Peanut cross-contamination in randomly selected baked goods.

BACKGROUND: The current standard of care for managing peanut allergy includes avoidance of peanut and use of injectable epinephrine; however, strict avoidance is difficult and accidental ingestion is common with potentially serious consequences. Despite vigilance and efforts to minimize the risk of accidental exposure, peanut protein cross-contamination continues to occur in a variety of foods, including baked goods. OBJECTIVE: To assess and quantify the presence of peanut protein contamination in certain baked goods. METHODS: Randomly selected baked goods were collected from bakeries in the New York and Miami metropolitan areas that sold a variety of ethnic cuisines. A second set of samples from the same bakeries was collected at least 1 week after to evaluate between-batch variability. Samples were sent to the Food Allergy Research and Resource Program to analyze peanut contamination by enzyme-linked immunosorbent assay. Consumption estimates were based on 2003 to 2010 National Health and Nutrition Examination Survey survey data. RESULTS: Of 154 samples from 18 bakeries, 4 (2.6%) had detectable peanut contamination with peanut protein levels ranging from 0.1 mg/100 g to 650 mg/100 g. Consumption estimates for single occasion ingestion of a contaminated item ranged from 0.07 mg to 832 mg of peanut protein. CONCLUSION: In this study, unintended peanut protein was present in a small, but not insignificant, proportion of baked goods, with the potential to trigger a reaction in individuals with peanut allergy. Some products contained high levels of unintended peanut protein. The current data support the potential for accidental exposure to peanut protein with its associated risk.

The importance of the 2S albumins for allergenicity and cross-reactivity of peanuts, tree nuts, and sesame seeds.

Allergies to peanuts, tree nuts, and sesame seeds are among the most important food-related causes of anaphylaxis. Important clinical questions include: Why is there a variable occurrence of coallergy among these foods and Is this immunologically mediated? The clinical and immunologic data summarized here suggest an immunologic basis for these coallergies that is based on similarities among the 2S albumins. Data from component resolved diagnostics have highlighted the relationship between IgE binding to these allergens and the presence of IgE-mediated food allergy. Furthermore, in vitro and in vivo experiments provide strong evidence that the 2S albumins are the most important allergens in peanuts for inducing an allergic effector response. Although the 2S albumins are diverse, they have a common disulfide-linked core with similar physicochemical properties that make them prime candidates to explain much of the observed coallergy among peanuts, tree nuts, and sesame seeds. The well-established frequency of cashew and pistachio nut coallergy (64%-100%) highlights how the structural similarities among their 2S albumins may account for observed clinical cross-reactivity. A complete understanding of the physicochemical properties of the 2S albumins in peanuts, tree nuts, and sesame seeds will enhance our ability to diagnose, treat, and ultimately prevent these allergies.

Risk of shared equipment in restaurants for consumers with peanut allergy: a simulation for preparing Asian foods: A simulation for preparing Asian foods.

BACKGROUND: Allergic reactions to meals consumed outside the home are common and can be severe and sometimes fatal. OBJECTIVE: To quantify the risk reduction potentially achieved by increasing an individual's threshold sensitivity to peanut (such as by means of immunotherapy) in scenarios of peanut exposure through shared kitchen materials in a restaurant setting. METHODS: Three versions of popular peanut-containing sauces were selected to represent common ingredients used in Asian cooking. Different combinations of utensils, equipment, sauces, and test conditions were prepared by a professional chef, with or without common cleaning procedures, to represent normal daily practice. Residue amounts of peanut-containing material on kitchen equipment and utensils were measured and used for quantitative risk assessment to model the risk reduction associated with increasing an individual's threshold. RESULTS: Shared utensils had mean residue amounts of 23 to 1519 mg peanut protein (no cleaning) and 3 to 82 mg peanut protein (after water rinse). Shared woks and pans had up to 20 mg peanut protein after rinsing. Individuals who reach a threshold of 300 mg peanut protein have a predicted relative risk reduction of 94.9% to greater than 99.99% with brief cleaning. With no cleaning, relative risk reductions were 63.5% to 91.1% for individuals with a baseline threshold of less than or equal to 100 mg peanut protein who reach a threshold of 300 mg peanut protein, increasing to 91% to 99.7% when reaching a threshold value of 1000 mg peanut protein. CONCLUSION: In all shared kitchen material scenarios that we studied, achieving an eliciting dose of 300 or 1000 mg peanut protein seems clinically relevant for the peanut-allergic population.

