Allergenicity attributes of different peanut market types

Antioxidant Activities of Different Peanut (Arachis hypogaea L.) Market Types by Spectrophotometric Techniques Combined with Chemometrics

Peanut is rich in oil and protein and has a large content of bioactive constituents consisting of tocopherols, phytosterols, and so on. Generally, Virginia, Spanish, Valencia and Runner market types are grown of peanut. In this study, it is aimed to determine the antioxidant activity, total phenolic content and total flavonoid content of peanuts from four different market types, for the first time, and group them with principal component analysis (PCA) and hierarchical cluster analysis (HCA). For PCA, PC1 and PC2 explained 87.655 % of the total variation and, according to the HCA of peanut samples, two main groups were determined. The total phenolic content changed 1.556 to 2.899 mg GAE/g. The lowest value have seen at Spanish merket type to determine the antioxidant activities of peanut samples were maked FRAP and DPPH assay, the lowest FRAP value (8.136 μmol FeSO47H2O/g sample) was seen at Valencia market type, the highest (14.004 μmol FeSO47H2O/g sample) was seen at Virginia market type. It was determined that the total flavonoid, total phenolic content, and antioxidant activities of the Virginia, Valencia, Spanish, and Runner market types included in the study were different from each other, and the Virginia market type showed superior characteristics compared to the others. The results obtained suggest that Virginia market type may be preferred more especially in peanut cultivation for food uses. It is thought that this study can be a source for future studies by eliminating a deficiency in the literature.

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.

Major peanut allergens are quickly released from peanuts when seeds are hydrated under specific conditions

Allergens release from their biological source is a critical step in allergic sensitization. We sought to investigate in vitro the role of hydration at 1:10 w/v without stirring and 1:5 w/v with and without stirring on the release of major and minor allergens from peanut kernels. We hypothesized that hydration plays a pivotal role in peanut allergens release, affecting major allergens predominantly, and that peanut-water ratio and stirring influence allergen diffusion. We found that major peanut allergen Ara h 1 was quickly released during hydration leading to a decrease in its content in the seed particularly at hydration performed at 1:5 w/v with stirring. Ara h 2 remained more preserved in the hydrated seed, while Ara h 3 showed no content decrease despite its important release into the hydration water. Minor allergens Ara h 8 and Ara h 9 have lower abundance in peanut leading to a reduction of their content in the seed after their diffusion into the water during hydration. The results also demonstrated that a higher seed-to-water ratio (1:5 w/v) and stirring had a more pronounced impact on allergen release.

Preparation of Blinded Food Matrixes for Clinical Oral Challenges

Clinically, oral food challenges have value in the diagnosis and management of food allergy. Oral food challenges are used not only for diagnostic confirmation that ingestion of a specific food elicits an adverse reaction, but also for determining individual threshold doses, tracking the progress toward desensitization during immunotherapy, determining the effect of processing on the allergenicity of a specific food, assessing the allergenicity of an ingredient derived from an allergenic source, and tracking the progress toward development of age-related tolerance to a specific food. To eliminate bias in oral challenges, the food under investigation is masked in a matrix so that it is not sensorially detectable by the patient or the clinical observer. The preparation of oral challenge foods requires care in the selection of the allergenic components, the selection of the components of the matrix, the masking of the allergenic component, and the homogeneity of the allergen in the overall matrix.

Modulating the allergenicity and functional properties of peanut protein by covalent conjugation with polyphenols

Peanut protein is a common food allergen. Our previous study demonstrated that the allergenicity of Ara h1 declines after covalent conjugation with polyphenols in vitro; however, how polyphenols affect the structure, function, and allergenicity of peanut protein extract (PPE) after covalent conjugating needs clarifying. Here, we assessed how the structure, function, and allergenicity of PPE changed after covalent conjugation with epigallocatechin-3-gallate (PPE-EGCG) and chlorogenic acid (PPE-CA). PPE covalently conjugated with EGCG and CA using the alkali treatment method. Multi-spectroscopy showed that the structure of PPE-EGCG/CA conjugate changed, becoming less folded. In contrast, the functional properties of PPE significantly improved. The allergenicity of PPE-EGCG/CA significantly declined in vitro and in vivo experiments. Our findings confirm that covalent conjugation of PPE with EGCG and CA reduces the allergenicity and improves the functional properties of PPE by changing the structure of the protein.

