New findings, pathophysiology, and antigen analysis in pollen-food allergy syndrome

Structural homology of mite profilins to plant profilins is not indicative of allergic cross-reactivity

Structural and allergenic characterization of mite profilins has not been previously pursued to a similar extent as plant profilins. Here, we describe structures of profilins originating from Tyrophagus putrescentiae (registered allergen Tyr p 36.0101) and Dermatophagoides pteronyssinus (here termed Der p profilin), which are the first structures of profilins from Arachnida. Additionally, the thermal stabilities of mite and plant profilins are compared, suggesting that the high number of cysteine residues in mite profilins may play a role in their increased stability. We also examine the cross-reactivity of plant and mite profilins as well as investigate the relevance of these profilins in mite inhalant allergy. Despite their high structural similarity to other profilins, mite profilins have low sequence identity with plant and human profilins. Subsequently, these mite profilins most likely do not display cross-reactivity with plant profilins. At the same time the profilins have highly conserved poly(l-proline) and actin binding sites.

[Oral allergy syndrome (OAS)]

The pollen-food allergy syndrome, also known as oral allergy syndrome, is characterized by local reactions in the mouth and throat after consuming certain raw plant foods in individuals sensitized to pollen from grass, weeds, and trees. Birch-apple is the prototype of this syndrome, with apple, pear, and plum being the most commonly associated foods. Symptoms are usually limited to the oral cavity but can include systemic reactions, including anaphylaxis. Sensitization to pollen allergens, such as lipid transfer proteins, profilin, and PR-10 proteins, triggers this syndrome. Its prevalence varies by geographic region and the predominant pollen type, affecting between 30% and 60% of food allergies. Diagnosis involves a clinical history, skin tests, and, in ambiguous cases, double-blind, placebo-controlled oral food challenges. Treatment primarily involves avoiding trigger foods.

Perspectives of Proteomics in Respiratory Allergic Diseases

Proteomics in respiratory allergic diseases has such a battery of techniques and programs that one would almost think there is nothing impossible to find, invent or mold. All the resources that we document here are involved in solving problems in allergic diseases, both diagnostic and prognostic treatment, and immunotherapy development. The main perspectives, according to this version, are in three strands and/or a lockout immunological system: (1) Blocking the diapedesis of the cells involved, (2) Modifications and blocking of paratopes and epitopes being understood by modifications to antibodies, antagonisms, or blocking them, and (3) Blocking FcεRI high-affinity receptors to prevent specific IgEs from sticking to mast cells and basophils. These tools and targets in the allergic landscape are, in our view, the prospects in the field. However, there are still many allergens to identify, including some homologies between allergens and cross-reactions, through the identification of structures and epitopes. The current vision of using proteomics for this purpose remains a constant; this is also true for the basis of diagnostic and controlled systems for immunotherapy. Ours is an open proposal to use this vision for treatment.

Omalizumab is effective for a patient with pollen-food allergy syndrome who experienced intractable lip edema

Pollen-food allergy syndrome (PFAS) is an immunoglobulin E (IgE)-mediated allergic reaction caused when patients with pollen allergy ingest food having cross-reactivity with pollen. To date, no effective treatment method for this has been established. Here we report the case of a patient with PFAS who experienced lip edema, causing difficulties in treatment. This report describes the case of a 12-year-old boy with perennial allergic rhinitis since the age of 8 years. After ingesting fresh fruits and raw vegetables at the age of 11 years, he started to experience lip edema repeatedly. Thus, the patient was referred to our department. Based on the results of serum antigen-specific IgE, prick-to-prick, and allergen component tests, he was diagnosed with PFAS. He has been instructed to avoid causative food. Furthermore, the treatment using an antihistamine and antileukotriene receptor antagonist was initiated for pollen allergy. Sublingual immunotherapy (SLIT) for Japanese cedar pollen was initiated because the patient experienced severe nasal allergy symptoms during the dispersal season of this pollen. These treatments alleviated the nasal symptoms; however, the lip edema persisted. Omalizumab administration improved the lip edema. The combination of SLIT and omalizumab may be an effective treatment option for patients with PFAS.

Recent Advances in the Allergic Cross-Reactivity between Fungi and Foods

Airborne fungi are one of the most ubiquitous kinds of inhalant allergens which can result in allergic diseases. Fungi tend to grow in warm and humid environments with regional and seasonal variations. Their nomenclature and taxonomy are related to the sensitization of immunoglobulin E (IgE). Allergic cross-reactivity among different fungal species appears to be widely existing. Fungus-related foods, such as edible mushrooms, mycoprotein, and fermented foods by fungi, can often induce to fungus food allergy syndrome (FFAS) by allergic cross-reactivity with airborne fungi. FFAS may involve one or more target organs, including the oral mucosa, the skin, the gastrointestinal and respiratory tracts, and the cardiovascular system, with various allergic symptoms ranging from oral allergy syndrome (OAS) to severe anaphylaxis. This article reviews the current knowledge on the field of allergic cross-reactivity between fungal allergens and related foods, as well as the diagnosis and treatment on FFAS.

