Identification of pyruvate kinase as a novel allergen in whiteleg shrimp (Litopenaeus vannamei) by specific-IgE present in patients with shrimp allergy

Respiratory symptoms, sensitisation and occupational exposure in the shrimp processing industry

Introduction

Shellfish processing workers are highly susceptible to respiratory illnesses such as allergies and asthma. This study examined respiratory symptoms and biomarkers of allergy and asthma in Norwegian shrimp processing plant workers and evaluated allergenic and irritant protein exposures in the workplace.

Material and methods

The study included 35 shrimp processing workers and 21 controls. Respiratory symptoms were assessed via questionnaire; blood samples were analysed for allergy and asthma biomarkers and specific IgE levels. Air samples were analysed for protein levels and composition.

Results

Shrimp processing workers had four to five times higher odds of reporting acute upper and chronic lower respiratory symptoms than the controls. They also had significantly higher plasma levels of IL4, CCL20, CSF2 and MMP12, with 11% of the exposed workers showing elevated levels of shrimp and crab specific IgE. Furthermore, exposed workers showed increased plasma levels of SFTPD and CHI3L1 post-shift. The median total protein exposure was 6 µg/m3, with peaks up to 66 µg/m3 in the cooking and peeling department. Total protein levels were correlated with CCL20, IL13, and basophil counts. Ninety-five shrimp proteins were identified, including seven known and eight potential allergens. Tropomyosin levels were generally high, particularly in the cooking and peeling department.

Conclusion

Shrimp workers had a higher prevalence of respiratory symptoms and biomarkers of allergy and asthma. The work environment contained tropomyosin and other allergenic proteins as well as irritants, highlighting the need for protective measures, especially in the cooking and peeling departments.

Research Progress on Shrimp Allergens and Allergenicity Reduction Methods

Shrimp are highly favored by consumers for their delicious taste and rich nutritional value. However, reports of allergic reactions caused by shrimp and its derivatives have been increasing, significantly impacting consumer health and posing a growing global food safety concern. This article introduces the structure and biochemical characteristics of major allergenic proteins in shrimp, including tropomyosin (TM), arginine kinase, sarcoplasmic calcium-binding protein, myosin light chain, troponin C, and hemocyanin. Currently, there is no effective treatment for shrimp allergies, and prevention is mainly achieved by avoiding consumption. The study of shrimp allergen sensitization reduction technology is of great significance to the development of hypoallergenic or desensitized products. The article provides a detailed overview of the effects of common processing techniques, including physical, chemical, biological, and combined methods, on the allergenicity of shrimp allergens; for instance, the binding rate to immunoglobulin E (IgE) was reduced by 73.59% after treating TM with high pressure (500 MPa) at 55 °C for 10 min and the recognition rate of TM to IgE decreased by 89.4% on average after treating TM with pepsin (30 μg/mL, pH 2) for 2 h. These techniques provide references for the development of hypoallergenic aquatic products or desensitized foods.

Reducing the allergenicity of tropomyosin in shrimp by covalent conjugation with quercetin and chlorogenic acid

The study aimed to assay the allergenicity of shrimp tropomyosin (TM) following covalent conjugation with quercetin (QR) and chlorogenic acid (CA). The structure of the TM-polyphenol covalent conjugates was examined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), circular dichroism (CD), fluorescence, differential scanning calorimetry (DSC), and Fourier Transform infrared spectroscopy (FTIR). Potential allergenicity was evaluated using in vitro and in vivo methods. The results showed that QR and CA induced structural changes in TM through aggregation. RBL-2H3 cell results showed that TM-QR and TM-CA covalent conjugates reduced the release of β-hexosaminidase and histamine, respectively. In the mice model, TM-QR and TM-CA covalent conjugates reduced the level of IgE, IgG, IgG1, histamine, and mMCP-1 in sera. Furthermore, the allergenicity was reduced by suppressing Th2-related cytokines (IL-4, IL-5, IL-13) and promoting Th1-related cytokines (IFN-γ). These research findings demonstrate that the covalent binding of TM with QR and CA, modifies the allergenic epitopes of shrimp TM, thereby reducing its potential allergenicity. This approach holds practical applications in the production of low-allergenicity food within the food industry.

