Association of Glucocorticoid Insensitivity with Increased Expression of Glucocorticoid Receptor β

In many chronic inflammatory disorders, glucocorticoid (GC) insensitivity is a challenging clinical problem associated with life-threatening disease progression. The molecular basis of GC insensitivity, however, is unknown. Alternative splicing of the GC receptor (R) pre–messenger RNA generates a second GCR, termed GCR-β, which does not bind GCs but antagonizes the transactivating activity of the classic GCR, termed GCR-α. In the current study, we demonstrate that GC-insensitive asthma is associated with a significantly higher number of GCR-β–immunoreactive cells in peripheral blood than GC-sensitive asthmatics or normal controls. Furthermore, we show that patients with GC-insensitive asthma have cytokine-induced abnormalities in the DNA binding capability of the GCR. These abnormalities can be reproduced by transfection of cell lines with the GCR-β gene resulting in significant reduction of their GCR-α DNA binding capacity. We conclude that increased expression of GCR-β is cytokine inducible and may account for GC insensitivity in this common inflammatory condition.