Chemically modified peanut extract shows increased safety while maintaining immunogenicity.

BACKGROUND: Peanuts are most responsible for food-induced anaphylaxis in adults in developed countries. An effective and safe immunotherapy is urgently needed. The aim of this study was to investigate the immunogenicity, allergenicity, and immunotherapeutic efficacy of a well-characterized chemically modified peanut extract (MPE) adsorbed to Al(OH)3 . METHODS: Peanut extract (PE) was modified by reduction and alkylation. Using sera of peanut-allergic patients, competitive IgE-binding assays and mediator release assays were performed. The immunogenicity of MPE was evaluated by measuring activation of human PE-specific T-cell lines and the induction of PE-specific IgG in mice. The safety and efficacy of MPE adsorbed to Al(OH)3 was tested in two mouse models by measuring allergic manifestations upon peanut challenge in peanut-allergic mice. RESULTS: Compared to PE, the IgE-binding and capacity to induce allergic symptoms of MPE were lower in all patients. PE and MPE displayed similar immunogenicity in vivo and in vitro. In mice sensitized to PE, the threshold for anaphylaxis (drop in BT) upon subcutaneous challenge with PE was 0.01 mg, while at 0.3 mg MPE no allergic reaction occurred. Anaphylaxis was not observed when PE and MPE were fully adsorbed to Al(OH)3 . Both PE and MPE + Al(OH)3 showed to be efficacious in a model for immunotherapy. CONCLUSION: In our studies, an Al(OH)3 adsorbed MPE showed reduced allergenicity compared to unmodified PE, while the efficacy of immunotherapy is maintained. The preclinical data presented in this study supports further development of modified peanut allergens for IT.

Estimated risk reduction to packaged food reactions by epicutaneous immunotherapy (EPIT) for peanut allergy.

BACKGROUND: Peanut allergy is a generally persistent, sometimes life-threatening food allergy. With no treatments demonstrating the ability to cure a food allergy, the focus of drugs in development has been on providing a level of protection against accidental exposure reactions. However, no study has estimated the relative risk reduction of a food-allergic population receiving a specific immunotherapeutic treatment for their allergies. OBJECTIVE: To estimate the relative risk reduction when consuming peanut-contaminated packaged food products in a double-blind, placebo-controlled Phase 3 study population of children treated with epicutaneous immunotherapy (EPIT) for 12 months with either a patch containing 250 µg peanut protein (250-µg patch) or a placebo patch. METHODS: The probability of an allergic reaction due to the unintended presence of peanut protein in packaged food products was modeled per study group and food category combination using Monte Carlo simulations. Risks per eating occasion of a contaminated packaged food product and the number of individuals per study population predicted to react on a yearly basis were investigated. RESULTS: The population treated with the 250-µg patch demonstrated a significantly increased dose-response distribution after 12 months of treatment, which resulted in a relative risk reduction of 73.2% to 78.4% when consuming peanut-contaminated packaged food products. In contrast, no statistically significant change was observed for the placebo group at the 12-month point. CONCLUSION: Our study estimates a substantial relative risk reduction for allergic reactions among peanut-allergic children after 12 months of EPIT with the 250-µg patch, supporting the potential real-world clinical relevance of this investigational immunotherapy and its possible role as a future therapy for peanut-allergic children. ClinicalTrials.gov Identifier: NCT02636699.

Quantitative risk reduction through peanut immunotherapy: Safety benefits of an increased threshold in Europe.

