title: The parietal epithelial cell is crucially involved in human idiopathic focal segmental glomerulosclerosis.
abstract: BACKGROUND
  Focal segmental glomerulosclerosis (FSGS) is one of the most common patterns of glomerular injury encountered in human renal biopsies. Epithelial hyperplasia, which can be prominent in FSGS, has been attributed to dedifferentiation and proliferation of podocytes. Based on observations in a mouse model of FSGS, we pointed to the role of parietal epithelial cells (PECs). In the present study we investigated the relative role of PECs and podocytes in human idiopathic FSGS.
  
  
  METHODS
  We performed a detailed study of lesions from a patient with recurrent idiopathic FSGS by serial sectioning, marker analysis and three-dimensional reconstruction of glomeruli. We have studied the expression of markers for podocytes, PECs, mesangial cells, endothelium, and myofibroblasts. We also looked at proliferation and composition of the deposited extracellular matrix (ECM).
  
  
  RESULTS
  We found that proliferating epithelial cells in FSGS lesions are negative for podocyte and macrophage markers, but stain for PEC markers. The composition of the matrix deposited by these cells is identical to Bowman's capsule.
  
  
  CONCLUSIONS
  Our study demonstrates that PECs are crucially involved in the pathogenesis of FSGS lesions.
authors.affiliation: Department of Pathology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. h.dijkman@pathol.umcn.nl
authors.forename: Henry
authors.initials: H
authors.lastname: Dijkman
authors.forename: Bart
authors.initials: B
authors.lastname: Smeets
authors.forename: Jeroen
authors.initials: J
authors.lastname: van der Laak
authors.forename: Eric
authors.initials: E
authors.lastname: Steenbergen
authors.forename: Jack
authors.initials: J
authors.lastname: Wetzels
mesh_terms: D001706:Biopsy; D050476:Bowman Capsule / Q000473:pathology*; D002648:Child; D004847:Epithelial Cells / Q000473:pathology* / Q000648:ultrastructure; D005923:Glomerulosclerosis, Focal Segmental / Q000473:pathology* / Q000601:surgery; D006801:Humans; D007678:Kidney Glomerulus / Q000473:pathology; D016030:Kidney Transplantation; D008297:Male; D046529:Microscopy, Electron, Transmission; D050199:Podocytes / Q000473:pathology / Q000648:ultrastructure; D014184:Transplantation, Homologous; D019459:Urothelium / Q000473:pathology*