Oral immunotherapy for treatment of egg allergy in children

Safety, clinical, and immunologic efficacy of a Chinese herbal medicine (Food Allergy Herbal Formula-2) for food allergy

BACKGROUND

Food Allergy Herbal Formula-2 (FAHF-2) is a 9-herb formula based on traditional Chinese medicine that blocks peanut-induced anaphylaxis in a murine model. In phase I studies FAHF-2 was found to be safe and well tolerated.

OBJECTIVE

We sought to evaluate the safety and effectiveness of FAHF-2 as a treatment for food allergy.

METHODS

In this double-blind, randomized, placebo-controlled study 68 subjects aged 12 to 45 years with allergies to peanut, tree nut, sesame, fish, and/or shellfish, which were confirmed by baseline double-blind, placebo-controlled oral food challenges (DBPCFCs), received FAHF-2 (n = 46) or placebo (n = 22). After 6 months of therapy, subjects underwent DBPCFCs. For those who demonstrated increases in the eliciting dose, a repeat DBPCFC was performed 3 months after stopping therapy.

RESULTS

Treatment was well tolerated, with no serious adverse events. By using intent-to-treat analysis, the placebo group had a higher eliciting dose and cumulative dose (P = .05) at the end-of-treatment DBPCFC. There was no difference in the requirement for epinephrine to treat reactions (P = .55). There were no significant differences in allergen-specific IgE and IgG4 levels, cytokine production by PBMCs, or basophil activation between the active and placebo groups. In vitro immunologic studies performed on subjects' baseline PBMCs incubated with FAHF-2 and food allergen produced significantly less IL-5, greater IL-10 levels, and increased numbers of regulatory T cells than untreated cells. Notably, 44% of subjects had poor drug adherence for at least one third of the study period.

CONCLUSION

FAHF-2 is a safe herbal medication for subjects with food allergy and shows favorable in vitro immunomodulatory effects; however, efficacy for improving tolerance to food allergens is not demonstrated at the dose and duration used.

Food Allergy: Common Causes, Diagnosis, and Treatment

Food allergy is a growing concern, and recognition of symptoms, knowledge of common food allergens, and management of reactions are important for patients and practitioners. Symptoms of a classic IgE-mediated food allergy vary in severity and can include any combination of laryngeal edema, wheezing, nausea, vomiting, diarrhea, urticaria, angioedema, and hypotension. Many foods can induce an allergic reaction, but the most commonly implicated foods include cow's milk, egg, peanut, tree nut, soy, wheat, fish, and shellfish. Milk and egg allergy generally develop and are outgrown in childhood. Peanut and tree nut allergy can occur during childhood or adulthood, are less likely to be outgrown, and tend to cause more fatal reactions. Given the possibility of life-threatening reactions, it is important to recognize the potential for cross-reactivity among food groups. Diagnosis of food allergy includes skin prick testing, specific serum IgE testing, and oral food challenges. Management is centered on avoidance of allergenic and cross-reacting foods and early recognition and immediate treatment of reactions. Treatment protocols to desensitize patients to food are currently under investigation.

Is clinical tolerance possible after allergen immunotherapy?

There is a growing evidence that allergen immunotherapy (AIT) can provide significant and long-lasting clinical benefit for a number of allergic individuals. However, it is less clear if AIT results in clinical tolerance, which is characterized by a persistent state of clinical non-reactivity to allergens after therapy is finished. Addressing this knowledge gap is particularly relevant for patients undergoing AIT for food allergies, as anything less than complete tolerance could have potentially devastating consequences. An increasing number of studies, in particular those involving oral immunotherapy, are attempting to assess tolerance induction following AIT. Clinical tolerance does appear to be achievable in a subset of patients undergoing AIT, but whether this is equivalent to the type of tolerance observed in nonallergic individuals remains unknown. Developing established criteria for assessing tolerance induction, as well as the use of consistent terminology when describing clinical tolerance, will be important for determining the disease-modifying potential of AIT.

Oral immunotherapy for food allergy: mechanisms and role in management

With the emergence of food allergy as an important public health problem, it has become clear that there is an unmet need in regard to treatment. In particular, IgE-mediated food allergy that is associated with risk of fatal anaphylaxis has been the subject of multiple studies in the past decade. The growing body of evidence derived from multiple centres and various study designs indicates that for IgE-mediated food allergy, immunomodulation through food immunotherapy is possible; however, the extent of protection afforded by such treatment is highly variable. At this time, the capacity for food immunotherapy to restore permanent tolerance to food has not been demonstrated conclusively. This review will discuss these topics as they apply to the most important studies of food oral immunotherapy.

IgE receptor signaling in food allergy pathogenesis

The pathogenesis of food allergy remains poorly understood. Recent advances in the use of murine models have led to discoveries that mast cells and IgE receptor signaling not only drive immediate hypersensitivity reactions but also exert an immunoregulatory function, promoting the development of allergic sensitivity to foods. We review the evidence that IgE, IgE receptors, key signaling kinases and mast cells impair oral tolerance to ingested foods, preventing the induction of regulatory T cells (Treg) and promoting the acquisition of pro-allergic T helper (Th) 2 responses. We discuss innovative strategies that that could be implemented to counteract these immunoregulatory effects of IgE-mediated mast cell activation, and potentially reverse established sensitization, curing food allergy.

Current opinion and review on peanut oral immunotherapy

In the last decade, peanut oral immunotherapy research has shown promise as an alternative treatment to avoidance in peanut-allergic patients. Research has not only focused on desensitization, but also on immunologic changes and sustained-tolerance. This article reviews the current literature and the historical background of oral immunotherapy as well as immune mechanisms in oral immunotherapy and other therapies being explored in food allergic individuals.

Recent advances in immunotherapy and vaccine development for peanut allergy

Peanut allergy is a common problem and can be the cause of severe, life-threatening allergic reactions. It rarely resolves, with the majority of patients carrying the disease onto adulthood. Peanut allergy poses a significant burden on the quality of life of sufferers and their families, which results mainly from the fear of accidental peanut ingestion, but is also due to dietary and social restrictions. Current standard management involves avoidance, patient education and provision of emergency medication, for use in allergic reactions, when they occur. Efforts have been made to develop a vaccine for peanut allergy. Recent developments have also highlighted the use of immunotherapy, which has shown promise as an active form of treatment and may present a disease-modifying therapy for peanut allergy. So far, results, especially from oral immunotherapy studies, have shown good efficacy in achieving desensitization to peanut with a good safety profile. However, the capacity to induce long-term tolerance has not been demonstrated conclusively yet and larger, phase III studies are required to further investigate safety and efficacy of this intervention. Peanut immunotherapy is not currently recommended for routine clinical use or outside specialist allergy units.

