Direct effects of dexamethasone on human podocytes

• Published in: Kidney international Vol. 70; no. 6; pp. 1038 - 1045
• Main Authors: Xing, C.-Y., Saleem, M.A., Coward, R.J., Ni, L., Witherden, I.R., Mathieson, P.W.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.09.2006; Nature Publishing; Elsevier Limited
• Subjects: Antigens, Polyomavirus Transforming; Biological and medical sciences; Cell Line, Transformed; Cell Survival - drug effects; Cell Transformation, Viral; Child, Preschool; Cyclin-Dependent Kinase Inhibitor p21 - metabolism; dexamethasone; Dexamethasone - pharmacology; Dose-Response Relationship, Drug; Gene Expression Regulation - drug effects; Glomerulonephritis; Glucocorticoids - pharmacology; Humans; Immunohistochemistry; Interleukin-6 - metabolism; Medical sciences; Membrane Proteins - metabolism; nephrin; Nephrology. Urinary tract diseases; Nephropathies. Renovascular diseases. Renal failure; podocyte; Podocytes - drug effects; Simian virus 40; Simian virus 40 - immunology; steroid-sensitive nephrotic syndrome; Tubulin - metabolism; vascular endothelial growth factor; Vascular Endothelial Growth Factor A - metabolism; dexamethasone; nephrin; steroid-sensitive nephrotic syndrome; vascular endothelial growth factor; podocyte; Glomerulonephritis; Kidney disease; Human; Transmembrane protein; Steroid; Corticosteroid; Nephrology; Urinary system disease; Dexamethasone; Steroid hormone; Antiinflammatory agent; Nephrotic syndrome; Urology; Renal glomerulus; Direct method; Podocyte; Nephrin; Vascular endothelium growth factor; Urinary system
• ISSN: 0085-2538; 1523-1755
• DOI: 10.1038/sj.ki.5001655

Glucocorticoids are widely used in the treatment of human glomerular diseases, but their mode of action is poorly understood particularly in steroid-sensitive nephrotic syndrome, which is most common in childhood and is characterized by a lack of inflammation in the kidney. The podocyte is a key cell in the glomerulus in health and disease: until recently, human podocytes have been difficult to study in vitro. We have developed a conditionally immortalized human podocyte cell line transfected with a temperature-sensitive simian virus 40 transgene: when the transgene is inactivated in vitro, these cells adopt the phenotype of differentiated podocytes. We have used these cells to evaluate, using immunocytochemistry, reverse transcriptase-polymerase chain reaction, and Western blotting, direct effects of the glucocorticoid dexamethasone at concentrations designed to mimic in vivo therapeutic corticosteroid levels. Dexamethasone upregulated expression of nephrin and tubulin-α, and downregulated vascular endothelial growth factor. Effects on cell cycle were complex with downregulation of cyclin kinase inhibitor p21 and augmentation of podocyte survival, without any effect on apoptosis. We report cytokine production by human podocytes, especially interleukin (IL)-6 and -8; IL-6 expression was suppressed by dexamethasone. These potent direct effects on podocytes illustrate a novel mode of action of glucocorticoids and suggest potential new therapeutic strategies for glomerular disease.