Current Insights into Immunotherapy Approaches for Food Allergy

The epidemiology of multifood allergy in the United States: A population-based study

BACKGROUND

Immunoglobulin E (IgE)-mediated food allergies (FAs) are increasingly common among US children and adults. Not only can living with FA impose considerable physical health impacts, but it also imposes economic burden and can negatively affect quality of life. Limited data indicate that allergy to multiple foods (multi-FA) also may be common, but much remains unknown about its distribution and determinants.

OBJECTIVE

To characterize the prevalence, characteristics, determinants, psychosocial burden, and distribution of multi-FA among a large, nationally representative sample of US children and adults.

METHODS

A US population-based survey was administered. Estimates of multi-FA prevalence, conditional frequencies of multi-FA combinations, and associated factors were derived. Latent class analyses were conducted using 9 dichotomized indicators of specific FA prevalence, which were used to determine factors associated with latent class membership and characterize FA-related psychosocial burden within each class.

RESULTS

Surveys were completed for 38,408 children and 40,443 adults. Among children and adults meeting established symptom-report criteria for FA, an estimated 40% and 48% had multi-FA, respectively. Among pediatric and adult populations with convincing FAs, the lifetime reported prevalence of physician-diagnosed atopic comorbidities increased significantly as the number of reported current convincing FAs increased, as did the proportion reporting multi-FA-related health care utilization and higher perceived psychosocial burden. Latent class analyses suggested the existence of the following 4 key latent phenotypes of multi-FA: milk and egg-dominant, seafood-dominant, peanut and tree nut-dominant, and broadly multi-food allergic.

CONCLUSION

The US population-level burden of multi-FA is high among both children and adults, and data indicate the presence of 4 major phenotypes of multi-FA in both populations.

Microbiome Therapeutics for Food Allergy

The prevalence of food allergies continues to rise, and with limited existing therapeutic options there is a growing need for new and innovative treatments. Food allergies are, in a large part, related to environmental influences on immune tolerance in early life, and represent a significant therapeutic challenge. An expanding body of evidence on molecular mechanisms in murine models and microbiome associations in humans have highlighted the critical role of gut dysbiosis in the pathogenesis of food allergies. As such, the gut microbiome is a rational target for novel strategies aimed at preventing and treating food allergies, and new methods of modifying the gastrointestinal microbiome to combat immune dysregulation represent promising avenues for translation to future clinical practice. In this review, we discuss the intersection between the gut microbiome and the development of food allergies, with particular focus on microbiome therapeutic strategies. These emerging microbiome approaches to food allergies are subject to continued investigation and include dietary interventions, pre- and probiotics, microbiota metabolism-based interventions, and targeted live biotherapeutics. This exciting frontier may reveal disease-modifying food allergy treatments, and deserves careful study through ongoing clinical trials.

Therapeutical Targets in Allergic Inflammation

From the discovery of IgE to the in-depth characterization of Th2 cells and ILC2, allergic inflammation has been extensively addressed to find potential therapeutical targets. To date, omalizumab, an anti-IgE monoclonal antibody, and dupilumab, an anti-IL-4 receptor α monoclonal antibody, represent two pillars of biologic therapy of allergic inflammation. Their increasing indications and long-term follow-up studies are shaping the many different faces of allergy. At the same time, their limitations are showing the intricate pathogenesis of allergic diseases.

Atopic Dermatitis Mediates the Association Between an IL4RA Variant and Food Allergy in School-Aged Children

BACKGROUND

Atopic dermatitis (AD) and food allergy (FA) may share genetic risk factors. It is unknown whether genetic factors directly cause FA or are mediated through AD, as the dual-allergen hypothesis suggests.

OBJECTIVE

To test the hypothesis that AD mediates the relationship between an IL-4 receptor alpha chain gene (IL4RA) variant, the human IL-4 receptor alpha chain protein-R576 polymorphism, and FA.

METHODS

A total of 433 children with asthma enrolled in the School Inner-City Asthma Study underwent genotyping for the IL4RA⁵⁷⁶ allele. Surveys were administered to determine FA, AD, and associated allergic responses. Mediation analysis was performed adjusting for race and ethnicity, age, sex, and household income. Multivariate models were used to determine the association between genotype and FA severity.

RESULTS

AD was reported in 193 (45%) and FA in 80 children (19%). Each risk allele increased odds of AD 1.39-fold ([1.03-1.87], P = .03), and AD increased odds of FA 3.67-fold ([2.05- 6.57], P < .01). There was an indirect effect of genotype, mediated by AD, predicting FA; each risk allele increased the odds of FA by 1.13 (odds ratio [95% CI], Q/R = 1.13 [1.02-1.24], R/R = 1.28 [1.04-1.51]; P < .01). Each risk allele increased the odds of severe FA symptoms 2.68-fold ([1.26-5.71], P = .01).

CONCLUSIONS

In a cohort of children with asthma, AD is part of the causal pathway between an IL4RA variant and FA. This variant is associated with increased risk of severe FA reactions. Addressing AD in children with an IL4RA polymorphism may modulate the risk of FA.