A narrative action on the battle against hunger using mushroom, peanut, and soybean-based wastes

Numerous generations have been affected by hunger, which still affects hundreds of millions of people worldwide. The hunger crisis is worsening although many efforts have been made to minimize it. Besides that, food waste is one of the critical problems faced by most countries worldwide. It has disrupted the food chain system due to inefficient waste management, while negatively impacting the environment. The majority of the waste is from the food production process, resulting in a net zero production for food manufacturers while also harnessing its potential. Most food production wastes are high in nutritional and functional values, yet most of them end up as low-cost animal feed and plant fertilizers. This review identified key emerging wastes from the production line of mushroom, peanut, and soybean (MPS). These wastes (MPS) provide a new source for food conversion due to their high nutritional content, which contributes to a circular economy in the post-pandemic era and ensures food security. In order to achieve carbon neutrality and effective waste management for the production of alternative foods, biotechnological processes such as digestive, fermentative, and enzymatic conversions are essential. The article provides a narrative action on the critical potential application and challenges of MPS as future foods in the battle against hunger.

Peanut Allergenicity: An Insight into Its Mitigation Using Thermomechanical Processing

Peanuts are the seeds of a legume crop grown for nuts and oil production. Peanut allergy has gained significant attention as a public health issue due to its increasing prevalence, high rate of sensitization, severity of the corresponding allergic symptoms, cross-reactivity with other food allergens, and lifelong persistence. Given the importance of peanuts in several sectors, and taking into consideration the criticality of their high allergic potential, strategies aiming at mitigating their allergenicity are urgently needed. In this regard, most of the processing methods used to treat peanuts are categorized as either thermal or thermomechanical techniques. The purpose of this review is to provide the reader with an updated outlook of the peanut’s allergens, their mechanisms of action, the processing methods as applied to whole peanuts, as well as a critical insight on their impact on the allergenicity. The methods discussed include boiling, roasting/baking, microwaving, ultrasonication, frying, and high-pressure steaming/autoclaving. Their effectiveness in alleviating the allergenicity, and their capacity in preserving the structural integrity of the treated peanuts, were thoroughly explored. Research data on this matter may open further perspectives for future relevant investigation ultimately aiming at producing hypoallergenic peanuts.

Allergenicity of peanut allergens and its dependence on the structure

Food allergies are a global food safety problem. Peanut allergies are common due, in part, to their popular utilization in the food industry. Peanut allergy is typically an immunoglobulin E-mediated reaction, and peanuts contain 17 allergens belonging to different families in peanut. In this review, we first introduce the mechanisms and management of peanut allergy, followed by the basic structures of associated allergens. Subsequently, we summarize methods of epitope localization for peanut allergens. These methods can be instrumental in speeding up the discovery of allergenicity-dependent structures. Many attempts have been made to decrease the allergenicity of peanuts. The structures of hypoallergens, which are manufactured during processing, were analyzed to strengthen the desensitization process and allergen immunotherapy. The identification of conformational epitopes is the bottleneck in both peanut and food allergies. Further, the identification and modification of such epitopes will lead to improved strategies for managing and preventing peanut allergy. Combining traditional wet chemistry research with structure simulation studies will help in the epitopes' localization.

IgE glycans promote anti-IgE IgG autoantibodies that facilitate IgE serum clearance via Fc Receptors

Background

Recent studies have shown that IgE glycosylation significantly impacts the ability of IgE to bind to its high-affinity receptor FcεRI and exert effector functions. We have recently demonstrated that immunizing mice with IgE in a complex with an allergen leads to a protective, glycan-dependent anti-IgE response. However, to what extent the glycans on IgE determine the induction of those antibodies and how they facilitate serum clearance is unclear.Therefore, we investigated the role of glycan-specific anti-IgE IgG autoantibodies in regulating serum IgE levels and preventing systemic anaphylaxis by passive immunization.

Methods

Mice were immunized using glycosylated or deglycosylated IgE-allergen-immune complexes (ICs) to induce anti-IgE IgG antibodies. The anti-IgE IgG antibodies were purified and used for passive immunization.

Results

Glycosylated IgE-ICs induced a significantly higher anti-IgE IgG response and more IgG-secreting plasma cells than deglycosylated IgE-ICs. Passive immunization of IgE-sensitized mice with purified anti-IgE IgG increased the clearance of IgE and prevented systemic anaphylaxis upon allergen challenge. Anti-IgE IgG purified from the serum of mice immunized with deglycosylated IgE-ICs, led to a significantly reduced elimination and protection, confirming that the IgE glycans themselves are the primary drivers of the protectivity induced by the IgE-immune complexes.

