title: Crosstalk between peroxisome proliferator-activated receptor-γ and mineralcorticoid receptor in TNF-α activated renal tubular cell.
abstract: BACKGROUND
  In our previous study, we observed the crosstalk between peroxisome proliferator-activated receptor-γ (PPAR-γ) and angiotensin II in activated renal tubular cells. The present study is aimed to further explore the crosstalk between PPAR-γ and mineralocorticoid receptor (MR) in tumor necrosis factor (TNF)-α activated renal tubular cells.
  
  
  METHODS
  Human proximal renal tubular epithelial cells HK-2 were cultured with the pre-treatment of PPAR-γ agonist, pioglitazone (5 μM), MR antagonist, eplerenone (5 μM), or their combined treatment, followed by activation with TNF-α (20 ng/ml). In the parallel experiment, PPAR-γ inhibitor GW9662 (25 µM) was used to study the independence of PPAR-γ. Gene expression and protein synthesis of intercellular adhesion molecule-1 (ICAM-1), interleukin-6 (IL-6), MR and PPAR-γ were measured by RT-PCR, ELISA and Western blot, respectively; nuclear factor κB (NF-κB) nuclear translocation activity in the nucleus was examined by EMSA assay.
  
  
  RESULTS
  TNF-α effectively activated HK-2 cells by up-regulating gene expression and protein synthesis of ICAM-1, IL-6 and MR and down-regulating PPAR-γ in a dose-dependent manner. TNF-α also significantly induced NF-κB nuclear translocation in HK-2 cells. Dual treatment of pioglitazone and eplerenone demonstrated synergistic effect on reducing ICAM-1 and IL-6 expression and alleviating NF-κB activation when compared with their monotherapies in TNF-α activated renal tubular cells. PPAR-γ antagonist, GW9662, significantly attenuated protective effect on ICAM-1, IL-6 and PPAR-γ expression by pioglitazone, eplerenone and their combined treatment.
  
  
  CONCLUSIONS
  Our data suggest that pioglitazone, in a PPAR-γ-dependent manner, trans-represses MR signaling by suppressing NF-κB activation. MR antagonist also restored PPAR-γ expression. Dual treatment of pioglitazone and eplerenone present better efficacy in attenuating excessive inflammatory response in activated renal tubular cells under stimulation of TNF-α than single treatment.
authors.affiliation: Department of Nephrology, Huadong Hospital Affiliated to Fudan University, Shanghai, People's Republic of China.
authors.forename: Jing
authors.initials: J
authors.lastname: Xiao
authors.forename: Weijun
authors.initials: W
authors.lastname: Chen
authors.forename: Yijun
authors.initials: Y
authors.lastname: Lu
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Zhang
authors.forename: Chensheng
authors.initials: C
authors.lastname: Fu
authors.forename: Zhenwen
authors.initials: Z
authors.lastname: Yan
authors.forename: Zhenxing
authors.initials: Z
authors.lastname: Zhang
authors.forename: Zhibin
authors.initials: Z
authors.lastname: Ye
mesh_terms: D000813:Anilides / Q000494:pharmacology; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D002460:Cell Line; D004357:Drug Synergism; D000077545:Eplerenone; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000166:cytology; D000451:Mineralocorticoid Receptor Antagonists / Q000494:pharmacology*; D016328:NF-kappa B / Q000378:metabolism; D047495:PPAR gamma / Q000819:agonists* / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D000077205:Pioglitazone; D018161:Receptors, Mineralocorticoid / Q000235:genetics / Q000378:metabolism; D013148:Spironolactone / Q000031:analogs & derivatives* / Q000494:pharmacology; D045162:Thiazolidinediones / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: C457499:2-chloro-5-nitrobenzanilide; D000813:Anilides; D000893:Anti-Inflammatory Agents; C508600:IL6 protein, human; D015850:Interleukin-6; D000451:Mineralocorticoid Receptor Antagonists; D016328:NF-kappa B; D047495:PPAR gamma; D018161:Receptors, Mineralocorticoid; D045162:Thiazolidinediones; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1; D013148:Spironolactone; D000077545:Eplerenone; D000077205:Pioglitazone