necessary but may be used to confirm or refute a conflicting history and test result. As nut allergy is likely to be a long-lived disease, nut avoidance advice is the cornerstone of management. Patients should be provided with a comprehensive management plan including avoidance advice, patient specific emergency medication and an emergency treatment plan and training in administration of emergency medication. Regular re-training is required.

The longitudinal impact of probiotic and peanut oral immunotherapy on health-related quality of life

BACKGROUND

We previously reported that probiotic and peanut oral immunotherapy (PPOIT) was effective at inducing sustained unresponsiveness compared with placebo in a double-blind, placebo-controlled randomized trial. This study evaluated the impact of PPOIT on health-related quality of life (HRQL).

METHOD

Fifty-one participants (PPOIT 24; placebo 27) from the PPOIT trial completed Food Allergy Quality of Life Questionnaire (FAQLQ-PF) and Food Allergy Independent Measure (FAIM) at pre-treatment, end-of-treatment and 3 months after end-of-treatment. A total of 42 participants (20 PPOIT; 22 placebo) completed measures at 12 months post-treatment. Changes over time in PPOIT and placebo groups were examined by repeated-measures analysis of variance and paired t tests.

RESULTS

Probiotic and peanut oral immunotherapy was associated with significant improvement in FAQLQ-PF (F = 3.63, P = .02), with mean difference 0.8 at 3 months post-treatment (P = .05) and 1.3 at 12 months post-treatment (P = .005), exceeding the 0.5 minimal clinically important difference for FAQLQ-PF. For FAIM, mean difference was 0.5 (P = .03) at 3 months and 0.4 (P = .04) at 12 months post-treatment. In placebo group, post-treatment FAQLQ and FAIM remained unchanged from pretreatment. Improvement in FAQLQ-PF and FAIM scores related specifically to acquisition of sustained unresponsiveness rather than to receiving PPOIT treatment or participation in the trial.

CONCLUSIONS

Probiotic and peanut oral immunotherapy has a sustained beneficial effect on psychosocial impact of food allergy at 3 and 12 months after end-of-treatment. Treatment was not associated with reduced HRQL relative to baseline in either PPOIT or placebo groups, indicating that PPOIT was well tolerated and psychological well-being was not negatively impacted. Improved HRQL was specifically associated with acquisition of sustained unresponsiveness.

Efficacy and Safety of AR101 in Oral Immunotherapy for Peanut Allergy: Results of ARC001, a Randomized, Double-Blind, Placebo-Controlled Phase 2 Clinical Trial

BACKGROUND

Peanut oral immunotherapy, using a variety of approaches, has been previously shown to induce desensitization in peanut-allergic subjects, but no products have been approved for clinical use by regulatory agencies.

OBJECTIVE

We performed the first phase 2 multicentered study to assess the safety and efficacy of AR101, a novel oral biologic drug product.

METHODS

A randomized, double-blind, placebo-controlled trial was conducted at 8 US centers. Eligible subjects were 4 to 26 years old, sensitized to peanut, and had dose-limiting symptoms to ≤143 mg of peanut protein in a screening double-blind, placebo-controlled food challenge (DBPCFC). Subjects were randomized 1:1 to daily AR101 or placebo and gradually up-dosed from 0.5 to 300 mg/day. The primary endpoint was the proportion of subjects in each arm able to tolerate ≥443 mg (cumulative peanut protein) at exit DBPCFC with no or mild symptoms.

RESULTS

Fifty-five subjects (29 AR101, 26 placebo) were enrolled. In the intention-to-treat analysis, 23 of 29 (79%) and 18 of 29 (62%) AR101 subjects tolerated ≥443 mg and 1043 mg at exit DBPCFC, respectively, versus 5 of 26 (19%) and 0 of 26 (0%) placebo subjects (both P < .0001). Compared with placebo, AR101 significantly reduced symptom severity during exit DBPCFCs and modulated peanut-specific cellular and humoral immune responses. Gastrointestinal (GI) symptoms were the most common treatment-related adverse events (AEs) in both groups, with 6 AR101 subjects (21%) withdrawing, 4 of those due primarily to recurrent GI AEs.