Japanese cedar pollen-based subcutaneous immunotherapy decreases tomato fruit-specific basophil activation

BACKGROUND

Some patients with Japanese cedar pollen (JCP)-induced allergic rhinitis develop pollen-food allergy syndrome (PFAS) as a reaction to tomato fruit. Pollen allergen-specific subcutaneous immunotherapy (SCIT) is reportedly beneficial for some associated food allergies; however, the reported changes in food allergen-specific immunoglobulin (Ig)E and IgG4 levels are inconsistent. Here, we investigated immunologic reactivity to tomato fruit after JCP-based SCIT.

METHODS

Twenty-three children (aged 6-17 years) with JCP-induced allergic rhinitis and sensitized to tomato (serum tomato fruit-specific IgE level >0.34 UA/ml) received JCP-based SCIT. Basophil activation by tomato and JCP extracts and serum-specific IgE and IgG4 levels against these allergens were determined before and after 4 or 5 months of maintenance SCIT. Basophil activation was assessed by monitoring CD203c upregulation on flow cytometry.

RESULTS

JCP-based SCIT significantly reduced the basophil activation caused by tomato fruit (p = 0.03) and JCP (p < 0.001) extracts. JCP-specific IgG4 levels markedly increased after SCIT (p < 0.001), whereas tomato fruit-specific IgG4 levels did not. After SCIT, no significant changes were observed in specific IgE levels for tomato fruit (p = 0.11) or JCP (p = 0.19).

CONCLUSIONS

Tomato fruit-specific basophil activation decreases after JCP-based SCIT, suggesting that it is efficacious in relieving and preventing the symptoms of PFAS in patients with JCP-induced allergic rhinitis.

Pharmacologic options for the treatment and management of food allergy

Food allergy affects approximately 5% of adults and 8% of children in developed countries, and there is currently no cure. Current pharmacologic management is limited to using intramuscular epinephrine or oral antihistamines in response to food allergen exposure. Recent trials have examined the efficacy and safety of subcutaneous, oral, sublingual, and epicutaneous immunotherapy, with varying levels of efficacy and safety demonstrated. Bacterial adjuvants, use of anti-IgE monoclonal antibodies, and Chinese herbal formulations represent exciting potential for development of future pharmacotherapeutic agents. Ultimately, immunotherapy may be a viable option for patients with food allergy, although efficacy and safety are likely to be less than ideal.

High IgE levels to α-lactalbumin, β-lactoglobulin and casein predict less successful cow's milk oral immunotherapy

BACKGROUND

A new treatment option for persistent cow's milk allergy (CMA) is oral immunotherapy (OIT). Not all patients develop tolerance during therapy, and markers to identify those who will benefit from it are needed. The objective was to study the IgE and IgG4 antibody profiles to milk and milk proteins before and after OIT in relation to clinical outcome.

METHODS

Seventy-six children (5-17 years) with challenge-verified CMA were subjected to a 6-month OIT protocol. The treatment aimed at reaching a maintenance dose of 200 ml CM (high dose = HD). Those who did not reach target were analysed as a low-dose (LD) group. Sera were characterized before and after OIT regarding serum levels of IgE and IgG4 to milk and five milk allergen components evaluated together with clinical CMA symptoms and outcome of OIT.

RESULTS

Fifty-five (72%) patients reached the maintenance dose (HD) during therapy. High specific IgE levels towards the milk allergens α-lactalbumin (P = 0.048), β-lactoglobulin (P = 0.006) and casein (P = 0.015) before OIT start were associated with lower maintenance dose reached. Patients who developed desensitization had a larger increase in IgG4 levels to α-lactalbumin (P = 0.034), β-lactoglobulin (P = 0.010), casein (P = 0.047) and lactoferrin (P = 0.030) during treatment than those who failed.

CONCLUSIONS

Component-resolved diagnostics before OIT can help to identify children with lower probability of a successful OIT outcome, as high IgE levels to α-lactalbumin, β-lactoglobulin and casein are associated with lower maintenance dose reached. An increase in the IgG4 concentration to milk components during treatment indicated effective desensitization.

New developments in immunotherapies for food allergy

Food allergy affects around 10% of the population. As the prevalence of food allergy continues to increase, disproportionately in children, new therapies for food allergy are being investigated. While there are no approved treatments for food allergy, immunotherapy facilitates significant desensitization and protection from accidental exposure. Nevertheless, current immunotherapies do not entirely nor permanently eliminate sensitivity to the food allergen. Since the rates of sustained unresponsiveness are significantly lower than desensitization, future therapies that enhance the rates of long-term tolerance in patients will catalyze progress in this field over the next 5–10 years.

Efficacy of baked milk oral immunotherapy in baked milk-reactive allergic patients

BACKGROUND

Patients with IgE-mediated cow's milk allergy who are nonreactive to baked milk (BM) can be desensitized with BM to promote tolerance to unheated milk (UM).

OBJECTIVE

We sought to test whether patients who are BM reactive can progress in BM oral immunotherapy (OIT) and become desensitized to UM as well.

METHODS

Fifteen patients (>4 years) who previously failed to complete our milk OIT program were enrolled into the BM OIT protocol. A dose of BM (180 °C for 30 minutes) which was less than the eliciting dose was increased 50% monthly while under medical supervision until the primary outcome dose of 1.3 g/d BM protein was achieved. Basophil reactivity and milk protein-specific IgE binding were analyzed at the first round of BM OIT therapy (T0) and at 12 months of BM treatment.