Conclusion

IgE glycosylation is essential for a robust anti-IgE IgG response and might be an important regulator of serum IgE levels.

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.

Irradiation technology: An effective and promising strategy for eliminating food allergens

Food allergies are one of the major health concerns worldwide and have been increasing at an alarming rate in recent times. The elimination of food allergenicity has been an important issue in current research on food. Irradiation is a typical nonthermal treatment technology that can effectively reduce the allergenicity of food, showing great application prospects in improving the quality and safety of foods. In this review, the mechanism and remarkable features of irradiation in the elimination of food allergens are mainly introduced, and the research progress on reducing the allergenicity of animal foods (milk, egg, fish and shrimp) and plant foods (soybean, peanut, wheat and nuts) using irradiation is summarized. Furthermore, the influencing factors for irradiation in the elimination of food allergens are analyzed and further research directions of irradiation desensitization technology are also discussed. This article aims to provide a reference for promoting the application of irradiation technology in improving the safety of foods.

Evolutionary warning system for COVID-19 severity: Colony predation algorithm enhanced extreme learning machine

Coronavirus Disease 2019 (COVID-19) was distributed globally at the end of December 2019 due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Early diagnosis and successful COVID-19 assessment are missing, clinical care is ineffective, and deaths are high. In this study, we investigate whether the level of biochemical indicators helps to discriminate and classify the severity of the COVID-19 using the machine learning method. This research creates an efficient intelligence method for the diagnosis of COVID-19 from the perspective of biochemical indexes. The framework is proposed by integrating an enhanced new stochastic called the colony predation algorithm (CPA) with a kernel extreme learning machine (KELM), abbreviated as ECPA-KELM. The core feature of the approach is the ECPA algorithm which incorporates the two main operators that have been abstained from the grey wolf optimizer and moth-flame optimizer to improve and restore the CPA research functions and are simultaneously used to optimize the parameters and to select features for KELM. The ECPA output is checked thoroughly using IEEE CEC2017 benchmark to verify the capacity of the proposed methodology. Finally, in the diagnosis of COVID-19 using biochemical indexes, the designed ECPA-KELM model and other competing KELM models based on other optimization are used. Checking statistical results will display improved predictive properties for all metrics and higher stability. ECPA-KELM can also be used to discriminate and classify the severity of the COVID-19 as a possible computer-aided method and provide effective early warning for the treatment and diagnosis of COVID-19.

Performance of allergen testing in a survey of frozen meals and meals ready-to-eat (MREs)

A 7-plex immunoassay capable of detecting cashew, egg, hazelnut, milk, peanut, shrimp, and soy allergens was used to screen meals ready-to-eat (MREs) and frozen meals that contained meat or poultry. The same food matrices were also evaluated using single individual allergen immunoassays. Multiplex and single allergen test results were compared with the allergen declared on the food label, which was considered the standard. For both the frozen meals (n = 113) and MREs (n = 24) each analytical method failed to detect allergens that were declared on product labels, but only in frozen meals were allergens detected that were not declared on the label. Undeclared allergens were detected for egg in 1.8% (2/113) and for soy in 7.1% (8/113) of frozen meals. Labelled allergens were not detected in 0.9% (1/113) of milk, 4.4% (5/113) of egg, and 15% (17/113) of soy allergens in frozen meals. Assay performance for evaluating allergens in MREs was poor.

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.

Quantitative proteomics analysis of high and low polyphenol expressing recombinant inbred lines (RILs) of peanut (Arachis hypogaea L.)

To facilitate selective breeding of polyphenol-rich peanuts, we looked for mass spectrometry-based proteomic evidence, investigating a subset of recombinant inbred lines (RILs) developed by the Australian peanut breeding program. To do this, we used label-free shotgun proteomics for protein and peptide quantitation, statistically analyzed normalized spectral abundance factors using R-package, as well as assayed important antioxidants. Results revealed statistically significant protein expression changes in 82 proteins classified between high or low polyphenols expressing RILs. Metabolic changes in polyphenol-rich RIL p27-362 point towards increased enzymatic breakdown of sugars and phenylalanine biosynthesis. The study revealed phenylpropanoid pathway overexpression resulting in increased polyphenols biosynthesis. Overexpression of antioxidant enzymes such as catalase, by 73.4 fold was also observed. A strong metabolic correlation exists with the observed phenotypic traits. Peanut RIL p27-362 presents a superior nutritional composition with antioxidant-rich peanut phenotype and could yield commercial profits. Data are available via ProteomeXchange with identifierPXD015493.

