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The major peanut allergen, Ara h 2, functions as a trypsin inhibitor, and roasting enhances this function
Abstract
The widespread use of peanut products, the severity of the symptoms, and its persistence in afflicted individuals has made peanut allergy a major health concern in western countries such as the United States, United Kingdom, and Canada. In a previous study, the authors showed that the allergenic properties of peanut proteins are enhanced as a result of thermal processing.
The purpose of this investigation was to determine whether any specific functions are associated with the major peanut allergen, Ara h 2, and whether the functionality of this protein is influenced by processing. An assay was developed and used to assess structure/function changes in Ara h 2 induced by roasting and the effect of these alterations on the allergenic properties of this major peanut allergen.
A protein domain homology search was used to determine possible functions for Ara h 2. One of the putative functions (protease inhibition) was tested by means of appropriate enzyme assays and protein gel electrophoresis. Circular dichroism was used to compare the structural properties of Ara h 2 purified from raw and roasted peanuts.
Ara h 2 purified from peanuts is homologous to and functions as a trypsin inhibitor. Roasting caused a 3.6-fold increase in trypsin inhibitory activity. Functional and structural comparison of the Ara h 2 purified from roasted peanuts to native and reduced Ara h 2 from raw peanuts revealed that the roasted Ara h 2 mimics the behavior of native Ara h 2 in a partially reduced form.
The data indicate that thermal processing might play an important role in enhancing the allergenic properties of peanuts. Not only has it previously been shown to affect the structural and allergic properties of peanut proteins but also, for the first time, the functional characteristics of an allergen. These structural and functional alterations are likely to influence the allergenicity of peanuts.
... Studies [9] have shown that a low calcium content and, at the same time, an increased content of oxalic acid in foods contribute to its high bioavailability and lead to greater formation and absorption of oxalates (up to 80%), and at high levels of calcium in foods, the bioavailability of oxalates decreases. Thus, to reduce the formation of oxalates in the human body, foods should be combining with dairy products, which are a source of calcium. ...
... It has been proven [9] that liming of soils reduces the intake of Cd into the plant. Thus, the Florunner peanut variety is the most sensitive to Cd accumulation. ...
... Peanuts are a good substrate for Aspergillus growth and aflatoxin production [12]. The factors that cause high levels of contamination are imperfect agricultural methods of planting, harvesting, drying, transportation and storage of the product [9]. ...
Its biological features and soil and climatic conditions limit the cultivation of peanuts in Ukraine. A prerequisite for obtaining high stable peanut yields is sowing with high-quality seeds characterized by excellent sowing and yield properties.
... Processing methods such as heat (roasting, boiling, and frying), chemical treatment, acidic and enzymatic hydrolysis, and other novel technologies such as ultrasonication, high pressure processing (HPP), irradiation, pulsed ultraviolet light (PUV), pulsed electric field (PEF), and combined processing (Hurdle technology) have been explored to reduce IgE reactivity and allergenicity of peanut. Processing technology has the capability of altering the protein structure, function, and physicochemical properties of peanuts (Dyer et al., 2018;Maleki, 2004;Maleki et al., 2003;Maleki & Hulburt, 2004;Nesbit et al., 2012;Nesbit, Chung, Hulburt, & Maleiki 2018). The alteration of allergenic proteins influences its immunoreactivity either positively or negatively by structural unfolding, aggregation, degradation, and crosslinking, which can influence the allergenicity. ...
... The alteration of allergenic proteins influences its immunoreactivity either positively or negatively by structural unfolding, aggregation, degradation, and crosslinking, which can influence the allergenicity. A key mechanism in reducing protein allergenicity is to alter its structural and linear immunoglobulin E (IgE) binding sites (epitopes) (Comstock, Maleki, & Teuber, 2016;Dyer et al., 2018;Khan et al., 2018;Li, Yu, Ahmedna, & Goktepe, 2013;Maleki et al., 2003;Nesbit et al., 2012;O'Konek et al., 2018;Rahaman, Vasiljevic, & Ramchandran, 2016;Vanga, Singh, & Raghavan, 2017). Enzymatic hydrolysis and hurdle techniques have the greatest potential to alter allergenic proteins while covalent modifications such as crosslinking, aggregation, oxidation, reduction, alkylation, and acylation also impart significant alteration in allergenicity (Cabanillas et al., 2011;Chung & Champagne, 2009;Kasera, Singh, Lavasa, Prasad, & Arora, 2015;Mikiashvili & Yu, 2018;Yu, Ahmedna, Goktepe, Cheng, & Maleki, 2011). ...
... Destruction of conformational epitopes may expose masked epitopes while linear epitopes may be altered by chemical and enzymatic hydrolysis (Kasera et al., 2015;Lee et al., 2016;Rahaman et al., 2016). Besides IgE epitopes, protein structure also plays a critical role and functions in the allergenic potential of proteins (Chruszcz et al., 2011, Nesbit et al., 2012, Dyer et al., 2018Maleki, Kopper et al., 2000;Maleki et al., 2003, Maleki, 2004, Maleki & Hurlburt, 2004. Therefore, the alteration in allergen structure subsequently alters its physicochemical properties such as solubility and digestibility, which in turn plays a significant role in altering the immunoreactivity (Apostolovic et al., 2013;Mikiashvili & Yu, 2018;Plundrich et al., 2015;Szymkiewicz & Jędrychowski, 2009;Vanga et al., 2016). ...
Peanut allergy has garnered significant attention because of the high sensitization rate, increase in allergy, and severity of the reaction. Sufficiently reliable therapies and efficient mitigating techniques to combat peanut allergy are still lacking. Current management relies on avoiding peanuts and nuts and seeds with homologous proteins, although adverse events mostly occur with accidental ingestion. There is a need for hypoallergenic peanut products to protect sensitized individuals and perhaps serve as immunotherapeutic products. Alongside traditional practices of thermal and chemical treatment, novel processing approaches such as high‐pressure processing, pulsed ultraviolet light, high‐intensity ultrasound, irradiation, and pulsed electric field have been performed toward reducing the immunoreactivity of peanut. Covalent and noncovalent chemical modifications to proteins also have the tendency to alter peanut allergenicity. Enzymatic hydrolysis seems to be the most advantageous technique in diminishing the allergenic potential of peanut. Furthermore, the combined processing approach (hurdle technologies) such as enzymatic hydrolysis followed by, or in conjunction with, roasting, high pressure and heat, ultrasound with enzymatic treatment, or germination have shown a significant reduction of peanut immunoreactivity and may emerge as useful techniques in reducing the allergenicity of peanut and other foods. This study represents our current knowledge about the alterations in allergenic properties of peanut via different processing mechanisms as well as evaluating its future potential, geographical based data on increasing sensitization, clinical relevance, eliciting dose, and current management of peanut allergy. Furthermore, the molecular characteristics and clinical relevance of peanut allergens have been discussed.
... Processing methods such as heat (roasting, boiling, and frying), chemical treatment, acidic and enzymatic hydrolysis, and other novel technologies such as ultrasonication, high pressure processing (HPP), irradiation, pulsed ultraviolet light (PUV), pulsed electric field (PEF), and combined processing (Hurdle technology) have been explored to reduce IgE reactivity and allergenicity of peanut. Processing technology has the capability of altering the protein structure, function, and physicochemical properties of peanuts (Dyer et al., 2018;Maleki, 2004;Maleki et al., 2003;Maleki & Hulburt, 2004;Nesbit et al., 2012;Nesbit, Chung, Hulburt, & Maleiki 2018). The alteration of allergenic proteins influences its immunoreactivity either positively or negatively by structural unfolding, aggregation, degradation, and crosslinking, which can influence the allergenicity. ...
... The alteration of allergenic proteins influences its immunoreactivity either positively or negatively by structural unfolding, aggregation, degradation, and crosslinking, which can influence the allergenicity. A key mechanism in reducing protein allergenicity is to alter its structural and linear immunoglobulin E (IgE) binding sites (epitopes) (Comstock, Maleki, & Teuber, 2016;Dyer et al., 2018;Khan et al., 2018;Li, Yu, Ahmedna, & Goktepe, 2013;Maleki et al., 2003;Nesbit et al., 2012;O'Konek et al., 2018;Rahaman, Vasiljevic, & Ramchandran, 2016;Vanga, Singh, & Raghavan, 2017). Enzymatic hydrolysis and hurdle techniques have the greatest potential to alter allergenic proteins while covalent modifications such as crosslinking, aggregation, oxidation, reduction, alkylation, and acylation also impart significant alteration in allergenicity (Cabanillas et al., 2011;Chung & Champagne, 2009;Kasera, Singh, Lavasa, Prasad, & Arora, 2015;Mikiashvili & Yu, 2018;Yu, Ahmedna, Goktepe, Cheng, & Maleki, 2011). ...
... Destruction of conformational epitopes may expose masked epitopes while linear epitopes may be altered by chemical and enzymatic hydrolysis (Kasera et al., 2015;Lee et al., 2016;Rahaman et al., 2016). Besides IgE epitopes, protein structure also plays a critical role and functions in the allergenic potential of proteins (Chruszcz et al., 2011, Nesbit et al., 2012, Dyer et al., 2018Maleki, Kopper et al., 2000;Maleki et al., 2003, Maleki, 2004, Maleki & Hurlburt, 2004. Therefore, the alteration in allergen structure subsequently alters its physicochemical properties such as solubility and digestibility, which in turn plays a significant role in altering the immunoreactivity (Apostolovic et al., 2013;Mikiashvili & Yu, 2018;Plundrich et al., 2015;Szymkiewicz & Jędrychowski, 2009;Vanga et al., 2016). ...
In this work, a novel green solvent based on the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate (EmimAc) with a superior dissolving ability to biomacromolecules was utilized to boost solubility of water-insoluble curdlan. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), circular dichroism (CD), and nuclear magnetic resonance (NMR) were used to characterize the structural changes of curdlan before and after regeneration. Thermal decomposition property of curdlan was also investigated using thermal gravimetric analysis (TGA). The results indicated after EmimAc treatment, the water-solubility of regenerated curdlan (RC) achieved 74.41 ± 0.63%. In addition, the hydrogen bonds in curdlan and its native triple helix structure were partially broken. In the meantime, new hydrogen bonds between EmimAc and curdlan formed. Moreover, the disruption of curdlan's original structure made it decreased thermostability and easier to dissolve in water. Therefore, this research can provide a feasible and effective approach for improving solubility of water-insoluble curdlan to enlarge its food and biomedical applications.
... Int Arch Allergy Immunol 2 DOI: 10.1159/000489277 roasting seem to play a pivotal role in the increased capacity of peanut allergens to bind peanut-specific IgE in the elicitation phase of the allergic response [3,6,7]. However, little information is available regarding the role of roasted peanut allergens in the initial phase of allergy, the so-called "sensitization" phase, where an immunological priming towards an allergic response takes place. ...
