scholarly journals Inducible nitric-oxide synthase plays a minimal role in lymphocytic choriomeningitis virus-induced, T cell-mediated protective immunity and immunopathology

1999 ◽  
Vol 80 (11) ◽  
pp. 2997-3005 ◽  
Author(s):  
C. Bartholdy ◽  
A. Nansen ◽  
J. Erbo Christensen ◽  
O. Marker ◽  
A. Randrup Thomsen
Keyword(s):  
Nitric Oxide ◽  
T Cell ◽  
Lymphocytic Choriomeningitis ◽  
Wild Type ◽  
Cell Mediated Immune Response ◽  
Oxide Synthase ◽  
Deficient Mice ◽  
Lcmv Infection ◽  
Inducible Nitric Oxide

By using mice with a targetted disruption in the gene encoding inducible nitric-oxide synthase (iNOS), we have studied the role of nitric oxide (NO) in lymphocytic choriomeningitis virus (LCMV)-induced, T cell-mediated protective immunity and immunopathology. The afferent phase of the T cell-mediated immune response was found to be unaltered in iNOS-deficient mice compared with wild-type C57BL/6 mice, and LCMV- induced general immunosuppression was equally pronounced in both strains. In vivo analysis revealed identical kinetics of virus clearance, as well as unaltered clinical severity of systemic LCMV infection in both strains. Concerning the outcome of intracerebral infection, no significant differences were found between iNOS-deficient and wild-type mice in the number or composition of mononuclear cells found in the cerebrospinal fluid on day 6 post-infection. Likewise, NO did not influence the up-regulation of proinflammatory cytokine/chemokine genes significantly, nor did it influence the development of fatal meningitis. However, a reduced virus-specific delayed-type hypersensitivity reaction was observed in iNOS-deficient mice compared with both IFN-γ-deficient and wild-type mice. This might suggest a role of NO in regulating vascular reactivity in the context of T cell-mediated inflammation. In conclusion, these findings indicate a minimal role for iNOS/NO in the host response to LCMV. Except for a reduced local oedema in the knockout mice, iNOS/NO seems to be redundant in controlling both the afferent and efferent phases of the T cell-mediated immune response to LCMV infection.

Selected Contribution: Differential role of nitric oxide synthase isoforms in fever of different etiologies: studies using Nosgene-deficient mice

2003 ◽  
Vol 94 (6) ◽  
pp. 2534-2544 ◽  
Author(s):  
Wieslaw Kozak ◽  
Anna Kozak
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Corn Oil ◽  
Normal Male ◽  
Wild Type ◽  
Oxide Synthase ◽  
And Control ◽  
Nos Isoforms ◽  
Deficient Mice

Male C57BL/6J mice deficient in nitric oxide synthase (NOS) genes (knockout) and control (wild-type) mice were implanted intra-abdominally with battery-operated miniature biotelemeters (model VMFH MiniMitter, Sunriver, OR) to monitor changes in body temperature. Intravenous injection of lipopolysaccharide (LPS; 50 μg/kg) was used to trigger fever in response to systemic inflammation in mice. To induce a febrile response to localized inflammation, the mice were injected subcutaneously with pure turpentine oil (30 μl/animal) into the left hindlimb. Oral administration (gavage) of N G-monomethyl-l-arginine (l-NMMA) for 3 days (80 mg · kg−1 · day−1in corn oil) before injection of pyrogens was used to inhibit all three NOSs ( N G-monomethyl-d-arginine acetate salt and corn oil were used as control). In normal male C57BL/6J mice, l-NMMA inhibited the LPS-induced fever by ∼60%, whereas it augmented fever by ∼65% in mice injected with turpentine. Challenging the respective NOS knockout mice with LPS and with l-NMMA revealed that inducible NOS and neuronal NOS isoforms are responsible for the induction of fever to LPS, whereas endothelial NOS (eNOS) is not involved. In contrast, none of the NOS isoforms appeared to trigger fever to turpentine. Inhibition of eNOS, however, exacerbates fever in mice treated with l-NMMA and turpentine, indicating that eNOS participates in the antipyretic mechanism. These data support the hypothesis that nitric oxide is a regulator of fever. Its action differs, however, depending on the pyrogen used and the NOS isoform.

