Pru p 3-specific IgE affinity is crucial in severe peach-allergy patients

Background

Peach allergy is common food allergen. Allergen components-specific antibodies of different isotypes in peach-allergy patients are poorly studied. Factors other than Pru p 3-sIgE levels may be related to severe symptoms.

Objective

To evaluated peach component-specific-IgE, IgG1, and IgG4 characteristics in individuals with and without peach allergy, and Pru p 3-sIgE affinity in patients with different clinical symptoms.

Methods

Fifteen healthy controls and 32 peach-allergy patients were enrolled. sIgE, sIgG1, and sIgG4 to 5 Escherichia coli-expressed peach-allergen components were determined by enzyme-linked immunosorbent assays. Pru p 3-sIgE affinity was measured in Pru p 3-sIgE-positive patients, using immunoadsorbance.

Results

Patients were divided into oral allergy syndrome (OAS) and peach-induced anaphylaxis (PIA) groups. Serum Pru p 1-, Pru p 2-, Pru p 3-, Pru p 4-, and Pru p 7-sIgG1s were detected. Pru p 1- and Pru p 2-sIgG1 levels were higher in healthy controls, but Pru p 3-sIgG1 levels were significantly higher in peach-allergy patients. Pru p 1-, Pru p 3-, and Pru p 4-sIgG4-positivity was significantly greater among patients than among controls. Pru p 3 was the predominant allergen in peach-allergy patients. Allergen-sIgG1 and sIgG4 were similar between OAS and PIA patients. Pru p 3-sIgE levels were significantly higher in PIA patients, but Pru p 3-sIgE-positivity was similar in both groups. In Pru p 3-sIgE-positive patients, Pru p 3-sIgE affinity was significantly higher in PIA than OAS patients.

Conclusions

Allergen-sIgG1 was associated with allergen exposure. Both Pru p 3-sIgE levels and affinity are key factors in severe peach-allergy patients.

Precision allergy molecular diagnosis applications in food allergy

PURPOSE OF REVIEW

Precision medicine has become important in the diagnosis and management of food allergies. This review summarizes the latest information regarding molecular allergology, an essential component of food allergy managements.

RECENT FINDINGS

Component-resolved diagnostics (CRD) can be used to investigate sensitization to allergens based on symptoms and to reveal co-sensitization and/or cross-sensitization in patients with allergies. The following allergen components are known to be associated with symptoms: ovomucoid from eggs, omega-5 gliadin from wheat, and many storage proteins (Gly m 8 from soy, Ara h 2 from peanut, Cor a 14 from hazelnut, Ana o 3 from cashew nut, Jug r 1 from walnut, and Ses i 1 from sesame). Recent studies on allergens of macadamia nuts (Mac i 1 and Mac i 2), almonds (Pru du 6), fish (parvalbumin and collagen), and shrimp (Pem m 1 and Pem m 14) have provided additional information regarding CRD. In addition, Pru p 7 is a risk factor for systemic reactions to peaches and has recently been found to cross-react with cypress and Japanese cedar pollen.

SUMMARY

CRD provides information of individualized sensitization profiles related to symptoms and severity of allergies in patients. Clinical practice based on CRD offers many benefits, such as higher diagnostic accuracy and improved management of individual patients.

Optimization of the diagnosis and characterization of gibberellin-regulated protein sensitization: An Italian cohort study

BACKGROUND

Pru p 7 was the first gibberellin-regulated protein (GRP) to be identified as a food allergen as the basis of a pollen food allergy syndrome.

OBJECTIVE

To clinically and biologically characterize a group of patients with suspected allergy to Pru p 7 to optimize the diagnostic workup of GRP sensitization.

METHODS

Allergy to Pru p 7 was suspected in the presence of a systemic allergic reaction to plant food, positive skin prick test results for cypress pollen and lipid-transfer protein-enriched peach extract, and absence of Pru p 3-specific immunoglobulin E. Controls were patients with food allergies, patients sensitized to Pru p 3, and patients with cypress allergy without food allergy. Diagnostic workup included skin tests, basophil activation test, Western blot, and single and multiplex assays.

