Oral immunotherapy for treatment of egg allergy in children

Oral immunotherapy for food allergy: A Spanish guideline. Egg and milk immunotherapy Spanish guide (ITEMS GUIDE). Part 2: Maintenance phase of cow milk (CM) and egg oral immunotherapy (OIT), special treatment dosing schedules. Models of dosing schedules of OIT with CM and EGG

INTRODUCTION

Cow's milk and egg are the most frequent causes of food allergy in the first years of life. Treatments such as oral immunotherapy (OIT) have been investigated as an alternative to avoidance diets. No clinical practice guides on the management of OIT with milk and egg are currently available.

OBJECTIVES

To develop a clinical guide on OIT based on the available scientific evidence and the opinions of experts.

METHODS

A review was made of studies published in the period between 1984 and June 2016, Doctoral Theses published in Spain, and summaries of communications at congresses (SEAIC, SEICAP, EAACI, AAAAI), with evaluation of the opinion consensus established by a group of experts pertaining to the scientific societies SEICAP and SEAIC.

RESULTS

Recommendations have been established regarding the indications, requirements and practical aspects of the different phases of OIT, as well as special protocols for patients at high risk of suffering adverse reactions.

CONCLUSIONS

A clinical practice guide is presented for the management of OIT with milk and egg, based on the opinion consensus of Spanish experts.

Long-term clinical and immunological effects of probiotic and peanut oral immunotherapy after treatment cessation: 4-year follow-up of a randomised, double-blind, placebo-controlled trial

BACKGROUND

Oral immunotherapy has attracted much interest as a potential treatment for food allergy, yet little is known about its long-term effects. We aimed to assess long-term outcomes in participants who completed a randomised, double-blind, placebo-controlled trial of combined probiotic and peanut oral immunotherapy (PPOIT), which was previously shown to induce desensitisation and 2-week sustained unresponsiveness.

METHODS

All participants who completed the PPOIT randomised trial were eligible to participate in this follow-up study 4 years after treatment cessation. Peanut intake and adverse reactions to peanut in the 4 years after treatment cessation were systematically documented with a structured questionnaire administered by allergy nurses. Additionally, participants were invited to undergo peanut skin prick tests, measurement of peanut sIgE and sIgG4 concentrations, and double-blind placebo-controlled peanut challenge to assess 8-week sustained unresponsiveness.

FINDINGS

48 (86%) of 56 eligible participants were enrolled in the follow-up study. Mean time since stopping treatment was 4·2 years in both PPOIT (SD 0·6) and placebo (SD 0·7) participants. Participants from the PPOIT group were significantly more likely than those from the placebo group to have continued eating peanut (16 [67%] of 24 vs one [4%] of 24; absolute difference 63% [95% CI 42-83], p=0·001; number needed to treat 1·6 [95% CI 1·2-2·4]). Four PPOIT-treated participants and six placebo participants reported allergic reactions to peanut after intentional or accidental intake since stopping treatment, but none had anaphylaxis. PPOIT-treated participants had smaller wheals in peanut skin prick test (mean 8·1 mm [SD 7·7] vs 13·3 mm [7·6]; absolute difference -5·2 mm [95% CI -10·3 to 0·0]; age-adjusted and sex-adjusted p=0·035) and significantly higher peanut sIgG4:sIgE ratios than placebo participants (geometric mean 67·3 [95% CI 10·3-440·0] vs 5·2 [1·2-21·8]; p=0·031). Seven (58%) of 12 participants from the PPOIT group attained 8-week sustained unresponsiveness, compared with one (7%) of 15 participants from the placebo group (absolute difference 52% [95% CI 21-82), p=0·012; number needed to treat 1·9 [95% CI 1·2-4·8]).

INTERPRETATION

PPOIT provides long-lasting clinical benefit and persistent suppression of the allergic immune response to peanut.

FUNDING

Murdoch Childrens Research Institute and Australian Food Allergy Foundation.

Deciphering the black box of food allergy mechanisms

OBJECTIVE

To review our current understanding of immunotherapy, the immune mechanisms underlying food allergy, and the methodological advances that are furthering our understanding of the role of immune cells and other molecules in mediating food allergies.

DATA SOURCES

Literature searches were performed using the following combination of terms: allergy, immunotherapy, food, and mechanisms. Data from randomized clinical studies using state-of-the-art mechanistic tools were prioritized.

STUDY SELECTIONS

Articles were selected based on their relevance to food allergy.

RESULTS

Current standard of care for food allergies is avoidance of allergenic foods and the use of epinephrine in case of severe reaction during unintentional ingestion. During the last few decades, great strides have been made in understanding the cellular and molecular mechanisms underlying food allergy, and this information is spearheading the development of exciting new treatments.

CONCLUSION

Immunotherapy protocols are effective in desensitizing individuals to specific allergens; however, recurrence of allergic sensitization is common after discontinuation of therapy. Interestingly, in a subset of individuals, immunotherapy is protective against allergens even after discontinuation of immunotherapy. Whether this protection is permanent is currently unknown because of inadequate long-term follow-up data. Research on understanding the underlying mechanisms may assist in modifying protocols to improve outcome and enable sustained unresponsiveness, rather than a temporary relief against food allergies. The cellular changes brought about by immunotherapy are still a black box, but major strides in our understanding are being made at an exciting pace.

Clinical aspects of oral immunotherapy for the treatment of allergies

Studies on oral immunotherapy (OIT) have been increasing worldwide. Nevertheless, some concerns exist with this treatment. The rate of long-term sustained unresponsiveness is quite low; moreover, the desensitization or sustained unresponsiveness does not equate to tolerance. Furthermore, adverse reactions are frequent. Therefore, safe and feasible methods for long-term therapies are needed. Novel therapies such as low-dose OIT, hypoallergenic products, and OIT in combination with omalizumab are reported as effective for inducing sustained unresponsiveness and may lead to fewer adverse reactions than standard OIT. Increased safety will contribute to feasibility of OIT. Currently, oral food challenge (OFC) with the low target dose has been reported. We may reduce the need for OIT by implementing low-dose OFC. More effective, safe, and feasible OIT strategies are needed.

Road map for the clinical application of the basophil activation test in food allergy

The diagnosis of IgE‐mediated food allergy based solely on the clinical history and the documentation of specific IgE to whole allergen extract or single allergens is often ambiguous, requiring oral food challenges (OFCs), with the attendant risk and inconvenience to the patient, to confirm the diagnosis of food allergy. This is a considerable proportion of patients assessed in allergy clinics. The basophil activation test (BAT) has emerged as having superior specificity and comparable sensitivity to diagnose food allergy, when compared with skin prick test and specific IgE. BAT, therefore, may reduce the number of OFC required for accurate diagnosis, particularly positive OFC. BAT can also be used to monitor resolution of food allergy and the clinical response to immunomodulatory treatments. Given the practicalities involved in the performance of BAT, we propose that it can be applied for selected cases where the history, skin prick test and/or specific IgE are not definitive for the diagnosis of food allergy. In the cases that the BAT is positive, food allergy is sufficiently confirmed without OFC; in the cases that BAT is negative or the patient has non‐responder basophils, OFC may still be indicated. However, broad clinical application of BAT demands further standardization of the laboratory procedure and of the flow cytometry data analyses, as well as clinical validation of BAT as a diagnostic test for multiple target allergens and confirmation of its feasibility and cost‐effectiveness in multiple settings.

