p38 MAP kinase regulates IL-1beta responses in cultured airway smooth muscle cells

1 Physiology Program, Harvard School of Public Health, Boston, Massachusetts 02115; and 2 Pulmonary and Critical Care Division, Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104 We have previously reported that interleukin (IL)-1 causes -adrenergic hyporesponsiveness in cultured human airway smooth muscle (HASM) cells by increasing cyclooxygenase (COX)-2 expression. The purpose of this study was to determine whether p38 mitogen-activated protein (MAP) kinase is involved in these events. IL-1 (2 ng/ml for 15 min) increased p38 phosphorylation fourfold. The p38 inhibitor SB-203580 (3 µM) decreased IL-1 -induced COX-2 by 70 ± 7% ( P < 0.01). SB-203580 had no effect on PGE 2 release in control cells but caused a significant (70-80%) reduction in PGE 2 release in IL-1 -treated cells. IL-1 increased the binding of nuclear proteins to the oligonucleotides encoding the consensus sequences for activator protein (AP)-1 and nuclear factor (NF)- B, but SB-203580 did not affect this binding, suggesting that the mechanism of action of p38 was not through AP-1 or NF- B activation. The NF- B inhibitor MG-132 did not alter IL-1 -induced COX-2 expression, indicating that NF- B activation is not required for IL-1 -induced COX-2 expression in HASM cells. IL-1 attenuated isoproterenol-induced decreases in HASM stiffness as measured by magnetic twisting cytometry, and SB-203580 abolished this effect. These results are consistent with the hypothesis that p38 is involved in the signal transduction pathway through which IL-1 induces COX-2 expression, PGE 2 release, and -adrenergic hyporesponsiveness. mitogen-activated protein; interleukin-1 ; human airway smooth muscle; SB-203580; nuclear factor- B; activator protein-1; prostaglandin E 2 ; cyclooxygenase-2; -adrenergic responsiveness; cytoskeletal mechanics; magnetic twisting cytometry