RESULTS

In terms of the primary outcome, only 3 (21%) of 14 patients tolerated the 1.3 g/d BM dose. Although some patients initially progressed in BM OIT, 8 of 11 failed because of IgE-mediated reactions. Three did not complete the program because of non-IgE-mediated factors. An increase in challenge threshold to UM was noted in patients continuing until 12 months (P = .003), including those among whom reactions precluded continuation in the program. Patients (n = 3) who successfully reached maintenance had decreased milk-specific IgE reactivity. Furthermore, the mean difference at T0 between induced HM and UM percentages of CD203c expression was significantly lower in patients who successfully completed BM OIT than in those who did not (-11% vs 4.4%, P = .0002), which is consistent with their decreased clinical reactivity to BM.

CONCLUSIONS

Although use of hypoallergenic BM in OIT is a promising therapy, care must be taken before its administration in BM-reactive patients because of the risk for anaphylaxis and only limited increase in challenge threshold attained.

Oral immunotherapy for the treatment of food allergy

Oral immunotherapy (OIT) is an emerging new therapy for food allergy. With multiple small exploratory trials and some large randomized-controlled phase 2 trials recently published and under way, there is a clear progress and interest toward making this a treatment option for patients suffering from food allergies. However, there are still many questions to be answered and parameters to fine-tune before OIT becomes an accepted option outside of the research setting. This review covers the main milestones in the development of OIT for food allergy and further discusses important specific issues that will have direct impact on its clinical application. More specifically, previous publications showing evidence for the induction of tolerance are specifically reviewed and varying safety, tolerability and efficacy parameters from previous reports are also discussed.

Oral immunotherapy and anti-IgE antibody treatment for food allergy

Food allergy is a major public health problem affecting nearly 10 % of children in most industrialized countries. Unfortunately, there are no effective therapies for food allergy, relegating patients to simply avoid the offending foods and treat reactions that occur on accidental exposure. Recently however, studies suggest that food immunotherapy may provide a promising new approach to food allergy, particularly using the oral form of immunotherapy (OIT). Enthusiasm for this approach though must be tempered because of the significant allergic reactions that often occur with OIT that tends to limit its use to patients with less severe disease. On the other hand, recent studies suggest that concomitant treatment of patients with omalizumab (anti-IgE monoclonal antibody) during the updosing phase of OIT may greatly reduce the allergic reactions associated with OIT, even in high-risk patients. This combined method may provide a novel approach to successfully and rapidly treat a large fraction of patients with high-risk food allergy.

Single B-cell deconvolution of peanut-specific antibody responses in allergic patients

BACKGROUND

The frequencies, cellular phenotypes, epitope specificity, and clonal diversity of allergen-specific B cells in patients with food allergy are not fully understood but are of major pathogenic and therapeutic significance.

OBJECTIVE

We sought to characterize peanut allergen-specific B-cell populations and the sequences and binding activities of their antibodies before and during immunotherapy.

METHODS

B cells binding fluorescently labeled Ara h 1 or Ara h 2 were phenotyped and isolated by means of flow cytometric sorting from 18 patients at baseline and 13 patients during therapy. Fifty-seven mAbs derived from allergen-binding single B cells were evaluated by using ELISA, Western blotting, and peptide epitope mapping. Deep sequencing of the B-cell repertoires identified additional members of the allergen-specific B-cell clones.

RESULTS

Median allergen-binding B-cell frequencies were 0.0097% (Ara h 1) or 0.029% (Ara h 2) of B cells in baseline blood from allergic patients and approximately 3-fold higher during immunotherapy. Five of 57 allergen-specific cells belonged to clones containing IgE-expressing members. Almost all allergen-specific antibodies were mutated, and binding to both conformational and linear allergen epitopes was detected. Increasing somatic mutation of IgG4 members of a clone was seen in immunotherapy, whereas IgE mutation levels in the clone did not increase.

CONCLUSION

Most peanut allergen-binding B cells isolated by means of antigen-specific flow sorting express mutated and isotype-switched antibodies. Immunotherapy increases their frequency in the blood, and even narrowly defined allergen epitopes are recognized by numerous distinct B-cell clones in a patient. The results also suggest that oral immunotherapy can stimulate somatic mutation of allergen-specific IgG4.

The role of epigenetic mediation and the future of food allergy research

IgE-mediated food allergy is a developing global health problem with prevalence rising at alarmingly fast rates. In this review, we discuss the interplay between genetics, epigenetics, and environmental exposures in the pathogenesis of food allergies. We aim to highlight the most recent evidence that suggests how epigenetic control may mediate genetic susceptibility of food allergies. We also examine how epigenetic modifications may be the key in explaining how environmental factors modulate and modify gene expression, leading to the dysregulation of immune tolerance and consequently, the development of food allergies. The emerging epigenetic paradigm in food allergies is likely to provide new mechanistic insight into food allergy risk and development as well as shape our therapeutic and preventive strategies.

Peanut oral immunotherapy transiently expands circulating Ara h 2-specific B cells with a homologous repertoire in unrelated subjects

BACKGROUND

Peanut oral immunotherapy (PNOIT) induces persistent tolerance to peanut in a subset of patients and induces specific antibodies that might play a role in clinical protection. However, the contribution of induced antibody clones to clinical tolerance in PNOIT is unknown.

OBJECTIVE

We hypothesized that PNOIT induces a clonal, allergen-specific B-cell response that could serve as a surrogate for clinical outcomes.

METHODS

We used a fluorescent Ara h 2 multimer for affinity selection of Ara h 2-specific B cells and subsequent single-cell immunoglobulin amplification. The diversity of related clones was evaluated by means of next-generation sequencing of immunoglobulin heavy chains from circulating memory B cells with 2x250 paired-end sequencing on the Illumina MiSeq platform.

RESULTS

Expression of class-switched antibodies from Ara h 2-positive cells confirms enrichment for Ara h 2 specificity. PNOIT induces an early and transient expansion of circulating Ara h 2-specific memory B cells that peaks at week 7. Ara h 2-specific sequences from memory cells have rates of nonsilent mutations consistent with affinity maturation. The repertoire of Ara h 2-specific antibodies is oligoclonal. Next-generation sequencing-based repertoire analysis of circulating memory B cells reveals evidence for convergent selection of related sequences in 3 unrelated subjects, suggesting the presence of similar Ara h 2-specific B-cell clones.

