Dexamethasone enhances basal and TNF-alpha-stimulated production of PAI-1 via the glucocorticoid receptor regardless of 11beta-hydroxysteroid dehydrogenase 2 status in human proximal renal tubular cells.
BACKGROUND
Long-term treatment with glucocorticoids (GCs) reportedly exaggerates renal fibrosis in chronic progressive inflammatory kidney disease. GCs induce the gene expression of plasminogen activator inhibitor-1 (PAI-1), a fibrosis enhancer in non-renal cells. Tumour necrosis factor-alpha (TNF-alpha) reduces the gene expression of 11beta-hydroxysteroid dehydrogenase (HSD) 2, an inactivator of GCs, and may enhance GC activity. However, the individual and collective effects of adrenal steroids, TNF-alpha and HSD2 status on PAI-1 production are unknown in human proximal renal tubular epithelial cells (HPTECs).


METHODS
Confluent HPTECs were treated with adrenal steroids (10 nM to 10 microM) or TNF-alpha (10 ng/ml) for up to 48 h. The mRNA amounts of the target genes were determined by TaqMan quantitative PCR, and the PAI-1 protein amounts were measured by an immunoassay.


RESULTS
Dexamethasone (DXA) maximally increased the amounts of PAI-1 mRNA and protein at 100 nM. Aldosterone (Ald) increased PAI-1 expression dose dependently, but the effect was over 100-fold weaker than that of DXA. The PAI-1-increasing effects of DXA and Ald were abolished completely by U-486, a specific inhibitor of the glucocorticoid receptor (GR) but not by spironolactone, a specific inhibitor of the mineralocorticoid receptor. The effect of DXA was also blocked partially by AG1478 and herbimycin A, tyrosine kinase inhibitors. DXA further increased TNF-alpha-stimulated PAI-1 expression via the GR. Although TNF-alpha treatment caused an 80% reduction in the gene expression of HSD2, an inactivator of GCs, HSD2 inhibition did not enhance DXA-induced PAI-1 production.


CONCLUSIONS
DXA induces basal and TNF-alpha-stimulated PAI-1 expression via the GR pathway, regardless of HSD2 status in HPTECs. Excess GCs may serve as a pro-fibrotic factor in chronic inflammatory kidney diseases.
Kimura
Hideki
H
Division of Nephrology, Department of General Medicine, School of Medicine, Faculty of Medical Sciences, University of Fukui, Fukui, Japan. hkimura@u-fukui.ac.jp
Li
Xuan
X
Torii
Kunio
K
Okada
Toshiharu
T
Kamiyama
Kazuko
K
Mikami
Daisuke
D
Takahashi
Naoki
N
Yoshida
Haruyoshi
H
D043209:11-beta-Hydroxysteroid Dehydrogenase Type 2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000450:Aldosterone / Q000494:pharmacology; D002478:Cells, Cultured; D003907:Dexamethasone / Q000009:adverse effects / Q000494:pharmacology*; D005355:Fibrosis; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000187:drug effects* / Q000378:metabolism* / Q000473:pathology; D017395:Plasminogen Activator Inhibitor 1 / Q000096:biosynthesis* / Q000235:genetics; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011799:Quinazolines; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000037:antagonists & inhibitors / Q000187:drug effects* / Q000378:metabolism*; D018161:Receptors, Mineralocorticoid / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D020032:Tyrphostins / Q000494:pharmacology
D017395:Plasminogen Activator Inhibitor 1; D011799:Quinazolines; D012333:RNA, Messenger; D011965:Receptors, Glucocorticoid; D018161:Receptors, Mineralocorticoid; C051321:SERPINE1 protein, human; D014409:Tumor Necrosis Factor-alpha; D020032:Tyrphostins; C101044:RTKI cpd; D000450:Aldosterone; D003907:Dexamethasone; D043209:11-beta-Hydroxysteroid Dehydrogenase Type 2; D011505:Protein-Tyrosine Kinases