Mitogen-activated protein kinases regulate cytokine gene expression in human airway myocytes

The signal transduction pathways regulating smooth-muscle gene expression and production of cytokines in response to proinflammatory mediators are undefined. Cultured human bronchial smooth-muscle cells were treated for 20 h with a cytokine cocktail containing interleukin (IL)-1β, tumor necrosis factor-α, and interferon-γ. A complementary DNA expression array containing 588 genes was used to follow cytokine-stimulated gene expression. The expression and secretion of the cytokines IL-1β, IL-6, and IL-8 significantly increased after 20 h of stimulation as measured by relative reverse transcriptase/polymerase chain reaction, enzyme-linked immunosorbent assay, and Western blotting techniques. Expression of IL-6 and IL-8 was sensitive to SB203580, the specific inhibitor of p38 mitogen-activated protein (MAP) kinase and PD98059, an inhibitor of MAP kinase kinase. Expression of IL-1β was sensitive only to PD98059. Together, these results demonstrate that the p38 and extracellular signal-regulated protein kinase MAP kinase pathways are required for proinflammatory mediator-induced cytokine expression in airway myocytes. The generation of chemokines and cytokines in airway smooth muscle also provides evidence that smooth-muscle cells have the ability to contribute to the inflammatory response.