Wendy Surs

Steroid-resistant asthma: Immunologic and pharmacologic features

Glucocorticoids play an important role in asthma therapy; however, a subset of patients are poorly responsive. We evaluated immunologic and pharmacologic features of 17 patients with steroid-resistant (SR) asthma (six male and 11 female patients) between the ages of 16 and 69 years (mean age, 29 years). SR asthma was defined as failure to improve morning prebronchodilator FEV1 greater than 60% predicted after a 2-week course of oral prednisone (mean dose, 45 mg/day). These patients were compared to 24 steroid-sensitive (SS) patients, aged 5 to 70 years (mean age, 17 years; 17 male and seven female patients), and 47 healthy control subjects, aged 20 to 40 years. Mean prednisone dose in SS patients was 25 mg/day. Steroid pharmacokinetics were evaluated in six patients with SR asthma. All studies were within normal limits. Peripheral blood mononuclear cells (PBMCs) from all subjects were stimulated with 10 micrograms/ml of phytohemagglutinin and incubated for 72 hours with 10(-5) to 10(-9) mol/L of methylprednisolone (Mpn). The Mpn dose-response curve for PBMCs from patients with SR asthma demonstrated a significant (p less than 0.05) increase in DNA synthesis, that is, more T cell proliferation than PBMCs stimulated with phytohemagglutinin in the presence of Mpn, as compared to SS patients and normal subjects. This augmentation of DNA synthesis was reversible with 10 micrograms/ml of troleandomycin in vitro. We conclude that PBMCs from patients with SR asthma demonstrate altered response to Mpn in the presence of a T cell mitogen. This abnormality in cellular response may contribute to persistent airway inflammation in patients with SR asthma despite glucocorticoid therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma histamine, epinephrine, cortisol, and leukocyte β‐adrenergic receptors in nocturnal asthma

Plasma histamine, cortisol, epinephrine, cyclic adenosine monophosphate (cAMP), and leukocyte β‐adrenergic receptors were measured in asthmatic patients with (n = 7) and without (n = 10) nocturnal asthma at 4 PM and 4 AM and compared with those of normal subjects (n = 10). A twofold higher plasma histamine concentration was observed at 4 AM compared with 4 PM in all groups, with no change in plasma cortisol, epinephrine, and cAMP concentrations. At 4 AM compared with 4 PM, only patients with nocturnal asthma had a significant 33% decrease (p < 0.05) in mononuclear and polymorphonuclear leukocyte β‐adrenergic receptor density, with no difference in binding affinity in all three groups. Polymorphonuclear leukocytes from patients with nocturnal asthma had significantly impaired response to iso‐proterenol at 4 AM (17% ± 7.3% SEM increase in cAMP; p < 0.05) compared with those of patients without nocturnal asthma (69.4% ± 13.7%) and normal (80.2% ± 21.3%) subjects. A significant change in β‐adrenergic receptor density and function occurs at night in patients with nocturnal asthma.

Effects of glucocorticoids on lymphocyte activation in patients with steroid-sensitive and steroid-resistant asthma

BACKGROUND Glucocorticoids are important medications used to control the airway inflammation associated with asthma. Synthetic glucocorticoids vary in their binding affinity for the glucocorticoid receptor (GCR). METHODS We compared hydrocortisone, beclomethasone dipropionate, triamcinolone acetonide, flunisolide, and budesonide with regard to their capacity to inhibit phytohemagglutinin-induced peripheral blood mononuclear cell proliferation from six patients with steroid-sensitive asthma and seven patients with steroid-resistant asthma. Peripheral blood mononuclear cell GCR binding affinities for dexamethasone and budesonide were also determined for both patient groups by using a radioligand binding assay and Scatchard analysis. RESULTS Dose-dependent inhibition was demonstrated for all glucocorticoids in both patient groups, with the steroid-resistant group requiring approximately 2 log-fold more glucocorticoids for an equivalent degree of inhibition. The mean concentrations necessary to cause 50% inhibition of lymphocyte proliferation (IC50s) for the steroid-sensitive group ranged from 2 x 10(-10) mol/L for budesonide to 7 x 10(-8) mol/L for hydrocortisone, whereas the mean IC50s for the steroid-resistant group ranged from approximately 2 x 10(-8) mol/L for budesonide to greater than 10(-6) mol/L for hydrocortisone. In addition, a significant correlation was noted between the degree of inhibition of lymphocyte proliferation (IC50) and the binding affinity of dexamethasone to the GCR. Patients with steroid-resistant asthma have been shown to have a reduced GCR binding affinity. The GCR binding affinity for budesonide was significantly higher in both groups (i.e., lower dissociation constant) than that obtained for dexamethasone. CONCLUSION These data suggest that glucocorticoids such as budesonide, by virtue of their high GCR binding affinities and greater ability to suppress lymphocyte proliferation, may therefore be beneficial in the management of difficult-to-control asthma.

Coexistence of glucocorticoid receptor and pharmacokinetic abnormalities: Factors that contribute to a poor response to treatment with glucocorticoids in children with asthma

Rapid glucocorticoid clearance and abnormal glucocorticoid receptor binding have been described as factors that contribute to an inadequate response to treatment with glucocorticoids in patients with asthma. We report the coexistence of these abnormalities in children with severe asthma who respond poorly to systemic glucocorticoid therapy.