TY - JOUR T1 - Reverbα is a novel regulator of COPD macrophage inflammation and glucocorticoid resistance JF - European Respiratory Journal JO - Eur Respir J VL - 38 IS - Suppl 55 SP - p3849 AU - John Blaikley AU - Julie Gibbs AU - Andrew Loudon AU - Stuart Farrow AU - Dave Singh AU - David Ray Y1 - 2011/09/01 UR - http://erj.ersjournals.com/content/38/Suppl_55/p3849.abstract N2 - Introduction: Human inflammation shows circadian oscillation of inflammatory mediators e.g. IL-6. The potency of many anti-inflammatory drugs e.g. glucocorticoids also oscillate in a similar manner. The mechanisms causing these phenomena are poorly understood. A recent discovery describes that cells have a “molecular clock”, regulating 10% of the genome.Aims: We investigated the function and mechanism of Reverbα, part of this “molecular clock”, concerning COPD inflammation.Results: LPS stimulated macrophages showed a diurnal response for IL-6. A novel Reverbα ligand (GSK414112) corrected this but had no effect if Reverbα expression was suppressed. The ligand had no effect in two epithelial cell lines (A549, Hela), demonstrating cell specific actions. An array and luminex analysis on cellular supernatants from human healthy and COPD macrophages defined the targets and mechanism of GSK414112 suppression. A number of key COPD targets were suppressed. GSK414112 up regulated PPARγ and LXRα, two nuclear receptors, and their respective cholesterol target genes e.g. ABCA1. Distal regulatory element analysis identified the importance of the LXR_DR4 motif, which Reverbα binds. This mechanism was confirmed experimentally with a LXR antagonist. Luciferase reporter constructs, focused on the IL-6 proximal promoter, identified that the ligand's cell specific effects were due to the C/EBP transcription factor binding site. GSK414112 doubled the IC50 of dexamethasone on IL-8.Conclusion: Reverbα affects both inflammation and glucocorticoid resistance. Synthetic ligands can modify its function potentially allowing for the first time temporal control of the inflammatory response and glucocorticoid potency. ER -