Anaphylaxis across Europe: are pollen food syndrome and lipid transfer protein allergy so far apart?

PURPOSE OF REVIEW

Traditionally pollen-food syndrome (PFS) is considered to be a mild cross-reacting food allergy affecting only Northern Europe, with lipid transfer protein (LTP) allergy being more severe and mainly occurring in Southern Europe. This review seeks to update the reader on both types of plant food allergy and to determine whether the stereotypical presentations of these plant food allergies remain the same, with a particular focus on reaction severity.

RECENT FINDINGS

Recent findings suggest that both these types of plant food allergy occur in children and adults. Although it is true that PFS allergy is more prevalent in Northern Europe and LTP allergy is more well known in Southern Europe, these conditions are not hidebound by geography, and the increasing spread and allergenicity of pollen due to global warming continues to change their presentation. Both conditions have a spectrum of symptom severity, with PFS sometimes presenting with more severe symptoms, including anaphylaxis and LTP allergy with milder reactions.

SUMMARY

It is important to consider that in many parts of Europe, reactions to plant foods, especially fruits or vegetables, could be mediated either by pollen cross-reactivity or primary sensitization to LTP allergens. All those presenting with symptoms to plant foods will benefit from a detailed clinical history and appropriate tests so that an accurate diagnosis can be made, and correct management implemented.

Real-life evaluation of molecular multiplex IgE test methods in the diagnosis of pollen associated food allergy

BACKGROUND

Diagnosis of food allergies is challenging, as combining information from specific IgE (sIgE)-sensitization pattern and skin prick tests (SPTs) with clinical history is necessary for a personalized management of allergic patients. The aim of this study was to compare two molecular tests, the ImmunoCAP ISAC (ISAC) and the Allergy Explorer, version 2 (ALEX² ) in the context of pollen food syndrome (PFS) diagnosis in a real-life scenario, to assess the benefit of multiplex testing in PFS patients.

METHODS

Diagnosis of food allergy was performed in 53 patients. Allergen-sIgE concentrations were measured with ISAC and ALEX² . Results for sIgE were statistically compared with each other, with SPT results and with clinical presentation of the patients.

RESULTS

Using ISAC as reference test for sIgE measurements, the average sensitivity of ALEX² for PR-10 allergens was 83.2% and the average specificity 88.0%. If only low sIgE concentrations were included, the sensitivity was 60.8% and the specificity 91.1%. Apple and hazelnut sensitizations were confirmed in most patients by concordance of sIgE and SPT results. Significant correlations were shown between clinical symptoms and Mal d 1- and Gly m 4-sIgE levels measured by both tests and for Cor a 1-sIgE levels measured by ALEX² . In eight patients, profilin related symptoms were supported by Hev b 8-sensitization.

CONCLUSION

Multiplex testing is beneficial to understand patient-specific individual sensitization profiles and to providing personalized management recommendations. In the future, custom-designed test kits might enable reducing costs of multiplex testing for specific patient groups without compromising the diagnostic value.

Rosaceae food allergy: a review

This review provides a global overview on Rosaceae allergy and details the particularities of each fruit allergy induced by ten Rosaceae species: almond/peach/cherry/apricot/plum (Amygdaleae), apple/pear (Maleae), and raspberry/blackberry/strawberry (Rosoideae). Data on clinical symptoms, prevalence, diagnosis, and immunotherapies for the treatment of Rosaceae allergy are herein stated. Allergen molecular characterization, cross-reactivity/co-sensitization phenomena, the impact of food processing and digestibility, and the methods currently available for the Rosaceae detection/quantification in foods are also described. Rosaceae allergy has a major impact in context to pollen-food allergy syndrome (PFAS) and lipid transfer protein (LTP) allergies, being greatly influenced by geography, environment, and presence of cofactors. Peach, apple, and almond allergies are probably the ones most affecting the quality of life of the allergic-patients, although allergies to other Rosaceae fruits cannot be overlooked. From patients' perspective, self-allergy management and an efficient avoidance of multiple fruits are often difficult to achieve, which might raise the risk for cross-reactivity and co-sensitization phenomena and increase the severity of the induced allergic responses with time. At this point, the absence of effective allergy diagnosis (lack of specific molecular markers) and studies advancing potential immunotherapies are some gaps that certainly will prompt the progress on novel strategies to manage Rosaceae food allergies.

