Potential allergenicity of Medicago sativa investigated by a combined IgE-binding inhibition, proteomics and in silico approach

Update on hazelnut allergy: Allergen characterization, epidemiology, food processing technique and detecting strategy

Hazelnuts are popular among people due to their dense nutrient component. However, eating them may be quite dangerous for those who are allergic. To improve food safety, this research examines current developments in the characterization, processing, and detection of hazelnut allergens. The identification and molecular knowledge of certain proteins that cause allergic responses are necessary for the characterization of hazelnut allergens. Proteomics and genomics are two techniques that have helped to advance our knowledge of hazelnut allergens and facilitate the creation of more precise diagnostic instruments. One important factor to reduce but not to eliminate the exposure to hazelnut allergens is food processing. The extractability of hazelnut proteins with regard to food processing plays a crucial role in determining allergenicity. Innovative technologies have been created to lessen allergenicity in foods containing hazelnuts while preserving their flavor and quality. These technologies include thermal and nonthermal processing techniques. To further safeguard consumers with hazelnut allergies, innovations in ingredient labeling and cross-contamination avoidance techniques have been put into place. For the purpose of management, if foods contain hazelnut, they must label it. Technological developments in analytical methods, including mass spectrometry, polymerase chain reaction, and enzyme-linked immunosorbent assays, have made it possible to identify hazelnut allergens with high specificity and sensitivity in a range of dietary matrices. Moreover, the advancement of point-of-care testing instruments presents the possibility of prompt on site identification, hence enhancing food safety for people with hazelnut allergies. The multidisciplinary efforts of researchers, food technologists, and allergists to enhance the safety of products containing hazelnuts are highlighted in this study.

Synergy of Analytical Characterization and Biocompatible Extractions for the Enhancement of High-Quality Biorefinery Products from Medicago sativa

This study presents the development of an analytical characterization strategy tailored to end products derived from an alfalfa (Medicago sativa)-based biorefinery with particular emphasis on protein concentrates and phenolic-enriched fractions. Our approach began with a comprehensive full-factorial experimental design aimed at optimizing the extraction process, taking care to design a biocompatible extraction protocol. Liquid chromatography with tandem mass spectrometry (LC-MS/MS) techniques were used to characterize the molecular profile of the extracts. In particular, the extracts showed a significant relative abundance of flavonoids and isoflavonoids in both their aglycone and glycosylated forms, in which antioxidant activity was evaluated. In addition, we elucidated the proteomic profiles of the protein concentrates. This proteomic characterization served as a valuable resource for understanding the differences between these end products, providing insights that can guide informed decisions about their potential applications.

A review of the toxicological effects and allergenic potential of emerging alternative protein sources

The growing environmental pressure of the animal food chain requires a system shift toward more sustainable diets based on alternative protein sources. Emerging alternative protein sources, such as faba bean, mung bean, lentil, black gram, cowpea, quinoa, hemp, leaf proteins, microalgae, and duckweeds, are being explored for their potential in meeting global protein demand and were, therefore, the subject of this review. This systematic literature review aims to understand the current knowledge on the toxicological effects and allergenic potential associated with these sources and derived protein and food products. The findings identified potential concerns associated with the presence of plant secondary metabolites, including antinutritional factors, phytoestrogens, and oligosaccharides, in all the sources included. Also, these protein sources have been shown to display allergenic properties, either through the intrinsic presence of allergens or through cross-reaction. Further, the effects of food processing on these proteins remain poorly understood and no conclusive data are available to quantitatively assess their safety after processing. Overall, those findings highlight the need for quantitative knowledge of the food safety attributes related to final food products. This will enable a concrete and preventive approach to food safety in the protein transition.

A systematic review of allergen cross-reactivity: Translating basic concepts into clinical relevance

Access to the molecular culprits of allergic reactions allows for the leveraging of molecular allergology as a new precision medicine approach-one built on interdisciplinary, basic, and clinical knowledge. Molecular allergology relies on the use of allergen molecules as in vitro tools for the diagnosis and management of allergic patients. It complements the conventional approach based on skin and in vitro allergen extract testing. Major applications of molecular allergology comprise accurate identification of the offending allergen thanks to discrimination between genuine sensitization and allergen cross-reactivity, evaluation of potential severity, patient-tailored choice of the adequate allergen immunotherapy, and prediction of its expected efficacy and safety. Allergen cross-reactivity, defined as the recognition of 2 or more allergen molecules by antibodies or T cells of the same specificity, frequently interferes with allergen extract testing. At the mechanistic level, allergen cross-reactivity depends on the allergen, the host's immune response, and the context of their interaction. The multiplicity of allergen molecules and families adds further difficulty. Understanding allergen cross-reactivity at the immunologic level and translating it into a daily tool for the management of allergic patients is further complicated by the ever-increasing number of characterized allergenic molecules, the lack of dedicated resources, and the need for a personalized, patient-centered approach. Conversely, knowledge sharing paves the way for improved clinical use, innovative diagnostic tools, and further interdisciplinary research. Here, we aimed to provide a comprehensive and unbiased state-of-the art systematic review on allergen cross-reactivity. To optimize learning, we enhanced the review with basic, translational, and clinical definitions, clinical vignettes, and an overview of online allergen databases.

