Hypoxia in Leishmania major Skin Lesions Impairs the NO-Dependent Leishmanicidal Activity of Macrophages (original) (raw)
Related papers
Parasites & vectors, 2017
Cutaneous leishmaniasis (CL) is a vector-borne parasitic disease caused by protozoa of the genus Leishmania. In Morocco, CL is a public health problem mainly caused by Leishmania major and Leishmania tropica, which are responsible for zoonotic and anthroponotic CL, respectively. Macrophages are the primary cells infected by Leishmania parasites and their capacity to produce nitric oxide (NO) is of critical importance for parasite elimination. To our knowledge, the role of NO on autochthonous infections has never been investigated before. In this study, we evaluated in vitro the capacity of autochthonous primary dermotropic strains of L. major and L. tropica to modulate NO production by J774-macrophages and determine the sensitivity of both species to exogenous NO. The infectivity of the J774 cell line was analyzed by optical microscopy. NO production by macrophages was measured by the Griess method. The sensitivity to NO by the two strains was assessed by the MTT assay using NO dono...
Leishmania (L.) amazonensis-induced inhibition of nitric oxide synthesis in host macrophages
Microbes and Infection, 2002
Inhibition of lipopolysaccharide (LPS)-induced nitric oxide (NO) production was demonstrated in J774-G8 macrophages infected with Leishmania (L.) amazonensis promastigotes. The downmodulation of NO production observed in infected and LPS-stimulated J774-G8 cells correlated with a reduction in inducible nitric oxide synthase (iNOS) activity. Reduction in iNOS activity was not paralleled by decreased iNOS mRNA expression, suggesting that the parasite affects post-transcriptional events of NO synthesis. Supplementation with L-arginine or tetrahydrobiopterin did not increase NO production, suggesting that inhibition is not due to an insufficiency of substrate or co-factor. Treatment with anti-IL-10, anti-IL-4 or anti-TGF-neutralizing antibodies also failed to increase NO production, indicating that these cytokines are not involved in the observed parasite-induced inhibition of NO synthesis. However, treatment of the cultures with IFN-γ resulted in a marked increase in NO production by infected LPS-stimulated cells. These results show that although L.(L.) amazonensis infection inhibits iNOS activity and NO production by J774-G8 cells, activation by IFN-γ is capable of overriding the suppression of NO synthesis.
Iranian journal of parasitology
The present study was conducted to investigate the optimized timing for macrophages induction and nitric oxide (NO) production against invading Leishmania parasite. The present study examined the murine macrophage cell line, B10R, in three different states. In the first state, the cells were first infected with L. major and then treated with IFN-γ and LPS as stimulants. In the second state, the cells were infected after stimulation with IFN-γ and LPS. In the third state, the cells were only exposed to stimulants as controls. In all the three states, cell culture supernatants were collected at three points in time (6, 24 and 48 h) and the amount of NO production was measured using Griess assay. The treatment of macrophages with inducers prior to infection with stationary phase parasite led to the secretion of significant amounts of NO, particularly at early time points quit contrary to the cells infected with parasites prior to induction. The amount of NO produced by cells induced af...
Macrophage killing of Leishmania amazonensis amastigotes requires both nitric oxide and superoxide
The American journal of tropical medicine and hygiene, 2007
The requirements for effective and efficient intracellular killing of Leishmania amazonensis by activated macrophages are unknown. Despite resistance to the arginase inhibitor LOHA by intracellular L. amazonensis amastigotes, enhanced replication did not account for the relative resistance of this parasite to macrophage activation. Herein we report that the presence of both superoxide and nitric oxide is necessary for efficient killing of L. amazonensis amastigotes within LPS/IFN-gamma-activated bone marrow-derived macrophages generated from C3H mice. Addition of an extracellular signal-regulated kinase (ERK) inhibitor to L. amazonensis-infected macrophages increased the ability of these activated macrophages to kill L. amazonensis amastigotes. This enhanced macrophage killing through addition of ERK inhibitor was abrogated by inhibition of superoxide or iNOS, whereas inhibiting superoxide had no effect on the killing of L. major. These results suggest that ERK activation may modula...
Parasite Immunology, 2012
CBA mouse macrophages effectively control Leishmania major infection, yet are permissive to Leishmania amazonensis. It has been established that some Leishmania species are destroyed by reactive oxygen species (ROS). However, other species of Leishmania exhibit resistance to ROS or even down-modulate ROS production. We hypothesized that L. amazonensis-infected macrophages reduce ROS production soon after parasite-cell interaction. Employing a highly sensitive analysis technique based on chemiluminescence, the production of superoxide (O ÁÀ 2) and hydrogen peroxide (H 2 O 2) by L. majoror L. amazonensis-infected CBA macrophages were measured. L. major induces macrophages to release levels of O ÁÀ 2 3AE5 times higher than in uninfected cells. This O ÁÀ 2 production is partially dependent on NADPH oxidase (NOX) type 2. The level of accumulated H 2 O 2 is 20 times higher in L. major-than in L. amazonensis-infected cells. Furthermore, macrophages stimulated with L. amazonensis release amounts of ROS similar to uninfected cells. These findings support previous studies showing that CBA macrophages are effective in controlling L. major infection by a mechanism dependent on both O ÁÀ 2 production and H 2 O 2 generation. Furthermore, these data reinforce the notion that L. amazonensis survive inside CBA macrophages by reducing ROS production during the phagocytic process.
