scholarly journals Inducible Nitric Oxide Is Essential for Host Control of Persistent but Not Acute Infection with the Intracellular Pathogen Toxoplasma gondii

1997 ◽  
Vol 185 (7) ◽  
pp. 1261-1274 ◽  
Author(s):  
Tanya M. Scharton-Kersten ◽  
George Yap ◽  
Jeanne Magram ◽  
Alan Sher
Keyword(s):  
Nitric Oxide ◽  
Toxoplasma Gondii ◽  
Acute Infection ◽  
Protective Role ◽  
Major Mechanism ◽  
Reactive Nitrogen Intermediates ◽  
Ifn Γ ◽  
Inos Knockout Mice

The induction by IFN-γ of reactive nitrogen intermediates has been postulated as a major mechanism of host resistance to intracellular pathogens. To formally test this hypothesis in vivo, the course of Toxoplasma gondii infection was assessed in nitric oxide synthase (iNOS)−/− mice. As expected, macrophages from these animals displayed defective microbicidal activity against the parasite in vitro. Nevertheless, in contrast to IFN-γ−/− or IL-12 p40−/− animals, iNOSdeficient mice survived acute infection and controlled parasite growth at the site of inoculation. This early resistance was ablated by neutralization of IFN-γ or IL-12 in vivo and markedly diminished by depletion of neutrophils, demonstrating the existence of previously unappreciated NO independent mechanisms operating against the parasite during early infection. By 3-4 wk post infection, however, iNOS knockout mice did succumb to T. gondii. At that stage parasite expansion and pathology were evident in the central nervous system but not the periphery suggesting that the protective role of nitric oxide against this intracellular infection is tissue specific rather than systemic.

scholarly journals p47 GTPases Regulate Toxoplasma gondii Survival in Activated Macrophages

2005 ◽  
Vol 73 (6) ◽  
pp. 3278-3286 ◽  
Author(s):  
Barbara A. Butcher ◽  
Robert I. Greene ◽  
Stanley C. Henry ◽  
Kimberly L. Annecharico ◽  
J. Brice Weinberg ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Acute Infection ◽  
Host Cells ◽  
Intracellular Growth ◽  
Latex Beads ◽  
Cellular Factors ◽  
Ifn Γ ◽  
Normal Inhibition

ABSTRACT The cytokine gamma interferon (IFN-γ) is critical for resistance to Toxoplasma gondii. IFN-γ strongly activates macrophages and nonphagocytic host cells to limit intracellular growth of T. gondii; however, the cellular factors that are required for this effect are largely unknown. We have shown previously that IGTP and LRG-47, members of the IFN-γ-regulated family of p47 GTPases, are required for resistance to acute T. gondii infections in vivo. In contrast, IRG-47, another member of this family, is not required. In the present work, we addressed whether these GTPases are required for IFN-γ-induced suppression of T. gondii growth in macrophages in vitro. Bone marrow macrophages that lacked IGTP or LRG-47 displayed greatly attenuated IFN-γ-induced inhibition of T. gondii growth, while macrophages that lacked IRG-47 displayed normal inhibition. Thus, the ability of the p47 GTPases to limit acute infection in vivo correlated with their ability to suppress intracellular growth in macrophages in vitro. Using confocal microscopy and sucrose density fractionation, we demonstrated that IGTP largely colocalizes with endoplasmic reticulum markers, while LRG-47 was mainly restricted to the Golgi. Although both IGTP and LRG-47 localized to vacuoles containing latex beads, neither protein localized to vacuoles containing live T. gondii. These results suggest that IGTP and LRG-47 are able to regulate host resistance to acute T. gondii infections through their ability to inhibit parasite growth within the macrophage.

scholarly journals The Intracellular Environment of Human Macrophages That Produce Nitric Oxide Promotes Growth of Mycobacteria

2013 ◽  
Vol 81 (9) ◽  
pp. 3198-3209 ◽  
Author(s):  
Joo-Yong Jung ◽  
Ranjna Madan-Lala ◽  
Maria Georgieva ◽  
Jyothi Rengarajan ◽  
Charles D. Sohaskey ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Protective Role ◽  
Human Macrophage ◽  
No Production ◽  
Content Type ◽  
Human Macrophages ◽  
Enhanced Expression ◽  
Reactive Nitrogen Intermediates ◽  
Ifn Γ