Advanced Proteomic and Bioinformatic Tools for Predictive Analysis of Allergens in Novel Foods

In recent years, novel food is becoming an emerging trend increasingly more demanding in developed countries. Food proteins from vegetables (pulses, legumes, cereals), fungi, bacteria and insects are being researched to introduce them in meat alternatives, beverages, baked products and others. One of the most complex challenges for introducing novel foods on the market is to ensure food safety. New alimentary scenarios drive the detection of novel allergens that need to be identified and quantified with the aim of appropriate labelling. Allergenic reactions are mostly caused by proteins of great abundance in foods, most frequently of small molecular mass, glycosylated, water-soluble and with high stability to proteolysis. The most relevant plant and animal food allergens, such as lipid transfer proteins, profilins, seed storage proteins, lactoglobulins, caseins, tropomyosins and parvalbumins from fruits, vegetables, nuts, milk, eggs, shellfish and fish, have been investigated. New methods for massive screening in search of potential allergens must be developed, particularly concerning protein databases and other online tools. Moreover, several bioinformatic tools based on sequence alignment, motif identification or 3-D structure predictions should be implemented as well. Finally, targeted proteomics will become a powerful technology for the quantification of these hazardous proteins. The ultimate objective is to build an effective and resilient surveillance network with this cutting-edge technology.

Is now the time for a Rubiscuit or Ruburger? Increased interest in Rubisco as a food protein

Much of the research on Rubisco aims at increasing crop yields, with the ultimate aim of increasing plant production to feed an increasing global population. However, since the identification of Rubisco as the most abundant protein in leaf material, it has also been touted as a direct source of dietary protein. The nutritional and functional properties of Rubisco are on a par with those of many animal proteins, and are superior to those of many other plant proteins. Purified Rubisco isolates are easily digestible, nutritionally complete, and have excellent foaming, gelling, and emulsifying properties. Despite this potential, challenges in efficiently extracting and separating Rubisco have limited its use as a global foodstuff. Leaves are lower in protein than seeds, requiring large amounts of biomass to be processed. This material normally needs to be processed quickly to avoid degradation of the final product. Extraction of Rubisco from the plant material requires breaking down the cell walls and rupturing the chloroplast. In order to obtain high-quality protein, Rubisco needs to be separated from chlorophyll, and then concentrated for final use. However, with increased consumer demand for plant protein, there is increased interest in the potential of leaf protein, and many commercial plants are now being established aimed at producing Rubisco as a food protein, with over US$60 million of funding invested in the past 5 years. Is now the time for increased use of Rubisco in food production as a nitrogen source, rather than just providing a carbon source?

Scale-Up of Alfalfa (Medicago sativa) Protein Recovery Using Screw Presses

As a consequence of the increased demand for proteins for both feed and food, alternative protein sources from green plants such as alfalfa (Medicago sativa) have come into focus, together with methods to recover these proteins. In this study, we have investigated the use of screw presses for protein recovery from alfalfa at laboratory and pilot scale. We found that using a pilot scale screw press, with a working pressure of 6 bar, 16% of the total protein was recovered in one pressing, and that after rehydrating and repressing the alfalfa up to ten times, 48% of the total protein could be recovered. The green alfalfa protein concentrate was analyzed for total protein, amino acid profile, protein digestibility, color, ash, fiber and fat content. It was found that repetitive pressings lowered the digestibility of the protein pool and reduced the total protein concentration due to dilution. To achieve the best quality protein at the highest concentrations, it is recommended to press the alfalfa no more than twice, which results in an alfalfa protein concentrate with more than 32% soluble protein and greater than 82% digestibility.

Experimental Research Models to Assess the Cross-Reactivity between Can f 5 and Human PSA—Two Different Perspectives

The similarity in antigenic structures, including the degree of correspondence between the amino acid sequence and the spatial structure, is not always reflected in the actual cross-reactivity of allergens. Inhibition tests appear to be an invaluable tool for assessing potential cross-reactivity between allergens under natural conditions. In this publication, we present two experimental models of inhibition tests: solid phase (SP-IT) and liquid phase (LP-IT). As an exemplary research model, we used the cross-reactivity between human PSA and anti-Can f 5 IgE antibodies. We performed an SP-IT model using a microplate coated with human PSA. The LP-IT model was based on mixing anti-Can f 5 IgE positive serum with a material containing human PSA. Anti-Can f 5 IgE and PSA concentrations before and after inhibition were measured to evaluate inhibition effectiveness. The results of the performed experiments showed that both proposed models of inhibition tests are an effective tools for studying cross-reactive relationships between antigens. In the SP-IT, the concentration of anti-Can f 5 decreased by 21.6% and, in the LP-IT, it decreased by 34.51%. In turn, the PSA concentration in the SP-IT decreased by 11.25% and, in the LP-IT, it decreased by 15.49%. In conclusion, both the SP-IT and the LP-IT seem to be effective tools for assessing the actual cross-reactivity between different allergens.