Masked Delivery of Allergen in Nanoparticles Safely Attenuates Anaphylactic Response in Murine Models of Peanut Allergy

Food allergy is a growing health concern worldwide. Current allergen-specific immunotherapy (AIT) approaches require frequent dosing over extended periods of time and may induce anaphylaxis due to allergen-effector cell interactions. A critical need remains to develop novel approaches that refine AIT for the treatment of food allergies. Previous studies show that poly(lactide-co-glycolide) (PLG) nanoscale particles (NP) effectively suppress Th1- and Th17-driven immune pathologies. However, their ability to suppress the distinct Th2-polarized immune responses driving food allergy are unknown. Herein, we describe the safety and efficacy of NPs containing encapsulated peanut allergen in desensitizing murine models of peanut allergy. Peanut extract encapsulation allowed for the safe intravenous delivery of allergen relative to non-encapsulated approaches. Application of 2–3 doses, without the need for dose escalation, was sufficient to achieve prophylactic and therapeutic efficacy, which correlated with suppression of Th2-mediated disease and reduced mast cell degranulation. Efficacy was associated with strong reductions in a broad panel of Th1, Th2, and Th17 cytokines. These results demonstrate the ability of PLG NPs to suppress allergen-specific immune responses to induce a more tolerogenic phenotype, conferring protection from intragastric allergen challenge. These promising studies represent a step forward in the development of improved immunotherapies for food allergy.

Early intervention and prevention of allergic diseases

Food allergy (FA) is now one of the most common chronic diseases of childhood often lasting throughout life and leading to significant worldwide healthcare burden. The precise mechanisms responsible for the development of this inflammatory condition are largely unknown; however, a multifactorial aetiology involving both environmental and genetic contributions is well accepted. A precise understanding of the pathogenesis of FA is an essential first step to developing comprehensive prevention strategies that could mitigate this epidemic. As it is frequently preceded by atopic dermatitis and can be prevented by early antigen introduction, the development of FA is likely facilitated by the improper initial presentation of antigen to the developing immune system. Primary oral exposure of antigens allowing for presentation via a well-developed mucosal immune system, rather than through a disrupted skin epidermal barrier, is essential to prevent FA. In this review, we present the data supporting the necessity of (1) an intact epidermal barrier to prevent epicutaneous antigen presentation, (2) the presence of specific commensal bacteria to maintain an intact mucosal immune system and (3) maternal/infant diet diversity, including vitamins and minerals, and appropriately timed allergenic food introduction to prevent FA.

Oral Immunotherapy in Children: Clinical Considerations and Practical Management

Oral immunotherapy (OIT) in pediatric patients provides an alternative option to the current standard of care in food allergy, which is allergen avoidance and reactive treatment. Because patients are exposed to one or more food allergens during treatment, OIT is associated with adverse events and can be a cumbersome process for children, their caregivers, and clinicians. However, there have been an overwhelming number of studies that show high efficacy in both single- and multi-allergen OIT, and that quality of life is greatly improved for both patients and their families after undergoing immunotherapy. This review discusses clinical considerations for OIT in pediatrics, including efficacy and safety, practical management, and future directions of treatment.

[What is the role of allergen immunotherapy in IgE-mediated food allergy?]

In food allergy, allergen avoidance and emergency treatment are still therapeutic hallmarks but, recently, allergen immunotherapy (AIT), with different application routes, has gained more attention. In primary food allergy, oral immunotherapy has been frequently used in clinical trials. This year, an oral immunotherapy preparation for treatment of peanut allergy was licensed in Europe. In secondary food allergy, sublingual and subcutaneous extracts have been used in clinical trials, mostly with cross-reactive pollen allergens. As there is no AIT preparation licensed for this indication, therapy should only be started when there also is a need for treating associated respiratory symptoms.

The Role of Regulatory T Cells in Epicutaneous Immunotherapy for Food Allergy

In recent decades, a rapid increase in the prevalence of food allergies has led to extensive research on novel treatment strategies and their mechanisms. Mouse models have provided preliminary insights into the mechanism of epicutaneous immunotherapy (EPIT)-induced immune tolerance. In EPIT, antigen applied on the skin surface can be captured, processed, and presented in the lymph nodes (LNs) by Antigen-presenting cells (APCs). In the LNs, induction of regulatory T cells (Treg cells) requires both direct contact during antigen presentation and indirect mechanisms such as cytokines. Foxp3+CD62L+ Treg cells can exhibit the characteristics of hypomethylation of Foxp3 TSDR and Foxp3-LAP+ Treg cells, which increase the expression of surface tissue-specific homing molecules to exert further sustained systemic immune tolerance. Studies have shown that EPIT is a potential treatment for food allergies and can effectively induce immune tolerance, but its mechanism needs further exploration. Here, we review Treg cells' role in immune tolerance induced by EPIT and provide a theoretical basis for future research directions, such as the mechanism of EPIT and the development of more effective EPIT treatments.

New Insights in Therapy for Food Allergy

Food allergy is an increasing problem worldwide, with strict avoidance being classically the only available reliable treatment. The main objective of this review is to cover the latest information about the tools available for the diagnosis and treatment of food allergies. In recent years, many efforts have been made to better understand the humoral and cellular mechanisms involved in food allergy and to improve the strategies for diagnosis and treatment. This review illustrates IgE-mediated food hypersensitivity and provides a current description of the diagnostic strategies and advances in different treatments. Specific immunotherapy, including different routes of administration and new therapeutic approaches, such as hypoallergens and nanoparticles, are discussed in detail. Other treatments, such as biologics and microbiota, are also described. Therefore, we conclude that although important efforts have been made in improving therapies for food allergies, including innovative approaches mainly focusing on efficacy and safety, there is an urgent need to develop a set of basic and clinical results to help in the diagnosis and treatment of food allergies.