CONCLUSIONS

In this study, AR101 demonstrated an acceptable safety profile and demonstrated clinical activity as a potential immunomodulatory treatment option in peanut-allergic children over the age of 4, adolescents, and young adults.

Precision medicine in allergic disease-food allergy, drug allergy, and anaphylaxis-PRACTALL document of the European Academy of Allergy and Clinical Immunology and the American Academy of Allergy, Asthma and Immunology

This consensus document summarizes the current knowledge on the potential for precision medicine in food allergy, drug allergy, and anaphylaxis under the auspices of the PRACTALL collaboration platform. PRACTALL is a joint effort of the European Academy of Allergy and Clinical Immunology and the American Academy of Allergy, Asthma and Immunology, which aims to synchronize the European and American approaches to allergy care. Precision medicine is an emerging approach for disease treatment based on disease endotypes, which are phenotypic subclasses associated with specific mechanisms underlying the disease. Although significant progress has been made in defining endotypes for asthma, definitions of endotypes for food and drug allergy or for anaphylaxis lag behind. Progress has been made in discovery of biomarkers to guide a precision medicine approach to treatment of food and drug allergy, but further validation and quantification of these biomarkers are needed to allow their translation into practice in the clinical management of allergic disease.

The prevalence of food allergy and other allergic diseases in early childhood in a population-based study: HealthNuts age 4-year follow-up

BACKGROUND

The HealthNuts study previously reported interim prevalence data showing the highest prevalence of challenge-confirmed food allergy in infants internationally. However, population-derived prevalence data on challenge-confirmed food allergy and other allergic diseases in preschool-aged children remain sparse.

OBJECTIVE

This study aimed to report the updated prevalence of food allergy at age 1 year from the whole cohort, and to report the prevalence of food allergy, asthma, eczema, and allergic rhinitis at age 4 years.

METHODS

HealthNuts is a population-based cohort study with baseline recruitment of 5276 one-year-old children who underwent skin prick test (SPT) to 4 food allergens and those with detectable SPT results had formal food challenges. At age 4 years, parents completed a questionnaire (81.3% completed) and those who previously attended the HealthNuts clinic at age 1 year or reported symptoms of a new food allergy were invited for an assessment that included SPT and oral food challenges. Data on asthma, eczema, and allergic rhinitis were captured by validated International Study of Asthma and Allergies in Childhood questionnaires.

RESULTS

The prevalence of challenge-confirmed food allergy at age 1 and 4 years was 11.0% and 3.8%, respectively. At age 4 years, peanut allergy prevalence was 1.9% (95% CI, 1.6% to 2.3%), egg allergy was 1.2% (95% CI, 0.9% to 1.6%), and sesame allergy was 0.4% (95% CI, 0.3% to 0.6%). Late-onset peanut allergy at age 4 years was rare (0.2%). The prevalence of current asthma was 10.8% (95% CI, 9.7% to 12.1%), current eczema was 16.0% (95% CI, 14.7% to 17.4%), and current allergic rhinitis was 8.3% (95% CI, 7.2% to 9.4%). Forty percent to 50% of this population-based cohort experienced symptoms of an allergic disease in the first 4 years of their life.

CONCLUSIONS

Although the prevalence of food allergy decreased between age 1 year and age 4 years in this population-based cohort, the prevalence of any allergic disease among 4-year-old children in Melbourne, Australia, is remarkably high.

The Prevalence and Natural History of Food Allergy

Numerous studies have demonstrated that the prevalence of food allergy is increasing. Not only are more children being diagnosed with food allergies, but studies suggest that when people outgrow their food allergies, it is taking longer than was previously thought. Studies in recent years have noted factors that may lead to a lower likelihood of developing a food allergy, including the early introduction of common food allergens, having a sufficient vitamin D level, or having a higher maternal intake of peanut early in pregnancy. Given a recent report that sensitization to common food allergens did not increase from the late 1980s/early 1990s to the mid-2000s, further studies will need to examine if the rise in food allergy prevalence is due to a change in the relationship between sensitization and clinical allergy or changes in the recognition and diagnosis of food allergy.

