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Title: Exposure to diesel exhaust up-regulates iNOS expression in ApoE knockout mice

Abstract

Traffic related particulate matter air pollution is a risk factor for cardiovascular events; however, the biological mechanisms are unclear. We hypothesize that diesel exhaust (DE) inhalation induces up-regulation of inducible nitric oxide synthase (iNOS), which is known to contribute to vascular dysfunction, progression of atherosclerosis and ultimately cardiovascular morbidity and mortality. Methods: ApoE knockout mice (30-week) were exposed to DE (at 200 {mu}g/m{sup 3} of particulate matter) or filtered-air (control) for 7 weeks (6 h/day, 5 days/week). iNOS expression in the blood vessels and heart was evaluated by immunohistochemistry and western blotting analysis. To examine iNOS activity, thoracic aortae were mounted in a wire myograph, and vasoconstriction stimulated by phenylephrine (PE) was measured with and without the presence of the specific inhibitor for iNOS (1400 W). NF-{kappa}B (p65) activity was examined by ELISA. The mRNA expression of iNOS and NF-{kappa}B (p65) was determined by real-time PCR. Results: DE exposure significantly enhanced iNOS expression in the thoracic aorta (4-fold) and heart (1.5 fold). DE exposure significantly attenuated PE-stimulated vasoconstriction by {approx} 20%, which was partly reversed by 1400 W. The mRNA expression of iNOS and NF-{kappa}B was significantly augmented after DE exposure. NF-{kappa}B activity was enhanced 2-fold after DE inhalation, andmore » the augmented NF-{kappa}B activity was positively correlated with iNOS expression (R{sup 2} = 0.5998). Conclusions: We show that exposure to DE increases iNOS expression and activity possibly via NF-{kappa}B-mediated pathway. We suspect that DE exposure-caused up-regulation of iNOS contributes to vascular dysfunction and atherogenesis, which could ultimately lead to urban air pollution-associated cardiovascular morbidity and mortality. - Highlights: > Exposed ApoE knockout mice (30-week) to diesel exhaust (DE) for 7 weeks. > Examine iNOS expression and activity in the blood vessels and heart. > DE exposure enhanced iNOS protein and mRNA expression in the aorta and heart. > iNOS activity was also increased after DE exposure. > This up-regulation of iNOS may contribute to vascular dysfunction and atherogenesis.« less

Authors:
 [1];  [2];  [3]; ; ;  [4];  [1];  [3]
  1. Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, BC (Canada)
  2. (Canada)
  3. James Hogg Research Centre, Providence Heart and Lung Institute, St. Paul's Hospital, University of British Columbia, Vancouver, BC (Canada)
  4. Department of Occupational and Environmental Health, University of Washington, Seattle, WA (United States)
Publication Date:
OSTI Identifier:
21587826
Resource Type:
Journal Article
Resource Relation:
Journal Name: Toxicology and Applied Pharmacology; Journal Volume: 255; Journal Issue: 2; Other Information: DOI: 10.1016/j.taap.2011.06.013; PII: S0041-008X(11)00235-3; Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; AIR POLLUTION; AORTA; ARTERIOSCLEROSIS; ENZYME IMMUNOASSAY; HAZARDS; HEART; HYPOXANTHINE PHOSPHORIBOSYLTRANSFERASE; INHALATION; KNOCK-OUT REACTIONS; LEUKOCYTES; LIPOPROTEINS; MACROPHAGES; MESSENGER-RNA; MICE; MORTALITY; NITRIC OXIDE; POLYMERASE CHAIN REACTION; VASOCONSTRICTION; ANIMAL CELLS; ANIMALS; ARTERIES; BIOASSAY; BIOLOGICAL MATERIALS; BLOOD; BLOOD CELLS; BLOOD VESSELS; BODY; BODY FLUIDS; CARDIOVASCULAR DISEASES; CARDIOVASCULAR SYSTEM; CHALCOGENIDES; CONNECTIVE TISSUE CELLS; DIRECT REACTIONS; DISEASES; ENZYMES; GENE AMPLIFICATION; GLYCOSYL TRANSFERASES; IMMUNOASSAY; INTAKE; LIPIDS; MAMMALS; MATERIALS; NITROGEN COMPOUNDS; NITROGEN OXIDES; NUCLEAR REACTIONS; NUCLEIC ACIDS; ORGANIC COMPOUNDS; ORGANS; OXIDES; OXYGEN COMPOUNDS; PENTOSYL TRANSFERASES; PHAGOCYTES; POLLUTION; PROTEINS; RNA; RODENTS; SOMATIC CELLS; TRANSFERASES; VASCULAR DISEASES; VERTEBRATES

Citation Formats

Bai Ni, James Hogg Research Centre, Providence Heart and Lung Institute, St. Paul's Hospital, University of British Columbia, Vancouver, BC, Kido, Takashi, Kavanagh, Terrance J., Kaufman, Joel D., Rosenfeld, Michael E., Breemen, Cornelis van, and Eeden, Stephan F. van, E-mail: Stephan.vanEeden@hli.ubc.ca. Exposure to diesel exhaust up-regulates iNOS expression in ApoE knockout mice. United States: N. p., 2011. Web. doi:10.1016/j.taap.2011.06.013.