Allergen immunotherapy for IgE-mediated food allergy: a systematic review and meta-analysis

BACKGROUND

The European Academy of Allergy and Clinical Immunology (EAACI) is developing Guidelines for Allergen Immunotherapy (AIT) for IgE-mediated Food Allergy. To inform the development of clinical recommendations, we sought to critically assess evidence on the effectiveness, safety and cost-effectiveness of AIT in the management of food allergy.

METHODS

We undertook a systematic review and meta-analysis that involved searching nine international electronic databases for randomized controlled trials (RCTs) and nonrandomized studies (NRS). Eligible studies were independently assessed by two reviewers against predefined eligibility criteria. The quality of studies was assessed using the Cochrane Risk of Bias tool for RCTs and the Cochrane ACROBAT-NRS tool for quasi-RCTs. Random-effects meta-analyses were undertaken, with planned subgroup and sensitivity analyses.

RESULTS

We identified 1814 potentially relevant papers from which we selected 31 eligible studies, comprising of 25 RCTs and six NRS, studying a total of 1259 patients. Twenty-five trials evaluated oral immunotherapy (OIT), five studies investigated sublingual immunotherapy, and one study evaluated epicutaneous immunotherapy. The majority of these studies were in children. Twenty-seven studies assessed desensitization, and eight studies investigated sustained unresponsiveness postdiscontinuation of AIT. Meta-analyses demonstrated a substantial benefit in terms of desensitization (risk ratio (RR) = 0.16, 95% CI 0.10, 0.26) and suggested, but did not confirm sustained unresponsiveness (RR = 0.29, 95% CI 0.08, 1.13). Only one study reported on disease-specific quality of life (QoL), which reported no comparative results between OIT and control group. Meta-analyses revealed that the risk of experiencing a systemic adverse reaction was higher in those receiving AIT, with a more marked increase in the risk of local adverse reactions. Sensitivity analysis excluding those studies judged to be at high risk of bias demonstrated the robustness of summary estimates of effectiveness and safety of AIT for food allergy. None of the studies reported data on health economic analyses.

CONCLUSIONS

AIT may be effective in raising the threshold of reactivity to a range of foods in children with IgE-mediated food allergy whilst receiving (i.e. desensitization) and post-discontinuation of AIT. It is, however, associated with a modest increased risk in serious systemic adverse reactions and a substantial increase in minor local adverse reactions. More data are needed in relation to adults, long term effects, the impact on QoL and the cost-effectiveness of AIT.

Pros and Cons of Clinical Basophil Testing (BAT)

PURPOSE OF REVIEW

We review basophil testing by flow cytometry with an emphasis on advantages and disadvantages.

RECENT FINDINGS

There are many tools available to assess the presence and severity of allergic diseases in patients. For 50 years, peripheral blood basophils have been used as tools to study these diseases. It is a very accessible cell that binds IgE antibody and secretes the classical mediators responsible for the symptoms of allergic reactions. In the last decade, an even more accessible methodology, using flow cytometry, has been developed to enhance the ability to use basophils for both mechanistic and clinical diagnostics. Basophil testing has been included in diagnostics for different forms of allergies as well as to monitor disease status. A variety of studies have begun to establish both precise methods and their clinical relevance for disease diagnosis, but there remain some important questions on how to take optimal advantage of the behaviours of basophils.

Data-driven programmatic approach to analysis of basophil activation tests

BACKGROUND

Conventional data analysis of flow cytometry-based basophil activation testing requires repetitive, labor-intensive analysis that hampers efforts to standardize testing for clinical applications. Using an open-source platform, we developed and implemented a programmatic approach to the analysis of the basophil activation test (BAT) by flow cytometry.

METHODS

Using the BÜHLMANN FlowCAST® assay, peripheral blood from peanut allergic patients undergoing oral immunotherapy was incubated with peanut allergens (Arah1, Arah2, Arah6, whole peanut extract) and stained with fluorescent antibodies to CCR3 and CD63 for the development of a data-driven programmatic analysis using Bioconductor and R. Basophil identification using clustering and classification was validated using manually gated comparisons in an experimental subset. Reproducibility of CD63 upregulation set on unstimulated or anti-FcERI stimulated basophils was compared.

RESULTS

BAT analysis of 294 experiments was successful in 91.5% using the above approach, with a total of 7,166 individual basophil activation tests from 269 experiments. We estimate this represents a net saving of 1340 min of labor by a skilled operator. Medium-based gating correlated to respective manual gating more closely than anti-FcERI based gating (R = 0.96 vs. R = 0.84, P < 0.001). Only 2% of the basophil activation results were significantly different from manual gating. Quality measures of the experiments and other measures of basophil activation were also provided by the analysis.

CONCLUSIONS

We present a novel data-driven flow cytometric platform for the analysis of clinical basophil activation testing, providing a high throughput objective approach to basophil activation analysis. © 2017 International Clinical Cytometry Society.

Oral immunotherapy for food allergy: A Spanish guideline. Immunotherapy egg and milk Spanish guide (items guide). Part I: Cow milk and egg oral immunotherapy: Introduction, methodology, rationale, current state, indications contraindications and oral immunotherapy build-up phase

INTRODUCTION

Cow's milk and egg are the most frequent causes of food allergy in the first years of life. Treatments such as oral immunotherapy (OIT) have been investigated as an alternative to avoidance diets. No clinical practice guides on the management of OIT with milk and egg are currently available.

OBJECTIVES

To develop a clinical guide on OIT based on the available scientific evidence and the opinions of experts.

METHODS

A review was made of studies published in the period between 1984 and June 2016, Doctoral Theses published in Spain, and summaries of communications at congresses (SEAIC, SEICAP, EAACI, AAAAI), with evaluation of the opinion consensus established by a group of experts pertaining to the scientific societies SEICAP and SEAIC.

RESULTS

Recommendations have been established regarding the indications, requirements and practical aspects of the different phases of OIT, as well as special protocols for patients at high risk of suffering adverse reactions.

CONCLUSIONS

A clinical practice guide is presented for the management of OIT with milk and egg, based on the opinion consensus of Spanish experts.

