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Doctoral Thesis
DOI
10.11606/T.10.2010.tde-18012011-133236
Document
Author
Full name
Andréia Oliveira Latorre
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2010
Supervisor
Committee
Górniak, Silvana Lima (President)
Garcia, Primavera Borelli
Justo, Giselle Zenker
Pinto, Frederico Azevedo da Costa
Spinosa, Helenice de Souza
Title in Portuguese
Efeitos imunotóxicos da Pteridium aquilinum em células natural killer de camundongos e a reversão destes efeitos com selênio
Keywords in Portuguese
Citometria de fluxo
Imunoestimulação
Metalotioneína
Microarranjo de DNA
Ptaquilosídeo
Abstract in Portuguese
Os resultados obtidos no mestrado mostraram que a samambaia do campo (Pteridium aquilinum) reduz a citotoxicidade das células natural killer (NK) esplênicas e a resposta imune celular do tipo tardia (DTH) de camundongos. Entretanto, até aquele momento não era sabido qual a célula afetada pela planta causava a diminuição da DTH. Assim, o objetivo inicial deste estudo foi verificar qual a célula envolvida na diminuição da DTH. Além disto, buscou-se descobrir o mecanismo de ação imunotóxico da P. aquilinum, o principio tóxico envolvido e se este efeito poderia ser revertido pelo selênio (Se). Para tal, camundongos C57BL/6 foram administrados com extrato de P. aquilinum, por gavage, durante 30 dias e suplementados com Se por mais 30 dias e a análise histológica revelou redução significativa na área de polpa branca esplênica que foi completamente revertida pelo tratamento com Se. Ainda, foi possível verificar que a diminuição da DTH foi causada pela redução da produção de IFNγ pelas células NK durante a indução da resposta imune celular. Além disto, camundongos administrados com ptaquilosídeo, por gavage, durante 14 dias mostraram a mesma redução na atividade das células NK causada pelo extrato de P. aquilinum, assim como a prevenção deste efeito pela co-administração de Se. Por fim, na análise da expressão gênica das células NK esplênicas dos camundongos tratados com ptaquilosídeo e/ou selênio pôde-se observar o aumento da expressão dos genes Mt1 e Mt2, possíveis responsáveis pelo mecanismo imunotóxico da planta, sendo posteriormente confirmado pelo aumento de metalotioneína e consequente redução de Zn2+ livre no espaço intracelular das células NK. Os resultados deste estudo claramente mostram que os efeitos imunossupressores da P. aquilinum são induzidos pelo ptaquilosídeo e são decorrentes do aumento da expressão dos genes da Mt1 e Mt2 e que a suplementação com Se pode prevenir e reverter estes efeitos tóxicos.
Title in English
Immunotoxic effects of Pteridium aquilinum in natural killer cells from mice and the reversion of these effects by selenium
Keywords in English
DNA microarray
Flow cytometry
Immunostimulation
Metallothionein
Ptaquiloside
Abstract in English
The results obtained in the master showed that the bracken fern (Pteridium aquilinum) reduces both the cytotoxicity of splenic natural killer cells (NK) and the delayed-type hypersensitivity (DTH) from mice. However, it was not known until that time, which cell affected by the plant that caused a decrease in DTH. Thus, the initial goal of this study was to determine which cell was involved in the reduction of DTH. Moreover, we sought to discover the mechanism of action of the P. aquilinum, the toxic principle involved and whether this effect could be reversed by selenium (Se). For that, C57BL/6 mice were treated with extract of P. aquilinum, by gavage, for 30 days and supplemented with Se for following 30 days. The histological analysis revealed a significant reduction in the splenic white pulp area that was completely reversed by treatment with Se. Still, it was verified that the decrease in DTH was caused by reduced production of IFNγ by NK cells during the induction of cellular immune response. In addition, the mice administered with ptaquiloside, by gavage, for 14 days showed the same reduction in the NK cell activity caused by the extract of P. aquilinum, as well as the prevention of this effect by co-administration of Se. Finally, we could observe an increase in the expression of Mt1 and Mt2 genes in the gene expression analysis of splenic NK cells from mice treated with ptaquiloside and/or selenium. These genes were probably responsible for immunotoxic mechanism of the plant, which was confirmed later by the augment of metallothionein and consequent reduction of free Zn2+ into the intracellular space of NK cells. The results of this study clearly show that the immunosuppressive effects of P. aquilinum are induced by ptaquiloside and they are a consequence of the augment in the gene expression of Mt1 and Mt2 and that the supplementation with Se can prevent and reverse these toxic effects.
 
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Publishing Date
2011-02-15
 
WARNING: The material described below relates to works resulting from this thesis or dissertation. The contents of these works are the author's responsibility.
  • ELIAS, F., et al. Haematological and immunological effects of repeated dose exposure of rats to integerrimine N-oxide from Senecio brasiliensis [doi:10.1016/j.fct.2011.06.032]. Food and Chemical Toxicology [online], 2011, vol. 49, p. 2313-2319.
  • LATORRE, A. O., et al. First report on rotenoids as neurotoxic principles of seeds from Aeschynomene indica (leguminosae). Journal of Animal and Veterinary Advances, 2011, vol. 10, p. 291-294.
  • LATORRE, A. O., et al. Selenium reverses Pteridium aquilinum-induced immunotoxic effects. Food and Chemical Toxicology, 2011, vol. 49, p. 464-470.
  • LATORRE, A.O., et al. Selenium reverses Pteridium aquilinum-induced immunotoxic effects [doi:10.1016/j.fct.2010.11.026]. Food and Chemical Toxicology [online], 2011, vol. 49, n. 2, p. 464-470.
  • LATORRE, ANDREIA O., et al. Ptaquiloside reduces NK cell activities by enhancing metallothionein expression, which is prevented by selenium. Toxicology (Amsterdam), 2013, vol. 304, p. 100-108.
  • Latorre, A.O., et al. Zinc Balance Is Critical For Prevention And Reversion Of Pteridium aquilinum-Induced Immunotoxicity. In 30th Annual Meeting of the Society of Toxicologic Pathology, Denver, 2011. 30th Annual Meeting of the Society of Toxicologic Pathology., 2011. Abstract.
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