... It is commonly agreed that allergens from roasted peanut have an increased capacity to bind preformed peanutspecific IgE compared to raw peanut, as this has been demonstrated for several peanut allergens, including the Ara h 3 samples of this study [3,6,7,18]. However, the interaction of such thermal-processed peanut allergens with DCs in the sensitization phase of allergy is poorly understood. ...
... This result indicates that increased and/or different receptors could be involved in the enhanced uptake and internalization of Ara h 3-roas by MDDCs. During roasting, chemical reactions occur, which can modify peanut allergens and their interaction with the immune system [6,7,9]. One of the reactions that may favor this mechanism is the Maillard reaction, which is a nonenzymatic chemical reaction that occurs during roasting that implies modifications of amino groups of proteins by reducing sugars, thereby generating glycated proteins called advanced glycation end (AGE) adducts [3,19]. ...
Roasting has been implicated in the increase of peanut allergenicity due to the chemical reactions that occur during the process. However, this increase is not fully understood, and little information is available regarding the role of roasted peanut allergens in the initial phase of allergy, where dendritic cells (DCs) play a key role. We sought to analyze differences in the internalization of Ara h 3 from raw and roasted peanut by immature monocyte-derived DCs (MDDCs) and the implication of the mannose receptor in the uptake. Ara h 3 was purified from raw and roasted peanut (Ara h 3-raw and Ara h 3-roas) and labeled with a fluorescent dye. The labeled allergens were added to MDDCs obtained from 7 donors and internalization was analyzed after 10, 30, and 120 min by flow cytometry. In parallel, mannan, which blocks the mannose receptor, was added 30 min before adding the labeled allergens. Results showed that the internalization of Ara h 3-roas by MDDCs was significantly increased at every time point. However, the increase in the internalization of Ara h 3-raw was only significant after 2 h of incubation. Ara h 3-roas had an enhanced capacity to be internalized by MDDCs in comparison with Ara h 3-raw at every time point. Blocking the mannose receptor decreased the internalization of Ara h 3-roas but not Ara h 3-raw. In conclusion, the internalization of Ara h 3-roas by the MDDCs is enhanced when compared to Ara h 3-raw, and the mannose receptor might be implicated in this enhancement.
... Roasting at 120 • C for 10 min reduces trypsin inhibitor activity by 42.5%; at 45 min, the reduction is almost complete (99.9% decrease in enzyme activity), while roasting at 120 • C for 150 min completely inactivates trypsin inhibitors [52]. This may be important in the use of raw, lightly roasted or briefly fried peanuts because such treatments may preserve the trypsin inhibitory potential of the allergens Ara h 1 [53], Ara h 2 [54] and Ara h 3 [55], which in turn may hinder protein digestion in the intestine. This is particularly relevant when the content of trypsin inhibitors (Ara h 1-3) is enriched, such as in roasted peanuts ( Figure 1B), and their inhibiting activity could be partially preserved due to inefficient thermal treatment (duration and temperature of the roasting is dictated by nutritional, sensory and economic aspects). ...
... For example, Ara h 2 and Ara h 6 remain stable after 120 min of digestion due to their tightly coiled structure that resists heat and gastrointestinal digestion [117]. In addition, they possess trypsin inhibitor activities [54]. This tryptic-inhibiting activity greatly contributes to the reduced digestibility of peanut proteins and peptides in the intestinal phase, protecting the rest of the proteins against tryptic digestion [19]. ...
Thermally processed peanuts are ideal plant models for studying the relationship between allergenicity and antioxidant capacity of protein-rich foods, besides lipids, carbohydrates and phyto-chemicals. Peanut is highly praised in the human diet; however, it is rich in allergens (>75% of total proteins). One-third of peanut allergens belong to the products of genes responsible for the defence of plants against stress conditions. The proximate composition of major peanut macromolecules and polyphenols is reviewed, focusing on the identity and relative abundance of all peanut proteins derived from recent proteomic studies. The importance of thermal processing, gastrointestinal digestion (performed by INFOGEST protocol) and their influence on allergenicity and antioxidant properties of protein-rich plant food matrices is elaborated. Antioxidant properties of bioactive peptides from nuts were also considered. Moreover, there are no studies dealing simultaneously with the antioxidant and allergenic properties of protein-and polyphenol-rich foods, considering all the molecules that can significantly contribute to the antioxidant capacity during and after gastrointesti-nal digestion. In summary, proteins and carbohydrates are underappreciated sources of antioxidant power released during the gastrointestinal digestion of protein-rich plant foods, and it is crucial to decipher their antioxidant contribution in addition to polyphenols and vitamins before and after gastrointestinal digestion.
... Ara h 2 and 6 belong to the 2S albumin seed storage proteins and the prolamin superfamily [2]. The structure of Ara h 2 consists of a five-helix bundle held together by four disulfide bonds and noted to have a structure similar to trypsin inhibitors [220], and has been confirmed as having trypsin inhibitory activity [221]. Ara h 2 contains multiple hydroxyprolination motifs, DPYSPS [222], which have been shown to have profound anaphylactic potency [223]. ...
... Studies of thermally processed Ara h 1 and Ara h 3 are a challenge as they tend to become insoluble, although in roasted peanuts IgE binding shows minimal differences [252]. The trypsin inhibition activity of Ara h 2 increases after roasting [221]. Both Ara h 2 and Ara h 6 retain similar IgE reactivity after roasting and maintain their structure [253]. ...
Technological advancement and globalization have led to the spread of foods to countries where the food does not yet have a documented history of consumption, in other words, novel foods. Novel foods also encompass truly novel foods, foods that have been processed in a novel manner, and novel means of exposure. With novel foods comes the potential of food allergens that pose an uncharacterized risk to those with food allergies. Food allergies are an increasingly important facet of public health. Therefore, a deeper understanding of novel foods as well as methods to evaluate consumers’ potential risk is necessary. Literature reviews and experimental evaluations leveraging liquid chromatography-electrospray ionization-mass spectrometry were used to explore the risks posed by novel sources of food allergens. Subject sources of allergens included Acheta domesticus, the house cricket, Tenebrio molitor, the yellow mealworm; extensively thermally processed walnut hulls and peanuts, as well as smoke from the wood of tree nut trees, and vapor from E-cigarette liquids. Novel methodologies to interpret complex mass spectrometry data were developed, allowing resultant information to be used in the assessment of allergenic risk. The methodologies developed in this research expand upon the utility of mass spectrometry to evaluate potentially allergenic proteins from poorly characterized sources. Broader characterization of the hazards and risks posed by food allergens permits stakeholders to be more adequately informed regarding the risks they wish to undertake. Advisor: Philip E. Johnson
... 10,11 Ara h2 is a trypsin inhibitor owing to its intramolecular disulde bond, and shows a signicantly enhanced trypsin inhibitor property aer heat processing. [12][13][14] Peanuts can enter foods accidentally owing to cross-contamination by companies. For allergy sufferers, it is important to know whether a food product is actually free of peanuts. ...
... Ara h2 has been reported to be a trypsin inhibitor with four disulde bonds (residue positions 33-116, 45-103, 104-152, 118-160) and inhibitor activity that can be reduced by breaking disulde bonds. 14,34 The DTT-reduced and IAA-alkylated protein efficiently reduced the cysteines and, therefore, cleaved the disulde bonds. Both DTT and IAA solutions were optimized in the range of 50-900 mmol L À1 during the sample preparation process. ...
A robust ultra high performance liquid chromatography with tandem mass spectrometry method was established for quantitative analysis of the major peanut allergens Ara h1 and Ara h2 in baked foodstuffs based on their signature peptides. The tryptic peptides DLAFPGSGEQVEK and NLPQQCGLR were chosen as the targeted analytes for Ara h1 and Ara h2, respectively. Their corresponding isotope-labeled peptides DL*AFPGSGEQV*EK and NL*PQQCGL*R were synthesized and employed as internal standards to overcome matrix effects during the sample analysis. Contents of Ara h1 or Ara h2 in samples were calculated according to the measured signature peptide of Ara h1 or Ara h2 and the calibration curve established using the hydrolysates of their corresponding proteins. The LOQ was 0.30 and 0.13 mg/kg for Ara h1 and Ara h2, respectively. The developed method had a satisfied accuracy, precision and sensitivity by in-house validation. The current method was successfully employed to measure peanut allergens Ara h1 and Ara h2 in commercial baked foods. It could be considered as a robust candidate method for promoting quality control of commercial baked foods and their accurate description of allergen warning information.
... After digested by pepsin for 80 min, the samples were subsequently digested by pancreatin according to US Pharmacopoeia (Maleki et al., 2003). Aliquots (20 μL) were taken at 0 s, as well as at 1, 2, 5, 10, 20, 40 and 80 min, during the digestion. ...
... The immunogenicity of Ara h 2 would decreased significantly when they were reduced before crosslinking treatment (Wu, Lian, et al., 2017) because of the structure change (Hu, Zhao, et al., 2011;Maleki et al., 2003). The possible cross-linked peptides contained phenylalanine and tryptophan (Wu, Lian, et al., 2017), and this reaction might mask these aromatic amino acids, reducing the UV absorption peaks of LP-Ara h 2 and HP-Ara h 2. The reduction and crosslinking treatment also unfolded Ara h 2, exposed the hydrophobic amino acid residues inside, which enhanced its surface hydrophobicity. ...
Peanut is ranked among the eight major food allergens. Ara h 2 is its major allergen, recognized by more than 90% of serum IgE from peanut-allergic patients. Cross-linking catalysed by microbial transglutaminase (MTGase) is proved to be feasible to decrease the allergenicity of Ara h 2. The crosslinking reaction occurred both inter- and intra-molecular could gain products with different molecular weights. In this study, after MTGase catalysed crosslinking, the products were separated into low molecular weight part of Ara h 2 (LP-Ara h 2) and high molecular weight part of Ara h 2 (HP-Ara h 2), and the structure, digestibility, IgG and IgE binding capability of each part were analysed. Compared with LP-Ara h 2, HP-Ara h 2 was found to have looser structure, higher digestion rate and corresponding lower immunogenicity. By controlling the reaction condition to get different products, the protein desensitization processes would get a better result.
... Additionally, roasted Ara h2 has been observed to shield Ara h1 from trypsin digestion. Thus, thermal processing has been demonstrated to modify both the structure and allergenicity of peanuts [37]. Consequently, we assessed the aptamers' efficacy in mitigating the anaphylactic potential of Ara h2 in peanut butter through a degranulation assay using RBL-2H3 cells. ...
