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.
View: Text | PDF
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

×

Figure 4

Classical mechanisms of parasite clearance are not responsible for the decreased parasitism mediated by CoPP.

Options: View larger image (or click on image) Download as PowerPoint
Classical mechanisms of parasite clearance are not responsible for the d...
(A) Effects of CoPP on the mean percentage of TUNEL-positive cells (apoptotic) found in infected macrophages, as shown in B. Glucocorticoid-treated macrophages (gluc) are shown as a positive control. Amastigotes were also stained with TUNEL (33). Data represent percentages in 10–15 microscope fields (original magnification, ×40). Effects of CoPP on (C) IRF-3 phosphorylation in infected macrophages (immunoblots) and (D) the amounts of IFN-β transcripts (qRT-PCR). (E) Effects of CoPP on the mean parasite burden in infected macrophages derived from wild-type or Ifnar1–/– mice. (F) Effects of CoPP on the mean parasitemia of wild-type and Ifnar1–/– mice (n = 8 per group). (G) Effects of in vivo CoPP treatment on the mean nitrite production by LPS-stimulated peritoneal macrophages at 8 dpi. Cells were pooled from 3–5 mice/group, and results represent 3–4 pools (Griess). Effects of CoPP on infected macrophages: (H) Mean nitrite production upon LPS stimulation in vitro (results represent 3 independent samples evaluated by Griess); (I) Mean parasite burden of macrophages derived from wild-type or Nos2–/– mice (Giemsa), as shown in J. Effects of in vivo CoPP treatment on: (K) Mean parasitemia and (L) survival of wild-type and Nos2–/– mice (n = 4–6). Experiments were performed at least twice. Error bars represent SEM. *P < 0.05 compared with infected untreated wild-type; #P < 0.05 compared with LPS-stimulated infected untreated macrophages; †P < 0.05 compared with infected untreated knockout mice. Scale bars: 20 μm.