Tumor necrosis factor α (TNFα) plays an important role in the pathogenesis of silicosis and other chronic inflammatory lung diseases. The present study investigates the role nuclear transcription factor κB (NF-κB) and oxygen free radicals in silica-induced TNFα production in primary alveolar macrophages and RAW 264.7 cells. Using electrophoretic mobility shift assay (EMSA) and enzyme-linked immunoadsorbent assay (ELISA), we have demonstrated that silica can induce NF-κB activation and TNFα expression in a dose-dependent manner. Transient transfection assays with a plasmid construct containing NF-κB binding sites linked to a reporter gene further show that silica is able to induce the transcriptional activation of NF-κB-dependent gene. Inhibition of NF-κB activation by SN50, a specific NF-κB blocker, abolishes silica-induced TNFα production. Pretreatment of the cells with catalase (H2O2 scavenger) or deferoxamine (·OH scavenger) effectively inhibits NF-κB and TNFα activation, whereas superoxide dismutase (O2 scavenger) has an opposite effect. These results indicate that silica mediated free radical generation and NF-κB activation play important roles in silica-induced TNFα gene expression.
|Number of pages||7|
|Journal||Molecular and Cellular Biochemistry|
|State||Published - 1999|
Bibliographical noteFunding Information:
This work was supported in part by the National Institutes of Health Grant HL54291 and by the National Institute of Occupational Safety and Health.
- Oxygen radicals
- Transcription factors
ASJC Scopus subject areas
- Molecular Biology
- Clinical Biochemistry
- Cell Biology