Abstract
Background: β2-Adrenergic receptor agonists can reduce the release of GM-CSF by human airway smooth muscle cells (HASMCs). These effects are considered anti-inflammatory and are ascribed to the activity of the (R)-enantiomer within the racemate of the agonist. However, the effect of the (S)-enantiomer on GM-CSF release, once thought to be inert, has not been extensively explored. Objective: We hypothesized that the (S)-enantiomer may counter the effects of the (R)-enantiomer, potentially increasing GM-CSF release. Therefore, the effects of administration of individual and combined enantiomers on GM-CSF release were examined. Methods: Cultured HASMCs were stimulated with IL-1β, TNF-α, and IFN-γ and treated with (R)-enantiomers and (S)-enantiomers of albuterol and formoterol, with and without propranolol and ICI-118,551, and in combination with dexamethasone. GM-CSF in the resulting conditioned media was assessed by ELISA. Results: (R)-enantiomers significantly reduced GM-CSF release by as much as 41% (P < .05), which was reversible with propranolol. In contrast, (S)-enantiomers significantly increased GM-CSF release by as much as 34% (P < .05) over release with no drug, and by 25% to 40% (P < .05) when added with (R)-enantiomers. The decremental effect of dexamethasone was amplified by (R)-enantiomers but inhibited by (S)-enantiomers. Both propranolol and ICI-118,551 alone increased GM-CSF release in a concentration-dependent fashion, similar to (S)-enantiomers. Conclusion: We conclude that GM-CSF release by HASMC is downregulated by (R)-enantiomers and enhanced by (S)-enantiomers. The reversal of (R)-enantiomer and dexamethasone effects by the (S)-enantiomer suggests suppression of their anti-inflammatory effects, perhaps through an antagonistic mechanism similar to propranolol.
Original language | English (US) |
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Pages (from-to) | 65-72 |
Number of pages | 8 |
Journal | Journal of Allergy and Clinical Immunology |
Volume | 116 |
Issue number | 1 |
DOIs | |
State | Published - Jul 2005 |
Externally published | Yes |
Keywords
- Albuterol
- Formoterol
- Inverse agonist
- Levalbuterol
- Propranolol
- Racemic
- cAMP
- β-receptors
ASJC Scopus subject areas
- Immunology and Allergy
- Immunology