KF19514, a phosphodiesterase 4 and 1 inhibitor, inhibits TNF-alpha-induced GM-CSF production by a human bronchial epithelial cell line via inhibition of PDE4.

Abstract

Bronchial epithelium plays an important role in the regulation of inflammatory reactions in the airways. We investigated the effect of KF19514, a phosphodiesterase (PDE) 4 and 1 inhibitor, on granulocyte-macrophage colony-stimulating factor (GM-CSF) production by a human bronchial epithelial cell line, BEAS-2B. BEAS-2B cells were stimulated with the tumor necrosis factor-alpha (TNF-alpha) and various concentrations of test agents for 48 h. Supernatants were assayed for GM-CSF by using an enzyme-linked immunosorbent assay (ELISA). In addition, intracellular cyclic AMP (cAMP) levels were measured in the presence of various agents. KF19514 significantly inhibited the release of GM-CSF by BEAS-2B cells in a concentration-dependent manner. The other PDE4 inhibitors and cAMP-elevating agents also inhibited the GM-CSF production. In the BEAS-2B cells, KF19514 and PDE4 inhibitors concentration-dependently increased intracellular cAMP levels. The inhibitory effect of KF19514 on the GM-CSF production was significantly reduced by a cAMP-dependent protein kinase A (PKA) inhibitor, H89. On the other hand, other PDE isozyme inhibitors did not inhibit the GM-CSF production by BEAS-2B cells, and did not elevate the intracellular cAMP levels. These results indicate that KF19514 and PDE4 inhibitors reduce TNF-alpha-induced GM-CSF production of BEAS-2B cells via a cAMP-dependent pathway. PDE4 may be a possible target for the regulation of cytokine production in epithelial cells.