Soot-Exposed Mononuclear Cells Increase Inflammatory Cytokine mRNA Expression and Protein Secretion in Cocultured Bronchial Epithelial Cells

Abstract

Background: Soot particles are air pollutants capable of inducing airway and lung parenchymal injury. Mononuclear and bronchial epithelial cells are central to the maintenance of homeostasis and inflammation in the airways. Objectives: The aim of this study was to evaluate the contribution of mononuclear cells to the release of inflammatory mediators by bronchial epithelial cells. Methods: To model the in vivo situation, an in vitro system of cocultured blood monocytes and BEAS-2B cells was established in a transwell system. Blood monocytes were exposed to soot particles (FR 101) at concentrations of up to 100 μg/10⁶ cells. Inflammatory cytokine mRNA and protein concentrations were quantified in BEAS-2B mono- and BEAS-2B-BM cocultures by RT-PCR and ELISA following exposure to soot for 1 and 8 h. Results: No inflammatory cytokine mRNA expression was observed in unstimulated BEAS-2B cells. IL-6 and IL-8 mRNA and protein levels showed a dose-dependent elevation in FR 101-exposed blood monocytes. In addition, both IL-6 and IL-8 mRNA expression was upregulated in cocultured BEAS-2B cells while cytokine concentrations in the blood monocyte-BEAS-2B coculture medium were significantly increased. This upregulation was likely due to a synergism of two cell populations. Conclusions: Exposure to soot particles induces an autocrine stimulation of inflammatory cytokine release by blood monocytes and BEAS-2B cells. Since IL-6 and IL-8 play a major role in the pathogenesis and persistence of bronchial inflammation, these findings may serve as a partial explanation for the aggravation of asthmatic and bronchitic symptoms after exposure to soot.

Effects of Particulate Matter on Cytokine Production In Vitro: A Comparative Analysis of Published Studies

“…A further cytokine that has been studied in a sufficient number of experiments to allow for a comparative analysis, is TNF-α. The results are also included in Table 5 for different concentrations of (Becker et al, 2005a(Becker et al, , 2005bCarter et al, 1997;Drumm et al, 2000;Dybing et al, 2004;Fujii et al, 2001Fujii et al, , 2002Garcon et al, 2006;Gilmour et al, 2003Gilmour et al, , 2005Hetland et al, 2004;Inoue et al, 2007;Ishii et al, 2004Ishii et al, , 2005Jimenez et al, 2002;Li et al, 2002;Mazzarella et al, 2007;Osornio-Vargas et al, 2003;Payne et al, 2004;Reibman et al, 2002Reibman et al, , 2003Stringer & Kobzik, 1998;Tao & Kobzik, 2002;Wottrich et al, 2004;Wu et al, 2001) particles and exposure times. Significant effects were observed at a concentration of about 50 µg/mL over time periods ranging between 9 and 24 hours.…”

“…As in table 4, the total numbers do not necessarily equal the number of experiments or studies, since authors might have investigated more than one cytokine in a study. Eight studies evaluated IL-6 (Carter et al, 1997;Drumm et al, 2000;Fujii et al, 2002;Ishii et al, 2004Ishii et al, , 2005Mazzarella et al, 2007;Payne et al, 2004;Wottrich et al, 2004), and twelve studies evaluated IL-8 (Carter et al, 1997;Drumm et al, 2000;Garcon et al, 2006;Gilmour et al, 2003;Hetland et al, 2004;Ishii et al, 2004;Li et al, 2002;Mazzarella et al, 2007;Payne et al, 2004;Schins et al, 2000;Stringer and Kobzik, 1998;Wottrich et al, 2004). Finally, TNF-α data are based on 6 references Fujii et al, 2002;Garcon et al, 2006;…”

“…See table 4 legend for clarification of the difference in total number of studies vs. total number of experiments. Twelve studies were evaluated for this table (Becker et al, 2005b;Carter et al, 1997;Drumm et al, 2000;Fujii et al, 2001Fujii et al, , 2002Gilmour et al, 2003Gilmour et al, , 2005Ishii et al, 2004Ishii et al, , 2005Jimenez et al, 2002;Reibman et al, 2003;Wu et al, 2001) Particle 24 hours. Twenty-six references were evaluated for this table.…”

Bacillus anthracisSpores Stimulate Cytokine and Chemokine Innate Immune Responses in Human Alveolar Macrophages through Multiple Mitogen-Activated Protein Kinase Pathways

“…There are, of course, other cells present in intact lungs that may independently provide an additional response or alter the response seen by alveolar macrophages. It is known, for example, that macrophage-epithelium interactions enhance the innate immune cytokine response to hyperoxia, particulants, and other toxins (8,16,17,25,28). We deliberately limited our studies to the interaction of spores with macrophages and diminished possible effects of germinated bacteria by using gentamicin in the medium.…”

Human lung innate immune cytokine response to adenovirus type 7

“…IP-10 was found in both epithelial cells and macrophages, suggesting that both types of cell participate and cooperate in the innate immune response that is responsible for the influx of inflammatory cells seen in Ad7 infection, and both cell types produce IP-10 in other systems (Pechkovsky et al, 2005;Tibbles et al, 2002;Zaiss et al, 2009). It has been shown that interactions between macrophages and epithelial cells promote inflammatory responses to hyperoxia, particulates and other toxins (Drumm et al, 2000;Hjort et al, 2003;Lee & Rannels, 1996;Sharma et al, 2004;Tao & Kobzik, 2002). Elegant work by D'Angio and co-workers demonstrated that cell-cell contact of THP-1 monocyte/macrophages and A549 epithelial cells is important for extracellular and intracellular IL-8 induction by hyperoxia in co-cultured THP-1 cells (Hjort et al, 2003).…”