ABSTRACTNitric oxide (NO) is a diffusible radical gas produced from the activity of nitric oxide synthase (NOS). NOS activity in murine macrophages has a protective role against mycobacteria through generation of reactive nitrogen intermediates (RNIs). However, the production of NO by human macrophages has remained unclear due to the lack of sensitive reagents to detect NO directly. The purpose of this study was to investigate NO production and the consequence to mycobacteria in primary human macrophages. We found thatMycobacterium bovisBCG orMycobacterium tuberculosisinfection of human macrophages induced expression of NOS2 and NOS3 that resulted in detectable production of NO. Treatment with gamma interferon (IFN-γ),l-arginine, and tetrahydrobiopterin enhanced expression of NOS2 and NOS3 isoforms, as well as NO production. Both of these enzymes were shown to contribute to NO production. The maximal level of NO produced by human macrophages was not bactericidal or bacteriostatic toM. tuberculosisor BCG. The number of viable mycobacteria was increased in macrophages that produced NO, and this requires expression of nitrate reductase. AnnarGmutant ofM. tuberculosispersisted but was unable to grow in human macrophages. Taken together, these data (i) enhance our understanding of primary human macrophage potential to produce NO, (ii) demonstrate that the level of RNIs produced in response to IFN-γin vitrois not sufficient to limit intracellular mycobacterial growth, and (iii) suggest that mycobacteria may use RNIs to enhance their survival in human macrophages.

scholarly journals The Function of Gamma Interferon-Inducible GTP-Binding Protein IGTP in Host Resistance to Toxoplasma gondii Is Stat1 Dependent and Requires Expression in Both Hematopoietic and Nonhematopoietic Cellular Compartments

2002 ◽  
Vol 70 (12) ◽  
pp. 6933-6939 ◽  
Author(s):  
Carmen M. Collazo ◽  
George S. Yap ◽  
Sara Hieny ◽  
Patricia Caspar ◽  
Carl G. Feng ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Toxoplasma Gondii ◽  
Host Resistance ◽  
Chronic Infection ◽  
Acute Infection ◽  
Gamma Interferon ◽  
Ifn Γ ◽  
Bone Marrow Chimeras

ABSTRACT IGTP is a member of the 47-kDa family of gamma interferon (IFN-γ)-induced GTPases. We have previously shown that IGTP is critical for host resistance to Toxoplasma gondii infection. In the present study, we demonstrate that T. gondii-induced IGTP expression in vivo and IFN-γ-driven synthesis of the protein in vitro are dependent on Stat1. Consistent with this observation, Stat1-deficient animals succumbed to T. gondii infection with the same rapid kinetics as IGTP−/− mice. To ascertain the cellular levels at which IGTP functions in host control of acute infection, we constructed reciprocal bone marrow chimeras between IGTP-deficient and wild-type mice. Resistance to infection was observed only when IGTP was present in both hematopoietic and nonhematopoietic compartments. To assess the possible contribution of IGTP to the maintenance of parasite latency, partial chemotherapy was used to allow the establishment of chronic infection in IGTP-deficient animals. Upon cessation of drug treatment, these animals showed delayed mortality compared with similarly infected and treated IFN-γ-deficient or inducible nitric oxide synthase-deficient mice, which succumbed rapidly. Parallel experiments performed with drug-treated bone marrow chimeras supported a role for the hematopoietic compartment in this NO-dependent, IGTP-independent control of chronic infection. Taken together, our findings demonstrate that host resistance mediated by IGTP is a Stat1-induced function which in the case of T. gondii acts predominantly to restrict acute as opposed to chronic infection. This effector mechanism requires expression of IGTP in cells of both hematopoietic and nonhematopoietic origin. In contrast, in latent infection, hematopoietically derived cells mediate resistance by means of a largely NO-dependent pathway.

MyD88-Dependent Glucose Restriction and Itaconate Production Control Brucella Infection

2021 ◽  
Author(s):  
Carolyn A. Lacey ◽  
Bárbara Ponzilacqua-Silva ◽  
Catherine A. Chambers ◽  
Alexis S. Dadelahi ◽  
Jerod A. Skyberg
Keyword(s):  
Glucose Transporter ◽  
Production Control ◽  
Brucella Melitensis ◽  
Underlying Mechanism ◽  
Protective Role ◽  
Ifn Γ ◽  
Glucose Restriction ◽  
Myd88 Signaling

