Cooperative Inhibitory Effects of Budesonide and Formoterol on Eosinophil Superoxide Production Stimulated by Bronchial Epithelial Cell Conditioned Medium

Abstract

Background: Improved asthma control by combinations of inhaled glucocorticosteroids (GCs) and long-acting β₂-agonists (LABAs) includes a reduced frequency and severity of exacerbations. In view of the association of exacerbations with increased airway inflammation, the question has arisen as to whether LABAs are able to complement the known anti-inflammatory activity of GCs. To address this, we studied the effects of a LABA, formoterol (FORM), and a GC, budesonide (BUD), alone and in combination, on bronchial epithelial cell-mediated eosinophil superoxide production in vitro.Methods: We employed 2 experimental approaches. First, superoxide production by human eosinophils incubated with conditioned medium (CM) from human bronchial epithelial cells cultured for 24 h with vehicle, BUD, FORM or BUD + FORM was measured (Epi/Eos assay). Second, eosinophils were stimulated with vehicle-CM to which the drugs were added (Eos assay). Superoxide production was determined as the superoxide dismutase-inhibitable reduction of ferricytochrome C. Results: CM increased eosinophil superoxide generation (p < 0.01) and epithelial-derived granulocyte macrophage colony-stimulating factor was the mediator responsible. In both assays, FORM dose-dependently inhibited eosinophil superoxide similarly and in the same concentration range as BUD. The BUD + FORM combination was more effective than BUD alone, and it completely inhibited CM-induced superoxide production in the Epi/Eos assay, suggesting complementary effects of both drugs on bronchial epithelial cells and eosinophils. Conclusions: The cooperative, inhibitory effects of BUD and FORM on eosinophils and bronchial epithelial cells, in terms of their effects on eosinophil superoxide production, may represent a possible mechanism for the enhanced anti-inflammatory efficacy of BUD and FORM combination therapy of asthma.

Fixed airflow obstruction in asthma: a descriptive study of patient profiles and effect on treatment responses

“…Interestingly, however, the fixed combination of budesonide and formoterol resulted in a greater effect on lung function than the monocomponents in both FAO+ and FAO− patients, and these effects were more than additive in FAO+ patients. This notion is consistent with results of in vitro studies showing cooperative, additive and synergistic anti-inflammatory and bronchoprotective effects between formoterol and budesonide [17–21]. …”

A Holy Grail of asthma management: toward understanding how long‐acting β2‐adrenoceptor agonists enhance the clinical efficacy of inhaled corticosteroids

“…Similar effects have been reported with salmeterol on the inhibition, by fluticasone, of both IL‐8 and eotaxin release from HASM cells ( Pang and Knox, 2000 , 2001 ). Budesonide and formoterol have also been shown to inhibit the generation of superoxide anions from human eosinophils and that a combination of both drugs is more effective than budesonide alone ( Persdotter et al , 2007 ). In the cells present in induced sputum, formoterol and salmeterol may enhance beclomethasone‐induced translocation of GR to the nucleus and suppress the release of RANTES (regulated upon activation, normal T cell‐expressed and ‐secreted) and IL‐8 ( aka CCL5 and CXCL8, respectively) ( Profita et al , 2005 ).…”

Why use long acting bronchodilators in chronic obstructive lung diseases? An extensive review on formoterol and salmeterol

“…ROS can also decrease the number and function of β 2 -adrenoceptors in lung tissue, and impair steroid receptor function. Formoterol and salmeterol were shown to reduce ROS generation in neutrophils and eosinophils in vitro and in vivo [56][57][58][59][60][61][62][63] and in cooperation with corticosteroids [64]. Principally, leukocytes have a relatively low number of β 2 adrenoceptors which may be further decreased under inflammatory conditions and oxidative stress.…”