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Anaphylaxis induced by extracts of tropical fruit pineapple (Ananas comosus) and papaya (Carica papaya) in a murine model

Grant number: 12/03186-5
Support type:Scholarships in Brazil - Post-Doctorate
Effective date (Start): June 01, 2012
Effective date (End): May 31, 2015
Field of knowledge:Health Sciences - Medicine
Principal Investigator:Fabio Fernandes Morato Castro
Grantee:Fernanda Miriane Bruni Soliani
Home Institution: Faculdade de Medicina (FM). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Allergies are a significant and widespread public health problem. Anaphylaxis reactions are induced by medications, venoms, foods and others. The classical mechanism of allergy is: antigen crosslinking of antigen-specific IgE bound to mast cell FceRI stimulates mast cell degranulation, with the rapid release of histamine and serotonin and the synthesis and secretion of platelet-activating factor (PAF) and leukotrienes. In mice the allergen can trigger a distinct response where "anaphylactic" antibodies are IgG antibody, macrophages, mast cells and basophils, Fc³RIII and Platelet Activating Factor (PAF). The allergies incidence are increasing in recent decades (Sampson et al., 2004). Allergic inflammation often is classified into temporal phases: a) early-phase reactions (anaphylaxis) are induced within seconds to minutes of allergen challenge and mainly reflect the secretion of mediators responsible for the symptomatic; b) late phase, is characterized by accumulation and activation of inflammatory cells accompanied by the persistent production of mediators by resident cells; c) chronic allergic inflammation, repetitive and prolonged exposure to specific allergen induces the presence of a large numbers of inflammatory cells and changes in the extracellular matrix in the affected tissues. Animal models of food allergy is of great importance and have been used to identify both the mechanisms involved in sensitization to the allergen as those involved in triggering allergies. The murine models developed are different among them. The use of adjuvants such as Cholera toxin is required for the development of food allergy by preventing tolerance but some models free of adjuvant are being proposed.The allergens are substances of various natures able to elucidate a Th2 response, culminating in the IgE production. Most allergen is proteins and the protease which may be the major allergen or inductor act as an adjuvant response, facilitating the development reaction to other proteins present in the solution. The serine and cysteine proteases are allergen of arthropods, mammals, fungi and plants. Some innocuous foods have caused allergies in humans. The Food Allergy´s clinic of the Department of Clinical Immunology and Allergy of the HC of São Paulo has received more and more patients with a history of allergy to various fruits being the predominant pineapple, mango, papaya and jackfruit. The pineapple (Ananas comosus) and papaya (Carica papaya) proteases have already characterized in the literature and there are also reports that both can cause occupational allergy. However, there are no studies that evaluated the role of these proteases as inductors or adjuvants in the development of allergies. In order to elucidate this fact, we propose the development of a food allergy model in mice that mimics the changes seen in humans.