Análise da participação das proteínas Bax e Bcl-2 em células endoteliais humanas durante a evolução da infecção por taquizoítos de Toxoplasma gondii

• Autor(a) principal: Oliveira, Mariana de Freitas
• Data de Publicação: 2010
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/7813
• topic: HUVEC; T. gondii; Bcl-2 family; Mitochondria; Apoptosis; HUVEC; T. gondii; Família Bcl-2; Mitocôndria; Apoptose; CNPQ::CIENCIAS BIOLOGICAS::MORFOLOGIA

Toxoplasmosis is a zoonosis widely distributed that affects over a third of world population and is of great importance on public health. Most Toxoplasma gondii infection in humans is asymptomatic. However, on recent years toxoplasmosis has been investigated since it comes as some opportunistic diseases in patients with the acquired immunodeficiency syndrome (AIDS) and transplant patients. Congenital toxoplasmosis can cause miscarriage or serious damage to the fetus leading to mental retardation and blindness in children, significantly reducing the quality of life of survivors. Thus, congenital transmission can be much more important than previously thought. Studies on the development of Toxoplasma gondii in different host cells are necessary for an appropriate therapy. At this study we employed the immunofluorescence and ultrastructural immunocytochemical assay with the aim to investigate the involvement of Bax and Bcl-2, members of Bcl-2 family which regulate apoptosis and the mitochondrial dynamic during the infection progress of human umbilical vein endothelial cells (HUVEC) by tachyzoites of T. gondii. Confocal microscopy revealed a mitochondrial filamentous network stained by Mito Tracker Red within cytoplasm of HUVEC and after 2h of infection this network became desorganized, probably as a consequence of T. gondii invasion. However, at 6h of infection, we observed the restructuring of the mitochondrial network in the cytoplasm of HUVEC, which remained at the time of 20h of infection. Even by confocal microscopy we observed Bax pro-apoptotic protein located mainly in the cytoplasm, in the mitochondria, and for the first time it was detected in the nucleus of HUVEC. At the time of 2h of infection, we observed the expression of Bax mainly in mitochondria. However, after 6h and 20h of infection, this expression decreased such in mitochondria as in HUVEC cytoplasm. The Bcl-2 expression was not observed in uninfected and HUVEC infected for 2h, 6h and 20h. Tachyzoites of T. gondii presented positive labeling for Bax and Bcl-2 over all time of infection. The ultrastructural analysis confirmed the mitochondrial dynamics observed by confocal microscopy throughout the interaction. The results of immunocytochemistry confirmed Bax expression in the nucleus of HUVEC and the expression of Bax and Bcl-2 in isolated tachyzoites of T. gondii. Therefore, our results suggest that T. gondii modulates the mitochondria morphology and Bax expression in HUVEC, probably interfering on the host cells defense mechanisms, including the progression of apoptosis.