Tolerance of peanuts and tree nuts in Spanish children with exclusive sensitization to lipid transfer proteins.

BACKGROUND: Allergy to peanuts and tree nuts is a common cause of food allergy in Spain, with lipid transfer proteins (LTP) being the most frequently recognized panallergen. LTP sensitization often leads to multiple food group sensitivities, resulting in overly restrictive diets that hinder patient's quality of life. This study aimed to assess the tolerance of peanuts and tree nuts (hazelnuts and walnuts) in children sensitized to LTP, potentially mitigating the need for such diets. METHODS: This prospective study enrolled individuals diagnosed with allergy to peanuts, hazelnuts, or walnuts. Data were collected from medical records, including demographics and clinical history. Allergological assessment comprised skin prick tests using commercial extracts and the nuts in question, alongside measurements of total and specific IgE to nuts and their primary molecular components. Participants showing positive LTP sensitization without sensitization to seed storage proteins underwent open oral nut challenges. RESULTS: A total of 75 individuals labeled as allergic to peanuts, 44 to hazelnuts, and 51 to walnuts were included. All of them underwent an open oral provocation test with the incriminated nut, showing a high tolerance rate. Peanut was tolerated by 98.6% of patients, 97.72% tolerated hazelnut, and 84.3% tolerated walnut. CONCLUSION: The findings suggest that the majority of patients allergic to peanuts, hazelnuts, or walnuts, due to LTP sensitization and lacking IgE reactivity to seed storage proteins, can tolerate these nuts. This supports the need for personalized nut tolerance assessments to avoid unnecessary dietary restrictions.

Impact of Presumed Tree Nut and Peanut Allergy on Quality of Life at Different Ages.

Tree nut and/or peanut allergy impairs patients' quality of life, but data on the impact of age and the type of nut or peanut on the quality of life are lacking. To evaluate the impact at different ages, age-appropriate survey questionnaires accompanied by FAQLQ and FAIM were distributed to patients with suspected tree nut and/or peanut allergy who presented at the allergy departments of three hospitals in Athens. Out of 200 questionnaires distributed, 106 met the inclusion criteria (46 children, 26 teenagers, 34 adults). The median score of each age group for FAQLQ was 4.6 (3.3-5.1), 4.7 (3.9-5.5), and 3.9 (3.2-5.1) and for FAIM was 3.7 (3.0-4.0), 3.4 (2.8-4.0), and 3.2 (2.7-4.1), respectively. FAQLQ and FAIM scores were correlated with the reported probability of using the rescue anaphylaxis set upon reaction (15.4%, p = 0.04 and 17.8%, p = 0.02, respectively) and pistachio allergy (FAQLQ: 4.8 vs. 4.0, p = 0.04; FAIM: 3.5 vs. 3.2, p = 0.03). Patients with additional food allergies reported worse FAQLQ scores (4.6 vs. 3.8, p = 0.05). Worse FAIM scores were associated with younger age (-18.2%, p = 0.01) and the number of life-threatening allergic reactions (25.3%, p < 0.001). The overall impact of tree nut and/or peanut allergy on patients' quality of life is moderate but differs with age, the type of nut, the use of adrenaline, and the number of previous reactions. The aspects of life affected and contributed factors also vary across age groups.

Induction of food-specific IgG by Gene Gun-delivered DNA vaccines.

