Recent studies indicate that chronic
asthma is associated with a spectrum of
glucocorticoid receptor (GCR) binding abnormalities that are
cytokine-inducible. These GCR abnormalities may contribute to poor
asthma control and failure to respond to
glucocorticoid (GC)
therapy. The purpose of this study was to determine whether GCR defects are associated with poorly controlled
asthma, and whether diminished GCR binding is reversible following a course of GC
therapy. We enrolled 12 patients with poorly controlled
asthma characterized by nocturnal awakening with
cough or
wheezing, AM FEV1 < 70%, or FEV1 variability of > 25% requiring a short course of high dose GC
therapy. GCR binding affinity was measured in peripheral blood mononuclear cells using a radioligand binding assay before and after the GC course. Spirometry, serum
cortisol,
eosinophil cationic protein (ECP), and soluble
IL-2 receptor (sIL-2R) levels were also performed before and after the GC course. At baseline, all subjects had airflow obstruction that significantly improved (median FEV1 increased from 65.0% to 89.5% of predicted, median FEV1/FVC ratio increased from 0.60 to 0.72) with
therapy. A diminished GCR binding affinity at baseline was noted with an elevated median dissociation constant (Kd) of 29.0 nM (interquartile range at the 25th and 75th percentile [IQ] of 22.3 and 44.5 nM) compared with normal controls (Kd 8.0 nM [IQ 7.0, 9.2]). Following the GC course, a significant decrease in the Kd was seen. Serum ECP and sIL-2R levels at baseline were elevated, with serum ECP demonstrating a significant reduction following the GC course.(ABSTRACT TRUNCATED AT 250 WORDS)