title: Retinoids augment the expression of podocyte proteins by glomerular parietal epithelial cells in experimental glomerular disease.
abstract: OBJECTIVE
  A decrease in glomerular podocyte number in membranous nephropathy and focal segmental glomerulosclerosis (FSGS) ultimately underlines glomerulosclerosis and the decrease in kidney function. Recent studies have shown that in these diseases, glomerular parietal epithelial cells begin to express proteins considered unique to podocytes, and that these glomerular epithelial transition cells might serve as podocyte progenitors. Because retinoids improve many forms of experimental glomerular disease characterized by podocyte injury and loss, we asked if all-trans retinoic acid (ATRA) induces parietal epithelial cells to express podocyte proteins.
  
  
  METHODS
  ATRA or vehicle was administered to rats with experimental membranous nephropathy (passive Heymann nephritis model) and mice with experimental FSGS (anti-glomerular antibody model) following the onset of proteinuria. Immunohistochemistry staining of PAX2 (parietal epithelial cell marker), WT-1 (podocyte cell marker), and Ki-67 (proliferation marker) were performed on kidney tissues.
  
  
  RESULTS
  Compared to diseased animals receiving vehicle, ATRA statistically significantly increased the number of glomerular transition cells, defined as cells double-staining for PAX2 and WT-1, in membranous nephropathy at weeks 2, 5 and 16, and in FSGS at weeks 1 and 2. This was accompanied by an increase in the number of podocytes compared to diseased controls receiving vehicle.
  
  
  CONCLUSIONS
  ATRA increases the number of glomerular epithelial transition cells in experimental proteinuric glomerular diseases. Thus, ATRA may provide a useful pharmacologic approach to decipher the mechanisms underlying the possible progenitor role of parietal epithelial cells.
authors.affiliation: Division of Nephrology, Department of Medicine, University of Washington School of Medicine, Seattle, Wash 98195-6521, USA.
authors.forename: Jiong
authors.initials: J
authors.lastname: Zhang
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Pippin
authors.forename: Michael R
authors.initials: MR
authors.lastname: Vaughan
authors.forename: Ronald D
authors.initials: RD
authors.lastname: Krofft
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Taniguchi
authors.forename: Paola
authors.initials: P
authors.lastname: Romagnani
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Nelson
authors.forename: Zhi-Hong
authors.initials: ZH
authors.lastname: Liu
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Shankland
mesh_terms: D000818:Animals; D015433:Glomerulonephritis, Membranous / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D019394:Ki-67 Antigen / Q000378:metabolism*; D008297:Male; D051379:Mice; D051762:PAX2 Transcription Factor / Q000378:metabolism*; D050199:Podocytes / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D016896:Treatment Outcome; D014212:Tretinoin / Q000008:administration & dosage*; D015854:Up-Regulation / Q000187:drug effects; D025721:WT1 Proteins / Q000378:metabolism*
chemical_list: D019394:Ki-67 Antigen; D051762:PAX2 Transcription Factor; C551986:PAX2 protein, rat; D025721:WT1 Proteins; D014212:Tretinoin