Nut allergy prevalence and differences between Asian-born children and Australian-born children of Asian descent: a state-wide survey of children at primary school entry in Victoria, Australia

BACKGROUND

Asian infants born in Australia are three times more likely to develop nut allergy than non-Asian infants, and rates of challenge-proven food allergy in infants have been found to be unexpectedly high in metropolitan Melbourne. To further investigate the risk factors for nut allergy, we assessed the whole-of-state prevalence distribution of parent-reported nut allergy in 5-year-old children entering school.

METHODS

Using the 2010 School Entrant Health Questionnaire administered to all 5-year-old children in Victoria, Australia, we assessed the prevalence of parent-reported nut allergy (tree nut and peanut) and whether this was altered by region of residence, socio-economic status, country of birth or history of migration. Prevalence was calculated as observed proportion with 95% confidence intervals (CI). Risk factors were evaluated using multivariable logistic regression and adjusted for appropriate confounders.

RESULTS

Parent-reported nut allergy prevalence was 3.1% (95% CI 2.9-3.2) amongst a cohort of nearly 60 000 children. It was more common amongst children of mothers with higher education and socio-economic index and less prevalent amongst children in regional Victoria than in Melbourne. While children born in Australia to Asian-born mothers (aOR 2.67, 95% CI 2.28-3.27) were more likely to have nut allergy than non-Asian children, children born in Asia who subsequently migrated to Australia were at decreased risk of nut allergy (aOR 0.1, 95% CI 0.03-0.31).

CONCLUSION

Migration from Asia after the early infant period appears protective for the development of nut allergy. Additionally, rural regions have lower rates of nut allergy than urban areas.

Specific oral tolerance induction in childhood

Food allergy continues to be a significant public health concern for which there are no approved treatments and management strategies primarily include allergen avoidance and pharmacological measures for accidental exposures. Food allergy is thought to result from either a failure to establish oral tolerance or the breakdown of existing oral tolerance, and therefore, experimental preventative and treatment strategies are now aimed at inducing specific oral tolerance. This may occur in infancy prior to the development of food allergy through the optimal timing of dietary exposure (primary oral tolerance induction) or as a treatment for established food allergy through oral immunotherapy (secondary oral tolerance induction). Trials examining the effectiveness of early dietary allergen exposure to prevent food allergy have yielded promising results for peanut allergy but not so for other allergens, although the results of several trials are yet to be published. Although infant feeding guidelines no longer advise to avoid allergenic foods and exposure to food allergens orally is an important step in inducing food tolerance by the immune system, evidence regarding the optimal timing, dose and form of these foods into the infant's diet is lacking. Likewise, oral immunotherapy trials appear promising for inducing desensitization; however, the long-term efficacy in achieving sustained desensitization and optimal protocols to achieve this is unknown. More research is needed in this emerging field.

A new framework for the interpretation of IgE sensitization tests

IgE sensitization tests, such as skin prick testing and serum-specific IgE, have been used to diagnose IgE-mediated clinical allergy for many years. Their prime drawback is that they detect sensitization which is only loosely related to clinical allergy. Many patients therefore require provocation tests to make a definitive diagnosis; these are often expensive and potentially associated with severe reactions. The likelihood of clinical allergy can be semi-quantified from an IgE sensitization test results. This relationship varies though according to the patients' age, ethnicity, nature of the putative allergic reaction and coexisting clinical diseases such as eczema. The likelihood of clinical allergy can be more precisely estimated from an IgE sensitization test result, by taking into account the patient's presenting features (pretest probability). The presence of each of these patient-specific factors may mean that a patient is more or less likely to have clinical allergy with a given test result (post-test probability). We present two approaches to include pretest probabilities in the interpretation of results. These approaches are currently limited by a lack of data to allow us to derive pretest probabilities for diverse setting, regions and allergens. Also, cofactors, such as exercise, may be necessary for exposure to an allergen to result in an allergic reaction in specific IgE-positive patients. The diagnosis of IgE-mediated allergy is now being aided by the introduction of allergen component testing which may identify clinically relevant sensitization. Other approaches are in development with basophil activation testing being closest to clinical application.

