Oral immunotherapy for peanut allergy induces eosinophilic esophagitis: three pediatric case reports

Eosinophilic gastrointestinal disorders and allergen immunotherapy: Lights and shadows

Allergic diseases, such as IgE-mediated food allergy, asthma, and allergic rhinitis, are relevant health problems worldwide and show an increasing prevalence. Therapies for food allergies are food avoidance and the prompt administration of intramuscular epinephrine in anaphylaxis occurring after accidental exposure. However, allergen immunotherapy (AIT) is being investigated as a new potential tool for treating severe food allergies. Effective oral immunotherapy (OIT) and epicutaneous immunotherapy (EPIT) induce desensitization and restore immune tolerance to the causal allergen. While immediate side effects are well known, the long-term effects of food AIT are still underestimated. In this regard, eosinophilic gastrointestinal disorders (EGIDs), mainly eosinophilic esophagitis, have been reported as putative complications of OIT for food allergy and sublingual immunotherapy (SLIT) for allergic asthma and rhinitis. Fortunately, these complications are usually reversible and the patient recovers after AIT discontinuation. This review summarizes current knowledge on the possible causative link between eosinophilic gastrointestinal disorders and AIT, highlighting recent evidence and controversies.

Remote allergen exposure elicits eosinophil infiltration into allergen nonexposed mucosal organs and primes for allergic inflammation

The natural history of allergic diseases suggests bidirectional and progressive relationships between allergic disorders of the skin, lung, and gut indicative of mucosal organ crosstalk. However, impacts of local allergic inflammation on the cellular landscape of remote mucosal organs along the skin:lung:gut axis are not yet known. Eosinophils are tissue-dwelling innate immune leukocytes associated with allergic diseases. Emerging data suggest heterogeneous phenotypes of tissue-dwelling eosinophils contribute to multifaceted roles that favor homeostasis or disease. This study investigated the impact of acute local allergen exposure on the frequency and phenotype of tissue eosinophils within remote mucosal organs. Our findings demonstrate allergen challenge to skin, lung, or gut elicited not only local eosinophilic inflammation, but also increased the number and frequency of eosinophils within remote, allergen nonexposed lung, and intestine. Remote allergen-elicited lung eosinophils exhibited an inflammatory phenotype and their presence associated with enhanced susceptibility to airway inflammation induced upon subsequent inhalation of a different allergen. These data demonstrate, for the first time, a direct effect of acute allergic inflammation on the phenotype and frequency of tissue eosinophils within antigen nonexposed remote mucosal tissues associated with remote organ priming for allergic inflammation.

Current Controversies and Future Prospects for Peanut Allergy Prevention, Diagnosis and Therapies

Peanut allergy has increased substantially in the past few decades, both in developed and developing countries. Peanut allergy has become a major public health concern, affecting up to 1 in 50 children, with repercussions for school and airline policies. Recent research findings have shown that, contrary to the long-standing teaching of "delayed" introduction of allergens, early introduction of peanut protein is of benefit as an allergy prevention strategy, especially in high-risk cases. Ideal dose, frequency and duration of "proactive" peanut therapy for maximum protection remain to be determined in order for it to become acceptable and practical on a large scale. Logistics around widespread screening of high-risk patients remain complex. The correct diagnosis of peanut allergy is crucial and diagnostic tests have been fine-tuned in the past 2 decades in order to help differentiate true allergy from false-positive sensitization through cross-reactivity. Component-resolved diagnostics have become routinely available, and the use of basophil activation tests has increased, although standardization and availability remain issues. Future tests, including epitope testing and histamine-release assays, promise to be even more specific in ruling out false positives and reducing the need for incremental food challenges. Stringent peanut avoidance and prompt treatment of reactions remain the cornerstone of treatment. The concept of exposing the allergic body to small amounts of peanut protein in a cautious, orderly, escalating fashion in the form of desensitization has been widely applied in the past 10-15 years, mainly in the research domain, but of late spilling over into every-day practice. However, desensitization does not equate to a cure, and has significant safety concerns and practical ramifications; probably requiring lifelong-controlled peanut ingestion for ongoing protection. Further strategies to enhance the safety and efficacy of immunotherapy are under exploration, many with a non-specific immune-modifying effect. Despite recent advances in peanut allergy, we still need to go back to basics with accurate diagnosis, nutritional counselling, well-organized allergy action plans and accessible emergency kits.