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.

Ara h 2 is the dominant peanut allergen despite similarities with Ara h 6

Background

Arachis hypogaea 2 (Ara h 2)-specific IgE is to date the best serologic marker to diagnose peanut allergy. Ara h 6 shares approximately 60% sequence identity and multiple epitopes with Ara h 2.

Objective

Our aim was to assess the diagnostic utility and relative importance of Ara h 2 and Ara h 6 in peanut allergy.

Methods

A cohort 100 of children was studied. The cohort included chidren who had peanut allergy, children who were sensitized to but tolerant of peanut, and children who were neither sensitized nor allergic to peanut. Levels of specific IgE to peanut and individual allergens were quantified by using ImmunoCAP. ImmunoCAP inhibition experiments and mast cell activation tests in response to both Ara h 2 and Ara h 6 were performed. Statistical analyses were done using SPSS version 14 and Prism version 7 software.

Results

Ara h 2–specific IgE and Ara h 6–specific IgE showed the greatest diagnostic accuracy for peanut allergy when compared with specific IgE to peanut and other peanut allergens. Most patients with peanut allergy were sensitized to both Ara h 2 and Ara h 6. Ara h 2 reduced Ara h 2–specific IgE binding more than Ara h 6 did (P < .001), whereas Ara h 6–specific IgE binding was inhibited to a similar degree by Ara h 2 and Ara h 6 (P = .432). In the mast cell activation test, Ara h 2 induced significantly greater maximal reactivity (P = .001) and a lower half maximal effective concentration (P = .002) than did Ara h 6 when testing cosensitized individuals.

Conclusions

Ara h 2–specific IgE and Ara h 6–specific IgE provide the greatest accuracy to diagnose peanut allergy. Ara h 2 is the dominant conglutin in peanut allergy in the United Kingdom, despite a degree of cross-reactivity with Ara h 6.

Vaccine against peanut allergy based on engineered virus-like particles displaying single major peanut allergens

BACKGROUND

Peanut allergy is a severe and increasingly frequent disease with high medical, psychosocial, and economic burden for affected patients and wider society. A causal, safe, and effective therapy is not yet available.

OBJECTIVE

We sought to develop an immunogenic, protective, and nonreactogenic vaccine candidate against peanut allergy based on virus-like particles (VLPs) coupled to single peanut allergens.

METHODS

To generate vaccine candidates, extracts of roasted peanut (Ara R) or the single allergens Ara h 1 or Ara h 2 were coupled to immunologically optimized Cucumber Mosaic Virus-derived VLPs (CuMVtt). BALB/c mice were sensitized intraperitoneally with peanut extract absorbed to alum. Immunotherapy consisted of a single subcutaneous injection of CuMVtt coupled to Ara R, Ara h 1, or Ara h 2.

RESULTS

The vaccines CuMVtt-Ara R, CuMVtt-Ara h 1, and CuMVtt-Ara h 2 protected peanut-sensitized mice against anaphylaxis after intravenous challenge with the whole peanut extract. Vaccines did not cause allergic reactions in sensitized mice. CuMVtt-Ara h 1 was able to induce specific IgG antibodies, diminished local reactions after skin prick tests, and reduced the infiltration of the gastrointestinal tract by eosinophils and mast cells after oral challenge with peanut. The ability of CuMVtt-Ara h 1 to protect against challenge with the whole extract was mediated by IgG, as shown via passive IgG transfer. FcγRIIb was required for protection, indicating that immune complexes with single allergens were able to block the allergic response against the whole extract, consisting of a complex allergen mixture.

CONCLUSIONS

Our data suggest that vaccination using single peanut allergens displayed on CuMVtt may represent a novel therapy against peanut allergy with a favorable safety profile.