Background: Shellfish and tree nut allergies are among the most prevalent food allergies, now affecting 2%-3% and 1% of the US population, respectively. Currently, there are no approved therapies for shellfish or tree nut allergies, with strict avoidance being the standard of care. However, oral immunotherapy for peanut allergy and subcutaneous immunotherapy for environmental allergens are efficacious and lead to the production of allergen-specific IgG, which causes suppression of allergen effector cell degranulation. Since allergen-specific IgG is a desired response to alleviate IgE-mediated allergies, we tested transcutaneously-delivered DNA vaccines targeting shellfish and tree nut allergens for their ability to induce antigen-specific IgG, which would have therapeutic potential for food allergies. Methods: We assessed Gene Gun-delivered DNA vaccines targeting either crustacean shellfish or walnut/pecan allergens, with or without IL-12, in naïve mice. Three strains of mice, BALB/cJ, C3H/HeJ and CC027/GeniUnc, were evaluated for IgG production following vaccination. Vaccines were administered twice via Gene Gun, three weeks apart and then blood was collected three weeks following the final vaccination. Results: Vaccination with shellfish allergen DNA led to increased shrimp-specific IgG in all three strains, with the highest production in C3H/HeJ from the vaccine alone, whereas the vaccine with IL-12 led to the highest IgG production in BALB/cJ and CC027/GeniUnc mice. Similar IgG production was also induced against lobster and crab allergens. For walnut/pecan vaccines, BALB/cJ and C3H/HeJ mice produced significantly higher walnut- and pecan-specific IgG with the vaccine alone compared to the vaccine with IL-12, while the CC027 mice made significantly higher IgG with the addition of IL-12. Notably, intramuscular administration of the vaccines did not lead to increased antigen-specific IgG production, indicating that Gene Gun administration is a superior delivery modality. Conclusions: Overall, these data demonstrate the utility of DNA vaccines against two lifelong food allergies, shellfish and tree nuts, suggesting their potential as a food allergy therapy in the future.

Multiplex component-based allergen macroarray test is useful to predict clinical reactivity to tree nuts in children.

BACKGROUND: In tree nut (TN) allergy, singleplex tests showed the diagnostic utility of rAna o 3, rCor a 14/nCor a 9, and nJug r 1/nJug r 4 for cashew/pistachio, hazelnut, and walnut allergies, respectively. However, disadvantages of the tests include high costs and excessive blood sampling in multi-sensitized patients, and a limited number of components. We investigated the utility of a multiplex macroarray (i.e., the ALEX2 test) in TN allergy. METHODS: In 169 children, skin prick test, the component- and extract-specific IgEs of TNs were investigated for clinical reactivity and tolerance. RESULTS: The predictors (AUC = 0.962-0.749) of clinical reactivity to cashew, pistachio, hazelnut, and walnut were rPis v 1/rAna o 3, rPis v 1/rAna o 3/nPis v 2/nPis v 3, rCor a 14/nCor a 11/nCor a 9, and nJug r 1/nJug r 2/nJug r 6/nJug r 4, respectively. More than 93% of the patients with clinical reactivity to pistachio/cashew, hazelnut and walnut had positivity of (≥0.3 kUA/L) rPis v 1/rAna o 3, rCor a 14 and nJug r 1/nJug r 2, respectively. The highest accuracies of clinical reactivity to culprit nut were obtained with combination of rPis v 1, sIgE and SPT positivities for cashew/pistachio, rPis v 1 ≥ 1.0 kUA/L for pistachio, rCor a 14 ≥ 1.0 kUA/L for hazelnut and combination of nJug r 1 and nJug r 2 positivities for walnut, respectively. Also, higher concentrations of rPis v 1 (≥15.0 kUA/L), rCor a 14 (≥5.0 kUA/L) and nJug r 1/nJug r 2 (≥15.0 kUA/L) had %100 specificity and PPV in predicting clinical reactivity to cashew, hazelnut and walnut, respectively. CONCLUSIONS: Multiplex macroarray test is useful and reliable in the diagnosis of TN allergy in children, confirms and expands existing knowledge, and can be used as a stand-alone tool in the bottom-up diagnostic approach.

Walnut Allergy Across Europe: Distribution of Allergen Sensitization Patterns and Prediction of Severity.

