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Responsiveness of alveolar macrophages from iNOS Knockout or wild type mice to an in vitro LPS or silica exposure.

Zeidler PC; Robinson VA; Castranova V
Toxicologist 2002 Mar; 66(1-S):353
The role of nitric oxide (NO) in pulmonary disease has been controversial with both anti-inflammatory (scavenging radicals and inhibiting NF- B activation) and pro-inflammatory (forming highly reactive peroxynitrite and augmenting NF- B activation by inflammatory agents) actions reported. Therefore, a project has been initiated to determine whether deletion of the iNOS gene in the C57BL/6J mouse alters the pulmonary response to lipopolysaccharide (LPS) or silica. The objective of the initial phase of this study was to determine the responsiveness of alveolar macrophages (AM's), harvested from naive wild type (WT) or iNOS knockout (KO) mice, to an in vitro LPS or silica exposure. Primary AM's were obtained by bronchoalveolar lavage from age and weight matched iNOS KO and WT mice. The cells were treated with IFN- (50 U/ml), IFN- (50 U/ml) plus LPS (1 g/ml), LPS (0.01 -100 g/ml), or silica (25 - 250 g/ml). Inflammatory parameters included: NO, tumor necrosis factor- (TNF- ) and macrophage inflammatory protein-2 (MIP-2) production, and intracellular generation of hydrogen peroxide and superoxide. Data show a significant increase in NO production upon exposure to IFN- +/- LPS in the WT but not iNOS KO AM's. NO production by KO or WT AM's was not increased by in vitro exposure to LPS or silica alone. LPS, but not silica, induced TNF- and MIP-2 production with the KO AM's being more responsive than WT. Basal intracellular production of hydrogen peroxide and superoxide was significantly greater in KO compared to WT AM's. In addition, LPS (10 g/ml) or silica (100 g/ml) stimulated intracellular oxidant production was lower in KO AM's. In conclusion, when compared to WT AM's, iNOS KO AM's exhibit a decreased ability to generate reactive oxygen species in response to LPS or silica. However, iNOS KO AM's exhibit enhanced inflammatory cytokine and chemokine production in response to LPS.
Pulmonary-disorders; Animal-studies; Silica-dusts; In-vitro-studies; Exposure-levels; Aerosols; Pulmonary-system-disorders; Respiratory-system-disorders
Publication Date
Document Type
Fiscal Year
NIOSH Division
Priority Area
Asthma and Chronic Obstructive Pulmonary Disease; Disease and Injury
Source Name
The Toxicologist. Society of Toxicology 41st Annual Meeting and ToxExpo, March 17-21, 2002, Nashville, Tennessee
Page last reviewed: March 3, 2021
Content source: National Institute for Occupational Safety and Health Education and Information Division