Binds to the glucocorticoid receptor. Unbound corticosteroids cross the membranes of cells such as mast cells and eosinophils, binding with high affinity to glucocorticoid receptors (GR). The results include alteration of transcription and protein synthesis, a decreased release of leukocytic acid hydrolases, reduction in fibroblast proliferation, prevention of macrophage accumulation at inflamed sites, reduction of collagen deposition, interference with leukocyte adhesion to the capillary wall, reduction of capillary membrane permeability and subsequent edema, reduction of complement components, inhibition of histamine and kinin release, and interference with the formation of scar tissue. In the management of asthma, the glucocorticoid receptor complexes down-regulates proinflammatory mediators such as interleukin-(IL)-1, 3, and 5, and up-regulates anti-inflammatory mediators such as IkappaB [inhibitory molecule for nuclear factor kappaB1], IL-10, and IL-12. The antiinflammatory actions of corticosteroids are also thought to involve inhibition of cytosolic phospholipase A2 (through activation of lipocortin-1 (annexin)) which controls the biosynthesis of potent mediators of inflammation such as prostaglandins and leukotrienes.