Food allergy, particularly peanut allergy (PA), is a growing health concern affecting millions globally. PA can lead to severe reactions, including fatal anaphylaxis. Despite the availability of FDA-approved therapies like Palforzia, a cure remains elusive. Current immunotherapies show promise but lack a definitive cure. This study applies an established computational biology tool to design aptamers targeting Ara h1 and Ara h2. The in silico design aims to streamline the selection process, enabling cost-effective and rapid identification of aptamer candidates. The developed aptamers (AYA22A, including AYA22AR321, AYA22AR211, and AYA22AR524), demonstrated efficacy in inhibiting degranulation of RBL-2H3 cells (rat basophilic leukemia cell line) in vitro. They showed promise in neutralizing peanut allergen-induced immune responses. The selected aptamers inhibited degranulation in RBL-2H3 cells, addressing concerns in raw peanuts. Moreover, these aptamers demonstrated stability and effectiveness in peanut plant seeds and commercial products. Our aptamers exhibited potential in modulating immune responses associated with peanut allergy. They influenced Th1/Th2 balance, indicating a role in cytokine regulation. In vitro studies also showed the aptamers’ impact on immune cell expression and cytokine production, resembling responses observed with established immunotherapies. The findings suggest AYA22A aptamers as a potential therapeutic option for peanut allergy, providing a basis for further in vivo investigations.
... Even protein allergenicity can occur or be maintained after heat treatment. Heat processing may result in the formation of "neoallergenic" ingredients or epitopes, in other words, heat processing enhances the allergenicity of certain allergenic foods [24, 39,92]. According to Davis and Williams [39], one patient with a reported allergy had an allergic reaction after consuming fish that had been cooked but did not experience a reaction after consuming raw fish. ...
Sustainable food practices within the food industry are pertinent to allow efficient food supply while not negatively impacting the environment. Alternative proteins have gained the attention of the food industry and consumers. To provide safe novel food products, these protein sources need to be assessed for potential allergen risk to ensure food safety and allow effective labelling to protect the consumer. In this review, the various detection assays applied to target potential allergens in novel and alternative foods are described together with their applications, mechanisms and limitations. Additionally, the use of non-thermal technologies to mitigate the reactivity of food allergens in these new products is explored. Non-thermal techniques including cold plasma, pulsed electric field, ultrasound and gamma irradiation are discussed. This review examines the potential mechanisms by which non-thermal technologies may reduce food allergenicity, primarily through alterations in protein epitopes that could affect antibody recognition. However, it is important to note that the understanding of the precise mechanisms and outcomes in allergen mitigation through these methods remains an area requiring further research.
... Research has shown that the commonly used roasting process does not reduce the allergenic properties of proteins from the 2S albumin group [3]. It may even increase the allergenic properties of these proteins [4]. In addition, strict elimination of peanuts from one's diet may be difficult given their widespread presence in various foods, contamination during the food manufacturing process, and misreading labels or ingredient information in restaurants. ...
Peanut allergy (PA) poses significant clinical challenges due to its potentially life-threatening nature and increasing prevalence, particularly in children. Strict avoidance is difficult due to the widespread presence of peanuts in various foods, leading to high rates of accidental exposure. Traditional management includes education, avoidance, and rescue medication. Recent advances in immunotherapy offer promising avenues for the management of PA. Various methods of immunotherapy have been investigated, including oral immunotherapy (OIT), sublingual immunotherapy (SLIT), and epicutaneous immunotherapy (EPIT). Immunotherapy is associated with challenges such as adverse effects, the risk of anaphylaxis, and the long-term persistence of tolerance. Combining immunotherapy with adjuvants such as omalizumab and dupilumab or probiotics is promising, but it raises questions about sustained efficacy and patient response after treatment discontinuation. In addition, the translation of clinical trial results into real-world settings remains a critical issue, as shown by low participation rates in immunotherapy programs. Immunotherapy for peanut allergy has the potential to be a game-changer in the treatment of peanut allergies. However, it is important to note that this treatment is not without its challenges. Further research, collaboration between clinicians and researchers, and addressing patient concerns are needed to establish immunotherapy as a safe and effective treatment option for individuals with peanut allergy.
... Its prevalence is on the rise because of the widespread use of peanut products, which has made food processors to be more proactive in their responsibility in preventing peanut contamination by implementing good manufacturing practices (GMPs) and allergen control programs based on proven technologies/regimes that effectively monitor allergen cross-contamination. Reports indicate that peanut allergies cause most of the annual emergency department admissions from food allergies and up to 63% to 67% of deaths caused by anaphylaxis [39,40]. Unlike most other types of food allergies such as milk, egg, wheat, and soy that resolve in childhood, peanut allergies (PAs) persist in 75-80% of children into adulthood [41]. ...
Reaction to food allergens is on the increase and so is the attending cost on consumers, the food industry, and society at large. According to FDA, the “big-eight” allergens found in foods include wheat (gluten), peanuts, egg, shellfish, milk, tree nuts, fish, and soybeans. Sesame was added to the list in 2023, making the target allergen list nine instead of eight. These allergenic foods are major ingredients in many food products that can cause severe reactions in those allergic to them if found at a dose that can elicit a reaction. Defining the level of contamination that can elicit sensitivity is a work in progress. The first step in preventing an allergic reaction is reliable detection, then an effective quantification method. These are critical steps in keeping contaminated foods out of the supply chain of foods with allergen-free labels. The conventional methods of chemical assay, DNA-PCR, and enzyme protocols like enzyme-linked immunosorbent assay are effective in allergen detection but slow in providing a response. Most of these methods are incapable of quantifying the level of allergen contamination. There are emerging non-destructive methods that combine the power of sensors and machine learning to provide reliable detection and quantification. This review paper highlights some of the critical information on the types of prevalent food allergens, the mechanism of an allergic reaction in humans, the measure of allergenic sensitivity and eliciting doses, and the conventional and emerging AI-based methods of detection and quantification—the merits and downsides of each type.
... Accordingto the observations taken during the systematic conduction of the experiment with good maintenance of the experimental plots, we have concluded that as the branching of groundnut increases, the yield also increases, respectively. However, the extent of increase in yield and branching varies for different treatments and those differences in the yield obtained were given below: [7], Nagar R, et al. [8], Oppong SD, et al. [9], Thilini SPLNK, et al. [10], Gawas D, et al. [11], Magagula N, et al. [12], Sathiya K, et al. [13], Mohanty P, et al. [14], Ibrahim II, et al. [15], Yilmaz M, et al. [16], Iddrisu A, et al. [17], Singh N, et al. [18], El Naim AM, et al. [19], Seijo G, et al. [20], Maleki SJ, et al. [21], Michael CY, et al. [22], Sanders TH, et al. [23,24], Veeramani P, et al. [25]. ...
The experiment was carried out at college of agriculture, karekere, hassan agricultural farm during year June 2022 to November 2022. The objective of this investigation was to study the effects of five different treatments nipping, passing empty drums, withhold of irrigation, nipping without irrigation and remaining cultural practices done at 20,20,30,30 and 30 days after sowing on the number of branches and yield of groundnut. A randomized complete block design with four replications was used in this experiment. The data was recorded based on different treatments on above mentioned days before and after sowing. The recorded results were observed as follows: no of branches recorded were nipping, passing of empty drums, withholding of irrigation, nipping without irrigation and following usually recommended practices were 19,21,15,21 and 15 respectively. The yield obtained in different treatment plots were 46.6, 53.9, 38.4, 58.5 (failure due to heavy rain) and 38.4 Q/ha, respectively. So, by observing the above results, we can conclude that the passing empty drums method showed high branches and high yield compared to other treatments. So, this cultural treatment can be recommended to farmers for increasing both yield and branches.
... These proteins possess a small, compact structure rich in disulfide bonds and act as a storage reserve during seed germination. They include Ara h 1, Ara h 2 from peanut, Tri a 28, Tri a 29, Tri a 30, Tri a 33, Tri a 39, and Tri a 40 from wheat (Table 1; Maleki et al., 2003; Figure 5). ...
In addition to the challenge of meeting global demand for food production, there are increasing concerns about food safety and the need to protect consumer health from the negative effects of foodborne allergies. Certain bio‐molecules (usually proteins) present in food can act as allergens that trigger unusual immunological reactions, with potentially life‐threatening consequences. The relentless working lifestyles of the modern era often incorporate poor eating habits that include readymade prepackaged and processed foods, which contain additives such as peanuts, tree nuts, wheat, and soy‐based products, rather than traditional home cooking. Of the predominant allergenic foods (soybean, wheat, fish, peanut, shellfish, tree nuts, eggs, and milk), peanuts (Arachis hypogaea) are the best characterized source of allergens, followed by tree nuts (Juglans regia, Prunus amygdalus, Corylus avellana, Carya illinoinensis, Anacardium occidentale, Pistacia vera, Bertholletia excels), wheat (Triticum aestivum), soybeans (Glycine max), and kidney beans (Phaseolus vulgaris). The prevalence of food allergies has risen significantly in recent years including chance of accidental exposure to such foods. In contrast, the standards of detection, diagnosis, and cure have not kept pace and unfortunately are often suboptimal. In this review, we mainly focus on the prevalence of allergies associated with peanut, tree nuts, wheat, soybean, and kidney bean, highlighting their physiological properties and functions as well as considering research directions for tailoring allergen gene expression. In particular, we discuss how recent advances in molecular breeding, genetic engineering, and genome editing can be used to develop potential low allergen food crops that protect consumer health.
... Although boiling can reduce peanut allergenicity, other studies have found that roasting increases the allergenicity of peanut proteins; it was hypothesized that roasting exposed the antigenic epitopes of peanut allergens and increased their allergenicity [21]. Some studies found that roasting increased the activity of the peanut allergen Ara h 2 and made it more difficult to digest, thus increasing allergenicity [22]. In addition to boiling and roasting, other heat treatments such as microwave heating and baking have different effects on food allergens. ...
... Furthermore, food preparation, and manner of food ingestion also affect allergenicity. The studies conducted on pea nut indicate that Millard reaction due to high temperature roasting (180 0 c) and emulsification due to adjuvant effect are the example which describes how the food preparation methods affect the food allergenicity 4 ,, 18 . The Meta -analysis study conducted on fruits and vegetables accounts that allergic reactions shifted from 0.1 -1.4 for tree nuts, fruits about 0.1 -4.3 % and for vegetables under1 %. ...
Allergic reactions to foods influence a remarkable amount of population and are related with significant wellbeing results. It is one of the most significant issues that have expanding consideration. Current comprehension of the turn of events and utilization of allergenic capability of certain types of food proteins is restricted. In spite of the fact that there is a selection of in vivo models for assessing hypersensitivity, none of the current models has been approved, is prescient, or generally acknowledged with respect to their allergen explicit inhibitors. Hence, there is a proceeded with enthusiasm on the knowledge recovery based on food allergy so as to give more enlightening way to the current research field. In this paper, the current status of purification, characterization, and types of food allergens and their impacts is thoroughly reviewed. The present available methods for the allergen assessment (in view of animal, cell and clinical methodologies) are emphasized.