BACKGROUND: Walnut allergy is common across the globe, but data on the involvement of individual walnut components are scarce. OBJECTIVES: To identify geographical differences in walnut component sensitization across Europe, explore cosensitization and cross-reactivity, and assess associations of clinical and serological determinants with severity of walnut allergy. METHODS: As part of the EuroPrevall outpatient surveys in 12 European cities, standardized clinical evaluation was conducted in 531 individuals reporting symptoms to walnut, with sensitization to all known walnut components assessed in 202 subjects. Multivariable Lasso regression was applied to investigate predictors for walnut allergy severity. RESULTS: Birch-pollen-related walnut sensitization (Jug r 5) dominated in Northern and Central Europe and lipid transfer protein sensitization (Jug r 3) in Southern Europe. Profilin sensitization (Jug r 7) was prominent throughout Europe. Sensitization to storage proteins (Jug r 1, 2, 4, and 6) was detected in up to 10% of subjects. The walnut components that showed strong correlations with pollen and other foods differed between centers. The combination of determinants best predicting walnut allergy severity were symptoms upon skin contact with walnut, atopic dermatitis (ever), family history of atopic disease, mugwort pollen allergy, sensitization to cat or dog, positive skin prick test result to walnut, and IgE to Jug r 1, 5, 7, or carbohydrate determinants (area under the curve = 0.81; 95% CI, 0.73-0.89). CONCLUSIONS: Walnut-allergic subjects across Europe show clear geographical differences in walnut component sensitization and cosensitization patterns. A predictive model combining results from component-based serology testing with results from extract-based testing and information on clinical background allows for good discrimination between mild to moderate and severe walnut allergy.

Model of Walnut Allergy in CC027/GeniUnc Mice Recapitulates Key Features of Human Disease.

Tree nut allergies affect 1% of the United States population, are often severe in nature and rarely outgrown. Despite the severity and prevalence, there are no FDA-approved treatments for tree nut allergy. Development of a therapeutic would be expedited by having a mouse model that mimics the human disease. We utilized the CC027/GeniUnc mouse strain, which was previously identified as an orally reactive model of peanut allergy, to develop a model of walnut allergy. Mice were sensitized with walnut and cholera toxin for 4 weeks and subsequently challenged by oral gavage. Blood samples were collected to measure serum IgE. Walnut-sensitized mice produced high levels of walnut-IgE and were cross-sensitized to pecan. Oral challenges with walnut resulted in severe anaphylaxis and accompanying allergic symptoms. Importantly, pecan challenges also led to severe allergic reactions, indicating cross-reactivity to pecan. Overall, this novel mouse model reproduces key characteristics of human walnut allergy, which provides a platform to develop novel therapies and better understand sensitization mechanisms.

Epitopes with similar physicochemical properties contribute to cross reactivity between peanut and tree nuts.

Many individuals with peanut (PN) allergy have severe reactions to tree nuts (TN) such as walnuts or cashews. Although allergenic proteins in TN and PN have overall low identity, they share discrete sequences similar in physicochemical properties (PCP) to known IgE epitopes. Here, PCP-consensus peptides (cp, 13 aa and 31 aa) were identified from an alignment of epitope rich regions of walnut vicilin, Jug r 2, leader sequence (J2LS) and cross-reactive epitopes in the 2S albumins of peanut and synthesized. A peptide similarity search in the Structural Database of Allergenic Proteins (SDAP) revealed a network of peptides similar (low property distance, PD) to the 13 aa cp (13cp) in many different plant allergens. Peptides similar to the 13cp in PN and TN allergens bound IgE from sera of patients allergic to PN and TN in peptide microarray analysis. The 13cp was used to produce a rabbit consensus peptide antibody (cpAB) that detected proteins containing repeats similar to the 13cp in western blots of various nut extracts, in which reactive proteins were identified by mass spectrometry. The cpAB bound more specifically to allergens and nut extracts containing multiple repeats similar to the 13 cp, such as almond (Pru du 6), peanut (Ara h 2) and walnut (Jug r 2). IgE binding to various nut extracts is inhibited by recombinant J2LS sequence and synthetic 31cp. Thus, several repeated sequences similar to the 13cp are bound by IgE. Multiple similar repeats in several allergens could account for reaction severity and clinically relevant cross-reactivity to PN and TN. These findings may help improve detection, diagnostic, and therapeutic tools.

Retrospective definition of reaction risk in Italian children with peanut, hazelnut and walnut allergy through component-resolved diagnosis.