Thermal processing of peanut impacts detection by current analytical techniques

Recalls of spice containing products due to undeclared peanut have highlighted the importance of analytical methods in these foods. We examined the performance of peanut detection methods in cumin and garlic, focusing on quantitative ELISA. Although suitable for qualitative detection, accurate quantitation proved difficult. Roasting of peanut contaminants influenced ELISA results, with raw peanut over-detected (3.9-fold) and roasted peanut under-detected (3.5-fold). Further investigation demonstrated the importance of protein targets for ELISA. The kit which gave the least variable results was based on detection of 2S albumin proteins. Additionally, we show that these proteins are more efficiently extracted from roasted peanut. We conclude that current methods are largely suitable for the qualitative detection of peanut in cumin and garlic. Quantitation relies on assumptions as to the state of thermal processing of peanut. We suggest that analytical method providers address robust detection by target selection, including identifying targets by MS.

Hypoallergen Peanut Lines Identified Through Large-Scale Phenotyping of Global Diversity Panel: Providing Hope Toward Addressing One of the Major Global Food Safety Concerns

Peanut allergy is one of the serious health concern and affects more than 1% of the world's population mainly in Americas, Australia, and Europe. Peanut allergy is sometimes life-threatening and adversely affect the life quality of allergic individuals and their families. Consumption of hypoallergen peanuts is the best solution, however, not much effort has been made in this direction for identifying or developing hypoallergen peanut varieties. A highly diverse peanut germplasm panel was phenotyped using a recently developed monoclonal antibody-based ELISA protocol to quantify five major allergens. Results revealed a wide phenotypic variation for all the five allergens studied i.e., Ara h 1 (4-36,833 µg/g), Ara h 2 (41-77,041 µg/g), Ara h 3 (22-106,765 µg/g), Ara h 6 (829-103,892 µg/g), and Ara h 8 (0.01-70.12 µg/g). The hypoallergen peanut genotypes with low levels of allergen proteins for Ara h 1 (4 µg/g), Ara h 2 (41 µg/g), Ara h 3 (22 µg/g), Ara h 6 (829 µg/g), and Ara h 8 (0.01 µg/g) have paved the way for their use in breeding and genomics studies. In addition, these hypoallergen peanut genotypes are available for use in cultivation and industry, thus opened up new vistas for fighting against peanut allergy problem across the world.

An Improved Enzyme-Linked Immunosorbent Assay (ELISA) Based Protocol Using Seeds for Detection of Five Major Peanut Allergens Ara h 1, Ara h 2, Ara h 3, Ara h 6, and Ara h 8

Peanut allergy is an important health concern among many individuals. As there is no effective treatment to peanut allergy, continuous monitoring of peanut-based products, and their sources is essential. Precise detection of peanut allergens is key for identification and development of improved peanut varieties with minimum or no allergens in addition to estimating the levels in peanut-based products available in food chain. The antibody based ELISA protocol along with sample preparation was standardized for Ara h 1, Ara h 2, Ara h 3, Ara h 6, and Ara h 8 to estimate their quantities in peanut seeds. Three different dilutions were optimized to precisely quantify target allergen proteins in peanut seeds such as Ara h 1 (1/1,000, 1/2,000, and 1/4,000), Ara h 2 and Ara h 3 (1/5,000, 1/10,000, and 1/20,000), Ara h 6 (1/40,000, 1/80,000, and 1/1,60,000), and Ara h 8 (1/10, 1/20, and 1/40). These dilutions were finalized for each allergen based on the accuracy of detection by achieving <20% coefficient of variation in three technical replicates. This protocol captured wide variation of allergen proteins in selected peanut genotypes for Ara h 1 (77-46,106 μg/g), Ara h 2 (265-5,426 μg/g), Ara h 3 (382-12,676 μg/g), Ara h 6 (949-43,375 μg/g), and Ara h 8 (0.385-6 μg/g). The assay is sensitive and reliable in precise detection of five major peanut allergens in seeds. Deployment of such protocol allows screening of large scale germplasm and breeding lines while developing peanut varieties with minimum allergenicity to ensure food safety.

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.