Novel approaches and perspectives in allergen immunotherapy

In this review, we report on relevant current topics in allergen immunotherapy (AIT) which were broadly discussed during the first Aarhus Immunotherapy Symposium (Aarhus, Denmark) in December 2015 by leading clinicians, scientists and industry representatives in the field. The aim of this symposium was to highlight AIT-related aspects of public health, clinical efficacy evaluation, mechanisms, development of new biomarkers and an overview of novel therapeutic approaches. Allergy is a public health issue of high socioeconomic relevance, and development of evidence-based action plans to address allergy as a public health issue ought to be on national and regional agendas. The underlying mechanisms are in the focus of current research that lays the ground for innovative therapies. Standardization and harmonization of clinical endpoints in AIT trials as well as current knowledge about potential biomarkers have substantiated proof of effectiveness of this disease-modifying therapeutic option. Novel treatments such as peptide immunotherapy, intralymphatic immunotherapy and use of recombinant allergens herald a new age in which AIT may address treatment of allergy as a public health issue by reaching a large fraction of patients.

Toward precision medicine and health: Opportunities and challenges in allergic diseases

Precision medicine (also called personalized, stratified, or P4 medicine) can be defined as the tailoring of preventive measures and medical treatments to the characteristics of each patient to obtain the best clinical outcome for each person while ideally also enhancing the cost-effectiveness of such interventions for patients and society. Clearly, the best clinical outcome for allergic diseases is not to get them in the first place. To emphasize the importance of disease prevention, a critical component of precision medicine can be referred to as precision health, which is defined herein as the use of all available information pertaining to specific subjects (including family history, individual genetic and other biometric information, and exposures to risk factors for developing or exacerbating disease), as well as features of their environments, to sustain and enhance health and prevent the development of disease. In this article I will provide a personal perspective on how the precision health-precision medicine approach can be applied to the related goals of preventing the development of allergic disorders and providing the most effective diagnosis, disease monitoring, and care for those with these prevalent diseases. I will also mention some of the existing and potential challenges to achieving these ambitious goals.

Evidence that eating baked egg or milk influences egg or milk allergy resolution: a systematic review

BACKGROUND

It has been proposed that the frequent ingestion of baked hen's egg or cow's milk accelerates the resolution of hen's egg or cow's milk allergy. This practice is being introduced into clinical practice.

OBJECTIVE

To systematically review the evidence to determine whether the introduction of baked hen's egg or cow's milk into the diet of children with hen's egg or cow's milk allergies respectively leads to a larger proportion of children outgrowing these allergies than expected.

METHODS

A systematic review of the literature was conducted in Medline, Embase and CINAHL. The inclusion criteria were as follows: randomized control trials, case-control or cohort studies; children aged 0-18 years with hen's egg or cow's milk allergy; baked hen's egg or cow's milk intervention with or without a comparator; and resolution of the hen's egg or cow's milk allergy as determined by food challenge as the outcome. Studies were critically appraised using the quality assessment tool for quantitative studies. PROSPERO reference CRD42015026029.

RESULTS

We identified 851 and 2816 hen's egg and cow's milk articles respectively. Only three hen's egg and three cow's milk studies fulfilled our pre-specified inclusion criteria. The studies concluded that baked products either increased the likelihood of the resolution of allergy or accelerated resolution. However, when critiqued, all studies were classified as weak because they were observational, lacking an appropriate control group; this brings into doubt the study's conclusions. There were a number of examples of severe reactions to baked products.

CONCLUSION

There is little evidence to address the hypothesis that the ingestion of baked hen's egg or cow's milk results in more patients outgrowing their hen's egg or cow's milk allergy respectively. Data are required from a trial comparing the resolution rates of baked-tolerant participants who are randomized to ingest or avoid baked products to assess the accuracy of this hypothesis.

Randomized controlled trial of oral immunotherapy for egg allergy in Japanese patients

BACKGROUND

Egg allergy is one of the most common food allergies in young children. While oral immunotherapy (OIT) is not routinely recommended in current guidelines, it has been considered as a potential alternative treatment strategy. Studies on OIT for food allergy have been explored, but no controlled trials have been reported in Japan.

METHODS

The first oral food challenge (OFC) was performed before treatment to ensure diagnosis and evaluate the threshold dose for egg using the double-blind, placebo-controlled food challenge. Participants were randomly assigned by computerized algorithm to receive OIT using egg (OIT group) or no egg (egg elimination [EE] group). A second OFC was performed in both groups approximately 6 months after therapy. Blood samples were collected and egg white-specific immunoglobulin (Ig)E and IgG4 were measured before and after the treatment period.

RESULTS

Eight of the 14 patients (57%) in the OIT group had no allergic reaction to 4 g dry egg powder whereas none of the 16 patients in the EE group did. All 14 patients in the OIT group had increased threshold for egg powder in the second OFC compared with baseline. There was no significant change in egg white-specific IgE level during therapy. After therapy, egg white-specific IgG4 increased significantly in the OIT group, but not in the EE group.

CONCLUSION

OIT is effective in increasing the threshold for allergens and inducing desensitization in Japanese egg allergy patients, similarly to North American and European patients.

Mechanistic correlates of clinical responses to omalizumab in the setting of oral immunotherapy for milk allergy

BACKGROUND

In our recent clinical trial, the addition of omalizumab to oral immunotherapy (OIT) for milk allergy improved safety, but no significant clinical benefit was detected.

OBJECTIVE

We sought to investigate mechanisms by which omalizumab modulates immunity in the context of OIT and to identify baseline biomarkers that predict subgroups of patients most likely to benefit from omalizumab.

METHODS

Blood was obtained at baseline and multiple time points during a placebo-controlled trial of OIT for milk allergy in which subjects were randomized to receive omalizumab or placebo. Immunologic outcomes included measurement of basophil CD63 expression and histamine release and casein-specific CD4⁺ regulatory T-cell proliferation. Biomarkers were analyzed in relationship to measurements of safety and efficacy.

RESULTS

Milk-induced basophil CD63 expression was transiently reduced in whole blood samples from both omalizumab- and placebo-treated subjects. However, IgE-dependent histamine release increased in washed cell preparations from omalizumab- but not placebo-treated subjects. No increase in regulatory T-cell frequency was evident in either group. Subjects with lower rates of adverse reactions, regardless of arm, experienced better clinical outcomes. Pre-OIT basophil reactivity positively associated with occurrence of symptoms during OIT, whereas the baseline milk IgE/total IgE ratio correlated with the likelihood of achieving sustained unresponsiveness. A combination of baseline basophil and serologic biomarkers defined a subset of patients in which adjunctive therapy with omalizumab was associated with attainment of sustained unresponsiveness and a reduction in adverse reactions.

CONCLUSIONS

Combining omalizumab therapy with milk OIT led to distinct alterations in basophil reactivity but not T-cell responses. Baseline biomarkers can identify subjects most likely to benefit from adjunctive therapy with omalizumab.

