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Toxoplasma gondii : infeção experimental e estudo da resposta imunológica e inflamatória utilizando diversos genótipos
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Resumo(s)
A toxoplasmose é uma zoonose provocada pelo protozoário intracelular obrigatório Toxoplasma gondii,
capaz de infetar animais de sangue quente. O ciclo sexuado ocorre exclusivamente em felídeos, enquanto
nos hospedeiros intermediários apenas se verificam estágios assexuados. Estudos mostram uma elevada
diversidade genética do parasita, com três linhagens clonais predominantes na América do Norte e
Europa (tipos I, II e III) e linhagens atípicas predominantes na América do Sul, frequentemente
associadas a quadros clínicos mais graves. Este trabalho teve como objetivo avaliar a resposta
inflamatória de células Caco-2, modelo in vitro do epitélio intestinal humano, infetadas com diferentes
genótipos (tipo I e III), analisando fenótipos como proliferação celular, captação de FITC-Dextran e a
percentagem de células infetadas. Os resultados evidenciaram diferenças no impacto dos dois genótipos.
Os ensaios de viabilidade celular mostraram que a exposição ao antigénio de excreção-secreção (ESA)
não afetou a viabilidade das células ao longo de 7 e 14 dias. Observou-se uma diminuição significativa
na percentagem de células infetadas ao longo do tempo de diferenciação, sendo esta mais acentuada nas
infeções com o tipo III. A análise da captação e quantificação de FITC-Dextran revelou níveis superiores
em células infetadas, comparativamente ao controlo, sugerindo alterações na permeabilidade epitelial
induzidas pelo parasita. Estes resultados demonstram que a diferenciação das células Caco-2 é um fator
determinante na resposta a infeções.
Toxoplasmosis is a zoonosis caused by the obligatory intracellular protozoan Toxoplasma gondii, capable of infecting warm-blooded animals. Its sexual cycle occurs exclusively in felines, while only asexual stages are observed in intermediate hosts. Studies show a high genetic diversity of the parasite, with three clonal lineages predominating in North America and Europe (types I, II, and III) and atypical lineages predominating in South America, often associated with more severe clinical outcomes. This study aimed to evaluate the inflammatory response of Caco-2 cells, an in vitro model of the human intestinal epithelium, infected with different genotypes (type I and III), by analyzing phenotypes such as cell proliferation, FITC-Dextran uptake, and the percentage of infected cells. The results revealed differences in the impact of the two genotypes. Cell viability assays showed that exposure to excretionsecretion antigens (ESA) did not affect cell viability over 7 and 14 days. A significant decrease in the percentage of infected cells was observed over the differentiation period, being more pronounced in infections with type III. The analysis of FITC-Dextran uptake and quantification revealed higher levels in infected cells compared to the control, suggesting parasite-induced alterations in epithelial permeability. These findings demonstrate that the differentiation of Caco-2 cells is a key factor in the response to infections.
Toxoplasmosis is a zoonosis caused by the obligatory intracellular protozoan Toxoplasma gondii, capable of infecting warm-blooded animals. Its sexual cycle occurs exclusively in felines, while only asexual stages are observed in intermediate hosts. Studies show a high genetic diversity of the parasite, with three clonal lineages predominating in North America and Europe (types I, II, and III) and atypical lineages predominating in South America, often associated with more severe clinical outcomes. This study aimed to evaluate the inflammatory response of Caco-2 cells, an in vitro model of the human intestinal epithelium, infected with different genotypes (type I and III), by analyzing phenotypes such as cell proliferation, FITC-Dextran uptake, and the percentage of infected cells. The results revealed differences in the impact of the two genotypes. Cell viability assays showed that exposure to excretionsecretion antigens (ESA) did not affect cell viability over 7 and 14 days. A significant decrease in the percentage of infected cells was observed over the differentiation period, being more pronounced in infections with type III. The analysis of FITC-Dextran uptake and quantification revealed higher levels in infected cells compared to the control, suggesting parasite-induced alterations in epithelial permeability. These findings demonstrate that the differentiation of Caco-2 cells is a key factor in the response to infections.
Descrição
Tese de Mestrado, Biologia Humana e Ambiente, 2024, Universidade de Lisboa, Faculdade de Ciências
Palavras-chave
T. gondii Genótipos Inflamação Infeção experimental Caco-2 Teses de mestrado - 2024