Plant Food Allergy Improvement after Grass Pollen Sublingual Immunotherapy: A Case Series

Background: Cross-reactivity between pollens and plant food has been widely described. Pollen extract subcutaneous immunotherapy in patients with pollens and plant food allergy has been shown to improve tolerance not only to inhalant allergens but also to reduce symptoms in patients with various food allergies. Methods: We retrospectively report our experience with 15 female patients with a positive history for moderate, persistent allergic rhinitis due to grass pollen and oropharyngeal symptoms after ingestion of different plant food. These patients followed a five-grass pollen sublingual tablet immunotherapy for three years in a discontinuous pre-co-seasonal scheme. Results: All 15 patients treated with the 5-grass pollen sublingual tablet immunotherapy, taken once daily for 3 years on a 7-month course, showed improved ocular/nasal symptoms, with a reduction in the use of symptomatic drugs (e.g., nasal corticosteroids and H1 antihistamines). After the first seven-month course of immunotherapy, all patients declared a good tolerance to the intake of fruits and vegetables, and in particular, good tolerance to the offending foods. Conclusions: In conclusion, we have observed improvement of both respiratory and plant food allergies after sublingual immunotherapy (SLIT) with a five-grass pollen tablet.

Update on pollen-food allergy syndrome

INTRODUCTION

Allergies affect 20-30% of the population and respiratory allergies are mostly due to pollen grains from anemophilous plants. One to 5% of people suffer from food allergies and clinicians report increasing numbers of pollen-food allergy syndrome (PFAS), such that the symptoms have broadened from respiratory to gastrointestinal, and even to anaphylactic shock in the presence of cofactors. Thirty to 60% of food allergies are associated with pollen allergy while the percentage of pollen allergies associated to food allergy varies according to local environment and dietary habits.

AREAS COVERED

Articles published in peer-reviewed journals, covered by PubMed databank, clinical data are discussed including symptoms, diagnosis, and management. A chapter emphasizes the role of six well-known allergen families involved in PFAS: PR10 proteins, profilins, lipid transfer proteins, thaumatin-like proteins, isoflavone reductases, and β-1,3 glucanases. The relevance in PFAS of three supplementary allergen families is presented: oleosins, polygalacturonases, and gibberellin-regulated proteins. To support the discussion a few original relevant results were added.

EXPERT OPINION

Both allergenic sources, pollen and food, are submitted to the same stressful environmental changes resulting in an increase of pathogenesis-related proteins in which numerous allergens are found. This might be responsible for the potential increase of PFAS.

Clinical Relevance of Cross-Reactivity in Food Allergy

The diagnosis and management of food allergy is complicated by an abundance of homologous, cross-reactive proteins in edible foods and aeroallergens. This results in patients having allergic sensitization (positive tests) to many biologically related foods. However, many are sensitized to foods without exhibiting clinical reactivity. Although molecular diagnostics have improved our ability to identify clinically relevant cross-reactivity, the optimal approach to patients requires an understanding of the epidemiology of clinically relevant cross-reactivity, as well as the food-specific (degree of homology, protein stability, abundance) and patient-specific factors (immune response, augmentation factors) that determine clinical relevance. Examples of food families with high rates of cross-reactivity include mammalian milks, eggs, fish, and shellfish. Low rates are noted for grains (wheat, barley, rye), and rates of cross-reactivity are variable for most other foods. This review discusses clinically relevant cross-reactivity related to the aforementioned food groups as well as seeds, legumes (including peanut, soy, chickpea, lentil, and others), tree nuts, meats, fruits and vegetables (including the lipid transfer protein syndrome), and latex. The complicating factor of addressing co-allergy, for example, the risks of allergy to both peanut and tree nuts among atopic patients, is also discussed. Considerations for an approach to individual patient care are highlighted.

Pediatric patient with eosinophilic esophagitis and pollen-food allergy syndrome

The incidence of eosinophilic esophagitis (EoE) and pollen-food allergy syndrome (PFAS) is increasing worldwide, and coexistence of these 2 diseases has been reported in adults. In children, however, these conditions have not been reported as comorbidities probably because sensitization to aeroallergens occurs at an older age. We report the case of a boy with EoE and PFAS. He had had intermittent vomiting since 2 years of age. At 7 years of age, he experienced an episode of itchiness of the lips and throat for the first time, followed by vomiting, immediately after ingesting some raw fruits. We diagnosed PFAS based on the skin prick test at 8 years of age and diagnosed EoE by esophagogastroduodenoscopy 11 months after the diagnose of PFAS. His digestive symptoms did not disappear despite eliminating the fruits responsible for PFAS, but esomeprazole improved his symptoms. The incidence of EoE and PFAS as comorbidities in children might increase in the future.

Characteristics of pollen-related food allergy based on individual pollen allergy profiles in the Chinese population

Background

Patients with pollinosis are often multi-sensitized to diverse pollen allergens. However, little is known about pollen allergy types among Chinese pollinosis patients. This study is aimed to characterize clinical manifestations of food allergy among patients with different types of pollen allergy.