Early oral immunotherapy in peanut-allergic preschool children is safe and highly effective

BACKGROUND

Oral immunotherapy (OIT) is an effective experimental food allergy treatment that is limited by treatment withdrawal and the frequent reversibility of desensitization if interrupted. Newly diagnosed preschool children may have clinical and immunological characteristics more amenable to treatment.

OBJECTIVE

We sought to test the safety, effectiveness, and feasibility of early OIT (E-OIT) in the treatment of peanut allergy.

METHODS

We enrolled 40 children aged 9 to 36 months with suspected or known peanut allergy. Qualifying subjects reacted to peanut during an entry food challenge and were block-randomized 1:1 to receive E-OIT at goal maintenance doses of 300 or 3000 mg/d in a double-blinded fashion. The primary end point, sustained unresponsiveness at 4 weeks after stopping early intervention oral immunotherapy (4-SU), was assessed by double-blinded, placebo-controlled food challenge either upon achieving 4 prespecified criteria, or after 3 maintenance years. Peanut-specific immune responses were serially analyzed. Outcomes were compared with 154 matched standard-care controls.

RESULTS

Of 40 consented subjects, 3 (7.5%) did not qualify. Overall, 29 of 37 (78%) in the intent-to-treat analysis achieved 4-SU (300-mg arm, 17 of 20 [85%]; 3000 mg, 12 of 17 [71%], P = .43) over a median of 29 months. Per-protocol, the overall proportion achieving 4-SU was 29 of 32 (91%). Peanut-specific IgE levels significantly declined in E-OIT-treated children, who were 19 times more likely to successfully consume dietary peanut than matched standard-care controls, in whom peanut-specific IgE levels significantly increased (relative risk, 19.42; 95% CI, 8.7-43.7; P < .001). Allergic side effects during E-OIT were common but all were mild to moderate.

CONCLUSIONS

At both doses tested, E-OIT had an acceptable safety profile and was highly successful in rapidly suppressing allergic immune responses and achieving safe dietary reintroduction.

Epidemiology of food allergy and food-induced anaphylaxis: is there really a Western world epidemic?

PURPOSE OF REVIEW

Food-induced anaphylaxis continues to be an important cause of hospital admissions, particularly in children. This review outlines recent advances in understanding the epidemiology of IgE-mediated food allergy and potential mechanisms for its rise in prevalence.

RECENT FINDINGS

The rise in food allergy prevalence in Western countries has happened more quickly than changes to the genome can occur; thus, environmental changes are likely to be important. Recent studies, however, suggest that genetic risk determines responses to environmental risk factors. Environmental peanut exposure has been associated with increased peanut allergy risk in individuals with filaggrin null mutations, consistently with sensitization occurring through a damaged skin barrier. Reduced microbial and vitamin D exposure is also leading candidates for risk factors for food allergy in the context of genetic susceptibility. In addition, HLA-DR and HLA-DQ gene region variants appear to play a role in peanut allergy, although no studies have yet assessed their susceptibility to environmental cues. Finally, findings from observational cohorts and the first large-scale intervention trials for food allergy prevention support early oral allergen exposure to reduce the prevalence of specific food allergies, which is informing changes in public health guidelines at the population level. Further research will be required to assess the impact of these guideline changes on the population prevalence of food allergy.

SUMMARY

New studies are providing important insights into the prevalence, causes, and mechanisms of food allergy. Recent findings are informing changes to population health guidelines in developed countries, which have the potential to halt or reverse the increase in food allergy prevalence. By contrast, food allergy in the developing world remains understudied.