GRO-α regulation in airway smooth muscle by IL-1β and TNF-α:: role of NF-κB and MAP kinases

Airway smooth muscle cells ( ASMC) are a source of inflammatory chemokines that may propagate airway inflammatory responses. We investigated the production of the CXC chemokine growth-related oncogene protein-alpha ( GRO-alpha) from ASMC induced by cytokines and the role of MAPK and NF-kappa B pathways. ASMC were cultured from human airways, grown to confluence, and exposed to cytokines IL-1 beta and TNF-alpha after growth arrest. GRO-alpha release, measured by ELISA, was increased by > 50-fold after IL-1 beta ( 0.1 ng/ml) or 5-fold after TNF-alpha ( 1 ng/ml) in a dose- and time-dependent manner. GRO-alpha release was not affected by the T helper type 2 cytokines IL-4, IL-10, and IL-13. IL-1 alpha and TNF-alpha also induced GRO-alpha mRNA expression. Supernatants from IL-1 beta-stimulated ASMC were chemotactic for neutrophils; this effect was inhibited by anti-GRO-alpha blocking antibody. AS-602868, an inhibitor of IKK-2, and PD-98059, an inhibitor of ERK, inhibited GRO-alpha release and mRNA expression, whereas SP-600125, an inhibitor of JNK, reduced GRO-alpha release without effect on mRNA expression. SB-203580, an inhibitor of p38 MAPK, had no effect. AS-602868 but not PD-98059 or SP-600125 inhibited p65 DNA-binding induced by IL-1 beta and TNF-alpha. By chromatin immunoprecipitation assay, IL-1 beta and TNF-alpha enhanced p65 binding to the GRO-alpha promoter, which was inhibited by AS-602868. IL-1 beta- and TNF-alpha-stimulated expression of GRO-alpha from ASMC is regulated by independent pathways involving NF-kappa B activation and ERK and JNK pathways. GRO-alpha released from ASMC participates in neutrophil chemotaxis.