Late nitric oxide synthesis during cutaneous murine leishmaniasis
Free Radical Biology and Medicine, 1999
The cytotoxins produced by phagocytic cells lacking peroxidases such as macrophages remain elusive. To elucidate macrophage microbicidal mechanisms in vivo, we compared the lesion tissue responses of resistant (C57Bl/6) and susceptible (BALB/c) mice to Leishmania amazonensis infection. This comparison demonstrated that parasite control relied on lesion macrophage activation with inducible nitric oxide synthase expression (iNOS), nitric oxide synthesis, and extensive nitration of parasites inside macrophage phagolysosomes at an early infection stage. Nitration and iNOS expression were monitored by confocal microscopy; nitric oxide synthesis was monitored by EPR. The main macrophage nitrating agent was shown to be peroxynitrite derived because parasite nitration occurred in the virtual absence of polymorphonuclear cells (monitored as peroxidase activity) and was accompanied by protein hydroxylation (monitored as 3-hydroxytyrosine levels). In vitro studies confirmed that peroxynitrite is cytotoxic to parasites whereas nitric oxide is cytostatic. The results indicate that peroxynitrite is likely to be produced close to the parasites and most of it reacts with carbon dioxide to produce carbonate radical anion and nitrogen dioxide whose concerted action leads to parasite nitration. In parallel, some peroxynitrite decomposition to the hydroxyl radical should occur due to the detection of hydroxylated proteins in the healing tissues. Consequently, peroxynitrite and derived radicals are likely to be important macrophage-derived cytotoxins.
Cellular Immunology, 2019
Increasing attention is given to the finding that macrophages under hypoxia are capable of controlling infection by the intracellular protozoan parasite Leishmania amazonensis. The hypoxia-inducible factor (HIF)-1α has been shown to play an essential role in this enhanced innate immune response. Our study aimed to explore the HIF-1α-dependent mechanisms leading to reduced survival of the parasites residing in macrophages under low oxygen conditions. Hypoxia triggered (P < 0.01) NADPH oxidase 2 (Nox2) expression and reactive oxygen species (ROS) production in J774 macrophages upon 24-h infection with L. amazonensis. Furthermore, increased (P < 0.01) expression levels of HIF-1α and macrophage migration inhibitory factor (MIF) were detected in the infected cells grown at 3% oxygen tension. We found that either HIF-1α silencing, Nox2 inhibition or MIF antagonism caused a significant (P < 0.05) reversal of the improved leishmanicidal activity displayed by the hypoxic phagocytes. Taken together, our current results suggest that, under conditions of limited availability of oxygen, activation of the HIF-1α/MIF axis via Nox2/ROS induction promotes killing of L. amazonensis amastigotes by macrophages. Such protective mechanism might operate in L. amazonensis-infected tissues where low oxygen levels prevail.
Reactive Oxygen Species and Nitric Oxide in Cutaneous Leishmaniasis
Journal of Parasitology Research, 2012
Cutaneous leishmaniasis affects millions of people around the world. Several species of Leishmania infect mouse strains, and murine models closely reproduce the cutaneous lesions caused by the parasite in humans. Mouse models have enabled studies on the pathogenesis and effector mechanisms of host resistance to infection. Here, we review the role of nitric oxide (NO), reactive oxygen species (ROS), and peroxynitrite (ONOO − ) in the control of parasites by macrophages, which are both the host cells and the effector cells. We also discuss the role of neutrophil-derived oxygen and nitrogen reactive species during infection with Leishmania. We emphasize the role of these cells in the outcome of leishmaniasis early after infection, before the adaptive T h -cell immune response. the outcome of the disease [1]. Cutaneous leishmaniasis is caused by several species of the genus Leishmania, including L. major, L. tropica, L. aethiopica, L. mexicana, L. braziliensis, L. guyanensis, L. panamensis, L. peruviana, and L. amazonensis. The Leishmania genus is divided in two subgenera, Leishmania and Viannia. In the subgenus Leishmania, L. amazonensis, L. mexicana (complex L. mexicana), and L. major (complex L. major) are by far the most studied species that cause cutaneous leishmaniasis. The subgenus Viannia comprises two important species that cause cutaneous leishmaniasis, L. guyanensis (complex L. guyanensis) and L. braziliensis (complex L. braziliensis) .
Journal of Parasitology, 2000
Leishmaniasis is a parasitic disease that leads to chronic inflammation. Macrophages, depending on their activation state, are either hosts or killers of the parasites. Downregulation of nitric oxide (NO) synthesis by the parasite infecting the macrophages has been proposed to be an important evading mechanism based on in vitro studies. We confirmed inhibition of NO release by macrophages infected with Leishmania amazonensis in vitro. To examine the role of the parasite in regulating NO production in vivo, we monitored systemic NO levels elicited by challenging naive and L. amazonensis-infected BALB/c mice with lipopolysaccharide (LPS). Animals were challenged after 1, 2, 6, and 9 wk of infection. NO production was monitored by electron paramagnetic resonance spectroscopy as the levels of hemoglobin nitrosyl complexes (HbNO) present in the animal's blood. No significant differences in HbNO levels were observed between LPS-treated naive and inoculated mice at any time during infection. To control for increased macrophage numbers in infected mice, naive mice were injected with a macrophage cell line before LPS challenge; this treatment did not increase produced NO levels. The results argue against a major role for the parasite in downregulating NO production in vivo.