Avaliação da modulação da infecção de macrófagos humanos com Leishmania (Viannia) braziliensis por leucotrienos
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2013-02-22
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Universidade Federal de Goiás
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The American Tegumentary Leishmaniasis (ATL) is an infectious disease caused by parasitic protozoa of the genus Leishmania, whose most prevalent species in Brazil is L. (Viannia) braziliensis. The human macrophage infection with L. (V.) braziliensis has been poorly investigated and is not known whether leukotrienes, lipid mediators produced by macrophages, may modulate this infection. The objective of this study was to evaluate whether leukotrienes modulate infection of human macrophages with L. (V.) braziliensis IMG3, a field clinical isolate. Human monocyte-derived macrophages were infected with promastigote forms of MHOM/BR/2003/IMG (IMG3) at a ratio of ~ 10:1 (parasite:cell). Cultures were incubated for 4 h and then washed to remove excess extracellular parasites, and incubated for additional 24, 48 or 72 h. To inhibit leukotriene synthesis, the cultures were treated with MK0591 and to antagonize the LTB4 receptor, CP-105, 696. LTB4 was also added to the cultures. The measurement of LTB4 was performed on culture supernatants using enzyme immunoassay. To evaluate the involvement of reactive oxygen intermediates (ROI) and nitric oxide (NO) their respective inhibitors were used, apocynin and aminoguanidine. To assess the production of ROIs it was used nitroblue tetrazolium salt (NBT). The IMG3 infected human macrophages, being selected periods of 4 h and 48 h incubation to assess phagocytosis and microbicidal activity, respectively. Treatments with MK0591 or CP105, 696 significantly increased the infection index after 4 h or 48 h incubation (p <005). The results show that the presence of MK0591 is need during whole incubation time (48 h) but not the LTB4 antagonist, whose effect is maintained after incubation for 4 h. The addition of LTB4 to the cultures significantly decreased macrophage infection, both during the first 4 h and after 48 h of incubation (p <0.05). The parasites induced LTB4 production in macrophage cultures during the first 30 min, but this production decreased after 4 h (p <0.05). The ROI and NO inhibitors significantly increased the infection index, before (ROI and NO) or after treatment with LTB4 (ROI). Preliminary results showed that production of superoxide anion is induced by parasites and this is further increased by LTB4. In conclusion, the results suggest that human macrophages produce leukotrienes following infection with L. (V.) braziliensis, and the main of them is LTB4. The LTB4 inhibits phagocytosis and enhances the microbicidal activity of macrophages, contributing to control of the infection. Results suggest that L. (V.) braziliensis induces LTB4, NO and ROI production and, in turn, LTB4 increases the microbicidal activity of macrophages via increase of ROI. Understanding the involvement of leukotrienes in the control of human macrophage infection with L. (V.) braziliensis can lead to the development of novel therapeutic targets for ATL.
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MORATO, Camila Imai. Avaliação da modulação da infecção de macrófagos humanos com Leishmania (Viannia) braziliensis por leucotrienos. 2013. 155 f. Dissertação (Mestrado em Medicina Tropical e Saúde Pública) - Universidade Federal de Goiás, Goiânia, 2013.