Oral immunotherapy for multiple foods in a pediatric allergy clinic setting

BACKGROUND

The increasing incidence of pediatric food allergy results in significant health care burden and family stress. Oral immunotherapy (OIT) can induce tolerance to peanut, milk, and egg. OIT for other foods, particularly multiple foods simultaneously, has not been thoroughly studied.

OBJECTIVE

To summarize our experience with OIT for multiple foods in a pediatric allergy clinic setting.

METHODS

Medical records were reviewed for patients undergoing OIT for multiple foods. Methods and outcomes of OIT were summarized. Outcomes were analyzed for correlation with baseline food allergen skin prick tests (SPTs) and specific IgE (sIgE) test results.

RESULTS

Forty-five patients aged 1.5 to 18 years undertook OIT for up to 12 foods, including peanut, tree nuts, seeds, legumes, and egg. At the time of review, 35 patients were receiving daily maintenance dosing, 4 had completed OIT and were continuing to eat their foods 3 times weekly, and 6 had stopped OIT because of anxiety, inconvenience, or allergy symptoms. A total of 49% of patients had reactions during the up-dosing process, mostly oral itching (33%), perioral hives (40%), and abdominal pain (35%). There was no correlation of baseline skin prick test (SPT) and sIgE test results with reaction threshold for baseline food challenge, lowest dose causing reactions during up-dosing, or time to reach maintenance. Higher baseline sIgE level but not baseline SPT result was associated with an increased number of allergic reactions during OIT. Baseline SPT correlated with stopping OIT.

CONCLUSION

A similar approach to that used for peanut OIT can be taken for nonpeanut foods and for multiple foods simultaneously. High baseline allergy test results are not a contraindication to OIT.

Eosinophilic Esophagitis: Review and Update

Background: Eosinophilic esophagitis (EoE) was first described in the 1990s, showing an increasing incidence and prevalence since then, being the leading cause of food impaction and the major cause of dysphagia. Probably, in a few years, EoE may no longer be considered a rare disease. Methods: This article discusses new aspects of the pathogenesis, symptoms, diagnosis, and treatment of EoE according to the last published guidelines. Results: The epidemiological studies indicate a multifactorial origin for EoE, where environmental and genetic factors take part. EoE affects both children and adults and it is frequently associated with atopic disease and IgE-mediated food allergies. In patients undergoing oral immunotherapy for desensitization from IgE-mediated food allergy the risk of developing EoE is 2.72%. Barrier dysfunction and T-helper 2 inflammation is considered to be pathogenetically important factors. There are different patterns of clinical presentation varying with age and can be masked by adaptation habits. Besides, symptoms do not usually correlate with histologic disease activity. The diagnostic criteria for EoE has evolved but mainly requires symptoms of esophageal dysfunction with histologic evidence of a peak value of at least 15 eosinophils per high-power field. Endoscopies have to be repeated in order to diagnose, monitor, and treat EoE. Treatment of EoE can be started either by drugs (PPIs and topical corticosteroids) or elimination diets. The multistage step-up elimination diet management approach of EoE is promising. Endoscopic dilation is used for patients with severe dysphagia/food impaction with inadequate response to anti-inflammatory treatment. Conclusions: Research in recent years has contributed to a better understanding of EoE's pathogenesis, genetic background, natural history, allergy workup, standardization in assessment of disease activity, evaluation of minimally invasive diagnostic tools, and new therapeutic approaches. However, several unmet needs are to be solved urgently, as finding a non-invasive disease-monitoring methods and biomarkers for routine practice, the development or new therapies, novel food allergy testing to detect triggering foods, drug, and doses required for initial therapy and safety issues with long-term maintenance therapy, amongst others. Besides, multidisciplinary management units of EoE, involving gastroenterologists, pediatricians, allergists, pathologists, dietitians, and ENT specialists are needed.

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 Nuts and Bolts of Food Immunotherapy: The Future of Food Allergy

Food allergies are on the rise and have a major impact on the quality of life of the food allergic child and their family. Currently, the mainstream treatment for food allergies is strict avoidance and elimination of the allergenic food(s) from the patient's diet in order to prevent an allergic reaction. However, recent advances in research have presented new therapeutic options for food allergic patients that are potentially becoming promising alternatives to traditional treatment. Food immunotherapy is the most popular of these new emerging interventions and has been studied intensively over the last decade for various foods. In this review, we discuss this exciting new development that is aspiring to become part of the mainstream therapy for food allergy.

