Sublingual vs oral immunotherapy for food allergy: identifying the right approach

Sublingual Immunotherapy: How Sublingual Allergen Administration Heals Allergic Diseases; Current Perspective about the Mode of Action

Owing to the successful application of sublingual immunotherapy (SLIT), allergen immunotherapy (AIT) has become one of the leading treatments for allergic diseases. Similar to the case with other AITs, such as subcutaneous and oral immunotherapies, not only the alleviation of allergic symptoms, but also the curing of the diseases can be expected in patients undergoing SLIT. However, how and why such strong efficacy is obtained by SLIT, in which allergens are simply administered under the tongue, is not clearly known. Various potential mechanisms, including the induction of blocking antibodies, T cell tolerance, regulatory B and T cells, CD103^-CD11b⁺ classical dendritic cells, and CD206⁺ macrophages, and the reduction of innate lymphoid cells, mast cells, and basophils, have been suggested. Recently, through a comparative analysis between high- and non-responder patients of SLIT, we have successfully proposed several novel mechanisms. Here, we introduce our recent findings and summarize the current understanding of the mechanisms underlying the strong efficacy of SLIT.

Successful sublingual immunotherapy for severe egg allergy in children: a case report

Background

Egg allergy is one of the most common food allergies in children. To date, oral immunotherapy (OIT) has been considered as a promising treatment option for egg allergy. However, safety issues remain concerning severe adverse events requiring epinephrine injection. Hence, establishing a safer method to treat egg allergy would be beneficial. We report here two children with egg allergy who were safely treated with sublingual immunotherapy (SLIT) before transitioning to OIT.

Case presentation

Patient 1 was a 7-year-old girl and Patient 2 was a 5-year-old girl. Although OIT for egg had been attempted in both patients, severe anaphylactic symptoms were induced by ingesting only 0.1 g of heated whole egg. Therefore, SLIT was conducted with aqueous suspensions consisting of water and heated whole egg powder. Suspensions were administered sublingually, kept in the mouth for 2 min, and spat out immediately thereafter. SLIT was continued for 7 months for Patient 1 and 8 months for Patient 2 due to the exploratory character of the study. Afterwards, the patients successfully transferred to low-dose OIT with 1 g of heated whole egg (≒170 mg of egg protein) daily, and are continuing the therapy as of June 2020. As for adverse reactions, Patient 1 expressed oral cavity itchiness once at the beginning of SLIT. Patient 2 had no adverse reaction. The levels of antigen-specific IgE decreased in both patients after SLIT, and further decreased after switching to OIT.

Conclusions

Few clinical studies have evaluated the efficacy and safety of SLIT for egg allergy. Although the treatment was conducted in only two patients, our results have shown that SLIT is a promising treatment procedure for egg allergy. Further clinical trials will be needed to additionally assess the efficacy and safety of SLIT in children with food allergy.

Genetically engineered fusion of allergen and viral-like particle induces a more effective allergen-specific immune response than a combination of them

Chimeric virus-like particles (VLPs) were developed as a candidate for allergen-specific immunotherapy. In this study, hepatitis B core antigen (HBcAg) that genetically fused to Chenopodium album polcalcin (Che a 3)-derived peptide was expressed in E. coli BL21, purified, and VLP formation was evaluated using native agarose gel electrophoresis (NAGE) and transmission electron microscopy (TEM). Chimeric HBc VLPs were characterized in terms of their reactivity to IgE, the induction of blocking IgG and allergen-specific IgE, basophil-activating capacity, and Th1-type immune responses. Results from IgE reactivity and basophil activation test showed that chimeric HBc VLPs lack IgE-binding capacity and basophil degranulation activity. Although chimeric HBc VLPs induced the highest level of efficient polcalcin-specific IgG antibody in comparison to those induced by recombinant Che a 3 (rChe a 3) mixed either with HBc VLPs or alum, they triggered the lowest level of polcalcin-specific IgE in mice following immunization. Furthermore, in comparison to the other antigens, chimeric HBc VLPs produced a polcalcin-specific Th1 cell response. Taken together, genetically fusion of allergen derivatives to HBc VLPs, in comparison to a mix of them, may be a more effective way to induce appropriate immune responses in allergen-specific immunotherapy. KEY POINTS: • The insertion of allergen-derived peptide into major insertion region (MIR) of hepatitis B virus core (HBc) antigen resulted in nanoparticles displaying allergen-derived peptide upon its expression in prokaryotic host. • The resultant VLPs (chimeric HBc VLPs) did not exhibit IgE reactivity with allergic patients' sera and were not able to degranulate basophils. • Chimeric HBc VLPs dramatically improved protective IgG antibody response compared with those induced by allergen mixed either with HBc VLPs or alum. • Chimeric HBc VLPs induced Th1 responses that were counterparts of Th2 responses (allergic). • Chimeric HBc VLPs increased IgG2a/ IgG1 ratio and the level of IFN-γ compared to those induced by allergen mixed with either HBc VLPs or alum. Graphical Abstract.

