Anti-inflammatory activity of beta2-agonists in primary lung epithelial cells is independent of glucocorticoid receptor.

In patients with asthma and chronic obstructive pulmonary disease, the addition of long-acting beta(2)-agonists (LABA) to glucocorticosteroids (GCS) results in better control than increasing the dose of GCS alone. In smooth muscle cells and fibroblasts, one apparent underlying mechanism involves the ability of LABAs to activate the glucocorticoid receptor (GR). The present study investigates the effects of formoterol (FORM), salmeterol (SALM) and budesonide (BUD) on GR activation in bronchial epithelial cells via tumour necrosis factor-alpha-stimulated granulocyte-macrophage colony-stimulating factor (GM-CSF) release, GR nuclear translocation and GR-regulated reporter gene activity. Both BUD and FORM inhibited GM-CSF release by < or = 50%. The combination of these two drugs, in clinically relevant concentrations, inhibited GM-CSF release by 85% down to unstimulated levels. A similar inhibition was obtained when combining BUD and SALM. The ability of FORM to inhibit GM-CSF synthesis was not altered by small interfering RNA-mediated depletion of GR and FORM nor SALM-induced GR translocation into the cell nucleus. In addition, FORM did not activate GR-regulated reporter gene activity (SALM was not tested), in contrast to the clear effect of BUD. It was concluded that in bronchial epithelial cells, inhibition of granulocyte-macrophage colony-stimulating factor synthesis by formoterol and salmeterol does not act via previously demonstrated glucocorticoid receptor-related mechanisms, suggesting an alternative pathway in these cells.

Effects of formoterol and budesonide on GM-CSF and IL-8 secretion by triggered human bronchial epithelial cells.

The effect of formoterol, alone and in combination with budesonide, upon tumour necrosis factor-alpha stimulated (10 ng x mL(-1)) human bronchial epithelial cells was investigated. Addition of formoterol (> or = 10(-10) M) reduced granulocyte macrophage-colony stimulating factor (GM-CSF) levels, as assessed by enzyme-linked immunosorbent assay, by 40-50% and increased interleukin (IL)-8 levels by approximately 50%. The effects of formoterol were long lasting (23 h). Budesonide (10(-8) M) reduced the amounts of both cytokines (GM-CSF and IL-8) by 40%. Simultaneous addition of formoterol and budesonide reduced GM-CSF levels approximately 75%, while IL-8 levels were decreased approximately 40%, similar to the reduction obtained with budesonide alone. The glucocorticoid receptor (GR) antagonist RU486 did not influence the effect of formoterol, suggesting no involvement of the GR. Formoterol rapidly induced an elevation in intracellular cyclic adenosine monophosphate, which was reduced in the presence of propranolol. In addition, the alterations in cytokine secretion induced by formoterol could be fully blocked by propranolol, demonstrating that these effects are beta2-receptor mediated. In conclusion, the combination of budesonide and formoterol reduces the secretion of granulocyte macrophage-colony stimulating factor to basal levels and counteracts the capacity of formoterol alone to induce interleukin-8 production, modulations which may facilitate improved asthma control.