CONCLUSIONS

Using a novel affinity selection approach to identify antigen-specific B cells, we demonstrate that the early PNOIT-induced Ara h 2-specific B-cell receptor repertoire is oligoclonal and somatically hypermutated and shares similar clonal groups among unrelated subjects consistent with convergent selection.

A Web site-based reporting system for monitoring home treatment during oral immunotherapy for food allergy

BACKGROUND

Reactions during the home treatment phase of oral immunotherapy (OIT) are not uncommon. An ongoing accurate reporting of home treatment outcomes is crucial for the safety and success of OIT. Previous reports have shown that as few as 20% of patients are truly compliant with paper-based diaries.

OBJECTIVE

To develop a Web site-based electronic reporting system (web-RS) for monitoring home treatment during OIT for food allergy.

METHODS

A web-RS was developed and incorporated a thorough questionnaire querying for pertinent data including the dose(s) consumed, occurrence and details of adverse reactions, treatment(s), and relevant potential exacerbating factors. All patients enrolled in milk, peanut, or egg OIT programs for at least 4 weeks from November 2012 through January 2014 were introduced to web-RS (n = 157). Successful reporting through web-RS was defined by consecutive reporting during the first home treatment phase (24 days) after its introduction. Comparisons were made with a previous group of OIT-treated patients (n = 100) who reported by E-mail.

RESULTS

Successful reporting was achieved by 142 of 157 patients (90.44%) in contrast to a 75% success rate with E-mail (P = .0009). The odds for successful reporting using web-RS were 3.1 (95% confidence interval 1.6-6.3) times higher compared with using E-mail. Mild reactions were reported more frequently with web-RS (P = .0032). Patient reports were constantly available in real time for medical staff review. No complaints regarding web-RS feasibility were reported. One risk factor for failure to use web-RS was a patient's prior successful OIT experience without using web-RS (P = .012).

CONCLUSION

A web-RS can be a powerful tool for improving OIT safety by achieving a high level of patient cooperation in reporting home treatment results.

Diagnosis, management, and investigational therapies for food allergies

Food allergies have increased in prevalence over the past 20 years, now becoming an important public health concern. Although there are no therapies currently available for routine clinical care, recent reports have indicated that immunotherapies targeting the mucosal immune system may be effective. Oral immunotherapy is conducted by administering small, increasing amounts of food allergen; it has shown promise for desensitizing individuals with peanut, egg, or milk allergies. Sublingual immunotherapy also desensitizes allergic patients to foods-2 major studies have examined the effects of sublingual immunotherapy in subjects with peanut allergies. We review the complex nature of IgE-mediated food allergies and the therapies being evaluated in clinical trials. We focus on the diagnosis and management of food allergies and investigational therapies.

Food allergies: the basics

IgE-associated food allergy affects approximately 3% of the population and has severe effects on the daily life of patients-manifestations occur not only in the gastrointestinal tract but also affect other organ systems. Birth cohort studies have shown that allergic sensitization to food allergens develops early in childhood. Mechanisms of pathogenesis include cross-linking of mast cell- and basophil-bound IgE and immediate release of inflammatory mediators, as well as late-phase and chronic allergic inflammation, resulting from T-cell, basophil, and eosinophil activation. Researchers have begun to characterize the molecular features of food allergens and have developed chip-based assays for multiple allergens. These have provided information about cross-reactivity among different sources of food allergens, identified disease-causing food allergens, and helped us to estimate the severity and types of allergic reactions in patients. Importantly, learning about the structure of disease-causing food allergens has allowed researchers to engineer synthetic and recombinant vaccines.

Suppression of the immunologic response to peanut during immunotherapy is often transient

BACKGROUND

Studies suggest that oral immunotherapy (OIT) and sublingual immunotherapy (SLIT) for food allergy hold promise; however, the immunologic mechanisms underlying these therapies are not well understood.

OBJECTIVE

We sought to generate insights into the mechanisms and duration of suppression of immune responses to peanut during immunotherapy.

METHODS

Blood was obtained from subjects at baseline and at multiple time points during a placebo-controlled trial of peanut OIT and SLIT. Immunologic outcomes included measurement of spontaneous and stimulated basophil activity by using automated fluorometry (histamine) and flow cytometry (activation markers and IL-4), measurement of allergen-induced cytokine expression in dendritic cell (DC)-T-cell cocultures by using multiplexing technology, and measurement of MHC II and costimulatory molecule expression on DCs by using flow cytometry.

RESULTS

Spontaneous and allergen-induced basophil reactivity (histamine release, CD63 expression, and IL-4 production) were suppressed during dose escalation and after 6 months of maintenance dosing. Peanut- and dust mite-induced expression of TH2 cytokines was reduced in DC-T-cell cocultures during immunotherapy. This was associated with decreased levels of CD40, HLA-DR, and CD86 expression on DCs and increased expression of CD80. These effects were most striking in myeloid DC-T-cell cocultures from subjects receiving OIT. Many markers of immunologic suppression reversed after withdrawal from immunotherapy and in some cases during ongoing maintenance therapy.

CONCLUSION

OIT and SLIT for peanut allergy induce rapid suppression of basophil effector functions, DC activation, and TH2 cytokine responses during the initial phases of immunotherapy in an antigen-nonspecific manner. Although there was some interindividual variation, in many patients suppression appeared to be temporary.

A randomized, double-blind, placebo-controlled pilot study of sublingual versus oral immunotherapy for the treatment of peanut allergy

BACKGROUND

Although promising results have emerged regarding oral immunotherapy (OIT) and sublingual immunotherapy (SLIT) for the treatment of peanut allergy (PA), direct comparisons of these approaches are limited.

OBJECTIVE

This study was conducted to compare the safety, efficacy, and mechanistic correlates of peanut OIT and SLIT.

METHODS

In this double-blind study children with PA were randomized to receive active SLIT/placebo OIT or active OIT/placebo SLIT. Doses were escalated to 3.7 mg/d (SLIT) or 2000 mg/d (OIT), and subjects were rechallenged after 6 and 12 months of maintenance. After unblinding, therapy was modified per protocol to offer an additional 6 months of therapy. Subjects who passed challenges at 12 or 18 months were taken off treatment for 4 weeks and rechallenged.