... e ark. 2000). h 2: Ara h 2, 17,5 kDa'lık bir glikoproteindir ve başlangıçta ham fıstık özlerinden tanımlanmıştır. Ara h 2, 2S albümin ailesinden, yani delta conglutin'den bir proteine benzeyen 5,2 izoelektrik noktaya (pI) sahip bir glikoproteindir. Ara h 2'nin bir tripsin inhibitörü olarak hareket edebilen bir depolama proteini olduğu bilinmektedir(Maleki ve ark. 2003). Ara h 2, sindirim enzimleri tarafından bozulmaya dayanabilen asidik bir proteindir, bu yüzden çoğu fıstık alerjisi hastasından serum IgE tarafından tanınabilmektedir(Sen ve ark. 2002). Ara h 3: Ara h 3, 60 kDa'lık tek zincirli bir polipeptittir ve Ara h 2 ve Ara h 6'dan daha az kararlı enzimatik (pepsin) etkiye yanıt veren glisin ailes ...
... Over 150 different foods are said to cause food-allergic reactions (15). In general, although a wide diversity of food can trigger an abnormal immune response, about 90% of such reactions are principally caused by the big 8 foods, i.e., eggs, cow's milk, peanuts, tree nuts, soy, wheat, fish and shellfish (16). The food sources of allergenic peptides/proteins are generally classified as follows. ...
... Among different proteins, glycinin is nutritionally superior to the 7S con-glycinins [69], and possesses superior intrinsic functional properties for processed foods [70]. Processing technology has the capability of altering the protein structure, function, and physicochemical properties of peanuts [71][72][73][74][75][76]. ...
Peanut (Arachis hypogaea L.) is an important grain legume crop of tropics and subtropics. It is increasingly being accepted as a functional food and protein extender in developing countries. The seed contains 36% to 54% oil, 16% to 36% protein, and 10% to 20% carbohydrates with high amounts of P, Mg, Ca, riboflavin, niacin, folic acid, vitamin E, resveratrol and amino acids. Seed contains 32 different proteins comprised of albumins and globulins. The two-globulin fractions, arachin and non-arachin, comprise approximately 87% of the peanut seed proteins. Peanut worldwide is mainly used for oil production, consumption as raw, roasted, baked products, peanut butter, peanut flour, extender in meat product formulations, confectionary and soups. Peanut proteins have many properties such as good solubility, foaming, water/oil binding, emulsification that make them useful in various food products. Very limited studies have been carried out in peanut functional properties, which has been reviewed in the present article. Adequate modifications can be done in protein functionality that are influenced by pH, temperature, pressure etc. However, some individuals develop severe IgE-mediated allergies to peanut seed proteins. Thus, methods to improve nutrition and reduce allergenicity have also been discussed. Within the last decade, manipulations have been done to alter peanut chemistry and improve nutritional quality of peanuts and peanut products. Hence, improved comprehensive understanding of functional properties and nutritional chemistry of peanut proteins can generate better source of food grain to meet nutritional requirement of growing population. In the present review, composition of peanut seed proteins, functional properties, nutritional components and nutraceutical value have been discussed with respect to beneficial aspects to health, reducing hunger and usage in food end products.
... At an individual level, Ara h 2 purified from roasted peanuts was found to have higher IgE-binding properties than Ara h 2 purified from the raw form. In addition to the increase in the allergenic potential of peanut, it has been observed that roasting enhances the trypsin inhibitor activity of Ara h 2 [12]. The chemical reactions that occur in peanuts during roasting, such as Maillard reactions, involving the modification of protein amino groups by reducing sugars during roasting, contribute to the increase of the IgE recognition of roasted peanut allergens [9,13,14]. ...
Ara h 2 is a relevant peanut allergen linked to severe allergic reactions. The interaction of Ara h 2 with components of the sensitization phase of food allergy (e.g., dendritic cells) has not been investigated, and could be key to understanding the allergenic potential of this allergen. In this study, we aimed to analyze such interactions and the possible mechanism involved. Ara h 2 was purified from two forms of peanut, raw and roasted, and labeled with a fluorescent dye. Human monocyte-derived dendritic cells (MDDCs) were obtained, and experiments of Ara h 2 internalization by MDDCs were carried out. The role of the mannose receptor in the internalization of Ara h 2 from raw and roasted peanuts was also investigated. Results showed that Ara h 2 internalization by MDDCs was both time and dose dependent. Mannose receptors in MDDCs had a greater implication in the internalization of Ara h 2 from roasted peanuts. However, this receptor was also important in the internalization of Ara h 2 from raw peanuts, as opposed to other allergens such as raw Ara h 3.
... However, some work exists that links the allergen proteins to defense against insects and pathogens. Ara h 2 is a trypsin inhibitor [7] and this function has been shown to control insect attacks, a feature that is being used in breeding programs for insect tolerance during seed storage [70]. The 2S albumin protein family, to which Ara h 2 and Ara h 6 belong, was demonstrated to be effective in inhibiting the growth of fungi and bacteria in radish seeds and four other members of the mustard family Brassicaceae [71]. ...
Food allergies are severe immune responses to plant and animal products mediated by immunoglobulin E (IgE). Peanuts (Arachis hypogaea L.) are among the top 15 crops that feed the world. However, peanuts is among the “big eight food allergens”, and allergies induced by peanuts are a significant public health problem and a life-threatening concern. Targeted mutation studies in peanuts demonstrate that single residue alterations in these allergen proteins could result in substantial reduction in allergenicity. Knowledge of peanut allergen proteins is confined to the allotetraploid crop and its two progenitors. We explored frequencies and positions of natural mutations in the hyperallergenic homologues Ara h 2 and Ara h 6 in newly generated sequences for 24 Arachis wild species and the crop species, assessed potential mutational impact on allergenicity using immunoblots and structural modeling, and evaluated whether these mutations follow evolutionary trends. We uncovered a wealth of natural mutations, both substitutions and gaps, including the elimination of immunodominant epitopes in some species. These molecular alterations appear to be associated with substantial reductions in allergenicity. The study demonstrated that Ara h 2 and Ara h 6 follow contrasting modes of natural selection and opposing mutational patterns, particularly in epitope regions. Phylogenetic analysis revealed a progressive trend towards immunodominant epitope evolution in Ara h 2. The findings provide valuable insight into the interactions among mutations, protein structure and immune system response, thus presenting a valuable platform for future manipulation of allergens to minimize, treat or eliminate allergenicity. The study strongly encourages exploration of genepools of economically important plants in allergenicity research.
... The manufacture of food is a key stage in where their allergenicity may be modified by diverse factors, so that the allergenic potential may be decreased, unchanged or even increased by the corresponding processing and storage (Maleki et al., 2003). ...
... Although, Ara h 2 is a 2S albumin from peanut and shows some homology to the LTPs (both belong to the prolamin superfamily), the domain responsible for lipid-binding is not present in the Ara h 2 molecule (45). However, Ara h 2 functions as a trypsin inhibitor and is able to prevent the degradation of further accompanying allergens such as Ara h 1 (46). In addition, roasting of peanut increases the IgE-binding potential of Ara h 2 by up to 90-fold (47). ...
Molecular allergology research has provided valuable information on the structure and function of single allergenic molecules. There are several allergens in food and inhalant allergen sources that are able to interact with lipid ligands via different structural features: hydrophobic pockets, hydrophobic cavities, or specialized domains. For only a few of these allergens information on their associated ligands is already available. Several of the allergens are clinically relevant, so that it is highly probable that the individual structural features with which they interact with lipids have a direct effect on their allergenic potential, and thus on allergy development. There is some evidence for a protective effect of lipids delaying the enzymatic digestion of the peanut (Arachis hypogaea) allergen Ara h 8 (hydrophobic pocket), probably allowing this molecule to get to the intestinal immune system intact (sensitization). Oleosins from different food allergen sources are part of lipid storage organelles and potential marker allergens for the severity of the allergic reaction. House dust mite (HDM), is more often associated with allergic asthma than other sources of inhalant allergens. In particular, lipid-associated allergens from Dermatophagoides pteronyssinus which are Der p 2, Der p 5, Der p 7, Der p 13, Der p 14, and Der p 21 have been reported to be associated with severe allergic reactions and respiratory symptoms such as asthma. The exact mechanism of interaction of these allergens with lipids still has to be elucidated. Apart from single allergens glycolipids have been shown to directly induce allergic inflammation. Several—in parts conflicting—data exist on the lipid (and allergen) and toll-like receptor interactions. For only few single allergens mechanistic studies were performed on their interaction with the air-liquid interface of the lungs, in particular with the surfactant components SP-A and SP-D. The increasing knowledge on protein-lipid-interaction for lipophilic and hydrophobic food and inhalant allergens on the basis of their particular structure, of their capacity to be integral part of membranes (like the oleosins), and their ability to interact with membranes, surfactant components, and transport lipids (like the lipid transfer proteins) are essential to eventually clarify allergy and asthma development.
... The average % α-helix content of native Ara h 2 was 33 ± 2 (SE) (average of five separate accumulated, and solvent-corrected spectra). This is in agreement with a previous analysis that showed that Ara h 2 has α-helical content between 30% and 60% (Maleki et al., 2003). Results showed that PAC C1 and chlorogenic acid, but not benzoic acid, delphinidin-3-glucoside, or cyanidin-3-glucoside, resulted in changes in Ara h 2 secondary structures (Fig. 3). ...
The potential for 42 different polyphenols found in Vaccinium fruits to bind to peanut allergen Ara h 2 and inhibit IgE binding epitopes was investigated using cheminformatics techniques. Out of 12 predicted binders, delphinidin-3-glucoside, cyanidin-3-glucoside, procyanidin C1, and chlorogenic acid were further evaluated in vitro. Circular dichroism, UV–Vis spectroscopy, and immunoblotting determined their capacity to (i) bind to Ara h 2, (ii) induce protein secondary structural changes, and (iii) inhibit IgE binding epitopes. UV–Vis spectroscopy clearly indicated that procyanidin C1 and chlorogenic acid interacted with Ara h 2, and circular dichroism results suggested that interactions with these polyphenols resulted in changes to Ara h 2 secondary structures. Immunoblotting showed that procyanidin C1 and chlorogenic acid bound to Ara h 2 significantly decreased the IgE binding capacity by 37% and 50%, respectively. These results suggest that certain polyphenols can inhibit IgE recognition of Ara h 2 by obstructing linear IgE epitopes.
... It had been reported that the structure of Ara h 1 after roasting (Maillard reaction) was retained and with better IgE-binding properties, which might be due to alterations such as chemical modifications on the amino acids or increased epitope exposure (Nesbit et al., 2012). The Ara h 2 also had higher IgE-binding properties after the Mallard reaction (Maleki, Chung, Champagne, & Khalifah, 2001), and with higher anti-trypsin digestibility (Maleki et al., 2003). While the IgE binding to the Ara h 2 isoforms is diffusing, for the purposes of our assessments we showed this as a decrease in IgE binding. ...
Peanuts contain four major allergens with differences in allergenic potency. Thermal processing can influence the allergenic properties of peanuts. Until now, a kinetic model has not been reported to assess the changes of soluble allergen (extracted from processed peanuts) content as affected by various thermal processing methods. Our objective is to characterize the reaction kinetics of the thermal processing methods, including wet processing (boiling with/without high-pressure, steaming with/without high-pressure), deep-frying and dry processing (microwaving and roasting) using five time intervals. The relationships between processing time and extractable major allergen content could be explained by a simple linear regression kinetic model (except high-pressure steaming). Among all the methods with optimal processing point, frying for 6 min had a relatively lower IgE binding (linear epitopes) ratio, possibly due to the processing conditions, which caused break down, cross-linking and aggregation of Ara h 2, and a relatively lower solubility.
