Tropomyosin (TM) is the main allergen in shrimp (Litopenaeus vannamei). In this study, the effects of allergenicity and structure of TM by glycosylation (GOS-TM), phosphate treatment (SP-TM), and glycosylation combined with phosphate treatment (GOS-SP-TM) were investigated. Compared to GOS-TM and SP-TM, the IgG/IgE binding capacity of GOS-SP-TM was significantly decreased with 63.9 ± 2.0 and 49.7 ± 2.7%, respectively. Meanwhile, the α-helix content reduced, surface hydrophobicity increased, and 10 specific amino acids (K30, K38, S39, K48, K66, K74, K128, K161, S210, and K251) were modified by glycosylation on six IgE linear epitopes of GOS-SP-TM. In the BALB/c mice allergy model, GOS-SP-TM could significantly reduce the levels of specific IgE, IgG1, and CD4+IL-4+, while the levels of IgG2a, CD4+CD25+Foxp3+, and CD4+IFN-γ+ were increased, which equilibrated Th1 and Th2 cells, thus alleviating allergic symptoms. These results indicated that glycosylation combined with phosphate treatment can provide a new insight into developing hypoallergenic shrimp food.

Scy p 8 (triosephosphate isomerase) as a crab allergen in inducing distinct T-helper (Th) cell differentiation and a linear epitope associated with allergenicity remain elusive. In this study, mice sensitized with Scy p 8 exhibited significantly upregulated levels of IgE, IgG1, and IL-4 release, inducing a Th2 immune response. Moreover, the release of IFN-γ (Th1) and the levels of Treg cells were downregulated, while IL-17A (Th17) was upregulated, indicating that Scy p 8 disrupted the Th1/Th2 balance and Th17/Treg balance in mice. Furthermore, bioinformatics prediction and serum samples from crab-allergic patients and mice enabled the discovery of 8 linear epitopes of Scy p 8. Meanwhile, the analysis of peptide similarity and tertiary superposition revealed that 8 epitopes of Scy p 8 exhibited conservation across various species, potentially resulting in cross-reactivity. These findings possess the potential to enhance the comprehension of crab allergens, thereby establishing a foundation for investigating cross-reactivity.

Tropomyosin has been identified as the major cross-reactive shellfish allergen, but recent studies showed the presence of other clinically relevant allergens. This study aims at determining the allergic immune responses of mice sensitized with raw and boiled shrimp extracts in comparison to recombinant tropomyosin (rTM). Female Balb/c mice were intragastrically sensitized and challenged with raw, boiled shrimp or rTM. Systemic, cellular and humoral allergic responses were compared, while allergenicity of the extracts was also compared by skin prick test (SPT) and immunoblot on shrimp allergic subjects. We showed that rTM and shrimp extracts induced IgE- and Th2-mediated allergic responses in mice, distinguished by remarkable intestinal inflammation in small intestine across all regimens. Notably, boiled shrimp extract exhibited the highest sensitization rate (73.7% of mice developed positive TM-specific IgE response) when compared with raw extract (47.8%) and rTM (34.8%). Mice sensitized with boiled extract manifested the highest allergen-specific IgE and Th2 cytokine responses than the others. Immunoblot results indicated that tropomyosin remained the major allergen in extract-based sensitization and had stronger allergenicity in a heat-treated form comparing to untreated TM, which was in line with the SPT results that boiled extract induced larger wheal size in patients. Hemocyanin and glycogen phosphorylase were also identified as minor allergens associated with manifestation of shrimp allergy. This study shows that boiled extract enhanced sensitization and Th2 responses in agreement with the higher allergenicity of heat-treated TM. This study thus presents three shrimp allergy murine models suitable for mechanistic and intervention studies, and in vivo evidence implies higher effectiveness of boiled extract for the clinical diagnosis of shellfish allergy.

Crustacean shellfish are major allergens in East Asia. In the present study, a major allergic protein in crustaceans, tropomyosin, was detected accurately using multiple reaction monitoring mode-based mass spectrometry, with shared signature peptides identified through proteomic analysis. The peptides were deliberately screened through thermal stability and enzymatic digestion efficiency to improve the suitability and accuracy of the developed method. Finally, the proposed method demonstrated a linear range of 0.15 to 30 mgTM/kgfood (R2 > 0.99), with a limit of detection of 0.15 mgTM/kg food and a limit of quantification of 0.5mgTM/kgfood and successfully applied to commercially processed foods, such as potato chips, biscuits, surimi, and hot pot seasonings, which evidenced the applicability of proteomics-based methodology for food allergen analysis.