RESULTS

Twenty-one subjects aged 7 to 13 years were randomized. Five discontinued therapy during the blinded phase. Of the remaining 16, all had a greater than 10-fold increase in challenge threshold after 12 months. The increased threshold was significantly greater in the active OIT group (141- vs 22-fold, P = .01). Significant within-group changes in skin test results and peanut-specific IgE and IgG4 levels were found, with overall greater effects with OIT. Adverse reactions were generally mild but more common with OIT (P < .001), including moderate reactions and doses requiring medication. Four subjects had sustained unresponsiveness at study completion.

CONCLUSION

OIT appeared far more effective than SLIT for the treatment of PA but was also associated with significantly more adverse reactions and early study withdrawal. Sustained unresponsiveness after 4 weeks of avoidance was seen in only a small minority of subjects.

Clinical efficacy and immunological changes subjacent to egg oral immunotherapy

BACKGROUND

Evidence of the efficacy of food oral immunotherapy (OIT) is not robust enough to change clinical practice from current standard management. Furthermore, the immunologic changes underlying food desensitization are unknown.

OBJECTIVE

To establish the immunologic basal status and differences between an egg-allergic group of children and a population of nonallergic children and to investigate the safety and efficacy of a specific egg OIT protocol to induce clinical desensitization and the associated immune responses.

METHODS

Children with or without egg allergy were recruited. Allergic subjects underwent an OIT protocol based on weekly doses of egg protein and a maintenance phase. Immune profile and changes in all subjects were investigated by measuring T-helper cells types 1 and 2 (TH1 and TH2) and T-regulatory cytokines and transcription factors and egg-specific IgE and IgG4 levels.

RESULTS

At baseline, a significantly lower production of ovalbumin-specific interleukin (IL)-10 and tumor necrosis factor-α and a trend toward higher IL-5 and IL-13 were found in allergic children. The egg OIT protocol enabled 60% of them to ingest 32 mL of egg white. Significant increases in egg-specific IgG4 levels and IL-10 production, with a trend toward lower IL-5 and IL-13 and higher tumor necrosis factor-α and interferon-γ levels, and significant decreases in egg-specific IgE concentration were observed.

CONCLUSION

Egg-allergic individuals display a bias toward TH2 type cytokine production and decreased TH1 and IL-10 responses compared with nonallergic individuals. The OIT protocol was safe and effective in inducing egg desensitization, leading to a shift in the immune profile of allergic individuals toward a nonallergic phenotype.

Safety and efficacy of a new regimen of short-term oral immunotherapy with Cry j 1-galactomannan conjugate for Japanese cedar pollinosis: a prospective, randomized, open-label study

BACKGROUND

Short-term oral immunotherapy (OIT) using the Cry j1-galactomannan conjugate for Japanese cedar pollinosis may be effective and relatively safe. However, a treatment regimen has not been established. In the present study, we examined a new OIT regimen with a build-up phase and extended the maintenance phase of OIT to the peak period of the pollen season to enhance the therapeutic effect and safety of OIT.

METHODS

A prospective, randomized, open-label trial was conducted over a period of 4 months. Participants were randomly divided into two groups. The OIT group comprised 23 subjects. The build-up phase was initiated 1 month before the expected pollen season. The maintenance phase was continued for 51 days during the peak pollen season. The control group comprised 24 subjects. The symptoms and medication score, levels of allergen-specific serum antibodies throughout the pollen season, and adverse effects with OIT were evaluated.

RESULTS

Participants receiving OIT showed significant improvements in total symptom scores, medication score, and total symptom-medication scores throughout the pollen season compared with the control group. The levels of allergen-specific serum IgG4 were significantly increased in the OIT group but not in the control group throughout the cedar pollen season. Importantly, no severe adverse effects were observed with OIT.

CONCLUSIONS

The new regimen of short-term OIT using the Cry j1-galactomannan conjugate for Japanese cedar pollinosis is effective, relatively safe and induces immune tolerance. Thus, OIT using allergen-galactomannan conjugates may provide a rapid, effective, and thus convenient immunotherapy for pollinosis instead of SLIT or SCIT.

Active management of food allergy: an emerging concept

IgE-mediated food allergies are common and currently there is no cure. Traditionally, management has relied upon patient education, food avoidance and the provision of an emergency medication plan. Despite this, food allergy can significantly impact on quality of life. Therefore, in recent years, evolving research has explored alternative management strategies. A more active approach to management is being adopted, which includes early introduction of potentially allergenic foods, anticipatory testing, active monitoring, desensitisation to food allergens and active risk management. This review will discuss these areas in turn.

Molecular evolution of hypoallergenic hybrid proteins for vaccination against grass pollen allergy

More than 10% of the population in Europe and North America suffer from IgE-associated allergy to grass pollen. In this article, we describe the development of a vaccine for grass pollen allergen-specific immunotherapy based on two recombinant hypoallergenic mosaic molecules, designated P and Q, which were constructed out of elements derived from the four major timothy grass pollen allergens: Phl p 1, Phl p 2, Phl p 5, and Phl p 6. Seventeen recombinant mosaic molecules were expressed and purified in Escherichia coli using synthetic genes, characterized regarding biochemical properties, structural fold, and IgE reactivity. We found that depending on the arrangement of allergen fragments, mosaic molecules with strongly varying IgE reactivity were obtained. Based on an extensive screening with sera and basophils from allergic patients, two hypoallergenic mosaic molecules, P and Q, incorporating the primary sequence elements of the four grass pollen allergens were identified. As shown by lymphoproliferation experiments, they contained allergen-specific T cell epitopes required for tolerance induction, and upon immunization of animals induced higher allergen-specific IgG Abs than the wild-type allergens and a registered monophosphoryl lipid A-adjuvanted vaccine based on natural grass pollen allergen extract. Moreover, IgG Abs induced by immunization with P and Q inhibited the binding of patients' IgE to natural allergens from five grasses better than IgG induced with the wild-type allergens or an extract-based vaccine. Our results suggest that vaccines based on the hypoallergenic grass pollen mosaics can be used for immunotherapy of grass pollen allergy.

The rapidly changing world of food allergy in children

Food allergy is a common problem in childhood. The term is used to include both immunoglobulin E (IgE)-mediated and non-IgE-mediated food allergies, which have a significant effect on the quality of life of patients and their families. In this report, we aim to discuss recent advances in the diagnosis, management, and treatment modalities of food allergy in children.