Bai Ni, James Hogg Research Centre, Providence Heart and Lung Institute, St. Paul's Hospital, University of British Columbia, Vancouver, BC, Kido, Takashi, Kavanagh, Terrance J., Kaufman, Joel D., Rosenfeld, Michael E., Breemen, Cornelis van, & Eeden, Stephan F. van, E-mail: Stephan.vanEeden@hli.ubc.ca. Exposure to diesel exhaust up-regulates iNOS expression in ApoE knockout mice. United States. doi:10.1016/j.taap.2011.06.013.
Bai Ni, James Hogg Research Centre, Providence Heart and Lung Institute, St. Paul's Hospital, University of British Columbia, Vancouver, BC, Kido, Takashi, Kavanagh, Terrance J., Kaufman, Joel D., Rosenfeld, Michael E., Breemen, Cornelis van, and Eeden, Stephan F. van, E-mail: Stephan.vanEeden@hli.ubc.ca. Thu . "Exposure to diesel exhaust up-regulates iNOS expression in ApoE knockout mice". United States. doi:10.1016/j.taap.2011.06.013.
@article{osti_21587826,
title = {Exposure to diesel exhaust up-regulates iNOS expression in ApoE knockout mice},
author = {Bai Ni and James Hogg Research Centre, Providence Heart and Lung Institute, St. Paul's Hospital, University of British Columbia, Vancouver, BC and Kido, Takashi and Kavanagh, Terrance J. and Kaufman, Joel D. and Rosenfeld, Michael E. and Breemen, Cornelis van and Eeden, Stephan F. van, E-mail: Stephan.vanEeden@hli.ubc.ca},
abstractNote = {Traffic related particulate matter air pollution is a risk factor for cardiovascular events; however, the biological mechanisms are unclear. We hypothesize that diesel exhaust (DE) inhalation induces up-regulation of inducible nitric oxide synthase (iNOS), which is known to contribute to vascular dysfunction, progression of atherosclerosis and ultimately cardiovascular morbidity and mortality. Methods: ApoE knockout mice (30-week) were exposed to DE (at 200 {mu}g/m{sup 3} of particulate matter) or filtered-air (control) for 7 weeks (6 h/day, 5 days/week). iNOS expression in the blood vessels and heart was evaluated by immunohistochemistry and western blotting analysis. To examine iNOS activity, thoracic aortae were mounted in a wire myograph, and vasoconstriction stimulated by phenylephrine (PE) was measured with and without the presence of the specific inhibitor for iNOS (1400 W). NF-{kappa}B (p65) activity was examined by ELISA. The mRNA expression of iNOS and NF-{kappa}B (p65) was determined by real-time PCR. Results: DE exposure significantly enhanced iNOS expression in the thoracic aorta (4-fold) and heart (1.5 fold). DE exposure significantly attenuated PE-stimulated vasoconstriction by {approx} 20%, which was partly reversed by 1400 W. The mRNA expression of iNOS and NF-{kappa}B was significantly augmented after DE exposure. NF-{kappa}B activity was enhanced 2-fold after DE inhalation, and the augmented NF-{kappa}B activity was positively correlated with iNOS expression (R{sup 2} = 0.5998). Conclusions: We show that exposure to DE increases iNOS expression and activity possibly via NF-{kappa}B-mediated pathway. We suspect that DE exposure-caused up-regulation of iNOS contributes to vascular dysfunction and atherogenesis, which could ultimately lead to urban air pollution-associated cardiovascular morbidity and mortality. - Highlights: > Exposed ApoE knockout mice (30-week) to diesel exhaust (DE) for 7 weeks. > Examine iNOS expression and activity in the blood vessels and heart. > DE exposure enhanced iNOS protein and mRNA expression in the aorta and heart. > iNOS activity was also increased after DE exposure. > This up-regulation of iNOS may contribute to vascular dysfunction and atherogenesis.},
doi = {10.1016/j.taap.2011.06.013},
journal = {Toxicology and Applied Pharmacology},
number = 2,
volume = 255,