BACKGROUND: The clinical relevance of increasing an allergic individual's peanut sensitivity threshold by immunotherapy, that is, eliciting dose (ED) to 300 or 1000 mg peanut protein, has not been previously characterized in a European population. In this study, we quantify the clinical benefits of an increased threshold of reaction following immunotherapy for the peanut-allergic individual. METHODS: Quantitative risk assessments incorporated numerous inputs to predict the risk of an allergic reaction after exposure to residual peanut protein in packaged foods. The three primary inputs for the risk assessment were the peanut-allergic individual's clinical threshold value, the amount of food consumed per eating occasion of selected packaged foods, and the concentration of peanut protein in the consumed product. Individual risk reductions were calculated for both children and adolescents-adults. RESULTS: Using available consumption and packaged food contamination data, children reaching an ED of 300 mg (if initial ED ≤ 100 mg) or 1000 mg (if initial ED 300 mg) achieved >99.99% risk reduction. Adolescents-adults also achieved >99.99% risk reduction in all cases but one. Adolescents-adults who reached an ED of 300 mg (if initial ED ≤ 100 mg) achieved 99.3%-99.9% risk reduction when consuming ice cream. CONCLUSIONS: It is concluded that an increase in threshold following immunotherapy which achieves an eliciting dose of 300 or 1000 mg peanut protein is clinically relevant for the European peanut-allergic population. Benefits of an increased threshold include a significant reduction in risk due to traces of peanut protein.

Effect of chemical modifications on allergenic potency of peanut proteins.

BACKGROUND: Modification of native peanut extracts could reduce adverse effects of peanut immunotherapy. OBJECTIVE: We sought to compare native and chemically modified crude peanut extract (CPE) and major peanut allergens Ara h 2 and Ara h 6 in a mediator-release assay based on the rat basophilic leukemia (RBL) cell line transfected with human Fcε receptor. METHODS: Native Ara h 2/6 was reduced and alkylated (RA), with or without additional glutaraldehyde treatment (RAGA). CPE was reduced and alkylated. Sera of subjects with peanut allergy (16 males; median age 7 years) were used for overnight RBL-passive sensitization. Cells were stimulated with 0.1 pg/mL to 10 µg/mL of peanut. ß-N-acetylhexosaminidase release (NHR) was used as a marker of RBL degranulation, expressed as a percentage of total degranulation caused by Triton X. RESULTS: Median peanut-specific immunoglobulin E was 233 kUA/L. Nineteen subjects were responders, NHR ≥ 10% in the mediator release assay. Responders had reduced NHR by RA and RAGA compared with the native Ara h 2/6. Modification resulted in a later onset of activation by 10- to 100-fold in concentration and a lowering of the maximum release. Modified RA-Ara h 2/6 and RAGA-Ara h 2/6 caused significantly lower maximum mediator release than native Ara h 2/6, at protein concentrations 0.1, 1, and 10 ng/mL (p < 0.001, < 0.001, and < 0.001, respectively, for RA; and < 0.001, 0.026, and 0.041, respectively, for RAGA). RA-CPE caused significantly lower maximum NHR than native CPE, at protein concentration 1 ng/mL (p < 0.001) and 10 ng/mL (p < 0.002). Responders had high rAra h 2 immunoglobulin E (mean, 61.1 kUA/L; p < 0.001) and higher NHR in mediator release assay to native Ara h 2/6 than CPE, which indicates that Ara h 2/6 were the most relevant peanut allergens in these responders. CONCLUSIONS: Chemical modification of purified native Ara h 2 and Ara h 6 reduced mediator release in an in vitro assay ∼100-fold, which indicates decreased allergenicity for further development of the alternative candidate for safe peanut immunotherapy.

Reduction and alkylation of peanut allergen isoforms Ara h 2 and Ara h 6; characterization of intermediate- and end products.

Conglutins, the major peanut allergens, Ara h 2 and Ara h 6, are highly structured proteins stabilized by multiple disulfide bridges and are stable towards heat-denaturation and digestion. We sought a way to reduce their potent allergenicity in view of the development of immunotherapy for peanut allergy. Isoforms of conglutin were purified, reduced with dithiothreitol and subsequently alkylated with iodoacetamide. The effect of this modification was assessed on protein folding and IgE-binding. We found that all disulfide bridges were reduced and alkylated. As a result, the secondary structure lost α-helix and gained some ß-structure content, and the tertiary structure stability was reduced. On a functional level, the modification led to a strongly decreased IgE-binding. Using conditions for limited reduction and alkylation, partially reduced and alkylated proteins were found with rearranged disulfide bridges and, in some cases, intermolecular cross-links were found. Peptide mass finger printing was applied to control progress of the modification reaction and to map novel disulfide bonds. There was no preference for the order in which disulfides were reduced, and disulfide rearrangement occurred in a non-specific way. Only minor differences in kinetics of reduction and alkylation were found between the different conglutin isoforms. We conclude that the peanut conglutins Ara h 2 and Ara h 6 can be chemically modified by reduction and alkylation, such that they substantially unfold and that their allergenic potency decreases.