Type IV chitinase quantification in four different grape cultivars (Vitis vinifera) in northeast of Iran by an indirect sandwich enzyme-linked immunosorbent assay

The incidence of grape (Vitis vinifera) allergy in the northeast of Iran is second to melon allergy. Type IV chitinase is one of the major grape allergens. The current study investigates the level of type IV chitinase in four grape variants for the first time in Khorasan Razavi Province using a highly sensitive sandwich enzyme-linked immunosorbent assay (ELISA). This assay was developed using a polyclonal antibody as a capture antibody and monoclonal antibody as a secondary one. Finally, the amount of type IV chitinase was measured by the validated ELISA test. The sensitivity of the developed sandwich ELISA is 16 ± 0.05 ng/ml, and its mean coefficients of intraday and interday variations are <5% and <15%, respectively. The recovery of the designed ELISA is 64 ± 0.9 %. The assessments showed that the highest level of type IV chitinase was 39.7 ± 2.3 μg/g in Peykani grape, whereas in the Sultana cultivar, it was 1.76 ± 0.1 μg/g. According to the data, the level of type IV chitinase is variable in different cultivars, and hence, it will be helpful for clinicians to recommend a less allergenic variety to the patient.

Legume Protein Consumption and the Prevalence of Legume Sensitization

Sensitization and allergy to legumes can be influenced by different factors, such as exposure, geographical background, and food processing. Sensitization and the allergic response to legumes differs considerably, however, the reason behind this is not yet fully understood. The aim of this study is to investigate if there is a correlation between legume protein consumption and the prevalence of legume sensitization. Furthermore, the association between sensitization to specific peanut allergens and their concentration in peanut is investigated. Legume sensitization data (peanut, soybean, lupin, lentil, and pea) from studies were analyzed in relation to consumption data obtained from national food consumption surveys using the European Food Safety Authority (EFSA), Global Environment Monitoring System (GEMS), and What We Eat in America-Food Commodity Intake Database (WWEIA-FCID) databases. Data were stratified for children <4 years, children 4⁻18 years, and adults. Sufficient data were available for peanut to allow for statistical analysis. Analysis of all age groups together resulted in a low correlation between peanut sensitization and relative peanut consumption (r = 0.407), absolute peanut consumption (r = 0.468), and percentage of peanut consumers (r = 0.243). No correlation was found between relative concentrations of Ara h 1, 2, 3, 6, 7, and 8 in peanut and sensitization to these peanut allergens. The results indicate that the amount of consumption only plays a minor role in the prevalence of sensitization to peanut. Other factors, such as the intrinsic properties of the different proteins, processing, matrix, frequency, timing and route of exposure, and patient factors might play a more substantial role in the prevalence of peanut sensitization.

Purification and Characterization of Naturally Occurring Post-Translationally Cleaved Ara h 6, an Allergen That Contributes Substantially to the Allergenic Potency of Peanut

The 2S albumin Ara h 6 is one of the most important peanut allergens. A post-translationally cleaved Ara h 6 (pAra h 6) was purified from Virginia type peanuts, and the cleavage site was mapped using high-resolution mass spectrometry. Compared to intact Ara h 6, pAra h 6 lacks a 5-amino acid stretch, resembling amino acids 43-47 (UniProt accession number Q647G9) in the nonstructured loop. Consequently, pAra h 6 consists of two chains: an N-terminal chain of approximately 5 kDa and a C-terminal chain of approximately 9 kDa, held together by disulfide bonds. Intermediate post-translationally cleaved products, in which this stretch is cleaved yet still attached to one of the subunits, are also present. The secondary structure and immunoglobulin E (IgE) binding of pAra h 6 resembles that of intact Ara h 6, indicating that the loss of the nonstructured loop is not critical for maintaining the protein structure. Commercially available monoclonal and polyclonal immunoglobulin G (IgG) antibodies directed to Ara h 6 react with both intact Ara h 6 and pAra h 6, suggesting that the involved epitopes are not located in the area that is post-translationally cleaved. No differences between intact Ara h 6 and pAra h 6 in terms of IgE binding were found, suggesting that the area that is post-translationally cleaved is not involved in IgE epitopes either. For all main cultivars Runner, Virginia, Valencia, and Spanish, intact Ara h 6 and pAra h 6 occur in peanut at similar levels, indicating that pAra h 6 is a consistent and important contributor to the allergenic potency of peanut.