Parasite killing in murine malaria does not require nitric oxide production

Parasitology ◽  
1999 ◽  
Vol 118 (2) ◽  
pp. 139-143 ◽  
Author(s):  
N. FAVRE ◽  
B. RYFFEL ◽  
W. RUDIN
Keyword(s):  
Nitric Oxide ◽  
Blood Stage ◽  
No Production ◽  
Nos Inhibitor ◽  
Oxide Synthase ◽  
Deficient Mice ◽  
Stage Parasite ◽  
Blood Stage Malaria ◽  
Inducible Nitric Oxide

Nitric oxide (NO) production has been suggested to play a role as effector molecule in the control of the malarial infections. However, the roles of this molecule are debated. To assess whether blood-stage parasite killing is NO dependent, we investigated the course of blood-stage Plasmodium chabaudi chabaudi (Pcc) infections in inducible nitric oxide synthase (iNOS)-deficient mice. Parasitaemia, haematological alterations, and survival were not affected by the lack of iNOS. To exclude a role of NO produced by other NOS, controls included NO suppression by oral administration of aminoguanidine (AG), a NOS inhibitor. As in iNOS-deficient mice, no difference in the parasitaemia course, survival and haematological values was observed after AG treatment. Our results indicate that NO production is not required for protection against malaria in our murine experimental model. However, C57BL/6 mice treated with AG lost their resistance to Pcc infections, suggesting that the requirement for NO production for parasite killing in murine blood-stage malaria might be strain dependent.

scholarly journals Inducible nitric oxide synthase provides protection against injury-induced thrombosis in female mice

2011 ◽  
Vol 301 (2) ◽  
pp. H617-H624 ◽  
Author(s):  
Rita K. Upmacis ◽  
Hao Shen ◽  
Lea Esther S. Benguigui ◽  
Brian D. Lamon ◽  
Ruba S. Deeb ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Ex Vivo ◽  
Physiological Role ◽  
Thrombotic Occlusion ◽  
Female Mice ◽  
Eicosanoid Production ◽  
Oxide Synthase ◽  
Deficient Mice ◽  
Inducible Nitric Oxide

Nitric oxide (NO) is an important vasoactive molecule produced by three NO synthase (NOS) enzymes: neuronal (nNOS), inducible (iNOS), and endothelial NOS (eNOS). While eNOS contributes to blood vessel dilation that protects against the development of hypertension, iNOS has been primarily implicated as a disease-promoting isoform during atherogenesis. Despite this, iNOS may play a physiological role via the modulation of cyclooxygenase and thromboregulatory eicosanoid production. Herein, we examined the role of iNOS in a murine model of thrombosis. Blood flow was measured in carotid arteries of male and female wild-type (WT) and iNOS-deficient mice following ferric chloride-induced thrombosis. Female WT mice were more resistant to thrombotic occlusion than male counterparts but became more susceptible upon iNOS deletion. In contrast, male mice (with and without iNOS deletion) were equally susceptible to thrombosis. Deletion of iNOS was not associated with a change in the balance of thromboxane A2 (TxA2) or antithrombotic prostacyclin (PGI2). Compared with male counterparts, female WT mice exhibited increased urinary nitrite and nitrate levels and enhanced ex vivo induction of iNOS in hearts and aortas. Our findings suggest that iNOS-derived NO in female WT mice may attenuate the effects of vascular injury. Thus, although iNOS is detrimental during atherogenesis, physiological iNOS levels may contribute to providing protection against thrombotic occlusion, a phenomenon that may be enhanced in female mice.

scholarly journals Inducible Nitric Oxide Synthase Does Not Mediate Brain Damage after Transient Focal Cerebral Ischemia in Mice

2007 ◽  
Vol 28 (3) ◽  
pp. 526-539 ◽  
Author(s):  
Harald Prüss ◽  
Konstantin Prass ◽  
Leyli Ghaeni ◽  
Milan Milosevic ◽  
Claudia Muselmann ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Cerebral Ischemia ◽  
Infarct Size ◽  
Focal Cerebral Ischemia ◽  
Inos Mrna ◽  
Wild Type ◽  
Transient Focal Cerebral Ischemia ◽  
Oxide Synthase ◽  
Deficient Mice ◽  
Inducible Nitric Oxide

Nitric oxide produced by the inducible nitric oxide synthase (iNOS) is believed to participate in the pathogenic events after cerebral ischemia. In this study, we examined the expression of iNOS in the brain after transient focal cerebral ischemia in mice. We detected differential expression of exons 2 and 3 of iNOS mRNA (16-fold upregulation at 24 to 72 h after middle cerebral artery occlusion, MCAO) compared with exons 6 to 8, 12 to 14, 21 to 22, and 26 to 27 (2- to 5-fold upregulation after 72 and 96 h), which would be compatible with alternative splicing. Expression levels of iNOS mRNA were too low for detection by the Northern blot analysis. Using specific antibodies, we did not detect any iNOS immunoreactivity in the mouse brain 1 to 5 days after MCAO, although we detected iNOS immunoreactivity in the lungs of mice with stroke-associated pneumonia, and in mouse and rat dura mater after lipopolysaccharide administration. In chimeric iNOS-deficient mice transplanted with wild-type bone marrow (BM) cells expressing the green fluorescent protein (GFP) or in wild-type mice transplanted with GFP+ iNOS-deficient BM cells, no expression of iNOS was detected in GFP+ leukocytes invading the ischemic brain or in resident brain cells. Moreover, both experimental groups did not show any differences in infarct size. Analysis of three different strains of iNOS-deficient mice and wild-type controls confirmed that infarct size was independent of iNOS deletion, but strongly confounded by the genetic background of mouse strains. In conclusion, our data suggest that iNOS is not a universal mediator of brain damage after cerebral ischemia.