Methods

We retrospectively analyzed 402 pollinosis patients from an outpatient allergy department of the Peking Union Medical College Hospital who had been diagnosed by experienced allergists. All included patients who answered a questionnaire regarding seasonal pollinosis and clinical symptoms after ingestion of food and underwent intradermal skin tests. Total IgE and specific IgE levels were quantified by ImmunoCAP, using 0.35 kUA/L as a threshold for positivity.

Results

The patients were divided into 3 groups, based on the season during which they experienced symptoms and the 2 peaks of Chinese airborne pollen: spring-tree pollen symptoms group (SG), autumn-weed pollen symptoms group (AG), and a combined spring and autumn pollen symptoms group (CG). Birch pollen (83%) and ash pollen (74%) were common allergens among patients with spring symptoms, while mugwort pollen (87%) was a common allergen among patients with autumn symptoms. In total, 30% of the study population experienced pollen-related food allergy. Pollen-related food allergies were more prevalent among the single-season symptom groups (68% and 50% for the SG and AG, respectively) than among the CG (20%). All patients with pollen-related food-induced anaphylaxis exhibited autumn weed pollen symptoms. Except for 2 patients, all patients with food-induced anaphylaxis were allergic to mugwort pollen. In the SG, all patients with food allergy were sensitive to birch pollen, with birch and Bet v 1-specific IgE levels higher in this group than in the group without food allergy (p < 0.001). In the AG, Art v 3 was more prevalent among patients with pollen-related food allergy than without food allergy (79% vs. 33%, p < 0.001), a proportion similar to the one in the CG (67% vs. 48%, p = 0.01). Meanwhile, the Art v 3-specific IgE levels among patients with pollen-related food allergy were higher than among tolerant patients in the AG (p < 0.001) and CG (p = 0.02). Unexpectedly, the Art v 3-specific IgE levels were higher in patients with food-induced anaphylaxis than with oral allergy syndrome only in the CG.

Conclusions

Bet v 1 (a Pathogenesis-related 10 protein) and Art v 3 (a non-specific lipid transfer protein; nsLTP) are candidate molecular biomarkers for the diagnosis of food allergies in patients with season-specific pollen-related allergies. Measuring pollen allergen component-specific IgE levels might be an effective tool for the management of pollinosis in clinical practice in China.

Epidemiological study of oral allergy syndrome in birch pollen dispersal-free regions

BACKGROUND

Oral allergy syndrome (OAS) is an immediate allergy caused by a cross-reaction of highly homologous common antigens (pan-allergens) contained in fruits/vegetables and pollen.

METHODS

A questionnaire was provided to 6824 outpatient visitors and serum levels of specific IgEs against crude antigens and pan-allergen components were measured to study the relationship between the prevalence of OAS and pollinosis in the Fukui Prefecture where there is almost no dispersal of birch pollen.

RESULTS

The prevalence of OAS was 10.8%. The rate of pollinosis complication in the OAS group was 67.4%, and OAS was observed in 16.8% of pollinosis patients. Causative foods in order of frequency were melon, pineapple, kiwi fruit, peach, and apple. A significantly higher number of patients from the OAS group were positive for birch, alder, and timothy grass-specific IgE. The rate of positivity for anti-component IgE corresponding to pollen in OAS group was also significantly higher. Of 34 patients with OAS caused by eating apples, 28 (82.4%) were positive for Mal d1-specific IgE. Of the 52 patients with peach-induced OAS, 41 (78.8%) were positive for Pur p1-specific IgE. The concordance rates between crude antigen-specific IgE and anti-PR-10 component-specific IgE were 87.1% and 93.3% for apple and peach respectively.

CONCLUSIONS

In regions where birch pollen is not dispersed, OAS patients have a significant association with the onset of Bet v1-associated allergy. Anti-PR-10 component IgE was useful in diagnosing OAS, and crude antigen-specific IgE was also associated with apple and peach allergies.

Component-Resolved Diagnosis in Food Allergies

Component-resolved diagnostics (CRD) in food allergies is an approach utilized to characterize the molecular components of each allergen involved in a specific IgE (sIgE)-mediated response. In the clinical practice, CRD can improve diagnostic accuracy and assist the physician in many aspects of the allergy work-up. CRD allows for discriminatory co-sensitization versus cross-sensitization phenomena and can be useful to stratify the clinical risk associated with a specific sensitization pattern, in addition to the oral food challenge (OFC). Despite this, there are still some unmet needs, such as the risk of over-prescribing unnecessary elimination diets and adrenaline auto-injectors. Moreover, up until now, none of the identified sIgE cutoff have shown a specificity and sensitivity profile as accurate as the OFC, which is the gold standard in diagnosing food allergies. In light of this, the aim of this review is to summarize the most relevant concepts in the field of CRD in food allergy and to provide a practical approach useful in clinical practice.