Tomato (Solanum lycopersicum L.) accumulation and allergenicity in response to nickel stress

Vegetables represent a major source of Ni exposure. Environmental contamination and cultural practices can increase Ni amount in tomato posing significant risk for human health. This work assesses the tomato (Solanum lycopersicum L.) response to Ni on the agronomic yield of fruits and the related production of allergens. Two cultivars were grown in pots amended with Ni 0, 30, 60, 120, and 300 mg kg⁻¹, respectively. XRF and ICP-MS analyses highlighted the direct increase of fruit Ni content compared to soil Ni, maintaining a stable biomass. Leaf water content increased at Ni 300 mg kg⁻¹. Total protein content and individual allergenic components were investigated using biochemical (RP-HPLC and N-terminal amino acid sequencing) and immunological (inhibition tests of IgE binding by SPHIAa assay on the FABER testing system) methodologies. Ni affected the fruit tissue concentration of pathogenesis-related proteins and relevant allergens (LTP, profilin, Bet v 1-like protein and TLP). This study elucidates for the first time that tomato reacts to exogenous Ni, uptaking the metal while changing its allergenic profiles, with potential double increasing of exposure risks for consumers. This evidence highlighted the importance of adequate choice of low-Ni tomato cultivars and practices to reduce Ni uptake by potentially contaminated matrices.

Detection of Allergenic Proteins in Foodstuffs: Advantages of the Innovative Multiplex Allergen Microarray-Based Immunoassay Compared to Conventional Methods

Several factors can affect the allergen content and profile of a specific food, including processing procedures often leading to a decrease in allergenicity, although no change, or even an increase, have also been reported. Evaluation of the effectiveness of a processing procedure requires the availability of reliable methodologies to assess the variation in molecules able to induce allergic reactions in the analyzed food. Conventional and innovative strategies and methodologies can be exploited to identify allergenic proteins in foodstuffs. However, depending on the specific purposes, different methods can be used. In this review, we have critically reviewed the advantages of an innovative method, the multiplex allergen microarray-based immunoassay, in the detection of allergens in foodstuffs. In particular, we have analyzed some studies reporting the exploitation of an IgE-binding inhibition assay on multiplex allergen biochips, which has not yet been reviewed in the available literature. Unlike the others, this methodology enables the identification of many allergenic proteins, some of which are still unknown, which are recognized by IgE from allergic patients, with a single test. The examined literature suggests that the inhibition test associated with the multiplex allergen immunoassay is a promising methodology exploitable for the detection of IgE-binding proteins in food samples.

Crosstalk Between the Immune System and Plant-Derived Nanovesicles: A Study of Allergen Transporting

Background: Nanometer-sized membrane-surrounded vesicles from different parts of plants including fruits are gaining increasing attention due to their anti-inflammatory and anticancer effects demonstrated by in vitro and in vivo studies, and as nanovectors for molecular delivery of exogenous substances. These nanomaterials are very complex and contain a diverse arsenal of bioactive molecules, such as nucleic acids, proteins, and lipids. Our knowledge about the transport of allergens in vesicles isolated from plant food is limited today. Methods: Here, to investigate the allergenicity of strawberry-derived microvesicles (MVs), nanovesicles (NVs), and subpopulations of NV, we have set up a multidisciplinary approach. The strategy combines proteomics-based protein identification, immunological investigations, bioinformatics, and data mining to gain biological insights useful to evaluate the presence of potential allergens and the immunoglobulin E (IgE) inhibitory activity of vesicle preparations. Results: Immunological test showed that several proteins of strawberry-derived vesicles compete for IgE binding with allergens spotted on the FABER biochip. This includes the known strawberry allergens Fra a 1, Fra a 3, and Fra a 4, and also other IgE-binding proteins not yet described as allergens in this food, such as gibberellin-regulated proteins, 2S albumin, pectate lyase, and trypsin inhibitors. Proteomics identified homologous sequences of the three strawberry allergens and their isoforms in total protein extract (TPE) but only Fra a 1 and Fra a 4 in the vesicle samples. Label-free quantitative proteomic analysis revealed no significant enrichment of these proteins in strawberry vesicles with respect to TPE. Conclusion: Immunological tests and bioinformatics analysis of proteomics data sets revealed that MVs and NVs isolated from strawberries can carry functional allergens their isoforms as well as proteins potentially allergenic based on their structural features. This should be considered when these new nanomaterials are used for human nutraceutical or biomedical applications.