scholarly journals Contribution of Nitric Oxide Synthases 1, 2, and 3 to Airway Hyperresponsiveness and Inflammation in a Murine Model of Asthma

1999 ◽  
Vol 189 (10) ◽  
pp. 1621-1630 ◽  
Author(s):  
George T. De Sanctis ◽  
James A. MacLean ◽  
Kaoru Hamada ◽  
Sanjay Mehta ◽  
Jeremy A. Scott ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Allergic Asthma ◽  
Airway Hyperresponsiveness ◽  
Airway Responsiveness ◽  
Wild Type ◽  
Methacholine Challenge ◽  
Oxide Synthase ◽  
Nos Isoforms ◽  
Deficient Mice

Asthma is a chronic disease characterized by increased airway responsiveness and airway inflammation. The functional role of nitric oxide (NO) and the various nitric oxide synthase (NOS) isoforms in human asthma is controversial. To investigate the role of NO in an established model of allergic asthma, mice with targeted deletions of the three known isoforms of NOS (NOS1, 2, and 3) were studied. Although the inducible (NOS2) isoform was significantly upregulated in the lungs of ovalbumin (OVA)-sensitized and -challenged (OVA/OVA) wild-type (WT) mice and was undetectable in similarly treated NOS2-deficient mice, airway responsiveness was not significantly different between these groups. OVA/OVA endothelial (NOS3)-deficient mice were significantly more responsive to methacholine challenge compared with similarly treated NOS1 and NOS1&3-deficient mice. Airway responsiveness in OVA/OVA neuronal (NOS1)-deficient and neuronal/endothelial (NOS1&3) double-deficient mice was significantly less than that observed in similarly treated NOS2 and WT groups. These findings demonstrate an important function for the nNOS isoform in controlling the inducibility of airway hyperresponsiveness in this model of allergic asthma.

scholarly journals Gastric Helicobacter Infection Induces a Th2 Phenotype but Does Not Elevate Serum Cholesterol in Mice Lacking Inducible Nitric Oxide Synthase

2005 ◽  
Vol 73 (3) ◽  
pp. 1664-1670 ◽  
Author(s):  
Melanie Ihrig ◽  
Mark T. Whary ◽  
Charles A. Dangler ◽  
James G. Fox
Keyword(s):  
Nitric Oxide ◽  
Serum Cholesterol ◽  
Antibody Responses ◽  
Wild Type ◽  
Cholesterol Levels ◽  
Mucous Metaplasia ◽  
Glandular Atrophy ◽  
Oxide Synthase ◽  
Deficient Mice ◽  
Inducible Nitric Oxide

ABSTRACT Persistent Helicobacter felis infection in (C57BL/6 × 129SvEv)F1 mice induces chronic gastritis. Expression of inducible nitric oxide synthase (iNOS) is upregulated in response to Helicobacter infection. In this study, 20 10-week-old iNOS−/− mice and 20 wild-type [(C57BL/6 × 129SvEv)F1] mice were infected with H. felis by oral gavage and were assessed histologically and serologically at 32 weeks postinfection. Equal numbers of uninfected controls were sham inoculated. The mice were scored for severity of gastric inflammation, hyperplasia, glandular atrophy, and mucous metaplasia in the corpus and for the level of helicobacter colonization. The immunoglobulin G1 (IgG1), IgG2a, and IgG2c antibody responses to H. felis were determined. As a secondary measure, serum cholesterol levels were assessed. iNOS−/− mice have a propensity for increased serum cholesterol, and although controversial, several human epidemiologic studies have demonstrated an association between Helicobacter infection and several risk factors for cardiovascular disease, including elevated serum cholesterol. Nevertheless, no differences in serum cholesterol levels were observed between the H. felis-infected and -uninfected iNOS−/− mice in this study. The uninfected animals had minimal to no gastric pathology. The gastric pathology scores for the infected animals were reduced significantly in the iNOS-deficient mice relative to those for the wild-type mice (all P < 0.01). Helicobacter-infected iNOS−/− mice had chronic lymphoid infiltration and negligible to mild glandular atrophy and mucous metaplasia in the fundic mucosa, while H. felis-infected wild-type mice had severe atrophic and metaplastic mucosal changes. The atrophic gastritis in the infected wild-type mice, particularly the female mice, was also accompanied by greater granulocytic infiltration, antral hyperplasia, and diminished antral colonization, unlike that in the infected iNOS−/− mice. iNOS−/− mice developed significantly lower Th1-associated IgG2c antibody responses to H. felis (P < 0.0003); the Th2-associated IgG1 responses were similar (P = 0.09), suggesting a greater effect of the iNOS defect on Th1 responses. H. felis colonization was significantly greater in the iNOS-deficient mice. These findings are indicative of an impaired Th1 component of the H. felis-induced inflammatory response when the influence of iNOS is removed.