Distinct parameters of the basophil activation test reflect the severity and threshold of allergic reactions to peanut

Background

The management of peanut allergy relies on allergen avoidance and epinephrine autoinjector for rescue treatment in patients at risk of anaphylaxis. Biomarkers of severity and threshold of allergic reactions to peanut could significantly improve the care for patients with peanut allergy.

Objective

We sought to assess the utility of the basophil activation test (BAT) to predict the severity and threshold of reactivity to peanut during oral food challenges (OFCs).

Methods

The severity of the allergic reaction and the threshold dose during OFCs to peanut were determined. Skin prick tests, measurements of specific IgE to peanut and its components, and BATs to peanut were performed on the day of the challenge.

Results

Of the 124 children submitted to OFCs to peanut, 52 (median age, 5 years) reacted with clinical symptoms that ranged from mild oral symptoms to anaphylaxis. Severe reactions occurred in 41% of cases, and 57% reacted to 0.1 g or less of peanut protein. The ratio of the percentage of CD63⁺ basophils after stimulation with peanut and after stimulation with anti-IgE (CD63 peanut/anti-IgE) was independently associated with severity (P = .001), whereas the basophil allergen threshold sensitivity CD-sens (1/EC₅₀ × 100, where EC₅₀ is half maximal effective concentration) value was independently associated with the threshold (P = .020) of allergic reactions to peanut during OFCs. Patients with CD63 peanut/anti-IgE levels of 1.3 or greater had an increased risk of severe reactions (relative risk, 3.4; 95% CI, 1.8-6.2). Patients with a CD-sens value of 84 or greater had an increased risk of reacting to 0.1 g or less of peanut protein (relative risk, 1.9; 95% CI, 1.3-2.8).

Conclusions

Basophil reactivity is associated with severity and basophil sensitivity is associated with the threshold of allergic reactions to peanut. CD63 peanut/anti-IgE and CD-sens values can be used to estimate the severity and threshold of allergic reactions during OFCs.

Development of a hypoallergenic recombinant parvalbumin for first-in-man subcutaneous immunotherapy of fish allergy

BACKGROUND

The FAST (food allergy-specific immunotherapy) project aims at developing safe and effective subcutaneous immunotherapy for fish allergy, using recombinant hypoallergenic carp parvalbumin, Cyp c 1.

OBJECTIVES

Preclinical characterization and good manufacturing practice (GMP) production of mutant Cyp (mCyp) c 1.

METHODS

Escherichia coli-produced mCyp c 1 was purified using standard chromatographic techniques. Physicochemical properties were investigated by gel electrophoresis, size exclusion chromatography, circular dichroism spectroscopy, reverse-phase high-performance liquid chromatography and mass spectrometry. Allergenicity was assessed by ImmunoCAP inhibition and basophil histamine release assay, immunogenicity by immunization of laboratory animals and stimulation of patients' peripheral blood mononuclear cells (PBMCs). Reference molecules were purified wild-type Cyp c 1 (natural and/or recombinant). GMP-compliant alum-adsorbed mCyp c 1 was tested for acute toxicity in mice and rabbits and for repeated-dose toxicity in mice. Accelerated and real-time protocols were used to evaluate stability of mCyp c 1 as drug substance and drug product.

RESULTS

Purified mCyp c 1 behaves as a folded and stable molecule. Using sera of 26 double-blind placebo-controlled food-challenge-proven fish-allergic patients, reduction in allergenic activity ranged from 10- to 5,000-fold (1,000-fold on average), but with retained immunogenicity (immunization in mice/rabbits) and potency to stimulate human PBMCs. Toxicity studies revealed no toxic effects and real-time stability studies on the Al(OH)3-adsorbed drug product demonstrated at least 20 months of stability.

CONCLUSION

The GMP drug product developed for treatment of fish allergy has the characteristics targeted for in FAST: i.e. hypoallergenicity with retained immunogenicity. These results have warranted first-in-man immunotherapy studies to evaluate the safety of this innovative vaccine.

Randomized trial of peanut consumption in infants at risk for peanut allergy

BACKGROUND

The prevalence of peanut allergy among children in Western countries has doubled in the past 10 years, and peanut allergy is becoming apparent in Africa and Asia. We evaluated strategies of peanut consumption and avoidance to determine which strategy is most effective in preventing the development of peanut allergy in infants at high risk for the allergy.

METHODS

We randomly assigned 640 infants with severe eczema, egg allergy, or both to consume or avoid peanuts until 60 months of age. Participants, who were at least 4 months but younger than 11 months of age at randomization, were assigned to separate study cohorts on the basis of preexisting sensitivity to peanut extract, which was determined with the use of a skin-prick test--one consisting of participants with no measurable wheal after testing and the other consisting of those with a wheal measuring 1 to 4 mm in diameter. The primary outcome, which was assessed independently in each cohort, was the proportion of participants with peanut allergy at 60 months of age.

RESULTS

Among the 530 infants in the intention-to-treat population who initially had negative results on the skin-prick test, the prevalence of peanut allergy at 60 months of age was 13.7% in the avoidance group and 1.9% in the consumption group (P<0.001). Among the 98 participants in the intention-to-treat population who initially had positive test results, the prevalence of peanut allergy was 35.3% in the avoidance group and 10.6% in the consumption group (P=0.004). There was no significant between-group difference in the incidence of serious adverse events. Increases in levels of peanut-specific IgG4 antibody occurred predominantly in the consumption group; a greater percentage of participants in the avoidance group had elevated titers of peanut-specific IgE antibody. A larger wheal on the skin-prick test and a lower ratio of peanut-specific IgG4:IgE were associated with peanut allergy.

CONCLUSIONS

The early introduction of peanuts significantly decreased the frequency of the development of peanut allergy among children at high risk for this allergy and modulated immune responses to peanuts. (Funded by the National Institute of Allergy and Infectious Diseases and others; ClinicalTrials.gov number, NCT00329784.).