Genomics of Shrimp Allergens and Beyond

Allergy to shellfishes, including mollusks and crustaceans, is a growing health concern worldwide. Crustacean shellfish is one of the "Big Eight" allergens designated by the U.S. Food and Drug Administration and is the major cause of food-induced anaphylaxis. Shrimp is one of the most consumed crustaceans triggering immunoglobulin E (IgE)-mediated allergic reactions. Over the past decades, the allergen repertoire of shrimp has been unveiled based on conventional immunodetection methods. With the availability of genomic data for penaeid shrimp and other technological advancements like transcriptomic approaches, new shrimp allergens have been identified and directed new insights into their expression levels, cross-reactivity, and functional impact. In this review paper, we summarize the current knowledge on shrimp allergens, as well as allergens from other crustaceans and mollusks. Specific emphasis is put on the genomic information of the shrimp allergens, their protein characteristics, and cross-reactivity among shrimp and other organisms.

Gut Microbiome Proteomics in Food Allergies

Food allergies (FA) have dramatically increased in recent years, particularly in developed countries. It is currently well-established that food tolerance requires the strict maintenance of a specific microbial consortium in the gastrointestinal (GI) tract microbiome as alterations in the gut microbiota can lead to dysbiosis, causing inflammation and pathogenic intestinal conditions that result in the development of FA. Although there is currently not enough knowledge to fully understand how the interactions between gut microbiota, host responses and the environment cause food allergies, recent advances in '-omics' technologies (i.e., proteomics, genomics, metabolomics) and in approaches involving systems biology suggest future headways that would finally allow the scientific understanding of the relationship between gut microbiome and FA. This review summarizes the current knowledge in the field of FA and insights into the future advances that will be achieved by applying proteomic techniques to study the GI tract microbiome in the field of FA and their medical treatment. Metaproteomics, a proteomics experimental approach of great interest in the study of GI tract microbiota, aims to analyze and identify all the proteins in complex environmental microbial communities; with shotgun proteomics, which uses liquid chromatography (LC) for separation and tandem mass spectrometry (MS/MS) for analysis, as it is the most promising technique in this field.

Crustacean shellfish allergens: influence of food processing and their detection strategies

Despite the increasing popularity of crustacean shellfish among consumers due to their rich nutrients, they can induce a serious allergic response, sometimes even life-threatening. In the past decades, a variety of crustacean allergens have been identified to facilitate the diagnosis and management of crustacean allergies. Although food processing techniques can ease the risk of crustacean shellfish allergy, no available processing methods to tackle crustacean allergies thoroughly. Strict dietary avoidance of crustacean shellfish and its component is the best option for the protection of sensitized individuals, which should rely on the compliance of food labeling and, as such, on their verification by sensitive, reliable, and accurate detection techniques. In this present review, the physiochemical properties, structure aspects, and immunological characteristics of the major crustacean allergens have been described and discussed. Subsequently, the current research progresses on how various processing techniques cause the alterations and modifications in crustacean allergens to produce hypoallergenic crustacean food products were summarized and discussed. Particularly, various analytical methodologies employed in crustacean shellfish allergen detection, and the effect of food processing and matrix on these techniques, are also herein emphasized for the appropriate selection of analytical detection tools to safeguard consumers safety.

A spotlight on analytical prospects in food allergens: From emerging allergens and novel foods to bioplastics and plant-based sustainable food contact materials

The present review throws a spotlight on new and emerging food safety concerns in view of a well-established food allergen risk arising from global socio-economic changes, international trade, circular economy, environmental sustainability, and upcycling. Food culture globalization needs harmonization of regulations, technical specifications, and reference materials towards mutually recognised results. In parallel, routine laboratories require high-throughput reliable analytical strategies, even in-situ testing devices, to test both food products and food contact surfaces for residual allergens. Finally, the currently neglected safety issues associated to possible allergen exposure due to the newly proposed bio- and plant-based sustainable food contact materials require an in-depth investigation.

MALDI-TOF MS and Magnetic Beads for Rapid Seafood Allergen Tests

We developed a strategy using immunomagnetic separation (IMS) coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to test seafood allergens. The protocol employed commercial magnetic beads (MBs) functionalized with anti-human IgE antibodies to carry out the IMS of IgEs in blood samples, followed by capture of allergens from seafood protein extracts for allergy analysis. After elution, the captured allergens were identified by MALDI-TOF MS and HPLC-MS/MS. The non-specific adsorption of MBs to biomolecules, the reproducibility and sensitivity of the protocol were investigated. The method shows consistent results with enzyme-linked immunosorbent assay tests. The false positive rate of the present method for the allergy test is 0%. The protocol was applied to detect the allergens in greasy-back shrimp for checking the allergenicity of patients' serum. Cooking fish as soup may effectively decrease the allergenicity. The method can be potentially used to identify unknown allergens of seafood to ensure the safety of allergic patients.

