Interaction between glucocorticoids and beta2-agonists: alpha and beta glucocorticoid-receptor mRNA expression in human bronchial epithelial cells.
Recent studies have suggested that regular use of beta2-agonists has adverse effects on asthma control, due to the cross-talk between cAMP responsive element binding proteins (CREB) and glucocorticoid receptors (GR). The aim of this study was to investigate the interaction between GR and CREB on cytoplasmic protein level with a gel mobility shift assay and to determine the effect of this interaction on mRNA levels by Northern blot analysis. After exposing human bronchial epithelial cells for 1 hr to either 1 microM terbutaline or budesonide, more binding of CREB and GR, respectively, was observed to their responsive elements in DNA. Simultaneous exposure to terbutaline and budesonide also increased the binding of CREB and GR to DNA. After 4 hr, both alpha and beta GR mRNAs were down-regulated by 1 microM budesonide. Simultaneous addition of 1 microM terbutaline prevented this down-regulation. Adding 100 times more budesonide compared to terbutaline again down-regulated both GR forms, although significantly less compared to the down-regulation induced by 1 microM budesonide alone. Addition of terbutaline to cells already exposed to budesonide did not reverse the GR mRNA expression within 44 hr. Similar results were obtained with metallothionein-2 (MT2) mRNA levels. In conclusion, beta2-agonists interfere with the GR function in human bronchial epithelial cells when given simultaneously, with this being overcome by sequential exposure of the cells to first glucocorticoids and later beta2-agonists.
Korn
S H
SH
Department of Pulmonology, Maastricht University, The Netherlands.
Wouters
E F
EF
Wesseling
G
G
Arends
J W
JW
Thunnissen
F B
FB
D051698:Activating Transcription Factor 2; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D001980:Bronchi / Q000378:metabolism*; D019819:Budesonide / Q000494:pharmacology; D017362:Cyclic AMP Response Element-Binding Protein / Q000096:biosynthesis; D015536:Down-Regulation; D004347:Drug Interactions; D004847:Epithelial Cells / Q000378:metabolism*; D005938:Glucocorticoids / Q000494:pharmacology*; D006801:Humans; D008668:Metallothionein / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D011965:Receptors, Glucocorticoid / Q000096:biosynthesis* / Q000187:drug effects / Q000235:genetics; D013726:Terbutaline / Q000494:pharmacology; D014157:Transcription Factors / Q000096:biosynthesis