Brucellosis is one of the most common global zoonoses and is caused by facultative intracellular bacteria of the genus Brucella . Numerous studies have found that MyD88 signaling contributes to protection against Brucella , however the underlying mechanism has not been entirely defined. Here we show that MyD88 signaling in hematopoietic cells contributes both to inflammation and to control of Brucella melitensis infection in vivo . While the protective role of MyD88 in Brucella infection has often been attributed to promotion of IFN-γ production, we found that MyD88 signaling restricts host colonization by B. melitensis even in the absence of IFN-γ. In vitro , we show that MyD88 promotes macrophage glycolysis in response to B. melitensis . Interestingly, a B. melitensis mutant lacking the glucose transporter, GluP, was more highly attenuated in MyD88 -/- than in WT mice, suggesting MyD88 deficiency results in an increased availability of glucose in vivo which Brucella can exploit via GluP. Metabolite profiling of macrophages identified several metabolites regulated by MyD88 in response to B. melitensis , including itaconate. Subsequently, we found that itaconate has antibacterial effects against Brucella and also regulates the production of pro-inflammatory cytokines in B. melitensis -infected macrophages. Mice lacking the ability to produce itaconate were also more susceptible to B. melitensis in vivo . Collectively, our findings indicate that MyD88-dependent changes in host metabolism contribute to control of Brucella infection.

scholarly journals Cooperation between Reactive Oxygen and Nitrogen Intermediates in Killing of Rhodococcus equi by Activated Macrophages

2000 ◽  
Vol 68 (6) ◽  
pp. 3587-3593 ◽  
Author(s):  
Patricia A. Darrah ◽  
Mary K. Hondalus ◽  
Quiping Chen ◽  
Harry Ischiropoulos ◽  
David M. Mosser
Keyword(s):  
Nitric Oxide ◽  
Prolonged Exposure ◽  
Rhodococcus Equi ◽  
Activated Macrophages ◽  
Intracellular Killing ◽  
Oxygen Intermediates ◽  
Bacterial Killing ◽  
Ifn Γ

ABSTRACT Rhodococcus equi is a facultative intracellular bacterium of macrophages which can infect immunocompromised humans and young horses. In the present study, we examine the mechanism of host defense against R. equi by using a murine model. We show that bacterial killing is dependent upon the presence of gamma interferon (IFN-γ), which activates macrophages to produce reactive nitrogen and oxygen intermediates. These two radicals combine to form peroxynitrite (ONOO−), which kills R. equi. Mice deficient in the production of either the high-output nitric oxide pathway (iNOS−/−) or the oxidative burst (gp91 phox−/− ) are more susceptible to lethalR. equi infection and display higher bacterial burdens in their livers, spleens, and lungs than wild-type mice. These in vivo observations, which implicate both nitric oxide (NO) and superoxide (O2 −) in bacterial killing, were reexamined in cell-free radical-generating assays. In these assays, R. equi remains fully viable following prolonged exposure to high concentrations of either nitric oxide or superoxide, indicating that neither compound is sufficient to mediate bacterial killing. In contrast, brief exposure of bacteria to ONOO− efficiently kills virulent R. equi. The intracellular killing of bacteria in vitro by activated macrophages correlated with the production of ONOO− in situ. Inhibition of nitric oxide production by activated macrophages by usingN G-monomethyl-l-arginine blocks their production of ONOO− and weakens their ability to control rhodococcal replication. These studies indicate that peroxynitrite mediates the intracellular killing of R. equiby IFN-γ-activated macrophages.

scholarly journals Development of a System To Study CD4+-T-Cell Responses to Transgenic Ovalbumin-Expressing Toxoplasma gondii during Toxoplasmosis

2004 ◽  
Vol 72 (12) ◽  
pp. 7240-7246 ◽  
Author(s):  
Marion Pepper ◽  
Florence Dzierszinski ◽  
Amy Crawford ◽  
Christopher A. Hunter ◽  
David Roos
Keyword(s):  
T Cells ◽  
T Cell ◽  
Toxoplasma Gondii ◽  
T Cell Responses ◽  
Cell Receptor ◽  
In Vivo Studies ◽  
Cell Responses ◽  
Ifn Γ

ABSTRACT The study of the immune response to Toxoplasma gondii has provided numerous insights into the role of T cells in resistance to intracellular infections. However, the complexity of this eukaryote pathogen has made it difficult to characterize immunodominant epitopes that would allow the identification of T cells with a known specificity for parasite antigens. As a consequence, analysis of T-cell responses to T. gondii has been based on characterization of the percentage of T cells that express an activated phenotype during infection and on the ability of these cells to produce cytokines in response to complex mixtures of parasite antigens. In order to study specific CD4+ T cells responses to T. gondii, recombinant parasites that express a truncated ovalbumin (OVA) protein, in either a cytosolic or a secreted form, were engineered. In vitro and in vivo studies reveal that transgenic parasites expressing secreted OVA are able to stimulate T-cell receptor-transgenic OVA-specific CD4+ T cells to proliferate, express an activated phenotype, and produce gamma interferon (IFN-γ). Furthermore, the adoptive transfer of OVA-specific T cells into IFN-γ−/− mice provided enhanced protection against infection with the OVA-transgenic (but not parental) parasites. Together, these studies establish the utility of this transgenic system to study CD4+-T-cell responses during toxoplasmosis.

