Modulation of TNF and GM-CSF release from dispersed human nasal polyp cells and human whole blood by inhibitors of different PDE isoenzymes and glucocorticoids.

The aim of this study was to investigate the role of the inhibitors of different PDE isoenzymes (PDE 1-5) on the production of two pro-inflammatory cytokines - tumor necrosis factor alpha (TNF) and granulocyte-macrophage colony-stimulating factor (GM-CSF). Two in vitro models were used to compare the antiinflammatory properties of PDE inhibitors with that of glucocorticoids. The effect on TNF release from diluted human blood following lipopolysaccharide (LPS from Salmonella abortus equi) stimulation as well as the GM-CSF and TNF release from human nasal polyp cells following allergic stimulation were investigated. Both models proofed to be well suited for the characterisation of the antiinflammatory properties of new chemical entities. In diluted human blood and dispersed human nasal polyp cells the induced TNF release was most potently suppressed by selective PDE4 inhibitors. Amrinone and milrinone, selective PDE3 inhibitors, suppressed TNF secretion to a lesser extent. The effects of theophylline (unspecific PDE inhibitor), vinpocetine (PDE1 inhibitor), EHNA (PDE2 inhibitor) and the PDE5 inhibitors zaprinast and E 4021 were weak. In human blood, the tested glucocorticoids beclomethasone, dexamethasone and fluticasone inhibited the LPS induced TNF release potently in a concentration dependent manner, whereas in dispersed human nasal polyp cells, the effect of the glucocorticoids on allergically induced TNF release, with the exception of dexamethasone, was much less pronounced. Glucocorticoids were the most potent inhibitors of GM-CSF release and the effect correlates well with the affinity to the glucocorticoid receptor. The selective PDE 4 inhibitors, and to a certain extent the PDE3 inhibitors amrinone and milrinone, reduced the GM-CSF release in a concentration dependent manner. In all investigations selective PDE4 inhibitors reduced TNF release to a much higher degree (4-10 fold) than GM-CSF release. Copyright 2002 Elsevier Science Ltd.