EAACI Guidelines on allergen immunotherapy: IgE-mediated food allergy

Food allergy can result in considerable morbidity, impairment of quality of life, and healthcare expenditure. There is therefore interest in novel strategies for its treatment, particularly food allergen immunotherapy (FA-AIT) through the oral (OIT), sublingual (SLIT), or epicutaneous (EPIT) routes. This Guideline, prepared by the European Academy of Allergy and Clinical Immunology (EAACI) Task Force on Allergen Immunotherapy for IgE-mediated Food Allergy, aims to provide evidence-based recommendations for active treatment of IgE-mediated food allergy with FA-AIT. Immunotherapy relies on the delivery of gradually increasing doses of specific allergen to increase the threshold of reaction while on therapy (also known as desensitization) and ultimately to achieve post-discontinuation effectiveness (also known as tolerance or sustained unresponsiveness). Oral FA-AIT has most frequently been assessed: here, the allergen is either immediately swallowed (OIT) or held under the tongue for a period of time (SLIT). Overall, trials have found substantial benefit for patients undergoing either OIT or SLIT with respect to efficacy during treatment, particularly for cow's milk, hen's egg, and peanut allergies. A benefit post-discontinuation is also suggested, but not confirmed. Adverse events during FA-AIT have been frequently reported, but few subjects discontinue FA-AIT as a result of these. Taking into account the current evidence, FA-AIT should only be performed in research centers or in clinical centers with an extensive experience in FA-AIT. Patients and their families should be provided with information about the use of FA-AIT for IgE-mediated food allergy to allow them to make an informed decision about the therapy.

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.

Food allergy in EAACI journals (2016)

Over the last years we have observed considerable progress in the area of food allergy, particularly in children. This review article focusses on important contributions which have lately been published in the three journals of the European Academy of Allergy and Clinical Immunology. A better understanding of allergens as well as the mechanisms of sensitization and tolerance induction may hopefully lead to a more targeted management of food allergy in the near future.

Update on Potential Therapies for IgE-Mediated Food Allergy

PURPOSE OF REVIEW

Food allergy is common, affecting up to 8% of children in the USA. Currently, therapy is limited to avoidance of the implicated allergen and availability of self-injectable epinephrine. However, several new approaches to food allergy are under investigation. This article reviews the published data on these new approaches.

RECENT FINDINGS

Oral immunotherapy, in which allergic subjects are exposed to increasing amounts of antigen, can be accomplished in the majority of allergic individuals. However, this approach is not a cure as most patients will react after cessation of regular intake. In addition, there is a high rate of side effects. Other approaches include epicutaneous immunotherapy, therapy with anti-IgE medications, and use of Chinese herbs. Several novel approaches on food allergy are under study. At the current time, these approaches show promise for preventing severe reactions to accidental exposures. However, there is little evidence that current approaches will represent a true cure for food allergy.

The Prevalence of Eosinophilic Esophagitis in Pediatric Patients with IgE-Mediated Food Allergy

BACKGROUND

Eosinophilic esophagitis (EoE) is an allergic inflammatory disease that is triggered by food allergens and characterized by progressive esophageal dysfunction. Recently, EoE has been identified in patients who underwent oral immunotherapy (OIT) for IgE-mediated food allergy, suggesting an association.

OBJECTIVE

We sought to ascertain whether significant associations exist between IgE-mediated food allergies and EoE.

METHODS

Using the analysis of electronic medical record data and manual chart review, we examined our subspecialty care network of 35,528 children and adolescents to identify and characterize patients with IgE-mediated and EoE food allergy. The most common food allergens were defined, and the prevalence of EoE in patients with IgE-mediated food allergy was determined. Logistic regression was used to measure the extent to which IgE-mediated food allergy to specific foods is associated with EoE.

RESULTS

The most common causes of EoE were milk, soy, egg, grains, and meats, an allergen pattern that is distinct from that of IgE-mediated food allergy. The prevalence of EoE in patients with IgE-mediated food allergy was higher than that reported in the general population (4.7% vs 0.04%). The distribution of IgE-mediated food allergens in patients with EoE was similar to that of the general population, and IgE-mediated allergy to egg (2.27; 1.91-2.64), milk (4.19; 3.52-4.97), or shellfish (1.55; 1.24-1.92) was significantly associated with an EoE diagnosis.

CONCLUSIONS

Our findings support a clinical association between these conditions that has implications for the management of children with food allergy, and particular relevance to patients undergoing OIT.