Artigo de Periódico
Leishmania (L.) amazonensis-induced inhibition of nitric oxide synthesis in host macrophages
Fecha
2002Registro en:
1286-4579
v. 4, n. 1
Autor
Balestieri, Filomena Maria Perrella
Queiroz, Allan Rêgo Pires
Scavone, Cristoforo
Costa, Vlaudia Maria Assis
Barral-Netto, Manoel
Abrahamsohn, Ises de Almeida
Balestieri, Filomena Maria Perrella
Queiroz, Allan Rêgo Pires
Scavone, Cristoforo
Costa, Vlaudia Maria Assis
Barral-Netto, Manoel
Abrahamsohn, Ises de Almeida
Institución
Resumen
Inhibition of lipopolysaccharide (LPS)-induced nitric oxide (NO) production was demonstrated in J774-G8 macrophages infected with Leishmania (L.) amazonensis promastigotes. The downmodulation of NO production observed in infected and LPS-stimulated J774-G8 cells correlated with a reduction in inducible nitric oxide synthase (iNOS) activity. Reduction in iNOS activity was not paralleled by decreased iNOS mRNA expression, suggesting that the parasite affects post-transcriptional events of NO synthesis. Supplementation with L-arginine or tetrahydrobiopterin did not increase NO production, suggesting that inhibition is not due to an insufficiency of substrate or co-factor. Treatment with anti-IL-10, anti-IL-4 or anti-TGF-β neutralizing antibodies also failed to increase NO production, indicating that these cytokines are not involved in the observed parasite-induced inhibition of NO synthesis. However, treatment of the cultures with IFN-γ resulted in a marked increase in NO production by infected LPS-stimulated cells. These results show that although L.(L.) amazonensis infection inhibits iNOS activity and NO production by J774-G8 cells, activation by IFN-γ is capable of overriding the suppression of NO synthesis.