Novel post-translationally cleaved Ara h 2 proteoforms: Purification, characterization and IgE-binding properties.

The 2S albumins Ara h 2 and Ara h 6 have been shown to be the most important source of allergenicity in peanut. Several isoforms of these allergens have been described. Using extraction and liquid chromatography we isolated proteins with homology to Ara h 2 and characterized hitherto unknown Ara h 2 proteoforms with additional post-translational cleavage. High-resolution mass spectrometry located the cleavage site on the non-structured loop of Ara h 2 while far UV CD spectroscopy showed a comparable structure to Ara h 2. The cleaved forms of Ara h 2 were present in genotypes of peanut commonly consumed. Importantly, we revealed that newly identified Ara h 2 cleaved proteoforms showed comparable IgE-binding using sera from 28 peanut-sensitized individuals, possessed almost the same IgE binding potency and are likely similarly allergenic as intact Ara h 2. This makes these newly identified forms relevant proteoforms of peanut allergen Ara h 2.

Dose and route of administration determine the efficacy of prophylactic immunotherapy for peanut allergy in a Brown Norway rat model.

Introduction: Allergen-specific immunotherapy (IT) is emerging as a viable option for treatment of peanut allergy. Yet, prophylactic IT remains unexplored despite early introduction of peanut in infancy was shown to prevent allergy. There is a need to understand how allergens interact with the immune system depending on the route of administration, and how different dosages of allergen may protect from sensitisation and a clinical active allergy. Here we compared peanut allergen delivery via the oral, sublingual (SL), intragastric (IG) and subcutaneous (SC) routes for the prevention of peanut allergy in Brown Norway (BN) rats. Methods: BN rats were administered PBS or three different doses of peanut protein extract (PPE) via either oral IT (OIT), SLIT, IGIT or SCIT followed by intraperitoneal (IP) injections of PPE to assess the protection from peanut sensitisation. The development of IgE and IgG1 responses to PPE and the major peanut allergens were evaluated by ELISAs. The clinical response to PPE was assessed by an ear swelling test (EST) and proliferation was assessed by stimulating splenocytes with PPE. Results: Low and medium dose OIT (1 and 10 mg) and all doses of SCIT (1, 10, 100 µg) induced sensitisation to PPE, whereas high dose OIT (100 mg), SLIT (10, 100 or 1000 µg) or IGIT (1, 10 and 100 mg) did not. High dose OIT and SLIT as well as high and medium dose IGIT prevented sensitisation from the following IP injections of PPE and suppressed PPE-specific IgE levels in a dose-dependent manner. Hence, administration of peanut protein via different routes confers different risks for sensitisation and protection from peanut allergy development. Overall, the IgE levels toward the individual major peanut allergens followed the PPE-specific IgE levels. Discussion: Collectively, this study showed that the preventive effect of allergen-specific IT is determined by the interplay between the specific site of PPE delivery for presentation to the immune system, and the allergen quantity, and that targeting and modulating tolerance mechanisms at specific mucosal sites may be a prophylactic strategy for prevention of peanut allergy.

Determination of Allergen Levels, Isoforms, and Their Hydroxyproline Modifications Among Peanut Genotypes by Mass Spectrometry.