RESULTS

In total, 23 patients and 14 controls were enrolled. The most implicated food was peach (91.3%). Approximately 70% of patients reacted to multiple foods. Mueller 4 reactions were 8.7%. In 26.1% of cases, a cofactor triggered the reaction. The basophil activation test results were positive for rPru p 7 in 87% of the patients. Specific immunoglobulin E to Pru p 7 was detected in 95.7% by singleplex and in 73.9% by multiplex assays in patients with suspected allergies; 73.9% of them also reacted to cypress pollen GRP (Cup s 7) in Western blot analysis.

CONCLUSION

Patients with Pru p 7-Cup s 7 allergy in our cohort confirm a mild-to-severe clinical syndrome characterized by pollen and food allergy. The diagnosis may benefit from the proposed selection criteria that can be used as preliminary steps to further characterize the cross-reactive GRP sensitization.

A European-Japanese study on peach allergy: IgE to Pru p 7 associates with severity

BACKGROUND

Pru p 3 and Pru p 7 have been implicated as risk factors for severe peach allergy. This study aimed to establish sensitization patterns to five peach components across Europe and in Japan, to explore their relation to pollen and foods and to predict symptom severity.

METHODS

In twelve European (EuroPrevall project) and one Japanese outpatient clinic, a standardized clinical evaluation was conducted in 1231 patients who reported symptoms to peach and/or were sensitized to peach. Specific IgE against Pru p 1, 2, 3, 4 and 7 and against Cup s 7 was measured in 474 of them. Univariable and multivariable Lasso regression was applied to identify combinations of parameters predicting severity.

RESULTS

Sensitization to Pru p 3 dominated in Southern Europe but was also quite common in Northern and Central Europe. Sensitization to Pru p 7 was low and variable in the European centers but very dominant in Japan. Severity could be predicted by a model combining age of onset of peach allergy, probable mugwort, Parietaria pollen and latex allergy, and sensitization to Japanese cedar pollen, Pru p 4 and Pru p 7 which resulted in an AUC of 0.73 (95% CI 0.73-0.74). Pru p 3 tended to be a risk factor in South Europe only.

CONCLUSIONS

Pru p 7 was confirmed as a significant risk factor for severe peach allergy in Europe and Japan. Combining outcomes from clinical and demographic background with serology resulted in a model that could better predict severity than CRD alone.

Effect of ultrahigh-pressure treatment on the structure and allergenicity of peach allergenic proteins

Peach is a common plant-derived allergenic food and ultrahigh-pressure treatment is often used in peach products. In our study, an in-depth analysis of the structural and allergenicity changes of peach allergenic proteins after UHP treatment was performed by spectroscopy, mass spectrometry combined with serology and cytology. The results indicated that UHP treatment could reduce the content of peach soluble proteins and cause changes in secondary and tertiary structures. In addition, more hydrophobic residues were exposed and proteins tended to polymerize after UHP-treatment. The results of immunological assays showed that UHP treatment could reduce the IgE binding capacity of peach proteins and affect the ability of basophil degranulation, the upregulation of some cytokines may contribute to the reduction of peach protein allergenicity. Notably, UHP treatment may lead to the masking of some digestion sites in Pru p 3 epitopes, thus impeding human digestion and increasing the potential risk of allergenicity.

Generalized allergic reaction in response to exercise due to strawberry gibberellin-regulated protein: a case report

Background

The Rosaceae family includes fruits, such as peach, apple, Japanese apricot, cherry (Prunoideae subfamily), and strawberry (Rosoideae subfamily). The allergens responsible for Rosaceae fruit allergies have been reported to include Bet v 1 and profilin, which mainly cause oral symptoms, and lipid transfer protein (LTP). Recently, gibberellin-regulated protein (GRP) has been identified as an allergen that induces generalized symptoms in peach-, orange-, and plum-related allergies. Most patients with food allergies induced by GRP show allergic symptoms accompanied by cofactors, such as exercise or drugs. To date, there are very few reports of generalized symptoms induced by strawberry.

