Glucocorticoid Receptor Isoforms α and β in in Vitro Cytokine-induced Glucocorticoid Insensitivity

A Torrego, L Pujols, J Roca-Ferrer, J Mullol… - American journal of …, 2004 - atsjournals.org
A Torrego, L Pujols, J Roca-Ferrer, J Mullol, A Xaubet, C Picado
American journal of respiratory and critical care medicine, 2004atsjournals.org
We stimulated peripheral blood mononuclear cells from 14 healthy subjects, 14 patients with
stable asthma, and 13 patients with unstable asthma with interleukin (IL)-2 and IL-4 to
induce glucocorticoid insensitivity and we examined the relationship between insensitivity
and the expression of glucocorticoid receptor (GR) isoforms. Results are expressed as IC50
(nanomolar) values (means±SD) in proliferation assays and as 103 cDNA molecules per
microgram of total RNA (means±SD) in real-time polymerase chain reaction analysis. Cells …
We stimulated peripheral blood mononuclear cells from 14 healthy subjects, 14 patients with stable asthma, and 13 patients with unstable asthma with interleukin (IL)-2 and IL-4 to induce glucocorticoid insensitivity and we examined the relationship between insensitivity and the expression of glucocorticoid receptor (GR) isoforms. Results are expressed as IC50 (nanomolar) values (means ± SD) in proliferation assays and as 103 cDNA molecules per microgram of total RNA (means ± SD) in real-time polymerase chain reaction analysis. Cells from patients with unstable asthma were less sensitive (316 ± 7 nM) to dexamethasone antiproliferative effects than those from healthy control subjects (102 ± 4 nM, p < 0.05) and patients with stable asthma (107 ± 2 nM, p < 0.05). Coincubation with IL-2 and IL-4 repressed the inhibitory effect of dexamethasone on proliferation in all groups (unstable: 851 ± 47 nM, p < 0.01; stable: 912 ± 52 nM, p = 0.001; control subjects: 537 ± 45 nM, p = 0.001). GR-α mRNA baseline expression was higher in patients with unstable asthma [(1.95 ± 0.40) × 103 cDNA molecules/μg total RNA, p < 0.05] than in patients with stable asthma [(1.46 ± 0.35) × 103 cDNA molecules/μg total RNA] and healthy subjects [(1.35 ± 0.25) × 103 cDNA molecules/μg total RNA]. GR-β mRNA was 600 times lower than GR-α in the three groups. Coincubation with IL-2 and IL-4 significantly increased GR-α mRNA expression in the three groups (p < 0.01), but caused no significant change in GR-β mRNA. GR-α, but not GR-β, protein was detected at baseline and after cytokine exposure. Our data do not support the hypothesis that increased GR-β expression can contribute to cytokine-induced glucocorticoid insensitivity.
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