Due to the widespread use of shellfish ingredients in food products, accurate food labelling is urgently needed for consumers with shellfish allergies. Most crustacean allergen detection systems target the immunorecognition of the allergenic protein tropomyosin. However, this mode of detection may be affected by an origin-dependent protein composition. This study determined if the geographic location of capture, or aquaculture, influenced the allergenic protein profiles of Black Tiger Shrimp (Penaeus monodon), one of the most farmed and consumed shrimp species worldwide. Protein composition was analysed in shrimp from nine different locations in the Asia-Pacific by SDS-PAGE, immunoblotting, and mass spectrometry. Ten of the twelve known shrimp allergens were detected, but with considerable differences between locations. Sarcoplasmic calcium-binding protein, myosin light chain, and tropomyosin were the most abundant allergens in all locations. Hemocyanin-specific antibodies could identify up to six different isoforms, depending on the location of origin. Similarly, tropomyosin abundance varied by up to 13 times between locations. These findings suggest that allergen abundance may be related to shrimp origin and, thus, shrimp origin might directly impact the readout of commercial crustacean allergen detection kits, most of which target tropomyosin, and this should be considered in food safety assessments.

BACKGROUND: Observational studies have implied a potential correlation between allergic diseases and major depressive disorder (MDD). However, the relationship is still inconclusive as it is likely to be interfered with by substantial confounding factors and potential reverse causality. The present study aimed to investigate causal correlation of the two diseases by a Mendelian randomization (MR) study and further elucidate the underlying molecular mechanisms.
METHODS: With the biggest summary datasets of a genome-wide association study (GWAS) in the East Asian population, we conducted a two-sample, bidirectional MR study to assess the causal correlation between shrimp allergy (SA) and MDD. Subsequently, we identified the pleiotropic genes\' susceptibility to the two diseases at whole-genome and tissue-specific levels, respectively. Enriched GO sets and KEGG pathways were also discovered to elucidate the potential underlying mechanisms.
RESULTS: With the most suitable MR method, SA was identified as a causal risk factor for MDD based on three different groups of independent genetic instruments, respectively (p < 2.81 × 10-2). In contrast, we did not observe a significant causal effect of MDD on SA. The GWAS-pairwise program successfully identified seven pleiotropic genetic variants (PPA3 > 0.8), indicating that the two diseases indeed have a shared genetic basis. At a whole-genome level, the MAGMA program identified 44 pleiotropic genes, which were enriched in allergy-related pathways, such as antigen processing and presentation pathway (p = 1.46 × 10-2). In brain-specific tissue, the S-MultiXcan program found 17 pleiotropic genes that were significantly enriched in immune-related pathways and GO sets, including asthma-related pathway, T-cell activation-related, and major histocompatibility complex protein-related GO sets. Regarding whole-blood tissue, the program identified six pleiotropic genes that are significantly enriched in tolerance induction-related GO sets.
CONCLUSIONS: The present study for the first time indicated a significant causal effect of SA on the occurrence of MDD, but the reverse was not true. Enrichment analyses of pleiotropic genes at whole-genome and tissue-specific levels implied the involvement of allergy and immune-related pathways in the shared genetic mechanism of the two diseases. Elucidating the causal effect and the acting direction may be beneficial in reducing the incidence rate of MDD for the massive group of SA patients in the East Asian region.

Food allergies are a growing public health problem with recent estimates of 10% of the US population affected by this immunologic disease. The quality of life is greatly impaired in food allergic individuals and their caregivers due to constant vigilance and fear of accidental exposure. Shellfish allergies are of particular concern because their prevalence has increased over the past 15 years, now affecting an estimated 3% of the adult population and 1.3% of children in the USA. Additionally, they are rarely outgrown, can result in fatal reactions, and there are no FDA-approved therapies for shellfish allergies. Reactions to one type of shellfish, crustaceans (shrimp, lobster, and crab), can be especially severe. The major crustacean allergens are highly conserved across species, resulting in high cross-reactivity of IgE between shrimp, lobster, and crab in allergic individuals. To develop novel therapies for shellfish allergies, preclinical mouse models are required. In this chapter, we present detailed methodology to induce shrimp allergy in CC027 mice. Once sensitized, mice produce shrimp-specific IgE, that is cross-reactive with lobster and crab, and experience anaphylaxis upon shrimp challenge. This model can be used to further investigate mechanisms of sensitization and preclinical testing of therapies.