Diagnosis and treatment of pediatric food allergy: an update

The prevalence of pediatric food allergy and anaphylaxis has increased in the last decades, especially in westernized countries where this emerging phenomenon was marked as a "second wave" of the allergic epidemic. Over recent years great advances have been achieved in the field of in vitro allergy testing and component-resolved diagnosis has increasingly entered clinical practice. Testing for allergen components can contribute to a more precise diagnosis by discriminating primary from cross-reactive sensitizations and assessing the risk of severe allergic reactions.The basic concept of the management of food allergy in children is also changing. Avoidance of the offending food is still the mainstay for disease management, especially in primary health care settings, but it severely affects the patients' quality of life without reducing the risk of accidental allergic reactions. There is a growing body of evidence to show that specific oral tolerance induction can represent a promising treatment option for food allergic patients. In parallel, education of food allergic patients and their caregivers as well as physicians about anaphylaxis and its treatment is becoming recognized a fundamental need. International guidelines have recently integrated these new evidences and their broad application all over Europe represents the new challenge for food allergy specialists.

Administration of a probiotic with peanut oral immunotherapy: A randomized trial

BACKGROUND

Coadministration of a bacterial adjuvant with oral immunotherapy (OIT) has been suggested as a potential treatment for food allergy.

OBJECTIVE

To evaluate a combined therapy comprising a probiotic together with peanut OIT.

METHODS

We performed a double-blind, placebo-controlled randomized trial of the probiotic Lactobacillus rhamnosus CGMCC 1.3724 and peanut OIT (probiotic and peanut oral immunotherapy [PPOIT]) in children (1-10 years) with peanut allergy. The primary outcome was induction of sustained unresponsiveness 2 to 5 weeks after discontinuation of treatment (referred to as possible sustained unresponsiveness). Secondary outcomes were desensitization, peanut skin prick test, and specific IgE and specific IgG4 measurements.

RESULTS

Sixty-two children were randomized and stratified by age (≤5 and >5 years) and peanut skin test wheal size (≤10 and >10 mm); 56 reached the trial's end. Baseline demographics were similar across groups. Possible sustained unresponsiveness was achieved in 82.1% receiving PPOIT and 3.6% receiving placebo (P < .001). Nine children need to be treated for 7 to achieve sustained unresponsiveness (number needed to treat, 1.27; 95% CI, 1.06-1.59). Of the subjects, 89.7% receiving PPOIT and 7.1% receiving placebo were desensitized (P < .001). PPOIT was associated with reduced peanut skin prick test responses and peanut-specific IgE levels and increased peanut-specific IgG4 levels (all P < .001). PPOIT-treated participants reported a greater number of adverse events, mostly with maintenance home dosing.

CONCLUSION

This is the first randomized placebo-controlled trial evaluating the novel coadministration of a probiotic and peanut OIT and assessing sustained unresponsiveness in children with peanut allergy. PPOIT was effective in inducing possible sustained unresponsiveness and immune changes that suggest modulation of the peanut-specific immune response. Further work is required to confirm sustained unresponsiveness after a longer period of secondary peanut elimination and to clarify the relative contributions of probiotics versus OIT.

Influence of early-life exposures on food sensitization and food allergy in an inner-city birth cohort

OBJECTIVE

Previous data suggest that food allergy (FA) might be more common in inner-city children; however, these studies have not collected data on both sensitization and clinical reactivity or early-life exposures.

METHODS

Children in the Urban Environment and Childhood Asthma birth cohort were followed through age 5 years. Household exposures, diet, clinical history, and physical examinations were assessed yearly; levels of specific IgE to milk, egg, and peanut were measured at 1, 2, 3, and 5 years of age. On the basis of sensitization (IgE ≥0.35 kU/L) and clinical history over the 5-year period, children were classified as having FA or being possibly allergic, sensitized but tolerant, or not allergic/not sensitized.

RESULTS

Five hundred sixteen children were included. Overall, 55.4% were sensitized (milk, 46.7%; egg, 31.0%; and peanut, 20.9%), whereas 9.9% were categorized as having FA (peanut, 6.0%; egg, 4.3%; and milk, 2.7%; 2.5% to >1 food). The remaining children were categorized as possibly allergic (17.0%), sensitized but tolerant (28.5%), and not sensitized (44.6%). Eighteen (3.5%) reported reactions to foods for which IgE levels were not measured. Food-specific IgE levels were similar in children with FA versus sensitized but tolerant children, except for egg, levels of which were higher in patients with FA at ages 1 and 2 years. FA was associated with recurrent wheeze, eczema, aeroallergen sensitization, male sex, breast-feeding, and lower endotoxin exposure in year 1 but not with race/ethnicity, income, tobacco exposure, maternal stress, or early introduction of solid foods.

CONCLUSIONS

Even given that this was designed to be a high-risk cohort, the cumulative incidence of FA is extremely high, especially considering the strict definition of FA that was applied and that only 3 common allergens were included.

Food-specific IgG Antibody-guided Elimination Diets Followed by Resolution of Asthma Symptoms and Reduction in Pharmacological Interventions in Two Patients: A Case Report

Asthma is one of the most common causes of office visits in the primary care and emergency care settings. Individuals are often able to maintain symptomatic control with long-term pharmacological therapy. Exacerbations of asthma commonly occur due to exposure to triggers such as viruses, pollutants, and allergens. While it is widely accepted that exposure to immunoglobulin E food allergens can exacerbate asthma symptoms, there is little evidence examining delayed immunoglobulin G-mediated reactions to food. Here we present two clinical cases of individuals who experienced a reduction in asthma symptoms, decreased dependence on pharmacological therapies, and increased quality of life by eliminating foods that demonstrated reactivity to immunoglobulin G levels identified through serum testing.