place = {United States},
year = {Thu Sep 01 00:00:00 EDT 2011},
month = {Thu Sep 01 00:00:00 EDT 2011}
}
  • Background: Particulate air pollution can aggravate cardiovascular disease by mechanisms suggested to involve translocation of particles to the bloodstream and impairment of endothelial function, possibly dependent on present atherosclerosis. Aim: We investigated the effects of exposure to diesel exhaust particles (DEP) in vivo and ex vivo on vasomotor functions in aorta from apoE{sup -/-} mice with slight atherosclerosis and from normal apoE{sup +/+} mice. Methods: DEP 0, 0.5 or 5 mg/kg bodyweight in saline was administered i.p. The mice were sacrificed 1 h later and aorta ring segments were mounted on wire myographs. Segments from unexposed mice were also incubatedmore » ex vivo with 0, 10 and 100 {mu}g DEP/ml before measurement of vasomotor functions. Results: Exposure to 0.5 mg/kg DEP in vivo caused a decrease in the endothelium-dependent acetylcholine elicited vasorelaxation in apoE{sup -/-} mice, whereas the response was enhanced in apoE{sup +/+} mice. No significant change was observed after administration of 5 mg/kg DEP. In vivo DEP exposure did not affect constriction induced by K{sup +} or phenylephrine. In vitro exposure to 100 {mu}g DEP/ml enhanced acetylcholine-induced relaxation and attenuated phenylephrine-induced constriction. Vasodilation induced by sodium nitroprusside was not affected by any DEP exposure. Conclusion: Exposure to DEP has acute effect on vascular functions. Endothelial dysfunction possibly due to decreased NO production as suggested by decreased acetylcholine-induced vasorelaxation and unchanged sodium nitroprusside response can be induced by DEP in vivo only in vessels of mice with some atherosclerosis.« less
  • Objectives: To determine if hemorrhage into an arterial wall can be detected in CT images by virtue of the iron content. Materials and Methods: Aortas from male apoE-/-/LDL-/- mice (n = 31) were infused in situ with contrast agent, for micro-CT scanning and histology. Roentgen-opacities within the aortic walls were identified by histology and micro-x-ray fluorescence to be iron or calcium. Dual-energy scanning was performed at 2 energy levels using synchrotron-based micro-CT [(2 {mu}m)3 voxels, 16 and 20 keV] and 64-slice CT (0.4 x 0.4 x 0.6 mm voxels, 80 and 120 kVp). Results: Opacities were identified as hemorrhage-related clustersmore » of multiple punctate deposits, containing both Fe (0.48 x 10-12 g/voxel) and Ca (3.18 x 10-2 g/voxel), or as isolated confluent accumulations of exclusively calcium. Subtraction of the dual-energy CT scans discriminated iron from calcium deposits. Conclusion: Detection and quantification of iron deposits in hemorrhaged atherosclerotic lesions is feasible by dual-energy CT imaging.« less
  • Highlights: •FXR up-regulates apoF. •It binds to ER1 element. •It activates apoF gene promoter. -- Abstract: Apolipoprotein F is a component protein mainly secreted by liver and resides on several lipoprotein classes. It can inhibit lipids transfer between different lipoproteins. FXR is a member of the nuclear receptor superfamily which is also highly expressed in the liver. It modulates bile acids synthesis and lipids metabolism by transcriptional regulation. We aimed to determine whether apoF can be regulated by FXR. The FXR agonist Chenodeoxycholic acid (CDCA) and GW4064 both can activate the expression of apoF in liver cell lines and inmore » C57/BL6 mouse liver. This is dependent on the binding of FXR to the FXR element ER1 (−2904 to −2892 bp) in the apoF gene promoter. Taken together, we have identified apoF as likely another target gene of FXR.« less
