title: Exaggerated renal fibrosis in P2X4 receptor-deficient mice following unilateral ureteric obstruction.
abstract: BACKGROUND
  The ATP-sensitive P2X7 receptor (P2X7R) has been shown to contribute to renal injury in nephrotoxic nephritis, a rodent model of acute glomerulonephritis, and in unilateral ureteric obstruction (UUO), a rodent model of chronic interstitial inflammation and fibrosis. Renal tubular cells, endothelial cells and macrophages also express the closely related P2X4 receptor (P2X4R), which is chromosomally co-located with P2X7R and has 40% homology; it is also pro-inflammatory and has been shown to interact with P2X7R to modulate its pro-apoptotic and pro-inflammatory effects. Therefore, we chose to explore the function of P2X4R in the UUO model of renal injury using knockout mice. We hypothesized that UUO-induced tubulointerstitial damage and fibrosis would also be attenuated in P2X4R(-/-) mice.
  
  
  METHODS
  P2X4R(-/-) and wild-type (WT) mice were subjected to either UUO or sham operation. Kidney samples taken on Days 7 and 14 were evaluated for renal inflammation and fibrosis, and expression of pro-fibrotic factors.
  
  
  RESULTS
  To our surprise, the obstructed kidney in P2X4R(-/-) mice showed more severe renal injury, more collagen deposition (picrosirius red staining, increase of 53%; P < 0.05) and more type I collagen staining (increase of 107%; P < 0.01), as well as increased mRNA for TGF-β (increase of 102%, P < 0.0005) and CTGF (increase of 157%; P < 0.05) by Day 14, compared with the UUO WT mice.
  
  
  CONCLUSIONS
  These findings showed that lack of P2X4R expression leads to increased renal fibrosis, and increased expression of TGF-β and CTGF in the UUO model.
authors.affiliation: Imperial College Renal and Transplant Centre, Hammersmith Hospital, Imperial College London, London, UK Clinic for Transplantations immunology and Nephrology, University Hospital Basel, Basel, Switzerland Department of Biomedicine, Molecular Nephrology, University Hospital Basel, Basel, Switzerland.
authors.forename: Min Jeong
authors.initials: MJ
authors.lastname: Kim
authors.affiliation: Imperial College Renal and Transplant Centre, Hammersmith Hospital, Imperial College London, London, UK.
authors.forename: Clare M
authors.initials: CM
authors.lastname: Turner
authors.affiliation: Imperial College Renal and Transplant Centre, Hammersmith Hospital, Imperial College London, London, UK.
authors.forename: Reiko
authors.initials: R
authors.lastname: Hewitt
authors.affiliation: Imperial College Renal and Transplant Centre, Hammersmith Hospital, Imperial College London, London, UK.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Smith
authors.affiliation: Imperial College Renal and Transplant Centre, Hammersmith Hospital, Imperial College London, London, UK.
authors.forename: Gurjeet
authors.initials: G
authors.lastname: Bhangal
authors.affiliation: Imperial College Renal and Transplant Centre, Hammersmith Hospital, Imperial College London, London, UK.
authors.forename: Charles D
authors.initials: CD
authors.lastname: Pusey
authors.affiliation: UCL Centre for Nephrology, University College London, London, UK.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Unwin
authors.affiliation: Imperial College Renal and Transplant Centre, Hammersmith Hospital, Imperial College London, London, UK.
authors.forename: Frederick W K
authors.initials: FW
authors.lastname: Tam
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D024042:Collagen Type I / Q000378:metabolism; D055513:Connective Tissue Growth Factor / Q000235:genetics; D004195:Disease Models, Animal; D005355:Fibrosis / Q000473:pathology; D007124:Immunoenzyme Techniques; D007668:Kidney / Q000378:metabolism / Q000473:pathology*; D008264:Macrophages / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009395:Nephritis, Interstitial / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D058848:Receptors, Purinergic P2X4 / Q000502:physiology*; D016212:Transforming Growth Factor beta / Q000235:genetics; D014517:Ureteral Obstruction / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*
chemical_list: C526318:CCN2 protein, mouse; D024042:Collagen Type I; D012333:RNA, Messenger; D058848:Receptors, Purinergic P2X4; D016212:Transforming Growth Factor beta; D055513:Connective Tissue Growth Factor
keywords: P2X4 receptor; TGF-β; connective tissue growth factor; renal fibrosis; unilateral ureteric obstruction