title: Urea-induced ROS cause endothelial dysfunction in chronic renal failure.
abstract: OBJECTIVE
  The pathogenic events responsible for accelerated atherosclerosis in patients with chronic renal failure (CRF) are poorly understood. Here we investigate the hypothesis that concentrations of urea associated with CRF and increased ROS production in adipocytes might also increase ROS production directly in arterial endothelial cells, causing the same pathophysiologic changes seen with hyperglycemia.
  
  
  METHODS
  Primary cultures of human aortic endothelial cells (HAEC) were exposed to 20mM urea for 48 h. C57BL/6J wild-type mice underwent 5/6 nephrectomy or a sham operation. Randomized groups of 5/6 nephrectomized mice and their controls were also injected i.p. with a SOD/catalase mimetic (MnTBAP) for 15 days starting immediately after the final surgical procedure.
  
  
  RESULTS
  Urea at concentrations seen in CRF induced mitochondrial ROS production in cultured HAEC. Urea-induced ROS caused the activation of endothelial pro-inflammatory pathways through the inhibition of GAPDH, including increased protein kinase C isoforms activity, increased hexosamine pathway activity, and accumulation of intracellular AGEs (advanced glycation end products). Urea-induced ROS directly inactivated the anti-atherosclerosis enzyme PGI2 synthase and also caused ER stress. Normalization of mitochondrial ROS production prevented each of these effects of urea. In uremic mice, treatment with MnTBAP prevented aortic oxidative stress, PGI2 synthase activity reduction and increased expression of the pro-inflammatory proteins TNFα, IL-6, VCAM1, Endoglin, and MCP-1.
  
  
  CONCLUSIONS
  Taken together, these data show that urea itself, at levels common in patients with CRF, causes endothelial dysfunction and activation of proatherogenic pathways.
authors: Institute of Pediatrics, University of Foggia, Foggia Viale Pinto 1, O.O.R.R., Foggia, Italy.
authors: Maria
authors: M
authors: D'Apolito
authors: Diabetes Research Center, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York, 10461, USA.
authors: Xueliang
authors: X
authors: Du
authors: Department of Clinical and Experimental Medicine, University of Foggia, Viale Pinto 1, O.O.R.R., Foggia, Italy.
authors: Daniela
authors: D
authors: Pisanelli
authors: Institute of Pediatrics, University of Foggia, Foggia Viale Pinto 1, O.O.R.R., Foggia, Italy.
authors: Massimo
authors: M
authors: Pettoello-Mantovani
authors: Institute of Pediatrics, University of Foggia, Foggia Viale Pinto 1, O.O.R.R., Foggia, Italy.
authors: Angelo
authors: A
authors: Campanozzi
authors: Diabetes Research Center, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York, 10461, USA.
authors: Ferdinando
authors: F
authors: Giacco
authors: Department of Clinical and Experimental Medicine, University of Foggia, Viale Pinto 1, O.O.R.R., Foggia, Italy.
authors: Angela Bruna
authors: AB
authors: Maffione
authors: Department of Clinical and Experimental Medicine, University of Foggia, Viale Pinto 1, O.O.R.R., Foggia, Italy.
authors: Anna Laura
authors: AL
authors: Colia
authors: Diabetes Research Center, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York, 10461, USA.
authors: Michael
authors: M
authors: Brownlee
authors: Department of Clinical and Experimental Medicine, University of Foggia, Viale Pinto 1, O.O.R.R., Foggia, Italy. Electronic address: ida.giardino@unifg.it.
authors: Ida
authors: I
authors: Giardino
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D001011:Aorta / Q000378:metabolism; D050197:Atherosclerosis / Q000201:enzymology / Q000378:metabolism / Q000503:physiopathology; D002374:Catalase / Q000378:metabolism; D018932:Chemokine CCL2 / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D000071063:Endoglin; D042783:Endothelial Cells / Q000378:metabolism; D004727:Endothelium / Q000201:enzymology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000473:pathology*; D024581:Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating) / Q000378:metabolism; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D019746:Intramolecular Oxidoreductases / Q000378:metabolism; D007676:Kidney Failure, Chronic / Q000139:chemically induced / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018384:Oxidative Stress; D011897:Random Allocation; D017382:Reactive Oxygen Species / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D014508:Urea / Q000737:chemistry*; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism
chemical_list: D015703:Antigens, CD; C111835:CCL2 protein, human; D018932:Chemokine CCL2; C064206:ENG protein, human; D000071063:Endoglin; C508600:IL6 protein, human; D015850:Interleukin-6; D017382:Reactive Oxygen Species; D011956:Receptors, Cell Surface; D014409:Tumor Necrosis Factor-alpha; D019010:Vascular Cell Adhesion Molecule-1; D014508:Urea; D003577:Cytochrome P-450 Enzyme System; D002374:Catalase; D013482:Superoxide Dismutase; D024581:Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating); D019746:Intramolecular Oxidoreductases; C022461:prostacyclin synthetase
keywords: CRF; Endothelial cells; GlcNAc; MnTBAP; O-linked-N-acetylglucosamine; Prostacyclin synthase; ROS; UCP-1; Urea; chronic renal failure; manganese tetrakis (4-benzoic acid) porphyrin; reactive oxygen species; uncoupling protein 1