Safety and efficacy of short-term oral immunotherapy with Cry j 1-galactomannan conjugate for Japanese cedar pollinosis: a randomized controlled trial

Current allergen-specific immunotherapy (AIT) for pollinosis requires long-term treatment with potentially severe side effects. Therefore, development of an AIT that is safe and more convenient with a shorter regimen is needed. This prospective, double-blind, placebo-controlled trial randomized 55 participants with Japanese cedar pollinosis (JCP) to active or placebo groups to test the safety and efficacy of short-term oral immunotherapy (OIT) with Cry j 1-galactomannan conjugate for JCP. Mean symptom-medication score as the primary outcome in the active group improved 27.8% relative to the placebo group during the entire pollen season. As the secondary outcomes, mean medication score in active group improved significantly, by 56.2%, compared with placebo during the entire pollen season. Mean total symptom score was similar between active and placebo groups during the entire pollen season. There were no severe treatment-emergent adverse events in the active and placebo groups. Therefore short-term OIT with Cry j 1-galactomannan conjugate is safe, and effective for reducing the amount of medication use for JCP.

Japanese guidelines for food allergy 2017

Five years have passed since the Japanese Pediatric Guideline for Food Allergy (JPGFA) was first revised in 2011 from its original version. As many scientific papers related to food allergy have been published during the last 5 years, the second major revision of the JPGFA was carried out in 2016. In this guideline, food allergies are generally classified into four clinical types: (1) neonatal and infantile gastrointestinal allergy, (2) infantile atopic dermatitis associated with food allergy, (3) immediate-type of food allergy (urticaria, anaphylaxis, etc.), and (4) special forms of immediate-type of food allergy such as food-dependent exercise-induced anaphylaxis and oral allergy syndrome (OAS). Much of this guideline covers the immediate-type of food allergy that is seen during childhood to adolescence. Infantile atopic dermatitis associated with food allergy type is especially important as the onset of most food allergies occurs during infancy. We have discussed the neonatal and infantile gastrointestinal allergy and special forms of immediate type food allergy types separately. Diagnostic procedures are highlighted, such as probability curves and component-resolved diagnosis, including the recent advancement utilizing antigen-specific IgE. The oral food challenge using a stepwise approach is recommended to avoid complete elimination of causative foods. Although oral immunotherapy (OIT) has not been approved as a routine treatment by nationwide insurance, we included a chapter for OIT, focusing on efficacy and problems. Prevention of food allergy is currently the focus of interest, and many changes were made based on recent evidence. Finally, the contraindication between adrenaline and antipsychotic drugs in Japan was discussed among related medical societies, and we reached an agreement that the use of adrenaline can be allowed based on the physician's discretion. In conclusion, this guideline encourages physicians to follow the principle to let patients consume causative foods in any way and as early as possible.

Efficacy and safety of high-dose rush oral immunotherapy in persistent egg allergic children: A randomized clinical trial

BACKGROUND

Egg oral immunotherapy is effective but time consuming.

OBJECTIVE

To assess the efficacy and safety of egg rush oral immunotherapy (ROIT) with a targeted dose equivalent to a raw egg white.

METHODS

Thirty-three persistent egg allergic children confirmed by double-blind, placebo-controlled food challenge (DBPCFC) were randomized to receive egg ROIT immediately after randomization (ROIT1 group), or to continue an egg avoidance diet for 5 months after randomization (control group [CG]). A 5-day build-up phase starting with the highest single tolerated dose at baseline DBPCFC was scheduled and several doses administered daily until achieving a dose of approximately 2,808 mg of egg white protein. In the maintenance phase, patients ate an undercooked egg every 48 hours for 5 months. The CG participants who failed the DBPCFC at 5 months began active treatment. Children from the ROIT1 group plus children from the CG who failed a second DBPCFC at 5 months and then received egg ROIT were randomized to the ROIT2 group. Adverse events (AEs) and immune marker evolution were recorded.

RESULTS

A total of 17 (89%) of 19 children in the ROIT1 group and no CG patients were desensitized at 5 months (P < .001). A total of 31 (97%) of the 32 children in the ROIT2 group completed the build-up phase in a median of 3 days (range, 1-14 days), and 30 (94%) of 32 maintained desensitization at 5 months. From baseline to 5 months of treatment, skin prick test, specific IgE, and specific IgE/IgG4 ratio to egg fractions significantly decreased, whereas specific IgG4 increased. During the build-up phase, AEs occurred in 69% of patients (50% had ≤2 AEs) and 31% of doses (2% severe, 55% gastrointestinal). Lower threshold dose in the DBPCFC and higher egg white and ovalbumin specific IgE levels at baseline revealed an association with a higher rate of AEs.

CONCLUSION

The proposed 5-day egg ROIT desensitized 94% of the allergic patients, with most AEs being mild or moderate.

A Dynamic Model of Immune Responses to Antigen Presentation Predicts Different Regions of Tumor or Pathogen Elimination

The immune system must discriminate between agents of disease and an organism's healthy cells. While the identification of an antigen as self/non-self is critically important, the dynamic features of antigen presentation may also determine the immune system's response. Here, we use a simple mathematical model of immune activation to explore the idea of antigen discrimination through dynamics. We propose that antigen presentation is coupled to two nodes, one regulatory and one effecting the immune response, through an incoherent feedforward loop and repressive feedback. This circuit would allow the immune system to effectively estimate the increase of antigens with respect to time, a key determinant of immune reactivity in vivo. Our model makes the prediction that tumors growing at specific rates evade the immune system despite the continuous presence of antigens indicating disease, a phenomenon closely related to clinically observed "two-zone tolerance." Finally, we discuss a plausible biological instantiation of our circuit using combinations of regulatory and effector T cells.

Application of phage peptide display technology for the study of food allergen epitopes

Phage peptide display technology has been used to identify IgE-binding mimotopes (mimics of natural epitopes) that mimic conformational epitopes. This approach is effective in the characterization of those epitopes that are important for eliciting IgE-mediated allergic responses by food allergens and those that are responsible for cross-reactivity among allergenic food proteins. Application of this technology will increase our understanding of the mechanisms whereby food allergens elicit allergic reactions, will facilitate the discovery of diagnostic reagents and may lead to mimotope-based immunotherapy.

Double-blind placebo-controlled challenge showed that peanut oral immunotherapy was effective for severe allergy without negative effects on airway inflammation

AIM

This study examined the efficacy and the safety of peanut oral immunotherapy (OIT).

METHODS

We recruited 60 patients aged six years to 18 years who had a moderate-to-severe reaction to a double-blind placebo-controlled peanut challenge: 39 received OIT during an eight-month build-up phase and maintenance phase and 21 controls avoided peanuts. We measured specific immunoglobulin E and G4 (IgE and IgG4) to peanuts and to Ara h 1, 2, 3, 8 and 9 and monitored adverse events, bronchial hyper-responsiveness (BHR) to methacholine and fractional concentrations of exhaled nitric oxide (FeNO). The median follow-up period was 30 months.

RESULTS

Most (85%) of the OIT patients passed the build-up phase and 67% tolerated 5 g of peanuts during the post-treatment challenge. No controls were desensitised, with a risk ratio of 29 and 95% confidence interval of 1.9-455. During OIT, IgE to peanut, Ara h 1, 2 and 3 decreased and IgG4 increased. Consuming peanuts had no harmful effects on BHR or FeNO. The annual incidence rate of emergency visits during the follow-up period was 11% or 3.0 per 10 000 patient-days.