... These sugar modifications also render allergens less digestible and can result in larger protein fragments, containing multiple IgE binding sites, to survive digestive enzymes in the gut [16], which are then more capable of cross-linking IgE on the surface of mast cells and causing degranulation. The role of food processing on the allergenic properties of ingested foods has been reported by other studies [10,11,[17][18][19][20][21][22][23][24]. Roasting-induced structural changes and chemical mechanisms for increased allergenic properties of the peanut allergens were previously explored in a simulated roasting model [10]. ...
Roasting is known to change the allergenic properties of peanuts. To study these observations at a molecular level, the relationship of IgE binding to the structure of Ara h 3 from raw and roasted peanuts was assessed. Ara h 3 (A3) was purified from raw (R), light roast (LR) and dark roast (DR) peanuts, the purity was assessed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and the secondary structures were compared with circular dichroism (CD) spectroscopy. In order to understand the contribution of structure to IgE binding, the R A3 was partially denatured (PD) by heat treatment (65 °C for 2 h), subjected to CD spectroscopy and IgE spot blot analysis with sera from peanut- allergic individuals. While we observed that the secondary structure of purified A3 from R and LR peanut in solution was affected by the reduction of disulfide bonds and heat treatment when purified from the peanut following the roasting process, only small alterations were seen in the secondary structure. The purified LR A3 bound higher levels of IgE than the RA3. CD spectroscopy of PD A3 revealed a reduction in the percentage of alpha helices, and serum IgE binding. Therefore, while A3 purified from roasted peanuts did not show significant changes in secondary structure, it showed higher IgE binding than R A3. Therefore, the higher IgE binding to LR A3 was more likely to be due to chemical modifications than structural changes. However, a decrease in the IgE binding was seen if R A3 was deliberately unfolded, indicating that the structure played an important role in IgE binding to A3.
... For example, mouse models show the use of antacids increase sensitization to food allergens, potentially by neutralizing gastric proteases (Pali-Scholl and Jensen-Jarolim, 2011;Untersmayr et al., 2003). The peanut allergen, Ara h 2, contains inhibitory sequences to trypsin, resulting in a decrease in its digestibility (Maleki et al., 2003). However, other studies have challenged this correlation between protein digestibility and protein allergenicity (Fu et al., 2002;Herman et al., 2007). ...
To what extent do structural and biophysical features of food allergen proteins distinguish them from other proteins in our diet? Invertebrate tropomyosins (Tpms) as a class are considered "pan-allergens," inducing food allergy to shellfish and respiratory allergy to dust mites. Vertebrate Tpms are not known to elicit allergy or cross-reactivity, despite their high structural similarity and sequence identity to invertebrate homologs. We expect allergens are sufficiently stable against gastrointestinal proteases to survive for immune sensitization in the intestines, and that proteolytic stability will correlate with thermodynamic stability. Thermal denaturation of shrimp Tpm shows that it is more stable than non-allergen vertebrate Tpm. Shrimp Tpm is also more resistant to digestion. Molecular dynamics uncover local dynamics that select epitopes and global differences in flexibility between shrimp and pig Tpm that discriminate allergens from non-allergens. Molecular determinants of allergenicity depend not only on sequence but on contributions of protein structure and dynamics.
Recent applications of HPP are reviewed for allergenicity reduction in foods, preservation of essential fatty acids, and reduction of salt content. HPP has shown good potential to manipulate functionality, retain essential fatty acids, and reduce allergenicity in foods.KeywordsHPPAllergenicity reductionRetention of lipidsSalt reduction
Background:
Understanding differences in sensitization profiles at the molecular allergen level is important for diagnosis, personalised treatment and prevention strategies in allergy.
Methods:
IgE sensitization profiles were determined in more than 2800 sera from children in 9 population-based cohorts in different geographical regions of Europe; north (BAMSE (Sweden), ECA (Norway)), west/central (PIAMA (the Netherlands), BiB (UK), GINIplus (Germany)), and south (INMA Sabadell and Gipuzkoa (Spain) and ROBBIC Rome and Bologna (Italy)) using the MeDALL-allergen chip.
Results:
Sensitization to grass pollen allergen, Phl p 1, and to major cat allergen, Fel d 1, dominated in most European regions whereas sensitization to house dust mite allergens Der p 1, 2 and 23 varied considerably between regions and were lowest in the north. Less than half of children from Sabadell which has a hot and dry climate were sensitized to respiratory allergens, in particular house dust mite allergens as compared to Gipuzkoa nearby with a more humid climate. Peanut allergen Ara h 1 was the most frequently recognized class 1 food allergen in Northern/Western Europe, while the fruit allergens Pru p 3, Act d 1 and 2 were prominent in Southern and Western/Central Europe. Ves v 5-sensitization dominated in North and West/Central Europe.
Conclusion:
We show regional, exposome and climate-dependent differences in molecular IgE-reactivity profiles in Northern, Western/Central and Southern Europe which may form a molecular basis for precision medicine-based approaches for treatment and prevention of allergy.
Peanut allergens adversely affect the health and quality of life of millions of consumers worldwide. The seeds of the peanut plant (Arachis hypogaea L.) contain a number of allergens that trigger the production of specific IgE antibodies in allergy-prone individuals. Currently, 18 proteins found in peanuts are accepted as allergens. These allergens are named from Ara h 1 to Ara h 18. Ara h 2, Ara h 6 and Ara h 7 are from albumin, Ara h 1 and Ara h 3 are from globülin. Ara h is the abbreviation of Arachis hypogaea, the Latin name for peanut. A peanut allergy is a reaction that occurs shortly after eating to peanuts or peanut products. It has various symptoms that can go up to swelling of the tongue, itching of the palate, itching and burning in the throat, itching in the eyes and nose, nausea, vomiting, abdominal pain, shortness of breath, wheezing, bruising, chest pain, hives, low blood pressure and shock. In this review, the properties of peanut allergens and the methods of reducing the allergen effect will be reviewed.
The chapter on "Food Allergens" in the Japanese Guidelines for Food Allergy 2021 was written to organize the knowledge required for an overview of food allergens. First, general knowledge of allergens was mentioned, including the fact that the majority of food allergens are proteins, knowledge of allergen epitopes and mechanisms of allergen reduction. Next, the confusingly used terms cross-antigenicity and clinical cross-reactivity were explained, noting that cross-antigenicity does not necessarily mean clinical cross-reactivity and the extent to which clinical cross-reactivity occurs between foods that exhibit cross-antigenicity. Four protein superfamilies containing most plant food allergens, prolamin, cupin, Bet v 1 homolog [pathogenesis-related protein: PR-10], and profilin, and three protein superfamilies containing most animal food allergens, tropomyosin, parvalbumin, and casein, are described.
Cover design molecule: Model of the major peanut allergen, Ara h 1, produced with the MPACK suite. (C. H. Schein and coworkers, 2006.) Address editorial correspondence to ASM
Peanut allergy is among the most widespread and life-threatening food allergies. Roasting was conducted to improve the sensorial quality of peanut and to change the structure and allergenicity of allergens. The potential allergenicity of digested defatted peanut powder did not significantly differ between raw and roasted peanuts. The raw/roasted peanut proteins were digested by trypsin and then analyzed with isobaric tags for relative and absolute quantitation (iTRAQ) to discover the changes in peptide quantity. Among the 44 detected peptides, the abundance of 29 peptides significantly increased by up to 36.78 times after roasting. Among those 29 peptides, seventeen peptides overlapped with linear IgE-binding epitopes, which were either destroyed or exposed after roasting. Combined with the spatial structure model, the iTRAQ result indicated the breaking of disulfide bonds and depolymerization of proteins during roasting. Roasting changed the conformational structure of protein, which increased allergen digestibility but did not guarantee a decrease in the potential allergenicity of peanut.
Peanut is rich in oils and proteins, which are found in oil bodies (OBs) and protein bodies (PBs), respectively. In this study, composition of proteins, neutral lipids, and phospholipids in crude OBs extracted by aqueous enzymatic extraction were analyzed. Distribution of oil, protein, and phospholipid in OBs was observed by confocal laser scanning microscopy (CLSM). Major proteins identified in OBs included oleosin, caleosin, and steroleosin. Lipoxygenase, arachin, conarachin, allergen, and ferritin, were also loosely associated with the surface of crude OBs. There were weak interactions between adsorbed proteins and OBs, such as electrostatic interactions, hydrophobic interactions, and hydrogen bonding. Results showed that fatty acids of crude OBs were rich in oleic acid (40.70%) and linoleic acid (35.01%). Phospholipids were mainly composed of phosphatidyl choline, phosphatidyl inositol, phosphatidyl ethanolamine, and phosphatidic acid, with relative contents of 54.87, 23.04, 16.76, and 5.33%, respectively. CLSM of OBs revealed oil droplets evenly distributed in aqueous phase and uniform distribution of proteins and phospholipids at oil droplets surface. This study provides new insights into composition and structure of peanut OBs and theoretical basis for demulsification.
Nuts confer many health benefits due to of their high content of vitamins and 10 antioxidants and they are increasingly consumed in the last years. Currently, tree nuts are included 11 in the list with the most allergenic ingredients, and its presence must be indicated in label foods. 12 Most nut allergens are seed storage proteins, lipid transfer proteins (LTP), profilins and homologous 13 to pathogenesis-related (PR) proteins. A common feature of the nut allergenic proteins is their 14 resistance to proteolysis and denaturation. Food processing is an important industrial tool to modify 15 allergenic properties of foods, in addition to ensure safety and to enhance organoleptic 16 characteristics. Food processing can alter the structure, function and properties of proteins, and 17 thereby also modify the IgE reactivity of allergens, so that it has been proposed as a method to obtain 18 food with altered allergenicity. There are no general rules about the effect of processing on the 19 allergenicity and hence, it has the ability to generate new allergenic epitopes (neoallergens) as well 20 as to abolish the existing reactive epitopes. These effects depend on the type and duration of the 21 treatment, as well as of the intrinsic characteristics of the protein and of the physicochemical 22 conditions of its microenvironment. Many studies have evaluated to characterize the molecular 23 changes induced by processing such as thermal, pressure or enzymatic treatments. Some daily 24 processing methods have been shown to be effective in decreasing the content of specific allergens 25 in certain foods, which may open a future path for hypoallergenic food development or pave the 26 way the use of specifically processed foods for tolerance induction. This work gives and updated 27 overview of the influence of several processing techniques (thermal, pressure and enzymatic 28 digestion) on nuts allergenicity such as, peanuts, pistachio, cashew, hazelnut, almond and walnuts 29 and their applications. 30
In recent years, clear progress has been made in the treatment and management of allergic diseases in children. The present age is considered to be a "patient-centered era". It is necessary to give due consideration to the patients' perspectives and individual lives in order to improve their quality of life. This is an era in which many situations can no longer be managed by doctors and medical technology alone, with partnerships between the medical side and the patient side more important than ever. Since medical progress is only recognized as true progress once it is reflected in clinical practice, we medical professionals must first understand the changes in the times in front of us. From the proposal, "from [cure] to [care]", we should make efforts to expand the support for multidisciplinary collaboration. We will manage a wide array of aggravating factors with a focus on patients and consider multifaceted approaches to treatment. True medical progress in modern times can only be achieved by sharing, giving back, and nurturing medical staff with an eye on our children's future based on advances in medical technology.