Molecular Basis of IgE-Mediated Shrimp Allergy and Heat Desensitization

Crustacean allergy, especially to shrimp, is the most predominant cause of seafood allergy. However, due to the high flexibility of immunoglobulin E (IgE), its three-dimensional structure remains unsolved, and the molecular mechanism of shrimp allergen recognition is unknown. Here a chimeric IgE was built in silico, and its variable region in the light chain was replaced with sequences derived from shrimp tropomyosin (TM)-allergic patients. A variety of allergenic peptides from the Chinese shrimp TM were built, treated with heating, and subjected to IgE binding in silico. Amino acid analysis shows that the amino acid residue conservation in shrimp TM contributes to eliciting an IgE-mediated immune response. In the shrimp-allergic IgE, Glu98 in the light chain and other critical residues that recognize allergens from shrimp are implicated in the molecular basis of IgE-mediated shrimp allergy. Heat treatment could alter the conformations of TM allergenic peptides, impact their intramolecular hydrogen bonding, and subsequently decrease the binding between these peptides and IgE. We found Glu98 as the characteristic amino acid residue in the light chain of IgE to recognize general shrimp-allergic sequences, and heat-induced conformational change generally desensitizes shrimp allergens.

Characterization and epitope prediction of phosphopyruvate hydratase from Penaeus monodon (black tiger shrimp)

Shellfish allergies constitute an important cause of food-induced anaphylactic reactions, which pose challenges to food safety and human health worldwide. In the present study, the specific IgE (sIgE) binding characteristics of different shrimp proteins of black tiger shrimp (Penaeus monodon) to the sera of eight shrimp-allergic patients from China were studied by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and nanoliquid chromatography time-of-flight mass spectrometry. According to the PLGS scores (>2000) and the sequence coverage (>40%), eight proteins with sIgE binding activity were identified, including myosin heavy chain type 1 (K4Q4N8), hemocyanin (G1AP69 and Q95V28), phosphopyruvate hydratase (O96656), arginine kinase (C7E3T4), tropomyosin (A1KYZ2), sarcoplasmic calcium binding protein (H7CHW2) and glyceraldehyde-3-phosphate dehydrogenase (A0A097BQP2). Among these eight proteins, phosphopyruvate hydratase was a prevalent IgE-binding protein among these Chinese patients with binding observed in 100% of sera. Moreover, 13 peptides were predicted as epitopes of phosphopyruvate hydratase. These new details help us to understand the crustacean IgE-binding proteins especially Penaeus monodon IgE-binding proteins, that would cause allergic reaction to Chinese patients. And our findings may provide essential information to improve allergy prevention and clinical treatment to shrimp allergy in China. PRACTICAL APPLICATION: This research may have diagnostic and therapeutic value for shrimp allergies in China.

Current Trends in Proteomic Advances for Food Allergen Analysis

Food allergies are a global food challenge. For correct food labelling, the detection and quantification of allergens are necessary. However, novel product formulations and industrial processes produce new scenarios, which require much more technological developments. For this purpose, OMICS technologies, especially proteomics, seemed to be relevant in this context. This review summarises the current knowledge and studies that used proteomics to study food allergens. In the case of the allergenic proteins, a wide variety of isoforms, post-translational modifications and other structural changes during food processing can increase or decrease the allergenicity. Most of the plant-based food allergens are proteins with biological functions involved in storage, structure, and plant defence. The allergenicity of these proteins could be increased by the presence of heavy metals, air pollution, and pesticides. Targeted proteomics like selected/multiple reaction monitoring (SRM/MRM) have been very useful, especially in the case of gluten from wheat, rye and barley, and allergens from lentil, soy, and fruit. Conventional 1D and 2-DE immunoblotting have been further widely used. For animal-based food allergens, the widely used technologies are 1D and 2-DE immunoblotting followed by MALDI-TOF/TOF, and more recently LC-MS/MS, which is becoming useful to assess egg, fish, or milk allergens. The detection and quantification of allergenic proteins using mass spectrometry-based proteomics are promising and would contribute to greater accuracy, therefore improving consumer information.

