Macrophages Promote Oxidative Metabolism To Drive Nitric Oxide Generation in Response to Trypanosoma cruzi

Abstract

dTrypanosoma cruzi is the causative agent of chronic chagasic cardiomyopathy. Why macrophages (ms), the early responders to infection, fail to achieve parasite clearance is not known. Mouse (RAW 264.7) and human (THP-1 and primary) ms were infected for 3 h and 18 h with T. cruzi TcI isolates, SylvioX10/4 (SYL, virulent) and TCC (nonpathogenic), which represent m stimulation and infection states, respectively. Ms incubated with lipopolysaccharide and gamma interferon (LPS/IFN-␥) and with interleukin-4 (IL-4) were used as controls. We monitored the cytokine profile (using enzyme-linked immunosorbent assay [ELISA]), reactive oxygen species (ROS; fluorescent probes), nitric oxide (·NO; Griess assay), and metabolic state using a customdesigned mitoxosome array and Seahorse XF24 Analyzer. LPS/IFN-␥ treatment of ms elicited a potent increase in production of tumor necrosis alpha (TNF-␣) at 3 h and of ROS and ·NO by 18 h. Upon SYL infection, murine ms elicited an inflammatory cytokine profile (TNF-␣ > > TGF-␤ ؉ IL-10) and low levels of ·NO and ROS production. LPS/IFN-␥ treatment resulted in the inhibition of oxidative metabolism at the gene expression and functional levels and a switch to the glycolytic pathway in ms, while IL-4-treated ms utilized oxidative metabolism to meet energy demands. SYL infection resulted in an intermediate functional metabolic state with increased mitoxosome gene expression and glycolysis, and IFN-␥ addition shut down the oxidative metabolism in SYL-infected ms. Further, TCC-and SYL-stimulated ms exhibited similar levels of cell proliferation and production of TNF-␣ and ROS, while TCC-stimulated ms exhibited up to 2-fold-higher levels of oxidative metabolism and ·NO production than SYL-infected ms. Inhibiting ATP-coupled O 2 consumption suppressed the ·NO generation in SYL-infected ms. Mitochondrial oxygen consumption constitutes a mechanism for stimulating ·NO production in ms during T. cruzi infection. Enhancing the oxidative metabolism provides an opportunity for increased ·NO production and pathogen clearance by ms to limit disease progression. Chagas cardiomyopathy is a neglected debilitating disease caused by the blood-borne parasite Trypanosoma cruzi. T. cruzi isolates are classified within six genetic groups (TcI to TcVI) which give insight into the evolution of the parasite (1). The virulent T. cruzi strain SylvioX10/4 (SYL) (2) and the nonpathogenic T. cruzi isolate (TCC) (3) are both of the TcI lineage which is considered to be the most common cause of disease in the Southern zone countries of South America, Central America, and Mexico. In mice and rats, SYL elicits acute parasitemia and persistent inflammatory infiltrate and injury in the myocardium and skeletal muscle during the chronic disease phase (4), while infection with the TCC isolate results in no detectable parasitemia or tissue injury (5).Macrophages (ms) serve as the first responders to T. cruzi infection, and their inflammatory activation exerts cytotoxic effects via NADPH oxidase (NOX)-mediated superoxide (O 2 · Ϫ ) ...

Modulation of host central carbon metabolism and in situ glucose uptake by intracellular Trypanosoma cruzi amastigotes

“…Infection outcomes are also anticipated to be host cell type–and perhaps parasite strain–dependent, as increased mitochondrial respiration in T . cruzi -infected macrophages was previously shown to be associated with increased nitric oxide production and parasite clearance [ 54 ], while our results show no association in non-phagocytic cells. Additional studies are needed to better understand the complex interplay between T .…”

MGL1 Receptor Plays a Key Role in the Control of T. cruzi Infection by Increasing Macrophage Activation through Modulation of ERK1/2, c-Jun, NF-κB and NLRP3 Pathways

“…Moreover, following overnight incubation of MGL1 −/− Mφ with IFN-γ, LPS or both, there was not a significant reduction in the number of intracellular parasites, as occurred in the WT Mφ. This activation deficiency of MGL1 −/− Mφ was accompanied by a remarkable downregulation of ROS and NO production, as well as by a reduction in the levels of IL-12 and TNF-α, which are important for controlling parasite infection and replication [44,45]. These observations suggest that MGL1 may recognize T. cruzi and favors a cross-talk between MGL1 signalling pathway and other important pathways for Mφ activation that helps to activate the oxidative burst.…”

Purinergic Antagonist Suramin Aggravates Myocarditis and Increases Mortality by Enhancing Parasitism, Inflammation, and Reactive Tissue Damage inTrypanosoma cruzi-Infected Mice

“…There is evidence that high parasite load is closely correlated with intense immunological polarization to a Th1 phenotype, which is paradoxically implicated in antitrypanosomal defense and cardiac damage [ 19 , 26 , 44 ]. So, although cell-mediated immunity and the Th1-phenotype are the main line of defense against T. cruzi [ 43 , 44 ], exacerbated leucocyte infiltration and the overproduction and extravasation of lysosomal hydrolases and reactive species (e.g., NO, H 2 O 2 , HClO, O 2 ·− , OH ·− , and ONOO ·− ) from the “respiratory burst” result in intense lipid, protein, and DNA damage in host cells [ 47 , 48 ]. Due to parasite persistence and continuous immunological activation, oxidative stress remains present throughout infection, generating more reactive molecular damage and sustained proinflammatory stimuli in a self-sustaining process [ 7 , 8 ].…”

“…However, a contrary effect was observed in our model. Thus, once the exacerbated immune response is linked to redox imbalance and intense cardiac reactive stress [ 47 , 48 ], by potentiating myocarditis, Sur can reinforce cardiac damage and mortality rates in infected mice.…”