Role of IFN-γ and IL-2 in rat lung epithelial cell migration and apoptosis after oxidant injury

2004 ◽  
Vol 286 (1) ◽  
pp. L4-L14 ◽  
Author(s):  
Olivier Lesur ◽  
Marcel Brisebois ◽  
Alexandre Thibodeau ◽  
Frédéric Chagnon ◽  
Denis Lane ◽  
...  
Keyword(s):  
Caspase 3 ◽  
Primary Cultures ◽  
Fold Increase ◽  
Protective Role ◽  
Scatchard Analysis ◽  
Membrane Expression ◽  
Extracellular Signal ◽  
Ifn Γ

In the present study, IFN-γ exposure to primary cultures of rat type II epithelial cells (TIIP) upregulated membrane expression of the common γ-chain of the IL-2 receptor (∼2.5- to 4-fold increase) and redistributed receptor affinity in TIIP, as assessed by Western blot, cell, and tissue histochemistry and Scatchard analysis. As for restitution processes of the lung epithelium, functionality of IL-2R on TIIP was conditional to IFN-γ exposure: 1) IFN-γ priming promoted a fivefold increase of IL-2-driven TIIP locomotion ( P < 0.05 vs. control at 100 U/ml) and 2) IFN-γ coincubation with IL-2 reduced bleomycin-induced TIIP apoptosis in vitro by 25% (caspase-3 activity) and by ∼70% (TdT-mediated dUTP nick end labeling/4′,6′-diamidino-2-phenylindole assay) as well as in vivo by ∼90% (caspase-3 activity; P < 0.05 vs. control). Sustained p42/44 extracellular signal-regulated kinase activity played a protective role in this process, whereas specific inhibition by PD-98059 (50 μM) significantly reversed bleomycin-induced TIIP apoptosis ( P < 0.05 vs. control). From these in vitro and in vivo data, it is proposed that combinations of IFN-γ and IL-2 can drive repair activity of TIIP by stimulating migration and preventing programmed cell death, both of which are speculated to be very fast restitution events after oxidant-induced acute lung injury.

A Uracil Auxotroph Toxoplasma gondii Exerting Immunomodulation to Inhibit Breast Cancer Growth and Metastasis

2021 ◽  
Author(s):  
Li-Qing Xu ◽  
Li-Jie Yao ◽  
Dan Jiang ◽  
Min Chen ◽  
Wen-Zhong Liao ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Toxoplasma Gondii ◽  
Tumor Growth ◽  
Lung Metastasis ◽  
Tumor Bearing ◽  
Uracil Auxotroph ◽  
Ifn Γ

Abstract Background: Breast cancer is the most common cause of cancer-related death among women, and patients with triple-negative breast cancer (TNBC) have poor prognosis, so it is necessary to develop new effective therapies urgently. Recent studies have demonstrated that uracil auxotroph Toxoplasma gondii vaccine displays antitumor effects. Here, we examined the immunotherapy effects of an attenuated uracil auxotroph strain of T. gondii against 4T1 murine breast cancer.Methods: We constructed a uracil auxotroph strain, the orotidine 5′-monophosphate decarboxylase gene deleted strain of T. gondii (RH-Δompdc) with the CRISPR/Cas9 technology. Its virulence in vitro and in vivo was determined by parasite replication assay, plaque assay, the parasite burden detection in mice peritoneal fluids and the survival analysis of T. gondii infection mice. Its immune modulation ability was evaluated by cytokines detection. Its antitumor effect was evaluated after its in situ inoculation to 4T1 tumors in mouse model, the tumor volume was measured, the 4T1 lung metastasis was detected by H&E and Ki67 antibody staining, and the cytokines levels were measured by ELISA.Results: RH-Δompdc strain could proliferate normally with uracil supplement, however, it was unable to propagate without uracil and in vivo, which implicated that it is avirulent to the hosts. This mutant showed vaccine characteristics that it could induce intense immune responses both in vitro and in vivo by boosting the expression of inflammatory cytokines significantly. RH-Δompdc in situ inoculation to the 4T1 tumors in mice could inhibit the tumor growth, reduce the lung metastasis, promote the survival of the tumor-bearing mice, and also increase the secretion of Th1 cytokines IL-12 and IFN-γ both in serum and in the tumor microenvironment (TME). Conclusion: The uracil auxotroph RH-Δompdc inoculation to the 4T1 tumors stimulated the anti-infection and antitumor immunity in mice, resulted in the inhibition of tumor growth and metastasis, the promotion in survival of the tumor-bearing mice, and the increasing secretion of IL-12 and IFN-γ both in serum and in the TME. Our findings implied that the immunomodulation resulted by RH-Δompdc could be a potential antitumor strategy.

