Induction of Shrimp Tropomyosin-Specific Hypersensitivity in Mice

Abstract

Background: Shellfish hypersensitivity is amongst the most common food allergies. The major shellfish allergen was identified as tropomyosin. Here, we investigated the immediate hypersensitivity responses, IgE and cell-mediated immune response in mice sensitized with recombinant shrimp tropomyosin. Methods: Shrimp tropomyosin was cloned and expressed as a His-tagged fusion recombinant protein in Escherichia coli. Three- to 4-week-old BALB/c mice were sensitized by intragastric administration of recombinant tropomyosin (0.1 mg) plus cholera toxin (10 µg) on days 0, 12, 19 and 26 and challenged on day 33. Mice fed with phosphate-buffered saline plus cholera toxin were included as controls. Animals were monitored for immediate hypersensitive responses and tropomyosin-specific IgE over time. In addition, shrimp tropomyosin-specific CD4+ T cells, interleukin-4 and interferon-γ levels were determined from in vitro splenocyte cultures. A passive cutaneous anaphylaxis assay was also conducted. Results: Mice fed with shrimp tropomyosin developed swelling of the snout, increased scratching behavior and shrimp tropomyosin-specific IgE. Sera from tropomyosin-sensitized mice elicited vascular leakage in naïve mice in the passive cutaneous anaphylaxis assay. Shrimp tropomyosin-specific CD4+ T cell proliferations and elevated interleukin-4 over interferon-γ levels were evident in splenocyte cultures of tropomyosin-fed mice upon tropomyosin stimulation. In contrast, shrimp tropomyosin-specific IgE, CD4+ T cells and hypersensitive responses were absent in the control mice. Conclusion: We have generated a BALB/c model of shrimp allergy. This model provides a useful tool for evaluating the immunopathogenic mechanisms involved in shellfish hypersensitivity.

An Adjuvant-Free Mouse Model of Transdermal Sensitization and Oral Elicitation of Anaphylaxis to Shellfish

“…There are 3 previous elegant studies that reported on the development of shrimp allergy and 1 on mud crab allergy using mouse models with BALB/c and C3H/HeJ mice [25,26,27,28]. Thus, Capobianco et al [27] reported a shrimp tropomyosin allergy mouse model using C3H/HeJ mice with oral exposure to purified shrimp tropomyosin along with cholera toxin adjuvant; their readouts of allergenicity included sIgE (OD values; no titers), spleen-cell IL-4 production and systemic anaphylactic symptom scores upon OC.…”

“…Thus, Capobianco et al [27] reported a shrimp tropomyosin allergy mouse model using C3H/HeJ mice with oral exposure to purified shrimp tropomyosin along with cholera toxin adjuvant; their readouts of allergenicity included sIgE (OD values; no titers), spleen-cell IL-4 production and systemic anaphylactic symptom scores upon OC. Lam et al [25] and Leung et al [26] reported another shrimp tropomyosin allergy model using recombinant protein and BALB/c mice using intragastric exposure with cholera toxin adjuvant [25,26]. Readouts of allergenicity included sIgE responses (OD values; no titers), spleen-cell IL-4 responses, oral allergen-induced symptom scores and histopathological changes in the gut.…”

“…As opposed to previous models of shrimp and mud crab allergy that used purified/recombinant proteins, we chose to use standardized mixed SFPE that is used in clinical testing for humans [25,26,27,28]. The rationale underlying our approach was to simulate the natural TDE to SF proteins in an occupational setting such as the SF industry where exposure is likely to be to multiple types of SF proteins.…”

“…However, there are relatively few efforts reported in the literature on the development of animal models. Three reported mouse models of shrimp tropomyosin allergy and 1 of mud crab allergy share the following features: (1) the use of adjuvants (cholera toxin/complete Freund's adjuvant) and (2) the use of either systemic (intraperitoneal injections) or oral exposure to induce sensitization [25,26,27,28]. These models are highly valuable and useful for studying SF allergy mechanisms in the context of coexposure of allergens with powerful adjuvants.…”

Low-Dose Allergen-Specific Immunotherapy Induces Tolerance in a Murine Model of Shrimp Allergy

“…Although the major shrimp allergen tropomyosin has been characterized, clinical trials for shrimp allergy AIT are still lacking. Here, we adopted a well-established mouse model that mimics the clinical responses in shrimp allergic patients [10], in order to investigate the dose-response effect of AIT with recombinant (r) shrimp tropomyosin from Metapenaeus ensis , i.e., rMet e 1, in treatment. …”