Case presentation

We evaluated the reactivity of strawberry GRP in a 15-year-old boy who was confirmed to have generalized symptoms induced by strawberry with exercise using an oral food challenge test (OFCT). The patient’s serum exhibited a strong positive reaction to strawberry GRP but not to peach GRP or peach LTP. The patient’s basophils reacted to strawberry and peach GRP but not to peach LTP.

Conclusions

Strawberry GRP may be a causative component for strawberry with exercise-induced generalized symptoms in this patient. This is the first study to investigate the role of GRP in strawberry with cofactor-induced allergic symptoms. Further epidemiological and clinical researches are necessary to improve diagnostic and therapeutic approaches for patients with strawberry allergy.

Molecular diagnosis contribution for personalized medicine

PURPOSE OF REVIEW

The purpose of the current review is to highlight the most recent findings in molecular allergy and its applicability in precision medicine for allergic patients.

RECENT FINDINGS

Molecular allergy provides useful information in areas of respiratory allergy (house dust mites, pet dander and pollen allergy), food allergy (tree nuts, peanuts, fruits and vegetables), hymenoptera venom allergy and others, in order to improve management of patients. Regional differences in sensitization profiles, assay characteristics and interpretation of molecular sensitization in relation to whole extracts and total immunoglobulin E need to be taken into account. Studies of the impact of such strategies are needed.

SUMMARY

Molecular allergy diagnosis represents a major contribution for personalized medicine. It aids in the assesment of risk prediction, disease severity, genuine/cross-reactive sensitization, and finally to apply precise management strategies.

Phenotypes and Endotypes of Peach Allergy: What Is New?

Peach allergy is emerging as a common type of fresh-fruit allergy in Europe, especially in the Mediterranean area. The clinical manifestations of peach allergy tend to have a peculiar geographical distribution and can range from mild oral symptoms to anaphylaxis, depending on the allergic sensitization profile. The peach allergen Pru p 7, also known as peamaclein, has recently been identified as a marker of peach allergy severity and as being responsible for peculiar clinical features in areas with high exposure to cypress pollen. This review addresses the latest findings on molecular allergens for the diagnosis of peach allergy, the clinical phenotypes and endotypes of peach allergy in adults and children, and management strategies, including immunotherapy, for peach allergy.

Allergenic Properties and Molecular Characteristics of PR-1 Proteins

Only a small fraction of proteins in plants and animals are classified as allergens. The allergenic properties are frequently attributed to certain functional characteristics of the proteins, such as a role in the plant defense against biotic and abiotic stress, to achieve the systematic acquired resistance. In line with this, eight members out of 17 functional pathogenesis-related (PR) protein families have been characterized as allergens. The present review summarizes the molecular features and allergenic significance of allergens of the PR-1 family. Not many allergens have been identified as belonging to this protein family, with most of them having a pollen origin, like mugwort or Bermuda grass. Molecular and structural features of allergenic PR-1 proteins are discussed and attributed to their IgE-reactive properties, clinical manifestation, and cross-reactivity among different foods and inhalants.

Skin Testing With Peach Peel Extract Versus Serum IgE to Pru p 3 as a Stronger Predictor of Peach-Induced Anaphylaxis