The changing geoepidemiology of food allergies

The science of food allergy has been rapidly evolving before our eyes in the past half century. Like other allergic disorders, the prevalence of food allergies has dramatically increased, and coupled with the increased public awareness of anaphylaxis due to food allergy, this has driven an explosion in basic and clinical research in this extremely broad subject. Treatment of food allergies has evolved and practices such as food challenges have become an integral part of an allergy practice. The impact of the increase of food allergy has driven package labeling laws, legislation on emergency treatment availability in schools and other public places, and school policy. But to this day, our knowledge of the pathogenesis of food allergy is still incomplete. There are the most obvious IgE-mediated immediate hypersensitivity reactions, but then multiple previously unidentified conditions such as eosinophilic esophagitis, food protein-induced enterocolitis syndrome, milk protein allergy, food-induced atopic dermatitis, oral allergy syndrome, and others have complicated the diagnosis and management of many of our patients who are unable to tolerate certain foods. Many of these conditions are not IgE-mediated, but may be T cell-driven diseases. The role of T regulatory cells and immune tolerance and the newly discovered immunological role of vitamin D have shed light on the variable clinical presentation of food allergy and the development of new methods of immunotherapy in an example of bench-to-bedside research. Component-resolved diagnostic techniques have already begun to allow us to more precisely define the epitopes that are targeted in food allergic patients. The development of biological modulators, research on genomics and proteomics, and epigenetic techniques all offer promising avenues for new modes of therapy of food allergy in the twenty-first century.

Sublingual (SLIT) versus oral immunotherapy (OIT) for food allergy

Food allergy is a common condition for which the only currently approved treatments are avoidance of the allergenic food and the administration of emergency medications upon accidental exposure. Over the past 10 years, significant advances have been made in the field of food immunotherapy, with efforts focusing on allergen exposure via the oral mucosa. Oral immunotherapy (OIT) and sublingual immunotherapy (SLIT) are the two modalities that have been most extensively studied, and this article will review recent advances in our knowledge of the efficacy and safety of these treatments.

Oral and sublingual immunotherapy for food allergy

IgE-mediated food allergy is a potentially life-threatening allergic disease with an increase in prevalence in developed countries over the past 15 years. Currently, there are no approved forms of therapy and the standard of care is dietary restriction and ready access to emergency medications, such as self-injectable epinephrine and antihistamines. Allergen-specific modalities of treatment currently being studied include oral immunotherapy (OIT) and sublingual immunotherapy (SLIT). Both forms demonstrate the ability to desensitize patients to a variety of specific food allergens and show great promise. However, more research is needed to evaluate the safety and efficacy of OIT and SLIT prior to routine use in clinical practice.

Two year effects of food allergen immunotherapy on quality of life in caregivers of children with food allergies

Background

Food allergy (FA) can have serious psychosocial and economic repercussions on food-allergic children and their caregivers and be associated with negative effects on their quality of life. Food allergen immunotherapy (IT) is a promising experimental therapy but can be linked to anxiety. This study investigated the effects of IT on FA-specific health-related quality of life (HRQL) over a 24 month-follow-up in caregivers of children with single and multiple food allergies. We hypothesized that characteristics such as age, asthma at baseline and respiratory allergic reactions during therapy were key characteristics that influenced HRQL scores.

Methods

A validated Food Allergy Quality of Life – Parental Burden Questionnaire (FAQL-PB) was used to assess HRQL. It was randomly distributed to and filled out by caregivers of 57 food-allergic children enrolled in clinical trials of IT. The same parent answered the FABQL-PB questionnaire at baseline and for 6-month, 12- month, 18- month, and 24-month time points on IT.

Results

Caregiver HRQL improved significantly (change < - 0.5, p <0.0001) at each follow-up time point compared to baseline. The percentages of caregivers with improvement in HRQL progressively increased (92% at 24 month-follow-up time point compared to baseline). HRQL improved more in caregivers of participants older than 10 years or desensitized to more than 4 food allergens than those who were not (p <0.0001). Caregivers of participants with pre-existing asthma or dose-related respiratory allergic reactions had less improvement in HRQL than those who did not (p <0.01).

Conclusion

IT lead to improvement in caregiver HRQL. Certain characteristics were associated with greater improvements in caregiver HRQL.

Electronic supplementary material

The online version of this article (doi:10.1186/1710-1492-10-57) contains supplementary material, which is available to authorized users.

Oral and sublingual immunotherapy for egg allergy

BACKGROUND

Clinical egg allergy is a common food allergy. Current management relies upon strict allergen avoidance. Oral immunotherapy (OIT) might be an optional treatment, through desensitization to egg allergen.

OBJECTIVES

We aimed to assess the successful desensitization and development of tolerance to egg protein and the safety of egg oral and sublingual immunotherapy in children and adults with immunoglobulin E (IgE)-mediated egg allergy as compared to a placebo treatment or an avoidance strategy.

SEARCH METHODS

We searched 13 databases for journal articles, conference proceedings, theses and unpublished trials using a combination of subject headings and text words (the last search was on 5 December 2013).

SELECTION CRITERIA

Randomized controlled trials (RCTs) were included. All age groups with clinical egg allergy were to be included.

DATA COLLECTION AND ANALYSIS

We retrieved 83 studies from the electronic searches. We selected studies, extracted data and assessed the methodological quality. We attempted to contact the study investigators to obtain the unpublished data, wherever possible. We used the I² statistic to assess statistical heterogeneity. We estimated a pooled risk ratio (RR) with 95% confidence interval (CI) for each outcome using a Mantel-Haenzel fixed-effect model if statistical heterogeneity was low (I² value less than 50%).

MAIN RESULTS

We included four RCTs with a total of 167 recruited individuals (OIT 100; control 67 participants), all of whom were children (aged four to 15 years). One study used a placebo and three studies used an avoidance diet as the control. Each study used a different OIT protocol. Thirty nine per cent of OIT participants were able to tolerate a full serving of egg compared to 11.9% of the controls (RR 3.39, 95% CI 1.74 to 6.62). Forty per cent of OIT participants could ingest a partial serving of egg (1 g to 7.5 g; RR 5.73, 95% CI 3.13 to 10.50). Sixty nine per cent of the participants presented with mild-to-severe adverse effects (AEs) during OIT (RR 6.06, 95% CI 3.11 to 11.83). Five of the 100 participants receiving OIT required epinephrine. We cannot comment on whether over- or under-reporting of AEs was a concern based on the available data. Overall there was inconsistent methodological rigour in the trials.

AUTHORS' CONCLUSIONS

The studies were small and the quality of evidence was low. Current evidence suggests that OIT can desensitize a large number of egg-allergic patients, although it remains unknown whether long-term tolerance develops. A major difficulty of OIT is the frequency of AEs, though these are usually mild and self-limiting. The use of epinephrine while on OIT seems infrequent. There are no standardized protocols for OIT and guidelines would be required prior to incorporating desensitization into clinical practice.