Recent advances in mechanisms of food allergy and anaphylaxis

Food allergens are innocuous proteins that promote tolerogenic adaptive immune responses in healthy individuals yet in other individuals induce an allergic adaptive immune response characterized by the presence of antigen-specific immunoglobulin E and type-2 immune cells. The cellular and molecular processes that determine a tolerogenic versus non-tolerogenic immune response to dietary antigens are not fully elucidated. Recently, there have been advances in the identification of roles for microbial communities and anatomical sites of dietary antigen exposure and presentation that have provided new insights into the key regulatory steps in the tolerogenic versus non-tolerogenic decision-making processes. Herein, we will review and discuss recent findings in cellular and molecular processes underlying food sensitization and tolerance, immunological processes underlying severity of food-induced anaphylaxis, and insights obtained from immunotherapy trials.

A general strategy for de novo immunotherapy design: the active treatment of food allergy

INTRODUCTION

IgE-mediated food allergy (FA) has been emerging as a public health priority. It is a potentially life-threatening condition with negative impact on the quality of life of patients and their family and its prevalence is increasing in westernized countries in the recent two decades. The current standard approach to FA consists of the strict avoidance of the triggering food. However, an elimination diet may be difficult and frustrating, above all for those foods (e.g. milk and egg) that are pivotal in the common diet. Oral immunotherapy (OIT) may increase the amount of food that the patient can intake without reaction and reduce the risk of potential life-threatening allergic reactions. It is currently considered the most promising treatment for FA. However, many gaps are still unsolved. Areas covered: The aim of this review is to shed light on the current evidence and the main needs in OIT in order to stimulate the development of longitudinal, prospective, and well-designed studies with the final goal of a 'precision medicine.' Expert commentary: Clinical trials for OIT conducted so far are extremely heterogeneous. The aim in the near future is to identify the most suitable candidates to OIT and algorithms for treatments tailored on well-characterized subpopulations of patients.

Component resolved diagnostic study of cow's milk allergy in infants and young children in northern China

BACKGROUND

Increasing dairy consumption in China has been accompanied by rising incidence of milk allergy. Here we analyzed profiles of specific immunoglobulin E (sIgE) against cow's milk proteins, and assessed their value for milk allergy diagnosis among infants and young children from northern China.

METHODS

Sera collected from 48 patients with milk allergy and 27 negative control subjects was analyzed by enzyme-linked immunosorbent assay to measure sIgE to α-lactalbumin (Bos d 4), β-lactoglobulin (Bos d 5), α-casein (Bos d 9), β-casein (Bos d 11), and κ-casein (Bos d 12).

RESULTS

Among milk-allergic individuals, most were sensitized to at least one milk protein; about half were sensitized to Bos d 5, Bos d 9, Bos d 11 and Bos d 12, respectively, while few had positive serum sIgE against Bos d 4. Bos d 12 sIgE had the largest area under curve (AUC) (0.878; 95% CI, 0.800-0.957) and thus showed the best diagnostic performance in discriminating between milk-allergic and non-milk allergic patients, with a sensitivity of 92.6% and specificity of 72.9% using a statistically optimal cut-off value (OD_450nm, 0.191). The combinations of Bos d 5 + Bos d 12 showed an AUC of 0.926, which was larger than for any individual components.

CONCLUSIONS

Our results revealed inter-individual variation in the sensitization to different milk allergen component. Bos d 12 sIgE showed best performance in diagnosing milk allergy. Milk allergy diagnostic accuracy was further improved using combinations of milk allergen components by application of ROC curves based on logistic regression.

