Avaliação da utilização de Lactobacillus delbrueckii UFV H2b20 como adjuvante na vacinação contra Leishmania braziliensis.

One of the greatest challenges in the formulation of a vaccine against Leishmania parasites is the discovery of an adjuvant capable of enhancing the efficacy of the vaccine. Lactobacillus delbrueckii UFV H2b20 presents an immunomodulatory effect already known in mice where it induces IL-12, IFN- and TNF- production in vitro, and increases the clearance of pathogenic Escherichia coli in these animals. In mononuclear cells of the human peripheral blood of healthy volunteers, it induced the IL-12 production IFN- and TNF- and stimulated the activation of effectors mechanisms of the innate immunity, leading to the differentiation of naive T lymphocytes in Leishmania amazonensis specific Th1 lymphocytes. In this work, we decided to verify the capacity of the Lact delbrueckii to protect mice BALB/c against infection for Leishmania braziliensis, acting, thus, as an adjuvant inductor of a response that would control this parasite. It was verified that Lact delbrueckii induced the production, in vitro, of high levels of IL-12, IFN- and TNF- for splenocytes from mice BALB/c. However, when inoculated in the presence of L. braziliensis antigen, this bacterium was not able to induce protection in the mice against the inoculation of infective forms of this parasite. This result could be explained by the concomitant induction of IL-10 by Lact delbrueckii, that could cause a suppression of the protective response. We also decided to isolate the molecule that was responsible for the induction of the IL-12 production by the Lact delbrueckii. For this, an extract of the cell wall of this bacterium was prepared. This extract induced IFN- , in vitro, in a peculiar and distinct way to the complete bacterium. The analysis of this extract demonstrated that the probable immunomodulatory molecule may be a low molecular weight carbohydrate. These results demonstrate the importance of more detailed studies with Lact. delbrueckii and other probiotic bacteria in order to characterize its distinct components involved in the induction of determined cytokines.