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Role of inducible nitric oxide synthase-deried nitric oxide in silica-induced pulmonary inflammation and fibrosis.

Authors
Zeidler-PC; Hubbs-A; Battelli-L; Castranova-V
Source
J Toxicol Environ Health, A 2004 Jul; 67(13):1001-1026
NIOSHTIC No.
20025386
Abstract
Inhalation of crystalline silica can produce lung inflammation and fibrosis. Inducible nitric oxide synthase (iNOS)-derived nitric oxide (NO) is believed to be involved in silica-induced lung disease. To investigate the role of iNOS-derived NO in this disease, the responses of iNOS knockout (KO) versus C57Bl/6J wild-type (WT) mice to silica were compared. Male mice (8-10 wk old, mean body weight 24.0 g) were anesthetized and exposed, by aspiration, to silica (40 mg/kg) or saline. At 24 h and 42 d postexposure, lungs were lavaged with saline. The first bronchoalveolar lavage (BAL) fluid supernatant was analyzed for lactate dehydrogenase (LDH) activity, levels of albumin, tumor necrosis factor-alpha (TNF-alpha), and macrophage inflammatory protein-2 (MIP-2), as well as total antioxidant capacity (TAC). The cellular fraction of the total BAL was used to determine alveolar macrophage (AM) and polymorphonuclear leukocyte (PMN) counts, and zymosanstimulated AM chemiluminescence (AM-CL). In separate mice, lung histopathological changes were evaluated 42 d postexposure. Acute (24-h) silica exposure decreased AMs, increased PMNs, increased LDH activity and levels of albumin, TNF-alpha, and MIP-2 in BAL fluid, and enhanced AM-CL in both iNOS KO and WT mice. However, iNOS KO mice exhibited less AM activation (defined as increased AM-CL and decreased AM yield) than WT. Furthermore, TAC following acute silica decreased in WT but was maintained in iNOS KO mice. Pulmonary reactions to subchronic (42 d) silica exposure were similar to acute. However, histopathological and BAL fluid indices of lung damage and inflammation, AM activation, and lung hydroxyproline levels were significantly less in iNOS KO compared to WT mice. These results suggest that iNOS-derived NO contributes to the pathogenesis of silica-induced lung disease in this mouse model.
Keywords
Animals; Animal-studies; Exposure-levels; Fibrosis; Injuries; Laboratory-animals; Lung-disease; Lung-disorders; Nitrous-oxides; Oxides; Pulmonary-system-disorders; Respiratory-system-disorders; Silica-dusts; Silicates
Contact
National Institute for Occupational Safety and Health, Health Effects Laboratory Division, and Department of Physiology and Pharmacology, West Virginia University, Morgantown, West Virginia 26505, USA
CODEN
JTEHD6
CAS No.
10102-43-9
Publication Date
20040701
Document Type
Journal Article
Email Address
vic1@cdc.gov
Fiscal Year
2004
NTIS Accession No.
NTIS Price
Issue of Publication
13
ISSN
1528-7394
NIOSH Division
HELD
Source Name
Journal of Toxicology and Environmental Health, Part A: Current Issues
State
WV
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