BACKGROUND: Serum IgE evaluation of peanut, hazelnut and walnut allergens through the use of component-resolved diagnosis (CRD) can be more accurate than IgE against whole food to associate with severe or mild reactions. OBJECTIVES: The aim of the study was to retrospectively define the level of reaction risk in children with peanut, hazelnut and walnut sensitization through the use of CRD. METHODS: 34 patients [n=22 males, 65%; median age eight years, interquartile range (IQR) 5.0-11.0 years] with a reported history of reactions to peanut and/or hazelnut and/or walnut had their serum analyzed for specific IgE (s-IgE) by ImmunoCAP® and ISAC® microarray technique. RESULTS: In children with previous reactions to peanut, the positivity of Arah1 and Arah2 s-IgE was associated with a history of anaphylaxis to such food, while the positivity of Arah8 s-IgE were associated with mild reactions. Regarding hazelnut, the presence of positive Cora9 and, particularly, Cora14 s-IgE was associated with a history of anaphylaxis, while positive Cora1.0401 s-IgE were associated with mild reactions. Concerning walnut, the presence of positive Jug r 1, Jug r 2, Jug r 3 s-IgE was associated with a history of anaphylaxis to such food. ImmmunoCAP® proved to be more useful in retrospectively defining the risk of hazelnut anaphylaxis, because of the possibility of measuring Cor a14 s-IgE. CONCLUSIONS: Our data show that the use of CRD in patients with allergy to peanut, hazelnut and walnut could allow for greater accuracy in retrospectively defining the risk of anaphylactic reaction to such foods.

Is There Any Necessity to Prescribe Consumption of Walnuts Cooked by Different Processing Techniques to Patients With Walnut Allergy?

The present study focused on identifying the usual methods of cooking walnuts in order to investigate changes in walnut allergen activity caused by cooking and evaluated the allergenic changes in walnut proteins within raw, dry-fried and boiled walnuts. Previous studies have reported a decrease in the allergen activity of walnut by thermal processing methods, which are not used in Korean kitchens, such as dry-frying and boiling. In Korea, Walnuts are consumed with rice and usually boiled and stir-fried with seasoning. Thus, the present study clarified the protein bands corresponding to raw walnuts and confirmed that the patterns of each walnut protein differ depending on cooking methods. This concern may be a very crucial point to understand the other tree nuts allergy as well as walnut allergy. The results of the present study differ from those of previous studies performed in Europe, although further studies with older participants are needed in order to draw more definite conclusions on lipid transfer protein (LTP). The other crucial point is that the findings of the present study support existing findings that the allergenic components of walnut have varying antigenicity depending on cooking methods. The allergenic components of walnut identified using diagnostic tests for walnut allergic patients could be reduced in walnuts cooked by different processing techniques. The allergenic components of walnut have varying allergen activity depending on cooking methods. Therefore, the allergenic components of walnuts identified using diagnostic tests for walnut allergic patients could allow physicians to prescribe consumption of walnuts cooked by different processing techniques to patients with walnut allergy.

A subset of walnut allergic adults is sensitized to walnut 11S globulin Jug r 4.

BACKGROUND: The role of sensitization to commercially available allergens of English walnut (Juglans regia) Jug r 1, 2 and 3 in walnut allergy has been previously investigated in walnut allergic adults and was unable to explain all cases of walnut allergy. OBJECTIVES: Identify recognized walnut allergens, other than the ones previously investigated (Jug r 1-3), in walnut allergic adults and determine the sensitization frequency and diagnostic value. METHODS: Three different in-house walnut extracts were prepared and analysed on SDS-PAGE blots to identify allergenic walnut proteins. Immunoblots and immunoprecipitation, followed by LC-MS analysis, were performed to screen for, and confirm, IgE binding to walnut allergens in selected walnut allergic adults. In a cohort of 55 walnut challenged adults, including 33 allergic and 22 tolerant, sensitization to native and recombinant walnut allergen Jug r 4 was assessed using immunoblotting and immuno-line blot (EUROLINE), respectively. RESULTS: Screening of sera of 8 walnut allergic adults identified Jug r 4 as an allergen in our population. In the total cohort of 55 subjects, 5 were positive for Jug r 4 on immunoblot and 10 on EUROLINE. All but one EUROLINE positive subject had a positive food challenge (sensitivity 27%, specificity 95%, PPV 90%, NPV 47%). All 5 subjects positive on immunoblot were also positive on EUROLINE. LC-MS analysis showed a lack of Jug r 4 in the ImmunoCAP extract. Co-sensitization to other 11S albumins (eg hazelnut Cor a 9) was common in Jug r 4 sensitized subjects, potentially due to cross-reactivity. CONCLUSIONS: Walnut 11S globulin Jug r 4 is a relevant minor allergen, recognized by 27% of walnut allergic adults. It has a high positive predictive value of 90% for walnut allergy. Specific IgE against Jug r 4 occurred mostly with concomitant sensitization to other walnut components, mainly Jug r 1.