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.

Immunotherapy for food allergies: a myth or a reality?

Food allergy is a worldwide issue, with an estimated prevalence of 2-10%. An effective treatment is not available for people affected and the only management is the avoidance of the allergen. Oral immunotherapy and sublingual immunotherapy have been tested by several authors, in particular for milk, egg and peanuts allergy, with significant results in term of desensitization induction. The achievement of tolerance is by the contrary doubtful, with different results obtained. In this review, we reviewed protocols of oral and sublingual immunotherapy for food allergy published in literature, mainly against milk, egg and peanut. At present, immunotherapy does not represent the gold standard in the treatment of food allergy, even if it can desensitize patients.

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.

Modified allergens and their potential to treat allergic disease

Allergen-specific immunotherapy is the only treatment of allergic diseases that aims at modifying the underlying immune mechanism. Current protocols are long and at risk of anaphylactic reactions. The main aim of current research is decreasing the risk of side effects and increasing efficacy, in particular targeting reduction of treatment duration. Since the advent of molecular biology, extracts can be replaced by recombinant hypo-allergens, peptides, or fusion proteins. In addition, different routes of administration are being pursued as well as the addition of new adjuvants that are targeted at skewing the immune system away from a Th2 to a more Th1 or regulatory T cell phenotype. In this review, we summarize the recent advances in this field focusing on the allergen modifications and new adjuvants.

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.

Oral Immunotherapy for Treatment of Immunoglobulin E-Mediated Food Allergy: The Transition to Clinical Practice

Today, there is neither an effective nor an active treatment for food allergy. Allergy immunotherapy has been proposed as an attractive strategy to actively treat food allergy. Oral immunotherapy (OIT), also known as oral desensitization, is a method of inducing the body's immune system to tolerate a food that causes an allergic overreaction. It has been studied for the use in treatment of immunoglobulin E-mediated food allergy to the most common foods, including milk, egg, and peanut. OIT has been able to desensitize subjects to varying degrees. However, many questions remain unanswered, including efficient formulation, optimal dosing, and induction protocol to achieve full tolerance, transition of OIT to clinical practice, and maximal safety profile. This review focuses on the use of OIT as a new and active treatment for food allergy. The possibility of transition of OIT to clinical practice represents, in this field, the next pivotal step with the goal of improving the quality of life of patients with food allergy and their families.

Immunotherapy in allergy and cellular tests: state of art

The basophil activation test (BAT) is an in vitro assay where the activation of basophils upon exposure to various IgE-challenging molecules is measured by flow cytometry. It is a cellular test able to investigate basophil behavior during allergy and allergy immunotherapy. A panoply of critical issues and suggestive advances have rendered this assay a promising yet puzzling tool to endeavor a full comprehension of innate immunity of allergy desensitization and manage allergen or monoclonal anti-IgE therapy. In this review a brief state of art of BAT in immunotherapy is described focusing onto the analytical issue pertaining BAT performance in allergy specific therapy.

Sublingual immunotherapy: World Allergy Organization position paper 2013 update

We have prepared this document, "Sublingual Immunotherapy: World Allergy Organization Position Paper 2013 Update", according to the evidence-based criteria, revising and updating chapters of the originally published paper, "Sublingual Immunotherapy: World Allergy Organization Position Paper 2009", available at http://www.waojournal.org. Namely, these comprise: "Mechanisms of sublingual immunotherapy;" "Clinical efficacy of sublingual immunotherapy" - reporting all the data of all controlled trials published after 2009; "Safety of sublingual immunotherapy" - with the recently published Grading System for adverse reactions; "Impact of sublingual immunotherapy on the natural history of respiratory allergy" - with the relevant evidences published since 2009; "Efficacy of SLIT in children" - with detailed analysis of all the studies; "Definition of SLIT patient selection" - reporting the criteria for eligibility to sublingual immunotherapy; "The future of immunotherapy in the community care setting"; "Methodology of clinical trials according to the current scientific and regulatory standards"; and "Guideline development: from evidence-based medicine to patients' views" - including the evolution of the methods to make clinical recommendations.Additionally, we have added new chapters to cover a few emerging crucial topics: "Practical aspects of schedules and dosages and counseling for adherence" - which is crucial in clinical practice for all treatments; "Perspectives and new approaches" - including recombinant allergens, adjuvants, modified allergens, and the concept of validity of the single products. Furthermore, "Raising public awareness about sublingual immunotherapy", as a need for our patients, and strategies to increase awareness of allergen immunotherapy (AIT) among patients, the medical community, all healthcare stakeholders, and public opinion, are also reported in detail.