CONCLUSION

Peanut OIT was efficacious in severe allergies without negative effects on airway inflammation, but unpredictable long-term reactions might occur.

Preparation and Analysis of Peanut Flour Used in Oral Immunotherapy Clinical Trials

BACKGROUND

Oral immunotherapy (OIT) is an investigational therapeutic approach for the treatment of food allergies. Characterization of the drug product used in oral immunotherapy trials for peanut allergy has not been reported.

OBJECTIVE

To quantify relative amounts of the major peanut allergens and microbial load present in peanut flour used in OIT trials and assess whether these parameters change over a 12-month period. We also anticipate that this report will serve as a guide for investigators seeking to conduct OIT trials under Food and Drug Administration-approved Investigational New Drug applications.

METHODS

Densitometric scanning of Ara h 1 and Ara h 2 resolved on SDS-PAGE gels was used to assess allergen content in peanut flour extracts. Microbial testing was conducted on peanut flour under US Pharmacopeia guidelines for the presence of Escherichia coli, salmonella, yeast, mold, and total aerobic bacteria. In addition, aflatoxin was quantified in peanut flour. Reported results were obtained from 4 unique lots of peanut flour.

RESULTS

Relative amounts of the major peanut allergens were similar between different lots of peanut flour and remained stable over a 12-month period. E coli and salmonella were absent from all lots of flour. Yeast, mold, total aerobic bacteria, and aflatoxin were within established US Pharmacopeia guidelines on all lots tested and remained within the criteria over a 12-month period.

CONCLUSIONS

Peanut flour used as a drug product contains the major peanut allergens and has low levels of potentially harmful microbes. Both these parameters remain stable over a 12-month period.

Clinical practice recommendations for allergen-specific immunotherapy in children: the Italian consensus report

Allergen-specific immunotherapy (AIT) is currently recognized as a clinically effective treatment for allergic diseases, with a unique disease-modifying effect. AIT was introduced in clinical practice one century ago, and performed in the early years with allergenic extracts of poor quality and definition. After the mechanism of allergic reaction were recognized, the practice of AIT was refined, leading to remarkable improvement in the efficacy and safety profile of the treatment. Currently AIT is accepted and routinely prescribed worldwide for respiratory allergies and hymenoptera venom allergy. Both the subcutaneous (SCIT) and sublingual (SLIT) routes of administration are used in the pediatric population.AIT is recommended in allergic rhinitis/conjunctivitis with/without allergic asthma, with an evidence of specific IgE-sensitization towards clinically relevant inhalant allergens. Long-term studies provided evidence that AIT can also prevent the onset of asthma and of new sensitizations. The favorable response to AIT is strictly linked to adherence to treatment, that lasts 3-5 years. Therefore, several factors should be carefully evaluated before starting this intervention, including the severity of symptoms, pharmacotherapy requirements and children and caregivers' preference and compliance.In recent years, there have been increasing interest in the role of AIT for the treatment of IgE-associated food allergy and extrinsic atopic dermatitis. A growing body of evidence shows that oral immunotherapy represents a promising treatment option for IgE-associated food allergy. On the contrary, there are still controversies on the effectiveness of AIT for patients with atopic dermatitis.This consensus document was promoted by the Italian Society of Pediatric Allergy and Immunology (SIAIP) to provide evidence-based recommendations on AIT in order to implement and optimize current prescription practices of this treatment for allergic children.

Improvement of Therapeutic Efficacy of Oral Immunotherapy in Combination with Regulatory T Cell-Inducer Kakkonto in a Murine Food Allergy Model

Oral immunotherapy (OIT) has been considered a promising approach for food allergies (FAs). However, the current OIT strategy is limited in terms of the long-term efficacy and safety. We have previously demonstrated that kakkonto, a traditional Japanese herbal medicine, suppresses the occurrence of allergic symptoms in a murine model of ovalbumin (OVA)-induced FA, which is attributed to the induction of the Foxp3⁺ CD4⁺ regulatory T cells. In this study, we established an OIT model using the FA mice with already established allergic symptoms and determined whether kakkonto could improve the efficacy of OIT. The OIT method consisted of initially administrating a very small amount of OVA and slowly increasing the amount. Allergic symptoms decreased in the OIT-treated FA mice. OIT significantly downregulated Th2 immune response-related gene expression in the FA mouse colon, and decreased the level of mouse mast cell protease-1, a marker of mast cell degranulation in the FA mouse plasma. Moreover, the concomitant use of kakkonto significantly enhanced the effectiveness of OIT on the allergic symptoms, and the combination therapy further suppressed the Th2 immune responses and the mast cell degranulation. In addition, OIT significantly increased the population of Foxp3⁺ CD4⁺ regulatory T cells in the FA mouse colon, and this population was further increased by OIT in combination with kakkonto. Furthermore, the combined therapy with kakkonto reduced the expression of RA-degrading enzyme CYP26B1 mRNA in the FA mouse colon. These findings indicated that the combination of OIT with kakkonto represents a promising approach for FA treatment.

IL-9-producing cells in the development of IgE-mediated food allergy

Food allergy is a harmful immune reaction driven by uncontrolled type 2 immune responses. Considerable evidence demonstrates the key roles of mast cells, IgE, and TH2 cytokines in mediating food allergy. However, this evidence provides limited insight into why only some, rather than all, food allergic individuals are prone to develop life-threatening anaphylaxis. Clinical observations suggest that patients sensitized to food through the skin early in life may later develop severe food allergies. Aberrant epidermal thymic stromal lymphopoietin and interleukin (IL) 33 production and genetic predisposition can initiate an allergic immune response mediated by dendritic cells and CD4+TH2 cells in inflamed skin. After allergic sensitization, intestinal IL-25 and food ingestion enhance concerted interactions between type 2 innate lymphoid cells (ILC2s) and CD4+TH2 cells, which perpetuate allergic reactions from the skin to the gut. IL-4 and cross-linking of antigen/IgE/FcεR complexes induce emigrated mast cell progenitors to develop into the multi-functional IL-9-producing mucosal mast cells, which produce prodigious amounts of IL-9 and mast cell mediators to drive intestinal mastocytosis in an autocrine loop. ILC2s and TH9 cells may also serve as alternative cellular sources of IL-9 to augment the amplification of intestinal mastocytosis, which is the key cellular checkpoint in developing systemic anaphylaxis. These findings provide a plausible view of how food allergy develops and progresses in a stepwise manner and that atopic signals, dietary allergen ingestion, and inflammatory cues are fundamental in promoting life-threatening anaphylaxis. This information will aid in improving diagnosis and developing more effective therapies for food allergy-triggered anaphylaxis.

The role of allergen immunotherapy in the management of allergic rhinitis

PURPOSE

To evaluate the role of allergen immunotherapy (AIT) in the treatment of allergic rhinitis (AR).