Identification and implication of an allergenic PR-10 protein from walnut in birch pollen associated walnut allergy.

SCOPE: English walnut (Juglans regia) belongs to the most important allergenic tree nuts. Co-sensitization with birch (Betula verrucosa) pollen has been reported. We aimed to identify a walnut allergen homologous to the major birch pollen allergen Bet v 1. METHODS AND RESULTS: A cDNA encoding a Bet v 1-homologous allergen (Jug r 5) in walnut kernels was cloned by RT-PCR. Jug r 5 was expressed in Escherichia coli, purified by column chromatography and characterized by circular dichroism spectroscopy. Specific IgE levels to walnut, Bet v 1, and Jug r 5 in birch pollen allergics (n = 16) with concomitant walnut allergy were measured by ImmunoCAP: 44% of the patients were tested positive to walnut while 94% were reactive to Jug r 5, and 100% to Bet v 1. Jug r 5 and Bet v 1 allergens showed bidirectional IgE cross-reactivity by competitive ELISA and were capable of inducing histamine release from effector cells. Immunoblot competition experiments demonstrated the presence of IgE-reactive Jug r 5 in walnut extract, but at low levels. CONCLUSION: A Bet v 1-like allergen was identified in walnut. Diagnostic use of Jug r 5 will compensate for the low sensitivity of walnut extract for patients with birch pollen associated walnut allergy.

Allergenic properties and differential response of walnut subjected to processing treatments.

The aim of this study was to investigate changes in walnut allergenicity after processing treatments by in vitro techniques and physiologically relevant assays. The allergenicity of walnuts subjected to high hydrostatic pressure and thermal/pressure treatments was evaluated by IgE-immunoblot and antibodies against walnut major allergen Jug r 4. The ability of processed walnut to cross-link IgE on effector cells was evaluated using a rat basophil leukaemia cell line and by skin prick testing. Susceptibility to gastric and duodenal digestion was also evaluated. The results showed that walnuts subjected to pressure treatment at 256 kPa, 138 °C, were able to diminish the IgE cross-linking capacity on effector cells more efficiently than high pressure treated walnuts. IgE immunoblot confirmed these results. Moreover, higher susceptibility to digestion of pressure treated walnut proteins was observed. The use of processed walnuts with decreased IgE binding capacity could be a potential strategy for walnut tolerance induction.

Prevalence of parent-reported immediate hypersensitivity food allergy in Chilean school-aged children.

BACKGROUND: Food allergies (FAs) affect 2-4% of school-aged children in developed countries and strongly impact their quality of life. The prevalence of FA in Chile remains unknown. METHODS: Cross-sectional survey study of 488 parents of school-aged children from Santiago who were asked to complete a FA screening questionnaire. Parents who reported symptoms suggestive of FA were contacted to answer a second in-depth questionnaire to determine immediate hypersensitivity FA prevalence and clinical characteristics of school-aged Chilean children. RESULTS: A total of 455 parents answered the screening questionnaire: 13% reported recurrent symptoms to a particular food and 6% reported FA. Forty-three screening questionnaires (9%) were found to be suggestive of FA. Parents of 40 children answered the second questionnaire; 25 were considered by authors to have FA. FA rate was 5.5% (95% CI: 3.6-7.9). Foods reported to frequently cause FA included walnut, peanut, egg, chocolate, avocado, and banana. Children with FA had more asthma (20% vs. 7%, P<0.02) and atopic dermatitis (32% vs. 13%, P<0.01) by report. The parents of children with FA did not report anaphylaxis, but 48% had history compatible with anaphylaxis. Of 13 children who sought medical attention, 70% were diagnosed with FA; none were advised to acquire an epinephrine autoinjector. CONCLUSION: Up to 5.5% of school-aged Chilean children may suffer from FA, most frequently to walnut and peanut. It is critical to raise awareness in Chile regarding FA and recognition of anaphylaxis, and promote epinephrine autoinjectors in affected children.