Efeito de prostaglandinas sobre a atividade fingicida de monócitas humanos desafiados com o Paracoccidioides brasiliensis
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Data
2008-12-12
Autores
Graciani, Ana Paula Bordon [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Paracoccidioides brasiliensis (Pb), agente etiológico da paracoccidioidomicose, é um fungo dimórfico que sobrevive no interior de monócitos/macrófagos humanos não ativados. Estudos anteriores em nosso laboratório têm demonstrado que os monócitos humanos não ativados são incapazes de realizar atividade fungicida, e esse processo está associado com a capacidade do fungo induzir a produção de prostaglandinas (PGs), uma vez que, essas células são capazes de realizar atividade fungicida significativa após o tratamento com indometacina (INDO), um inibidor da produção de ciclooxigenase. No entanto, o processo de pré-ativação com IFN-γ, resulta em um parcial efeito compensatório sobre os efeitos inibidores das PGs, principalmente quando essas células são desafiadas com a cepa de baixa virulência do fungo. Assim, a proposta deste presente estudo foi avaliar se a ativação de monócitos humanos com outras citocinas como TNF-α e GM-CSF resulta em um efeito similar ao observado com IFN-γ. Uma outra questão a ser respondida é se esse processo poderia estar associado com alterações nos níveis de H2O2 e NO, que são moléculas efetoras envolvidas na atividade fungicida contra o P. brasiliensis, bem como nos níveis das citocinas TNF-α, IL-10 e IL-6. Culturas de monócitos do sangue periférico, obtidos de 20 indivíduos normais foram tratadas somente com INDO ou ativados com IFN-γ, TNF-α ou GM-CSF na presença ou ausência de INDO por 18h, e posteriormente desafiados com cepas de alta (Pb18) ou baixa (Pb265) virulência do P. brasiliensis por 4h. Após esse período, as culturas foram avaliadas quanto à atividade fungicida, produção de H2O2 e NO e expressão de mRNA para enzima óxido nítrico sintase (iNOS) por RT-PCR em tempo real. As concentrações de TNF-α, IL-6 e IL-10 nos sobrenadantes das coculturas foram avaliadas por ELISA. Nossos resultados...
Paracoccidioides brasiliensis (Pb), the etiological agent of paracoccidioidomycosis, is a dimorphic fungus that survives within nonactivated human monocytes/macrophages. Previous studies have demonstrated that the lack of fungicidal activity by nonactivated human monocytes is associated to fungus capacity to inducing prostaglandins release, since a significative fungicidal activity was detected after monocytes treatment with indomethacin (INDO), a cyclooxigenase inhibitor. However, cells activation with IFN-γ seems to partially compensating this inhibitory effect, mainly when cells were challenged with low virulent strain of the fungus. Here, we extended our studies, addressing whether monocytes activation with other cytokines such as TNF-α and GM-CSF results in a similar effect to that observed with IFN-γ. Moreover, we asked if this process could be associated with alterations on H2O2 and NO levels, the molecules involved in Pb killing, as well as in the levels of the cytokines TNF-α, IL-10 and IL-6. Peripheral blood monocytes obtained from 18 healthy donors were treated only with INDO or activated with IFN-γ, TNF-α or GM-CSF in presence or absence of INDO for 18h, and further challenged with high (Pb18) or low (Pb265) virulent strain of Pb for 4h. After, cultures were evaluated for fungicidal activity, H2O2 and NO release and expression of inducible nitric oxide synthase (iNOS) mRNA by real-time RT-PCR. The concentrations of TNF-α, IL-6 and IL-10 on supernatants of cocultures were evaluated by ELISA. Our results provided evidence that human monocytes challenged with both strains of P. brasiliensis release prostaglandins that via induction of IL-10 and IL-6 inhibits TNF-α production. This process results in defective cell activation with consequent release of low H2O2 levels and lack of fungicidal activity by cells. However the inhibitory effect of PGs may be... (Complete abstract click electronic access below)
Paracoccidioides brasiliensis (Pb), the etiological agent of paracoccidioidomycosis, is a dimorphic fungus that survives within nonactivated human monocytes/macrophages. Previous studies have demonstrated that the lack of fungicidal activity by nonactivated human monocytes is associated to fungus capacity to inducing prostaglandins release, since a significative fungicidal activity was detected after monocytes treatment with indomethacin (INDO), a cyclooxigenase inhibitor. However, cells activation with IFN-γ seems to partially compensating this inhibitory effect, mainly when cells were challenged with low virulent strain of the fungus. Here, we extended our studies, addressing whether monocytes activation with other cytokines such as TNF-α and GM-CSF results in a similar effect to that observed with IFN-γ. Moreover, we asked if this process could be associated with alterations on H2O2 and NO levels, the molecules involved in Pb killing, as well as in the levels of the cytokines TNF-α, IL-10 and IL-6. Peripheral blood monocytes obtained from 18 healthy donors were treated only with INDO or activated with IFN-γ, TNF-α or GM-CSF in presence or absence of INDO for 18h, and further challenged with high (Pb18) or low (Pb265) virulent strain of Pb for 4h. After, cultures were evaluated for fungicidal activity, H2O2 and NO release and expression of inducible nitric oxide synthase (iNOS) mRNA by real-time RT-PCR. The concentrations of TNF-α, IL-6 and IL-10 on supernatants of cocultures were evaluated by ELISA. Our results provided evidence that human monocytes challenged with both strains of P. brasiliensis release prostaglandins that via induction of IL-10 and IL-6 inhibits TNF-α production. This process results in defective cell activation with consequent release of low H2O2 levels and lack of fungicidal activity by cells. However the inhibitory effect of PGs may be... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Paracoccidiodes brasiliensis - Tratamento, Fungos, Prostaglandin, Human monocytes, Fungicidal activity
Como citar
GRACIANI, Ana Paula Bordon. Efeito de prostaglandinas sobre a atividade fingicida de monócitas humanos desafiados com o Paracoccidioides brasiliensis. 2008. 92 f. Tese (doutorado) - Universidade Estadual Paulista, Faculdade de Medicina de Botucatu, 2008.