Immunotherapy - risk/benefit in food allergy

Food allergy is a growing health concern in the westernized world with approx. 6% of children suffering from it. A lack of approved treatment has led to strict avoidance of the culprit food proteins being the only standard of care. Nowadays in-depth research is conducted to evaluate the possible use of allergen-specific immunotherapy (SIT) as an active therapeutic option for food allergy. Various routes of administration for the immunotherapy are investigated, including subcutaneous, oral, sublingual, and epicutaneous, and some appear to be successful in inducing a temporary tolerant state. Most research has been conducted with oral immunotherapy due to its efficacious and relatively safe profile. Increasing interest is dedicated to safer and more convenient approaches, such as sublingual and epicutaneous SIT; however, doubts exist about their possible capacity to induce temporary tolerant state and permanent oral tolerance. The high frequency of allergic adverse reactions of the various approaches and the inability to achieve permanent oral tolerance have highlighted the need of refinements in the strategies. A promising strategy for preventing IgE cross-linking and thus enhancing safety of SIT, while still activating T cells, is the use of tolerogenic peptides. The implementation of such an immunotherapy approach has the potential of not only increasing the chance of achieving a permanent state of tolerance, but also improving the safety and tolerability of the therapy. Immunotherapy for food allergy is still not ready for the clinic, but current and upcoming studies are dedicated to collect enough evidence for the possible implementation of allergen-SIT as a standard treatment for food allergy.

How to reintroduce cow's milk?

In a child that is allergic to milk, the natural next step, following the elimination diet, is the reintroduction of cow's milk. Several questions may arise. When feasible, this reintroduction has many benefits for the child and his family. However, the disease needs to be well defined by physicians and explained to parents. They need to understand that there are different types of allergy to cow's milk, specifically IgE- and non-IgE-mediated, and each of these may exhibit both a variable duration and frequently an incomplete recovery. Deciding where to first reintroduce cow's milk to a child who has previously followed a milk-free diet, whether it be at home or in a hospital, also frequently presents an issue. Following this first reintroduction, the progressive increase of milk into the diet needs to be managed properly, as not all children will go back to a normal dairy products intake. Recent studies show that most children with milk allergy tolerate products containing baked milk and that their consumption might speed up recovery. Hence, the purpose of the milk challenge in a child on a milk-free diet is becoming, even in a child still reactive to milk, the first step of gradual and individually adapted reintroduction of milk or dairy products. When reintroduction of cow's milk does not work, immunotherapy becomes an option, and this is carried out in specialized centers.

Food allergy diagnosis and therapy: where are we now?

Food allergy is a growing worldwide epidemic that adversely effects up to 10% of the population. Causes and risk factors remain unclear and diagnostic methods are imprecise. There is currently no accepted treatment for food allergy. Therefore, there is an imminent need for greater understanding of food allergies, revised diagnostics and development of safe, effective therapies. Oral immunotherapy provides a particularly promising avenue, but is still highly experimental and not ready for clinical use.

Cow's milk allergy: from allergens to new forms of diagnosis, therapy and prevention

The first adverse reactions to cow's milk were already described 2,000 years ago. However, it was only 50 years ago that several groups started with the analysis of cow's milk allergens. Meanwhile the spectrum of allergy eliciting proteins within cow's milk is identified and several cow's milk allergens have been characterized regarding their biochemical properties, fold and IgE binding epitopes. The diagnosis of cow's milk allergy is diverse ranging from fast and cheap in vitro assays to elaborate in vivo assays. Considerable effort was spent to improve the diagnosis from an extract-based into a component resolved concept. There is still no suitable therapy available against cow's milk allergy except avoidance. Therefore research needs to focus on the development of suitable and safe immunotherapies that do not elicit severe side effect.