title: Podoplanin-positive cells are a hallmark of encapsulating peritoneal sclerosis.
abstract: BACKGROUND
  Encapsulating peritoneal sclerosis (EPS) and simple peritoneal sclerosis are important complications of long-term peritoneal dialysis (PD). Podoplanin is expressed by mesothelial cells and lymphatic vessels, which are involved in inflammatory reactions in the peritoneal cavity.
  
  
  METHODS
  We studied 69 peritoneal biopsies from patients on PD (n = 16), patients with EPS (n = 18) and control biopsies taken at the time of hernia repair (n = 15) or appendectomy (n = 20). Immunohistochemistry was performed to localize podoplanin. Additionally, markers of endothelial cells, mesothelial cells, myofibroblasts (smooth muscle actin), proliferating cells, and double labelling for smooth muscle actin/podoplanin were used on selected biopsies.
  
  
  RESULTS
  Podoplanin was present on the endothelium of lymphatic vessels in the submesothelial fibrous tissue and on mesothelial cells. In patients on PD and in biopsies with appendicitis, the mesothelial cells demonstrated a cuboidal appearance and circumferential podoplanin staining, with gaps between the cells. The number of lymphatic vessels was variable, but prominent at sites of fibrosis. In patients with EPS, a diffuse infiltration of podoplanin-positive cells with a fibroblastic appearance was present in 15 out of 18 biopsies. This pattern was focally present in 3 out of 16 on PD and none in the 35 controls. The podoplanin-positive cells did not express the endothelial marker or the mesothelial marker (calretinin).
  
  
  CONCLUSIONS
  EPS is characterized by a population of podoplanin and smooth muscle actin double-positive cells. Podoplanin might be a suitable morphological marker supporting the diagnosis and might be involved in the pathogenesis of EPS.
authors: Department of Internal Medicine, Division of General Internal Medicine and Nephrology, Robert-Bosch-Hospital, Stuttgart, Germany.
authors: Niko
authors: N
authors: Braun
authors: Dominik M
authors: DM
authors: Alscher
authors: Peter
authors: P
authors: Fritz
authors: Ilka
authors: I
authors: Edenhofer
authors: Martin
authors: M
authors: Kimmel
authors: Ariana
authors: A
authors: Gaspert
authors: Fabian
authors: F
authors: Reimold
authors: Beata
authors: B
authors: Bode-Lesniewska
authors: Urs
authors: U
authors: Ziegler
authors: Dagmar
authors: D
authors: Biegger
authors: Rudolf P
authors: RP
authors: Wüthrich
authors: Stephan
authors: S
authors: Segerer
mesh_terms: D000328:Adult; D001062:Appendectomy / Q000009:adverse effects; D001706:Biopsy; D016022:Case-Control Studies; D005260:Female; D005455:Fluorescent Antibody Technique; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006547:Hernia / Q000150:complications / Q000628:therapy; D006801:Humans; D007124:Immunoenzyme Techniques; D008208:Lymphatic System; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008875:Middle Aged; D058628:Myofibroblasts / Q000378:metabolism; D010530:Peritoneal Dialysis / Q000009:adverse effects*; D056627:Peritoneal Fibrosis / Q000175:diagnosis* / Q000209:etiology* / Q000378:metabolism; D011379:Prognosis; D012307:Risk Factors; D000098853:Podoplanin
chemical_list: D008562:Membrane Glycoproteins; C117468:PDPN protein, human; D000098853:Podoplanin