title: Parietal epithelia cells in the urine as a marker of disease activity in glomerular diseases.
abstract: BACKGROUND
  The detection of viable podocytes in the urine of patients with proteinuric diseases has been described as a non-invasive method to monitor disease activity. Most of the published studies use podocalyxin (PDX) as a podocyte specific marker.
  
  
  METHODS
  We examined the excretion of viable PDX-positive cells in a random set of spot urine from patients with biopsy-proven focal segmental glomerulosclerosis (FSGS), membranous nephropathy (MGN) or membranoproliferative glomerulonephritis (MPGN) and characterized the excreted cells for podocyte and parietal epithelia markers as well as for proliferation activity.
  
  
  RESULTS
  We found that untreated patients with active disease excrete high numbers of PDX-positive cells in their urine. In contrast to that we were not able to detect significant amounts of PDX-positive cells in the urine of patients with active minimal change disease (MCD) and patients with FSGS or MGN in full remission. When we further characterized the cells we rarely detected expression of podocyte specific markers in the PDX-positive cells, but at least 50% of the PDX-positive cells were double positive for cytokeratin (CK8-18). Immunohistochemistry of the corresponding renal biopsies showed that 100% of podocytes and parietal cells stained positive for PDX. Semiquantitative analysis revealed that 45% of parietal cells were positive for CK8-18 and 100% of proximal tubular cells. No cells of the glomerular epithelial layer stained positive for CK8-18.
  
  
  CONCLUSIONS
  PDX-positive cells are lost in the urine in disease states that require podocyte regeneration and are a useful non-invasive marker for glomerular disease activity. These cells are possibly derived from the parietal epithelial layer.
authors.affiliation: Mario Schiffer, Division of Nephrology, Department of Medicine, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Achenbach
authors.forename: Michael
authors.initials: M
authors.lastname: Mengel
authors.forename: Irini
authors.initials: I
authors.lastname: Tossidou
authors.forename: Imke
authors.initials: I
authors.lastname: Peters
authors.forename: Joon-Keun
authors.initials: JK
authors.lastname: Park
authors.forename: Marion
authors.initials: M
authors.lastname: Haubitz
authors.forename: Jochen H
authors.initials: JH
authors.lastname: Ehrich
authors.forename: Hermann
authors.initials: H
authors.lastname: Haller
authors.forename: Mario
authors.initials: M
authors.lastname: Schiffer
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D015432:Glomerulonephritis, Membranoproliferative / Q000378:metabolism / Q000473:pathology / Q000652:urine*; D015433:Glomerulonephritis, Membranous / Q000378:metabolism / Q000473:pathology / Q000652:urine*; D005923:Glomerulosclerosis, Focal Segmental / Q000378:metabolism / Q000473:pathology / Q000652:urine*; D006801:Humans; D007633:Keratins / Q000378:metabolism; D007668:Kidney / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D050199:Podocytes / Q000378:metabolism / Q000473:pathology*; D012795:Sialoglycoproteins / Q000378:metabolism; D013194:Staining and Labeling; D014556:Urine / Q000166:cytology; D055815:Young Adult
chemical_list: D012795:Sialoglycoproteins; C001643:podocalyxin; D007633:Keratins