Proteomics-Based Methodologies for the Detection and Quantification of Seafood Allergens

Seafood is considered one of the main food allergen sources by the European Food Safety Authority (EFSA). It comprises several distinct groups of edible aquatic animals, including fish and shellfish, such as crustacean and mollusks. Recently, the EFSA recognized the high risk of food allergy over the world and established the necessity of developing new methodologies for its control. Consequently, accurate, sensitive, and fast detection methods for seafood allergy control and detection in food products are highly recommended. In this work, we present a comprehensive review of the applications of the proteomics methodologies for the detection and quantification of seafood allergens. For this purpose, two consecutive proteomics strategies (discovery and targeted proteomics) that are applied to the study and control of seafood allergies are reviewed in detail. In addition, future directions and new perspectives are also provided.

Impact of microwave processing on the secondary structure, in-vitro protein digestibility and allergenicity of shrimp (Litopenaeus vannamei) proteins

This study aimed to evaluate the effects of microwave processing (2.45 GHz, 1000 W, 75-125 °C, and 5-15 min) on the secondary structures, in-vitro protein digestibility, microstructural characteristics, and allergenicity of shrimp. SDS-PAGE analysis showed that the band intensity of tropomyosin reduced with the increase of processing temperatures and durations. The significant reduction in the allergenicity of tropomyosin was up to 75% when treated with microwave at 125 °C for 15 min. A significant reduction by 30-75% in the total soluble protein content, peptide content, and in-vitro protein digestibility of shrimp protein was observed. These changes mentioned above were strongly associated with the modification of the secondary structure of shrimp proteins, including the increase in β-sheets, and the loss in turns. Also, more microscopic holes, fragments, strips in treated samples were observed by scanning electron microscopy. Therefore, high-intensity microwave treatment showed great potential in reducing the allergenicity of shrimp.

Review of New Trends in the Analysis of Allergenic Residues in Foods and Cosmetic Products

BACKGROUND

Allergies represent an important health problem in industrialized countries. Allergen sensitization is an important risk factor for the development of allergic diseases; thus, the identification of an individual's allergen sensitization is essential for the diagnosis and treatment of diseases.

OBJECTIVE

This review compares different modern methods applied for the analysis of allergens in various matrices (from 2015 to the end of September 2019).

CONCLUSIONS

Immunological methods are still most frequently used for detection of allergens. These methods are sensitive, but the lack of specificity and cross-reaction of some antibodies can still be a relevant source of errors. DNA-based methods are fast and reliable for determination of protein allergens, but the epitopes of protein allergens with posttranslational modifications and their changes, originated during various processing, cannot be identified through the use of this method. Methods based on application of biosensors are very rapid and easy to use, and can be readily implemented as screening methods to monitor allergens. Recent developments of new high-resolution MS instruments are encouraging and enable development in the analysis of allergens. Fast, very sensitive, reliable, and accurate detection and quantification of allergens in complex samples can be used in the near future. Mass spectrometry coupled with LC, GC, or electrophoretic methods bring additional advances in allergen analysis. The use of LC-MS or LC-MS/MS for the quantitative detection of allergens in various matrices is at present gaining acceptance as a protein-based confirmatory technique over the routinely performed enzyme-linked immunosorbent assays.

The nuts and bolts of omics for the clinical allergist

OBJECTIVE

Omics, aka multi-omics, is an emerging area of research that is advancing the use of personalized medicine in clinical practice and is therefore relevant for the practicing allergist.

DATA SOURCES

We performed a literature search of a selection of scientific findings in omics and allergy, including variants that may be important to allergy outcomes in the genome, transcriptome, metabolome, microbiome, epigenome, and exposome, among others.

STUDY SELECTIONS

Basic science papers and review articles.

RESULTS

The use of multi-omic data in clinical practice is changing how clinicians treat their patients whereby more personalized approaches are becoming standard in medical practice and has the potential to transform the treatment of allergies.

CONCLUSION

Multi-omic data are relevant and will become increasingly important for the clinical allergist.

