title: Fetuin, matrix-Gla protein and osteopontin in calcification of renal allografts.
abstract: BACKGROUND
  Calcification of renal allografts is common in the first year after transplantation and is related to hyperparathyroidism. It is associated with an impaired long-term function of the graft (Am J Transplant 5∶1934-41, 2005). Aim of this study is to examine the role of the anti-calcifying/calcifying factors in the pathophysiology of renal allograft calcification.
  
  
  METHODS
  We analyzed protocol allograft biopsies, blood and urine samples of 31 patients with and 27 patients without allograft calcification taken at 6 weeks, 3 and 6 months after transplantation. Patient demographical data, cold ischemia time, initial graft function and donor characteristics were comparable between the two groups. Biopsies were stained for osteopontin, fetuin, and matrix-gla-protein. Serum and urine electrolytes, matrix-gla-protein, fetuin, Vitamin D and intact parathyroid hormone in serum and osteopontin (OPN) in urine were examined.
  
  
  RESULTS
  Serum levels of fetuin and matrix-Gla protein as well as urinary levels of OPN showed specific time dependent changes (6 weeks vs. 3 months vs. 6 months; all p<0.0001). In patients with calcifications, urinary levels of OPN were decreased by 55% at 6 weeks and increased thereafter, showing 54% higher levels at 6 months compared to patients without calcification (6 weeks: p<0.01, 6 months: p<0.05). Local protein expression of fetuin-A, matrix-Gla protein and OPN in the graft was specifically increased around calcified plaques, without differences in the mRNA tissue expression.
  
  
  CONCLUSIONS
  Anticalcifying factors show significant changes in the early phase after renal transplantation, which may be important for the prevention of allograft calcification. The differences in OPN indicate an involvement of this factor in the regulation of calcification.
authors.affiliation: Department of Medicine, Division of Nephrology & Hypertension, Hanover Medical School, Hannover, Germany.
authors.forename: Johan M
authors.initials: JM
authors.lastname: Lorenzen
authors.forename: Filippo
authors.initials: F
authors.lastname: Martino
authors.forename: Irina
authors.initials: I
authors.lastname: Scheffner
authors.forename: Verena
authors.initials: V
authors.lastname: Bröcker
authors.forename: Holger
authors.initials: H
authors.lastname: Leitolf
authors.forename: Hermann
authors.initials: H
authors.lastname: Haller
authors.forename: Wilfried
authors.initials: W
authors.lastname: Gwinner
mesh_terms: D002114:Calcinosis / Q000097:blood / Q000378:metabolism* / Q000652:urine; D002118:Calcium / Q000097:blood; D002135:Calcium-Binding Proteins / Q000097:blood / Q000378:metabolism*; D004573:Electrolytes / Q000097:blood / Q000652:urine; D016326:Extracellular Matrix Proteins / Q000097:blood / Q000378:metabolism*; D060748:Fetuins / Q000378:metabolism*; D006801:Humans; D007674:Kidney Diseases / Q000097:blood / Q000378:metabolism* / Q000652:urine; D016030:Kidney Transplantation; D053495:Osteopontin / Q000097:blood / Q000378:metabolism* / Q000652:urine; D010281:Parathyroid Hormone / Q000097:blood; D014184:Transplantation, Homologous; D014807:Vitamin D / Q000097:blood; D000097568:Matrix Gla Protein
chemical_list: D002118:Calcium; D002135:Calcium-Binding Proteins; D004573:Electrolytes; D016326:Extracellular Matrix Proteins; D060748:Fetuins; D053495:Osteopontin; D010281:Parathyroid Hormone; D014807:Vitamin D; D000097568:Matrix Gla Protein