Nitric oxide (NO) is a gas released by the airway epithelium, but the mechanism regulating NO release is unclear. We hypothesized that lung mononuclear cell release of tumor necrosis factor α (TNF) and interleukin- 1β3 (IL-1) would induce epithelial cells to release NO. Lung mononuclear cells were obtained from seven normal volunteers by bronchoalveolar lavage and cultured with Escherichia coli lipopolysaccharide for 24 h. The mononuclear cell culture-conditioned media (M-CM) were then applied to cultures of the murine lung epithelial cell line, LA-4. Nitrite and nitrite + nitrate concentrations were 0.9 ± 0.1 and 11.8 ± 2.4 μM in the M-CM. Culturing LA-4 cells line with the M-CM (1:10 dilution) resulted in a marked and time-dependent increase in nitrite or nitrite + nitrate compared with LA- 4 cells cultured in media alone (2.4 ± 0.5 versus 0.9 ± 0.1 μm and 16.6 ± 0.6 versus 11.8 ± 2.4 μM after 24 h). Antibodies to TNF and/or IL-1 significantly reduced the nitrite or nitrite + nitrate concentrations and the concentrations of TNF and IL-1 in the M-CM correlated with nitrite concentrations in the LA-4 culture supernatant fluids (r2 = 0.848 and 0.956). Inducible nitric oxide synthase (iNOS) protein and mRNA examined by immunohistochemistry and Northern blot analysis revealed a marked elevation in the cells cultured with the M-CM which was significantly reduced by TNF and IL-1 antibodies. These data demonstrate that mononuclear cells can stimulate LA-4 cells to express iNOS by releasing TNF and IL-1.
|Original language||English (US)|
|Number of pages||6|
|Journal||American Journal of Respiratory and Critical Care Medicine|
|State||Published - Jan 1 1997|
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine
- Critical Care and Intensive Care Medicine