High-pressure processing (HPP) has an undeniable role in nonthermal food pasteurization being, among others, the most successful nonthermal processing technology, which has motivated both academia and industry to develop novel applications for HPP and new food products. HPP can lead to the development of new foods with improved texture aspects due to the “cold gelation,” a process that leads to the formation of proteins’ networks with a stable thermodynamic conformation allowing a phase transition from liquid to solid. Proteins, both from animal- and plant-based origins, are widely used to improve food products in terms of texture, flavor, and other rheological aspects. Nevertheless, when foods are submitted to HPP, they can have different responses in terms of texture, which will determine consumers’ acceptance. In this chapter, the effects of HPP on animal- and plant-based proteins are presented and discussed. Important fundamental features of proteins, such as three-dimensional confirmation, techno-functional properties, and other applications, are highlighted.
Background
Allergic reactions to food allergens usually occur after ingestion. However, fear of reactions to airborne peanut is a common concern for people with peanut allergy. There are no scientific reports on severe reactions with airborne peanut allergen.
Objective
To investigate the occurrence of allergic reactions in peanut‐allergic children undergoing airborne peanut challenge and to determine levels of airborne peanut protein in a separate experimental evaluation.
Methods
Eighty‐four children with peanut allergy underwent an airborne peanut challenge, 0.5 m from a bowl of peanuts for 30 min under controlled conditions. In a separate experiment, airborne peanut proteins from roasted and dry‐roasted peanuts were collected at varying distances and at varying times with an electret SensAbues filter connected to an air pump. Collected airborne peanut proteins were extracted, dissolved and detected by ELISA. Basophil activation test was used to confirm biological activity.
Results
No moderate/severe allergic reactions to airborne peanut allergens were observed. Two children (2%) had mild rhino‐conjunctivitis which required no treatment. The IgE‐antibodies to peanut or Ara h 2 did not predict a reaction. In the experimental set‐up, biological active peanut proteins were detected, in a very low amount, in median 166 ng/ml for dry‐roasted and 33 ng/ml for roasted peanuts and decreased dramatically when the collection occurred at a greater distance (0.5–2 m) from the peanut source. Increased exposure time did affect the amount of collected peanut protein at 0 m, and the highest median was obtained after 60 min (p = .012); for time trend p = .0006.
Conclusions and Clinical Relevance
Allergic reactions to airborne peanut proteins are rare and cannot be predicted by high levels of IgE‐antibodies to peanut or Ara h 2. Only small amounts of biologically active peanut proteins were detected in the air and seem unlikely to trigger moderate/severe allergic reactions.
To elicit an immunoglobulin E (IgE)‐mediated allergenic response, the allergen must cross‐link IgE molecules on the surface of mediator release cells. Understanding the IgE‐allergen interaction at the molecular level is therefore important in designing ways to reduce or eliminate allergenicity. This chapter describes some of the structural and molecular components that contribute to allergenicity of proteins and foods and the processes involved in altering the allergenicity of food proteins. It addresses possible options for the reduction of allergenicity in foods. The multitude of biochemical reactions that occur during processing of foods may have a variety of effects on primary, secondary, tertiary, and quaternary proteins or peptide structures that could alter allergenic properties of proteins. The physical removal of an allergen from a food source can be effective when the allergenis present in a discrete location within the food, or when the allergen is preferentially soluble or degradable.
Résumé
Introduction
La noisette est le premier allergène alimentaire en Europe en termes de prévalence chez l’adulte et chez l’enfant. Elle se situe au 4e rang des allergènes alimentaires responsables d’anaphylaxie en France chez l’enfant. L’impact sur la qualité de vie des enfants et de leur famille est d’autant plus marqué qu’elle entre dans la composition de nombreux produits transformés, souvent de manière masquée. Nous nous sommes intéressés à la composition en noisette de produits fréquemment consommés afin d’établir une échelle utilisable en test de provocation orale et, à plus long terme, en immunothérapie orale en population pédiatrique.
Méthodes
Les différents produits ont été sélectionnés en tenant compte de leur accessibilité en grande distribution et de leur attrait auprès des jeunes patients. Les poids en noisette ont été déterminés par pesée ou calcul. Le degré de cuisson a été estimé car non précisé par les industriels.
Résultats
Les compositions des produits suivants ont été rapportées : le Nutella®, les Kinder Schokobons®, les Kinder Bueno® et Bueno White®, les céréales Trésor de Kellog's®, les biscuits Gerblés pomme noisette®, les Résilles d’Or noisette®, les croissants de lune Bahlsen®, les Ferrero Rocher®, les Baiocchi® et les Duplo®. Les contenus en noisette varient de 30 mg à 4420 mg. La constitution d’une échelle de progression se heurte cependant à la difficulté d’estimation des degrés de cuisson des produits et donc de leur allergénicité.
Conclusion
Différents produits manufacturés attrayants pourraient être utilisés pour des tests de provocation orale proches de la vie réelle chez les enfants allergiques à la noisette, favorisant ainsi leur adhésion à une éventuelle immunothérapie orale ultérieure.
Food processing affects the bioavailability and immunoreactivity of allergens. However, there was a lack of the combined study of the influence of the processing and gastrointestinal digestion on peanut matrix. Digestibility of peanut matrices was assessed by using an in vitro digestion model and monitored by SDS-PAGE, immunoblotting with polyclonal antibody and serum from peanut-allergic patients. The IgE-binding ability of digested samples will be assessed by immunoassay. Peanut proteins were digested by pepsin after only 2 min which was accompanied by a loss of high molecular weight proteins and enrichment in polypeptides with molecular weight lower than 10 kDa. Ara h 1 and Ara h 3 were partly proteolysis, and Ara h 2/6 containing a digestion-resistant fragment. All soluble fractions after 120 min gastric digestion reduced a higher IgE-binding ability than that after 10 min. Our findings provide a more realistic picture, considering the role of food processing and food matrix.
Cette thèse actualise les connaissances de l'évaluation de l'allergénicité des aliments et son application au diagnostic de l'allergie alimentaire. Après la définition, les caractéristiques et la classification des allergènes alimentaires, les phénomènes physico-chimiques modifiant l'allergénicité des aliments ainsi que les réactivités croisées sont décrites. Ainsi sont introduits les outils cliniques et biologiques utiles au diagnostic de l'allergie alimentaire et à la détection des traces d'allergènes alimentaires. Une collaboration étroite entre cliniciens et chercheurs biologistes, permet d'optimiser la prise en charge diagnostique et thérapeutique de l'allergie alimentaire. Cette démarche se concrétise par la mise à disposition et l'utilisation de divers outils (développement d'allergènes recombinants, dosage de contaminants alimentaires dans des médicaments ou aliments, ...) et est illustrée par diverses mises en situation clinique réelles.
Diabetes and aging are commonly accompanied by arterio- and atherosclerosis. Infiltration of the arterial subendothelial intima by macrophages/monocytes is an important early event preceding the development of atheromatous lesions; these macrophages are known to produce mitogenic factors in early atherosclerotic lesions. It has been previously shown that, over time, vascular matrix accumulates proteins nonenzymatically modified by advanced glycosylation end products (AGEs). In view of the fact that macrophages/monocytes have AGE-specific receptors associated with the expression of several growth factors, we investigated the possibility that AGEs mediate initial monocyte-vessel wall interactions that occur before overt formation of vascular lesions. This study demonstrates that (i) in vitro- and in vivo-formed AGEs are chemotactic for human blood monocytes, (ii) sub-endothelial AGEs can selectively induce monocyte migration across an intact endothelial cell monolayer, and (iii) subsequent monocyte interaction with AGE-containing matrix results in the expression of platelet-derived growth factor. These results support the existing hypothesis that in vivo-forming glucose-derived protein adducts can act as signals for the normal turnover of senescent tissue protein by means of the AGE-specific receptor system. Time-dependent glucose-induced deposition of AGEs on matrix proteins may promote monocyte infiltration into the subendothelium. Subsequent AGE-triggered macrophage activation and consequent elaboration of proliferative factors may normally coordinate remodeling but may also lead to the diverse pathogenic changes typical of arterio- and atherosclerosis in diabetic or aging populations.
Can secondary structure prediction be improved by prediction rules that focus on a particular structural class of proteins?
To help answer this question, we have assessed the accuracy of prediction for all-helical proteins, using two conceptually
different methods and two levels of description. An overall two-state single-residue accuracy of ∼80% can be obtained by a
neural network, no matter whether it is trained on two states (helix and non-helix) or first trained on three states (helix,
strand and loop) and then evaluated on two states. For four test proteins, this is similar to the accuracy obtained with inductive
logic programming. We conclude that on the level of secondary structure, there is no practical advantage in training on two
states, especially given the added margin of error in identifying the structural class of a protein. In the further development
of these methods, it is increasingly important to focus on aspects of secondary structure that aid in the construction of
a correct 3-D model, such as the correct placement of segments.
An optimized self-organizing map algorithm has been used to obtain protein topological (proteinotopic) maps. A neural network is able to arrange a set of proteins depending on their ultraviolet circular dichroism spectra in a completely unsupervised learning process. Analysis of the proteinotopic map reveals that the network extracts the main secondary structure features even with the small number of examples used. Some methods to use the proteinotopic map for protein secondary structure prediction are tested showing a good performance in the 200-240 nm wavelength range that is likely to increase as new protein structures are known.
Nonenzymatic glycation of proteins occurs at an accelerated rate in diabetes and can lead to the formation of advanced glycation end products of proteins (AGEs), which bind to mononuclear phagocytes (MPs) and induce chemotaxis. We have isolated two cell surface-associated binding proteins that mediate the interaction of AGEs with bovine endothelial cells. One of these proteins is a new member of the immunoglobulin superfamily of receptors (termed receptor for AGEs or RAGE); and the second is a lactoferrin-like polypeptide (LF-L). Using monospecific antibodies to these two AGE-binding proteins, we detected immunoreactive material on Western blots of detergent extracts from human MPs. Radioligand-binding studies demonstrated that antibody to the binding proteins blocked 125I-AGE-albumin binding and endocytosis by MPs. Chemotaxis of human MPs induced by soluble AGE-albumin was prevented in a dose-dependent manner by intact antibodies raised to the AGE-binding proteins, F(ab')2 fragments of these antibodies and by soluble RAGE. When MP migration in response to N-formyl-Met-Leu-Phe was studied in a chemotaxis chamber with AGE-albumin adsorbed to the upper surface of the chamber membrane, movement of MPs to the lower compartment was decreased because of interaction of the glycated proteins with RAGE and LF-L on the cell surface. The capacity of AGEs to attract and retain MPs was shown by implanting polytetrafluoroethylene (PTFE) mesh impregnated with AGE-albumin into rats: within 4 d a florid mononuclear cell infiltrate was evident in contrast to the lack of a significant cellular response to PTFE with adsorbed native albumin. These data indicate that RAGE and LF-L have a central role in the interaction of AGEs with human mononuclear cells and that AGEs can serve as a nidus to attract MPs in vivo.