scholarly journals Novel role of the nitrite transporter NirC in Salmonella pathogenesis: SPI2-dependent suppression of inducible nitric oxide synthase in activated macrophages

Microbiology ◽  
2009 ◽  
Vol 155 (8) ◽  
pp. 2476-2489 ◽  
Author(s):  
Priyanka Das ◽  
Amit Lahiri ◽  
Ayan Lahiri ◽  
Dipshikha Chakravortty
Keyword(s):  
Nitric Oxide ◽  
Type Strain ◽  
Wild Type Strain ◽  
No Production ◽  
Activated Macrophages ◽  
Wild Type ◽  
Raw264.7 Macrophages ◽  
Oxide Synthase ◽  
Inducible Nitric Oxide

Activation of macrophages by interferon gamma (IFN-γ) and the subsequent production of nitric oxide (NO) are critical for the host defence against Salmonella enterica serovar Typhimurium infection. We report here the inhibition of IFN-γ-induced NO production in RAW264.7 macrophages infected with wild-type Salmonella. This phenomenon was shown to be dependent on the nirC gene, which encodes a potential nitrite transporter. We observed a higher NO output from IFN-γ-treated macrophages infected with a nirC mutant of Salmonella. The nirC mutant also showed significantly decreased intracellular proliferation in a NO-dependent manner in activated RAW264.7 macrophages and in liver, spleen and secondary lymph nodes of mice, which was restored by complementing the gene in trans. Under acidified nitrite stress, a twofold more pronounced NO-mediated repression of SPI2 was observed in the nirC knockout strain compared to the wild-type. This enhanced SPI2 repression in the nirC knockout led to a higher level of STAT-1 phosphorylation and inducible nitric oxide synthase (iNOS) expression than seen with the wild-type strain. In iNOS knockout mice, the organ load of the nirC knockout strain was similar to that of the wild-type strain, indicating that the mutant is exclusively sensitive to the host nitrosative stress. Taken together, these results reveal that intracellular Salmonella evade killing in activated macrophages by downregulating IFN-γ-induced NO production, and they highlight the critical role of nirC as a virulence gene.

scholarly journals Regulation of phagosomal iron release from murine macrophages by nitric oxide

2002 ◽  
Vol 365 (1) ◽  
pp. 127-132 ◽  
Author(s):  
Victoriano MULERO ◽  
Xiao-qing WEI ◽  
Foo Y. LIEW ◽  
Jeremy H. BROCK
Keyword(s):  
Nitric Oxide ◽  
Bone Marrow ◽  
Interferon Γ ◽  
Iron Release ◽  
Wild Type ◽  
Peripheral Tissues ◽  
Oxide Synthase ◽  
Deficient Mice ◽  
Lps Treatment

The role of NO in macrophage iron turnover was studied in macrophages from inducible nitric oxide synthase (iNOS)-deficient mice. Interferon γ/lipopolysaccharide (IFNγ/LPS)-activated bone marrow-derived macrophages from iNOS-deficient mice, following phagocytosis of 59Fe-labelled transferrin—anti-transferrin immune complexes, showed reduced iron release compared with cells from wild-type iNOS littermates. Uptake of the complexes by macrophages was similar in iNOS-deficient and wild-type mice. Ferritin was up-regulated by IFNγ/LPS treatment, but NO exercised a modest opposing down-regulatory effect. No effect of iNOS deficiency was seen when iron was taken up from iron citrate, which enters via a non-phagocytic route. These results suggest that NO plays a key role in regulating iron turnover in macrophages acquiring iron by phagocytosis of erythrocytes or cell debris, and thus the supply to peripheral tissues, such as to the bone marrow for erythropoiesis.

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