Identification of pyruvate kinase 2 as a possible crab allergen and analysis of allergenic proteins in crabs consumed in Taiwan

In Taiwan, crab is one of the main causes for food allergy. Several proteins are recognized as crustacean allergens, and tropomyosin is known to be the major one. However, sensitization patterns of Taiwanese patients to crustacean allergens remain unclear. Therefore, we analyzed the specific-IgE binding ability of crucifix crab (Charybdis feriatus) allergens by western blot using patients' sera. In particular, we found a 56 kDa protein in crucifix crab reacted with specific-IgEs in patients' sera, and we further identified the protein as a novel crab allergen pyruvate kinase 2. Additionally, little is known about tropomyosin contents in crabs consumed in Taiwan. Thus, we also quantified the levels of tropomyosin by using enzyme-linked immunosorbent assay (ELISA) among raw and cooked crab species. Our results showed tropomyosin levels varied depending on crab species. In summary, these findings improve the understanding of crustacean allergens and contribute to the clinical diagnosis of crustacean allergies.

The transcriptome sequencing and functional analysis of eyestalk ganglions in Chinese mitten crab (Eriocheir sinensis) treated with different photoperiods

Photoperiod plays an important role in individual growth, development, and metabolism in crustaceans. The growth and reproduction of crabs are closely related to the photoperiod. However, as of yet, there are still no transcriptomic reports of eyestalk ganglions treated under different photoperiods in the Chinese mitten crab (Eriocheir sinensis), which is a benthonic crab with high commercial value in Asia. In this study, we collected the eyestalk ganglions of crabs that were reared under different photoperiods, including a control group (L: D = 12 h: 12 h, named CC), a constant light group (L: D = 24 h: 0 h, named LL) and a constant darkness group (L: D = 0 h: 24 h, named DD). RNA sequencing was performed on these tissues in order to examine the effects of different photoperiods. The total numbers of clean reads from the CC, LL and DD groups were 48,772,584 bp, 53,943,281 bp and 53,815,178 bp, respectively. After de novo assembly, 161,380 unigenes were obtained and were matched with different databases. The DEGs were significantly enriched in phototransduction and energy metabolism pathways. Results from RT-qPCR showed that TRP channel protein (TRP) in the phototransduction pathway had a significantly higher level of expression in LL and DD groups than in the CC group. We found that the downregulation of the pyruvate dehydrogenase complex (PDC) gene and the upregulation phosphoenolpyruvate carboxykinase (PPC) gene were involved in energy metabolism processes in LL or DD. In addition, we also found that the upregulation of the expression level of the genes Gαq, pyruvate kinase (PK), NADH peroxidase (NADH) and ATPase is involved in phototransduction and energy metabolism. These results may shed some light on the molecular mechanism underlying the effect of photoperiod in physiological activity of E. sinensis.

Serum IgE cross-reactivity between fish and chicken meats in dogs

BACKGROUND

In humans, a cross-reactive clinical allergy has been reported between three chicken and fish meat proteins: beta-enolase, aldolase A and parvalbumin.

OBJECTIVE

To evaluate if IgE cross-reactivity between chicken and fish also existed in the dog.

ANIMALS

Sera from dogs with suspected allergic skin disease and with IgE against chicken and fish.

METHODS AND MATERIALS

Sera were analysed by ELISA and immunoblotting with chicken, white fish (haddock and cod) and salmon extracts. Reciprocal inhibition ELISAs and inhibition immunoblots were then performed. Protein sequencing of bands identified on multiple extracts was determined by mass spectrometry.

RESULTS

Out of 53 archived canine sera tested by ELISA against chicken, white fish or salmon, 15 (28%), 12 (23%) and 26 (49%), respectively, had elevated IgE against one, two or all three of these extracts. Seven of the triple-reactive sera were subjected to reciprocal inhibition ELISAs. A >50% inhibition was found between chicken-fish, chicken-salmon and fish-salmon in seven, four and five of seven dogs, respectively. Immunoblotting identified multiple IgE-binding proteins of identical molecular weights in the three extracts; these were partially to fully cross-reactive by inhibition immunoblotting. Mass spectrometry identified nine cross-reactive proteins as: pyruvate kinase, creatine kinase, alpha-actin, glyceraldehyde-3-phosphate dehydrogenase, beta-enolase, aldolase, malate dehydrogenase, lactate dehydrogenase and triose-phosphate isomerase 1. All of these have been reported previously as fish, shellfish and/or chicken allergens for humans.

CONCLUSIONS AND CLINICAL IMPORTANCE

Whether any of these newly identified IgE cross-reactive chicken-fish allergens is the cause of clinical allergy needs to be determined in dogs reacting to at least two of these common food sources.