Ara h 1, a major peanut allergen was isolated, and its structure on secondary, tertiary, and quaternary level at ambient temperature was investigated using spectroscopic and biochemical techniques. Ara h 1 appeared to be a highly structured protein on a secondary level, possesses a clear tertiary fold, and is present as a trimeric complex. Heat treatment of purified Ara h 1 results in an endothermic, irreversible transition between 80 and 90 degreesC, leading to an increase in beta-structures and a concomitant aggregation of the protein. Ara h 1 from peanuts that were heat-treated prior to the purification procedure exhibited a similar denatured state with an increased secondary folding and a decreased solubility. The effect of heat treatment on the in vitro allergenic properties of Ara h 1 was investigated by means of a fluid-phase IgE binding assay using serum from patients with a clinically proven peanut allergy. Ara h 1 purified from peanuts heated at different temperatures exhibited IgE binding properties similar to those found for native Ara h 1, indicating that the allergenicity of Ara h 1 is heat-stable. We conclude that the allergenicity of Ara h 1 is unaffected by heating, although native Ara h 1 undergoes a significant heat-induced denaturation on a molecular level, indicating that the recognition of conformational epitopes of Ara h 1 by IgE either is not a dominant mechanism or is restricted to parts of the protein that are not sensitive to heat denaturation.
Predicting the secondary structure of a protein (alpha-helix, beta-sheet, coil) is an important step towards elucidating its three-dimensional structure, as well as its function. Presently, the best predictors are based on machine learning approaches, in particular neural network architectures with a fixed, and relatively short, input window of amino acids, centered at the prediction site. Although a fixed small window avoids overfitting problems, it does not permit capturing variable long-rang information.
We introduce a family of novel architectures which can learn to make predictions based on variable ranges of dependencies. These architectures extend recurrent neural networks, introducing non-causal bidirectional dynamics to capture both upstream and downstream information. The prediction algorithm is completed by the use of mixtures of estimators that leverage evolutionary information, expressed in terms of multiple alignments, both at the input and output levels. While our system currently achieves an overall performance close to 76% correct prediction--at least comparable to the best existing systems--the main emphasis here is on the development of new algorithmic ideas.
The executable program for predicting protein secondary structure is available from the authors free of charge.
pfbaldi@ics.uci.edu, gpollast@ics.uci.edu, brunak@cbs.dtu.dk, paolo@dsi.unifi.it.
The three-dimensional structure of the bifunctional alpha-amylase/trypsin inhibitor (RBI) from seeds of ragi (Eleusine coracana Gaertneri) has been determined in solution using multidimensional H-1 and N-15 NMR spectroscopy. The inhibitor consists of 122 amino acids, with 5 disulfide bridges, and belongs to the plant alpha-amylase/trypsin inhibitor family for which no three-dimensional structures have yet been available. The structure of the inhibitor was determined on the basis of 1131 interresidue interproton distance constraints derived from nuclear Overhauser enhancement measurements and 52 phi angles, supplemented by 9 psi and 51 chi(1) angles. RBI consists of a globular four-helix motif with a simple ''up-and-down'' topology. The helices are between residues 18-29, 37-51, 58-65, and 87-94. A fragment from Val 67 to Ser 69 and Gln 73 to Glu 75 forms an antiparallel beta-sheet. The fold of RBI represents a new motif among the serine proteinase inhibitors, The trypsin binding loop of RBI adopts the ''canonical'', substrate-like conformation which is highly conserved among serine proteinase inhibitors. The binding loop is stabilized by the two adjacent alpha-helices 1 and 2, This motif is also novel and not found in known structures of serine proteinase inhibitors, The three-dimensional structure of RBI together with biochemical data suggests the location of the alpha-amylase binding site on the face of the molecule opposite to the site of the trypsin binding loop, The RBI fold should be general for all members of the RBI family because conserved residues among the members of the family form the core of the structure.
Peanuts and soybeans are two of the six most common foods to cause food hypersensitivity reactions in children. We used the serum of 10 patients with atopic dermatitis and positive double-blind, placebo-controlled, food challenges to peanut and two patients with atopic dermatitis and positive double-blind, placebo-controlled, food challenges to soybean to investigate the change in IgE-specific and IgG-specific binding to these proteins altered by either chemical or thermal denaturation. We used IgE- and IgG-specific ELISA-inhibition analyses to compare these effects on the crude peanut and crude soy extracts, as well as on the major allergenic fractions of both proteins. Heating the soy proteins at various temperatures and time intervals did not significantly change the IgE- or IgG-specific binding of the soy positive pooled serum. When the peanut proteins were subjected to similar heating experiments, the IgE- and IgG-specific binding did not change. When these same proteins were treated with enzymes in the immobilized digestive enzyme assay system used to mimic human digestion, the binding of IgE to the crude peanut and crude soy extracts was reduced; 100-fold for peanut and 10-fold for soybean. Therefore it appears that thermal denaturation of peanut and soybean protein extracts does not enhance or reduce IgE- and IgG-specific binding activity. Chemical denaturation appears to minimally reduce the binding of these proteins.
Proteins undergo a series of nonenzymatic reactions with glucose over time to form advanced glycosylation end products (AGEs).
Macrophages have a receptor that recognizes the AGE moiety and mediates the uptake and degradation of AGE proteins. This removal
process is associated with the production and secretion of cachectin (tumor necrosis factor) and interleukin-1, two cytokines
with diverse and seemingly paradoxical biological activities. The localized release and action of these cytokines could account
for the coordinated removal and replacement of senescent extracellular matrix components in normal tissue homeostasis.
We have trained a two-layered feed-forward neural network on a non-redundant data base of 130 protein chains to predict the secondary structure of water-soluble proteins. A new key aspect is the use of evolutionary information in the form of multiple sequence alignments that are used as input in place of single sequences. The inclusion of protein family information in this form increases the prediction accuracy by six to eight percentage points. A combination of three levels of networks results in an overall three-state accuracy of 70.8% for globular proteins (sustained performance). If four membrane protein chains are included in the evaluation, the overall accuracy drops to 70.2%. The prediction is well balanced between alpha-helix, beta-strand and loop: 65% of the observed strand residues are predicted correctly. The accuracy in predicting the content of three secondary structure types is comparable to that of circular dichroism spectroscopy. The performance accuracy is verified by a sevenfold cross-validation test, and an additional test on 26 recently solved proteins. Of particular practical importance is the definition of a position-specific reliability index. For half of the residues predicted with a high level of reliability the overall accuracy increases to better than 82%. A further strength of the method is the more realistic prediction of segment length. The protein family prediction method is available for testing by academic researchers via an electronic mail server.
To investigate clinical features of acute allergic reactions to peanuts and other nuts.
Analysis of data from consecutive patients seen by one doctor over one year in an allergy clinic at a regional referral centre.
62 patients aged 11 months to 53 years seen between October 1993 and September 1994.
Type and severity of allergic reactions, age at onset of symptoms, type of nut causing allergy, results of skin prick tests, and incidence of other allergic diseases and associated allergies.
Peanuts were the commonest cause of allergy (47) followed by Brazil nut (18), almond (14), and hazelnut (13). Onset of allergic symptoms occurred by the age of 2 years in 33/60 and by the age of 7 in 55/60. Peanuts accounted for all allergies in children sensitised in the first year of life and for 82% (27/33) of allergies in children sensitised by the third year of life. Multiple allergies appeared progressively with age. The commonest symptom was facial angioedema, and the major feature accounting for life threatening reactions was laryngeal oedema. Hypotension was uncommon. Of 55 patients, 53 were atopic--that is, had positive skin results of tests to common inhaled allergens--and all 53 had other allergic disorders (asthma, rhinitis, eczema) due to several inhaled allergens and other foods.
Sensitisation, mainly to peanuts, is occurring in very young children, and multiple peanut/nut allergies appear progressively. Peanut and nut allergy is becoming common and can cause life threatening reactions. The main danger is laryngeal oedema. Young atopic children should avoid peanuts and nuts to prevent the development of this allergy.
Long-term incubation of proteins with glucose leads to the formation of advanced glycation end products (AGE). Recent immunological studies have suggested the potential role of AGE in atherosclerosis, aging, and diabetic complications. We previously prepared a monoclonal (6D12) as well as a polyclonal anti-AGE antibody and proposed the presence of a common AGE structure(s) that may act as a major immunochemical epitope [Horiuchi, S., Araki, N., & Morino, Y. (1991) J. Biol. Chem. 266, 7329-7332]. The purpose of the present study was to determine the major epitope. Amino acid analysis of AGE-proteins indicated that N(epsilon)-(carboxymethyl)lysine (CML) was a major modified lysine residue. Immunologic studies demonstrated the positive reaction of 6D12 not only to all CML-modified proteins tested, but also to BSA modified with several aldehydes known to generate a CML-protein adduct, and a linear correlation between the CML contents of CML-BSA and their immunoreactivity to 6D12 up to approximately 8 mol/mol of protein. Further experiments with CML analogs revealed that the epitope of 6D12 is a CML-protein adduct with an important carbonyl group. In contrast to 6D12, our polyclonal anti-AGE antibody showed a significant but much weaker immunoreactivity to CML-BSA, suggesting that the polyclonal antibody contains two populations, one reactive to CML (CML-PA) and the other unreactive to CML (Non-CML-PA). Non-CML-PA separated from CML-PA by CML-BSA affinity chromatography did not react with all CML-modified preparations, but retained its property to react commonly with AGE preparations obtained from proteins, lysine derivatives, and monoaminocarboxylic acids. Therefore, it is clear that a CML-protein adduct is a major immunological epitope in AGE structures, but there still exist other major epitope(s) expressed commonly in AGE-proteins.
Publisher Summary The first step in a PHD prediction is generating a multiple sequence alignment. The second step involves feeding the alignment into a neural network system. Correctness of the multiple sequence alignment is as crucial for prediction accuracy as is the fact that the alignment contains a broad spectrum of homologous sequences. This chapter describes three prediction methods that use evolutionary information as input to neural network systems to predict secondary structure (PHDsec), relative solvent accessibility (PHDacc), and transmembrane helices (PHDhtm). It illustrates the possibilities and limitations in practical applications of these methods with results from careful cross-validation experiments on large sets of unique protein structures. All predictions are made available by an automatic Email prediction service. The baseline conclusion after some 30,000 requests to the service is that 1-D predictions have become accurate enough to be used as a starting point for the expert-driven modeling of protein structure.
