Role of leukotrienes in immune protection conferred by the heterologous immunization BCG/DNA-HSP65 against tuberculosis / Papel dos leucotrienos na proteção conferida pela imunização heteróloga BCG/DNA-HSP65 contra tuberculose

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Tuberculosis is responsible for more than 2 millions of death for year. The immune response against tuberculosis is related to activation of IFN-g-producing CD4+ and CD8+ cells. IFN-g increases the microbicidal mechanisms of macrophages to kill intracellular bacilli. Recently, the lipid mediator leukotriene B4 (LTB4) has been related to protection against several diseases, including tuberculosis. In this sense, the aim of this study was to evaluate the role of leukotrienes in the protection induced by homologous immunization with DNA-HSP65 or heterologous with BCG/DNA-HSP65 (prime-boost). Firstly, we confirmed the role of leukotrienes to control the replication of M. tuberculosis when we showed that C57BL/6 mice, which are able to contain bacilli growth, secreted high levels of LTB4; and when we blocked leukotrienes synthesis by treatment with MK-886, C57BL/6 mice became more susceptible to infection. Then, we evaluated the role of leukotrienes in the protection induced by homologous or heterologous (prime-boost) immunization. Our data showed that animals deficient in leukotrienes synthesis (5-LO KO) infected with M. tuberculosis were more susceptible to infection than WT mice. The higher susceptibility of 5-LO KO was related to the decreasing of IFN-g, nitrite and IL-17 production, increasing of PGE2 secretion, defective recruitment of inflammatory cells and increased influx of Foxp3+ cells to the lungs. Homologous immunization has lost completely its protector effect in the absence of leukotrienes, while heterologous immunization induced only partial protection. Prime-boost-immunized 5-LO KO mice secreted higher levels of IL-17 and had lower influx of Foxp3+ cells to the lungs, when compared to non-immunized infected 5-LO KO. The abrogation of the synthesis of prostaglandins during the immunization by prime-boost reduced the protector effect of the vaccine either in WT and 5-LO KO mice, suggesting that prostaglandins may be important to the process of immunization. Together, our data reinforce the key role of leukotrines in immune response against tuberculosis, suggesting that these lipid mediators may act indirectly to induce IFN-g, nitrite and IL-17 synthesis.

ASSUNTO(S)

leucotrienos lipid mediators leukotrienes prostaglandinas mediadores lipídicos vacinas tuberculose tuberculosis prostaglandins

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