The recently published reference genome of peanuts enables a detailed molecular description of the allergenic proteins of the seed. We used LC-MS/MS to investigate peanuts of different genotypes to assess variability and to better describe naturally occurring allergens and isoforms. Using relative quantification by mass spectrometry, minor variation of some allergenic proteins was observed, but total levels of Ara h 1, 2, 3, and 6 were relatively consistent among 20 genotypes. Previously published RP-HPLC methodology was used for comparison. The abundance of three Ara h 3 isoforms were variable among the genotypes and contributed to a large proportion of total Ara h 3 where present. Previously unpublished hydroxyproline sites were identified in Ara h 1 and 3. Hydroxylation did not vary significantly where sites were present. Peanut allergen composition was largely stable, with only some isoforms displaying differences between genotypes. The resulting differences in allergenicity are of unknown clinical significance but are likely to be minor. The data presented herein allow for the design of targeted MS methodology to allow the quantitation and therefore control of peanut allergens of clinical relevance and observed variability.

Development of a Sandwich Enzyme-Linked Immunosorbent Assay for Detection and Quantification of Clam Residues in Food Products.

Seafood is a frequent cause of allergic reactions to food globally. The presence of undeclared trace amounts of clam can cause allergic reactions in sensitive individuals. Limited tools are available to test food products for the presence of traces of clam. We report on the development of a sandwich ELISA that can detect and quantify clam protein in food. Antisera against a mix of two commercially important clam species, Atlantic Surf (Spisula solidissima) and ocean quahog (Arctica islandica), were raised in rabbit and sheep. A sandwich ELISA was constructed with this antisera, and sensitivity and specificity were evaluated. Also, model food products spiked with clam protein were analyzed to assess the performance of the ELISA. Comparison was made with a commercially available ELISA for crustacea. The lower limit of quantification of the sandwich ELISA is 2.5 ppm clam protein in food samples, allowing the detection of low amounts of clam that may trigger a reaction in clam allergic patients. The sandwich ELISA was highly specific with cross-reactivity only noted for other molluscan shellfish (mussel and scallop). Clam protein in tomato juice and potato cream soup was detected well with recoveries ranging from 65 to 74% and from 74 to 113%, respectively. However when potato cream soup was retorted, the recover fell to 20%, imposing the risk of underestimating the clam content of a food product. A commercially available crustacean ELISA test was not suitable to detect clam protein. The sandwich ELISA described here is suitable for detection and quantification of clam protein in food products. Care should be taken with food products that have been retorted as the results may be underestimated.

Purification and Initial Characterization of Ara h 7, a Peanut Allergen from the 2S Albumin Protein Family.

2S albumins are important peanut allergens. Within this protein family, Ara h 2 and Ara h 6 have been described in detail, but Ara h 7 has received little attention. We now describe the first purification of Ara h 7 and its characterization. Two Ara h 7 isoforms were purified from peanuts. Mass spectrometry revealed that both the isoforms have a post-translation cleavage, a hydroxyproline modification near the N-terminus, and four disulfide bonds. The secondary structure of both Ara h 7 isoforms is highly comparable to those of Ara h 2 and Ara h 6. Both Ara h 7 isoforms bind IgE, and Ara h 7 is capable of inhibiting the binding between Ara h 2 and IgE, suggesting at least partially cross-reactive IgE epitopes. Ara h 7 was found in all main market types of peanut, at comparable levels. This suggests that Ara h 7 is a relevant allergen from the peanut 2S albumin protein family.

Effect of heat treatment on the conformational stability of intact and cleaved forms ofthe peanut allergen Ara h 6 in relation to its IgE-binding potency.

This work reports on theeffect of heat treatment on the protein conformational stabilityof intact and post-translationallycleaved peanut allergen Ara h 6 in relation to IgE-binding. Intact and post-translationallycleaved Ara h 6 are structurally similar and theirstrong resistance to denaturant-inducedunfolding is comparable. Only upon exposure toautoclave conditions the twoforms of Ara h 6 demonstrated susceptibility toirreversible denaturationresulting in a significant decrease in IgE-binding potency. Thisreduction isfor the intact protein more pronounced than for than for the cleaved form. This isattributed to less conformational constrains of the cleaved form comparedtointact, as suggested by the 2-fold lower activation energy for unfoldingfound for the cleavedform. Overall, harsh conditionsare required to denature Ara h 6 and to significantly reduce its IgE-bindingpotency. The cleavedform possesses more resistance to such denaturation than the intactform.