Advanced glycation end-products (AGEs) are formed by spontaneous chemical reactions between carbohydrates and tissue proteins. The accumulation of AGEs in long-lived proteins contributes to the age-related increase in brown colour, fluorescence and insolubilisation of lens crystallins and to the gradual crosslinking and decrease in elasticity of connective tissue collagens with age. These nonenzymatic reactions, known collectively as Maillard or browning reactions, are also implicated in the development of pathophysiology in age-related diseases such as diabetes mellitus, atherosclerosis, Alzheimer’s disease, and in dialysis-related amyloidosis. Oxygen and oxidation reactions accelerates Maillard reactions in vitro, and the structurally characterised AGEs that accumulate in long-lived tissue proteins are in fact glycoxidation products, formed by sequential glycation and oxidation reactions.
In addition to their immediate effects on protein structure and function, AGEs also induce oxidative stress, leading to inflammation and propagation of tissue damage. Thus, glycation of protein, formation of AGEs and resultant oxidative stress, which accelerate Maillard reactions, can initiate an autocatalytic cycle of deleterious reactions in tissues.
Pharmacological inhibition of the Maillard reaction should improve the prognosis for a broad range of age-related diseases. The role of oxidative stress as a catalyst and the consequences of Maillard reaction damage in tissues suggests that antioxidant therapy may also retard the progression of age-related pathology.
Virtually all food allergens are proteins, although only a small percentage of the many proteins in foods are allergens. Any food that contains protein has the potential to cause allergic reactions in some individuals. However, a few foods or food groups are known to cause allergies on a more frequent basis than other foods. At a 1995 consultation on food allergies sponsored by the Food and Agriculture Organization, a group of international experts confirmed that peanuts, soybeans, crustacea, fish, cow’s milk, eggs, tree nuts, and wheat are the most common allergenic foods. These foods are responsible for more than 90% of serious allergic reactions to foods. Allergies to certain fresh fruits and vegetables are also rather common, but the allergens tend to be labile to processing and cooking and the symptoms are mild and confined primarily to the oropharyngeal area. The prevalence of allergic sensitivities to specific foods varies from one country to another depending on the frequency with which the food is eaten in that country and the typical age at its introduction into the diet. For example, peanuts are a much more frequent cause of food allergies in the United States than in most other countries. Americans eat peanuts more often and introduce peanut butter into the diet of children at an early age. The Japanese probably experience more soybean and rice allergies than some other cultures because of the frequency of these two foods in the Japanese diet. Scandinavians have a high incidence of codfish allergy for similar reasons. Table 1 provides a listing of the most common allergenic foods and food groups compiled from a thorough search of the medical literature. Table 2 provides a listing of the less common allergenic foods. Only some of the foods listed in this table have been documented to cause severe, life-threatening allergic reactions. Citations are provided to studies and/or case reports that document the allergenicity of those particular foods. The absence of a particular food on this list may not mean that it is nonallergenic but may indicate that its allergenicity has not been documented. Conversely, the presence of a specific food on the list merely indicates that it has been listed in one or more reports as a cause of food allergy and does not indicate the prevalence or potential as an allergenic food.
Aging pathogenesis involves non-enzymatic modifications of proteins; protein oxidation, glycation and their interactions have aroused a particular interest. Possible interrelations between oxidation and glycation have been evaluated in vitro: bovine serum albumin was oxidized by gamma-irradiation and then exposed to in vitro glycation. Fluorescence modifications induced by radiolytic oxidation and glycation were similar and tended to be additive. Both non-enzymatic processes provoked a loss of free sulfhydryl groups and a strong increment of protein carbonyl content: this supports that glycation can act through oxidative mechanisms. The observed rearrangement of amino groups after irradiation could predispose proteins to glycation attacks. Protein peroxides generated during irradiation appear able to give birth to further protein modifications leading to the generation of carbonyl groups and to interact with monosaccharides, probably stimulating their autoxidation and in turn glycative protein damage. Glycation increases the oxidation-mediated structural damage revealed by SDS-PAGE. Therefore our data support the hypothesis of mutual enhancement between oxidation and glycation of proteins and suggest possible molecular mechanisms of interactions.
Processing of foods induces changes in their physical, chemical and sensory characteristics. Many researchers have shown the chemical consequences of food processing on acceptability and sensory attributes, nutritive value and wholesomeness of foods. A cursory account of these changes is provided.
We demonstrated recently that mite-allergic patients differed from healthy controls in the specificity of their IgG antibodies towards mite antigens.
The present study investigates whether these discriminatory IgG responses could be associated with the expression and the evolution of clinical manifestations in allergy to cow's milk proteins.
Antibody specificity was evaluated by comparing IgG-binding to native bovine beta-lactoglobulin (nBLG) and its products of pepsin hydrolysis (dBLG) using a solid-phase enzyme-linked immunosorbent assay (ELISA). Antibody specificity was further investigated in competitive ELISA using streptavidin-biotin technology with purified IgG fractions from selected subjects and specific mouse monoclonals raised against BLG.
IgG antibodies from CM-intolerant or allergic sera (n=222) showed a higher degree of binding to nBLG than to dBLG, while control sera showed similar levels to both nBLG and dBLG (n=99 children/65 adults). Sera from symptomatic patients, wether or not they contained IgE antibodies, demonstrated group-segregating capacities to compete with pooled purified IgG from each clinical class, and with selected murine anti-nBLG monoclonal antibodies for binding to n- and dBLG. Furthermore, this inhibitory capacity shifted dramatically in a small subset (n=14) of children as they developed CM-tolerance.
The IgG responses to BLG of CM-intolerant or allergic patients are very different from those of healthy controls, being characterized not only by increased titres but also similar patterns of modified specificity, including a marked preference for conformational epitopes. Cross-competition experiments confirmed that the restricted specificity was clinically associated, appearing as an immunological signature, which allowed almost complete discrimination between patient groups. This phenomenon is a particularly promising diagnostic feature in this category of young patients where conventional tests usually only document the status of sensitization.
In general, allergenic foods are resistant to processes commonly used in food manufacturing. Nearly all the causative proteins (allergens) retain their allergenicity after treatment by heat and/or proteolysis. Notable exceptions exist; for example, the allergenicity of many fresh fruits and vegetables is decreased or removed by relatively mild processes such as gentle heating or mashing. The use of proteolytic enzymes to remove allergenicity is successfully used in the production of hypoallergenic infant formulas, but this approach with other allergenic foods has resulted in only limited success. Processing effects can result in decreased or complete removal of allergenic qualities of a food, such as the removal of proteins in oilseed processing, which renders the oils hypoallergenic and safe for consumption by allergic individuals. This discussion will address the different allergenic foods and processes which can affect or decrease their allergenicity.
Because of the widespread use of peanut products, peanut allergenicity is a major health concern in the United States. The effect or effects of thermal processing (roasting) on the allergenic properties of peanut proteins have rarely been addressed.
We sought to assess the biochemical effects of roasting on the allergenic properties of peanut proteins.
Competitive inhibition ELISA was used to compare the IgE-binding properties of roasted and raw peanut extracts. A well-characterized in vitro model was used to test whether the Maillard reaction contributes to the allergenic properties of peanut proteins. The allergic properties were measured by using ELISA, digestion by gastric secretions, and stability of the proteins to heat and degradation.
Here we report that roasted peanuts from two different sources bound IgE from patients with peanut allergy at approximately 90-fold higher levels than the raw peanuts from the same peanut cultivars. The purified major allergens Ara h 1 and Ara h 2 were subjected to the Maillard reaction in vitro and compared with corresponding unreacted samples for allergenic properties. Ara h 1 and Ara h 2 bound higher levels of IgE and were more resistant to heat and digestion by gastrointestinal enzymes once they had undergone the Maillard reaction.
The data presented here indicate that thermal processing may play an important role in enhancing the allergenic properties of peanuts and that the protein modifications made by the Maillard reaction contribute to this effect.
Fatal anaphylactic reactions to foods are continuing to occur, and better characterization might lead to better prevention. The objective of this report is to document the ongoing deaths and characterize these fatalities. We analyzed 32 fatal cases reported to a national registry, which was established by the American Academy of Allergy, Asthma, and Immunology, with the assistance of the Food Allergy and Anaphylaxis Network, and for which adequate data could be collected. Data were collected from multiple sources including a structured questionnaire, which was used to determine the cause of death and associated factors. The 32 individuals could be divided into 2 groups. Group 1 had sufficient data to identify peanut as the responsible food in 14 (67%) and tree nuts in 7 (33%) of cases. In group 2 subjects, 6 (55%) of the fatalities were probably due to peanut, 3 (27%) to tree nuts, and the other 2 cases were probably due to milk and fish (1 [9%] each). The sexes were equally affected; most victims were adolescents or young adults, and all but 1 subject were known to have food allergy before the fatal event. In those subjects for whom data were available, all but 1 was known to have asthma, and most of these individuals did not have epinephrine available at the time of their fatal reaction. Fatalities due to ingestion of allergenic foods in susceptible individuals remain a major health problem. In this series, peanuts and tree nuts accounted for more than 90% of the fatalities. Improved education of the profession, allergic individuals, and the public will be necessary to stop these tragedies.
Hypersensitivity to peanuts is a reaction mediated by IgE Abs in response to several peanut protein allergens. Among these allergenic proteins, Ara h 2 is one of the most commonly recognized allergens. Ara h 2 is a 17-kDa protein that has eight cysteine residues that could form up to four disulfide bonds. Circular dichroism studies showed substantial changes in the secondary and tertiary structures of the reduced Ara h 2 as compared with the native protein. Upon treatment with trypsin, chymotrypsin, or pepsin, a number of relatively large fragments are produced that are resistant to further enzymatic digestion. These resistant Ara h 2 peptide fragments contain intact IgE-binding epitopes and several potential enzyme cut sites that are protected from the enzymes by the compact structure of the protein. The enzyme-treated allergen remains essentially intact despite the action of proteases until the fragments are dissociated when the disulfide linkages are reduced. Amino acid sequence analysis of the resistant protein fragments indicates that they contain most of the immunodominant IgE-binding epitopes. These results provide a link between allergen structure and the immunodominant IgE-binding epitopes within a population of food-allergic individuals.
- S L Hefle
- J Nordlee
- Taylor S Allergenic
- Foods
Hefle SL, Nordlee J, Taylor S. Allergenic foods. Crit Rev Food Sci Nutr
1996;14:1269-73.
The effects of processing on the allergenic properties of peanut proteins
- S J Maleki
- S Y Chung
- E T Champagne
- J P Raufman
Maleki SJ, Chung SY, Champagne ET, Raufman JP. The effects of processing on the allergenic properties of peanut proteins. J Allergy Clin
Immunol 2000;106:763-76.
Protein structure plays a critical role in peanut allergen stability and may determine immunodominant IgE-binding epitopes
- Sen