Caspase-1 but not IL-1R mediates <i>T. cruzi</i>-induced NO secretion.

<p>PMs (3×10⁵/well of chamber slides) from WT, MyD88^−/− and NLRP3^−/− mice were infected with <i>T. cruzi</i> Y trypomastigotes (5 parasites/cell) for 2–4 h. After the extracellular parasites were removed, AG (1 mM) was added to the cultures. After 48 h, the chambers were fixed with methanol, stained with DAPI and evaluated by fluorescence microscopy (600×). The numbers represent the increase in the number of amastigotes compared to untreated cells, and 1000 macrophages were counted from a representative experiment (<b>A</b>). PMs (3×10⁵/well of chamber slides) from WT, caspase-1^−/− and IL-1R^−/− mice (3 parasites/cell) were infected with <i>T. cruzi</i> Y trypomastigotes (5 parasites/cell) for 2–4 h. Chambers were obtained as described and evaluated by fluorescence microscopy (600×). The number of amastigotes was counted in 1000 macrophages from a representative experiment. The experiments were repeated two times with similar results (<b>B</b>). <i>T. cruzi</i>-infected PMs (3 parasites per cell) (1,5×10⁶ cells/300 µl) from WT, caspase-1^−/−, iNOS^−/− and IL-1R^−/− mice were treated or not with z-YVAD-fmk (10 µM) or AG (1 mM). After 48 h, nitrite accumulation was measured in the culture supernatants by the Griess reaction. Bars represent the mean ± S.D. of triplicate samples. *** p>0,001 compared to the untreated group (<b>C</b>). <i>T. cruzi</i>-infected PMs (3×10⁵/well of chamber slides) from WT, caspase-1^−/−, iNOS^−/− and IL-1R^−/− mice (3 parasites/cell) were treated or not with z-YVAD-fmk (10 µM) or AG (1 mM). Chambers were obtained as described above and evaluated by fluorescence microscopy (600×). The frequency of infected macrophages was counted in 1000 macrophages from a representative experiment. Bars represent the rate of increase compared to untreated cells, where *** p>0,001 compared to the untreated group. The experiments were repeated two times with similar results (<b>D</b>).