The most important peach fruit allergen is Pru p 3, followed by Pru p 1, Pru p 4, and Pru p 7. We aimed to assess their role in subjects with peach fruit-induced allergy (anaphylaxis and OAS) and compare skin prick tests (SPT) vs. specific immunoglobulin E (sIgE) for predicting anaphylaxis. We also selected a control group. SPT included prevalent inhalant and plant food allergens plus peach peel extract. The sIgE to Pru p 1, Pru p 3, Pru p 4, and Pru p 7 were quantified. Compared with controls (n = 42), cases (n = 41) were younger (P = 0.003), more frequently female (P < 0.05) and had higher SPT positivity to peach peel (44% vs. 2.4%, P < 0.0001). There were significant differences in sensitization to several pollens: Olea europaea, Artemisia vulgaris, Prunus persica, Platanus acerifolia (all P < 0.001); and fruits: apple (P < 0.04), peanut (P < 0.002), tomato (P < 0.005), and melon (P < 0.05). Pru p 3 sIgE was detected in 61% of all cases (85% anaphylaxis and 38% OAS; P < 0.01 each) and 5% of controls (P < 0.001). Pru p 4 sIgE was present in 19% of cases and 7% of controls. The sIgE to Pru p 1 and Pru p 7 were not found. The odds ratio to predict anaphylaxis for peach peel SPT was 113 (confidence interval [CI], 20–613; P < 0.0001); for sIgE to Pru p 3, 22 (CI, 5.3–93; P < 0.0001); and for SPT positivity to selected plant food allergens, 5 (CI, 1–19; P < 0.05). In our study group, SPT with peel peach extract was a better predictor of anaphylaxis than Pru p 3 sIgE or other variables considered. The role of sIgE to Pru p 1, Pru p 4, and Pru p 7 seemed negligible.

When the Frequencies of Sensitization and Elicitation of Allergic Reaction Do Not Correlate-The Case of Apple Gibberellin-Regulated Protein Tested in an Italian Population

Background: The literature reports describing allergic symptoms against apples in the patients sensitized to the gibberellin-regulated proteins (GRPs) suggested the presence of an allergenic GRP in this fruit. Objective: This study aimed to assess the presence of a GRP protein in apples and investigate its allergenicity. Methods: The protein was isolated and identified by the classical biochemical methods. The bioinformatics tools were used for similar searches and molecular modeling. The immunological features were investigated using the multiplex FABER test. Clinical data were collected by the allergy specialists. Results: A GRP was detected in the apple peel and pulp and it was named applemaclein. This protein displays 94% of sequence identity with peamaclein, Pru p 7, representing the prototype of this allergen family. The applemaclein molecular model shows a very irregular surface with grooves/clefts that may potentially accommodate small molecular ligands. In a population of 4,721 patients in Italy, 187 (4.0%) were sensitized to any allergenic GPR. Of those, 115 (61.5%), 61 (32.6%), 30 (16.0%), and 99 (52.9%) had immunoglobulin E (IgE) to apple, peach, pomegranate, and cypress GRP, respectively. However, in a cohort of the patients in Italy, most individuals IgE positive to the apple GRP did not report allergic reactions against this fruit. Conclusion: Compared with the peach Pru p 7, applemaclein shows some different structural features and higher sensitization frequency, which is often not associated with allergic reactions against apple. Further studies are needed to understand a possible correlation between the applemaclein structural properties, the interaction with still unknown molecules, and immunological behavior.

Food Allergy Evaluation for Dermatologic Disorders

Food allergy evaluation for dermatologic disorders is warranted when Type 1 allergy is suspected, and includes skin prick testing (SPT) or measurement of specific immunoglobulin E (IgE) levels. The utility of these tests for identifying triggers is improved with clinical correlation, especially for contact urticaria, and protein contact dermatitis, which are mixed mechanism diseases. In atopic dermatitis (AD), patients are at risk for development of food allergy, and screening with SPT or IgE may be considered in severe AD, especially to guide early food introduction. Management of food-related AD exacerbations should focus on modifications in skincare before evaluating for allergy.

Components of plant-derived food allergens: Structure, diagnostics, and immunotherapy

A large number of plant-derived food allergen components have been identified to date. Although these allergens are diverse, they often share common structural features such as numerous disulfide bonds or oligomeric structures. Furthermore, some plant-derived food allergen components cross-react with pollen allergens. Since the relationship between allergen components and clinical symptoms has been well characterized, measurements of specific IgE to these components have become useful for the accurate clinical diagnosis and selection of optimal treatment methods for various allergy-related conditions including allergy caused by plant-derived foods. Herein, I have described the types and structures of different plant allergen components and outlined the diagnosis as well as treatment strategies, including those reported recently, for such substances. Furthermore, I have also highlighted the contribution of allergen components to this field.