title: p-cresyl sulphate has pro-inflammatory and cytotoxic actions on human proximal tubular epithelial cells.
abstract: BACKGROUND
  p-Cresyl sulphate (p-CS) and p-cresyl glucuronide (p-CG) are uraemic toxins that exhibit pro-inflammatory features in leukocytes and are associated with the progression of chronic kidney disease (CKD). Tubular cells are key targets of nephrotoxic agents and tubular cell death and activation contribute to the progression of CKD. However, the potential toxicity of these compounds on tubular cells is not fully understood. More specifically, apoptosis has never been studied.
  
  
  METHODS
  HK-2 human proximal tubular epithelial cells were studied. Cell death was evaluated by flow cytometry of DNA content and by morphology. Gene expression was studied by real-time (RT)-PCR. Protein expression was studied by western blot and flow cytometry.
  
  
  RESULTS
  Long-term (7 days) exposure to p-CS induced apoptosis in HK-2 cells in a concentration-dependent manner. In addition, short-term (3 h) exposure to p-CS promoted the expression of the TWEAK receptor Fn14, cooperated with TWEAK in promoting cell death and increased inflammatory gene expression. Albumin was cytotoxic and increased the inflammatory response to p-CS concentrations found in the circulation of non-dialysis CKD patients. In contrast, no biological actions of p-CG were observed on HK-2 cells, either alone or in combination with p-CS.
  
  
  CONCLUSIONS
  This study demonstrates for the first time that p-CS has pro-apoptotic and pro-inflammatory effects on tubular cells. These results identify mechanisms by which uraemic toxicity may contribute to CKD progression.
authors.affiliation: IIS-Fundacion Jimenez Diaz-UAM, Madrid, Spain.
authors.forename: Jonay
authors.initials: J
authors.lastname: Poveda
authors.forename: Maria D
authors.initials: MD
authors.lastname: Sanchez-Niño
authors.forename: Griet
authors.initials: G
authors.lastname: Glorieux
authors.forename: Ana B
authors.initials: AB
authors.lastname: Sanz
authors.forename: Jesús
authors.initials: J
authors.lastname: Egido
authors.forename: Raymond
authors.initials: R
authors.lastname: Vanholder
authors.forename: Alberto
authors.initials: A
authors.lastname: Ortiz
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D016923:Cell Death / Q000502:physiology; D002478:Cells, Cultured; D003408:Cresols / Q000494:pharmacology*; D018450:Disease Progression; D004847:Epithelial Cells / Q000378:metabolism; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D051436:Renal Insufficiency, Chronic / Q000378:metabolism; D013463:Sulfuric Acid Esters / Q000494:pharmacology*; D000074050:TWEAK Receptor
chemical_list: D003408:Cresols; D018124:Receptors, Tumor Necrosis Factor; D013463:Sulfuric Acid Esters; C000613297:TNFRSF12A protein, human; D000074050:TWEAK Receptor; C408690:4-cresol sulfate
keywords: apoptosis; cell death; fn14; inflammation; tweak; uraemic toxins