Release of Major Peanut Allergens from Their Matrix under Various pH and Simulated Saliva Conditions-Ara h2 and Ara h6 Are Readily Bio-Accessible

The oral mucosa is the first immune tissue that encounters allergens upon ingestion of food. We hypothesized that the bio-accessibility of allergens at this stage may be a key determinant for sensitization. Light roasted peanut flour was suspended at various pH in buffers mimicking saliva. Protein concentrations and allergens profiles were determined in the supernatants. Peanut protein solubility was poor in the pH range between 3 and 6, while at a low pH (1.5) and at moderately high pHs (>8), it increased. In the pH range of saliva, between 6.5 and 8.5, the allergens Ara h2 and Ara h6 were readily released, whereas Ara h1 and Ara h3 were poorly released. Increasing the pH from 6.5 to 8.5 slightly increased the release of Ara h1 and Ara h3, but the recovery remained low (approximately 20%) compared to that of Ara h2 and Ara h6 (approximately 100% and 65%, respectively). This remarkable difference in the extraction kinetics suggests that Ara h2 and Ara h6 are the first allergens an individual is exposed to upon ingestion of peanut-containing food. We conclude that the peanut allergens Ara h2 and Ara h6 are quickly bio-accessible in the mouth, potentially explaining their extraordinary allergenicity.

Origin and Processing Methods Slightly Affect Allergenic Characteristics of Cashew Nuts (Anacardium occidentale)

The protein content and allergen composition was studied of cashews from 8 different origins (Benin, Brazil, Ghana, India, Ivory Coast, Mozambique, Tanzania, Vietnam), subjected to different in-shell heat treatments (steamed, fried, drum-roasted). On 2D electrophoresis, 9 isoforms of Ana o 1, 29 isoforms of Ana o 2 (11 of the acidic subunit, 18 of the basic subunit), and 8 isoforms of the large subunit of Ana o 3 were tentatively identified. Based on 1D and 2D electrophoresis, no difference in allergen content (Ana o 1, 2, 3) was detected between the cashews of different origins (P > 0.5), some small but significant differences were detected in allergen solubility between differently heated cashews. No major differences in N- and C-terminal microheterogeneity of Ana o 3 were detected between cashews of different origins. Between the different heat treatments, no difference was detected in glycation, pepsin digestibility, or IgE binding of the cashew proteins.

Detection of peanut allergen in human blood after consumption of peanuts is skewed by endogenous immunoglobulins

Some studies have suggested that allergens may appear in the circulation after ingestion of allergenic food sources. The reported levels of allergen in serum, however, are low, and conclusions between studies differ. Here, we investigated factors that determine the detection of allergens in serum after consumption of peanuts. Ten healthy volunteers ingested 100g of light-roasted peanuts. Serum samples were taken at regular intervals for six hours. A double monoclonal sandwich ELISA was used to analyse the presence and quantity of the major peanut allergen Ara h 6 in serum. In 4 out of 10 subjects, no Ara h 6 could be detected. Purified Ara h 6 that was digested in vitro was still reactive in the ELISA, rejecting the possibility that digestion leads to small peptides that could not be detected. Spiking of purified Ara h 6 in baseline serum showed that the pre-ingestion serum of these four subjects partially prevented Ara h 6 to react in the ELISA, with a reduction of reactivity of up to 3 orders of magnitude or more. Pre-ingestion serum of the other six subjects did not show such an effect. The reduction of reactivity of Ara h 6 coincided with high titres of IgG and IgG4, and removal of IgG from pre-ingestion serum abolished this effect completely, indicating that IgG and IgG4 inhibited the reactivity of Ara h6 in the ELISA. We conclude that some individuals have IgG and IgG4 against food allergens in their blood, which interferes with detection of such food allergens in serum. Because this effect does not occur for each individual, the possibility of such interference should be taken into consideration when interpreting immunochemical studies on the absorption of food allergens in serum.

Recent advances in component resolved diagnosis in food allergy

Due to the high prevalence of food allergic diseases globally there are increasing demands in clinical practice for managing IgE-mediated conditions. During the last decade, component resolved diagnostics has been introduced into the field of clinical allergology, providing information that cannot be obtained from extract-based tests. Component resolved data facilitate more precise diagnosis of allergic diseases and identify sensitizations attributable to cross-reactivity. Furthermore it assists risk assessment in clinical practice as sensitization to some allergenic molecules is related to persistence of clinical symptoms and systemic rather than local reactions. The information may also aid the clinician in prescription of oral immunotherapy (OIT) in patients with severe symptoms, and in giving advice on food allergen avoidance or on the need to perform food challenges. The use of allergen components is rapidly evolving and increases our possibility to treat food allergic patients with a more individual approach. Using molecular allergology, we can already now better diagnose, prognose and grade the food allergy. In summary, daily routine molecular allergy diagnostics offers a number of benefits that give us a higher diagnostic precision and allow for better management of the patient.