  • This study aimed to explore the mechanisms by which prodigiosin protects against hypoxia-induced oxidative/nitrosative brain injury induced by middle cerebral artery occlusion/reperfusion (MCAo/r) injury in mice. Hypoxia in vitro was modeled using oxygen-glucose deprivation (OGD) followed by reoxygenation of BV-2 microglial cells. Our results showed that treatment of mice that have undergone MCAo/r injury with prodigiosin (10 and 100 {mu}g/kg, i.v.) at 1 h after hypoxia ameliorated MCAo/r-induced oxidative/nitrosative stress, brain infarction, and neurological deficits in the mice, and enhanced their survival rate. MCAo/r induced a remarkable production in the mouse brains of reactive oxygen species (ROS) and a significantmore » increase in protein nitrosylation; this primarily resulted from enhanced expression of NADPH oxidase 2 (gp91{sup phox}), inducible nitric oxide synthase (iNOS), and the infiltration of CD11b leukocytes due to breakdown of blood-brain barrier (BBB) by activation of nuclear factor-kappa B (NF-{kappa}B). All these changes were significantly diminished by prodigiosin. In BV-2 cells, OGD induced ROS and nitric oxide production by up-regulating gp91{sup phox} and iNOS via activation of the NF-{kappa}B pathway, and these changes were suppressed by prodigiosin. In conclusion, our results indicate that prodigiosin reduces gp91{sup phox} and iNOS expression possibly by impairing NF-{kappa}B activation. This compromises the activation of microglial and/or inflammatory cells, which then, in turn, mediates prodigiosin's protective effect in the MCAo/r mice. -- Highlights: Black-Right-Pointing-Pointer Prodigiosin ameliorated brain infarction and deficits. Black-Right-Pointing-Pointer Prodigiosin protected against hypoxia/reperfusion-induced brain injury. Black-Right-Pointing-Pointer Prodigiosin diminished oxidative/nitrosativestress and leukocytes infiltration. Black-Right-Pointing-Pointer Prodigiosin reduced BBB breakdown. Black-Right-Pointing-Pointer Prodigiosin down-regulated gp91{sup phox} and iNOS by inhibiting NF-{kappa}B activation.« less
  • Recent epidemiological studies suggest that traffic-related air pollution may have detrimental effects on cardiovascular health. Previous studies reveal that gasoline emissions can induce several enzyme pathways involved in the formation and development of atherosclerotic plaques. As a direct comparison, the present study examined the impact of diesel engine emissions on these pathways, and further examined the effects on vascular lesion pathology. Apolipoprotein E-null mice were simultaneously placed on a high-fat chow diet and exposed to four concentrations, plus a high concentration exposure with particulates (PM) removed by filtration, of diesel emissions for 6 h/day for 50 days. Aortas were subsequentlymore » assayed for alterations in matrix metalloproteinase-9, endothelin-1, and several other biomarkers. Diesel induced dose-related alterations in gene markers of vascular remodeling and aortic lipid peroxidation; filtration of PM did not significantly alter these vascular responses, indicating that the gaseous portion of the exhaust was a principal driver. Immunohistochemical analysis of aortic leaflet sections revealed no net increase in lesion area, but a significant decrease in lipid-rich regions and increasing trends in macrophage accumulation and collagen content, suggesting that plaques were advanced to a more fragile, potentially more vulnerable state by diesel exhaust exposure. Combined with previous studies, these results indicate that whole emissions from mobile sources may have a significant role in promoting chronic vascular disease.« less