METHOD

Individual studies, systematic reviews, and practice guidelines that included information on sublingual AIT (SLIT) and subcutaneous AIT (SCIT) in the treatment of AR were considered.

RESULTS

AIT via the SLIT or SCIT route has been shown to be effective in treating AR symptoms with resultant improvements in overall quality of life, comorbid illnesses, and medication requirements. Persistent clinical benefits have been demonstrated years after AIT treatment discontinuation. AIT may prevent the progression of AR to asthma. In addition, studies that evaluated the pharmacoeconomics of AR treatment indicate that AIT may be more cost effective than pharmacotherapy. The AIT cost savings are likely underestimated in that few cost comparison studies considered AIT's long-term benefits or preventive effects.

CONCLUSION

Multiple individual studies and systematic reviews provide strong evidence for the clinical effectiveness of AIT in the treatment of AR. Cost-effectiveness and disease modification are additional advantages of AIT compared with standard drug treatment in the management of AR.

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.

Food allergy: immune mechanisms, diagnosis and immunotherapy

Food allergy is a pathological, potentially deadly, immune reaction triggered by normally innocuous food protein antigens. The prevalence of food allergies is rising and the standard of care is not optimal, consisting of food-allergen avoidance and treatment of allergen-induced systemic reactions with adrenaline. Thus, accurate diagnosis, prevention and treatment are pressing needs, research into which has been catalysed by technological advances that are enabling a mechanistic understanding of food allergy at the cellular and molecular levels. We discuss the diagnosis and treatment of IgE-mediated food allergy in the context of the immune mechanisms associated with healthy tolerance to common foods, the inflammatory response underlying most food allergies, and immunotherapy-induced desensitization. We highlight promising research advances, therapeutic innovations and the challenges that remain.

Blocking antibodies induced by immunization with a hypoallergenic parvalbumin mutant reduce allergic symptoms in a mouse model of fish allergy

BACKGROUND

Fish is a frequent elicitor of severe IgE-mediated allergic reactions. Beside avoidance, there is currently no allergen-specific therapy available. Hypoallergenic variants of the major fish allergen, parvalbumin, for specific immunotherapy based on mutation of the 2 calcium-binding sites have been developed.

OBJECTIVES

This study sought to establish a mouse model of fish allergy resembling human disease and to investigate whether mouse and rabbit IgG antibodies induced by immunization with a hypoallergenic mutant of the major carp allergen protect against allergic symptoms in sensitized mice.

METHODS

C3H/HeJ mice were sensitized with recombinant wildtype Cyp c 1 or carp extract by intragastric gavage. Antibody, cellular immune responses, and epitope specificity in sensitized mice were investigated by ELISA, rat basophil leukemia assay, T-cell proliferation experiments using recombinant wildtype Cyp c 1, and overlapping peptides spanning the Cyp c 1 sequence. Anti-hypoallergenic Cyp c 1 mutant mouse and rabbit sera were tested for their ability to inhibit IgE recognition of Cyp c 1, Cyp c 1-specific basophil degranulation, and Cyp c 1-induced allergic symptoms in the mouse model.

RESULTS

A mouse model of fish allergy mimicking human disease regarding IgE epitope recognition and symptoms as close as possible was established. Administration of antisera generated in mice and rabbits by immunization with a hypoallergenic Cyp c 1 mutant inhibited IgE binding to Cyp c 1, Cyp c 1-induced basophil degranulation, and allergic symptoms caused by allergen challenge in sensitized mice.

CONCLUSIONS

Antibodies induced by immunization with a hypoallergenic Cyp c 1 mutant protect against allergic reactions in a murine model of fish allergy.

Component-resolved analysis of IgA, IgE, and IgG4 during egg OIT identifies markers associated with sustained unresponsiveness

BACKGROUND

In a previously reported CoFAR study, 55 subjects with egg allergy underwent randomized, placebo-controlled egg oral immunotherapy (eOIT). Active treatment induced desensitization in most and sustained unresponsiveness (SU) in a smaller subset. We hypothesized that component-resolved analysis of IgE, IgG4, IgA, IgA1, and IgA2 may identify potential biomarkers of SU in OIT subjects.

METHODS

Longitudinal samples for 51 egg-allergic subjects (37 active and 14 placebo) were available. Egg white (EW)-, ovalbumin (OVA)-, and ovomucoid (OVM)-specific levels of IgA, IgA1, and IgA2 were quantified by ELISA. IgE and IgG4 to these antigens were quantified using ImmunoCAP^® . Clinical responders achieved SU to egg; all others were considered nonresponders. Between-group comparisons were made among active and placebo, as well as responders and nonresponders.

RESULTS

No placebo subjects achieved responder status. Through month 48, among the 37 active subjects, baseline IgE-OVM was lower in responders (median 3.97 kU/l, n = 19) than in nonresponders (10.9 kU/l, n = 18, P = 0.010). Logistic regression analysis revealed that lower baseline IgE-EW (P = 0.038), IgE-OVM (P = 0.032), and a higher IgG4/IgE-OVM ratio (P = 0.013) were associated with clinical response. Relative increases in IgG4-EW, IgA-EW, and IgA2-EW were observed in responders (P = 0.024, 0.024, and 0.029, respectively). IgG4/IgE, IgA/IgE, and IgA2/IgE ratios for EW and IgA/IgE ratio for OVA were found to be significantly elevated among responders (P = 0.004, 0.009, 0.028, and 0.008, respectively).

CONCLUSIONS

Increased IgG4-EW, IgA-EW, and IgA2-EW during eOIT are associated with clinical response to eOIT. Lower pretreatment IgE-EW and IgE-OVM are also associated with SU. Future studies are needed to evaluate and validate these potential biomarkers.

New Routes of Allergen Immunotherapy

Objectives

Allergen immunotherapy is the only cure for immunoglobulin E mediated type I respiratory allergies. Subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT) are the most common treatments. In this article, we reviewed new routes of allergen immunotherapy.

Methods

Data on alternative routes to allow intralymphatic immunotherapy (ILIT), epicutaneous immunotherapy (EPIT), local nasal immunotherapy (LNIT), oral immunotherapy (OIT), and oral mucosal immunotherapy (OMIT) were gathered from the literature and were discussed.

Results

ILIT features direct injection of allergens into lymph nodes. ILIT may be clinically effective after only a few injections and induces allergen-specific immunoglobulin G, similarly to SCIT. A limitation of ILIT is that intralymphatic injections are required. EPIT features allergen administration by using patches mounted on the skin. EPIT seeks to target epidermal antigen–presenting Langerhans cells rather than mast cells or the vasculature; this should reduce both local and systemic adverse effects. LNIT involves the spraying of allergen extracts into the nasal cavity. Natural or chemically modified allergens (the latter, termed allergoids, lack immunoglobulin E reactivity) are prepared in a soluble form. OIT involves the regular administration of small amounts of a food allergen by mouth and commences with low oral doses, which are then increased as tolerance develops. OMIT seeks to deliver allergenic proteins to an expanded population of Langerhans cells in the mucosa of the oral cavity.