Shellfish is a leading cause of food allergy and anaphylaxis worldwide. Recent advances in molecular characterization have led to a better understanding of the allergen profile. High sequence homology between shellfish species and between shellfish and house dust mites leads to a high serological cross-reactivity, which does not accurately correlate with clinical cross-reactions. Clinical manifestations are immediate and the predominance of perioral symptoms is a typical feature of shellfish allergy. Diagnosis, as for other food allergies, is based on SPTs and specific IgE, while the gold standard is DBPCFC. Cross-reactivity between shellfish is common and therefore, it is mandatory to avoid all shellfish. New immunotherapeutic strategies based on hypoallergens and other innovative approaches represent the new frontiers for desensitization.

Shellfish, including various species of mollusks (e.g., mussels, clams, and oysters) and crustaceans (e.g., shrimp, prawn, lobster, and crab), have been a keystone of healthy dietary recommendations due to their valuable protein content. In parallel with their consumption, allergic reactions related to shellfish may be increasing. Adverse reactions to shellfish are classified into different groups: (1) Immunological reactions, including IgE and non-IgE allergic reactions; (2) non-immunological reactions, including toxic reactions and food intolerance. The IgE-mediated reactions occur within about two hours after ingestion of the shellfish and range from urticaria, angioedema, nausea, and vomiting to respiratory signs and symptoms such as bronchospasm, laryngeal oedema, and anaphylaxis. The most common allergenic proteins involved in IgE-mediated allergic reactions to shellfish include tropomyosin, arginine kinase, myosin light chain, sarcoplasmic calcium-binding protein, troponin c, and triosephosphate isomerase. Over the past decades, the knowledge gained on the identification of the molecular features of different shellfish allergens improved the diagnosis and the potential design of allergen immunotherapy for shellfish allergy. Unfortunately, immunotherapeutic studies and some diagnostic tools are still restricted in a research context and need to be validated before being implemented into clinical practice. However, they seem promising for improving management strategies for shellfish allergy. In this review, epidemiology, pathogenesis, clinical features, diagnosis, and management of shellfish allergies in children are presented. The cross-reactivity among different forms of shellfish and immunotherapeutic approaches, including unmodified allergens, hypoallergens, peptide-based, and DNA-based vaccines, are also addressed.

BACKGROUND: Allergies to house dust mite (HDM) and to crustaceans are clinically and pathogenically linked. Several homologous allergenic proteins have been identified, among which tropomyosin is the prototype, expressing epitopes endowed with variable levels of immunoglobulin E (IgE) cross-reactivity. Component-resolved diagnosis (CRD) does not allow a thorough characterization of all relevant IgE reactivities to these allergen sources.
OBJECTIVE: We studied 1 patient allergic to shrimp with positive skin prick test to HDM and negative scores for IgE to HDM allergen components routinely used in CRD (group 1 and 2 allergens, Der p 23 and tropomyosin).
METHODS: In order to identify the allergen(s) involved in IgE reactivity, we used serological proteome analysis (SERPA), which utilizes two-dimensional gel electrophoresis (2DE), immunoblotting and mass spectrometry (MS). The identified allergenic proteins were tested with sera from 20 crustacean-allergic patients and 19 grass-allergic patients serving as controls.
RESULTS: Der p 14 and myosin heavy chain type 1 (MHC1) were identified as the components recognized by patient\'s IgE in the proteome of Dermatophagoides pteronyssinus and Penaeus monodon, respectively. The MHC1 protein shows about 30% sequence identity with Der p 14 in specific domains, and cross-reactivity against epitopes shared by the 2 proteins was demonstrated by reduced reactivity to shrimp extract following pre-incubation with Der p 14. Serum IgE from 5 out of 20 patients allergic to crustaceans reacted with MHC1, compared to none among 19 controls (p < 0.05).
CONCLUSIONS: We identified MHC1 as a relevant allergic component in the proteome of Penaeus monodon, the prototypic allergen source used in diagnosis of allergy to crustaceans. Our data demonstrate MHC1 cross-reactivity between MHC1 and Der p 14 from Dermatophagoides pteronyssinus.