scholarly journals Crucial Role of Interferon Consensus Sequence Binding Protein, but neither of Interferon Regulatory Factor 1 nor of Nitric Oxide Synthesis for Protection Against Murine Listeriosis

1997 ◽  
Vol 185 (5) ◽  
pp. 921-932 ◽  
Author(s):  
Thomas Fehr ◽  
Gabriele Schoedon ◽  
Bernhard Odermatt ◽  
Thomas Holtschke ◽  
Markus Schneemann ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Binding Protein ◽  
Consensus Sequence ◽  
Interferon Regulatory Factor ◽  
Regulatory Factor ◽  
Oxygen Intermediates ◽  
Ifn Γ ◽  
Effector Mechanisms

Listeria monocytogenes is widely used as a model to study immune responses against intracellular bacteria. It has been shown that neutrophils and macrophages play an important role to restrict bacterial replication in the early phase of primary infection in mice, and that the cytokines interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) are essential for protection. However, the involved signaling pathways and effector mechanisms are still poorly understood. This study investigated mouse strains deficient for the IFN-dependent transcription factors interferon consensus sequence binding protein (ICSBP), interferon regulatory factor (IRF)1 or 2 for their capacity to eliminate Listeria in vivo and in vitro and for production of inducible reactive nitrogen intermediates (RNI) or reactive oxygen intermediates (ROI) in macrophages. ICSBP−/− and to a lesser degree also IRF2−/− mice were highly susceptible to Listeria infection. This correlated with impaired elimination of Listeria from infected peritoneal macrophage (PEM) cultures stimulated with IFN-γ in vitro; in addition these cultures showed reduced and delayed oxidative burst upon IFN-γ stimulation, whereas nitric oxide production was normal. In contrast, mice deficient for IRF1 were not able to produce nitric oxide, but they efficiently controlled Listeria in vivo and in vitro. These results indicate that (a) the ICSBP/IRF2 complex is essential for IFN-γ–mediated protection against Listeria and that (b) ROI together with additional still unknown effector mechanisms may be responsible for the anti-Listeria activity of macrophages, whereas IRF1-induced RNI are not limiting.

scholarly journals Expression of Indoleamine 2,3-Dioxygenase, Tryptophan Degradation, and Kynurenine Formation during In Vivo Infection with Toxoplasma gondii: Induction by Endogenous Gamma Interferon and Requirement of Interferon Regulatory Factor 1

2002 ◽  
Vol 70 (2) ◽  
pp. 859-868 ◽  
Author(s):  
Neide M. Silva ◽  
Cibele V. Rodrigues ◽  
Marcelo M. Santoro ◽  
Luiz F. L. Reis ◽  
Jacqueline I. Alvarez-Leite ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Mrna Expression ◽  
Metabolic Pathway ◽  
Acute Infection ◽  
Regulatory Factor ◽  
Indoleamine 2,3 Dioxygenase ◽  
Tryptophan Degradation ◽  
Ifn Γ ◽  
Oxide Synthase

ABSTRACT The induction of indoleamine 2,3-dioxygenase (INDO) expression and the tryptophan (Trp)-kynurenine (Kyn) metabolic pathway during in vivo infection with Toxoplasma gondii was investigated. Decreased levels of Trp and increased formation of Kyn were observed in the lungs, brain, and serum from mice infected with T. gondii. Maximal INDO mRNA expression and enzyme activity were detected in the lungs at 10 to 20 days postinfection. Further, the induction of INDO mRNA expression, Trp degradation and Kyn formation were completely absent in tissues from mice deficient in IFN-γ (IFN-γ−/−) or IFN regulatory factor -1 (IRF-1−/−). These findings indicate the important role of endogenous IFN-γ and IRF-1 in the in vivo induction of the Trp-Kyn metabolic pathway during acute infection with T. gondii. In contrast, expression of INDO mRNA and its activity was preserved in the tissues of TNF-receptor p55- or inducible nitric oxide synthase-deficient mice infected with T. gondii. Together with the results showing the extreme susceptibility of the IFN-γ−/− and the IRF-1−/− mice to infection with T. gondii, our results indicate a possible involvement of INDO and Trp degradation in host resistance to early infection with this parasite.

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