Production of reactive oxygen intermediates by human macrophages exposed to soot particles and asbestos fibers and increase in NF-kappa B p50/p105 mRNA

Alveolar macrophages (AM) play a decisive role in the immunologic defense s ystem of the lung and in inflammatory pulmonary pathomechanisms. AM and blo od monocytes (BM) were exposed to Chrysotile B, Soot FR 101, and Printer 90 (P 90). We evaluated the reactive oxygen intermediate (ROI) release of AM and BM after particle exposure. ROI release was measured by chemiluminescen ce. Thirty-minute exposure caused a significant (up to 2.5-fold) increase i n ROI release of AM (100 mu g/10(6) cells) compared with control experiment s (p < 0.01). Identical exposure conditions for BM resulted in a similar re action pattern (maximum 2.2-fold increase in ROI release; p < 0.05). After a 90-min particle exposure at concentrations of 10 and 100 mu g/10(6) cells , we investigated the steady-state level of p50/p105 mRNA encoding for the precursor protein of the p50 subunit of nuclear factor kappa B (NF-kappa B) by semiquantitative reverse transcription-polymerase chain reaction. One h undred mu g Chrysotile B, FR 101, or P 90 induced a significant maximum 4.0 -fold up-regulation of NF-kappa B gene expression in AM and a 3.3-fold up-r egulation in BM (p < 0.05). The addition of superoxide dismutase (200 U/ml) to particle- and fiber-exposed macrophages resulted in inhibition of ROI r elease and a decrease in NF-kappa B mRNA expression (70%). NF-kappa B is an important transcription factor involved in the regulation of numerous gene s (e.g., for inflammatory cytokines, and cytokine receptors). These cytokin es are supposed to be involved in inflammatory pathomechanisms in bronchial epithelial cells, which result, for example, in chronic obstructive pulmon ary disease. Our results suggest that particle-induced ROI release is assoc iated with an increase in NF-KB (p50/p105) mRNA steady-state level.