Oxidative stress fuels Trypanosoma cruzi infection in mice
Claudia N. Paiva, … , Joseli Lannes-Vieira, Marcelo T. Bozza
Claudia N. Paiva, … , Joseli Lannes-Vieira, Marcelo T. Bozza
Published June 25, 2012
Citation Information: J Clin Invest. 2012;122(7):2531-2542. https://doi.org/10.1172/JCI58525.
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Research Article

Oxidative stress fuels Trypanosoma cruzi infection in mice

Abstract

Oxidative damage contributes to microbe elimination during macrophage respiratory burst. Nuclear factor, erythroid-derived 2, like 2 (NRF2) orchestrates antioxidant defenses, including the expression of heme-oxygenase–1 (HO-1). Unexpectedly, the activation of NRF2 and HO-1 reduces infection by a number of pathogens, although the mechanism responsible for this effect is largely unknown. We studied Trypanosoma cruzi infection in mice in which NRF2/HO-1 was induced with cobalt protoporphyrin (CoPP). CoPP reduced parasitemia and tissue parasitism, while an inhibitor of HO-1 activity increased T. cruzi parasitemia in blood. CoPP-induced effects did not depend on the adaptive immunity, nor were parasites directly targeted. We also found that CoPP reduced macrophage parasitism, which depended on NRF2 expression but not on classical mechanisms such as apoptosis of infected cells, induction of type I IFN, or NO. We found that exogenous expression of NRF2 or HO-1 also reduced macrophage parasitism. Several antioxidants, including NRF2 activators, reduced macrophage parasite burden, while pro-oxidants promoted it. Reducing the intracellular labile iron pool decreased parasitism, and antioxidants increased the expression of ferritin and ferroportin in infected macrophages. Ferrous sulfate reversed the CoPP-induced decrease in macrophage parasite burden and, given in vivo, reversed their protective effects. Our results indicate that oxidative stress contributes to parasite persistence in host tissues and open a new avenue for the development of anti–T. cruzi drugs.

Authors

Claudia N. Paiva, Daniel F. Feijó, Fabianno F. Dutra, Vitor C. Carneiro, Guilherme B. Freitas, Letícia S. Alves, Jacilene Mesquita, Guilherme B. Fortes, Rodrigo T. Figueiredo, Heitor S.P. Souza, Marcelo R. Fantappié, Joseli Lannes-Vieira, Marcelo T. Bozza

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Figure 3

CoPP reduces parasitism via macrophage physiology and NRF2 target genes.

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CoPP reduces parasitism via macrophage physiology and NRF2 target genes....
(A) Effects of in vivo treatment with CoPP or SnPP on the mean parasite burden of peritoneal macrophages at 8 dpi (n = 3 mice/group). Peritoneal cells were cultured for an additional 48 hours before cells were fixed. (B) Effects of treatment with CoPP or SnPP on the mean parasite burden of thioglycollate-elicited macrophages infected in vitro. (C) Effects of treatment with CoPP on the mean parasite burden of L929 fibroblast cells. (D) Effects of prior transfection of THP-1 cells with HO-1 or empty vector on mean parasite burden. (E) Effects of treatment with CoPP on mean parasite burden of BMMs derived from wild-type and Hmox1–/– mice or (F) Nrf2–/– mice. (G) Effects of prior transfection of THP-1 cells with Nrf2 or empty vector on mean parasite burden. (H–L) Dose-dependent decreases in macrophage parasitism with the NRF2 activators. (M) Mean parasitemia during acute infection (n = 8) in mice treated with pterostilbene or resveratrol. Thioglycollate-elicited macrophages were infected with 3:1 trypomastigotes in vitro for 12 hours and treated with drugs for 48 hours. Each experiment was performed with 2 independent samples of cells, and results for 1 sample are shown. Cells were stained with Giemsa, and amastigotes were counted in each of 100 infected cells. The mean percentage of infected cells was calculated for each field, and 20 fields were assessed. All experiments were performed at least twice, with similar results. *P < 0.05 compared with infected nontreated controls. Error bars represent SEM. Scale bars: 20 μm.