Conclusions

ILIT, EPIT, LNIT, OIT, and OMIT are new routes for allergen immunotherapy. They are safe and effective.

Oral immunotherapy with low allergenic hydrolysed egg in egg allergic children

BACKGROUND

A major drawback of oral immunotherapy for food allergy is the possibility of severe side-effects. We assessed both safety and efficacy of a low allergenic hydrolysed egg (HydE) preparation used in a double-blind placebo-controlled randomized study in egg allergic children.

METHODS

In a pilot multicentre study, 29 egg allergic patients (aged 1-5.5 years) were administered daily for 6 months 9 g HydE or placebo in a blinded, randomized manner. Safety was verified by oral food challenge to assess tolerance towards HydE at the start and efficacy by an open oral food challenge (OFC, primary outcome) at the end. Additionally, changes in basophil activation and specific IgE and IgG4 were assessed.

RESULTS

All egg allergic patients randomized to HydE (n = 15) tolerated the full dose at day 1 and received the maintenance dose from the start at home. No statistically significant difference was observed on the final OFC (36% and 21% had a negative OFC in the treatment and placebo groups, respectively). Specific IgG4 levels increased, while both CD203c+ and CD63+ basophils decreased significantly more over time in the treatment than in the placebo group.

CONCLUSIONS

HydE can be regarded as a safe, low allergenic product to use in children allergic to egg. Although not significant, HydE given for 6 months increased numerically the proportion of patients becoming tolerant to egg. HydE induced a modulation of the immune response towards better tolerance. A longer treatment period and/or a higher dose may improve the clinical outcome and should be evaluated.

Changes in biomarkers during a six-month oral immunotherapy intervention for cow's milk allergy

AIM

Oral immunotherapy (OIT) is a promising but still experimental method to treat children with cow's milk (CM) allergy (CMA). We evaluated changes in allergic, immunological and inflammatory parameters, which happened during the six-month OIT for CMA.

METHODS

We treated 28 school-aged children with CMA using OIT with a double-blind placebo-controlled design. After the controlled study finished, the placebo group was treated with the same but open-label OIT protocol. Sixteen immune variables were tested before and after the six-month OIT.

RESULTS

Before OIT, the median serum CM-specific immunoglobulin (Ig) E was 18.0kIU/L in the intervention group and 9.4kIU/L in the placebo group (p = 0.46). At six months, interleukin (IL)-6 and IL-10 were significantly higher in the intervention group. When the changes during the blinded and open OIT were analysed together for both groups, blood eosinophils and serum total IgE decreased and milk-specific IgG and IgG4, serum IL-4 and IL-6, and serum leptin and resistin increased significantly.

CONCLUSION

Preliminary evidence was found that markers of allergy such as blood eosinophils and serum IgE decreased and milk-specific IgG and IgG4 increased during OIT. Adipokines, leptin and resistin, which functionally are cytokines linked to Th1-type response, increased during OIT.

Epicutaneous immunotherapy for the treatment of peanut allergy in children and young adults

BACKGROUND

Peanut allergy is common, life-threatening, and without therapeutic options. We evaluated peanut epicutaneous immunotherapy (EPIT) by using Viaskin Peanut for peanut allergy treatment.

OBJECTIVE

We sought to evaluate the clinical, safety, and immunologic effects of EPIT for the treatment of peanut allergy.

METHODS

In this multicenter, double-blind, randomized, placebo-controlled study, 74 participants with peanut allergy (ages 4-25 years) were treated with placebo (n = 25), Viaskin Peanut 100 μg (VP100; n = 24) or Viaskin Peanut 250 μg (VP250; n = 25; DBV Technologies, Montrouge, France). The primary outcome was treatment success after 52 weeks, which was defined as passing a 5044-mg protein oral food challenge or achieving a 10-fold or greater increase in successfully consumed dose from baseline to week 52. Adverse reactions and mechanistic changes were assessed.

RESULTS

At week 52, treatment success was achieved in 3 (12%) placebo-treated participants, 11 (46%) VP100 participants, and 12 (48%) VP250 participants (P = .005 and P = .003, respectively, compared with placebo; VP100 vs VP250, P = .48). Median change in successfully consumed doses were 0, 43, and 130 mg of protein in the placebo, VP100, and VP250 groups, respectively (placebo vs VP100, P = .014; placebo vs VP250, P = .003). Treatment success was higher among younger children (P = .03; age, 4-11 vs >11 years). Overall, 14.4% of placebo doses and 79.8% of VP100 and VP250 doses resulted in reactions, predominantly local patch-site and mild reactions (P = .003). Increases in peanut-specific IgG₄ levels and IgG₄/IgE ratios were observed in peanut EPIT-treated participants, along with trends toward reduced basophil activation and peanut-specific T_H2 cytokines.

CONCLUSIONS

Peanut EPIT administration was safe and associated with a modest treatment response after 52 weeks, with the highest responses among younger children. This, when coupled with a high adherence and retention rate and significant changes in immune pathways, supports further investigation of this novel therapy.

Heated egg yolk challenge predicts the natural course of hen's egg allergy: a retrospective study

BACKGROUND

Children do not always outgrow hen's egg allergies in early childhood. Because egg yolks are less allergenic than egg whites, we performed an oral food challenge with heated egg yolk slightly contaminated with egg white (EYSEW OFC) in infants allergic to hen's egg. We hypothesized that the EYSEW OFC results would predict the egg allergy's natural course.

METHODS

We retrospectively reviewed participants with hen's egg allergy who underwent their first EYSEW OFC at 12-23 months of age between 2004 and 2010. Participants who passed the first EYSEW OFC were defined as EYSEW-tolerant, and participants who failed the OFC were defined as EYSEW-reactive. Participants who passed the EYSEW OFC underwent an OFC with half of a heated whole egg (WE OFC). Participants who passed a WE OFC were defined to be heated hen's egg-tolerant. Participants who failed the EYSEW OFC or the WE OFC underwent another OFC at least 6 months later. We compared tolerance to heated hen's egg at 36 months after the first EYSEW OFC between EYSEW-tolerant and EYSEW-reactive participants. Univariate and multivariate logistic regression analyses were conducted.

RESULTS

Of the 197 included participants (median age: 18.3 months; range: 12.1-23.8 months), 179 (90.9 %) were EYSEW tolerant and 18 (9.1 %) were EYSEW reactive. At 36 months after the first EYSEW OFC, 164 EYSEW-tolerant (91.6 %) and 12 EYSEW-reactive participants (66.7 %) achieved heated hen's egg tolerance. In the univariate logistic regression analyses, EYSEW-reactive participants (crude odds ratio [OR], 5.5 [95 % confidence intervals [CI], 1.8-16.6]; p = 0.003) and those with baseline egg white sIgE levels (crude OR: 3.9 per ten-fold increase [95 % CI, 1.5-10.2]; p = 0.005) had greater odds of persistent allergy to hen's egg at 36 months after the first EYSEW OFC. In a multivariate logistic regression analysis after adjustment for baseline egg white sIgE, EYSEW-reactive participants had greater odds of persistent allergy to hen's egg than EYSEW-tolerant participants (adjusted OR: 4.6 [95 % CI, 1.5-15.0]; p = 0.003).

