title: Upregulation of transglutaminase and ε (γ-glutamyl)-lysine in the Fisher-Lewis rat model of chronic allograft nephropathy.
abstract: BACKGROUND
  Tissue transglutaminase (TG2), a cross-linking enzyme, modulates deposition of extracellular matrix protein in renal fibrosis. This study aimed to examine TG2 and its cross-link product ε(γ-glutamyl)-lysine in the Fisher-Lewis rat renal transplantation (RTx) model of chronic allograft nephropathy (CAN).
  
  
  METHODS
  Left renal grafts from male Fisher and Lewis were transplanted into Lewis rats, generating allografts and isografts, respectively. Blood pressure, renal function, and proteinuria were monitored for up to 52 weeks. At termination, CAN was assessed in the renal tissue by light and electron microscopy, TG2 and ε(γ-glutamyl)-lysine by immunofluorescence, and the urinary ε(γ-glutamyl)-lysine by high performance liquid chromatography.
  
  
  RESULTS
  Compared to the isograft, the allografts were hypertensive, proteinuric, and uraemic and developed CAN. Extracellular TG2 (glomerulus: 64.55 ± 17.61 versus 2.11 ± 0.17, P < 0.001; interstitium: 13.72 ± 1.62 versus 3.19 ± 0.44, P < 0.001), ε(γ-glutamyl)-lysine (glomerulus: 21.74 ± 2.71 versus 1.98 ± 0.37, P < 0.01; interstitium: 37.96 ± 17.06 versus 0.42 ± 0.11, P < 0.05), TG2 enzyme activity (1.09 ± 0.13 versus 0.41 ± 0.03 nmol/h/mg protein, P < 0.05), TG2 mRNA (20-fold rise), and urinary ε(γ-glutamyl)-lysine (534.2 ± 198.4 nmol/24 h versus 57.2 ± 4.1 nmol/24 h, P < 0.05) levels were significantly elevated in the allografts and showed a positive linear correlation with tubulointerstitial fibrosis.
  
  
  CONCLUSIONS
  CAN was associated with upregulation of renal TG2 pathway, which has a potential for pharmacological intervention. The elevated urinary ε(γ-glutamyl)-lysine, measured for the first time in RTx, is a potential biomarker of CAN.
authors.affiliation: Division of Renal Transplantation, Sheffield Kidney Institute, Northern General Hospital, Herries Road, Sheffield S5 7AU, UK.
authors.forename: Badri
authors.identifier: 0000-0002-7309-7080
authors.initials: B
authors.lastname: Shrestha
authors.affiliation: Division of Renal Transplantation, Sheffield Kidney Institute, Northern General Hospital, Herries Road, Sheffield S5 7AU, UK.
authors.forename: Imran
authors.initials: I
authors.lastname: Butt
authors.affiliation: Academic Nephrology Unit, Medical School, University of Sheffield, Sheffield S10 2RX, UK.
authors.forename: Michelle
authors.initials: M
authors.lastname: Da Silva
authors.affiliation: Academic Nephrology Unit, Medical School, University of Sheffield, Sheffield S10 2RX, UK.
authors.forename: Armando
authors.initials: A
authors.lastname: Sanchez-Lara
authors.affiliation: Division of Renal Transplantation, Sheffield Kidney Institute, Northern General Hospital, Herries Road, Sheffield S5 7AU, UK.
authors.forename: Bart
authors.identifier: 0000-0003-1244-3063
authors.initials: B
authors.lastname: Wagner
authors.affiliation: Division of Renal Transplantation, Sheffield Kidney Institute, Northern General Hospital, Herries Road, Sheffield S5 7AU, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Raftery
authors.affiliation: Academic Nephrology Unit, Medical School, University of Sheffield, Sheffield S10 2RX, UK.
authors.forename: Timothy
authors.initials: T
authors.lastname: Johnson
authors.affiliation: Academic Nephrology Unit, Medical School, University of Sheffield, Sheffield S10 2RX, UK.
authors.forename: John
authors.identifier: 0000-0001-7385-1197
authors.initials: J
authors.lastname: Haylor
mesh_terms: D064591:Allografts; D000818:Animals; D002908:Chronic Disease; D003432:Cross-Linking Reagents / Q000378:metabolism; D004151:Dipeptides / Q000378:metabolism* / Q000652:urine; D004195:Disease Models, Animal; D005455:Fluorescent Antibody Technique; D019204:GTP-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D007674:Kidney Diseases / Q000097:blood / Q000201:enzymology* / Q000209:etiology* / Q000503:physiopathology; D007678:Kidney Glomerulus / Q000473:pathology / Q000648:ultrastructure; D016030:Kidney Transplantation / Q000009:adverse effects*; D008297:Male; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011916:Rats, Inbred F344; D011917:Rats, Inbred Lew; D011503:Transglutaminases / Q000235:genetics* / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D003432:Cross-Linking Reagents; D004151:Dipeptides; D012333:RNA, Messenger; C000717609:Tgm2 protein, rat; C001299:epsilon-(gamma-glutamyl)-lysine; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D019204:GTP-Binding Proteins