Padronização de modelo de inflamação alérgica pela exposição a picadas de mosquitos Aedes aegypti.

Abstract

BARROS, M. S. Standardization of a model of allergic inflammation by exposure to Aedes aegypti mosquito bites. 2012. 95 f. Dissertation (Masters Thesis in Immunology) Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, 2012. During blood feeding, Aedes aegypti female mosquitoes inoculate saliva into the skin of their vertebrate hosts, modulating their immune functions and facilitating disease transmission. Some components with anticoagulant, antiplatelet and vasodilatory activities have been described in the saliva of Ae. aegypti that act by neutralizing the effects of hemostasis, allowing the meal to occur successfully. In addition, classical studies have shown that salivary secretion is responsible for the sensitization to mosquito bites and many of the components present in saliva are immunogenic and able to induce intense immune response. The immunological response to these allergens includes severe local and systemic reactions with involvement of IgE antibodies and IgG subclasses, and T cellmediated hypersensitivity. Following a mosquito bite, it is possible to observe a measurable immune and inflammatory response at the bite site and some of these reactions can be observed through the itching and swelling. Thus, the aim of this project was to develop a model to evaluate the profile of the systemic immune response developed in mice naturally exposed to Ae. aegypti mosquito bite. To do that, mice were sensitized by exposure to Ae aegypti bites and intranasally challenged with PBS or salivary gland extract (SGE) of the mosquito. Additionally, this model was compared to a classical model of allergic lung inflammation induced by sensitization and subsequent challenge with ovalbumin (OVA). After the sensitization and challenge procedures, breathing pattern, tracheal reactivity and the amount and type of cells present in bronchoalveolar lavage (BAL) were evaluated. Also, cytokines in BAL, total and specific antibodies present in serum, mucus secretion and collagen deposition in lung tissue were determined. Our results showed that mice sensitized by mosquito bites and challenged with SGE presented cellular infiltration in BAL that was dependent to the number of exposures (“1x” or “4x”), and mainly of mononuclear cells and eosinophils. The lymphocytic population was mainly of CD4 and CD19 cells. This qualitative cell profile was similar to the OVA group. In both groups, “4x” and OVA, we observed an increase in the population of T CD4 cells that produce IL-4 and IL-5 in lung and in the levels of these cytokines in BAL. Furthermore, we observed an intense mucus production by bronchial epithelial cells and little deposition of collagen around the bronchioles. Both groups showed increased levels of total IgE, specific IgG1, but only the group sensitized by bites produced significant amounts of specific IgG2a. Unlike the OVA group, mice exposed to mosquitoes showed no alterations in breathing pattern in response to methacholine. In addition, no changes were observed in the reactivity of the trachea in response to methacholine. In conclusion, our results show that the response induced by sensitization with Ae. aegypti saliva and challenge with EGS promotes a mixed response, with production antibodies of both Th1 and Th2 patterns, migration of eosinophils and mononuclear cells into the bronchoalveolar space, production of mucus in the lungs and no changes in breathing pattern and reactivity of the trachea that are common in models of pulmonary allergy.