CONCLUSIONS

Classifying infants who are allergic to hen's egg into EYSEW tolerant and EYSEW reactive groups was useful in determining prognosis.

Active treatment for food allergy

Food allergy has grown in rapidly in prevalence, currently affecting 5% of adults and 8% of children. Management strategy is currently limited to 1) food avoidance and 2) carrying and using rescue intramuscular epinephrine/adrenaline and oral antihistamines in the case of accidental ingestion; there is no FDA approved treatment. Recently, oral, sublingual and epicutaneous immunotherapy have been developed as active treatment of food allergy, though none have completed phase 3 study. Efficacy and safety studies of immunotherapy have been variable, though there is clearly signal that immunotherapy will be a viable option to desensitize patients. The use of bacterial adjuvants, anti-IgE monoclonal antibodies, and Chinese herbal formulations either alone or in addition to immunotherapy may hold promise as future options for active treatment. Active prevention of food allergy through early introduction of potentially offending foods in high-risk infants will be an important means to slow the rising incidence of sensitization.

Markers of tolerance development to food allergens

IgE-mediated reactions to food allergens are the most common cause of anaphylaxis in childhood. Although allergies to cow's milk, egg, or soy proteins, in contrast to peanut and tree nut allergens, resolve within the first 6 years of life in up to 60% due to natural tolerance development, this process is not well understood. At present, there is no cure or treatment for food allergy that would result in an induction of tolerance to the symptom-eliciting food. Avoidance, providing an emergency plan and education, is the standard of treatment. Oral immunotherapeutic approaches have been proven reasonable efficacy; however, they are associated with high rates of side-effects and low numbers of patients achieving tolerance. Nevertheless, mechanisms that take place during oral immunotherapy may help to understand tolerance development. On the basis of these therapeutic interventions, events like loss of basophil activation and induction of regulatory lymphocyte subsets and of blocking antibodies have been described. Their functional importance at a clinical level, however, remains to be investigated in detail. Consequently, there is eminent need to understand the process of tolerance development to food allergens and define biomarkers to develop and monitor new treatment strategies for food allergy.

Food Allergy: Our Evolving Understanding of Its Pathogenesis, Prevention, and Treatment

Food allergy is defined as an IgE-mediated hypersensitivity response to ingested food with allergic symptoms ranging from urticaria to life-threatening anaphylaxis. Food allergy is thought to develop because of (1) failed induction of tolerance upon initial exposure to food antigen or (2) breakdown of established tolerance to food antigen. We review current understanding of the pathogenesis, epidemiology, and natural history of food allergy, including the unconventional IgE-mediated food allergy to mammalian meat known as alpha-gal food allergy. We highlight emerging data on food allergy treatment and prevention, emphasizing the growing appeal of manipulating the gut microenvironment using probiotics and helminth products to blunt systemic allergic responses to food.

pH and heat induced structural changes of chicken ovalbumin in relation with antigenic properties

Ovalbumin is the major egg white protein known to induce allergic reactions in humans. A comprehensive evaluation of the structural and antigenicity features of ovalbumin subjected to different pH and heat treatments was performed by combining fluorescence spectroscopic measurements, ELISA and in silico prediction. The intrinsic fluorescence spectra indicated modification of the ovalbumin tertiary structure depending on pH and applied temperature. The heat treatment caused the alteration of ovalbumin structure, which exhibited gradual hydrophobic exposure. The in depths check of ovalbumin molecular model, after performing molecular dynamics simulations, indicated the slight transition toward a typical β-strand dominant structure with the temperature increase. Moreover the immunoenzymatic test was employed to estimate the effect of the pH and thermal treatment on the stability of ovalbumin epitopes. Only a 5.5% reduction of the residual antigenicity was observed when heat treating the ovalbumin samples at pH 7.0, whereas a significant reduction (over 82%) of the antigenicity was obtained at pH 9.5 and temperatures over 80°C. Both pH and thermal treatment affected the conformation of ovalbumin. The reduced recognition of the modified native ovalbumin by specific antibodies at alkaline pH is most probably a consequence of significant changes in the local conformation of the epitopes.

Oral Immunotherapy for Food Allergy

Food allergy is a potentially life-threatening condition with no approved therapies, apart from avoidance and injectable epinephrine for acute allergic reactions. Oral immunotherapy (OIT) is an experimental treatment in which food-allergic patients consume gradually increasing quantities of the food to increase their threshold for allergic reaction. This therapy carries significant risk of allergic reactions. The ability of OIT to desensitize patients to particular foods is well-documented, although the ability to induce tolerance has not been established. This review focuses on recent studies for the treatment of food allergies such as cow's milk, hen's egg, and peanut.

Omalizumab facilitates rapid oral desensitization for peanut allergy

BACKGROUND

Peanut oral immunotherapy is a promising approach to peanut allergy, but reactions are frequent, and some patients cannot be desensitized. The anti-IgE medication omalizumab (Xolair; Genentech, South San Francisco, Calif) might allow more rapid peanut updosing and decrease reactions.

OBJECTIVE

We sought to evaluate whether omalizumab facilitated rapid peanut desensitization in highly allergic patients.

METHODS

Thirty-seven subjects were randomized to omalizumab (n = 29) or placebo (n = 8). After 12 weeks of treatment, subjects underwent a rapid 1-day desensitization of up to 250 mg of peanut protein, followed by weekly increases up to 2000 mg. Omalizumab was then discontinued, and subjects continued on 2000 mg of peanut protein. Subjects underwent an open challenge to 4000 mg of peanut protein 12 weeks after stopping study drug. If tolerated, subjects continued on 4000 mg of peanut protein daily.

RESULTS

The median peanut dose tolerated on the initial desensitization day was 250 mg for omalizumab-treated subjects versus 22.5 mg for placebo-treated subject. Subsequently, 23 (79%) of 29 subjects randomized to omalizumab tolerated 2000 mg of peanut protein 6 weeks after stopping omalizumab versus 1 (12%) of 8 receiving placebo (P < .01). Twenty-three subjects receiving omalizumab versus 1 subject receiving placebo passed the 4000-mg food challenge. Overall reaction rates were not significantly lower in omalizumab-treated versus placebo-treated subjects (odds ratio, 0.57; P = .15), although omalizumab-treated subjects were exposed to much higher peanut doses.

CONCLUSION

Omalizumab allows subjects with peanut allergy to be rapidly desensitized over as little as 8 weeks of peanut oral immunotherapy. In the majority of subjects, this desensitization is sustained after omalizumab is discontinued. Additional studies will help clarify which patients would benefit most from this approach.